JP2002046030A - Manufacturing method of bevel gear, bevel gear material and bevel gear - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To improve the manufacturing efficiency of a large gear of a hypoid gear and to improve the fatigue strength. SOLUTION: A rough material is forged to form a gear material 30. At this time, the end 92 of the tooth surface 84 of the gear material 30
Etc., and the tooth bottom 110 is attached to the tooth bottom 1
14, a concave curved surface 116, and a draft surface 112. In the finishing process, if the machining allowance 104 is removed by cutting, the tooth surface 102 is smoothly connected to the concave curved surface 116,
The shape and size of each part are selected so that a part of the round part of the end part 92 remains and functions as a chamfer. Concave surface 11
6 and the tooth bottom surface 114 have a skin portion formed at the time of forging, and have no steps, so that fatigue strength is improved. In addition, it is not necessary to chamfer the end portion 92 or the like with a dedicated processing device, thereby improving manufacturing efficiency.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a hypoid gear,
The present invention relates to a method for manufacturing a bevel gear such as a bevel gear, a bevel gear material, and a bevel gear.

[0002]

2. Description of the Related Art When manufacturing bevel gears, the periphery of teeth is usually machined, such as rough gear cutting, finishing gear cutting, chamfering of tooth end faces, and chamfering of tooth tip faces. It has also been proposed to manufacture an umbrella-shaped gear material having a shape corresponding to the coarse-geared intermediate product by forming such as forging, but this method is a change from the rough gear-cutting process to the forming process as it is. The finishing gear cutting, the chamfering of the tooth end face, the chamfering of the tooth tip face, etc. are performed in the conventional manner. As described above, in order to chamfer the tooth end surface and the tooth apex surface of the coarsely cut intermediate product and the formed material by machining, a special processing machine and a cutting process are required, and the bevel gear This has contributed to an increase in manufacturing costs.

[0003] In addition, the bottom of a bevel gear having a tooth surface formed by rough tooth cutting and finishing tooth cutting has a tooth bottom formed by rough tooth cutting and a tooth surface formed by finishing tooth cutting. A step remains at the boundary. This point is the same in the manufacturing method in which the rough gear cutting process is directly changed to the molding process. The tooth bottom is a portion on which a large stress acts when the bevel gear is used, and the step existing at the tooth bottom adversely affects the strength of the bevel gear.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has been made in view of the above circumstances by improving a method of manufacturing a bevel gear and reducing manufacturing costs and / or increasing strength of the bevel gear. According to the present invention, a bevel gear manufacturing method, a bevel gear material, and a bevel gear according to the following embodiments are obtained. As in the case of the claims, each aspect is divided into sections, each section is numbered, and if necessary, the other sections are cited in a form in which the numbers are cited. This is for the purpose of facilitating the understanding of the present invention and should not be construed as limiting the technical features and combinations thereof described in the present specification to those described in the following sections. . Further, when a plurality of items are described in one section, the plurality of items need not always be adopted together. It is also possible to select and adopt only some of the items.

(1) A forming process of forming a bevel gear material in which at least one of the large-end acute angle portion, the small-end acute angle portion, and both edges of the tooth tip surface of each tooth is formed by molding. When,
The bevel gear material manufactured in the forming process is machined, and the rounded portion is left unprocessed, leaving a bevel on the large end, a bevel on the small end, and a bevel on the tooth tip. And a machining step of manufacturing a bevel gear functioning as at least one of the following (claim 1).
In this way, the rounded portion is formed at the corner including at least one of the large-end acute angle portion, the small-end acute angle portion, and both edges of the tooth tip surface of the bevel-shaped gear material. If at least a part of the portion is left unprocessed and functions as at least one of chamfering the large-end acute angle portion, the small-end acute angle portion, and the tooth tip chamfer, at least a part of the chamfering machining process Can be omitted, and the manufacturing cost of the bevel gear can be reduced. In addition, it is also possible to form a round part at the obtuse angle part in both ends of each tooth, and to function as a chamfer. INDUSTRIAL APPLICABILITY The present invention is particularly suitable for manufacturing a hypoid gear or a bevel gear with a complicated tooth surface shape and high precision, but is also applicable to manufacture of a normal bevel gear having no bent teeth. (2) A bevel-shaped gear material having a curved surface that smoothly connects a tooth surface and a tooth bottom surface formed by cutting a portion of the tooth surface by machining to remove the tooth margin. A shaping step for manufacturing by shaping, and forming a tooth surface by cutting off the margin of the bevel gear material manufactured in the shaping step by machining, leaving the curved surface and the tooth bottom surface unprocessed, A method of manufacturing an umbrella gear including a machining step of manufacturing an umbrella gear in which the remaining curved surface and root surface are smoothly connected to the machined tooth surface (claim 2). In this way, the machining of the bottom surface of the bevel gear is omitted, and if a curved surface that smoothly connects the bottom surface and the tooth surface formed by machining is formed in the bevel gear material, Both reduction in manufacturing cost and increase in strength of the bevel gear can be achieved. The manufacturing cost can be reduced by omitting the machining of the root surface, and the root portion in which the tooth surface and the root surface are smoothly connected by the curved surface has a better stress concentration than the root portion having the step. It is avoided and the strength of the bevel gear is improved. In addition, since the root surface and the curved surface are not machined, in the case of forging or the like, a dense metal structure near the surface of the molded product is left as it is, and the fatigue strength is superior to the machined one. A bevel gear is obtained. Said
The feature of the item (1) can be applied to the bevel gear manufacturing method of this item. (3) The method for manufacturing a bevel gear according to the above mode (1) or (2), wherein the forming step is a step of forging the raw material for the bevel gear. (4) The bevel gear is a large gear of a hypoid gear.
The method for manufacturing a bevel gear according to any one of the above modes (1) to (3). (5) A bevel-shaped gear material manufactured by molding and formed into a bevel-shaped gear by machining, wherein at least one of a large-end acute angle portion, a small-end acute angle portion, and both edges of a tooth tip surface of each tooth. Finally, a bevel-shaped gear material that is left as it is when formed into a product, and is formed with a rounded portion instead of a chamfer at the large end acute angle portion, a small end acute angle portion chamfer and a tooth tip chamfer of each tooth. (6) While the tooth surface is provided with a margin, the tooth root is not provided with a margin, and the tooth surface formed by cutting the margin by machining and the teeth which are not machined are left. A material for bevel gears that has a curved surface that smoothly connects to the bottom surface and is manufactured by molding. the above
The feature of the item (5) can be applied to the bevel gear material of the item. (7) A tooth bottom surface, a concave surface smoothly connected to the tooth bottom surface, a draft surface smoothly connected to the concave surface and having a draft angle, and a material with an allowance for a tooth surface of a product. A bevel gear material made by molding, comprising a tooth surface that is connected to the draft surface (Claim 3). If the material tooth surface is machined by the cutting allowance to form the tooth surface, the tooth surface is smoothly connected to the non-machined tooth bottom by a non-machined curved surface. . In addition, the draft surface plays a role of facilitating removal of the material from the mold when the material for the bevel gear is formed, and then disappears due to machining of the material tooth surface. The bevel gear material according to this mode is particularly suitable for implementing the method for manufacturing a bevel gear according to the above mode (2). The feature of the above item (5) can be applied to the bevel gear material of this item. (8) The bevel gear is machined, but at least one of the large-end acute angle portion, the small-end acute angle portion, and the chamfers at both edges of the tooth tip surface are not machined ( Claim 4). (9) A bevel gear having a tooth surface, a root surface, and a curved surface smoothly connecting the tooth surface and the root surface, the tooth surface being machined, and the tooth bottom and the curved surface being not machined (claim) Item 5).

[0006]

1 and 2 show a gear machining system suitable for carrying out a gear machining method according to an embodiment of the present invention. The present gear processing system includes a forging device 10 for manufacturing a gear material by forging a rough material, and a finishing device 12 for performing finishing by performing a cutting process on a formed gear material. This gear machining system is for machining a large gear of a hypoid gear having a right-hand twisted tooth. Forging device 10
Is an example of the bevel-shaped gear material according to the present invention. The hypoid gear (gear gear) which has been finished by the finishing device 12 and further subjected to heat treatment, lapping, etc. It is an example of a bevel gear according to the present invention.

The forging device 10 is for producing a gear material, and the structure itself is well known, so that it will be briefly described. The forging device 10 includes an upper die 16 and a lower die 18 which cooperate with each other to form a forging die 14, and a die driving device 20 for operating the upper die 16 and the lower die 18 with a required die load. . In the upper die 16 and the lower die 18, a shape to be processed by forging a rough material to be formed into a gear material is engraved as an impression.
The shape of the gear material is divided into two by one plane perpendicular to the central axis, and the divided shapes are engraved on the upper mold 16 and the lower mold 18 respectively. Forging can be performed in any of hot, warm and cold.

In the forging apparatus 10 configured as described above, first, in a state where the upper die 16 and the lower die 18 are opened, a rough material having a rough land shape is set therein. Next, the upper die 16 and the lower die 18 are repeatedly approached and separated by the stamping device 20, whereby the rough material undergoes appropriate plastic deformation to be formed into a gear material. Although not shown, the stamping device 20 includes the upper die 16 and the lower die 1.
A guide portion for guiding approach and separation from the upper die 8 is provided to prevent the upper die 16 and the lower die 18 from being misaligned.

Next, based on FIG.
Will be described. The finishing device 12 creates a gear by machining the tooth surface of the gear material 30 formed by the forging device 10. This finishing device 12 is disclosed in Japanese Patent Application
Since it is almost the same as that described in -105185, it will be briefly described. In the finishing machine 12, a tool headstock 34 and a workpiece headstock 36
Are supported so as to be relatively movable. The tool headstock 34 includes a first moving table 38 that moves in a first direction (hereinafter, referred to as an X-axis direction) parallel to a horizontal plane formed on the apparatus main body 32. Column 4 on the first moving table 38
0 is erected and formed on the side of the column 40 in the vertical direction.
A housing 48 supporting a tool spindle 46 is moved in the Y-axis direction by a pair of guide rails 42 extending in the (Y-axis direction) and a lifting motor 44. The housing 48 is
The tool spindle 46 is rotatable around the axis and in the axial direction.
(In the X-axis direction), and a rotary drive motor 50 for rotating the tool spindle 46 and an axial drive motor 52 for moving in the axial direction are provided. The lifting motor 44, the rotary drive motor 50, and the axial drive motor 52 are controlled by a control device (not shown) so that the tool spindle 46 moves in the X-axis direction and the Y-axis direction while rotating around the axis. Can be.

On the other hand, the work headstock 36 is provided on the apparatus main body 32 with a second movable base 60 provided so as to be relatively movable in a Z-axis direction orthogonal to the X-axis direction in a horizontal plane, and a second movable base 60 thereof. A turning table 62 provided on the moving table 60 and capable of relative rotation about a vertical axis; and a drive motor 64 provided on the apparatus main body 32 and a turning motor 66 provided on the turning table 62 for moving respectively. Can be A work spindle 68 is rotatably supported on a turntable 62 around a horizontal axis, and is rotated by a spindle rotation motor 70.
As a result, the work spindle 68 can rotate around a horizontal axis, move in the Z-axis direction, and pivot around a vertical axis. According to the finishing device 12, by combining the above four motion elements and the rotation of the respective spindles 46 and 68 around the axis, both the forming gear cutting and the generating gear cutting can be performed. . The gear material 30 formed by the aforementioned forging device 10 is
8 and perform machining to cut the tooth flank of the gear.

Next, the shape of the gear material 30 formed by the forging device 10 will be described in detail. In FIG.
For ease of understanding, only one tooth of the gear blank 30 is shown. The shape of the gear material 30 substantially matches the shape of the large gear of the hypoid gear, which is a finished product, and the shape of such a large gear is generally well known, so that illustration and detailed description thereof will be omitted.

As shown in FIG. 3, the teeth 78 of the gear material 30 are located on the front side (the left side of the teeth in the figure) in the rotation direction (clockwise with respect to the center of rotation located in the back of the teeth in the figure). It has a concave concave tooth surface 80 of a central concave position and a convex convex tooth surface 82 of a central concave surface on the rear side, and between the two tooth surfaces 80, 82, is continuous with the tip of each tooth surface 80, 82. The tip surface 84 is formed. The teeth 78 further have a small end side face 86 facing the center of rotation (rear side in the figure) of the gear material 30 and a large end side face 8 facing the outside of rotation (front side in the figure).
8 is provided. In the gear material 30, a round portion having roundness is formed at the boundary between the surfaces 80 to 88 of the teeth 78 formed as described above. Specifically, both end portions 90 and 92 in the width direction of the tooth tip surface, a large end side acute angle portion 94 which is a boundary portion between the concave side tooth surface 80 and the large end side end surface 88, and a convex side tooth surface 82 A rounded portion is formed at a small end side acute angle portion 96 which is a boundary portion with the small end side end surface 86. Also, the large end side end face 8
Large-end obtuse angle 98 which is the boundary between the upper surface 8 and the convex tooth surface 82
Also, a rounded portion is formed at the small end obtuse angle portion 100 which is the boundary between the small end side end surface 86 and the concave side tooth surface 80. The cross-sectional shapes of these rounded portions are defined by circular arcs having a constant radius, and tooth surfaces 80 and 82 and a tooth tip surface 84 located on both sides of each rounded portion, a large end side end surface 88 and a concave side tooth surface 80, Small end side end surface 86 and convex side tooth surface 82, large end side end surface 88 and convex side tooth surface 82,
And, the small end side end surface 86 and the concave side tooth surface 80 are formed so as to be smoothly connected. These rounded portions have a size that functions as a chamfer of the large gear of the hypoid gear, with a part of the rounded portion remaining even after the machining allowance is removed later by finishing.

As shown in FIGS. 4 and 5, the concave tooth surface 80 of the gear material 30 is formed on the tooth surface 102 of the product gear.
Be one allowance 104 is attached, it is formed in parallel to inclined slope alpha ₁ tooth surface 102 to be formed by finishing device 12. The thickness of the allowance 104 is set to a thickness sufficient to remove the skin portion of the entire concave tooth surface 80 formed by forging by cutting. In the drawing, the tooth surface 102 of the gear as a product is shown by a two-dot chain line.

Next, the shape of the tooth bottom 110 of the gear blank 30 will be described. As shown in an enlarged manner in FIG. 5, the tooth bottom 110 is formed continuously with the concave tooth surface 80 and has a draft α _2.
And a tooth bottom surface 114, and a concave curved surface 116 that smoothly connects the draft surface 112 and the tooth bottom surface 114. The draft α ₂ is a gradient provided to enable the gear material 30 to be removed from the forging die 14 after forging. The shape of the root 110 is substantially symmetric with respect to the longitudinal direction of the root 110, and the portion of the root 110 on the convex tooth surface 82 side and the convex tooth surface 8
Both are formed substantially similarly. Draft surface 12
0 and the tooth bottom surface 114 are smoothly connected by the concave curved surface 122, and the tooth surface 124 of the large gear is provided with the allowance 126 to be the convex tooth surface 82.

After the gear cutting reference surface, the reference hole and the like of the thus formed gear material 30 are cut by a lathe,
Finishing is performed by the finishing device 12. The gear material 30 is attached to the workpiece spindle 68, and a face milling cutter 130 as a gear cutting tool is attached to the tool spindle 46, so that the gear material 30 and the cutter 130 are given relative motion required for gear cutting. And the allowances 104, 126
Are removed by cutting to form tooth surfaces 102 and 124. At this time, if the allowances 104 and 126 are removed, the draft surfaces 112 and 120 and the portions of the concave curved surfaces 116 and 122 connected to the draft surfaces 112 and 120 disappear, and the tooth surface 10
2 and 124 are just connected to the concave curved surfaces 116 and 122 smoothly. Allowance 104, 126, draft surface 11
2, 120 and concave curved surfaces 116, 122 are so selected. Since it is not desirable that even a slight step is formed at the boundary between the tooth surfaces 102, 124 and the concave curved surfaces 116, 122, the dimensional tolerance of the gear material 30 is limited to the draft surface 112 of the concave curved surfaces 116, 122. , 120
Is desirably determined so that a portion that leads to remains slightly.

FIG. 6 shows a conventional manufacturing method for comparison with the manufacturing method of the above-described hypoid gear large gear according to the present invention. Conventionally, a rough tooth surface 200 having a cutting allowance 202 and inclined at an inclination α ₁ is formed at the time of rough machining, and a tooth surface 204 is formed by machining the rough tooth surface 200 only at the machining allowance 202 at the time of finish machining. . In this processing method, at the time of roughing, the tooth bottom portion 206 is formed by the tooth bottom surface 208 and the concave curved surface 21 that smoothly connects the tooth bottom surface 208 to the rough tooth surface 200.
0 at the time of finish machining.
Cutting is performed only on 0, and the tooth bottom portion 206 is kept in the state at the time of roughing. Therefore, a margin 202 is provided at the boundary between the part where the finish processing has been performed and the part where the rough processing has been performed.
As a result, a step portion 212 having a size of a minute is formed, and the step portion 212 adversely affects the strength (particularly, fatigue strength) of the hypoid gear (large gear). Step 21
The stress concentration occurs at the corner of No. 2 and the fatigue strength is reduced.

On the other hand, in the hypoid gear (gear gear) manufactured by the manufacturing method of the present embodiment, the step portion 212 does not exist, so that the fatigue strength (durability) of the hypoid gear (gear gear) is remarkably improved. In addition, tooth bottom 1
Since the tooth bottom surface 114 and the concave curved surface 116 of the ten are not cut and are formed by forging, the fatigue strength is improved from this point, and the time required for the cutting is shortened. Further, as shown in FIG. 5, typically, one end 92 of the tooth tip surface, both ends 90, 92 of the tooth tip surface 84, a large-end acute angle portion 94, a small-end acute angle portion 96, and a large-end acute angle portion 96. The rounded portions formed on the side obtuse angle portion 98 and the small-end side obtuse angle portion 100 are partially left at the time of the finishing process and are left forged and function as chamfers. Time is reduced. Conventionally, the finishing time of the hypoid gear (large gear) is significantly shortened, and the equipment cost is reduced, as compared with the case where the processing has been conventionally required by a dedicated processing device.

In this embodiment, the rounded portions are formed at all of the acute angles 94 and 96 at the large and small ends, the obtuse portions 98 and 100, and both ends 90 and 92 of the tooth tip surface 84. If at least one of them has a rounded portion, the effect of the present invention can be obtained in that portion. For example, a rounded portion is formed only at the large end side acute angle portion 94 and the small end side acute angle portion 96, and the other obtuse angle portions 98 and 100 where the end face and the tooth surface intersect at an obtuse angle are particularly rounded. No part is formed. It is sufficient that these portions have roundness necessary for manufacturing or use of the forging die 14, and it is not necessary to form a round portion for functioning as a chamfer.

Further, the shape of each rounded portion is not limited to a shape defined by an arc having a constant radius, and may be, for example, a set of curves whose radius gradually changes, or having two or more different radii. It may be formed as a set of arcs. A typical example of the latter is a curved surface composed of a central portion defined by an arc having a large radius of curvature and two sides defined by arcs having a small radius of curvature on both sides thereof.

The embodiment described above is merely an exemplification of the present invention, and the present invention relates to the above-mentioned [Problems to be solved by the invention,
Problem solving means and effects], and various modifications and improvements can be made based on the knowledge of those skilled in the art.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically showing a forging device for manufacturing a gear material according to an embodiment of the present invention.

FIG. 2 is a plan view schematically showing a finishing apparatus that manufactures a gear by performing finishing on the gear material.

FIG. 3 is a perspective view showing a part of the gear material.

FIG. 4 is a side sectional view showing another part of the gear material.

FIG. 5 is an enlarged side sectional view showing a main part of the gear material shown in FIG. 4;

FIG. 6 is a side sectional view for explaining a conventional gear manufacturing method.

[Explanation of symbols]

10: Forging device 12: Finishing device 1
4: Forging die 80: Concave-side tooth surface 82: Convex-side tooth surface 102, 124: Tooth surface 104, 126: Allowance 110: Root portion 112, 120: Draft surface 114: Bottom surface 116, 122: Concave curved surface

Continued on the front page F term (reference) 3C025 DD04 DD12 3J030 BA02 BB08 BC02 BC06 BC10 CA10 4E087 AA08 AA10 CA11 DB04 DB24 HA03

Claims (5)

[Claims] 1. A forming step of manufacturing a bevel gear material having a rounded portion formed in at least one of a large-end acute angle portion, a small-end acute angle portion, and both edges of a tooth tip surface of each tooth by molding. The bevel-shaped gear material manufactured in the forming process is machined, and the rounded portion is left unprocessed to be chamfered at the large-end acute angle portion, the small-end acute angle portion, and the tooth tip. A manufacturing process of manufacturing a bevel gear functioning as at least one of chamfers. 2. A bevel gear having a tooth surface and a curved surface which forms a curved surface which smoothly connects the tooth surface and the tooth bottom surface formed by cutting off the tooth margin by machining. A forming step of manufacturing the material by molding, and forming a tooth surface by cutting off the allowance of the bevel gear material manufactured in the forming step by machining.
A machining step of manufacturing a bevel gear in which the curved surface and the root surface are left unprocessed, and the remaining curved surface and the root surface are smoothly connected to the machined tooth surface. Manufacturing method of bevel gear. 3. A tooth bottom surface, a concave surface smoothly connected to the tooth bottom surface, a draft surface smoothly connected to the concave surface and having a draft angle, and an allowance is provided for a tooth surface of the product. A bevel gear material manufactured by molding, comprising: a material tooth surface which is connected to the draft surface. 4. The tooth surface of each tooth is machined, but at least one of the large-end acute angle portion, the small-end acute angle portion, and the chamfers at both edges of the tooth tip surface is not machined. Bevel gears featured. 5. A tooth surface, a tooth bottom surface, and a curved surface for smoothly connecting the tooth surface and the tooth surface, wherein the tooth surface is machined, and the tooth surface and the curved surface are not machined. Bevel gear.