SU856729A1 - Electric discharge machine for piercing holes - Google Patents

Description

I

This invention relates to EDM. processing, namely, to the designs of 1. machines for piercing holes. 1 The electrical erosion machine is known, the electrode tool of which is installed in the spindle connected to the feed drive and the wear compensation mechanism controlled by the automation unit according to the signals of the limit switches. The compensation mechanism is made in the form of Two rods placed in correspondingly different compressive force friction clamps rigidly connected to the movable carriage and fitted with a slide fixed on the frame, the stone of which is movably connected to one of the rods, and the free end interacts with a rigid stop, mounted on the second boom 1.

Such an EDM machine design allows for improved machining performance by automating wear compensation. However, the sliding of the clamp relative to the rod occurs during processing, thereby impairing the stability of the process. In addition, the field of application of the mechanism is limited to the piercing of parts with holes that are identical both in cross section and in depth of processing, i.e. with the same wear of the electrodes on all passes.

The purpose of the invention is to eliminate the effect of electrode wear on the treatment process, which ensures the stability of the erosion process.

This goal is achieved by the fact that in the proposed machine, the electrode wear compensation mechanism is made in the form of a pole that interacts with a rod rigidly connected to the spindle and with limit switches limiting the spindle stroke. In this case, the compensation mechanism ensures the progression of the spindle stroke depending on the amount of wear, i.e. The downward stroke of the spindle increases by the amount of wear, which is ensured by annular grooves on the rod, arranged in steps equal to the average amount of wear of the electrodes.

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FIG. 1 schematically shows the proposed machine, a general view; in fig. 2 - compensation mechanism; in fig. 3 (A, B, C,

D, D) - scheme of the mechanism of compensation.

The machine includes spindle 1 associated with a feed motor. A multi-electrode head 2 with electrodes 3 is fixed in spindle products and pneumatic drive mechanism

7 compensation. The electrode wear compensation mechanism is made in the form of a slider 8 mounted for discrete movement on a rod 9 equipped with annular grooves for programming the spindle stroke. The step of the annular grooves is equal to the average wear of the electrodes on the previous pass. For the case of processing products with several holes of different depth, the annular grooves are made with variable pitch, and for the case of machining parts with holes of the same depth, the annular grooves can be replaced by a thread.

The slider is held on the rod by a spring-loaded retainer 10 entering the annular grooves. The slider 8 has protrusions interacting with end microswitches mounted on the frame, the upper 11 and lower 12 switches are the spindle travel limiters, the middle switch 13 serves for giving the command to rotate the products. On the frame there is an actuator 14 associated with a pneumatic drive of the compensation mechanism.

The proposed machine works as follows.

The parts are mounted on the base mandrels 4. Before starting the processing, in the initial position of the i-ro passage, the protrusion of the slider 8 is at a distance ti from the lower microswitch 12, which limits the spindle travel (A in FIG. 3) downwards. After filling the bath with working fluid, the spindle 1 together with the multi-electrode head 2 and the rod 9 with the slider 8 sitting on it starts the working stroke downwards, the holes are pierced with electrodes 3. By the time the firmware is finished and the holes are calibrated, the spindle passes the distance ti, the slider

8 its protrusion presses the lower microswitch 12 (B in Fig. 3). The wear of electrodes during the i-th passage is equal to the value of Al.

On a microswitch 12 signal, the spindle 1, controlled by the automation unit 6, together with the multielectrode head 2, the rod 9 and the slide 8 quickly go up until the electrodes 3 come out of the machined holes of 2-3 mm. At this moment, the slider 8 with a protrusion presses the middle microswitch 13 (B in FIG. 3),

On a signal which the pneumatic cylinder 5 rotates the products turns them to a predetermined angle. The spindle 1 with the rod 9 and the slider 8 continue upward movement until the upper microswitch 11 is activated, which is the upward movement limiter. The spindle 1 stops, not the income to its original position before the i-th pass for a distance equal to the amount of wear of the electrodes.

Simultaneously with the stop of the spindle 1, the upper microswitch 11 sends a command to the compensation actuator 7, which through the actuator 14 moves the slider 8 with the latch 10 upwards from one annular groove of the rod 9 to the other. Thus, the position of the slider 8 relative to the spindle 1 and the lower microswitch 12, which limits the spindle movement downwards, changes, increasing by the step size of the annular grooves tt equal to the previously known average wear of the electrode on the i-th passage.

After actuation of the pneumatic actuator 7 compensation and return it and the actuator 14 to its original position, the machine is ready for the next () th pass. The command to move the spindle 1 downward is given, the cycle repeats, but before the (i + 1) -th pass, the spindle is already in the new original position, close to the part by the Al-I value, and the spindle stroke on the i + 1 pass is equal to the new The distance from the ledge of the slider to the lower microswitch 12 ((.14-1).

The machine machined parts with several holes of 3.5 mm, a piercing depth of 8 mm, a calibration depth of 25 mm, the electrode wear in a single pass was 2 mm, the annular grooves on the brush were replaced with threads with a step t-2 mm; In addition, samples of parts with several holes of 3.5 mm, a piercing depth of 8 mm and 12 mm, wear of the electrodes, respectively, were 2 and 3 mm, the annular groove spacing on the rod was variable, respectively, 2 and 3 mm.

The use of the proposed device makes it possible to program the amount of compensation for electrode wear when machining parts with different hole piercing depths, to easily change the program for compensating movement of spindles by replacing the rod.

At the same time, the rigidity of the compensation system and the absence of its mechanical effect on the operation of the feed regulator during flashing provide an increase in the stability of the erosion process of multielectrode treatment, and also makes it possible to automate the process.

Claims (1)

Invention Formula An electroerosive machine for forgiving holes with an electrode tool installed in a spindle connected to a feed drive and a wear compensation mechanism controlled by an automation unit using limit switch signals, characterized in that, in order to increase the stability of the machining process by programming the spindle stroke taking into account the amount of wear of the electrode tool, the wear compensation mechanism is made in the form of a rigidly connected spindle, which has annular grooves of the rod and the slider mounted on it with the possibility of axial movement when exposed to the actuating element of the compensation mechanism, with the step of annular grooves equal to the average amount of wear of the electrode-tool. Sources of information taken into account in the examination 1. USSR author's certificate jVo 302927, cl. B 23 P 1/08, 1968. u.