JP2006326615A - Laser beam machining method and apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser beam machining method and apparatus for reducing thermal damage on the inner wall face of a pipe opposing to a machining face, for suppressing the deposit of spatters onto the inner wall face of the pipe, and for reducing burrs sticking to the cut part of the inner wall face of the pipe and dispensing with washing of the metallic pipe after laser beam machining, in cutting out an arbitrary pattern on the cylindrical face of the metallic pipe as a workpiece by laser beam machining. <P>SOLUTION: The laser beam machining apparatus is equipped with a machining table 2 for holding the metallic pipe 1 as the workpiece, a laser oscillator 21, and a nozzle 22 for emitting a laser beam 23. In performing laser beam machining, a gas 35 containing dry ice particles 36 supplied from a dry ice injection controller 31 is injected from an injection nozzle 34 to the hollow part of the metallic pipe 1. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a laser processing method and laser processing for producing a fine pipe-shaped metal product such as a stent by condensing and cutting a laser beam on an outer surface of a cylindrical surface of a metal pipe-shaped workpiece. Relates to the device.

  For example, in the treatment of atherosclerotic stenosis of blood vessels and the like, an expansion tool called a stent material is inserted into the stenosis portion of the blood vessels to prevent the blood vessels from being blocked. Various types of stent materials have been developed. For example, Japanese Patent Application Laid-Open Nos. 6-181993 and 10-155915 disclose an outer shape of 1.5 to 1.7 mm and a thickness of 0.05 to 0.00. A stainless steel pipe having a length of about 11 mm and a length of about 30 mm is manufactured by cutting into a desired pattern by laser processing.

  Japanese Patent Application Laid-Open Nos. 8-332230 and 2001-219286 disclose a laser processing method that solves damage to the inner wall surface caused by excess laser light and spatter adhesion.

  In JP-A-8-332230, a stainless steel pipe called a mandrel is built in a stainless steel pipe, and a desired pattern is cut by a laser beam while moving the stainless steel pipe under computer control. An assist gas, which is oxygen gas, is injected from the same axis as the light beam, and the melt is blown out through the hollow portion of the metal pipe. Further, the mandrel is disposed on the hollow bottom of the metal pipe so as to protect the inner wall surface facing the condensing point of the laser beam, and is rotated when cutting a desired pattern. Furthermore, one end of the mandrel is sealed to form a small hole on the side surface, this mandrel is placed directly below the condensing point of the laser beam, and a vacuum or positive pressure is introduced into the mandrel so that the melt generated during cutting is removed. I also try to remove it.

  In Japanese Patent Laid-Open No. 2001-219286, in order to protect the inner wall portion of the opposing pipe from thermal damage and to suppress the adhesion of spatter, a grease mixed with highly reflective powder is poured into the hollow portion of the pipe, and the surplus is made by the highly reflective powder. The laser beam is scattered and the spatter adhering inside the metal pipe is discharged out of the pipe together with the grease.

JP-A-6-181993 JP-A-10-155915 JP-A-8-332230 JP 2001-219286 A

  However, the above prior art has the following problems.

  In the prior art described in JP-A-6-181993 and JP-A-10-155915, a thin stainless steel pipe having a small diameter is cut into a desired pattern by laser processing. However, when a cylindrical surface of a thin metal pipe with a small diameter, such as a stent material, is cut through with a laser beam, an excess laser beam after the through cutting is applied to the inner wall surface of the pipe facing the processing surface of the metal pipe. There is a possibility of damaging the inner wall surface. In addition, spatter generated at the time of through cutting resolidifies and adheres to the inner wall surface of the metal pipe, and burrs are generated at the cut portion of the inner wall surface of the metal pipe. In order to remove the spatter and burrs, a mechanical or chemical process (such as electropolishing) is required, which takes a lot of time.

  In the prior art described in JP-A-8-332230 and JP-A-2001-129286, the use of a mandrel or grease prevents damage to the inner wall surface due to excessive laser beam and prevents spatter adhesion. it can. However, burrs generated at the cut portion of the inner wall surface of the metal pipe during laser cutting cannot be removed.

  In addition, the conventional technique described in Japanese Patent Application Laid-Open No. 2001-219286 also has a problem that a cleaning process for cleaning the grease attached to the inner wall surface of the pipe after processing is required.

  It is an object of the present invention to reduce thermal damage on the inner wall surface of a pipe facing the processing surface when performing a cutting process of an arbitrary pattern on a cylindrical surface of a metal pipe, which is a workpiece, by laser processing, and a sputter pipe It is an object to provide a laser processing method and a laser processing apparatus that suppresses adhesion to an inner wall surface, reduces burrs adhering to a cut portion of an inner wall surface of a pipe, and does not require cleaning of a metal pipe after laser processing.

(1) In order to achieve the above object, the present invention oscillates a laser beam by a laser oscillator, irradiates a cylindrical surface of a metal pipe as a workpiece with a laser beam output from the laser oscillator, and In the laser processing method of a metal pipe that penetrates and cuts the cylindrical surface of the pipe, the cylindrical surface of the metal pipe is laser processed while injecting a gas containing particles into the hollow portion of the metal pipe.

  In this way, by performing laser processing on the cylindrical surface of the metal pipe while injecting a gas containing particles into the hollow portion of the metal pipe, an excess laser beam penetrating and cutting through the cylindrical surface of the metal pipe is Therefore, it is possible to reduce the thermal damage of the inner wall surface of the metal pipe, and the spatter generated by laser processing is also introduced to the outside of the metal pipe by the gas injected into the hollow portion of the metal pipe. Since it is discharged, it is possible to reduce adhesion of spatter to the inner wall surface of the pipe. In addition, the particles injected into the hollow part of the metal pipe collide with the burr generated at the cut part of the inner wall surface of the metal pipe by laser processing to peel off the burr, and the gas that flows through the peeled burr by the gas flowing into the hollow part Since it discharges outside, the burr | flash adhering to the cutting part of an inner wall surface of a pipe can be reduced. In addition, since the gas containing particles injected into the hollow portion of the metal pipe is discharged to the outside, a special cleaning step as in the case of using grease is not required.

(2) Preferably, in (1) above, the particles are dry ice particles, ice particles, or ceramic particles.

  As a result, the action described in the above (1) is obtained, and in particular, when dry ice or ice particles are used as the particles, the temperature is low, so that there is a cooling effect. Since diffusion is suppressed, the cutting width can be narrowed and more precise processing can be performed. Furthermore, especially when dry ice particles are used as the particles, the laser energy is absorbed and sublimated when the laser beam is scattered, and transformed into carbon dioxide, which is an inert gas. And more precise processing becomes possible. Further, since the dry ice particles flowing through the hollow portion sublimate under atmospheric pressure, nothing is left after processing, and post-processing is extremely easy.

(3) Preferably, in the above (1) or (2), the gas is any one of nitrogen gas, argon gas, carbon dioxide, and air.

  As a result, the action described in the above (1) is obtained, and particularly when nitrogen gas, argon gas, or carbon dioxide gas is used, since these are inert gases, the melted portion caused by laser irradiation is localized. Precise processing is possible.

(4) In order to achieve the above object, a laser processing apparatus of the present invention irradiates a cylindrical surface of a metal pipe serving as a workpiece with a laser oscillator that oscillates a laser beam and a laser beam output from the laser oscillator. A nozzle for gripping the metal pipe to rotate and linearly move the metal pipe, and a control means for controlling the laser oscillator and the processing base to cut out a predetermined pattern on the metal pipe, And an injection device for injecting a gas containing particles into the hollow portion of the metal pipe.

  Thereby, the method of said (1) can be implemented, As a result, when performing the cutting process of arbitrary patterns to the cylindrical surface of the metal pipe which is a workpiece by laser processing, the pipe which opposes a processing surface It reduces thermal damage to the inner wall surface, suppresses spatter from adhering to the inner wall surface of the pipe, reduces burrs adhering to the cut portion of the inner wall surface of the pipe, and eliminates the need for cleaning the metal pipe after laser processing.

(1) According to the present invention, when performing a cutting process of an arbitrary pattern on a cylindrical surface of a metal pipe, which is a workpiece, by laser processing, heat damage on the inner wall surface of the pipe facing the processing surface is reduced, and It is possible to prevent spatter from adhering to the inner wall surface of the pipe, reduce burrs adhering to the cut portion of the inner wall surface of the pipe, and eliminate the need for cleaning the metal pipe after laser processing.
(2) Further, when dry ice or ice particles are used as the particles, the temperature is low, so that there is a cooling effect and more precise processing can be performed.
(3) In addition, when dry ice particles are used as the particles, they sublimate when the laser beam is scattered and transform into carbon dioxide, which is an inert gas, so that more precise processing can be performed. Since the dry ice particles flowing through the hollow portion sublimate under atmospheric pressure, nothing remains after the processing, and post-processing becomes extremely easy.
(4) Further, when nitrogen gas, argon gas, or carbon dioxide gas is used as the gas, since these are inert gases, precise processing can be performed.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram showing an overall configuration of a laser processing apparatus that performs a laser processing method according to an embodiment of the present invention.
In FIG. 1, a laser processing apparatus according to this embodiment includes a processing table 2 for holding and moving a metal pipe 1, and a laser irradiation apparatus that oscillates a laser beam and irradiates the metal pipe 1 with a laser beam 23. 20, a dry ice particle injection device 30 that injects nitrogen gas containing dry ice particles into the hollow portion of the metal pipe 1, and a CNC controller 40.

  The metal pipe 1 is a tube-shaped workpiece made of a metal material such as stainless steel, and is used to produce a fine pipe-shaped metal product such as a stent.

  The processing table 2 includes a uniaxial stage 14 and a rotation drive mechanism 15.

  The uniaxial stage 14 includes a base plate 10, a motor 11 and a bearing 13 provided on the base plate 10, one end connected to the motor 11, and the other end supported by the bearing 13, the movable plate 3, And a nut portion 8 provided on the lower surface of the movable plate 3 to which the screw shaft 12 is screwed.

  The rotational drive mechanism 15 includes a motor 6 and two bearings 4 and 5 provided on the movable plate 3, and a gripping portion 7 of the metal pipe 1 is connected to the output shaft of the motor 6. 4 and 5 are rotatably held.

  The motor 11 is driven and controlled by a linear movement command from the CNC controller 40, and the motor 6 is driven and controlled by a rotational movement command from the CNC controller 40.

  The laser irradiation apparatus 20 includes a laser oscillator 21 that oscillates laser light, and a nozzle 22 that irradiates a metal pipe 1 that is a workpiece with a laser beam 23 output from the laser oscillator 21. The laser oscillator 21 is controlled by a laser irradiation command from the CNC controller 40.

  The nozzle 22 is installed on the processing table 2 so that the laser beam 23 is perpendicularly incident on the side surface of the metal pipe 1, and focuses the laser beam 23 on the surface of the metal pipe 1. An assist gas is supplied to the nozzle 22, and the assist gas is jetted coaxially with respect to the laser beam 23. The assist gas is, for example, oxygen gas, and has an effect of promoting laser processing of the metal pipe 1 by being injected coaxially with the laser beam 23.

  The dry ice particle injection device 30 includes a dry ice injection control device 31, a liquefied carbon dioxide gas cylinder 32, a nitrogen gas cylinder 33, a dry ice injection control device 31, and an injection nozzle 34.

  The liquefied carbon dioxide gas cylinder 32 and the nitrogen gas cylinder 33 are connected to the dry ice injection control device 31 via hoses 32a and 33a, and by opening and closing a valve built in the dry ice injection control device 31, the liquefied carbon dioxide gas and the nitrogen gas are supplied. Control the supply. A valve built in the dry ice injection control device 31 is controlled by an injection command of the CNC controller 40.

  The dry ice injection control device 31 is connected to the injection nozzle 34 via a hose 31a. When a valve built in the dry ice injection control device 31 is opened, liquefied carbon dioxide gas and nitrogen gas are liquefied carbon dioxide gas in the hose 31a. Is supplied to the injection nozzle 34 through a hose for nitrogen and a hose for nitrogen gas. The injection nozzle 34 is changed into fine dry ice particles of several μm by injecting liquefied carbon dioxide gas from a micro orifice to a cooling effect by adiabatic expansion, and the dry ice particles are mixed with nitrogen gas. A gas (nitrogen gas) 35 containing dry ice particles 36 is injected from the opening. The principle of operation of the injection nozzle 34 is described in, for example, Japanese Utility Model Laid-Open No. 5-49258.

  The injection nozzle 34 is held in a state of being inserted into the metal pipe 1 from one side opening of the metal pipe 1, and injects a gas 35 containing dry ice particles 36 into the hollow portion of the metal pipe 1 during laser processing.

  The CNC controller 40 outputs a linear movement command and a rotational movement command to the motors 11 and 6 to control the motors 11 and 6, controls linear movement and rotation of the metal pipe 1, and outputs an irradiation command to the laser oscillator 21. Then, the laser oscillator 21 is controlled to control the irradiation / non-irradiation of the laser beam 23, thereby cutting a cut-out hole having a desired shape on the side surface of the metal pipe 1. In the CNC controller 40, a program for cutting out a desired pattern is recorded in advance. Further, the CNC controller 40 outputs an injection command to the dry ice injection control device 31 when the motors 11 and 6 and the laser oscillator 21 are controlled, and injects the gas 35 containing the dry ice particles 36 into the metal pipe 1. Let

  Next, the function and effect of this embodiment of the present invention will be described.

  FIG. 2 is a cross-sectional view of the metal pipe 1 showing a cutting state when the gas 35 is not injected into the hollow portion of the metal pipe 1 during laser processing.

  In FIG. 2, the laser beam 23 irradiated and condensed on the surface of the metal pipe 1 is absorbed by the metal to become heat, and the metal is cut by instantaneously melting, evaporating and removing the metal. At this time, the laser beam 51 surplus in the cutting process is applied to the pipe inner wall surface 54 facing the condensing position of the laser beam 23, and the part is melted or thermally damaged.

  Further, the metal piece melted and removed at the time of cutting is scattered as spatter 52 inside the metal pipe 1 and adheres to the inner wall surface of the pipe, and the metal which is melted and adhered to the periphery of the cut portion becomes a burr 53.

  Furthermore, heat at the time of cutting propagates to the portion 55 around the cut portion of the inner wall surface of the metal pipe 1, and the portion 55 may also melt.

  FIG. 3 is a cross-sectional view of the metal pipe 1 showing a cutting state when the gas 35 containing the dry ice particles 36 is injected into the hollow portion of the metal pipe 1 during laser processing according to the present embodiment.

  In FIG. 3, the laser beam 23 irradiated and condensed on the surface of the metal pipe 1 penetrates and cuts the side surface of the metal pipe 1. At this time, the gas 35 containing the dry ice particles 36 is injected from the injection nozzle 34 into the hollow portion of the metal pipe 1, and the laser beam 51 surplus for the cutting process is supplied to the dry ice particles 36 injected into the hollow portion. Therefore, the amount of laser light reaching the pipe inner wall surface 54 facing the pipe side surface position where the laser beam 23 is condensed is reduced, and thermal damage to the pipe inner wall surface is reduced.

  Further, the dry ice particles 36 injected into the hollow portion of the metal pipe 1 collide with the burr 53 generated on the inner wall surface of the cut portion by the laser beam 23, and the burr 53 is caused to impact the inner wall surface of the metal pipe 1 by the impact caused by the collision. The burr 53 that has been peeled off and peeled off is discharged outside the pipe by the gas 35 flowing in the hollow portion of the metal pipe 1. Further, the spatter 52 generated during the cutting process by the laser beam 23 is also discharged to the outside by the gas 35 flowing through the hollow portion of the metal pipe 1 and does not adhere to the inner wall surface of the pipe.

  Further, the dry ice particles 36 flowing through the hollow portion of the metal pipe 1 are sublimated under atmospheric pressure to become carbon gas, and are discharged to the outside of the metal pipe 1. This eliminates the need for a special cleaning process such as the case where grease containing a highly reflective material, which is a conventional technique, is poured into the hollow portion of the metal pipe 1 to protect the pipe inner wall surface 54 facing the laser focusing position.

  Further, the solid dry ice particles 36 absorb laser energy when they scatter the excessive laser beam 51 and sublimate to transform into carbon dioxide gas which is an inert gas. Similarly, the dry ice particles 36 that collide with the burr 53 are transformed into carbon dioxide, which is an inert gas, by the energy of the collision. Thereby, since the carbon dioxide gas which is an inert gas is filled around the condensing position of the laser beam 23 in the hollow portion of the metal pipe 1, the metal combustion around the cut portion is suppressed, and the diffusion of the molten layer is suppressed. . The diffusion of the molten layer is also suppressed when the dry ice particles 36 having a low temperature cool the periphery of the cut portion of the metal pipe 1. This makes it possible to narrow the cutting width and perform extremely precise processing.

  As described above, according to the present embodiment, the following effects can be obtained.

  (1) At the time of laser processing by the laser beam 23, the surplus laser beam 51 is scattered by the dry ice particles 36 injected into the hollow portion of the metal pipe 1, so that it is applied to the inner wall surface of the pipe facing the laser condensing position. Thermal damage can be reduced.

  (2) Since the spatter 52 scattered in the hollow portion is discharged outside the pipe by the gas 35 flowing through the hollow portion of the metal pipe 1, it is possible to suppress the spatter 52 from adhering to the inner wall surface of the metal pipe 1.

  (3) Since the dry ice particles 36 injected into the hollow portion collide with the burr 53 and blow off, the burr 53 can be reduced.

  (4) Since the dry ice particles 36 flowing through the hollow portion are sublimated under atmospheric pressure, nothing remains after laser processing, and a special cleaning step after laser processing, which has been conventionally required, can be made unnecessary. .

  (5) Since the carbon dioxide gas, which is an inert gas, is filled around the condensing position of the laser beam 23 and the metal combustion is suppressed, the diffusion of the molten layer is suppressed and precise processing can be performed.

  (6) Since the diffusion of the molten layer is suppressed by the cooling effect of the low temperature dry ice particles 36, more precise processing can be performed.

  In the present embodiment, dry ice is used as particles contained in the gas, but other particles that are not limited thereto may be used. Other particles include, for example, low-temperature ice particles and ceramic particles such as alumina. Even when ice particles are used, the effects (1) to (4) and (6) can be obtained, and ceramics such as alumina. When particles are used, the effects (1) to (4) can be obtained.

  Moreover, in this Embodiment, although nitrogen gas was used as gas injected to a hollow part, you may use not only this but other gas. Other gases include, for example, an inert gas such as argon gas, helium gas, carbon dioxide, etc., and the effects of the above (1) to (6) can be achieved by using these gases, for example, in combination with dry ice particles. Is obtained. In some cases, air may be used, and also in this case, the effects (1) to (4) and (6) can be obtained.

It is a schematic block diagram of the laser processing apparatus by one Embodiment of this invention. It is sectional drawing of the metal pipe which shows the cutting | disconnection condition in case gas is not injected to the hollow part of a metal pipe at the time of laser processing. It is sectional drawing of a metal pipe which shows the cutting | disconnection condition at the time of injecting the gas containing a dry ice particle to the hollow part of a metal pipe at the time of laser processing.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Metal pipe 2 Processing stand 3 Movable plate 4,5 Bearing 6 Motor 7 Holding part 8 Nut part 10 Base plate 11 Motor 12 Screw shaft 13 Bearing 20 Laser irradiation apparatus 21 Laser oscillator 22 Nozzle 23 Laser beam 30 Dry ice particle injection apparatus 31 Dry Ice injection control device 32 Liquefied carbon dioxide gas cylinder 33 Nitrogen gas cylinder 34 Injection nozzle 35 Gas 36 Dry ice particles 40 CNC controller 51 Laser beam surplus for cutting 52 Sputter 53 Burr 54 Inner wall surface 55 of the pipe facing the laser condensing position

Claims (4)

  In a laser processing method for a metal pipe, in which a laser beam is oscillated by a laser oscillator, a laser beam output from the laser oscillator is irradiated onto a cylindrical surface of a metal pipe to be processed, and the cylindrical surface of the metal pipe is cut through. A laser processing method comprising laser processing a cylindrical surface of the metal pipe while injecting a gas containing particles into the hollow portion of the metal pipe.   2. The laser processing method according to claim 1, wherein the particles are any one of dry ice particles, ice particles, and ceramic particles.   3. The laser processing method according to claim 1, wherein the gas is any one of nitrogen gas, argon gas, carbon dioxide, and air. A laser oscillator that oscillates laser light;
A nozzle for irradiating a cylindrical surface of a metal pipe to be processed with a laser beam output from the laser oscillator;
A work table for gripping the metal pipe and rotating and linearly moving the metal pipe;
Control means for controlling the laser oscillator and the processing table so as to cut out a predetermined pattern in the metal pipe;
A laser processing apparatus comprising: an injection device that injects a gas containing particles into a hollow portion of the metal pipe.

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