JPH0249839B2 - - Google Patents

Description

[Detailed Description of the Invention] [Summary] The present invention relates to an electric press device for powder materials. In particular, in order to compress powder materials, a constant pressing force is set, and this pressing force and the deformation reduction of the material are used to compress the powder material. Detects pressure changes and drives the servo motor.
In addition to obtaining the product by repeatedly stopping the servo motor, the method is characterized in that it is provided with a means for mitigating the impact when starting the servo motor, and a spring in the means for mitigating the impact functions as a device useful for detecting the pressing force of the powder material. be.

[Industrial application field]

The present invention relates to a device for compression molding powdered materials such as plastics and ceramics into a predetermined shape, and particularly relates to an electric press device using a servo motor.

[Conventional technology]

Conventionally, in a powder compression molding machine, when obtaining a predetermined molded product, pressure is continuously applied to the material in the mold until a predetermined pressure is reached.

When applying continuous pressure to the powder in this way,
The instantaneous pressure reaction force generated in the hydraulic device installed at the compression end causes the oil in the hydraulic device to escape through the relief valve, and the pressure is measured. When a predetermined pressure is reached, the pressure is determined. Release.
For this reason, the hydraulic system has drawbacks such as the complexity of replenishing a predetermined amount of oil in the case of the next compression molding.

Molded products that are continuously pressed will shrink and deform over time due to thermal factors and changes in the bonding state inside the molded product, and it cannot necessarily be said that each part is compressed under uniform pressure. .

[Problems to be Solved by the Present Invention] The present invention provides an electric press device for powder materials to obtain a molded product free from the above-mentioned drawbacks, and is capable of compressing powder intermittently to form a molded product. At the same time, the intermittent compressive force is buffered by a spring that presses the piston in the sub-cylinder located at the top of the main cylinder, reducing the shock applied to the device. It is useful as a means to cope with the pressing force, and the purpose is to obtain a high quality molded product while using the device for a long period of time.

[Means for solving problems]

The electric press device for powder materials of the present invention is an electric press device that detects the reaction force of the pressing force and controls the rotation of the servo motor in order to apply a constant pressing force to the powder material in the mold. A shaft section is provided that applies a pressing force to the powder material in the mold by the rotation of the motor, a main piston is provided at the end of the shaft section on the side opposite to the mold, and the main piston is positioned within the main cylinder. A small hole is provided on the side corresponding to the main piston, and the main cylinder and a sub-cylinder having a smaller diameter than the main cylinder are communicated through the small hole, and a sub-piston pressed by a spring is arranged in the sub-cylinder. The servo motor is driven and controlled by a pressure sensor installed in a part of the main cylinder.
The product is obtained through repeated stops.

[Effect]

In the electric press device for powder materials of the present invention,
In order to detect a constant pressing force on the powder material in the mold, the reaction force generated at the shaft end on the opposite side of the mold is applied to the main piston in the main cylinder, and the secondary piston in the secondary cylinder, which has a smaller diameter than the main cylinder, is pressed at a constant pressure. By being biased by a spring having a compressive force of It is possible to prevent damage, detect changes in oil pressure between the main cylinder and sub cylinder, and detect the pressing force due to shrinkage deformation of the powder material over time, and drive/stop the servo motor. The product is obtained through repetition.

〔Example〕

The drawings show an embodiment of an electric press device in a powder compression molding machine of the present invention.

The compressor main body 1 has a U-shape, and a mold 2 is disposed on a substrate 1a of the compressor main body 1, and a heater 3 is provided around the mold 2.

As a means for compressing the powdered material put into the mold 2, a gear 5 rotated by a servo motor 4 inside the frame 1b of the compressor body 1 is fixed to a ball screw shaft 6. The ball screw shaft 6 is fitted with a ball nut 9 fixed to the rear end of the ram 8 of the press, and the ram 8 of the press is connected to the frame 1b of the compressor main body 1. It is guided by a flange 10 provided in the opening, and a key 11 provided on the flange 10 engages with a keyway 12 formed in the ram 8 of the press, allowing the ram 8 of the press to rise and move without rotating. Make it perform a downward movement.

A punch 13 is fixed to the lower end of the ram 8 of the press, and compresses the powdered material between it and the mold 2.

A bearing 14 is attached to the end 6a of the ball screw shaft 6.
The end portion 6a and the bearing 14 are disposed within the main piston 15.

The main piston 15 is provided in a main cylinder 16 located at the top of the compressor body 1, and when no pressing force is applied to the punch 13 at the tip of the ram, the shoulder 15a of the main piston 15 is located at the top of the compressor body 1. It is engaged with the wall 1c.

The upper wall 16a of the main cylinder 16 has an opening 1
6b, and the upper wall 16 of this main cylinder 16
It communicates with a small-diameter sub-cylinder 17 arranged on the upper part a. A pressure sensor 19 is provided in the side opening 16c of the main cylinder 16.
The signal from the servo motor 4 is applied to a control device 20 which compares and calculates the signal with a pressure set value, and the control device 20 is connected to control the servo motor 4 via an amplifier.

A small-diameter sub-piston 18 is provided in the small-diameter sub-cylinder 17, and a step 18a of the sub-piston 18 is attached to a step 17a formed on the inner surface of the sub-cylinder 17.
end 18b of secondary piston 18 such that
The spring 21 acts as a pressing force. In order to adjust the pressing force of this spring 21, the end of the spring 21 is connected to the sub cylinder 17.
The adjusting screw 25 is attached to an end plate 25a of an adjusting screw 25 inserted through the upper wall 17b.

The space between the main piston 15 of the main cylinder 16 and the sub-piston 18 of the small-diameter sub-cylinder 17 is filled with oil 22 which has almost no compression ratio.
is the oil inlet.

24 is a pressure value setter provided in the control device 20.

With the above configuration, the control device 20 allows the necessary pressing force W to be applied to the powder material M to be put into the mold 2.
is set by the setting device 24, and the servo motor 4 of the powder compression molding machine is operated. The rotation of the servo motor 4 is controlled by a ball screw shaft 6 via gears 5 and 7.
, thereby through the ball nut 9,
The material M in the mold 2 is compressed by the ram 8 and the punch 13.

At this time, a reaction force of the pressing force of the punch 13 is generated at the end 6a of the ball screw shaft 6, and this reaction force is received by the main piston 15 and the main cylinder 16, and based on this reaction force, the material M and the ball screw A shock is generated on the shaft 6, ball nut 9, etc., but this shock is transmitted from the main cylinder 16 to the small diameter sub-cylinder 1.
7 is absorbed by the spring 21 behind the sub-piston 18 and alleviated.

In this case, the main piston 15 of the main cylinder 16
The area of the secondary cylinder 1 is large, and compared to this, the area of the secondary cylinder 1 is large.
Since the area of the secondary piston 18 of No. 7 is configured to be small, even if a strong pressing force is generated on the main piston 15, the reaction force of the pressing force W is small, and the force applied to the secondary piston 18, which functions as a hydraulic damper, is small. Therefore, the compressive force of the spring 21 is smaller than the pressing force W, and a small spring 21 is sufficient. Moreover, by setting the compression force of the spring 21 by rotating the adjusting screw 25, it becomes possible to accurately detect the pressing force W.

Spring 21 with reduced impact as described above
is caused by the compression force of the spring 21.
8 returns to the compressed state, and in this state, the oil pressure in the main cylinder 16 is measured by the detection of the pressure sensor 19, and if it is less than the specified pressing force W, the servo motor 4 continues to rotate and the specified pressing force is reached. When it reaches W, the rotation of the servo motor 4 is stopped by a signal from the control device 20. When the material M is deformed and reduced over time, the oil pressure inside the main cylinder 16 changes, and the pressure sensor 19 detects that the pressure is below the specified pressing force W, and the servo motor 4 is driven again, as described above. As a similar hydraulic damper, the action of the spring 21 in the sub-cylinder 17 relieves the shock applied to each part, and when the spring 21 returns, the hydraulic pressure in the main cylinder 16 is reduced to the specified pressing force W by the detection of the pressure sensor 19. Once reached, the signal from the control device 20 stops the rotation of the servo motor 4.

Pressure and pressure caused by the rotation of the servo motor 4
The product can be obtained by repeating the action of stopping, pressing, and stopping several times during the time required to mold the material.
During this time, the shock caused by repeated pressing and stopping is cushioned by the small-diameter sub-cylinder 17 provided above the main cylinder 16 and the spring 21 provided behind the sub-piston 18, thereby protecting each part of the device. has.

〔effect〕

When the electric press device for powder materials of the present invention starts applying a pressing force to the powder material in the mold using a servo motor, the impact generated in each part related to the shaft, which is a pressing member, is applied to the end of the shaft. It is absorbed by the arranged main piston, main cylinder, small-diameter sub-cylinder, and spring provided on the sub-piston of the sub-cylinder.

In addition, in the present invention, the pressing force necessary for molding the powder material is set to a constant value, and this pressing force is detected by a pressure sensor installed in the main cylinder, so the compression force of the spring corresponds to the standard pressing force. However, by making the diameter of the secondary piston smaller than that of the main piston, a smaller spring can be used, and the compression force of the spring can be controlled by the adjustment setting member provided at the end of the secondary cylinder. Can be matched accurately.

Furthermore, in the configuration of the present invention, the hydraulic pressure in the main cylinder between the main piston and the sub-piston is detected by a pressure sensor, and when the hydraulic pressure in the main cylinder indicates a certain pressing force necessary for molding, the servo is activated. The motor stops, and after a certain period of time, the reaction force by the main piston due to the deformation and contraction of the material decreases, and the hydraulic pressure in the main cylinder shows below a certain pressing force, and the servo motor is formed to drive. By repeating the operations of pressing, stopping, pressing, and stopping the powder material within a predetermined period of time to complete the product, it has the effect of obtaining uniform and high-quality products.

[Brief explanation of the drawing]

The drawing shows an electric press device for powdered materials according to the invention. 4... Servo motor, 6, 8, 13... Shaft part, 15
...Main piston, 16...Main cylinder, 16b...Small hole, 17...Sub-cylinder, 18...Sub-piston, 2
1...Spring, 19...Pressure sensor, 25...Adjustment setting member.

Claims (1)

[Claims] 1. In an electric press device that detects the reaction force of the pressing force and controls the rotation of a servo motor in order to apply a constant pressing force to the powder material in the mold, A shaft section that applies a pressing force to the powder material in the mold is provided, a main piston is provided at the end of the shaft section on the side opposite to the mold, the main piston is positioned in the main cylinder, and the main piston is located in the main cylinder. A small hole is provided on the side corresponding to the piston, and the main cylinder and a sub-cylinder having a smaller diameter than the main cylinder are communicated through the small hole.A sub-piston pressed by a spring is disposed in the sub-cylinder, and the main cylinder An electric press device for powder materials, characterized in that a product is obtained by repeatedly driving and stopping a servo motor using a pressure sensor installed in a part of the press. 2. The electric press device for powder materials according to item 1, characterized in that a setting member for adjusting the compression force of the spring that presses the auxiliary piston in the auxiliary cylinder chamber is provided outside the auxiliary cylinder chamber so as to correspond to the pressing force. .