JPH0813005A - Production of metal powder sintered parts - Google Patents

Abstract

PURPOSE:To produce the metal powder sintered parts through a small number of processes at a low cost. CONSTITUTION:When metal powder sintered parts each having sliding part are produced through a process for injection-molding a compound prepd. by kneading the metal powder with an org. binder into a desired shape, a process for dewaxing the resultant injection-molded body and a process for sintering the dewaxed body, a part (a) previously coated with a ceramics coating film is disposed at the cavity part of a metal mold for injection molding and a part (b) is formed around the part (a) by injection-molding the compound. An assembling process is eliminated and the cost is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a metal powder sintered part having a sliding relationship between its constituent parts.

[0002]

2. Description of the Related Art Conventionally, a metal powder sintered part as described above is injected by a compound in which a metal powder and an organic binder are kneaded in a specific composition as disclosed in Japanese Patent Laid-Open No. 229403/1984. After being molded, it is manufactured through a degreasing process and a sintering process. At this time, the shape of the sintered part to be obtained complicates the mechanism of the mold for mold splitting and the like, and when it is difficult to manufacture the mold, divide the sintered part into multiple parts. However, they are combined after they are separately injection-molded, but the above publication does not specifically disclose a combination of a plurality of parts and an assembling method. On the other hand, in plastic molding, in order to eliminate the assembly process, a method of integrating a plurality of parts at the time of injection molding is performed by using a known insert molding method.

[0003]

However, when insert molding is applied to the metal powder injection molding method, the injection molded body (green part) can be integrated, but the individual parts are contacted by sintering. It is not possible to produce products that slide after sintering because the parts agglomerate. Therefore, after all, the individual parts must be separately sintered and then separately assembled. Therefore, there has been a problem that the product cost increases due to the increase in the number of processes.

The inventions according to claims 1 to 3 have been made in view of such conventional problems, and provide a method for producing a metal powder sintered part which has a small number of steps and can be produced at low cost. To aim.

[0005]

In order to solve the above-mentioned problems, the invention according to claim 1 relates to a step of injection-molding a compound obtained by kneading a metal powder and an organic binder into a desired shape, and this injection-molded article. And a step of sintering the obtained degreased body, in the method of manufacturing a metal powder sintered part having a sliding portion, the upper part preliminarily coated with the ceramics film is used as an injection molding die. It was placed in the cavity, and the second component was injection-molded around the instep component by the compound.

According to a second aspect of the present invention, in the first aspect of the invention, the upper part and the second part that are fitted by injection molding in the mold are taken out as a unit, and then degreased and sintered. Is characterized by.

The invention according to claim 3 is characterized in that the injection molding is performed with a spacer made of a main component material of the organic binder contained in the compound being interposed in the sliding portion between the upper part and the second part. And

That is, the present invention is a method of assembling a metal powder sintered part having sliding parts between constituent parts so that it can be slid afterwards inside a mold by a metal powder injection molding method.

The concept of the present invention will be described with reference to FIGS. 3 and 4, taking as an example the case of assembling a product 1 shown in the perspective view of FIG. 1 and the vertical plan view of FIG. The product 1 is composed of two parts, a part (instep part) a and a part (external part) b, and both of them slide on the fitting part 2.

As shown in FIG. 3, first, a part a having a ceramic coating 3 formed by powder or vapor deposition on its surface in advance is inserted into a movable insert 5 (cavity) of a mold 4 by parting, and then, The mold is closed to form a cavity for molding the component b in a portion surrounded by the component a, the movable insert 5 and the fixed insert 6. In this cavity, a spacer 19 made of a plastic material, which is the main component of the organic binder contained in the compound, is arranged in a part of the fitting part 2 of the two parts, and a mold is used by the injection molding machine. When a compound is injected into the cavity of No. 4, the component b is formed in the fitting unit 2 via the spacer 19. After the pressure-holding and cooling steps, they are integrated, as shown in FIG.
As shown in FIG. 5, the parts a and b having a shape capable of becoming the product 1 are taken out from the mold, and then the parts a and b are removed.
The metal product 1 is obtained by degreasing and sintering the same as above.

[0011]

FUNCTION The mold 4 is designed in consideration of the fact that the injection-molded body will later shrink due to sintering. As shown in FIG. 4, the compound is injected into the cavity portion where the component b can be molded in the portion surrounded by the component a, the movable-side insert 5, and the fixed-side insert 6, and the molded product is taken out after holding pressure and cooling. The body is assembled with a part a, a part b and a spacer 19 at the fitting part 2, and the part b is provided with a spool 7 and a runner 8 forming the part. At this time, the part a newly inserted from the inside of the part a previously inserted is pressed by the internal pressure of the molded body, and the contraction from the mold size after molding is small and there is no clearance. Do not slide together. After that, the integrated product taken out from the mold 4 is
As shown in FIG. 4, the part b is separated from the gate 11,
It is put into the degreasing process as it is. At this time, since the spacer 19 is made of plastic, which is the main component of the organic binder contained in the compound, it is decomposed by degreasing, completely disappears, and clearance is generated. After the sintering step, the metal powder sintered body shrinks in the sintering step due to agglomeration accompanying the growth of grain boundaries. Therefore, spacer 1
9 needs to be arranged in a portion that causes shrinkage in the direction of eliminating the clearance after shrinkage, and the parts a and b in the fitting part 2 are formed on the ceramic film 3 previously applied to the part a. Since the metal powder in the compound does not come into direct contact and the contact surface is completely separated, agglomeration does not occur in the fitting part 2, and clearance occurs in the fitting part 2 due to sintering shrinkage of the component b. With these clearances, it becomes possible to manufacture the product 1 which can slide without agglomeration of components even after sintering.

The use of the spacer is limited to the case where the fitting portion shrinks in the direction in which the clearance is lost due to the sintering shrinkage.

[0013]

【Example】

Example 1 (Structure) Example 1 will be described with reference to FIGS. 7 and 8 for manufacturing a product whose perspective view is shown in FIG. 5 and vertical plan view is shown in FIG. The two parts c and d rotate about the contact portion 9 and slide at the portions.

The component d is obtained by a metal powder sintering method and prepared in advance as a sintered body, and the surface portion thereof is coated with a ceramic fine powder of c-BN to form a ceramic coating 3. In this part d, a spacer 19 made of acrylic resin (main component of organic binder) is arranged as shown in FIG. 5, this is inserted into the movable side of the mold 4 by parting, and the mold 4 is closed. The cavity surrounded by the component d, the movable-side insert 5, and the fixed-side insert 6 forms a cavity for molding the component c. From the injection molding machine, in the cavity of the mold 4, fine metal powder SUS316L, organic binder wax,
A component c is formed by injecting a compound of polystyrene or acrylic resin, and the component c is fitted in the hole 10 of the component d to integrate the component c and the component d. After the pressure holding and cooling steps, the integrated parts c and d are taken out from the mold with the spool 7 and the runner 8 of the part c held. After that, the component c is separated from the gate 11, and degreasing and sintering are performed while being integrated to obtain a metal powder sintered component having a sliding portion.

(Function) The fine metal powder is SUS316L in the cavity where the component c can be molded by the portion surrounded by the component d having the acrylic resin spacer 19 arranged therein, the movable insert 5 and the fixed insert 6. The molded product obtained by injecting a compound composed of wax, polystyrene, and acrylic resin with an organic binder, holding pressure and cooling, has the part c and the part d and the spacer 19 assembled in the fitting part 2, Is attached with a spool 7 and a runner 8 which form this. At this time, the previously inserted part d is pressed from the inside of the hole 10 by the part c newly pressed by the internal pressure of the molded body via the spacer 19, and the shrinkage from the size of the hole 10 after molding is small, and the clearance is small. Since the product does not exist, the product is integrated and does not slide. After that, when the component c is separated from the gate 11 and put into the degreasing step, the organic binder in the compound forming the component c is decomposed by the degreasing, and the fine powder of SUS316L and a very small amount of the binder that cannot be completely decomposed. Only the ingredients remain.

On the other hand, since the spacer 19 is made of acrylic resin which is the main component of the organic binder, it is completely eliminated by degreasing and becomes a clearance. After this, the sintering process is further performed.
The parts c and the part d in the fitting part 2 are contracted due to aggregation due to the growth of grain boundaries, and the fitting part 12 is completely separated from the ceramic coating 3 applied to the part d in advance. The parts c and d do not agglomerate with each other at the joint part 2 and the product is made slidable due to the clearance generated as the part c shrinks. Since it has the undercut portion 13 that does not fall off, the product can slide without falling off or separating.

(Effect) By the above method, a product having sliding can be assembled in the mold 4 together with the injection molding, and as a result, the assembly can be automated.
Sliding products can be manufactured at low cost.

[Embodiment 2] (Structure) In this embodiment, the parts in Embodiment 1 are made of SUS.
The configuration is the same as that of the first embodiment except that a rolled material of 316L is obtained by machining, and thus the description thereof is omitted.

(Operation) Since the operation is the same as that of the first embodiment, its explanation is omitted.

(Effect) By these methods, even if one of the parts is a machined product, the product having sliding can be inserted into the mold and assembled with the other part by injection molding as in the first embodiment. Moreover, since the assembly is automated by this, the sliding product can be manufactured at a low cost as in the first embodiment.

[Third Embodiment] (Structure) A third embodiment will be described with reference to FIGS. 11 and 12 for manufacturing a product whose perspective view is shown in FIG. 9 and whose transverse side view is shown in FIG. FIG. 11 shows A in FIG.
-A 'as viewed from the direction of the arrow in the mold. The two parts e and f are such that the part e slides on the part f in the axial direction.

The component e is obtained by a metal powder sintering method and prepared in advance as a sintered body, and the surface is coated with a ceramic film 3 of alumina vapor deposition. This component e is inserted into the movable side of the mold 4 by placing a spacer 19 made of polystyrene (corresponding to the main component of the organic binder) by parting.
Is closed to form a cavity portion capable of molding the component f in a portion surrounded by the component e, the movable side insert 5, the spacer 19 and the fixed side insert 6.

From the injection molding machine, a compound f made of SUS316L of fine metal powder and wax, polystyrene, or acrylic resin as an organic binder is injected into the cavity of the mold 4 to form the part f, and the rail part 14 of the part e. The component f is fitted in the
Integrate through. After the pressure holding and cooling steps, the integrated parts e and f are taken out from the mold 4 together with the spool 7 and runner 8 of the part f. After that, the component f is separated from the gate 11 and degreased and sintered while being integrated.

(Function) A molded body taken out after injecting a compound into a cavity portion capable of molding the component f in a portion surrounded by the component e, the movable side insert 5 and the fixed side insert 6 and holding and cooling it. Is a fitting portion (rail portion 14 and rail groove 1
In 5), the part e and the part f are assembled via the spacer 19, and the part 7 is attached with the spool 7 and the runner 8 forming the part. At this time, the previously inserted component e
The part f newly molded from the inside of the rail groove 15 presses the rail groove 15 by the internal pressure of the molded body, and since the contraction from the rail groove 15 after molding is small and there is no clearance, the product does not slide.

After that, the part f is separated from the gate 11 and put into the degreasing process. At this time, since the spacer 19 is polystyrene, which is the main component of the organic binder, it is decomposed and completely disappeared in this degreasing, and a clearance is generated. After this, a sintering process is further performed, but the metal powder sintered body shrinks due to agglomeration accompanying the growth of grain boundaries in the sintering process, and the parts e and f in the rail portion 14 and the rail groove 15 are previously It is completely separated by the ceramic coating 3 applied to e, and further, due to the above clearance, the bite does not bite into the component e due to agglomeration during sintering, and further clearance is generated as the component f contracts. Makes the product slidable, and the pre-fabricated part f has an undercut and a stopper 16 so as not to drop into the pre-fabricated part e,
Since the product does not fall or separate, it becomes a product that can slide.

(Effect) According to the above method, a product having slide sliding can be assembled in the mold 4 together with injection molding, and since the assembly is automated by this, the sliding product can be manufactured at low cost. It becomes possible to manufacture.

[Embodiment 4] (Structure) FIGS. 15 and 16 are used to manufacture a product having a front view in FIG. 13 and a vertical front view in FIG.
Example 4 will be described based on FIG. The two parts g and h are jointed so that the part h is spherically supported by the part g and can freely rotate and slide.

The component g is obtained by a metal powder sintering method and prepared in advance as a sintered body, and a ceramic film 3 of SiC vapor deposition is applied to the surface portion. This part g can be inserted into the movable side of the mold 4 by parting, the mold 4 can be closed, and the part h can be molded at the portion surrounded by the part g, the movable side insert 5, and the fixed side insert 6. The cavity is formed.

From the injection molding machine, a compound consisting of SUS316L of fine metal powder and wax, polystyrene, and acrylic resin as an organic binder is injected into the cavity of the mold 4 to form a component h, and the joint 1 of the component g.
At 8, the component h is fitted and the component g and the component h are integrated. After the pressure holding and cooling steps, the integrated parts g and h are taken out from the mold 4 together with the spool 7 and runner 8 of the part h. After that, the component h is separated from the gate 11 and degreased and sintered while being integrated.

(Function) A molded body taken out after injecting a compound into a cavity capable of molding the component h in a portion surrounded by the component g, the movable side insert 5 and the fixed side insert 6 and holding and cooling it. Is a part g and a part h at the joint portion 18.
Is attached to the component h, and the spool 7 and the runner 8 forming the component h are attached to the component h. At this time, the component g newly inserted from the inside of the outer periphery of the joint portion 18 presses the outer peripheral portion of the joint portion 18 by the internal pressure of the molded body, and the contraction from the outer peripheral portion of the joint portion 18 after molding occurs. The product does not slide due to its small size and no clearance.

After this, the parts are separated from the gate 11,
In the degreasing process, the organic binder is decomposed and removed. After this, a sintering process is further performed, but in the sintering process, the metal powder sintered body shrinks due to aggregation due to the growth of grain boundaries, and the parts g and h in the joint part 18 are
Since it is completely separated by the ceramic coating 3 applied to the part g in advance, it does not bite into the part g due to the aggregation here, and a clearance is generated as the part h contracts. It becomes slidable, and since the pre-processed part g has an undercut that does not fall off, the product does not fall off or separate, so sliding is possible.

(Effect) According to the above method, a product that slides freely like a joint can be assembled in the mold 4 together with the injection molding, and since the assembly is automated by this, a low cost is achieved. Sliding products can be manufactured at low cost.

[Embodiment 5] (Structure) An example of a product having the same structure as that of Embodiment 4 in which the material of the constituent parts is changed will be described with reference to FIGS.

Component g was prepared in advance as a green part by injection molding of a compound composed of SUS316L of fine metal powder and wax, polystyrene, and acrylic resin as an organic binder. Alumina powder was applied to the surface portion and ceramic coating 3 was applied. Has been done. This part g is the mold 4
Is inserted into the movable side by parting, the mold 4 is closed, and the cavity surrounded by the part g, the movable side insert 5, and the fixed side insert 6 is formed so that the part h can be molded. Next, a compound is injected from the injection molding machine into the cavity so that the component h is molded. This compound has a metal powder content volume ratio lower than that of the compound in which the component g is molded.

When a compound is injected from the injection molding machine into the cavity of the mold 4, a part h is formed, and the part h is fitted at the joint part 18 of the part g to integrate the parts g and h. To do. After the pressure holding and cooling steps, the integrated parts g and h are taken out from the mold together with the spool 7 and runner 8 of the part h. After that, the component h is separated from the gate 11, and thereafter, degreasing and sintering are performed while being integrated.

(Function) The part h is surrounded by the green part of the part g, the compound, and the stationary insert 6.
The molded body obtained by injecting the compound into the cavity capable of molding, holding pressure, cooling, and taking out is assembled with the component g and the component h at the joint portion 18. The component h is formed with the spool 7 and the runner. 8 is attached. At this time, the component g newly inserted from the inside of the outer periphery of the joint portion 18 presses the outer peripheral portion of the joint portion 18 by the internal pressure of the molded body, and the contraction from the outer peripheral portion of the joint portion 18 after molding occurs. The product does not slide due to its small size and no clearance.

After this, the parts are separated from the gate 11,
In the degreasing process, the organic binder is decomposed and removed. After this, a sintering process is further performed, but in the sintering process, the metal powder sintered body shrinks due to aggregation due to the growth of grain boundaries, and the parts g and h in the joint part 18 are
Since it is completely separated by the ceramic coating 3 applied to the part g in advance, it does not bite into the part g due to the aggregation here, and a clearance is generated as the part h contracts. It becomes slidable, and since the pre-processed part g has an undercut that does not fall off, the product does not fall off or separate, so sliding is possible.

(Effects) By the above method, it becomes possible to assemble a product that slides freely like a joint in the mold 4 together with the injection molding as in the case of the fourth embodiment.
Further, as a result, the assembly is automated, so that the sliding product can be manufactured at a low cost.

The metal fine powder and the organic binder in the compounds described in Examples 1 to 5 are not limited to these, and the same effect can be obtained with other substances.

Further, a plastic spacer made of the main component of the organic binder contained in the compound is used to secure the clearance when the clearance is reduced due to shrinkage during sintering, but as shown in Example 5, It is possible to adopt a method of ensuring clearance by changing the compounding ratio of the fine metal powder in the compound used for molding each of the first and second parts to change the sintering shrinkage rate. In this case, since the plastic spacer is not required, the man-hour for arranging the spacer can be eliminated.

[0041]

As described above, according to the present invention, the metal parts having the sliding portions are simultaneously assembled while performing injection molding so that the metal parts can be slid afterwards in the mold, thereby performing the assembling process. By eliminating them, it becomes possible to manufacture low-cost metal sliding parts.

[Brief description of drawings]

FIG. 1 is a perspective view showing a product obtained by the present invention.

FIG. 2 is a vertical plan view showing a product obtained by the present invention.

FIG. 3 is a vertical sectional view of an injection molding machine conceptually showing the present invention.

FIG. 4 is a vertical plan view showing a product obtained by the present invention.

5 is a perspective view showing a product obtained in Example 1. FIG.

6 is a vertical plan view showing a product obtained in Example 1. FIG.

7 is a vertical sectional view showing the injection molding machine used in Example 1. FIG.

8 is a vertical plan view showing the product obtained in Example 1. FIG.

9 is a perspective view showing a product obtained in Example 3. FIG.

10 is a cross-sectional side view showing the product obtained in Example 3. FIG.

11 is a vertical cross-sectional view showing an injection molding machine used in Example 3. FIG.

12 is a cross-sectional side view showing the product obtained in Example 3. FIG.

13 is a front view showing a product obtained in Example 4. FIG.

FIG. 14 is a vertical sectional front view showing a product obtained in Example 4;

FIG. 15 is a vertical cross-sectional view showing an injection molding machine used in Example 4.

16 is a vertical cross-sectional front view showing the product obtained in Example 4. FIG.

17 is a vertical sectional front view showing the product obtained in Example 5. FIG.

[Explanation of symbols] a to h parts 1 product 2 fitting part 3 ceramics coating 4 mold 5 movable side insert 6 fixed side insert 19 spacer

Claims (3)

[Claims] 1. A step of injection-molding a compound obtained by kneading a metal powder and an organic binder into a desired shape, a step of degreasing the injection-molded body, and a step of sintering the obtained degreased body, In the method of manufacturing a metal powder sintered part having a sliding part, an instep part previously coated with a ceramics film is placed in the cavity part of the injection molding die, and the other part is injection-molded around the instep part by the compound. A method for producing a metal powder sintered part, comprising: 2. The upper part and the second part which are fitted by injection molding in the mold are taken out as a unit, and then degreased,
The method for producing a metal powder-sintered component according to claim 1, which comprises sintering. 3. The injection molding is performed in a state where a spacer made of a main component material of an organic binder contained in the compound is interposed in a sliding portion between the upper member and the second member. 2. The method for producing a metal powder sintered part according to 2.