JPH02169194A - Method for cutting hole - Google Patents

Abstract

PURPOSE:To obtain a hole of high quality by moving an end effector along a curve having a prescribed shape connected smoothly to the closed figure and then, performing drilling on a work. CONSTITUTION:The respective teaching data on the central point P and the radius R are read out from a memory. The position of a point Q separated by distance R in the prescribed direction from the central point P is obtained by operation and the position and shape of a semicircle S with the two points P and Q as both end points are specified. When the semicircle S is specified, a laser beam torch is positioned toward the central point P and then, moved from the central point P to the shifting point Q along the semicircle S. The work is cut, namely, the hole H is cut off along a circle C by moving the torch by 360 deg. along the semicircle S while irradiating the work with laser beam. By this method, the cut surface of the cut-off hole H is smoothed without changing suddenly the mobile direction of the torch and generating vibration.

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention relates to a method of drilling a workpiece using an automatic cutting machine such as a laser cutting robot, and in particular, improves the quality of the drilling cut surface. It is related to the technology to make it happen.

(Conventional technology) Technology has been put into practical use that automates the process of drilling holes in workpieces using laser cutting robots. FIG. 5 is a diagram showing the locus of a laser torch used in such an automatic drilling process, and a circle C corresponds to the shape of the hole. In the actual drilling process, the laser torch is first positioned toward the center point P of the circle C assumed on the surface of the workpiece W, and then the laser 1 is moved linearly along the line segment PQ. Thereafter, the laser torch is moved from point Q along circle C to fuse and cut the workpiece W, thereby making a hole by cutting off the inside of circle C. In this way, once the laser torch is positioned at the center point P, the laser torch is positioned at the center point P during teaching.
This is because the locus of the laser torch is specified by positioning the laser torch and teaching the position of the center point P and the radius of the circle C in that state.

(Problem to be Solved by the Invention) By the way, when moving the laser torch according to the above order, in the part where the laser torch moves from the line segment PQ to the circle C, the moving direction of the laser torch is changed from the direction shown in the figure. It must turn 90 degrees in eight directions. Therefore, the arm of the robot is subjected to a large acceleration at this direction changing portion, which causes vibration of the arm and the laser torch. As a result, the laser irradiation position becomes unstable in the vicinity of point Q, and the cut surface of the hole obtained in terms of Rn also becomes rough in the vicinity of point Q, resulting in a problem that the quality of the hole deteriorates. be.

OBJECTS OF THE INVENTION The present invention is intended to overcome the above-mentioned problems in the prior art and aims to obtain high quality holes in automatic drilling processes.

(Means for solving eight problems) In order to achieve the above-mentioned object, in this invention, an automatic cutting device equipped with an end effector for cutting a workpiece is used, and the end effector is cut into a predetermined closed shape (for example, a circle). ), and then move the end effector along the m-shape to cut and drill holes in the workpiece along the closed shape. In performing the process, after moving the end effector along a curve of a predetermined shape (for example, a semicircle) that smoothly connects the predetermined point to the m shape, avoid moving the end effector along the closed shape. and performs a hole drilling process on the workpiece.

In this invention, "smoothly connecting" to a closed figure means a curve of the above-mentioned predetermined shape (hereinafter referred to as "guidance curve").
This means that continuity in the tangential direction of the movement path of the end effector is ensured at the transition point from J to the closed figure described above. For comparison, considering the example shown in FIG. 5, in this prior art, at the transition point Q, the tangential direction of the moving path changes discontinuously from the direction to the eight direction. On the other hand, the present invention corresponds to one in which the movement route between PQ and Q is changed so as to eliminate this discontinuity.

However, even if the continuity is microscopically lost due to interpolation processing of the moving route, this is allowed as an error. In other words, it is only necessary to substantially realize the transition from the induction curve having the above-mentioned continuity to the m-shape.

(Function) In this invention, when the end effector moves from the guide curve side to the m-figure side, continuity in the moving direction is ensured. Therefore, no sudden acceleration is applied to the end effector or its drive mechanism, and vibration of the end effector is prevented. As a result, deterioration in quality of the cut surface of the hole due to vibration can be prevented.

(Example) Fig. 2 of A- is a schematic perspective view showing the mechanical configuration of a rectangular seat MA type laser cutting robot as an example of an automatic cutting device to which the present invention is applied to perform automatic hole drilling processing. It is. In the rFfI diagram, this laser cutting []bot RB
has a movable base 2 on top of the base 1, which is movable in the X direction (horizontal direction) by a motor M1 (not shown).
A workpiece (not shown) is placed on this moving table 2.

A beam 4 is installed on the Ir4 portion of the ram 3 vertically installed on both sides of the base 1, and the beam 4 extends in the 7 directions (vertical direction in the figure) and is moved in the Y direction by a motor M2. A movable shift fJi column 5 is provided.

Further, a motor M4 is provided at the lower end of the moving column 5 to move up and down in the X direction by a motor M3. As a result, the arm 6 provided eccentrically from the central axis of the moving column 5 rotates in the θ direction in the figure. Also,
A motor M5 is provided on the side of the lower end of the arm 6, and the laser torch T as an end effector for cutting the workpiece is rotated in the ψ direction in the figure.

Of these, the laser torch T is supplied with a laser torch from a laser oscillation device d7 through a laser guide vibe 8. Further, the uI III unit 119 has a built-in microcomputer, and the operation panel 10 is equipped with a keyboard, a display, and the like. Furthermore, the external computer 11 is for inputting/outputting data of the gods and processing data, and is equipped with a CR 12, a keyboard 13, and the like.

FIG. 3 is a schematic diagram of the electrical configuration of the robot Re shown in FIG. 2. In FIG. 3, the following devices are connected to a microcomputer 21 built in a control unit d9 via a bus BL.

■The above motors M-M5 and these motors M1 to M5
Mechanism drive system 23 including encoders E1 to E5 (not shown in FIG. 2) that detect the rotation angle of ■Laser oscillation device 7 ■Operation panel 10 ■External computer 11°B, below teaching operation Now, the teaching process and the reproducing process of the robot +-RB will be sequentially explained, taking as an example the process of cutting off the circular hole 1 from the workpiece W shown in FIG.

First, in teaching (Fig. 1 Δ), the control device 9
Initial settings are performed (step S1).

Next, the operator judges whether the lj+ motion to be taught is a drilling process (step S2), and if it is not a drilling process, normal teaching is performed (step 83).

When teaching the drilling process, first, in order to show that the teaching here is related to the drilling process, a predetermined drilling process is performed in the teaching data storage area provided in the memory of the microcomputer 21. A flag is set (step S4). Then, use the dummy work W to locate the center point P of the circle C (Fig. 1B) that defines the hole H to be cut out. as taught above (step S5). In addition, this dummy work W. is the workpiece used for teaching, and the workpiece W used for actual drilling process.
It has the same shape as (Fig. 3).

In the next step S6, while the laser torch T is positioned toward the center point P, the value of the radius R of the circle C is taught,
This completes the teaching of one drilling process. The orientation of the laser torch T may be taught at the same time as the position of the center point P is taught. and,
Due to the existence of step S7 in FIG. 1A, the teaching step described above is executed for a series of motions from the start to the end of the robot RB's motion, thereby completing the teaching. However, for ease of understanding, only one hole H is used here.
Consider only the teachings about. Therefore, in this example:
Steps 84 to S6 are executed only once. The teaching data thus obtained is stored in the memory together with the drilling flag.

C1 Reproduction Operation In the reproduction operation (Fig. 1C), first, the υ1111 device 9 is initialized (step 511), the read pointer for teaching data from the memory is advanced by one (step 812), and then the read pointer is It is determined whether or not the drilling flag is set at the taught data storage address (step 513). If the drilling flag is not set, normal playback processing (step 51) is performed.
Step 4) is performed, but if the drilling flag is set, the process advances to step S15, and the respective teaching data regarding the center point P and radius R are read out from the memory.

Next, in step S16, the position of a point Q (Fig. 1D) which is a distance R away from the center point P in a predetermined direction (described later) is calculated, and a semicircle S Determine the location and shape of.

Then, interpolation points on this semicircle S are determined by a circular interpolation method or the like.

In this process, in order to obtain the equation of the semicircle S from both end points P and Q, information indicating whether the semicircle is a clockwise semicircle or a counterclockwise semicircle is required. This information may be taught at the time of teaching the hole numbering process, or it may be set in advance that the direction is generally clockwise (or counterclockwise). This direction of rotation is circle C
It is assumed that the direction of rotation is the same as that of the cutting operation along (described later).

Furthermore, the information on which direction to take the point Q from the center point P and the information for determining the direction of the plane forming the semicircle S7'1Cff can be determined from the position and orientation of the end effector T at the center point P. can. That is, with the orientation of the laser torch T taught at the center point P as a reference, a semicircle S is determined in a plane perpendicular to this orientation, and the point Q is the center point among the points on this plane. P
What is necessary is to specify it as a point separated by a distance R from the center point P along the direction indicated by the attitude ψ of the laser torch T at .

Note that, as will become clear later, point Q is a transition point from semicircle S to circle C.

Specifically, as shown in FIG. 1E, an absolute coordinate system (X, Y.

Z ) Niolt 6 points P (7) 5jegwo (P ,
Py, P2), and the attitude under the laser torch at point P is given by the direction cosine 11. m
, nl) and the direction from point P to Q by direction cosine (1, m , n2), the coordinates of point Q (QX, Q, , O7) are as follows (1) to (
3) Given by Eq.

QX=Px+RJ12・(1
)Q = PY+Rm2 −(2)Q
= Pl+Rn2 - (3) However, 1112 +m1 ff12 + 01n2=O...
(4).

Also, the midpoint between points P and Q (that is, the center point of the semicircle S) M
The coordinates of (MX, M,, M7) + yo, M - (P
+ Q E) / 2
... (!+)X M, -(P, +Q,,)/2 ...(6)
M = (P + - Ql) / 2 ... (
7) It is l.

On the other hand, as shown in FIG. 1E, point M is the origin and (t
The work coordinate system (D, D,
In O7), the coordinates (S , S , S ) of any Y point on the semicircle S are expressed as 5) 1) (-(R /2) costS wy=
It is expressed as (R/2) sin tS, 47-O.

Then, it is expressed by half of the absolute coordinate system (X, Y, Z)...(8)...(9)...(10). However, L is the (3X3) rotation matrix steering wheel between the workpiece coordinate system and the absolute coordinate system,
l, ml, n, j! 2. m, 2. It is expressed by n2. These equations (5) to (11) are the equations of the semicircle S expressed by parameters.

When the semicircle S is identified in this way, the center point P
After positioning the laser torch T toward
21 (step 517).

This movement is performed according to the chain of interpolation points obtained by the interpolation port described above. Further, although the interpolation of step S16 and step 317 are executed substantially in parallel, for convenience, they are shown as a serial sequence in FIG. similar). Note that although the laser irradiation is started from the center point P, the laser irradiation may be started at a point in the middle of the semicircle SL.

In the next step 318, a circle C is specified as a circle with radius R centered on point P, and the position of the interpolation point on the circumference is calculated. The equation of circle C adopts Px~P7 instead of Mx-Ml in equation (11) already mentioned, and becomes (8)~
In formula (10), (R/2)→R, and
This can be obtained by setting the range of the parameter t to π≦t≦3π.

Then, in step S19, while irradiating the work W with the laser, the laser torch T is moved 36 times along the circle S.
By moving 0°, the workpiece W is cut along the circle C, that is, the hole 1 is cut off. As a result, the substantial part of the drilling process is completed, and step 820 is reached without the escape operation of the laser torch T, and the regeneration operation is completed. Note that 98 steps for specifically determining the respective positions of the circle C and the semicircle S may be performed before starting the reproduction operation.

In this reproduction operation, it can be understood from the positional/shape relationship between the circle C and the semicircle S that the semicircle C, that is, the induction curve, smoothly connects with the circle C at the transition point Q. That is, the tangent directions of the circle C and the semicircle S at the transition point Q are both in the B direction (Fig. 1D), and are equal to each other by 1°.
The direction of movement of the laser torch T does not change suddenly.
No vibrations occur. As a result, the cut-out hole H becomes smooth and its quality is improved.

D. Modification As can be seen from the above description, the present invention is characterized by a closed shape that defines the cutting shape and a guiding curve that guides the movement of the end effector (laser torch T) before reaching the closed shape. The point is that it connects smoothly. For this reason,
The hole H does not need to be a round hole, and may be a square hole or an elongated hole defined by, for example, a rectangle KA in FIG. 4A or an oval 8 in FIG. 4B. Further, in teaching the moving route shown in FIG. 1D, the respective positions of the center point P and the transition point Q may be taught.

Furthermore, as shown in FIG. 4C, a technique for moving toward the circle C after positioning at a point PA other than the center point of the circle C is also included in the scope of the present invention. As for the shape of the W lead curve, a circular arc such as a semicircle is preferable in terms of ease of calculation and mechanical control, but as shown in Figure 4D, it is preferable to use a circular arc such as a semicircle or a parabola. It is also possible to employ it as a guide curve.

On the other hand, in the above embodiment, positioning is performed at the center point P of the circle C in relation to teaching. However, from the viewpoint of preventing vibration at the transition portion to the cutting line of the hole (figure 11), it is not necessary that the positioning point be determined in advance in relation to teaching. For this reason, even if a positioning point is determined in advance for the purpose of preventing interference with obstacles, and movement is to be performed from that point to the hole cutting starting point (transition point Q), the present invention is applicable. Applicable. Furthermore, considering these circumstances, the positioning point may be set outside the closed figure instead of inside the closed figure.

In addition, this invention can be applied to other robots such as articulated robots, automatic cutting devices that alternately operate NC11 and IJtll, etc.
It can be realized in various mechanical configurations.

(Effects of the Invention) As explained above, according to the present invention, the cutting end effector is moved to the r′A figure that defines the shape of the hole along the guiding curve that smoothly connects to this closed figure. Therefore, vibration of the end effector at the transition portion to the closed shape can be prevented. Therefore, there is an effect that the quality of the cut surface of the hole can be improved.

FIG. 1B is an explanatory diagram of data taught in teaching; FIG. 1C is a flowchart showing reproducing operation in the embodiment; FIG. 10 and FIG. An explanatory diagram showing the movement path and coordinates; FIG. 2 is a schematic diagram of the structure of the right-angled plug-shaped laser cutting robot to which the embodiment is applied; FIG. 3 is an illustration of the electrical diagram of the robot shown in FIG. 4A to 4D are detailed explanatory diagrams of the present invention. FIG. 5 is a conventional automatic drilling machine 1! FIG. 3 is an explanatory diagram showing a moving path of a laser torch in J31j.

R [3... Laser cutting robot, T... Laser torch (end effector for cutting workpieces), W... Workpiece, ]''... Hole, C...
...Circle that defines the shape of the hole (riJ shape), P...Center of the circle, S...Induction curve Figure D

Claims (1)

[Claims] (1) Using an automatic cutting device equipped with an end effector for cutting a workpiece, after positioning the end effector toward a predetermined point inside or outside a predetermined closed shape,
By moving the end effector along the closed shape, when cutting the workpiece along the closed shape and performing the drilling process, a shape of a predetermined shape that smoothly connects from the predetermined point to the closed shape is formed. A hole-cutting method characterized in that after moving the end effector along a curve, the end effector is moved along the closed figure to perform a hole-drilling process on the workpiece.