JP4331626B2 - Laser hardening method - Google Patents

Description

  The present invention relates to a laser quenching method using a laser beam, and more particularly to a laser quenching method for forming a circular or annular quenching region on a workpiece using a laser beam.

  In general, a laser quenching method using a laser beam is known as a method for quenching a workpiece made of a metal material. This laser quenching method irradiates the surface of a workpiece with a laser beam, rapidly heats the vicinity of the surface of the workpiece, and performs self-cooling by heat conduction inside the workpiece, thereby forming a hard quenching layer near the surface of the workpiece. To form.

  And this laser quenching method is capable of locally quenching a part of the workpiece that needs to be quenched, that there is very little thermal strain associated with the quenching process, water for cooling the quenched workpiece, It has the characteristic that oil etc. are unnecessary.

  Here, as a conventional technique for forming a circular or annular quenching region on a workpiece using a laser beam, the laser beam spot irradiated on the surface of the workpiece is removed by removing the central portion of the laser beam output from the laser oscillator. There is known a laser quenching method in which an annular quenching region is formed in the vicinity of the surface of a workpiece by making the shape annular (see, for example, Patent Document 1).

JP-A-2-133511

  On the other hand, as another conventional technique for forming a circular or annular quenching region on a workpiece, there is known a laser quenching method in which a laser beam is irradiated toward the workpiece while rotating the laser beam and the workpiece relative to each other (for example, Patent Document 2).

JP-A-8-337821

  In another conventional laser hardening method, for example, an annular hardened region is formed on a work such as a disk-shaped saw (round saw), and the surface of the work is irradiated with a laser beam while the work is rotated. It is. Thereby, the vicinity of the surface of the workpiece is heated in an annular shape by the laser beam, and an annular quenching region can be formed in the vicinity of the surface of the workpiece.

  By the way, the laser quenching method according to the prior art described in Patent Document 1 described above irradiates the surface of the workpiece with a laser beam having an annular spot shape by removing the central portion of the laser beam output from the laser oscillator. To do. Therefore, when increasing the area of the annular quenching region to be formed on the workpiece, it is necessary to enlarge the spot shape area by blurring the focal point of the laser beam irradiated on the workpiece surface. For this reason, the energy of the laser beam per unit area irradiated on the surface of the work is reduced, and it becomes impossible to heat the vicinity of the surface of the work to a predetermined quenching temperature, or the vicinity of the surface of the work is predetermined. There is a problem that the heating time until reaching the quenching temperature becomes long.

  On the other hand, in the laser quenching method according to another conventional technique described in Patent Document 2 described above, an annular quenching region is formed near the surface of the workpiece by irradiating the surface of the workpiece with a laser beam while rotating the workpiece. To do. For this reason, when forming an annular quenching region by irradiating a rotating workpiece with a laser beam, the irradiation time of the laser beam on the workpiece becomes shorter on the outer periphery side of the annular quenching region, and on the inner periphery side of the quenching region. It tends to be long.

  Thereby, since the amount of heat input by the laser beam is larger toward the inner peripheral side than the outer peripheral side, the quenching area formed on the workpiece has a deeper quenching depth on the inner peripheral side of the quenching region where the heat input is large, The quenching depth becomes shallow on the outer peripheral side of the quenching region where the heat input is small. As described above, another conventional laser hardening method has a problem that it is difficult to form a circular or annular hardening region having a substantially uniform hardening depth on the workpiece.

  The present invention has been made in view of the above-described problems of the prior art, and when a circular or annular quenching region is formed on a workpiece using a laser beam, the quenching depth is almost uniform over the entire region. An object of the present invention is to provide a laser quenching method capable of forming a quenching region.

  In order to solve the above-described problems, the present invention irradiates a laser beam from the laser irradiation device toward the workpiece while relatively rotating the laser irradiation device that irradiates the laser beam and the workpiece, and the workpiece is circularly or annularly quenched. It is applied to a laser hardening method formed by forming

The invention according to claim 1 is characterized in that the laser beam has a spot shape extending from the inner peripheral side to the outer peripheral side of the quenching region and irradiates the outer peripheral side and the inner peripheral side of the quenching region at the same time. heat input of the laser beam irradiated on the outer peripheral side of the region is that the set to be larger than the heat input of the laser beam irradiated on the inner peripheral side of the quenching region.

  The invention of claim 2 is that the spot shape of the laser beam irradiated to the workpiece is set so that the outer peripheral side of the quenching region is large and the inner peripheral side of the quenching region is small.

  The invention according to claim 3 is that the intensity distribution of the laser beam applied to the workpiece is set larger on the outer peripheral side than on the inner peripheral side of the quenching region.

  The invention according to claim 4 is that the heat input amount of the laser beam irradiated to the quenching region is set by a segment mirror provided in the laser irradiation apparatus.

  The invention according to claim 5 is that the heat input amount of the laser beam irradiated to the quenching region is set by a diffractive lens provided in the laser irradiation apparatus.

According to the invention of claim 1, by irradiating the workpiece with the laser beam while relatively rotating the laser irradiation device and the workpiece, the irradiation time of the laser beam on the workpiece is short on the outer peripheral side of the annular quenching region. , It becomes longer on the inner peripheral side of the quenching region. However, the laser beam irradiates the inner peripheral side and the outer peripheral side of the quenching region at the same time , and the amount of heat input of the laser beam irradiated to the outer peripheral side of the quenching region is determined by the laser beam irradiated to the inner peripheral side of the quenching region. By setting the amount larger than the heat input amount, the outer peripheral side of the quenching region where the irradiation time of the laser beam is short and the inner peripheral side of the quenching region where the irradiation time is long can be heated almost uniformly by the laser beam. Thereby, the quenching depth of the circular or annular quenching region formed on the workpiece can be made almost uniform over the entire region, and a uniform quenching process is performed in the vicinity of the surface of the workpiece using the laser beam. be able to.

  According to the second aspect of the present invention, the spot shape of the laser beam applied to the workpiece is set to be large on the outer peripheral side of the quenching region and to be small on the inner peripheral side of the quenching region. Thereby, when the laser beam and the workpiece are relatively rotated to form a circular or annular quenching region on the workpiece, the amount of heat input on the inner peripheral side of the quenching region with a long irradiation time of the laser beam is reduced, The amount of heat input on the outer peripheral side of the quenching region with a short laser beam irradiation time can be increased. As a result, the quenching depth of the quenching region formed on the workpiece can be made substantially uniform over the entire region.

  According to the invention of claim 3, since the intensity distribution of the laser beam irradiated to the workpiece is set so that the outer peripheral side is larger than the inner peripheral side of the quenching region, the laser beam irradiation time is longer in the quenching region. While reducing the amount of heat input on the peripheral side, it is possible to increase the amount of heat input on the outer peripheral side of the quenching region where the laser beam irradiation time is short. As a result, the quenching area of the workpiece can be heated almost uniformly by the laser beam, and the quenching depth of the quenching area formed on the workpiece can be made substantially uniform over the entire area.

  According to invention of Claim 4, while adjusting the laser beam irradiated to a workpiece | work from a laser irradiation apparatus with a segment mirror, while reducing the amount of heat inputs in the inner peripheral side of a quenching area | region, on the outer peripheral side of a quenching area | region The amount of heat input can be increased.

  According to the invention of claim 5, the amount of heat input on the inner peripheral side of the quenching region is reduced by adjusting the laser beam irradiated to the workpiece from the laser irradiation device by the diffraction type lens, and the outer peripheral side of the quenching region. The amount of heat input at can be increased.

  Hereinafter, an embodiment of a laser quenching method according to the present invention will be described in detail with reference to FIGS. 1 to 9 by taking as an example a case where a swash plate used in a swash plate hydraulic pump is subjected to a quenching process. First, FIG. 1 to FIG. 6 show a first embodiment of the present invention.

  In the figure, reference numeral 1 denotes a fixed displacement swash plate hydraulic pump. The swash plate hydraulic pump 1 includes a casing 2, a rotating shaft 5, a cylinder block 8, each piston 10, a swash plate 13, a valve plate 14 and the like which will be described later. Has been.

  Reference numeral 2 denotes a casing that forms an outer shell of the swash plate hydraulic pump 1. The casing 2 is provided with a casing main body 3 formed into a bottomed cylindrical shape from a cylindrical portion 3A and a bottom portion 3B, and an opening end side of the cylindrical portion 3A. It is roughly constituted by the lid body 4 to be covered. A shaft insertion hole 3 </ b> C through which a rotation shaft 5 described later is inserted is formed in the bottom 3 </ b> B of the casing body 3. In addition, a pair of supply / discharge passages 4A and 4B is formed in the lid 4 as shown by a two-dot chain line.

  Reference numeral 5 denotes a rotating shaft rotatably provided on the casing 2 via bearings 6 and 7, and 8 denotes a cylinder block splined to the outer peripheral side of the rotating shaft 5. The cylinder block 8 is a rotating shaft in the casing 2. 5 and rotate together. One end surface of the cylinder block 8 faces a swash plate 13 described later, and the other end surface is in sliding contact with a valve plate 14 described later.

  .. Are a plurality of cylinders drilled in the cylinder block 8. The cylinders 9 are spaced apart from each other at a predetermined interval in the circumferential direction of the cylinder block 8 around the rotating shaft 5. It extends in the axial direction. One end of each cylinder 9 opens to the end face of the cylinder block 8, and cylinder ports 9A, 9A,... Are formed on the other end.

  .. Are a plurality of pistons slidably fitted in the respective cylinders 9, and shoes 11 are swingably provided on the distal ends of the pistons 10 protruding from the respective cylinders 9. . Each shoe 11 is supported by a shoe presser 12 so as to be in sliding contact with a sliding surface 13B of a swash plate 13 described later.

  Reference numeral 13 denotes a swash plate provided in the casing 1 in an inclined state with respect to the rotary shaft 5, and the swash plate 13 is a hollow circle having a shaft insertion hole 13A through which the rotary shaft 5 is inserted. An annular sliding surface 13 </ b> B on which each shoe 11 is slidably contacted is provided on the surface of the swash plate 13 that faces the cylinder block 8. Each shoe 11 slides on the sliding surface 13 </ b> B of the swash plate 13 so as to draw a circular path, and reciprocates the piston 10 along the cylinder 9.

  14 is a valve plate fixed to the lid 4 and provided in the casing 2. The valve plate 14 includes supply and discharge passages 4A and 4B of the casing 2 (lid 4) and cylinder ports 9A of the cylinders 9. A pair of supply / discharge ports (not shown) for intermittently communicating between the two are formed.

  When the rotating shaft 5 and the cylinder block 8 are rotated by a rotation source (not shown) such as an engine, the shoe 11 provided on the tip side of each piston 10 is circular on the sliding surface 13B of the swash plate 13. The piston 10 slides so as to draw a trajectory, and the piston 10 is reciprocated along the cylinder 9. As a result, the swash plate hydraulic pump 1 draws hydraulic oil into the cylinder 9 from the supply / discharge passages 4A and 4B via the supply / discharge port of the valve plate 14 and the cylinder port 9A, and pressurizes the hydraulic oil by the piston 10. Thus, high pressure oil is discharged through the cylinder port 9A, the supply / discharge port of the valve plate 14 and the supply / discharge passages 4A, 4B.

  As described above, when the swash plate hydraulic pump 1 is operated, the shoe 11 provided on each piston 10 always slides on the sliding surface 13 </ b> B of the swash plate 13. For this reason, the sliding surface 13B of the swash plate 13 is subjected to a quenching process using a laser quenching method to be described later. Hereinafter, a laser quenching method for the sliding surface 13B of the swash plate 13 will be described with reference to FIGS. This will be described with reference to FIG.

  In the figure, reference numeral 21 denotes a workpiece rotating device, and the workpiece rotating device 21 is roughly constituted by a motor 22 and a work table 24 (described later) that is rotationally driven by the motor 22. Here, the motor 22 is fixed to a base (not shown), and a pulley 23 is attached to the output shaft 22A.

  Reference numeral 24 denotes a work table that is rotationally driven by the motor 22. The work table 24 is formed using a material having high thermal conductivity such as copper, and is rotatably supported on a base (not shown). . A swash plate 13 as a work is detachably fixed to the upper end side of the work table 24 with the sliding surface 13B facing upward.

  On the other hand, a pulley 25 is attached to the lower end side of the work table 24, and a timing belt 26 is wound around the pulley 25 and a pulley 23 provided on the motor 22. A coolant passage (not shown) through which a cooling medium such as water flows is provided inside the work table 24, and a swash plate fixed to the work table 24 by circulating the cooling medium through the coolant passage. 13 is cooled.

  The work table 24 is rotated in the direction indicated by the arrow R around the axis OO together with the swash plate 13 by the rotation of the motor 22 being transmitted by the timing belt 26.

  A laser irradiation device 27 irradiates a laser beam 29 (described later) toward the swash plate 13 rotated by the work table 24. The laser irradiation device 27 includes a laser oscillator 28, a first bend mirror 31, a segment mirror 33, a second bend mirror 36, and the like, which will be described later.

Reference numeral 28 denotes a laser oscillator. The laser oscillator 28 is constituted by an oscillator such as a CO ₂ laser, a YAG laser, or a semiconductor laser, and oscillates a laser beam 29. The laser beam 29 oscillated by the laser oscillator 28 is emitted toward a first bend mirror 31 described later.

  Reference numeral 30 denotes a housing having an entrance 30A and an exit 30B for the laser beam 29. In the housing 30, a first bend mirror 31, a segment mirror 33, a second bend mirror 36, and the like are arranged. ing.

  Reference numeral 31 denotes a first bend mirror, and the bend mirror 31 is attached to a mirror mount 32 disposed in the vicinity of the entrance 30 </ b> A of the housing 30. The bend mirror 31 reflects the laser beam 29 introduced into the housing 30 through the entrance 30 </ b> A and guides it to the segment mirror 33. The mirror mount 32 is attached to the housing 30 so that the position thereof can be adjusted, and the reflection direction of the laser beam 29 by the bend mirror 31 can be appropriately adjusted toward the segment mirror 33.

  Reference numeral 33 denotes a segment mirror, and the segment mirror 33 is constituted by an assembly of a large number of plane mirrors 33A, 33A,... Individually attached to a mirror mount 34 as shown in FIG. Here, each plane mirror 33A is attached to the mirror mount 34 via a spherical joint or the like (not shown) so that the position thereof can be adjusted, and the angle of each plane mirror 33A can be adjusted appropriately. Yes.

  The segment mirror 33 adjusts the angle of each plane mirror 33A to adjust the laser beam 29 output from the laser oscillator 28 to a laser beam having an arbitrary spot shape and intensity distribution, and this adjusted laser. The beam 35 is reflected toward a bend mirror 36 described later. The mirror mount 34 is attached to the housing 30 so that the position thereof can be adjusted, and the reflection direction of the adjustment laser beam 35 by the segment mirror 33 can be appropriately adjusted toward the bend mirror 36.

  Reference numeral 36 denotes a second bend mirror, and the bend mirror 36 is attached to a mirror mount 37 disposed in the vicinity of the exit 30 </ b> B of the housing 30. The bend mirror 36 reflects the adjustment laser beam 35 reflected by the segment mirror 33 and guides it to the swash plate 13 fixed to the work table 24 of the work rotating device 21 through the emission port 30B of the housing 30. It is. The mirror mount 37 is attached to the housing 30 so that the position thereof can be adjusted, and the reflection direction of the laser beam 29 by the bend mirror 36 can be appropriately adjusted toward the sliding surface 13B of the swash plate 13. .

  Each of the above-described mirror mounts 32, 34, and 37 includes a cooling mechanism that cools the mirror by circulating a cooling medium, and a fog prevention mechanism that prevents the mirror from fogging by blowing dry air toward the mirror. (Both not shown) are provided.

  The laser beam 29 output from the laser oscillator 28 is reflected by the bend mirror 31 in the housing 30 and is incident on the segment mirror 33. When the laser beam 29 is reflected from the segment mirror 33 to the bend mirror 36, the adjustment laser is used. It is adjusted to the beam 35. Then, the adjustment laser beam 35 reflected from the segment mirror 33 toward the bend mirror 36 is reflected by the bend mirror 36, whereby the sliding surface of the swash plate 13 fixed to the work table 24 of the work rotating device 21. Focus on 13B.

  At this time, since the swash plate 13 rotates together with the work table 24 in the direction indicated by the arrow R about the axis OO, the sliding surface 13B of the swash plate 13 is heated in an annular shape by the adjusting laser beam 35. In addition, an annular quenching region 38 indicated by a two-dot chain line in FIG. 4 is formed on the sliding surface 13B.

Here, regarding the beam spot 35 ′ of the adjustment laser beam 35 condensed on the sliding surface 13 B of the swash plate 13, this beam spot 35 ′ adjusts the angle of each plane mirror 33 A constituting the segment mirror 33. Thereby, it is formed in a substantially trapezoidal shape as shown in FIG. The beam spot 35 ′ has a spot shape extending from the inner peripheral side to the outer peripheral side of the quenching region 38 as indicated by hatching in FIG. 4, and is formed on the outer peripheral side and the inner peripheral side of the quenching region 38. Irradiated at the same time. In this case, the beam spot 35 ′ is formed in a trapezoidal shape in which the width dimension A on the outer peripheral side of the quenching region 38 is larger than the width dimension B on the inner peripheral side of the quenching region 38 (A> B).

  On the other hand, regarding the intensity distribution of the adjustment laser beam 35 irradiated on the sliding surface 13B of the swash plate 13, the intensity of the adjustment laser beam 35 is changed from the inner periphery side to the outer periphery side of the quenching region 38 as shown in FIG. It is set almost uniformly over the range.

  Accordingly, in a state where the adjustment laser beam 35 is irradiated on the sliding surface 13B of the swash plate 13, the swash plate 13 is rotated in the direction indicated by the arrow R about the axis OO, and the sliding surface 13B of the swash plate 13 is moved to the sliding surface 13B. By forming the annular quenching region 38, the amount of heat input on the inner peripheral side of the quenching region 38 with a long irradiation time of the adjustment laser beam 35 is suppressed to a small value, and the outer periphery of the quenching region 38 with a short irradiation time of the adjustment laser beam 35 is shortened. The amount of heat input at the side can be increased.

  Next, an operation of forming the annular quenching region 38 on the sliding surface 13B of the swash plate 13 by the laser quenching method using the workpiece rotating device 21 and the laser irradiation device 27 described above will be described.

  First, the swash plate 13 is fixed to the work table 24 of the work rotation device 21 with the sliding surface 13B facing upward. Then, by operating the motor 22 and rotating the work table 24, the swash plate 13 is rotated in the direction indicated by the arrow R about the axis OO.

  On the other hand, the laser irradiation device 27 outputs a laser beam from the laser oscillator 28, reflects the laser beam 29 from the first bend mirror 31 toward the segment mirror 33, and the segment mirror 33 generates an arbitrary spot shape. Adjustment (processing) is performed to an adjustment laser beam 35 having an intensity distribution. The adjusted laser beam 35 adjusted by the segment mirror 33 is reflected by the second bend mirror 36 and then irradiated to the sliding surface 13B of the swash plate 13 fixed to the work table 24.

  Therefore, the swash plate 13 is heated in an annular shape by the adjustment laser beam 35 by being irradiated with the adjustment laser beam 35 while rotating in the direction indicated by the arrow R about the axis OO. As a result, as indicated by a two-dot chain line in FIG. 4, an annular quenching region 38 is formed on the sliding surface 13 </ b> B of the swash plate 13.

  Then, for example, a cooling medium such as water (not shown) is circulated through a coolant passage provided in the work table 24 to cool the heated swash plate 13, thereby laser on the sliding surface 13 </ b> B of the swash plate 13. The quenching operation is completed.

  Here, when the annular quenching region 38 is formed on the sliding surface 13B of the swash plate 13 by irradiating the rotating swash plate 13 with the adjustment laser beam 35, the irradiation time of the adjustment laser beam 35 on the swash plate 13 is as follows. The outer periphery side of the quenching region 38 is shortened and the inner periphery side of the quenching region 38 is lengthened.

  On the other hand, in the present embodiment, the beam spot 35 ′ of the adjustment laser beam 35 irradiated on the sliding surface 13 B of the swash plate 13 has a large width dimension A on the outer peripheral side of the quenching region 38, and It is formed in a trapezoidal shape with a small width B on the inner peripheral side.

  Thus, when the annular quenching region 38 is formed on the sliding surface 13B of the swash plate 13, the amount of heat input on the inner peripheral side of the quenching region 38 with a long irradiation time of the adjustment laser beam 35 is suppressed, and the adjustment laser is reduced. The amount of heat input on the outer peripheral side of the quenching region 38 with a short irradiation time of the beam 35 can be increased. Therefore, the inner peripheral side and the outer peripheral side of the quenching region 38 can be heated substantially uniformly by the adjustment laser beam 35.

  As a result, the annular quenching region 38 formed on the sliding surface 13B of the swash plate 13 is evenly quenched over the entire region, so that as shown in FIG. A hard quenching layer 39 having a substantially equal quenching depth T from the inner periphery side to the outer periphery side can be formed in the vicinity.

  Next, FIGS. 7 and 8 show a second embodiment of the present invention. The feature of the present embodiment is that the intensity distribution of the laser beam irradiated to the workpiece is changed to the outer circumference than the inner circumference side of the quenching region. The side is set to be larger. In the present embodiment, the same components as those in the first embodiment described above are denoted by the same reference numerals, and the description thereof is omitted.

  In the figure, reference numeral 41 denotes an adjustment laser beam irradiated to the sliding surface 13B of the swash plate 13, and the adjustment laser beam 41 is output from the laser oscillator 28 of the laser irradiation apparatus 27 used in the first embodiment. The laser beam 29 is adjusted to a laser beam having an arbitrary spot shape and intensity distribution using the segment mirror 33.

  Here, regarding the beam spot 41 ′ of the adjustment laser beam 41 condensed on the sliding surface 13 B of the swash plate 13, the beam spot 41 ′ adjusts the angle of each plane mirror 33 A constituting the segment mirror 33. As a result, as shown in FIG. 7, the hardened region 38 is formed in a rectangular shape having the same width dimension C on the inner peripheral side and outer peripheral side and a length dimension D larger than the width dimension C.

  On the other hand, regarding the intensity distribution of the adjustment laser beam 41 applied to the sliding surface 13B of the swash plate 13, the intensity of the adjustment laser beam 41 is small on the inner peripheral side of the quenching region 38, as shown in FIG. It is set to gradually increase toward the outer peripheral side of the quenching region 38.

  Accordingly, when the swash plate 13 is rotated in the direction indicated by the arrow R about the axis OO, the sliding surface 13B of the swash plate 13 is irradiated with the adjustment laser beam 41 to form the annular quenching region 38. The amount of heat input on the inner peripheral side of the quenching region 38 with a long irradiation time of the adjusting laser beam 41 can be suppressed to a small value, and the amount of heat input on the outer peripheral side of the quenching region 38 with a short irradiation time of the adjusting laser beam 41 can be increased. It can be done.

  In the laser hardening method according to the present embodiment, the beam spot 41 ′ of the adjustment laser beam 41 irradiated on the sliding surface 13 </ b> B of the swash plate 13 has a rectangular shape, and the intensity distribution of the adjustment laser beam 41 is changed to the hardening region 38. It is set so that it is small on the inner peripheral side and gradually increases toward the outer peripheral side of the quenching region 38.

  Thus, when the annular laser beam 41 is formed by irradiating the sliding surface 13B of the swash plate 13 with the adjusting laser beam 41 while rotating the swash plate 13, the quenching region having a long irradiation time of the adjusting laser beam 41 is formed. The amount of heat input on the inner peripheral side of 38 can be reduced, and the amount of heat input on the outer peripheral side of the quenching region 38 with a short irradiation time of the adjustment laser beam 41 can be increased. Can be heated substantially uniformly by the adjustment laser beam 41.

  As a result, the annular quenching region 38 formed on the sliding surface 13B of the swash plate 13 is evenly quenched over the entire region, so that as shown in FIG. A hard quenching layer 39 having a substantially equal quenching depth T from the inner periphery side to the outer periphery side can be formed in the vicinity.

  Next, FIG. 9 shows a third embodiment of the present invention. The feature of this embodiment is that the amount of heat input of the laser beam irradiated to the quenching region is set by a diffractive lens provided in the laser irradiation apparatus. There is to do. In the present embodiment, the same components as those in the first embodiment described above are denoted by the same reference numerals, and the description thereof is omitted.

  In the figure, reference numeral 51 denotes a laser irradiation apparatus used in the present embodiment in place of the laser irradiation apparatus 27 according to the first embodiment. The laser irradiation apparatus 51 includes a laser oscillator 28 and a diffractive lens 53 described later. The condenser lens 55 and the like are generally configured.

  Reference numeral 52 denotes a housing having an entrance 52A and an exit 52B for the laser beam 29. In the housing 52, a diffractive lens 53, a condenser lens 55, and the like are arranged.

  Reference numeral 53 denotes a diffractive lens. The diffractive lens 53 is attached to a lens holder 54 disposed in the vicinity of the entrance 52A of the housing 52. Here, the diffractive lens 53 can freely modulate the phase of the light by a fine uneven pattern formed on the surface thereof, and the laser beam 29 output from the laser oscillator 28 is, for example, the first embodiment. The adjustment laser beam 35 is adjusted (processed) in the same manner as in the embodiment, and this adjustment laser beam 35 is irradiated onto the sliding surface 13B of the swash plate 13.

  Reference numeral 55 denotes a condensing lens, and the condensing lens 55 is attached to a lens holder 56 disposed in the vicinity of the emission port 52 </ b> B of the housing 52. The condensing lens 55 condenses the adjustment laser beam 35 that has passed through the diffractive lens 53 on the sliding surface 13B of the swash plate 13 fixed to the work table 24 of the work rotating device 21.

  The laser irradiation device 51 used in the present embodiment includes the diffractive lens 53 as described above, and the laser beam 29 output from the laser oscillator 28 is combined with the adjustment laser beam 35 while passing through the diffractive lens 53. Become. Then, after passing through the condenser lens 55, the adjustment laser beam 35 is applied to the sliding surface 13B of the swash plate 13 fixed to the work table 24 of the work rotating device 21, and the table is placed on the sliding surface 13B. A shaped beam spot 35 'is formed.

  Thus, as in the first embodiment described above, when the annular quenching region 38 is formed on the sliding surface 13B of the swash plate 13, the quenching region where the irradiation time of the adjustment laser beam 35 on the swash plate 13 is long. The amount of heat input on the inner peripheral side of the laser beam can be reduced, and the amount of heat input on the outer peripheral side of the quenching region where the irradiation time of the adjustment laser beam 35 is short can be increased.

  Therefore, also in the present embodiment, uniform quenching can be performed over the entire area of the annular quenching region formed on the sliding surface 13B of the swash plate 13, and in the vicinity of the sliding surface 13B of the swash plate 13. A hard quenching layer having a substantially equal quenching depth can be formed in the region from the inner circumference side to the outer circumference side.

  In the first embodiment described above, the laser beam 29 is irradiated from the laser irradiation device 27 toward the sliding surface 13B of the swash plate 13 while the swash plate 13 is rotated by the work table 24. is doing. However, the present invention is not limited to this. For example, the swash plate 13 is fixed, and the entire laser irradiation device 27 is rotated with respect to the swash plate 13, and the sliding surface of the swash plate 13 from the laser irradiation device 27. You may make it irradiate the laser beam 29 toward 13B. The same applies to the second and third embodiments.

  Moreover, in each embodiment mentioned above, the swash plate 13 used for the swash plate type hydraulic pump 1 is illustrated as a workpiece | work to which a laser hardening process is performed. However, the present invention is not limited to this, and can be widely applied to members having a circular or annular quenching region such as a shoe used in a swash plate type hydraulic pump, a valve seat on which a valve body is seated and detached.

It is a longitudinal cross-sectional view which shows the swash plate type hydraulic pump provided with the swash plate with which the laser hardening method which concerns on this invention is applied. It is an external view which shows the workpiece | work rotation apparatus and laser irradiation apparatus which are used for 1st Embodiment. It is a perspective view which shows the segment mirror in FIG. It is the top view which looked at the beam spot shape of the adjustment laser beam by 1st Embodiment from the arrow IV-IV direction in FIG. It is a characteristic diagram which shows the relationship between the intensity | strength of the adjustment laser beam by 1st Embodiment, and a hardening area | region. It is sectional drawing which shows the swash plate in which the hardening layer was formed by the laser beam. It is a top view similar to FIG. 4 which shows the beam spot shape of the adjustment laser beam by 2nd Embodiment. It is a characteristic diagram which shows the relationship between the intensity | strength of the adjustment laser beam and quenching area | region by 2nd Embodiment. It is the same external view as FIG. 2 which shows the workpiece | work rotation apparatus and laser irradiation apparatus which are used for 3rd Embodiment.

Explanation of symbols

13 Swash plate (work)
13B Sliding surface 21 Work rotating device 27, 51 Laser irradiation device 28 Laser oscillator 29 Laser beam 33 Segment mirror 35, 41 Adjusted laser beam 38 Hardened region 35 ', 41' Beam spot 39 Hardened layer 53 Diffractive lens

Claims (5)

A laser quenching method in which a laser beam is irradiated from the laser irradiation device toward the workpiece while relatively rotating a laser irradiation device that irradiates a laser beam and the workpiece, and a circular or annular quenching region is formed on the workpiece. In
The laser beam has a spot shape that extends from the inner peripheral side to the outer peripheral side of the quenching region, and simultaneously irradiates the outer peripheral side and the inner peripheral side of the quenching region,
The laser quenching method according to claim 1, wherein a heat input amount of the laser beam irradiated to the outer peripheral side of the quenching region is set larger than a heat input amount of the laser beam irradiated to the inner peripheral side of the quenching region.   2. The laser hardening method according to claim 1, wherein the spot shape of the laser beam applied to the workpiece is set so that an outer peripheral side of the quenching region is large and an inner peripheral side of the quenching region is small.   The laser hardening method according to claim 1, wherein an intensity distribution of the laser beam applied to the workpiece is set larger on an outer peripheral side than on an inner peripheral side of the quenching region.   4. The laser quenching method according to claim 1, wherein the heat input amount of the laser beam irradiated to the quenching region is set by a segment mirror provided in the laser irradiation apparatus.   4. The laser hardening method according to claim 1, wherein the heat input amount of the laser beam irradiated to the quenching region is set by a diffractive lens provided in the laser irradiation device.

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