JPS6218289B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in wire-cut electrical discharge machining equipment, and particularly to a workpiece fall prevention device that prevents the workpiece from tilting and falling at the end of machining.

Figure 1 shows a wire-cut electric discharge machining device that performs this type of machining. In the figure, 1 is a wire electrode, and a metal wire with a diameter of usually about 0.05 to 0.3 mm is transferred from a wire supply reel 2 to a take-up reel 3. It is wound at a constant speed. 4 and 5 are an upper guide and a lower guide for supporting and guiding the wire electrode 1;
1 is a power supply plate that slides in contact with the wire electrode 1, 7 is a workpiece, and 8 is a machining power source. supply 9 is the machining fluid nozzle,
A machining fluid 11 having a specific resistance of about tens of thousands to hundreds of thousands of Ω·cm is supplied from a machining fluid supply device 10 to the machining gap. 12 is an X-Y for holding and fixing the workpiece 7
Cross table 13 is a numerical control device that gives rotation commands to the X-axis drive motor 14 and Y-axis drive motor 15 that operate this X-Y cross table 12. The relative position and relative speed with respect to the workpiece 7 are controlled, and the workpiece 7 is cut into a desired contour shape.
Punching etc. are performed.

Figure 2 shows the machining part of the workpiece in detail. In the figure, the same symbols as in Figure 1 indicate the same parts, 7a is the machining gap of the workpiece 7, and 7b is the machining gap of the workpiece 7. The formed machining grooves 9a and 9b are an upper machining liquid nozzle and a lower machining liquid nozzle that supply the machining liquid 11 to the machining gap 7a.
It is usually shaped like a pipe to concentrate it.
16 is an upper arm, and 17 is a lower arm, which respectively support processing liquid nozzles 9a, 9b, guides 4, 5, etc.

A workpiece is machined into a desired shape by the wire cut electric discharge machining apparatus configured as described above, and when this machining is completed and the process is about to end, as shown in FIG. 3, the workpiece 7c is cut off and falls off.
(hereinafter referred to as the punch-like member) and the workpiece 7d that does not fall out (hereinafter referred to as the die-like member) have a small remaining machining area, and the supporting force of this machining residual area alone cannot support the weight of the punch-like member 7c. The punch-like member 7c becomes tilted. At this time, if the wire electrode 1 contacts at least one of the punch-like member 7c or the die-like member 7d of the workpiece 7 and a short circuit occurs, the machining is stopped and continuous machining is no longer possible. Further, unless a short circuit occurs, processing continues, but the punch-like member 7c
Since it is tilted, the machining accuracy in this part will be poor.

Further, at the time when the machining of the workpiece is completed, the punch-like member 7c that has been machined into the desired shape loses its supporting portion and falls, as shown in FIG. At this time, the punch-like member 7c is inserted into the lower machining liquid nozzle 9b located below the punch-like member 7c.
collides, and the punch-like member 7c is damaged,
Or the lower processing liquid nozzle 9b or the lower arm 17
There was a drawback that it could cause damage to other items.

In order to prevent the punch-like member from tilting or falling at the end of machining, it has been conventionally done by pouring adhesive into the groove of the workpiece during machining to fix the punch-like member. Alternatively, a method has been used in which a punch-like member and a die-like member are fixed with a fixing fitting or the like with a machined groove in between. However, all of these methods require manual intervention during processing, which is cumbersome, and requires workers to be on standby even during automatic operation at night, which is extremely inconvenient. Furthermore, the fixing method using adhesive requires a step of separating the punch-like member and die-like member after processing, which has the disadvantage of reducing work efficiency.

In order to solve these drawbacks, proposals as shown in FIGS. 5 to 8 have been made.

Figures 5 and 6 show an example of this proposal,
In the figure, 7 is a workpiece, 18 is an original hole formed in this workpiece 7 and into which a wire electrode (not shown) is inserted at the start of machining, 7b is a machining groove, 7e is a planned machining trajectory, and 7c is punch-like member,
7d is a die-shaped member, 9a is an upper processing liquid nozzle, 1
9 is a pin implanted in the punch-like member 7c;
It is attached to the punch-like member 7c by screwing or the like. Reference numeral 20 denotes a holding plate that is rotatably provided around this pin 19, and the length from the center to both ends is longer than the longest part of the planned machining trajectory 7e, and the upper machining liquid nozzle 9a abuts the side surface. It is constructed to have a thickness of
In addition, this holding plate 20 is made of a material that can withstand enough to suspend the punch-like member 7c, and
In particular, in the case of a wire-cut electrical discharge machining apparatus in which the upper machining fluid nozzle 9a is located at the same level as the wire electrode 1, it is necessary to construct the upper machining fluid nozzle 9a from an insulating material. Furthermore, the fitting rotating part between the pin 19 and the holding plate 20 is made using a bearing or the like, or each part is processed to be smooth.
The holding plate 20 is designed to be able to rotate smoothly even with a slight pressing force.

Next, the operation will be explained. Prior to performing a predetermined electric discharge machining, a pin 19 and a holding plate 2 are placed approximately at the center of the planned position where the punch-like member 7c is to be machined.
Set to 0. Next, when the wire electrode is inserted into the original hole 18 and processing is started, the upper processing liquid nozzle 9a eventually comes into contact with the side surface of the holding plate 20. After this, the upper machining liquid nozzle 9a continues to press the holding plate 20 until this machining is completed. Therefore, at the end of processing, the holding plate 20 suspends the punch-like member 7 with both ends bridged by the die-like member 7d, thereby preventing the punch-like member 7c from falling. Furthermore, even just before the end of machining, the holding plate 20 acts to prevent the punch-like member 7c from tilting, allowing complete machining to be performed without reducing machining accuracy even in the final machining part.

FIG. 7 shows another example of this proposal. In the figure, 21 is a cross-shaped retainer that is freely rotatably fitted with a pin 19 implanted in a punch-like member 7c that is scheduled to be processed. plate, at least retaining plate 21
A part of the die-like member 7d is always bridged over the die-shaped member 7d. Reference numeral 22 denotes a T-shaped holding plate, and when the bridge portion 22a of this holding plate is pressed against the upper processing fluid nozzle 9a and rotated, the other portion 22b becomes bridge-like. Such a holding plate 2
If No. 1 or 22 is used, the holding plate can be made smaller, and the distance that the machining fluid nozzle contacts and presses against the holding plate can be shortened, especially when the punch-like member's own weight is added at the end of machining. There is no need to rinse while pressing the holding plate, which has a large anti-rotation force, and the pressing force of the upper machining liquid nozzle can be reduced accordingly.

FIG. 8 shows still another example of this proposal, in which a pin 1 is implanted on the lower surface of the die-shaped member 7d.
9 and a holding plate 21 having a cross shape or the like is rotatably fitted, and this holding plate 21 is rotated by contacting and pressing the lower processing liquid nozzle 9b. This example is suitable when there is no space above the punch-like member 7c to attach the holding plate 21, or when it is undesirable to provide an attachment hole for the pin 19 in the punch-like member 7c.

However, the above proposal also has the following drawbacks. The first problem is that the machining liquid nozzle that presses and rotates the holding plate does not come into contact with the holding plate. The reason for this is shown in Figures 9 and 10.
The diagram will be explained. That is, in the test machining before the main machining, as shown in the cross section in FIG. In this case, it is known that the upper and lower groove widths can be made uniform by moving the upper guide 4 upward from l ₂ to l' ₂ (l ₂ <l' ₂ ) as shown in FIG. ing. As a result, the position of the upper machining liquid nozzle is also moved upward so that it does not come into contact with the holding plate. On the other hand, when the upper groove width increases, the upper machining liquid nozzle is moved downward together with the upper guide 4, and the part other than the cylindrical part of the nozzle comes into contact with the holding plate, causing an inconvenience. . The second drawback is that the wire electrode 1 and the machining fluid nozzle are made to have the same potential in order to prevent the machining fluid nozzle, which is usually made of metal, from being electrolytically corroded. The holding plate must be made of insulating material to prevent short circuit with the processing fluid nozzle.
This weakens the holding force of the holding plate, and if the weight of the punch-shaped portion increases, it will no longer be possible to hold it. The third drawback is that since the holding plate is pressed and rotated by the machining fluid nozzle, a reaction force is applied to the machining fluid nozzle, which in turn affects the guide, causing a reduction in machining accuracy. This has a particularly large effect when the rotation of the holding plate is not smooth.

This invention was made in order to eliminate the above-mentioned drawbacks, and has a fixed part of the device located near the machining liquid nozzle that can freely move toward and away from the workpiece.
In addition, by providing a pressing member that abuts in an electrically insulated state on the side surface of a holding member (hereinafter referred to as a holding plate) that provides a part of the workpiece to be cut off during the cutting process of the workpiece, the workpiece can be cut off. It is an object of the present invention to provide a workpiece fall prevention device in which a pressing member always comes into contact with a holding plate without reducing processing accuracy.

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 11, the same reference numerals as those in FIG. 2 indicate the same or corresponding parts, and 23 is a pipe whose one end is fixed to the upper arm 16 with a screw or the like, and from which the machining fluid 11 from the upper machining fluid nozzle 9a is discharged. The cylindrical portion of the first pressing member 23 is provided with a thread. 24 is the first pressing member 23
A second pressing member 24 is screwed onto the cylindrical portion of the cylindrical portion of the cylindrical portion 24, and the second pressing member 24 can be moved up and down by rotating. Note that the pressing members 23, 24
The first pressing member 23 has no part in contact with the upper processing liquid nozzle 9a, and except for the device in which the upper arm 16 and the workpiece 7 are at the same potential.
At least one of the second pressing member 24 and the second pressing member 24 are made of an insulating material. FIG. 12 shows a plane of the pressing members 23 and 24.

When the holding plate is pressed and rotated by the pressing member configured in this way, the second pressing member can be raised and lowered as desired, so that the pressing member is always in contact with the holding plate and the pressing member is not connected to the machining fluid nozzle. Since contact is avoided and the holding plate is rotated by the pressing force of the arm, the machining accuracy of the workpiece will not be reduced. Furthermore, since the pressing member is insulated, the holding plate can be made of metal.

FIG. 13 shows another embodiment of the present invention, in which an upper arm 16 of a wire cut electrical discharge machining apparatus is shown.
A rod-shaped pressing member 25 is screwed together. This pressing member 25 is made of an insulating material if necessary. Note that even if the positional relationship between the pressing member 25, the machining liquid nozzle 9a, and the holding plate changes as the machining progresses, the holding plate is always in contact with only the pressing member 25, and the machining liquid nozzle is not contacted. ing. In this embodiment, a plurality of rod-shaped pressing members 25 having different lengths are provided, and the distance to the holding plate is adjusted by using a pressing member 25 of a desired length or by rotating the pressing member 25 to raise and lower it. Therefore, the price of the pressing member 25 can be reduced.

Fig. 14 is applied when the pressing force for rotating the holding plate is not so large, and a thread is formed in the pipe-shaped part of the upper processing liquid nozzle 9a from which the processing liquid 11 is discharged. A pressing member 26 is screwed together. Also in this device,
It can be raised and lowered by rotating the pressing member 25,
The contact position of the holding plate is adjusted.

In addition, in the above embodiment, the case where the retainer plate is provided on the upper surface of the punch-like member is explained.
Even in the case where a holding plate is provided on the lower surface of the die-shaped member, it is possible to implement the same method as in the above embodiment by attaching a pressing member to the lower arm.

In addition to being provided on the arm, the pressing member may be provided on a strongly constructed device part.

As described above, in the present invention, either the workpiece part that is cut off by the cutting process or the workpiece part that remains uncut, the workpiece part that is cut off and the workpiece part that remains uncut. At least one holding plate for supporting the workpiece part to be cut off is rotatably provided at a position spanning the workpiece part remaining in the workpiece, and a fixed part of the apparatus located near the machining liquid nozzle is provided with at least one holding plate for supporting the workpiece part to be cut off. The structure includes a pressing member that can freely move toward and away from the workpiece and that contacts the side surface of the holding plate in an electrically insulated state during cutting of the workpiece, so that the workpiece can be cut off by the holding plate. The machining accuracy of the workpiece is improved by preventing tilting of the workpiece, and even if the machining liquid nozzle moves away from the workpiece, the pressing member can be brought into contact with the holding plate and the desired rotation can be given. Moreover, since the pressing member contacts the holding plate in an electrically insulated state, the holding plate can be made of metal, which has the effect that even if the weight of the workpiece to be cut increases, it can be held by the holding plate. .

[Brief explanation of the drawing]

Fig. 1 is a diagram explaining a wire cut electric discharge machining device, Fig. 2 is a cross-sectional view showing the part where a workpiece is machined, and Figs. 3 and 4 are workpieces machined by conventional processing equipment. 5 to 8 are cross-sectional views showing the object, and FIGS.
0 is a diagram showing the processing state, FIG. 11 is a sectional view showing an embodiment of the present invention, FIG. 12 is a plan view showing a pressing member according to an embodiment of the invention, FIGS. 13 and 14. 3A and 3B are cross-sectional views showing other embodiments of the present invention, respectively. In the figure, 1 is a wire electrode, 4 is an upper guide, 5 is a lower guide, 7 is a workpiece, 9 is a machining liquid nozzle, 20, 21, 22 are holding plates, 23, 2
4, 25, and 26 are pressing members. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] 1. Cutting the workpiece by applying relative feed between the wire electrode and the workpiece while supplying machining liquid from a machining liquid nozzle to the machining gap between the wire electrode and the workpiece. A wire-cut electrical discharge machining device is provided, in which a holding member configured as follows is attached to at least one of the workpiece portion that is cut off by cutting and the workpiece portion that remains uncut. At the same time, a pressing member is provided on a fixed part of the device located near the machining liquid nozzle, which is capable of moving toward and away from the workpiece, and which contacts the holding member in an electrically insulated state during cutting of the workpiece. A workpiece fall prevention device characterized by being provided with a workpiece fall prevention device. (a) To support the part of the workpiece to be cut off,
It is rotatably mounted so as to straddle the groove formed during cutting. (b) The structure is such that a portion different from the portion pressed by the pressing member with respect to the center of rotation of the holding member always straddles the groove. 2. The workpiece fall prevention device according to claim 1, wherein the holding member is provided on the upper surface of the part of the workpiece to be cut off. 3. The workpiece fall prevention device according to claim 1, wherein the holding member is provided on the lower surface of the workpiece portion that remains without being cut off. 4. The workpiece fall prevention device according to claim 1 or 2, wherein the pressing member is screwed onto an arm that is a fixed part of the device. 5. The workpiece fall prevention device according to claim 1 or 2, wherein the pressing member is screwed onto a machining liquid nozzle that is a fixed part of the device. 6. Claim 1, characterized in that the pressing member consists of a first pressing member fixed to an arm that is a fixed part of the device, and a second pressing member screwed to the first pressing member. Or the workpiece fall prevention device described in item 2. 7. The workpiece fall prevention device according to any one of claims 1 to 7, wherein a portion of the pressing member that comes into contact with the holding member is electrically insulated.