CS199028B1 - Stopping device for quick feed of tool - Google Patents

Description

BACKGROUND OF THE INVENTION The present invention relates to a device for stopping rapid traverse of a tool, in particular an abrasive disc, provided with a current transformer with a primary connected in the tool drive motor circuit, a rectifier with a derivative member connected to the secondary winding of the current transformer.

The device for switching off the rapid traverse of the tool takes advantage of the fact that when the tool moving at the accelerated feed touches the workpiece, the current in the power supply circuit of the motor driving the grinding wheel increases sharply, or the torque increases. This current pulse is fed through a current transformer with a primary connected in one phase of the grinding wheel drive motor, after streaking and insanity, to a relay that switches off the accelerated feed. The next tool feed is already at the speed prescribed for the working operation. However, prior art devices equipped with DC amplifiers with tube or transistor components are characterized by instability of operation, where the initial level at which the device is to be switched is relatively frequent and the sensitivity of conventional amplifier devices is not sufficient and the device reacts to touch delay. tool material means very sharp tool engagement, which is undesirable especially when working on brittle materials or thin-walled structures.

199 028

199 02B

This lack of data is decoupled from the device according to the invention by providing a comparator and hyeteresis, the inverting input of which is connected to the rectifier output, and whose non-inverting input is connected via a first voltage divider to a DC voltage source; a voltage divider connected to a high-level gate in an inverter circuit, whose output is via a switching transistor, whose collector is connected to a power supply via a trip relay.

The use of integrated circuits in a given circuit not only significantly increases the stability and sensitivity of the device, but also my faster response to the input signal, much longer service life and operational reliability.

An example of a device according to the invention is shown in the attached drawing showing the circuit diagram of the control circuit.

In one phase of the grinding spindle drive motor 1, a current transformer 2 is connected by its primary. The output voltage of the current transformer 2, which is proportional to the current of the motor 1, is applied to the rectifier 6. The output of the rectifier 8 is connected via the first capacitor 6 to the inverting input 6 of the comparator 6. The non-inverting input 6 of the comparator 6 is connected to the power supply source 8 via the first protective resistor 6 and the first voltage divider consisting of the first resistor 10 and the second resistor 11. 12. The supply voltage to the inverting input 6 is supplied from the slider of the potenoiometer

13. which is connected to a first voltage divider. The potentiometer 13 is used to adjust the initial voltage difference between the inverting and non-inverting inputs 6, 6 of comparator 6 and the initial switching level of the device. The epol potentiometer 13 and the first capacitor 6 simultaneously form a refractory member for the output pulse of the rectifier 6. The comparator 6 is provided with third and fourth capacitors 14, 15 forming the frequency compensation, the lower the value of these capacitors 14. The higher the frequencies the comparator 6 transmits, and thus the faster it reacts to the input changes. The feedback resistor 16 creates hysteresis of the comparator 6. The first diode 17 provides protection against congestion of the inverting input 6. The second and third diodes 29, 30 connected antiparallelly between the inverting and non-inverting inputs 6, 6 prevent the comparator 6 from overloading. of the negated product connected as an inverter. The integration capacity 21 increases the noise immunity of the gate 20. The gate 20 is connected via a matching diode 22 formed by a fourth diode 23 by a fifth and a sixth resistor 24. 25 based on a switching transistor 26 whose collector is connected to a power supply 8 via a relay 27 s. a protective diode 28, which serves to switch off the rapid traverse of the tool.

In the quiescent state, the voltage at the non-inverting input vždy is always more positive than at the inverting input,, so that the output of comparator 6 has a positive voltage. The step change of current in the power supply circuit of the grinding load drive motor 1 comes in the form of a voltage derivative

· The output voltage of comparator £ drops to zero and closes the switching relay 22 ·

The sensitivity of the circuit is set by the slider 13 of the potenoiometer, thus selecting the magnitude of the phase current change of the drive motor 1 to which the device is to respond.

Claims (1)

SUBJECT OF THE INVENTION Apparatus for adjusting rapid traverse of a tool, in particular an abrasive wheel, provided with a current transformer with a primary connected in the tool drive motor circuit, a rectifier with a derivative member connected to the secondary winding of the current transformer, and a trip relay for switching off the feed (6) and hysteresis, whose inverting input (5) is connected to the output of the rectifier (3), and whose non-inverting vatup (7) is connected via a first voltage divider to a DC supply source (8), the comparator output (6) via a second voltage divider connected to the high-level gate (20) in an inverter circuit, the output of which is connected via a matching element (22) based on a switching transistor (26) whose collector is connected to a power supply (8) via a trip relay (27).