JPH06214626A - Nc data producing device - Google Patents

Abstract

PURPOSE:To produce the NC data in order to smoothly cut an intersecting line between both curved surfaces. CONSTITUTION:A curved surface generating function 61 produces two or more curved surfaces to be cut, and an intersecting line calculating function 62 calculates the intersecting line between both curved surfaces produced by the function 61. An approaching function 63 adds an approach to make a machining tool approach from the tangent vector direction at the start point of the intersecting line to this start point and also adds a relief to relieve the machining tool in the tangent vector direction at the end point of the intersecting line to this end point respectively. Then an NC data converting function 64 converts the value of the intersecting line obtained by the function 62 and the value added by the function 63 into the NC data. Thus the intersecting line cutting NC data are obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an NC data creating device for a machine tool, and more particularly to an NC data creating device for smoothly cutting a curved line and a line of intersection between curved surfaces.

[0002]

2. Description of the Related Art Conventionally, NC has been used to create machine tool control data.
A data generator is used. Some of the NC data creating devices have a three-dimensional NC data creating function including a cross cutting function. The function of this NC data creation device will be described with reference to FIG. The apparatus first creates a wireframe model based on the input data and creates two curved surfaces, curved surface 1 and curved surface 2. Then, the intersection line (ridge line) where these two curved surfaces intersect is calculated. The intersecting line obtained by this is processed with a ball end mill to finish the ridge line part smoothly. The machining work of the intersection line based on the data created by this NC data creation device is performed by feeding the ball end mill from the start point as shown in FIG. Fast feed to the point) and cutting feed to the start point to start cutting along the feed intersection line.
Then, after going through the intersection line with cutting feed, it is returned to the start point with fast feed.

[0003]

In the NC data creating apparatus described above, when the cutting is advanced from the clearance point to the intersection line start point by cutting feed in the machining cycle, the intersection line is approximately XY.
When it is on a plane (horizontal plane), the ball end mill is approached almost perpendicular to the intersection line. In this case, as shown in FIG. 12, since the ball end mill enters perpendicularly to the intersection line start point, there is a problem that some bite occurs. In addition, as shown in FIG. 13, when the intersection line is a lobe shape, that is, when cutting is performed along the intersection line and then returns to the start point, the tool is approached at the start of the cutting of the intersection line and then advanced along the intersection line. At this time, as shown in the figure, since a tool which is approached in a substantially vertical direction is fed in a horizontal direction on a line of intersection, a considerable vector fluctuation occurs. Similarly, at the end of the cutting of the intersecting line, the tool fed substantially horizontally on the intersecting line is allowed to escape substantially vertically, so that a considerable vector change also occurs. For this reason, due to the delay of the servo system, sagging occurs on the intersection line start side and the intersection line end side (that is, as shown in the figure, there is a trajectory where the tool is approached almost vertically at the intersection line start side and then cut horizontally. However, there is a problem in that the locus of the trace on the end side of the intersection line) and uncut parts occur.

The present invention has been made in order to solve the above problems, and an object thereof is to provide an intersection generated when a tool comes into contact with an intersection line in cutting an intersection line between curved surfaces. It is to eliminate the bite of the tool into the line and form a smooth cutting surface. Further, the present invention is to eliminate the uncut residue caused by the sag of the servo system when the loop-shaped intersection line is cut.

[0005]

In order to solve the above problems, the NC data creating apparatus of the present invention is a curved surface creating means for creating two or more curved surfaces for cutting, and a curved surface created by the curved surface creating means. An intersection line calculating means for calculating mutual intersection lines, an approach of approaching the machining tool from the tangent vector direction at the starting point to the starting point of the intersection line, and a relief for escaping the machining tool toward the tangent vector direction at the ending point of the intersection line And an NC data conversion unit that converts the value of the intersection line obtained by the intersection line creation unit and the value added by the approach unit into NC data for intersecting line cutting. Is characterized by.

[0006]

The NC data creating apparatus of the present invention first creates a wire frame model from the cross-sectional shape input by the curved surface creating means and creates two curved surfaces. Next, the intersecting line calculating means calculates the intersecting line between the two curved surfaces obtained by the curved surface generating means. Then, the approach means calculates the approach of approaching the machining tool from the tangent vector direction at the start point to the intersection line cutting start point and the escape at which the machining tool escapes to the end point of the intersection line in the tangent vector direction at the end point. Is added to the calculated intersection line. Finally, the NC data conversion means sets the value of the intersection line obtained by the intersection line creation means and the value added by the approach means to the intersection line cutting NC.
Convert to data.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, reference numeral 12 is an NC data creating device,
20 is a machining center type machine tool, and 10 is a numerical controller for controlling the machine tool 20 based on the data created by the NC data creating device. The numerical controller 10 includes servo motor drive circuits DUX, DUY, D
The UZ and sequence controller 11 are connected via an interface (not shown).

On the other hand, the machine tool 20 includes a work table 25 for supporting a work W by the rotation of servo motors 21, 22, 23 driven by the servo motor drive circuits DUX, DUY, DUZ, and a spindle. The relative position between the spindle 26 driven by the motor SM and the spindle head 24 that hangs the spindle 26 is three-dimensionally changed. Further, 27 is a tool magazine that holds a plurality of types of tools, and a tool required for the next process is taken out by a magazine indexing device (not shown) and a tool exchanging device 28 to remove the spindle 26.
The tool previously mounted on the spindle is returned to the magazine, and the workpiece W is processed by the tool mounted on the spindle.

The sequence controller 11 is connected to an NC data generator 12 and a spindle motor drive circuit 15 for controlling the rotation speed of the spindle motor SM. This N
The C data creating device 12 includes a microprocessor 12a, a clock signal generating circuit 12b, a ROM 12c, and a RAM 12
d, fixed disk 12e, interfaces 12f, 12
The interface 12 is mainly composed of g and 12h.
A keyboard 13 and a CRT display device 14 are connected to h. Information for the NC data creating device 12 to perform processing is stored in the fixed disk 12e, and the NC data creating device creates desired NC data according to the value input from the keyboard 13 based on the information.

FIG. 2 shows an NC data generating device 12 of this embodiment.
Each function of is shown. This NC data creation device has a curved surface creation function 61 that creates two curved surfaces from an input cross section, an intersection line calculation function 62 that calculates an intersection line where two or more curved surfaces intersect, and an approach that adds an approach vector to the intersection line. Function 6
3 and an NC data conversion function 64 for converting the value of the intersecting line into NC data.

First, the curved surface creation function 61 creates a wire frame model from the input cross-sectional shape and creates the curved surface 1 and the curved surface 2 shown in FIG. Next, the intersection calculation function 62
The intersection line where the two curved surfaces created by the curved surface creation function 61 intersect is calculated. Then, the approach function 63 adds movement to the start point and the end point of the intersection calculated by the intersection calculation function 62 to move by the clearance in the approach vector direction described later with reference to FIGS. 5 and 6. The NC data conversion function 64 calculates the movement of the clearance and the calculated intersection line value.
Converts into NC data for machine tools for cutting the intersection line of the curved surface. The processing procedure by the approach function 63 and the NC data conversion function 64 will be described with reference to the flowchart of FIG. In the present embodiment, the case where the intersection line is looped, that is, the start point and the end point of the intersection line coincide will be described as an example.

First, the approach function 63 is performed in step 71.
The intersection line point group calculated by the intersection line calculation means is obtained. The calculated intersection line points are P [1], P [2], P
Let [3], ... P [n] be expressed by the following quadratic interpolation formula. The interpolation formula is composed of three points in the intersection line group. P (ξ) = [{P [2k−1] −2P [2k] + P [2k + 1]} / 2] · ξ ² + [{P [2k + 1] −P [2k−1]} / 2] ξ + P [2k ] (Formula 1) Here, k = 1, 2, 3, ... {n-1} /2-1.0≤ξ≤1.0

The approach function 63 then proceeds to step 72.
The approach side approach vector for approaching the machining tool to the start point of the intersection line and the retreat side approach vector for letting the machining tool escape from the end point of the intersection line are calculated. In the present embodiment, these approach vectors are 3 on the side of the starting point of the intersection line.
The vector of the tangent line of the start point and the end point is obtained from each of the three points on the point side and the end point side. To obtain the tangent vector, (Equation 2) is obtained by differentiating the above (Equation 1). P ′ (ξ) = {P [2k−1] −2P [2k] + P [2k + 1]} · ξ + {P [2k + 1] −P [2k−1]} / 2 (Equation 2)

Substituting k = 1 and ξ = -1.0 into (Equation 2) to obtain the tangent vector at the intersection start point, the following (Equation 3) is obtained. P '(-1.0) =-{P [1] -2P [2] + P [3]} + {P [3] -P [1]} / 2 = -3 / 2 · P [1] + 2P [2] -1 / 2 · P [3] (Equation 3)

Similarly, when k = {n-1} / 2 and ξ = 1.0 are substituted into (Equation 2) to obtain the tangent vector at the intersection line end point, the following (Equation 4) is obtained. P ′ (1.0) = {P [n−2] −2P [n = 1] + P [n]} + {P [n] −P [n−2]} / 2 = −1 / 2 · P [N-2] -2P [n-1] + 3/2 · P [n] (Equation 4)

Next, at step 73, the approach function 63
Calculates the approach point from the tangent vector calculated based on the above equation, and adds the movement of the machining tool in the approach vector direction by the clearance to the start point and the end point of the intersection line. This approach point is based on (Equation 3) and (Equation 4) above.
From the above, assuming that the approaching unit approach vector is Vs, the retreating unit approach vector is Ve, and the clearance is C, it is represented by the following (Equation 5) and (Equation 6). Approach side approach point Ps = P (1) -CVs ... (Equation 5) Retreat side approach point Pe = P (n) + CVe ... (Equation 5)

The contents of (Equation 5) and (Equation 6) will be further described with reference to FIGS. In FIG. 5, the tangent vector at P [1] at the starting point P [1] of the intersection line as shown in (Equation 5) |
CVs | is added to define the approach point Ps on the approach side. Similarly, FIG. 6 shows the end point P of the intersection line as shown in (Equation 6).
The tangent vector | CVe | in P (n) is added to (n) to define the backward approach point Pe.

Finally, at step 74, the NC data conversion function 64 sets the value of the intersection point group to which the movement for moving the clearance shown in FIGS. 5 and 6 is added to the intersection line (ridge line) of the workpiece.
The NC data is completed by converting it into NC data for cutting. Here, the machine tool 20 based on the NC data
The processing operation by will be described. First, the machine tool 20
4 uses a ball end mill having a relatively large diameter to drive the servomotors 21, 22, 23 to change the relative position between the work table 25 that supports the work W and the spindle head 24. The curved surface 1 and the curved surface 2 shown in are cut.

Next, the process of finishing the intersection line (ridge line) of the curved surface is started. The machine tool 20 uses the tool changing device 28 to replace the ball end mill having a relatively large diameter with a ball end mill having a small diameter for intersecting line finishing. Then, this approach in which the ball end mill is approached to the intersection of curved surfaces will be described with reference to FIG. 7. First, at the approach point Ps on the approach side described in FIG.
From the start point, the tool (ball end mill) is fast-forwarded on the Z axis. Then, the tool is fed by cutting feed from the approach point Ps to the start point along the tangential direction, and the machining of the intersecting line is started. When the machining of the intersecting line is completed, the tool is released from the end point in the tangential direction to the retract side approach point Pe described in FIG. From this approach point Pe, the tool is fast-forwarded on the Z-axis and then moved on XY to return to the start point. In the above description, an example of cutting the intersection line of two curved surfaces has been described, but the present invention can be used for cutting the intersection line of three or more curved surfaces, and is used not only for the intersection line of curved surfaces but also for general curved surface processing. be able to. This example will be described with reference to FIGS.

FIG. 8 shows an approach method in conventional curved surface processing. First, from the start point, send the machining tool by rapid feed to the clearance point where clearance is increased from the curved surface end Es, then feed by cutting feed to the curved end Es, and then cut feed along the curved surface to the other curved end Ee. After sending, it escapes from the Ee by fast-forwarding on the Z-axis. Then, place the processing tool on the curved surface end Es' adjacent to the curved surface end Es until X
Send on Y-axis.

FIG. 9 shows an approach method for curved surface processing according to this embodiment. The NC data creation apparatus of this embodiment performs an approach side approach point P's from the tangential direction to the end point E's on the starting point side of cutting and an end point P's by the processing substantially similar to that described with reference to FIGS. NC data to which a receding side approach point P′e in the tangential direction from the side end E′e is added is created. Based on this, in the present embodiment, the machining tool is fast-forwarded from the start point on the Z-axis to the approach-side approach points P and s, and then cutting feed is made to approach the end E's on the start point side from the tangential direction to perform cutting. To start. At the end of cutting of the part,
The tool is released from the end portion E'e on the end point side in the tangential direction to the approach point P'e on the retreat side. And the approach point P'e
To the position on the approach point P "s' adjacent to the approach point P's adjacent to the approach side P's" on the XY axes, and then the tool is fed in the same manner to cut the adjacent part. According to this embodiment, it is possible to prevent the drooling caused by the plunging of the tool, which has conventionally occurred when the curved surface is cut.

[0022]

According to the present invention, when cutting a line of intersection between curved surfaces, the starting point of cutting is approached from the tangential direction of the starting point, so that the tool touches the line of intersection. It is possible to form a smooth cutting surface without biting of the tool into the intersection line. Further, according to the present invention, when cutting a loop-shaped intersection line, since the vector in the cutting direction does not change suddenly at the start point and the end point of the intersection line cutting, the servo system does not sag, and the uncut portion caused by this sag Can be eliminated.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing configurations of an NC data creation device and a machine tool.

FIG. 2 is a block diagram of functions of the NC data creation device according to the present embodiment.

FIG. 3 is a flowchart showing a processing procedure by an approach function 63 and an NC data conversion function 64 of the NC data creating apparatus of the embodiment of FIG.

FIG. 4 is an explanatory diagram of an intersection line processed by data created by the NC data creating device according to the embodiment of this invention.

5 is an explanatory diagram of an approach point on the approach side to the intersection line start point in FIG. 4;

6 is an explanatory diagram of a backward approach point from the end point of the intersection line in FIG. 4;

FIG. 7 is an explanatory diagram of an approach using a ball end mill for cutting the intersecting line of the present embodiment.

FIG. 8 is an explanatory view of a trajectory of a ball end mill during conventional curved surface processing.

FIG. 9 is an explanatory view of the trajectory of the ball end mill during curved surface processing according to another embodiment of the present invention.

FIG. 10 is an explanatory diagram of a curved surface processed by a conventional NC data creation device.

FIG. 11 is an explanatory view of a conventional approach using a ball end mill for cutting a line of intersection.

FIG. 12 is an explanatory view of a conventional approach using a ball end mill that cuts a line of intersection.

FIG. 13 is an explanatory view of a conventional approach using a ball end mill for cutting a line of intersection.

[Explanation of Codes] 10 Numerical Control Device 12 NC Data Creation Device 12a Microprocessor 12e Fixed Disk 20 Machine Tool 61 Curved Surface Creation Function 62 Intersection Line Calculation Function 63 Approach Function 64 NC Data Conversion Function

Claims (1)

[Claims] 1. A curved surface creating means for creating two or more curved surfaces to be cut, an intersecting line calculating means for calculating an intersecting line of curved surfaces created by the curved surface creating means, and a starting point at the starting point of the intersecting line. An approach for approaching the machining tool from the tangent vector direction, and an approach means for adding an escape for escaping the machining tool in the tangential vector direction at the end point of the intersection line, and an intersection line obtained by the intersection line creation means. An NC data creating device comprising: an NC data converting unit that converts a value and a value added by the approaching unit into NC data for intersecting line cutting.