JP3287133B2 - Laser processing machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser beam machine for shortening the piercing time and automatically adjusting the focus of a laser beam when performing laser beam machining.

[0002]

2. Description of the Related Art In the laser processing industry, it is required to reduce the processing time and the operation time of an adjustment operation in order to increase the productivity of the laser processing operation.

[0003] When laser cutting is performed using a laser processing machine, first, piercing is performed to make a small hole in a workpiece, and then cutting is performed. The processing time of this piercing process increases as the plate thickness increases, but even when the plate thickness is the same, changes in the material of the plate and surface conditions (such as unevenness and dirt)
This causes variations in the processing time. This variation in processing time tends to increase as the plate thickness increases. However, in order to surely perform the piercing, the set time of the piercing must be set longer than the longest piercing. In this method, even if the piercing process is performed in a short time, the process cannot immediately proceed to the cutting process in the next step, and a waste time is generated.

[0004] In order to shorten the piercing time, there has been proposed a method of detecting penetration and moving to the next step. As an example, a method of detecting penetration of the piercing process from the amount of reflected light of the laser beam that returns on the same axis as the optical axis of the laser beam during the piercing process (for example, Japanese Patent Laid-Open No. 2-165)
886) or a method of installing a thermocouple immediately below a piercing through-hole and detecting penetration of the piercing from the temperature of a laser beam receiving portion thereof (for example, Japanese Patent Laid-Open No. 2-2).
No. 05283).

When a lens is exchanged or a lens is cleaned as one of maintenance operations of a laser beam machine, a focal position of a laser beam is different from that before maintenance. Therefore, a focus adjustment operation must be performed. As a focus adjustment method, a method of irradiating a workpiece with laser light and detecting a focus position from the amount of reflected light (for example, JP-A-59-73192). and so on.

[0006]

However, in the above-mentioned conventional configuration, when detecting penetration of focus adjustment or piercing from reflected light, the reflectance varies depending on the material of the workpiece and the surface state of the workpiece. It is difficult to accurately detect the penetration of focus adjustment and piercing.

When a detector is installed immediately below a piercing hole, there is a danger that dust and workpieces resulting from the processing will accumulate and fall on the detection surface of the detector, making it impossible to detect them correctly. In addition, in order to directly irradiate a high-output laser beam used for piercing to the detector, a structure having high durability against the laser beam is required for the detector.

Further, the laser light does not always focus the outer light and the inner light at one point due to the spherical aberration. The outer light focuses on the near side and the inner light focuses on a farther position. Therefore, there is a problem that the accuracy of the optimal focus adjustment is reduced.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems and to provide a laser beam machine for accurately detecting penetration of a piercing process and shortening a piercing time and a focus adjusting time.

[0010]

In order to achieve the above object, a laser beam machine according to the present invention comprises a laser beam output means for outputting a laser beam, a temperature of an irradiated portion of a workpiece irradiated with the laser beam. And a penetration determining means for detecting penetration during piercing from the temperature detected by the temperature detecting means. When the detected temperature drops sharply after the start of piercing, the penetration of piercing is detected. Configuration.

A laser beam output unit for outputting a laser beam; a laser beam focusing unit for focusing the laser beam; a driving unit for driving the laser beam focusing unit; Temperature detecting means for detecting the temperature of the section; and focal length calculating means for calculating a focal length from the detected value of the temperature detecting means and the position data of the laser beam focusing means. The driving means is driven based on the result.

[0012]

[0013]

In the above arrangement, the detection data of the temperature detecting means for measuring the temperature of the portion of the workpiece to be irradiated with the laser beam is collected, and the change in the detection data is used to detect the penetration of the piercing process.

Further, an appropriate focal length can be determined from the detected value of the temperature detector and the position data of the laser light focusing means, and based on this, the laser light focusing means is driven to the optimum position.

[0015]

[0016]

【Example】

(Embodiment 1) Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic structural view of a laser beam machine according to a first embodiment of the present invention. 1 is a laser oscillator that outputs a laser beam 2, 2 is a laser beam output from the laser oscillator 1, 3 is a torch through which the laser beam 2 is transmitted, 4 is a condenser lens that collects the laser beam 2, and 5 is a condensing lens. A workpiece to be processed by being irradiated with the laser beam 2 having passed through the optical lens 4;
Reference numeral 7 denotes an NC control unit for controlling the positions of the laser oscillator 1, the torch 3 and the condenser lens 4 and a processing program, etc., 7 a torch drive unit for driving the torch in response to a command from the NC control unit 6, 8
Reference numeral 9 denotes a condenser lens driving unit that drives the condenser lens in response to an instruction from the NC control unit 6. Reference numeral 9 denotes a temperature detector that detects a temperature of a portion of the workpiece 5 where the laser beam 2 is irradiated and converts the temperature into an electric signal. Reference numeral 10 denotes a measurement point at which the temperature detector 9 measures temperature. Reference numeral 11 denotes a penetration determination unit that sequentially receives detection values output from the temperature detector 9 and determines penetration of piercing from a change in the received detection values. It is.

If an infrared temperature detector for detecting the temperature from infrared rays emitted from the object to be measured is used as the temperature detector 9, the temperature can be detected without contacting the object to be measured, but the temperature can be detected without contacting the object. Other things may be used as long as they can do it.

Next, the procedure for detecting penetration in the piercing process will be described. The measurement point 10 of the temperature detector 9 is adjusted to be located on the optical axis of the laser beam 2 and on the surface of the workpiece 5 so that the laser beam irradiating section and the measurement point 10 coincide. The height of the torch 3 at the time of piercing, the position of the condenser lens 4,
Piercing conditions such as laser output and assist gas pressure are set in advance to optimal values for the workpiece 5.

First, after moving the torch 3 to the position where the piercing is performed, the height of the torch 3 and the position of the condenser lens 4 are adjusted to the set positions, and the piercing is started under the set processing conditions. Simultaneously with the start of the piercing process, the temperature detector 9 detects the temperature of the measurement point 10 and outputs the detected value to the penetration determination unit 11. When the piercing process is started, the temperature of the laser beam irradiating part rapidly rises, and when the temperature reaches the melting point, the workpiece 5 is melted, blown off by the assist gas, and the depth of the piercing process is increased. When the melting portion reaches the back surface of the workpiece 5 and penetrates, the laser beam 2 penetrates, and there is no longer a portion irradiated with the laser beam 2 and having a high temperature, so that the temperature of the laser beam irradiating portion rapidly decreases. The temperature detected by the temperature detector 9 increases at the same time as the piercing process, and rapidly decreases at the same time as the penetration. The penetration judging unit 11 judges penetration at the time of piercing processing based on a sharp decrease in the detection data received from the temperature detector 9.

When the penetration determination unit 11 determines that the piercing process has been performed, the penetration determination unit 11 sends the NC control unit 6.
The NC control unit 6 receives this signal, terminates the piercing processing, shifts to the execution of the processing program of the next step, and newly transmits the laser oscillator 1, the torch drive unit 7, and the condenser lens drive unit 8. Command is output.

Since the temperature of the melting point and the rate of temperature change differ depending on the material and the thickness of the workpiece 5, the criterion for the penetration of the piercing process is set for each workpiece in consideration of these factors.

According to the above configuration, the temperature detector 9 does not receive the laser beam 2 directly, and the life of the temperature detector 9 is greatly extended. In addition, since the temperature of the irradiated portion of the laser beam is detected instead of the reflection of the laser beam to determine whether the laser beam has penetrated, the surface state of the workpiece is not affected. Further, since the temperature is detected from a position distant from the laser beam irradiation portion, contamination of the temperature detector 9 due to scattering of spatter or the like can be prevented,
It is possible to prevent a decrease in detection accuracy. Furthermore,
Since the torch 3 and the temperature detector 9 are provided integrally, it is possible to detect penetration regardless of where the torch 3 is moved.

(Embodiment 2) Hereinafter, a second embodiment of the present invention will be described with reference to the drawings.

FIG. 2 is a schematic structural view of a laser beam machine according to a second embodiment of the present invention. In the figure, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.
Reference numeral 12 denotes a focal length calculation unit that calculates a focal length from the position data of the condenser lens 4 when the detection value of the temperature detector 9 becomes maximum.

Next, the procedure of focus adjustment will be described. As in the first embodiment, the height of the torch 3 is adjusted so that the measurement point 10 of the temperature detector 9 is located on the optical axis of the laser beam 2 and is located on the surface of the workpiece 5.

A low-power laser beam 2 is output from a laser oscillator 1 and irradiates a workpiece 5. Note that this laser light 2
Is such that the workpiece 5 does not melt. The temperature detector 9 starts temperature detection simultaneously with the irradiation of the laser beam 2.
FIG. 3 is a diagram showing the operation of the condenser lens during focus adjustment.
The configuration of FIG. 3 shows a part of the configuration of FIG. 2 and illustrates the relationship between the position of the condenser lens 4 and the focal position of the laser beam 2. As shown in (a) → (b) → (c) in FIG. 3, the position of the condenser lens 4 is moved by a fixed distance, and the focal position of the laser beam 2 with respect to the workpiece 5 is changed.

The driving of the condenser lens 4 is performed as follows in this embodiment. That is, the NC control unit 6 as the drive control means moves the condenser lens 4 slightly above the position of the condenser lens 4 where the normal focus position is determined (on the opposite side of the workpiece 5). Then, first, the condenser lens 4 is driven toward the workpiece 5. If the condenser lens 4 continues to be driven, it will eventually reach the vicinity of the workpiece 5, but even at this stage, it may not be possible to determine the focal position. This can occur, for example, when the focal point is located above the original position of the condenser lens 4 (on the side opposite to the workpiece 5). Therefore, when the focus position cannot be determined at the time of driving to the workpiece 5 as described above,
The condenser lens 4 is driven in the opposite direction.
As a result, the focus position can always be determined as long as there is no abnormality in the apparatus, and the portion that becomes the normal focus position is determined first, so that quick focus position determination is possible.

Further, the condenser lens 4 can be driven as follows. That is, first, the condensing lens 4 is moved to the mechanical origin, which is the uppermost part of the driving range (the side opposite to the workpiece 5) by the NC control unit 6 as the drive control means. Next, the condenser lens 4 is driven toward the workpiece to calculate the focal position. By doing so, the wasteful operation of driving the condenser lens 4 in the reverse direction without finding the focal position and performing the focal position determination and calculation of the same part is eliminated, and the focal position is always required unless there is an abnormality in the apparatus. Can be determined. This is particularly useful for the first focus position determination.

In any of the above cases, the temperature detector 9 measures the temperature of the laser beam irradiating section every time the condenser lens 4 moves and stores it in the focal length calculating section 12. The focal length calculation unit 12 also stores the position data of the condenser lens 4 from the NC control unit 6 at the same time. After the necessary data of the temperature of the laser beam irradiation part and the position of the condenser lens 4 are obtained in this way,
The position of the condenser lens 4 when the detected temperature becomes maximum is searched, and the focal length is calculated from the position data.

When the position of the condenser lens 4 is moved while irradiating the laser beam 2, the entire torch 3 is moved in the horizontal direction in the vertical or horizontal direction, as compared with the case where the laser beam irradiating portion of the workpiece 5 is set at the same point. When the laser light irradiating part is changed by moving the laser light at a certain distance, heat is not accumulated in the laser light irradiating part of the workpiece 5 and its surroundings, so that accurate temperature detection can be performed. The moving distance of the condenser lens 4 for each temperature measurement is selected according to the desired focal length accuracy. The longer the moving distance in the horizontal direction for each measurement, the less the thermal effect may be. The movement of the condenser lens 4 and the movement of the torch 3 in the horizontal direction may be performed continuously. If the workpiece 5 has a uniform surface state without surface dirt or scratches, more accurate temperature detection is possible.

According to the above configuration, the temperature detector 9 does not directly receive the laser beam 2, and the life of the temperature detector 9 is greatly extended. In addition, since the focus position is detected based on a change in temperature, there is no problem of a decrease in detection accuracy due to a shift in the focus position due to spherical aberration generated when detection is performed by reflection of laser light.

Further, there may be a case where the focal position cannot be calculated due to displacement or breakage of the condenser lens 4 or other causes. In this case, in this embodiment, the output of the laser oscillator 1 is stopped and an alarm sound is issued. The determination of the inability to calculate the focal position may be made based on the position information of the condenser lens 4, the driving time of the condenser lens 4, or other means.

Thus, it is possible to inform the operator that the normal machining is not performed, and it is possible to return to a normal machining state at an appropriate timing. Also,
Since the output of the laser beam 2 is stopped, a safe laser processing machine can be provided in which an operator does not accidentally touch the laser beam 2 and cause injury when checking or repairing when the focal position is not found. Can be.

( Reference Example ) Hereinafter, a reference example of the present invention will be described with reference to the drawings.

FIG. 4 is a schematic configuration diagram of a laser processing machine according to a reference example of the present invention. In the drawing, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted. Reference numeral 13 denotes a light-emitting member which is provided below the workpiece 5 and serves as a penetration detection unit which emits light when irradiating the laser beam 2. For example, a metal plate such as an iron plate, a copper plate, and an aluminum plate can be used.
Other means may be used. Reference numeral 14 denotes a photodetector, which is a penetration change detecting unit that detects the amount of light emitted by the light emitting member 13 and converts it into an electric signal. The photodetector 14 is the laser beam 2
Is not directly hit (for example, immediately below the work piece 5,
(A position outside the moving range of the torch 3). The penetration determination unit 15 sequentially receives the detection values output from the photodetector 14, and determines the penetration of the piercing process from the change in the received detection values.

Next, a procedure for detecting penetration in the piercing process will be described. Height of torch 3 during piercing, focusing lens 4
The optimum values for the workpiece 5 are set in advance for the piercing conditions such as the position, laser output, and assist gas pressure.

First, after moving the torch 3 to the position where the piercing is performed, the height of the torch 3 and the position of the condenser lens 4 are adjusted to the set positions, and the piercing is started under the set processing conditions. Simultaneously with the start of the piercing process, the photodetector 14 detects the light amount of the light emitting member 13 and outputs the detected value to the penetration determining unit 15. When the piercing process is started, the temperature of the laser beam irradiating part rapidly rises, and when the temperature reaches the melting point, the workpiece 5 is melted, blown off by the assist gas, and the depth of the piercing process is increased. When the melting portion reaches the back surface of the workpiece 5, the laser beam 2 penetrates the workpiece 5. When the workpiece 5 penetrates, the laser beam 2 passes through the workpiece 5 and irradiates the light emitting member 13 installed below the workpiece 5. The light emitting member 13 emits light when irradiated with the laser light 2. This light causes the detection value of the photodetector 14 to rise sharply. When the detected data exceeds the reference value, the penetration determining unit 15 determines penetration during piercing.

When the penetration determination unit 15 determines the penetration of the piercing process, the penetration determination unit 15 sends the NC control unit 6
The NC control unit 6 receives this signal, terminates the piercing processing, shifts to the execution of the processing program of the next step, and newly transmits the laser oscillator 1, the torch drive unit 7, and the condenser lens drive unit 8. Command is output.

Since the amount of emitted light varies depending on the laser output, the criterion for piercing is set based on the laser output.

With the above configuration, even if the workpiece 5 drops (for example, the workpiece may be cut into a circle), it is on the light emitting member 13, and the photodetector 14 is connected to the light emitting member 13. Since the photodetector 14 is located at a remote position, the photodetector 14 is not damaged, and the life of the photodetector 14 can be greatly extended without scattering of spatter. Also, when the workpiece 5 is dropped, if there is a direct detector directly below as in the past, the detector is usually small and covered with the workpiece 5 and cannot be detected. In the reference example, since the light emitting member 13 such as an iron plate is used, the penetrating laser light 2 is diffused and irradiated onto the light emitting member 13 other than the workpiece 5 that has fallen, and the penetration can be detected. is there. Further, compared to a later-described device that uses a heat-generating member instead of the light-emitting member 13 to detect penetration from its temperature rise, the temperature hardly disappears immediately but no light remains. And the accuracy can be maintained at a high level.

It is to be noted that a light emitting member 13 that emits light of a specific frequency is used, and an optical frequency detector that detects the frequency of light is used instead of the photodetector 14 so that the light emitting member 13 emits light of a specific frequency. Even if the penetration of the piercing process is detected from the detection, the same effect can be obtained,
Further, since light of a specific frequency is detected, it is easily separated from external light, and is hardly affected by external light.

Further, instead of the light emitting member 13, a heat generating member that generates heat by laser beam irradiation is used, and instead of the photodetector 14, a temperature detector for detecting the temperature of the heat generating member is used.
It is also possible to detect the penetration of the piercing process from the temperature rise of the heat-generating member due to the laser beam irradiation. In this case, the life of the temperature detector is greatly extended, and the workpiece falling when the light-emitting member 13 is used is dropped. This has the same effect as that at the time, and has the effect that the influence of external light can be completely blocked. In this case, a metal plate such as an iron plate, a copper plate, and an aluminum plate can be used as the heat generating member, but other means may be used.

[0044]

As is apparent from the above description of the embodiment, the present invention is provided with a temperature detecting means, detects and collects the temperature of the laser beam irradiating portion of the workpiece, and collects the laser beam from the data. The focus adjustment of the optical means and the determination of the penetration of the piercing process can be performed, and the focus adjustment and the detection of the penetration of the piercing process can be reliably performed regardless of the surface condition of the workpiece.

[0045]

As long as there is no abnormality in the equipment, the focus can be adjusted without fail. Even if there is an abnormality in the equipment, the operator is notified of the occurrence of the abnormality and can perform prompt processing. Can ensure the safety of people.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a laser processing machine according to a first embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of a laser processing machine according to a second embodiment of the present invention.

FIG. 3 is a diagram illustrating a focus adjustment operation.

FIG. 4 is a schematic configuration diagram of a laser processing machine according to a reference example of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Laser oscillator 2 Laser light 3 Torch 4 Condensing lens 5 Workpiece 6 NC control part 7 Torch driving part 8 Condensing lens driving part 9 Temperature detector 10 Measurement point 11 Penetration determining part 12 Focal length calculating part 13 Light emitting member 14 Photodetector 15 Penetration determination unit

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B23K 26/00-26/38

Claims (7)

(57) [Claims] A laser beam output unit for outputting a laser beam; a temperature detection unit for detecting a temperature of a laser beam irradiation unit of the workpiece from a position remote from the laser beam irradiation unit; A laser processing machine provided with a penetration determination means for detecting penetration of piercing processing from a value. 2. The piercing process according to claim 1, wherein the piercing process detects the piercing process when the detected value of the temperature detecting device rapidly decreases after the start of the piercing process.
The laser processing machine as described. 3. A laser light output means for outputting a laser light, a laser light condensing means for condensing the laser light, a driving means for driving the laser light condensing means, and a laser light irradiation for the workpiece. Temperature detecting means for detecting the temperature of the section; and focal length calculating means for calculating a focal length from the detected value of the temperature detecting means and the position data of the laser beam focusing means. A laser processing machine for driving the driving means based on the result. 4. The laser beam machine according to claim 3, wherein the focal length calculating means calculates the focal length from the position data of the condenser lens when the temperature detected by the temperature detecting means becomes maximum. 5. The laser beam machine according to claim 3, wherein the drive means comprises drive control means for controlling the laser light focusing means to move the laser light focusing means to a mechanical origin and thereafter to drive the laser light focusing means. 6. A drive control means for driving the laser light focusing means to the workpiece side first, and then controlling the laser light focusing means to drive in the opposite direction.
The laser processing machine as described. 7. When an appropriate focal length cannot be determined,
4. The laser beam machine according to claim 3, wherein at least one of stopping the laser beam output means and issuing an alarm is performed.