JP2011235405A - Wire electric discharge machining device, and wire electric discharge machining method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wire electric discharge machining apparatus that improves straightness accuracy by suppressing both a concave error and a top/bottom dimensional error.SOLUTION: The wire electric discharge machining device is provided for machining a workpiece 2 by an electric discharge from a wire 1 which vertically extends. The machining device includes: a voltage applicator 11 for applying a machining voltage to the wire; a upper supporter 4a for supporting the wire above the workpiece; a lower supporter 4b for supporting the wire below the workpiece; and a mover 12 for moving one of the supporters in a direction along the wire and away from the workpiece, and moving the supporter in a direction substantially perpendicular to a finished surface of the workpiece and away from the workpiece.

Description

  The present invention relates to a wire electric discharge machining apparatus and a wire electric discharge machining method.

  Wire electric discharge machining is widely used as a machining method capable of machining a workpiece with high accuracy relatively easily, but the demand for machining accuracy is becoming increasingly high. For example, not only the shape accuracy of the upper and lower surfaces of the workpiece, but also the shape of the middle part of the workpiece cut by a plane perpendicular to the thickness direction is required to be substantially the same as the upper and lower surfaces. It has become to. This indicates that it is required to reduce unevenness on the side surface (finished surface) of the workpiece and to obtain high straightness accuracy. In wire electric discharge machining, machining in stages such as rough machining and finishing machining is performed, but higher straightness is required particularly in finishing machining performed after the second cut after the rough machining.

  In the conventional wire electric discharge machining apparatus, vibrations may occur in the vertically extending wire due to the influence of the machining liquid ejected from the machining liquid nozzle. The vibration of the wire does not have the largest amplitude at the center as in general string vibration, but the amplitude of the portion located at a distance of about 1/4 of the plate thickness from the upper surface of the workpiece. Is the largest. The cause of the shift of the position where the amplitude is maximum has not been clarified so far. Due to the vibration of the wire, the workpiece is processed into a shape called “taiko” in which the middle step in the thickness direction is recessed from the upper and lower surfaces. Since a Tyco error defined by the distance between the straight line connecting the upper and lower surfaces of the workpiece and the most recessed point occurs, irregularities are likely to occur on the side surface of the workpiece, making it difficult to improve straightness accuracy.

  Therefore, for example, Patent Document 1 discloses a technique for increasing the straightness accuracy by increasing the interval between the workpiece and the machining liquid nozzle during finishing and reducing the ejection of the machining liquid.

JP-A-63-022219

  According to the technique disclosed in Patent Document 1, the amplitude of the wire is maximized by weakening the ejection of the machining liquid to reduce the amplitude of the wire and expanding the gap between the workpiece and the machining liquid nozzle. The position is moved to a position away from the work piece to suppress the Tyco error. However, the amplitude of the wire increases on the side of the machining liquid nozzle away from the workpiece, for example, on the upper surface side of the workpiece. As a result, there is a problem that a difference between the upper surface shape and the lower surface shape of the workpiece (hereinafter referred to as vertical dimension error) becomes large.

  This invention is made | formed in view of the above, Comprising: It aims at obtaining the wire electrical discharge machining apparatus which can improve a straightness precision, suppressing both a Tyco error and a vertical dimension error.

  In order to solve the above-described problems and achieve the object, the present invention is a wire electric discharge machining apparatus for machining a workpiece by electric discharge from a vertically extending wire, and a voltage application for applying a machining voltage to the wire. An upper support portion that supports the wire above the workpiece, a lower support portion that supports the wire below the workpiece, and one of the support portions extends along the wire from the workpiece. And moving means for moving the support portion in a direction substantially perpendicular to the finished surface of the workpiece and away from the workpiece.

  According to the present invention, there is an effect that it is possible to improve both straightness accuracy by suppressing both a Tyco error and a vertical dimension error.

FIG. 1 is a diagram illustrating a schematic configuration of the wire electric discharge machining apparatus according to the first embodiment of the present invention, and is a diagram illustrating a process of performing rough machining on a workpiece. FIG. 2 is a view for explaining the position of the support portion when the finish machining after the second cut is executed on the workpiece by the wire electric discharge machining apparatus shown in FIG. 1. FIG. 3 is a diagram for explaining the vibration state of the wire during finishing. FIG. 4 is a diagram for explaining a straightness error when the finishing process is executed in the state shown in FIG. FIG. 5 is a diagram illustrating a conventional finishing example in which the machining liquid nozzle and the support portion are not moved. FIG. 6 is a diagram for explaining a Tyco error that occurs in the finishing process shown in FIG. FIG. 7 is a diagram showing a conventional finishing process example in which the machining liquid nozzle and the support portion are moved upward. FIG. 8 is a diagram for explaining the vertical dimension error generated in the finishing process shown in FIG.

  Hereinafter, a wire electric discharge machining apparatus and a wire electric discharge machining method according to an embodiment of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is a diagram illustrating a schematic configuration of the wire electric discharge machining apparatus according to the first embodiment of the present invention, and is a diagram illustrating a process of performing rough machining on a workpiece. The wire electric discharge machining apparatus includes a wire 1, a machining liquid nozzle 3, a support unit 4, a voltage application unit 11, and a moving unit 12. The wire 1 is provided so as to extend vertically. A processing voltage is applied to the wire 1 from the voltage application unit 11. The workpiece 2 is machined by the occurrence of electric discharge between the workpiece 2 as the workpiece and the wire 1. The processing of the work 2 includes a roughing process for cutting a product from the solid work 2 and a finishing process for increasing the straightness accuracy of the finished surface 2a cut by the roughing process.

  The machining fluid nozzle 3 includes an upper machining fluid nozzle 3 a provided above the workpiece 2 and a lower machining fluid nozzle 3 b provided below the workpiece 2. The machining liquid nozzle 3 ejects the machining liquid toward the workpiece 2 along the wire 1. The machining waste generated between the wire 1 and the workpiece 2 is discharged by the machining liquid ejected from the machining liquid nozzle 3. In addition, the wire 1 penetrates the machining liquid nozzle 3 so that the machining liquid can be ejected from a position close to the workpiece 2.

  The support part 4 includes an upper support part 4 a that supports the wire 1 above the work 2, and a lower support part 4 b that supports the wire 1 below the work 2. The wire 1 is supported by the upper support portion 4a and the lower support portion 4b so as to extend vertically (in the vertical direction).

  The voltage application unit 11 applies a pulsed processing voltage to the wire 1. The moving means 12 moves the upper support portion 4a in the direction along the wire 1 and away from the workpiece 2, that is, upward. Further, the moving means 12 moves the upper support portion 4 a in a direction substantially perpendicular to the finished surface 2 a of the work 2 and away from the work 2. The moving means 12 is, for example, a motor.

  With the wire electric discharge machining apparatus described above, rough machining shown in FIG. 1 is performed on the solid workpiece 2 to cut out a product. The support 4 in the roughing process is a state in which the wire 1 finishes the workpiece 2 in a state in which no machining liquid is ejected from the machining liquid nozzle 3 and no machining voltage is applied, that is, no vibration is generated in the wire 1. At a position parallel to the surface 2a.

  FIG. 2 is a view for explaining the position of the support portion 4 when the finish machining after the second cut is executed on the workpiece 2 by the wire electric discharge machining apparatus shown in FIG. In FIG. 2 and subsequent figures, the voltage application unit 11 and the moving means 12 are not shown. As shown in FIG. 2, when performing the finishing process, the upper support part 4a is moved upward (in the direction indicated by the arrow X) along the wire 1, and the upper support part 4a is moved from the roughing process. Is moved away from the workpiece 2.

  Further, when the finishing process is performed, the upper support 4a is placed in a direction substantially perpendicular to the finishing surface 2a of the work 2 and away from the work 2 than in the roughing process (direction indicated by an arrow Y). Slightly move and tilt wire 1.

  The upper working fluid nozzle 3a is also moved in the directions indicated by the arrows X and Y. This is because the wire 1 also moves with the movement of the upper support portion 4a, so that the upper machining liquid nozzle 3a penetrating the wire 1 also needs to be moved. Moreover, it is also for suppressing the jet pressure of the machining fluid applied to the workpiece 2.

  FIG. 3 is a diagram for explaining the vibration state of the wire 1 during finishing. As shown in FIG. 3, at the time of finishing, the wire 1 vibrates due to the ejection of the machining fluid. By moving the upper support portion 4 a in the direction indicated by the arrow X, the portion of the wire 1 having the largest amplitude is positioned away from the workpiece 2. Thereby, the Tyco error which generate | occur | produces in the finishing surface 2a of the workpiece | work 2 can be suppressed.

  Further, by moving the upper support portion 4a in the direction indicated by the arrow Y, the inclination generated by the vibration of the wire 1 is canceled out. Thereby, the vertical dimension error which generate | occur | produces in the finishing surface 2a of the workpiece | work 2 can be suppressed.

  FIG. 4 is a diagram for explaining a straightness error when the finishing process is executed in the state shown in FIG. As shown in FIG. 4, in the above-described finishing process, the straightness error 7 can be further reduced, and a process with high straightness accuracy can be realized. The straightness error 7 is defined as the larger error of the Tyco error and the vertical dimension error. Further, the Tyco error and the vertical dimension error will be described in detail later.

  Here, in many cases, the vibration amplitude of the wire 1 is maximized at a portion located about a quarter of the plate thickness from the upper surface of the work 2, and therefore, the upper support 4 a is moved upward. If the distance is ¼ or more of the workpiece plate thickness, desirably about の of the plate thickness, for example, a plate thickness of 60 mm, the moving distance is preferably set to about 20 mm. Further, since the vertical dimension error is approximately 10 μm or less, and in many cases about 3 to 5 μm, the distance between the wire 1 in the state where no vibration is generated and the upper end of the workpiece 2 is 3 to 5 μm. What is necessary is just to move the support part 4a.

  Moreover, although the intensity of the jetting of the processing liquid is not described, a method of reducing the jetting pressure and reducing the vibration amplitude of the wire 1 may be used in the finishing process.

  Further, the movement of the upper support portion 4a in the direction indicated by the arrow Y is performed in order to eliminate the vertical dimension error in the finishing process caused by the movement of the upper support portion 4a in the direction indicated by the arrow X. Therefore, it is necessary to perform the finishing process after performing both of these two movements. By adopting such a configuration, in the roughing process, the machining liquid nozzle 3 is brought into close contact with the workpiece 2 to suppress the occurrence of wire breakage and improve the machining speed, and in the finishing process with less fear of wire breakage, The straightness accuracy can be improved by moving the machining liquid nozzle 3 and the support portion 4 so as to move the machining liquid nozzle 3 away from the workpiece 2.

  In the present embodiment, the upper support 4a and the upper machining liquid nozzle 3a are moved, but the lower support 4b and the lower machining liquid nozzle 3b may be moved. For example, the lower support 4b and the lower working fluid nozzle 3b may be moved downward and moved in the direction indicated by the arrow Y in FIG. However, in order to remove the portion where the amplitude of the wire 1 is maximum below the workpiece 2, the moving distance below the lower supporting portion 4b is longer than the moving distance when moving the upper supporting portion 4a upward. Will grow.

  Next, an example of a conventional finishing process will be shown, and the Tyco error and the vertical dimension error will be described. FIG. 5 is a diagram illustrating a conventional finishing example in which the machining liquid nozzle and the support portion are not moved. FIG. 6 is a diagram for explaining a Tyco error that occurs in the finishing process shown in FIG.

  As described above, the wire 21 is brought into a vibration state by the ejection of the machining liquid from the machining liquid nozzle 23 or the like. Here, the vibration of the wire 21 does not have the largest amplitude in the central portion unlike the vibration of a general string, and the amplitude of the portion located at a distance of about ¼ of the plate thickness from the upper surface of the work 22 is not. Become the largest. The cause of this has not been clarified so far. However, due to the vibration described above, the work 22 is processed into a shape as shown in FIG. The The Tyco error 5 is defined by the distance between the straight line connecting the upper and lower surfaces of the workpiece 22 and the most recessed point.

  FIG. 7 is a diagram showing a conventional finishing process example in which the machining liquid nozzle and the support portion are moved upward. FIG. 8 is a diagram for explaining the vertical dimension error generated in the finishing process shown in FIG.

  As shown in FIG. 7, the portion where the vibration amplitude of the wire 21 is maximized is removed above the workpiece 22 by moving the upper machining liquid nozzle 23 and the upper support portion 24 upward. However, since the vibrating portion of the wire 21 is located on the upper surface of the work 22, the upper surface and the lower surface of the work 22 are processed with different dimensions. As a result, a vertical dimension error 6 defined by a dimensional difference between the upper surface and the lower surface of the workpiece 22 occurs.

  The straightness error is defined as the larger one of the vertical dimension error 6 and the above-described Tyco error 5. In the present embodiment, the straightness error can be suppressed and the straightness accuracy can be improved by suppressing both the Tyco error 5 and the vertical dimension error 6.

  As described above, the wire electric discharge machining apparatus according to the present invention is useful for improving straightness accuracy in wire electric discharge machining of a workpiece.

1,21 Wire 2,22 Workpiece (Workpiece)
2a Finished surface 3,23 Processing liquid nozzle 3a Upper processing liquid nozzle 3b Lower processing liquid nozzle 4,24 Support part 4a Upper support part 4b Lower support part 5 Tyco error 6 Vertical dimension error 7 Straightness error 11 Voltage application part 12 Moving means

Claims (6)

A wire electric discharge machining apparatus for machining a workpiece by electric discharge from wires extending vertically,
A voltage application unit for applying a machining voltage to the wire;
An upper support for supporting the wire above the workpiece;
A lower support portion for supporting the wire below the workpiece;
One of the support portions is moved in a direction along the wire and away from the workpiece, and the support portion is in a direction substantially perpendicular to the finished surface of the workpiece and the workpiece And a moving means for moving in a direction away from the wire electric discharge machining apparatus.   The wire electric discharge machining apparatus according to claim 1, wherein the moving unit moves the upper support portion. A wire electrical discharge machining method for machining a workpiece by electrical discharge from a vertically extending wire,
An upper support portion for supporting the wire above the workpiece or a lower support portion for supporting the wire below the workpiece in a direction along the wire and away from the workpiece. A wire electric discharge machining method characterized by moving the support portion in a direction substantially perpendicular to a finished surface of the workpiece and away from the workpiece.   The wire electric discharge machining method according to claim 3, wherein the movement of the support part along the wire is an upward movement of the upper support part.   5. The wire electric discharge machining method according to claim 4, wherein an upward movement distance of the upper support portion is equal to or more than ¼ of a plate thickness of the workpiece in a direction along the wire.   The moving distance of the upper support portion in a direction substantially perpendicular to the finished surface of the workpiece is a distance in which the distance between the upper end of the workpiece and the wire is 3 to 5 μm. The wire electric discharge machining method according to claim 4 or 5.

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