JP4972136B2 - Method of stepping an outer peripheral surface of a shaft-shaped member having a circular cross section - Google Patents

Description

  The present invention relates to a stepping method for forming a stepped portion on an outer peripheral surface of a shaft-shaped member having a circular cross section.

  The shaft member of the transmission has a different diameter depending on the axial position, and as disclosed in Patent Document 1, the shaft member is manufactured by drawing so that the diameter of each axial position becomes a desired diameter. Is common.

  Further, in order to support the shaft member at a desired position in the transmission case, a positioning step may be formed on the outer peripheral surface of the shaft member. Since it is difficult, it is often formed by cutting.

JP 2004-197912 A

  However, when forming a step part by cutting, since a part of material is removed by cutting, the yield of material falls. In order to improve the yield, it is possible to reduce the amount of cutting by pre-squeezing the diameter of the part forming the step portion by drawing and cutting the part, but if the shaft member is hollow, cutting The thickness of the processed portion is reduced, which causes a reduction in the strength of the shaft member.

  The present invention has been made in view of such technical problems, and a stepping process for forming a step portion having a substantially right angle on the outer peripheral surface of a shaft-like member having a circular cross section without depending on the cutting process. It aims to provide a method.

  According to an aspect of the present invention, there is provided a stepping method for an outer peripheral surface of a shaft-shaped member having a circular cross section, wherein the outer peripheral surface of the member is deformed to change the outer diameter from the first diameter to the second diameter. An inclined portion forming step for forming an inclined portion that continuously decreases in diameter, and at least (a) a first inner peripheral surface having an inner diameter substantially equal to the first diameter, and (b) the first A second inner peripheral surface connected to the inner peripheral surface of the first inner peripheral surface and extending radially outward from the first inner peripheral surface, and connected to the second inner peripheral surface and substantially perpendicular to the insertion direction of the member. The member having the inclined portion formed therein is inserted into a mold having a pressing surface, the outside of the inclined portion is brought into contact with the pressing surface, and the member is further pressed from this state to reduce the diameter of the inclined portion. A step forming first step for deforming outward in the direction, and pulling out the member pushed into the mold from the mold, And a step of forming a stepped portion by using the first inner peripheral surface to move the flesh of the inclined portion that has moved to the outside in the radial direction beyond the first diameter by the stepped portion forming first step. Is provided.

  According to the above aspect, the step portion having a substantially right angle can be formed on the outer peripheral surface of the shaft-shaped member having a circular cross section regardless of the cutting process, and the problem of yield reduction and strength reduction that has been a problem in the cutting process. Can be eliminated.

It is the figure which showed the manufacturing process of the stepped shaft-shaped member. It is the figure which showed a mode that the step part was shape | molded by the step-working method which concerns on embodiment of this invention. FIG. 3 is a partially enlarged view of FIG. It is the figure which showed the simulation result in the case of shape | molding a step part on the outer peripheral surface of a hollow axial part with the step processing method which concerns on embodiment of this invention. It is the figure which showed the simulation result in the case of shape | molding a step part in the outer peripheral surface of a solid axial part by the step forming method which concerns on embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a view showing a manufacturing process of the stepped shaft-like member 1 (FIG. 1D).

  To manufacture the stepped shaft-like member 1, first, a steel round bar is cut into a predetermined length to obtain a solid columnar member 10 (FIG. 1A). The cylindrical member 10 is formed into a member having a solid portion 11 in the center in the axial direction and a hollow shaft portion 2 extending vertically from the solid portion 11 by front-rear extrusion molding (FIG. 1 (b). )).

  Next, the shaft portion 2 is contracted in stages by drawing, and the outer diameter of the shaft portion 2 is made different according to the axial position (FIG. 1C). Thus, the shaft portion 2 is connected to the large-diameter portion 20, the first to third reduced-diameter portions 21 to 23 that are connected to the large-diameter portion 20 and have an outer diameter smaller than that of the large-diameter portion 20. And the 1st-3rd inclination parts 24-26 in which an outer diameter each decreases continuously are shape | molded.

  Next, a stepping process is performed on the shaft portion 2. In the stepping process, first, the shaft portion 2 is inserted into a step forming mold 5 (see FIG. 2), and the shaft portion 2 is pressed downward by a vertical punching press. Thereby, the 1st inclination part 24 which connects the large diameter part 20 and the 1st diameter reduction part 21 is buckled (step part shaping | molding 1st process). Subsequently, the first inclined portion 24 buckled by pulling out the shaft portion 2 from the mold 5 is ironed and a step portion 24 ′ is formed on the outer peripheral surface of the shaft portion 2 (FIG. 1 (d), step). Part molding second step). Thereby, the stepped shaft-like member 1 is obtained.

  The stepping process will be described in detail with reference to FIG. In FIG. 2, only the first reduced diameter portion 21 among the first to third reduced diameter portions 21 to 23 connected to the large diameter portion 20 is illustrated for easy explanation.

  FIG. 2A shows a state before inserting the shaft portion 2 into the mold 5 after forming the reduced diameter portions 21 to 23 by drawing. The outer diameter of the large diameter portion 20 of the shaft portion 2 is r1, the outer diameter of the first reduced diameter portion 21 is r2, and the outer diameter of the first inclined portion 24 continuously decreases from r1 to r2.

  The mold 5 includes a first mold 51 and a second mold 52 that is combined with the first mold 51 and movable in the vertical direction in the figure. A space 6 is formed in the mold 5 by combining the first mold 51 and the second mold 52.

  The space 6 includes first to third spaces 61 to 63 that are continuous in the axial direction of the shaft portion 2.

  The first space 61 is a cylindrical space having an open upper portion, and has a first inner peripheral surface 61s having an inner diameter R1 substantially equal to the outer diameter r1 of the large diameter portion 20.

  The second space 62 is a cylindrical trapezoidal space that is continuous with the first space 61, and is connected to the first inner peripheral surface 61s and expands radially outward from the first inner peripheral surface 61s. An inner peripheral surface 62s and a pressing surface 62p that is connected to the second inner peripheral surface 62s and substantially perpendicular to the insertion direction of the shaft portion 2 are provided. In this embodiment, the second inner peripheral surface 62s is a tapered surface whose inner diameter continuously increases from the inner diameter R1 of the first inner peripheral surface 61s.

  The third space 63 is a cylindrical space that is continuous with the second space 62, and is connected to the inner peripheral end of the pressing surface 62 p and has an inner diameter R 2 that is substantially equal to the outer diameter r 2 of the first reduced diameter portion 21. 3 inner peripheral surfaces 63s.

  When the shaft portion 2 is inserted into the space 6 having such a shape, as shown in FIG. 2B, the large-diameter portion 20 of the shaft portion 2 comes into contact with the first inner peripheral surface 61 s and the first inclined portion 24. The outer side of the first end contacts the pressing surface 62p on the lower end side, and the first reduced diameter portion 21 contacts the third inner peripheral surface 63s. On the other hand, a space 64 is formed between the first inclined portion 24 and the second inner peripheral surface 62s.

  When the shaft portion 2 is further pushed into the mold 5 from the state shown in FIG. 2B by a vertical press (not shown), the first inclined portion 24 having no member in contact with the radially inner side and the outer side is shown. 2 (c), the meat of the first inclined portion 24 that has buckled and buckled moves toward the space 64, that is, radially outward while the outer side is pressed against the pressing surface 62p.

  FIG. 3 is a partially enlarged view of FIG. Due to buckling, the volume of the meat that moves radially outward beyond the outer diameter r1 of the large-diameter portion 20 (extension part 71) is V1, the inner diameter of the large-diameter portion 20 is buckled radially inward and buckled. If the volume of the space left between the inclined portion 24 and the pressing surface 62p (the thinned portion 72) is V2, the inclination angle of the first inclined portion 24 before buckling and the shaft portion by vertical punching press The pushing amount of 2 is adjusted so that V1 and V2 are substantially equal. This is to fill the thinned portion 72 with the meat of the overhang portion 71 without excess or deficiency by the next ironing.

  When the first inclined portion 24 is buckled, the second mold 52 is raised by a hydraulic cylinder (not shown) and the shaft portion 2 is retracted from the mold 5 as shown in FIG. At this time, the meat of the overhang portion 71 is squeezed by the first inner peripheral surface 61s and moved downward along the first inner peripheral surface 61s in the drawing. As a result, the meat of the overhanging portion 71 moves to the lower side of the buckled first inclined surface 24 and fills the cutout portion 72, thereby forming a step portion 24 ′ having a substantially vertical corner. The The angle of the stepped portion 24 'is preferably a right angle, but may be slightly larger or smaller than the right angle as long as it can be made a right angle by finishing.

  FIG. 4 is a diagram showing a simulation result when the stepped portion 24 ′ is formed by the above stepping method.

  FIG. 4A shows a state in which the shaft portion 2 is inserted into the mold 5. When the shaft portion 2 is pushed in from this state, the first inclined portion 24 is buckled, the meat of the portion moves beyond the outer diameter r1 of the large diameter portion 20 to the outside in the radial direction, and an overhang portion 71 is formed. (FIGS. 4B to 4C).

  And if the axial part 2 in which the overhang | projection site | part 71 was formed is retracted from the metal mold | die 5, the meat | flesh of the overhang | projection site | part 71 will be rubbed by the 1st internal peripheral surface 61s, and it will be below the 1st internal peripheral surface 61s. It is sent. As a result, the underfilled portion 72 on the lower side of the first inclined portion 24 is filled with meat, and the first inclined portion 24 is formed into a stepped portion 24 ′ having a substantially vertical corner (FIG. 4 ( d)).

  Thus, according to this stepping method, it is possible to form the stepped portion 24 ′ having a substantially right angle on the outer peripheral surface of the shaft portion 2 without performing the cutting processing. The problem of strength reduction can be solved (effect corresponding to claim 1).

  Further, the volume V1 of the meat (the overhanging portion 71) that has moved outward in the radial direction beyond the outer diameter r1 of the large-diameter portion 20 is radially inner than the outer diameter of the large-diameter portion 20 and is buckled. The inclination of the first inclined portion 24 and the amount of pressing of the shaft portion 2 by vertical punching are adjusted so as to be equal to the volume V2 of the space formed between the inclined portion 24 and the pressing surface 62p (the thinned portion 72). Thus, the meat of the overhanging portion 71 is filled in the lacking portion 72 without excess and deficiency, and the stepped portion 24 ′ having substantially right-angled corners can be accurately formed (effect corresponding to claim 2). ).

  Furthermore, since the second inner peripheral surface 62s following the first inner peripheral surface 61s is a tapered surface, the meat that has moved to the outer side in the radial direction beyond the outer diameter r1 of the large-diameter portion 20 causes the shaft portion 2 to become gold. It is possible to prevent the step portion 24 ′ from being defective because it is not galvanized by the die 5 when being removed from the die 5 (effect corresponding to claim 3).

  In order to prevent galling, the second inner peripheral surface 62s is preferably a tapered surface as in this embodiment. However, if the galling can be prevented, the second inner peripheral surface 62s is replaced with other types. It is good also as a shape. For example, the second inner peripheral surface 62s may be a smooth curved surface that connects to the first inner peripheral surface 61s, or only the connection portion between the first inner peripheral surface 61s and the second inner peripheral surface 62s is tapered. It may be a surface or a curved surface.

  The embodiment of the present invention has been described above, but the above embodiment is merely one example of application of the present invention, and the technical scope of the present invention is limited to the specific configuration of the above embodiment. is not.

  The step forming method and the mold can be widely used for forming a step portion on the outer peripheral surface of a shaft-shaped member having a circular cross section (the outer periphery of the cross section only needs to be substantially circular), for example, A step portion can be formed on the shaft portion of the pulley for the belt type continuously variable transmission.

  Even if the shaft portion 2 is solid, a step portion can be formed on the outer peripheral surface thereof. In this case, the meat of the first inclined portion 24 moves radially outward not by buckling but by plastic deformation.

  FIGS. 5A to 5D show simulation results when the shaft portion 2 is solid. FIGS. 5A to 5D show states in the middle of processing corresponding to FIGS. 4A to 4D, respectively, and the same reference numerals are used for configurations common to FIGS. 4A to 4D. It is attached. As shown in FIG. 5 (d), even if the shaft portion 2 is solid, it is possible to form a step portion 24 'having a substantially right angle as in the case where the shaft portion 2 is hollow.

  Furthermore, the corner | angular part of a flange part can also be shape | molded at a substantially right angle using the said stepped processing method and a metal mold | die. In this case, for example, a part (corresponding to the first inclined portion 24 in the above embodiment) whose outer diameter continuously decreases as it moves away from the axial center position is formed in advance by bulge forming or the like, and the part is made of the above-mentioned gold If molding (plastic deformation and ironing) is performed using a mold similar to the mold, it is possible to form a corner that is substantially perpendicular to the portion.

DESCRIPTION OF SYMBOLS 1 Stepped shaft-shaped member 2 Shaft part 5 Mold 24 1st inclination part (inclination part)
61 1st space 61s 1st inner peripheral surface 62 2nd space 62s 2nd inner peripheral surface 62p Pressing surface

Claims (3)

A stepping method for an outer peripheral surface of a shaft-shaped member having a circular cross section,
An inclined portion forming step of forming an inclined portion in which the outer diameter of the member is deformed to continuously reduce the outer diameter from the first diameter to the second diameter;
Inside, at least,
(a) a first inner peripheral surface having an inner diameter substantially equal to the first diameter;
(b) a second inner peripheral surface connected to the first inner peripheral surface and extending radially outward from the first inner peripheral surface, and connected to the second inner peripheral surface in the insertion direction of the member A pressing surface that is substantially perpendicular to the surface;
The member formed with the inclined portion is inserted into a mold having a contact, the outside of the inclined portion is brought into contact with the pressing surface, and the inclined portion is deformed radially outward by further pressing the member from this state. A step forming step 1 to be performed;
By pulling out the member pushed into the mold from the mold, the flesh of the inclined portion that has moved to the outside in the radial direction beyond the first diameter in the step forming step 1 is obtained. A second step of forming the stepped portion by the inner peripheral surface;
A stepping method comprising the steps of: The stepping method according to claim 1,
At least one of the inclination angle of the inclined portion formed by the inclined portion forming step and the pressing amount of the member in the step forming first step,
(x) a volume of meat that moves radially outward beyond the first diameter by the step forming first step;
(y) the volume of the space left between the inclined portion and the pressing surface, which is radially inward of the first diameter and deformed by the step forming first step;
Are adjusted to be approximately equal,
A stepping method characterized by that.   3. The stepping method according to claim 1 or 2, wherein the second inner peripheral surface is a tapered surface.