Laser beam generating unit

A laser beam generating unit has a semiconductor laser unit having a plurality of beam emitting portions located in the shape of a matrix, and a plurality of optical fibers for individually transmitting laser beam emitted from the beam emitting portions. An optical fiber bundle is formed by binding a plurality of the optical fibers on a side where laser beam emits, and laser beam is emitted through a taper adaptor provided on the side where laser beam emits. Then, laser beam can be transmitted by the optical fibers at a good condition, and can be collected by a beam transmitting path of the adaptor having the thinner diameter with high efficiency and the power density can be raised.

BACKGROUND OF THE INVENTION

This invention relates to a laser beam generating unit for collecting laser beam emitted from a plurality of beam emitting portions (emitters) of a semiconductor laser in order to utilize for desired usage.

Generally, a semiconductor laser (laser diode: LD) is known as a source of laser beam having high conversion efficiency from electricity into light, and the efficiency of laser beam exceeding 50 percent, and then, a big scale of cooling unit is not necessary. Therefore, the semiconductor laser is utilized in the field of information processing industry since it can be made compact. But, this semiconductor laser has not been used in the field of machining with laser beam since the size of laser beam of this semiconductor laser is 1 mm or lower at the most and only several watt (W) of beam output is expected although the semiconductor laser has high efficiency of laser beam.

In recent years, a semiconductor laser beam collecting machine to be used for machining with laser beam by using a plurality of semiconductor lasers which are one-dimensionally or two-dimensionally arranged has been planned (see FIGS. 1 through 3 of the Japanese patent application (Publication No.H07-168040). This semiconductor laser collecting machine can obtain high output of laser beam having high light density since a plurality of semiconductor lasers are used although output of laser beam from one semiconductor laser is small.

This semiconductor laser beam collecting machine disclosed in this patent application collects laser beam emitted from the respective beam emitting portions which are sources of laser beam of a semiconductor laser substrate through a beam guiding path formed at the substrate so as to raise the output in order to utilize machining with laser beam. The beam guiding path has input ports having the same number as the sources of laser beam at one end, and all of the laser beam received at each input port is transmitted for only one output port which is formed at the other end.

According to the above-mentioned semiconductor laser beam collecting machine, a relatively big basic plate having a beam guiding path is necessary to be separately prepared in order to collect laser beam emitted from a plurality of beam emitting portions. Dew to the presence of such a basic plate, the machine is not made compact.

Then, an attention is paid to such a structure that laser beam is collected from each of beam emitting ends of the optical fiber bundle which is made by binding a plurality of optical fibers without using the above-mentioned substrate. In such a case, the diameter of the bound portion of the optical fiber bundle is big. In order to collect lower output of laser beam from many beam emitting portions and obtain high output of laser beam, the number of the optical fibers increases, and invites power density down. For this reason, it is desired to make the diameter of the optical fiber bundle smaller on the beam emitting side if the optical fibers are used as the laser beam collecting means.

Then, laser beam generating units for collecting laser beam emitted from each of beam emitting portions with high efficiency by a combination of laser beam collecting means and a taper beam transmitting path are still desired.

SUMMARY OF THE INVENTION

One aspect of the invention is laser beam generating unit having a semiconductor laser unit equipped with a plurality of beam emitting portions arranged in the shape of a matrix, each beam emitting portion being capable of emitting laser beam, and a laser beam collecting means for collecting laser beam emitted from a plurality of said beam emitting portions, comprising:an emission entrance through which said laser beam collected by said laser beam collecting means enters therein, an emission exit corresponding to said emission entrance, and a taper portion having a taper beam transmitting path formed so as to gradually have a thinner diameter from said emission entrance for said emission exit.

The expression “in the shape of a matrix” in the invention does not always means so-called arrangement in the shape of a matrix where pitches of a line direction and a column direction are corresponded with each other, but includes arrangements having a broad meaning, such as an arrangement in the shape of a honeycomb where a plurality of portions arranged at a predetermined pitch in a line direction (or in a column direction) are shifted from the portions in the column direction (or in the line direction), an arrangement in the shape of a zigzag, and the other arrangements.

Another aspect of the invention is the laser beam generating unit, wherein a shape of a cross section of said laser beam collected by said laser beam collecting means is equal to a shape of said emission entrance opening or smaller.

According to this aspect of the invention, the beam transmitting path which is a path of laser beam has a taper shape so as to gradually have a thinner diameter from the emission entrance for the emission exit, thereby raising the power density of laser beam. Besides, there are the following effects. That is, the beam emitting portions are arranged in the shape of a matrix, a honeycomb, or a zigzag, so that the laser beam is emitted from a plurality of beam emitting portions as it is in the shape of a matrix. That is, the shape of the cross section of a group of laser beam which is emitted from a plurality of beam emitting portions (the shape of the cross section of the area where the laser beam emitted from a plurality of beam emitting portions disperses) is almost rectangular, and the shape of the cross section of the beam transmitting path is generally smaller than the shape of the cross section of a group of the laser beam, which is generally a circle. If the laser beam emitted from the beam emitting portions is entered into the beam transmitting path without collecting the laser beam, a part of the laser beam may not enter the beam transmitting path and may be lost. According to the invention, but, the laser beam emitted from a plurality of the beam emitting portions is collected by the laser beam collecting means which is located between the beam emitting portions and the beam transmitting path, and thereafter, is entered into the emission entrance, so that beam loss can be decreased (can be prevented, preferably) and the laser beam can be effectively utilized.

Another aspect of the invention is the laser beam generating unit, wherein a degree of narrowing a diameter of said laser beam near said emission exit of said beam transmitting path is smaller than a degree of narrowing said diameter of said laser beam near said emission entrance of said beam transmitting path. The expression “the degree of narrowing the diameter of laser beam in some section” in the specification means a value (a ratio) obtained by dividing “the diameter of laser beam emitted from some section” by “the diameter of laser beam which enters some section”.

According to this aspect of the invention, the degree of narrowing the diameter of the laser beam near the emission exit of the beam transmitting path is smaller than the degree of narrowing the diameter of the laser beam near the emission entrance of the beam transmitting path, so that the diameter of laser beam can be narrowed in steps, thereby obtaining laser beam optimum for machining in various kinds of meanings.

Another aspect of the invention is the laser beam generating unit, wherein said laser beam collecting means is an optical fiber bundle made by binding a plurality of optical fibers for individually transmitting laser beam respectively emitted from a plurality of beam emitting portions on a side where said laser beam is emitted, which is opposite to a laser beam receiving end facing a plurality of said beam emitting portions.

According to this aspect of the invention, a plurality of optical fibers are used as the laser beam collecting means, and the taper portion is provided on the side where laser beam is emitted and the laser beam is emitted through this taper portion. Then, the laser beam emitted from each of the beam emitting portions can be collected with high efficiency by the taper portion the diameter of which is narrowed, and the power density can be raised on the basis of such a principle that coherent laser beam can transmit in the taper beam guide path which is inclined at a predetermined angle, being reflected, with no beam loss.

Another aspect of the invention is the laser beam generating unit, wherein said laser beam collecting means is a lens.

According to this aspect of the invention, the laser beam collecting means is a lens, thereby simplifying its structure and its manufacturing routine in comparison with the optical fibers.

Another aspect of the invention is the laser beam generating unit, wherein said taper portion is made of a metal material, and said beam transmitting path has a taper hollow portion an inner face of which is polished.

According to this aspect of the invention, the taper portion is made of a metal material, and the beam transmitting path has the taper hollow portion an inner face of which is polished, so that a good beam transmitting path having no beam loss can be easily obtained only by forming a taper hole and polishing the inner face in the shape of a mirror having no irregularity.

Another aspect of the invention is the laser beam generating unit, wherein said taper portion is made of a metal material, and said beam transmitting path has a taper hollow portion at an inner face of which a reflecting film is formed.

According to this aspect of the invention, the taper portion is made of a metal material, and the beam transmitting path has the taper hollow portion at an inner face of which a reflecting film is formed, so that a good beam transmitting path having no beam loss can be easily obtained only by forming a taper hole and forming a reflecting film having no irregularity at its inner face.

Another aspect of the invention is the laser beam generating unit, wherein said taper portion is made of a synthetic resin material, and said beam transmitting path has a taper hollow portion at an inner face of which a metal reflecting film is formed by evaporation-plating.

According to this aspect of the invention, the taper portion is made of a synthetic resin material, and the beam transmitting path has the taper hollow portion at an inner face of which a metal reflecting film is formed by evaporation-plating, so that a good beam transmitting path having no beam loss can be easily obtained only by forming a taper hole and finishing the inner face in the shape of a mirror having no irregularity by evaporation-plating. Besides, the taper portion may be made of a glass material. In such a case, the same effects can be also obtained by forming a metal reflecting film on the inner face of the beam transmitting path by evaporation-plating.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following is an explanation of respective embodiments of the invention.

The First Embodiment

The first embodiment of the invention is now explained, referring to the appended drawingsFIGS. 1 through 3.

FIG. 1is a perspective view schematically showing the whole machine tool having a laser beam generating unit to which the invention is applied,FIG. 2is a cross section of a side of one laser beam generating unit inFIG. 1, andFIG. 3is a perspective view showing one laser beam generating unit ofFIG. 1including a part exploded.

As shown inFIG. 1, a machine tool1has a laser beam generating unit2for generating laser beam, a laser beam transmitting unit3for transmitting laser beam outputted from the laser beam generating unit2to a machining portion, and a laser beam radiating unit9for radiating transmitted laser beam from a torch9aon a workpiece W.

The laser beam generating unit2of the machine tool1is comprised of a plurality of laser beam generating units2A, each having a semiconductor laser unit12, a hardened resin14(seeFIGS. 2 and 3), and an optical fiber unit13comprised of end portions of optical fibers7aformed in the shape of a block by the hardened resin14.

In this embodiment, the laser beam generating unit2has three laser beam generating units2A, but the number of the laser beam generating units2A is optional, such as one, two, or four or more. That is, the number of the units2A is properly selected according to volume of output of laser beam necessary for each usage.

The laser beam generating unit2has a main body case2bhaving a through hole2aon its side, and three laser beam generating units2A are stored and located inside the main body case2b. Laser beam outputted from each laser beam generating unit2A is transmitted to an optical fiber8which projects outside the case from the through hole2a, via an optical fiber bundle7which is comprised of a plurality of optical fibers7a. Laser beam is collected from an aggregate of a plurality of optical fiber bundles7through an optical system (not shown) and enters the optical fiber8.

The laser beam transmitting unit3has the optical fiber8and four optical fibers4having a structure similar to the optical fiber8. Between the optical fiber8and the optical fibers4, mirrors5are respectively located. Such a problem that laser beam leaks out of the optical fibers4,8in the laser beam transmitting unit3when bending the fibers a predetermined angle or more (such as 8°) is solved by optically connecting two fibers through the mirror5, so that a path of transmitting laser beam can be freely designed.

A convex lens6ais located between an end portion on a side of output of laser beam (“the output side end portion” hereinafter) in the optical fibers8,4and the mirror5, and a convex lens6bis located between an end portion on a side of input of laser beam (“the input side end portion” hereinafter) in the optical fibers4and the mirror5. The laser beam which is emitted (oscillated) from each laser beam generating unit2A and transmitted through the optical fiber bundles7and the optical fiber8diffuses when outputted from the output side end portion of the optical fiber8. But, the diffused laser beam is converted into a parallel beam by the convex lens6a, and thereafter, is reflected by the mirror5, so that the direction of the laser beam changes a predetermined angle.

And, the parallel beam reflected by the mirror5is collected so as to be smaller than a diameter of a core member (not shown) owned by the optical fibers8,4by refraction of the lens6b, and is inputted in the core member of the input side end portion. Then, the laser beam diffused from one core member of the optical fibers8,4is collected and inputted into the core member of the other optical fiber4.

When emitting laser beam from the laser beam generating unit2with the above-mentioned structure, the laser beam is transmitted to a laser beam radiating unit9through the laser beam transmitting unit3, and is radiated on the workpiece W from the torch9aso as to focalize the laser beam with respect to the workpiece W through a lens (not shown) located in the torch9a.

Then, laser beam can be equally radiated on a surface of the workpiece when rotating the workpiece W in an arrow C direction ofFIG. 1at a predetermined speed. In case of the workpiece W made of steel, hardening machining can be executed on a portion 1.0 mm-1.5 mm from the surface of the workpiece W. The machine tool1is shown inFIG. 1only in order to explain the path of transmitting laser beam, so that a table, a driving unit for the table, and the other portions are omitted.

Subsequently, a structure of the laser beam generating unit2(2A) is explained, referring toFIGS. 2 and 3. As shown inFIGS. 2 and 3, each of the laser beam generating units2A comprising the laser beam generating unit2has the semiconductor laser unit12having a plurality of laser beam emitting portions11which are located in the shape of a matrix, each laser beam emitting portion11emitting laser beam L, and a plurality of optical fibers7afor individually transmitting the laser beam L which is emitted from each laser beam emitting portion11.

The expression “in the shape of a matrix” in this embodiment does not always means so-called arrangement in the shape of a matrix where pitches of a line direction (X direction) and a column direction (Y direction) are corresponded with each other, but includes arrangements having a broad meaning, such as an arrangement in the shape of a honeycomb where a plurality of portions arranged at a predetermined pitch in a line direction (or in a column direction) are shifted from the portions in the column direction (or in the line direction), an arrangement in the shape of a zigzag, and the other arrangements.

The semiconductor laser unit12is comprised of a plurality of semiconductor laser substrates26(nine, for instance) which are stacked up, each having a plurality of beam emitting portions (emitters)11arranged at a front face of the semiconductor laser unit12in the X direction, and is stored in a heat sink25having box-like shape. Each semiconductor laser substrate26has a microlens18arranged so as to cover each beam emitting portion11. The microlens18is for converting laser beam into parallel beam, and is a cylindrical lens or so. A notch for heat release25aformed in the shape of almost rectangular shape is formed at both sides of the heat sink25(only on side is shown inFIGS. 2 and 3).

The semiconductor laser substrate26is one made by connecting a p-type layer and a n-type layer having an activated layer therebetween. At a side of the activated layer, a plurality of beam emitting portions (emitters), capable of oscillating laser beam on the basis of voltage of the p-type layer and the n-type layer, are arranged in the X direction (seeFIG. 3). In such a semiconductor laser substrate26, the laser beam L (FIG. 3) is emitted from each beam emitting portion11when voltage is applied to the p-type layer and the n-type layer through an electrode (not shown).

A plurality of optical fibers7aare positioned and fixed by a glass system of hardened resin14in a predetermined length from each top end of the optical fiber7aso as to form a block so that each of the beam emitting portions11having a matrix shape can correctly face each beam receiving end7b(seeFIG. 2) and each pitch of the beam receiving end7bin the X direction and in the Y direction can correspond to each pitch between the beam emitting portions11in the X direction and in the Y direction with one to one. As mentioned before, the optical fiber unit13is comprised of the hardened resin14and the end portions of the optical fibers7awhich are formed in a block by the hardened resin14.

The optical fiber unit13takes the form of a rectangular parallelopiped which is relatively thin in a front/rear direction (in a thickness direction) in such a manner that the beam receiving ends7bof a predetermined number of optical fibers7a(such as 54 (6×9) ) are positioned and hardened with resin, and thereafter, a front end face14a(seeFIG. 2) of the hardened resin14is accurately polished so as to be strictly parallel to each beam receiving end7bof the optical fiber7a. If the optical fiber unit13having such a structure is used, many optical fibers7acan be correctly positioned at a one time such that the front end face14ais a standard with respect to the arrangement of the beam emitting portions11.

In this embodiment, the semiconductor laser unit12has nine steps of the semiconductor laser substrates26and six beam emitting portions11formed in each semiconductor laser substrate26. But, the number of the beam emitting portions11owned by one semiconductor laser substrate26or the number of steps of the semiconductor laser substrates26can be properly changed.

And, a Y-direction movement frame21is fitted onto a periphery of the front end face14aof the optical fiber unit13. The Y-direction movement frame21which supports the optical fiber unit13is engaged with Y-direction rails19,19, which are formed inside a X-direction movement frame20, and movably supported by both rails19,19in the Y direction. And, the Y-direction movement frame21has engagement convex portions21a,21b, capable of slidably engaging with the Y-direction rails19,19, at one side and the other side.

Between the semiconductor laser unit12and the optical fiber unit13, a positioning adjustment means15for correctly adjusting a positional relation between the beam emitting portion11and the beam receiving end7bto be positioned facing each other is located. The positioning adjustment means15is comprised of the Y-direction movement frame21installed on the optical fiber unit13, and a supporting body30for supporting the Y-direction movement frame21on a side of the semiconductor laser unit12.

The supporting body30has a support base16for fixedly supporting the semiconductor laser unit12in a predetermined state, and the X-direction movement frame20movably supported by the support base16in the X direction. The support base16has a base portion16a, and a pedestal portion16bfor supporting the semiconductor laser unit12which is formed at an almost central portion of the base portion16a.

And, the support base16has pole portions16c,16dextending in up/down direction (Y direction) having a predetermined space therebetween on a front side of the base portion16a(the right side ofFIG. 3), and beam portions17,17extending so as to connect upper portions of the pole portions16c,16dand to connect lower portions of the pole portions16c,16d. As shown inFIG. 2, X-direction rails17a,17bextending in a direction of a length of the beam portion are respectively formed at the beam portions17on the upper side and the lower side. That is, the X-direction rails17a,17bare arranged, having a predetermined space in the up/down direction of the front face of the semiconductor laser unit12(the face on the side of emitting beam), and the Y-direction rails19,19(one side is omitted in the figure for convenience) are arranged, having a predetermined space in the right/left direction of the front face of the side of emitting beam.

And, a tapped hole (now shown) is formed at a predetermined position of the pole portion16dso as to face the X direction. A X-direction adjusting screw22, for adjusting a position of the X-direction movement frame20with respect to the support base16in the X-direction, is fitted in the tapped hole. An end portion of the X-direction adjusting screw22abuts on one side of the X-direction movement frame20.

The X-direction movement frame20is formed so as to have almost rectangular shape and to have a space wherein the Y-direction movement frame21can move a predetermined distance in the X direction and in the Y direction in a space S between the pole portions16c,16dof the support base16. The X-direction movement frame20has engagement ditches20a,20bcapable of slidably engaging with the X-direction rails17a,17bsuch that a space of a central portion of the frame20is positioned at the front face of the semiconductor laser unit12, a tapped hole20c(seeFIG. 2) formed at a predetermined position of the movement frame20so as to face the Y direction, and an Y-direction adjusting screw23for adjusting a position in the Y direction of the Y-direction movement frame21with respect to the X-direction movement frame20by fitting in the tapped hole20c. An end portion23aof the Y-direction adjusting screw23is abutted on an upper side face of the Y-direction movement frame21which is held in a central space of the X-direction movement frame20.

A spring member (not shown), such as a plate spring and a coiled spring are formed between the pole portion16cand the X-direction movement frame20so as to shrink. Then, a X direction adjusting mechanism is structured, through which the position in the X direction of the X-direction movement frame20(that is, the optical fiber unit13) can be adjusted by rotationally moving the X-direction adjusting screw22with a rotational axis as its center in a direction and in the other direction so as to press or release the side of the X-direction movement frame20. Besides, as shown inFIG. 2, a spring member24, such as a plate spring and a coiled spring is formed between a bottom face of the X-direction movement frame20and a lower side of the Y-direction movement frame21so as to shrink. Then, a Y direction adjusting mechanism is structured, through which the position in the Y direction of the Y-direction movement frame21(that is, the optical fiber unit13) can be adjusted by rotationally moving the Y-direction adjusting screw23in a direction and in the other direction so as to press or release the upper side of the Y-direction movement frame21.

Respective members comprising the present laser beam generating unit2A are structured such that necessary portion thereof can be separated and assembled with a screw or the like as a matter of convenience of assemble work or installation of the optical fiber unit13on the supporting body30although the figures does not show.

In the machine tool1, the output of the laser beam emitted from each beam emitting portion11of the semiconductor laser unit12is small (1 w or so, for instance). But, in each laser beam generating unit2A, the semiconductor laser unit12is comprised of nine steps of the semiconductor laser substrates26which are stacked, the substrate26having a plurality of beam emitting portions11, each capable of emitting laser beam L. Then, it is possible to obtain high output of laser beam necessary for machining on the workpiece W by collecting large volume of the laser beam L from the semiconductor laser unit12. When providing a plurality of the laser beam generating units2A, as shown inFIG. 1, the higher output of laser beam can be obtained utilizing many semiconductor laser units12in such a machine tool1.

At the time of an assemble operation of the machine tool1, the optical fiber unit13is assembled on the supporting body30in a state ofFIG. 2. That is, the engagement convex portions21a,21bof the Y-direction movement frame21are slidably engaged with the Y-direction rails19,19by a predetermined operation, facing the front end face14aof the optical fiber unit13installing the Y-direction movement frame21in advance to the beam emitting portions11of the semiconductor laser unit12exposing from the X-direction movement frame20.

Subsequently, in order to adjust the positioning of the beam emitting portions11of the thus assembled laser beam generating unit2A and the beam receiving ends7bin the X direction and in the Y direction, the laser beam L which is emitted from a plurality of beam emitting portions11and transmitted through the optical fiber bundle7is displayed on a monitor (not shown) so as to watch the state. The X-direction movement frame20which supports the optical fiber unit13through the Y-direction movement frame21is slightly moved with respect to the support base16which supports the semiconductor laser unit12in the X direction, and the Y-direction movement frame21which supports the optical fiber unit13is slightly moved with respect to the X-direction movement frame20in the Y direction when properly rotationally gradually moving the X-direction adjusting screw22and the Y-direction adjusting screw23in a proper direction according to the state watched on the monitor.

In the laser beam generating unit2(2A) provided at the machine tool1, positions of the beam receiving ends7bof the optical fiber unit13with respect to many beam emitting portions11in the X direction and in the Y direction can be collectively adjusted with a high accuracy by properly rotationally moving the X-direction adjusting screw22and the Y-direction adjusting screw23.

Subsequently, a structure of the optical fiber bundle7is now explained in detail.

FIG. 4is one instance of optical fibers wherein (a) is a side view showing one optical fiber enlarged, (b) is a side view showing an end portion of an optical fiber bundle made by binding a plurality of optical fibers and an adaptor enlarged, and (c) is a front view showing a state seen from line Vc-VcofFIG. 4(b).

In this embodiment, an adaptor31which is a taper portion is connected with the end portions of the optical fibers7acomprising the optical fiber bundle7without machining the top end portion of each optical fiber7a.

In this embodiment, an emission end27bof the optical fiber7awhich is comprised of a core27and a clad28has a shape similar to the beam receiving end7b, as shown inFIG. 4(a). As shown inFIG. 4(b) (c), a plurality of optical fibers7a(the number is fifty four, for instance) are bound in one (on the side where laser beam emits which is opposite to the side of the beam receiving ends7bfacing a plurality of beam emitting portion11) so as to form the optical fiber bundle7. And, the optical fiber bundles7of the respective laser beam generating units2A are bound so as to form the optical fiber bundle7(54×3, for instance) having a bigger diameter.

In this embodiment, the expression “the optical fiber bundle7” of each laser beam generating unit2A is used for one made by binding three optical fiber bundles7. The number of the optical fibers7ainFIG. 4(b), (c) does not correspond to one of the actual optical fibers.

The adaptor31which is the taper portion is connected with an emission end7d, which is a portion through which laser of the whole optical fiber bundle7emits. As shown inFIG. 4(b), the adaptor31has almost cylindrical shape, and the adaptor31is connected with the optical fiber bundle7such that a connecting portion31dprojecting in the shape of like cylinder on the emission end7dside is inserted into an outer peripheral portion of the emission end7d, facing a side of emission entrance31athe inner diameter of which is bigger than an emission exit31bto the emission end7dof the optical fiber bundle7. The adaptor31is strongly fixed by the outer peripheral portion of the emission end7dthrough a fixing means (not shown).

The adaptor31which is the taper portion has the emission entrance31afacing the emission end7d, the emission exit31bcorresponding to the emission entrance31a, and a beam transmitting path31cconnecting the emission entrance31aand the emission exit31bwith each other. The beam transmitting path31cis tapered, having gradually thinner diameter from the side of the emission entrance31afor the emission exit31b. In this embodiment, the shape of the opened emission entrance31is a circle as shown with a reference number31aofFIG. 4(c). A plurality of small circles shown with a broken line inside the circle31ashows a shape of a cross section of the optical fiber7a, so that the shape of the cross section of laser beam collected by the optical fiber bundle7is an aggregate of concentric circles which are smaller than the respective small circles. In the end, the shape of the cross section of the laser beam collected by the optical fiber bundle7is smaller than the shape of the emission entrance opening in this embodiment. With such a structure, all the laser beam L emitted from each optical fiber7aof the optical fiber bundle7can be transmitted with no beam loss, being reflected by the inner face of the beam transmitting path31c. With such a structure, the optical fiber bundle7can function as means for collecting laser beam, for collecting the laser beam L emitted from a plurality of beam emitting portions11and entering into the emission entrance31a.

The adaptor31is made of a metal material, such as aluminum, and the beam transmitting path31chas a taper hollow portion formed so as to penetrate and so as to have gradually thinner diameter from the side of the emission entrance31aof the adaptor31for the side of the emission exit31b. The inner peripheral face of the beam transmitting path31cis strictly polished in order to save beam loss at the time of transmitting of laser beam as much as possible so as to have a flat face having no irregularity. Alternatively, a reflecting film for throughout transmitting laser beam is formed on the inner peripheral face of the beam transmitting path31cwhich is made of a metal material by a plating (coating) in order to save beam loss at the time of transmitting of laser beam as much as possible.

When using the optical fiber bundle7in this embodiment for the laser beam generating unit2(2A) the laser beam L emitted from many beam emitting portions11can be collected with high efficiency, and can be entered into the optical fiber8(seeFIG. 1) raising the power density due to presence of the adaptor31which is the taper portion. Besides, the beam emitting portions11in this embodiment are located in the shape of a matrix, the laser beam emitted from a plurality of beam emitting portions11is emitted in the shape of a matrix as it is. That is, the shape of the cross section of a group of the laser beam which is emitted from a plurality of beam emitting portions (in other words, the shape of the cross section of the area where the laser beam L emitted from a plurality of beam emitting portions distributes) is almost rectangular shape, and the shape of the cross section of the beam transmitting path31c(the shape of the emission entrance opening) is a small circle. According to this embodiment, the optical fiber bundle7is located between the beam emitting portions11and the beam transmitting path31cso that the laser beam emitted from a plurality of beam emitting portions11can be collected by the bundle7and enters in the emission entrance31a. Therefore, it is possible to avoid beam loss (beam leakage at the time of enter of laser beam from the optical fiber bundle7into the beam transmitting path31c) and to effectively utilize laser beam. Besides, according to this embodiment, the means for collecting laser beam are a plurality of optical fibers7a, and the taper adaptor31is provided at the side of emitting laser beam, and the laser beam is emitted through the adaptor31. Then, the laser beam emitted from each laser beam emitting portion can be collected with high efficiency by the adaptor which diameter is narrowed so as to improve power density on the basis of such a principle that coherent laser beam can transmit in the taper beam guide path which is inclined at a predetermined angle, being reflected, with no beam loss.

In addition, with a simple routine wherein a plurality of optical fibers7aare bound on the side of emitting laser beam so as to from the optical fiber bundle7and the emission end7dof the bundle7is connected with the adaptor31, the laser beam L can be effectively collected in order to obtain high output of laser beam for machining with laser beam although individual laser beam L is a lower output. Furthermore, the adaptor31is made of a metal material, and the beam transmitting path31chas the taper hollow portion, the inner face of which is polished, thereby easily obtaining the good beam transmitting path31cwith no beam loss if a taper hole is only formed at the adaptor31and its inner face is only polished in the shape of a mirror having no irregularity.

The adaptor31may be made of a strong synthetic resin material, such as a glass and transparent plastic, not of a metal material. That is, with a glass or a synthetic resin material, the adaptor31is formed so as to have a shape similar to a case where a metal material is used, and thereafter, a metal reflecting film, such as gold and silver, is formed on the inner peripheral face of the beam transmitting path31cby vacuum evaporation plating. Then, the adaptor31is structured with a glass or a synthetic resin material, and the beam transmitting path31cis comprised of the taper hollow portion, at the inner face of which a metal reflecting film is formed by evaporation plating, thereby easily obtaining the good beam transmitting path31cwith no beam loss if a taper hole is only formed at the adaptor31and its inner face is only finished in the shape of a mirror by evaporation plating with no irregularity.

InFIG. 4(b), the adaptor31is connected with the emission end7dof the optical fiber bundle7, but both the adaptor31and the optical fiber bundle7may not be connected with each other. For instance, both the adaptor31and the optical fiber bundle7may be supported by the same case or base plate so that the emission entrance31aof the adaptor31and the emission end7dof the optical fiber bundle7are faced each other.

As clear fromFIG. 4(b), the diameter of the beam transmitting path31cof the adaptor31in this embodiment is narrowed from the emission entrance31afor the emission exit31bat the same inclination (at the same rate) (that is, a degree of narrowing a diameter of laser beam is the same from the emission entrance31ato the emission exit31b). But, the degree of narrowing the diameter of laser beam near the emission exit31bof the beam transmitting path31cmay be made smaller than the degree of narrowing the diameter of laser beam near the emission entrance31a. In such a case, the diameter of laser beam can be narrowed in stages, thereby obtaining laser beam optimum for machining in various kinds of meanings. The expression “the degree of narrowing the diameter of laser beam in some section” in the specification means a value (a ratio) obtained by dividing “the diameter of laser beam emitted from some section” by “the diameter of laser beam which enters some section”.

The Second Embodiment

The second embodiment of the invention is now explained, referring toFIG. 5.

In the first embodiment, means for collecting laser beam (that is, means for collecting laser beam L emitted from a plurality of beam emitting portions11) is the optical fiber bundle7having a plurality of the optical fibers7a. But, the means for collecting laser beam in this embodiment are lens107as shown inFIG. 5, thereby simplifying its structure and its manufacturing routine in comparison with the optical fibers.FIG. 5is a perspective sectional view schematically showing another machine tool having the laser beam generating unit to which the invention is applied.

InFIG. 5, a reference number111denotes a beam emitting portion for emitting the laser beam L, and a reference number112denotes a semiconductor laser unit having a plurality of the beam emitting portions111arranged in the shape of a matrix, and a reference number102A denotes a laser beam generating unit.

A reference number131cis a taper beam transmitting path formed so as to gradually have a thinner diameter, and a reference number131adenotes an emission entrance of laser beam which is located at a position facing an emission end107dof the laser beam collecting means107, and a reference number131bdenotes an emission exit corresponding to the emission entrance131a. The parts131(a taper portion) having the emission entrance131a, the emission exit131band the beam transmitting path131cmay have a structure similar to the adaptor31. That is, the taper portion131may be made of a metal material, and the beam transmitting path131cmay have a taper hollow portion inner face of which is polished. Alternatively, the taper portion131may be made of metal material, and the beam transmitting path131cmay have a taper hollow portion at an inner face of which a reflecting film is formed. Furthermore, the taper portion131may be made of a synthetic resin material, and the beam transmitting path131cmay have a taper hollow portion at an inner face of which a metal reflecting film is formed by evaporation plating. The structures of the other parts may be similar to ones in the first embodiment.

The beam emitting portions111in this embodiment are arranged in the shape of a matrix, so that the laser beam L in the shape of a matrix is emitted from a plurality of beam emitting portions111as it is. That is, a shape of a cross section of a group of laser beam which is comprised of laser beam emitted from a plurality of the beam emitting portions111(in other word, the shape of the cross section of the area where laser beam emitted from a plurality of the beam emitting portions111distribute) is almost rectangular. On the other hand, the shape of the cross section of the beam transmitting path131c(the shape of the emission entrance opening) is a small circle. According to this embodiment, lens107are arranged between the beam emitting portions111and the beam transmitting path131cso that the laser beam emitted from a plurality of the beam emitting portions111is collected by the lens107and enters the emission entrance131a, thereby avoiding beam loss (that is, beam to be leaked at the time when laser beam enters into the beam transmitting path131cfrom the lens107, and effectively utilizing laser beam. The lens107to be used in this embodiment may collect a group of laser beam which broadly distributes in an area having an almost rectangular shape into an area of a small circle, or into an area having similar shape (that is, the area having a small rectangular shape) In this case, preferably, the shape of the cross section of the laser beam collected by the lens107is equal to the shape of the emission entrance opening or smaller.

A microlens (not shown inFIG. 5, see a reference number18ofFIG. 2) may be located so as to cover each beam emitting portion111so that the microlens can convert laser beam into parallel beam. Besides, the lens107may collect laser beam so as to be parallel to an optical axis in addition to only collecting laser beam from a plurality of the beam emitting portions111. In such a case, beam loss (irregular reflection) in the beam transmitting path131ccan be reduced.

In this embodiment, a degree of narrowing the diameter of laser beam near the emission exit131bof the beam transmitting path131cis smaller than a degree of narrowing the diameter of laser beam near the emission entrance131aof the beam transmitting path131c, as clear fromFIG. 5. Then, the diameter of laser beam can be narrowed in stages, thereby obtaining laser beam optimum for machining in various kinds of meanings.

The Third Embodiment

The third embodiment of the invention is now explained, referring to the appended drawingsFIGS. 6 through 19.

FIG. 6is a sectional view showing a structure of a machine tool according to the invention,FIG. 7is a perspective view showing an appearance of the machine tool according to the invention,FIG. 8is a sectional view showing the machine tool when installing a tool for cutting machining201,FIG. 9is a sectional view showing structures of a laser beam generating means and a tool for radiating laser beam,FIG. 10is a perspective view showing an appearance of a structure of the laser beam generating means,FIG. 11is a perspective view showing appearances of structures of the laser beam generating means and the tool for radiating laser beam,FIG. 12is a partial sectional view showing a structure of an installation portion of the tool for radiating laser beam,FIG. 13is an exploded perspective view showing a structure of a second beam guide portion4031,FIG. 14is a view showing a structure of a tapered beam path portion, andFIG. 15is a view showing a closing mechanism in an end of an opening (the tool side end portion) of the second beam guide portion4031.

A machine tool200according to the invention as shown inFIGS. 6 and 7has a workpiece holding means203for holding a workpiece W and a tool rest202for supporting a tool201as shown inFIG. 8.

Preferably, the workpiece holding means203can hold the stationary workpiece W, and move and rotate the workpiece W. The workpiece holding means for rotating the workpiece W are a chuck203A as shown inFIG. 19, a tail stock (not shown) and the like.

The tool rest202supports at least one tool, movably between a waiting position and a machining position (a position where the workpiece W is machined). Preferably, the tool rest202is rotatably moved around a rotationally moving axis202a. Preferably, the tool rest202has at least one tool installation portion2026, and the tool is attachably and detachably supported by the tool installation portion2026. A reference number2021ofFIG. 6denotes an axial portion, and a reference number2022denotes a movable portion rotatably supported by the axial portion2021, for rotating around the rotationally moving axis202atogether with the tool installation portion2026. A case2023stores the axial portion2021and the movable portion2022. A core2024is supported on a side of the case2023, and a coil2025is wound on the core2024. And, a plurality of magnets2027are located at a position facing the core2024at an outer peripheral face of the movable portion2022in the peripheral direction of the movable portion2022. When electrifying the coil2025with such a structure, a repulsive force or an attracting force generates between the core2024and the magnets2027, through which the movable portion2022and the tool installation portion2026can be rotated to predetermined rotational positions A cooling unit204cools an inside of the tool rest202by supplying air therein. In the tool rest202, big torque acts on the movable portion2022, so that large volume of heat generates on the driving portion (such as the core2024and the coil2025). The cooling unit204is effective for cooling such heat. With the cooling unit204, thermal expansion of the core2024and the coil2025can be reduced, thereby properly keeping a gap between the core2024and the magnet2027.

A laser beam generating means A for generating laser beam ofFIG. 6is located at the tool rest202, and hardening is executed on the workpiece W held by the workpiece holding means203with laser beam generated from the laser beam generating means A. According to the invention, hardening can be executed with the machine tool in addition to cutting machining, thereby preventing increase of a space for locating a laser beam hardening unit. Besides, it is not necessary to move a workpiece from a machine tool to a laser beam hardening unit, thereby shortening operation time and also simplifying the operations. Preferably, such hardening is executed, while rotating the workpiece W by the workpiece holding means203.

Preferably, the laser beam generating means A is located at a surface202bof the tool rest202, almost perpendicular to the rotationally moving axis202aif the tool rest202is rotationally moved around the rotationally moving axis202a. In such a case, it is sufficient to locate the laser beam generating means A in an existent empty space (that is, the surface of the tool rest almost perpendicular to the rotationally moving axis). Then, it is not necessary to secure a new location space, thereby avoiding a large sized machine tool.

Preferably, the laser beam generating means A is comprised of a semiconductor laser source402for emitting laser beam and a beam guide portion403for transmitting emitted laser beam, as detailedly shown inFIG. 9. When using the semiconductor laser source402, the laser beam generating means A can be made smaller, and can be located at the tool rest202.

Preferably, the semiconductor laser source402has a plurality of emitters4020which are openings for emitting laser beam, as detailedly shown inFIG. 10. The source402may be “an array type” wherein the emitters4020are arranged in a row or “a stack type” wherein a plurality of the arrays are stacked. Only one or more (as shown inFIG. 11) semiconductor laser sources402may be used. InFIG. 11, three sources402are shown, but the number may be two, four or more. Such kind of the semiconductor laser source402is a semiconductor laser stacked array “Light Stack” made by Coherent Inc. of the U.S.A., for instance. The array may be comprised of nineteen (19) emitters (40 W) and twenty five (25) layers of arrays may be stacked so that a total number of the emitters is 19×25=475 (40 W×25 layers=1 kW). When using three of such a laser beam stack as shown inFIG. 11, the total number of the emitters is 475×3=1425 (1 kW×3=3 kW).

Preferably, the beam guide portion403has a first beam guide portion4030comprised of a bundle of a plurality of optical fibers300, and a second beam guide portion4031located so as to pass laser beam from the first beam guide portion4030, as shown inFIG. 9. Preferably, the optical fiber300is located such that an end thereof faces the emitter4020in order to receive laser beam from each emitter4020(seeFIG. 10), and laser beam emitted from each emitter4020is transmitted. In such a case, output of laser beam can be raised since a plurality of optical fibers300collects laser beam emitted from each emitter4020. Preferably, the end portion of each optical fiber300in a state of being embedded in a resin301is located, facing each emitter4020. Preferably, a microlens4021(fast axis converging lens or slow axis converging lens) located between the end portion of the optical fiber300and the emitter4020collects laser beam from the emitter4020on an end face of the optical fiber300. Preferably, a sheet shaped microlens4021is attached to the semiconductor laser source402with an adhesive or by soldering. The other ends of the optical fibers300may be bundled. Preferably, the number of the optical fibers300is the same as one of the emitters4020.

Preferably, the second beam guide portion4031may be a beam guiding body (see a reference number312ofFIG. 12) having an outer peripheral face processed so as to reflect, and laser beam passes through the beam guiding body, being reflected by the outer peripheral face. Alternatively, the second beam guide portion4031may be a hollow path (see reference numbers310b,310c) formed inside a predetermined member310(“the path forming member” hereinafter) as shown inFIG. 13, and the inner face of the path is processed so as to reflect, and laser beam passes through the hollow path, being reflected by the inner face. Preferably, the path forming member310is made of metal, such as aluminium. A method of forming the hollow path is that the path forming member is formed so as to divide into a plurality of the members310, and a groove310bis formed at a mating face310a, as shown inFIG. 13. Preferably, mirror finish, lapping or metal coating is carried out on the portion of the groove310b. If the second beam guide portion4031is comprised of the beam guiding body, the position of the optical path of laser beam can be easily adjusted only by changing the position of the beam guiding body. If the second beam guide portion4031is comprised of the hollow path, the second beam guide portion can be formed by mechanical machining, and an accuracy of the position of the optical path of laser beam can be improved. If a material having superior heat conductivity is used for the predetermined material, an efficiency of cooling can be also improved.

Preferably, at least one of the first and second beam guide portions4030,4031has a tapered beam path portion having a cross-section (area of a transverse section) gradually reducing along a direction of advancing laser beam, and the laser beam from the semiconductor laser source402is improved in its power density in a process of passing through the tapered beam path portion. With this structure, hardening with laser beam can be smoothly executed.

The tapered beam path portion may be a bundle structure comprised of a plurality of optical fibers, having a cross-section gradually reducing. Preferably, such a structure is applied to the optical fibers300comprising the first beam guide portion4030(see a reference number302ofFIG. 12) If the number of the emitters4020is 1425, the number of the optical fibers300is necessary to be also 1425. If a diameter of one optical fiber300is 250 μm, the bundle diameter is 250 μm×1425=φ 11 mm. If the diameter of one optical fiber300is 500 μm, the bundle diameter is 500 μm×1425=φ 22 mm. When the bundle diameter remains φ 11 mm or φ 22 mm, the power density of laser beam is not raised and then, a hardening with laser can not be executed. Then, preferably, the cross section of the optical path of a bundle portion302is gradually reduced so that the bundle diameter becomes φ 4 through φ 5, and 100 W/mm2of power density (2 kW of output) is obtained.FIG. 14(a) shows one fiber300before processing to be tapered, a reference number300ais a clad, and a reference number300bis a core.FIG. 14(b) shows the fiber300after machining so as to be tapered, andFIG. 14(c) shows a bundle structure comprised of the fibers after tapering machining. A reference number303denotes a clad newly coated. Such bundle structure may be used for the second beam guide portion4031, not for the first beam guide portion4030.

Besides, a tapered fiber (see Japanese patent applications, Publication numbers are 2003-100123. 2003-75658 and 2002-289016) may be used for the tapered beam path portion.

As shown inFIG. 13, a tapered hollow path may be formed inside the predetermined member310.

Preferably, the tool installation portion2026supports the tool for cutting machining (see the reference number201ofFIG. 8), or supports a tool for emitting laser beam (reference numbers500,510ofFIGS. 6,7,9,11or12) in place of the tool for cutting machining. Then, the tools for emitting laser beam500,510can be detached from the tool rest202when not using, thereby preventing foreign objects from adhering to the tools for emitting laser beam500,510. Besides, the unit becomes compact since a single tool installation portion2026can support both the tool for cutting machining201and the tools for emitting laser beam500,510. Preferably, the beam guide portion403is located, extending from a portion near the semiconductor laser source402and to a portion near the tool installation portion2026, and has a tool side end portion4031anear the tool installation portion2026, and the tool for emitting laser beam500or510connects with the tool side end portion4031a, being supported by the tool installation portion2026, so that laser beam supplied from the semiconductor laser source402is radiated on the workpiece W.

When detaching the tools for emitting laser beam500,510in a structure wherein the tools can be detached, it is necessary to close the tool side end portion4031aof the beam guide portion403in order not to adhere or enter foreign objects, such as oil mist in the air. Preferably, a shutter means for opening and closing the tool side end portion4031ais provided so as to open the end portion4031awhen contacting the tools for emitting leaser beam500,510with the tool side end portion4031a, and so as to close the tool side end portion4031awhen detaching the tools for emitting laser beam500,510from the end portion4031ain order to save attachment of foreign objects to the end portion. Concretely speaking, a shutter means311may be provided so as to be moved to a closed position311cfor closing the tool side end portion4031aand an opened position311A for opening the end portion4031a, as shown inFIG. 15. That is, the shutter means311may be rotationally movable in a direction of a reference number E, and may enter or come out in an axial direction of the rotational axis as shown with a reference number F. Then, the end portion4031aof the beam guide portion403is opened so as to connect with the tools for emitting laser beam500,510in a state of311A, and the end portion4031ais closed in a state of311C after moving from311B so as not to enter foreign objects into the end portion4031aor adhere foreign objects to the end portion4031a. In the end, it is possible to avoid power down of laser beam due to presence of the foreign objects. Besides, the structure is simple if the shutter means is one shown inFIG. 15.

The machine tool may be one shown inFIG. 19. That is, the workpiece holding means203A rotates the held workpiece W, and a tool rest202A has a tool installation portion2026A. And, an automatic tool changer (not shown) may be located at a position facing the tool installation portion2026A (such as a position corresponding to a mechanical origin of the tool rest202A which is provided on a side of a direction D ofFIG. 19, and the automatic tool changer attaches and detaches the tool for cutting machining and the tools for emitting laser beam to and from the tool installation portion2026A. Then, cutting machining can be performed on the rotating workpiece W when installing the tool for cutting machining on the tool installation portion2026A, and a hardening can be performed on the rotating workpiece W when installing the tool for emitting laser beam on the tool installation portion2026A. Preferably, a stock portion (ATC tool magazine)210having a plurality of the tools for cutting machining and for emitting laser beam is provided, and the tool stocked by the stock portion210is installed in the tool installation portion2026A by the automatic tool changer. Preferably, the stock portion210has such a structure that a tool to be newly installed according to machining program is transferred to a position facing the automatic tool changer.

The tool for emitting laser beam is now explained, referring toFIGS. 16 through 18.FIG. 16(a) is a partial sectional view showing a structure of the tool for radiating laser beam,FIG. 16(b) is a side view showing a structure of a torch portion503, andFIG. 16(c) is a side view showing a structure of a shutter means505.FIG. 17(a) is a partial sectional view showing another structure of the tool for radiating laser beam, andFIG. 17(b) is a side view showing a structure of a torch portion513.FIG. 18is a view showing a structure of the shutter means for properly closing an end portion of a beam guide path (a path of laser beam) wherein (a) is a sectional view showing a state of a closed position, (b) is a sectional view showing a state of an opened position, and (c) is a side view showing a state of the closed position.

The tool for emitting laser beam500has a shape as shown inFIG. 16(a), and has an engagement portion501for engaging with the tool rest202of the machine tool200, a beam guide path502which is a path of laser beam supplied, and a torch portion503for emitting laser beam passed through the beam guide path502on the workpiece W.

The beam guide path502is a hollow path which is formed inside a predetermined member504, and an inner face of the path is preferably processed so as to reflect. With such a structure, laser beam passes through the hollow path, being reflected by the inner face. The processing of reflecting is lapping, mirror finish, or coating with gold or silver. The member504may be made of metal, such as aluminium. A method of forming the hollow path is that the member504is divided into a plurality of members, and a groove is formed at a mating face. If the member504is divided into a plurality of members, it is necessary that beam does not escape from a gap of the mating face. If the beam guide path is the hollow path502, the beam guide path can be formed by mechanical machining, and an accuracy of the position can be improved.

The beam guide path may be comprised of a beam guiding body512having an outer peripheral face processed so as to reflect, as shown inFIG. 17(a), not be comprised of the hollow path. In this case, laser beam passes through the beam guiding body512, being reflected by the outer peripheral face. The processing to reflect is coating with gold or silver, for instance. The beam guiding body is a glass, for instance. When forming the beam guide path with the beam guiding body512, the position of the optical path of laser beam can be easily adjusted only by change of a position of the beam guiding body512.

Preferably, a shutter means (reference number505inFIG. 16(a),515ofFIG. 17(a) and525ofFIG. 18)is located at an end portion of the beam guide path502or512in such a manner that an end portion502aor512aof the beam guide path502or512is opened so as to allow supply of laser beam when engaging the engagement portion501with the tool rest202, and the end portion502aor512aof the beam guide path502or512is closed so as to restrict attachment of foreign objects to the end portion or enter of foreign objects in the end portion when not engaging the engagement portion501with the tool rest202. In case of a machine tool, oil mist generally floats in the air. The above-mentioned shutter means505,515,525are very proper for restricting attachment of oil mist to the beam guide path502,512and enter of oil mist in the beam guide path502,512. And, power down of laser beam due to the presence of the foreign objects in the beam guide path can be avoided when using the tool for emitting laser beam.

The shutter means may be one as shown inFIG. 16(a) and (c), or as shown inFIG. 18.

The shutter means505as shown inFIG. 16(a) and (c) is comprised of an axial portion5051and a shutter member5052attached to the axial portion5051. When moving the axial portion5051in a direction as shown by arrows A and B, the shutter member5052selectively moves to a rotational position for opening the end portion502aof the beam guide path and a rotational position for closing the end portion502aof the beam guide portion through a cam mechanism (not shown).

The shutter means525as shown inFIG. 18(a), (b) and (c) is comprised of a shutter member5251movable to a closed position for closing the end portion512aof the beam guide path512(seeFIG. 18(a) and (c)) and an opened position for opening the end portion512a(seeFIG. 18(b)), and a spring member5252for energizing the shutter member5251to the closed position. The shutter member5251is moved to the opened position against the spring member5252when engaging the engagement portion501with the tool rest202, as shown inFIG. 18(b), and is moved to the closed position by an energizing force of the spring member5252when detaching the engagement portion501from the tool rest202. The shutter member5251may be formed with a rubber plate having a restoring force, and may be held by a member5253having almost cylindrical shape. If the shutter means is structured as shown inFIG. 16orFIG. 18, the members5051,5253abut on the tool rest202so as to freely move the shutter members5052,5251when attaching/detaching the tool for emitting laser beam to/from the machine tool, so that an operation for moving the member5251is not necessary, thereby avoiding an error operation and never failing to operate.

Preferably, cooling paths506,516in which fluid flows are formed near the beam guide paths502,512. In this case, heat generated due to passage of laser beam can be restricted. Fluid may be liquid (such as water) or gas. If the cooling path506,516is opened at a position facing the workpiece W and gas is injected on the workpiece W, it is possible to remove foreign objects on a surface of the workpiece, to avoid oxidizing the workpiece, and to cool. In case where a hardening with laser beam is performed after cutting machining, it is possible to remove water for cutting and cutting chips which remain on the surface of a workpiece, thereby improving a quality of machining with laser beam. When overheating the workpiece during a hardening, an efficiency of hardening reduces. In such a case, the workpiece is cooled with air purging so as to reduce decrease of the efficiency of hardening. If inert gas is used for gas, it is possible to shield a portion hardened.

The present invention has been explained on the basis of the example embodiments discussed. Although some variations have been mentioned, the embodiments which are described in the specification are illustrative and not limiting. The scope of the invention is designated by the accompanying claims and is not restricted by the descriptions of the specific embodiments. Accordingly, all the transformations and changes within the scope of the claims are to be construed as included in the scope of the present invention.

INDUSTRIAL APPLICABILITY

The present invention can be applied to various kinds of machines for obtaining a predetermined output of laser beam by collecting laser beam emitted from many semiconductor lasers.