JPH01237090A - Method and device for setting working speed of laser beam machine - Google Patents

Abstract

PURPOSE:To improve the shape accuracy and material yield by operating the max. working speed from requested working diameter and shape accuracy, the delay of the positioning system of an NC device and the cut width and executing the setting of working speed. CONSTITUTION:A shape recognizing part 2, an inner shape/outer shape deciding part 3 and working speed polynomial coefft. setting part 6 are arranged for a CAD data file 1. The shape data of the data file 1 is read in the shape recognizing part 2 and the deciding part 3 decides whether it is inner circle working or outer circle working. The relation of the offset amt., working speed and cut width of the device is introduced to the setting part 6 and the shape accuracy setting part 4 sets a requested accuracy. A working speed arithmetic part 7 sets the error of a working locus and the setting part 6 solves a polynomial and finds the max. working speed satisfying the shape accuracy. The shape accuracy and material yield are improved because the working speed introducing the delay of a servosystem call be set.

Description

[Detailed Description of the Invention] [Summary] This invention relates to a method and device for automatically setting the machining speed when circular or arc machining is performed in a laser processing machine, and is capable of achieving a desired shape accuracy regardless of the size of the machined shape. The purpose of the present invention is to provide a method and device for setting the maximum machining speed required for the workpiece when machining a circle or an arc with a laser beam while moving the laser beam and the workpiece relative to each other using an NC device. The maximum machining speed is calculated from the diameter of the machining shape, the shape accuracy, the delay of the positioning system of the NC device, and the cutting width that depends on the machining speed.

[Industrial application field]

The present invention relates to a method and apparatus for automatically setting a machining speed when performing circle or arc machining in a laser beam machine.

In recent years, laser processing has been playing an increasingly important role in, for example, sheet metal processing. In this laser processing, C
A D (Computer Aided Design
n) From the data
The information (parameters) used to set the machining speed when creating rol) data include the material, thickness, and CAD of the plate material.
It is necessary to determine the machining speed, especially the maximum machining speed, that provides the desired shape accuracy from this limited information.

[Conventional technology]

Conventionally, when setting the laser processing speed, it was determined only according to the material and thickness of the plate material, regardless of the shape to be processed. Moreover, most of these depend on the skill of the operator, and the approximate processing speed (laser feed speed) was calculated based on the material and plate thickness.Apart from this, there is a device that automatically sets the processing speed. is also known, but in that case also N
The shape (diameter) data of the plate material is not taken into account when creating the C data.

[Problem to be solved by the invention]

However, as is well known, laser machining is faster than relatively constant-speed wire-cut electrical discharge machining or NC milling, so it is particularly difficult to use a circle or an arc (hereinafter, unless otherwise specified, when simply referred to as a circle, it will be referred to as a circle). The accuracy of the machined shape of a part (including a circular arc) is affected by the diameter size, processing speed, delay in the positioning system of the processing machine, etc., and is essentially unrelated to the material and plate thickness.

Therefore, not only the shape accuracy as a sheet metal product varies, but also sufficient shape accuracy could not be obtained. Therefore, in the case of a product that requires strict shape accuracy, it is necessary to perform re-machining by adjusting the machining speed, or to perform finishing machining using a finishing tool such as a reamer.

SUMMARY OF THE INVENTION In order to solve these conventional problems, it is an object of the present invention to provide a method and apparatus for setting a maximum machining speed that provides desired shape accuracy regardless of the size of the shape.

The basic concept of the present invention is that CA
When creating NC data from D data, the required accuracy is determined from the shape data, required shape accuracy, processing machine positioning system delay (servo system offset), and cutting width during processing, regardless of the size of the shape. The goal is to automatically set the maximum machining speed that satisfies your needs.

[Means to solve the problem]

In order to achieve the above object, according to the present invention, when processing a circle or an arc with a laser beam while moving the laser beam and the workpiece relative to each other using an NC device, the diameter of the workpiece is required to be machined. The structural feature is that the maximum machining speed is calculated from the shape accuracy, the delay of the positioning system of the NC device, and the cutting width that depends on the machining speed.

Further, as shown in FIG. 1, the processing speed setting device for a laser processing machine according to the present invention imports processing shape data from a CAD data file (1) that stores shape data and determines circles and arc shapes by shape recognition. Shape recognition unit to extract (2
), an inner shape/outer shape determination unit (3) that determines whether the shape to be machined is inner circle machining or outer circle machining and determines the offset direction during machining, and the required shape accuracy of the machined shape. a shape accuracy setting section (4) for setting, a coefficient setting section (5) for setting coefficients of a predetermined cutting width calculation formula that defines the relationship between the offset amount, processing speed, and cutting width;
A machining speed calculation formula coefficient setting section (6) that sets coefficients for a machining speed calculation formula that determines the maximum machining speed that satisfies the required shape accuracy from the required shape accuracy and off-cut cutting width, and a machining speed calculation formula coefficient setting section (6) that solves this machining speed calculation formula. It has a machining speed calculation section (7) that sets the machining speed.

[For production]

In the present invention, due to the delay in the positioning system of the NC servo system, the center trajectory of the laser beam during actual laser processing is always longer than the trajectory of the laser beam center expressed inside the NC control device, which is offset from the CAD shape data. This takes advantage of the phenomenon of becoming smaller. That is, in FIG. 2, 9 is NC111J? 1 shows the trajectory (calculated value) of the laser beam center expressed inside the device, and 10 shows the trajectory that the laser beam center actually passes during processing. S is the processing start point.

In this way, Ncll? Although the locus of the laser center represented in the apparatus 11 incorporates an offset into the CAD shape data, the actual machining locus is always smaller than the locus 9 as shown at 10. The difference ΔR between these trajectories is the machining error. It is known that the value can be derived from the following mathematical formula (machining speed polynomial) from servo theory.

However, R (-m)・Radius F of trajectory 9 (wm/5ec)=machining speed T, (see)・Time constant of positioning system Also, the above equation (1) is when the exponential acceleration/deceleration of the servo motor itself constant T
It is also known that when expressed using x (sec), it can be replaced with the basic formula.

In the present invention, any formula may be used.

As can be understood from the above equation, the error ΔR increases as the radius R of the circle (or arc) that is the machining shape decreases, and the machining speed F
The faster it gets, the bigger it gets.

Here, as an example, it is assumed that a diagonal line part 53 having a round hole 55 is cut out from a plate material 51 by laser processing as shown in FIG. Among the portions 53, machining of the straight portions is outside the scope of the present invention, so only the machining of the round holes 55 and the arcuate edge portions (hereinafter referred to as rounded portions) 57 are of concern here.

In Fig. 7, if we first focus on the round hole 55, this part is the part that is discarded on the inside (the part at the center) when viewed from the center of the circle, and the rounded part (radius R') 57 is the part of the arc of the circle. The outside of the circle when viewed from the center is the part to be discarded.

Hereinafter, for convenience, we will refer to the former (no need for the inside) as "inner circle machining" and the latter (no need for the outside) as "outer circle machining".Circle (or arc) machining is referred to as "inner circle machining" or " It can be broadly classified into one of two types: "outer circle machining."

The effects in both cases will be explained in more detail below.

Figure 3 (A) shows the case of inner circle machining e) described above, and the same figure (
B) shows the case of outer circle machining.

First, in Figure 3 (A), 9 is NC, similar to Figure 2.
The locus of the laser center expressed inside the control device is shown, 1
0 indicates the locus of the laser center during actual processing. Also, 1
1 indicates the circle represented by the CAD data (the circle to be actually processed). In laser processing, the processing width W processed by the laser beam is smaller than the laser beam radius (FIG. 8). In other words, in laser processing, there are parts that melt due to the heat around the beam, so it is not possible to process to the same size as the beam diameter, and the processing width W is always larger than the beam diameter.

As will be described later, the cutting width (processing width) decreases as the processing speed increases.

In FIG. 3(A), 12 indicates a circle actually processed by the laser beam (located outside the outer diameter of the laser beam).

Therefore, in the figure, the shaded area indicates the shape error (Δ
(equivalent to R).

Also, in the case of the outer circle machining shown in FIG. 3(B), shape errors shown by diagonal lines occur in exactly the same way as in the case of the inner circle machining in FIG. The required value of this shape error (accuracy) varies depending on the use of the product and is determined in advance by design and the like.

On the other hand, R (radius) and T in the above formula (1) or (2)
1. T□ (time constant) is also a known number, and is set together with ΔR by the machining speed polynomial coefficient setting section. Thus, the maximum machining speed that satisfies the shape accuracy can be determined using this machining speed polynomial.

FIG. 6 shows the relationship between the processing speed j[F and the cutting width W, which is given by the following equation (3).

W electric aF+b... (3) However, a
- coefficient, b constant number term.

In reality, we investigated the relationship between machining speed F and cutting width W through experiments, and applied the method of least squares to the experimental data, assuming that the relationship between F and W can be expressed by a linear function equation. (3)
Determine the coefficient a and constant term s of the equation.

〔Example〕

FIG. 4 shows an embodiment of the present invention. The embodiment shown in the figure is based on CAD data in laser processing.
A post module 75 includes a machining condition setting section 71 and a tool movement section 73, which basically have the same configuration as that shown in FIG. 1. It is configured as.

The tool interlocking section 73 has a tool motion description section 14 that describes the motion of the laser corresponding to the tool, and its data is stored in the NG data file 8.

In the machining condition setting section 71, first, from a CAD data file l storing shape data (diameter, etc.), step 501 is performed.
(Fig. 5), the shape is read into the shape recognition unit 2, and circles and arcs are extracted by shape recognition (step 503). Based on this, it is determined whether the shape to be machined is inner circle or outer circle. Step 507)
, determine the direction of offset during machining. On the other hand, in step 505, the offset amount set by the cutting width calculation formula coefficient setting unit 5 and the relationship between the machining speed and the cutting width are provided to the machining speed polynomial coefficient setting unit 6, which is known per se.
Step 511), and manually enter the shape accuracy (4R) required for the product into the shape accuracy setting section 4 using an external input device such as the keyboard device 20 (Step 509).
, Equation (1) or (2) in the machining speed polynomial coefficient setting section 6
). Note that this data input may be stored in advance in the shape accuracy setting section 4 without using an external input means.

From the above, ΔR, R in formula (1) or (2),
T, is set (step 511).

By solving this polynomial in the machining speed calculating section 7, the maximum machining speed that satisfies the required shape accuracy is determined (step 513), and then the maximum machining speed thus determined is set (step 515) and the laser output is Setting section 13
Determine the output of When the machining speed for a predetermined machining location (for example, the round hole 55 in FIG. 7) is determined in the above manner, the machining speed for all the locations to be machined (for example, the rounded portion 57 in FIG. 7) is determined in step 517. Step 507 is performed until the total machining speed is determined.
Repeat the steps below.

Note that the laser output setting unit 13 determines the laser output that enables cutting at the processing speed set by the processing speed calculation unit 7 based on the material and thickness of the plate material, and at the same time determines the pulse oscillation that applies the laser in a pulsed manner. The laser irradiation conditions are also determined, such as whether to apply continuous oscillation or continuous oscillation.

〔Effect of the invention〕

As described above, according to the present invention, by analyzing the delay of the positioning system (servo system) of the laser processing machine used, the relationship between cutting width and processing speed, it is possible to simply input the shape accuracy required for the product. , it is possible to determine a machining speed that always provides stable shape accuracy regardless of the size of the shape, which greatly contributes to improving yield.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the basic configuration of the present invention, Fig. 2 is a diagram showing the relationship between the trajectory of the laser center expressed inside the NC control device and the trajectory in which the laser center actually moves during processing, and Fig. 3
Figures (A) and (B) show the locus of the laser center expressed inside the NC11il device, the actual locus of the laser center during machining, and the circular arc represented by CAD data during inner circle machining and outer circle machining, respectively. , a diagram showing the relationship between the arcs actually processed,
FIG. 4 is a block diagram showing an embodiment of the present invention, FIG. 5 is a flow chart showing an embodiment of the present invention, and FIG. 6 is a block diagram showing an embodiment of the present invention.
FIG. 7 is a diagram showing the relationship between cutting width and processing speed, FIG. 7 is a diagram showing an example of a processing shape, and FIG. 8 is a diagram explaining the relationship between actual cutting width and laser beam diameter. 1... CAD data file, 2... Shape recognition section, 3... Inner shape/outer shape determination section, 4... Shape accuracy setting section, 5... Cutting width calculation formula coefficient setting section, 6 ... Machining speed polynomial coefficient setting unit, 7... Machining speed calculation unit, 8... NC data file.

Claims (1)

[Claims] 1. When processing a circle or an arc with a laser beam while relatively moving the laser beam and the workpiece using an NC device, the diameter of the processed shape required for the workpiece, the shape accuracy, and the NC A method for setting a machining speed for a laser processing machine, characterized by calculating a maximum machining speed from a delay in a positioning system of the device and a cutting width that depends on the machining speed. 2. In a laser processing machine that processes circles or arcs with a laser beam while relatively moving the laser beam and workpiece using an NC device, the diameter of the processed shape required for the workpiece, shape accuracy, and positioning of the NC device A machining speed setting device for a laser beam machine, characterized by having means for calculating a maximum machining speed from a system delay and a cutting width that depends on the machining speed. 3. Shape recognition that takes in the machining shape data and recognizes the shape in a laser processing machine that processes circles or arcs with a laser beam while moving the laser beam and workpiece relative to each other using an NC device based on predetermined machining shape data. part (2), an inner shape/outer shape determination part (3) which determines the offset direction during machining by determining inner circle machining or outer circle machining of the machining shape, and a part (3) that determines the required shape accuracy of the machining shape. A shape accuracy setting section (4) for setting, a coefficient setting section (5) for setting the coefficients of a predetermined cutting width calculation formula that defines the relationship between the offset amount, processing speed, and cutting width, and the size and requirements of the processing shape. The machining speed calculation formula coefficient setting section (6) sets the coefficients of the machining speed calculation formula that determines the maximum machining speed that satisfies the required shape accuracy from the shape accuracy, offset amount, and cutting width, and the machining speed calculation formula coefficient setting section (6) solves the machining speed calculation formula to determine the machining speed. Machining speed calculation unit (7
) A processing speed setting device for a laser processing machine.