JP3031131B2 - Powder molding product manufacturing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a powder-formed product capable of obtaining a stable quality irrespective of an undercut position of the powder-formed product or a slight variation in the filling amount of the material powder.

[0002]

2. Description of the Related Art Conventionally, when an undercut is formed on a powder-formed product, the process is generally performed as follows.

First, as shown in FIG. 3A, both contact surfaces of an upper die 10 and a lower die 12 are aligned, and a lower punch 16 is inserted into an inner hole of the lower die 12 to form a mold space. The material powder 20 is filled into the mold space with the cam die 14 inserted into the mold space.

Next, as shown in FIG. 1B, an upper punch 18 is inserted and moved into the upper die 10 from above in order to compress the material powder 20 filled in the mold space. The material powder 20 is compressed with this movement, but the positions of the upper die 10 and the lower die 12 are shifted downward as the upper punch 18 moves.

[0005] When the compression of the material powder 20 is completed as described above, first, as shown in FIG.
Is pulled out of the mold space, and then the lower punch 16 is fixed, so that the upper die 10, the lower die 12, and the upper punch 18 are moved upward as shown.

Then, as shown in FIG. 1B, only the upper die 10 is further moved upward and separated from the lower die 12.

When the upper die 10 comes off the molded product 20A, as shown in FIG. 5, the lower die 12 is moved downward while the upper die 10 is moved upward to take out the molded product 20A. Note that the steps of FIG. 4B and FIG. 5 may be performed simultaneously.

As described above, when a molded product having an undercut portion is formed, the load applied to the upper punch 18 and the lower punch 16 during compression is generally non-uniform. In this sense, a load sensor is provided on the cam die 14, the upper and lower punches 18, 16 and the like, and an error signal is output when an abnormal load occurs during pressurization or depressurization.

[0009]

However, in such a conventional manufacturing apparatus, an overload on the mold is simply detected, and a major problem due to cracking of the mold is not caused. Although it could be prevented, it was not possible to prevent galling and poor density due to variations in the filling amount of the material powder.

FIG. 6 shows the relationship between the load applied to the upper punch 18 and the number of moldings when a molded article is manufactured by a conventional method, and FIG. 7 shows the load applied to the lower punch 16 and the number of moldings in the same case. FIG. As can be seen from this figure, the loads received by the upper and lower punches 18 and 16 are not constant, but rather fluctuate. As a result, the stress applied to the cam die 14 naturally fluctuates as shown in FIG. 6 to 8 were examined in detail, and a correlation diagram as shown in FIG. 9 showing the relationship between the bending stress of the cam dies and the load difference between the upper and lower punches was obtained. In other words, it can be seen from this figure that the bending stress applied to the cam die depends on the load difference between the upper and lower punches.

Therefore, if this load difference can be reduced, it is possible to prevent occurrence of galling of the cam die 14 and poor density of a molded product bordering the cam die 14.

The present invention has been made in view of the above-mentioned conventional problems, and obtains stable quality regardless of the undercut position of the powder-formed product and the slight variation in the filling amount of the material powder. It is an object of the present invention to provide an apparatus for manufacturing a powder-formed product that can be used.

[0013]

In order to achieve the above object, the present invention provides an upper die and a lower die forming side walls of a mold space filled with material powder, and forming upper and lower walls of the mold space. An upper punch and a lower punch which are arranged to face each other to compress the material powder to be filled into the mold space from both opening sides of the mold space, and the upper die and the lower die in a moving direction of the upper punch and the lower punch. A driving unit for moving, a load detecting sensor for detecting a load applied to each of the upper punch and the lower punch when the material powder is compressed, and a position for detecting a relative position of the upper die and the lower die with respect to the lower punch. A detection sensor; load difference calculation means for calculating a load difference between the upper punch and the lower punch based on a detection result of the load detection sensor during the previous compression of the material powder; The optimum relative position of the upper die and the lower die with respect to the lower punch is calculated in accordance with the load difference calculated by the calculating means, and the upper die and the lower die during powder filling are set to the optimum relative positions. Control means for driving the driving means based on a signal from the position detection sensor.

[0014]

The present invention thus constructed operates as follows.

The load detecting sensor detects a load applied to each of the upper punch and the lower punch when the material powder is compressed.

[0016] The load difference calculating means is based on the detection result of the load detection sensor at the time of the previous compression of the material powder,
The load difference between the upper punch and the lower punch is calculated.

The control means calculates an optimum relative position of the upper die and the lower die with respect to the lower punch in accordance with the load difference calculated by the load difference calculating means, and calculates the relative positions of the upper die and the lower die during powder filling. The upper die and the lower die are moved to the upper punch and the lower die based on a signal from a position detection sensor that detects a relative position of the upper die and the lower die with respect to the lower punch so that the optimal relative position is set. Driving means for moving the punch in the moving direction is driven.

[0018]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a schematic configuration of a control system in a powder-formed product manufacturing apparatus according to the present invention.

The upper punch load sensor 1 and the lower punch load sensor 2, which are load detecting sensors, are mounted directly on the pressurizing surface of the upper punch 18 or the lower punch 16, or a hydraulic pressure for moving the upper punch 18 or the lower punch 16 up and down. Attached to the mechanism. As the load sensor, a pressure sensor, a strain gauge, or the like can be used.

The servo valve linear sensor 3 as a position detecting sensor is a sensor for detecting the relative positions of the lower punch 16 and the upper die 10 and the lower die 12. Therefore, the relative position detected by this sensor corresponds to the distance from the pressing surface of the lower punch 16 to the upper opening surface of the mold space formed by the upper die 10 as shown in FIG. .

The hydraulic servo mechanism 5 as a driving means drives the upper die 10 and the lower die 12 in the vertical direction by hydraulic pressure.

The CPU 8 functions as load difference calculating means and control means, and controls the positions of the upper die 10 and the lower die 12 in accordance with the following flowchart.

The flowchart shown in FIG. 2 shows a process for adjusting the filling amount of the metal powder in accordance with the difference in load between the upper and lower punches.

First, the load P1 received by the upper punch 18 when the metal powder 20 is pressurized in the state shown in FIG. 3B is detected by the upper punch detection sensor 1 and in the same state. The load P2 received by the lower punch 16 is detected by the lower-punch detection sensor 2 (S
1) The CPU 8 receives the detection signals from these sensors and calculates the load difference ΔP between the upper and lower punches (S2). Next, the CPU 8 determines whether or not the calculated load difference ΔP is within the set range R (S3).

If the load difference ΔP is within the set range R, there is no problem in performing the next molding in this state.
Subsequently, the molding process (manufacture of a molded product) is performed as it is (S7).

On the other hand, if the load difference ΔP is not within the set range R, it is determined which of the upper punch 18 and the lower punch 16 is heavier (S4). Since it is necessary to prevent the load from increasing during molding, a process of lowering the original positions of the upper and lower dies 10, 12 positioned at the time of powder filling to reduce the filling amount is performed. Specifically, the upper and lower dies 10, 1 at the time of powder filling this time
The original position of No. 2 is recognized by the servo valve linear sensor 3, and the relationship between the change distance of the original position and the increase / decrease of the load difference is input to the CPU 8 in advance, so that the detected load difference is eliminated. In which direction (vertical direction) should the original position be moved and how long should it be moved?
U8 can be calculated immediately. CP obtained in this way
Based on the calculation result of U8, the original positions of the upper and lower dies 10, 12 in the next molding are lowered. From the next time, this is set as a new original position (S5). Conversely, if the load difference on the lower punch 16 side is large, the same operation as described above is performed, and the upper and lower dies 10, 12 are increased in order to increase the filling amount.
Is carried out to raise the original position from that of the previous time (S6).

By performing the above processing, the load difference from the next time falls within the set range R.

In order to eliminate the load difference, a method of changing the strokes of the upper and lower punches 18 and 16 can be considered, but this is not practical because it adversely affects the dimensions of the molded product. Also, in the above embodiment, the description has been given of the case where the load difference is eliminated by adjusting the filling amount of the metal powder.However, if the load difference is too large to be eliminated by adjusting the filling amount, an alarm is issued. It is also possible to add a process such as issuing or canceling the operation. In this way, a more realistic device is obtained.

[0029]

As described above, according to the present invention, the filling amount of the material powder is adjusted according to the load difference between the upper and lower punches, so that the cam dies can be prevented from galling. In addition, since uniform pressing can be performed in the vertical direction with the cam die as the center, it is possible to prevent stiffness, dimensional defects, molding cracks, and the like due to poor density, and to stabilize the quality of molded products.

[Brief description of the drawings]

FIG. 1 is a block diagram of a control system of the apparatus of the present invention.

FIG. 2 is a flowchart showing an operation of the apparatus shown in FIG.

FIGS. 3A and 3B are diagrams showing a procedure of a conventional molding method.

4 (A) and (B) are views showing a procedure of a conventional molding method performed subsequently to the procedure of FIG. 3 (B).

FIG. 5 is a diagram showing a procedure of a conventional molding method performed subsequently to the procedure of FIG. 4 (B).

FIG. 6 is a diagram showing the relationship between the load of the upper punch and the number of moldings.

FIG. 7 is a diagram showing the relationship between the load of the lower punch and the number of moldings.

FIG. 8 is a diagram showing a relationship between bending stress of a cam die and the number of moldings.

FIG. 9 is a diagram showing a relationship between a load difference between upper and lower punches and a bending stress of a cam die.

[Description of References] 1 ... Load sensor for upper punch 2 ... Load sensor for lower punch 3 ... Linear sensor for servo valve 5 ... Hydraulic servo mechanism 8 ... CPU 10 ... Upper die 12 ... Lower die 14 ... Cam die 16 ... Lower punch 18 ... Upper punch 20: Material powder 20A: Molded product

Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B30B 11/02 B22F 3/03 B30B 11/00

Claims (1)

(57) [Claims] An upper die (10) and a lower die (12) forming side walls of a mold space filled with a material powder (20), and upper and lower walls of the mold space are formed and filled in the mold space. Upper punch (18) and lower punch (16) disposed to face each other to compress the material powder from both opening sides of the mold space, and the upper die and the lower die in the moving direction of the upper punch and the lower punch. A driving means (5) for moving, a load detection sensor (1, 2) for detecting a load applied to each of the upper punch and the lower punch when the material powder is compressed, and a lower part of the upper die and the lower die. A position detection sensor (3) for detecting a relative position with respect to the punch; and a load difference calculating means for calculating a load difference between the upper punch and the lower punch based on a detection result of the load detection sensor during the previous compression of the material powder. (8) and the load difference calculation means The optimum relative position of the upper die and the lower die with respect to the lower punch is calculated according to the load difference, and the upper die and the lower die during powder filling are set to the optimum relative position. Control means (8) for driving said driving means based on a signal from a position detection sensor.