JPH0488504A - Tool effective position correcting method - Google Patents

Abstract

PURPOSE:To perform grinding at the optimum working angle in accordance with the shape of work by measuring the positions of tool effective points in accordance with plural working angles, storing them as data and always correcting the effective point to a teaching locus. CONSTITUTION:A locus interpolation part 1 moves a grinding stone 14 along the plane to be worked of the work 15 by interpolating taught coordinates. Simultaneously, a locus vector calculation part 2 and a grinding angle calculation part 3 calculate a teaching locus vector Vp, a tool approach vector Va, and a grinding angle thetat, and a TCP calculation part 4 calculates TCP at need based on them. Following that, a coordinate reverse transformation part 5 performs reverse transformation based on calculated TCP. Therefore, the TCP i.e. the effective point of a tool can be always corrected to the teaching locus even when the grinding angle thetat of the grinding stone 14 formed between the plane to be worked of the work 15 is changed. Therefore, it is not required to conform the working direction of the tool to the measuring direction of quantity of wear, and interference with the work can be evaded, and a part remaining being unground can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a method for correcting the position of a tool effect point,
This is particularly effective for thick tools.

B0 Summary of the Invention The present invention is a tool in which the position of the tool effect point changes depending on the machining angle made with respect to the machined surface of the workpiece, and the position of the tool effect point corresponding to a plurality of said machining angles is measured in advance and used as data. The angle between the taught trajectory vector and the tool approach vector is calculated as the machining angle, the coordinates of the tool effect point corresponding to the machining angle are determined by interpolating the data, and the coordinates of the tool effect point corresponding to the machining angle are determined based on the coordinates. This is a correction to place the tool effect point on the teaching trajectory. Therefore, there is no need to align the machining direction of the tool with the wear measurement direction, and interference with the workpiece is avoided, reducing uncut material. Furthermore, the teaching time is shortened, and it becomes possible to grind at the optimum machining angle depending on the shape of the workpiece.

C1 Prior Art Currently, the so-called teaching playback method is the mainstream method for giving operational instructions when an industrial robot performs grinding work. In this method, the grindstone moves repeatedly according to the taught point position, so if the grindstone becomes worn, it will not be possible to work as originally taught, resulting in problems such as poor finish and uncut parts. There is.

Therefore, when repeating grinding, the amount of wear on the grindstone is measured in advance, and the wear of the grindstone is corrected by converting it into a correction amount for the point at which the grinding effect occurs (so-called tool center point, hereinafter abbreviated as TCP). It is carried out.

Here, in a thick tool such as a grinder, the position of the TCP differs depending on the cutting angle with respect to the surface to be ground of the workpiece.

For example, as shown in FIG. 2, when the cutting angle θ is small, the intersection of the outer peripheral surface and the bottom surface of the grindstone 14 becomes TCP;
As the cutting angle θ increases, the TCP moves upward on the convexly curved outer peripheral surface of the grindstone 14. Here, the grinding angle refers to the angle that the grindstone 14 makes with respect to the processed surface of the work 15. Therefore, if grinding is performed in a direction different from the direction in which the amount of wear was measured, the TCP cannot be corrected accurately, resulting in a problem that the grinding accuracy is significantly reduced.

Therefore, in the teaching work, it is necessary to teach so that the angle between the tool and the workpiece is constant.
Interference with the workpiece was unavoidable, resulting in ungrinding residue.

Furthermore, if there are parts that cannot be ground due to interference, the grinding must be done manually. Furthermore, it was not possible to take the optimum posture of the tool for each workpiece to be ground.

D0 Problems to be Solved by the Invention The present invention has been made in view of the above-mentioned prior art, and it corrects the position of the TCP as needed in response to changes in the machining angle made by the tool with respect to the surface to be machined of the workpiece. The object of the present invention is to provide a tool effect position correction method that allows the tool to be placed on the teaching trajectory.

86 Means and operation for solving the problem The configuration of the present invention to achieve the above object is to provide a tool in which the position of the tool effect point changes depending on the machining angle formed with respect to the workpiece surface, and the tool has a plurality of machining angles in advance. The position of the tool effect point corresponding to is measured and stored as data, the angle between the teaching trajectory vector and the tool approach vector is calculated as the machining angle, and the data is interpolated to correspond to the machining angle. The present invention is characterized in that the coordinates of the tool effect point are determined, and based on the coordinates, correction is made to place the tool effect point on the taught trajectory.

F. Examples Hereinafter, the present invention will be described in detail with reference to examples shown in the drawings.

FIG. 4 shows a tool effect position correction device according to an embodiment of the present invention. As shown in the figure, the tool effect position correction device includes a trajectory interpolation section 1, a trajectory vector calculation section 2, a grinding angle calculation section 3, a TCP calculation section 4, and a coordinate inverse conversion section 5.

Here, the trajectory interpolation unit 1 interpolates a plurality of coordinates taught by the teaching breakback method to obtain a continuous trajectory. In other words, the coordinates taught during teaching are discontinuous, but during actual grinding work, it is necessary to move the grindstone on a continuous trajectory, so coordinates are determined by interpolating between them. be.

Next, a trajectory vector V is calculated using these interpolated coordinates. When the surface to be ground of the workpiece 15 is flat, the trajectory vector V9 is a vector in the direction along the surface to be ground, and when the surface to be ground is curved, it is a vector in the tangential direction at the contact point of the grindstone 14. It is a vector.

Furthermore, the grinding angle calculation unit 3 calculates the grinding angle θ based on the trajectory vector V and the tool approach vector V. The tool approach vector V is the workpiece 15
is the vector in the direction of the grinding wheel I4 with respect to the surface to be ground.

Therefore, the grinding angle θ is determined as the angle at which the trajectory vector V and the tool approach vector V intersect.

Here, in the case of a thick tool like the grindstone 14, the position of the TCP changes depending on the grinding angle θ1. Therefore, the coordinates of the TCP corresponding to a plurality of grinding angles θ1 are measured in advance, as shown in FIG. 3, and stored as data. In FIG. 3, the TCP coordinates hardly change with respect to the Y-axis, but change somewhat with respect to the Y-axis, and change greatly with respect to the Z-axis. As for the TCP coordinates, the direction perpendicular to the flat surface of the grinding wheel 4 is the Z-axis, the direction along the tool approach vector V is the Y-axis, and the direction perpendicular to both the Z-axis and the Y-axis is the Y-axis. did.

Further, the TCP calculation unit 4 calculates TCP from the measurement data shown in FIG. 3 based on the grinding angle θ1. Since the grinding angle θ is continuously changed so as to be optimal for the location to be ground, the point where the grinding effect occurs is determined by the grinding angle θ1.

Furthermore, the coordinate inverse transformation unit 5 inversely transforms the interpolated coordinates so that the TCP determined by the TCP calculation unit 4 is on the taught trajectory.

The tool effect position correction device of this embodiment having the above configuration is used for the grinding machine shown in FIG.

That is, as shown in FIG. 1, an angle grinder 13 is attached to the tip of the robot 11 via a six-axis flange 12, and a disc-shaped grindstone 14 is rotatably provided on the angle grinder 13. This grindstone 14 is used as workpiece 1.
Grinding can be performed by moving it along the surface to be ground of No. 5.

First, the trajectory interpolation unit l interpolates the taught coordinates and moves the grindstone to the grindstone 1.
4 is moved along the surface of the workpiece 15 to be machined. At the same time, the trajectory vector calculation unit 2 and the grinding angle calculation unit 3 calculate the taught trajectory vector V2, the tool approach vector V, and the cutting angle θ, and based on these, the TCP calculation unit 4 calculates the TCP at any time.

Subsequently, the coordinate inverse transformation unit 5 inversely transforms the interpolated coordinates based on the calculated TCP.

Therefore, even if the cutting angle θ8 formed by the grindstone 15 with respect to the surface to be machined of the workpiece 15 changes, the TCP, that is, the effective point of the tool, is always corrected to the taught trajectory.

For this reason, it is no longer necessary to match the machining direction of the tool with the direction in which the amount of wear is measured, thereby avoiding interference with the workpiece and reducing uncut material.

Furthermore, the teaching time is shortened, and it becomes possible to grind at the optimum machining angle depending on the shape of the workpiece.

G0 Effects of the Invention As described above in detail based on the examples, in the present invention, even if the machining angle formed by the tool with respect to the surface to be machined of the workpiece changes, the effective point of the tool always remains on the teaching trajectory. Corrected above. For this reason, there is no need to align the machining direction of the tool with the wear measurement direction, so interference with the workpiece is avoided and uncut material is reduced. Furthermore, the teaching time is shortened, and it becomes possible to grind at the optimum machining angle depending on the shape of the workpiece.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the tool to be corrected by the present invention and its grinding state, and Fig. 2 (a), (b), and (C) show changes in the grinding angle of the grindstone and the position of the tool effect point, respectively. FIG. 3 is a graph showing the grinding angle and the coordinates of the point of application of the tool, and FIG. 4 is a block diagram of a tool effect position correction device according to an embodiment of the present invention. In the drawing, ■ is a trajectory interpolation unit, 2 is a trajectory vector calculation unit, 3 is a cutting angle calculation unit, 4 is a TCP calculation unit, 5 is a coordinate inverse transformation unit, 11 is a robot, 12 is a 6-axis flange, 3 is an angle grinder , ■ 4 is a grindstone, 5 is a workpiece.

Claims (1)

[Claims] In a tool in which the position of the tool effect point changes depending on the machining angle made with respect to the workpiece surface, the position of the tool effect point corresponding to a plurality of machining angles is measured in advance and stored as data, and the position of the tool effect point is measured in advance and stored as data. The angle between the teaching trajectory vector and the tool approach vector is calculated as an angle, the coordinates of the tool effect point corresponding to the machining angle are determined by interpolating the data, and the tool effect point is placed on the teaching trajectory based on the coordinates. A tool effect position correction method characterized by correcting the position of a tool.