JP7049158B2 - Quenching quality judgment method - Google Patents

Description

The present invention relates to a quenching quality determination method for determining the quenching quality of an object to be quenched that has been quenched by an energy beam.

For example, in Patent Document 1, an energy beam is applied to a rotating quenched object, and the temperature of the hottest portion exceeds the austeniticization temperature while repeating heating and natural cooling of the hardened surface layer surface, and is the highest. A quenching method is disclosed in which the temperature of a portion to be low is heated to a state where the temperature is lower than the austeniticization temperature and higher than the martensitic transformation start temperature, and then the irradiation of the energy beam is stopped to cool the portion (FIG. 1 of Patent Document 1). 3, FIG. 4, [0007], [0019], [0020]).

Japanese Patent No. 5756745

According to Patent Document 1, since the temperature of the lowest temperature portion immediately before cooling in the cooling step due to the stop of irradiation of the energy beam exceeds the martensitic transformation start temperature, the austenite structure can be maintained and the quenching quality is good. Is disclosed that can be obtained.

However, the inventors of the present application have heat from adjacent or adjacent scanning lines before the scanning irradiation of the energy beam is completed during self-cooling by the quenching object in the cooling step on the scanning line where the scanning irradiation of the energy beam is completed. It has been found that there is a portion where tempering occurs due to reheating by propagation, and there is a problem that the desired quenching quality may not be achieved at the portion where tempering occurs.

The present invention has been made in consideration of such a problem, and makes it possible to determine the quenching quality of a portion where tempering has occurred due to reheating during self-cooling by an object to be quenched by a cooling step. It is an object of the present invention to provide a quality judgment method.

The quenching quality determination method according to the present invention is a quenching quality determination method for determining the quenching quality of an object to be quenched.
Quenching is performed in the main scanning direction by rotating the quenching object relative to the irradiated energy beam, and the quenching target is sequentially transferred in the sub-scanning direction orthogonal to the main scanning direction. When quenching the surface,
A measurement step for measuring the temperature history of the irradiation site of the energy beam for each main scanning direction, and a measurement step.
An acquisition step of acquiring a reheating tempering temperature point according to the rotation cycle for each temperature history of the irradiation site in each main scanning direction.
A determination step for determining the quenching quality of the quenching object based on the acquired reheat tempering temperature point, and
To prepare for.

According to the present invention, the reheated tempering temperature points according to the rotation cycle of the quenching object are acquired for each temperature history of the irradiation site in each main scanning direction constituting the quenching target surface, and the acquired reheating tempering is obtained. Since the quenching quality of the material to be quenched is determined based on the temperature point, after irradiating one irradiation site in the main scanning direction, the next irradiation site in which the sub-scanning directions are adjacent to each other at the same position in the main scanning direction. During the self-cooling of the object to be quenched up to, the heating of the next irradiation site causes reheating of the one irradiation site, and the quenching quality (pass / fail) of the site where tempering occurs due to the reheating is accurately determined. Can be determined.

In the acquisition step of acquiring the reheating tempering temperature point,
When the temperature of the self-cooling site at a predetermined position immediately before the irradiation site in each main scanning direction constituting the quenching target surface after quenching is lower than the martensitic transformation start temperature, and the position corresponding to the irradiation site. When the temperature of the self-cooling site in the above is above the martensitic transformation start temperature and reheated to a temperature within the temperature range lower than the austenitization temperature, it is determined to be the reheat tempering temperature point and obtained. May be good.

In this way, the temperature of the self-cooling site at a predetermined position immediately before the irradiation site in each main scanning direction constituting the quenching target surface after quenching is lower than the martensitic transformation start temperature, and corresponds to the irradiation site. Since it can be estimated that quenching occurs when the temperature of the self-cooling site at the position where the tempering occurs exceeds the martensitic transformation start temperature and is reheated to a temperature within the temperature range lower than the austenitic transformation temperature, the reheating tempering temperature point. It is possible to surely determine and acquire whether or not it is.

The predetermined position immediately before the irradiation site in each main scanning direction is a position before the irradiation site, which is far from the beam diameter at the irradiation site of the energy beam, and is self-cooled by the approach of the energy beam. By setting the position from to switching to reheating, it is possible to reliably obtain the reheating tempering temperature point on condition that the temperature at that position is lower than the martensitic transformation start temperature.

Further, in the determination step of determining the quenching quality of the quenching object, the quenching quality is determined.
The cumulative value obtained by weighting the reheating tempering temperature point by the carbon content of the quenching object and the irradiation time of the energy beam at the irradiation site is the target hardness for obtaining the desired quenching hardness. By determining that the quenching quality is acceptable in the range below the correspondingly set threshold value and the quenching quality is unacceptable in the range above the threshold value, the pass / fail determination can be accurately performed.

According to the present invention, the reheated tempering temperature points according to the rotation cycle of the quenching object are acquired for each temperature history of the irradiation site in each main scanning direction constituting the quenching target surface, and the acquired reheating tempering is obtained. Since the quenching quality of the material to be quenched is determined based on the temperature point, after irradiating one irradiation site in the main scanning direction, the next irradiation site in which the sub-scanning directions are adjacent to each other at the same position in the main scanning direction. During the self-cooling of the object to be quenched up to, the heating of the next irradiation site causes reheating of the one irradiation site, and the quenching quality (pass / fail) of the site where tempering occurs due to the reheating is accurately determined. Can be determined.

FIG. 1 is a schematic overall configuration diagram of a quenching quality determination system that implements the quenching quality determination method according to this embodiment. FIG. 2A is an explanatory diagram showing the arrangement of three spot thermometers that measure the temperatures at the upper end, the center, and the lower end at the irradiation site of the hardened cross section. FIG. 2B is an explanatory diagram showing the arrangement of three spot thermometers that measure the temperatures at the upper end, the center, and the lower end of the 45 ° front cross section from the quenching cross section. FIG. 3 is an explanatory diagram of the laser beam. FIG. 4 is an explanatory diagram showing an example in which the entire area such as a heated cross section is detected as a thermal image by thermography. It is a flow diagram provided for the operation explanation of the quenching quality judgment system. FIG. 6A is an explanatory diagram of a quenching method (quenching quality determination program) according to this embodiment. FIG. 6B is an explanatory diagram of the surface to be quenched by the laser beam according to the plan. It is an actual measurement figure which shows the temperature change of the lower end, the center, and the upper end of the surface to be quenched. It is explanatory drawing explaining the calculation formula of the cumulative type tempering parameter (cumulative value). It is a correlation diagram which shows the correspondence relation of the actual hardness with respect to the cumulative type tempering parameter.

Hereinafter, the quenching quality determination method according to the present invention will be described in detail with reference to the attached drawings with reference to suitable embodiments.

[Constitution]
FIG. 1 is a schematic overall configuration diagram of a quenching quality determination system 10 that implements the quenching quality determination method according to this embodiment.

The quenching quality determination system 10 basically has an optical head 16 that irradiates a quenching object (work) 20 with a laser beam L as an energy beam, and the optical head 16 is tilted at a predetermined angle with respect to a vertical line. An NC machine 18 that holds the object to be hardened and conveys it in the vertical direction, a chuck 22 that holds the object to be hardened 20 fixedly, and a motor 24 that rotates the object to be hardened 20 in the horizontal direction by rotating the chuck 22 in the horizontal direction. A thermometer 26 that measures the temperature of the irradiation site (irradiation position) of the laser beam L (irradiation site temperature, irradiation position temperature) and the temperature of the self-cooling site (self-cooling site temperature), and a controller (control) that controls these. Device) 28.

The optical head 16 includes a laser oscillator 12 that generates a laser beam L, and an engineering system 14 that includes a lens that converges the laser beam L generated by the laser oscillator 12 and guides the laser beam L to the quenching object 20.

The controller 28 is a computer including a microcomputer, and is a CPU (central processing unit), a memory (storage device) ROM (including EEPROM), RAM (random access memory), and other A / D converters, D. It has an input / output device such as a / A converter, a timer as a timing unit, etc., and the CPU reads and executes the program recorded in the ROM to realize various function realization units (function realization means, function unit, function). Means), for example, functions as a control unit, a calculation unit, a processing unit, and the like.

The controller 28 according to this embodiment has an NC machine drive signal Srd for transporting the NC machine 18 in the vertical direction while controlling the position in the vertical direction, and the intensity (output) of the laser beam L emitted from the optical head 16. And the optical head drive signal Shd that controls on (irradiation) / off (non-irradiation) of the laser beam L, and the motor drive signal for controlling the rotation speed and on (rotational state) / off (stop state) of the motor 24. It has each functional part that generates Smd.

The controller 28 also captures (inputs) the rotation position detection signal (rotation phase, rotation angle) of the resolver of the motor 24 as the rotation phase (rotation angle) of the object to be hardened 20, that is, the phase detection signal Spd, and quenches. The rotation phase (rotation angle) θ of the object 20 in the main scanning direction, which will be described later, is detected.

The controller 28 is further connected to a thermometer 26 that measures the temperature of the object to be quenched 20 in a non-contact manner, and captures (inputs) the temperature detection signal St.

The quenching object 20 of this embodiment is a cylinder made of mild steel or hard steel having a carbon content of about 0.15 [%] to 1.2 [%], and the inner peripheral surface of the cylinder is the surface to be quenched. It is set to 21.

Therefore, as shown in FIG. 2A, the thermometer 26 has three points (substantially) of the upper end, the center, and the lower end at the irradiation site (quenched cross section) Is of the laser beam L having a rotation angle θ of θ = 0 [°]. The three spot thermometers 26a, 26b, and 26c for measuring the temperature of the overlapped portion or the overlapped portion of the adjacent laser beams L are fixed to a fixing member (not shown).

In this case, the three spot thermometers 26a, 26b, and 26c are the lower end temperature of the irradiation site Is (the temperature of the irradiation site and the lower end temperature of the heating section) Ta and the center temperature (the temperature of the irradiation site and the center temperature of the heating section), respectively. ) Tb and the upper end temperature (the temperature of the irradiation site and the upper end temperature of the heated cross section) Tc are detected.

When the object to be quenched 20 passes the irradiation site Is while rotating in the rotation direction, it is cooled by natural cooling, so that the temperature drops sharply to a predetermined temperature at the heat-affected zone Haz shown in the gray range.

Therefore, as shown in FIG. 2B, the thermometer 26 further has θ = −0 [°] to −90 [°] in the rotational direction from the irradiation site Is where the temperature after natural cooling becomes the temperature in the equilibrium state. The temperature of the already irradiated part (cross section in the rotational direction from the hardened cross section) in the range of, in this embodiment, the temperature of the upper end, the center, and the lower end of −45 [°] (also referred to as the front 45 ° cross section). The three spot thermometers 26d, 26e, and 26f for measuring the temperature are fixed to a fixing member (not shown).

The spot thermometers 26d, 26e, and 26f have the lower end temperature (45 ° cross-section lower end temperature before heating) Td, the center temperature (45 ° cross-section center temperature before heating) Te, and the upper end temperature (before heating) of the 45 ° pre-irradiation site Ib, respectively. 45 ° Cross-section top temperature) Tf is detected.

The above θ = −0 [°] is half (radius = D / 2) of the beam diameter D of the laser beam L shown in FIG. 3 (for example, the diameter at which the intensity distribution on the cross section perpendicular to the beam is halved). It means that the position is farther away (the position where the heat of the irradiation site Is of the laser beam L does not affect).

The thermometer 26 is not limited to the spot thermometers 26 (26a to 26f) as shown in FIGS. 2A and 2B, and as shown in FIG. 4, the entire area is observed as a thermal image by the thermography 26sg. It may be detected.

[motion]
Basically, the operation of the quenching quality determination system 10 configured as described above will be described with reference to the flow chart shown in FIG.

The controller 28 sets a quenching method (quenching quality determination program) corresponding to the quenching target 20 in the initial setting of step S1.

[Quenching plan (quenching quality judgment program)]
As shown in FIGS. 6A and 6B, the quenching method (quenching quality determination program) according to this embodiment is a quenching object that rotates at a predetermined rotation speed (constant rotation number) through the motor 24 and the chuck 22 by the motor drive signal Smd. Preheating 1 is performed on the inner peripheral surface of the cylinder of 20 by scanning the upper end side in the main scanning direction with the laser beam L at time points t1 to t2, and then at time point t2, the optical head 16 is passed through the NC machine 18. It is transferred by overlapping approximately one beam diameter D downward (sub-scanning direction orthogonal to the main scanning direction) by a predetermined amount, scanning the central portion at time points t2 to t3 to perform preheating 2, and further, time point t3. At, the beam is transferred downward by approximately one beam diameter D by a predetermined amount, and the lower end side is scanned at time points t3 to t4 to perform preheating 3.

Further, at the time point t4, scanning is performed on the same scanning line (on the lower end side scanning line) and at the time points t4 to t5 to perform the main heating 1. It is transferred by overlapping the diameter D above (the sub-scanning direction orthogonal to the main scanning direction) by a predetermined amount, scanning the central portion at time points t5 to t6 to perform main heating 2, and further at time point t6. The entire surface of the surface to be quenched 21 of the object to be quenched 20 is quenched by scanning the upper end side at time points t6 to t7 and performing the main heating 3 by overlapping and transferring by approximately one beam diameter D by a predetermined amount. To finish.

The controller 28 turns the laser beam L into an on (irradiation) state at a constant output (constant intensity) at a time point t1 during the preliminary heating 1 to 3 and the main heating 1 to 3, and the constant output at the time point t7. The optical head drive signal Shd that turns off (non-irradiates) the laser beam L output at (constant intensity) is supplied to the optical head 16.

The motor 24 is stopped when the reheating tempering temperature (reheating tempering temperature point) Ti (i = 1, 2, ...) To be described later is no longer detected.

As described above, the temperature detection signal St is the lower end temperature (heating cross section lower end temperature) at the irradiation site (hardening cross section) Is of the laser beam L having a rotation angle θ of θ = 0 [°] by the spot thermometers 26a to 26f. ) Ta, the center temperature (center temperature of the heated cross section) Tb, and the upper end temperature (upper end temperature of the heated cross section) Tc are continuously detected, and the rotation angle θ is θ = −45 [°] (also referred to as the front 45 ° cross section). -45 ° pre-irradiation site Ib bottom temperature (45 ° cross-section bottom temperature before heating) Td, center temperature (45 ° cross-section center temperature before heating) Te, and top temperature (45 ° cross-section top temperature before heating) Tf The preheating period (time points t1 to t4), the main heating period (time points t4 to t7), and the period in which the reheating and tempering temperature is detected are continuously detected.

Then, the quenching quality is determined based on the reheating tempering temperature point (reheating tempering temperature) Ti.

In this embodiment, after step S1 in which the above-mentioned quenching method (quenching quality determination program) is set, in step S2, the controller 28 moves the laser beam L to the initial scanning position of the quenching object 20 fixed to the chuck 22. The NC machine 18 is driven by the NC machine drive signal Srd so that the optical head 16 is positioned. In other words, in step S2, the quenching object 20 is positioned and fixed at the irradiation site of the laser beam L.

In step S3, the controller 28 speed-controls the motor 24 by the motor drive signal Smd so that the motor 24 rotates at a predetermined rotation speed (constant rotation speed), that is, the quenching object 20 rotates at a predetermined rotation speed (constant rotation speed).

Next, in step S4, the controller 28 uses the spot thermometers 26a to 26f to measure the heating cross-section lower end temperature Ta, the heating cross-section center temperature Tb, the heating cross-section upper end temperature Tc, the pre-heating 45 ° cross-section lower end temperature Td, and the pre-heating 45 °. Detection of the cross-section center temperature Te and the cross-section upper end temperature Tf before heating is started.

Next, in steps S5 and S6, the preliminary heat treatment and the main heat treatment by the laser beam L described with reference to FIGS. 6A and 6B are performed, respectively.

Due to the preheating treatment, the temperature Td at the lower end of the 45 ° cross section before heating, the central temperature Te at 45 ° before heating, and the temperature Tf at the upper end of the 45 ° cross section before heating are predetermined to be lower than the martensitic transformation start temperature Ms (referred to as Ms point temperature). By this heat treatment during the period when the temperature is heated to 45 ° before heating and the 45 ° cross-section temperature before heating is stable (the temperature gradient is equal to or less than the predetermined value), the lower end temperature Ta of the heated cross section, the center temperature Tb of the heated cross section, and heating are performed. Hardening is performed by heating the upper end temperature Tc of the cross section to a temperature higher than the austenizing temperature A3 (referred to as A3 point temperature).

Next, in step S7, due to the end of the main heat treatment, the 45 ° cross-section lower end temperature Td before heating, the 45 ° cross-section center temperature Te before heating, and the 45 ° cross-section upper end temperature Tf before heating start to decrease for a predetermined time. When (for example, one rotation cycle) has elapsed, in step S8, the motor 24 is stopped and the temperature detection by the spot thermometers 26a to 26f is terminated.

In step S9, the quenching quality is determined, and the current process is terminated. In the next and subsequent quenching treatments for the same quenching object 20, the treatments after step S2 may be repeated.

<Quenching quality judgment>
FIG. 7 shows the temperature changes at the lower end, the center, and the upper end of the quenching target surface 21. In FIG. 7, the sawtooth wave drawn downward indicates the phase detection signal Spd, and its amplitude value corresponds to 0 [°] to 360 [°]. It is possible to detect the rotation angle θ on the hardened surface of the hardened object 20 in.

As can be seen from the change in the lower end temperature Ta of the heating cross section, the lower end is quenched by heating above the A3 point temperature by the main heating 1 at the time points t4 to t5.

Similarly, by the main heating 2 at time points t5 to t6, the center is quenched by being heated above the A3 point temperature, as can be seen from the change in the central temperature Tb of the heating cross section.

Similarly, by the main heating 3 at the time points t6 to t7, the upper end is quenched by being heated above the A3 point temperature, as can be seen from the change in the heating cross-sectional upper end temperature Tc.

In the lower end scanning line (lower end quenching part), the 45 ° cross-section lower end temperature Td before heating immediately before the time point t6 is lower than the Ms point temperature, and at the time point t6, the heated cross-section lower end temperature Ta is higher than the Ms point temperature. Is less than the A3 point temperature, so it is detected as the reheating tempering temperature point (temperature T1l).

Further, in the lower end scanning line (lower end quenching portion), the 45 ° lower end temperature Td of the cross section before heating immediately before the time point t7 is lower than the Ms point temperature, and at the time point t7, the lower end temperature Ta of the heated cross section is higher than the Ms point temperature. However, since the temperature is lower than the A3 point temperature, it is detected as the reheating tempering temperature point (temperature T2l).

In the central scanning line (central quenching portion), the 45 ° cross-sectional center temperature Te before heating immediately before the time point t7 is below the Ms point temperature, and at the time point t7, the heated cross-section center temperature Tb is above the Ms point temperature. Is less than the A3 point temperature, so it is detected as the reheating tempering temperature point (temperature T1 m).

In the upper end scanning line (upper end quenching portion), the 45 ° cross-section upper end temperature Tf immediately before heating at the time point t8 is below the Ms point temperature, and at the time point t8, the heated cross-section upper end temperature Tc is higher than the Ms point temperature. Is less than the A3 point temperature, so it is detected as the reheating tempering temperature point (temperature T1u).

Good or poor quenching quality is determined depending on whether the quenching hardness of the quenching object 20 reaches the target hardness Htar. The cumulative tempering parameter (cumulative) shown in the following equation (1) is determined. Value) In this embodiment, the actual hardness is predicted by calculating M.

M = (C + log) ΣTi = (C + log) T1 + (C + log) T2 + (C + log) T3 + ... (1)

Here, Ti is the reheating tempering temperature point [° C.], t is the tempering time [s], and the value obtained by dividing the beam diameter D of the laser beam L by the peripheral speed v [m / s] in the main scanning direction. That is, the irradiation time of the laser beam L at the irradiation site Is, C is determined by the steel material, and C = 17.7-5.8 × a (a is the carbon content [%]).

As described above, as the reheating tempering temperature point Ti, two points of temperature T1l and T2l are detected at the lower end, one point of temperature T1m is detected at the center, and temperature T1u is detected at the upper end.

Here, for convenience of understanding of equation (1), as shown in FIG. 8, three reheating tempering temperature points T1, T2, and T3 are tentatively detected by the scanning line at the lower end (quenched portion at the lower end). If so, the cumulative tempering parameter (cumulative value) M can be calculated up to the third term of the above equation (1).

FIG. 9 shows the characteristic 100 (correlation line) of the correspondence between the cumulative tempering parameter (cumulative value) M acquired in advance and the actual hardness.

When the value of the cumulative tempering parameter (cumulative value) M is larger than the target cumulative value Mtar, the actual hardness is lower than the target hardness Htar, so the quenching quality is judged to be poor (NG), and when the value is less than the target cumulative value Mtar. Since the actual hardness exceeds the target hardness Htar, the quenching quality is good and it is judged as "Good".

[Summary and modification examples]
The quenching quality determination method according to the above-described embodiment is a quenching quality determination method for determining the quenching quality of the quenching object 20, with respect to the irradiated energy beam (laser beam L or electron beam such as a semiconductor laser). By rotating the object to be quenched 20 to quench in the main scanning direction, and sequentially transferring the object to be quenched in the sub-scanning direction orthogonal to the main scanning direction, the entire surface of the surface to be quenched 21 is quenched.

In the above embodiment, the fixed laser beam L is scanned by rotating the quenching object 20 with the motor 24, and the quenching target surface 21 is quenched, but the present invention is limited to this. Instead, by using a galvano scanner or the like, the laser beam L may be scanned in a three-dimensional space to perform quenching on the quenching target surface 21. In short, the surface to be quenched 21 may be scanned by rotating the object to be quenched 20 relative to the energy beam L to be irradiated.

Then, in this embodiment, when determining the quenching quality, the temperature history for each main scanning direction of the irradiation site Is of the energy beam L (heating cross-section lower end temperature Ta, heating cross-section center temperature Tb, and heating cross-section upper end temperature Tc). Reheating and quenching temperature points (temperatures T1l, T2l, T1m, according to the rotation cycle (period of the phase detection signal Spd)) for each temperature history of the irradiation site Is in the main scanning direction. It includes an acquisition step for acquiring T1u) and a determination step for determining the quenching quality of the quenching object 20 based on the acquired reheated tempering temperature points (temperatures T1l, T2l, T1m, T1u).

According to this embodiment, the quenching target is for each temperature history (heating cross-section lower end temperature Ta, heating cross-section center temperature Tb, heating cross-section upper end temperature Tc) of the irradiation site Is in each main scanning direction constituting the quenching target surface 21. The reheated tempering temperature points (temperatures T1l, T2l, T1m, T1u) according to the rotation cycle of the object 20 are acquired, and the quenching target is obtained based on the acquired reheated tempering temperature points (temperatures T1l, T2l, T1m, T1u). Since the quenching quality of the object 20 is determined, after irradiating one irradiation site Is (for example, the irradiation site Is on the lower end scanning line in FIG. 6B) in the main scanning direction, the sub-scanning is performed at the same position in the main scanning direction. During the self-cooling of the quenching object 20 to the next irradiation site Is (in this case, the irradiation site Is on the central scanning line in FIG. 6B) adjacent to each other in the direction, the next irradiation site Is (irradiation site Is on the central scanning line). ) Reheats the one irradiation site (irradiation site Is on the lower end scanning line), and the quenching quality (pass / fail) of the site where tempering occurs due to the reheating can be accurately determined.

In the acquisition step of acquiring the reheat tempering temperature point Ti, the self at a predetermined position (for example, a 45 ° cross section before heating) immediately before the irradiation site Is in each main scanning direction constituting the quenching target surface 21 after quenching. When the temperature of the cooling site (Tf, Te, Td) is lower than the martensitic transformation start temperature Ms point, and the temperature of the self-cooling site at the position corresponding to the irradiation site Is is the martensitic transformation start temperature Ms. When the temperature exceeds the point and is reheated to a temperature within the temperature range lower than the austenitic transformation temperature A3 point, it is determined and acquired as the reheat tempering temperature point (temperatures T1l, T2l, T1m, T1u).

As described above, the temperature of the self-cooling portion at a predetermined position immediately before the irradiation portion Is in each main scanning direction (for example, a 45 ° cross section before heating) constituting the quenching target surface 21 after quenching is the martensitic transformation start temperature Ms point. In the lower case, the temperature of the self-cooling site at the position corresponding to the irradiation site Is exceeded the martensitic transformation start temperature Ms and was reheated to a temperature within the temperature range lower than the austenitization temperature A3 point. In this case, since it can be estimated that tempering will occur, it is possible to reliably determine and obtain whether or not the temperature is the reheating tempering temperature point (temperatures T1l, T2l, T1m, T1u).

The predetermined position immediately before the irradiation site Is in each main scanning direction is a position before the irradiation site Is, which is far from the beam diameter (D / 2) at the irradiation site Is of the energy beam L, and is an energy beam. By setting the position until switching from self-cooling to reheating due to the approach of L, the reheating tempering temperature point (temperature T1l, provided that the temperature at that position is less than the martensitic transformation start temperature Ms point). T2l, T1m, T1u) can be reliably acquired.

Further, in the determination step for determining the quenching quality of the quenching object 20, the reheating tempering temperature points (temperatures T1l, T2l, T1m, T1u) are set to the carbon content a [%] of the quenching object 20 and the irradiation site Is. The cumulative value (for example, M = (C + log) (T1l + T2l)) weighted and accumulated by the irradiation time t (beam diameter D / peripheral speed v) of the energy beam L in the above is the target for obtaining the desired quenching hardness. Since it is determined that the quenching quality is acceptable in the range below the threshold (target cumulative value) Mtar set corresponding to the hardness Htar, and the quenching quality is rejected in the range above the threshold (target cumulative value) Mtar. , Pass / fail judgment can be performed accurately.

That is, since the pass / fail judgment of the quenching quality can be performed based on whether the cumulative value M is equal to or less than the threshold value by using the above equation (1), the pass / fail judgment for obtaining the desired quenching hardness can be easily performed.

It should be noted that the present invention is not limited to the above-described embodiment, and it goes without saying that various configurations can be adopted based on the contents described in this specification.

10 ... Quenching quality judgment system 16 ... Optical head 20 ... Quenching object 21 ... Quenching target surface 26 ... Thermometer 28 ... Controller L ... Laser beam

Claims (4)

It is a quenching quality determination method for determining the quenching quality of an object to be quenched.
Quenching is performed in the main scanning direction by rotating the quenching object relative to the irradiated energy beam, and the quenching target is sequentially transferred in the sub-scanning direction orthogonal to the main scanning direction. When quenching the surface,
A measurement step for measuring the temperature history of the irradiation site of the energy beam for each main scanning direction, and a measurement step.
An acquisition step of acquiring a reheating tempering temperature point according to the rotation cycle for each temperature history of the irradiation site in each main scanning direction.
A determination step for determining the quenching quality of the quenching object based on the acquired reheat tempering temperature point, and
A quenching quality determination method characterized by comprising. In the quenching quality determination method according to claim 1,
In the acquisition step of acquiring the reheating tempering temperature point,
When the temperature of the self-cooling site at a predetermined position immediately before the irradiation site in each main scanning direction constituting the quenching target surface after quenching is lower than the martensitic transformation start temperature, and the position corresponding to the irradiation site. When the temperature of the self-cooling site in the above is above the martensitic transformation start temperature and reheated to a temperature within the temperature range lower than the austenitization temperature, it is determined to be the reheat tempering temperature point and obtained. Quenching quality determination method characterized by. In the quenching quality determination method according to claim 2,
The predetermined position immediately before the irradiation site in each main scanning direction is a position before the irradiation site far from the beam diameter at the irradiation site of the energy beam, and is re-cooled from self-cooling due to the approach of the energy beam. A quenching quality determination method characterized by the position until switching to heating. In the quenching quality determination method according to any one of claims 1 to 3,
In the determination step of determining the quenching quality of the quenching object,
The cumulative value obtained by weighting the reheating tempering temperature point by the carbon content of the quenching object and the irradiation time of the energy beam at the irradiation site is the target hardness for obtaining the desired quenching hardness. A quenching quality determination method, characterized in that it is determined that the quenching quality is acceptable in a range below the correspondingly set threshold, and that the quenching quality is unacceptable in a range above the threshold.

Images