JPH1085975A - Laser beam machining method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser beam machining method by which the restriction of the thickness and the hole diameter of a material to be machined can be relaxed, and the material can be appropriately drilled. SOLUTION: After cutting the material 11 to be machined from a piercing point P1 to a working starting point P2 on a hole work line L3 along a cutting introducing line L1, the material 11 is notched and cut along the hole work line L3 from the working starting point P2 to a notch completion point P3 to form a notch groove 15. After that, a nozzle is moved to the working starting point P2, and the material 11 is cut along the hole work line L3 from the starting point P2 to the notch completion point P3 to form a hole 17.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser cutting method for cutting a hole such as a round hole or a square hole in a workpiece such as a steel plate by using a laser beam and an assist gas.
In particular, the present invention relates to a laser processing method capable of eliminating adverse effects on products due to burning (abnormal combustion).

[0002]

2. Description of the Related Art Using a laser beam and an assist gas,
In the conventional processing method for cutting a workpiece such as a steel plate into a predetermined shape, an optimum cutting condition is empirically obtained from the material and the thickness of the workpiece, and the nozzle is coated based on the processing condition. The workpiece is positioned at the cutting start point, laser light is emitted from the nozzle, and processing is started at a predetermined cutting speed from the cutting start point.

[0003] In the vicinity of a lead portion of a hole shape of a thick steel plate, a small hole processing portion, or a corner portion of a processing shape, a normal processing speed and a processing condition of laser output are changed to control each material and plate thickness. Processing is performed based on processing conditions such as the processing speed, laser output, assist gas pressure, and pulse duty set in the apparatus. After processing a predetermined length, the processing is switched back to normal processing conditions and processing is performed again. ing. In particular, for example, in the processing of a small hole in a steel plate having a thickness of 9 mm or more and the corner portion, the moving speed of the nozzle and the laser output are reduced in order to secure the processed shape.

[0004] In the case of, for example, small hole drilling of a workpiece 11 made of a steel plate, as shown in Fig. 11, a hole drilling line L3 extends from a piercing point P1 at the start of processing along an introduction line L1.
Cutting is performed up to the upper processing start point P2 to form the introduction groove 14. Further, in a portion reaching the hole processing line L3, the hole enters the hole processing line L3 at a predetermined angle, a right angle, or a small arc locus, and the processing is performed. Then, by moving the nozzle from the processing start point P2 in the direction of the arrow of the hole processing line L3 and returning the nozzle to the processing start point P2, a hole processing groove 16 is formed, and a predetermined hole 17 is formed in the workpiece 11. Has formed.

[0005]

However, at a point P4 immediately before the processing end point P2 of the hole processing groove 16 (also the same point as the processing start point P2), a turbulent flow of the assist gas ejected from the nozzle causes a problem. There is a problem in that heat is accumulated in the workpiece 11 to cause erosion and a desired processed shape cannot be obtained. Since the movement of the nozzle in the groove near the cutting start point P2 is changed by approximately 90 degrees, the speed is temporarily reduced, so that even if the laser processing conditions are changed, the groove is not as sharp as the other processing parts.
The width (cut groove width) is wide. Further drilling line L
At the cutting start point P2 of FIG.
At a point P4 immediately before the end point of the machining, the assist gas flows into the introduction groove 14 immediately before the end of the hole machining, and the assist gas is turbulent and the normal cuff width can be maintained. However, the following problem occurs near the point P4 immediately before.

The hole 1 having a diameter smaller than the thickness of the workpiece 11
In the processing of FIG.
As shown in (a), the shape of the hole 171 on the front surface side is circular to some extent, and the outer peripheral edge of the inner scrap portion 19 is also substantially circular, and there is no particular problem. However, on the back surface of the workpiece 11, as shown in FIG. 12B in which the back surface is seen through from the front surface at the point P <b> 4 immediately before, a scrap portion 191 is formed in the scrap portion 19 and the hole 172 on the back surface side is missing. Part 1
There is a problem that the inner peripheral surface 172a corresponding to 91 has an irregular shape. Further, a residue 20 of the molten metal of the workpiece 11 is generated between the cutout portion 191 and the inner peripheral surface 172a.
Thus, there is a problem that the scrap portion 19 is welded to the scrap portion 19 to prevent the scrap portion 19 from dropping from the hole 172, thereby making the hole processing impossible. In particular, when the hole diameter is small, the scrap portion 19 becomes small and its weight becomes light.
The welding force makes it difficult for the scrap portion 19 to fall.

[0007] The generation of the residue 20 is explained as follows. That is, as shown in FIG. 13, when the nozzle 12 is moved to the left in FIG.
As the lower end of the workpiece 11 is cut to the right, an uncut portion 111 is generated below the workpiece 11. Then, while the laser beam 13 is moved from the immediately preceding point P4 to the processing start point P2 while maintaining this state, the laser beam 13 flows out into the introduction groove 14 together with the assist gas. As a result, the uncut portion 111 deviates from the normal cutting conditions including the assist gas, so that the uncut portion 111 is melted to form a residue 20, and this residue 2
With 0, the scrap portion 19 is welded to the peripheral surface 172a of the hole 172 to prevent the scrap portion 19 from dropping.

Therefore, according to the conventional processing method, not only the processing shape of the hole 172 on the rear surface side is deformed, but also
There is a problem in that the relationship between the thickness of No. 1 and the size of the hole 17 is restricted as shown by the chain line curve in FIG. That is, FIG. 6 shows the relationship between the minimum hole diameter and the thickness that can be processed to obtain an appropriate processing shape by taking the thickness of the workpiece 11 on the horizontal axis and the hole diameter on the vertical axis. It is. According to this graph, for example, when the material SS40 of the workpiece 11 has a thickness of 10 mm, the hole diameter is 8 mm or more and the thickness is 15 m.
m, the hole diameter is 12 mm or more, and the thickness is 20 mm,
There is a problem that the hole diameter is limited to 22 mm or more.

The present invention has been made in view of the problems existing in the prior art, and a first object of the present invention is to alleviate the restrictions on the thickness of the workpiece and the hole diameter. It is another object of the present invention to provide a laser processing method capable of reliably and appropriately performing a hole drilling on a work material.

A second object of the present invention is to provide a laser processing method capable of appropriately forming a cut groove in addition to the first object. A third object of the present invention, in addition to the first or second object, is to provide a laser processing method capable of performing an operation of returning a nozzle to a processing start point and improving processing efficiency.

A fourth object of the present invention is to provide, in addition to any one of the first to third objects, a method of processing a workpiece along a hole processing line in which an oval or a plurality of circular arcs are formed in a web shape. It is therefore an object of the present invention to provide a laser processing method capable of performing hole processing more appropriately.

A fifth object of the present invention is to provide, in addition to any one of the first to third objects, a laser processing method capable of processing a square hole more appropriately. According to a sixth object of the present invention, in addition to the first object,
An object of the present invention is to provide a laser processing method capable of improving processing efficiency.

[0013]

According to the first aspect of the present invention,
In order to achieve the first object, in a laser processing method of irradiating a workpiece with laser light output from a nozzle and injecting an assist gas along the laser light to drill a hole, a piercing point is used. After cutting the workpiece to the processing start point on the hole processing line along the cutting introduction line, cut the workpiece from the processing start point to the cutting end point along the hole processing line to form a cutting groove, Thereafter, the nozzle is returned to the processing start point, and the workpiece is cut from the processing start point to the cut end point along the hole processing line in a direction opposite to the cut groove.

In the invention according to claim 2, the second
In order to achieve the above object, in claim 1, the incision cutting of the workpiece from the machining start point to the incision end point is partially performed on a hole machining line, and the incision machining condition is lower than a normal cutting speed. The operation is performed at a low speed and lower than the normal laser output.

According to a third aspect of the present invention, in order to achieve the third object, in the second aspect, the laser beam and the assist gas are temporarily stopped when the cutting and cutting are completed, and the processing of the nozzle is started. To a normal cutting condition at the processing start point.

According to a fourth aspect of the present invention, in order to achieve the fourth object, in any one of the first to third aspects, the hole machining line is formed by forming an elliptical shape or a plurality of circular arcs into a web shape. The cut end point is set on the curve where the curvature of the hole processing line is the largest.

In the fifth aspect of the present invention, the fifth aspect is provided.
In order to achieve the above object, in any one of the first to third aspects, the cut end point is set on a straight line of a square hole processing line.

According to a sixth aspect of the present invention, in order to achieve the sixth object, in the first aspect, the cut end point of the cut groove is defined as a point at which the forming angle from the processing start point exceeds 180 degrees. After performing the processing of the cut groove under the normal processing condition, the nozzle is moved to the processing start point in a state where the laser output is stopped, and the processing condition is slower than the normal cutting processing speed at the processing start point. Means is adopted in which the processing conditions are switched to cut the workpiece from the processing start point to the cutting end point.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. This embodiment is a processing method for cutting a circular hole 17 having a predetermined radius in the workpiece 11. FIG. 4 shows a laser beam 1 so as to be close to the upper surface of a workpiece 11 such as a steel plate having a predetermined thickness.
3 and a path for moving the nozzle 12 for irradiating the assist gas. This path, laser beam and assist gas generation conditions, laser output, assist gas pressure, pulse duration
Processing conditions such as the tee and the processing speed are stored in advance in a memory of a control device (not shown) in accordance with the material, thickness, hole diameter, and the like of the workpiece 11. Then, by selecting a condition suitable for the hole diameter of the workpiece 11 to be machined and moving the nozzle 12, the hole machining is performed under appropriate conditions.

The cutting operation of the hole 17 will be described with reference to FIGS. As shown in FIG. 2A, first, a predetermined position of the workpiece 11, that is, the piercing point P1
Then, the laser beam 13 and the assist gas are output from the nozzle 12 to form a small hole substantially equal to the beam diameter.

Next, as shown in FIG. 2B, the nozzle 1 extends along the hole shape introduction line L1 from the piercing point P1 to a specific point of the hole processing line L3, that is, the processing start point P2.
2 is moved to form the introduction groove 14. In this step,
The processing conditions for the nozzle moving speed and the laser output are set lower than the normal processing conditions.

Next, the nozzle 12 is moved from the machining start point P2 in the clockwise direction in FIG. 2C, that is, in the direction opposite to the original machining direction, along the arc-shaped hole machining line L3, to a predetermined length. The cutting groove 15 having an arc shape is cut.
The nozzle center P3 at the tip of the cut groove 15 is the cut end point, and the laser light is temporarily stopped at this point P3. The cutting end point P3 is located at the hole 17 as described later.
This is also a processing end point where the processing of the above is completed in the final stage.

Next, in FIG. 2C, the nozzle 12 is returned along the cutting line L2 from the cutting end point P3. Thereafter, the processing is switched to the normal processing conditions at the processing start point P2, and cutting is performed in the counterclockwise direction along the hole processing line L3, thereby forming a circular hole processing groove 16 as shown in FIG. The hole processing groove 16 is formed toward the cutting end point P3. As shown in FIG. 1, the center point P4 of the nozzle for processing the tip of the hole processing groove 16 approaches the end point P3.

When the nozzle at the point P4 immediately before the end of the processing is moved from the approach state to the end point P3, the cut groove 1
A hole 16 is connected to 5. In this step, the cut groove 15 is formed in advance with a predetermined cuff width along the hole processing line L3. In the case of drilling, the direction of travel of the nozzle is tangent to the arc, so that the larger the radius of the arc, the closer to a straight line. Accordingly, at the end point P3 of the hole drilling of the workpiece 11, the assist gas linearly escapes to the cuff portion having a predetermined width. It does not disperse in all directions. In the case of an arc having a large radius, the condition is further improved. Therefore, the hole processing groove 16 is smoothly connected to the cut groove 15 with the same kerf width.

At the end point of drilling, the assist gas escapes linearly, so that the molten material also escapes linearly to the cuff.
The melt does not remain in the drilled groove 16 as a residue. Therefore, the scrap portion 19 is smoothly dropped from the hole 17. Further, the cutting end portion P3, particularly, the workpiece 11
Of the back surface side is eliminated, and a stable and high-quality drilled shape can always be obtained.

Further, in the processing of small holes, which has conventionally been regarded as a problem of laser processing, small holes having a diameter smaller than the diameter of the plate thickness, for example, about 1/3 of the plate thickness, can be formed. This is clear from the graph of FIG. That is, as shown by a processing limit curve indicated by a solid line in FIG. 6, when the plate thickness is, for example, 19 mm, the hole diameter becomes about 7 mm, and a hole with a smaller diameter can be formed as compared with the related art.

The cut groove 15 shown in FIG.
Assuming that the formation angle from the processing start point P2 to the end point P3 with respect to the piercing point P1 is α, this formation angle α
Is appropriately set depending on the diameter of the hole 17, the thickness of the workpiece 11, and the like. For example, if the diameter of the hole is small, 90
Degrees, and 30 degrees if larger.
When the thickness is small, the formation angle α is set small, and when the thickness is large, the formation angle α is set large.

Here, the operation and effect based on each configuration in the above embodiment will be described below. (A) In the above embodiment, the cutting and cutting of the workpiece 11 from the processing start point P2 to the cut end point P3 is partially performed, and the cutting conditions are a speed lower than a normal cutting speed and a normal cutting speed. Since the cutting is performed under a condition lower than the output, formation of the cut groove 15 can be performed reliably and appropriately. (B) In the above-described embodiment, the laser beam and the assist gas are temporarily stopped at the time when the cutting and cutting are completed, the nozzle is returned to the processing start point P2, and the normal cutting processing conditions are switched at the processing point. Therefore, the operation of returning the nozzle to the processing start point can be quickly performed, and the processing efficiency can be improved.

The present invention is not limited to the above embodiment, but can be embodied as follows. (1) As shown in FIG. 7, when the hole 17 to be machined has a square shape, from the piercing point P1 toward the machining start point P2 of the straight hole machining line L3 under conditions lower than the normal machining conditions. An introduction groove 14 is formed, and a linear cut groove 1 having a predetermined length is formed from this point to a cut end point P3.
5 is also formed under conditions lower than normal processing conditions.
After that, the nozzle is returned to the processing start point P2, the normal processing conditions are switched, and the square hole 16 is formed along the hole processing line L3.

In this embodiment, since the tip of the hole 16 is linearly opposed to the cut end point P3 at the processing end portion, the hole 16 faces the arc-shaped processing line of the embodiment at the time of the final processing of the hole 16. The processing operation can be performed more reliably and appropriately as compared with the method. (2) As shown in FIG. 8, in the case where the hole processing introduction line L1 after piercing cuts from outside the hole 17, the introduction line L1 is made to coincide with the direction of one side of the square hole processing line L3. Thus, the introduction groove 14 is formed under processing conditions lower than normal processing conditions. Next, a cutting groove 15 is formed from the processing start point P2 along a cutting line L2 on the other side under processing conditions lower than normal processing conditions, and when the nozzle moves to the cutting end point P3, the laser output is stopped. . Next, the nozzle is returned from the cutting end point P3 to the processing start point P2. Finally, at the point P2, the normal processing conditions are switched, and the nozzle is moved from the processing start point P2 to the processing end point P3 along the arrow direction of the hole processing line L3 to form the hole processing groove 16.

Also in this embodiment, since the cut groove 15 and the processing groove 16 are linearly opposed at the processing end portion, the same effect as in the embodiment shown in FIG. 7 is obtained. (3) As shown in FIG. 9, after the introduction groove 14 is formed under processing conditions lower than normal processing conditions, the cut groove 15 is formed under normal processing conditions so that the formation angle α becomes 180 degrees or more. Thereafter, the laser output from the nozzle is stopped at the cutting end point P3. Thereafter, the nozzle is advanced to the machining start point P2, and the nozzle is moved from the point P2 toward the point P3 to form the hole machining groove 16 under machining conditions lower than normal machining conditions.

In this embodiment, the laser can be moved to the processing start point P2 after stopping the output of the laser and the assist gas without stopping the nozzle until the cutting end point P3, so that the processing efficiency can be improved. it can. (4) As shown in FIG. 10, when the hexagonal hole 17 is machined, the introduction groove 14 is formed at the machining start point P of the hexagonal corner.
Set to 2. The processing end portion is set to a hexagonal side. When the cut end point P3 'is set at the hexagonal corner as shown on the left side of FIG. 10, the inclination angle θ between the cut groove 15 and the hole processing groove 16 becomes 120 degrees when the inclination angle θ is hexagonal. Compared to the case where a point having an inclination angle of 90 degrees or less is set as the cut end point, the restrictions on the thickness and the hole diameter of the work material can be relaxed, and the hole processing on the work material is appropriately performed. be able to. (5) In the processing method of each embodiment other than the embodiment shown in FIG.
At 3, the nozzle is moved at a low speed in the normal processing direction without stopping the laser beam, and processing is switched to normal processing conditions at the processing start point P2. (6) For example, an incision end point is set on an elliptical hole or a curve having the largest curvature among hole processing lines irregularly formed by a smooth curve.

In this case, it is possible to more appropriately form a hole in the workpiece.

[0034]

Embodiments of the present invention will be described below. The diameter is 6 with respect to the material SS400 of the workpiece 11 and the thickness of 16 mm.
When drilling a hole of mm, it depends on the following laser processing conditions. As the normal processing conditions described above, a laser output: 20
00 W, cutting speed: 800 mm / min, and assist gas (oxygen gas) pressure: 0.4 kg / cm ² .

Further, as processing conditions lower than usual as described above, laser output: 900 W, cutting speed: 100 mm / m
in, assist gas (oxygen gas) pressure: 0.4 kg / cm
² was used.

[0036]

As described above, according to the first aspect of the present invention, the restrictions on the thickness and the hole diameter of the workpiece can be alleviated, and the drilling of the workpiece can be performed reliably and properly. It has an excellent effect that it can be performed.

According to the second aspect of the present invention, in addition to the effect of the first aspect, the formation of the cut groove can be performed reliably and appropriately. According to the third aspect of the invention, in addition to the effect of the second aspect of the invention, the operation of returning the nozzle to the processing start point can be performed, and the processing efficiency can be improved.

According to a fourth aspect of the present invention, in addition to the effects of the first to third aspects of the present invention, an elliptical or a plurality of circular arcs are formed on a workpiece along a hole forming line formed in a web shape. Can be performed more appropriately.

According to the fifth aspect of the invention, in addition to the effects of the first to third aspects, it is possible to more appropriately process a rectangular hole. The invention according to claim 6 can improve the processing efficiency in addition to the effect of the invention according to claim 1.

[Brief description of the drawings]

FIG. 1 is a plan view showing an embodiment of a laser processing method embodying the present invention.

FIGS. 2A, 2B, and 2C are plan views illustrating processing steps of an introduction groove and a cut groove, respectively.

FIG. 3 is a plan view illustrating a processing step of forming a hole processing groove.

FIG. 4 is a perspective view illustrating a hole drilling method.

FIGS. 5A and 5B are cross-sectional views each showing a groove processing step.

FIG. 6 is a graph showing a relationship between a thickness of a workpiece and a hole diameter.

FIG. 7 is a plan view showing another embodiment of the present invention.

FIG. 8 is a plan view showing another embodiment of the present invention.

FIG. 9 is a plan view showing another embodiment of the present invention.

FIG. 10 is a plan view showing another embodiment of the present invention.

FIG. 11 is a plan view showing a conventional hole processing method.

12A is a plan view showing the shape of the upper part of a hole formed by a conventional processing method, and FIG. 12B is a plan view showing the shape of the lower part of the hole.

FIG. 13 is a sectional view showing the shape of a groove formed by a laser processing method.

[Explanation of symbols]

11: Workpiece material, 14: Cutting introduction groove, 15: Cut groove, 16: Hole processing groove, P1: Piercing point, P
2: Cut start point, P3: Cut end point, P4: Point immediately before cut end point P3, L1: Cutting introduction line, L2
… Cut processing line, L3… hole processing line.

Claims (6)

[Claims] 1. A laser processing method for irradiating a laser beam output from a nozzle onto a workpiece and injecting an assist gas along the laser beam to drill a hole, wherein the laser beam is emitted along a cutting introduction line from a piercing point. After cutting the work material to the processing start point on the hole processing line, the work material is cut from the processing start point along the hole processing line to the cutting end point to form a cut groove, and then the processing start point A laser processing method of returning a nozzle to the workpiece and cutting the workpiece from the processing start point to the cut end point along the hole processing line in a direction opposite to the cut groove. 2. The cutting method according to claim 1, wherein the incision and cutting of the workpiece from the machining start point to the incision end point are partially performed on a hole machining line, and the incision machining conditions are a speed lower than a normal cutting speed, Also, a laser processing method performed under conditions lower than a normal laser output. 3. The laser beam and the assist gas according to claim 2, wherein the laser beam and the assist gas are temporarily stopped when the cutting and cutting are completed.
A laser processing method in which a nozzle is returned to a processing start point and normal cutting processing conditions are switched at the processing start point. 4. The hole processing line according to claim 1, wherein the hole processing line is formed by forming an elliptical shape or a plurality of circular arcs into a web shape, and the cutting end point is a curve having the largest curvature of the hole processing line. The laser processing method set above. 5. The laser processing method according to claim 1, wherein the cut end point is set on a straight line of a rectangular hole processing line. 6. A cutting end according to claim 1, wherein the cutting end point of the cutting groove is set to a point at which the forming angle from the processing start point exceeds 180 degrees, and after processing the cutting groove under normal processing conditions, With the laser output stopped, the nozzle is moved to the processing start point, and at the processing start point, the processing conditions are switched to processing conditions lower than the normal cutting processing speed, and the processing is performed from the processing start point to the cutting end point. Laser processing method for cutting materials.