JP2589980B2 - Wire cut electric discharge machine - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a wire-cut electric discharge machine, particularly to one provided with a heater for cutting a wire electrode.

[Prior art and problems]

Conventionally, in wire-cut electric discharge machines, various devices are used for cutting wire electrodes at the end of electric discharge machining, for connecting wire electrodes in preparation work before starting machining, or for cutting wire electrodes during automatic connection. There is. For example, it is known that a wire electrode is heated and cut by directly energizing the wire electrode. In this case, it is necessary to lengthen the energizing heating section of the wire electrode, the electrode is wasted at the time of cutting, it takes a long time to raise the cooled wire electrode cutting temperature, it is inefficient, and the cutting point is not determined, In some cases, heating may not be sufficient and cutting may not be possible, resulting in low reliability.

[Solution for problem]

The present invention has been proposed in order to improve the above points, and discharges a workpiece by a wire electrode which is supplied from a reel and travels between guides with a predetermined tension and speed by a brake roller and a take-up roller. In a wire-cut electric discharge machine, a heater that stretches and cuts a wire electrode in a tensioned state by heating, a temperature sensor provided in the heater to detect a temperature of the heater, and a detection signal of the temperature sensor And a temperature control power supply for maintaining and controlling the temperature of the heater at a predetermined temperature, wherein the heater is provided with a predetermined tension on a wire electrode traveling path between the brake roller and the workpiece. Are arranged so as to be able to contact and separate from a predetermined position of the wire electrode. Preferably,
The heater is formed by winding a heater coil around a heat-resistant refractory material, and a temperature detection point of the temperature sensor is arranged at a predetermined position in contact with the wire electrode of the heater.

[Action]

Based on the detection signal of the temperature sensor provided in the heater, the temperature can be maintained at a temperature suitable for cutting the heater into the wire electrodes by the temperature control power supply. When the heater is moved and brought into contact with a predetermined position of the wire electrode, the wire electrode is heated and stretched at the predetermined position by the heater already maintaining the optimum cutting temperature. At this time, since the wire electrode is given a predetermined tension between the brake roller and the take-off roller, the wire electrode is pulled and cut instantaneously and reliably, and the cut portion of the wire electrode is always straight and tapered. Cut at

〔Example〕

Hereinafter, the present invention will be described with reference to one embodiment of the drawings. FIG. 1 shows a guide portion of a wire-cut electric discharge machine equipped with an automatic connection device. A wire electrode 1 is continuously supplied from a reel 2, moves between upper and lower guides 3 and 4, and faces a workpiece 5. To perform electrical discharge machining. Reference numeral 6 denotes a take-up roller, and reference numeral 7 denotes a brake roller. Under the control of both, the wire electrode 1 travels from top to bottom at a predetermined speed and tension. Reference numeral 8 denotes a claw that grips and sends the wire electrode 1, 9 denotes a heater for cutting, 10 denotes a pipe electrode that guides the wire electrode 1 through the inside, 11 denotes a claw that sends the pipe electrode 10, 12 denotes an energizing pin, and 13 denotes a vent. The roller guide 14 is a wire electrode discharge pipe.

When the previous processing is completed, the wire electrode 1 is cut by the contact of the heater 9. The cut wire electrode 1 is inserted into the pipe electrode 10 by the claw 8, and in the inserted state, is inserted into the start hole of the workpiece 5 that is controlled to be positioned next by the claw 11. Of course, this insertion can be performed while applying electric current to the pipe electrode 10 to discharge-process the start hole. The tip of the wire electrode 1 penetrating the workpiece 5 passes through the lower guide 4, passes through the vent roller guide 13, is taken up by the take-up roller 6, and is discharged through the discharge pipe 14. After the connection of the guide and the traveling movement of the wire electrode 1 is completed in this way, the wire cutting can be performed by performing relative machining feed of the machining shape by NC control to the workpiece 5 side.

The cutting of the wire electrode 1 by the heater 9 is important in that the tip of the wire electrode 1 is always cut in a straight and sharp state in order to facilitate the subsequent wire passing operation. FIG. 2 shows an embodiment of the cutting heater 9 in which 91 is Ni-C.
r, a heater coil made of a heating wire such as Fe-Cr-Al, a platinum wire, or the like, wound around a support pipe 92 made of heat-resistant, refractory material, alumina, or other ceramics. Numeral 93 denotes a thermistor which is arranged at a contact position with the wire electrode 1 in the pipe 92 to detect temperature. 94 is a dumet wire, and 95 is an insulating material. Although the heater power supply is not shown, the current of the coil 91 is controlled by the detection signal of the thermistor 93 so as to maintain the predetermined temperature constant. Normal wire electrode cutting temperature is about 600-900
The temperature change is controlled to about ± 5 to ± 10 ° C at about ° C. In this manner, the thermistor 93 is placed at the cutting position of the heater.
The wire electrode 1 can be cut straight without fail because the temperature is controlled so that the wire electrode is heated and stretched and then maintained at a precisely constant temperature suitable for cutting. FIG. 3 is a view for explaining a cutting state of the wire electrode 1. A predetermined tension is applied to the guided wire electrode 1, and a contact portion 1a is extended by sending a heater to contact the wire electrode 1. It is cut straight to taper.

According to the experiment, in the experiment when cutting the Bs electrode, the heater temperature wire diameter wire tension cutting time 700 ± 5 ℃ 0.2mmφ 1kg 1sec 700 ± 6 ℃ 0.3mmφ 1.8kg 1.5sec Could be cut exactly.

As described above, the heater is always controlled at a constant temperature. Normally, in wire cutting, there is splashing of machining fluid, etc., and the temperature change is large, but the heater temperature is kept constant by sensor temperature detection and temperature control. Since the heater is maintained at a predetermined temperature, regardless of the presence or absence of such a factor of temperature change, the heater is sent to the cutting position of the wire electrode and brought into contact with the heater so that the heater can be cut instantaneously and reliably. can do. In addition, it is possible to always cut straight and tapered.

In addition to a thermistor, a thermocouple, a temperature measuring resistor of platinum, copper, nickel, etc., an IC temperature sensor, and the like can be used as the temperature sensor for controlling the temperature of the heater. By locating the heater at the contact position, the temperature can be accurately detected, and the heater temperature can be accurately and constantly controlled. The temperature sensor may be provided outside the heater. As the touch heater member, a silicon carbide heating element, a molybdenum silicide heating element, an oxide, a ceramic heating element, and the like can be arbitrarily used in addition to the heating wire coil.

〔The invention's effect〕

Since the present invention is configured as described above, a heater accurately maintained at a predetermined temperature suitable for the material and wire diameter of the wire electrode at a predetermined position of the wire electrode in a predetermined tension applying state is provided. Since the contact can be made, there is an effect that the wire electrode can be easily and reliably cut at a predetermined position in a shorter time.

At this time, since a predetermined tension is applied to the wire electrode, the wire electrode is heated and stretched and pulled and cut at a predetermined position where the heater is in contact, so that the wire electrode is cut straight and tapered. It is possible to obtain effects such as easy connection and connection to the start hole of the body. In particular, a wire electrode having a relatively large diameter, which is used in accordance with the recent increase in the speed of wire-cut electric discharge machining, can be cut in the same manner, and the cutting operation can be performed more safely.

[Brief description of the drawings]

FIG. 1 is a structural view of an apparatus according to an embodiment of the present invention, FIG. 2 is an enlarged structural view of a part thereof, and FIG. 3 is an explanatory view of a cut state of a wire electrode. DESCRIPTION OF SYMBOLS 1 ... Wire electrode 2 ... Reel 34 ... Guide 5 ... Workpiece 6 ... Take-off roller 7 ... Brake roller 9 ... Cutting heater 91 ... Coil 92 ... Support pipe 93 ... Thermistor 94 ... … Jumet wire

Claims (3)

(57) [Claims] 1. A wire-cut electric discharge machine which discharges a workpiece by a wire electrode supplied from a reel and moved between a pair of guides at a predetermined tension and speed by a brake roller and a take-up roller. A heater for extending and cutting the applied wire electrode by heating, a temperature sensor provided in the heater to detect the temperature of the heater, and maintaining the temperature of the heater at a predetermined temperature by a detection signal of the temperature sensor. A temperature control power supply for controlling the temperature of the wire electrode, wherein the heater comes into contact with and separates from a predetermined position of the wire electrode under a predetermined tension on a wire electrode travel path between the brake roller and the workpiece. A wire-cut electric discharge machine characterized by being configured and arranged as possible. 2. The heater according to claim 1, wherein said heater is formed by winding a heater coil around a heat-resistant refractory material.
Item 10. The wire-cut electric discharge machine according to item 9. 3. A wire-cut electric discharge machine according to claim 1, wherein a temperature detection point of said temperature sensor is arranged at a predetermined position of said heater in contact with said wire electrode.