JPH0491894A - Method for compacting powder - Google Patents

Abstract

PURPOSE:To improve the quality by controlling displacing rate of an upper punch after punching process corresponding to spring back rate in compacting of powder having much spring back rate. CONSTITUTION:At the time of compacting the powder 4 having much spring back rate by using the upper punch 1, die 2 and lower punch 3 in the powder compacting, after completing pressurized holding with the upper punch 1, the upper punch 1 is lifted while controlling the displacing rate corresponding to the spring back rate, after the punching process to remove pressure strain. By this method, the development of crack, detachment, etc., of the green compact can be prevented and the quality of powder compacted product can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for molding powder with a large amount of springback, and more particularly, to a method for forming powder that does not cause cranking, flaking, bulges, etc. of the molded product. It is something.

[Conventional technology]

In a method of molding powder using an upper punch, a die, and a lower punch, conventionally, after the upper punch has completed pressurization and holding, a pressure release step is performed to complete the molding.

In this molding method, when powder with a large amount of springback is molded, the strain caused by pressure is rapidly released after pressure is released, resulting in cracks, peeling, bulges, etc., occurring in the molded product.

[Problems to be Solved by the Invention] However, with the above-mentioned molding method, if the molded product is sintered and manufactured into a product with cracks, peeling, bulges, etc. occurring,
There was a problem in that the desired product could not be produced in terms of shape, appearance, and material properties.

This invention aims to solve the above problems.

[Means to solve the problem]

The powder compacting method of the present invention is a method of compacting powder with a large amount of springback using a punch, a die, and a lower punch. This is to control the amount of displacement corresponding to the amount and raise the upper punch to prevent cranking, peeling, spalling, etc. of the molded product.

[Effect]

In the non-forming method of this invention, pressure is released from 3 to 1 of each loaf as shown in Fig. 1, but 1. Green compact 4
．． 3 still has strain caused by the internal pressure, so the same 1] As in G"l, the spring that is generated in proportion to the internal residual pressure has a displacement lid that corresponds to the amount of deflection. It is necessary to move the upper punch 1 upward 4 and release it by controlling the internal pressure L7.

As shown in Figure 1, pull out die 2 as shown in Figures 1 and 0,
Subsequently, as shown in FIG. 0), upper 7 punches If;

It does not cause any problems such as blurring.

〔Example〕

Hereinafter, an embodiment of the method according to the invention will be described in detail with reference to the sequence of operation of the forming device.

The first time (4) represents a state in which the powder 4 is filled into the die 2 and the T-bump 3. In the same figure (in Bl, punch 1 descends as shown by arrow a and plunges into die 2. In the same figure), punch 1, die 2, and punch 1 descend at the same time, and downward pressure as indicated by arrow F is applied to powder 4. This becomes powder 4a.

Next, at [α] in the same figure, Da-I 2 stops and 7, Sara! mlml
- The punch descends, arrow F is applied, and when the setting pressure is reached, the two-bunner l comes to a resting stop while maintaining this set pressure, and the molding of the compact 4a is completed.

Next, in Fig. 11:'), with the pressure of the punch 1 released and in the state indicated by the arrows in the previous figure A, the B-force F is applied to the opening C1. There is. , when the green compact 4a
Due to the springback of the punch 1, it is slightly pushed back, which is the tip of the pressure relief.

Next] - is the characteristic feature of the present invention.
As shown in Figure [F], a slight negative force is exerted on the punch 1, that is, the arrow F moves, and the green compact 4a becomes a compacted compact 4b from which strain has been removed. The amount of this fine movement is set and controlled in accordance with the characteristics of the springback lid described above, the material of the 1st powder + 2nd powder, the amount thereof, and the like. After releasing the internal pressure by lifting the upper punch 1 in this way, pull down the die 2 as shown in Figure 0, and then lower the upper punch 1 as shown in Figure 1 (l). When it rises, it becomes free.The reason why cracks, peeling, burrs, etc. do not occur in this state is due to the effect of removing strain from the green compact 4a due to the slight rise mentioned above.

The operation diagram in FIG. 2 shows the top punch 1 in one cycle of the press for forming. Figure 4 shows the operating state of the die 2 and lower punch 3. The horizontal axis is time, as explained in Figure 1 (5)
The vertical axis corresponds to each state of the ~0 pull section, and the upper punch 1 at that time. Die 2. 5 shows the positional relationship of the lower punches 3.

Table 1 shows cracks, peeling, cracks, and dimensions of the molded product when the amount of rise of the upper punch 1 was varied in powder molding of clay@magnet as a practical example using the powder molding method of the present invention. This is data obtained by observing and evaluating the condition of

Table 1 * Springback amount 5.7%, ○, △,
wm) [Effects of the Invention] Hereinafter, the powder compacting method according to the present invention will be explained. Gui 2. In the process of molding powder with a large amount of sgelling hack using the lower punch 3,
After the pressure is maintained by the upper punch 1, the upper punch 1 is moved to the spring 5 after the pressure is released. By controlling the amount of displacement corresponding to the amount of pressure and raising it ten times, and removing pressure distortion,
It is highly effective in preventing cracking, peeling, etc. from forming on the molded product.

・・Powder 4a...Powder compact 4b... Molded object that's all Applicant: Seiko Electronic Components Co., Ltd. Agent: Patent Attorney Takayoshi Hayashi

[Brief explanation of drawings]

FIG. 1 (5) to 0D is a cross-sectional view showing the second stage of powder compaction according to the present invention, and FIG. 2 shows the operation of the upper punch, gouging, and lower punch at 1 g cycle of the press of FIG. 1. It is an operation diagram. 1... Upper punch 2... Gui 3... Lower punch (

Claims (1)

[Claims] In the method of molding powder with a large amount of springback using an upper punch, a die, and a lower punch, after the upper punch has completed pressurization and holding, the displacement of the upper punch is controlled in accordance with the amount of springback following the pressure release process. A powder compacting method characterized by raising the powder by