JP3574191B2 - Method for producing molded body for multilayer sintered parts - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to a method for manufacturing a molded product for a multilayer sintered part, in which a plurality of inner and outer layers of a powder material are integrally formed in a die by a lower punch and an upper punch.
[0002]
[Prior art]
Conventionally, as a method of manufacturing a molded body for a sintered component having two layers inside and outside, according to Japanese Patent Publication No. 55-42121, a lower punch is divided into two divided punches on the inside and outside and a partition punch in the middle of the two punches. After the partitioning punch is raised, inner and outer spaces separated by the punch are formed in the die, and each space is filled with the powder material for the inner layer and the powder material for the outer layer, respectively. And pressing an upper punch into a die to press-mold two inner and outer layers of powder material integrally.
[0003]
[Problems to be solved by the invention]
In the above conventional example, the powder material for the inner layer and the powder material for the outer layer can be separately filled in the die, but when the partitioning punch is lowered, the powder material of both layers is irregular at the boundary between the inner and outer layers. Since the powder material is crushed and mixed, the mixing state of the powder material at the boundary portion is not constant, and the bonding strength between the inner layer and the outer layer of the sintered part varies, so that the quality is not stable.
In view of the above points, an object of the present invention is to provide a molding method capable of uniformly controlling the mixing state of powder at each boundary between a plurality of inner and outer layers.
[0004]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a method in which the lower punch and the upper punch are each constituted by a plurality of divided punches inside and outside, and the powder material of each layer inside and outside is filled between the divided punches corresponding to each layer of the lower punch and the upper punch After individually pressing, the divided punch of the lower punch and the divided punch of the upper punch are moved so that the powder material of each layer fits each other, and then the powder material of all the layers is pressed integrally. In the method for producing a molded body for a multilayer sintered part to be molded, by adjusting the degree of compaction when filling between the divided punches and individually pressing, the mixed state of the powder material at the boundary between the inner and outer surface layers is adjusted. It is characterized by management .
[0005]
[Action]
Since the powder materials of the inner and outer layers are individually pressed and then fitted to each other, the powder material of each layer has shape retention at the time of fitting, and the powder material of each layer is irregular at the boundary between adjacent layers. It doesn't collapse and mix.
By adjusting the degree of the powder compact in each of the divided punches, the mixed state of the powder material at the boundary between the inner and outer layers can be controlled to a predetermined state.
[0006]
【Example】
FIG. 1 shows a molding apparatus for producing a molded body W for a sintered component having two layers inside and outside. The molding apparatus includes a die 1, a lower punch 2, and an upper punch 3.
The lower punch 2 is composed of an inner / outer double split punch composed of a lower inner punch 20 and a lower outer punch 21 which can move up and down independently of each other. Similarly, the upper punch 3 can also move up and down independently of each other. The inner and outer double punches each include an upper inner punch 30 and an upper outer punch 31.
The outer diameter of the lower inner punch 20 is slightly larger than the inner diameter of the upper outer punch 31.
[0007]
In manufacturing the molded body W, first, the lower outer punch 21 is lowered as shown in FIG. 2A, and the space around the lower inner punch 20 closed by the punch 21 is filled with the outer layer powder material Wa. Then, as shown in FIG. 2B, the upper outer punch 31 is lowered, and the powder material Wa is pressed between the lower outer punch 21 and the upper outer punch 31. At this time, the lower inner punch 20 is pushed down by the upper outer punch 31. Next, as shown in FIG. 2 (c), a gap in the upper outer punch 31 closed by the lower inner punch 20 is filled with an inner layer powder material Wb different from the outer layer powder material Wa. As shown in ()), the upper inner punch 30 is lowered, and the powder material Wb is pressed between the lower inner punch 20 and the upper inner punch 30. The inner layer powder material Wb is supplied through a supply port (not shown) formed on the peripheral surface of the upper outer punch 31.
[0008]
Next, as shown in FIG. 2 (e), the lower inner punch 20 and the upper inner punch 30 are lowered to fit the inner layer powder material Wb into the outer layer powder material Wa. Here, since the powder materials Wa and Wb are pressurized in advance and have shape-retaining properties, it is unlikely that the powder materials Wa and Wb are crushed and mixed irregularly at the boundary between the inner and outer layers during fitting. Further, since the outer diameter of the lower inner punch 20 is made larger than the inner diameter of the upper outer punch 31, the inner diameter of the outer layer powder material Wa that matches the outer diameter of the lower inner punch 20 and the inner diameter of the upper outer punch 31 are reduced. There is no gap between the inner layer powder material Wb and the outer peripheral surface of the matching inner layer powder material Wb, so that the inner and outer layers do not rub against each other so that the powder materials Wa and Wb are mixed.
[0009]
Next, as shown in FIG. 2 (f), both the upper inner punch 20 and the upper outer punch 21 are lowered to a predetermined depth, and the inner and outer layers of the powder materials Wa and Wb are integrally pressed and molded. At this time, the powder materials Wa and Wb are mixed at the boundary between the inner and outer layers. In the present embodiment, the outer layer powder material Wa is preliminarily compacted to such an extent that the shape retention can be obtained in the pressing step of FIG. 2B, while the inner layer powder material Wb is of FIG. 2D. In the pressing step, the powder is strongly compacted to a thickness close to the final product. In the final pressing step of FIG. 2 (f), the powder material Wa for the outer layer is mainly powdered, and the powder material Wa for the outer layer is used for the inner layer. Although the powder material Wb was made to bite, contrary to the above, the inner layer powder material Wb was temporarily compacted, and the inner layer powder material Wb was bitten into the outer layer powder material Wa in the final pressing step, or The powder materials Wa and Wb of both the inner and outer layers may be temporarily compacted, and the powder materials Wa and Wb of both layers may be mutually bitten in the final pressing step. Of the powder material Wa, Wb at the boundary between the inner and outer layers by adjusting the degree of compaction in the pressing step of The engaged state can be properly managed.
[0010]
After completion of the final pressurizing step, the upper inner punch 30 and the upper outer punch 31 are raised to the upper retreat position, and then the lower inner punch 20 and the lower outer punch 21 are lifted, and the compact W is die-mounted as shown in FIG. 1 and the molded body W is put into a furnace to obtain a sintered part having two layers inside and outside.
[0011]
Although the production of the molded body W having two layers inside and outside has been described above, the present invention can be similarly applied to the production of a molded body having three or more layers inside and outside. For example, in the case of manufacturing a three-layer inner / outer molded body, the lower punch and the upper punch are each composed of an inner / middle / outer triple inner / outer split punch, and the outer layer powder is interposed between the lower outer punch and the upper outer punch. Filling and pressing the material, filling and pressing the powder material for the intermediate layer between the lower middle punch and the upper middle punch, and powder material for the inner layer between the lower inner punch and the upper inner punch And pressurizing are sequentially performed individually, then the inner and outer three layers of the powder material are fitted with each other, and finally the three layers of the powder material are integrally press-molded.
[0012]
【The invention's effect】
As apparent from the above description, according to the present invention, the mixed state of the powder material at the boundary between the layers can be controlled to a predetermined state, the bonding strength between the layers of the sintered component is stabilized, and the quality is improved. .
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an example of a molding apparatus used for carrying out the present invention. FIGS. 2A to 2F are process diagrams showing an example of a molding procedure according to the present invention.
W Molded body Wa, Wb Powder material of each layer 1 Die 2 Lower punch 20, 21 Split punch 3 Upper punch 30, 31 Split punch

Claims (1)

Each of the lower punch and the upper punch is composed of a plurality of inner and outer divided punches, and the powder material of each inner and outer layer is filled between the divided punches corresponding to the respective layers of the lower punch and the upper punch, and individually pressurized. Manufacturing of a molded body for a multilayer sintered part in which each of the divided punches and the upper punch is moved so that the powder materials of the respective layers are fitted to each other, and then the powder materials of all the layers are integrally pressed. In the method, the mixing state of the powder material at the boundary between the inner and outer surface layers is controlled by adjusting the degree of compaction when the powder is filled between the split punches and individually pressed, and the multilayer sintering is characterized in that Manufacturing method of molded parts.

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