JP7320889B2 - Laser processing method - Google Patents

Description

The present invention relates to a laser processing method for performing laser processing.

In recent years, a technique has been proposed in which a cylindrical irradiation area extending in the direction of the optical axis of a laser is displaced in a direction that intersects the optical axis, thereby forming a processing surface on the surface side of the workpiece through which the irradiation area passes. (Patent Document 1). This processing method is an excellent processing method in that mechanical damage can be reduced and a smooth processed surface can be formed as compared with a mechanical processing method.

Japanese Patent No. 6562536

This type of machining method is used for corner regeneration in workpieces having corners formed by two adjacent surfaces, such as cutting tools having corners formed by a rake face and a flank face. It is also used for purposes such as Specifically, a laser is irradiated so that the optical axis extends along the direction in which the rake face or flank face expands, and by displacing this laser, a new rake face or flank face is formed as a machined face at the corner. can do.

However, during this process, the heat generated by the laser irradiation concentrates on the corners, causing ablation. I am worried about the situation. Therefore, there is a problem that laser processing is not necessarily effective for processing objects that require high processing accuracy, such as cutting tools for precision processing.

SUMMARY OF THE INVENTION The present invention has been made to solve such problems, and its object is to provide a laser processing method that can be effectively used for processing a workpiece that requires high processing accuracy. is.

In order to solve the above problems, a first aspect provides a corner formed by adjoining a first region extending along a predetermined plane and a second region extending along a plane intersecting the plane formed by the first region. a preparation procedure for preparing a workpiece having a part; an irradiation procedure for irradiating the workpiece with a laser so that an optical axis extends along a surface direction in which the second region spreads; and an optical axis of the laser. is displaced along one or both of the direction intersecting the plane formed by the second region and the plane direction in which the second region spreads, so that the second region is newly formed at the corner by the laser. and a processing procedure for forming a processing surface to be a region, and a material having a thermal conductivity of 1/20 or more of the processing object as the processing object, at least from the first region to the second region This is a laser processing method that uses a masked boundary region leading to .

Further, in this aspect, the following second aspect may be adopted.

In the second aspect, as the object to be processed, at least a boundary region from the first region to the second region is masked with a material having a thermal conductivity of 1/11 or more of the object to be processed. Use

Moreover, in each of the above aspects, a third aspect shown below may be used.

In the third aspect, in the irradiation procedure, the optical axis extends along the surface direction of the second region and in the direction from the first region to the second region or in the direction from the second region to the first region. The laser is irradiated so that the

Moreover, in this aspect, it may be like the 4th aspect shown below.

In the fourth aspect, in the processing procedure, when displacing the optical axis of the laser along the plane direction in which the second region spreads, along a ridgeline formed by the first region and the second region Displace.

The applicant of the present application has proposed a method for suppressing the concentration of heat due to laser irradiation on a corner when processing an object having a corner formed by two adjacent surfaces with a laser. I came up with the idea of masking the part, and as described later, I am conducting an evaluation test to find out what kind of material is effective for masking. As a result, it was found that masking with a material having a thermal conductivity of 1/20 (more preferably 1/11) or more of the object to be processed can effectively suppress the occurrence of ablation caused by laser irradiation. .

Therefore, in the processing method using the object to be processed as in each of the above aspects, the occurrence of abrasion caused by laser irradiation can be suppressed, and the surface roughness of the corner can be made uniform. It can also be effectively used for machining objects that require high machining accuracy, such as cutting tools for precision machining.

Block diagram showing the overall configuration of a laser processing device Block diagram showing the configuration of the irradiation unit Enlarged view of main part of workpiece Flowchart showing a processing procedure for processing Diagram showing the energy distribution in a laser Microscopic image of sample in evaluation test A diagram showing a workpiece in another embodiment

A mode for carrying out the present invention will be described in detail with reference to the drawings.

(1) Apparatus configuration As shown in FIG. A displacement mechanism 30 for relatively displacing the irradiation unit 10 and a control unit 40 for controlling the operation of the entire laser processing apparatus 1 are provided.

As shown in FIG. 2, the irradiation unit 10 includes an oscillator 11 that outputs a pulse laser, a vibration adjuster 13 that adjusts the order of the laser frequency, an attenuator (ATT) 15 that adjusts the laser output, and a laser diameter. A beam expander (EXP) 17 or the like is provided for adjustment, and the laser beam that has passed through these is output through an optical lens 19. to irradiate the laser. Among these, the oscillator 11 uses an Nd:YAG pulse laser.

Here, although the configuration is made up of a single optical lens 19, the configuration includes a set of optical lenses arranged at predetermined intervals and a mechanism for adjusting the intervals between the optical lenses. may be

The holding part 20 is a rod-shaped member extending in a direction intersecting the optical axis of the laser (the Y-axis direction in this embodiment), and is configured to be able to hold the workpiece 100 at its tip. This workpiece 100 is held in a positional relationship in which the end protrudes from the tip of the holding portion 20 .

The displacement mechanism 30 includes a mechanism main body 31 that displaces the irradiation section 10 and a driving section 33 that operates the mechanism main body 31 based on commands from the outside. In this embodiment, the mechanism main body 31 is configured to displace the irradiation unit 10 in two directions (X-axis direction and Y-axis direction in this embodiment) that intersect the optical axis of the laser. Note that the mechanism main body 31 may be configured to displace the holding portion 20 with respect to the irradiation portion 10 .

The control unit 40 is a computer that controls laser irradiation by the irradiation unit 10, relative displacement of the irradiation unit 10 by the displacement mechanism 30, and the like, according to control commands to each unit.

The workpiece 100 includes a first region 111 extending along a predetermined plane (the XY plane in this embodiment), and a plane intersecting the first region 111 (the YZ plane in this embodiment). It has corners 110 formed adjacent to a second region 113 that widens. In this embodiment, the workpiece 100 is a cutting tool in which one of the first region 111 and the second region 113 is formed as a rake face and the other is formed as a flank face, and is made of cemented carbide. is.

As shown in FIG. 3, this workpiece 100 has an area from the first area 111 to the boundary area 120 with the second area 113 that is 1/20 (preferably 1/11) or more of the workpiece 100. is masked with a material having a thermal conductivity of In the present embodiment, the mask layer 130 formed by this masking spreads along the first region 111, extends over the entire boundary region 120 beyond a new second region 113' that becomes a processing surface to be described later, but at least the new second region 113' extends. It suffices if the range up to reaching the second area 113' (that is, one end side of the boundary area 120) can be masked. The mask layer 130 is formed as a layer having a thickness (10 μm to 20 μm in this embodiment) corresponding to the diameter of the laser irradiation region 200 .

The first region 111 of the corner 110 of the object 100 extends along a plane (XY plane in this embodiment) intersecting the optical axis of the laser, and the second region 113 extends along the optical axis of the laser. It is installed in a positional relationship that spreads along the direction.

In the laser processing apparatus 1 having such a configuration, along the planar direction in which the second region 113 spreads, the direction from the first region 111 to the second region 113 or the direction from the second region 113 to the first region 111 ( In this embodiment, the laser is irradiated so that the optical axis extends along the direction from the first region 111 to the second region 113 parallel to the Z axis, and the corner 110 is displaced by displacing the laser. A new second region 113' can be formed as a processing surface.

(2) Processing Procedure by Control Unit 40 A procedure of "processing" executed by the control unit 40 by a program stored in the built-in memory 41 will be described below with reference to FIG. This machining process is executed after holding and positioning the workpiece 100 in the holding unit 20, and is started when an activation command is received from an interface (manipulation device or communication device, not shown).

When this processing is started, first, setting information stored in advance in the built-in memory 41 is read (s110). This setting information is information set by the user in advance, and the output P0 [w] of the laser irradiated by the irradiation unit 10 and the processing according to the material characteristics of the workpiece 100 installed in the holding unit 20 It consists of a threshold value Pth[w] and coordinate information defining each of one or more processing surfaces to be formed on the object 100 to be processed.

This coordinate information defines the positional relationship of the processing surface of the processing object 100 along the second region 113 of the corner 110 . This processing threshold value Pth is obtained from prior experiments using the pulse laser to be used and literature information. It is determined based on the input beam diameter.

In addition, the output level of the laser is such that the distance along the optical axis direction in the processable region of the irradiation region 200 is at least longer than the distance along the optical axis direction of the processing surface of the workpiece 100. It was set based on the relationship between Specifically, the output level P0 is set to a value greater than the processing threshold value Pth (P0>Pth).

Subsequently, a workable area is defined based on the setting information read in s110 (s120). The processable region is an energy distribution equal to or greater than the processing threshold value Pth [w] corresponding to the material properties of the object 100 in the irradiation region 200 extending cylindrically in the laser irradiated by the irradiation unit 10. It is an area, and the workpiece 100 can be processed using this area.

In step s120, the energy distribution P ( After r) is calculated, a tubular region is identified by connecting planar regions with a predetermined radius rth having an energy distribution equal to or greater than the processing threshold value Pth along the optical axis (see FIG. 5). Then, the radius rth in this area is specified as a parameter that defines the machinable area.

It has been confirmed by experiments that this machinable region changes from a linear cylindrical shape to a constricted cylindrical shape whose diameter decreases toward the focal position as the laser output P0 increases. . In other words, as the laser output P0 increases, the outer periphery of the processable area changes from a straight line to a curved shape. is selectively included in the setting information described above.

Next, it is checked whether or not there is an unformed processing surface (s130). Here, in the coordinate information among the setting information read out in step s110, if there is coordinate information that has not been referred to since the start of this processing, the unformed processing surface is determined to exist.

If it is determined in s130 that an unmachined surface exists (s130: YES), any coordinate information not referred to in the subsequent processing is extracted and defined by this coordinate information. A machined surface is set as a target machined surface to be formed in subsequent processing (s140).

Next, laser irradiation by the irradiation unit 10 is started (s150). Here, laser irradiation by the irradiation unit 10 that has received an instruction from the control unit 40 is started.

In this way, with respect to the workpiece 100, along the surface direction in which the second region 113 spreads, the direction from the first region 111 to the second region 113 or the direction from the second region 113 to the first region 111 (this embodiment In the form, the laser is irradiated so that the optical axis extends in the direction from the first region 111 to the second region 113 parallel to the Z-axis.

Next, the displacement mechanism 30 causes the irradiation area 200 of the laser irradiated by the irradiation unit 10 to approach the object 100 (s160). Here, a control command is issued to the displacement mechanism 30 so that the irradiation unit 10 is relatively displaced toward the holding unit 20 side, and the displacement mechanism 30 receives this command until the workpiece 100 and the machinable region overlap each other. , perform relative displacement of the irradiation unit 10 .

The overlap between the workpiece 100 and the processable area is determined based on the radius rth defined in s120 and the coordinate information of the machining surface set in s140. until the distance between (in this embodiment, the distance along the Y-axis direction) is a distance corresponding to the radius rth that defines the processable area of the irradiation area 200. It is realized by

Next, the displacement mechanism 30 scans the irradiation area 200 of the laser emitted by the irradiation unit 10 along the second area 113 of the workpiece 100 (s170). Here, a control command is issued to the displacement mechanism 30 so that the irradiation unit 10 is relatively displaced along the second region 113, and the displacement mechanism 30 that receives this command causes the irradiation region 200 to pass through the entire processing surface. , the relative displacement of the irradiation unit 10 is performed. Here, the optical axis of the laser is displaced along the ridgeline formed by the first region 111 and the second region 113 when displacing along the planar direction in which the second region 113 spreads.

In this way, through s160 to s170, the corner 110 of the workpiece 100 is processed into a processable region, and a new second region 113' is formed as a processed surface. After s170, the laser irradiation by the irradiation unit 10 started at s150 ends (s180). Here, the irradiation unit 10 that has received the instruction from the control unit 40 terminates laser irradiation.

Thus, after finishing s180, the process returns to s130, and s130 to s180 are performed until there is no more unmachined surface to be machined. After that, if it is determined in s130 that there is no unmachined surface to be machined (s130: NO), this machining process ends.

The workpiece 100 thus processed is used with the mask layer 130 removed from the corner 110 .

Note that s150 described above is the irradiation procedure in the present invention, and s160 to s170 are the processing procedure in the present invention. Further, the holding and positioning of the workpiece 100 on the holding unit 20 performed prior to processing are preparatory procedures in the present invention.

(3) Evaluation test When processing an object having corners formed by two adjacent surfaces, such as the object 100 described above, with a laser, the heat generated by the laser irradiation heats the corners. There is a concern that the ablation will be concentrated in the corners, and as a result, the surface roughness at the corners will not be uniform over the entire surface, and the surface roughness will be greatly different in some parts.

For example, when machining an object that requires high machining accuracy as a tool, such as a cutting tool for precision machining, the unevenness of the surface roughness at the corners affects the machining accuracy of the tool. This is not desirable because it has adverse effects.

The applicant of the present application came up with the idea of masking the corners as a method of suppressing the concentration of the heat accompanying the laser irradiation to the corners. Evaluation tests were conducted using multiple materials.

First, as a sample to be processed, a cylindrical cemented carbide K-type G10E (thermal conductivity: 105 W/m°C) manufactured by Sumitomo Electric Industries, Ltd. was used, and the end surface of the cylindrical shape was treated with the first material. A sample A masked with , and a sample B masked with a second material on the cylindrical end face were prepared. Here, sample A uses U alloy 78 (thermal conductivity of 9.6 W/m°C) manufactured by Asahi Metal Factory Co., Ltd. as the first material, and sample B uses phenol resin (thermal conductivity rate of 0.13-0.25 W/m·°C) is used. Then, regarding each sample, the cylindrical end face was regarded as the first region 111 and the outer peripheral surface was regarded as the second region 113, and the same processed surface was formed by the above-described processing.

When the cylindrical end face of each sample having the processed surface formed in this manner was observed under a microscope after washing, it was found that, as shown in FIG. It can be seen that it did not occur. On the other hand, in sample B, as shown in FIG. 6B, the corners are partially melted or fallen off, and evidence of re-solidification after melting is observed, and the surface roughness of the corners is not uniform. Or, there is a high possibility that the surface roughness is greatly different partially.

From this result, even if the material has a thermal conductivity lower than that of the object to be processed, a material having a thermal conductivity that is several tenths (for example, 1/20) or more of the object to be processed, such as the material containing the above sample, It has been suggested that the occurrence of ablation can be effectively suppressed by performing laser processing while masking the corners. On the other hand, it can be said that the occurrence of ablation cannot be suppressed by masking with a material having a thermal conductivity of less than 1/100 of the object to be processed. In other words, by masking the corners with a material having a thermal conductivity of 1/20 (more preferably 1/11) or more of the object to be processed, the occurrence of ablation caused by laser irradiation can be effectively suppressed. I understand.

(4) Modifications Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and can take various forms as long as they fall within the technical scope of the present invention. Needless to say.

For example, in the above-described embodiment, the laser is irradiated so that the optical axis extends in a direction extending from the first region 111 to the second region 113 along the surface direction of the second region 113 and parallel to the Z axis. exemplified. However, the laser may be irradiated so that the optical axis extends along the surface direction in which the second region 113 spreads, and the optical axis may be inclined with respect to the Z-axis. and the second region 113 may not be along the direction from one to the other.

In the above embodiment, the first region 111 of the workpiece 100 extends in a plane (XY plane), and the laser is scanned along this plane. However, the first region 111 of the part to be processed 100 is not limited to a planar one, and as shown in FIG. What is the second area 113 can also be adopted. In this case, after irradiating the laser so that the optical axis extends along the surface direction of the second region 113 and in the direction from the first region 111 to the second region 113, the optical axis of the laser is It may be displaced along the planar direction in which the second region 113 spreads and along the ridge line formed by the first region 111 and the second region 113 .

(5) Effect With the processing method of the above embodiment, the occurrence of ablation caused by laser irradiation can be suppressed, and the surface roughness of the corners can be made uniform. It can also be effectively used for machining objects that require high machining accuracy, such as cutting tools.

The machining method of the present invention can also be effectively used for machining objects that require high machining accuracy, such as cutting tools for precision machining.

DESCRIPTION OF SYMBOLS 1... Laser processing apparatus, 10... Irradiation part, 11... Oscillator, 13... Vibration adjuster, 15... Attenuator (ATT), 17... Beam expander (EXP), 19... Optical lens, 20... Holding part, 30... Displacement mechanism , 31...Mechanism body, 33...Drive unit, 40...Control unit, 41...Built-in memory, 100...Working object, 110...Corner, 111...First area, 113...Second area, 120...Boundary area, 130 ... mask layer, 200 ... irradiation area.

Claims (4)

A preparatory procedure for preparing a workpiece having a corner formed by adjoining a first region extending along a predetermined plane and a second region extending along a plane intersecting a plane formed by the first region. and,
an irradiation step of irradiating the object to be processed with a laser so that the optical axis extends along the surface direction in which the second region spreads;
By displacing the optical axis of the laser along one or both of a direction intersecting with the second region and a direction along the plane formed by the second region, the laser is applied to the corner. and a processing procedure for forming a processing surface that becomes the new second region,
As the object to be processed, at least the region from the first region to the boundary region with the second region is masked with a material having a thermal conductivity of 1/20 or more of the object to be processed,
Laser processing method.

As the object to be processed, at least a boundary region from the first region to the second region is masked with a material having a thermal conductivity of 1/11 or more of the object to be processed,
The laser processing method according to claim 1. In the irradiating step, the laser is arranged so that the optical axis extends along the surface direction of the second region and in the direction from the first region to the second region or in the direction from the second region to the first region. to irradiate
The laser processing method according to claim 1 or 2. In the processing procedure, the optical axis of the laser is displaced along a ridgeline formed by the first region and the second region when the optical axis of the laser is displaced along the surface direction in which the second region spreads.
The laser processing method according to claim 3.

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