JPS6360082B2 - - Google Patents

Description

Detailed Description of the Invention The present invention determines the impedance, which changes state as the sintering progresses, when firing and sintering by applying ultrasonic waves, and determines the sintering state. The present invention relates to a sintering apparatus capable of performing controlled sintering control.

Conventional sintering equipment fills a mold with a uniformly mixed composition, heats it under pressure, obtains the desired density and solubility, and cools it. Mechanisms for maintaining uniform dispersion during the mixing process or sintering process include a time control mechanism, temperature control, and a mechanism for controlling the contraction state of the sintered body as a signal. however,
It is desirable to be able to use a method or device that maintains obvious simplicity and workability and can produce high-quality products with high efficiency in a single step in a short period of time, but conventional devices cannot sufficiently achieve this purpose. Ta.

The present invention deals with a sequential reaction that proceeds in the sintering process from the step of obtaining a mixed homogeneous composition,
For example, by providing a sintering device that can accurately detect density changes, etc., and control them adaptively in accordance with the situation,
The main purpose is to solve the problems mentioned above and achieve the objectives.

The device of the present invention consists of the following device parts. That is, a mold to be filled with the powder mixture, a punch to press the powder filled in the mold, a pressure device to press the punch, a vibration device to apply ultrasonic vibration to the punch, and the vibration device. and a control device that detects and discriminates impedance changes to display the progress of sintering or to apply a signal to the pressurizing device or the like. The apparatus of the present invention is provided with an electromagnetic field device section for carrying out the operation in a required electric field or magnetic field depending on the application, thereby achieving the object of the present invention more effectively.

Next, the present invention will be explained by illustrating one embodiment.
FIG. 1 is a partially sectional front view for explaining a system model according to an embodiment of the present invention, and FIG. 2 is a diagram showing the relationship between impedance and change in sintered body density. In this example, the composition of the starting powder composition was a mixture of samarium cobalt (particle size: 500 mesh) and 16 vol% of phenol as a binder (referred to as mixed composition A) when molding the magnet. The ultrasonic wave used is 1.5kw, 28kHz.

In FIG. 1, the required amount of mixed composition A is filled into the inner cavity 1 of a mold 10 for sintering. The upper punch 6 is fixed and the lower punch 7 is pressurized to compress the composition. The vibration of the ultrasonic vibrator 9 acts on the upper punch 6 through the horn 2 to apply vibration to the mixed composition A in the inner cavity 1. 4 is an oscillator, and the oscillating high frequency is applied to the vibrator 9 through circuits 25 and 26. 8 is a cylinder that pressurizes the punch 7, and the pressurizing pump part 5
controlled by Reference numeral 3 denotes a control device that detects and discriminates impedance changes based on current and voltage from an energizing circuit between the oscillator 4 and the vibrator 9, and sends a control signal to the pump 5. A circuit 24 applies a signal to the pump 5 to control its operation. When driving the cylinder 8 to apply pressure to the punch 7 or to apply molding pressure, a stop signal is sent from the pump 5 to the oscillator 4 via the circuit 23.

In the above process, the mixed composition to be molded is filled into the mold 1, the upper and lower punches 6 and 7 are fitted together, and the vibrator 9 is pressed while driving the cylinder 8 to apply initial pressure.
to apply ultrasonic vibration. As molding and sintering progress due to this pressurization and vibration, the impedance to the vibration applied gradually changes, and this change is constantly detected from the vibration power supply circuit, and the signal is discriminated by the device 3, and the impedance change is adjusted to a predetermined value. When the pressure is reached, pump 5 is activated to apply upset molding pressure.
command and control. In this way, when the cylinder 8 is driven by the operation of the pump 5 to apply molding pressure, a stop signal is issued from the pump section 5 to stop the oscillator 4.

The above mixed composition A is a ferromagnetic material, but in the case of such a composition, or in the case of sintering an electrode material, the impedance can be detected and measured in an electric field or a magnetic field and controlled as described above. The effect can be further enhanced by proceeding with sintering. Overall, the relationship between density and impedance in this case is:
Changes in B, C, and D can be seen during the sintering process, but
By outputting a discrimination signal from the control device 3 at each of these points and controlling the pressing force to change the impedance along the curve A, a uniform and desired density can be obtained. Of course, the pressure control using the detected impedance as a signal can be controlled along various arbitrary curves corresponding to the purpose of sintering.

When the above-mentioned mixed composition A is subjected to the above-mentioned ultrasonic waves, and a pressure force of 2000 Kg/cm ² is applied by a cylinder, and a magnetic field of 10 KOe is applied, it can be produced in about 1/2 the application time of the usual one, 16MGO's were obtained. Note that sintering can be performed by external heating using a heater or the like, or by high-frequency heating.

The present invention has been described above with reference to one embodiment.
Vibration impedance detection can detect mechanical impedance directly from the vibrator, and by determining this detected impedance, the sintering progress state can be accurately known, and adaptive control such as pressurization and heating can be performed. This allows the product to be sintered and molded to have properties suited to the purpose.

[Brief explanation of the drawing]

FIG. 1 is a partially sectional front view of an embodiment of the present invention.
Figure 2 is a diagram showing the relationship between density and impedance. 1... Sintered mold lumen, 10... Sintered mold, 9... Vibrator,
8...Cylinder, 3...Control device, 4...High frequency oscillator, 5...Control pump, 6, 7...Upper and lower punch, 2
3, 24, 25, 26, 27, 28, 29...Circuit, 21, 22...Hydraulic pipe.

Claims (1)

[Claims] 1. In a product that pressure-sinters and molds a powder mixture composition, a mold that is filled with the powder mixture, a punch that presses the powder filled in the mold, a pressurizing device that presses the punch, and It is characterized by being provided with a vibrating device that applies ultrasonic vibration to the punch, and a control device that detects and discriminates changes in the impedance of the vibrating device to display the sintering progress state or to apply a signal to the pressure device, etc. A sintering device that uses ultrasonic waves.