JPH0628816B2 - Wire cut electrical discharge machining method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a wire-cut electric discharge machining method, and more particularly to an improvement of a wire-cut electric discharge machining method in which a wire electrode is reciprocated in a machining portion to perform machining.

[Conventional technology]

The wire electrode supplied from the first arm or the processing head having the wire electrode supply / recovery device is folded back by the electrode returning device provided in the second arm or the processing head to form two reciprocating heads. The wire electrodes that reciprocate between the two are closely opposed to each other to give a machining feed,
A wire-cut discharge for performing machining while applying a voltage pulse for electric discharge machining between the wire electrode and the workpiece and supplying a machining liquid between the machining gap formed by the workpiece and the wire electrode approaching and facing each other. A processing method has been proposed and its implementation is under consideration.

[Problems to be solved by the invention]

As described above, when one wire electrode is folded back to form two reciprocating wires and machining is performed using the two reciprocating wire electrodes, it is possible to obtain a sufficient machining gap within the machining gap formed between the wire electrode and the workpiece. Since a large amount of machining liquid can be supplied, machining accuracy can be greatly improved, and a sufficient cooling effect can be obtained, so that efficient machining can be performed with a large current.

However, the wire-cut electric discharge machining has a problem that it is difficult to perform good roughing and finishing depending on the machining shape or the material of the workpiece.

In addition, the wire electrode has the property of being softened by electric discharge and its tensile strength being low, and many scratches are generated on the surface of the wire electrode on the return path by electric discharge, and in some cases the discharge gap becomes large and during rough machining. Since the two reciprocating wire electrodes are not uniformly machined, the machining accuracy is impaired, and it is also difficult to obtain a good machined surface.

[Problems to be solved by the invention]

The present invention has been made from the above viewpoint,
An object of the present invention is to provide a wire-cut electric discharge machining method that has high machining efficiency and machining accuracy and can always perform good roughing and finishing regardless of the machining shape or the material of the workpiece. It is a thing.

[Means for solving problems]

Thus, the above-mentioned object is a wire-cut electric discharge machining method in which a wire electrode is folded back and two reciprocating wire electrodes are brought into contact with each other and run in opposite directions to machine a workpiece.
This is achieved by arranging the two wire electrodes in the normal direction of the machining contour line during rough machining and by arranging them in the tangential direction during finishing machining.

[Action]

Thus, as described above, the two reciprocating wire electrodes are arranged in the normal direction of the machining contour line during rough machining, and are arranged in the tangential direction during finishing machining. Sufficient machining liquid is supplied to the machining gap with the body to enable stable machining.Furthermore, at the time of finishing when two reciprocating wire electrodes are arranged in the tangential direction, it can be performed twice in one process. Since the finishing process is performed by using this method, good finishing process is possible.

〔Example〕

Hereinafter, the configuration of the present invention will be specifically described with reference to the embodiments shown in the drawings.

FIG. 1 and FIG. 2 are explanatory views showing the step of stretching the wire electrode stepwise in the apparatus for carrying out the wire-cut electric discharge machining method according to the present invention, and FIG. FIG. 5 is an enlarged plan view of a wire electrode rotating device portion for changing the arrangement by rotating two reciprocating wire electrodes in FIG. 4, FIG. 4 is a sectional view taken along the line AA in FIG. 3, and FIG. FIG. 6 is a plan view showing an operating state of the rotating device shown in FIG. 4, and FIGS. 6 to 8 are explanatory views showing a processing situation by the method of the present invention.

In FIGS. 1 and 2, 101 is a column, and 102 is a first arm provided so as to be movable in the vertical direction in the figure with respect to the column 101 and extend toward the processing position. The processing head 103 is a second arm or processing head provided so as to be movable in the vertical direction in the figure with respect to the column 101 and extend toward the processing position, 104 is a wire electrode, 1
Reference numeral 05 is a wire electrode supply drum, 106 to 112 are guide rollers for supplying wire electrodes, 113 is a brake roller that can be brought into contact with and separated from the guide roller 111, 114 is an electrode folding roller, and 115 and 116 are energizing rollers. , 117 and 118 are wire electrode rotating devices for rotating guides 117a and 118a such as electrode positioning dies and boat-shaped guides, and 119 holds the electrode folding roller 114 on the side of the second arm or the processing head. An electrode return device for making a U-turn of the wire electrode 104 and returning it to the first arm or the processing head 102 side, 120 and 121.
Is a presser roller, 122 is a capstan, 123 is a capstan
A pinch roller provided so as to be able to approach and separate from 122, 124 to 126 are guide rollers for collecting wire electrodes, 127 is an electrode winding drum, 128 is a telescopic electrode transfer device, and 129 is a split type. No. 130 of the processing liquid jetting nozzle, 130 is a processing tank, 131 is a stage mounted in the processing tank 130, 13
2 X-axis direction moving table 133 and Y-axis direction moving table 13
A cross slide table composed of 4 and their driving motors 135 and 136, 137 is a bed, 138 is a workpiece fixed on a stage 131 by a clamp, and 139 is an energizing roller 1.
A power supply device for applying a voltage pulse for electric discharge machining between the wire electrode 104 and the workpiece 138 via 15.

Thus, FIG. 1 shows the wire electrode 10 at the processing preparation stage.
4 shows a stretched state of 4, the wire electrode 104 pulled out from the wire electrode supply drum 105 in the initial stage, through the guide rollers 106 to 111 for wire electrode supply,
Then, as shown by the dotted line in the figure, the electrode winding drum 12 is directly guided to the capstan 122 and the pinch roller 123, and then through the guide rollers 124 to 126 for collecting the wire electrode.
Connected to 7 to be collected.

At this time, the guide rollers 107 and 109 and the brake roller
113 is the corresponding guide roller 106, 10
8 and 111 are separated, and the presser roller 121 is also the guide roller 1
12, the energizing rollers 115 and 116 are also separated from each other, and the pressing roller 120 is also displaced to the right side in the drawing from the position during processing. In addition, guides 117a and 11 for positioning the electrodes are provided.
As 8a, for example, the electrode rotating devices 117 and 118 having open / close type dies or boat type guides by contact and separation or rotation described in Japanese Patent Application Nos. 58-194952 and 58-210374 are wire electrodes. For insertion, the wire electrode insertion portion is opened or retracted to the left side in the figure, and the split type machining liquid jet nozzle 129 is also in an open state. Furthermore, the folding roller 114, which is moved and held on the electrode returning device 119 side during processing, is also attached to the tip of the electrode conveying device 128 in the state shown in FIG.

Thus, when starting the processing, a nesting type electrode transfer device 128 that expands and contracts using hydraulic pressure or a motor as a power source.
Is gradually extended as shown in the figure. In that case, the wire electrode 104 stretched between the guide roller 111 and the capstan 121 is hooked on the electrode 114 by the electrode folding roller attached to the tip of the electrode transport device 128, and is moved downward in the drawing. Be stretched. At that time, the guide rollers 107, 1
Since the 09, the brake roller 113, and the like are separated from their corresponding guide rollers 106, 108, and 111, the wire electrode 104 moves along with the extension of the electrode transfer device 128, and the supply drum 105
Freely drawn from. A groove for holding and guiding the wire electrode is formed on the outer periphery of the folding roller 114 so that the wire electrode does not fall off.

Then, when the electrode transport device 128 extends and the tip thereof reaches the electrode return device 119 provided in the second arm or the processing head 103, the folding roller 114 is separated from the tip of the electrode transport device 128 and returned. Wire electrode 1 captured by device 119
04 is in a state of being stretched in a U-shape while reciprocating between the first arm or processing head 102 and the second arm or processing head 103.

After that, as shown in FIG. 2, a nested electrode carrier 12
8 is completely retracted, and then the pressing rollers 120 and 121 are moved to the left in the drawing to bring the wire electrodes 104 reciprocally stretched between the first and second arms or the processing head close to and contact each other. , The guide rollers 107, 109 and the brake roller 113 are connected to the guide rollers 106, 108, 1 respectively.
11, the energizing roller 116 is also moved to the left to make contact with the other energizing roller 115, and the wire electrode rotating devices 117 and 118 are further displaced in the right direction in the figure, respectively. The wire electrode 104 is held at a fixed position by the electrode positioning guides 117a and 118a,
By rotating the capstan 122, the wire electrode 104 is slowly run. Next, the division type machining liquid jet nozzle 129 is closed to start the supply of the machining liquid, the power supply device 139 is operated, and a voltage pulse is applied between the wire electrode 104 and the workpiece 138, so that the machining becomes possible. , The motors 135 and 136 of the cross slide table 132 are driven based on a command of a numerical controller (not shown) to maintain a predetermined gap between the wire electrode 104 and the workpiece 138, and if the machining feed is performed, The electric discharge machining of a desired shape is performed on the body 138.

Thus, during the above processing period, the wire electrode rotating device
117 and 118 are operated to arrange the two reciprocating wire electrodes 104 in the machining portion in the normal direction of the machining contour line during rough machining, and in the tangential direction during finishing machining. At the time of processing, the wire electrode on the return path is delayed by a minute distance from the wire electrode on the outward path.

Hereinafter, the configurations and functions of the wire electrode rotating devices 117 and 118 will be described with reference to FIGS. 3 to 5. However, since the configurations of both rotating devices are the same, only the electrode rotating device 117 provided on the first arm or processing head 102 side will be described here, and the rotation on the second arm or processing head 103 side will be described. The moving device will be omitted.

In FIGS. 3 to 5, 117a is a wire electrode positioning guide,
117b is a pedestal, 117c has a worm wheel type gear 117c-1 formed on the periphery thereof, and a protrusion 117c-2 on the bottom surface thereof.
Is a turntable that is rotatably fitted in a recess 117b-1 formed in the frame 117b, 117d is a gripping frame, and 117e is the gripping frame 117d.
The hydraulic cylinder 117f is a reciprocating two wire electrode 104 (hereinafter, the one going from the first arm or processing head 102 to the second arm or processing head 103 is referred to as the "outward side electrode 104a", the second electrode First from arm or processing head 103
The one returned to the arm or the processing head 102 is referred to as "return side electrode 104b". ) In the electrode guide groove formed in the electrode positioning guide 117a.
7g is a presser pin holder, 117h is a spring built in the above presser pin holder 117g and pushing out the above presser pin 117f, 11h
Reference numeral 7i is a support frame that supports the pressing pin holder 117g so that it can be moved toward and away from the guide 117a, and 117j and 117j are the rotary plates 117c.
Is fixed to the upper surface of the support frame 117i and slidably guides the support frame 117i, and 117k is attached to a rotation shaft of a motor 117l attached to the upper surface of the rotating plate 117c, and a side surface of the support frame 117i. The pinion gear meshed with the rack gear 117i-1 engraved on the shaft 117m is attached to the rotary shaft of the motor 117n attached to the mount 117b, and is of the worm wheel type formed on the peripheral portion of the rotating plate 117c. Tooth profile
Worm gear meshed with 117c-1.

Thus, as shown in FIG. 1, during the period in which the wire electrode transport device 128 is operated and the wire electrode 104 is suspended from the first arm or processing head 102 to the second arm or processing head 103. For example, the entire wire electrode rotating device 117 is retracted to the left in the drawing, and the pinion gear 117k is used to move the support frame 117i in the horizontal direction on the rotating plate 117c.
Is rotated counterclockwise in the figure and meshes with the rack gear
The support frame 117i is extended rightward in the figure by 117i-1, so that the wire electrode 104 is suspended while the pressing pin 117f is separated from the guide 117a to the rightmost position.

Then, as shown in FIG. 2, the wire electrode 104 is wound around the electrode returning device provided in the second arm or the processing head 103, and the two reciprocating wire electrodes 104a and 104b are supported by the supporting frame 117i.
When it is inserted into the inner region, the hydraulic cylinder 117e operates and the gripping frame 117d advances to the right in the figure, whereby the two reciprocating wire electrodes 104a, 104b form the electrode guide formed on the electrode positioning guide 117a. Taken into the groove. At the same time, the pinion gear 117k is rotated clockwise in the figure, and the support frame 117i is moved leftward in the figure, so that the presser pin 117f is moved.
Enter the electrode guide groove of the electrode positioning guide 117a, and the action of the spring 117h causes the two wire electrodes 104a, 10a to
Hold 4b in a fixed position by pressing 4b close enough or contacting each other.

As described above, when the wire electrode tensioning work is completed and the two reciprocating wire electrodes 104a and 104b are tensioned in a straight line in a processed portion, the wire electrode 104 is stretched as described above.
Machining is started by applying a voltage pulse for electric discharge machining between the workpiece 138 and the workpiece 138 and controlling the cross slide table 132 by the numerical controller to provide machining feed therebetween.

Thus, during the rough machining during the machining period, the wire electrode 104a,
The 104b are arranged in the normal direction of the machining contour line, and are arranged in the tangential direction at the time of finishing, and machining is performed.

Further, under a processing condition (for example, special finishing processing) in which the electrode is not consumed to the extent that it affects the diameter of the wire electrode, the surface of the return-side electrode 104b has a large number of scratches due to the discharge, resulting in a large discharge gap. However, since the diameter of the wire electrode does not change, as shown in FIG. 6, the return path side electrode 104b is processed in an excessively processed state depending on the material or processed shape of the work piece. As shown in FIG. 7, processing is performed while maintaining the state in which the outward path side electrode 104a is advanced by a minute distance with respect to the return path side electrode 104b.

Therefore, during the machining period, the motor 117n attached to the pedestal 117b is operated by a command from the numerical control device by a command from the numerical control device (not shown in the figure), which causes the worm wheel type tooth profile 117c-1 to operate. Turntable 117c
Is rotated, which causes the wire electrodes 104a and 104b to rotate.
When the rough machining is performed as described above, the wire electrodes 104a and 104b are arranged in the normal direction of the machining contour line and
The electrodes 104b are arranged in a state of being slightly delayed with respect to the outward-path side electrodes 104a, and are adjusted so as to be arranged in a tangential direction during finishing processing.

Also, depending on the shape of the processed part, etc., as shown in FIG.
The wire electrodes 104a and 104b are appropriately arranged in the normal direction or the tangential direction of the processing contour line for processing.

〔The invention's effect〕

Since the present invention is configured as described above, according to the present invention, since the processing is performed while controlling the arrangement of the two reciprocating wire electrodes according to the processing state, the two electrodes and the workpiece are The machining liquid is sufficiently supplied to the machining gap of and the finishing process is performed twice in a single process, so that the machining shape or the material of the workpiece can be changed. Regardless, good finishing can always be performed.

The configuration of the present invention is not limited to the above embodiment. That is, for example, in the present embodiment, two wire electrodes are arranged in the normal direction of the machining contour line during rough machining, and the return path side electrode of the two wire electrodes is the forward path side electrode. Although the machining is performed with a further minute delay, in addition to this, the machining is performed while appropriately controlling the repetition frequency of the voltage pulse supplied between the wire electrode and the workpiece, the ejection amount of the machining fluid, the ejection pressure, and the like. It is also recommended to configure as. Further, the electrode transfer device 128 does not necessarily have to be a telescopic type in a telescopic form, and may be a device that simply raises and lowers one rod. Machining liquid jet nozzle 12
It is also recommended that 9 be mounted not only on the first arm or working head but also on the second arm or working head. The electrode return device 119 also includes the wire electrode 104.
Any form may be used as long as it can be folded back on the side of the second arm or the processing head and returned to the side of the first arm or the processing head. For example, the electrode folding roller 114 is fixed to the electrode returning device 119 from beginning to end, and the wire electrode hooked on the most distal rod of the electrode conveying device 128 or the rod as an elongated pipe is fed back inside and outside the pipe. The wire electrode may be configured to be hooked on the fixed folding roller 114. Further, the structure of the wire electrode rotating device 117 is not limited to that of the above-described embodiment, and various design changes can be made, and the electrode positioning guide 117a can also take various forms as described above.

In the illustrated embodiment, the wire electrode rotating device 11
Although only the electrode positioning guides 117a and 118a are rotated by 7 and 118, the energizing rollers 115 and 116, the guide roller 112, the pressing roller 121 and the like are also rotated together with the guide 117a, and further the electrode return is performed. Also guides device 119 and presser roller 120
It may be configured to rotate together with 118a. In short, two wire electrodes that reciprocate in a portion opposed to the workpiece are extended at least in the processing portion in the normal direction of the processing contour line. Any configuration may be used as long as it can be arranged in the tangential direction. Furthermore, in the above-mentioned embodiment, the used wire electrode is replaced with the electrode winding drum.
Although it was collected in 127, it may be directly discarded in the collection box. Therefore, the present invention covers all modifications that can be easily conceived by those skilled in the art from the above description.

[Brief description of drawings]

FIG. 1 and FIG. 2 are explanatory views showing the step of stretching the wire electrode stepwise in the apparatus for carrying out the wire-cut electric discharge machining method according to the present invention, and FIG. FIG. 5 is an enlarged plan view of a wire electrode rotating device portion for changing the arrangement by rotating two reciprocating wire electrodes in FIG. 4, FIG. 4 is a sectional view taken along the line AA in FIG. 3, and FIG. FIG. 6 is a plan view showing an operating state of the rotating device shown in FIG. 4, and FIGS. 6 to 8 are explanatory views showing a processing situation by the method of the present invention. 101 …… Column 102 …… First arm processing head 103 …… Second arm processing head 104 …… Wire electrode 105 …… Wire electrode supply drum 106 to 112 …… Guide roller 113 …… Brake roller 114 …… Electrode Folding roller 115, 116 ...... Current-carrying roller 117, 118 ...... Wire electrode rotating device 117a …… Electrode positioning guide 117b …… Stand 117c …… Rotating plate 117d …… Grip frame 117e …… Hydraulic cylinder 117f …… Presser pin 117g …… Presser pin holder 117h …… Spring 117i …… Support frame 117j, 117j …… Support frame guide 117k …… Pinion gear 117l, 117n …… Motor 117m …… Worm gear 120,121 …… Presser roller 122 …… Capstan 123 ...... Pinch rollers 124 to 126 …… Guide rollers 127 …… Electrode winding drum 128 …… Electrode transport device 129 …… Split type machining fluid jet nozzle 130 …… Machining tank 131 …… Platform 132 …… Cross slide table 1 33 …… X-axis moving table 134 …… Y-axis moving table 135,136 …… Drive motor 137 …… Bed 138 …… Workpiece 139 …… Power supply unit

Claims (2)

[Claims] 1. A wire-cut electric discharge machining method in which a wire electrode is folded back and two reciprocating wire electrodes are brought into contact with each other and run in opposite directions to machine a workpiece. The above wire-cut electric discharge machining method is characterized in that the machining is performed by arranging in a normal direction of a machining contour line during machining and by arranging in a tangential direction during finishing machining. 2. The wire-cut electric discharge machining method according to claim 1, wherein the electrode on the return path is delayed by a minute distance from the electrode on the outward path during rough machining of the two wire electrodes.