JPS6351811B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a wire cut taper processing method,
In particular, simultaneous 2-axis control is performed on each of the two control surfaces, and simultaneous 4-axis control is performed as a whole to control the relative movement between the wire and the workpiece. The present invention relates to a wire cut taper processing method capable of performing taper processing with different shapes and lower surface shapes.

As is well known, a wire cut electric discharge machine is a machine in which a wire is stretched between an upper guide and a lower guide, and an electrical discharge is generated between the wire and the workpiece to machine the workpiece, and the workpiece is placed on a table. It is fixed on the top and is moved in the X and Y directions along the machining shape according to commands from the numerical control device. In this case, if the wire is stretched perpendicularly to the table (workpiece), the machining shape of the upper and lower surfaces of the workpiece will be the same, and the upper guide will be moved in the X, Y direction (U
For example, if the upper guide is deflected in a direction perpendicular to the direction of movement of the workpiece and the wire is tilted relative to the workpiece, the shape of the upper and lower surfaces of the workpiece can be changed. So-called taper processing is performed in which the wire processing surface is not the same but is inclined.

FIG. 1 is an explanatory view of such taper processing, in which a wire WR is stretched between an upper guide UG and a lower guide DG at a predetermined angle with respect to the workpiece WK. Now, let the lower surface PL of the workpiece WK be a program shape (the upper surface QU of the workpiece WK may also be a program shape), and also the taper angle α, the distance H between the upper guide UG and the lower guide DG, and the lower surface of the workpiece WK from the lower guide DG. If the distance to h is the bottom surface of the workpiece
The offset amount d ₁ of the lower guide DG and the offset amount d ₂ of the upper guide UG with respect to PL are respectively d ₁ =h・tanα+d/2...(1) d ₂ =H・tanα−h・tanα−d/2= It can be expressed as H・tanα−d ₁ ...(2). Note that d is the processing width.

Therefore, the amount of offset changes depending on the movement of the workpiece.
By controlling the movement of the upper guide UG on which the wire WR is stretched so that d ₁ and d ₂ are constant, taper processing with a taper angle α as shown in FIG. 2 can be performed. In addition, in the figure, the dotted line and the dashed-dotted line are the passages of the upper guide UG and the lower guide DG, respectively. As described above, as a wire cut electric discharge machining command, if the program path on the lower or upper surface of the workpiece, the feed rate on the program path, the taper angle α, the distances H, h, etc. are commanded, machining will be performed according to the command. .

Incidentally, recently there has been a demand for parts whose upper and lower surfaces are completely different in shape, for example, where the upper surface has a straight line and the lower surface has an arc. However, conventional taper processing methods have not been able to process such parts. Therefore, on the same date as the present application, the applicant of the present application has proposed a taper processing method that can perform taper processing in which the top surface shape and the bottom surface shape are completely different. By the way, the proposed taper machining method works when the workpiece is arranged so that its upper and lower surfaces are parallel to the first and second control planes (for example, the XY program plane and the UV lower guide movement plane). It was applicable to In other words, the proposed taper processing method cannot be applied when the workpiece is disposed at an angle with respect to the first and second control surfaces.

Now, in an NC wire-cut electric discharge machine that can perform taper machining, there is a mechanical limit to the size of the taper angle, and as long as the workpiece is placed horizontally, it is not possible to perform taper machining that exceeds the maximum taper angle. However, despite such limitations on the taper angle, some parts may require taper processing to have a taper angle larger than the maximum taper angle. In such a case, move the workpiece (part material) to the control surface (XY program surface or UV lower guide movement surface)
By mounting at an angle rather than parallel to the control surface, the taper angle relative to the control surface is within the limit of the maximum taper angle, and it is possible to perform taper processing on the workpiece that is larger than the maximum taper angle. That is, if taper machining with a taper angle greater than the maximum taper angle determined by the machine is required, the workpiece must be mounted at an angle with respect to the control surface to perform the taper machining. However, with the conventional method and the proposed taper machining method, it is not possible to perform taper machining in which the shape of the top surface of the part and the shape of the bottom surface of the part are different while keeping the workpiece tilted.

In view of the above, the present invention provides a wire cut taper machining method that can perform taper machining in which the top surface shape and the bottom surface shape of the component are different even when the workpiece is mounted at an angle with respect to the control surface. With the goal.

Hereinafter, the present invention will be explained in detail with reference to the drawings.
In the following explanation, the program surface will be referred to as the first control surface or XY program surface, and the surface on which the lower guide moves will be referred to as the second control surface or UV lower guide movement surface, but the method of selecting the control surface is limited to this. figure,
(a) The lower guide moving surface can also be used as the upper guide moving surface.

Figure 3 is an explanatory diagram of the relationship between the control surface and the component surface, where WK is the component, US is the top surface of the component, DS is the bottom surface of the component, WR is the wire, and FCS is the program surface.The first control surface (XY program surface) , SCS is the second control surface (UV lower guide movement surface) that is the movement surface of the lower guide, and the upper surface US and lower surface DS of the component WK are the XY program surface FCS, respectively.
They are arranged parallel to the UV lower guide movement surface SCS.

Figure 4 shows the parts in the first and second positions when the upper and lower surfaces of the parts are circular and square, respectively.
It is an explanatory diagram illustrating the wire path when tilted with respect to the control plane (XY program plane and UV lower guide movement plane). Figure A is a cross-sectional view when parts are arranged at an angle, and Figure C is a 1 is an explanatory diagram of the wire passage on the second control surface. As shown in Figure 4A, the upper surface US and lower surface DS of the part (workpiece) WK are arranged with an inclination of β to the XY program FCS and the UV lower guide movement surface SCS. As a result, the wire path PRP on the XY program plane FCS is not circular but has a distorted shape, and the UV lower guide movement plane
The SCS wire path DGP is also no longer square and has a distorted shape. Incidentally, FIG. 5 shows the wire passages on each control surface when the inclination direction is changed.

Now, in the present invention, the workpiece is
The relative positional relationship data between the workpiece and the first and second control surfaces as well as the top surface shape data and bottom surface shape data of the part are respectively input, and then the part is placed at an angle with respect to the control surface. Find the position of the point (projection point) where the straight line connecting the corresponding points on the top surface and the bottom surface of the component intersects the first and second control surfaces, and then wire the corresponding projection points on the first and second control surfaces. Simultaneous 4-axis control is performed using the position data of each projection point so that the projection points are traced at the same time, and taper machining with different shapes on the top and bottom surfaces of the part is performed, where the taper angle is larger than the maximum taper angle determined by the machine. ing.

FIG. 6 is an explanatory diagram illustrating the taper processing method of the present invention. In the figure, V ₃ is the thickness of the workpiece, and V ₄ is the thickness from the X n axis when the axes X _n , Y _n , and Z _n of the machine coordinate system are taken as shown (however, the _{Y n} axis is perpendicular to the plane of the paper). The distance to the XY program plane FCS, V ₅ is the distance from the X _n axis to the UV lower guide movement surface SCS, V ₆ is the rotation angle when rotating with the Y _n axis as the rotation support axis, V ₇ is the rotation angle when the X _n axis is used as the rotation support axis. This is the rotation angle when rotating as a rotation support shaft. or,
P ₁ is a point on the wire path on the top surface US of the component, P ₂ is a point on the wire path on the bottom surface DS of the component, and the component coordinate system X _p −Y _p −Z _p (however,
Each of these points in Y _p- axis is perpendicular to the plane of the paper)
It is assumed that the coordinates of P ₁ and P ₂ are known and correspond to each other. Furthermore, Q _i and R _i are straight lines connecting the corresponding points P ₁ and P ₂ on the top and bottom surfaces of the component.
The point where P ₁ P ₂ intersects the XY program plane FCS and the UV lower guide movement plane SCS (projection point)
It is.

Now, V ₃ to V ₇ and points P ₁ and P ₂ are known. Therefore, from these values, the XY program plane
Projected point Q _i on FCS and lower guide movement plane SCS,
Coordinates of R _i (XM ₁ , YM ₁ , ZM ₁ ), (XM ₂ , YM ₂ ,
ZM ₂ ), these corresponding projection points Q _i , R _i
(i=1, 2,...) so that XY
The desired part can be obtained by simultaneously controlling two axes of X and Y on the program surface, controlling two axes of U and V simultaneously on the UV lower guide movement surface, and controlling four axes simultaneously as a whole.

Now, the coordinates of points P ₁ and P ₂ in the component coordinate system are (x _p1 , y _p1 , 0) and (x _p2 , y _p2 , −V ₃ ), respectively.
The coordinates of these points P ₁ and P ₂ when converted to the mechanical coordinate system are (x _n1 , y _n1 , z _n1 ) and (x _n2 , y _n2 , z _n2 ). The conversion formula from the component coordinate system (x _p , y _p , z _p ) to the machine coordinate system (x _n , y _n , z _n ) is as follows.

x _n = x _p・cosV ₆ −z _p・sinV ₆ y _n =y _p・cosV ₇ −(x _p・sinV ₆ +z _p・cosV ₆・sinV ₇ ) z _n =y _p・sinV ₇ +(x _p・sinV ₆ +z _p・cosV ₆・cosV ₇ ) (3) However, it is assumed that V ₆ rotations are first performed around the Y _n axis, and then V ₇ rotations are performed around the X _n axis.

Therefore, P ₁ (x _p1 , y _p1 , 0), P ₂ (x _p2 , y _p2 , −
V ₃ ) is converted to the mechanical coordinate system using equation (3) as shown in equations (4) and (5).

x _n1 ＝x _p1・cosV ₆ y _n1 ＝y _p1・cosV ₇ −x _p1・sinV ₆ z _n1 ＝y _p1・sinV ₇ ＋x _p1・sinV ₆ (4) x _n2 ＝x _p2・cosV ₆ ＋V ₃・sinV ₆ y _n2 = y _p2・cosV ₇ − (x _p2・sinV ₆ −V ₃・cosV ₆・sinV ₇ ) z _n2 = y _p2・sinV ₇ + (x _p2・sinV ₆ −V ₃・cosV ₆・cosV ₇ ) (5) Now, the unit vectors i, j, k of the vector P ₁ Qi-→(=B→) are A=√( _n1 − _n2 ) ² + ( _n1 − _n2 ) ² +
( _n1 − _n2 ) ² (6) then i=(x _n1 − x _n2 )/A j=(y _n1 − y _n2 )/A k=(z _n1 − z _n2 )/A (7) . Also, since the Z-axis coordinate ZM ₁ of point Q _i is V ₄ , k・|B|=(V ₄ −z _n1 ) holds true, and the magnitude of vector β is |B|=(V ₄ − z _n1 )・A/(z _n1 −z _n2 ). Therefore, the X-axis and Y-axis coordinate values of the projection point Q _i are XM ₁ ,
YM ₁ and ZM ₁ are respectively XM ₁ = x _n1 + (V ₄ − z _n1 )・(x _n1 − x _n2 )/(z _n1
−z _n2 ) y _n1 + (V ₄ − z _n1 ) · (y _n1 − y _n2 )/(z _n1 − z _n2 ) ZM ₂ = V ₄ (8) and the coordinates of the projection point Q _i are determined. Similarly, each axis coordinate value XM ₂ of the projection point R _i of the UV lower guide movement surface,
YM ₂ and ZM ₂ are XM ₂ = x _n2 + (V ₅ − z _n2 )・(x _n1 − x _n2 )/(z _n1
−z _n2 ) YM ₂ = y _n2 + (V ₅ − z _n2 )・(y _n1 − y _n2 )/(z _n1 − z _n2 ) ZM ₂ = V ₅ (9).

Next, the projection point coordinates (X _i , Y _i ) on the X, Y program plane and the axial components U i , _{V i of} the vector R _i Q _i -→ are determined, and X _i , Y _i , U _i , V _i is stored in memory as NC data. _However , _{X i , Y i , U i} , _and Vi _{are as follows :} .

Then, for all corresponding points on the top and bottom surfaces of the component, using equations (8) to (10), X _i , Y _i ; U _i , V _i
(i=1, 2, 3...) is determined and stored in memory.

If X _i , Y _i , U _i , and V _i at all corresponding points are found,
Create an NC tape using these as NC data and
Using NC tape (tape operation) or reading one block at a time from memory (memory operation),
Controls a wire cut electrical discharge machine using simultaneous 4-axis control.

Next, inputting the shapes of the top and bottom surfaces of the component will be explained. FIG. 7 is a partial plan view of the parts. Now, the line elements in the component top surface shape PUP and component bottom surface shape PDP are respectively G ₁ , G ₃ , G ₅ , G ₇ ; G ₂ , G ₄ , G ₆ ,
G ₈ , and the line elements G ₁ and G ₂ , G ₃ and G ₄ , G ₅ and G ₆ , G ₇
Assuming that G8 and _G8 correspond to each other, the part shape definition program will be as follows. However, it is assumed that points S ₁ to _{S 10} and arcs C ₁ , C ₂ , and C ₃ have already been defined.

G ₁ ; S ₁ , S ₂ , 1 G ₂ ; S ₆ , S ₇ , 1 G ₃ ; C ₁ , CW, S ₂ , S ₃ , 40 G ₄ ; C ₂ , CW, S ₇ , S ₈ , 40 G ₅ ; S ₃ , S ₄ , 1 G ₆ ; S ₈ , S ₉ , 1 G ₇ ; C ₃ , CW, S ₄ , S ₅ , 50 G ₈ ; S ₉ , S ₁₀ , 50 In the above program CW indicates a clockwise circular arc, and the numbers 1, 40, and 50 at the end are the number of divisions of each line element G _i . When the number of divisions is 2 or more
Each division point is determined during the NC data creation process,
For each corresponding division point, X _i , Y _i , U _i ,
V _i is calculated and output as NC data.

FIG. 8 is a block diagram of the present invention, and FIG. 9 is a process flowchart.

An NC data creation program is stored in the ROM 101 in advance. In addition, V ₃ to _{V 7} , the shape data of the top and bottom surfaces of the part (the above-mentioned part shape definition statement)
is read from the tape 102 by the tape reader 103 and stored in the RAM 104. Processing part 1
05 first reads the shape data from the RAM 104 and calculates the coordinates of corresponding points on the top and bottom surfaces of the component through the following steps (a) and (b), and sequentially stores them in the RAM 106.

(b) Determine whether the number of divisions of two corresponding line elements is 2 or more. If it is 1, the end point of each line element is stored in the RAM 106 as the corresponding point coordinates, and the next line element data is read.

(b) If the number of divisions is 2 or more, find the coordinates of the division point of each line element, use them as the corresponding point coordinates, and store them in RAM1.
06 and read the next line element data.
As shown in Figure 10A, if the number of divisions is M and the coordinates of the two points are (x _a , y _a ) and (x _b , y _b ), respectively, then the division point coordinates of the straight line connecting the two points are x _j , y _j (j=1,
2,...M) becomes x _j = x _a + j/M (x _b - x _a ) y _j = y _a + j/M (y _b - _{y a} ). Also, as shown in Figure 10B, θ ₀ is the central angle, r is the arc radius, M is the number of divisions, and θ (= θ ₀ /
M) is the angular increment, and the angle at which the straight line connecting the center C _p and the arc starting point C _s is the X axis, then the coordinates of the dividing point x _j , y _j (j = 1, 2,...M) are x ₁ = x _a , y ₁ = y _a x _j = X _j-1・cosθ−y _j-1・sinθ y _j =x _j-1・sinθ+y _j-1・cosθ.

When the calculation and storage of all corresponding points is completed through the above processing, the processing unit 105 uses each corresponding point to calculate X _i , Y _i , U _i , V _i (i= 1, 2,...) and store this in the RAM 106 as NC data. The shape of the top and bottom surfaces of the parts differs due to the above.
This means that NC data has been created on the RAM 106. Thereafter, NC data is recorded on tape 108 by tape punch 107 to create an NC tape. Incidentally, the NC data may be directly read one block at a time from the RAM 106 and inputted to the NC device 201 to perform the taper process.

As described above, according to the present invention, even if the taper angle is larger than the maximum taper angle determined by the machine when the upper and lower surface shapes of the part are different, the wire can be attached by tilting the workpiece to the control surface. Taper machining is possible by controlling the relative movement between the workpiece and the workpiece using simultaneous 4-axis control, and accurate taper machining can be performed along the wire path set on the top and bottom surfaces of the component, making it possible to perform taper machining using simultaneous 4-axis control. A wire cut taper machining method is provided that can expand the field of application of electrical discharge machines.

[Brief explanation of the drawing]

Figures 1 and 2 are explanatory diagrams of conventional taper processing;
Figure 3 is an explanatory diagram of the relationship between the control surface and the component surface, and Figures 4 and 5 show the relationship between the control surface and the component surface, and Figures 4 and 5 show the wires on the XY program plane and the UV movement plane when the top surface of the component is a circle and the bottom surface of the component is square. Passage explanatory diagram,
Fig. 6 is an explanatory diagram of the taper processing method of the present invention, Fig. 7 is a partial plan view of the part, Fig. 8 is a block diagram of the present invention, Fig. 9 is a flowchart of the NC data creation process, and Fig. 1
Figure 0 is an explanatory diagram of dividing point calculation. WR...wire, WK...component, US...top of the component, DS...bottom of the component, FCS...XY program surface, SCS...UV lower guide movement surface.

Claims (1)

[Claims] 1 In a wire cut taper machining method in which a predetermined taper machining is performed on a workpiece by controlling the relative movement between the wire and the workpiece by simultaneously controlling two axes on two control planes and controlling the relative movement between the wire and the workpiece by simultaneous four-axis control as a whole, the workpiece is , and input the relative positional relationship data between the workpiece and the first and second control surfaces as well as the top surface shape data and bottom surface shape data of the part, and Calculate the position of a projected point where a straight line connecting corresponding points on the wire path set on the upper surface and lower surface of the component intersects the first and second control surfaces, and
and a wire cut taper machining method characterized by controlling relative movement between the wire and the workpiece by simultaneous four-axis control based on the position of the projection point on the second control surface.