JP2002346681A - Method for manufacturing hollow stepped shaft - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a hollow stepped shaft which has a reduced diameter part, which is longer than the width of a large diameter part, on one side of the large diameter part in the direction of the shaft, and which has an other processing part such as gears and the like on the other side, by use of one set of mold implements and without changing material setting in process of molding. SOLUTION: Thick-walled hollow materials B1 , B2 , B3 are set up in mold implements 1, 11, 22, by respectively placing molds for molding the one side face to face with the one sides of the materials and molds for molding the other side face to face with the other sides, while core bars 7 are inserted in each of the hollow parts of the materials. The materials are pressed by the molds for molding the one side and processing parts of the one side are molded by extrusion in the molds for molding the one side. Thereafter during the process from the middle to the end of molding of the processing parts of the one sides, the materials are pressed by the molds for molding the processing part of the other side and the processing parts of the other sides are molded by extrusion.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a large-diameter portion having a large-diameter portion at an intermediate portion in the axial direction, and having, on one side in the width direction of the large-diameter portion, a length smaller than the large-diameter portion and longer than the width of the large-diameter portion. The present invention relates to a method for manufacturing a hollow stepped shaft having a shaft-shaped one-side machined portion having, and a second-side machined portion shorter than the one-side machined portion on the other axial side.

FIGS. 13 to 15 show first, second, and third hollow stepped shafts A ₁ , A ₂ , A ₃ to be manufactured by the present invention.
It is shown. First hollow stepped shaft A shown in FIG.
₁ has a large-diameter portion a at an intermediate portion in the axial direction, and on one side in the axial direction of the large-diameter portion a, makes the diameter smaller in a stepped manner than the large-diameter portion a and the width of the large-diameter portion a (axial direction). Length), a small-diameter shaft portion b which is a processing portion on one side longer, a gear portion c which is a processing portion on the other side shorter than the processing portion on the other side on the other side in the axial direction, and a hole is formed in the shaft center portion. It has a shape having d.

Further, a second hollow stepped shaft A ₂ shown in FIG.
Is a serrated portion e provided on the outer periphery of the distal end portion of the small-diameter portion b of the one-side processed portion, and the other shaft portion f which is a short-side processed portion on the other side of the large-diameter portion a having the gear portion c. have. The other shaft portion f is shorter than the small diameter portion b on one side.

A third hollow stepped shaft A shown in FIG.
_In No. ₃ , a concave portion g which is a processed portion on the other side is provided on the other side of the large diameter portion a. A serration e is provided at the tip of the small diameter shaft b.
Is molded.

[0005]

2. Description of the Related Art Conventional methods for manufacturing a hollow stepped shaft having the above-mentioned shape include a method of forming a rough portion by hot forging and then forming the entire surface by cutting, and a method of forming a solid portion of a shaft portion by cold forging. After forming, the gear part is machined with a hobbing machine, and the hollow part is hollowed out by machining (gun drill etc.).
Three steps are required, and different molds are used for each. In the swaging process, it depends on the shape of the stepped hollow shaft.
A swaging head was required for each step, which also required at least three processing steps.

Further, in the conventional production of a stepped hollow shaft by cold forging, when the length of the small diameter portion is relatively long with respect to the width of the large diameter portion, the small diameter portion and other processed portions are used. A certain gear portion could not be formed at the same time. Therefore, in the conventional manufacturing method, the small-diameter shaft portion and the gear portion are separated in separate steps.
That is, when the gear portion is machined by a hobbing machine after forging, or both the shaft portion and the gear are forged, the molding is performed by different mold devices. And when using these different mold devices, the gap between the upper mold and the lower mold occurs, and concentricity and concentricity cannot be obtained, and the hollow thickness becomes uneven and the thickness becomes uneven. Was.

The present invention has been made in view of the above, and has a small-diameter portion longer than the large-diameter portion on one side in the axial direction of the large-diameter portion, and another processing portion such as a gear on the other side. The hollow stepped shaft can be molded with one set of mold equipment and without changing the material during molding, and a hollow stepped shaft with excellent coaxiality and concentricity with the outer periphery can be manufactured at low cost. It is another object of the present invention to provide a method of manufacturing a hollow stepped shaft capable of further ensuring strength.

[0008]

In order to achieve the above object, a method of manufacturing a hollow stepped shaft according to the present invention has a large-diameter portion at an intermediate portion in the axial direction, and has a large-diameter portion at one axial side of the large-diameter portion. , One side processing part smaller in diameter than the large diameter part and longer than the width of the large diameter part,
On the other side in the axial direction, a method of manufacturing a hollow stepped shaft having a processing portion on the other side shorter than the processing portion on the one side, and further forming a hollow stepped shaft, wherein a thick hollow material is inserted into a hollow portion with a core metal. Then, the mold for one side processing is opposed to one end side, the mold for the other side processing is opposed to the other end side, and set in a mold apparatus. Pressing the material, extruding the one-side processing part into this one-side processing mold, and using the other-side processing mold during the one-side processing part from the middle to the end of molding. The material was pressed to extrude the processed part on the other side.

In the method of manufacturing a hollow stepped shaft, a part of the mold for processing the other side is retracted with respect to the material at the time of molding the processed part on the other side, and the other side is processed into a space formed by the retraction. Either part or all of the part was molded.

[0010]

[Work] According to the above-mentioned manufacturing method, one side processed portion which is long in the axial direction with respect to the width of the large diameter portion is extruded first, and the one side processed portion is formed from the middle of the one side processed portion to the end of the forming. The other processed part shorter than the processed part is formed.

[0011]

FIG. 1 shows a first embodiment of the present invention.
Explanation will be made based on FIG. Figure 1 is a mold apparatus for molding an axis A ₁ with a first hollow stage, the mold apparatus 1 comprises a set of holes 2 in which the first material B ₁ of thick hollow is set, this A lower die 4 having a gear part forming die 3 provided to extend to the inner side (lower side) of the set hole 2;
The outer diameter which fits into the upper die has a shaft portion forming mold 5 was outside diameter shape of the first small-diameter shaft portion b of the hollow stepped shaft A ₁ inside 6
And a metal core 7 for forming a hole d of the _first hollow stepped shaft A1;
An auxiliary lower die 8 having external teeth fitted to the gear forming die 3 of the lower die 4 and slidably fitted to the gear forming die 3 of the lower die 4.

[0012] Next, a first method of manufacturing a hollow stepped shaft A ₁ of using the mold assembly 1 from Fig. 1 in FIG.
Figure 1 shows a set state of the material B _1, together with sets material B ₁ in setting hole 2 of the lower mold 4, the material B ₁
The lower metal mold 7 is inserted from below, and the auxiliary lower mold 8 is inserted into the gear mold 3 of the lower mold 4 to close the gear mold 3.

FIG. 2 shows a state in the middle of processing, and the upper die 6 is shown.
And move down to Material B₁Press. At this time, the teeth of the lower mold 4
Since the car mold 3 is closed by the auxiliary lower mold 8,
Material B ₁Is placed in the space between the inner die of the upper die 6 and the metal core 7.
It enters and is pushed upward. In this process
Set position O of upper die 6₁Stroke L from ₁
Is the first hollow stepped shaft A₁End face of large diameter part a in completed state
Final molding stroke L up to₂Stroke on the way to
It is.

[0014] Figure 3 shows the machining end state in which downward movement over a final molding stroke L ₂ of the upper die 6 from the set state position O _1, at this time, from the machining middle state shown in FIG. 2, the auxiliary under The mold 8 is moved downward from the set state position O ₁ ′ over the length L ₃ of the gear portion c of the hollow stepped shaft A ₁ to be fixed, and in this state, the lower movement of the upper mold 6 to L ₂ is continued. .

As a result, the raw material B ₁ is further pressed by the upper die 6, and a part of the meat of the raw material B ₁ is extruded into the gear portion forming die 3 opened by the lower movement of the auxiliary lower die 8. The gear portion c is extruded between the core metal 7 and the core metal 7. During this time, by moving the upper die 6 down to the terminal end (L ₃ ), the thick meat of the material B ₁ is pushed out into the upper die 6 in the axial direction, and the shaft b Is formed.

[0016] By this processing step has a large diameter portion a to an intermediate portion of the method shown in FIG. 13, the shaft portion b on one hand, the first hollow stepped shaft A ₁ having the other to the gear c Manufactured.

The outer peripheral shape of the auxiliary lower die 8 is not necessarily a gear shape fitted inside the lower die 3, but may be a shaft having a diameter slightly smaller than the addendum circle of the gear forming die 3.

FIGS. 4 to 6 show a second embodiment of the present invention.
It will be described based on. In this description, members having the same configuration as in the first embodiment are denoted by the same reference numerals, and description thereof is omitted. In the figure, reference numeral 11 denotes a mold device for molding the _second hollow stepped shaft A2.
However, in order to form the shaft f on the other side, the auxiliary lower die 8 is divided into a lower die 8a for a gear portion and a lower die 8b for a shaft, and each is separately provided. It is designed to move. A serration forming die 6a for forming serrations e at the tip of the shaft on the inner surface of the upper die 6.
Is provided.

[0019] will be described in FIG. 7 the second manufacturing method of a hollow stepped shaft A ₂ of using a mold apparatus 11 having the above structure from FIG. Figure 4 shows a set state of the material B _2, Material B
With sets ₂ to set the hole 3 of the lower mold 4, inserting a metal core 7 from the lower side to the material B _2. Further, by inserting the lower mold 8a gear portion of the auxiliary lower die 8 to the gear part mold 3 of the lower mold 4, also the lower mold 8b for the shaft portion of the shaft portion f the length W _1, the auxiliary lower mold 8 At the set position O ₂ ′ of the gear unit lower die 8a. Figure O ₂ is the set position of the upper die 6.

FIG. 5 shows a state in the middle of processing, and the upper die 6 is shown.
The pressed material _{B 2} moves downward over _{L 4} from the set position _{O 2.} Meat materials B ₂ in this case with extruded along the metal core 7 into the lower for the shank-type 8b, extruded enters into the space between the inner and the core 7 of the upper die 6 upward.

FIG. 6 shows a state in which the molding is completed. From the state shown in FIG. 5, the auxiliary lower die 8 composed of the lower die 8a for the gear portion and the lower die 8b for the shaft is integrally formed. From the set state position O ₂ ′, and the lower die 6 is moved downward by the length L _{6 corresponding} to the gear forming length, and the upper die 6 is moved from the middle of the processing to the large diameter from the end face set by the auxiliary lower die 8. the width W ₂ parts to the downward movement over the distance L ₅ until a predetermined dimension. At this time, L ₅ > L ₆ , and the meat of the material B ₂ is pushed upward inside the upper mold 6 by the difference, and the small-diameter shaft part b having a predetermined length is obtained.
Is molded. At this time, the lower die 6 is attached to the tip of the small diameter shaft portion b.
The serration e is formed into the serration mold 6a provided at the inner diameter of the above.

The tooth profile of the gear unit the mold 3 to the outer periphery of which moves the large-diameter portion of the material B ₂ is downward according downward movement of the L ₆ of the lower die 8 is formed over L _6.

FIGS. 7 to 1 show a third embodiment of the present invention.
Description will be made based on 0. In the figure, reference numeral 21 denotes a third hollow stepped shaft A.
₃ is a mold apparatus for molding the mold _3.
Is composed of a lower mold 22 and an upper mold 23, an auxiliary lower mold 24 and the metal core 7. The lower mold 22 is set hole 27 for supporting the large diameter portion forming mold 26 to the outer diameter of the large diameter portion a of a hollow stepped shaft A ₃ and an inner diameter, the material B ₃ to the back side (lower side) And a shank forming die 28 connected to the set hole 27.
A serration mold 29 is provided at the tip of the shank mold 28. The auxiliary lower mold 24 is set at a position facing the tip of the small-diameter shaft portion b.

The upper die 23 has an outer diameter set to fit the large-diameter portion forming hole 26 of the lower die 22 and an inner diameter set to the hollow stepped shaft A _3.
A first upper mold 23a having an inner diameter of the concave portion g is slidably fitted inside the first upper mold 23a having an outer diameter of the inner diameter of the concave portion g. And a second upper die 23b having a size matching the upper die 23b.

[0025] Next, a third manufacturing method of hollow stepped shaft A ₃ of using the mold apparatus 21 from Figure 7 with Figure 10. Figure 7 shows a set state of the material B _3, the material B
₃ is set in the set hole 27 of the lower mold 22, the core metal 7 is inserted into the material B ₃ from below, and the upper mold 23 is further inserted.
There has been a contact with the upper surface of the material B _3. O ₃ is set state position of the upper die 23.

FIG. 8 shows a state in the middle of machining, and
First and second sides 23a and 3 of this, 23b and moves downward over _{L 7} from _{O 3} in the one piece presses from above the material _{B 3.} As a result, the raw material B ₃ is extruded into the shaft portion forming die 28. Figure 9 shows a state in which extruded small-diameter shaft portion b is further moved downward by L ₈ the upper die 23. At this time, the upper end portion of the material B ₃ is expanded into a shape along the large-diameter portion forming mold 26 of the lower mold 22.

[0027] FIG. 10 shows a state of forming a recess g of the large-diameter portion a, the second upper die 23b located inside of the upper mold 23 from the state shown in FIG. 9 to the predetermined position O _{3 'L 9} The first upper mold 23a is moved upward while moving downward.

As a result, the concave portion g of the large diameter portion a is formed by the second upper die 23b, and the meat removed by molding the concave portion g is pushed upward following the upward movement of the first upper die 23a. Thus, a large diameter portion a is formed.

The downward position O _{3 'of} the second upper die 23b at this time, a position where the dimension between the one end face of the bottom and a large diameter portion a recess g has a predetermined dimension W _3.

In each of the above embodiments, each material B ₁ ,
Molded from B _{2, B 3} is performed by cold forging by cold forging, or warmed to 200 to 700 ° C. at room temperature. In addition, the material generates heat due to its plastic deformation, and the subsequent processing is performed smoothly.

Each of the raw materials B ₁ , B ₂ , B ₃ is made of a low carbon steel having a hardness of at least HRC 20 after tempering (salt bath or oil cooling) and a C content of 0.34 or less.

As a material which does not generate work cracks in plastic working, has good hardenability, and has good elongation, C: 0.34 or less, Si: 0.15 to 0.35, Mn:
1.0 to 1.5, P: 0.03 or less, S: 0.035 or less, B and Ti are each added in small amounts, and the remaining Fe is used. The lower limit of C is an amount sufficient to obtain the following heat treatment effect.

As one example of this, C: 0.32, S
i: 0.23, Mn: 1.38, P: 0.03 or less,
S: 0.035 or less, B: 0.0014, Ti: 0.0
2. A hollow stepped shaft was manufactured in the first embodiment using the material of the remaining Fe component, and heat treatment was performed under heat treatment conditions (heat cycle) shown in FIG. The hardness with respect to the distance (mm) was as shown in FIG. Sufficient hardness was obtained up to a depth of 7 mm from the surface.

[0034]

According to the present invention, the one-side processed portion which is longer in the axial direction with respect to the width of the large-diameter portion is extruded first, and the above-mentioned one-side processed portion is formed from the middle to the end of the forming. By forming the other processing part shorter than the one processing part, there is a small diameter part longer than the width of the large diameter part on one side in the axial direction of the large diameter part, and other processing parts such as gears on the other side. The hollow stepped shaft can be molded with a single set of mold equipment without changing the material during molding, and a hollow stepped shaft with excellent coaxiality and concentricity with the outer periphery can be manufactured at low cost. .

Further, according to the present invention, since the hollow stepped shaft is formed by plastic working, the fiber flow of the material is formed without being sheared during the working, and the surface is hardened to increase the strength. Can be secured. Further, no scratch such as an acute angle is generated after the heat treatment, and there is no problem such as burning cracks.

[Brief description of the drawings]

FIG. 1A is a cross-sectional view illustrating a state in which a material is set in a mold device according to a first embodiment of the present invention.
(B) is XX sectional drawing of (a).

FIG. 2 is a cross-sectional view showing a state during processing in the first embodiment of the present invention.

FIG. 3 is a cross-sectional view illustrating a processing end state according to the first embodiment of the present invention.

FIG. 4 is a cross-sectional view illustrating a state in which a material is set in a mold device according to a second embodiment of the present invention.

FIG. 5 is a cross-sectional view showing a state in the middle of processing according to a second embodiment of the present invention.

FIG. 6 is a cross-sectional view showing a processing end state according to a second embodiment of the present invention.

FIG. 7 is a cross-sectional view illustrating a state where a material is set in a mold device according to a third embodiment of the present invention.

FIG. 8 is a sectional view showing a state in which a material is set in a mold apparatus according to a third embodiment of the present invention.

FIG. 9 is a cross-sectional view illustrating a state in which a material is set in a mold device according to a third embodiment of the present invention.

FIG. 10 is a cross-sectional view showing a processing end state according to a third embodiment of the present invention.

FIG. 11 is a diagram showing heat treatment conditions, in which (a) shows quenching and (b) shows tempering.

12 is a diagram showing hardness with respect to a distance from a surface of a member heat-treated under the heat treatment conditions shown in FIG. 11;

FIG. 13 is a sectional view showing a first hollow stepped shaft.

FIG. 14 is a sectional view showing a second hollow stepped shaft.

FIG. 15 is a sectional view showing a third hollow stepped shaft.

[Explanation of symbols]

1,11,21 ... mold apparatus, 2,27 ... set hole, 3 ...
Gear part forming die, 4,22 ... lower die, 5,28 ... shaft part forming die, 6,23 ... upper die, 6a ... serration forming die, 7 ...
Core metal, 8, 24 ... auxiliary lower mold, 8a ... gear lower mold, 8b ...
Lower dies for shafts, 23a, 23b: first and second upper dies.

Claims (2)

[Claims] A large-diameter portion is provided at an intermediate portion in the axial direction, and one side processed portion having a smaller diameter than the large-diameter portion and longer than a width of the large-diameter portion is provided on one axial side of the large-diameter portion. On the other side, a method for manufacturing a hollow stepped shaft having a processed portion on the other side shorter than the processed portion on the one side, and further forming a hollow stepped shaft, in a state where a thick hollow material is inserted into a hollow portion with a core metal, A mold for one side processing is opposed to one end side, and a mold for the other side processing is opposed to the other end side, and set in a mold apparatus. Pressing and extruding the one-side processed part into the one-side processing mold,
A method for manufacturing a hollow stepped shaft, wherein a material is pressed by a mold for processing on the other side and a processed portion on the other side is extruded. 2. A part of the other side processing part is retracted with respect to the material when forming the other side processing part, and a part or all of the other side processing part is placed in a space formed by the retraction. The method for manufacturing a hollow stepped shaft according to claim 1, wherein the shaft is molded.