JPH04217007A - Working path forming device - Google Patents

Abstract

PURPOSE:To prevent the occurrence of a dropped part or unmachined part in a working path between adjacent curved surfaces in accordance with the shape of each kind of tool. CONSTITUTION:An R-curved surface forming processing section 8 forms a new curved surface composed of a spatial extent in which the central point of a tool can exists when the tools is set so that the edge of the tool can come into contact with the boundary line or corner point of a curved surface to be worked. Then an R-curved surface interference avoidance processing section 10 avoids the interference of a working path with the new curved surface. Therefore, the definition of the curved surface or designation of an area to be worked by an operator for preventing the occurrence of a dropped part of unmachined part in a working path becomes unnecessary and the reliability and working efficiency are improved.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a machining path generation device, and more particularly to a machining path generation device for generating a machining path for machining a curved surface with an NC machine tool.

0002

2. Description of the Related Art FIG. 20 is a block diagram of essential parts of an example of a conventional machining path generation device. This machining path generation device uses a keyboard (1), mouse (2), and tablet (
3) Input the coordinate values, etc. of the machining curved surface.

A curved surface definition processing section (4) defines a processed curved surface from definition information such as input coordinate values. The defined curved surface information memory (5) stores curved surface information of defined processed curved surfaces. The machining path generation processing section (56) consists of a basic machining path generation processing section (7) and a curved surface interference avoidance processing section (9),
A machining path for machining the machining curved surface is generated based on the curved surface information.

The basic machining path generation processing section (7) generates a basic machining path that is a basic machining path. A curved surface interference avoidance processing unit (9) determines whether or not the basic machining path generated by the basic machining path generation processing unit (7) interferes with the machining curved surface, and if so, generates a machining path that avoids the interference. generate.

The NC data file (11) stores machining passes generated by the machining pass generation processing section (56) as NC data. The CRT (12) displays the generated machining path to visually show the machining path generation status to the operator.

Next, the operation will be explained. Consider a case where machining paths are generated for two machining curved surfaces S1 and S2 as shown in FIG. 21 in order to perform milling with a machining center, an NC milling device, or the like. First, input the definition information of the machining surfaces S1 and S2 to be machined using the keyboard (1), mouse (2), and tablet (3), as well as the machining method, tool used, finishing allowance, tool pick width, and machining start point. and machining information such as machining direction.

Based on the definition information, a curved surface definition processing section (
In step 4), machining curved surfaces S1 and S2 are defined, and the curved surface information of the defined machining curved surfaces S1 and S2 is stored in the defined curved surface information memory (5). Further, the processing information is also stored in the definition curved surface information memory (5). The curved surface information is CR
The quality is confirmed by displaying on T(12), etc.

Next, based on the curved surface information and processing information,
A machining path is generated by a machining path generation processing unit (56). First, the basic machining path generation processing section (7)
, a basic machining path as shown in FIG. 23 is generated. Figure 22
is the basic machining path generated in the XY plane,
FIG. 23 shows basic machining paths generated within one curved surface. Here, it is assumed that a basic machining path as shown in FIG. 22 is generated.

Next, the curved surface interference avoidance processing section (9) performs
Interference avoidance is performed as follows for each point Pi on the basic machining path. First, a straight line L passing through point Pi and parallel to the Z axis is determined. Next, an offset curved surface s1 is obtained by offsetting the machining curved surface S1 by [tool diameter + finishing allowance] in the normal direction of the machining curved surface S1. Then, the intersection between the straight line L and the offset curved surface s1 is determined, and if there is an intersection, it is determined that there is interference, and if there is no intersection, it is determined that there is no interference.

Furthermore, if there is interference, the intersection is regarded as a point on the machining path instead of the point Pi, thereby avoiding the interference. Similarly, interference is avoided for the machining curved surface S2, and the process is performed for all points on the basic machining path.

As described above, each point P on the basic machining path
For i, a machining path (14) that avoids interference as shown in FIG. 24 is generated and output to the NC data file (11). (13) is the tool, and r is the offset width. The machining path (14) traces the offset curved surfaces s1 and s2, but if the adjacent machining curved surfaces S1 and S2 do not touch each other smoothly, the offset curved surfaces s1 and s2 will not contact each other, so the machining path (14) follows the offset curved surfaces s1 and s2. Offset curved surface s1,s
Between 2 and 2, it will fall downward and cause a cut.

Therefore, in order to prevent cutting on adjacent machining curved surfaces, the machining curved surface is defined by extending the machining curved surface end in the tangential direction of the machining curved surface, or the machining area is specified and the machining path (
The operation of the tool (13) is restricted so that the tool (14) does not fall. FIG. 25 also shows an example in which the machining path falls between adjacent machining curved surfaces S1 and S2.

[0013] Another conventional example is Japanese Patent Application Laid-Open No. 1-2889.
One example is the "numerically controlled processing device" disclosed in Japanese Patent No. 08. In this numerically controlled machining device, a tubular offset surface and a spherical offset surface are generated for the boundaries and end points of adjacent machining curved surfaces, respectively, to prevent the machining path from falling on the adjacent machining curved surfaces.

[0014]

Problems to be Solved by the Invention In the conventional machining path generation apparatus, there is a problem in that defining a machining curved surface and specifying a machining area in order to prevent the machining path from collapsing on an adjacent machining curved surface is troublesome and easy to make mistakes. Further, the numerically controlled machining apparatus cannot handle various tool shapes other than ball end mills, and there is a problem in that uncut parts may be left when a flat end mill is used, for example.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a machining path generation device that is easy to operate, is compatible with various tool shapes, and can prevent machining path depressions and uncut parts between adjacent machining curved surfaces. .

[0016]

[Means for Solving the Problems] The machining path generation device of the present invention includes a curved surface defining means for defining a curved surface, and a curved surface defining means for defining a curved surface. Boundary surface generation means that generates a curved surface consisting of a spatial range in which the center point of a tool can exist, and the center of the tool when the tool cutting edge is placed so as to be in contact with a corner point that is a corner of the curved surface. corner curved surface generation means for generating a curved surface consisting of a spatial range in which points can exist; basic machining path generation means for generating a basic machining path that is a basic machining path for machining the curved surface; Curved surface interference avoidance means for avoiding interference when a path interferes with a curved surface, and also for each curved surface generated by the boundary curved surface generation means and the corner curved surface generation means when the curved surface interference avoidance means avoids interference. The configuration is characterized in that it includes R-curved surface interference avoidance means for avoiding interference.

[0017]

[Operation] In the machining path generating device of the present invention, a curved surface is defined by the curved surface defining means. The boundary curved surface generation means generates, for a boundary line that is an end of the curved surface, a curved surface consisting of a spatial range in which the center point of the tool can exist when the tool cutting edge is arranged so as to be in contact with the boundary line. Further, the corner curved surface generation means generates a curved surface consisting of a spatial range where the center point of the tool can exist when the tool cutting edge is arranged so as to be in contact with the corner point of the curved surface. Ru.

When the basic machining path generated by the basic machining path generating means interferes with a curved surface, the interference is avoided by the curved surface interference avoidance means, and each of the basic machining paths generated by the boundary curved surface generating means and the corner curved surface generating means is If there is interference with the curved surface, the interference is avoided by the R curved surface interference avoidance means. Therefore, a machining pass is generated in which interference is avoided according to the tool shape at the boundary of the curved surface where there is a possibility that the machining pass may drop and cut.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained in more detail below based on embodiments shown in the drawings. Note that this invention is not limited to this. FIG. 1 is a block diagram of main parts of a machining path generation device according to an embodiment of the present invention. The same reference numerals as in FIG. 20 indicate the same or similar components.

In this machining path generation device, a machining path generation processing section (6) includes a basic machining path generation processing section (7) and a curved surface interference avoidance processing section (9) similar to the conventional example, as well as an R curved surface generation processing section (6). It includes a processing section (8) and an R-curved surface interference avoidance processing section (10).

The R curved surface generation processing unit (8) generates a curved surface ( (hereinafter referred to as a boundary surface). In addition, when the tool is placed so that the tool cutting edge touches the corner point of the machining curved surface, the curved surface (
Hereinafter, this will be referred to as a corner curved surface. ) is generated. The boundary curved surface and the corner curved surface are collectively referred to as an R-curved surface.

There are three types of tools for machining curved surfaces: a ball end mill, a flat end mill, and a flat end mill with radius, as shown in FIGS. 2, 3, and 4, respectively. rb is the ball end mill component radius, rf is the flat end mill component radius, and tc is the tool center.

When the tool is a ball end mill, FIG.
As shown, the boundary curved surface (15) is the processed curved surface (16)
It becomes a tubular shape whose center is the boundary line (17) of , and whose radius is the ball end mill component radius rb. The boundary line (18a) of the offset curved surface (18), which is obtained by offsetting the processed curved surface (16) by the offset width rb in the normal direction, is the boundary line (18a) of the processed curved surface (16).
5) Exists above.

Furthermore, as shown in FIG. 6, the corner curved surface (1
9) has a spherical shape whose center is the corner point (20) of the machined curved surface (16) and whose radius is the ball end mill component radius rb. The corner point (18b) of the offset curved surface (18) is
Exists on the corner curved surface (19). FIG. 7 shows a boundary curved surface (15) and a corner curved surface (19) when the tool is a flat end mill.

FIGS. 8, 9, and 10 are explanatory diagrams of the R curved surfaces of a ball end mill, a flat end mill, and a flat end mill with an R. R curved surface interference avoidance processing unit (1
0) executes machining path interference avoidance processing on the R-curved surface generated by the R-curved surface generation processing section (8).

Next, the operation will be explained. Consider the case where machining passes for two machining curved surfaces S1 and S2 as shown in FIG. 21 are generated. First, input the definition information of the machining surfaces S1 and S2 to be machined using the keyboard (1), mouse (2), and tablet (3), as well as the machining method, tool used, finishing allowance, tool pick width, and machining start point. and machining information such as machining direction.

Based on the definition information, the curved surface definition processing section (
In step 4), machining curved surfaces S1 and S2 are defined, and the curved surface information of the defined machining curved surfaces S1 and S2 is stored in the defined curved surface information memory (5). Further, the processing information is also stored in the definition curved surface information memory (5). The curved surface information is CR
The quality is confirmed by displaying on T(12), etc. Then, a machining path is generated by a machining path generation processing section (6) based on the curved surface information and machining information.

The operation of the machining path generation processing section (6) will be explained based on the flowchart shown in FIG. First, in step (21), the basic machining path generation processing section (
7) generates a basic machining path as shown in FIG. 22, and determines each point Pi on this basic machining path.

Next, the R curved surface generation processing section (8), the curved surface interference avoidance processing section (9), and the R curved surface interference avoidance processing section (10)
Interference avoidance processing is executed by In step (22), it is checked whether the point Pi interferes with one machining curved surface Si. If it is determined that there is interference, step (2)
3), the process proceeds to step (24), and if it is determined that there is no interference, the process proceeds from step (23) to step (25). In step (24), a point on the machined curved surface Si where interference is avoided is found, and that point is set as a new point Pi. Then, proceed to step (25).

In step (25), it is determined whether the interference avoidance process has been executed for all the machined curved surfaces regarding the point Pi. If not yet, the next processed curved surface Si is determined in step (26), and the processing from step (22) onwards is executed. Then, when the interference avoidance process has been executed for all the machined curved surfaces, the process proceeds to step (27). In step (27), point Pi is determined as the point where interference is avoided, and a machining path is generated up to that point Pi.

In step (28), it is determined whether all points on the basic machining path have been processed. If not yet, execute the process from step (21) onwards. The operation ends when all points on the basic machining path have been executed. In this way, a machining path that avoids interference is generated and output to the NC data file (11).

The interference check process in step (22) will now be described in more detail with reference to FIG. 12. In step (29), point P on the basic machining path
Find a straight line L that passes through i and is parallel to the Z axis. Step (30
), the machining curved surface Si is offset in consideration of the tool shape, and the curved surface is set as the offset curved surface si, and the straight line L
Find the intersection z1 with If the point on the processed curved surface Si is P, then the point p on the offset curved surface si is (P, p are three-dimensional vectors.)

[0033]

[Math 1]

It is obtained as follows. Note that when nxy=0, a term including rf is not added to the calculation. And Figure 1
As shown in 3, the intersection point z of the straight line L and the offset curved surface si
Find 1. This intersection z1 is determined, for example, by Newton's method.

L: Pi=at+b, where a and b are constants, and t is a parameter. Si: q=Si(U,V) However, q is a three-dimensional vector, and U, V are curved surface parameters. is obtained by solving three-dimensional simultaneous equations regarding the straight line L and the offset curved surface si.

In step (31), an R curved surface Ri is generated for the processed curved surface Si. First, the boundary curved surface Ri will be described. As shown in FIG. 14, a point on the boundary line of the processed curved surface Si is Rc, a tangent vector in the boundary line direction at the point Rc is A, and R is a three-dimensional vector indicating a point on the boundary curved surface Ri.

Assuming that the tool is a flat end mill with an R, Rw represents the locus that the center of the tool traces around the tangent vector A when the tool is placed so that the cutting edge of the tool contacts the point Rc. In order to avoid the boundary line of the machining curved surface Si from tool interference, it is sufficient to cover the boundary line with a curved surface obtained by sweeping the trajectory Rw along the boundary line. That is, a curved surface obtained by sweeping the locus Rw along the boundary line is defined as a boundary curved surface Ri.

Let w be the parameter for the direction of rotation around the tangent vector A, and the point Rc changes according to the change in the parameter w.
Assuming that the normal vector M in changes, the normal vector M is as follows: M=f(A,w) where f is a function including rotational transformation. It can be expressed as From this, the point R on the boundary curved surface Ri is

[0039]

[Math 2]

It is obtained as follows. Note that when mxy=0, a term including rf is not added to the calculation. The number 2 is rb=0
Alternatively, by setting rf=0, it can also be applied to a flat end mill or a ball end mill.

Here, if the parameter along the boundary line of the machined curved surface Si is b, then the point Rc is a function of the parameter b. Since the tangent vector A is also along the boundary line of the machined curved surface Si, it is a function of the parameter b. Therefore, the normal vector M is also a function of the parameter b.

Therefore, since the variables on the right side of Equation 2 are all functions of the parameters b and w, the point R on the boundary surface Ri
is R=Ri(b,w), and is expressed as a function of two parameters b and w.

Next, regarding the corner curved surface, the corner point is Q=Si(u0, v0), where Q is a three-dimensional vector and u0, v0 are constants. Since it can be expressed as It is generated as a function of θ and φ.

FIGS. 15, 16, and 17 show the corner curved surfaces and parameters θ, φ for ball end mills, flat end mills, and flat end mills with R, respectively.
Indicates the correspondence with Rc is the corner point, and FIGS. 6 to 10
This corresponds to (20). In step (32), the intersection z2 between the straight line L and the R curved surface Ri is determined. This intersection z2 is determined by Newton's method in the same manner as in step (30) above, since equations (3) and (4) expressing the R-curved surface Ri are both two variables.

In step (33), classification is performed as follows based on the intersection points z1 and z2. Intersection points z1 and z2 cannot be found:
No interference (Step 34) Only the intersection z1 is found: There is interference and the interference point is z1 (Step 35) Only the intersection z2 is found: There is interference and the interference point is z2 (Step 36) The intersection z1,
Find z2: There is interference and the interference point has the larger value of either z1 or z2 (step 37)

As described above, it is checked whether or not there is interference, and if there is interference, the point of interference is determined. Figure 18, Figure 1
9 is an illustrative diagram of a machining path obtained by the aforementioned machining path generation device, and corresponds to FIGS. 24 and 25 in the conventional example. This prevents the tool from falling between the adjacent machining curved surfaces S1 and S2.

[0047] The machining surface Si may be any type of curved surface, such as a machining surface defined from a curve, a machining surface defined from a curved surface, a machining surface defined from a point group, a machining surface defined from a mathematical formula, etc. It may be. The machining path generation device of the present invention may be realized by being built into a CAD/CAM device, an automatic programming device, a numerical control device, or the like.

[0048]

[Effects of the Invention] According to the machining path generation device of the present invention,
At the boundary between curved surfaces where tool interference is likely to occur,
The boundary curved surface generation means generates a curved surface where the center of the tool exists when the tool is arranged so that the tool cutting edge touches the boundary line of the curved surface, and the corner curved surface generation means causes the tool cutting edge to touch the corner point of the curved surface. A curved surface where the center of the tool exists when the tool is placed is generated. Since interference is avoided when the basic machining path interferes with each curved surface generated by the boundary curved surface generation means and the corner curved surface generation means by the R curved surface interference avoidance means, various tools based on the machining information can pass machining paths that can avoid interference. is generated. It also eliminates the need for the operator to define curved surfaces and specify machining areas to prevent machining path depressions and uncut parts, improving reliability and work efficiency.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of main parts of a machining path generation device according to an embodiment of the present invention.

FIG. 2 is a side view of the ball end mill.

FIG. 3 is a side view of the flat end mill.

FIG. 4 is a side view of a flat end mill with an R.

FIG. 5 is an exemplary diagram of a boundary curved surface of the ball end mill according to the apparatus of FIG. 1;

6 is an exemplary diagram of a corner curved surface of the ball end mill according to the apparatus of FIG. 1. FIG.

7 is an exemplary diagram of an R curved surface of the flat end mill according to the apparatus of FIG. 1. FIG.

FIG. 8 is an explanatory diagram of an R curved surface of a ball end mill.

FIG. 9 is an explanatory diagram of an R curved surface of a flat end mill.

FIG. 10 is an explanatory diagram of an R curved surface of a flat end mill with an R.

FIG. 11 is a flowchart of machining path generation according to the apparatus of FIG. 1;

FIG. 12 is a flowchart of interference check processing according to the apparatus of FIG. 1;

FIG. 13 is an explanatory diagram for finding interference points.

FIG. 14 is an explanatory diagram of boundary surface generation.

FIG. 15 is a perspective view of a corner curved surface of a ball end mill.

FIG. 16 is a perspective view of a corner curved surface of a flat end mill.

FIG. 17 is a perspective view of a corner curved surface of a flat end mill with an R.

18 is a side view of a machining pass by the apparatus of FIG. 1; FIG.

19 is a side view of a machining pass by the apparatus of FIG. 1; FIG.

FIG. 20 is a block diagram of main parts of an example of a conventional machining path generation device.

FIG. 21 is an illustrative diagram of a shape to be processed.

FIG. 22 is an illustrative diagram of a basic machining path.

FIG. 23 is an illustrative diagram of a basic machining path.

24 is a side view of a machining pass by the apparatus of FIG. 20; FIG.

25 is a side view of a machining pass by the apparatus of FIG. 20; FIG.

[Explanation of symbols]

4 Surface definition processing section 7 Basic machining path generation processing section 8 R surface generation processing section 9 Curved surface interference avoidance processing 10 R curved surface interference avoidance processing section

Claims (1)

[Claims] [Claim 1] A curved surface defining means for defining a curved surface, and a spatial range in which the center point of a tool can exist when a tool cutting edge is arranged so as to be in contact with a boundary line that is an end of the curved surface. Boundary surface generation means for generating a curved surface consisting of;
A corner curved surface generating means for generating a curved surface consisting of a spatial range in which a center point of a tool can exist when a tool cutting edge is arranged so as to be in contact with the corner point of the curved surface; A basic machining path generation means for generating a basic machining path that is a basic machining path for machining, a curved surface interference avoidance means for avoiding interference when the basic machining path interferes with a curved surface, and the curved surface interference avoidance means. A machining path generation device comprising: R curved surface interference avoidance means for avoiding interference with each of the curved surfaces generated by the boundary curved surface generation means and the corner curved surface generation means when avoiding interference.