JP2806955B2 - 3D tool compensation method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a three-dimensional tool correction method for determining an offset tool path of a three-dimensional spline curve, and particularly to a method of offsetting a three-dimensional spline curve by a simple program command. The present invention relates to a three-dimensional tool correction method for obtaining a path.

[Conventional technology]

In general, for a curve that cannot be represented by a mathematical expression, for example, a model shape, necessary points are given, these points are smoothly connected by a spline curve, the spline curve data is stored in a memory, and the spline curve data is used. Processing. In particular, three-dimensional spline curves are widely used.

[Problems to be solved by the invention]

On the other hand, even if a spline curve is obtained, it is necessary to program a three-dimensional tool correction for actual machining. In general, in two-dimensional tool correction, an offset vector is calculated inside a CNC (numerical control device) based on an offset amount and a tool correction command based on a simple G code command, and a tool center path can be obtained.

However, in the three-dimensional tool correction, the offset vector cannot be easily calculated inside the CNC, and generally, the machining is performed by instructing the offset vector in each block. Also, using other automatic program creation devices, etc.,
Although it is possible to calculate the offset vector of each block once, it is economically expensive.

The present invention has been made in view of such a point,
It is an object of the present invention to provide a three-dimensional tool correction method for obtaining an offset tool path of a three-dimensional spline curve with a simple program command.

[Means for solving the problem]

In the present invention, in order to solve the above problem, in a three-dimensional tool correction method for generating a spline curve in a three-dimensional space and obtaining an offset path of a tool of the spline curve, a point on the spline curve, An offset vector that is on a plane defined by a point before the point and a point next to the point and that is orthogonal to the spline curve at a point on the spline curve and that has a specified offset amount is determined. , A three-dimensional tool correction method for determining an offset path of a tool from the offset vector is provided.

Also, in a three-dimensional tool correction method for generating a spline curve in a three-dimensional space and determining a tool offset path of the spline curve, a point on the spline curve, a point before the point, and the point On a plane defined by the following points, and at a point on the spline curve:
A three-dimensional orthogonal to a straight line connecting the point before the point and the point next to the point, obtaining an offset vector having a specified offset amount, and obtaining an offset path of the tool from the offset vector Tool compensation method is
Provided.

[Action]

A plane is defined by three points before and after the three-dimensional spline curve, and a vector on this plane and having a direction orthogonal to the spline curve is defined as an offset vector. By calculating this in the numerical controller, there is no need to issue an offset command in each block.

A plane is defined by three points before and after the three-dimensional spline curve, and a straight line connecting the point before and after the point for obtaining the offset vector on this plane is obtained, and a direction orthogonal to this straight line is obtained. And a vector having an offset amount instructed. By calculating this in the numerical controller, there is no need to issue an offset command in each block.

〔Example〕

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows a conceptual diagram of the three-dimensional tool correction system of the present invention. The spline curve Ls has given points P ₁ , P ₂ , P ₃ , P _4.
···, P _n-1 , Pn

The next instruction is at the origin P _0.

G41 Ii Jj Kk Dd; Here, G41 is a three-dimensional tool correction start command, and this G command is modal, and the next tool correction cancel command
Effective until commanded by G40. That is, at the starting point,
Since the spline curve Ls has not been determined, an offset vector is specified. i, j, and k are offset vectors in the X, Y, and Z-axis directions, respectively, and d is an offset amount, which is usually a radius of a tool. Here, it is assumed that the spline curve is separately obtained, and XY
The command for the Z movement amount is omitted.

At the next point P ₂ , a spline curve is determined from the points P ₁ , P _2, and P _{3. The} spline curve lies in a plane defined by the three points, and is perpendicular to the spline curve Ls at the point P ₂ and the offset amount is d. the vector V ₂ calculated by CNC internal. Similarly, the vector
V ₃ and V ₄ are obtained, and an offset tool path Lc is obtained. However, here, the direction of the adjacent vector needs to be 90 ° or less.

At the end point Pn, a plane is determined from the three points Pn, Pn _-1 and Pn _-2 , and a vector perpendicular to the spline curve is calculated at the point Pn.

By performing spline interpolation on the points at the tip of these offset vectors, it is possible to determine the offset tool path of the three-dimensional spline curve. By performing this calculation inside the CNC, it is necessary to specify the offset vector in each block. And the machining program is simplified.

Next, a second example of obtaining an offset vector will be described. FIG. 2 is an explanatory diagram for obtaining a second offset vector. Here obtains the offset vector V _m at the point P _m. By three points P _m-1 , P _m , and P _{m + 1} ,
The plane Sm is determined. Here, a straight line L _m connecting the points P _m-1 and P _{m + 1}
, And a vector V _m perpendicular to the straight line L _m and having an offset amount d is obtained. If this is obtained for each point, a corrected tool path Lc is obtained.

When the three points P _m−1 , P _m , and P _{m + 1} are on one straight line, the plane Sm is not determined, so the plane is determined from the straight line and the previous offset vector V _m−1. Decide.

Also in this example, it is necessary to specify an offset vector at the start point in the same manner as in the above example. In addition, at the end point,
An offset vector perpendicular to a straight line connecting the end point and the point immediately before the end point is obtained.

Further, a third example of obtaining an offset vector will be described. FIG. 3 is a diagram for explaining a third example of obtaining an offset vector. Here, it obtains the offset vector V _q in terms P _q on the spline curve Ls. point
A plane Sq determined by P _q−1 , P _q , and P _{q + 1} is determined. In addition, this 3
Determining an offset vector V _q in the normal direction of the arc which is determined by the point. Here, the spline curve Ls and the arc determined by the three points are represented as the same curve, but the spline curve and the arc do not actually match.

Further, similarly to the second example, when the points P _q−1 , P _q , and P _{q + 1} are on the same straight line, they cannot be determined, so that the straight line and the previous offset vector V _q−1 are used. Determine the plane. Further, since a circle is not determined, a vector orthogonal to a straight line determined by the three points is set as an offset vector.

Further, at the starting point, an offset vector is commanded as in the first and second examples. At the end point, an arc is determined by three points: an end point, a point before the end point, and a point two before the end point.

Next, hardware for implementing the present invention will be described. FIG. 4 is a hardware configuration diagram of a numerical controller (CNC) for implementing the present invention. In the figure,
The processor 11 controls the whole according to a control program stored in the ROM 12. Coprocessor 11a
Executes a calculation of a vector or the like exclusively in accordance with a command from the processor 11. The RAM 13 stores various calculation data. The nonvolatile memory 14 stores a processing program 14a, parameters, and the like, and uses a battery-backed CMOS or the like.

The PMC (programmable machine controller) 15 receives commands such as the M function and the T function, converts them into signals for controlling the machine tool by the sequence program 15a, and outputs the signals to the machine control circuit. In addition, a signal is received from the machine control circuit side to perform processing, and a part thereof is read by the processor 11. The display control circuit 16 converts a digital signal into a display signal. The display device 16a receives the display signal and displays a machining program, a coordinate position, and the like. As the display device, a CRT, a liquid crystal display device, or the like is used. The keyboard 17 is used for inputting various data.

The position control circuit 18 is a circuit for controlling the servo motor 20, and the servo amplifier 19 drives the servo motor 20 in response to a command from the position control circuit 18. The servomotor 20 is provided with a tachometer 21 for speed feedback and a position detector 22 such as a pulse coder and an optical scale.
These components are required for the number of axes, but since the configuration of each axis is the same, only one axis is described here.

The input / output circuit 23 transmits and receives digital signals to and from the outside, and is connected to the machine-side control circuit. Manual pulse generator 24
Is used to digitally move each axis and is mounted on a machine operation panel.

Here, there is one processor, but a multi-processor system using a plurality of processors may be used depending on the system.

〔The invention's effect〕

As described above, in the present invention, the offset vector is calculated from the points before and after the three-dimensional spline curve in the numerical control device, and the offset tool path is obtained. Is unnecessary, and creation of a machining program is simplified.

Further, an expensive automatic program creating device is not required for creating a program.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of the three-dimensional tool correction method of the present invention, FIG. 2 is an explanatory diagram of a second example for obtaining an offset vector, and FIG. 3 is an explanatory diagram of a third example for obtaining an offset vector. FIG. 4 shows a numerical controller (CNC) for implementing the present invention.
FIG. 2 is a configuration diagram of hardware. 11 Processor 11a Coprocessor 12 ROM 13 RAM 14 Nonvolatile memory 14a Machining program 15 PMC (programmable machine controller) 15a Sequence program 16a Display device 17 ...... keyboard V ₁ ~V _n ...... offset vector P ₁ to P _n ...... Ls ...... spline curve Lc ...... which is offset tool paths point on the spline curve

Continuation of the front page (72) Inventor Kiyoji Ishii 3580 Kobaba, Oshino-za, Oshino-mura, Minamitsuru-gun, Yamanashi Prefecture FANUC Corporation Product Development Laboratory (56) References JP-A-62-264307 (JP, A) (58) Surveyed field (Int.Cl. ⁶ , DB name) G05B 19/404 G05B 19/4093

Claims (4)

(57) [Claims] 1. A three-dimensional tool correction method for generating a spline curve in a three-dimensional space and determining an offset path of a tool of the spline curve, comprising: a point on the spline curve; a point before the point; At a point on the plane defined by the point next to the point, at a point on the spline curve, an offset vector orthogonal to the spline curve and having a specified offset amount is obtained. Tool correction method for finding the offset path of the tool. 2. A three-dimensional offset vector is specified at the start point of the spline curve, and the end point is on a plane defined by an end point, a point before the end point, and a point two before the end point. 2. The method according to claim 1, wherein a vector orthogonal to the curve is set as an offset vector.
Item 3D tool correction method. 3. A three-dimensional tool correction method for generating a spline curve in a three-dimensional space and determining an offset path of a tool of the spline curve, comprising: a point on the spline curve; a point before the point; And on a plane defined by a point next to the point, and at a point on the spline curve, orthogonal to a straight line connecting the point before the point and the point next to the point, the specified offset amount A three-dimensional tool correction method for obtaining an offset vector having a magnitude of: and obtaining an offset path of the tool from the offset vector. 4. A three-dimensional offset vector is specified at the start point of the spline curve, and the end point of the spline curve is on a plane defined by an end point, a point before the end point, and a point two before the end point. 4. The three-dimensional tool correction method according to claim 3, wherein a vector orthogonal to a straight line connecting the end point and a point two points before the end point is set as a tool correction vector.