JPH07126712A - Deburring method of injection molded goods of metallic powder goods - Google Patents

Abstract

PURPOSE:To easily execute the removal of burr with the small deformation of molded goods by removing burr from a half-drown body obtd. by degreasing only an organic binder contained in the surface layer part of a green body and thereafter executing degreasing. CONSTITUTION:In a temporary dewaxing stage, e.g. in the green body 2 of metal powder injection molded goods constituted of metal powder and 30wt.% organic binder and in which a bore part 2b is formed, 3 to 5% of the binder is degreased under heating. Thus, a half-brown body 2 in which the contents of the binder in the surface layer part 2d are reduced while the contents of the binder in the product part 2a are maintained is obtd. Next, this brown body 2 is inserted into a rotary barrel together with adrasive stones, the half- brown body 2 is bombarded with the abrasive stones, and the half-brown body burr 2c are removed away from the half-brown body product part 2c.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to deburring of sintered parts obtained by metal powder injection molding.

[0002]

2. Description of the Related Art Conventionally, as a method for easily removing burrs from sintered parts by powder metallurgy, for example, Japanese Patent Publication No. 5-2196.
Japanese Patent Publication No. 3 discloses an invention in which a green compact obtained by compression molding of metal powder is subjected to shot blasting before sintering. Generally, the powder metallurgy green compact has a smaller shape-retaining force than that of the completely-sintered part. Therefore, according to the invention, the burr can be removed more easily than the completely-sintered part.

[0003]

[MEANS FOR SOLVING THE PROBLEMS] The metal powder injection molding method comprises an injection step of injection molding a kneaded body of metal powder and an organic binder into a mold to obtain a green body, and removing the organic binder from the green body. And a degreasing step of obtaining a brown body, and a sintering step of sintering the brown body to obtain a sintered component. When removing burrs from such a metal powder injection-molded product, burrs can be easily removed by removing the burrs in the state of the brown body where the shape retention force of the burrs is minimized.

However, the permissible amount of the organic binder contained in the brown body at the time of sintering is extremely small (generally about 1 wt% with respect to the brown body), and the agglomeration amount of the metal powder contained in the brown body is small. Since it is smaller than the green compact in powder metallurgy, the brown body generally has a smaller shape retention force than the green compact. Therefore, when the method disclosed in Japanese Patent Publication No. 5-21963 is used for a metal powder injection-molded article and the brown body after degreasing is shot-blasted, the brown body is deformed.

Therefore, the present invention was developed in view of the above-mentioned drawbacks of the prior art, and an object thereof is to provide a method for removing burrs from a metal powder injection molded product which is easy and has little deformation of the molded product. .

[0006]

Means for Solving the Problems The present invention provides a method for removing burrs of a metal powder injection-molded article, which comprises a temporary degreasing step of degreasing only an organic binder contained in the surface layer of a green body to obtain a semi-blown body. It is a method comprising a deburring step of removing burrs from the semi-brown body, and a degreasing step of degreasing the organic binder contained in the semi-brown body from which the burrs have been removed to obtain a final brown body.

[0007]

In the present invention, by degreasing only the organic binder contained in the surface layer of the green body in the temporary degreasing step, the shape retention of the surface layer including burrs is maintained while maintaining the internal shape retention. A semi-brown body with reduced strength is obtained. Next, in the deburring process of the semi-brown body,
The burr on the surface layer portion having a reduced shape retention force is easily removed while the deformation is suppressed by the shape retention force inside. Furthermore, the desired final brown body is obtained by degreasing the organic binder remaining in the semi-brown body from which burrs have been removed in the present degreasing step to a desired content.

[0008]

Embodiment 1 FIGS. 1 to 5 show the present embodiment, FIGS. 1a and 1b are a plan view and a vertical sectional view of a green body, FIG. 2 is a vertical sectional view of a semi-brown body, and FIG. 3 is a schematic explanatory view. Figure 4
FIG. 4 is a vertical sectional view of the final brown body.

The green body 1 is made of SUS316L metal powder having an average particle size of 10 μm and 30 w with respect to the metal powder.
It is obtained by injection-molding a compound (not shown) in which a compound kneaded with an organic binder made of t% nylon resin is kneaded. Also, an inner diameter portion 1b provided in the green body product portion 1a of the green body 1
The green body burr 1c which is generated by the compound flowing into the gap of the mold is formed on the.

First, the green body 1 is heated and degreased with 3 to 5 wt% of the nylon resin in an ordinary heating and degreasing furnace (not shown) to obtain a semi-brown body 2 (temporary degreasing step-see FIG. 2). . Next, the semi-brown body burr 2c is inserted from the semi-brown body burr 2c into the rotary barrel 4, and the semi-brown body burr 2c is separated from the semi-brown body product part 2a. (Deburring step—see FIG. 3).

Thereafter, the semi-brown body 2 is inserted into a heating degreasing furnace (not shown), and the nylon resin is heated and degreased until the content of the nylon resin becomes 0.5 wt% with respect to the final brown body 5. A brown body 5 is obtained (this degreasing step—see FIG. 4). Further, the final brown body 5 is sintered in a normal sintering furnace (not shown) to obtain a completed sintering component (not shown).

The operation of this embodiment will be described below. In the temporary degreasing step, heating is performed in the order from the green body surface layer portion 1d of the green body 1 to the inner green body product portion 1a, and the nylon resin heated to the thermal decomposition temperature is gasified to be heated from the green body surface layer portion 1d. Since it scatters, the heat degreasing causes the green body surface layer 1d.
To the green body product section 1a.

Therefore, in the semi-brown body 2, the content of the nylon resin in the semi-brown body surface portion 2d decreases while the content of the nylon resin in the semi-brown body product portion 2a is maintained. That is, the semi-brown body product section 2
Semi-brown body burr 2 with the shape retention of a maintained.
Only the shape retention force of the semi-brown body surface layer portion 2d including c is reduced.

Next, in the deburring step, the polishing stone 3 collides with the semi-brown body burr 2c whose shape-retaining force is lowered, and the impact force at that time causes the semi-brown body burr 2 to have a shape.
c separates from the semi-brown body product part 2a. After this, in the degreasing step, the nylon resin in the semi-brown body product portion 2a of the semi-brown body 2 is heated and degreased until the desired content is obtained, and the final brown body 5 is obtained.

According to this embodiment, the semi-brown body burr 2c whose shape-retaining force is lowered is removed while the shape-retaining force of the semi-brown body product part 2a of the semi-brown body 2 is maintained. The semi-brown body burr 2c can be removed from the semi-brown body product 2a without deforming the body product 2a.

[0016]

Second Embodiment FIG. 5 is a schematic explanatory view showing the present embodiment.
The present embodiment is different in the burr removal process in the first embodiment, and the other construction is composed of the same constituent parts, and the same constituent parts are designated by the same reference numerals and the description thereof will be omitted.

With the semi-brown body 2 inserted between the upper and lower sides of the nozzle 6 of the shot blasting device (not shown), the abrasive powder 7 is sprayed from the upper and lower sides of the nozzle 6 onto the semi-brown body surface layer portion 2d and the semi-brown body burr 2c. . At this time, the polishing powder 7 is evenly distributed over the entire surface layer 2d of the semi-brown body.
So that they collide with each other, a half brown body 2 is placed between the upper and lower parts of the nozzle 6.
Repeatedly move, invert, and change patterns. The movement and reversal of the semi-brown body 2 may be performed by an automatic machine such as a robot (not shown) or a rotating barrel (not shown).

The operation of this embodiment will be described below. Half brown body surface layer 2d and half brown body burr 2c
The semi-brown body burr 2c is detached from the semi-brown body product portion 1a by the impact force when the polishing powder 7 collides with.
The other operations are the same as those in the first embodiment, and the description of the operation is omitted.

According to this embodiment, the following effects are obtained in addition to the effects of the first embodiment. Since it is easier to adjust the impact force of the polishing powder 7 ejected from the nozzle 6 than the impact force of the polishing stone 3 in the first embodiment, the semi-brown body product portion 2
The risk of damaging a is smaller than that in the first embodiment.

[0020]

Third Embodiment FIG. 6 is a schematic explanatory view showing the present embodiment.
The present embodiment is different from the first embodiment in the temporary degreasing step, and the other components are the same, and the same components are designated by the same reference numerals and the description thereof is omitted.

In the temporary degreasing process, the green body 1 is
The nylon resin contained in the green body 1 is dissolved by inserting it into the pallet 9 into which the aOH aqueous solution 8 has been injected and immersing the green body 1 in the NaOH aqueous solution 8. After dissolving and degreasing 3 to 5 wt% of the nylon resin, the green body 1 is taken out from the pallet 9,
Get a half brown body 2.

The operation of this embodiment will be described below. By immersing the green body 1 in the aqueous NaOH solution 8 and allowing the NaOH to permeate into the green body 1 while dissolving the nylon resin, the nylon resin is dissolved and degreased from the green body surface layer portion 1d to the green body product portion. The steps are sequentially performed toward 1a.

Therefore, in the semi-brown body 2, the content of nylon resin in the semi-brown body product portion 2a is maintained, and the content rate of nylon resin in the semi-brown body surface portion 2d decreases. That is, the semi-brown body product part 2a
Half brown body burr 2c with the shape retention of
Only the shape-retaining power of the semi-brown body surface layer portion 2d including is reduced. The other operations are the same as those in the first embodiment, and the description of the operation is omitted.

According to this embodiment, the following effects are obtained in addition to the effects of the first embodiment. The dissolution degreasing with the NaOH aqueous solution 8 degreases the nylon resin of the green body surface layer portion 1d earlier than the heating degreasing in Example 1, and thus the processing time can be shorter than that in Example 1.

[0025]

As described above, according to the method for removing burrs of metal powder injection-molded articles according to the present invention, in the step of removing burrs of a semi-brown body, the deformation is suppressed by the internal shape retention force. Since the burrs on the surface layer portion having the reduced shape retention are easily removed, the burrs of the metal powder injection-molded product can be easily removed without deforming the molded product.

[Brief description of drawings]

1A and 1B show a first embodiment, in which a is a plan view and b is a longitudinal sectional view.

FIG. 2 is a vertical sectional view showing the first embodiment.

FIG. 3 is a schematic explanatory diagram illustrating a first embodiment.

FIG. 4 is a vertical sectional view showing the first embodiment.

FIG. 5 is a schematic explanatory view showing a second embodiment.

FIG. 6 is a schematic explanatory view showing a third embodiment.

[Explanation of symbols]

 1 Green body 2 Half brown body 3 Polishing stone 4 Rotating barrel 5 Final brown body

Claims (1)

[Claims] 1. A method for removing burrs from a metal powder injection-molded article, comprising a temporary degreasing step of degreasing only an organic binder contained in the surface layer of a green body to obtain a semi-brown body, and removing the burrs from the semi-brown body. And a degreasing step of degreasing the organic binder contained in the semi-brown body from which the burr has been removed to obtain a final brown body. .