CN1112515C - Shaft structure of screw rotor for screw fluid machinery - Google Patents

Abstract

A helical rotor is provided with a rotor 1 formed with helical teeth and a small-diameter shaft 5 or an embedded hole at the outer end 4 of a central shaft 3, the central shaft 3 protruding to the outer end 2 on the axis of the rotor, and the outer end 2 is embedded Alternatively, the separately manufactured rotor shaft 6 embedded in the small-diameter shaft 5 or the insertion hole is provided with the insertion hole 7 or the small-diameter shaft. In addition, a helical groove is formed on the circumferential surface of a metal shaft covered with synthetic resin. The rotation direction of the helical groove is opposite to that of the helical rotor. The helical groove is formed by a contour line made of a smooth The peak-shaped curve is connected, and the above-mentioned shaft is provided with steps, and the surface of the shaft is covered with synthetic resin.

Description

Shaft structure of the helical rotor of the helical fluid machine

technical field

The present invention relates to the structure of the shaft of the screw rotor used in the screw fluid machine, especially the connection structure of the shaft of the screw rotor used in compressors, expanders, vacuum pumps, etc., and the shaft relative to the rotor of the screw rotor Install structure.

Background technique

Conventionally, this type of helical rotor is formed by integrating the rotor and the rotor shaft. For example, the shaft formed by the rotor, the central shaft and the rotor shaft is machined from the same metal material. Alternatively, it has been proposed to cover and form a synthetic resin rotor around the metal shaft by injection molding in order to improve workability and reduce weight.

Even if the size of the rotor is the same among various models, due to the change of the discharge pressure of the screw fluid machine and the change of the driving prime mover, and the change of the shaft length, shaft diameter or surface treatment of the screw fluid machine according to the use of the screw fluid machine, so The manufacturing process of the rotor is complicated, and there are many kinds.

Therefore, there are many problems. Taking the diameter of each part of the helical rotor as an example, the diameter of the rotor teeth is usually about 3 to 4 times that of the shaft. So there are the following problems in terms of manufacturing:

(1) In the case where the rotor and the shaft are machined from the same metal material, to use a raw material that matches the diameter of the rotor teeth, it must be cut to the desired shaft diameter by machining. Therefore, the material and The processing time produces great waste.

(2) In the case of integrally forming a thermosetting synthetic resin rotor around a metal shaft, it is sufficient to prepare a metal material commensurate with the diameter of the shaft, but the shaft is long compared to the shaft diameter, so During processing, it is necessary to consider measures to deal with the center vibration of the shaft and long rod, which deteriorates the productivity.

(3) Furthermore, since the rotor shaft is very long, the casting mold of the rotor is also large, and the cost is high, and the workability at the time of molding is not good. In addition, also in the case of surface treatment, the workability is not good.

(4) For example, a water injection compressor injects water into the compression action space, cools and seals the space, and if the shaft is in contact with fluid containing the atmosphere or moisture, it will rust during long-term use, which is The causes of leakage of the shaft seal and abnormal wear of the sliding part.

(5) Since the diameters and shaft lengths of the shafts are different even if the tooth profile dimensions of the rotors are the same, the components cannot be used in common use, and manufacturing and management are complicated.

As a solution to these problems, in order to reduce the weight, the screw rotor part is divided into a hollow small diameter part and a hollow large diameter part, and the opposing end faces are connected by frictional pressure welding. For this type of screw compressor, The Japanese Patent Publication No. 57-105418 has content in this respect, but its structure is to adopt a hollow shaft, and its connection is also connected by frictional crimping, which is not the key to solving the above-mentioned problems. In addition, in the screw compressor disclosed in Japanese Patent Application Laid-Open No. 56-49311, the crankshafts are simply connected by splines, and elastic bodies are injected into the spline connections to reduce wear and noise. In addition, in the propeller shaft disclosed in Japanese Patent Application Laid-Open No. 2-71108, a groove is formed on either one of the transmission shaft and the hoop, and a protrusion coupled to the groove is formed on the other. In addition, as disclosed in Japanese Patent Publication No. 52-25562, an integral sleeve is provided on the impeller of the compressor, and a thread is cut on the hole of the sleeve to accommodate the threaded portion of the shaft and assembled. However, these methods regard the general installation as the real key issue, etc., but in fact they are not the key to solving the above-mentioned problems.

The helical rotor is formed by covering and forming a synthetic resin rotor around the metal shaft by injection molding. The method of forming such a helical rotor is well known in the past. This type of helical rotor is shown in FIG. 12 .

Figure 12 shows a partial cross-sectional view [figure (a)] and a front view [figure (b)] cut off with a plane A-A [refer to Figure 12(b)] containing the shaft (shown as a concave rotor), but in these On the circumferential surface of the shaft 41 formed by the central shaft 38 of the helical rotor and the rotor shaft 36, a single or multiple cross-sections are formed with a square (quadrilateral) groove 39 or protrusion, and the groove 39 or protrusion has a tooth 46 with the rotor 1f. The helix angle of the helical direction in the same direction and the opposite direction strengthens the connecting force between the shaft 41 and the rotor 1f, and prevents the disengagement of the two (for example, refer to Japanese Patent Laying-Open Publication No. 6-123292, Japanese Patent Laid-Open No. 1-301976 Bulletins, etc.).

Since these helical rotors are formed of synthetic resin on the surface of the rotor, they will not rust.

Therefore, such a screw rotor is most suitable for a screw compressor (water injection type screw compressor) that injects water into a compression action space.

However, a groove 39 with a square cross-sectional shape is formed on the peripheral surface of the shaft 41, and synthetic resin is covered here to combine the shaft 41 and the rotor 1f. In this helical rotor, the metal shaft 41 and the rotor 1f made of synthetic resin are connected together. Difference in heat shrinkage (shaft-heat shrinkage is small, rotor-heat shrinkage is large) and the change in rotational torque due to load changes during operation is large, and the difference between the rotor (synthetic resin part) and the groove 39 provided on the shaft surface Stress concentration occurs at the corner of the groove corresponding to the peak. The above-mentioned difference in thermal contraction is due to the difference in linear expansion coefficient caused by the difference in the material of the shaft and the rotor. When the synthetic resin rotor after injection molding is cooled, or with the compressor It is caused by the temperature change when running and stopping.

This type of screw rotor has the following problems: due to the above reasons, the rotor 1f is prone to cracks from the peak corner of the groove 39 arranged on the shaft surface to the tooth bottom of the rotor 1f. , this crack will expand, the connecting force between the shaft 41 and the rotor 1f will decrease, and finally the shaft and the rotor will be separated.

On the other hand, if referring to FIG. 13 to observe the water-injected screw compressor, it will be found that the feature is that, in the case of using the above-mentioned type of screw rotor, since the rotor is made of synthetic resin, rust can be prevented. However, there is a problem that since the shaft 41 is made of metal, and the shaft surface between the compression chamber and the shaft seal (water seal) is in contact with the water supplied to the compression chamber, the shaft surface must rust.

In this way, in the screw rotor of the existing water injection type screw compressor, when the shaft portion, especially the shaft surface embedded in the water shaft seal device, is rusted, the shaft surface will be corroded due to rust, and the portion of the shaft will be corroded due to rust. The diameter of the shaft should be reduced, and a gap will be generated between the above-mentioned shaft seal device and the shaft surface, which will damage the body of the shaft seal device and reduce the performance of the shaft seal.

Therefore, there is a problem that the water supplied to the compression action chamber leaks from the gap between the above-mentioned shaft seal device and the shaft surface to the shaft end of the screw rotor shaft, flows into the bearing portion adjacent to the shaft seal portion, and induces deterioration of the lubricating oil and The emulsification phenomenon leads to a reduction in the life of the bearing, so its anti-rust measures constitute a problem.

In addition, there are various problems as follows: Since the performance of the shaft seal part decreases with the occurrence of the above-mentioned rust, the lubricating oil supplied to the bearing part flows into the compression action chamber from the gap between the shaft seal part and the shaft surface, and is mixed into the The water used for cooling and sealing of the action chamber contaminates the water, and oil is also mixed into the exhaust air, which adversely affects the equipment used on the consumption side.

Therefore, the material of the above-mentioned helical rotor shaft can be made of stainless steel, or the surface of the shaft embedded in the shaft seal device can be treated with electroplating and coating with good anti-rust effect to prevent rust, but the price and processing cost of the helical rotor have also appeared in this way. Added questions.

Contents of the invention

The purpose of the present invention is to:

The first or second is formed by simple shaft connection, and the same rotor can be used in various machines with different shaft lengths, without wasting the material of the screw rotor, and solves the problem of high cost due to many man-hours required for manufacturing and processing. In addition, The shaft can be disassembled, the installation is easy, and the forming machine can be miniaturized. Only the special shafts in various machines can be processed. The processing of the shaft is easy, and the manufacturing cost can be reduced.

Thirdly, in addition to any one of the first and second problems, it is possible to prevent assembly errors of the rotor and the rotor shaft and further reduce the cost.

No. 4 and No. 5, plus any one of No. 1 to No. 3, since the central shaft is covered with synthetic resin, it is easy to carry out only the necessary part as a rust prevention measure for the shaft. Anti-rust treatment or surface treatment, easy to use corrosion-resistant materials.

6th, plus any one of the 1st to 5th issues, since the vent hole is perforated, the vent hole penetrates from the insertion hole recessed on the rotor shaft or the central shaft to the shaft end on the opposite side, and the shaft It can be inserted smoothly when connecting, so the insertion operation can be easily and reliably performed, and the temperature difference between the operation and stop of the recessed part can allow air to circulate (breathing).

No. 7 and No. 8, plus any one of No. 1 to No. 6, because the linear expansion coefficient of the material embedded in the central axis is smaller than that of the embedded shaft, the conduction caused by compression The effect of the heat is to make the mating hoop tighter, enabling it to maintain a mating state for a long time.

Ninth, another object of the present invention is to provide a screw rotor in which a synthetic resin rotor is formed around a metal shaft, which can overcome all the problems pointed out above and make the connection between the shaft and the rotor The connection force is strong, and the concentrated stress of the connection part caused by temperature changes can be eliminated, and the shaft surface of the shaft seal part can be prevented from rusting, and it is inexpensive and has good processability.

In order to achieve the above-mentioned first to eighth objects, the present invention is characterized in that: the screw rotor of the screw fluid machine has a rotor formed with helical teeth and a central shaft protruding from at least one side of the outer end of the rotor axis. The outer end of the rotor is provided with a step, and a small-diameter shaft is protruded, and an additional rotor shaft with a recessed embedding hole is externally embedded on the small-diameter shaft for shaft connection.

In addition, the shaft connection can also be realized in the following manner: the outer end of the central shaft having the rotor formed with helical teeth and the central shaft protruding from at least one of the outer ends of the rotor shaft is recessed with an insertion hole, In addition, a separately manufactured rotor shaft with a small-diameter shaft projecting therefrom is inserted into the insertion hole for shaft connection.

In order to achieve the ninth object above, the helical rotor of the present invention, in which a synthetic resin rotor is formed around a metal shaft, is characterized in that:

Steps and/or bumps are provided at the shaft portion covered with synthetic resin material, and,

providing wave-shaped grooves or spiral grooves on the surface of the above-mentioned covering shaft portion,

A cross-section of the above-mentioned wave-shaped groove or helical groove, cut by a plane including the center line of the shaft, is formed with a contour line that connects the arc-shaped groove surface and the adjacent arc-shaped groove surface with a smooth peak-shaped curve formed by the Ministry.

The helical rotor embodiment of the present invention will be described below according to the accompanying drawings. Among the main components that constitute this embodiment, because it contains the components that can be modified in various ways within the scope of the general technical level of the present invention in the same industry , so no specific reason is specified, and the gist of the present invention is not allowed to be limited and explained only based on the specific structures disclosed in the embodiments of the present invention.

Description of drawings

Fig. 1 is a sectional view of the first embodiment of the screw rotor of the present invention.

Fig. 2 is a sectional view showing the state before the screw rotor shaft is connected according to the first embodiment of the present invention.

Fig. 3 is a sectional view of the second embodiment of the screw rotor of the present invention.

Fig. 4 is a sectional view of a third embodiment of the screw rotor of the present invention.

Fig. 5 is a cross-sectional view of a fourth embodiment of the helical rotor of the present invention.

Fig. 6 is a schematic sectional view of an example of a compressor or a main part of a conventionally known water jet screw compressor.

Fig. 7 is a side sectional view of an embodiment of the helical rotor of the present invention and a partial enlarged sectional view of the helical groove.

Fig. 8 is a side sectional view of another embodiment of the screw rotor of the present invention.

Fig. 9 is a partial side sectional view of another embodiment of the screw rotor of the present invention.

Fig. 10 is a partial side sectional view of another embodiment of the screw rotor of the present invention.

Fig. 11 is a partial side sectional view of a different embodiment of the screw rotor of the present invention described above.

Fig. 12 is a partial side sectional view and a front view of an example of a conventionally known helical rotor.

Detailed ways

The screw fluid machine of the present invention will be described below, and the screw fluid machine is taken as an example for the convenience of description. The following description will be made based on the embodiments shown in FIG. 1 to FIG. 5 . As shown in Figures 1 and 2, the helical rotor is formed with a helical tooth-shaped rotor 1 and at least one outer end 2 of the shaft of the rotor 1 to extend a central shaft 3, (or by forming a synthetic resin material around the metal shaft. The rotor is equipped with a central shaft 38 protruding from at least one outer end on the rotor shaft center), a step is provided on the outer end 4 of the central shaft 3, and a small-diameter shaft 5 is protruded, and the embedded hole 7 is recessed. A separate rotor shaft 6 is externally fitted on the small-diameter shaft 5 for shaft connection. In this case, it is also preferable to provide the same center shaft 3a, small-diameter shaft 5a, separately manufactured rotor shaft 6a, and fitting hole 7a on the other end 2a of the rotor 1 as above. And respectively from the starting end 26,26a and the outermost end 27,27a of the small-diameter shaft 5,5a arranged on the central shaft 3,3a of the above-mentioned rotor 1, to the length of the rotor end face-rotor outer end 2,2a, in the clip The two axial ends of the rotor 1 are designed to be roughly the same size. Fig. 2 is a cross-sectional view showing the state before the shaft of the screw rotor is connected, and the same parts as in Fig. 1 are assigned the same reference numerals, and description thereof will be omitted here.

In the following description of the present invention, the so-called rotor also includes rotor toothing formed with helical teeth.

In addition, as shown in Figure 3, the above-mentioned shaft connection can also be carried out in this way: on at least one outer end 8 of the rotor 1c formed with the helical tooth and the axis of the rotor 1c, a central shaft 9 is extended, and on the central shaft The outer end of 9 is concavely provided with an embedding hole 10 , and an additionally manufactured rotor shaft 11 with a small-diameter shaft 12 is embedded in the embedding hole 10 . In this case, such shaft connection means can also be adopted: preferably also on the outer end 8a of the rotor 1c, on the outer end of the same central shaft 9a as above, the embedding hole 10a is recessed, and on the other rotor A small-diameter shaft 12a protrudes from the shaft 11a, and the small-diameter shaft 12a is fitted into the fitting hole 10a. In this case, it is preferable to connect from the starting end 28, 28a and the innermost end 29, 29a of the insertion hole 10, 10a recessed on the central axis of the above-mentioned rotor 1c to the rotor end surface-the outer end 8, 8a of the rotor. The length is designed to be substantially the same size at both axial ends clamping the rotor 1c.

Furthermore, as a means of connecting the shafts in the above embodiments, the diameter of the hole is made smaller than the diameter of the shaft, and the shaft is press-fitted into the insertion hole, or connected by thermal fitting. In addition, it is also possible to process a feather key on the hole and the shaft to connect the shaft, or to process a thread on the hole and the shaft and then perform screw connection.

As shown in FIG. 4 , the rotor 1 d is formed by integrally forming a thermosetting synthetic resin rotor around the metal center shaft 13 . The shaft connection method of the third embodiment is: at least one outer end 32 on the metal central shaft 13 of the rotor 1d extends the central shaft 15, and the outer end of the central shaft 15 is recessed with an embedded hole 16, and the A separately manufactured rotor shaft 17 with a small-diameter shaft 18 projecting therefrom is fitted into the insertion hole 16 . The shape of the shaft connection of the fourth embodiment is shown in Figure 5, and the mode of shaft connection can also be: at least one outer end 35 of the metal central shaft 19 of the rotor 1e, extend the central shaft covered with synthetic resin around 20, a step is provided on the outer end 21 of the central shaft 20 and a small-diameter shaft 22 protrudes, and the embedding hole 24 recessed at the end of the separately manufactured rotor shaft 23 is externally embedded on the small-diameter shaft 22 . Moreover, the 3rd and 4th embodiments preferably also adopt the shaft connection device with the same structure as that of Fig. 4 and Fig. 5 at each outer end 32a, 35a, and the same symbol is marked a, and its description is omitted here. Also, in this case, it is also preferable to go from the starting end 30, 30a and the innermost end 31, 31a of the insertion holes 16, 16a recessed in each central axis of the above-mentioned rotor 1d to the outer end 32, 32a of the rotor, respectively. and the lengths from the initial ends 33, 33a and the outermost ends 34, 34a of the small-diameter shafts 22, 22a arranged on the central axis of the above-mentioned rotor 1e to the outer ends 35, 35a of the rotors respectively, in each of the rotors 1d, 1e Both shaft ends are respectively designed to have approximately the same size. In addition, the connecting device of these shafts makes the hole diameter smaller than the shaft diameter. It is better to heat the insertion hole (the shaft can also be cooled) and press the shaft into the insertion hole, or it is also possible to process splines on the hole and the shaft as described above. , for shaft connection, or cutting threads on the hole and shaft for threaded connection. In addition, the above-mentioned rotor can also adopt the technical means of covering the outer peripheral surface of the central shaft with a synthetic resin of the same quality as the rotor.

In the above-mentioned first to fourth embodiments, the shape of the insertion hole and the small-diameter shaft of the shaft connection device can be circular, triangular, quadrilateral, polygonal, etc., and different shapes can also be used, such as one end of the central shaft An embedded hole is recessed, and a small-diameter shaft protrudes from the other end. In addition, as shown in FIG. 4, the periphery of the extended part of the metal central shaft 13 of the rotor 1d is not covered with synthetic resin, and the central shaft 20 is shown in FIG. The periphery of the extension part is covered with synthetic resin, and the periphery of the extension part of the metal central shaft 19 of the rotor 1e may not be covered with synthetic resin according to different conditions of use, but a metal central shaft 19 is used, or covered with synthetic resin. Around the extended portion of the metal central shaft 13 of the rotor 1d.

Moreover, in any one of the embodiments shown in Fig. 1 to Fig. 5, vent holes 25, 25a... The vent hole penetrates from each insertion hole 7 , 7 a , 10 , 10 a , 16 , 16 a , 24 , 24 a recessed on the rotor shaft or central shaft to the shaft end on the opposite side. In this case, the so-called approximate axis refers to the position where each vent hole 25, 25a... can make any part of each insertion hole 7, 7a, 10, 10a, 16, 16a, 24, 24a communicate with the outside air. , not the axis in geometry, so the present invention is called the approximate axis (the axis of the center can also be perforated in manufacture).

In addition, the material of the rotor shafts 6, 6a, 23, 23a which are externally connected to the central shaft of the rotor is a metal material, and the coefficient of linear expansion of the metal material is smaller than that of the material used for the central shaft. In addition, the material used for the central shaft of the rotor is a metal material, and the coefficient of linear expansion of the metal material is smaller than that of the rotor shafts 11, 11a, 17, 17a embedded with the central shaft.

Next, the operation and main functions of the compressor shown in FIG. 6 will be described. The helical rotor composed of the rotor part and the separately manufactured rotor shaft in the form of various embodiments and various shaft connection devices, as shown in Figure 6, has no change in appearance, and the function of the helical rotor of the helical fluid machine does not exist. Variety. The functions of various technical devices of the present invention are described below. Because the rotor and the shaft are a combined structure, in order to realize the generalization of the size of the rotor (including the rotor teeth), it can be mass-produced with a dedicated processing machine. On the other hand, the shaft is processed separately for each disassembled shaft. , and combine the two to form the desired rotor by shrink fitting or the like. The processing quality and performance of the helical rotor thus completed are very stable, and the processing man-hours and manufacturing costs can be greatly reduced. And since parts can be commonly used, parts management is also easy.

In addition, since the central shaft is covered with synthetic resin, in addition to the anti-rust effect of the shaft, even if the small gap between the shaft seal of the action chamber and the bearing chamber touches during the operation of the fluid machine, it will not be sintered.

Furthermore, when the central shaft of the helical rotor is matched with the rotor shaft, the air remaining in the recessed portion can escape to the outside through the vent hole formed on the rotor shaft. Therefore, the air circulation (breathing effect) of the recessed part due to the temperature difference between operation and stop can be carried out, and the connection can also be very firm.

Because the linear expansion coefficient of the material embedded on the central shaft is smaller than that of the embedded shaft, the effect of heat conduction generated by the compression action makes the matching hoop tighter. Therefore, the combined state can be reliably maintained for a long period of time. Moreover, when the rotor teeth or the rotor shaft are worn during long-term operation, only these parts can be replaced separately during maintenance or the like.

Fig. 7(a) is a schematic side sectional view of another embodiment of the helical rotor of the present invention. Figures (b) to (d) are enlarged cross-sectional views of the spiral groove or wave groove.

In the figure, on the metal shaft 41, the diameter is reduced in the axial direction, and a step 47 is provided. On the circumferential surface of the central shaft 38 formed by the thin diameter shaft part, the groove and the peak of the groove section are provided with circular arcs. Shaped small spiral groove 43, screw thread or wave groove. In the case of the present embodiment, the helical groove 43 is one thread, but the same function and effect can be obtained even with a plurality of threads.

Figure 7(b) is an enlarged cross-sectional view of the spiral groove 43. The peaks 44, 44' connect the surfaces of the groove 43 having an arc-shaped R and the adjacent groove 43' to each other, and the peaks 44, 44 are trimmed with a radius r. ', so that it is connected with the surface of the spiral groove 43 with a smooth curved surface, and there are no corners on the circumferential surface of the shaft.

The cross-section of the above-mentioned helical groove 43 is shown in Figure 7 (b), and the trimming radius r of the peak portion 44 is different from the radius R of the arc groove, for example, making it a small radius, but as shown in Figure (c), it is also The above-mentioned radius r may have the same length R as that of the arc grooves so that the arcs are directly connected to each other.

In addition, the shape of the cross-section may be a peak shape or a substantially Wilbur screw shape [see FIG.

Furthermore, referring to FIG. 7( a ), the above-mentioned helical groove 43 is a helical groove that rotates in the opposite direction with respect to the rotation direction of the helical rotor during operation. That is, when the male rotor rotates clockwise as viewed from the suction side shaft end, the helical groove 43 is expected to spiral leftward, and a right-handed helical groove is formed on the female rotor shaft meshing with the male rotor.

The central shaft 38 is composed of a thin-diameter shaft portion provided with the above-mentioned helical groove 43. On both sides of the central shaft 38, a shaft diameter part that is a little thinner than the diameter of the helical groove 43 is provided as a retraction of the tool when the helical groove 43 is processed. Sipe.

The central shaft 38 is constituted by a thin-diameter shaft portion provided with the spiral groove 43, because if the diameter D2 of the central shaft 38 is smaller than the axial diameter D1 of the rotor shaft 36 on the suction side and the discharge side (D1>D2), then it can The interval h between the circumferential surface of the central shaft 38 covered with the above-mentioned synthetic resin and the tooth groove bottom of the synthetic resin rotor (indicated by a dotted line in the figure) is made thick, so even if the synthetic resin material near the shaft is cracked, the crack will Reaching the rotor cogs is also extremely rare.

The groove (peak) depth of the spiral groove 43 is relatively shallow compared to the shaft diameter, for example, about 1% of the diameter. This structure can control the thermal shrinkage stress generated by the groove-shaped covering portion of synthetic resin within a small range.

46 denotes the teeth of the rotor 1f made of synthetic resin covering the shaft 41 .

47 is a step provided on the shaft 41, and the axial thrust of the rotor 1f is supported by the step. In order to avoid stress concentration, a small R or chamfer is provided at the corner of the step 47 .

In this embodiment, when the material of the synthetic resin covering the shaft 41 is glass phenol resin mainly composed of phenol resin and glass fiber, since the coefficient of linear expansion of the above resin is similar to that of metal (here, steel, cast iron) The linear expansion coefficient, so the compressor adopting this rotor can control the stress generated by the difference in thermal shrinkage between the shaft 41 and the rotor 1f during its operation and stop within a small range.

Synthetic resins for rotors are not limited to the above-mentioned glass phenol resins. If the synthetic resin satisfies the characteristics such as mechanical strength and has an expansion coefficient close to that of the shaft material, if the synthetic resin is used, it will be possible to reduce the temperature caused by thermal changes. There is no limit to its composition if the resulting stress is as small as possible.

Fig. 8 is a partial cross-sectional view of another embodiment of the helical rotor of the present invention.

Among the reference numerals given in the figure, the components represented by the same reference numerals as those described in FIG. 7( a ) are the same components as those in the above-mentioned embodiment.

The diameter D4 of the place where the helical groove 43 is provided on the shaft 41 covered with synthetic resin is thicker than the shaft diameter D3 of the rotor shaft 36 including the suction side and the discharge side (D4>D3). The surface area of the portion where the spiral (wave) groove 43 is provided strengthens the connection force between the shaft 41 and the rotor 1f.

In this case, there is no need to worry about reducing the strength of the shaft 41 because there is no need to provide an undercut for machining the helical groove 43 on the shaft 41 . Also, a step 47 provided between the shaft diameter D4 and the shaft diameter D3 serves to support the axial force required for the synthetic resin rotor 1f. As for the shape of the step 47 as mentioned above.

In this embodiment, if the distance between the outer peripheral surface of the central shaft 38 provided with the helical groove 43 and the outer periphery of the rotor 1f is A2, and the distance between the end surface of the rotor 1f and the step 47 of the shaft 41 provided with the helical groove 43 is A1 , in the case of A1=A2, during the cooling period of the formed synthetic resin rotor 1f, since the synthetic resin material near the shaft 41 has a uniform cooling rate, the internal stress generated by the rotor is reduced, so the possibility of cracks in the resin material decreased.

In the case of the present embodiment, the cross-sectional shape of the spiral groove 43 may also be the groove shape shown in FIG. 7 .

Fig. 9 is a partial cross-sectional view of a water-injected screw compressor according to another embodiment of the screw rotor of the present invention. A step thinner than the shaft diameter of the shaft 41 is provided between the suction-side shaft seal part and the discharge-side shaft seal part. The shaft 41 includes the rotor shaft 36 on the suction side and the discharge side, and a spiral groove or a corrugated groove is provided on the peripheral surface of the central shaft 38 constituted by the small-diameter shaft portion.

The length range L of the step is preferably longer than the distance between the water shaft seals on the suction side and the discharge side, and shorter than the distance between the oil shaft seals on the suction side and the discharge side. Further, a synthetic resin-coated shaft 48 is extended and formed, and the synthetic resin-coated shaft 48 is connected to both end surfaces of the rotor 1f made of synthetic resin, and is integrally fitted with the shaft seal device.

The reference numerals are the same as those in FIG. 7 .

In the case of this embodiment, since the range L where the step is provided is very long, the axial length of the place where the spiral groove or wave groove is provided is very long, the surface area of the shaft is increased, and the bond between the shaft 41 and the synthetic resin rotor is enhanced. degree of connectivity. In addition, since the synthetic resin covers the shaft embedded in the water shaft seal, the rotor, shaft and other parts will not rust even if it is used in a water jet screw compressor.

Fig. 10 shows a partial cross-section of another embodiment of the screw rotor of the present invention, and the appended symbols are the same as those marked in Figs. 7-9.

In the case of the present embodiment, since the diameter of the shaft covering portion (where the spiral groove ₄₃ is provided) of the synthetic resin material constituting the shaft seal portion is compared to the shaft covering portion (where the spiral groove 43 is provided) of the synthetic resin material forming the rotor 1f The diameter of the place) should be thinner, so providing a plurality of steps 47 between the two can ensure the thickness of the synthetic resin material forming the shaft seal, and can prevent the resin material from cracking.

In addition, since the groove depth of the helical groove ₄₃₁ is made shallower than that of the helical groove 43, cracks do not occur in the synthetic resin material forming the shaft seal portion.

The above-mentioned grooves are not limited to spiral grooves, and the effect is the same even if wave-shaped grooves are provided.

In this embodiment, because the diameter of the shaft covering part (where the helical groove 43 is provided) is relatively large, and the axial length of the place where the helical groove is provided is long, the surface area of the shaft is increased, and the connection strength between the shaft 41 and the synthetic resin can be enhanced.

FIG. 11 shows a partial section of an embodiment different from the above, and the reference numerals are the same as those marked in FIGS. 7 to 10 .

This embodiment can also be said to be a modification of the rotor shaft shown in FIG. 10. The shaft covering portion of the synthetic resin material on the rotor is formed by a gentle curve, and an expansion portion is provided at the center of the shaft 41 in the longitudinal direction. 41 includes the entire central axis 38 .

On the circumferential surface of the shaft covering portion covered with synthetic resin, wave-shaped or spiral grooves 43 are provided on the entire surface.

In this embodiment, since the axial force applied to the rotor 1f is dispersedly supported by the arcuate surface of the center shaft 38, there is no stress concentration and cracks in the resin material can be reduced.

Although not shown in the figure, the shaft 41 is made by casting. If the shaft 41 is covered with synthetic resin, the surface of the casting remains intact (but the molding sand attached to the surface must be completely removed), and the shaft 41 covered with the resin material is processed by machining. If the surface of the shaft is not covered by the resin material, the resin enters the unevenness of the casting surface of the shaft covered with the resin material, which can strengthen the connection structure between the shaft and the rotor, and can also save processing man-hours.

Effect of the present invention is as follows:

1st or 2nd, because the rotor and shaft of the helical rotor adopt a combined structure, if the size of the rotor is the same, the rotor can be processed in the same processing process, so the productivity can be improved, the processing quality can be maintained stable, and the parts management is also easy. . In addition, due to the simple shaft connection form, the same rotor can be used in various machines with different shaft lengths, without wasting the material of the screw rotor, and it does not require many man-hours in manufacturing and processing, which solves the problem of high cost. Since the shaft can be disassembled, the installation is easy, and the shaft can be made short, so the forming machine can be miniaturized. Furthermore, as long as one type of shaft is processed, it can also be applied to other models, so the manufacturing cost can be greatly reduced. In addition, even if the shaft has to undergo surface treatment and other complicated manufacturing processes, since the component itself is smaller than the rotor, handling is easy and workability is also good. Thirdly, in addition to the first or second effects, assembly errors of the rotor and the rotor shaft can be prevented, common processing parts can be realized, and the manufacturing cost can be further reduced.

No. 4 and No. 5, plus the effect of any one of No. 1 to No. 3, because the central shaft is covered with synthetic resin, as a rust prevention measure for the shaft, it is easy to replace only the necessary Partial anti-rust treatment or surface treatment, it is also easy to use corrosion-resistant materials.

Sixth, in addition to the effect of any one of the first to fifth, since the vent hole is perforated, the vent hole penetrates from the insertion hole recessed on the rotor shaft or the central shaft to the shaft end on the opposite side, Since the shaft can be inserted smoothly when the shaft is connected, the insertion operation can be easily and reliably performed, and the temperature difference between the operation and stop of the recessed part can cause air circulation (breathing).

7th and 8th, plus any of the effects of 1st to 6th, because the linear expansion coefficient of the material embedded in the central axis is smaller than that of the embedded shaft, it is produced by compression The effect of the heat conduction is to make the matching hoop tighter, so that it can keep the matching state for a long time.

The 9th, the present invention is owing to be provided with the helical groove or wave groove that forms with smooth curve connecting peak portion and groove portion cross-section on the circumferential surface of the shaft that synthetic resin covers, except can relax the stress concentration of rotor junction, can prevent from In addition to the occurrence of cracks on the bottom of the teeth facing the grooves of the helical rotor, the separation between the shaft and the rotor (synthetic resin part) can be prevented, and the connection state can be strengthened and maintained for a long time.

Tenth, since the shaft is provided with a step or expansion part, the axial movement of the rotor is constrained. Even if there is a separation between the shaft and the rotor for some reason, the inner surface of the casing and the end surface of the rotor will not change during the operation of the compressor. Damage accidents such as contact and sintering may occur.

Eleventh, in the case of water-jet screw compressors, the parts in contact with water will not rust at all, improving the reliability of the shaft seal device, and the discharged air will not be mixed with rust and oil. In addition, since the deterioration of the lubricating oil caused by water mixing into the lubricating oil and the occurrence of emulsification can be prevented, the life of the bearing can be improved.

Twelfth, even if the material of the shaft is steel or cast iron, the surface of the shaft does not need to be electroplated or coated for anti-rust treatment. In addition, the processing time can be shortened compared with the existing equipment, and an inexpensive screw rotor can be manufactured.

Thirteenth, the screw rotor of the present invention is not limited to the rotor used in the water-jet screw compressor, but also has the following effects: even as an oil-cooled screw compressor and an oil-free screw compressor, a screw vacuum pump or a screw expander, etc. The use of fluid machine rotors is also feasible.

Claims (13)

1. the axle construction of a helical rotor, it is characterized in that: in the helical rotor of screw fluid machine, comprise the rotor that is formed with helical tooth and protrude in the central shaft of the outer end of at least one side on this rotor axis, the outer end of this central shaft is provided with step, is equipped with the path axle, and the rotor shaft of system in addition that will be concaved with embedded hole is embedded in outward and carries out axle connection on this path axle.

2. the axle construction of a helical rotor, it is characterized in that: in the helical rotor of screw fluid machine, be concaved with embedded hole in the outer end of this central shaft of central shaft that comprises the rotor that is formed with helical tooth and protrude in the outer end of at least one side on this rotor axis, and the rotor shaft of system in addition that will be equipped with the path axle is embedded in and carries out axle connection in this embedded hole.

3. helical rotor axle construction as claimed in claim 1, it is characterized in that: path axle (5,5a) be based in the central shaft (3 of above-mentioned rotor (1), 3a), respectively from the path axle (5, starting point 5a) (26,26b) and outermost end (27,27a) (2, length 2a) all is designed to essentially identical size in this two axial ends to rotor end-face.

4. helical rotor axle construction as claimed in claim 2, it is characterized in that: the path aixs cylinder is located on the above-mentioned centre of rotor axle, embedded hole (10,10a) be arranged with in the central shaft (3 of described rotor (1), 3a), respectively from the starting point of described embedded hole (28,28a) and inner terminal (29,29a) (8, length 8a) all is designed to essentially identical size in the two axial ends of this rotor to rotor end-face.

5. as any 1 the described helical rotor axle construction in the claim 1 to 4, it is characterized in that: above-mentioned rotor makes thermosetting plastic rotor form as one with it around metal central shaft and makes.

6. the axle construction of a helical rotor is characterized in that: in the helical rotor of screw fluid machine,

Being coated with around on the metal shaft of synthetic resin, is to be provided with step on central shaft at least, and,

The surface that covers the axle of above-mentioned synthetic resin is provided with spiral chute or waveform groove,

With profile line form above-mentioned spiral chute or waveform groove, by the section that the plane that comprises shaft centre line is dissectd, this profile line forms with the joint that smooth peak shape curve connects the circular-arc groove face of circular-arc groove face and adjacency,

Above-mentioned spiral chute, its sense of rotation is opposite with the sense of rotation of helical rotor, and is formed with plastic rotor around metal axle.

7. the axle construction of a helical rotor is characterized in that: in the helical rotor of screw fluid machine,

Be coated with around on the metal shaft of synthetic resin, be provided with step and/or protuberance, and,

The surface of the axle of above-mentioned coverage of synthetic resin is provided with waveform groove or spiral chute,

With profile line form above-mentioned waveform groove or spiral fluted, by the section that the plane that comprises shaft centre line is dissectd, this profile line forms with the joint that smooth peak shape curve connects the circular-arc groove face of circular-arc groove face and adjacency.

8. helical rotor as claimed in claim 6 is characterized in that: in the axle surface coverage that is connected with plastic rotor synthetic resin is arranged, form between the axle envelope portion of the axle envelope portion of suction side of axle and discharge side, axial surface with synthetic resin at least.

9. helical rotor as claimed in claim 7 is characterized in that: in the axle surface coverage that is connected with plastic rotor synthetic resin is arranged, form between the axle envelope portion of the axle envelope portion of suction side of axle and discharge side, axial surface with synthetic resin at least.

10. as claim 6 or 8 described axle construction, it is characterized in that: above-mentioned rotor is to use the surface that covers, forms its central shaft periphery with rotor with the synthetic resin of material.

11. as claim 1 to 4,8, any 1 described axle construction of 9, it is characterized in that: basic for the place, axle center is equipped with vent at above-mentioned rotor shaft, this vent is from being arranged with embedded hole perforation on this rotor shaft or central shaft to the axle head of its opposite side.

12. as claim 1,3,4,8, any 1 described axle construction of 9, it is characterized in that: the material of the rotor shaft that the outer embedding of centre of rotor axle connects is a metallic material, and this metallic material has the linear expansion coeffcient character littler than the linear expansion coeffcient of this central shaft material therefor.

13. as claim 2 to 4,8, any 1 described axle construction of 9, it is characterized in that: the used material of centre of rotor axle is a metallic material, this metallic material have linear expansion coeffcient than with the little character of linear expansion coeffcient of the embedded rotor shaft that is connected of this central shaft.

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