JPH03110087A - Follow-up control method for three-dimensional laser beam machine - Google Patents

Abstract

PURPOSE:To allow processing with high accuracy regardless of the contour shapes of a work by detecting the electromagnetical capacity between a work and a processing head and processing the work while maintaining the distance between the work and the processing head constant according to the detected electromagnetical capacity. CONSTITUTION:The contour shapes of the work W are taught as well together with the teaching of the coordinate values and position angle at the teaching point on a processing line K. These shapes are taught from a teaching box 13 into a processing program and are stored into the memory of a controller 12 after the completion of the program. The respective curves stored in the controller 12 are first read out at the time of processing according to the above- mentioned program. The actually measured value of the electrostatic capacity is so controlled as to be corrected to a reference value by the variable functions set to correspond respectively to the contour shapes of the work W. The processing head 1 can then follow up the processing line K at a prescribed distance therefrom even on any surfaces of the work W having the characteristic contour shapes such as recessed surfaces and projecting surfaces.

Description

[Detailed description of the invention]

[Industrial illumination field] This invention detects the electromagnetic capacitance between the workpiece and the processing head, and processes the workpiece while maintaining a constant distance between the workpiece and the processing head according to the detected electromagnetic capacitance. The present invention relates to a follow-up control method for a three-dimensional laser processing machine. [Prior Art] Devices for cutting or welding workpieces using laser beams have been well known and generally known. A teaching/playback method is used in which the machining trajectory of the workpiece is taught in advance and the workpiece is machined according to the taught data. In addition, in this type of equipment, during processing, it is necessary to maintain an appropriate distance between the workpiece and the tip of the processing head, that is, the focal position of the laser beam irradiated to the workpiece. For example, the distance between the tip of the processing head and the eddy current is 1. A sensor is provided for detection by 'Ki magnetic force, such as magnetism or D electromagnetic force. Figure 4 is a perspective view showing the configuration of a general three-dimensional laser processing machine. In Figure 1, the arm [11] is connected to the processing head (
1) is attached to the β-axis (8), and this β-axis (8)
It consists of an α-axis (9) connected to the α-axis (9), and a Z-axis (lO) connected to the α-axis (9). (2) is a β bearing that supports the β axis (8) which is rotated by the motor (M5) in the direction of the arrow β in the figure; (3) is the motor (M4)
α supports the α axis (9) rotating in the direction of arrow α in the figure.
Bearing, (4) is the processing head (1) by the motor (M3)
The Z bearing (5) supports the Z axis (10) that moves in the direction of the arrow Z in the figure, and the X bearing (5) supports the axis that moves the processing head (1) in the direction of the arrow X in the figure by the motor (Ml). (6) is a Y bearing that supports the shaft that moves the processing head (1) in the direction of arrow Y in the figure by the motor (Ml). (7) is a capacitive sensor installed at the tip of the machining head (1), and is used to detect the machining line (K) on the workpiece
When machining along the line, the workpiece (W) and the machining head (
1) The capacitance between the workpiece (W) and the processing head (1) is detected in order to keep the distance between the tips constant. Note that the processing head (11) irradiates the surface of the workpiece (W) with a laser beam (L) for processing from its tip. Each motor (Ml) to (M5) is driven by a command from the control device (12). , this allows the processing laser beam (L)
The focal point follows the machining line (on), and the machining head (1
) is controlled so that its posture is approximately perpendicular to the surface of the workpiece (W). Incidentally, the machining program is obtained by the operator operating the teaching box (13) to perform teaching work, and is stored in the memory of the control device t (12). Next, a method of controlling the height of the processing head (1) will be explained. In machining using the above machining program, the capacitance between the workpiece (W) and the machining head (11) is detected by the sensor (7) provided at the tip of the machining head (1). Since it changes depending on the distance from the workpiece (W) to the tip of the processing head (1), it is only necessary to control the detected capacitance so that it becomes the same value as the preset capacitance. , work (Wl
It is obvious that the capacitance between the workpiece (W) and the processing head [1] is inversely proportional to the distance from the workpiece (W) to the tip of the processing head (1). As shown in Figure 4, machining of workpiece (W) 1m (K)
The height rIt (height) of the machining head (1) is set to a dimension (A) that allows optimum machining, and the capacitance at the position of the machining head (1) at this time is set to the reference value. and is stored in advance in the memory of the control device (12). Thereby, the capacitance detected by the sensor (7) is compared with a preset capacitance reference value, and as a result, if the detected capacitance deviates from the reference value,
Control bag f so that the detected capacitance matches the reference value
Fi! (12) controls the movement of the processing head (1). Therefore, the height of the processing head (1) with respect to the processing line (K) on the workpiece (If), that is, the focal position of the processing laser beam (L) irradiated onto the workpiece (W), is always maintained appropriately. Processing takes place. [To the problem to be solved by the invention] Since the tracking control method of the conventional three-dimensional laser processing machine is performed as described above, when the workpiece (W) has a planar shape, the processing head follows it with high precision. . When machining a workpiece (Wl) having a concave shape as shown in Fig. 5 in the direction of the arrow, when the machining head (1) is at position b shown in the figure, the distance between the workpiece fill and the machining head (11) is Because it is smaller than the position of a, a
A capacitance larger than the position will be detected. As a result, the control device [12] determines that the detected capacitance is larger than the reference capacitance value, so the processing head (
11 is close to the workpiece (W), and outputs an instruction to pull up the processing head (1). Note that a workpiece (W) having a convex shape as shown in FIG.
), the control is completely opposite to that for the concave workpiece (W) described above. Regardless of the shape of the workpiece above. Since the relationship between the distance and capacitance between the workpiece (If) and the processing head (11) is different from that of the planar workpiece (11), the processing head (1) moves from the predetermined processing trajectory to the position shown in B in the figure. As a result, the laser beam (L)
There has been a problem in that it is no longer possible to maintain a normal focal position, resulting in machining defects and high precision machining. The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a follow-up control method for a three-dimensional laser processing machine that can perform highly accurate processing without being limited to the shape of a workpiece. [Means for solving the problem] A follow-up control method for a three-dimensional laser processing machine according to the present invention includes:
Various contour shapes of the workpiece are specified in the machining program, and a conversion function between the distance between the workpiece and the machining head and the electromagnetic capacitance corresponding to the contour shape is set in advance, and when machining is performed according to the machining program, A conversion function corresponding to the contour shape of the workpiece is selected, and the actually measured electromagnetic capacitance is corrected using the selected conversion function to control the actual distance between the workpiece and the processing head to a predetermined basic value. Processing is carried out at the same time. [Operation] In the present invention, various contour shapes of the workpiece are specified in the machining program, and a conversion function between the distance between the workpiece and the machining head and the electromagnetic capacitance corresponding to the contour shape is set in advance. Accordingly, the above conversion function is selected during machining, and the actually measured electromagnetic capacitance between the workpiece and the machining head is corrected.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. 1st
The figure is a flow diagram showing the follow-up control method of a three-dimensional laser processing machine according to the present invention, Figure 2 is a perspective view of a workpiece with a characteristic contour shape, and Figure 3 is a workpiece with respect to the electrostatic capacitance between the workpiece and the processing head. This is a conversion function curve showing the distance between the tip of the machining head and the tip of the processing head for each workpiece shape. Note that the configuration of the three-dimensional laser processing machine according to the present invention is the same as the conventional one shown in FIG. 4, so a description thereof will be omitted. Next, teaching in a follow-up control method for a three-dimensional laser processing machine will be explained. As mentioned above, the processing program required for laser processing can be obtained through teaching work. -The following points can be considered as the necessity of magnetic teaching. ■The target workpiece is three-dimensional, and its machining shape is an arbitrary spatial curve, making it difficult to accurately display it as nine drawing information. ■It is necessary to determine the attitude angle (α, β) of the machining head so that it is approximately perpendicular to each machining surface, but it is very difficult to numerically calculate the attitude angle from two drawings. It is often complicated and difficult. Therefore, as shown in Figure 2, a marking line (processing line) is drawn on the workpiece along the machining shape, and the operator adjusts the attitude angle of the processing head while operating the teaching pendant along this marking line. We will teach the data of the five axes including, and finally. Machining speed, output, i! In this way, the machining program is completed by adding machining condition data such as control/pulse.
In three-dimensional machining, teaching work is performed by actually moving the processing machine. Next, teaching of a workpiece as shown in FIG. 2 will be explained with reference to FIG. 1. FIG. 2 shows a workpiece (W) having contour shapes such as a flat surface, a concave surface, and a convex surface. Note that (K) indicates a machining line on the workpiece. First, during teaching, the operator teaches the coordinate values and posture angle at the teaching point on the machining line (K), but at this time, the contour shape of the workpiece (1) at the teaching point is also taught at the same time. It determines whether the contour shape of the workpiece is flat, concave, or convex, and teaches each of them in the machining program from the teaching box (13).Then, by repeating this operation sequentially, the machining line ( K) The above characteristic shape data (workpiece contour shape) and 5-axis data (x, y, z, α, β) will be taught during the machining program,
After that, by adding the machining condition data mentioned above, the machining program is completed.2. This is the control device! (It is stored in the memory of 121. When performing processing such as cutting or welding using the processing program obtained as described above, the workpiece (If)
It is important to always maintain a constant distance between the machining head (1) and the machining head (1) in order to perform highly accurate machining. Therefore, the workpiece (W) and the processing head (1
As a method of controlling the distance between the processing head (1)
A capacitive sensor (7) installed at the tip of the head detects the capacitance between the workpiece (W) and the processing head (11), and the processing is performed according to the detected capacitance value. A method is used in which the head (1) is moved in the optical axis direction of the laser beam (L) to obtain a predetermined distance, that is, an appropriate focal position of the laser beam (L). However, in the above method, As mentioned in the conventional technology,
Since the relationship between the distance between the workpiece (W) and the processing head (1) and the capacitance is affected by the contour shape of the workpiece (W), the predetermined distance between the workpiece (W) and the processing head (1) is This will cause the problem of not being able to obtain it. Hereinafter, a method for solving this problem will be explained in detail using FIGS. 1 and 2. The conversion function curve shown in FIG. In the figure, 1 curve machining is a flat surface, 1 curve ■ is a concave surface, and 1 curve l ■ is a convex surface, and each curve shows the workpiece (W) and the machining A reference value of capacitance corresponding to a predetermined distance between the heads (1) is set.For example, in the case of curve 2, as shown in the figure, the reference value of capacitance corresponding to a predetermined distance h6 is C0. Note that each of the above curves is obtained through experiments, etc., and is stored in advance in the memory of the control device (12).Here, when machining the convex surface part of the workpiece (W) according to the machining program described above, Taking this as an example, first, each curve stored in the control bag 2 (f12) is read out.Next, by a machining program in which the contour shape of the workpiece (Wl) is taught in advance, it is determined that the contour shape to be machined is a convex surface. The curve ■ corresponding to the convex surface is selected from the read curves.Then, the capacitance reference value C0 corresponding to the reference distance h0 set for the curve ■ and the capacitance that can be placed on the convex surface are selected. The actual capacitance is compared with the actual capacitance.For example, as shown in Figure 3, the actually measured capacitance is C1
If so, it is determined that the capacitance is deviated from the reference value C0, and the actual measured capacitance C1 is corrected to the reference value C0. As a result, the distance between the workpiece (W) and the processing head (1) +1ih in the actual measurement value C1 is set to the predetermined distance fih. Note that such control is executed at any time as the processing progresses. As described above, by controlling the actual measured value of capacitance to be corrected to the reference value of capacitance using the conversion function set corresponding to each contour shape of the workpiece (If),
The processing head (1) can follow the processing line (to) at a predetermined distance on any surface of the workpiece (W) that has a characteristic contour shape, such as a flat surface, concave surface, or convex surface. It becomes. Therefore, since the distance between the workpiece (W) and the processing head (1) is maintained at a predetermined distance, the focal position of the laser beam (L) irradiated onto the workpiece (W) is always constant. Become. Incidentally, in the above embodiment, a continuous curve is stored in the memory as a conversion function, but discrete values may be stored as data and used by successive interpolation. In addition, in the above embodiment, the workpiece (W) and the processing head (1
1 is detected by capacitance, but the same effect can be obtained by using other electromagnetic capacitances such as eddy current or magnetism. Further, in the above embodiment, the contour shapes of the workpiece taught at the time of teaching are of three types: flat, concave, and convex, but it goes without saying that the shape is not limited to these shapes. [Effects of the Invention] As explained above, according to the present invention, various contour shapes of a workpiece can be specified in a machining program, and a conversion function of the distance between the workpiece and the machining head and the electromagnetic capacitance corresponding to the various contour shapes can be determined. When machining is performed according to the machining program described above, the conversion function corresponding to the contour shape of the workpiece is selected in advance, and the actually measured electromagnetic capacitance is corrected by the selected conversion function to reduce the distance between the workpiece and the machining head. Since machining is performed while controlling the distance of This has the effect of providing a method.

[Brief explanation of drawings]

Fig. 1 is a flow diagram showing a follow-up control method for a three-dimensional laser processing machine according to an embodiment of the present invention, Fig. 2 is a perspective view showing the shape of a workpiece, and Fig. 3 is a diagram showing distance versus capacitance according to this method. A curve diagram showing a conversion function. FIG. 4 is a block diagram of a three-dimensional laser processing machine, and FIGS. 5 and 6 are diagrams for explaining a conventional follow-up control method. In the figure, (1) is the processing head, and (W) is the workpiece. (C0) is the reference value of capacitance, and (h,) is the reference distance between the workpiece and the processing head. In addition, in FIG. 9, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] In a follow-up control method for a three-dimensional laser processing machine that performs processing while maintaining the distance between the workpiece and the processing head at a predetermined reference value based on the detected electromagnetic capacitance between the workpiece and the processing head, various types of the workpieces are processed. In addition to specifying the contour shape in the machining program, a conversion function between the distance between the workpiece and the machining head and the electromagnetic capacitance corresponding to the contour shape is set in advance, and when machining is performed according to the above machining program, the contour of the workpiece Select a conversion function that corresponds to the shape, correct the measured electromagnetic capacitance using the selected conversion function, and perform processing while controlling the actual distance between the workpiece and the processing head to a predetermined reference value. A follow-up control method for a three-dimensional laser processing machine, characterized by: