JP2010125517A - Laser machining method for pipe - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a process for performing fusion cutting of a pipe along its diagonal flat plane, which prevents the occurrence of level differences and deviations of the fusion-cut surface diagonally across the pipe in the shape of a round slice by a simple method and achieves a target fusion-cut surface of the pipe. <P>SOLUTION: A laser beam machining process for the pipe includes: a step of applying a laser beam from a laser machining head 4 to a pipe 1, an object to be machined, from the diagonal direction and performing the fusion cutting through a half of the pipe 1 in the manner of cutting the pipe 1 to make round slices; a step of reversing the pipe 1 by 180 degrees around a central line 6 in the longitudinal direction of the pipe 1 which is used as the axis of rotation; a step of applying the laser beam to the remaining half of the pipe 1 from the diagonal direction, performing fusion cutting of the remaining half in the manner of cutting the pipe to make round slices, thereby performing fusion cutting of the pipe 1 along the diagonal flat plane. Before fusion cutting is carried out, at least either of a top of the pipe 1 and both sides of the pipe 1 is measured by a sensor 7 near the fusion cutting position of the pipe 1, and the actual measured position and the ideal position of the pipe are compared. When correction is required, coordinates for machining are corrected in accordance with the amount of deviations between the actual pipe position and the ideal pipe position. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to a laser machining method for a pipe in which a laser from a laser machining head is applied to a pipe from an oblique direction, and the pipe is cut in a ring shape along a plane in the oblique direction.

When a long pipe is blown in a circular shape along an oblique plane by a laser processing machine, even if a laser processing head capable of controlling five axes is used, the laser processing head extends over 180 ° along the outer periphery of the long pipe. Since it is not possible to turn continuously, in the half-cut fusing process, half of the pipe is cut by the laser of the laser processing head, then the pipe is turned 180 degrees around the center line in the longitudinal direction of the pipe, and then The other half of the pipe is cut by the laser of the laser processing head.

However, if the pipe undergoes thermal deformation due to warping or twisting of the pipe, bending deformation of the pipe, especially fusing before reversal, the slanted cross-section of the cross-section melted before reversing the pipe and the slanted circular cut after reversal. The shape of the melt-shaped cross section deviates, and a step appears in the ring-shaped melt cross section, making it impossible to obtain the target melt cross section. Incidentally, if the ring-shaped molten cross section is perpendicular to the longitudinal center line of the pipe, the molten cross section does not appear as a large step compared to the oblique molten cross section.

On the other hand, for example, Patent Document 1 discloses processing a pipe with a laser processing machine, detecting a processing position of the pipe with a sensor, and correcting the position of the laser processing head based on the deviation.

However, since the technique of Patent Document 1 is only a simple correction of the machining position, the technique which is the premise of the present invention, that is, the laser of the laser machining head is applied to the pipe from an oblique direction, and half of the pipe is cut in an oblique direction. After the pipe is turned 180 degrees around the center line in the longitudinal direction of the pipe as the rotation axis, the laser of the laser processing head is applied to the other half of the pipe from the oblique direction, and the other half of the pipe is If the pipe is melted in an oblique direction and the pipe is melted along an oblique plane, it cannot be applied to the technology as it is.
JP 2004-216440 A

Therefore, the object of the invention is to apply the above-mentioned base technology, that is, apply the laser of the laser processing head to the pipe from an oblique direction, melt half of the pipe in an oblique direction, and cut the center line in the longitudinal direction of the pipe. After rotating the pipe 180 degrees as the axis of rotation, the laser of the laser processing head is applied to the other half of the pipe from the oblique direction, and the other half of the pipe is melted in a circular shape in the oblique direction, so that the pipe is flat in the oblique direction. Accordingly, in the process of fusing along the line, it is possible to prevent the occurrence of a step or deviation of the oblique cut surface of the melted section by a simple means so that the target melted section can be obtained.

Based on the above problems, the present invention applies a laser from a laser processing head to a pipe to be processed from an oblique direction, and melts half of the pipe in an oblique direction in a circular shape, and then the center line in the longitudinal direction of the pipe. After rotating the pipe 180 degrees with the rotation axis as the rotation axis, the laser from the laser processing head is applied to the other half of the pipe from the oblique direction, and the other half of the pipe is blown in an oblique direction to cut the pipe obliquely. In laser processing of a pipe that blows along the flat surface of the pipe, before cutting in an oblique direction, at least one of the upper surface of the pipe and both sides of the pipe is measured by a sensor near the fusing position of the pipe, Compare the measured actual pipe position with the ideal pipe position, and when correction is required, depending on the amount of deviation between the measured actual pipe position and the ideal pipe position, Correcting the target, and so on.

When the object to be processed is a square pipe, the actual pipe position is measured by measuring the provisional height of the actual pipe at the center of the ideal pipe position, and is lowered by a predetermined dimension a from the measured provisional height. The actual pipe side surface is measured at the position, and then the actual pipe top surface position is measured at a position displaced in the horizontal direction by a predetermined dimension b from the measured actual pipe side surface. A correction amount is obtained from the measured value of the actual pipe upper surface position.

When the object to be processed is a round pipe, the actual pipe position is measured by measuring the provisional height of the actual pipe at the center of the ideal pipe position, and both sides of the measured provisional height being lowered by the pipe radius r. Measure the actual pipe side surface at the position of the surface, then measure the actual pipe upper surface position at the measured middle point of both side surfaces, and measure the measured value of the intermediate point of the both side surfaces and the actual pipe upper surface position. The correction amount is obtained from the value.

The above sensor can be constituted by a gap sensor for copying attached to the laser processing machine. The pipe-shaped molten cross section in the diagonal direction is one plane or two or more planes. Further, the coordinates at the time of processing can be corrected only in the vertical direction according to the actual deformation mode of the pipe.

According to the present invention, before actual cutting in an oblique direction, an actual pipe position is measured by a sensor in the vicinity of the cutting position, and according to the amount of deviation between the measured actual pipe position and the ideal pipe position, This corrects the coordinates, so even if there is deformation or misalignment of the pipe before fusing, there is no step or deviation of the melted cross section in the diagonal direction before and after 180 degree reversal of the pipe. A molten cross-section is obtained.

When the workpiece is a square pipe, the actual pipe position is measured at the center of the ideal pipe position by measuring the actual height of the actual pipe, and the actual pipe position is lowered by the parameter a from the temporary height. Next, the actual pipe upper surface position is measured at a position displaced in the horizontal direction by the parameter b from the measured actual pipe side surface, and the measured value of the actual pipe side surface and the actual pipe upper surface are measured. The correction amount is obtained from the position measurement value. Therefore, even if the pipe is subject to vertical deformation or torsional deformation, the machining position can be corrected to an appropriate state by the minimum measurement.

When the object to be processed is a round pipe, the actual pipe position is measured by measuring the provisional height of the actual pipe at the center of the ideal pipe position, and by reducing the pipe radius r from the provisional height. Measure the actual pipe side surface at the position, then measure the actual pipe upper surface position at the measured middle point of both side surfaces, and measure the measured value of the intermediate point of the both side surfaces and the measured value of the actual pipe upper surface position. From this, the correction amount is obtained. Even if the pipe is deformed or displaced, there is almost no change in the pipe radius r, so that the actual position of the round pipe can be accurately determined at the machining position.

When the gap sensor for copying attached to the laser processing machine is used as the above-described sensor, no special sensor is required, and the actual pipe position can be easily measured, thus facilitating the implementation. In addition, when the slanted circular cross section is a single plane, there is no step in the melt cross section before and after 180-degree reversal of the pipe, the finish is improved, and there are two or more slanted circular cross sections, for example, two planes. In this case, the ridge lines of the peaks of the two planes or the groove lines of the valleys are not shifted and can be accurately formed at the target position. Furthermore, if the correction of coordinates is performed only in the vertical direction, it is possible to easily cope with thermal deformation and deflection deformation in the vertical direction that are likely to occur in the pipe during the laser processing.

1 to 6 show a pipe laser processing method according to the present invention. 7 and 8 show the actual pipe position measurement principle for a square pipe and a round pipe.

1 to 6, a pipe 1 to be processed (cutting target) is a rectangular metal pipe as an example, and is held by a clamp means 3 of an index device 2 attached to a laser processing machine 8. According to the illustrated example, the clamp means 3 fixes one end of the pipe 1 in a cantilever state, but may also be a double-supported type in which both ends of the pipe 1 are fixed. In the fixed state of the pipe 1, the X axis is set in the longitudinal direction of the pipe 1, the Y axis is set in the horizontal direction, and the Z axis is set in the vertical direction.

The laser processing machine 8 includes a laser processing head 4 that can control, for example, five axes, and the laser processing head 4 is controlled based on the reference coordinates on the laser processing machine side during processing by a preset program and numerical control. It moves along the processing path of the pipe 1. The attitude of the laser processing head 4 can be controlled with a high degree of freedom. However, the laser beam from the laser processing head 4 cannot be irradiated in a completely upward state, and the laser processing head 4 cannot be continuously swung over 180 ° along the outer periphery of the pipe 1.

In the fixed state of the pipe 1 shown in FIG. 1, the laser processing method for a pipe according to the present invention is at least one of the upper surface of the pipe 1 and the both side surfaces of the pipe 1 near the fusing position of the pipe 1 before fusing. Any surface is measured by the sensor 7, the measured actual pipe position is compared with the ideal pipe position, that is, the pipe position without any deviation, and the measured actual pipe position when the deviation amount is necessary to be corrected. The reference coordinates at the time of machining are corrected according to the amount of deviation from the ideal pipe position. The above correction can be performed using the local function of the numerical control program.

FIG. 7 shows a process of measuring the deviation amount of the square pipe 1. In FIG. 7, an imaginary line portion indicates an ideal pipe position, and a solid line portion indicates an actual pipe position. The displacement amount of the pipe 1 is measured by using a sensor 7 such as a scanning gap sensor attached to the laser processing machine 8 and using the sensor 7 at the center of the ideal pipe position as shown in (1). After approaching the actual pipe 1 and measuring the provisional height of the actual pipe 1, (2) measuring the actual pipe side face at a position lower than the provisional height by a predetermined dimension a, and then (3) The actual pipe upper surface position is measured at a position displaced in the horizontal direction by a predetermined dimension b from the measured actual pipe side surface, and these measured values are stored in the control unit 9 of the laser processing machine 8. The predetermined dimension a and dimension b are dimensions for measuring the shoulder portion of the square pipe 1 and are determined as values smaller than the corresponding side length in consideration of the expected displacement of the pipe 1. Is done.

Next, the control unit 9 obtains a lateral (horizontal) correction amount from the measured value of the pipe side in (2) above, the numerical value obtained from the lateral width of the pipe 1 and the ideal pipe position, and A correction amount in the vertical direction (Z-axis direction) is obtained from the measured value of the pipe side surface in (3) and the ideal pipe position, and when correction is necessary, the coordinates (y0, z0) at the time of machining are expressed as coordinates (y1, z1). ). This correction is necessary when the amount of deviation exceeds the allowable value.

Before the processing of FIG. 1, the rotation axis of the index device 2 and the linear axis of the laser processing machine 8, for example, the X axis, are set correctly in parallel, and the pipe 1 is correctly fixed to the clamp means 3 of the index device 2. In addition, if the pipe 1 is not deformed from the beginning, there is no deviation amount to be corrected as a result of the measurement. Therefore, little correction is generally required before the initial machining. Here, no correction is necessary.

Next, the laser processing head 4 applies the laser to the target fusing line 5 shown in FIG. 1 from an oblique direction as shown in FIG. 2, and the longitudinal center line of the pipe 1 as shown in FIG. As shown in FIG. 2, the pipe 1 is moved by sequentially moving from one position of the horizontal line passing through 6 to the left side, the upper side and the right side, and stopping at the other position of the horizontal line as the end position. The upper half of the upper half is blown in an oblique direction, and the upper half is cut into a ring shape. During processing, the laser processing head 4 moves on a plane including the target fusing line 5.

Due to the melting in the oblique direction, the pipe 1 is usually thermally deformed downward in the upper half due to heat at the time of melting. When the pipe 1 is long and thin, the downward bending deformation due to the weight of the free end is added to the downward thermal deformation.

Next, the pipe 1 is inverted 180 degrees by the clamp means 3 of the indexing device 2 with the center line 6 in the longitudinal direction (X-axis direction) of the pipe 1 as the rotation axis as shown in FIG. By this inversion, the inclination of the target fusing line 5 is in the opposite direction to the inclination of the target fusing line 5 in FIG. Even if the thermal deformation is slightly canceled by the downward deflection deformation due to this inversion, the pipe 1 is usually bent upward due to the thermal deformation accompanying the fusing in FIG. 2 after the inversion.

In the state of FIG. 4 after inversion, the actual pipe position is measured by the measurement of FIG. 7 before the fusing process, and the measured actual pipe position is compared with the ideal pipe position. When the deviation amount at that time exceeds the allowable value, the control unit 9 of the laser processing machine 8 corrects the coordinates at the time of processing according to the deviation amount. This correction can be performed using a local function of the numerical control program.

When there is a deviation amount in the Z-axis direction and a deviation amount in the Y-axis direction and correction is necessary, the coordinates (y0, z0) at the time of machining are displaced in the direction of these deviation amounts as shown in FIG. Thus, the coordinates are corrected to the coordinates (y1, z1). According to this processing mode, thermal deformation and deflection deformation both appear large in the vertical direction (Z-axis direction), and generally the amount of deviation in the Y-axis direction is small. Only in the Z-axis direction) is sufficient.

After the correction of the coordinates, as shown in FIGS. 5 and 6, the laser processing head 1 applies the laser to the remaining half of the pipe 1 from an oblique direction, and cuts the remaining half of the pipe 1 in an oblique direction. Is cut along an oblique plane. Also at this time, the laser processing head 4 is moving on a plane including the target fusing line 5. In FIG. 5 and FIG. 6, the thin line indicates the one before correction, and the solid line indicates the one after correction.

Thus, in the laser processing after 180 ° reversal, even if the pipe 1 is bent due to thermal deformation at the time of the first fusing as shown in FIG. 5, the coordinates are corrected at the time of processing. The cutting position of the ring-shaped 1 does not shift in the vertical direction. For this reason, the melt cross section before and after inversion does not have a step shape, but is accurately connected.

Next, FIG. 8 shows a process of measuring the deviation amount of the round pipe 1 as a processing target. In FIG. 8, the solid line portion of the pipe 1 indicates an ideal pipe position, and the broken line portion indicates an actual pipe position. In FIG. 8, the displacement amount of the pipe 1 is measured using a sensor 7 such as a gap sensor for copying, as shown in (1), at the center of the ideal position of the pipe 1 as shown in FIG. Measure the height, (2) measure the actual side of the pipe at the position of one side that has been lowered from the provisional height by the pipe radius r, and (3) the other that has fallen from the provisional height by the pipe radius r (4) The actual pipe upper surface position is measured at the midpoint between the measured both side surfaces, and these measured values are stored in the control unit of the laser processing machine.

The control unit 9 moves in the vertical direction (Z-axis direction) based on the difference between the measured value at the intermediate point in (2) and (3) above and the measured value at the measured point in (4) above and the ideal pipe position. Then, the correction amount in the horizontal direction (Y-axis direction) is obtained, and the coordinates at the time of machining are corrected when correction is necessary, as described above.

In the above example, the melted cross section in the oblique direction (melting line 5 viewed from the side surface) is a single plane, but the melt section has two or more, for example, 2 as illustrated in FIG. There may be two planes. Even in such a molten section, according to the processing method of the present invention, the ridge line or trough groove line of the molten section by two planes is practically accurate at the target position without being shifted after processing. Formed.

In the measurement process during the processing before reversal or the processing after reversal, if the rotation axis of the index device 2 and the linear axis of the laser processing machine 8, for example, the X axis are not set correctly in parallel, the pipe 1 is used as the index device. If the coordinates are corrected as a result of the measurement when the pipe 1 is not correctly fixed to the clamp means 3 or when the pipe 1 is deformed from the beginning, the deviation amount based on them is also corrected.

In the illustrated example, the pipe 1 is inverted using the index device 2, but the pipe 1 can also be inverted manually by an operator without using the index device 2. In processing, the pipe 1 is not limited to the horizontal direction, and can be held upright as a vertical direction or an inclined direction. In the case of the square pipe 1, when the horizontal position is tilted or twisted, the tilt or twist can be corrected by rotating the pipe 1 on the index device 2 side.

The present invention is not limited to the embodiment described above, and can be used for processing pipes having shapes other than those illustrated, and pipes made of materials other than metal.

It is a side view of a measurement process in the laser processing method of a pipe. It is a side view of a fusing process in the laser processing method of a pipe. FIG. 5 is a path diagram of a laser processing head in a pipe laser processing method. It is a side view of the measurement process after inversion in the laser processing method of a pipe. It is a side view of the fusing process after inversion in the laser laser processing method of a pipe. FIG. 5 is a path diagram of a laser processing head in a pipe laser processing method. It is explanatory drawing of the shift measurement of a square-shaped pipe. It is explanatory drawing of the shift | offset | difference measurement of a round pipe. It is the side of another melt section.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pipe 2 Index apparatus 3 Clamp means 4 Laser processing head 5 Fusing line 6 Center line 7 Sensor 8 Laser processing machine 9 Control unit

Claims (7)

The laser from the laser processing head is applied to the pipe to be processed from an oblique direction, and half of the pipe is melted in a circular cut in an oblique direction, and then the pipe is inverted 180 degrees around the center line in the longitudinal direction of the pipe. After that, the laser from the laser processing head is applied to the remaining half of the pipe from the oblique direction, the remaining half of the pipe is melted in a circular cut in the oblique direction, and the pipe is melted along a plane in the oblique direction. In
Before the cutting in the oblique direction, measure at least one of the upper surface of the pipe and both sides of the pipe with a sensor near the cutting position of the pipe, and determine the measured actual pipe position and the ideal pipe position. A laser processing method for a pipe, characterized in that the coordinates at the time of processing are corrected according to the amount of deviation between the measured actual pipe position and the ideal pipe position when correction is required. When the object to be processed is a square pipe, the actual height of the actual pipe is measured at the center of the ideal pipe position, and the actual side surface of the pipe is lowered by a predetermined dimension a from the measured temporary height. Next, the actual pipe upper surface position is measured at a position displaced in the horizontal direction by a predetermined dimension b from the measured actual pipe side surface, and the measured value of the actual pipe side surface and the actual pipe upper surface position are measured. The laser processing method for a pipe according to claim 1, wherein a correction amount is obtained from the measured value. When the object to be processed is a round pipe, the temporary height of the actual pipe is measured at the center of the ideal pipe position, and the actual height is measured at the positions on both side surfaces that are lowered by the pipe radius r from the measured temporary height. Measure the pipe side surface, then measure the actual pipe upper surface position at the measured midpoint of both side surfaces, and calculate the correction amount from the measured value of the intermediate point of the both side surfaces and the measured value of the actual pipe upper surface position. The pipe laser processing method according to claim 1, wherein the pipe laser processing method is obtained. 3. The pipe laser processing method according to claim 1, wherein the sensor is a copying gap sensor. 2. The pipe laser processing method according to claim 1, wherein the melt cross section of the pipe is a single plane. 2. The pipe laser processing method according to claim 1, wherein the melt cross section of the pipe is two or more planes. The pipe laser processing method according to claim 1, wherein the processing coordinates are corrected only in the vertical direction.

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