Laser processing head and laser processing device

Abstract

The conversion element (71) converts a beam profile of a laser beam (Ls) supplied from the outside and emitted from the nozzle (215). The holder (61) holds the conversion element (71). The holder (61) is joined to the front end of the shaft (62). The actuator (64) moves the shaft (62) so that the conversion element (71) enters and retreats with respect to a light beam (Ls1) of the laser beam (Ls). A first flow path (FR1) through which a fluid that is a refrigerant (FL1) is able to flow from a root side to the holder (61) side and a second flow path (FR2) through which the fluid flowing in the first flow path (FR1) is able to flow in a manner of returning from the holder (61) side of the shaft (62) to the root side are formed inside the shaft (62).

Description

Technical Field

[0001] This disclosure relates to laser processing heads and laser processing apparatus. Background Technology

[0002] Patent Document 1 describes a laser processing head comprising an optical element that converts the beam profile of a laser beam into a predetermined beam profile, and a drive unit that holds the optical element and moves it relative to the laser beam. The laser processing head described in Patent Document 1, by inserting the beam profile-converting optical element into the laser beam, can convert the beam profile of the emitted laser beam into a beam profile corresponding to the optical element inserted into the beam.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2020-116603 Summary of the Invention

[0006] The thermal lensing effect is a phenomenon where a material's temperature rises and its density or refractive index changes when a laser beam is absorbed and its energy is converted into heat. Optical elements inserted into a laser beam do not allow the entire beam to pass through; therefore, they heat up by absorbing a portion of the laser beam's energy, which is then converted into heat. This heat is transferred from the heated optical element to the holding component of the drive unit that holds the optical element, causing the holding component to heat up and expand thermally.

[0007] When optical components overheat, the focal position of the laser beam shifts to a non-negligible degree due to the thermal lensing effect. Furthermore, excessive thermal expansion of the holding components can cause significant misalignment of the optical axis center, resulting in non-negligible defects. These phenomena lead to reduced processing accuracy and stability in laser processing.

[0008] Therefore, there is a desire for a laser processing head and laser processing apparatus that can transform the beam profile of the laser beam and is less prone to processing defects caused by thermal lensing or thermal conduction.

[0009] A first embodiment of one or more embodiments provides a laser processing head comprising: a conversion element for converting the beam profile of a laser beam supplied from the outside and emitted from a nozzle; a support for holding the conversion element; a shaft connected to the support at a front end; an actuator for moving the shaft such that the conversion element enters and exits relative to the laser beam; a first flow path formed inside the shaft and capable of allowing a fluid acting as a coolant to flow from the root side of the shaft toward the support side; and a second flow path capable of allowing the fluid flowing in the first flow path to flow back from the support side of the shaft toward the root side.

[0010] According to the first embodiment, the shaft connected to the bracket holding the conversion element has a first flow path for the refrigerant to flow toward the bracket and a second flow path for the refrigerant to return from the bracket side. Therefore, by allowing the refrigerant to flow in the first and second flow paths, the shaft, bracket, and conversion element can be cooled effectively.

[0011] A second embodiment of one or more provides a laser processing apparatus comprising: a laser oscillator that outputs a laser beam; a laser processing head having a conversion element for converting the beam profile of the laser beam supplied from the laser oscillator; and a refrigerant supply device that supplies refrigerant to the laser processing head, the laser processing head comprising: a support for holding the conversion element; a shaft connected to the support at a front end; an actuator for moving the shaft such that the conversion element enters and exits relative to the laser beam; a first flow path formed inside the shaft and capable of allowing the refrigerant supplied from the refrigerant supply device to flow from the root side of the shaft toward the support side; and a second flow path capable of allowing the refrigerant flowing in the first flow path to flow back from the support side of the shaft toward the root side.

[0012] According to the second embodiment, the shaft connected to the support holding the conversion element has a first flow path for refrigerant to flow toward the support and a second flow path for refrigerant to return from the support side, as well as a refrigerant supply device for supplying refrigerant to the first flow path. Therefore, by allowing refrigerant to flow in the first flow path and the second flow path, the shaft, support and conversion element can be cooled well.

[0013] The laser processing head and laser processing apparatus according to one or more embodiments are capable of converting the beam profile of the laser beam and are less prone to processing defects caused by thermal lensing effect or heat conduction. Attached Figure Description

[0014] Figure 1This is a diagram showing the overall structure of a laser processing apparatus 91, which is an embodiment of a laser processing apparatus as one or more implementations.

[0015] Figure 2 This is a longitudinal sectional view of the laser processing head 2 of the laser processing device 91.

[0016] Figure 3 Viewed from the front Figure 2 The top view at position S3-S3 is a diagram showing the first configuration of the contour conversion device 5 of the laser processing head 2.

[0017] Figure 4 This is a top view showing the second mode of the contour conversion device 5.

[0018] Figure 5 This diagram shows the cooling section RK of the laser processing head 2. Figure 5 (a) is Figure 3 A sectional view at position S5a-S5a in the diagram. Figure 5 (b) is Figure 5 A cross-sectional view at position S5b-S5b in (a).

[0019] Figure 6 This is a first cross-sectional view showing the heat transfer method of the moving part 6 of the conversion element in the contour conversion device 5.

[0020] Figure 7 This is a second cross-sectional view showing the heat transfer method of the moving part 6 of the conversion element.

[0021] Figure 8 It is a graph showing the change in temperature over time. Figure 8 (a) represents the temperature change in the case of the contour conversion device 5 of the embodiment. Figure 8 (b) represents the temperature change in the comparative example.

[0022] Figure 9 This is a diagram showing the cooling section RKA as a variation of the cooling section RK in Example 1. Figure 9 (a) is a partial sectional view. Figure 9 (b) is Figure 9 A sectional view at position S9b-S9b in (a).

[0023] Figure 10 This is a diagram showing the cooling unit RKB, which is a variation of the cooling unit RK in Example 2. Figure 10 (a) is a partial sectional view. Figure 10 (b) is Figure 10 A cross-sectional view at position S10b-S10b in (a).

[0024] Figure 11 This is a diagram showing the cooling section RKC, which is a variation of the cooling section RK in Example 3. Figure 11 (a) is a partial sectional view. Figure 11 (b) is Figure 11 A sectional view at position S11b-S11b in (a).

[0025] Figure 12 This is a diagram showing the cooling section RKD, which is a variation of the cooling section RK in example 4. Figure 12 (a) is a partial sectional view. Figure 12 (b) is Figure 12 A sectional view at position S12b-S12b in (a).

[0026] Figure 13 yes Figure 12 A sectional view at position S13-S13 in (a). Detailed Implementation

[0027] (Example)

[0028] The laser processing head and laser processing apparatus involved in one or more embodiments are explained by way of the laser processing head 2 and the laser processing apparatus 91 having the laser processing head 2. Figure 1 This is a block diagram illustrating the structure of a laser processing apparatus 91, as an embodiment of a laser processing apparatus according to one or more implementations. The laser processing apparatus 91 is configured to include a laser oscillator 1, a laser processing head 2, an NC (Numerical Control) device 3, a head drive unit 4, an operation unit 31, and a refrigerant supply device 8. The NC device 3 is an example of a control device.

[0029] The laser oscillator 1 generates a laser beam Ls of a predetermined wavelength, for example, using a fiber laser. The generated laser beam Ls is provided to the laser processing head 2 via an optical cable 1a and a coupler 1b. The laser oscillator 1 is not limited to a fiber laser oscillator, but can also be a solid-state laser oscillator, a direct diode laser oscillator, etc.

[0030] Figure 2 This is a longitudinal sectional view of the laser processing head 2 of the laser processing device 91. Figure 2 Arrows are used to indicate the directions: up, down, front, and back. The left side is the front edge of the paper, and the right side is the inside edge.

[0031] like Figure 1 and Figure 2As shown, the laser processing head 2 includes a coupler connection 23, a contour conversion device 5, a housing 21, a collimating lens drive 22, a focusing lens drive 24, and an optical element assembly 7. The optical element assembly 7 is configured to include a beam contour conversion element 71, a collimating lens 72, a bending mirror 73, and a focusing lens 74. Hereinafter, the beam contour conversion element 71 will be referred to as the conversion element 71.

[0032] like Figure 2 As shown, one end of the coupler connection 23 is connected to the coupler 1b, and the other end is connected to the contour conversion device 5. The contour conversion device 5 includes a conversion element moving part 6. The conversion element moving part 6 has a base part 51, an aperture 52, and a conversion element 71. The conversion element 71 enters and exits the laser beam Ls relative to the laser beam Ls by the movement of the conversion element moving part 6. Details of the contour conversion device 5 will be described later.

[0033] The housing 21 has a tubular first housing 212 and a second housing 213, which are L-shaped. One end of the first housing 212 is connected to the base portion 51 of the contour conversion device 5. The first housing 212 has a collimating lens 72 and a collimating lens drive portion 22 for moving the collimating lens 72. A 45° inclined surface 212a is formed inside the other end of the first housing 212, and a bending mirror 73 is mounted on the inclined surface 212a. The second housing 213 is connected to the other end of the first housing 212 in such a way that one end is orthogonal to the other end of the second housing 212. A nozzle bracket 214 is mounted at the front end of the other end of the second housing 213, and a nozzle 215 is detachably mounted on the nozzle bracket 214.

[0034] Inside the laser processing head 2, starting from the coupler 1b side, there are an aperture 52, a conversion element 71, a collimating lens 72, a bending mirror 73, and a focusing lens 74 arranged in sequence.

[0035] The laser beam Ls provided by the laser oscillator 1 is emitted as diverging light from the coupler 1b into the interior of the base portion 51 of the contour conversion device 5. The laser beam Ls, emitted as diverging light, passes through the opening 52a of the aperture 52 and, depending on the adjustment position of the collimating lens 72, becomes parallel light or light with a diverging angle or a converging angle. The angle-adjusted laser beam Ls is reflected by the bending mirror 73 and enters the second housing 213, where it is focused at a predetermined focal position by the focusing lens 74 and emitted from the nozzle 215 toward the workpiece W, which is the part being processed.

[0036] The conversion element 71 is inserted between the aperture 52 and the collimating lens 72 while converting the beam profile of the laser beam Ls1.

[0037] The collimating lens drive unit 22 has a drive unit 22K that includes a motor 21g. The drive unit 22K converts the rotational motion of the motor 21g into linear motion, causing the collimating lens 72 to move along the optical axis CL1 of the light beam Ls1 (refer to arrow DR1).

[0038] The focusing lens 74 moves linearly along the optical axis CL1 by the action of the focusing lens drive unit 24 (refer to arrow DR2). By moving the focusing lens 74 along the optical axis CL1, the focal position of the laser beam Ls emitted from the nozzle 215 is adjusted.

[0039] The conversion element moving part 6 causes the optical element, namely the conversion element 71, which converts the beam profile of the laser beam Ls supplied from the laser oscillator 1, to move back and forth between an entry position and a retraction position relative to the laser beam Ls1 entering the laser beam Ls.

[0040] Next, besides Figure 2 In addition, refer to Figures 3-7 The contour conversion device 5, which has a conversion element moving part 6, will be described in detail. Figure 3 Viewed from the front Figure 2 The top view at position S3-S3 is a diagram showing the first configuration of the contour conversion device 5 of the laser processing head 2. Figure 4 This is a top view showing the second mode of the contour conversion device 5. Figure 5 This diagram shows the cooling section RK of the laser processing head 2. Figure 3 A sectional view at position S5-S5. Figure 6 This is a first cross-sectional view showing the heat transfer method of the moving part 6 of the conversion element in the contour conversion device 5. Figure 7 This is a second cross-sectional view showing the heat transfer method of the moving part 6 of the conversion element.

[0041] like Figure 3 As shown, the contour conversion device 5 includes a base portion 51 and a conversion element moving portion 6. The base portion 51 is formed of a metal such as aluminum, and has a thin plate portion 511 formed in a plate shape with a slender shape on both sides, and a grid-shaped base 512 connected to the front end of the thin plate portion 511 in the longitudinal direction. Here, the metal material of the base portion can be made of an element with high thermal conductivity. If only this is considered, silver, copper, gold, magnesium, zinc, etc. can be selected in addition to aluminum. Here, aluminum is selected as the metal material of the base portion 51 based on cost, safety, and thermal conductivity efficiency. When the volume of the base portion is relatively small, copper can also be selected.

[0042] exist Figure 2 In Figure 2 The thin plate portion 511, which is not shown in the figure, is configured to extend to the left of the paper surface near the front relative to the optical axis CL1.

[0043] The base 512 has a rectangular bottom 512a and frame wall portions 512b that are erected facing forward in a rectangular frame shape from each side of the bottom 512a. The base 512 has a roughly circular through hole 51a at the bottom 512a centered on a position that forms the optical axis CL1 of the laser beam Ls (see reference). Figure 2 The aperture 52 is mounted such that it covers the through hole 51a from the front side, and has an opening 52a of a circular aperture hole with a predetermined area in the center.

[0044] An air ejection section 53 is formed on the inner surface of the through hole 51a of the base 512, on the side closer to the coupler 1b than the aperture 52. In this example, the air ejection section 53 is configured to include: three vent holes 53a to 53c arranged in a left-right direction; and an air supply section 53d with three branches at its front end that supply air to the vent holes 53a to 53c in parallel. The air is dry, dust-free air supplied by a supply source such as a compressor (not shown). The air ejected from the vent holes 53a to 53c flows within the laser processing head 2 at a higher pressure than the external air, preventing dust from adhering to the optical element assembly 7, etc.

[0045] The conversion element moving part 6 is configured to include a conversion element 71, a support 61, a shaft 62, and an actuator 64 as a linear actuator with a slider 63. The conversion element 71 is a circular, thin-plate component made of quartz, and converts the beam profile of the laser beam Ls. The support 61 holds the conversion element 71 such that the optical axis CL71 of the conversion element 71 is parallel to the optical axis CL1 of the laser beam Ls. The support 61 is a generally rectangular metal component when viewed from above.

[0046] like Figure 5 As shown, the bracket 61 has a stepped hole 61a for receiving the conversion element 71. The conversion element 71 is inserted into the stepped hole 61a, and the pressing flange 612 is threaded to the bracket 61 via the spring member 611 using the bolt 613, thereby the conversion element 71 is received and held in the bracket 61.

[0047] like Figure 3 As shown, the shaft 62 is formed from a metal such as stainless steel into a rod extending from left to right, and a bracket 61 is connected to the right end. A through hole 512c is formed on the left wall of the frame wall portion 512b of the base 512, and the shaft 62 is inserted through the through hole 512c. The bracket 61 is located in the internal space surrounded by the frame wall portion 512b.

[0048] The left end of shaft 62 is connected to slider 63 of actuator 64. Actuator 64 causes slider 63 to move left and right by a predetermined stroke according to the air supply status from first air supply port 641 and second air supply port 642 (refer to arrow DR3). The operation of actuator 64 is controlled by NC device 3. As slider 63 moves, bracket 61 connected to slider 63 also moves left and right.

[0049] Figure 3 This indicates that, through the movement of slider 63, bracket 61 is in the position where it has moved to the rightmost end of the predetermined stroke. Figure 4 This indicates that the support 61 is in the retracted position at the leftmost end of the predetermined stroke. That is, the conversion element 71 moves between the entry position and the retracted position relative to the laser beam Ls1 by the action of the actuator 64.

[0050] The slider 63 is externally provided with an inlet 631 for fluid to flow in and an outlet 632 for fluid to flow out. A refrigerant supply path 8a from the refrigerant supply device 8 is connected to the inlet 631.

[0051] like Figure 3 As shown, when the support 61 is in the engaged position, the optical axis CL71 of the conversion element 71 is aligned with the optical axis CL1 of the laser beam Ls. When the support 61 is in the engaged position, the entire cross-section of the laser beam Ls1 is contained within the effective area of ​​the conversion element 71, and the beam profile of the beam Ls1 is converted to a beam profile corresponding to the inherent conversion characteristics of the conversion element 71. Figure 4 As shown, when the bracket 61 is in the retracted position, not only the conversion element 71 but also the bracket 61 is in a position where it does not come into contact with the laser beam Ls1 of the laser beam Ls.

[0052] like Figure 5 As shown, a connector 633 is installed at the right end of the slider 63, and the left end of the shaft 62 is connected to the connector 633. The connector 633 has a connection passage 6331 and a connection passage 6332.

[0053] The conversion element moving part 6 has a cooling part RK for cooling the support 61 and the shaft 62. The cooling part RK is configured to include a blind hole 62a, a pipe 621, a connecting passage 6331, a connecting passage 6332, a connecting path 631a, a connecting path 632a, an inlet 631, and an outlet 632. The inlet 631 is connected to the refrigerant supply device 8 via a refrigerant supply path 8a.

[0054] Blind hole 62a is a non-through recess that opens on the left end face of shaft 62 and forms a straight line along the axis. The left end of blind hole 62a, serving as an outlet, connects to an L-shaped connecting passage 6332 formed in connector 633. Blind hole 62a is located at the center of bottom 62a1 beyond the length of shaft 62 and near support 61. Connecting passage 6332 connects to outlet 632.

[0055] Tube 621 is a tubular component supported at its left end by connector 633 and inserted into blind hole 62a parallel to it. Tube 621 is configured not to contact the inner surface of blind hole 62a. For example, the axis CL21 of tube 621 coincides with the axis CL2 of blind hole 62a. The internal space (first space) of the through hole 621a of tube 621 is the first flow path FR1 through which refrigerant FL1 can flow. The space V, which is the space between the outer surface of tube 621 and the inner surface of blind hole 62a (second space), is the second flow path FR2 through which refrigerant FL1 can flow.

[0056] The outer diameter of the tube 621 and the inner diameter of the hole 621a and the blind hole 62a can be set, for example, so that in a section orthogonal to the axis CL2, the cross-sectional area of ​​the first flow path FR1 is approximately the same as the cross-sectional area of ​​the second flow path FR2. The front end 621b of the tube 621 does not reach the bottom 62a1 of the blind hole 62a. As a gap between the bottom 62a1 and the tube 621, a connecting flow path FR3 is formed connecting the first flow path FR1 and the second flow path FR2. That is, the second opening 621d, which becomes the right end of the hole 621a of the tube 621, opens inside the blind hole 62a.

[0057] The distance between the front end 621b of the tube 621 and the front end position of the portion with a uniform inner diameter in the blind hole 62a (i.e., the front end position of the portion in the blind hole 62a other than the front end with progressively smaller diameter) in the direction of the axis CL2 is defined as the gap distance Da. The gap distance Da is set such that the refrigerant FL1, such as the fluid flowing out of the first flow path FR1, flows to the second flow path FR2 as unimpeded as possible through the connecting flow path FR3.

[0058] The first opening 621c at the left end of the hole 621a of the tube 621 is connected to the connecting passage 6331. The connecting passage 6331 is connected to the inlet 631.

[0059] Refrigerant FL1 supplied from refrigerant supply device 8 flows in cooling section RK. Refrigerant FL1 absorbs heat from the conversion element 71, support 61, and shaft 62, which are heated by the passage of laser beam Ls, and discharges it to the outside. The group of components that are heated by laser beam Ls, including at least conversion element 71, support 61, and shaft 62, is collectively referred to as heating component SB.

[0060] The temperature rise of the heating component SB is suppressed by the cooling effect of the cooling unit RK and the refrigerant supply device 8. The function of the cooling unit RK, etc., will be explained in detail.

[0061] The refrigerant supply device 8 supplies refrigerant FL1 to the outside via refrigerant supply line 8a. Refrigerant FL1 is, for example, a fluid, specifically water. Hereinafter, refrigerant FL1 will be described as water FL1. Water FL1 is, for example, at room temperature. Room temperature is a temperature above 20°C and below 35°C. That is, as... Figure 5 As shown in (a), the refrigerant supply device 8 continuously supplies water FL1 to the inlet 631 via the refrigerant supply path 8a. The supply of water FL1 by the refrigerant supply device 8 is controlled by the NC device 3.

[0062] Water FL1 supplied to inlet 631 flows into hole 621a from first opening 621c of pipe 621 via connecting passage 6331. Water FL1 flows within first flow path FR1 (refer to arrow DR4) towards second opening 621d at the front end. Water FL1 flows out from second opening 621d and into connecting flow path FR3 within blind hole 62a, where the flow direction is reversed (refer to arrow DR5), flowing in an annular second flow path FR2 between the outer surface of pipe 621 and the inner surface of blind hole 62a (refer to arrow DR6). Water FL1 is discharged to the outside from outlet 632 via connecting passage 6332 as discharged refrigerant, i.e., discharged water FL2.

[0063] like Figure 6 As shown, when the conversion element 71 is in the engaged position, the laser beam Ls1 of the laser beam Ls passes through the conversion element 71. At this time, the conversion element 71 absorbs a portion of the laser beam Ls as heat energy and heats up. As the temperature of the conversion element 71 rises, its heat moves radially to the support 61 holding the conversion element 71 via heat conduction (see arrow tm11), and the temperature of the support 61 also rises. The heat that moves to the support 61 moves towards the axis 62 connected to the support 61 via heat transfer (see arrow tm12).

[0064] A blind hole 62a is formed inside the shaft 62, and water FL1 flows inside the blind hole 62a. Therefore, heat from the shaft 62 moves from the inner surface of the blind hole 62a to the water FL1 through heat transfer (see arrow tm13). As a result, the temperature of the water FL1 rises, and the temperature rise of the shaft 62 is suppressed.

[0065] The temperature rise of the support 61 and shaft 62 is caused not only by the laser beam Ls passing through the conversion element 71, but also by the following phenomenon. For example, stray light tm2 (refer to) sometimes occurs due to diffuse reflection from the inner surface downstream of the conversion element 71 in the laser processing head 2. Figure 7The light irradiates the support 61 and shaft 62, causing the temperature to rise. Additionally, stray light tm3 (see reference) is sometimes repeatedly reflected between the incident surface 71a of the conversion element 71 and the aperture 52 opposite to that incident surface 71a. Figure 7 The temperature rises as the light shines on the support 61 and the shaft 62.

[0066] The heat from the stray light tm2 and stray light tm3 causing the temperature to rise in the support 61 and shaft 62 is transferred to the water FL1 flowing in the second flow path FR2. Therefore, the temperature rise in water FL1 inhibits the temperature rise in the support 61 and shaft 62. However, in these phenomena, the heat supplied to the heating element SB is relatively small; the main reason for the temperature rise in the heating element SB is the passage of the laser beam Ls in the conversion element 71. Therefore, under normal irradiation conditions of the laser beam Ls on the workpiece W, the temperature rise in the heating element SB is greatest in the conversion element 71, followed by the support 61 and shaft 62.

[0067] In this way, the laser processing head 2 with the cooling section RK can effectively suppress the temperature rise of the heating component SB.

[0068] Figure 8 It is a graph showing the change in temperature over time. Figure 8 (a) represents the temperature change when using the contour conversion device 5 of the embodiment. Figure 8 (b) represents the temperature change in the comparative example. That is, Figure 8 (a) is a graph showing the time change of temperature rise of support 61 and external air after the conversion element 71 is set to the in position and the laser beam Ls is output from laser oscillator 1 in the contour conversion device 5 with cooling section RK. Figure 8 (b) is a graph showing the temperature change over time of the support 61 and the outside air after the laser beam Ls is output from the laser oscillator 1 in a contour conversion device with the same structure except for the absence of a cooling section RK, with the conversion element 71 in the in position. In each graph, the elapsed time is 20 minutes.

[0069] like Figure 8 As shown in (a), with the cooling unit RK present, at the elapsed time of 0 minutes, the external air and support 61 are at approximately 23°C. After the elapsed time of 10 minutes, the support 61 heats up to approximately 33°C and remains at a saturation temperature after the elapsed time of 10 minutes. Figure 8 As shown in (b), without the cooling unit RK, the external air and the support 61, which are 23°C at 0 minutes, heat up as time passes and even after 20 minutes, reaching about 45°C, they do not reach saturation and continue to rise.

[0070] Compare Figure 8(a) and Figure 8 As shown in (b), by having a cooling section RK, the temperature rise of components SB, such as the conversion element 71 and the support 61, can be effectively suppressed. Therefore, the thermal lensing effect of the conversion element 71 in the laser processing head 2 is minimized, and variations in the focal position of the laser beam Ls can be suppressed to a practically unobstructed level, preventing any adverse effects. Furthermore, the thermal expansion of the support 61 and the shaft 62 is also minimized, and the offset of the optical axis center of the conversion element 71 can be suppressed to a practically unobstructed level, preventing any adverse effects. Therefore, the laser processing head 2 and the laser processing apparatus 91 with the cooling section RK can convert the beam profile of the laser beam Ls, and it is difficult for processing defects to occur.

[0071] The cooling section RK directs water FL1, which is at a lower temperature before heat transfer from the heating element SB, flowing in from the inlet 631, through the first flow path FR1 of pipe 621, into the blind hole 62a near the front end of the shaft 62, close to the conversion element 71 where the temperature rise is greatest. Therefore, the temperature difference between the water FL1 and the heating element SB, i.e., the shaft 62, which is the first point of contact, is large. Consequently, more heat is transferred from the shaft 62 to the water FL1, effectively suppressing the temperature rise of the heating element SB.

[0072] The flow direction of water FL1 can also be reversed. That is, water FL1 is injected from outlet 632 into the second flow path FR2 and flows towards the support 61 in the second flow path FR2. The water FL1 flowing in the second flow path FR2 flows towards the root side of the shaft 62 in the internal space of pipe 621, i.e., the first flow path FR1, through the connecting flow path FR3, and is discharged from inlet 631. In this flow direction, as water FL1 flows towards the support 61 in the second flow path FR2, heat moves from the shaft 62 and the temperature rises, and the temperature is higher than at the time of injection when it reaches the vicinity of the support 61. Therefore, it is effective in absorbing the heat of the shaft 62 more efficiently than the support 61.

[0073] In this way, the heat conduction method changes according to the flow direction of water FL1, so by reversing the flow direction appropriately, the deviation of the cooling method of the heated component SB can be corrected.

[0074] As described above, in a cross-section where the inner and outer diameters of pipe 621 and the inner diameter of blind hole 62a are orthogonal to axis CL2, the cross-sectional areas of the first flow path FR1 and the second flow path FR2 should be approximately the same. This ensures that the flow rate and velocity of water FL1 flowing in the first and second flow paths FR1 are approximately constant, making stagnation less likely. Therefore, heat transfer from shaft 62 to water FL1 proceeds with high efficiency, and the temperature rise of the heating component SB is more effectively suppressed.

[0075] The embodiments of the present invention are not limited to the structures described above, and may also be modified within the scope of the spirit of the present invention.

[0076] (Variation Example 1)

[0077] like Figure 9 As shown, the conversion element moving part 6 can also be the conversion element moving part 6A of the modified example 1, which replaces the cooling part RK and has a cooling part RKA. Figure 9 This is a diagram showing the cooling section RKA as a variation of the cooling section RK in Example 1. Figure 9 (a) is a partial sectional view. Figure 9 (b) is Figure 9 A sectional view at position S9b-S9b in (a).

[0078] The conversion element moving part 6A has a shaft 62A replacing the shaft 62. The shaft 62A has a blind hole 62Aa and a partition wall 6A1. The partition wall 6A1 is a thin plate-shaped component arranged in the diameter direction to divide the space within the blind hole 62Aa in two, except for the area near the bottom. The internal space of the blind hole 62Aa is divided by the partition wall 6A1 into a first flow path FR1 and a second flow path FR2. The space near the bottom that is not reached by the partition wall 6A1 becomes a connecting flow path FR3 that connects the first flow path FR1 and the second flow path FR2.

[0079] In this structure, when room temperature water FL1 is injected into the first flow path FR1, the water FL1 changes direction in the connecting flow path FR3 and flows through the second flow path FR2 as discharge water FL2 from the outlet 632 (in Figure 9 (Not shown in the figure) flows outward. As a result, during the flow of water FL1 in the first flow path FR1, the connecting flow path FR3 and the second flow path FR2, heat is transferred from the inner surface of the blind hole 62Aa and the water temperature rises. Instead, the temperature rise of the conversion element 71, the support 61 and the shaft 62A, which are the heating components SB, is suppressed.

[0080] Even when the shaft 62A is too thin to insert the tube into the blind hole 62Aa, the cooling section RKA of Modified Example 1 can easily form the first flow path FR1, the second flow path FR2, and the connecting flow path FR3.

[0081] (Variation Example 2)

[0082] like Figure 10 As shown, the switching element moving part 6 can also be the switching element moving part 6B of Variation 2, which replaces the cooling part RK and has a cooling part RKB. Figure 10 This is a diagram showing the cooling unit RKB, which is a variation of the cooling unit RK in Example 2. Figure 10 (a) is a partial sectional view. Figure 10 (b) is Figure 10 A cross-sectional view at position S10b-S10b in (a).

[0083] The conversion element moving part 6B has a bracket 61B and a shaft 62B that replace the bracket 61 and shaft 62, respectively, as well as a tubular conduit 6B2. The shaft 62B has a through hole 62Ba that is not a blind hole. The conduit 6B2 is configured to pass through the through hole 62Ba, surround the conversion element 71 of the bracket 61B in an arc shape on the radially outer side, and pass through the through hole 62Ba again. The conduit 6B2 passing through the bracket 61B is pressed and accommodated in a predetermined position by a pressing cover 6B1.

[0084] In this structure, room temperature water FL1 is injected into one of the pipes 6B2 within the through-hole 62Ba. The water FL1 flows towards the support 61B within the pipe 6B2 (refer to dashed arrow DR7), flows in an arc shape radially outward of the conversion element 71 in the support 61B (refer to dashed arrow DR8), and then flows in the opposite direction within the through-hole 62Ba (refer to dashed arrow DR9), exiting as discharge water FL2 from the outlet 632 (in... Figure 10 (Not shown in the diagram) flows outwards. In this structure, water FL1 heats up not only from shaft 62B but also from support 61B. This suppresses the temperature rise of the conversion element 71, support 61B, and shaft 62B, which are heating components SB.

[0085] In Modification 2, the cooling section RKB transfers heat to the conversion element 71, which has a large temperature rise, relative to the water FL1, thus better suppressing the temperature rise of the heating component SB.

[0086] (Variation Example 3)

[0087] like Figure 11 As shown, the conversion element moving part 6 can also be the conversion element moving part 6C of the modified example 3, which replaces the cooling part RK and has a cooling part RKC. Figure 11 This is a diagram showing the cooling section RKC, which is a variation of the cooling section RK in Example 3. Figure 11 (a) is a partial sectional view. Figure 11 (b) is Figure 11 A sectional view at position S11b-S11b in (a).

[0088] The moving part 6C of the conversion element has a shaft 62C that replaces the shaft 62. The shaft 62C is formed into a cylindrical shape by joining semi-cylindrical half-shaft parts 62C1 and 62C2 together. Figure 11 (a) or Figure 11As shown in (b), the half-shaft portions 62C1 and 62C2 each have a semi-circular cross-section and a U-shaped recess 6C1 and 6C2 respectively. On the shaft 62C that combines the half-shaft portions 62C1 and 62C2, a flow path FRC with a circular cross-section and a U-shaped arrangement in the length direction is formed, with the recesses 6C1 and 6C2 facing each other and folded back on the support 61 side.

[0089] In this structure, when room temperature water FL1 is injected into the flow path FRC, the water FL1 is turned back near the support 61 and discharged as outflow water FL2 from the outlet 632 (in Figure 11 (Not shown in the figure) flows out to the outside. As a result, during the flow of water FL1 in the flow path FRC, heat is transferred from the inner surfaces of the recesses 6C1 and 6C2, which are the inner surfaces of the flow path FRC, and the temperature rise is suppressed by the transfer of heat from the conversion element 71, the support 61, and the shaft 62C, which are the heating components SB.

[0090] In Modification 3, the moving part 6C of the conversion element can form the cooling part RKC without using tubular components, which is relatively inexpensive.

[0091] (Variation Example 4)

[0092] like Figure 12 As shown, the conversion element moving part 6 can also be the conversion element moving part 6D of the modified example 4, which replaces the cooling part RK and has a cooling part RKD. Figure 12 This is a diagram showing the cooling section RKD, which is a variation of the cooling section RK in example 4. Figure 12 (a) is a partial sectional view. Figure 12 (b) is Figure 12 A sectional view at position S12b-S12b in (a). Figure 13 yes Figure 12 A sectional view at position S13-S13 in (a).

[0093] The switching element moving part 6D has a bracket 61D, a pressing plate 61D, and a shaft 62D, which respectively replace the bracket 61 and the shaft 62. The bracket 61D has a circular recess, namely a receiving portion 61Da, for accommodating the switching element 71. The pressing plate 61D1 is a thin plate having a circular opening 61Db that exposes the switching element 71 except for its peripheral portion. The pressing plate 61D is formed of a thin metal plate with a higher thermal conductivity than the bracket 61D. For example, the bracket 61D is formed of aluminum, and the pressing plate 61D is formed of copper.

[0094] like Figure 12 and Figure 13As shown, a flange 62Dd extends from the front end of the shaft 62D. The pressing plate 61D fastens the flange 62Dd together with the bracket 61D using bolts N1. Through this structure, most of the heat from the heated conversion element 71 in the conversion element moving part 6D is transferred to the shaft 62D via the pressing plate 61D. As a result, the temperature rise of the conversion element 71 and the bracket 61D is effectively suppressed.

[0095] On the other hand, shaft 62D has a blind hole 62Dc with the support 61D side as the bottom, and a first tube 6D2 and a second tube 6D3 inserted into the blind hole 62Dc. The second tube 6D3 is longer than the first tube 6D2, is inserted into the hole of the first tube 6D2, and its front end protrudes from the first tube 6D2 toward the support 61D side.

[0096] The blind hole 62Dc has a first hole portion 62Da with a first inner diameter on its outlet side, and a second hole portion 62Db with a second inner diameter smaller than the first inner diameter on its inner side. A first tube 6D2 is disposed within the first hole portion 62Da with a length shorter than that of the first hole portion 62Da. A second tube 6D3 extends from the front end of the first tube 6D2 toward the support 61D side, with the extended portion positioned at a point closer to the outlet side than the bottom of the blind hole 62Dc, and is disposed within the second hole portion 62Db. The second tube 6D3 is connected and supported to the first tube 6D2 on its outlet side by a connecting piece 6D4.

[0097] In this structure, water FL1 is injected from the end opposite to the support 61D into the interior of the first pipe 6D2 and the second pipe 6D3. The water FL1 injected into the second pipe 6D3 flows within it (refer to arrow DR10), and flows out into the blind hole 62Dc near the bottom (refer to arrow DR11), reversing its flow direction to become a return flow. The water FL1 injected into the first pipe 6D2 flows within it, and flows out into the blind hole 62Dc near the boundary between the first orifice 62Da and the second orifice 62Db (refer to arrow DR12). The water FL1 flowing from the first pipe 6D2 and the second pipe 6D3 into the blind hole 62Dc becomes a combined return flow, exiting as discharge water FL2 from outlet 632. Figure 12 (Not shown in the diagram) flows out to the outside.

[0098] The cooling unit RKD has multiple flow paths (two in this example) for supplying water FL1 into the blind hole 62Dc, as described above, and the water FL1 flows out of the blind hole 62Dc from each flow path at different positions in the axial direction. Therefore, deviations in the length direction can be reduced, allowing heat to be transferred as uniformly as possible from the shaft 62D to the water FL1. Consequently, under the same temperature reduction gradient, the shaft 62D as a whole is well cooled, thus effectively suppressing the temperature rise of the support 61D and the conversion element 71 held by the support 61D.

[0099] The aforementioned modifications 1 to 4 each have cooling sections RKA to RKD, thereby enabling the conversion element 71 to convert the beam profile of the laser beam Ls and effectively suppressing the temperature rise of the heating component SB. Therefore, the thermal lensing effect caused by the heating of the conversion element 71 is minimal, and changes in the focal position of the laser beam Ls can be suppressed to a level that is not problematic in practical use, thus preventing any issues. Furthermore, the thermal expansion of the supports 61A to 61D and the shafts 62A to 62D is also minimized, and the positional deviation of the optical axis of the conversion element 71 can be suppressed to a level that is practically unobstructed, preventing any adverse conditions.

[0100] As described above, the laser processing head 2 and the laser processing apparatus 91 equipped with the cooling sections RK or RKA to RKD of the embodiments and modifications 1 to 4 can change the beam profile of the laser beam Ls and are less prone to processing defects.

[0101] The above describes an example of using water as refrigerant FL1, but refrigerant FL1 is not limited to water. Furthermore, refrigerant FL1 may also be a gas rather than a fluid. If water is used as refrigerant FL1, it can be applied inexpensively and is easy to handle. The above embodiments and variations 1 to 4 can be freely combined within possible combinations.

[0102] This application claims priority based on Japanese Patent Application No. 2021-069778, filed on April 16, 2021, the entire disclosure of which is incorporated herein by reference.

Claims

1. A laser processing head, characterized in that, have: A conversion element that converts the beam profile of a laser beam supplied from the outside and emitted from a nozzle; A support that holds the conversion element; A shaft, which has the bracket connected to its front end; and An actuator that moves the shaft, causing the conversion element to enter and retract relative to the laser beam. The conversion element, the support, and the shaft are heating components that are heated by the laser beam. The laser processing head also features: A first flow path is formed inside the shaft and enables the fluid that is the refrigerant to flow from the root side of the shaft toward the support side; as well as A second flow path allows the fluid flowing in the first flow path to flow back from the support side of the shaft to the root side. The shaft has a blind hole at the bottom on the support side and a tube disposed inside the blind hole. The first space inside the tube is the first flow path. The second space between the inner surface of the blind hole and the outer surface of the tube is the second flow path.

2. A laser processing apparatus, characterized in that, have: A laser oscillator that outputs a laser beam; A laser processing head having a conversion element for converting the beam profile of a laser beam supplied from the laser oscillator; and A refrigerant supply device supplies refrigerant to the laser processing head. The laser processing head comprises: A support that holds the conversion element; A shaft, which has the bracket connected to its front end; and An actuator that moves the shaft, causing the conversion element to enter and retract relative to the laser beam. The conversion element, the support, and the shaft are heating components that are heated by the laser beam. The laser processing head also features: A first flow path is formed inside the shaft and enables the refrigerant supplied from the refrigerant supply device to flow from the root side of the shaft toward the support side. as well as A second flow path allows the refrigerant flowing in the first flow path to flow back from the support side of the shaft to the root side. The shaft has a blind hole at the bottom on the support side and a tube disposed inside the blind hole. The first space inside the tube is the first flow path. The second space between the inner surface of the blind hole and the outer surface of the tube is the second flow path.

3. The laser processing apparatus according to claim 2, characterized in that, The refrigerant is water.

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