JP6565114B2 - Curing processing method and curing processing apparatus for member to be processed - Google Patents

Description

  The present invention relates to a curing method and a curing apparatus for a member to be processed, in which a surface to be processed having a curved shape of the member to be processed is irradiated with a laser beam to form a cured layer.

In a steam turbine, erosion wear tends to occur at a leading edge portion on the steam inlet side of a turbine low-pressure stage blade (simply referred to as a turbine blade) due to collision of vaporized steam.
As a technique for reducing this erosion wear, a technique for improving the erosion resistance of the front edge by performing a curing process using a flame torch or high frequency induction heating on the front edge that is eroded by erosion is known. Yes.

However, the hardening process of the leading edge by the flame torch is difficult to accurately control the heat input to the turbine blade, and there is a possibility that the hardness may vary. Moreover, the hardening process of the front edge part by high frequency induction heating has the problem that it is necessary to manufacture coils suitable for various turbine blade shapes and the manufacturing cost is high.
On the other hand, for example, the hardening process of the front edge portion by laser beam irradiation described in Patent Document 1 is easy to manage heat input and can be finely processed, and can follow various turbine blade shapes. And the problem of the hardening process of the front edge part by high frequency induction heating can be solved.

JP2013-209912A

However, in recent years, as the efficiency of the steam turbine increases, the curved surface shape and thickness change as the position of the turbine blades becomes the tip, and the heat capacity changes, so that the amount of heat required for the curing process differs depending on the position.
Further, the stainless steel used for the turbine blades may be melted or precipitate an abnormal metal structure due to overheating during the hardening process, resulting in a decrease in hardness, which may lead to deterioration in erosion resistance.

Thus, in order to obtain a hardened layer that is equivalent in any position of the turbine blade and has high erosion resistance, heat input management by temperature control is essential. However, the radiation thermometer used as a general temperature measurement for temperature control cannot accurately measure the temperature because the emissivity fluctuates due to the heating of the surface of the metal material. Since control is difficult, a hardened layer with high erosion resistance cannot be formed.
Therefore, the present invention has been made in view of the above circumstances, and it is possible to measure the temperature of a laser spot with high accuracy based on the intensity of thermal radiation emitted from the laser spot on the processing surface irradiated with the laser beam. Then, it aims at providing the hardening processing method and hardening processing apparatus of the to-be-processed member which can form a high quality and high-depth hardened layer in a to-be-processed surface.

  In order to achieve the above object, a method for curing a member to be processed according to an aspect of the present invention includes irradiating a surface to be processed having a curved shape of a member to be processed with a laser beam to form a laser spot. When forming a hardened layer on the processing surface, scan the direction along the curved surface of the laser spot to measure the thermal radiation light at a plurality of measurement positions, for each of the thermal radiation light at the plurality of measurement positions, Each temperature at the plurality of measurement positions is calculated by dividing the spectrum into two spectral heat radiation lights having different wavelengths, and obtaining a ratio of the intensity of the two spectral heat radiation lights, and one of the temperatures at the plurality of measurement positions is calculated. The highest value was set to the maximum temperature of the laser spot, and the laser output value of the laser beam was controlled so that the maximum temperature of the laser spot approached the target maximum temperature.

In order to achieve the above object, a processing apparatus for processing a member according to one embodiment of the present invention includes a laser irradiation apparatus that irradiates a processing surface having a curved shape of a processing member with a laser beam, and the processing surface. A thermal radiation measurement unit that measures the intensity of the thermal radiation emitted from the laser spot of the formed laser beam, and the laser irradiation device receives the laser beam based on information output from the thermal radiation measurement unit. A control unit that outputs a laser output value, and the thermal radiation measurement unit has a wavelength different from that of the condensing unit that collects the thermal radiation emitted from the laser spot. A beam splitter that splits the light into two spectral thermal radiations, and two photosensors that measure the intensity of the two spectral thermal radiations, and the control unit measures the two photosensors. The temperature calculation unit that calculates the maximum temperature of the laser spot based on the ratio of the intensity of the two spectral heat radiations is compared with the maximum temperature of the laser spot calculated by this temperature calculation unit and the preset target maximum temperature. An output value changing unit that changes the laser output value of the laser beam irradiated by the laser irradiation apparatus so that the maximum temperature of the laser spot approaches the target maximum temperature, and the thermal radiation measurement The unit includes a scanner unit that scans the laser spot in a direction along the curved surface, and the temperature calculation unit scans the thermal radiation light at a plurality of measurement positions in the direction along the curved surface of the laser spot by scanning the scanner unit. Measure the temperature at each of the plurality of measurement positions based on the ratio of the intensity of the two spectral heat radiation light to each of the heat radiation light at the plurality of measurement positions. Out, the highest value among the temperatures of the plurality measurement positions, the maximum temperature of the laser spot.

  According to the method and apparatus for curing a member to be treated according to the present invention, the temperature of the laser spot is accurately determined based on the intensity of the thermal radiation emitted from the laser spot on the surface to be treated irradiated with the laser beam. By measuring, a hardened layer having a high quality and a high depth can be formed on the surface to be processed.

It is a figure explaining the operation | movement which irradiates a laser beam to the front edge part of the turbine blade which concerns on this invention, and forms a hardened layer. It is a figure which shows the structure of the hardening processing apparatus of 1st Embodiment which concerns on this invention. It is a figure which shows the thermal radiation light detector which comprises the hardening processing apparatus of 1st Embodiment. It is a figure which shows the structure of the scanner part of the thermal radiation light detector of 1st Embodiment. It is a figure which shows the structure of the control apparatus which comprises the hardening processing apparatus of 1st Embodiment. It is a figure which shows operation | movement of the thermal radiation light detector of 1st Embodiment. It is a figure which shows the structure of the thermal radiation light detector of 2nd Embodiment which concerns on this invention. It is a figure which shows operation | movement of the thermal radiation light detector of 2nd Embodiment.

DESCRIPTION OF EMBODIMENTS Hereinafter, modes for carrying out the present invention (hereinafter referred to as embodiments) will be described in detail with reference to the drawings.
[First Embodiment: Turbine Blade Curing Treatment Device]
Reference numeral 1 in FIG. 1 denotes a turbine low-pressure stage blade (abbreviated as a turbine blade) that constitutes a steam turbine, and erosion wear is caused by the dropletized steam colliding with the front edge portion 2 of the turbine blade 1. Prone to occur.
FIG. 2 is a turbine blade hardening processing apparatus according to the first embodiment of the present invention that forms a hardened layer on the front edge portion 2 by irradiating the front edge portion 2 of the turbine blade 1 with a laser beam.

The turbine blade curing apparatus according to the first embodiment includes a laser generator 3, a laser irradiation head 4, a thermal radiation light detector 5, and a control device 6.
The laser generator 3 generates a laser beam 7 irradiated on the surface of the front edge portion 2 of the turbine blade 1, and is composed of a semiconductor laser having oscillation wavelengths of 940 nm ± 10 nm and 980 nm ± 10 nm, for example. .

The laser irradiation head 4 irradiates the surface of the front edge portion 2 with the laser beam 7 generated by the laser generator 3, and the laser beam 7 reflected by the surface of the front edge portion 2 of the steam turbine blade 1 is incident thereon. In order to prevent this, the laser beam 7 is disposed at a position where the laser beam 7 is inclined with respect to the surface of the front edge portion 2 of the turbine blade 1.
The laser irradiation head 4 is connected to a movement drive device (not shown), and can be moved in a feed direction (a direction perpendicular to the paper surface in FIG. 2) from the front end 2a of the front edge 2 shown in FIG. 1 toward the base end 2b. By irradiating the surface of the front edge portion 2 with the laser beam 7, the laser spot 8 is continuously formed from the front end 2a of the front edge portion 2 to the base end side 2b.

The thermal radiation detector 5 is connected to the laser irradiation head 4 via a connecting member 9 and moves in the feed direction together with the laser irradiation head 4 by a movement drive device.
As shown in FIG. 3, the thermal radiation detector 5 is different from the condenser 10 that collects the thermal radiation B emitted from the laser spot 8 and the thermal radiation B collected by the condenser 10. A beam splitter 11 that splits into two spectral heat radiation beams Ba and Bb having wavelengths (1300 nm and 1550 nm), and two photosensors 12 and 13 that measure the energy (intensity) of the two spectral heat radiation beams Ba and Bb, The optical axis adjustment mechanisms 14 and 15 provided between the beam splitter 11 and the photosensors 12 and 13 are provided.

  The condensing unit 10 includes optical systems such as mirrors 16 to 19 and a diaphragm 20 that condense the thermal radiation light B emitted from the laser spot 8 toward the beam splitter 11. Here, as shown in FIG. 4, the mirror 17 can be rotated around a rotation shaft 17a disposed on the back side of the mirror, and a predetermined direction in a forward / reverse direction from a rotation drive source (not shown) to the rotation shaft 17a. When the rotational force of the rotational angle is transmitted, the mirror 17 swings to the angle indicated by the broken line in FIG. 4 (hereinafter referred to as the swing mirror 17).

As shown in FIG. 1, the oscillating operation of the oscillating mirror 17 causes the measurement position from the measurement position L crossing the laser spot 8 with the direction (width direction) along the curved surface of the front edge portion 2 of the turbine blade 1 as the scanning direction. Thermal radiation light B at the measurement position up to R is condensed on the condensing unit 10.
The optical axis adjustment mechanisms 14 and 15 are mechanisms for adjusting the optical axes so that the spectral heat radiation Ba and Bb from the beam splitter 11 toward the photosensors 12 and 13 are directed to the measurement spots of the photosensors 12 and 13. is there.

As shown in FIG. 5, the control device 6 includes an input port 21, an arithmetic processing unit 22, and an output port 23.
The energy (intensity) Me _{A of the} spectral heat radiation light Ba and the energy (intensity) Me _{B of the} spectral heat radiation light Bb are input to the input port 21. Here, when the oscillating mirror 17 performs the oscillating operation, the energy (intensity) Me _{A of the} spectral thermal radiation light Ba and the energy (intensity) Me _{B of the} spectral thermal radiation light Bb in the direction along the curved surface of the laser spot 8. Is input to the input port 21.

The arithmetic processing unit 22 includes a ROM (Read Only Memory) 24 and a RAM (Random Access Memory) 25. The arithmetic processing unit 22 may include a ROM 24 and a RAM 25 built-in, or a ROM 24 and a RAM 25 externally connected by a path.
The ROM 24 includes a maximum temperature setting unit 26 that calculates the maximum temperature of the laser spot 8 and a laser output value setting unit 27 that calculates the optimum value of the laser output value of the laser generator 3 corresponding to the maximum temperature of the laser spot 8. It is remembered.
The RAM 22 is provided with an area for accumulating calculation values and intermediate data used in the calculations of the maximum temperature setting unit 26 and the laser output value setting unit 27.
The output port 23 outputs the laser output value LS calculated by the laser output value setting unit 27 to the laser generator 3.

Next, the procedure in which the maximum temperature setting unit 26 of the ROM 24 calculates the maximum temperature of the laser spot 8 will be described.
The maximum temperature setting unit 26 first crosses the laser spot 8 in the direction (width direction) along the curved surface of the front edge portion 2 of the turbine blade 1 shown in FIG. While scanning from the measurement position L to the measurement position R (or from the measurement position R to the measurement position L), the energy (intensity) Me _{A of the} spectral heat radiation light Ba input from the photosensors 12 and 13 via the input port 21. The energy (intensity) Me _A and Me _B for each predetermined measurement time is read out of the energy (intensity) Me _B of the spectral heat radiation light Bb.

ε：放射率
α_Ａ：分光熱放射光Ｂａの測定光学系の受光特性係数
λ_Ａ：分光熱放射光Ｂａの波長（１３００nm）
Ｃ１：定数
Ｃ２：定数
Ｔ：温度 Here, the relational expression between the energy (intensity) Me _A [W / m ² ] of the spectral heat radiation light Ba and the temperature T [° K] can be expressed by the following expression (1) based on Planck's radiation law. it can.

ε: Emissivity α _A : Light receiving characteristic coefficient of measurement optical system of spectral heat radiation light Ba λ _A : Wavelength (1300 nm) of spectral heat radiation light Ba
C1: Constant C2: Constant T: Temperature

ε：放射率
α_Ｂ：分光熱放射光Ｂｂの測定光学系の受光特性係数
λ_Ｂ：分光熱放射光Ｂｂの波長（１５５０nm）
Ｃ１：定数
Ｃ２：定数
Ｔ：温度 Further, the relational expression between the energy (intensity) Me _B [W / m ² ] of the spectral heat radiation light Bb and the temperature T [° K] can be expressed by the following expression (2) based on Planck's radiation law. .

ε: Emissivity α _B : Light receiving characteristic coefficient of measurement optical system of spectral thermal radiation Bb λ _B : Wavelength of spectral thermal radiation Bb (1550 nm)
C1: Constant C2: Constant T: Temperature

この（３）式の第１式の分母、分子に存在している放射率εは、分光熱放射光Ｂａ及び分光熱放射光Ｂｂの各波長によらない変数であり、（３）式の第２式のように消去される。 Then, when the above equation (1) is divided by the above equation (2), the following equation (3) is obtained.

The emissivity ε present in the denominator and numerator of the first formula of the equation (3) is a variable that does not depend on the wavelength of the spectral heat radiation light Ba and the spectral heat radiation light Bb. It is erased as shown in Formula 2.

Then, to calculate the ratio of the energy (intensity) Me _B of a predetermined measurement energy (intensity) of the frequency photothermal radiated light Ba loaded every time Me _A and minutes photothermal emitted light Bb _(Me A / Me _B), the emissivity The temperature T is calculated based on the second formula of the formula (3) in which ε is eliminated.
As described above, the direction (width direction) along the curved surface of the front edge portion 2 of the turbine blade 1 shown in FIG. 1 is measured from, for example, the measurement position L by the swing operation of the swing mirror 17 so as to cross the laser spot 8. While scanning up to the position R (or from the measurement position R to the measurement position L), the energy (intensity) Me _A and the energy (intensity) of the spectral heat radiation light Ba input from the photosensors 12 and 13. Me _B is read at every predetermined measurement time, and the temperature T is calculated at every predetermined measurement time, so that the direction along the curved surface of the front edge 2 of the turbine blade 1 (width direction), that is, along the curved surface of the laser spot 8 is met. Each temperature T at a plurality of measurement positions in the direction is determined.
The maximum temperature setting unit 26 sets the highest temperature among the temperatures T at the plurality of measurement positions as the maximum temperature T _MAX of the laser spot 8.

Next, the procedure in which the laser output value setting unit 27 of the ROM 24 calculates the optimum value of the laser output value of the laser generator 3 will be described.
The RAM 22, in advance, the material of the turbine blade 1, the area of the laser spot 8, the target maximum temperature T _P of the laser spot 8 in correspondence with the depth of the hardened layer is stored.
Laser output value setting unit 27 compares the maximum temperature T _MAX and the target maximum temperature T _P of the laser spot 8 set at the highest temperature setting unit 26, when the maximum temperature T _MAX is lower than the target maximum temperature T _P is calculates the laser output value LS of a value greater than the current value, the maximum temperature T _MAX is higher than the target maximum temperature T _P calculates the laser output value LS of the smaller value than the current value.

Next, the operation in which the turbine blade curing apparatus of the first embodiment forms a cured layer on the front edge portion 2 of the turbine blade 1 will be described.
The laser irradiation head 4 is disposed at the tip 2a of the front edge portion 2 of the turbine blade 1, and moves the laser irradiation head 4 at a predetermined speed in the feeding direction toward the base end side 2b by a moving drive device, and also emits heat radiation. The oscillating operation of the oscillating mirror 17 of the photodetector 5 is performed.
Here, after the laser irradiation head 4 moves in the feeding direction by the first feeding amount, the condensing unit 10 condenses the thermal radiation light B while scanning from the measurement position L to the measurement position R in FIG. Thus, after the oscillating mirror 17 performs the oscillating operation and the laser irradiation head 4 moves in the feeding direction by the second feeding amount, the condensing unit 10 scans from the measurement position R toward the measurement position L. However, the oscillating mirror 17 performs an oscillating operation so as to collect the heat radiation light B, and the movement drive device and the oscillating mirror 17 operate so as to repeat such an operation.

When the laser beam 7 generated by the laser generator 3 is irradiated from the laser irradiation head 4 to the surface of the front edge portion 2 of the turbine blade 1, the thermal radiation B emitted from the laser spot 8 is emitted from the oscillating mirror 17. By the swinging operation, the light is condensed on the condensing unit 10 while scanning in the direction along the curved surface of the laser spot 8.
The thermal radiation B condensed while scanning in the direction along the curved surface of the laser spot 8 is split into two spectral thermal radiations Ba and Bb having different wavelengths by passing through the beam splitter 11, and spectral thermal radiation. The intensity of Ba and Bb is measured by the two photosensors 12 and 13.

  Here, as shown in FIG. 6, the thermal radiation other than the measurement position also passes through the beam splitter 11 and is split as the spectral thermal radiation. Since an error occurs when the spectral heat radiation light other than the measurement position is measured by the photosensors 12 and 13, by operating the optical axis adjustment mechanisms 14 and 15, the spectral heat radiation of the thermal radiation light B at the measurement position. The optical axis is adjusted so that only the light Ba and Bb are directed to the measurement spots of the photosensors 12 and 13.

The control device 6 to which the intensities of the spectral heat radiation lights Ba and Bb are input from the two photosensors 12 and 13 eliminates the above-described emissivity ε by obtaining the ratio of the intensity of the spectral heat radiation lights Ba and Bb. The temperature T is calculated based on the second expression of the expression (3), and the highest temperature among the temperatures T at the plurality of measurement positions in the direction along the curved surface of the laser spot 8 is determined as the highest temperature T of the laser spot 8. Set to _MAX .

Then, the control unit 6 compares the maximum temperature _{T MAX} and the target maximum temperature _{T P,} the maximum temperature _{T MAX} sets the laser output value LS so as to approach the target maximum temperature _{T P.} Then, by outputting the laser output value LS from the control device 6 to the laser generator 3, a laser beam 7 corresponding to the laser output value LS is generated by the laser generator 3, and the laser irradiation head 4 and the front of the turbine blade 1. By irradiating the surface of the edge 2 with the laser beam 7, a hardened layer is formed on the front edge 2.

  The member to be treated according to the present invention corresponds to the turbine blade 1, the surface to be treated according to the present invention corresponds to the surface of the front edge portion 2, and the laser irradiation apparatus according to the present invention includes the laser generator 3 and the laser irradiation. It corresponds to the head 4, the thermal radiation measurement unit according to the present invention corresponds to the thermal radiation detector 5, the control unit according to the present invention corresponds to the control device 6, and the temperature calculation unit according to the present invention is the maximum temperature. The output value changing unit according to the present invention corresponds to the laser output value setting unit 27, and the scanner unit according to the present invention corresponds to the oscillating mirror 17.

Next, the effect of the turbine blade hardening processing apparatus of the first embodiment will be described.
The thermal radiation detector 5 scans the direction along the curved surface of the laser spot 8 to measure thermal radiation at a plurality of measurement positions, and the maximum temperature setting unit 26 of the control device 6 determines the temperature at the plurality of measurement positions. By setting the highest temperature T as the maximum temperature T _MAX of the laser spot 8, the maximum temperature T _MAX of the laser spot 8 having a curved surface shape can be measured with high accuracy.

Further, the maximum temperature setting unit 26 of the control device 6 separates the two spectral heat radiation beams Ba and Bb having different wavelengths when calculating the temperature T for each of the heat radiation light at the plurality of measurement positions, The temperature T is calculated based on the second equation of the above-described equation (3) by obtaining the intensity ratio (Me _A / Me _B ) of the two spectral thermal radiation beams Ba and Bb. Since the second equation (3) in which the emissivity ε whose value constantly changes due to changes in temperature, material, surface condition, etc. is used is calculated, the direction along the curved surface of the laser spot 8 is used. It is possible to measure each temperature T at a plurality of measurement positions with high accuracy.

The laser output value setting unit 27 of the control device 6 compares the maximum temperature T _MAX and the target maximum temperature T _P, the maximum temperature T _MAX sets the laser output value LS so as to approach the target maximum temperature T _P As a result, the laser beam 7 having the optimum output is irradiated from the laser irradiation head 4 to the surface of the front edge portion 2 of the turbine blade 1, so that the front edge portion 2 of the turbine blade 1 has high quality and high depth. The hardened layer can be formed.

Further, in the turbine blade curing apparatus of the first embodiment, the optical axis adjusting mechanisms 14 and 15 provided between the beam splitter 11 and the photosensors 12 and 13 have the spectral heat radiation of the thermal radiation light B at the measurement position. Since the optical axis is adjusted so that only the light Ba and Bb are directed to the measurement spots of the photosensors 12 and 13, the photosensors 12 and 13 have the energy (intensity) Me of the spectral heat radiation Ba and Bb at the measurement position. _A and Me _B can be measured with high accuracy. For this reason, the temperature T can be calculated with high accuracy based on the ratio of the energy (intensity) Me _A and Me _B of the spectral heat radiation light Ba and Bb.
In addition, when hardening the front edge part 2 of the steam turbine blade 1 using the turbine blade hardening processing apparatus shown in FIG. 2, in order to suppress the dispersion | variation in a laser absorptivity, the front edge part 2 of the steam turbine blade 1 is demonstrated. It is preferable to previously polish the surface with # 80 abrasive paper.

[Second Embodiment: Thermal Radiation Detection Unit]
Next, FIG. 7 shows the thermal radiation light detector 5 of the second embodiment constituting the turbine blade curing processing apparatus, and the thermal radiation light detector 5 shown in FIG. 7 is the same as that of the first embodiment. The turbine blade curing apparatus is provided in place of the thermal radiation detector 5 shown in FIG. In FIG. 7, the same components as those of the thermal radiation detector 5 shown in FIG.

  In the thermal radiation detector 5 of the second embodiment, a condenser lens 30 that condenses the thermal radiation light B reflected from the mirror 19 is disposed between the mirror 19 of the condenser 10 and the beam splitter 11. In addition, an optical fiber 31 through which the thermal radiation light B collected by the condenser lens 30 passes is disposed. The light is split into Bb.

Further, in the thermal radiation detector 5 of FIG. 3, the optical axis adjusting mechanisms 14 and 15 are provided between the beam splitter 11 and the photosensors 12 and 13, but the thermal radiation detector of the second embodiment is provided. 5 does not provide.
According to the thermal radiation detector 5 of the second embodiment, the thermal radiation B collected while scanning the direction along the curved surface of the laser spot 8 is reflected by the mirror 16, the oscillating mirror 17 of the condenser 10, After passing through the diaphragm 20 and the mirrors 18 and 19, the light is condensed by the condenser lens 30, and after passing through the optical fiber 31, the light is split into two spectral heat radiation beams Ba and Bb by the beam splitter 11.

Here, in the above-described first embodiment, in the thermal radiation detector 5 shown in FIG. 3, light other than the spectral thermal radiation Ba and Bb at the measurement position is photosensors depending on the adjustment positions of the photosensors 12 and 13. 12 and 13 may be detected. In that case, photo sensor 1
2 and 13, since the thermal radiation at different positions is detected, there is a possibility that the measured temperature T varies due to the deviation of the ratio of the energy (intensity) Me _A and Me _B of the spectral thermal radiation.

  On the other hand, in 2nd Embodiment, as shown in FIG. 8, by using the thermal radiation light detector 5 shown in FIG. 7 instead of the thermal radiation light detector 5 shown in FIG. Thermal radiation light other than the measurement position also passes through the diaphragm 20 and travels toward the beam splitter 11 side. However, the heat radiation light other than the measurement position is blocked at the entrance of the optical fiber 31, and only the heat radiation light B at the measurement position passes through the optical fiber 31 and is split by the beam splitter 11. Therefore, only the spectral heat radiation light Ba and Bb are directed to the measurement spots of the photosensors 12 and 13. That is, the optical fiber 31 functions as an optical path limiting element.

As described above, in the second embodiment, in the thermal radiation detector 5 shown in FIG. 7, the thermal radiation at the measurement position reflected from the mirror 19 between the mirror 19 and the beam splitter 11 of the condenser 10. By arranging the optical fiber 31 through which the light B passes, the heat radiation light other than the measurement position is blocked at the entrance of the optical fiber 31, and the photosensors 12 and 13 have the energy (intensity) of the spectral heat radiation Ba and Bb at the measurement position. ) Only Me _A and Me _B can be measured with high accuracy. In the second embodiment, the temperature T is calculated based on the ratio of the energy (intensity) Me _A and Me _B of the spectral heat radiation light Ba and Bb measured by the heat radiation light detector 5 shown in FIG. . For this reason, in the second embodiment, the temperature T can be calculated with higher accuracy than in the first embodiment.

Further, since the thermal radiation detector 5 of the second embodiment does not require the optical axis adjusting mechanisms 14 and 15 shown in FIG. 3, the apparatus cost can be reduced.
In the above-described embodiment, an example of a configuration that specifically targets the turbine blade as the member to be cured according to the present invention has been shown. However, the member to be cured according to the present invention is not limited to the turbine blade. Absent.

  In addition, the material of the member to be cured by the present invention is not particularly limited, but the present invention is preferably applied to a member to be treated made of a steel-based or titanium-based alloy material that is hardened by a specific heat treatment. Furthermore, the present invention can be particularly preferably applied to a member to be processed made of any one of ferritic stainless steel, martensitic stainless steel, and precipitation hardening stainless steel.

The present inventors use the above-described turbine blade hardening apparatus of the first embodiment, and under conditions of a control temperature of 1200 ° C. and a laser scanning speed of 1 mm / sec, ferritic stainless steel, martensitic stainless steel, and precipitation hardening system. The surface of the test piece made of any one material of stainless steel was irradiated with a laser beam for curing.
When the hardness of the cured layer of the test piece obtained by cutting the specimen subjected to the curing treatment in the thickness direction was measured with a hardness tester, the hardness was 450 Hv or more, and the cured depth of the cured layer was It was obtained over 6 mm. Here, the surface layer of the hardened layer is not melted.

In addition, the inventors investigated the area of the laser spot where the hardness of the cured layer is 450 Hv or more and the curing depth is 6 mm or more with respect to the above-described test piece.
As a result of the investigation, it was found that the area of the laser spot should be set to 600 mm ² or more in order to obtain a high hardness layer having a hardness of 450 Hv or more and a curing depth of 6 mm or more.
Therefore, when the surface of the front edge 2 of the turbine blade 1 is irradiated with the laser beam 7 and the front edge 2 is cured, the surface of the laser spot 8 is irradiated with the laser beam 7 having an area of 600 mm ² or more. A hardened layer having a thickness of 450 Hv or more and a hardening depth of 6 mm or more can be formed on the front edge 2 of the turbine blade 1, thereby extending the life of the turbine blade 1 against erosion wear. As a result, the maintenance-free turbine blade 1 can be obtained.

DESCRIPTION OF SYMBOLS 1 Turbine blade 2 Leading edge part 2a Tip 2b Base end side 3 Laser generator 4 Laser irradiation head 5 Thermal radiation light detector 6 Control apparatus 7 Laser beam 8 Laser spot 9 Connecting member 10 Condensing part 11 Beam splitter 12, 13 Photo Sensor 14.15 Optical axis adjusting mechanism 16, 18, 19 Mirror 17 Swing mirror 17a Rotating shaft 20 Aperture 21 Input port 22 Arithmetic processing unit 23 Output port 24 ROM
25 RAM
26 Maximum temperature setting unit 27 Laser output value setting unit 30 Condensing lens 31 Optical fiber B Thermal radiation light Ba, Bb Spectral thermal radiation light Me _A , Me _B Spectral thermal radiation energy (intensity)
LS Laser output value T Thermal radiation light temperature T _MAX maximum temperature _TP target maximum temperature

Claims (7)

When forming a laser spot by irradiating a processing surface having a curved shape of a processing target member with a laser beam, and forming a hardened layer on the processing surface,
Scan the direction along the curved surface of the laser spot to measure the thermal radiation at a plurality of measurement positions,
For each of the thermal radiation at the plurality of measurement positions, split into two spectral thermal radiations having different wavelengths,
By calculating the ratio of the intensity of these two spectral thermal radiation lights, each temperature at the plurality of measurement positions is calculated,
The highest value among the temperatures of the plurality of measurement positions is set as the maximum temperature of the laser spot,
A curing method for a member to be processed, characterized in that the laser output value of the laser beam is controlled so that the maximum temperature of the laser spot approaches the target maximum temperature. The member to be treated is a steam turbine blade having the surface to be treated as a surface of a front edge portion,
The direction from the front end of the front edge portion of the steam turbine blade toward the base end side is defined as a feed direction, and the laser spot is continuously formed along the feed direction. A method for curing a member to be treated. The hardened layer having a hardness of 450 Hv or more and a hardening depth of 6 mm or more is formed on the surface to be processed by irradiating a laser beam having an area of the laser spot of 600 mm ² or more. The method for curing a member to be treated according to claim 1 or 2.   The material to be treated is any one of ferritic stainless steel, martensitic stainless steel, and precipitation hardening stainless steel, and the material to be treated according to any one of claims 1 to 3. Curing method. A laser irradiation apparatus for irradiating a processing surface having a curved shape of a processing target member with a laser beam;
A thermal radiation measurement unit that measures the intensity of thermal radiation emitted from a laser spot of the laser beam formed on the surface to be treated;
A control unit that outputs a laser output value of the laser beam to the laser irradiation device based on information output by the thermal radiation measurement unit;
The thermal radiation measurement unit
A condensing unit that condenses the thermal radiation emitted from the laser spot;
A beam splitter that splits the condensed thermal radiation into two spectral thermal radiations of different wavelengths;
Two photosensors for measuring the intensity of the two spectral thermal radiation lights,
The controller is
A temperature calculator that calculates the maximum temperature of the laser spot based on a ratio of the intensity of the two spectral thermal radiations measured by the two photosensors;
The laser irradiated by the laser irradiation apparatus compares the maximum temperature of the laser spot calculated by the temperature calculation unit with a preset target maximum temperature, and the maximum temperature of the laser spot approaches the target maximum temperature. An output value changing unit for changing the laser output value of the beam ,
The thermal radiation measurement unit includes a scanner unit that scans a direction along the curved surface of the laser spot,
The temperature calculation unit measures thermal radiation at a plurality of measurement positions in a direction along the curved surface of the laser spot by scanning the scanner unit, and for each of the thermal radiation at the plurality of measurement positions, Each temperature of the plurality of measurement positions is calculated based on a ratio of the intensity of spectral thermal radiation, and the highest value among the temperatures of the plurality of measurement positions is set as the maximum temperature of the laser spot. An apparatus for curing a member to be processed. 6. The optical axis adjustment mechanism for adjusting the axial positions of the two spectral thermal radiation beams flowing from the beam splitter is provided in the two photosensors of the thermal radiation measurement unit. The to-be-processed member hardening processing apparatus. 6. The curing processing apparatus for a member to be processed according to claim 5 , wherein an optical fiber through which the thermal radiation emitted from the laser spot passes is provided on the way to the beam splitter of the thermal radiation measurement unit.

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