CN1208144C - Gear precision plastic forming process and its forming mould - Google Patents

Abstract

The invention belongs to a gear precision plastic forming process and a forming die thereof. The forming die has a gear-shaped cavity with a profile of a gear part. The gear-shaped cavity has a feed section with an inclined top and root, a sizing section similar to the gear part, and a discharge section with an inclined top and root. The forming process is to put the heated blanks into different gear plastic precision molds in turn, and carry out warm extrusion to form gear blanks, and then process the teeth of the gear blanks by shaping, cold shaping or shaving. The forming process and the forming die thereof have small forming force, good forming quality, high production efficiency and low cost.

Description

Gear Precision Plastic Forming Technology and Its Forming Die

technical field

The invention belongs to a gear precision plastic forming process and a gear precision plastic forming die.

Background technique

The existing gear processing technology mainly adopts the traditional technology, which has been used for many years. The process steps are: blanking - high temperature forging blank - heat treatment - tooth shape and shape cutting processing - (carburizing), quenching, Tempering - Finishing after heat treatment. This process has the following disadvantages: large blank cutting volume, low productivity, low material utilization rate, only 30-50%; large energy consumption, serious environmental pollution; many workpiece turnover times, long production cycle, high production cost; The streamline of the forging structure is cut off and the structure is coarse, which reduces the mechanical properties of the product; it is difficult to process new gears such as backlash-free transmission gears and non-cylindrical gears. The existing gear precision forming process basically adopts the closed upsetting forming method. The gear precision plastic forming die used has a straight tooth profile and inner cavity tooth profile, which can only be used for small modulus, small outer diameter and small thickness. Gears, this forming process is mainly used for the forming of small modulus, short tooth profile and small diameter gears. When used to manufacture gears with large modulus, long tooth shape, and large diameter, the forming force and demoulding force are large, the life of the mold is short, the tooth shape is difficult to fill, and the accuracy of the tooth shape cannot be guaranteed. The above-mentioned disadvantages become more obvious as the diameter increases.

Contents of the invention

The purpose of the present invention is to provide a gear precision plastic forming process with small forming force, good forming quality, high production efficiency and low cost and the gear precision plastic forming die.

The first step of the gear plastic precision forming scheme of the present invention is to replace the high-temperature forging blank in the traditional gear processing technology with warm extrusion forming, and form a gear close to the shape of the gear part in the warm extrusion forming die with a taper The blank, and then carry out precision forming or precision machining of the tooth profile, so that the tooth profile can reach the required dimensional accuracy and surface roughness of the gear parts. The precision forming or precision machining of tooth shape mainly includes the following types. One is to shave the gear blank with a gear shaving machine; the other is to cold squeeze and shape the gear blank in a cold shaping die with a taper. For Gears with low precision requirements, such as gears with a precision not higher than IT7 grade, can meet the precision requirements. For gears with high precision requirements, such as gears with higher than IT7 grade, the teeth are shaved after cold shaping; the third is to push the gear blank at a temperature After shaping, it is cold shaped. For high-precision gears, the teeth should be shaved or ground.

The precision plastic forming mold for gears of the present invention has a mold body, and the mold body has a gear-shaped cavity that communicates with two ends in the shape of a gear part, and tooth-shaped grooves corresponding to the tooth profile of the gear part are distributed inside the gear-shaped cavity. , the gear-shaped cavity has a feed section on the feed side, which is characterized in that: the angle between the addendum of the feed section and the axis of the gear-shaped cavity is called the addendum axial diversion angle β1 in this application document, and β1 is greater than zero is 0.5-30°, and the included angle between the side surface of the inner tooth in the feed section and the symmetrical plane of the inner tooth is not zero, which is called the feed radial split angle α1 in this application document, and α1 is 0.5-30°.

The gear precision plastic forming die of the present invention has four kinds of first-stage warm extrusion forming dies, second-stage warm extrusion forming dies, pushing shaping dies and cold shaping dies.

The tooth tip axial conduction angle β1 of the first-stage warm extrusion die is 0.5-30°, and the tooth profile area on the discharge side of the gear-shaped cavity is 5% to 40% larger than the required tooth profile area of the gear part. The tooth profile area of the gear blank formed by grade temperature extrusion is 5% to 40% larger than that required by the gear parts.

The two-stage warm extrusion die has a certain diameter section and an outwardly expanded discharge section. The discharge section is on the discharge side, and the shape of the fixed diameter section of the gear-shaped cavity is similar to that of the gear parts. The tooth shape groove corresponding to the tooth shape of the gear part, the tooth shape in the sizing section is a straight tooth shape similar to the tooth shape of the gear part, and the axial diversion angle β1 of the tooth top of the feed section is 0.5-30° , the angle between the dedendum of the feed section and the axis of the gear cavity is called the dedendum axial diversion angle β2 in this application document, β2≥β1, generally β2 is 0-5° larger than β1, and the radial direction of the feed section The split angle α1 is 0.5-30°; the tooth shape of the sizing section, that is, the tooth shape of the gear blank after two-stage warm extrusion is larger than the tooth shape required by the gear part by a, and a is warm extrusion. The margin, the range of a is generally 0.8-6mm. The tooth profile area of the sizing section, that is, the tooth profile area of the gear blank formed by two-stage warm extrusion is 5% to 40% larger than the tooth profile area required by the gear parts. Make the formed gear blank close to the requirements of the gear parts; the angle between the tooth top of the discharge section and the axis of the gear cavity is called the tooth top axial retraction angle γ1 in this application document, γ1 is greater than zero, and γ1 is 0.5-30 °, the angle between the dedendum of the discharge section and the axis of the gear cavity is called the dedendum axial withdrawal angle γ2 in this application document, and the dedendum axial withdrawal angle γ2 only needs to be greater than zero, and the internal gear of the discharge section The included angle between the side surface and the symmetric plane of the internal teeth is not zero, which is called the ejection radial split angle α2 in this application document, α2 is greater than zero, and the length of the discharge section is generally 5-50 mm.

The push shaping die has a certain diameter section and an outwardly expanding discharge section, the discharge section is on the discharge side, and the shape of the fixed diameter section of the gear cavity is similar to that of the gear parts. The tooth shape corresponding to the tooth shape groove, in order to improve the accuracy of pushing and shaping, the tooth shape in the fixed diameter section is a straight tooth shape similar to the tooth shape of the gear part, and the tooth top axial diversion angle β1 of the feed section is 0.5 -30°, the dedendum axial diversion angle β2 of the feed section, β2≥β1, generally β2 is 0-5° larger than β1, and the radial diversion angle α1 of the feed section is 0.5-30°; in the sizing section The tooth shape of the gear blank after pushing and shaping is larger than the tooth shape required by the gear part by b, b is the pushing and shaping allowance, the range of b is generally 0.1-3.5mm, and the tooth shape area of the sizing section That is, the tooth profile area of the gear blank after pushing and shaping is 5% to 30% larger than the tooth profile area required by the gear part; the tooth tip axial retraction angle γ1 of the discharge section is 0.5-30°, and the The dedendum axial withdrawal angle γ2, the dedendum axial withdrawal angle γ2 is greater than zero, the radial diversion angle α2 of the discharge section is greater than zero, and the length of the discharge section is 5-50mm.

The cold shaping die has a certain diameter section and an outwardly expanding discharge section, the discharge section is on the discharge side, and the shape of the fixed diameter section of the gear cavity is similar to that of the gear parts. The tooth shape corresponding to the tooth shape groove, the tooth shape in the sizing section is the same or similar to the tooth shape of the gear part, and the tooth top axial diversion angle β1 of the feed section is 0.5-30°, The dedendum axial diversion angle β2 of the feeding section, β2≥β1, generally β2 is 0-5° larger than β1, and the radial diversion angle α1 of the feeding section is 0.5-30°; the tooth profile of the sizing section is cold The tooth shape of the gear blank after shaping is larger than the tooth shape required by the gear part by c, c is the cold shaping allowance, the range of c is 0.0-2.5mm, and the c of the last cold shaping die for multiple cold shaping is 0.0 -0.45mm, the tooth profile area of the sizing section, that is, the tooth profile area of the gear blank after cold shaping is 0 to 20% larger than the tooth profile area required by the gear part; the tooth top of the discharge section is axially ejected Angle γ1 is 0.5-30°, it is enough that the tooth root axial withdrawal angle γ2 of the discharge section is greater than zero, the radial diversion angle α2 of the discharge section is greater than zero, and the length of the discharge section is 5-50mm.

For a group of two-stage warm extrusion forming dies, pushing shaping dies, and cold shaping dies for gears with a large modulus, any of the above three forming dies can be used several times, generally two or three. Die with successively decreasing shaping margins. For example, the warm extrusion forming allowances a of the two warm extrusion forming dies are 5 mm and 3 mm respectively, the pushing shaping allowance b of the two pushing shaping dies are 2 mm and 1 mm respectively, and the two cold shaping dies The cold shaping margin c is 0.5mm and 0.05mm respectively.

The γ1 of the two-stage warm extrusion forming die, pushing shaping die and cold shaping die is preferably equal to γ2. The discharge section of the two-stage warm extrusion die, push shaping die, and cold shaping die is preferably processed by a wire cutting machine tool. The direction of the cutting line is consistent with the generatrix of the tooth shape of the discharge section. The processed tooth The top axial withdrawal angle γ1 is equal to the dedendum axial withdrawal angle γ2, and the withdrawal radial split angle α2 processed in this way meets the requirements of the forming process, and EDM can also be used. It is sufficient that the radial split angle α2 is greater than zero, such as 0.1°, generally 0.5-30°.

In this application document, the tooth shape of the extruded and shaped gear blank is 5% to 40% larger than the tooth shape area of the gear part, which is an approximate estimate and is for reference only, mainly by a , b, c are determined.

The material used for the gear precision plastic forming die is die steel, and the surface roughness of the sizing section is not greater than Ra1.6.

The first feature of the gear precision plastic forming process of the present invention is that it adopts warm extrusion forming.

The steps of the gear precision plastic forming process of the present invention include: the first step is to heat the cut cylindrical blank to 400-1100°C; the second step is to put the heated blank into the warm extrusion forming die, and warm extrusion The gear blank is pressed into a gear blank that is close to the tooth profile of the gear part. The tooth profile area of the gear blank is 5%-40% larger than the tooth profile area required by the gear part. The warm extrusion forming is in the first-stage warm extrusion forming die. The pressure is applied to the upper and lower sides of the cylindrical blank, and then extruded or second-stage warm extrusion is carried out in the die for second-stage warm extrusion. For gears with a large modulus such as gears with a modulus of m=5, After the first-stage warm extrusion forming, the second-stage warm extrusion is carried out, and the billet formed by the first-stage warm extrusion is subjected to equal-area push forming of axial flow and radial diversion in the die of the second-stage warm extrusion forming. , the tooth shape of the gear blank formed by two-stage warm extrusion is larger than the required tooth shape of the gear part by a, a is the warm extrusion forming allowance, and the range of a is 0.8-6mm, and the two-stage warm extrusion Forming can be carried out multiple times in a number of secondary warm extrusion dies with different a, and the warm extrusion forming allowance a of each time decreases successively; the primary warm extrusion forming is to form the circumference of the billet into an arc shape or Straight-line teeth, at the same time change the tooth top from the required straight line to arc shape, the resistance of the metal flowing into the tooth cavity is reduced and the metal does not need to completely fill the tooth cavity, so the forming force is reduced and the service life of the mold is improved; The third step is to carry out precision forming and cutting of the tooth profile, so that the tooth profile can reach the dimensional accuracy and surface roughness required by the gear parts.

There are three types of precision forming or cutting of tooth profile:

The first one is to cool the gear blank to room temperature and then cut it, turn the end face, turn the center hole, pull the spline, shave or grind the teeth, so that the tooth shape can meet the required dimensional accuracy and surface roughness of the gear parts.

The second step is as follows: after the gear blank is cooled to room temperature, surface treatment is performed to remove the surface oxide layer and impurities; lubrication treatment; cold shaping, the gear blank is loaded into the feed side of the cold shaping die and applied on the gear blank. The pressure pushes the gear blank from the discharge side, and the tooth profile of the gear blank after cold shaping is larger than the tooth profile required by the gear part by c, c is the cold shaping allowance, c is 0.0-2.5mm, after cold shaping The tooth shape area of the gear blank is 0 to 20% larger than the tooth shape area required by the gear parts, and the cold shaping can be carried out several times in a number of cold shaping dies ranging from c, each cold shaping allowance c decreases in turn, and the last cold shaping allowance c is 0.02-0.45mm; cutting processing, turning the end face, turning center hole, drawing spline, and gear parts with high precision should be shaving or grinding to make the teeth The shape can reach the required dimensional accuracy and surface roughness of gear parts. a>c of the gear precision plastic forming die used.

The third step is as follows: put the gear blank formed by warm extrusion upside down while it is hot, put it into the feeding side of the pushing and shaping die for pushing and shaping, apply pressure on the gear blank, and push the gear blank from the discharge The tooth shape of the gear blank after pushing and shaping is larger than the required tooth shape of the gear part by b, b is the pushing and shaping allowance, and the range of b is generally 0.1-3.5mm. The value of b increases with the increase of the modulus. Large and large, the tooth shape area of the gear blank after pushing and shaping is 5% to 30% larger than the tooth shape area required by the gear parts. The pushing and shaping margin b of the second step decreases in turn: cool the gear blank after pushing and shaping to room temperature for surface treatment, remove the surface oxide layer and impurities; carry out lubrication treatment; cold shaping, the gear blank is loaded into the feeding material of the cold shaping die The side exerts pressure on the gear blank to push the gear blank from the discharge side. The tooth shape of the cold shaped gear blank is larger than the tooth shape required by the gear part by c on one side. c is the cold shaping allowance, and the range of c is 0.0-2.5mm, the tooth shape area of the gear blank after cold shaping is 0 to 20% larger than the tooth shape area required by the gear parts, and the cold shaping can be performed multiple times in a number of cold shaping dies ranging from c , the cold shaping allowance c decreases successively each time, and the last cold shaping allowance c is 0.02-0.45mm; cutting processing, turning end faces, turning center holes, and drawing splines, for high-precision gear parts such as higher than Gears with IT7 precision should be shaved or ground to make the tooth shape meet the required dimensional accuracy and surface roughness of the gear parts. a>b>c of the gear precision plastic forming die used.

Lubricants, such as oil graphite lubricants, are used in the process of first-stage warm extrusion, second-stage warm extrusion, push shaping, and cold shaping.

In the two-stage warm extrusion forming, pushing shaping, and cold shaping processes, the gear blank is radially divided and axially diverted. The tooth grooves of the forming die and the shaping die have a certain length of diversion taper, see Figure 16 and Figure 17, the gear blank or blank whose outer diameter is larger than the dedendum circle moves downward along the diversion cone under the action of the axial force P During the movement, there is a radial flow of metal at the same time, so that the excess metal at the root of the tooth flows to the top of the tooth, so that the tooth shape is filled. The metal deformation mainly occurs in the tooth-shaped part, so the extrusion force is small, the force of the mold is good, and the service life is long.

Heat treatment of the above-mentioned gears that meet the required dimensional accuracy and surface roughness of gear parts. For medium-high carbon steel gears, it can be directly quenched, and the processed gears can be heated to 800°C to 900°C for quenching. For low-carbon steel or low-carbon alloys Carburizing and quenching of steel gears, the processed gears are put into a carburizing furnace and heated to 900°C to 1000°C for carburizing, and then cooled and quenched after reaching the required thickness of the carburized layer.

The gear precision plastic forming die of the present invention has the tooth top axial diversion angle β1 and the radial diversion angle α1 in the feeding section, the forming force is small, and the two-stage warm extrusion forming die, push shaping die, and cold shaping Dies, all have root axial conduction angle β2, which can avoid tooth root scratches and facilitate tooth root forming, especially two-stage warm extrusion forming dies, push shaping dies, and cold shaping dies. Both the feed section and the discharge section have the axial withdrawal angle γ1 of the tooth top, the axial withdrawal angle γ2 of the tooth root, and the radial diversion angle α2, which not only facilitates the mold withdrawal but also avoids scratching the gear parts, improving precision plastic forming The precision of the gear and the reduction of surface roughness, the precision of the gear parts after cold shaping can reach IT8 level or even IT7 level.

The gear precision plastic forming process of the present invention adopts a warm-cold compound forming process, and the deformation amount of warm forming and cold forming can be reasonably distributed easily. Due to the small axial pressure required for warm extrusion forming, more than 85% of the deformation is obtained by warm extrusion during gear forming, so that the shape of the blank is close to the size required by the gear parts; the cold extrusion force is large, Cold shaping only causes a small plastic deformation of the metal, mainly to improve the dimensional accuracy of the gear tooth shape and reduce the surface roughness. Therefore, it can reduce the gear forming force and ensure the dimensional accuracy and surface roughness of the gear parts. Warm forming is achieved by controlling the deformation in several times according to the specific shape or requirements of the product once heated. During the first warm extrusion deformation, the billet temperature is higher, the deformation resistance is smaller, and the deformation amount can be obtained larger, and the deformation amount of each subsequent warm forming is appropriately reduced. By adopting this method, several stations can be set up on one hydraulic press to work at the same time, and different working steps of a gear part can be completed simultaneously on one hydraulic press, and can also be completed on other forming equipment, forming a flow operation and improving production efficiency. For example, a multi-station CNC fast hydraulic press with a hydraulic machine power source can control the maximum forming force on each station according to the force required by each station, so that the metal on each station can fill the cavity without The mold is damaged due to excessive force, and the service life of the mold is improved. During the pushing process, the workpiece enters from the feed side of the mold and pushes out from the discharge side, which solves the problem of ejection during gear extrusion.

Compared with the traditional mechanical cutting process after high-temperature forging, the gear precision plastic forming process of the present invention has the following advantages:

1. Reduce the cutting allowance, save raw materials and energy;

2. Due to the integrity of the forging streamline and the refinement of the structure, the fatigue strength of the gear is improved;

3. It can be widely used in gears with various complex tooth shapes, such as cycloidal, Novikov gears and non-circular gears;

4. Reduced gear production cost;

5. It is convenient to organize continuous production, shorten the production cycle and improve productivity

6. Reduce the dependence on special machine tools such as gear shaping machines, and have low requirements for workers' technical level;

Compared with the existing gear precision plastic forming process, it has the following advantages:

1. During the forming process, the blank flows radially and axially, which significantly reduces the gear forming force, and can form gear parts with large modulus, long tooth shape and large diameter, such as modulus m=6, long tooth shape 50mm in length and Φ300mm in diameter, the tooth shape is well filled; 2. Push forming is adopted, and the gear is easy to demould after forming.

Description of drawings

The specific steps and the gear precision plastic forming die of the present invention will be described in detail below in conjunction with the embodiments and accompanying drawings, but the gear precision plastic forming process and the gear precision plastic forming die of the present invention are not limited to the following embodiments.

Fig. 1 is the top view of the one-stage warm extrusion die of the present invention.

Fig. 2 is a sectional view along line A-A in Fig. 1 .

Fig. 3 is a view along the direction A in Fig. 2 .

Fig. 4 is a top view of the two-stage warm extrusion die.

Fig. 5 is a sectional view along line B-B in Fig. 4 .

Fig. 6 is a view along the B direction in Fig. 5 .

Fig. 7 is a top view of the push shaping die.

Fig. 8 is a sectional view along line C-C in Fig. 7 .

Fig. 9 is a top view of the cold shaping die.

Fig. 10 is a sectional view taken along line D-D in Fig. 9 .

The view along the direction C in FIG. 8 and the view along the direction D in FIG. 10 are the same as those in FIG. 6 , so they are omitted.

1. Die body 2. Gear-shaped cavity 3. Tooth-shaped groove

4. Discharge side 5. Feed section 6. Die body

7. Gear-shaped cavity 8. Tooth-shaped groove 9. Feed section

10. Calibration section 11. Discharge section 12. Die body

13. Gear-shaped cavity 14. Tooth-shaped groove 15. Feed section

16. Calibration section 17. Discharge section 18. Die body

19. Gear-shaped cavity 20. Tooth-shaped groove 21. Feed section

22. Calibration section 23. Discharge section 24. Toothed straight groove

Fig. 11 is an axial sectional view of a gear part.

Fig. 12 is a gear shaft hole diagram of the gear part in Fig. 11.

Fig. 13 is a schematic cross-sectional view along the axial direction of the gear blank for one-stage warm extrusion.

Figure 14 is a schematic diagram of the comparison between the discharge side of the tooth-shaped groove of the first-stage warm extrusion forming die and the tooth profile of the gear part.

Fig. 15 is a schematic cross-sectional view of the gear blank along the axial direction of the two-stage warm extrusion.

Fig. 16 is a schematic diagram of axial flow diversion and radial flow diversion of the blank during two-stage warm extrusion forming, push shaping, and cold shaping.

Fig. 17 is a schematic diagram of the metal flow in the direction of axial flow and radial diversion of the blank during two-stage warm extrusion forming, push shaping, and cold shaping, that is, a view along the direction F in Fig. 16 .

Fig. 18 is a schematic cross-sectional view of the push shaping along the axial direction of the gear blank.

Fig. 19 is a schematic cross-sectional view of the cold shaping along the axial direction of the gear blank.

Figure 20 is a schematic diagram of the comparison between the tooth profile of the gear and the tooth profile of the gear part after cold shaping.

The scales of the above figures are not consistent.

25. Gear parts 26. Teeth 27. Gear shaft hole

28. Pressure die 29. Billet 30. Primary warm extrusion die

31. Top block 32. Pressure die 33. Two-stage warm extrusion die

34. Gear blank 35. Backing plate 36. Pressure die 37. Pushing and shaping die 38. Backing plate

39. Pressure die 40. Cold shaping die 41. Backing plate 42. Teeth after cold shaping

The cross-sections of the pressure dies 28, 32, 36, 39 and the top block 31 in each of the following embodiments are similar to the gear parts.

Detailed ways

The gear precision plastic forming die of the present invention has four kinds of first-stage warm extrusion forming dies, second-stage warm extrusion forming dies, pushing shaping dies and cold shaping dies.

The first-stage warm extrusion die embodiment is shown in Fig. 1, Fig. 2, and it has a die body 1, has the gear-shaped cavity 2 that the two ends of profile are the shape of a gear part communicates in the die body 1, in the gear-shaped cavity 2 The tooth-shaped groove 3 corresponding to the tooth shape of the gear part is distributed on the inner side. The gear-shaped cavity 2 has only the feed section 5, and the axial diversion angle β1 of the addendum 5 of the feed section 5 is 0.5-30°, such as 10°, and the radial direction The split angle α1 is 0.5-30°, such as 10°, see Figure 3, the tooth profile area of the discharge side of the first-stage warm extrusion die is 5% to 40% larger than the tooth profile area required by the gear parts, such as 15 %.

Two-stage warm extrusion die embodiment of the present invention is shown in Fig. 4, Fig. 5, Fig. 6, and it has a die body 6, has the gear-shaped chamber 7 that the two ends that outline is the shape of a gear part communicate with each other at the die body 6, In the gear-shaped cavity 7, there are feeding section 9, sizing section 10 and outwardly expanding discharge section 11 successively. Tooth shape. Its addendum axial conduction angle β1 is 1-30° such as 8°, the dedendum axial conduction angle β2 is 0-5° greater than β1 such as 4°, and the radial diversion angle α1 is 0.5-30° such as 5° °. The axial retraction angle γ1 of the addendum and the axial retraction angle γ2 of the tooth root are 0.5-30° such as 4°, the radial split angle α2 of the retraction is 0.5-30° such as 5°, and the length of the discharge section is generally 5° -50mm. The tooth profile area of the sizing section 10, that is, the area of the gear blank formed by two-stage warm extrusion, is 5% to 40% such as 15% larger than the required tooth profile area of the gear part. The range of the secondary warm extrusion forming allowance a is 0.8-6mm such as 2.5mm.

Push shaping die embodiment of the present invention is shown in Fig. 7, Fig. 8, and it has a die body 12, has the gear-shaped cavity 13 that the two ends of profile are the shape of gear parts communicates at the die body 12, in the gear-shaped cavity 13 successively There is a feed section 15, a sizing section 16 and an outwardly expanding discharge section 17. The tooth profile of the toothed groove 14 at the sizing section 16 is a straight tooth profile similar to the tooth profile of the gear part. Its addendum axial conduction angle β1 is 1-30° such as 8°, the dedendum axial conduction angle β2 is 0-5° greater than β1 such as 4°, and the radial diversion angle α1 is 0.5-30° such as 5° °. The axial retraction angle γ1 of the addendum and the axial retraction angle γ2 of the tooth root are 0.5-30° such as 4°, the radial split angle α2 of the retraction is 0.5-30° such as 5°, and the length of the discharge section is generally 5° -50mm. The tooth profile area of the sizing section 16 is 5% to 30% such as 15% larger than the tooth profile area required by the gear part after being pushed and shaped. The range of the pushing and shaping allowance b is 0.1-3.5 mm, such as 0.2 mm.

The cold shaping die embodiment of the present invention is shown in Fig. 9, Fig. 10, and it has a die body 18, has the gear-shaped cavity 19 that the two ends that profile is the shape of a gear part communicates in the die body 18, successively in the gear-shaped cavity 19 There is a feed section 21, a sizing section 22 and an outwardly expanding discharge section 23. The tooth shape of the toothed groove 24 in the sizing section 22 is a toothed straight groove 24 that is the same as or similar to the tooth shape of the gear part. . Its addendum axial conduction angle β1 is 1-30° such as 8°, the dedendum axial conduction angle β2 is 0-5° greater than β1 such as 4°, and the radial diversion angle α1 is 0.5-30° such as 5° °. The axial retraction angle γ1 of the addendum and the axial retraction angle γ2 of the tooth root are 0.5-30° such as 4°, the radial split angle α2 of the retraction is 0.5-30° such as 5°, and the length of the discharge section is generally 5° -35mm. The tooth profile area of the sizing section, that is, the area of the gear blank after cold shaping is 0 to 20% larger than the tooth profile area required by the gear part. The range of cold shaping margin c is 0.0-2.5mm. The c of the last cold shaping die is 0.0-0.45mm, such as 0.1mm.

The first embodiment of the gear precision plastic forming process of the present invention is the forming of the gear parts shown in Figure 11 and Figure 12. Its tooth shape is an involute line tooth shape. In this embodiment, the precision is IT7, and the tooth surface is rough. The degree is Ra1.6, the modulus is 3, the number of teeth is 21, the gear height is 31mm, the material is 20CrMnTi (other gear materials can also be used, such as 20Cr, 20CrMo, 20CrMnMo, 20MnTiB, 20MnVB, 45, 40Cr), the blank is Φ65 ×32mm. The implementation steps are as follows:

1. Heat the cut cylindrical blank to 400-1100°C in an intermediate frequency induction furnace, and heat it to 850°C in this embodiment:

2. First-stage warm extrusion forming. Put the heated billet 29 into the first-stage warm extrusion die 30 shown in FIG. 13, that is, the first-stage warm extrusion die shown in FIG. The hydraulic press (also can be carried out on other hydraulic presses with a tonnage greater than 2500KN) is carried out by the pressure die 28 from the top of the blank 29, and the top block 31 is simultaneously carried out warm extrusion from below, and the gear shaft hole 27 is extruded without being squeezed through. When extruding, use oil agent graphite lubricant, stop extruding after the extrusion force reaches 2500KN, and eject the workpiece. The tooth profile area of the gear blank formed by the first-stage warm extrusion is 25% larger than the tooth profile area required by the gear parts, see Figure 14;

3. Two-stage warm extrusion forming, as shown in Figure 15, put the extruded gear blank 29 from the feed side into the second-stage warm extrusion die 33 immediately while it is hot, that is, the second-stage warm extrusion shown in Figure 4 The forming die is formed by two-stage warm extrusion with equal area of axial flow and radial flow in YA32-150 hydraulic press, so as to reduce the temperature drop of the blank as much as possible. The blank 29 is pushed and formed under the thrust of the pressing die 32, and pushed out from the discharge side of the two-stage warm extrusion die 33 to form a gear blank 34. During the pushing process, the gear blank 29 is axially guided. To shunt the flow, see Figure 16 and Figure 17 for the process. In this embodiment, the two-stage warm extrusion die 33 has an axial diversion angle β1 at the top of the tooth, 8°, an axial diversion angle β2 at the root, which is 4° greater than β1, and a radial diversion angle α1, which is 5°. The axial retraction angle γ1 of the addendum and the axial retraction angle γ2 of the tooth root are 4°, the radial split angle α2 of the retraction is 5°, and the length of the discharge section is 8mm. The allowance a of the secondary warm extrusion is 1.4mm, and the value of a makes the tooth profile area of the gear blank 34 equal to the tooth profile area of the gear blank 29 after the primary warm extrusion. Oil graphite is used as lubricant when extruding.

4. Pushing and shaping, as shown in Figure 18, the gear blank 34 obtained after the above-mentioned two-stage warm extrusion is turned upside down and the temperature is reduced as much as possible, and then put into the pushing and shaping die 37 from the feed side while it is hot In the pushing and shaping die shown, the pushing and shaping is carried out on a YA32-150 hydraulic press, and the gear blank 34 is pushed and formed under the thrust of the pressing die 36 and pushed out from the discharge side of the pushing and shaping die 37 . In this embodiment, the axial diversion angle β1 of the addendum tip 37 is 8°, the axial diversion angle β2 of the tooth root is 4° larger than β1, and the radial split angle α1 is 5°. The axial retraction angle γ1 of the addendum and the axial retraction angle γ2 of the tooth root are 4°, the radial split angle α2 of the retraction is 5°, and the length of the discharge section is 14mm. The area of the gear blank after pushing and shaping is 10% larger than the tooth profile area required by the gear parts. Push shaping allowance b is 0.6mm.

5. Cool the gear blank 34 obtained by pushing and shaping to room temperature in air;

6. Surface treatment and lubrication treatment, the gear blank 34 cooled to room temperature is subjected to sand blasting-acid washing-alkali washing-water washing-phosphating-saponification treatment;

7. Cold shaping, as shown in Figure 19, put the gear blank 34 processed in process 6 from the feed side into the cold shaping die 40, that is, the cold shaping die shown in Figure 9, and perform cold pushing on a 1000KN hydraulic press Forming, the pressure die 39 pushes the gear blank 34 from the feed side through the sizing section from the discharge side. The addendum axial flow angle β1 of the cold shaping die 40 of this embodiment is 8°, and the dedendum axial direction The diversion angle β2 is 2° larger than β1, and the radial diversion angle α1 is 1°. The axial retraction angle γ1 of the addendum, the axial retraction angle γ2 of the tooth root are 3°, the radial split angle α2 of the retraction is 3°, and the length of the discharge section is 13mm. The area of the gear blank after cold shaping is 5% larger than the tooth profile area required by the gear parts. The allowance c for cold shaping is 0.06mm, and c is used as the allowance for shaving teeth;

8. Cut and process the two ends of the turning gear blank 34, drill the gear shaft hole 27, pull the spline, and shave the teeth to make the tooth shape meet the required dimensional accuracy and surface roughness of the part;

9. Heat treatment means carburizing and quenching. Put the processed gear into a carburizing furnace and heat it to 980°C for carburizing. After reaching the required thickness of the carburized layer, cool down to about 850°C and then quench.

The gears of medium and high carbon steel can be quenched directly, such as 45# steel.

The steps of the current manufacturing process of gear part 25 are: forging gear blank, gear blank normalizing, drilling, turning both ends, spline drawing, finish turning outer circle, finish turning both ends, hobbing, chamfering, shaving , heat treatment.

The second embodiment of the gear precision plastic forming process of the present invention is to form the gear parts shown in Figure 11 and Figure 12. Its tooth shape is an involute tooth shape, the precision is IT7, and the surface roughness of the tooth is Ra1.6 , The modulus is 2.5, the number of teeth is 25, the gear height is 30mm, the material is 20CrMnTi, and the blank is Φ65×32mm. The implementation steps are as follows:

1. Heating the cut cylindrical blank to 400-1100°C in an intermediate frequency induction furnace, and heating to 850°C in this embodiment;

2. First-stage warm extrusion forming. Put the heated billet 29 into the first-stage warm extrusion die 30 shown in FIG. Do not squeeze through. Stop extrusion after the extrusion force reaches 2500KN, and eject the workpiece. The tooth profile area of the gear blank formed by the first-stage warm extrusion is 15% larger than the tooth profile area required by the gear parts, see Figure 14;

3. Two-stage warm extrusion forming, as shown in Figure 15, put the extruded gear blank 29 into the secondary warm extrusion forming die 33 from the feed side immediately while it is hot, and perform two-stage warm extrusion on a YA32-150 hydraulic press Press forming to minimize the drop in blank temperature. The blank 29 is pushed and formed under the thrust of the pressing die 32, and is pushed out from the discharge side of the two-stage warm extrusion die 33 to form a gear blank 34. In this embodiment, the two-stage warm extrusion die 33 is The addendum axial conduction angle β1 is 8°, the dedendum axial conduction angle β2 is 4° larger than β1, and the radial diversion angle α1 is 5°. The axial retraction angle γ1 of the addendum and the axial retraction angle γ2 of the tooth root are 4°, the radial split angle α2 of the retraction is 5°, and the length of the discharge section is 8mm. The margin a of the secondary warm extrusion is 0.8 mm, and the value of a makes the tooth profile area of the gear blank 34 equal to the tooth profile area of the gear blank 29 after the primary warm extrusion.

4. The gear blank 34 obtained by warm extrusion is cooled to room temperature in air:

5. Surface treatment and lubrication treatment, the gear blank 34 cooled to room temperature is subjected to sand blasting-acid washing-alkali washing-water washing-phosphating-saponification treatment;

6. Cold shaping, as shown in Figure 19, put the gear blank 34 processed in the process 5 into the cold shaping die 40 from the feed side, and carry out cold extrusion molding on a 1000KN hydraulic press, and the pressing die 39 pushes the gear blank 34 by The feed side is pushed out from the discharge side of the sizing section. The axial conduction angle β1 of the addendum 40 of the cold shaping die 40 of this embodiment is 8°, the axial conduction angle β2 of the dedendum is 2° greater than β1, and the radial The split angle α1 is 1°. The axial retraction angle γ1 of the addendum, the axial retraction angle γ2 of the tooth root are 3°, the radial split angle α2 of the retraction is 3°, and the length of the discharge section is 13mm. The area of the gear blank after cold shaping is 5% larger than the tooth profile area required by the gear parts. The allowance c for cold shaping is 0.04mm, and c is used as the allowance for shaving teeth;

Cutting process, heat treatment are identical with embodiment one.

The third embodiment of the gear precision plastic forming process of the present invention is the forming of the gear parts shown in Figure 11 and Figure 12. Its tooth shape is an involute line tooth shape. In this embodiment, the precision is IT7, and the tooth surface is rough. The degree is Ra1.6, the modulus is 2.5, the number of teeth is 20, the gear height is 31mm, the material is 20CrMnTi (other gear materials can also be used, such as 20Cr, 20CrMo, 20CrMnMo, 20MnTiB, 20MnVB, 45, 40Cr), the blank is Φ53 ×32mm. The implementation steps are as follows:

1. Heating the cut cylindrical blank to 400-1100°C in an intermediate frequency induction furnace, and heating to 850°C in this embodiment;

2. First-stage warm extrusion forming. Put the heated billet 29 into the first-stage warm extrusion die 30 shown in FIG. . Stop extrusion after the extrusion force reaches 2300KN, and eject the workpiece. The tooth profile area of the gear blank formed by the first-stage warm extrusion is 25% larger than the tooth profile area required by the gear parts, see Figure 14;

3. Pushing and shaping, as shown in Figure 18, the gear blank 34 obtained after the above-mentioned first-stage warm extrusion is turned upside down, and the temperature is reduced as much as possible. The YA32-150 hydraulic press carries out pushing and shaping, and the gear blank 34 is pushed and formed under the thrust of the pressing die 36, and is pushed out from the discharge side of the pushing and shaping concave die 37. In this embodiment, the axial diversion angle β1 of the addendum tip 37 is 8°, the axial diversion angle β2 of the tooth root is 4° larger than β1, and the radial split angle α1 is 5°. The axial retraction angle γ1 of the addendum and the axial retraction angle γ2 of the tooth root are 4°, the radial split angle α2 of the retraction is 5°, and the length of the discharge section is 14mm. The area of the gear blank after pushing and shaping is 15% larger than the tooth profile area required by the gear parts. Push shaping allowance b is 0.8mm.

4. Cool the gear blank 34 obtained by pushing and shaping to room temperature in air;

5. Surface treatment and lubrication treatment, the gear blank 34 cooled to room temperature is subjected to sand blasting-acid washing-alkali washing-water washing-phosphating-saponification treatment;

6. Cold shaping, as shown in Figure 19, put the gear blank 34 processed in the process 5 into the cold shaping die 40 from the feed side, and carry out cold extrusion forming on a 1000KN hydraulic press, and the pressing die 39 presses the gear blank 34 Pushed out from the feed side through the sizing section and from the discharge side, the tooth tip axial conduction angle β1 of the cold shaping die 40 of this embodiment is 6°, and the dedendum axial conduction angle β2 is 2° greater than β1, The radial split angle α1 is 6°. The axial retraction angle γ1 of the addendum, the axial retraction angle γ2 of the tooth root are 3°, the radial split angle α2 of the retraction is 3°, and the length of the discharge section is 13mm. The area of the gear blank after cold shaping is 5% larger than the tooth profile area required by the gear parts. The allowance c for cold shaping is 0.04mm, and c is used as the allowance for shaving teeth;

Cutting process, heat treatment are identical with embodiment one.

The fourth embodiment of the gear precision plastic forming process of the present invention is the forming of the gear parts shown in Figure 11 and Figure 12. Its tooth shape is an involute line tooth shape. In this embodiment, the precision is IT7, and the tooth surface is rough. The degree is Ra1.6, the modulus is 2, the number of teeth is 30, the gear height is 31mm, the material is 20CrMnTi, and the blank is Φ63×32mm. The implementation steps are as follows:

1. Heating the cut cylindrical blank to 400-1100°C in an intermediate frequency induction furnace, and heating to 850°C in this embodiment;

2. First-stage warm extrusion forming. Put the heated billet 29 into the first-stage warm extrusion die 30 shown in FIG. Do not squeeze through. Stop extrusion after the extrusion force reaches 2500KN, and eject the workpiece. The tooth profile area of the gear blank formed by the first-stage warm extrusion is 20% larger than the tooth profile area required by the gear parts, see Figure 14;

3. Cool the gear blank 34 obtained by warm extrusion to room temperature in air;

4. Surface treatment and lubrication treatment, the gear blank 34 cooled to room temperature is subjected to sand blasting-acid washing-alkali washing-water washing-phosphating-saponification treatment;

5. Cold shaping, as shown in Figure 19, put the gear blank 34 processed in process 4 into the cold shaping die 40 from the feed side, and carry out cold extrusion forming on a 1500KN hydraulic press, and the pressing die 39 presses the gear blank 34 Pushed out from the feed side through the sizing section and from the discharge side, the tooth tip axial flow angle β1 of the cold shaping die 40 of this embodiment is 8°, and the dedendum axial flow angle β2 is 2° larger than β1, The radial split angle α1 is 1°. The axial retraction angle γ1 of the addendum, the axial retraction angle γ2 of the tooth root are 3°, the radial split angle α2 of the retraction is 3°, and the length of the discharge section is 13mm. The area of the gear blank after cold shaping is 8% larger than the tooth profile area required by the gear parts. The allowance c for cold shaping is 0.07mm, and c is used as the allowance for shaving teeth;

Cutting process, heat treatment are identical with embodiment one.

The fifth embodiment of the gear precision plastic forming process of the present invention is the forming of the gear parts shown in Figure 11 and Figure 12. Its tooth shape is an involute line tooth shape. In this embodiment, the precision is IT8, and the surface of the tooth is rough The degree is Ra 1.6, the modulus is 3, the number of teeth is 19, the gear height is 31mm, the material is 20CrMnTi (other gear materials can also be used, such as 20Cr, 20CrMo, 20CrMnMo, 20MnTiB, 20MnVB, 45, 40Cr), and the blank is Φ60× 32mm. The implementation steps are as follows:

1. Heating the cut cylindrical blank to 400-1100°C in an intermediate frequency induction furnace, and heating to 850°C in this embodiment;

2. First-stage warm extrusion forming. Put the heated billet 29 into the first-stage warm extrusion die 30 shown in FIG. Do not squeeze through. Stop extrusion after the extrusion force reaches 2500KN, and eject the workpiece. The tooth profile area of the gear blank formed by the first-stage warm extrusion is 25% larger than the tooth profile area required by the gear parts, see Figure 14;

3. Two-stage warm extrusion forming, as shown in Figure 15, put the extruded gear blank 29 into the secondary warm extrusion forming die 33 from the feed side immediately while it is hot, and carry out axial flow guide in YA32-150 hydraulic press The equal-area two-stage warm extrusion forming with radial flow can reduce the temperature drop of the blank as much as possible. The blank 29 is pushed and formed under the thrust of the pressure die 32, and is pushed out from the discharge side of the two-stage warm extrusion die 33 to form a gear blank 34. In this embodiment, the two-stage warm extrusion die 33 is The addendum axial conduction angle β1 is 8°, the dedendum axial conduction angle β2 is 4° larger than β1, and the radial diversion angle α1 is 5°. The axial withdrawal angle γ1 of the addendum, the axial withdrawal angle γ2 of the tooth root are 4°, the radial split angle α2 of the withdrawal is 5°, and the length of the discharge section is 8mm. The allowance a of the secondary warm extrusion is 1.4 mm, and the value of a makes the tooth profile area of the gear blank 34 equal to the tooth profile area of the gear blank 29 after the primary warm extrusion. Oil graphite is used as lubricant when extruding.

4. Pushing and shaping, as shown in Figure 18, the gear blank 34 obtained after the above-mentioned two-stage warm extrusion is turned upside down and the temperature is reduced as much as possible. Put it into the pushing and shaping die 37 from the feed side while it is hot The YA32-150 hydraulic press carries out pushing and shaping, and the gear blank 34 is pushed and formed under the thrust of the pressing die 36, and is pushed out from the discharge side of the pushing and shaping concave die 37. In this embodiment, the axial diversion angle β1 of the addendum tip 37 is 8°, the axial diversion angle β2 of the tooth root is 4° larger than β1, and the radial split angle α1 is 5°. The axial retraction angle γ1 of the addendum and the axial retraction angle γ2 of the tooth root are 4°, the radial split angle α2 of the retraction is 3°, and the length of the discharge section is 14mm. The area of the gear blank after pushing and shaping is 10% larger than the tooth profile area required by the gear part, and the pushing and shaping allowance b=0.6mm.

5. Cool the gear blank 34 obtained by pushing and shaping to room temperature in air;

6. Surface treatment and lubrication treatment, the gear blank 34 cooled to room temperature is subjected to sandblasting-acid washing-alkali washing-water washing-phosphating-saponification treatment;

7. Cold shaping, as shown in Figure 19, put the gear blank 34 processed in the process 6 into the cold shaping die 40 from the feed side, and carry out cold extrusion forming on a 1000KN hydraulic press, and the pressing die 39 presses the gear blank 34 Pushed out from the feed side through the sizing section and from the discharge side, the tooth tip axial flow angle β1 of the cold shaping die 40 of this embodiment is 8°, and the dedendum axial flow angle β2 is 2° larger than β1, The radial split angle α1 is 4°. The axial retraction angle γ1 of the addendum, the axial retraction angle γ2 of the tooth root are 3°, the radial split angle α2 of the retraction is 3°, and the length of the discharge section is 13mm. The area of the gear blank after cold shaping is equal to the tooth profile area required by the gear parts. The margin c of cold shaping is 0.

No gear shaving, other processes of cutting and heat treatment are the same as those in Embodiment 1.

Embodiment 6 of the gear precision plastic forming process of the present invention is the forming of the gear parts shown in Fig. 11 and Fig. 12. Its tooth shape is an involute tooth shape. In this embodiment, the precision is IT7, and the tooth surface is rough The degree is Ra1.6, the modulus is 1.5, the number of teeth is 40, the gear height is 25mm, and the material is 20CrMnTi (other gear materials can also be used, such as 20Cr, 20CrMnTi, 20CrMo, 20CrMnMo, 20MnTiB, 20MnVB, 45, 40Cr). It is Φ63×27mm. The implementation steps are as follows:

1. Heating the cut cylindrical blank to 400-1100°C in an intermediate frequency induction furnace, and heating to 850°C in this embodiment;

2. First-stage warm extrusion forming. Put the heated billet 29 into the first-stage warm extrusion die 30 shown in FIG. Do not squeeze through. Stop extrusion after the extrusion force reaches 2500KN, and eject the workpiece. The tooth profile area of the gear blank formed by the first-stage warm extrusion is 20% larger than the tooth profile area required by the gear parts, see Figure 14;

3. Cool the gear blank 34 obtained by warm extrusion to room temperature in air;

4. Surface treatment and lubrication treatment, the gear blank 34 cooled to room temperature is subjected to sand blasting-acid washing-alkali washing-water washing-phosphating-saponification treatment;

5. Cold shaping, as shown in Figure 19, put the gear blank 34 processed in process 4 into the cold shaping die 40 from the feed side, and carry out cold extrusion forming on a 1000KN hydraulic press, and the pressure die 39 will press the gear blank 34 Pushed out from the feed side through the sizing section and from the discharge side, the tooth tip axial flow angle β1 of the cold shaping die 40 of this embodiment is 8°, and the dedendum axial flow angle β2 is 2° larger than β1, The radial split angle α1 is 1°. The axial retraction angle γ1 of the addendum is 3°, the axial retraction angle γ2 of the tooth root is 3°, the radial split angle α2 of the retraction is 3°, and the length of the discharge section is 13mm. The area of the gear blank after cold shaping is equal to the tooth profile area required by the gear parts, and the margin c of cold shaping is 0;

6. The two end surfaces of the turning gear blank 34 are cut, the gear shaft hole 27 is drilled, the spline is drawn, and the teeth are not shaved.

7. Heat treatment is carburizing and quenching. Put the processed gear into the carburizing furnace and heat it to 980°C for carburizing. After reaching the required thickness of the carburized layer, cool down to 850°C for quenching.

The seventh embodiment of the gear precision plastic forming process of the present invention is the forming of the gear parts shown in Figure 11 and Figure 12. Its tooth shape is an involute line tooth shape. In this embodiment, the precision is IT6, and the tooth surface is rough. The degree is Ra0.8, the modulus is 6, the number of teeth is 45, the gear height is 40mm, the material is 20CrMnTi, and the blank is Φ280×43mm. The implementation steps are as follows:

1. Heat the cut cylindrical blank to 850°C in an intermediate frequency induction furnace;

2. First-level warm extrusion forming. Put the heated billet 29 into the first-level warm extrusion forming die 30 in FIG. out.

3. Two-stage warm extrusion forming, as shown in Figure 15, immediately put the extruded gear blank 29 into two two-stage warm extrusion dies 33 with different warm extrusion forming margins a, In the YA32-150 hydraulic press, carry out two-stage warm extrusion forming. In this embodiment, the two-stage warm extrusion dies 33 have an axial conduction angle β1 of 8° at the tip of the tooth, and an axial conduction angle of the tooth root. The angle β2 is 4° larger than β1, and the radial split angle α1 is 5°. The axial retraction angle γ1 of the addendum and the axial retraction angle γ2 of the tooth root are 4°, the radial split angle α2 of the retraction is 5°, and the length of the discharge section is 18mm. The margins a of the secondary warm extrusion forming are 5.5 mm and 4.0 mm respectively, so that the tooth profile area of the gear blank 34 is equal to the tooth profile area of the gear blank 29 after the primary warm extrusion forming. Oil graphite is used as lubricant when extruding.

4. Pushing and shaping, as shown in Figure 18, the gear blank 34 obtained after the above-mentioned two-stage warm extrusion is turned upside down, and the temperature is reduced as much as possible. In the die 37, the YA32-150 hydraulic press carries out two pushing and shaping. In this embodiment, the axial diversion angle β1 of the addendum tip 37 is 8°, the axial diversion angle β2 of the tooth root is 4° larger than β1, and the radial split angle α1 is 5°. The axial retraction angle γ1 of the addendum and the axial retraction angle γ2 of the tooth root are 4°, the radial split angle α2 of the retraction is 5°, and the length of the discharge section is 18mm. The pushing and shaping margins b are 2.8mm and 1.8mm respectively.

5. Cool the gear blank 34 obtained by pushing and shaping to room temperature in air;

6. Surface treatment and lubrication treatment, the gear blank 34 cooled to room temperature is subjected to sand blasting-acid washing-alkali washing-water washing-phosphating-saponification treatment;

7. Cold shaping, as shown in Figure 19, put the gear blank 34 processed in step 6 into two cold shaping dies 40 with different cold shaping allowances c, and perform cold pushing and forming twice on a 1000KN hydraulic press. In the cold shaping die 40 of this embodiment, the addendum axial conduction angle β1 is 8°, the dedendum axial conduction angle β2 is 2° greater than β1, and the radial diversion angle α1 is 2°. The axial retraction angle γ1 of the addendum, the axial retraction angle γ2 of the tooth root are 3°, the radial split angle α2 of the retraction is 3°, and the length of the discharge section is 23mm. The allowance c for cold shaping is 0.9mm, 0.04mm, and 0.04mm respectively as the grinding allowance;

8. Cutting and machining the two ends of the turning gear blank 34, drilling the gear shaft hole 27, and drawing the spline.

9. Heat treatment means carburizing and quenching. Put the processed gear into the carburizing furnace and heat it to 980°C for carburizing. After reaching the required thickness of the carburized layer, cool down to 850°C and then quench.

10. Grinding the teeth to make the tooth shape meet the required dimensional accuracy and surface roughness of the parts;

In the various embodiments of the above-mentioned forming process, if the precision of the gear part is lower than IT7, multiple cold shaping can be carried out, so that c=0 in the last cold shaping can meet the requirements; for gear parts with small surface roughness, such as Ra0 .8 Gears to be ground: The tooth top axial diversion angle β1 of the first-stage warm extrusion die of the first-stage warm extrusion forming process is 4°, and the radial diversion angle α1 is 5°.

The cutting process mentioned in this application document refers to any one or more of turning, milling, planing, drilling, broaching, and shaving, excluding gear grinding; the cold shaping allowance c in this application is the sizing section The tooth shape of the gear blank after cold shaping is that the tooth 42 of the gear blank is larger than the tooth 26 required by the gear part by c on one side, see Figure 20. Said cooling to room temperature is preferably controlled to be cooled to room temperature.

Claims (10)

1. A precision plastic forming mold for gears, which has a mold body, a gear-shaped cavity that communicates with both ends of the mold body in the shape of a gear part, and teeth corresponding to the tooth shape of the gear part are distributed inside the gear-shaped cavity The gear-shaped cavity has a feed section on the feed side, which is characterized in that: the angle between the tooth top of the feed section and the axis of the gear-shaped cavity is the tooth top axial diversion angle β1, and β1 is 0.5-30° , the angle between the side of the inner tooth in the feed section and the symmetrical plane of the inner tooth is the feed radial split angle α1, and α1 is 0.5-30°. 2. The gear precision plastic forming die according to claim 1, characterized in that: it also has a certain diameter section and an outwardly expanded discharge section, and the tooth-shaped groove corresponding to the tooth shape of the gear part is in the The tooth shape of the sizing section is a straight tooth shape similar to the tooth shape of the gear part, and the angle between the dedendum of the feeding section and the axis of the gear cavity is the dedendum axial diversion angle β2, β2≥β1; the sizing section The tooth profile is larger than the tooth profile required by the gear parts by a, a is the allowance for warm extrusion, and the range of a is 0.8-6mm; the angle between the tooth top of the discharge section and the axis of the gear cavity is the tooth top The axial withdrawal angle γ1, γ1 is 0.5-30°, the angle between the tooth root of the discharge section and the axis of the gear cavity is the tooth root axial withdrawal angle γ2, the tooth root axial withdrawal angle γ2 is greater than zero, and the outlet The included angle between the side surface of the inner tooth of the feed section and the symmetrical plane of the inner tooth is the radial diversion angle α2 of the ejection mold, and α2 is greater than zero. 3. The gear precision plastic forming die according to claim 1, characterized in that: it also has a certain diameter section and an outwardly expanded discharge section, and the tooth-shaped groove corresponding to the tooth shape of the gear part is in the The tooth shape of the sizing section is a straight tooth shape similar to the tooth shape of the gear part, and the dedendum axial diversion angle β2 of the feed section, β2≥β1; the tooth profile ratio of the sizing section is required by the gear part. The single side of the shape is large b, b is the allowance for pushing and shaping, and the range of b is 0.1-3.5mm; the axial retraction angle γ1 of the tooth top of the discharge section is 0.5-30°, and the axial retraction of the tooth root of the discharge section The angle γ2, the dedendum axial retraction angle γ2 is greater than zero, and the radial split angle α2 of the discharge section is greater than zero. 4. The gear precision plastic forming die according to claim 1, it also has a sizing section and an outwardly expanded discharge section, and the tooth-shaped groove corresponding to the tooth shape of the gear part is in the sizing section The tooth profile is the same as or similar to the tooth profile of the gear part, the root axial diversion angle β2 of the feed section, β2≥β1; the tooth profile of the sizing section is more than the tooth profile required by the gear part Large c on one side, c is the cold shaping allowance, the range of c is 0.0-2.5mm; the axial retraction angle γ1 of the tooth top of the discharge section is 0.5-30°, and the axial retraction angle of the tooth root of the discharge section γ2 is greater than zero, and the ejection radial split angle α2 of the discharge section is greater than zero. 5. The gear precision plastic forming die according to claim 4, characterized in that: said cold shaping margin c is 0.02-0.45mm. 6. The gear precision plastic forming die according to claim 2 or 3 or 4 or 5, characterized in that: γ1=γ2. 7. A gear precision plastic forming process, the steps include: the first step is to heat the cut cylindrical blank to 400-1100°C; the second step is to put the heated blank into the gear precision plastic forming mold for warming Extrusion forming, the pressure is added to the upper and lower sides of the cylindrical blank, and the warm extrusion is close to the gear blank of the tooth profile of the gear part. The warm extrusion forming is carried out in the gear precision plastic forming die described in claim 1. Stage temperature extrusion forming or repacking into the gear precision plastic forming die described in claim 2 to carry out at least one secondary temperature extrusion forming, the tooth shape ratio of the gear blank after the secondary temperature extrusion forming is required by the gear parts The single side of the tooth shape is large a, a is the allowance for warm extrusion, and the range of a is 0.8-6mm; the third step is to carry out precision forming and cutting of the tooth shape, so that the tooth shape can reach the dimensional accuracy required by the gear parts and surface roughness. 8. The gear precision plastic forming process according to claim 7, characterized in that the steps of tooth profile precision forming and cutting process are: cooling the gear blank to room temperature before turning and shaving. 9. The gear precision plastic forming process according to claim 7, characterized in that the steps of tooth shape precision forming and cutting process are as follows: after cooling the gear blank to room temperature, carry out surface treatment to remove the surface oxide layer and impurities Carry out lubrication treatment; cold shaping, put the gear blank into the gear precision plastic forming mold described in claim 4, apply pressure on the gear blank, push the gear blank from the discharge side to carry out cold shaping at least once, and the gear after cold shaping The tooth profile of the blank is larger than c on one side of the tooth profile required by the gear part; cutting process; a>c of the two gear plastic precision forming dies used. 10. The gear precision plastic forming process according to claim 7, characterized in that the steps of precision forming and cutting of the tooth profile are as follows: put the gear blank after warm extrusion upside down while it is hot and put it into In the gear precision plastic forming die described in claim 3, at least one pushing and shaping is carried out, pressure is applied to the gear blank, the gear blank is pushed out from the discharge side, and the tooth profile ratio of the gear blank after pushing and shaping is required by the gear parts. The single side of the tooth shape is large b; the gear blank after pushing and shaping is cooled to room temperature for surface treatment to remove the surface oxide layer and impurities and then lubricated; cold shaping, the gear blank is packed into the gear precision plastic forming described in claim 4 Apply pressure on the gear blank in the mold to push the gear blank from the discharge side for at least one cold shaping. The tooth profile of the gear blank after cold shaping is larger than the tooth profile required by the gear part. Machining; three A>b>c of the gear plastic precision forming die.

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