CS252009B1 - Connection of thyristor demagnetizing and magnetizing device - Google Patents

Abstract

By combining magnetic clamping of workpieces and their demagnetization, i.e. removal of residual remanent magnetism, it is possible to connect a thyristor demagnetization and magnetization device to workpiece clamping devices, e.g. of a surface grinder with mutual interconnection of the power transformer, control circuits with control elements and a power thyristor stage controlling the clamping electromagnet according to the invention, the essence of which is that in the control circuit (4j, the rectifier circuit (21) with stabilization is connected to the circuit (22) of the phase control of the thyristors and the terminal transistor (25) and the ignition pulse transformer (26), further connected to the circuit (23J of the change in the frequency of the polarity of the supply voltage of the electromagnet and the circuit (24), the length of the demagnetization time, while the power thyristor stage (2) consists of two pairs of antiparallel connected thyristors (Yl, Y2, Y3, Y4) with protective resistors (Rl, R2, R3, R4).

Description

Bile magnetic clamping of workpieces and their degaussing, i. j. Removal of residual remanent magnetism makes it possible to connect the thyristor demagnetizing and magnetizing devices of workpiece clamping devices, e.g. plane grinder with interconnection of power transformer, control circuits with controls and power thyristor stage controlling the clamping electromagnet according to the invention, characterized in that in the control circuit (4j) the stabilizing circuit (21) is connected to the phase (22) of the phase controlled by thyristors and a terminal transistor (25) and an ignition pulse transformer (26), further coupled to a circuit (23J) of the electromagnetic supply voltage polarity change frequency and circuit (24), degaussing time lengths, the power thyristor stage (2) forming two pairs antiparallel connected thyristors (Y1, Y2, Y3, Y4) with protective resistors (R1, R2, R3, R4).

The invention relates to the connection of a thyristor demagnetizing and magnetizing device, magnetically clamping tables of plane grinders. Until now, a direct current source, which constitutes a power transformer, usually with a two-way rectifier, has been used for magnetic clamping of workpieces when machining on a surface grinder.

Either a reversing switch is used to remove remanent magnetism residues from the clamped workpiece - degaussing, wherein the degaussing is performed by manually switching - reversing the switch, i. j, by reversing the polarity of the solenoid supply voltage, or by an automatic degaussing device in which the degaussing is also performed by reversing, by means of two relays while simultaneously applying the step resistors to the solenoid coil circuit and thereby gradually decreasing the supply voltage.

The disadvantage of the first method of degaussing the workpiece is the low degaussing efficiency, even with maximum simplicity.

The automatic degaussing device essentially spins the requirement to remove remnants of remanent magnetism from the clamped workpieces, but the use of step selectors does not allow it to be used in the higher solenoid coil currents. A further disadvantage is the series connection of the series resistors to the coil circuit of the electromagnet to create a gradual drop in the supply voltage, thereby reducing energy efficiency.

The above drawbacks are overcome by the connection of a thyristor degaussing and magnetizing device for plane grinders interconnected with a power transformer, control circuits with controls and a power thyristor stage controlling the clamping solenoid according to the invention, the principle being that the control circuit has a stabilizing rectifier circuit connected to a thyristor phase control circuit with a terminal transistor and an ignition pulse transformer, further coupled to a frequency change circuit of the electromagnetic power supply voltage, and a degaussing time length circuit, the power thyristor stage being two pairs of antiparallel connected protective resistor thyristors.

Involvement of thyristor degaussing and magnetizing devices achieves higher degaussing efficiency, higher energy efficiency and saving of magnetization source compared to similar devices.

The essence is documented in the accompanying drawings.

Fig. 1 is a block diagram of the whole apparatus; FIG. 2 shows its control part and FIG. 3 thyristor power stage.

The thyristor demagnetizing and magnetizing device (Fig. 1) consists of a power transformer 1, a power output thyristor stage 2, control circuits 4, an input potentiometer 5 for a continuously adjustable frequency change polarity of the solenoid supply voltage 3, an input potentiometer 6 for time adjustment of the degaussing function. and the degaussing function selection buttons 7 - - magnetising.

The power thyristor stage 2 (Fig. 3) consists of anti-parallel connected thyristors Y1, Y2, Y3, Y4, with protective resistors R1, R2, R3, R4, connected in the control electrodes of thyristors Y1, Y2, Y3, Y4.

The control circuits (Fig. 2) consist of a rectifier 21 with stabilization to which a power transformer is connected with its output. The output of the rectifier circuit 21 supplies the thyristor phase control circuit 22, the polarity change circuit 23 of the solenoid supply voltage and the degaussing time duration circuit 24.

The thyristor phase control circuit 22 supplies an output transistor 25 with a pulse ignition transformer 26, via the relay contacts 30, 31, and 32 in circuit 23, of the thyristor control electrodes Y1, Y2, Y3, Y4 (FIG. 3).

The input of the polarity change frequency potentiometer 5 and the potentiometer β of the duration of the degaussing time, as well as the control buttons 7 of the magnetization function input, respectively, are connected to the output of the polarity frequency changing circuit 23 of the electromagnet supply voltage and the degaussing time duration circuit. demagnetization.

When connected to the mains, the device is ready for immediate operation. By pressing the magnetizing function button 7, the control circuit activates the thyristors Y2 and Y4 (FIG. 3) via the relay contact 32 (FIG. 3), thereby applying voltage to the thatch electromagnet 3, which is thus continuously supplied with direct current.

After the machining operation is completed, the degaussing function button 7 is pressed to connect to the thyristor phase control circuit 22 (FIG. 2) the polarity reversal circuit 23 and the degaussing duration time circuit 24 and the actual degaussing function is started by alternately connecting the thyristors Y1 and Y3. (Fig. 3) with thyristors Y2 and Y4 (Fig. 3) as a function of the specified rate of change in polarity by potentiometer 5, wherein the thyristor phase control circuit 22 provides a gradual decrease in the power supply voltage of the clamp thatch solenoid 3 6th

At the end of the cycle, the device disconnects. The new cycle is performed by pressing the magnet function button 7 again.

Claims (1)

Connection of the thyristor demagnetizing and mangeting device of workpiece clamping devices, e.g. a plane grinder, with the interconnection of the power transformer, the control circuits with the controls and the power thyristor stage controlling the clamping solenoid, characterized in that in the control circuit (4j) the stabilizing circuit (21) is connected to the thyristor phase control circuit (22). with a terminal transistor (25) and an ignition pulse transformer (26), further coupled to the electromagnetic supply voltage polarity frequency changing circuit (23) and the degaussing duration length circuit (24), the power thyristor stage (2) being two pairs of antiparallel connected thyristors (Y1, Y2, Y3, Y4j with protective resistances (R1, R2, R3, R4).