JP2003193113A - Sintered product, method for forming sintered product, and forming die - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily obtain a sintered product having fall-off-stopping shape and a rotation-stopping shape and suitably used as a resin insert at a low cost. <P>SOLUTION: Material powder is compacted and the green compact is sintered to obtain the sintered product 10. The sintered product 10 is provided with axially extending recessed parts 12 and a circumferentially extending diameter- expanded part 13. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a sintered product suitable for a resin insert.

[0002]

2. Description of the Related Art Heretofore, an insert method has been known in which a resin is injected into a mold loaded with an insert product to manufacture a composite part in which the insert product and a molten resin are integrated. With the insert method, it is possible to manufacture composite parts that integrally include multiple types of materials that have different properties such as resin and metal with good workability. For example, by integrating a sintered part with a resin part as an insert product, Therefore, it is possible to easily obtain a composite part that can be driven without oil.

Generally, a radial load, a thrust load, or both are applied to a composite part composed of a resin part and a sintered part. Therefore, the sintered part to be resin-inserted has a rotation stopper for preventing the resin part from rotating. Shape or
It is necessary to provide a retaining shape that prevents the embedded resin component from falling off in the axial direction.

The rotation of the sintered part with respect to the resin part is performed by, for example, providing a linear groove 52 over the entire axial length on the outer peripheral surface 51 of the part 50 as shown in FIG. 5, and letting the resin enter the linear groove 52. Can be prevented. The linear groove 52 is formed by forming a ridge extending in the compression direction on the inner peripheral surface of a mold for molding the component 50, so as to perform compression molding for forming a green compact or sizing (recompression) after sintering. Can be formed.

[0005]

Further, the axial detachment of the sintered part from the resin part is caused by the above-mentioned outer peripheral surface 5 of the part 50.
This can be prevented by providing a peripheral groove 53 on the base plate 1 as shown in FIG. 6 and allowing resin to enter the peripheral groove 53. However, since the shape of the circumferential groove 53 is an undercut shape, it cannot be formed with a mold like the straight groove 52, and must be formed by machining. For this reason, in order to manufacture a sintered part having both a retaining shape and a rotation stopping shape, a device for machining further in addition to resin insert molding and a machining time are required, resulting in poor workability. Manufacturing cost is high,
There was a problem of poor productivity.

The present invention has been made in view of the above problems, and it is an object of the present invention to provide a sintered component having a retaining shape and a rotation stopping shape, which is suitable for a resin insert, easily and at low cost. To aim.

[0007]

In order to solve the above problems, a sintered product according to the invention of claim 1 is formed by sintering a green compact obtained by compression molding of a material powder, It is characterized by having a concavo-convex portion that extends in the axial direction and a diameter-enlarged portion that extends in the circumferential direction. According to this invention, since the sintered product is provided with the uneven portion extending in the axial direction and the enlarged diameter portion extending in the circumferential direction, when the product is insert-molded as an insert product, the uneven portion is formed. And the resin are integrated so that they mesh with each other, and the relative rotation between the sintered product and the resin part can be suppressed, and the expanded diameter part is integrated so as to bite into the resin part, thereby allowing relative movement in the axial direction. That is, the omission can be suppressed. Since such an uneven shape portion and an enlarged diameter portion can be easily formed by a compression molding die for material powder or a correction die for sizing (for recompression) of a sintered body, a retaining shape and a rotation stopper are provided. A sintered product having a shape can be provided easily and at low cost.

A method of molding a sintered product according to a second aspect of the present invention comprises a compression step of compression molding material powder to form a green compact, and a sizing for sizing the sintered body obtained by sintering the green compact. A method of molding a sintered product, comprising the steps of:
In the compression process, mold the uneven portion extending in the axial direction,
The sizing step is characterized in that a diameter-expanded portion extending in the circumferential direction is formed. According to the present invention, after forming a green compact having a concavo-convex shaped portion extending in the axial direction in the compression step, the sizing step of sizing the sintered body obtained by sintering the green compact is sintered. Since the enlarged diameter portion that extends in the circumferential direction is formed on the body, the retainer and rotation stopper can be performed without performing steps such as machining for forming the retainer groove, which are not necessarily required for manufacturing the sintered product. A sintered product having a shape can be easily molded.

A molding die according to a third aspect of the present invention is a molding die used for compression molding of material powder or sizing of a sintered body, which comprises a core rod for molding the inner peripheral surface of the molded body and an outer periphery. An upper first punch and a lower first punch for shaping a surface; an upper second punch that is located between the core rod and the upper first punch to shape the upper end surface of the compact; and a core rod and a lower first punch. A lower second punch that is located between the upper second punch and the lower second punch for shaping the lower end surface of the compact, and the inner peripheral surfaces of the tips of the upper first punch and the lower first punch, which are in contact with each other, have a recess whose tip side is open. It is characterized by being provided. According to this invention, since the concave portions are formed on the inner peripheral surfaces of the tip portions of the upper first punch and the lower first punch, respectively, when the upper first punch and the lower first punch are brought into contact with each other, Since the cavity having the band-shaped concave groove in which the concave portions are integrated is formed, the molded object is arranged on the inner peripheral side of this concave groove and the molded object is formed by the upper second punch and the lower second punch from above and below. By compressing the upper and lower end surfaces, it becomes possible to easily form a molded body having an enlarged diameter portion in accordance with the shape of the cavity.

A molding die according to a fourth aspect of the present invention is a molding die used for compression molding of material powder or sizing of a sintered body, and a core rod for molding an inner peripheral surface of the molded body, Upper first punch and lower first for molding the outer peripheral surface
The punch is located between the core rod and the upper first punch to form the upper end surface of the compact, and the upper second punch is located between the core rod and the lower first punch to mold the lower end surface of the compact. And a lower second punch for preventing the upper first punch and the lower first punch from coming into contact with each other when the upper and lower end surfaces of the compact are axially compressed by the upper second punch and the lower second punch. It is characterized by being. According to the present invention, since the upper first punch and the lower first punch do not come into contact with each other,
The molding die is provided with a band-shaped portion that does not radially restrain the vicinity of the central portion of the outer peripheral surface of the molding target in the axial direction. Therefore, by deforming the body compressed from above and below so as to be extruded to this portion, it is possible to easily form the molded body having the expanded diameter portion.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to FIGS. FIG. 1 shows a molded body (sintered product) 10 according to an embodiment of the present invention.
The molded body 10 is formed by sintering and sizing (recompressing) a green compact obtained by compressing and molding a material powder, and one or more groove portions (concave-shaped portion) 12 on an outer peripheral surface 11. One expanded diameter portion 13 is provided (four in this embodiment at equal intervals). The groove portion 12 is one end surface 1 of the molded body 10.
4 extends along the axial direction to the other end surface 14.
The enlarged diameter portion 13 extends in the circumferential direction and is formed as a ridge divided by the groove portion 12.

When the molded product 10 having such a shape is inserted into a resin part as an insert product, the groove 12 is formed.
When the resin enters into the resin and hardens, relative rotation with respect to the resin portion is suppressed, and the expanded diameter portion 13 is inserted so as to bite into the resin, whereby the relative movement or removal of the resin portion in the axial direction Is suppressed. Therefore, the molded body 10 having the groove portion 12 and the enlarged diameter portion 13 does not easily fall off from the resin component even when subjected to a radial load or a thrust load in the resin component, and can be used stably. In the figure, the enlarged diameter portion 13 is shown as the molded body 1.
Although it is largely projected from the outer peripheral surface 11 of 0, even if the projection amount is smaller than that shown in the figure, a sufficient retaining effect can be obtained.

The above-mentioned groove portion 12 and expanded diameter portion 13 are sized (recompressed) during compression molding of material powder or after sintering.
It can sometimes be formed. Hereinafter, a case where the expanded diameter portion 13 is formed during sizing will be described.

2 and 3, the expanded diameter portion 13 of the molded body 10 of this embodiment is formed on a cylindrical sintered body 15 obtained by sintering a green compact obtained by compression molding of material powder. The outline of the mold for doing is shown. This die is a straightening die 20 for sizing (recompression) for re-compressing the sintered body 15 to improve shape accuracy, and is a lower punch 2 that is moved in the axial direction.
2. The upper punch 27 and the core rod 26 are provided.
The lower punch 22, the upper punch 27 and the core rod 26 are
As shown in FIG. 3, the through hole 21a formed in the die 21
A cylindrical cavity C is formed inside which is used to mold the molded body 10. 2 shows the die before compression, and FIG. 3 shows the die at the time of compression. The sintered body 15 before being recompressed by the correction die 20 has a groove 12 on the outer surface of the cylinder.
Are formed.

The lower punch 22 has a through hole 21a in the die 21.
The lower cylindrical first punch 23 inserted into the
The cylindrical lower second punch 2 fitted inside the punch 23.
4 and. A cylindrical block 25 forming the lower half of the outer peripheral surface of the molded body 10 is fixed to the inner peripheral portion of the upper end of the lower first punch 23. On the other hand, the upper punch 27 includes a cylindrical upper first punch 28 which is fitted and inserted in the through hole 21 a of the die 21, and a cylindrical upper second punch 29 which is fitted and inserted inside the upper first punch 28. ing. A cylindrical block 30 forming the upper half of the outer peripheral surface of the molded body 10 is fixed to the inner peripheral portion of the lower end of the upper first punch 28.

The block 25 has an inner peripheral surface 25a having an inner diameter substantially equal to the outer diameter of the sintered body 15 and forms the lower half of the outer peripheral surface of the cavity C. At the upper end portion (tip portion) of the inner peripheral surface 25a, a concave portion 25b whose tip side is open is formed.
Is provided. Furthermore, the sintered body 1 is formed on the inner peripheral surface 25a.
A ridge (not shown) fitted in the groove 12 of No. 5 extends in the axial direction. On the other hand, the block 30 has an inner peripheral surface 30a having an inner diameter substantially equal to the outer diameter of the sintered body 15, and has a cavity C
The upper half of the outer peripheral surface is formed. This inner surface 3
The lower end portion (tip portion) of 0a is provided with a concave portion 30b whose front end side is open. Further, on the inner peripheral surface 30a, a ridge (not shown) that fits into the groove 12 of the sintered body 15 is extended in the axial direction.

Next, the formation of the expanded diameter portion 13 by the straightening die 20 constructed as described above will be described with reference to FIGS.
Will be described with reference to. First, as shown in FIG. 2, the upper punch 27 (the upper first punch 28 and the upper second punch 29) is lifted, the upper surface of the lower punch 22 is aligned with the upper surface of the die 21, and The sintered body 15 is placed on. Then, the upper punch 27 is lowered so that both end surfaces 14 of the sintered body 15 are brought into contact with the lower surface of the upper second punch 29 and the lower second punch 24.
It is restrained by the upper surface and the blocks 30 and 25 are fitted to the outside of the sintered body 15, and the core rod 26
Is fitted inside the sintered body 15.

Further, as shown in FIG. 3, in the die 21, the upper first punch 28 (block 30) lower surface and the lower first punch 23 (block 25) upper surface come into contact with each other.
7 and the lower punch 22 are lowered to form the recess 25b and the recess 3
A cavity C having a band-shaped concave groove B integrated with 0b is formed. In this manner, with the upper first punch 28 and the lower first punch 23 in contact with each other, the lower second punch 24 and the upper second punch 29 are axially pressed against each other and the sintered body 15 is pressed.
By compressing, the sintered body 15 is plastically deformed along the shape of the cavity C. That is, the sintered body 15
Is re-compressed and molded by the straightening die 20 into a shape with good accuracy, and the outer peripheral surface 11 is deformed so as to enter the concave groove B to form the expanded diameter portion 13.

Next, regarding another embodiment of the present invention,
This will be described with reference to FIG. The molding die shown in FIG. 4 is for sizing (recompression) for recompressing the molded body (sintered body) to improve the shape accuracy, as in the first embodiment. A lower punch 41, an upper punch 44 and a core rod 47 which are movable in the axial direction are arranged in a through hole 48a formed in a die 48, and a molded body is compression molded,
It is a straightening die 40 that forms a molded body 49 having an enlarged diameter portion 49a extending in the circumferential direction near the central portion in the axial direction.

The lower punch 41 has a through hole 48a in the die 48.
A cylindrical lower first punch 42 fitted in the
Cylindrical lower second punch 4 fitted inside punch 42
3 and 3. On the other hand, the upper punch 44 includes a cylindrical upper first punch 45 fitted in the through hole 48 a of the die 48,
A cylindrical upper second punch 46 fitted inside the upper first punch 45 is provided. These lower first punch 4
2, lower second punch 43, upper first punch 45 and upper second
The end faces in the axial direction of the punch 46 are all flat.

In this straightening die 40, as shown in FIG. 4, the lower first punch 42 and the upper first punch 45 during compression molding are used.
Are provided so as not to abut each other. Therefore, in the molded body, the inner peripheral surface 49b is constrained by the core rod 47, and the lower first punches 4 arranged at intervals.
The outer peripheral surfaces 49c and 49d near the upper and lower ends are constrained by the lower second punch 43 and the upper second punch 46 while being constrained by the lower second punch 43 and the upper second punch 46, respectively. The expanded first diameter portion 49a is formed by being deformed so as to be extruded between the lower first punch 42 and the upper first punch 45 which are not present.

The shapes, combinations and the like of the respective constituent members shown in the above embodiment are examples, and can be variously changed based on design requirements and the like without departing from the spirit of the present invention. In the above-described embodiment, the expanded diameter portion is formed by the straightening mold for sizing, but a mold forming a closed cavity as shown in FIG. 2 and FIG. 3 is used, and the groove portion and the expanded portion are formed in the step of compacting. It is also possible to form into a shape having a diameter portion. In this case, the lower second punch 24 is greatly lowered so that the space formed between the lower second punch 24, the block 25, and the core rod 26 can be filled with the material powder in an amount necessary for forming a compact, Material powder may be filled in this space, and the lower punch 22 and the upper punch 27 may be lowered into the die 21 for compression molding as shown in FIG.

[0023]

As described above, according to the sintered product of the first aspect of the invention, the sintered product is provided with the uneven portion extending in the axial direction and the enlarged diameter portion extending in the circumferential direction. Therefore, when this product is insert-molded with resin as an insert product, the concavo-convex shape part and the resin are integrated so that they mesh with each other, so that relative rotation between the sintered product and the resin part can be suppressed, and the expanded part By being integrated so as to bite into the resin portion, relative movement in the axial direction, that is, slipping out can be suppressed. Since such an uneven shape portion and an enlarged diameter portion can be easily formed by a compression molding die for material powder or a correction die for sizing (for recompression) of a sintered body, a retaining shape and a rotation stopper are provided. A sintered product having a shape can be provided easily and at low cost.

According to the method for forming a sintered product according to the second aspect of the present invention, the green compact is formed by forming the green compact having the concavo-convex portion extending in the axial direction in the compression step and then sintering the green compact. In the sizing step of sizing the obtained sintered body, since the expanded diameter portion extending in the circumferential direction is formed in the sintered body, it is not always necessary to manufacture a sintered product, such as machining for forming a groove for retaining. It is possible to easily form a sintered product having a retaining shape and a rotation preventing shape without performing unnecessary steps.

According to the molding die of the third aspect of the present invention, since the upper first punch and the lower first punch have the concave portion on the inner peripheral surface of the tip portion, these upper first punches are provided. And the lower first punch is brought into contact with each other to form a cavity having a band-shaped concave groove in which the respective concave portions are integrated. Therefore, the object to be molded is arranged on the inner peripheral side of the concave groove so that the upper first By compressing the molded body in the axial direction by the two punches and the lower second punch, it becomes possible to easily form the molded body having the expanded diameter portion according to the cavity shape.

According to the molding die of the fourth aspect of the present invention, since the upper first punch and the lower first punch do not come into contact with each other, the molding die has an axial direction of the outer peripheral surface of the molding target. Since the concave groove that does not restrain the vicinity of the central portion is provided in a band shape, when the molded body is axially compressed inside the concave groove, the molded body is deformed so as to be pushed into the concave groove. Therefore, it is possible to easily form the molded body having the expanded diameter portion without using a special mold structure or a mold having a special shape.

[Brief description of drawings]

FIG. 1 is a perspective view showing a sintered product according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a state before compression of the molding die according to the embodiment of the present invention.

FIG. 3 is a cross-sectional view showing a state of the molding die shown in FIG. 2 during compression.

FIG. 4 is a sectional view showing a molding die according to another embodiment of the present invention.

FIG. 5 is a perspective view showing a conventional sintered product having an anti-rotation shape.

FIG. 6 is a perspective view showing a sintered product having a conventional rotation stop and retaining shape.

[Explanation of symbols]

10,49 Sintered product (molded body) 11 outer peripheral surface 12 Concavo-convex shape part (groove part) 13, 49a Expanded part 15 Sintered body 20, 40 Mold for molding (correction mold) 23,42 Lower first punch 24,43 Lower second punch 25a inner peripheral surface 25b recess 26, 47 core rod 28,45 Upper first punch 29,46 Upper second punch 30a inner peripheral surface 30b recess

Claims (4)

[Claims] 1. A compact formed by sintering a material powder, which is formed by sintering, and has an uneven portion extending in the axial direction and a diameter expanding portion extending in the circumferential direction. Sintered product. 2. A method of molding a sintered product, comprising: a compression step of compression molding a material powder to form a green compact, and a sizing step of sizing a sintered body obtained by sintering the green compact. Then, in the compressing step, a concavo-convex shape portion that extends in the axial direction is formed, and in the sizing step, a diameter-expanded portion that extends in the circumferential direction is formed. 3. A molding die used for compression molding of material powder or sizing of a sintered body, comprising a core rod for molding an inner peripheral surface of the molded body, an upper first punch and a lower punch for molding an outer peripheral surface thereof. Formed between a first punch, an upper second punch located between the core rod and the upper first punch to form the upper end surface of the compact, and located between the core rod and the lower first punch. A lower second punch for shaping a lower end surface of the body, and a concave portion having an open front end is provided on inner peripheral surfaces of the upper first punch and the lower first punch tip portions which are in contact with each other. Molding die characterized by. 4. A molding die used for compression molding of material powder or sizing of a sintered body, comprising a core rod for molding the inner peripheral surface of the molded body, and an upper first punch and a lower punch for molding the outer peripheral surface. Formed between a first punch, an upper second punch located between the core rod and the upper first punch to form the upper end surface of the compact, and located between the core rod and the lower first punch. A lower second punch for shaping the lower end surface of the body, wherein the upper first punch and the lower first punch are mutually compressed when the upper and lower end surfaces of the compact are axially compressed by the upper second punch and the lower second punch. A molding die, which is provided so as not to abut.