JPH0521963B2 - - Google Patents

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to improvements in methods for manufacturing sintered products.

(Prior Art) A method for manufacturing a sintered product has been known as shown in Japanese Patent Application Laid-Open No. 128505/1982, but a method for manufacturing a sintered product, for example, a turbine hub for an automobile as shown in FIG. 1 is manufactured by molding powder (iron powder) into a predetermined shape using a powder compacting machine, but during molding, molding burrs 2 are created at each corner corresponding to the joint of the mold.
(see FIG. 1b) occurs.

In order to remove such molding burrs, conventionally, after sintering the green compact (turbine hub) 1,
Barrel processing and shot blasting were used, but since the material was sintered, it was hard, requiring a large amount of processing power, and it was difficult to remove molding burrs.

In addition, there are methods for removing burrs before sintering, such as those that spray an elastic body such as rubber, and those that allow the shots to fall naturally. The problem was that it had to be removed, complicating the process.

(Objective of the Invention) The present invention is aimed at manufacturing a sintered product that can easily remove molding burrs with small processing power, and at the same time facilitate control of sintering atmosphere gas and promote surface hardening of the sintered product. The purpose is to provide a method.

(Structure of the Invention) For this reason, the present invention provides a method for viewing a compacted powder body from an oblique direction with respect to the forming burrs of the compact, and at least the entire surface of the green compact on which the forming burrs are formed. While molding burrs are removed from the green compact by spraying copper-based metal powder over a period of time, the green compact is sintered while the copper-based metal powder remains attached to the surface and pores of the green compact. In other words, the adhered copper-based metal powder is infiltrated into the surface layer of the green compact.

(Effects of the Invention) According to the present invention, since copper-based metal powder is injected onto a green compact with low hardness before sintering, molding burrs can be easily removed even with a light injection force, and pressure It does not damage the powder.

In addition, since the green compact is sintered with this copper-based metal powder attached to it and infiltrated into the surface layer of the green compact, the surface layer of the green compact has no chance of reacting with carbon. As a result, the carbon content in the sintering atmosphere gas can be roughly controlled.

Furthermore, since the copper-based metal powder is infiltrated into the surface layer of the green compact, surface hardening of the sintered product is also promoted.

(Example) As shown in FIG. 2, the deburring device 3 for the compacted powder 1 is arranged between the compacting machine 4 on the left side of the figure and the pool space 5 on the right side of the figure. Molding machine 4
The green compact 1 that is punched out in a constant cycle is carried onto the mesh belt 7 by the carry-in chute 6, deburring is automatically performed while being conveyed by the mesh belt 7, and the green compact 1 after deburring is transferred to the carry-out chute. 8, it will be carried out to pool space 5.

The deburring device 3 is equipped with a dust cover 9 that covers the outer periphery of the mesh belt 7 and around the exit and inlet ports 7a and 7b, and high pressure air A is supplied above and below the mesh belt 7 inside the dust cover 9. Nozzles 10 and 11 are provided for spraying copper-based metal powder (hereinafter referred to as Cu powder) M toward the powder compact 1 on the mesh belt 7.

These nozzles 10 and 11 are arranged obliquely to the molding burrs of the compact 1. When the Cu powder M is injected from the nozzles 10 and 11 onto the green compact 1 on the mesh belt 7, as it is transported by the mesh belt 7, at least the entire surface of the green compact 1 on which the molding burr is formed ,
That is, in the case of this embodiment, the Cu powder M is injected over the entire upper and lower surfaces of the powder compact 1.

A storage hopper 12 for Cu powder M is connected to the lower part of the dustproof cover 9.
Cu powder supply pipe 10a of each nozzle 10, 11 from
Cu powder M is supplied to 11a. Further, high-pressure air A is supplied from a compressor or the like (not shown) to air supply pipes 10b and 11b of each nozzle 10 and 11.

The above-mentioned Cu powder M is preferably copper powder from the viewpoint of cost, but nickel powder, cobalt powder, etc. can also be used.

Regarding specific injection conditions such as the particle size and injection pressure of the Cu powder M, for example, the material and particle size of the powder compact 1, the hardness before sintering, the general size of molding burrs, or the body 1 and nozzle 10,
It is set as appropriate depending on various conditions such as the distance from 11. For example, it is generally desirable that the particle size of the Cu powder M be slightly larger than the particle size of the powder used to form the green compact 1. That is, when forming the green compact 1 as described above, powder with a particle size of about 0.15 mm or less is usually used, but for such a compact 1, the powder of the compact itself is It is preferable to inject Cu powder having a particle size larger than that of the body and, for example, about 0.3 mm or less. In such a case, the injection pressure may be, for example, the pressure of compressed air commonly used in factories, that is, 5 to 6
A pressure of about Kg/cm ² is appropriate. Furthermore, these Cu
Specific settings of injection conditions such as powder particle size and injection pressure can be easily made by those skilled in the art when implementing the present invention.

However, in the deburring device 3, the third
As shown in the figure, when Cu powder is injected from the nozzles 10 and 11 while the green compact 1 is conveyed by the mesh belt 7, the green compact 1 has a low hardness before sintering, so
As shown in Figures a and 4b, the molding burr 2 falls off or shrinks with a light jetting force and is removed. Further, since the jetting force of the nozzles 10 and 11 is light, the green compact 1 is not scratched by the collision of the Cu powder M.

The injection of the Cu powder M causes the Cu powder to adhere to the surface and pores of the green compact 1, but this is left as is.

On the other hand, as shown in FIG. , Honyaki zone 19,
A slow cooling zone 20 and a cooling zone 21 are provided, and the temperatures in each zone 17 to 21 are as shown in FIG. 5b in comparison with FIG. 5a.

In the sintering device 15, the green compact 1 with the Cu powder M still attached is transferred to the mesh belt 16.
When the sintering process is performed while conveying the powder, as shown in FIGS. 6a and 6b, during the sintering process, the Cu powder M adhering to the surface of the powder compact 1 is removed from the surface of the powder compact 1. The layer is infiltrated.

Then, the surface layer of the powder compact 1 will be coated with Cu powder M, and since Cu powder M is difficult to react with carbon, the amount of Cu powder M is approximately equal to the amount of carbon (for example, 0.8%) in the powder compact 1. This makes it possible to roughly control the amount of carbon in the sintering gas atmosphere (for example, around 0.6% to 1.0%).

Furthermore, since the Cu powder M infiltrates the surface of the green compact 1, surface hardening of the sintered product is also promoted.

[Brief explanation of drawings]

Figure 1a is a cross-sectional view of the green compact before deburring;
FIG. 2 is a side view of the deburring device according to the present invention; FIG. Fourth
Figure a is a sectional view of the green compact after deburring, Figure 4 b is an enlarged sectional view of part a of Figure 4 a, Figure 5 a is a side view of the sintering device, and Figure 5 b is Figure 5. FIG. 6a is a sectional view of the green compact after sintering, and FIG. 6b is an enlarged sectional view of section a in FIG. 6a. 1... Green compact (turbine hub), 2... Molding burr,
3... Deburring device, 10, 11... Nozzle, 15...
Sintering equipment, M...Cu powder (copper metal powder), A...High pressure air.

Claims (1)

[Claims] 1. A copper-based metal is applied to a green compact formed into a predetermined shape from a direction oblique to the forming burrs of the green compact and over at least the entire surface of the compact where the forming burrs are formed. The powder is injected to remove molding burrs from the green compact, and the green compact is sintered while the copper-based metal powder remains attached to the surface and pores of the green compact. A method for producing a sintered product, characterized by infiltrating the surface layer of a green compact with adhered copper-based metal powder.