JP4000861B2 - Manufacturing method of stepped shaft - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention has stepped portions having different diameters in the axial direction, and gear teeth (straight teeth, helical teeth, bevel gears, etc.) and splines are provided on the outer periphery of at least the large-diameter stepped portion on one end side in the axial direction. The present invention relates to a method for manufacturing a stepped shaft.
[0002]
[Prior art]
As a conventional manufacturing method of the stepped shaft as described above, after rough forming by cold or hot forging, the entire surface is machined, and the tooth portion is machined by a hobbing machine or / and a broaching machine. Manufactured.
[0003]
In addition, a manufacturing method is also known in which the rough forming and the tooth forming shape are formed by a press machine.
[0004]
[Problems to be solved by the invention]
In the former of the above-described conventional manufacturing method, since different forging and machining processes are required, there is a problem that the setup for the process increases and the cost increases.
[0005]
In the latter case, since both dies facing each other in the axial direction are single-acting, the tooth profile such as gears is plastically processed on the outer periphery of the large-diameter portion having a large step with respect to the other portions. It was difficult.
[0006]
The present invention is considered in view of the above, and the tooth profile on the outer periphery of the large-diameter portion can be formed by plasticity, and at low cost, each of the plurality of tooth profiles provided in the axial direction is shaken and coaxial. It is an object of the present invention to provide a manufacturing method of a stepped shaft that can be manufactured with high accuracy.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, a method for manufacturing a stepped shaft according to the present invention includes stepped portions having different diameters in the axial direction, and at least a tooth profile on the outer periphery of a large-diameter stepped portion on one end side in the axial direction. In the stepped shaft forming method, the shape of the stepped shaft is the same as the outer shape of the stepped shaft, and the shape of the lower mold cavity is substantially similar to the shape of the lower mold cavity disposed with the large diameter portion opened upward. In addition, a molding material in which the outer diameter of the tooth forming part is smaller than the inner diameter of the tooth forming part of the lower mold cavity is inserted so that the upper end of the molding material protrudes from the lower mold cavity. The entire upper end of the molding material consists of a main punch formed in a shaft shape, an inner punch formed in a cylindrical shape surrounding the main punch, and an outer punch formed in a cylindrical shape surrounding the inner punch, and Each enabled individually At the mold, they were pressed by downward integrally shaped, and then enlarged deforming the part to press the axial portion of the molding material moves downward only the main punch under the pressing conditions of the inner punch and the outer punch Then, the outer peripheral portion was filled in the tooth forming mold and the tooth profile portion was roughly molded, and then the upper surface of the molding material was pressed with an inner punch that was allowed to move upward when a force stronger than the set pressure was applied from the lower surface. In this state, the main punch and outer punch are moved down, and the tooth profile part is finished by pressing the tooth profile part including the outside of the tooth tip part from the inside of the tooth bottom part of the molding material outside the inner punch together with the shaft center part of the molding material. It was made to mold.
[0008]
[Action]
The molding material inserted into the lower mold is pressed into the lower mold by pressing it with the upper mold, and then roughly molded, and then the shaft at one end of the molding material is pressed with the main punch. As a result, the concave portion by the main punch is formed in this portion, the meat of the concave portion moves in the direction perpendicular to the axis, and the stepped portion of this portion is expanded to fill the lower tooth-forming mold. The tooth profile is roughly formed. The coarsely formed tooth portion is pressed in the axial direction by an outer punch that moves downward on the outer side of the inner punch while the upper end of the molding material is pressed by the inner punch at a predetermined pressure, and is finish-molded. At this time, the inner axial center part of the inner punch is also pressed by the main punch that moves downward.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows an example of a press machine for carrying out the method of the present invention. In the figure, 1 is a bolster, 2 is a slide, 3 is a lower mold device fixed to the upper surface of the bolster 1, and 4 is fixed to the lower surface of the slide 2 The upper die device 5 is a guide post for guiding the upper device 4 in the vertical direction with respect to the lower die device 3.
[0010]
The lower mold apparatus 3 includes a die holder 7 fixed to the bolster 1 by a fixing member 6, a lower mold 8 slidably fitted in the die holder 7 in a vertical direction, and a lower mold 8. A set base 9 set at a predetermined height in the die holder 7, a lifting plate 11 supported by a support base 11 a at a position facing the lower surface of the lower mold 8, and a lower set base of the lower mold 8 The lower molding apparatus 12 is disposed at 9 parts and closes the lower side of the lower mold cavity of the lower mold 8, and a clamp member 13 that fixes the lower mold 8 to the die holder 7. The elevating plate 11 is raised by the lift rod 10. The set table 9 includes a ring plate 9a, a mandrel plate 9b, a plate 9c, and a ring plate 9d. The clamp members 13 are provided at a plurality of locations in the circumferential direction of the die holder 7. The engagement / disengagement of the clamp member is performed manually or by a known appropriate means such as a hydraulic cylinder.
[0011]
The lift rod 10 is connected to a lower mold lift cylinder (not shown). The lower molding device 12 is inserted into the lower part of the lower mold cavity of the lower mold 8 and includes a lower molding die 14 supported by the set table 9 and a hollow part molding pin 17. The molding die 14 is moved up and down by a lower molding cylinder (not shown) via a rod 15 and a lower support 16. The hollow portion molding pin 17 is supported on the set base 9 side.
[0012]
The lower mold 8 has a multilayer structure by shrink fitting, and the inner lower mold member formed with the cavity can be replaced by wear or the like.
[0013]
The upper die device 4 includes a main punch 18 formed in an axial shape, an inner punch 19 formed in a cylindrical shape surrounding the main punch 18, and an outer punch 20 formed in a cylindrical shape surrounding the inner punch 19. Have. These punches 18, 19, and 20 are slidably fitted. The main punch 18 is integrally coupled to the slide 2 via the plate 21 and the frame member 22, and the inner punch 19 is coupled to the piston rod of the inner cylinder 24 provided on the slide 2 via the intermediate member 23. Further, the outer punch 20 is coupled to a piston rod of an outer cylinder 26 provided on the slide 2 through another intermediate member 25.
[0014]
In this press machine, the lower die 8 in the lower die device 3 is fixed to the die holder 7 by fitting the clamp member 13 after fitting into the die holder 7.
[0015]
In this state, in the lower mold cavity of the lower mold 8, the molding material 27 molded in a shape to be fitted in the lower mold cavity in advance in the previous step is placed with the upper end portion thereof lowered as shown in FIG. Fit from the mold cavity . Next, the slide 2 is moved downward and the upper portion of the molding material 27 is pressed by the main punch 18, the inner punch 19 and the outer punch 20 to mold the molding material 27 into a shape along the cavity of the lower die 8.
[0016]
2 to 6 show a process of molding the partially hollow stepped shaft 28 shown in FIG. 7 from the molding material 27. The stepped shaft 28 has first, second, third, and fourth step portions a, b, c, and d that are gradually reduced in diameter from one end side. A gear 29 and a first spline 30 are provided in one step portion a, and a second spline 31 is provided in a fourth step portion d located on the tip side. And it has the hollow part e open | released to the front-end | tip in the small diameter part.
[0017]
FIG. 2 shows a state in which the molding material 27 is inserted into the lower mold 8 of the lower mold apparatus 3. At this time, the lower die 8 is provided with a molding cavity for molding the stepped shaft 28, and the gear 29 of the stepped shaft 28 and the first and second splines 30, 31 are formed on the inner surface thereof. Corresponding molds 29a, 30a, 31a are provided. On the other hand, the molding material 27 can be inserted into the molding cavity, and is molded into a shape corresponding to the shape of the stepped shaft 28 by a material molding process described later. This molding material 27 is formed to have step portions a ', b', c ', b' corresponding to the step portions a, b, c, b of the stepped shaft 28 and a hole e 'in the shaft center portion. Yes. A portion of the first step a 'protrudes from the molding cavity by a predetermined height. The hollow portion forming pin 17 is inserted to a predetermined depth of the hole e ′.
[0018]
FIG. 3 shows the first molding step. The upper die device 4 is moved downward so that the punches 18, 19, and 20 thereof are integrated, and the first step portion a ′ of the molding material 27 is moved downward. Press the end face.
[0019]
As a result, the molding material 27 is pushed into the molding cavity, and by this process, the first step portion a ′ is molded into the first spline mold 30a and the tip portion of the fourth step portion d ′ is molded into the second spline. The first and second splines 30 and 31 are formed at the respective step portions by being extruded into the mold 31a.
[0020]
FIG. 4 shows the second molding step. Only the main punch 18 is moved downward from the state of the first molding step to press only the axial center portion of the first step a ′. As a result, the diameter of the first step portion a ′ is expanded outward in the direction perpendicular to the axis, and this portion is increased in thickness into the gear forming die 29a, and the gear 29 is roughly formed in the step portion a ′.
[0021]
At this time, the main punch 18 of the upper mold device 4 is moved downward together with the lower movement of the slide 2. On the other hand, the inner punch 19 and the outer punch 20 also move downward together with the slide 2, but in order to keep both the punches 19 and 20 at the position of the first step, the inner punch 19 and the outer punch 20 are moved upward at the same speed as the main punch 18 and over the same distance. Move. The upper end of the molding material 27 is held by the tips of the punches 19 and 20. Further, at this time, the lower mold 14 is supported on the set table 9 side, but at the time of lower molding, the lower mold 14 is moved up by the lower molding cylinder as necessary by lowering the lower mold 14. The tip part of the stepped shaft 28 is molded by moving upward.
[0022]
FIG. 5 shows a third molding step, in which the main punch 18 and the outer punch 20 are moved downward from the state of the second molding step. Thereby, the gear 29 is finish-molded. Also at this time, the inner punch 19 is kept at the same speed as the main punch 18 and the outer punch 20 in the downward movement, and is moved up over the same distance to be substantially stopped. The upper end of the molding material 27 is partially pressed by the inner punch 19, and when a force stronger than the set pressure is applied to this portion, the inner punch 19 moves upward and the force is released.
[0023]
FIG. 6 shows the fourth molding step, and the main punch 18 and the outer punch 20 are moved upward while the inner punch 19 is used as a stripper and kept at the position of the third step.
[0024]
Molding is completed in the fourth molding step, the upper mold device 4 is moved up, and then the lower support 16 is moved up to knock out the molded product. At this time, if the gear 29 is a straight gear, it is knocked out as it is, but if it is a helical gear, the molded product is knocked out while being rotated along the tooth trace.
[0025]
In addition, as shown in the figure, the molding material 27 used in the above-described embodiment is preliminarily molded into a stepped shaft shape. As an example of the processing method of the molding material 27, FIG. It shape | molds with the manufacturing method of the hollow stepped shaft shown in FIGS. 8-10 using the shown press machine. Needless to say, the molding of the molding material 27 is not limited to the method described below.
[0026]
In FIG. 8, reference numeral 35 denotes a mold apparatus for forming the molding material 27 of the stepped shaft 28, and the mold apparatus 35 includes a lower mold 36, an upper mold 37, an auxiliary lower mold 38, and a core metal 39. The lower die 36 includes a large-diameter portion mold 40 having an outer diameter of the large-diameter portion a of the molding material 27 as an inner diameter, a set hole 41 that supports the hollow material A on the back side (lower side) thereof, It has a shaft forming die 42 connected to the set hole 41. And the auxiliary lower mold | type 38 is set in the position facing the front-end | tip of the small diameter axial part b.
[0027]
The upper die 37 has an inner punch 37a whose outer diameter is sized to fit into the large-diameter portion forming hole 40 of the lower die 36, a main punch 37b slidably fitted inside the inner punch 37a, and an inner punch. The outer punch 37c is slidably fitted on the outer side of 27a, and these can be moved up and down individually.
[0028]
Next, a method for manufacturing the molding material 27 using the mold apparatus 35 will be described with reference to FIGS. FIG. 8 shows a set state of the hollow material A. The hollow material A is set in the set hole 41 of the lower die 36, and the core metal 39 is inserted into the hollow material A from the lower side to a predetermined depth. Further, the upper die 37 is in contact with the upper surface of the hollow material A. O ₁ is the set state position of the upper die 37.
[0029]
FIG. 9 shows a state in the middle of processing. The upper die 37 is moved down from O ₁ to L ₁ in which the first and second upper dies 37a and 37b are integrated, and the hollow material A is moved from above. Press. As a result, the hollow material A is extruded into the shaft portion molding die 42. Figure 10 shows a state where extruded small-diameter shaft portion b moves downward further by L ₂ the upper die 37. At this time, a depression is formed in the upper end portion of the hollow material A by pushing down the main punch 37b from the inner punch 37a. The diameter of the lower die 36 is increased to a shape along the large-diameter portion molding die 41, and the molding material 27 is molded. Moreover, the hole of a large diameter part is closed by the thickening of this part.
[0030]
In the embodiment described above, an example in which one end portion of the molding material 27 is pressed into a concave shape by the main punch 18 to expand the diameter of this portion is illustrated, but this portion is not necessarily concave, A shaft portion may be projected from the end portion of the large diameter portion, and the large diameter portion may be expanded and deformed by pressing this portion with the main punch 18.
[0031]
【The invention's effect】
According to the present invention, it has stepped portions with different diameters in the axial direction and has a hole with an open end in the axial center portion of the small-diameter portion, and at least on the outer periphery of the large-diameter stepped portion on one end side in the axial direction. This stepped shaft can be formed by plastic deformation of the tooth forming form on the outer periphery of the large diameter step part, and this kind of stepped shaft is formed at a low cost and each of a plurality of tooth forms provided in the axial direction. It can be manufactured in a state in which the accuracy of runout and coaxiality is good.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an example of a press machine for carrying out the method of the present invention.
FIG. 2 is a cross-sectional view showing a state in which a molding material is inserted into a lower mold.
FIG. 3 is a cross-sectional view showing a first molding step.
FIG. 4 is a cross-sectional view showing a second molding step.
FIG. 5 is a cross-sectional view showing a third molding step.
FIG. 6 is a cross-sectional view showing a fourth molding step.
FIG. 7 is a cross-sectional view showing a stepped shaft formed by the method of the present invention.
FIG. 8 is a cross-sectional view showing a first molding step for molding a molding material.
FIG. 9 is a cross-sectional view showing a second molding step for molding a molding material.
FIG. 10 is a cross-sectional view showing a third molding step for molding a molding material.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Bolster, 2 ... Slide, 3 ... Lower mold apparatus, 4 ... Upper mold apparatus, 5 ... Guide post, 6 ... Fixing member, 7 ... Die holder, 8 ... Lower mold, 9 ... Set stand, 10 ... Lift rod, 11 DESCRIPTION OF SYMBOLS ... Elevating plate, 12 ... Lower molding apparatus, 13 ... Clamp member, 14 ... Lower molding die, 15 ... Rod, 16 ... Lower support stand, 17 ... Pin for hollow part molding, 18 ... Main punch, 19 ... Inner punch, 20 ... outer punch, 21 ... plate, 22 ... frame member, 23, 25 ... intermediate member, 24 ... inner cylinder, 26 ... outer cylinder, 27 ... molding material, 28 ... stepped shaft, 29 ... gear, 30, 31 ... spline, 35 ... Mold device, 36 ... Lower die, 37 ... Upper die, 37a ... Inner punch, 37b ... Main punch, 37c ... Outer punch, 38 ... Auxiliary lower die, 39 ... Core metal, 40 ... Large diameter part molding die, 41 ... set holes, 2 ... shaft portion forming mold, A ... hollow material.

Claims (1)

In a method of forming a stepped shaft having stepped portions with different diameters in the axial direction, and at least having a tooth profile on the outer periphery of the large-diameter stepped portion on one end side in the axial direction,
In the lower mold cavity, which has the same shape as the outer periphery of the stepped shaft, with the large diameter part open upward, it is approximately similar to the shape of this lower mold cavity and the outer diameter of the tooth forming part Insert a molding material formed with a diameter smaller than the inner diameter of the tooth forming part of the lower mold cavity, with its upper end protruding from the lower mold cavity,
The entire upper end portion of the molding material in the lower mold cavity is formed into a main punch formed in a shaft shape, an inner punch formed in a cylindrical shape surrounding the main punch, and a cylindrical shape surrounding the inner punch. consists of a outer punch, and at the upper mold which is actuable each individually, they were pressed moves downward together form,
Next, only the main punch is moved downward under the pressed state of the inner punch and the outer punch, the axial center portion of the molding material is pressed, this portion is expanded in diameter, and the outer peripheral portion is filled in the tooth forming mold to replace the tooth profile portion. Rough molding,
After that, when a force stronger than the set pressure is applied from the lower surface, the main punch and the outer punch are moved downward while holding the upper surface of the molding material with the inner punch that is allowed to move upward. A method for manufacturing a stepped shaft, wherein the tooth profile including the outside of the tooth tip is pressed from the inside of the bottom of the molding material outside the inner punch to finish the tooth profile.

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