JPH0790425B2 - Automatic wire feeder for wire electric discharge machine - Google Patents

Description

TECHNICAL FIELD The present invention relates to an automatic wire feeder for a wire electric discharge machine.

[Prior Art] FIG. 7 schematically shows a processing state of a conventional apparatus disclosed in, for example, Japanese Patent Laid-Open No. 62-120920. (1) in the figure
Is a wire electrode, (2) is a workpiece, (3) is a workpiece (2)
It is a machining start hole through which the wire electrode (1) is bored, and the workpiece (2) is driven in the X and Y directions with respect to the wire electrode (1) by another driving device (not shown).
Reference numeral (4) is a pipe guide, which is provided with a die guide (5) for inserting the wire electrode (1) therein and for guiding the wire electrode (1) in the processing area at the tip. (6) is a lower die guide that guides the wire electrode (1), and is attached to the upper end of the lower guide (7). Reference numeral (8) is an electric power supply for supplying processing energy from the power supply (9) to the wire electrode (1). (10) is a fixed reference block for positioning the pipe guide (4), (11) is a movable block for positioning the pipe guide (4) by the pressing force of a spring, (1
2) is the lower side power supply attached to the lower guide (7). (13) and (14) are wire electrodes (1) and workpieces (2)
The upper and lower nozzles for ejecting the machining fluid (15) to the electric discharge machining area of and, and (16) are bearings for guiding the pipe guide (4). Reference numerals (17) and (18) denote working fluid inlets for supplying the working fluid (15) to the nozzles (13) and (14). (19) is a pinch roller which feeds the wire electrode (1) through the pipe guide (4) to the lower guide (7), which is attached to the upper part of the pipe guide (4) and is driven by the drive motor (20). Drive 1) downward. (21) is a pipe guide (4) with lead screw (22) and slider (23)
By the motor, which moves upward and downward along the guide rod (24), the vertical movement of the pipe guide (4) facilitates the insertion of the wire into the lower guide (7) of the wire electrode (1). (25) is a cutter for cutting the wire electrode (1), which cuts the wire electrode (1) after the pipe guide (4) is lifted to the upper part of the cutter (25) by the motor (21). Reference numeral (26) is a roller for pulling and driving the wire electrode (1) supplied to the lower guide (7), and a roller (2 on which a belt (27) is stretched.
8) and the motor (29) connected to this roller (28)
Wire electrode (1) to the wire electrode collection box (30)
It is structured to send out. Further, (31) is a detection device for detecting contact between the pipe guide (4) and the workpiece (2),
Reference numeral (32) is a control device, and (32A) is a wire feed control means attached to the control device (32), which receives a signal from the detection device (31) and is a wire feed drive motor (2).
0) control. (32B) is a table position control means attached to the control device (32), which operates a table drive mechanism (not shown) to move the XY cross table (see FIG. 1) to move the wire electrode (1) and the machining start hole. Control the relative motion of (3).

FIG. 8 shows the operation of feeding the wire electrode (1) of the above-mentioned conventional device to the lower guide (7). The pipe guide (4) is driven by the drive motor (21) to form the machining start hole (3). To the end face of the workpiece (2) and the conduction between the pipe guide (4) and the workpiece (2) is detected by the contact detection circuit (3
The control device (32) stops the motor (21) for driving the pipe guide (4) by the detection signal of 1),
At the same time, the wire feed motor (20) is driven to rotate the pinch roller (19) to feed the wire electrode (1). The wire electrode (1) sequentially passes through the processing start hole (3) and the lower guide (7), is caught by the roller (26), is carried by the belt (27), and is collected in the collecting box (30).

FIG. 9 shows the operation when cutting the wire electrode (1) in the above conventional device. The pipe guide (4) is pulled up to the upper part of the cutter (25), and the cutter (2
5) is driven in the direction of the arrow in the figure by another driving source (not shown) to cut the wire electrode (1).

In the conventional device configured as described above, especially when automatically supplying a wire to a small-diameter machining start hole (for example, wire electrode diameter 0.2 mm, machining start hole diameter 0.5 mm), the machining start hole of the workpiece is shown in FIG. When the wire electrode (1) is opened by being displaced from a predetermined position as shown in Fig. 11 or the tip of the wire electrode (1) cut by the cutter (25) is wrapped around the wire electrode as shown in Fig. 11, the pipe guide If it deviates from the center line of (4), wire electrode (1) in any case
Since the tip of the wire electrode is displaced from the machining start hole (3) and abuts on the periphery of the machining start hole (3) on the surface of the workpiece (2), the tip of the wire electrode (1) is inserted into the machining start hole (3). Therefore, the automatic wire supply operation is disabled. Such a state is detected by the detection device (31) and notified to the control device (32). When the detection device (31) detects the contact between the wire electrode (1) and the workpiece (2), the control device (32) immediately stops the wire automatic supply operation by the wire feeding control means (32A), Then, after the table position control means (32B) controls the table driving mechanism of the XY cross table (not shown) to move the wire electrode position, the wire electrode inserting operation is tried again. This is repeated until the wire electrode insertion point is encountered.

[Problems to be Solved by the Invention] However, when the contact between the wire electrode (1) and the workpiece (2) is detected, the wire automatic supply operation is immediately stopped, the wire electrode position is moved, and then the wire is again moved. In the conventional device that tries the electrode insertion operation, the tip of the wire electrode (1) immediately after the wire automatic supply operation is stopped by detecting the contact between the wire electrode (1) and the workpiece (2) Since the wire electrode (1) is in a straight line and the tip of the wire electrode (1) merely touches the surface of the workpiece (2), the wire electrode (1) jumps up when the wire electrode position is moved thereafter, and is in a non-contact state. Occurs. In such a case, the detection device (31) detects that the wire electrode (1) and the workpiece (2) are not in contact with each other and informs the wire feed control means (32A) of the wire feed control means. (3
2A) continues the automatic wire feeding operation. For this reason, the tip of the wire electrode (1) protrudes more than necessary and is largely bent, and the tip of the wire electrode (1) is directed in a direction along the surface of the workpiece (2) in an arc shape, and the machining is started. The insertion into the hole (3) becomes impossible, and the automatic wire supply operation becomes impossible.

As described above, in the conventional apparatus, the automatic wire feeding operation is disabled due to the large deflection of the tip portion of the wire electrode due to the wire automatic feeding operation accompanied by the wire electrode jumping up when the wire electrode position is moved. Such a problem is more likely to occur as the diameter of the wire electrode and the diameter of the processing start hole are smaller, and the success rate of the automatic wire feeding operation is significantly reduced.

In view of the above points, the present invention can prevent the wire electrode from jumping up when the wire electrode position is moved, can reliably insert the tip of the wire electrode into the processing start hole, and in the prior art, the wire automatic supply operation can be performed. It is an object of the present invention to provide an automatic wire feeder for a wire electric discharge machine that can make the automatic wire feeding operation practical even with a machining start hole of φ1 mm or less, which has not been put into practical use because of its extremely low success rate.

[Means for Solving the Problems] An automatic wire feeder for a wire electric discharge machine according to the present invention is a wire feeding mechanism for feeding a wire electrode to a work side, and whether the fed wire electrode comes into contact with a work piece. When the contact between the wire electrode and the workpiece is detected by the electrode contact detecting means for detecting whether or not the wire contact is detected by the electrode contact detecting means, the wire feeding is stopped so that the tip portion of the wire electrode is bent by a predetermined amount. After the stop, when the electrode contact detection means detects non-contact between the wire electrode and the workpiece, the wire feeding control means for controlling the wire feeding mechanism so as to continue the wire feeding, and the tip of the wire electrode has a predetermined amount. When the wire feeding is stopped in the bent state, the table drive mechanism that moves the XY cross table is operated to move the XY cross table in multiple directions within the specified range, and In which the non-contact between the wire electrode workpiece and a table position control means for controlling the table driving mechanism so as to stop the movement of the XY cross table when detected by the electrode contact detection means during.

[Operation] In the present invention, the wire electrode is sent toward the workpiece on the XY cross table by the wire feeding mechanism.
When the fed wire electrode comes into contact with the workpiece without being inserted into the machining start hole, the electrode contact detection means detects this contact and informs the wire feed control means and the table position control means that the contact has been detected. With the wire feeding control means,
When it is notified from the electrode contact detection means that the wire electrode has come into contact with the workpiece, the wire feeding mechanism is controlled to stop the wire feeding so that the tip portion of the wire electrode is bent by a predetermined amount, The spring force of the wire electrode due to this deflection is made to act on the workpiece side, and the table position control means is informed that the wire feeding has been stopped.
Further, in the table position control means, when the wire feeding control means is notified that the wire feeding has been stopped, the table driving mechanism is controlled to move the XY cross table in multiple directions within a predetermined range. When the tip of the wire electrode is located in the machining start hole due to the relative movement between the wire electrode and the machining start hole due to the movement of the XY cross table in multiple directions, the tip part of the wire electrode is unconstrained and its energy is stored. The spring force stretches by the amount of the flexure, and the tip is inserted into the machining start hole. When the wire electrode and the workpiece become non-contact due to the insertion of the tip of the wire electrode into the machining start hole, the electrode contact detection means detects this non-contact, and the fact that the non-contact is detected is detected by the table position control means and the wire. Notify the feed control means. In the table position control means, when the electrode contact detection means notifies that the wire electrode is not in contact with the workpiece, the table drive mechanism is controlled to control the XY position.
Stop moving the cross table. Further, the wire feeding control means controls the wire feeding mechanism to continue the wire feeding of the wire electrode when the electrode contact detecting means notifies that the wire electrode and the workpiece are in the non-contact state. This completes the insertion of the wire electrode into the processing start hole.

As described above, when the wire electrode comes into contact with the workpiece without being inserted into the machining start hole, the wire feeding is stopped so that the tip portion of the wire electrode is bent by a predetermined amount, and the wire electrode By allowing the spring force to act on the workpiece side and moving the XY cross table in multiple directions within a specified range, it is possible to prevent the wire electrode from jumping up when the wire electrode position is moved. The insertion of the tip into the processing start hole can be ensured.

[Embodiment] FIG. 1 is a configuration diagram showing an embodiment of the present invention, and FIG. 2 is a circuit diagram showing an electrode contact detection device. In the figure, the same or corresponding parts as those of the conventional example are designated by the same reference numerals and the description thereof will be omitted.

In FIG. 1, (19) is a wire feed roller, (20) is a wire feed drive motor, and (31) is an electrode contact detection for detecting whether or not the wire electrode (1) is in contact with the workpiece (2). It is a device. The electrode contact detector (31), as shown in FIG. 2, the wire electrode (1) and the electrode voltage E _O and compare power from the workpiece applied to have a DC power source (2) (37) (38 ) Is compared with the comparison voltage E _C from the comparator (39), and the wire electrode (1) comes into contact with the workpiece (2) and the inter-electrode voltage E _O decreases and becomes less than the comparison voltage E _C. , Comparator (3
It is configured so that the contact detection signal can be obtained from 9). The wire electrode (1) is electrically connected to the electrode contact detection device (31) through the power feeding die (8) and the pipe guide (4). Reference numeral (32a) is a wire feed control means attached to the control device (32), which receives a signal from the electrode contact detection means (31) and controls a wire feed drive motor (20) which is a wire feed mechanism. Reference numeral (32b) is a table position control means attached to the control device (32), which operates the X-axis drive motor (35) and the Y-axis drive motor (36) to move the XY cross table (34) to move the wire electrode. The relative movement of (1) and the processing start hole (3) is controlled. (32c) is a wire cutting / supply control means attached to the control device (32), which is an electrode contact detection means (31).
The drive motor (20), the motor (21), and the cutter (25) are controlled by receiving the signal of (1), and a counter for counting the number of times the output signal of the electrode contact detection device (31) is output is built in.

Next, the operation of this embodiment will be described based on FIGS. 3 to 6 and referring to FIG. FIG. 3 is a flow chart showing the procedure of wire feeding control, FIGS. 4 (a) to 4 (d) are explanatory diagrams showing examples of the state and movement of the wire electrode, and FIGS. 5 (a) to (c) are Explanatory drawing which shows an example of the locus | trajectory of a relative movement of a wire electrode and a workpiece, respectively.
(A), (b) is explanatory drawing which shows an example of the state and movement of another wire electrode, respectively.

In FIG. 1, the wire insertion operation is performed by first driving a driving motor (2) that drives a pinch roller (19) which is a wire feeding mechanism.
0) is rotated (step 40), and the wire electrode (1) is fed toward the workpiece (2) to start wire feeding (step 41). The wire electrode (1) moves in the direction of the workpiece (2), the tip of the wire electrode (1) does not enter the machining start hole (3) of the workpiece (2), and Upon contact with the upper surface, the electrode contact detection device (31) detects the contact, and an output signal for notifying the contact between the wire electrode (1) and the workpiece (2) is output (step 42), and the wire feed control means ( 32a). In the wire feeding control means (32a), the delay means controls the rotation of the drive motor (20) to stop after a certain period of time to stop the wire feeding of the wire electrode (1) (steps 43, 4).
Four). FIG. 4 (a) shows a state in which feeding of the wire electrode (1) is stopped, and a slight amount of deflection is generated in the wire electrode (1) due to a lapse of a fixed time until the wire feeding is stopped, that is, a delay time. It is present and it is necessary to set an appropriate amount of deflection in order to ensure the insertion operation of the wire electrode (1) described below. According to an experiment conducted by the present inventor, it has been found that the optimum amount of deflection is about 0.5 to 1.0 mm when the gap between the pipe guide (4) and the workpiece (2) is 8 mm.

Next, after the feeding of the wire electrode (1) is stopped, the wire electrode (1) and the workpiece (2) are detected by the electrode contact detection device (31).
The table position control means (32b) which has received the output signal for notifying the contact of the X-axis drive motor (3
5) Alternatively, the Y-axis drive motor (36) or both are drive-controlled to move the XY cross table (34) as shown in FIGS. 4 (a) to 4 (d) (step 45), and the wire electrode (1) ) And the processing start hole (3) are moved relative to each other. Fourth
In the figure (a), the tip of the wire electrode (1) has a processing start hole (3).
Shows a state in which feeding is stopped by touching the right side of the figure, and when relative movement is performed in the left and right directions of the figure as shown in FIGS. 4 (b) and 4 (c), the wire electrode (1 Since the tip of) also moves left and right while contacting the upper surface of the workpiece (2),
As shown in Figure (d), it must be inserted into the processing start hole (3). Therefore, the range of relative movement is limited to a certain range in order to prevent the tip of the wire electrode (1) from being dragged out of the machining start hole (3) again by relative movement. According to the experiments conducted by the present inventor, it has been found that the center line of the pipe guide (4) and the center line of the processing start hole (3) are not limited to a range not separated by 2.0 mm or more. In order to allow the wire electrode (1) to be inserted regardless of the direction in which the wire electrode (1) is in contact with the outer circumference of the processing start hole (3) and the feeding is stopped, for example, a fifth electrode is used.
The tip of the wire electrode (1) is set so as to appropriately move in each direction as shown in FIG. (A). 3)
Is inserted into. In addition to the way shown in FIG. 5 (a), there are countless ways to take the locus, including the locus shown in FIG. 5 (b) or (c).

As described above, when the tip of the wire electrode (1) comes to a position where it is surely inserted into the processing start hole (3), the electrode contact detection device (31) causes the wire electrode (1) and the work piece (2) to move. The signal for notifying the non-contact is output (step 46). The table position control means (32b) receiving the output signal stops and controls the X-axis drive motor (35) and the Y-axis drive motor (36).
Stop the XY cross table (34). Further, the wire feeding control means (32a) receiving the output signal drives and controls the drive motor (20) to continue the wire feeding of the wire electrode (1) (step 47). The wire electrode (1) where the wire feeding is continued is the processing start hole (3) and the lower guide (7).
Through the roller (26), is carried by the belt (27) and is collected in the collection box (30), and the wire insertion operation is completed (step 48).

By the way, for example, as shown in FIGS. 6 (a) and 6 (b),
If the tip of the wire electrode (1) is bent or the winding is strongly twisted, the XY cross table (34) is moved and the wire electrode (1) and the machining start hole (3) move relative to each other. However, the wire electrode (1) may not be inserted into the processing start hole (3) or may be caught in the processing start hole (3). In such a case, the wire electrode (1) cannot be inserted even if the wire is fed. Therefore, when the relative movement between the wire electrode (1) and the processing start hole (3) is completed within a certain range, the insertion failure state is detected by the electrode contact detection device (31). If it is in the insertion impossible state, the electrode contact detection device (31) outputs an output signal indicating the contact between the wire electrode (1) and the workpiece (2), and the wire cutting / supply control means (32c) receiving the output signal. ) Drives and controls the motor (21) to raise the pipe guide (4) to the upper part of the cutter (25), then operates the cutter (25) to cut the wire electrode (1), and after cutting, the motor The pipe guide (4) is lowered to its original position by (21) to complete the cutting operation. After the cutting operation is completed,
The wire cutting / supply control means (32c) again operates the drive motor (2
0) is driven to feed the wire electrode (1) toward the workpiece (2), and the wire feeding control means (32a) and table position control means (32b) repeat the above wire insertion operation. Then, the wire electrode (1) is surely inserted into the processing start hole (3) so that the wire electrode (1) can be inserted. When the wire electrode (1) is not inserted into the processing start hole (3) by the wire insertion operation after the wire is cut, the detection / cutting / supplying operation of such an uninsertable state is performed by the wire cutting / cutting operation. When the counter is a renewal control means built in the supply control means (32c), the counter is repeatedly performed a preset number of times (step 50). After that, the cutting / supplying operation is stopped (step 51).

[Effects of the Invention] As described above, according to the present invention, when the wire electrode comes into contact with the workpiece without being inserted into the machining start hole, the tip of the wire electrode is bent by a predetermined amount. By stopping the feeding so that the spring force of the wire electrode due to this deflection acts on the workpiece side, the XY cross table is moved in multiple directions within a specified range, so the movement of the wire electrode position The wire electrode can be prevented from jumping up at this time, and the insertion of the tip of the wire electrode into the processing start hole can be ensured. For this reason, it is possible to significantly improve the reliability of the automatic wire feeding operation especially to the small-diameter processing start hole, and it is possible to apply the processing start hole of φ1 mm or less, which has been conventionally difficult.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a circuit diagram showing an electrode contact detection device, FIG. 3 is a flow chart showing a procedure of wire feeding control, and FIGS. FIG. 5D is an explanatory view showing an example of a wire electrode and movement, and FIG.
FIGS. 6 (a) to 6 (c) are explanatory views showing an example of the loci of relative movements of the wire electrode and the workpiece, FIG. 6 (a),
(B) is explanatory drawing which shows another wire electrode and an example of movement, FIG. 7 is a block diagram which shows schematically the wire automatic supply apparatus of the conventional wire electric discharge machine, and FIG. 8 is the wire electrode of the same apparatus. FIG. 9 is a block diagram schematically showing a feeding operation, FIG. 9 is a block diagram showing a wire electrode cutting operation of the same apparatus, FIG. 10 and FIG.
FIG. 11 is a cross-sectional view showing a state of the wire electrode when the wire electrode is fed in the same device. In the figure, (1) is a wire electrode, (2) is a workpiece,
(3) is a machining start hole, (20) is a drive motor (wire feeding mechanism), (21) is a motor, (25) is a cutter, (31) is an electrode contact detection device, (32) is a control device, ( (32a) is wire feeding control means, (32b) is table position control means, (3
4) is an XY cross table, (35) is an X-axis drive motor (table drive mechanism), and (36) is a Y-axis drive motor (table drive mechanism). In each drawing, the same reference numerals indicate the same or corresponding parts.

Claims (2)

[Claims] 1. A wire automatic supply device of a wire electric discharge machine for automatically supplying a wire electrode to a workpiece on an XY cross table, a wire feeding mechanism for feeding the wire electrode to the workpiece side, and a fed wire Electrode contact detection means for detecting whether or not the electrode has come into contact with the workpiece, and when the electrode contact detection means detects contact of the wire electrode with the workpiece, the tip portion of the wire electrode is bent by a predetermined amount. Wire feeding control for controlling the wire feeding mechanism so as to continue the wire feeding when the non-contact of the wire electrode and the workpiece is detected by the electrode contact detection means after the wire feeding is stopped. Means and a table drive mechanism for moving the XY cross table when the wire feeding is stopped in a state where the tip of the wire electrode is bent by a predetermined amount, the XY cross table is operated. The table drive mechanism is configured to move the stable in multiple directions within a predetermined range, and to stop the movement of the XY cross table when non-contact of the wire electrode and the workpiece is detected by the electrode contact detection means during its operation. And an automatic wire feeder for a wire electric discharge machine. 2. A cutter mechanism for cutting the wire electrode when the contact of the wire electrode and the workpiece is detected by the electrode contact detection means after the multi-directional XY cross table position control within a certain range is completed by the table position control means. The wire automatic supply of the wire electric discharge machining apparatus according to claim 1, further comprising a wire cutting / supply control means for controlling the wire feeding mechanism so as to continue the wire feeding after the cutting. apparatus.