JPS629293Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a technology for manufacturing multi-layer sintered mechanical parts partially made of different materials.

FIGS. 1 and 2 are drawings showing a Rocker arm 1 of an internal combustion engine as an example of such a part.
This component performs a see-saw motion using a shaft 3 passing through the hole 1c as a fulcrum as the cam 2 that slides in contact with the left end pad 1b rotates, and opens and closes the valve 4 at the right end.

Therefore, the pad 1b needs to be made of a high-quality material that has its own wear resistance and does not wear out the cam of the mating member, but the main body 1a needs to be made of a relatively low-grade material with appropriate toughness. Can be done.

Now, when molding such a multi-layer compact using the powder metallurgy method, there is a method in which the powder forming each layer is filled into a mold and compressed so that the interface between the two layers is horizontal. There is a method of filling vertically, but in the case of the part shown in Figure 1, the shaft hole 1c
It is customary to perform molding in the direction shown in the figure, with the shaft hole perpendicular, in order to perform molding at the same time, that is, to use the latter filling method.

Figure 3 shows a typical conventional method, in which the lower punch 6 is divided into two parts 6a and 6b, and a partition plate 7 is interposed between them. These three members, and in the case of a die floating type, the die 5, the lower punch 6b, and the partition plate 7 are configured to be able to move up and down independently of each other.

To briefly explain the operation of this mold, (a) to (b) first fill the first powder into the cavity formed by the die 5, lower punch 6a and partition plate 7, and then (c)
~(d) The lower punch 6b is lowered to the predetermined filling depth to fill the partition plate 7 with the second powder, and (e) ~
(f) The partition plate 7 is pulled down to the same level as the lower punches 6a and 6b, held together, and the powder is compacted between them and the upper punch 8 to obtain the desired two-layer molded product.

However, the problem with this method is that it requires a special press with a triple operating mechanism on the lower punch side, but the thickness of the partition plate is not large enough to withstand the sliding between the two punches and the pressure during forming. Although it requires a certain degree of thickness in order to have rigidity, it has the disadvantage that the thickness causes an error in the amount of powder filled.

This idea was made in view of the above circumstances,
In correspondence with the divided lower punches 6a and 6b, the upper punch 8 is also divided into two parts, 8a and 8b, and the upper and lower punches are interlocked in a predetermined step during the powder filling process, thereby eliminating the need for a partition plate. west,
This eliminates the problems of conventional devices.

Hereinafter, for convenience of explanation, one embodiment of this invention will be described using a simplified multilayer molded body as shown in FIG. 4 as an example.

Figure 5 shows the operation of this device, that is, a series of steps from powder filling to molding, where the lower punches are 6a, 6b.
It is the same as the conventional punch in that it is divided into two parts, but there is no partition plate 7, and instead, the upper punch is divided into parts 8a, 8b and the lower punch, respectively. In the figure, first (a) only the lower punch 6a is positioned at a predetermined filling depth and a cavity for the first layer 1a is formed by the side surfaces of the die 5, the lower punch 6a and the same 6b, and (b) then this Fill the cavity with powder for layer 1a.

(C) Next, the upper punch 8a is lowered, and at the same time as its tip comes into contact with the powder, the lower punch 6a is also lowered at the same speed to move the powder in the cavity downward without compressing it. As means for this synchronous operation, for example, electric control that detects the position of the upper punch 8a with a limit switch and operates the lower ram, or interposing a spacer between the upper ram and the lower ram as in Japanese Patent Publication No. 53-11701. Mechanical means and other known means can be used as appropriate. Note that the powder moves downward until the tip of the upper punch 8a is below the initial position of the lower punch 6a (more precisely, the predetermined position of the lower punch 6b when filling the powder for the second layer 1b). It is necessary to do it.

(d) Lower the lower punch 6b to a predetermined filling depth to form a cavity for the second layer 1b on the sides of the die 5, lower punch 6b and upper punch 8a, and (e) fill the cavity with powder for the layer 1b. Fill it.

(f) Next, the upper punch 8b is lowered, and at the same time as its tip contacts the powder, the lower punch 6b is also lowered at the same speed, so that the powder in the cavity is not compressed and has the same height as the powder for layer 1a. By moving the powder up to the left, the multi-layer filling of the powder is completed.

(G) ~ (H) At this point, the synchronized operation of the corresponding upper and lower punches is canceled, and the adjacent punches 6a, 6b and 8a, 8b are operated as a unit to compact the powder and discharge the compact, Complete the entire process.

FIG. 6 is a schematic diagram of this device (mold) attached to an ordinary powder press equipped with a double-acting lower ram. Lower punches 6a and 6b are attached to each of the double-acting lower rams.
The upper punch 8b is attached to the upper ram, and the upper punch 8a is attached to a pneumatic cylinder within the upper ram. Note that the drive sources for the upper and lower rams, cylinders, etc., and the electric circuits that control them are well known and are therefore not shown.

As detailed above, the biggest advantage of this invention is that the partition plate 7 can be eliminated, and as a result, the mechanism on the lower punch side, including the press, is simplified and the quality of the molded product is improved. do. However, on the other hand, there are disadvantages such as the die thickness being more than double that of the conventional method and the upper and lower punches being correspondingly longer, but the above-mentioned advantages are evaluated to be greater than these.

[Brief explanation of the drawing]

Figures 1 and 2 are drawings showing the appearance and operating state of a rocker arm for an internal combustion engine as an example of a multi-layer molded body, Figure 3 is a drawing explaining a conventional device for molding a multi-layer molded body, and Figure 4 is a diagram illustrating a conventional device for forming a multi-layer molded body. FIGS. 5 and 6, which are simplified schematic diagrams of a multilayer molded body, are drawings for explaining the operation and main structure of the device according to this invention. 1a...Main body (first layer) of multilayer molded body, 1b
... Pad (second layer), 5 ... Die, 7 ... Partition plate, 6a ... Corresponding to layer 1a (divided)
Lower punch, 6b... (divided) lower punch corresponding to layer 1b, 8a... (divided) upper punch corresponding to layer 1a, 8b... (divided) upper punch corresponding to layer 1b .

Claims (1)

[Scope of utility model registration request] In a device that is equipped with a die, an upper punch, and a lower punch, and compresses and molds the powder filled in the die between the upper and lower punches, the upper punch and lower punch are divided by the same vertical cutting plane and can be moved up and down individually. 1. An apparatus for forming a multi-layer compact in powder metallurgy, characterized in that it is equipped with means for interlocking and lowering corresponding upper and lower punches in a powder moving step during a powder filling step.