JPH03169490A - Follow-up control method for three-dimensional laser beam machine - Google Patents

Abstract

PURPOSE:To hardly cause defective machining on a curved-face shape part by selecting the set height of an electrostatic capacity sensor according to the curved-face shape in a machining program according to a work shape during teaching. CONSTITUTION:Three kinds of plane shape, projecting radius-shape and recessed radius-shape are given according to the work shape and respective height data are made to h1, h2 and h3. When an operator selects the work shape as SENSE I, SENSE II and SENSE III, respectively, during teaching, three kinds of control heights can be selected according to the work shape. Although a detection value of electrostatic capacity as in the past will do as a value of the control height h1, values of electrostatic capacities which are deviated from the case of the phase shape actually are measured in advance for the control heights h2 and h3 and the values are obtained only by adding or subtracting the deviated amounts to or from the actual electrostatic capacities. After all, the values of the control heights h2 and h3 are obtained by changing purposely. By this method, since the set height of the electrostatic capacity sensor can be selected, defective machining is hardly caused on the curved-face shape part.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a three-dimensional laser processing device that processes a curved workpiece, in which the height between the tip of the processing head and the workpiece is detected by a capacitive sensor. This article relates to a follow-up control method for holding a machining head at a preset height in response to changes in the shape of a workpiece.

[Conventional technology]

Conventionally, devices for cutting or welding workpieces using laser beams, etc. are well known, and there is a teaching/playback system in which -M is taught the processing line on the workpiece in advance and processing is performed according to the data. method is used. In addition, in this type of equipment, it is necessary to keep the height between the tip of the processing head and the workpiece, that is, the focal position of the laser beam, at an appropriate level during processing. A sensor is provided to detect height. A capacitance type sensor is often adopted as the sensor.

FIG. 6 is a schematic perspective view showing the shaft configuration of a general three-dimensional laser processing machine. In the figure, the arm (11) has a β-axis (8) to which the processing head (1) is attached, and a β-axis (8) to which the processing head (1) is attached.
α-axis (9) connected to α-axis (9) and Z-axis connected to α-axis (9)
It consists of an axis (10). (2) is the motor (M
S) is a β bearing for rotating the β axis (8) in the direction of arrow β;
This is an α bearing for rotating the machine in the direction of the arrow α. (4)
moves the processing head (1) via the motor (M3) in the direction of arrow Z.
Z bearing for moving in the direction, (5) is the motor (M2
) is a Y bearing for moving the processing head (1) in the direction of arrow Y, and (6) is an X bearing for moving the processing head (1) in the direction of arrow X via a motor (M1). . (7) is a capacitive sensor attached to the processing head (1), which functions to maintain a constant height from the workpiece W when moving along the processing line K on the workpiece W. The processing head (1) also irradiates a processing laser beam L from its tip. In addition, each motor (M1) to (MS)
is driven by a command from the NC control device (l2) so that the focus of the processing laser beam L follows the processing line K and the attitude of the processing head (1) is approximately perpendicular to the surface of the workpiece W. is controlled by. The machining program is determined by a teaching operation performed by an operator using a teaching box (13), and is stored in the memory within the NC control device (12).

Next, a method for controlling the height of the processing head (1) will be explained. In machining using the machining program described above, the capacitance between the workpiece (W) and the machining head (1) is detected by a capacitive sensor (7) provided at the tip of the machining head (1). This capacitance is the workpiece (W
) to the tip of the processing head (1), the detected capacitance may be controlled to have the same value as a preset capacitance. As shown in FIG. 6, the capacitance at the position of the machining head (1) with respect to the machining line (K) of the workpiece fW) is set as a reference value and is stored in advance in the memory of the NC control device (l2). .

As a result, the capacitance detected by the capacitive sensor (7) is compared with a preset capacitance reference value, and as a result, if the detected capacitance deviates from the reference value, The processing head (1) is controlled by the NC controller IT F121 so that the detected capacitance matches the reference value.
movement is controlled.

Therefore, the height of the processing head (1) with respect to the processing line (K) on the workpiece (Wl), that is, the focal position of the processing laser beam (L) irradiated onto the workpiece [W], is always maintained properly. Processing is performed while

[Problem that the invention seeks to solve]

Conventional tracking control methods for three-dimensional laser processing equipment can accurately track a workpiece in a planar shape, but only one set height of the sensor can be selected during the processing program, so the characteristics of the sensor cannot be selected. Furthermore, it is known that the detection accuracy of the sensor decreases at locations where the workpiece has a curved surface shape, resulting in a deviation from a constant height. For example, the seventh
In the shape of the workpiece W shown in the figure (convex R part), the processing head (
The movement 1) moves at a position higher than the set height (A) between the workpiece W and the tip of the processing head (1), which is indicated by a dotted line in the figure (B). In addition, in the shape of the workpiece W (concave R part) shown in Fig. 8, the movement of the processing head (1) is based on the set height [A] between the workpiece W and the tip of the processing head (1), which is indicated by a dotted line in the figure. The workpiece also moves at a low position (Bl. Therefore, machining defects may occur on the curved surface shape part, or the machining head (1) may collide with the workpiece W, making it impossible to achieve the purpose of follow-up control using the sensor described above. Ta.

In order to solve the above-mentioned problems, the present invention provides a follow-up control having a means for correcting the decrease in detection accuracy of the sensor when processing a curved workpiece using a capacitive sensor. With the goal.

[Means to solve the problem]

In order to solve this problem, the present invention uses a height tracking control method for a capacitive sensor in which, when teaching a machining trajectory, an operator selects a plurality of pre-registered controls according to the shape of the workpiece surface. It is possible to select from the height and specify it on the machining program.

[Effect]

In this invention, a plurality of control heights of capacitive sensors are registered in advance in the memory of the control device, and the machining trajectory is taught in consideration of the detection accuracy characteristics of the capacitive sensor for the workpiece surface shape. Sometimes, a button is added to the teaching operation box so that the operator can select the registered control height and specify it in the machining program. Follow-up control is executed according to the control height specified on the processing program.

[Embodiments of the Invention] This invention relates to height tracking control of a capacitance sensor in a three-dimensional laser processing device, and since the processing device is no different from the conventional one, a description of the processing device will be omitted here. .

Flowchart diagrams in Figures 1 and 2, and Figures 3 and 4.
An embodiment of the present invention will be described with reference to FIGS.

Depending on the shape of the workpiece, there are three types shown in Fig. 3: planar shape, convex R shape, and concave R shape, and the height data for each case is h+. l-z. Let's say hyu. During teaching, the worker can check the shape of the workpiece separately.
NSEI, S E N S E II, SENSE II
If selected as I, the control height will be 3 depending on the workpiece shape.
You can choose the type. The value of the control height h1 may be a conventional capacitance detection value, but the control height h2. h,+ is obtained by measuring in advance the amount of capacitance that actually deviates from the case of a planar shape, and simply adding or subtracting the amount of deviation from the actual capacitance value. In other words, the control height h. ．． The value of hyu is intentionally changed.

Next, FIG. 2 is a flowchart for inputting height data into the machining program. After starting teaching (step SL), the operator determines whether the workpiece has a flat or straight shape (step S2). If it is a flat part, SENSEI is registered in the program (step S3). Next, it is determined whether it is a concave R shape (step S4) and if it is a concave R shape. SENSE
II is registered in the program (step S5). If it is a convex R shape, SENSEm is registered in the program (step S6). This is continued until the end of teaching (step S7).

FIG. 1 is a flowchart of height follow-up control during processing of a workpiece. Machining is started according to the machining program (step S8). NC device is SE in height control
NSEI. SENSEII and SENSEIII are determined (step S9). Next, the NC device sets the control height in the selected state (step SIO). SENSE
If I (planar shape), h=hl. SENSE II
(Convex R shape) then h=h. ．． If it is SENSE III (concave R shape), set it as hh. The height is controlled based on each of these data (step Sll). The above control is performed until the machining is completed (step S12). After processing, h
It is reset to =1+ + (step S13).

FIGS. 4 and 5 show the state of the processing head (1) at a curved surface portion when a workpiece W (cross-sectional view) is processed using a processing program using the present invention. Fig. 4 shows a case where the workpiece W has a convex round shape, and Fig. 5 shows a case where the workpiece W has a concave round shape. In both cases, the processing head (
The actual movement of 1) is coming soon (B).

〔Effect of the invention〕

As described above, according to the present invention, since the set height of the capacitance sensor can be selected during teaching according to the shape of the workpiece, there is an effect that machining defects are less likely to occur in curved portions.

[Brief explanation of the drawing]

FIG. 1 shows the height of "
FIG. 3 is a flowchart of follow-up control. Figure 2 is a flowchart for changing the conditions according to the shape of the workpiece and registering them in the program during teaching.
Figure 3 is a perspective view showing the shape of the workpiece;
The figure is a side view showing the movement of the processing head (1) when this invention is used. Further, FIG. 6 is a configuration diagram of a conventional three-dimensional laser processing apparatus. FIGS. 7 and 8 are side views showing the movement of the processing head (1) under conventional height follow-up control. In the figure, (1) is a processing head, and (7) is a capacitance sensor. (ill is arm, (l2) is NC device, (
13) represents a teaching box, K represents a machining line, W represents a workpiece, A represents a constant height from the workpiece W, and B represents a locus of the machining head section detected by the electrostatic capacitive sensor (7). In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] A three-dimensional machine that maintains the height from the tip of the processing head to the workpiece at a preset value in a laser processing device that supports the processing head so that it can move relative to the workpiece in three-dimensional directions. A follow-up control method for a three-dimensional laser processing device, characterized in that a set height can be selected according to a curved surface shape within one processing program.