JPH10216888A - Manufacture of drive hub - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize the excellent finish accuracy of an intermediate member, and to minimize the cutting time by pressing a press stock close to abutting surfaces of a lower die and an upper die by a hollow punch, performing the plastic flow along a mandrel and the upper and lower dies to form the intermediate member, pressing the intermediate member by another hollow punch to form an approximately completed product, and cutting it. SOLUTION: When a tip 109 of a hollow punch 106 is lowered close to joining surfaces of a lower die 104 and an upper die 105, a press stock 10 in a forming die space is filled to the bottom of a counter punch 103 through the forward extrusion, and the intermediate material is plastic-deformed in each outer circumferential direction or axial direction through backward extrusion and fills the space. Because the press stock is plastic-deformed with excellent flow balance, an intermediate member excellent in the product accuracy can be obtained. A bottom part of the intermediate member is pressed by the hollow punch in another forming die to obtain an approximately completed product, and the small finish allowance is cut by a lathe, etc., to complete the product. The efficient production is realized by introducing the cold forging.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a drive hub, and more particularly, to a hard disk drive (HDD).
The present invention relates to a method for manufacturing a drive hub suitable for forming a drive hub of a spindle motor for use by cold forging.

[0002]

2. Description of the Related Art Drive hubs for HDDs are required to be processed at a low cost for extremely high finishing accuracy and mass production. Therefore, for example, as disclosed in JP-A-8-11021, a disc-shaped blank is formed from a round bar cut to a required length, and then the blank is manufactured by cold stamping forging in one to several stages. It has been known that a cutting blank having a shape close to that of a blank is cut and further cut into a product.

Japanese Patent Publication No. 7-41347 discloses a method for forging a cylindrical member having a flange portion similar to a drive hub. According to this method, a metal lump is formed in a cup shape, and a flange can be integrally formed around the metal lump in the same forging step.

[0004]

The former of the prior art described above focuses on obtaining a disk-shaped cutting blank close to the product by one to several stages of cold stamping forging. Has a straight surface that is relatively easy to press form.

However, in the case of a cup-shaped drive hub or the like in which a flange portion serving as a magnetic path is integrally formed on the outer peripheral portion, the outer peripheral portion has a complicated shape. I can't get it.

[0006] On the other hand, according to the latter conventional technique, it is a suitable forging method for integrally forming a flange on the base of a cup-shaped product. However, as can be seen from FIG. 4 and its description,
A circumferential notch is formed in the inner peripheral surface of the side mold portion on the second punch side, and the inner diameter of the deepest portion of the notch is the second notch.
Since the diameter is substantially the same as the outer diameter of the punch, it is not possible to integrally form a flange at the middle or the outer diameter of the cup-shaped product.

SUMMARY OF THE INVENTION In view of the above, the present invention provides a high-precision flange that contributes to the life of a die and a punch and does not impose a burden on finish cutting by introducing the proposed cold forging method into a manufacturing process. An object of the present invention is to manufacture an attached intermediate member at low cost.

[0008]

One aspect of the present invention is achieved by cold forging in the following steps.

A) The press material, which is arranged in a forming die space by a hollow punch having an outer diameter smaller than the outer shape of the hollow press material made of metal and an inner diameter larger than the outer diameter of the mandrel, is connected to a lower die. A step of vertically pressing to near the contact plane of the upper die, plastically flowing the press material around and backward along the mandrel and the upper and lower dies, and filling the flange forming space to form an intermediate member.

B) a step of arranging the intermediate member on another forming die and pressing it with a hollow punch to obtain a near-finished product with a small finishing margin;

C) A step of cutting the fine finishing allowance to obtain a finished product.

One aspect of the present invention is achieved by cold forging in the following steps.

A) A hollow punch in which the outer diameter is smaller than the outer diameter of a solid disc-shaped press material made of metal and is formed in the space of the forming die formed by the lower die and the upper die, and the center is hollow. The press material is pressed vertically to the vicinity of the contact plane between the lower die and the upper die, and the press material is plastically flowed around and backward along the hollow portion of the hollow punch and the upper and lower dies to form the flange portion forming space and A step of forming an intermediate member by filling the hollow portion of the hollow punch.

B) a step of arranging the intermediate member on another forming die and pressing it with a hollow punch to obtain a near-finished product with a small finishing margin.

C) A step of cutting the fine finishing allowance to obtain a finished product.

[0016]

Embodiments of the present invention will be described below with reference to the drawings.

First Embodiment (Method of Forming a Flange at the Outer Peripheral Tip from a Hollow Press Material) FIG. 1 (a) shows a hollow press material 10 made of a metal. It is a metal material having a diameter of 20φ, an inner diameter of 9φ, and a thickness of about 8 mm, which is made of a metal material added with 0.5%.

The hollow press blank 10 is formed by a cold forging method. In the first step shown in FIG. 1B, the thick portion 11 is pressed, and the cylindrical portion 12 having a thin inner diameter for inserting the rotating shaft is provided.
And a flange portion 13 is preliminarily worked on the outer peripheral portion, and the intermediate member 1 is formed.
A is obtained.

The intermediate member 1A is further compressed in the second step of FIG. 1 (c), and the thin inner diameter cylindrical portion 12 and the outer diameter cylindrical portion 14 are extended to obtain a near-completed product 1 similar to a finished product. The approximated finished product 1 has a finish cutting allowance of 0.1 to 0.1.
Although not shown, it is cut by a lathe or the like, but not shown, to become a finished product.

Next, a concrete method of the intermediate member and the finished product shown in FIG. 1 will be described with reference to FIGS.

In FIG. 5, a press material 10 (shown by a two-dot chain line) having substantially the same diameter as a lower die 104, which will be described later, includes a mandrel 101, a knockout sleeve 102 concentrically arranged on the mandrel, and a counter punch 103. ,
It is arranged in a forming die space formed by the lower die 104 and the upper die 105, and is press-formed by a hollow punch 106 which slides down on the inner diameter of the upper die 105 and descends.

The characteristic feature is that the inner diameter of the upper die 105 is smaller than the inner diameter of the lower die 104, and a tapered surface 107 for forming a flange portion is formed over the entire inner peripheral edge portion which comes into contact with the lower die 104. I have. The outer peripheral edge of the counter punch 103 is joined to the inner peripheral surface of the lower die 104 with a gentle curve or tapered surface 108 extending upward. Further, the hollow punch 106 is used for the mandrel 10.
1 with a gap G of several millimeters, and the outer peripheral edge of the tip 109 is tapered or curved.
Or a combination thereof.

In the above configuration, when the tip 109 of the hollow punch 106 is lowered close to the position of the joint surface between the lower die 104 and the upper die 105, the press material 10 placed in the forming die space is pushed forward to reach the bottom of the counter punch 103 by extrusion. While being filled, the intermediate material is plastically deformed without stagnation by rearward extrusion while maintaining the plastic flow balance in both outer peripheral directions or in the axial direction, filling the die space, and the intermediate member 1A is formed. Of course, the lower limit position of the hollow punch 106 is designed so that the plastic deformation pressure is not applied to the dies 104 and 105 more than necessary within the range where the flange 13 is formed. If the life of the die is further concerned, it is preferable to provide a plastic flow balance groove between the upper die 105 and the hollow punch 106. Accordingly, here, the press material is plastically flowed with a good flow balance, so that the plastic is not subjected to a plastic deformation pressure that would damage the die, and an intermediate member having excellent product accuracy can be obtained.

In the next step, the intermediate member is placed on a counter punch 113 having a flat bottom surface, and the bottom portion is pressed by a hollow punch 116 while the center portion is restrained by a mandrel 111 and the outer peripheral portion is restrained by a lower die 114. The material of the cylindrical bottom part 15 is simultaneously poured into the outer cylindrical part (outer diameter cylindrical part) 14 and the center side cylindrical part (inner diameter thin cylindrical part) 12. As a result, the distance between the cylindrical bottom portion 15 and the flange portion 13 is extended, and the hollow cylinder at the center portion is further extended, so that a near-completed product 1 having a fine finishing allowance as a subsequent machining allowance is obtained.

Here, the hollow punch 116 has only a chamfered tip inner diameter portion 117, and the corners of the obtained product are machined at substantially right angles.

The near-finished product thus obtained is a finished product obtained by cutting the fine finishing allowance using a lathe or the like.

Second Embodiment (Method of Forming Flange from Hollow Press Material to Middle Outer Perimeter) FIG. 2 shows a method of forming a flange from a hollow press material to a middle outer periphery by a first embodiment. The difference from the example (FIG. 1) is that a thin cylindrical portion 20a is formed in advance on the outer peripheral portion of the press material 20 and is processed as a material.
Subsequent processing steps are not different from FIG. According to this method, the cylindrical portion 23a is easily formed integrally with the rear of the flange 23.

When the cylindrical portion 23a is relatively short, the cylindrical portion may be formed simultaneously when the flange 23 is formed from the hollow press material 10. In this case, it is not necessary to use a material having a cylindrical portion in advance as shown in FIG.

Third Embodiment (Method of Forming Flange from Solid Member to Intermediate Perimeter) FIG. 3A shows a solid material 30 and a thick portion 31 formed in a first step of FIG. The intermediate member 3A is pressed and preliminarily worked with the central shaft 32 and the flange portion 33 on the outer peripheral portion. The bottom of this intermediate member is further compressed in the second step (c), and the center shaft 32 and the outer diameter cylindrical portion 34 are extended to obtain a product 3 which is similar to a finished product. It should be noted that the finished part 3 is also a finished product after finishing margins are cut as in the above embodiment.

The steps (a) and (b) will be described in detail with reference to FIG.

In FIG. 7, a press material (indicated by a two-dot chain line) 30 is placed in a molding die space formed by a counter punch 303, a lower die 304, and an upper die 305 which are arranged concentrically with a knockout sleeve 301. It is arranged and pressed by a hollow punch 306 which slides down the inner diameter of the upper die 305 and descends. The characteristic feature is that the inner diameter of the lower die 304 and the inner diameter of the upper die 305 are substantially equal, and the upper die has a tapered surface 30 that forms the flange 33 over the entire inner peripheral edge portion joined to the lower die 104.
7 are formed. The outer peripheral edge of the counter punch 303 is joined to the inner peripheral surface of the lower die 304 with a gentle curve or tapered surface extending upward. Further, the hollow punch 306 has a gap 308 of several millimeters at the outer periphery of the tip.
Is formed so as to face the upper die 305, and the inner and outer peripheral edges of the pressing tip 309 are tapered or curved, or a combination thereof.

In the above configuration, when the tip 309 of the hollow punch 306 is lowered close to the position of the joining surface between the lower die 304 and the upper die 305, the press material 30 disposed in the forming die space is pushed forward to reach the bottom of the counter punch 303 by extrusion. While being filled, the intermediate material is plastically deformed along the hollow of the hollow punch by back extrusion to fill the die space and form the intermediate member.

Fourth Embodiment (Method of Forming a Flange from a Solid Member to an Intermediate Perimeter) FIG. 4 shows a method of forming a flange from a solid member to an intermediate outer periphery, according to a third embodiment ( The difference from FIG. 3) is that a thin cylindrical portion 40a is formed in advance on the outer peripheral portion of a solid press material and then processed using the material as a material. The subsequent processing steps are not different from FIG. I do. According to this method, the cylindrical portion is easily formed integrally with the rear of the flange 43.

[0034]

As described above, according to the present invention, it is possible to perform cold forging in the manufacture of a drive hub, and not only to efficiently manufacture the drive hub, but also to form the pressed shape because of its high finishing accuracy. Finishing time is also minimized. Further, the life of the molding die is greatly improved, and the method for manufacturing a drive hub suitable for mass production is provided.

[Brief description of the drawings]

FIG. 1 is a diagram showing a first embodiment, a process for obtaining a drive hub intermediate product having a flange at an outer peripheral end from a hollow press material.

FIG. 2 is a view showing a second embodiment, a process for obtaining a drive hub intermediate product having a flange at an outer peripheral intermediate portion from a hollow press material.

FIG. 3 is a view showing a process of obtaining a drive hub intermediate product having a flange at an outer peripheral end from a solid press material according to a third embodiment.

FIG. 4 is a view showing a fourth embodiment, a process for obtaining a drive hub intermediate product having a flange at an outer peripheral intermediate portion from a solid press material.

FIG. 5 is a detailed view of a first step (b) in FIG. 1;

FIG. 6 is a detailed view of a second step (c) in FIG.

FIG. 7 is a detailed view of a first step (b) in FIG. 3;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Completed product, 1A ... Intermediate member, 10 ... Hollow press material, 11 ... Thick part, 12 ... Inner diameter thin cylindrical part, 13 ... Flange part, 14 ... Outer diameter cylindrical part, 101 ... Mandrel, 1
02: knockout sleeve, 103: counter punch, 104: lower die, 105: upper die, 106: hollow punch.

Claims (6)

[Claims] 1. A method of manufacturing a drive hub formed in the following steps: a) A hollow punch having an outer diameter smaller than an outer diameter of a hollow press material made of metal and an inner diameter larger than the outer diameter of the mandrel. The press material placed in the forming die space is pressed vertically to the vicinity of the contact plane between the lower die and the upper die, and the press material is plastically flowed around and backward along the mandrel and the upper and lower dies to form a flange forming space. And forming an intermediate member by filling the gap. b) a step of arranging the intermediate member on another forming die and pressing it with a hollow punch to obtain a near-finished product with a small finishing margin; c) A step of cutting the fine finishing allowance to obtain a finished product. 2. A method for manufacturing a drive hub according to claim 1, wherein the hollow cylindrical press material is a material having a thin cylindrical portion having the same outer diameter in advance on an outer peripheral portion on one surface. 3. The method for manufacturing a drive hub according to claim 1, wherein the flange portion is plastically deformed along a taper formed on an inner peripheral portion of the upper die. 4. A method of manufacturing a drive hub formed by the following steps: a) an outer shape of a solid disc-shaped press material made of metal disposed in a forming die space formed by a lower die and an upper die; The press material is pressed vertically to the vicinity of the contact plane between the lower die and the upper die by a hollow punch having a smaller outer diameter and a hollow center, and the press material is pressed into the hollow portion of the hollow punch and the upper and lower dies. Forming an intermediate member by plastically flowing along the periphery and rearward along the flange portion forming space and the hollow portion of the hollow punch. b) a step of arranging the intermediate member on another forming die and pressing it with a hollow punch to obtain a near-finished product with a small finishing margin; c) A step of cutting the fine finishing allowance to obtain a finished product. 5. A manufacturing method of a drive hub according to claim 4, wherein the solid disc-shaped press material is a material having a thin cylindrical portion having the same outer diameter in advance on an outer peripheral portion of one surface. Method. 6. A method for manufacturing a drive hub according to claim 4, wherein the flange portion is plastically deformed along a taper formed on an inner peripheral portion of the upper die.