JP2530944B2 - Laser processing method and device - Google Patents

Description

Detailed Description of the Invention

[0001]

The present invention relates to relates to a laser processing method and apparatus for drawing a variety of patterns on the metal surface of a workpiece having an outer shape of the rotary member by laser irradiation, the symbol on the metal surface, When patterns, marks, characters, etc. are composed of patterns consisting of lines and dots, or when the so-called iridescent color processing is performed in which the shade of the reflective gloss of the pattern itself changes in a rainbow-like manner depending on the angle of incident light and the viewing direction. It is preferably used for

[0002]

2. Description of the Related Art As a means for drawing patterns, patterns, marks, characters, etc. on the surface of a metal or the like, a desired pattern is drawn by a thin groove or a concave point formed on an irradiation locus by irradiating a laser beam. The application method is widely used. Further, in recent years, interference fringes are generated on the laser light irradiation surface, and fine irregularities corresponding to the interference fringes of the laser light are formed on the metal surface, so that the drawing pattern itself reflects the hue of the gloss of the incident light. An iridescent color processing technique has been proposed, which changes rainbow-coloredly depending on the viewing direction (for example, Japanese Patent Laid-Open No. 2-263589).

However, when the surface of the object to be processed is a metal such as stainless steel, the surface irradiated with laser light is easily oxidized by high heat, and the drawing pattern is visually recognized by being colored with an oxide layer having a color shade different from that of the metal base material. Therefore, the above-mentioned coloring may become a problem depending on the type and application of the work piece, and it is desired to prevent this oxidation. In particular, in the iridescent color processing, there is a problem that the shade of reflective gloss is affected by the above-mentioned oxidation coloring, resulting in a decrease in decorative value in terms of sharpness and saturation. On the other hand, when a quenching mark or the like is applied to the metal surface, it is preferable that the oxidizing property is strong in terms of processing efficiency and finish, and there are processes for the purpose of the above-mentioned oxidative coloring. It is required to accelerate the oxidation.

Further, in the ordinary decoration processing, it is necessary to position the focal point of the processing converging lens on the irradiation surface of the workpiece,
Further, in the iridescent color processing, in order to generate interference fringes on the irradiation surface, it is necessary to position the irradiation surface at a fixed position deviated from the focal point of the same lens in one depth and one direction. However, a jar, a bowl,
When the surface to be processed is a three-dimensional curved surface such as a workpiece having the outer shape of a rotating body such as a flower vase, the distance from the scan head that emits the laser beam changes depending on the position of the surface to be processed. It becomes very difficult to control the optical system that adjusts the depth of focus of the laser light, and the rotating body
In order to perform the required drawing along the circumferential direction of the work piece having the outer shape of, it is necessary to change the direction of the work piece each time the drawing of the scan range is finished and re-set the position, There is a problem that the operation for this is very complicated. Furthermore, since it is difficult to confirm whether or not drawing is progressing in an appropriate state during processing, it is checked whether or not the drawing state is appropriate after completion of the entire drawing or every time drawing of the scan range is completed. In the former case, even if there is a drawing defect in the initial stage, the subsequent drawing causes a large time loss, and in the latter case, it takes a lot of time and labor, and in any case, there is a problem that the processing efficiency decreases. .

In view of the above-mentioned circumstances, the present invention can sufficiently deal with the contradictory demands of preventing oxidation and promoting oxidation on the surface irradiated with laser light, and the workpiece is the outer shape of the rotating body . Provided is a laser processing method and device capable of accurately rotating a scanning surface while keeping the scan surface at a fixed position and firmly positioning and holding a workpiece The purpose is to do.

[0006]

In order to achieve the above object, the first of the laser processing methods according to the present invention is that the upper surface is processed on a rotary table in a closed container in which at least the upper half is transparent. Fix a receiving seat with a through hole communicating with the vacuum suction hole of the rotary table at the center by forming a recess corresponding to the bottom shape of the object, and having a metal surface on this receiving seat.
The workpiece whose outer shape is a rotating body is placed so that the rotational symmetry axis of the rotating body coincides with the rotation axis of the rotary table, and the workpiece is sucked and fixed by vacuum suction from the vacuum suction hole. Then, while the inside of the hermetically sealed container is in a high-vacuum or replacement gas atmosphere, while continuously or intermittently rotating the rotary table, a laser beam whose optical axis direction is variable from the outside is passed through the transparent portion of the hermetically sealed container to form the workpiece. By irradiating the surface of the metal, the surface of the metal is drawn according to the irradiation locus.

The second method of laser processing according to the present invention
In the first processing method, an inert gas is used as the replacement gas, and in the third method, an oxygen gas or a gas having a high oxygen concentration is used as the replacement gas.

On the other hand, for the same purpose, the first of the laser processing apparatuses according to the present invention is a closed container for arranging a workpiece, which is provided with a vacuum suction port and / or a replacement gas introduction port and at least an upper half of which is transparent. And a rotary table having a vacuum suction hole provided in this closed container, and a vacuum table which is fixed on the rotary table and whose upper surface forms a recess corresponding to the shape of the bottom of the workpiece and which has a vacuum suction table at the center. A receiving seat having a through hole communicating with the hole, a laser resonator, and a scan head having a variable optical axis direction for irradiating a laser beam emitted from the resonator onto a surface of a workpiece through a transparent portion of the closed container. And.

[0009]

When the inside of the closed container is set to a high vacuum atmosphere, the surface of the workpiece placed inside the container does not contain oxygen which is a source of oxidation even when laser light is irradiated from outside the container.
No oxide layer is formed on the irradiated surface. Similarly, even if the inside of the closed container is replaced with an inert gas such as nitrogen gas, no oxide layer is formed on the irradiated surface. Therefore, if you dislike coloring the drawing pattern due to oxidative coloring in ordinary decoration processing or iridescent coloring processing,
In the present invention, the inside of the closed container may be set to a high vacuum atmosphere or an inert gas atmosphere. On the other hand, if the inside of the closed container is replaced with oxygen gas or a gas with a high oxygen concentration, oxidation will be more likely to occur on the laser light irradiation surface of the workpiece than in the case of laser processing in normal air. Therefore, in the case of providing a quenching mark or the like on the metal surface, or in a decoration process or the like that positively utilizes coloring by drawing pattern oxidation, the sealed container may be set to an oxygen gas or a gas atmosphere of high oxygen concentration.

[0010] Thus, although the workpiece of interest are those having an outer shape of the rotating body such as vase or vases, the rotary body
By aligning the axis of rotational symmetry with the axis of rotation of the rotary table, with the scan head side that irradiates the laser beam set to a fixed position, the rotary table rotates to continuously or intermittently scan the workpiece surface. It is possible to perform processing in each of the above-mentioned atmospheres while updating. Therefore, in ordinary decoration processing, it is necessary to position the focus of the processing converging lens on the irradiation surface of the work piece, and in iridescent color processing, in order to generate interference fringes on the irradiation surface, It is necessary to position the irradiation surface at a fixed position that is offset in one direction in the depth and shallow directions.
Since the position of the scan surface can be kept constant even in the processing on the three-dimensional curved surface constituting the peripheral surface of, the control of the optical system for adjusting the depth of focus of the laser beam in writing becomes very easy.

Moreover, since the workpiece on the rotary table can be firmly attracted and fixed by vacuum suction, and there is no risk of misalignment during rotation, if the positioning is performed first, the distance from the scan head to the scan surface is increased. In addition to performing stable machining, the workpiece is placed on the rotary table via the receiving seat corresponding to the bottom shape of the workpiece, which facilitates initial positioning and holds the workpiece during machining. The state is stable, and a strong suction force can be applied regardless of the shape of the workpiece. Furthermore, since at least the upper half of the closed container is transparent, it is possible to visually judge the drawing state from the outside during processing and to judge whether it is appropriate or not. When the workpiece is tiltable and its outer diameter changes depending on the vertical position, such as a pot, it is possible to set the irradiation angle of the laser beam centered on the scan to a desirable range with the workpiece tilted. Becomes

[0012]

FIG. 1 shows a laser beam machine according to an embodiment of the present invention. In the figure, 1 is a processing machine main body having a drawing operation panel 1a on the right front surface and a laser operation panel 1b on the left front surface, 2 is a scan head arranged in a protruding shape on the center front side of the upper portion of the main body 1, and 3 is Placed on the rear side and metal surface inside
A closed container accommodating a workpiece 4 having an outer shape of a rotating body , 5 is an image display device for observing a machining surface installed in the upper left part of the main body 1, 5a is an image pickup camera thereof, 5b is a machining surface Is a floodlight that illuminates.

FIG. 2 shows the configuration of an optical system in the laser processing machine. Reference numeral 6 in the figure is a laser resonator such as a YAG laser, and the laser beam 7 emitted from this is
The beam is expanded by a beam expander 9 with a built-in magnifying lens, and the light is passed through a movable lens 10a of a Z scanner (Dynamic Focus) 10 and a condensing lens (Imaging Object).
Ctive) 11 converges at X scanner 12 and Y
The beam direction is controlled by the rotary reflecting mirrors 12a and 13a of the scanner 13 to irradiate the surface of the workpiece 4.

Here, the Z scanner 10 converts the focal point position of the condenser lens 11 into the beam angle and the curved surface shape data of the workpiece 4 measured in advance within a predetermined scanning range of the X and Y scanners 12 and 13. Accordingly, set the fixed position on the machined surface. That is, the fixed position of this focal point is a position displaced to the upper or lower side with respect to the surface of the workpiece 4 in the ordinary decoration processing and to the surface in the iridescent coloring processing.

The processing state at the irradiation position of the laser beam 7 is the workpiece 4 illuminated by the projector 5b.
The processed surface is captured by the imaging camera 5a and displayed on the image display device 5 for observation. An auxiliary laser 14 such as a He—Ne laser is installed coaxially behind the laser resonator 6 to visualize the laser beam 7 and observe the focus position.

FIG. 3 shows a laser processing part of the laser processing machine. Reference numeral 15 in the figure is a trolley-shaped machine frame equipped with casters 15a equipped with the whole of the processing part, and a laser resonator 6 is horizontally installed below the laser cavity 6 through mounting bolts 6a. The vertical slide base 17 is fixedly mounted on the vertical support plate 16 attached to the machine frame 15, and
A Z table 18 which is moved up and down by driving a motor 18a is fitted on the slide base 17. And
The scan head 2 incorporating the X scanner 12 and the Y scanner 13 is attached to the upper portion of the rectangular cylindrical head support rod 19 fixed to the Z table 18 in an upright state. A head cover 2a covers the scan head 2.

The optical path of the laser beam from the laser resonator 6 to the scan head 2 is set inside the horizontal optical conduit 20 and the vertical optical conduit 21, and the reflecting mirror 8 and the beam are provided between the optical conduits 20 and 21. The expander 9 is provided, and the condenser lens 11 and the Z scanner 10 are provided between the upper end of the vertical light pipe 20 and the scan head 2. The vertical light pipe 21 is connected to the beam expander 9 side to the large-diameter upper tube 21a connected to the scan head 2 side so as to cope with the change in the distance of the laser beam optical path as the Z table 18 moves up and down. It has a telescopic structure in which a lower tube 21b having a diameter is fitted.

On the other hand, a horizontal slide base 22 is mounted above the laser resonator 6 on the machine frame 15, and a motor 23a is driven on the base 22 to drive the horizontal slide base 22 in a direction perpendicular to the plane of FIG. In other words
A table 23 is fitted, and a Y table 24 that moves in the front-rear direction by driving a motor 24a is fitted on the X table 23. The receiving frame 25 provided on the Y table 24 is fitted with the hermetically sealed container. 3 is pivotally supported via a pivot 3a. Then, the closed container 3 has the receiving frame 2
Driven by a motor 25a attached to the shaft 5,
It is configured so as to be tiltable in the front-rear direction about a.

As shown in FIG. 4, the hermetically sealed container 3 includes a metal container body 26 having a circular opening 26a directed obliquely upward and approximately 45 ° forward, and a fastener 27 at the opening 26a.
(See FIG. 3) and a substantially hemispherical glass cover 28 that is hermetically fitted. Therefore, the container body 26 is provided with the replacement gas introduction port 29a and the vacuum suction port 29b at the rear portion of the side wall, and the rotary table 30 having a substantially T-shaped cross section is vertically provided through the bearings 31, 31 at the front portion of the bottom wall. It is rotatably supported around the axis of direction. The rotary table 30 is located at a height near the boundary between the container body 26 and the glass cover 28, and
By driving a motor 32 attached to the lower surface side of 6, the bevel gear 33a fixed to the lower end portion of the shaft portion 30a protruding downward from the container body 26 and the bevel gear 33b provided at the shaft center of the motor 32 are engaged. Drive to rotate.

A vacuum suction hole 34 is formed in the rotary table 30 so as to vertically penetrate along the axis of the rotary table 30. The workpiece 4 placed on the rotary table 30 via a receiving seat 35 is placed on the rotary table 30. The rotary table 30 is suctioned and fixed by vacuum suction. The receiving seat 35 is
A through hole having a through hole 35a communicating with the vacuum suction hole 34 of the rotary table 30 and having an upper surface shape corresponding to the bottom shape of the workpiece 4 is used.
It is detachably attached to the rotary table 30 by screwing. Here, the workpiece 4 is a metal surface as described above.
It has a surface and the outer shape is a rotating body.
The axis of rotational symmetry of the body coincides with the axis of rotation of the rotary table 30.
Thus, it is placed on the receiving seat 35. In FIG. 3, the workpiece 4 is a metal vase, and as the receiving seat 35, one having a concave portion 35b on the upper surface for tightly fitting the bottom of the vase is used. Seal rings 36a and 36b are provided at the interface between the rotary table 30 and the receiving seat 35 and at the interface between the receiving seat 35 and the workpiece 4, respectively. 36c is a gasket that hermetically seals the contact surface between the container body 26 and the cover 28.

FIG. 5 shows an example of a gas circuit in the laser beam machine having the above structure. In the figure, L1 is a pipe connected to the replacement gas introduction port 29a of the closed container 3, L2 is a pipe connected to the vacuum suction port 29b, L3 is a pipe connected to the rotary table 30, and SOL1 to 6 are solenoid valves. VP is a vacuum pump, F is a filter, PS is a pressure switch, VS is a vacuum pressure switch, PG is a pressure gauge, VG is a vacuum pressure gauge, A is an atmosphere opening port, and a solenoid valve SOL1 is connected to a nitrogen gas cylinder N ₂ . The solenoid valve SOL2 is connected to the oxygen gas cylinder O ₂ .

At the time of machining, in order to adsorb and fix the workpiece 4 on the rotary table 30, SOL5 and SOL6 may be turned ON and the vacuum pump VP may be operated. However, when the coloring of the drawing pattern due to the oxidation coloring is disliked in the usual decoration processing or iridescent coloring processing, SOL3 and SOL4 are turned on,
Whether SOL1 and SOL2 are turned off to create a high vacuum atmosphere in the closed container 3 by suction with the vacuum pump VP,
With SOL1 turned on and SOL2 and SOL4 turned off, the inside of the hermetically sealed container 3 may be replaced with a nitrogen gas introduced from a nitrogen gas cylinder N ₂ to create an inert gas atmosphere.
On the other hand, when applying a quenching mark or performing decoration processing that actively uses coloring due to oxidation of the drawing pattern,
It is only necessary to turn on SOL2 and turn off SOL1 and SOL4, and replace the inside of the closed container 3 with the oxygen gas introduced from the oxygen gas cylinder O ₂ to create an oxygen gas atmosphere.

For processing, the inside of the closed container 3 is set to a desired atmosphere, and the X, Y, and Z tables 23, 24, 1 are set.
After the irradiation position and the focus position of the laser beam 7 with respect to the surface of the workpiece 4 at the scanning center are determined by the movement adjustment of 8, the rotary table 30 is continuously or intermittently driven and the laser beam 7 is emitted from the scan head 2. Through the glass cover 28 of the closed container 3 to irradiate the surface of the workpiece 4. At this time, the laser beam 7 controls the displacement in the optical axis direction in cooperation with the rotation of the rotary table 30 in accordance with a drawing pattern such as a desired pattern, pattern, mark, or character. The movement of the scan range in the vertical direction on the surface of the work piece 4 tilts the closed container 3 back and forth or raises and lowers the Z table 18 according to the outer shape of the work piece 4. 4 surface and scan head 2
When the distance between and changes, the Y table 24 is moved back and forth. The movement of each of these movable parts during drawing is automatically controlled by measuring the outer surface shape of the workpiece 4 in advance and inputting this measurement data to the control system.

The illustrated laser beam machine is provided with the raising / lowering means of the scan head 2, the front / rear and left / right moving means of the closed container 3, and the forward / backward tilting means. In the present invention, various concrete mechanisms of these means are provided. These means are not essential while the design can be changed.

[0025]

According to the laser processing method and laser processing apparatus of the present invention, it is possible to place a workpiece having the outer shape of a rotating body in a closed container and perform drawing by irradiating a laser beam from the outside. Therefore, by setting the atmosphere in the closed container, it is possible to deal with both cases where the coloring of the drawing pattern due to oxidation coloring is disliked and the case where the coloring due to oxidation is positively used, and the laser beam irradiation is performed by rotating the rotary table. Since the scan plane can be updated while keeping the position constant, it is very easy to control the optical system that adjusts the depth of focus of the laser beam during drawing, and the workpiece is firmly fixed and misaligned during rotation. Since there is no risk of causing problems, stable positioning can be performed without changing the distance from the scan head to the scan surface if you position it first. Since the receiving seat corresponding to the bottom shape of the work piece is used, the initial positioning is easy and the holding state during processing is stable, and a strong suction force acts regardless of the shape of the work piece. Further, it is possible to visually judge the drawing state during processing from the outside and easily determine the suitability, and it is possible to improve the processing efficiency by eliminating the time loss accompanying the processing continuation after the drawing failure occurs.

[Brief description of drawings]

FIG. 1 is a perspective view of an entire laser processing machine according to an embodiment of the present invention.

FIG. 2 is a schematic perspective view showing a configuration of an optical system in the laser processing machine.

FIG. 3 is a side view of a laser processing section of the laser processing machine.

FIG. 4 is a vertical sectional side view of a hermetically sealed container portion of the laser processing section.

FIG. 5 is a gas circuit diagram corresponding to the closed container.

[Explanation of symbols]

 1 ... Laser processing machine main body 2 ... Scan head 3 ... Airtight container 4 ... Workpiece 6 ... Laser resonator 7 ... Laser beam 28 ... Glass cover (transparent part) 29a ... Substitution gas inlet 29b ... Vacuum suction port 30 ... Rotary table 34 ... Vacuum suction hole 35 ... Receiving seat 35a ... Through hole 35b ... Recess

Front page continuation (72) Inventor Yoshikazu Okano 1-9-1, Jōkoji, Amagasaki City, Hyogo Prefecture Osaka Osaka Fuji Kogyo Co., Ltd. (56) Reference JP-A-61-273294 (JP, A) JP-A-2- 258183 (JP, A)

Claims (4)

(57) [Claims] 1. A transparent table which has a recess corresponding to the shape of the bottom of an object to be processed and which communicates with a vacuum suction hole of the rotary table at the center of the rotary table in a closed container in which at least an upper half part is transparent. Fix a pedestal with a hole and a work piece with a metal surface on the pedestal whose outer shape is a rotating body.
The rotary body is placed so that the rotational symmetry axis of the rotary body coincides with the rotary axis of the rotary table, and the workpiece is sucked and fixed by vacuum suction from the vacuum suction hole. Alternatively, as a replacement gas atmosphere, while continuously or intermittently rotating the rotary table, by irradiating the metal surface of the workpiece with a laser beam whose optical axis direction is variable from the outside through the transparent portion of the closed container, A laser processing method, characterized in that a drawing is performed on an irradiation track. 2. The laser processing method according to claim 1, wherein the replacement gas is an inert gas. 3. The laser processing method according to claim 1, wherein the replacement gas is oxygen gas or a gas having a high oxygen concentration. 4. A closed container for arranging a workpiece, which is provided with a vacuum suction port and / or a replacement gas introduction port and at least an upper half of which is transparent , and a vacuum provided in the closed container.
A rotary table having a suction hole, and a rotary table fixed on the rotary table.
The top surface of the
And a through hole in the center that communicates with the vacuum suction hole of the rotary table.
And a laser resonator, and a scan head having a variable optical axis direction for irradiating the surface of the workpiece with a laser beam emitted from the resonator through the transparent portion of the closed container. Laser processing equipment.