JPS6157133B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for setting a wire electrode in an electric discharge machining apparatus, and more specifically, the present invention relates to a method for setting a wire electrode in an electric discharge machining apparatus. easy to,
The present invention relates to a method for setting a wire electrode in an electric discharge machining apparatus, which is suitable for automatic insertion.

In a wire cut electric discharge machine, when reconnecting the wire electrode after it has been cut for some reason, or when machining another workpiece after completing the required machining,
Cutting and connecting wire electrodes is required. In order to automate these tasks and perform them efficiently,
It is necessary to devise a method so that the cut end of the wire electrode is inserted through the guide roller and the machining start hole of the workpiece. In particular, when the diameter of the wire electrode is small, the cut end tends to sway due to external forces such as a breeze, and simply feeding out the wire electrode does not ensure that the tip is guided as desired. It is extremely difficult to insert it into a hole, a machining start hole, etc. of a workpiece. For this reason, in the past, the wire electrode was straightened by passing it through a pinch roller, and then the wire electrode was cut, and the cut end was inserted into a guide hole, a machining start hole, etc. of the workpiece. When inserting the wire electrode, a method is used in which water is jetted along the direction in which the wire electrode is inserted, and the jet water is used to insert the wire electrode into a desired hole, groove, etc. The above-mentioned conventional method is effective when the wire diameter of the wire electrode is thick to a certain extent, but when using an ultra-fine wire electrode with a wire diameter of about 0.1 mmφ or less, for example, the jet water may cause the wire to The linearity of the wire is no longer maintained, making it extremely difficult to insert the wire electrode.

Therefore, it is an object of the present invention to provide a wire electrode set for an electric discharge machining apparatus, in which the cut end of a wire electrode having a small wire diameter can be reliably inserted into a desired guide hole, a machining start hole of a workpiece, etc. The purpose is to provide a method.

The features of the present invention for achieving the above object include the above-mentioned wire electrode setting method in an electric discharge machining apparatus for automatically inserting a wire electrode into a wire guide or a hole, groove, or other inserted part of a workpiece. When feeding the insertion end of the wire electrode downward toward the required inserted part in order to set the wire electrode, the above-mentioned method is used to maintain the verticality of the insertion end of the wire electrode being fed. The point is to pour a liquid onto the wire electrode of sufficient viscosity to adhere to the extended portion of the wire electrode so as to act as a weight.

In the following, the method of the invention will be explained in detail with reference to the illustrated embodiments.

FIG. 1 schematically shows a mechanical diagram of an embodiment of a wire setting device 1 for a wire-cut electrical discharge machining machine, which is capable of automatically inserting a wire electrode by the method of the present invention. The wire setting device 1 is a device for cutting the wire electrode 3 paid out from the wire bobbin 2 as desired, and automatically inserting it into the workpiece 4 and setting it. The wire extends downward via guide rollers 5 and 6, is inserted into the machining start hole 4a of the workpiece 4, and is taken off by a belt-type wire take-off device 8 driven by a motor 7. Here, the symbols 9 and 10 indicate:
These wire guides 9,
10 is provided in housings 11 and 12 for supplying machining fluid. Machining fluid supplied from a machining fluid tank (not shown) is once supplied into the housings 11 and 12 as indicated by the arrow X in the center of FIG. 1, and then supplied from each housing 11 and 12 to the discharge machining gap. Electric discharge machining pulses from a power source (not shown) are applied to the electric discharge machining gap 16 via the current-carrying rollers 13, 14, 15 and the workpiece 4.

The wire setting device 1 has first to third roller pairs 17, 18, and 19, and each of these roller pairs includes rollers 17a, 17b, and roller 18.
a, 18b and rollers 19a, 19b. The rollers 17a, 18a, and 19a are each made of a conductive material and are rotatably supported by a frame (not shown), and the rollers 18a, 19a are rotationally driven in the directions of arrows A and B by motors 20 and 21, respectively. On the other hand, rollers 17b, 18b, 19
b is rotatably supported by movable support shafts 22, 23, 24, and these movable support shafts 22, 2
Each roller 17b,
18b, 19b correspond to rollers 17a, 18
A, 19a can be pressed into contact with or separated from each other. When the rollers 17a, 18a, 19a are in pressure contact with the corresponding rollers 17b, 18b, 19b, the wire electrode 3 is pressed by these rollers with a moderate force from both sides, causing friction with the circumferential surface of each roller. The wire electrodes can be fed downward by rotation of the rollers 18a and 19a.

A weight 28 is connected to a pulley 29 between rollers 5 and 6.
It is suspended from the wire electrode 3 via the wire electrode 3, thereby applying an upward tensile force to the wire electrode 3.

In order to heat the wire electrode 3 under the tension applied by the weight 28 and remove the curl of the wire electrode 3, rollers 17a and 19a are used.
An energization heating circuit 30 is provided between the two. The energization heating circuit 30 includes power supply brushes 31 and 32 that are in electrical contact with the rollers 17a and 19a,
The power supply brush 32 is connected to the negative electrode of a power source 33. On the other hand, the power supply brush 31 is connected to the positive terminal of a power source 33 via two current adjustment variable resistors 34 and 35 and a switch 36. Therefore, when the switch 36 is closed, a heating current flows through the wire electrode 3 located between the rollers 17a and 19a, heating this portion of the wire electrode. In this case, the value of the variable resistor 34 is adjusted so as to generate enough heat to straighten the wire electrode. This current value varies depending on the wire diameter of the wire electrode 3, but
For example, in the case of 0.15φ, it is preferably 5 to 8A, and in the case of 0.2φ, it is preferably 7 to 10A.

Further, in order to form a narrow diameter part in a part of the wire electrode 3 between the second roller pair 18 and the third roller pair 19 and to supply a heating current to melt this narrow diameter part, a roller is installed. A power supply brush 38 is provided which contacts the power supply 18a, and the power supply brush 38 is connected to the connection point between the variable resistors 34 and 35 via a switch 37. When the switch 37 is closed, a heating current regulated by the variable resistor 35 flows through the wire electrode between the roller pair 18, 19, and the wire electrode 3 is fused as will be described later.

As will be described in detail later, when the fused wire electrode 3 is fed downward by the pair of rollers 18, the wire electrode 3 descends while maintaining its straightness and perpendicularity, and the wire guides 9, 10 and processing Starting hole 4
A lubricating device 40 is provided below the roller pair 19 so that the roller pair 19 can be easily inserted through the roller pair 19. The lubrication device 40 consists of an oil tank 41 containing a relatively high viscosity oil, such as "Bactera" oil, and a lubrication nozzle 43 equipped with a lubrication valve 42. By opening the lubrication valve 42, Oil can be poured onto the wire electrode 3 from the tip opening 43a of the oil nozzle 43. Oil nozzle 4
3, the oil applied to the wire electrode 3 falls downward along the wire electrode 3, but the falling speed is relatively slow due to the viscosity of the oil. The oil adhering to the wire electrode 3 becomes an oil picker 44 as shown in FIG. 2, for example, and is transmitted through the wire electrode 3 and pulled down.

In this way, relatively high viscosity oil adheres to the thin wire electrodes 3, for example as oil picks, so these oil picks act as a weight, and the wire electrode 3 absorbs the tensile force caused by these oil picks. is pulled straight downward. Therefore, the wire electrode 3 is moved by the roller pair 18.
Since the wire electrode 3 can maintain its straightness and verticality while being fed downward,
Even if there is a disturbance such as a breeze, the wire guides 9 and 10
And it can be inserted into the processing start hole 4a reliably.

Note that the state of the oil that travels through the wire electrode 3 and falls may not always be oil-thinning depending on the viscosity of the oil, the oiling method, etc.; Even if the wire electrode 3 falls slowly, any form may be used as long as it can serve as a weight to maintain the linearity and perpendicularity of the wire electrode 3. It has been confirmed through experiments that oil must have a viscosity at least equal to or higher than the viscosity of Class 3 kerosene in order to achieve this purpose.

Next, the automatic wire setting device 1 shown in FIG.
The operation will be explained.

When the wire electrodes are not cut or set, the switches 36 and 37 are in a closed state, each electromagnetic actuator 25, 26, and 27 is deenergized, and each roller 17b, 18b, and 19b is in a corresponding roller It is in a state separated from 17a, 18a, and 19a. Therefore, the wire electrode 3 is taken off by the belt-type wire take-off device 8 while being applied with the attractive force by the weight 28, and the required wire cut electric discharge machining can be performed in the electric discharge machining gap 16.

To explain how to set the wire electrode 3, first, the motor 7 is stopped, and the switch 36 is closed while the wire electrode 3 stops running.

In this case, the actuators 25 and 27 are energized and the rollers 17a and 19a are both in contact with the wire electrode 3, so the roller 17a is in contact with the wire electrode 3.
A heating current for straightening the wire flows through the wire electrode between a and 19a, heating the wire electrode 3, and at the same time, the lower part of the wire electrode 3 is fixed by a belt-type wire pulling device 8. Tension is applied to the wire electrode 3 by the weight 28. As a result, the wire electrode 3 is heated and pulled in its axial direction at the same time, so that it is stretched straight, and the curls caused when it was wound around the bobbin or when it passed through the rollers 5 and 6 are removed. Good removal.

After the wire electrode 3 has been straightened as described above, the switch 36 is opened and the electromagnetic actuator 26 is also energized to press the roller 18b against the corresponding roller 18a. Thereafter, the switch 37 is opened, a heating current is applied to the wire electrode 3 located between the roller pair 18 and 19, and the motor 21 is activated.With one of the wire electrodes 3 fixed by the roller pair 18, the roller 19a is moved in the direction indicated by the arrow. Rotate in direction B. Therefore, the wire electrode between the pair of rollers 18 and 19 is heated and stretched in the axial direction, and the wire electrode 3 in this portion is as shown in FIG.
As shown in FIG. 2, it is constricted and becomes thin, and a narrow diameter portion 3a is formed in a part of the constriction. This narrow diameter portion forming operation by the roller pair 19 can be performed by, for example, driving the motor 21 for a predetermined fixed period of time according to the wire diameter using a timer to form the desired narrow diameter portion of the wire without cutting the wire electrode 3. It can be formed on the electrode 3.

When the wire electrode 3 reaches the state shown in FIG. When the heating current is continued to be supplied through the thin diameter portion 3a, since the electrical resistance of the narrow diameter portion 3a is the highest, the amount of heat generated in this portion increases, and eventually the narrow diameter portion 3a is fused. In this case, as described above, since no tensile force is applied to the wire electrode 3, the fused end portion thereof will be formed into a substantially hemispherical shape as shown in FIG. 3b.

After cutting the wire electrode 3 as described above,
The actuator 27 is deenergized to separate the roller 19b from the roller 19a, and then the motor 7
is driven, and the cut lower end of the wire electrode is removed from inside the electrical discharge machining apparatus by the belt-type wire take-off device 8.

Next, the actuator 25 is deenergized to stop the pair of rollers 17 from holding the wire electrode 3, and the motor 20 rotates the roller 18a in the direction of the arrow, thereby drawing out the wire electrode 3 downward. At this time, the lubrication valve 42 is opened, the lubrication device 40 lubricates the wire electrode 3 with oil as described above, and the wire electrode 3 is pulled straight downward by the oil.

In this way, the vicinity of the tip of the wire electrode 3 is in a vertical state due to the oil, and the fusing end is tapered, so that the upper cut part is sent downward by the pair of rollers 18. In this case, it is possible to easily reach the guide 9 and the through hole 4a, and since the tip thereof is approximately hemispherical, the side wall surface of the guide 9 and the inner circumference of the through hole 4a can be easily reached. The tip does not stick to the surface and can pass through the guides 9, 10 and the through hole 4a extremely smoothly. In this way, the wire electrode 3 can pass through the guide 9, the processing start hole 4a, and the guide 10 via the current-carrying rollers 13 and 14, and reach the belt-type wire take-off device 8 without any difficulty. At this time, the belt type wire pulling device 8 is driven by the motor 7, and the wire electrode 3 is pulled downward.

In the apparatus shown in FIG. 1, the actuators 25, 26, 27, motors 7, 20, 21, and switches 36, 37 may of course be operated manually by the operator as described above. about,
This may be automatically performed by a sequence circuit including the above-mentioned timer circuit.

According to the method of the present invention, since the verticality of the wire electrode is maintained by pouring a liquid of a required viscosity into the wire electrode, automatic insertion of the wire electrode can be reliably performed with a simple device. Since it can be easily applied to conventional electrical discharge machining equipment, it is possible to realize an economical and high-performance wire electrode setting device for electrical discharge machining equipment.

[Brief explanation of the drawing]

FIG. 1 is a schematic mechanical diagram showing an embodiment of a wire setting device according to the method of the present invention, and FIG. 2 is an enlarged perspective view of main parts showing the state of the wire electrode when the wire electrode is lubricated after cutting. Fig. 3a is an enlarged detailed view of the wire electrode when a narrow diameter part is formed in the wire electrode, and Fig. 3b is an enlarged view showing the state after the narrow diameter part of the wire electrode shown in Fig. 3a is fused. It is a detailed view. DESCRIPTION OF SYMBOLS 1... Automatic wire setting device, 3... Wire electrode, 4... Workpiece, 4a... Machining start hole, 9,
10... wire guide, 17... first roller pair,
18...Second roller pair, 19...Third roller pair,
20, 21... Motor, 25, 26, 27... Electromagnetic actuator, 30... Current heating circuit, 3
1, 32, 33...power supply brush, 33...power supply,
34, 35...Variable resistor, 36, 37...Switch, 40...Lubrication device, 41...Oil tank, 4
2...Lubrication valve, 43...Lubrication nozzle.

Claims (1)

[Claims] 1. In a wire electrode setting method in an electric discharge machining apparatus for automatically inserting a wire electrode into a wire guide and/or a hole, groove, or other inserted part of a workpiece, the wire electrode is When the insertion end portion is fed downward toward a required inserted portion, it acts as a weight on the feeding portion of the wire electrode in order to maintain the verticality of the insertion end portion of the wire electrode being fed. 1. A method for setting a wire electrode in an electrical discharge machining apparatus, comprising pouring a liquid having a sufficient viscosity to the wire electrode so that the wire electrode adheres to the wire electrode.