JPH1085995A - Method for making surface of sintered part dense - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method useful for enlarging a drawing margin and also for making sintered parts dense. SOLUTION: The first 11, second 12 and third 13 differences in level are arranged on the inner circumference of the cavity 10 of a die 1, serially along the direction of the axial line P1 of the cavity 10. With a sintered part W inserted in the cavity 10, the part W passes through the first 11, second 12 and third 13 differences in level successively; therefore, a plural number of sizing process are carried out in one inserting operation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for densifying a surface of a sintered part such as a sintered gear part.

[0002]

2. Description of the Related Art A sintered gear part will be described as an example of a sintered part. Conventionally, in the field of sintered gear parts, FIG.
As shown in FIG. 5, a sizing process is performed on the sintered gear part W1 by pressing the sintered gear part W1 into the die hole 100 using a die 100 having a die hole 101, and Techniques for adjusting the dimensions of W1 and the like are known. According to this technology, the sintered gear part W
Along with the dimensional adjustment of 1, the surface densification of the sintered gear component W1, particularly the outer peripheral portion of the sintered gear component W1, is promoted.

[0003] As a technique for densifying the surface of a sintered gear part, Japanese Patent Application Laid-Open No. 6-501988 discloses a technique for densifying the surface of a sintered gear part using a rolling device to improve the strength of the sintered gear part. A technique for improving wear resistance has been disclosed.

[0004]

According to the technique shown in FIG. 7, however, the surface of the sintered gear part W1 can be densified, but there is a limit to the ironing allowance in one pushing operation. Further, there is a limit in improving the surface densification of the sintered gear component W1. Further, according to the above-mentioned publication technology, rolling equipment is required, which is not always sufficient in terms of cost and productivity.
Further, in rolling, there is a limit to the improvement of gear accuracy due to the influence of tooth profile error, tooth lead error, and the like.

The present invention has been made in view of the above-mentioned circumstances, and by increasing the ironing allowance obtained by one pressing operation, the surface density of a sintered part is improved in terms of productivity and surface densification. It is an object to provide a conversion method.

[0006]

According to a first aspect of the present invention, there is provided a method for densifying a surface of a sintered component, comprising a die hole into which the sintered component is inserted, and an inner peripheral portion of the die hole along an axial direction of the die hole. In a single operation of pressing a sintered part into a die hole using a die having a plurality of steps arranged in series, a plurality of sizing processes are sequentially performed by sequentially passing the sintered part through the steps. It is characterized by performing.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As a sintered part used in the method of the present invention, a disk-shaped part can be adopted. For example, sintered gear parts are typical. In sintered parts, voids that induce a decrease in strength may remain, so there is a situation where the surface needs to be densified. The material of the sintered component used in the method of the present invention can be appropriately selected, and it does not matter whether it is ferrous or non-ferrous.

[0008] According to the method of the present invention, in one operation of pushing the sintered part into the die hole, the sintered part is sequentially passed through the step, whereby a plurality of sizing processes are sequentially performed.

[0009]

【Example】

(First Embodiment) An embodiment of the present invention will be described below with reference to FIG. The left part of FIG. 1 shows before sizing processing,
The right part of FIG. 1 shows the state after the sizing process. The die 1 is a die and is fixed to a press. Dice 1
It has a die hole 10 into which a sintered gear part W as a sintered part is inserted. A ring-shaped first step 11, a ring-shaped second step 12, and a ring-shaped third step 13 are arranged in series at the inner peripheral portion of the die hole 10 toward the back along the direction of the axis P1 of the die hole 10. Are located in Therefore, the die hole 10
A first ring-shaped sizing surface 15, a second ring-shaped sizing surface 16, a third ring-shaped sizing surface 17, and a fourth ring-shaped sizing surface 18 are provided on the inner periphery of the axis P <b> 1.
Are arranged in series along the direction. The axis P1 is arranged along the vertical direction.

In this embodiment, the ironing allowance of the entire die hole 10 can be appropriately selected according to the type of the sintered gear part W. For example, if the diameter of the tooth tip of the sintered gear component W before the sizing process is 100 mm, the entire ironing allowance of the die hole 10 can be about 0.3 mm to 1 mm. For example, 0.6
mm. That is, in the case of 0.6 mm, the ironing allowance is (0.6 / 100) × 100 = 0.6%.
Accordingly, the ironing allowance in FIG. 1 is exaggerated for ease of understanding.

In the present embodiment, the ironing allowance from the first sizing surface 15 to the second sizing surface 16 is δ1, and the ironing allowance from the second sizing surface 16 to the third sizing surface 17 is δ.
2. If the ironing allowance from the third sizing surface 17 to the fourth sizing surface 18 is δ3, δ1 = δ2 = δ3.
That is, in the above case, δ1 = δ2 = δ3 = 0.2 mm
Can be. Further, depending on the sintered gear part W, δ1> δ2
> Δ3, or δ1 <δ2 <δ3.
Note that the relationship of the ironing allowance is not limited to the above relationship.

An upper punch 30 is provided above the die 1 so as to be able to move up and down in a press machine. The upper punch 30 has a tip surface 30x. With the lower punch 32 fitted in the die hole 10, the press machine is provided so as to be able to move up and down. The lower punch 32 has a tip surface 32x. FIG. 2 shows a plan view of the sintered gear part W before sizing. As shown in FIG. 2, external teeth Wc are continuously formed in the circumferential direction on the outer peripheral portion of the sintered gear component W. Accordingly, the first sizing surface 15 to the fourth sizing surface 18 and the first to third steps 11 to 13 are also configured such that the external teeth are continuous in the circumferential direction.

The sintered gear part W used in the present embodiment is an iron-based material. It is formed through a binding step. In the sintered gear component W passing through the green compact, pores may remain. Now, when sizing the sintered gear part W, the sintered gear part W is set near the opening of the die hole 10 with the upper punch 30 positioned above and the lower punch 32 positioned near the opening of the die hole 10. You. Then, in a state where the shaft end surface of the sintered gear component W is sandwiched between the distal end surface 30x of the upper punch 30 and the distal end surface 32x of the lower punch 32, the sintered gear component W is moved toward the back of the die hole 10 in the direction of arrow Y1. Is inserted. The pressing operation of the sintered gear part W is performed once.

In this case, the sintered gear component W sequentially passes through the first step 11, the second step 12, and the third step 13.
In other words, the sintered gear part W is the first sizing surface 1
5, the second sizing surface 16, the third sizing surface 17, and the fourth sizing surface 18 sequentially pass. As a result, a plurality of ironing operations, that is, a plurality of sizing processes, are performed on the sintered gear component W.

Thereafter, the upper punch 30 and the lower punch 32 are raised, and the sintered gear part W is also raised. Die hole 1
When reaching the vicinity of the opening 0, the lower punch 32 stops rising, but the upper punch 30 further rises. Thereafter, the sintered gear component W is taken out from the die hole 10.
As can be understood from the above description, according to the present embodiment, the sintered gear component W sequentially passes through the first step 11, the second step 12, and the third step 13 of the die hole 10. Therefore, it is advantageous to increase the ironing allowance as compared with the related art shown in FIG. 7 having one step. Therefore, it is advantageous also for densification of the sintered gear part W. In particular, it is advantageous for densification of the outer peripheral portion such as the vicinity of the root of the sintered gear component W.

According to this embodiment, conventional equipment can be used as it is, except for the die 1, and specifically, a press machine,
Since the upper punch 30 and the lower punch 32 can be used as they are, it is advantageous for making the sintered gear component W dense while reducing costs and improving productivity. The ironing allowance can be appropriately adjusted according to the required strength of the sintered gear component W required.

(Second Embodiment) A second embodiment shown in FIG.
The configuration is basically the same as that of the first embodiment, and has the same operation and effect. A ring-shaped first step 11 and a ring-shaped second step 12 are arranged in series in the inner peripheral portion of the die hole 10 along the direction of the axis P <b> 1 of the die hole 10. Therefore, a ring-shaped first sizing surface 15, a ring-shaped second sizing surface 16, and a ring-shaped third sizing surface 17 are arranged in series in the inner peripheral portion of the die hole 10 along the direction of the axis P <b> 1 of the die hole 10. Are located in

(Third Embodiment) A third embodiment shown in FIG.
The configuration is basically the same as that of the first embodiment, and has the same operation and effect. That is, a ring-shaped first step 11, a ring-shaped second step 12, and a ring-shaped third step 13 are arranged in series in the inner peripheral portion of the die hole 10 along the direction of the axis P1 of the die hole 10. Have been.

The amount of protrusion of the first step 11 in the radial direction is represented by V
1. If the amount of protrusion of the second step 12 in the radial direction is V2 and the amount of protrusion of the third step 13 in the radial direction is V3, V1 <V
2 <V3 is set. Therefore, the ironing allowance is set so as to gradually increase from the first step 11 to the third step 13. In this embodiment, the projecting amount of the second step 12 in the radially inner direction is V2, the second step 12, the third step 13 where the first step 11, the second step 12, and the third step 13 are perpendicular to the axis. It is inclined by θ.

Also in this example, the sintered gear part W is provided with the first step 11, the second step 12, and the third step 1 of the die hole 10.
3 sequentially. Therefore, even if the sintered gear part W is only pushed once into the die hole 10, the sizing process is performed a plurality of times. Furthermore, the sintered gear part W
Since it passes through the first step 11, the second step 12, and the third step 13 of the die hole 10 sequentially, it is advantageous to increase the ironing allowance.

As shown in FIG. 4, the first step 11, the second step
Since the step 12 and the third step 13 are inclined, when the sintered gear component W is pushed in, the ironing process is not applied to the entire outer periphery of the sintered gear component W, but the sintering is performed. Ironing is gradually applied to the outer peripheral portion of the gear component W. That is, the local ironing process is in a form that is successively continued in the circumferential direction of the sintered gear component W.

Therefore, it is possible to prevent the load required for the ironing operation from becoming excessive, which is advantageous for reducing the load required for the ironing operation. Therefore, it is also advantageous in preventing the occurrence of cracks and the like in the sintered gear part W. (Fourth Embodiment) In a fourth embodiment shown in FIG. 5, first to third ring grooves 51 to 53 formed in the inner peripheral portion of the die hole 10 of the die 1 are formed coaxially. The first ring body 61 is fitted in the first ring groove 51. The second ring body 62 is fitted in the second ring groove 52. A third ring body 63 is fitted in the third ring groove 53. The first ring body 61 to the third ring body 63 are coaxially arranged.

In this embodiment, if the inside diameter of the first ring body 61 is D1, the inside diameter of the second ring body 62 is D2, and the inside diameter of the third ring body 63 is D3, then D1>D2> D3. ing. Therefore, the inner peripheral surface of the first ring body 61 forms the first step 11, and the inner peripheral surface of the second ring body 62
The step 12 is formed, and the inner peripheral surface of the third ring body 63 forms the third step 13.

According to this embodiment, as in the case of the first embodiment, the sintered gear part W is provided with the first step 1 of the die hole 10.
In order to sequentially pass through the first step 12, the second step 12, and the third step 13,
Even if only one pushing operation of the sintered gear part W is performed,
Multiple sizing processes are performed. Further, similarly to the above-described embodiment, the sintered gear component W
Since it sequentially passes through the step 11, the second step 12, and the third step 13, it is advantageous to increase the ironing allowance. Therefore, it is advantageous also for densification of the sintered gear part W. In particular, it is advantageous for densification of the outer peripheral portion such as the vicinity of the root of the sintered gear component W.

According to this embodiment, if the first to third ring members 61 to 63 are worn or damaged, the first to third ring members 61 to 63 can be replaced as appropriate. (Fifth Embodiment) The fifth embodiment shown in FIG. 6 has basically the same configuration as the embodiment shown in FIG. 5, and basically has the same operation and effect.

A first ring groove 51 to a third ring groove 53 are formed in an inner peripheral portion of the die hole 10 of the die 1. The depth of the first ring groove 51 is h1, the depth of the second ring groove 52 is h2, and the depth of the third ring groove 53 is h.
Assuming that 3, h1>h2> h3. The first ring body 61 is fitted in the first ring groove 51. Second
A second ring body 62 is fitted in the ring groove 52.
A third ring body 63 is fitted in the third ring groove 53. The first ring body 61 to the third ring body 63 are coaxially arranged. The first ring body 61 to the third ring body 6
3 has a C-ring shape.

In this embodiment, the depths h1 to h3 of the first to third ring grooves 51 to 53 are changed so that h1>h2> h
3, the amount of projection of the first ring body 61 to the third ring body 63 in the radial direction is changed. Accordingly, if the inner diameter of the first ring body 61 is D1, the inner diameter of the second ring body 62 is D2, and the inner diameter of the third ring body 63 is D3,
As described above, D1>D2> D3 is set.

In this embodiment, the inner peripheral surface of the first ring body 61 forms the first step 11, and the inner peripheral surface of the second ring body 62 forms the second step 12, as in the above-described embodiment. The inner peripheral surface of the third ring body 63 forms the third step 13. According to this embodiment, similarly to the above-described embodiment, the sintered gear component W sequentially passes through the first step 11, the second step 12, and the third step 13 of the die hole 10, so that the ironing allowance is increased. It is advantageous to do. Therefore, it is advantageous also for densification of the sintered gear part W. In particular, it is advantageous for densification of the outer peripheral portion such as the vicinity of the root of the sintered gear component W.

According to this embodiment, if the first to third ring members 61 to 63 are worn or damaged, the first to third ring members 61 to 63 can be replaced.

[0030]

According to the method of the present invention, in one operation of pushing a sintered part into a die hole, a plurality of sizing processes are sequentially performed by sequentially passing the sintered part through a step. . Therefore, it is advantageous in terms of surface densification and productivity of the sintered part.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view according to a first embodiment, in which a left part shows a state before a sizing processing, and a right part shows a state after a sizing processing.

FIG. 2 is a plan view of a sintered gear component.

FIG. 3 is a cross-sectional view according to a second embodiment, in which a left part shows a state before the sizing processing, and a right part shows a state after the sizing processing.

FIG. 4 is a sectional view of a main part according to a third embodiment.

FIG. 5 is a sectional view of a main part according to a fourth embodiment.

FIG. 6 is a sectional view of a main part according to a fifth embodiment.

FIG. 7 is a cross-sectional view according to the related art, in which a left part shows a state before the sizing processing, and a right part shows a state after the sizing processing.

[Explanation of symbols]

In the figure, 1 is a die, 10 is a die hole, W is a sintered gear part (sintered part), 11 is a first step, 12 is a second step, 13
Denotes a third step, 15 denotes a first sizing surface, 16 denotes a second sizing surface, 17 denotes a third sizing surface, and 18 denotes a fourth sizing surface.

Claims (1)

[Claims] 1. A die having a die hole into which a sintered component is inserted, and having a plurality of steps arranged in series in an inner peripheral portion of the die hole along an axial direction of the die hole, In one operation of pressing a sintered part into the die hole, a plurality of sizing processes are sequentially performed by sequentially passing the sintered part through the steps, and the surface density of the sintered part is characterized by Method.