JPH06320339A - Sump wire electric discharge machine - Google Patents

Abstract

PURPOSE:To maintain a water level in a machining tank always in a position of proper range regardless of fluctuating a total amount of inflow water by providing a control device for opening a drain valve by receiving an upper limit position detection signal of the water level and closing a discharge valve by a lower limit position detection signal of this water level. CONSTITUTION:When a water level reaches an upper limit position, an upper limit position detecting float switch is turned on, and by an upper limit position detection signal of this switch, a motor 15 is forwardly rotated by a controller 22, to increase an opening of a valve unit 11 in a drain port 10 through a ball screw 14 and a ball nut 17. Thus by increasing a drain amount per minute from the discharge port 10, the water level of a machining tank 1 in a sump wire electric discharge machine is maintained at the upper limit or less. When the water level leads to an almost intermediate position between the upper/lower limit position detecting float switches, the motor 15 is reversely rotated to decrease the opening of the valve unit 11, and in this condition, normal electric discharge machining is performed. When the water level reaches a lower limit position, the motor 15 is reversely rotated to further decrease the opening of the valve unit 11, and the water level is maintained at the lower limit or more.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water reservoir wire electric discharge machine for filling a machining tank with water (machining liquid) to perform electric discharge machining on a workpiece in water.

[0002]

2. Description of the Related Art Conventionally, in a water reservoir wire electric discharge machining apparatus, the water level of a machining tank is such that a weir plate is vertically movable in an opening provided in a wall of the machining tank so that the water in the machining tank is removed from the upper edge of the dam plate. It is done by making it overflow. That is, the water level is maintained at a required height by adjusting the position of the dam plate up and down.

However, in the case of using the opening provided with such a dam plate, the water level must be adjusted manually, and it is not possible to appropriately cope with the case where workpieces having partially different thicknesses are continuously machined. In particular, it cannot handle the case of continuous automatic operation at night. Also, since there are two drainage points, a special structure is required for wastewater treatment.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a water-storing wire electric discharge machine which can always maintain the water level of a machining tank in an appropriate range according to the total amount of water flowing into the machining tank.

[0005]

[Means for Solving the Problems] A processing machine for electric discharge machining a workpiece in water stored in a processing tank. Provide water level adjustment means. The water level adjusting means opens the drain valve in response to the water level detection device that detects the water level upper limit position and the water level upper limit position (set value), the drain valve that opens and closes, and the water level upper limit position detection signal. A control device for closing the drain valve is provided.

It is preferable to have the following specific configuration. The drain valve should be adjustable in opening. In the drain valve, the contact surface between the valve body and the valve seat is a conical surface having an apex in the downflow direction, and the valve body is moved in the direction of the conical axis.

[0007]

The water level detecting device detects the upper limit position and the lower limit position of the water level and sends a detection signal to the control device. The control device opens the drain valve for a predetermined time set by the detection signal that the water level has reached the upper limit during electrical discharge machining, and similarly closes the drain valve for the predetermined time set by the detection signal that has reached the lower water level.

[0008] The controller may adjust the drainage port to an opening degree such that the amount of drainage per unit time is approximately equal to the total amount of water flowing into the processing tank during the period between the predetermined time zones. . The conical contact surfaces of the valve element and the valve seat, which have an apex in the downflow direction, facilitate the adjustment of the drainage amount.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a part of a machining tank 1 of a water reservoir wire electric discharge machine (hereinafter, simply referred to as a machining machine). Processing tank 1
Is placed on the table 2 and is movable relative to the upper wire guide 3 and the lower wire guide 4 in the orthogonal X and Y axis directions. The upper wire guide 3 is provided with an upper nozzle 5 at the tip, and is attached to the tip of a Z-axis unit 6 which is movable in the vertical (Z-axis) direction with respect to the upper column of the processing machine. The lower wire guide 4 is fixedly attached to the tip of the lower arm 7 of the processing machine, and is arranged so as to face the upper wire guide 3. Reference numeral 8 is a work and is arranged on the table 9.

The processing tank 1 has a drain port 10 on the bottom surface on one side. The drainage port 10 includes a valve body 11 and a valve seat 12 that receives the valve body 11, and a contact surface between the valve body 11 and the valve seat 12 is a conical surface having an apex at the bottom. A shaft 13 is vertically attached to the valve body 11 in conformity with the conical axis, and an upper end portion of the shaft 13 is formed with a ball screw 14.

A motor 15 (step motor) is attached to one side wall of the processing tank 1, and this one side wall is extended to form a stay 16 and the ball nut 1
7 is rotatably attached to the shaft. The ball nut 17 is
The output shaft 18 of the motor 15 is connected to the belt 19 and is driven by the motor 15. The ball screw 14 of the shaft 13 is screwed into the ball nut 17.

On the other hand, an upper limit float switch 20a and a lower limit float switch 20b are vertically attached to the Z-axis unit 6 so as to move together with the upper wire guide 3 as the Z-axis unit 6 moves up and down. It has become. As shown in FIG. 2, the float switch 20a defines the upper limit water level, and the float switch 20b is disposed above the tip of the nozzle 5 to define the lower limit water level. Reference numeral 21 indicates the position of the electrode pin in the upper wire guide 3.

The float switch 20 (a, b) is turned on.
It is connected to the controller 22 with a / OFF switch, and transmits an ON signal to the controller 22 when the water level of the processing tank 1 reaches the upper limit position and the lower limit position, and is OFF in other states. Float switch 20 (a,
b) and the controller 22 constitute a water level detecting device.

The controller 22 has a function capable of driving the motor 15 in the normal rotation / stop / reverse rotation and setting the respective driving time (rotation amount). Further, the forward rotation of the motor 15 raises the valve body 11. The drainage port 10 is opened, and it descends in the reverse direction. That is, the water level detecting device, the motor 15 and the drainage port 10 capable of adjusting the opening degree constitute a water level adjusting means.

At the start of electric discharge machining, water is stored in the machining tank 1. The water level is set in the middle of the float switch 20 (a, b), that is, between the upper limit water level and the lower limit water level. The size of the processing tank 1 is 50 x 50 x 20 (c
m), the total amount of water flowing into the processing tank 1 per unit time is 10
00 cc / min, and the space between the float switches 20 (a, b) is 50 mm in vertical distance.

The controller 22 is set with respective times of forward rotation, stop, and reverse rotation. Regarding forward / reverse rotation,
The opening amount a, the opening amount b, and the opening amount c are set as the rotation amount of the motor that substantially moves the valve body 11 up and down to determine the opening amount of the drainage port 10. As for the opening degree a, the amount of rise of the valve body 11 from the position where the drain port 10 is completely closed is 10 mm, and the amount of drainage at this time is approximately equal to the total amount of inflow water 1000
cc / min. The opening degree b is 5
The amount of drainage at this time is 0 mm and is 3000 cc / min. The opening degree c is the valve body 11 when the drainage port 10 is closed.
Is 0 mm and the drainage is 0 cc / min. In addition,
Since the valve body 11 and the valve seat 12 are in contact with each other by the conical surface, the drainage amount does not accurately change from 1000 cc to 3000 cc when the amount of rise of the valve body 11 changes from 10 mm to 30 mm. .

Regarding stop, stop time a, stop time b
And the stop time c is set. The stop time a is a time when the forward rotation is stopped, and is set in relation to the opening a, the interval between the float switches (a, b) and the size of the processing tank 1, and is 3 minutes. The stop time b is determined in the same manner as the stop time a, but is 6 minutes. The stop time c is the time until one of the float switches (a, b) is turned on.

When electric discharge machining is started in the state of FIG. 2 (a), the water level in the machining tank 1 is between the upper limit A and the lower limit A, and neither float switch 20 (a, b) operates. The valve body 11 of the drainage port 10 is maintained at the opening a (10 mm). That is, jets are discharged from the nozzles of the upper wire guide 3 and the lower wire guide 4 into the processing tank 1, and 1000 cc / min of water is supplied as the total amount of water flowing in, but approximately the same amount of water is discharged to the drain port 10. Since it flows out of the tank, the water level in the processing tank 1 does not actually change. Therefore, there is no possibility that the water level exceeds the upper limit of A to cause an electric leakage accident, or the upper limit of A exceeds the lower limit to expose the tip of the nozzle 5 and the sludge is not removed properly. You can

The water level in the processing tank 1 is such that when the processing machine repairs a wire breakage or moves to a new processing position during the continuous processing operation, the wire is automatically connected or the water pressure supplied to the nozzle changes. It changes due to changes in the total amount of water that flows in during roughing and finishing. When the water level reaches the A upper limit position, the float switch 20a turns O
N operation is performed, and the controller 22 receives the upper limit position detection signal.
Rotates the motor 15 in the forward direction and sets the valve body 11 to the opening b (30 mm) through the ball screw 14 and the ball nut 17, and 3
Stop for a minute (stop time a). Therefore, the water level is 8m / min.
It falls from m (when the total amount of water around 1000 cc is flowing in) to 12 mm per minute (when the water supply is interrupted) to prevent the water level from exceeding the upper limit A. In this case, the water level drops quickly and accidents such as electric leakage can be reliably prevented.

When the water level reaches an almost intermediate position of the float switch 20 (a, b), the float switch 20a
The operation that accompanies the ON operation ended, and then
The motor 15 is reversely rotated, the valve body 11 is lowered, and the drainage port 10 is stopped at the position of the opening a, and the stop time c is reached. This state is a normal electric discharge machining state.

When the water level reaches the A lower limit position, the float switch 20b is turned on, and the controller 22 reverses the motor 15 in response to the lower limit position detection signal to open the valve body 11 via the ball screw 14 and the ball nut 17. c (0
mm) and stop for 6 minutes (stop time b). For this reason,
The water level rises in the range of 4 mm / min (when the total supply amount around 1000 cc is maintained) to 0 mm (when the water supply is interrupted) to prevent the water level from exceeding the lower limit A.

When the stop time b elapses, the operation associated with the float switch 20b being turned on is terminated, and then the motor 15 is normally rotated to raise the valve body 11,
It is stopped (stop time c) at the place where the drainage port 10 is opened a. This state is a normal electric discharge machining state. Normally, when the stop time b has elapsed, the water level of the processing tank 1 has reached almost the middle position of the float switch 20 (a, b), and the above operation is executed, but Since the float switch 20b is still in the ON state when the supply of water is stopped, the drain port 10 is maintained in the closed state.

In the above operation, even if the thickness (vertical dimension) of the work changes as shown in FIG. 2B, the Z-axis unit 6 moves up and down with the change and the float switch 20.
(A, b) is also moved to set the B upper limit and the B lower limit, and the same operation is performed. However, when the Z-axis unit 6 is vertically moved rapidly, its displacement should be kept within the interval of the float switch 20 (a, b), and the displacement of the float switch 20 (a) should be increased rapidly. , B)
If the interval is exceeded, it is necessary to increase the total amount of water flowing into the processing tank 1 by a separate means along with the vertical movement.

The above is an embodiment, and the present invention is not limited to the illustrated concrete configuration. The water level detection device is not limited to the float switch 20 (a, b), and may be a detection device based on another detection principle. 2 float switches
In some cases, more than one piece may be placed to make finer water level adjustments. The opening and closing of the valve element 11 can be performed not by a motor but by an air actuator that can adjust the step operation and the step amount.

[0025]

INDUSTRIAL APPLICABILITY In a water sump wire electric discharge machine, unattended automatic operation for a long time becomes possible. There is only one drainage point from the processing tank, so no special wastewater treatment is required.

[Brief description of drawings]

FIG. 1 is a front view showing the whole mechanically.

FIG. 2 is a front view showing (a) and (b) in parallel during processing.

[Explanation of symbols]

 1 Processing Tank 2 Table 3 Upper Wire Guide 4 Lower Wire Guide 5 Nozzle 6 Z Axis Unit 7 Lower Arm 8 Work 9 Mounting Platform 10 Drainage Port 11 Valve Disc 12 Valve Seat 13 Shaft 14 Ball Screw 15 Motor 16 Stay 17 Ball Screw 18 Output Axis 19 Belt 20 (a, b) Float switch 21 Electrode pin

Claims (3)

[Claims] 1. A machine for electric discharge machining a workpiece in water stored in a machining tank, the machine comprising water level adjusting means, wherein the water level adjusting means detects the upper limit position and the lower limit position of the water surface in the machining tank. It has a device and a drain valve that opens and closes on the valve seat, and can output a drainage port that can make the amount of drainage per unit time larger than the total amount of water that flows into the machining tank per unit time and the upper limit position detection signal of the water level during electrical discharge machining. A water-storing wire electric discharge machine, comprising a control device which receives and opens the drain valve and also closes the drain valve by a water level lower limit position detection signal. 2. The drain valve is capable of adjusting the opening of the drain port, and the control device opens the drain valve for a predetermined time set by receiving a signal for detecting the upper limit position of the water level, and also the lower limit of the water level. The drainage valve is closed by the position detection signal for a set period of time, and during these time periods, the amount of drainage per unit time is adjusted to be approximately equal to the total amount of water flowing into the processing tank per unit time. The water reservoir wire electric discharge machine according to claim 1, wherein 3. The drainage port is characterized in that the contact surface between the valve body and the valve seat is a conical surface having an apex in the downflow direction, and the valve body is moved in the direction of the axis of the conical shape. The water discharge wire electric discharge machine according to claim 2.