WO2019239974A1

WO2019239974A1 - Laser machining head and laser machining device

Info

Publication number: WO2019239974A1
Application number: PCT/JP2019/022266
Authority: WO
Inventors: 俊英加藤
Original assignee: 株式会社アマダホールディングス
Priority date: 2018-06-15
Filing date: 2019-06-05
Publication date: 2019-12-19
Also published as: JP2019217509A; JP6589016B1

Abstract

In the present invention, a protective glass (7c) is disposed between a condenser lens (7b) and a nozzle (9). A swirling flow-channel part (82a) causes gas (G) supplied from the outside to swirl around an optical axis (CL7) of the condenser lens (7b). A filter (85) is formed of a porous material and is housed in the swirling flow-channel part (82a). An axial flow-channel part (82b) directs the flow of gas (G) that has passed through the filter (85) toward the protective glass (7c) along the optical axis (CL7) of the condenser lens (7b). A deflecting flow-channel part (82e) turns the flow of gas (G) that has passed through the axial flow-channel part (82b) into an inward flow (G4) directed to the optical axis (CL7) along a surface (7c1), of the protective glass (7c), on the near side of the nozzle (9).

Description

Laser processing head and laser processing apparatus

The present disclosure relates to a laser processing head and a laser processing apparatus.

The laser processing head included in the laser processing apparatus includes a focusing lens and a protective glass disposed closer to the nozzle than the focusing lens. The protective glass is arranged to prevent the focusing lens from being contaminated by fumes or spatters generated by laser processing.

If the protective glass is contaminated, it must be cleaned. Therefore, suppression of contamination of the protective glass has been studied to reduce the man-hours for cleaning the protective glass.
Patent Document 1 describes a technique of providing a flow path in a laser processing head for assist gas that is ejected from a nozzle during laser processing so that the assist gas flows along a lower surface that is a nozzle side surface of the protective glass. ing.

The laser processing head described in Patent Document 1 has an annular swirl flow path, a swirl flow generation flow path, and a gas rectifier.
In the laser processing head having this configuration, the assist gas passes through the gas rectifier after being turned into a swirl flow that flows in one direction in the annular swirl flow path. The assist gas is rectified so that the swirl component is reduced by the gas rectifying means and has a uniform velocity distribution in the circumferential direction, and flows through the lower surface of the protective glass.

Japanese Patent No. 6159583

When the laser processing head is used for a long time, the protective glass is also contaminated. Therefore, it is desired to more effectively prevent contamination of the protective glass and reduce the number of steps for cleaning the protective glass.
In the laser processing head described in Patent Document 1, in order to effectively prevent contamination of the protective glass, it is considered to rectify a larger flow rate of assist gas and flow it along the lower surface of the protective glass. .

In the laser processing head described in Patent Document 1, the swirling flow path and the gas rectifying means are disposed adjacent to each other in the radial direction below the protective glass.
In order to rectify the assist gas having a large flow rate, it is necessary to make the distance through which the assist gas passes through the gas rectifying means longer. That is, it is necessary to increase the radial thickness of the gas rectifying means.
In this case, the outer diameter of the laser processing head is increased, which causes a problem that space saving is difficult and measures for avoiding interference with other members are required.

Therefore, an object of the embodiment is to provide a laser processing head and a laser processing apparatus that can more effectively prevent contamination of the protective glass while suppressing an increase in size of the laser processing head.

According to the first aspect of the embodiment, the focusing lens, the nozzle, the protective glass disposed between the focusing lens and the nozzle, and the gas supplied from the outside around the optical axis of the focusing lens. A swirl flow path section that swirls the filter, a filter formed of a porous material and housed in the swirl flow path section, and the protection of the gas flow that has passed through the filter along the optical axis of the focusing lens. An axial flow path portion directed to glass, and a deflection flow in which the flow of the gas that has passed through the axial flow path portion is an inward flow toward the optical axis along the surface of the protective glass that is closer to the nozzle. A laser processing head comprising a path portion is provided.
According to the second aspect of the embodiment, the laser processing device includes a laser oscillator, a gas supply device, and a laser processing head, and the laser processing head focuses the laser light supplied from the laser oscillator into a desired light beam. A lens, a nozzle that emits the laser light, a protective glass that is disposed between the focusing lens and the nozzle and through which the laser light passes, and an optical axis of the focusing lens that supplies the gas supplied from the gas supply device A swirl flow path section that swirls around, a filter formed of a porous material and housed inside the swirl flow path section, and the flow of the gas that has passed through the filter along the optical axis of the focusing lens An axial flow path section that directs the protective glass, and an inward direction toward the optical axis along the surface of the protective glass near the nozzle of the gas flow that has passed through the axial flow path section The laser processing apparatus is provided which has a deflection channel portion to.

According to the laser processing head and laser processing apparatus of the embodiment, contamination of the protective glass can be more effectively prevented while suppressing an increase in the size of the laser processing head.

FIG. 1 is a diagram illustrating an overall configuration of a laser welding apparatus 51 that is an example of the laser welding apparatus according to the embodiment. FIG. 2 is a longitudinal sectional view showing the nozzle holder 8 and the nozzle 9 of the laser processing head 1 provided in the laser welding apparatus 51. FIG. 3 is a partial longitudinal sectional view showing the structure of the rectifying unit 10 in the nozzle holder 8. FIG. 4 is a cross-sectional view for explaining the gas flow G2 flowing through the swirl flow path portion 82a in the rectifying unit 10. FIG. 5 is a partial longitudinal sectional view showing the state of the rectifying unit 10 with the inner sleeve 84 removed. FIG. 6 is a longitudinal sectional view showing the inner sleeve 84. FIG. 7 is a schematic longitudinal sectional view for explaining the flow of the assist gas in the nozzle holder 8. FIG. 8 is a schematic longitudinal sectional view for explaining the flow of the assist gas in the nozzle holder 8P with the filter 85 of the rectifying unit 10 removed. FIG. 9 is a cross-sectional view illustrating a rectifying unit 10A that is a modification of the rectifying unit 10. FIG. 10 is a schematic longitudinal sectional view for explaining the flow of the assist gas in the nozzle holder 8A having the rectifying unit 10A. 10 is a plan view showing a filter 851 which is a modification of the filter 85. FIG.

The laser processing apparatus according to the embodiment will be described with reference to a laser processing apparatus 51 as an example.

(Example)
FIG. 1 is a configuration diagram showing a laser processing apparatus 51. The laser processing device 51 includes a laser processing head 1, a control device 2, a laser oscillator 3, and a gas supply device 4. The laser processing device 51 performs processing such as cutting or punching on the workpiece W by irradiating the laser beam Ls from the tip of the laser processing head 1.

The laser processing head 1 includes a main body portion 7, a nozzle holder 8 attached to the tip of the main body portion 7, and a nozzle 9 attached to the tip of the nozzle holder 8 in a detachable manner.
Inside the laser processing head 1, a collimating lens 7a, a focusing lens 7b, and a protective glass 7c are arranged from the side far from the nozzle 9. That is, the protective glass 7 c is disposed between the focusing lens 7 b and the nozzle 9.
The protective glass 7c prevents fumes or spatters coming from the nozzle 9 side from adhering to the focusing lens 7b.

The laser oscillator 3 is a fiber laser oscillator, for example, and generates and emits laser light. The emitted laser light is supplied to the laser processing head 1 through the fiber cable 5.
The gas supply device 4 uses a nitrogen cylinder as a gas source, and supplies high purity nitrogen gas as an assist gas to the laser processing head 1 through a gas supply hose 6.
The gas supply device 4 may be a device in which a gas source is air instead of a nitrogen cylinder, oxygen is separated by a separation filter such as a hollow fiber membrane to generate a nitrogen rich gas, and the gas is supplied to the laser processing head 1. Hereinafter, the gas supplied from the gas supply device 4 to the laser processing head 1 is referred to as a gas G.

The laser processing head 1 shapes the laser beam supplied from the laser oscillator 3 into a luminous flux having a desired characteristic by the collimating lens 7a and the focusing lens 7b disposed therein, and an opening at the tip of the nozzle 9 through the protective glass 7c. The laser beam Ls is emitted from 9a to the outside.
The laser processing head 1 injects the supplied gas G from the opening 9a of the nozzle 9 through the internal flow path.

The control device 2 controls the operation of the laser oscillator 3, the operation of the gas supply device 4, and the operation for beam shaping by the focusing lens 7 b of the laser processing head 1.

Next, the structure of the nozzle holder 8 in the laser processing head 1 will be described in detail with reference to FIGS.
FIG. 2 is a longitudinal sectional view showing a detailed structure of the nozzle holder 8 of the laser processing head 1. 3 is an enlarged longitudinal sectional view of the base 82 in FIG. 2, and FIG. 4 is a transverse sectional view at the position S4-S4 in FIG. FIG. 5 is a longitudinal sectional view showing a state in which a filter 85 (described later) is removed from the nozzle holder 8 shown in FIG. 3, and FIG. 6 is a longitudinal sectional view showing an inner sleeve 84 (described later). The vertical direction is defined as the direction of the arrow shown in FIG.

As shown in FIG. 2, the nozzle holder 8 includes a rectifying unit 10, a relay unit 81, and a plate 83.
The rectifying unit 10 includes a base 82, a protective glass 7 c attached to the base 82, an inner sleeve 84, and a filter 85.
The relay part 81 has a flange 811 at the upper part, and the nozzle 9 is attached to the lower end of the relay part 81 so as to be replaceable with screws. The relay part 81 is fixed to the base part 82 with screws N1 in a state where the flange 811 is sandwiched between the base part 82 and the plate 83.

As shown in FIG. 2 or FIG. 3, the base 82 has a through hole 821 whose center is the axis line CL7, and has a substantially prismatic appearance. The axis CL7 coincides with the optical axis of the focusing lens 7b.
A shelf 822 is formed as a peripheral shelf on the upper portion of the through hole 821. The protective glass 7 c is held on the shelf 822 by the presser plate 87 in a state where the O-ring 86 is compressed with respect to the shelf 822.
The through hole 821 has a reduced diameter portion 82c having a small inner diameter Da (see FIG. 5) just below the shelf portion 822. The through-hole 821 has an axial flow path portion 82b whose diameter increases as it goes downward from the reduced diameter portion 82c, and a swirl flow path portion 82a that extends with the same inner diameter along the axis CL7.
Further, the through hole 821 has an inner flange portion 82d having a smaller diameter than the reduced diameter portion 82c on the lower side of the swirl flow passage portion 82a.

As shown in FIG. 6, the inner sleeve 84 includes a base portion 84a having an outer diameter Db and a small-diameter protruding portion 84c having a smaller diameter than the base portion 84a. The small-diameter protruding portion 84c fits into the inner flange portion 82d of the base portion 82 without a gap.
The inner peripheral surface 84b of the inner sleeve 84 is an inclined peripheral surface whose diameter decreases from the base portion 84a side toward the small-diameter protruding portion 84c.
The outer diameter Db is set slightly smaller than the inner diameter Da of the reduced diameter portion 82c of the base portion 82.

The inner sleeve 84 is attached to the base 82 by being inserted into the through hole 821 of the base 82 from above and fitting the small-diameter protruding portion 84c into the inner flange portion 82d. Between the reduced diameter portion 82c of the base portion 82 and the outer peripheral surface 84a1 of the base portion 84a of the inner sleeve 84, an orifice space Vc is formed as an annular gap having a distance d1 in the radial direction.
That is, the reduced diameter portion 82c and the base portion 84a form an orifice 89 having a cross-sectional area in a plane orthogonal to the axis CL7 that is smaller than the cross-sectional area of the swirling space Va formed by the swirling flow passage portion 82a and the base portion 84a. Yes.

A top space Vd having a distance ta in the vertical direction is formed between the tip 84d above the inner sleeve 84 and the protective glass 7c.
A swirl space Va is formed as a space surrounded by the base portion 84a of the inner sleeve 84 and the swirl flow passage portion 82a of the base portion 82, and an introduction space Vb is formed as a space surrounded by the base portion 84a and the axial flow passage portion 82b. Has been.
The swirl space Va is formed in an annular shape having a longitudinal cross-sectional shape of a rectangle, and the introduction space Vb has a right-angled triangle with the vertical cross-sectional shape having the top at the top.
The inner space of the inner sleeve 84 is a frustoconical space upside down and is referred to as a base inner space Ve.

A filter 85 formed in an annular shape is accommodated in the swirl space Va. The filter 85 is filled with no gap at least in the radial direction below the swirl space Va. In this example, the filter 85 is formed such that the length L2 in the axial direction is larger than the thickness d2 in the radial direction in the longitudinal sectional shape.
The filter 85 is formed of a so-called porous material such as a porous metal or a porous resin, or a material corresponding thereto. The porous material is, for example, sintered metal or sintered resin, and the corresponding material is, for example, glass wool or wire mesh. An example of the porous metal is “Celmet (registered trademark)” manufactured by Sumitomo Electric Industries, Ltd.

As shown in FIG. 4, the base 82 has a gas introduction path 88 that extends at right angles to the axis CL <b> 7 at an axial position corresponding to the swirl flow path portion 82 a.
The gas introduction path 88 is a bottomed hole that opens as a connection port 824 on the side surface 823 of the base portion 82, and the back side communicates with the swirl flow path portion 82 a through the gas introduction port 88 a.
As shown in FIG. 5, the position P1 in the vertical direction of the gas inlet port 88a in the swirling channel portion 82a is closer to the lower side.

Returning to FIG. 4, the gas supply hose 6 shown in FIG. 1 is connected to the connection port 824 of the gas introduction path 88. As a result, the gas G supplied from the gas supply device 4 via the gas supply hose 6 passes through the connection port 824 and enters the swirl flow channel portion 82a from the gas introduction port 88a of the gas introduction channel 88 as the gas flow G1.
The gas introduction path 88 is formed so as to extend substantially in the tangential direction with respect to the swirling flow path portion 82a. Therefore, the gas flow G1 entering from the gas introduction port 88a flows in the swirl flow path portion 82a so as to swirl around the axis CL7 along the annular shape. This flow is referred to as swirl flow G2. The swirl direction of the swirl flow G2 is the counterclockwise direction in FIG.

The swirling flow G2 tends to flow in the counterclockwise direction of FIG. 4 through the inside of the filter 85 housed in the swirling flow path portion 82a. As described above, since the filter 85 is formed of a porous material, the resistance to the flow is large.
Therefore, as the swirl flow G2 flows while swirling upward, which becomes the outlet of the swirl flow path portion 82a, the flow velocity is made uniform in the circumferential direction and the swirl component decreases.

The filter 85 has a cylindrical shape in which the length L2 in the direction of the axis CL7 is longer than the radial thickness d2 in the cross-sectional shape. For this reason, when the swirling flow G2 passes upward from the filter 85, the flow velocity is sufficiently uniformed to become the upward flow G3 shown in FIG. 3 having no swirling component. The upward flow G3 is a flow that rises in parallel without turning and faces the protective glass 7c.
The upward flow G3 that escapes upward from the filter 85 and faces the protective glass 7c flows from the introduction space Vb to the orifice space Vc. That is, the axial flow path portion 82b that forms the introduction space Vb directs the flow of the gas G to the protective glass 7c as the upward flow G3.

The cross-sectional area of the flow path through which the upward flow G3 flows rapidly decreases from the introduction space Vb to the orifice 89. Therefore, the velocity of the upward flow G3 increases rapidly and passes through the orifice space Vc of the orifice 89.
Above the orifice 89, a protective glass 7c is disposed oppositely to block the upward path, the outer side in the radial direction of the channel is blocked by an O-ring 86, and the inner side in the radial direction communicates with the base inner space Ve. . Therefore, the upward flow G3 that has passed through the orifice 89 strikes the protective glass 7c and is deflected radially inward to become an inward flow G4.
The inward flow G4 passes through the top space Vd, which is a space between the tip portion 84d above the inner sleeve 84 and the protective glass 7c, and is centered along the surface 7c1 on the side close to the nozzle 9 of the protective glass 7c. Heading to the axis CL7. That is, the base portion 82, the inner sleeve 84, and the protective glass 7c that form the top space Vd serve as a deflection flow path portion 82e that deflects the upward flow G3 to the inward flow G4.
Since the inward flow G4 does not substantially have a swirl component as described above, the inward flow G4 becomes a downward flow G5 that travels downward along the axis CL7 after traveling toward the center in the radial direction.
As described above, the orifice 89 is provided in the gas G channel between the swirl channel unit 82a and the deflection channel unit 82e.

FIG. 7 is a schematic diagram showing the result of simulating the flow of the downward flow G5 in the base inner space Ve and the relay inner space Vf. The relay part internal space Vf is a space in the nozzle holder 8 and the nozzle 9. FIG. 7 shows only a typical flow at the center.

Since the inward flow G4 does not have a swirl component and there is no variation in the speed in the circumferential direction, the downward flow G5 descends the base inner space Ve and the relay inner space Vf substantially linearly in parallel with the axis CL7. It becomes a flow.
As a result, the assist gas Ga ejected to the outside from the opening 9a of the nozzle 9 becomes a converged flow that does not diffuse.

FIG. 8 is a schematic diagram showing a simulation result under the same conditions as a nozzle holder 8P obtained by removing the filter 85 from the nozzle holder 8 instead of the nozzle holder 8 as a comparative example with respect to FIG.
Since the filter 85 is not attached to the nozzle holder 8P of the comparative example, the flow corresponding to the downward flow G5 is generated as the downward flow G5P having a swirling component, and swirls through the base inner space Ve and the relay inner space Vf. Descend.
Thereby, the assist gas GaP from which the downward flow G5P is ejected to the outside from the opening 9a of the nozzle 9 becomes a flow that swirls and diffuses, and directionality may occur in the surface quality of the cut surface in the cutting process.
On the other hand, the nozzle holder 8 does not have a swirl component or generates a downward flow G5 with a small swirl component. Therefore, the assist gas Ga becomes a flow that converges, and in the cutting process using the laser processing head 1 provided with the nozzle holder 8, directionality is hardly generated in the surface quality of the cut surface.

As described above, the nozzle holder 8 of the laser processing head 1 has the annular swirl flow path so that the gas flow G1 of the gas G supplied from the gas supply device 4 is swung in one direction in the swirl flow path portion 82a. It has a gas introduction path 88 that is introduced in the tangential direction of the portion 82a.
Moreover, the nozzle holder 8 has a filter 85 formed of a porous material and extending long in the direction of the axis CL7 inside the annular swirl flow passage portion 82a.

As a result, the swirl flow G2 that enters the swirl flow path portion 82a and initially swirls gradually removes the swirl component as the flow flows upward with the outlet due to the resistance of the filter 85, and the flow velocity in the circumferential direction is uniform. Turn into.
Therefore, the downward flow G5 descending the relay portion internal space Vf that is the internal space of the nozzle holder 8 becomes a substantially parallel flow without a swirl component, and the assist gas Ga ejected from the nozzle 9 is a converged flow that does not diffuse. Become. Therefore, directionality is hardly generated in the surface quality of the cut surface, and good surface quality is obtained.

Further, the nozzle holder 8 has an annular orifice 89 above the swirling flow path portion 82a. As a result, the upward flow G3 is increased in speed and becomes an inward flow G4, and the adhesion of dirt to the protective glass 7c is more effectively prevented. Further, since the assist gas Ga ejected from the nozzle 9 is also increased in speed, the amount of gas consumed by the gas supply device 4 is reduced, and a cost suppressing effect is obtained.

Further, the rectifying unit 10 sets the flow direction passing through the filter 85 as the axial direction instead of the conventional radial direction. As a result, the laser processing head 1 is not increased in size, space is saved, and it is difficult to interfere with other members, so that the degree of freedom in designing the laser processing apparatus 51 is improved.

The example of the embodiment is not limited to the above-described configuration, and may be modified without departing from the gist of the present invention.

Although an annular filter 85 has been described in the laser processing apparatus 51 described above, the effect of reducing the swirling component can be obtained even in an arc shape.
FIG. 9 is a cross-sectional view showing an example of the rectifying unit 10A in which an arc-shaped filter 85A having a spread angle of 135 ° is attached to the swirling flow path unit 82a instead of the filter 85. FIG. 9 corresponds to FIG. 4 and can be compared.

As shown in FIG. 9, when the filter 85A is mounted so as to block the gas introduction port 88a that opens to the swirling flow path portion 82a, the swirling component of the swirling flow G2 may be reduced satisfactorily.

FIG. 10 is a schematic diagram showing the result of simulating the gas flow flowing inside the nozzle holder 8A having the filter 85A. In FIG. 10, only the central representative flow is shown.
As shown in FIG. 10, the downward flow G5A flowing through the base inner space Ve and the relay inner space Vf inside the nozzle holder 8A is slight because the nozzle holder 8A has a smaller reduction in the swirl component than the nozzle holder 8. Flows downward with a turn. And it ejects outside as assist gas GaA from the opening part 9a of the nozzle 9. FIG. Since the swirl component of the downward flow G5A is small, the ejected assist gas GaA does not substantially diffuse and becomes a generally converged flow.

The

filters

85 and 85A are not limited to those integrally formed in a 360 ° annular shape and a 135 ° arc shape, respectively. A plurality of filters formed in a small-angle arc shape may be connected in the circumferential direction, and the plurality of filters may be spaced apart in the circumferential direction.
For example, as shown in FIG. 11, a plurality of filters 851 and one filter 852 may be used instead of the filter 85 to form an approximately 360 ° annular filter.

When the annular filter 85 is integrally formed, for example, the base portion 82 of the nozzle holder 8 is divided into a vertical structure at the position P1 shown in FIG. 82a.
When the base portion 82 is structured not to be divided into upper and lower parts, as shown in FIG. 11, the filter 851 is set such that the length L2 corresponding to the chord of the arc is smaller than the inner diameter Da of the reduced diameter portion 82c of the base portion 82. By doing so, it can be mounted on the swirling flow path portion 82a.
In the example of FIG. 11, after four filters 851 are mounted, a filter 852 having a width that can be mounted in the remaining gap is mounted. In this case, between the filter 852 and the adjacent filter 851. Although a triangular gap is generated in a plan view, since the ratio of the gap to the entire filter is small, the downward flow G5 is a good flow having substantially no swirlability.

The number of gas inlets 88a is not limited to one, and a plurality of gas inlets 88a may be provided. When a plurality of gas introduction ports 88a are provided, the gas introduction paths 88 may be provided corresponding to the respective gas introduction ports 88a, or one gas introduction path 88 is shared and branched to and connected to each gas introduction port 88a. You may make it the structure to do.
The plurality of gas introduction ports 88a may be provided at equiangular intervals in the circumferential direction from the viewpoint of uniformizing the swirling flow G2 in the swirling flow path portion 82a. For example, when two gas introduction ports 88a are provided, they may be provided at positions separated by 180 ° (positions opposed in the radial direction).

The type of the laser oscillator 3 is not limited to the fiber laser. A carbon dioxide laser, a disk laser, a YAG laser, a diode laser, an excimer laser, or the like may be used.
The control device 2 may not be provided integrally with the laser processing device 51 as a structure. The control device 2 may be provided separately from the laser processing head 1, the laser oscillator 3, and the gas supply device 4 so as to be able to communicate with them wirelessly or by wire.

The disclosure of the present application is related to the subject matter described in Japanese Patent Application No. 2018-114519 filed on Jun. 15, 2018, the entire disclosures of which are incorporated herein by reference.

Claims

A focusing lens;
A nozzle,
A protective glass disposed between the focusing lens and the nozzle;
A swirl flow path section for swirling the gas supplied from the outside around the optical axis of the focusing lens;
A filter formed of a porous material and housed inside the swirl flow path portion;
An axial flow path section for directing the flow of the gas that has passed through the filter to the protective glass along the optical axis of the focusing lens;
A deflection flow path section that makes the flow of the gas that has passed through the axial flow path section an inward flow toward the optical axis along the surface of the protective glass near the nozzle; and
A laser processing head comprising:
The laser processing head according to claim 1, wherein an orifice is provided between the swirl flow path portion and the deflection flow path portion.
3. The laser processing head according to claim 1, wherein the filter is formed in an annular shape or an arc shape when viewed from the direction of the optical axis, and the length in the axial direction is longer than the radial thickness in the longitudinal sectional shape.
A laser oscillator;
A gas supply device;
A laser processing head;
With
The laser processing head is
A focusing lens that shapes the laser beam supplied from the laser oscillator into a desired light beam;
A nozzle for emitting the laser beam;
A protective glass that is disposed between the focusing lens and the nozzle and through which the laser beam passes;
A swirl flow path section for swirling the gas supplied from the gas supply device around the optical axis of the focusing lens;
A filter formed of a porous material and housed inside the swirl flow path portion;
An axial flow path section for directing the flow of the gas that has passed through the filter to the protective glass along the optical axis of the focusing lens;
A deflecting flow path section that makes the flow of the gas that has passed through the axial flow path section an inward flow toward the optical axis along the surface of the protective glass close to the nozzle;
A laser processing apparatus.
The laser processing apparatus of Claim 4 which has an orifice between the said turning flow path part and the said deflection flow path part.