JP3200588B2 - Laser distortion processing method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for processing a plate-shaped workpiece to deform (warp) the workpiece.

[0002]

2. Description of the Related Art It is not possible to distort (warp) a plate-like slider called an "Altic" by scratching one main surface of the plate-like slider with diamond, so that the main surface (surface) of the slider becomes convex. Are known.

[0003]

However, in the processing using diamond, it is not easy to make the same scratch on a large number of plate-like members, and it takes a long time to perform the processing, and the productivity is not high.

The present invention has been made in view of the above points, and an object of the present invention is to provide a strain processing method and apparatus which can apply a predetermined strain (warp) to a plate-shaped workpiece in a short time. Is to do.

[0005]

In order to achieve the above object, a laser processing method according to the present invention irradiates a laser beam to one principal surface of a plate- like workpiece to be processed for a slider so that a side of the principal surface is irradiated. The method comprises distorting a plate-shaped workpiece so as to be concave, and more specifically, corresponds to an area and shape of a predetermined shape of an irradiation area of one main surface of the plate-shaped workpiece. distort the plate workpiece to be concave by irradiating a laser beam with respect to s bidirectional husband side of the main surface is perpendicular to a wide irradiation area which consists Rukoto form a slider.
In the following description of the specification, portions that do not satisfy the conditions described in this paragraph are literally outside the scope of the invention described in the claims.

That is, the laser distortion processing method of the present invention comprises:
By irradiating one main surface of the plate-shaped workpiece with laser light, the irradiated portion is locally heated, and tensile (shrinkage) stress accompanying rapid cooling after the local heating is left in the irradiated portion. The workpiece is deformed so that the main surface on the side including the shape becomes concave. As described above, in the present invention, a workpiece is caused to change in geometrical shape (distortion) by laser light, and such processing is referred to as “laser distortion processing” in this specification.

[0007] In this specification, the term "plate-like" refers to a workpiece having a shape such that the shape of the workpiece can be changed in accordance with shrinkage of a portion (irradiated portion) irradiated with the laser beam. This means that, for example, not only the thickness does not need to be constant, but also the width and length need not be constant. That is, the term “plate-shaped” is intended to exclude, for example, spheres that hardly change in shape even when the part to be irradiated with laser light contracts, and the part to be irradiated with the laser light is excluded. May be a shape close to a “sphere” as long as the shape of the workpiece can be significantly changed due to contraction.

[0008] Therefore, when the member to be processed is a typical "plate", "one main surface" refers to one of two opposing wide surfaces (that is, main surfaces) of the "plate". In the case where the member to be processed has a three-dimensional shape deviated from a typical “plate”, it refers to a relatively large surface including a region irradiated with laser light (a surface region that defines a portion to be irradiated). This broad side
Typically, although it is actually preferable to be "planar", a convex portion or a concave portion such as a saddle portion is formed as a set even if it is originally convex or concave at the stage before laser light irradiation. It may include a mating portion.

The region irradiated with the laser beam is preferably a part of one main surface, but may be the whole of the one main surface in some cases. In that case, even if the laser irradiation conditions (for example, irradiation energy density) are changed between the central part and the peripheral part of the main surface, the thickness of the workpiece is made different depending on the place (part), and the same tension is applied. The ease of deformation with respect to stress may be different depending on the location (site). Of course, if desired, a portion other than the “one main surface” of the member to be processed may be subjected to distortion processing by laser light irradiation or the like.

When a part of one main surface is irradiated with laser light to perform distortion processing, it is preferable to irradiate the laser light to the central part of one main surface. May be irradiated with laser light in an arbitrary shape such as a linear shape, a band shape, or a circular shape, or may be irradiated with a laser light having an arbitrary shape such as a circular shape. When the central portion of the main surface is irradiated with the laser light, any desired planar shape can be selected as the region to be irradiated. For example, even when the member to be processed is a rectangular flat plate, a circle or (rather than a rectangular shape) at the center of one main surface is used.
By irradiating a laser beam to the square area, a distortion can be imparted to the workpiece so that the central portion of the other main surface of the flat plate becomes convex. Note that, instead of making the central portion of the other main surface of the plate-shaped workpiece to be convex in each of the two orthogonal directions on the main surface, the central portion of the other main surface is formed by the central portion of the other main surface. The workpiece may be deformed so as to be convexly curved along a single line on the main surface. In addition, if desired, at least a part of the laser beam irradiated portion of the one main surface of the plate-shaped workpiece is irradiated with the laser light to scatter the forming material of the processed member so that the scattered mark portion is concave. Location. Further, a projection may be formed on at least a part of the irradiated portion or a peripheral region thereof.

As long as the material to be processed is locally heated by the laser beam and then rapidly cooled, any material of the material to be processed may be used as long as a contractive (tensile) stress remains in the heated portion. It may be a material (including alloys), a ceramic material (single or composite composition (mixture)), or an organic or inorganic polymer material such as plastic. In the case of a mixture, the composition may be uniform or non-uniform, and the composition may vary depending on the location. The irradiated portion may be at least partially melted or not melted at all during heating. Furthermore, it does not matter whether or not sintering proceeds by heating. Further, a material having a plurality of phases having a crystal structure in a solid state or a material having a single crystal phase may be used. Further, the material may or may not easily increase the amorphous property by quenching, and may or may not easily reduce the crystal grains by quenching. These properties can vary significantly depending on the individual materials and the laser irradiation conditions that affect the heating rate and temperature, so depending on each material, when quenched after local heating with laser light, Laser light irradiation may be performed by selecting a condition under which contractive (tensile) stress remains in the heated portion.

The type of laser light to be irradiated, for example, wavelength, average energy, energy density, peak output, pulse width, pulse repetition frequency, etc., depends on the material and size of the workpiece to be processed. What is necessary is just to select what has a contractive (tensile) stress easily remaining in the heated portion when it is rapidly cooled after heating. However, as a laser beam, the peak output is high and the irradiation energy density is easy to control.
Pulses are preferred over continuous light. In the case of a pulse laser, the control of the irradiation energy (density) and the like may be performed by controlling the number of irradiation pulses. For example, a single shot or a plurality of shots of laser pulses may be applied to the entire irradiation region or a plurality of locations in the irradiation region. Irradiation may be performed. The preferred pulse width of the laser pulse can vary greatly depending on the workpiece, but is rapidly heated locally (material dependent) to the desired temperature and then quenched (in the non-pulsed period defined by the pulse interval). Is preferably about 0.03 to 20 ms so that

Since heating by the laser beam can be performed locally and rapidly, not only the temperature change due to heating is large, but also the irradiated part heated by local heating, by stopping the heating by the heating means, That is, by stopping the laser beam irradiation or between the irradiation of the laser pulse of one shot and the irradiation of the laser pulse of the next shot, it is rapidly cooled and frozen in that state, so that the tensile stress remains. Internal distortion will occur. As a result, distortion (warpage) occurs such that the main surface to which the irradiated portion belongs is concave.

The amount of distortion (magnitude of distortion) generated in the workpiece may be controlled by controlling laser irradiation conditions such as the energy density of the laser beam applied to the irradiation area.

A laser processing apparatus according to the present invention is a laser processing apparatus for performing the above-described laser processing method, and is preferably an optical fiber for guiding a laser beam from a laser oscillator and an optical fiber emitted from the optical fiber. A laser distortion processing apparatus having a focus lens that focuses the laser light on the main surface of the workpiece, or a mask having an opening through which laser light from a laser oscillator passes, and an image of the opening of the mask. And an imaging optical system for forming an image on the main surface of the processing member.

In the former case, there is a high degree of freedom in the arrangement position of the workpiece with respect to the laser oscillator. In this case, preferably, a collimating lens for collimating the laser light emitted from the optical fiber and making the collimated laser light incident on the focus lens is provided. In order to change the diameter (spot diameter) of the laser beam applied to the workpiece, the diameter of the optical fiber (at the emission section) is changed, or at least one of the collimator lens and the focus lens is different in focal length. What is necessary is just to replace it.

In the latter case, since an image of the opening can be reduced or made at the same magnification in a region having a shape defined by the opening of the mask, processing can be easily performed on an irradiation region having a predetermined shape. In this case, the imaging optical system preferably includes a collimating lens that collimates the laser light from the opening of the mask so that the shape of the relatively large mask opening can be reduced at a high energy density to form an image. A focus lens that focuses the laser beam collimated by the collimating lens in front of the main surface of the workpiece and in the vicinity of the main surface. Further, it is preferable that the opening of the mask is adjustable. Thus, the shape and size of the region to be irradiated with the laser beam can be easily controlled, and the control of the distortion (warpage) to be caused in the member to be processed becomes easier.

[0018]

Next, a preferred embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 1 schematically shows laser distortion processing of a workpiece 2 by a laser distortion processing apparatus 1 according to a preferred embodiment of the present invention.

A laser distortion processing apparatus 1 shown in FIG. 1 comprises a laser oscillator 3 in the near-infrared, visible or ultraviolet region, an optical fiber 4 for guiding a laser beam from the laser oscillator 3 to a position near a workpiece 2, A collimating lens 6 for collimating the laser beam B1 diverging from the emission end 5 of the fiber 4 into a parallel beam B2, and the collimated laser beam B2 is focused on a processing surface 7 which is one main surface of the processing member 2. Focusing lens 8.

Here, the diameter of the laser beam B1 at the emission end 5 of the optical fiber 4 is φ0,
Assuming that the focal length of the focus lens 8 is f1 and f2, respectively, the irradiation spot diameter φ of the laser beam B3 on the processing surface 7 is given by the following equation F1.

Φ = (f2 / f1) · φ0 (F1)

Therefore, in order to change the size of the irradiation area by changing the size of the irradiation spot diameter φ, or to change the irradiation energy density, etc., one of the optical fiber 4 and the lenses 6 and 8 must be used. Any of φ0, f1, and f2 may be changed.

If the irradiation area or the processing area on the processing surface 7 is larger than the irradiation spot diameter φ, and it is necessary to scan the beam B3 over the entire irradiation area, the processing target 2 When the workpiece 2 is translated with respect to the beam B3 by driving the XY table 9 on which the X-Y table 9 is mounted in translation, the emission optical system 10 (the support of the emission end 5 of the optical fiber 4 (see FIG. Not shown) and the collimating lens 6
And the support (not shown), the focus lens 8 and the support (not shown))
May be translated. The emission optical system 10 may be changed as desired as long as the laser beam having a desired intensity can be irradiated on the irradiation area 11 of the processing surface 7 by the beam B3.

The laser distortion processing apparatus 1 irradiates a laser beam B3 from the laser oscillator 3 with a high energy density to a predetermined irradiation area 11 of the processing surface 7 of the processing member 2 in a short time. The irradiated region 11 can be processed so that contraction stress remains in the region 11.

FIG. 2 shows another preferred embodiment of the laser distortion processing apparatus 12 according to the present invention,
1 schematically shows laser distortion processing.

The laser distortion processing apparatus 1 of FIG. 2 has a laser oscillator 3 in the same or far-infrared region as in FIG. 1, and an aperture (aperture) A (FIG. 3) having a shape corresponding to the irradiation area 11. A mask 13 illuminated by a laser beam B0 from a laser oscillator 3, and a laser beam B4 extending from an opening A of the mask 13.
A collimating lens 6 for collimating the laser beam B5 into a substantially parallel beam B5, and a focus lens 8 for converging the collimated laser beam B5 on the surface 7 to be processed of the member 2 to be processed. To be illuminated 1 on the surface 7 to be processed in which
1 to form an image. The laser distortion processing device 1
In No. 2, a folding mirror 14 is provided between the collimating lens 6 and the focus lens 8. Therefore, X-
The Y table 9 is driven in translation or the mirror 1
By moving the emission optical system 15 composed of the focusing lens 8 and the focusing lens 8 in a direction parallel to the beam B5, the irradiation position in that direction can be changed.

As shown in FIG. 3, for example, the mask 13 includes a mask body 18 having a reinforcing mounting frame 16 at the periphery and a hole (opening) 17 at the center, and a mask body 18.
Horizontal size adjustment plate 1 movable in the horizontal direction Y with respect to
9, 20; vertical size adjusting plates 21 and 22 movable in the vertical direction Z with respect to the mask body 18;
Fixture 23 for fixing 9, 20, 21, 22 at the adjustment position
And Therefore, the opening (aperture) of the mask 13
A is an inner edge 19a of the adjusting plates 19, 20, 21, 22;
20a, 21a and 22a. The mask 13 can irradiate the laser beam B6 with a large irradiation area on a square work surface and change the size of the opening A in the vertical and horizontal directions so that the irradiation can be performed by using only one mask 13. The area and shape of the region 11 can be changed.

In this example, the inner edge of each adjustment plate is straight, and the opening A is rectangular (or square), but the inner edge is curved instead of straight, and the opening is oblong. May be changed to a circle. Further, the movable direction of the adjustment plate with respect to the mask body may be curved instead of straight. Further, instead of defining the opening by the inner edge of the adjusting plate, the opening may be defined so as to be adjustable by any other means such as electro-optical means.
In addition, instead of making the entire opening have a uniform transmittance, the laser light transmittance of a portion of the opening may be higher than the transmittance of another portion. Further, instead of a series of openings, the openings may be formed in a pattern of a plurality of discontinuous openings.

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A laser plate (altitude: 1.25 mm, width: 1.0 mm, thickness: 0.6 m) called Altic (Al ₂ O ₃ + TiC) using a laser distortion processing apparatus 12 shown in FIG.
m), the central part of one main surface 7 is 0.8 mm long and 0.8 mm wide.
One shot of a YAG laser pulse having a pulse width of 0.5 ms was applied to the workpiece 11 having a width of 0.5 mm. As the irradiation conditions, the irradiation energy density (J / mm ² ) of the laser beam B6 to the region to be processed 11 was 0.17 (Example 1), which was about twice that of Example 1 and 0.36 (Example 2). When the value was changed to about 0.72 (Example 3), the distortion was exaggerated in FIG. 4 and indicated by an imaginary line in the workpiece 2 subjected to the distortion processing. When the magnitude of strain is expressed by the amount of displacement (nm) at the end as shown by D in FIG. 4, the amount of distortion D (nm) is 2.
03 (Example 1), 6.68 (Example 2), and 11.63 (Example 3). Based on the above experimental results, the distortion amount (n) with respect to the irradiation energy density (J / mm ² )
As shown in FIG. 5, it can be seen that the relationship changes almost linearly (more strictly, slightly sub-linear) as shown in FIG. Therefore, in the case of the ceramic plate as in this embodiment, it is considered that the amount of distortion up to about 10 nm can be controlled by changing the laser irradiation conditions.

As described above, even if the workpiece 2 is made of a relatively hard ceramic, by subjecting one main surface to laser distortion processing by laser irradiation, the workpiece 2 is distorted in a very short time. (Warping) can be imparted, and the amount of distortion can be changed by changing laser irradiation conditions such as irradiation energy density (laser irradiation conditions such as irradiation energy density depending on the amount of distortion desired to be set and controlled). Can be controlled).

It will be apparent to those skilled in the art that other laser irradiation conditions may be changed to control the amount of distortion. However, only in the case of this embodiment, it was confirmed that when the pulse repetition frequency was relatively low, there was practically no effect of the repetition frequency. This indicates that the experiment of the example was performed under such a condition that the irradiated portion was rapidly heated by each laser pulse, and was rapidly cooled after the completion of the pulse irradiation.

The laser distortion processing of the present invention is applicable not only to manufacturing of a member such as a slider that uses a small warpage to reduce friction with other members, but also to any member requiring a fine shape or minute size adjustment. It can also be used for manufacturing.

In some cases, this distortion processing may be used as a type of surface treatment that hardly causes deformation of the member to be processed when viewed macroscopically.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view of strain processing by a laser strain processing apparatus according to a preferred embodiment of the present invention.

FIG. 2 is a schematic explanatory view of distortion processing by a laser distortion processing apparatus according to another preferred embodiment of the present invention.

3 is a schematic plan view of both sides of the mask of the apparatus of FIG. 2,
(A) is viewed from one surface, and (b) is viewed from the other surface.

FIG. 4 is an explanatory side view showing distortion (warpage deformation) of a workpiece in the case of an embodiment.

FIG. 5 is a graph showing the results of Examples.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 12 Laser distortion processing apparatus 2 Workpiece 3 Laser oscillator 4 Optical fiber 5 Exit end 6 Collimator lens 7 Workpiece surface (one main surface) 8 Focus lens 9 XY table 10 Injection optical system 11 Workpiece area ( (Irradiation area) 12 Projection optical system 13 Mask 19, 20, 21, 22 Adjusting plate (of opening A) A Opening B0, B1, B2, B3, B4, B5, B6 Laser beam D Distortion amount Y, Z Moving direction φ Irradiation beam spot diameter φ0 Beam diameter

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-63-220991 (JP, A) JP-A-62-93028 (JP, A) JP-A-5-245543 (JP, A) JP-A-4- 33792 (JP, A) JP-A-63-303237 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B23K 26/00 B23K 26/06 B23K 26/08

Claims (7)

(57) [Claims] An irradiation area of a predetermined shape on one main surface of a plate-shaped workpiece for a slider is irradiated with a laser beam having a wide irradiation area corresponding to the area and shape of the area. laser distortion processing method consisting Rukoto form a slider distort the plate workpiece to be concave with respect to s bidirectional husband side are orthogonal. 2. The laser distortion processing method according to claim 1, wherein an irradiation area of the workpiece to be irradiated with the laser beam is a central portion of the main surface. 3. The laser distortion machining method according to claim 1, wherein the energy density of the laser radiated to the irradiation area is controlled to control the magnitude of the distortion generated in the workpiece. 4. The laser strain processing method according to claim 1, wherein the member to be processed is a ceramic material. 5. A laser processing apparatus for carrying out the laser processing method according to any one of claims 1 to 4, a mask having an opening for passing the laser beam from the laser oscillator An optical system for forming an image of the opening of the mask on the main surface of the member to be processed. 6. An imaging optical system, comprising: a collimating lens for collimating a laser beam from an opening in a mask; and a laser beam collimated by the collimating lens, in front of the main surface of the member to be processed and in the vicinity of the main surface. The laser distortion processing apparatus according to claim 5 , further comprising a focusing lens for focusing. 7. openings of the mask is adjustable according to claim 5
Or the laser distortion processing apparatus according to 6 .