Laser hardening equipment

Abstract

To provide a laser hardening apparatus capable of improving accuracy of hardening treatment by preventing overheating when a laser beam is applied to a workpiece.SOLUTION: A laser hardening apparatus 100 includes a laser drive unit 114 that controls an operation of a laser light source 110. The laser drive unit 114 includes a laser control unit 114a that controls an intensity (an output value) of a laser light L, an output value storage unit 114b that stores a hardening output value, and an operation panel 114c. The hardening output value is constituted by a magnitude with respect to the intensity of the laser light L that can heat a surface of a workpiece WK to a hardening temperature. The laser hardening apparatus 100 stores the hardening output value in the output value storage unit 114b by executing a hardening output value setting subprogram. When the laser hardening apparatus 100 irradiates the workpiece WK with the laser light L, the laser hardening apparatus 100 emits the laser light L according to the hardening output value stored in the output value storage unit 114b.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a laser hardening device that performs hardening processing on a workpiece by irradiating the workpiece with laser light. [Background technology]

[0002] Conventionally, laser hardening devices have been known that irradiate the surface of a workpiece such as carbon steel with a laser beam to heat the irradiated portion to an austenite state and perform hardening. In this case, the portion of the workpiece heated to the austenite state is rapidly cooled by itself through thermal diffusion and thermal conduction to the interior and periphery of the workpiece after the laser beam has passed through. For example, Patent Document 1 listed below discloses a laser hardening device that increases or decreases the output of the laser beam depending on the temperature of the heated portion of the workpiece irradiated with the laser beam. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 3-56615

[0004] However, in the laser hardening device disclosed in Patent Document 1, immediately after the workpiece is irradiated with laser light, an overshoot occurs in which the temperature of the heated portion becomes higher than the temperature suitable for hardening, causing the workpiece to melt, resulting in a problem of reduced accuracy in the hardening process.

[0005] The present invention has been made to address the above-mentioned problems, and its object is to provide a laser hardening device that can prevent the workpiece from being overheated when irradiated with laser light, thereby improving the accuracy of the hardening process. Summary of the Invention

[0006] In order to achieve the above object, the present invention is characterized in that a laser hardening device forms a light spot by a laser beam on the surface of a workpiece to harden the surface, the device comprising: a laser light source for emitting a laser beam; a control device for controlling the output of the laser beam emitted from the laser light source; and a hardening output value that is an output value of the laser beam that can heat the surface of the workpiece to a hardening temperature, the control device storing the hardening output value. Output value storage unit and 、 An object temperature detector that outputs a temperature detection signal that indicates the temperature of the surface of the object on which a light spot is formed by being irradiated from a laser light source. and The control device includes a small-output laser light emitting step of emitting laser light from the laser light source at an output value that cannot heat an object that is the same as or similar to the workpiece to the hardening temperature, a laser output increasing step of increasing the output value of the laser light emitted from the laser light source until the temperature detected using the temperature detection signal output by the object temperature detector reaches the hardening temperature, and storing the output value of the laser light when the temperature detected using the temperature detection signal output by the object temperature detector reaches the hardening temperature in an output value storage unit as a hardening output value. death, The laser beam is started to be emitted to the workpiece at the hardening output value.

[0007] According to the features of the present invention configured as described above, the laser hardening device starts irradiating the workpiece with a laser beam at a hardening output value that is an output value of the laser beam that can heat the surface of the workpiece to the hardening temperature, so that the irradiated portion of the workpiece with the laser beam can be prevented from being overheated beyond the hardening temperature, thereby improving the accuracy of the hardening process. Also, the laser hardening device according to the present invention can quickly heat the surface of the workpiece to the hardening temperature. Further, according to the present invention, The laser hardening device increases the output value of the laser light from an output value that is not enough to heat the same or similar object as the workpiece to the hardening temperature until the hardening temperature is reached, and obtains the output value when the hardening temperature is reached as the hardening output value, thereby enabling the production of a highly accurate hardening output value.

[0008] Here, the hardening output value capable of heating the surface of the workpiece to the hardening temperature is the output power capable of heating the surface of the workpiece to above the lower limit and below the upper limit of the hardening temperature without changing the output power of the laser beam. In this case, the hardening output value includes an output value that can maintain the surface of the workpiece at the hardening temperature after heating it to the hardening temperature, and an output value that drops below the hardening temperature over time.

[0009] Another feature of the present invention is that in the laser hardening device, the hardening output value is set to a temperature required for hardening the surface of the workpiece. to The key is to have a value that can be maintained.

[0010] According to another feature of the present invention configured in this manner, the laser hardening device has a hardening output value set to a value that can maintain the temperature of the surface of the workpiece, so that accurate hardening processing can be performed even after the temperature of the hardened portion of the workpiece has reached the hardening temperature, without any control to maintain the hardening temperature.

[0011] Another feature of the present invention is that in the laser hardening device, the output value memory unit stores a plurality of hardening output values ​​for at least one of the type of workpiece, the size of the light spot, the feed rate of the light spot, and the hardening temperature.

[0012] According to another feature of the present invention configured in this manner, the laser hardening device has an output value memory unit that stores a plurality of hardening output values ​​for at least one of the type of workpiece, the size of the light spot, the feed rate of the light spot, and the hardening temperature, so that the hardening process can be performed by appropriately selecting a hardening output value that corresponds to the type of workpiece or the specifications of the hardening process.

[0013] Another feature of the present invention is that the laser hardening apparatus further comprises a workpiece temperature detector that outputs a temperature detection signal representing the temperature of the surface of the workpiece on which a light spot is formed when the workpiece is irradiated with the laser light source, and the control device is provided in a laser drive unit that supplies laser drive power to the laser light source, and controls the operation of the laser drive unit using the temperature detection signal output by the workpiece temperature detector so that the temperature of the surface of the workpiece irradiated with the laser light is maintained at the hardening temperature.

[0014] According to another feature of the present invention configured in this manner, the laser hardening device controls the emission intensity of the laser light within the laser driving unit, so that the emission intensity can be quickly controlled in accordance with the temperature condition of the hardening portion of the workpiece.

[0015] Another feature of the present invention is that in the laser hardening device, the control device stores a history of changes in the output value of the laser light for the workpiece. According to another feature of the present invention thus configured, The laser hardening device stores the change history of the output value of the laser beam for the workpiece, thereby improving traceability by leaving a record of the processing details of the workpiece and enabling tracking at a later date. Furthermore, the laser hardening device according to the present invention can also verify the validity of the hardening output value at the time of emitting the laser beam by checking the change history of the output value of the laser beam.

[0016] In addition, the laser hardening device A laser hardening device forms a light spot with a laser beam on the surface of a workpiece to harden the surface, and includes a laser light source that emits a laser beam, a control device that controls the output of the laser beam emitted from the laser light source, and a hardening output value that is the output value of the laser beam that can heat the surface of the workpiece to a hardening temperature. Output value storage unit The control device starts emitting the laser light to the workpiece at the hardening output value. According to this,The laser hardening device starts irradiating the workpiece with a laser beam at a hardening output value that is an output value of the laser beam that can heat the surface of the workpiece to the hardening temperature, so that the irradiated portion of the workpiece with the laser beam can be prevented from being overheated beyond the hardening temperature, and the accuracy of the hardening process can be improved. Laser hardening equipment: The surface of the workpiece can be quickly heated to the hardening temperature. where: The hardening output value that can heat the surface of the workpiece to the hardening temperature is the output that can heat the surface of the workpiece to above the lower limit of the hardening temperature and below the upper limit of the hardening temperature without changing the output of the laser beam. In this case, the hardening output value includes an output value that can maintain the surface of the workpiece at the hardening temperature after heating it to the hardening temperature, and an output value that drops below the hardening temperature over time.

[0017] In addition, the laser hardening device In the laser hardening device, the hardening output value is set to a value required to harden the surface temperature of the workpiece. to It is a value that can be maintained According to this, The laser hardening device has a hardening output value set to a value that can maintain the temperature of the surface of the workpiece, so it can perform accurate hardening processing even after the temperature of the hardened part of the workpiece reaches the hardening temperature without any control to maintain the hardening temperature.

[0018] In addition, the laser hardening device In the laser hardening device, the output value storage unit stores a plurality of hardening output values ​​for at least one of the types of workpieces, the sizes of the light spots, the feed rates of the light spots, and the hardening temperatures. According to this, In the laser hardening device, the output value memory unit stores multiple hardening output values ​​for at least one of the type of workpiece, the size of the light spot, the feed rate of the light spot, and the hardening temperature, so that the hardening process can be performed by appropriately selecting the hardening output value according to the type of workpiece or the specifications of the hardening process. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a block diagram schematically showing the configuration of a laser hardening device according to an embodiment of the present invention; [Figure 2] 2 is an explanatory diagram schematically showing the positions at which a temperature detector measures the temperature relative to the light spots formed on the surfaces of the test piece or workpiece by the laser hardening device shown in FIG. 1. FIG. [Figure 3] 2 is a flowchart showing the flow of processing of a hardening output value setting program executed by a general control device in the laser hardening device shown in FIG. [Figure 4] 1. FIG. 4 is a flowchart showing a part of the processing flow of a hardening output value setting subprogram executed by a laser control unit in the laser hardening device shown in FIG. [Figure 5] 10 is a flowchart showing another part of the processing flow of the hardening output value setting subprogram executed by the laser control unit in the laser hardening device shown in FIG. [Figure 6] 2 is a flowchart showing a flow of processing of a laser output adjusting program executed by a laser control unit in the laser hardening apparatus shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0020] (Configuration of laser hardening device 100) An embodiment of a laser hardening apparatus according to the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a schematic configuration of a laser hardening apparatus 100 according to the present invention. The drawings referred to in this specification are schematic, with some components exaggerated to facilitate understanding of the present invention. Therefore, the dimensions and ratios of the components may differ. The laser hardening apparatus 100 is a heat treatment device that uses a laser to harden the surface of a workpiece WK made of a metal material such as carbon steel by irradiating the workpiece WK with laser light L under computer control (NC control).

[0021] The laser hardening apparatus 100 includes a table 101. The table 101 is a plate-shaped mounting base that detachably holds the workpiece WK, and is supported by an XY feed device 102. The XY feed device 102 is a mechanical device that displaces the table 101 in two mutually perpendicular axial directions, the X-axis direction and the Y-axis direction, within the same plane, under the operational control of an overall control device 120 (described later), and is configured with a feed screw mechanism.

[0022] In this case, the feed screw mechanism is configured to include feed screw shafts (not shown) on which male threads are formed and which extend in the X-axis direction and the Y-axis direction, and nut portions (not shown) on which female threads that mesh with the male threads are formed and which are directly or indirectly connected to table 101. In Fig. 1, the X-axis direction is the left-right direction, and the Y-axis direction is the depth direction of the page.

[0023] The feed screw shafts of this feed mechanism extending in the X-axis direction and the Y-axis direction are connected to feed motors (not shown). These feed motors are electric motors (servo motors in this embodiment) that rotate the feed screw shafts in the forward and reverse directions, respectively, and their operation is controlled by the overall control device 120.

[0024] A laser light source 110 is provided above the table 101. The laser light source 110 is an optical device for emitting laser light L to heat the workpiece WK held on the table 101, and is supported by a support 112. In this embodiment, it is configured as a semiconductor laser with a wavelength of 940 nm and an output of 2 kW. The operation of this laser light source 110 is controlled by the overall control device 120 via a laser driver 114, and it forms a rectangular light spot SP with sides of 5 mm on the surface of the workpiece WK.

[0025] The shape and size of the light spot SP, the type and output of the laser are set appropriately according to the specifications of the hardening process, and are not limited to those in this embodiment. The laser light source 110 is provided with a temperature detector 111.

[0026] The temperature detector 111 is a temperature detection device that outputs a temperature detection signal, which is an electrical signal corresponding to the temperature of the portion of the surface of the workpiece WK irradiated with the light spot SP, to the laser driver 114. In this embodiment, the temperature detector 111 is configured as a radiation thermometer that detects the temperature coaxially with the optical axis of the laser light emitted by the laser light source 110. The temperature detector 111 is attached to the side of the laser light source 110.

[0027] In this case, the temperature detector 111 can adjust the measurement position MP to any position within the temperature measurement range within the region on the surface of the workpiece WK where the light spot SP is formed. In this embodiment, as shown in Fig. 2, the temperature detector 111 is adjusted so that the temperature measurement position MP is located rearward in the direction of travel of the light spot SP within the region on the surface of the workpiece WK where the light spot SP is formed (rearward in the direction of travel of the light spot SP from the center of the light spot SP). In this case, the temperature measurement position MP is preferably located at the very rear of the region on the surface of the workpiece WK where the light spot SP is formed, with respect to the direction of travel of the light spot SP.

[0028] The support 112 is a metal part for supporting the laser light source 110 above the table 101, and is supported by a Z feed device 113. The support 112 supports the laser light source 110 in a state in which the angle of the laser light source 110 relative to the surface of the table 101 can be changed.

[0029] Z feed device 113 is a mechanical device for displacing table 101 in the Z-axis direction (the up-down direction in the figure) perpendicular to the X-axis direction and the Y-axis direction in the figure under the operation control of overall control device 120, and is configured to include a feed screw mechanism. In this embodiment, table 101 is configured to displace in the X-axis direction and the Y-axis direction in the figure relative to laser light source 110, and laser light source 110 is configured to displace in the Z-axis direction in the figure relative to table 101. However, it is sufficient that table 101 and laser light source 110 are configured to be displaceable relative to each other, and therefore it is sufficient that at least one of them is configured to be displaceable relative to the other.

[0030] The laser driving unit 114 is a constant current power supply that functions as a driver for controlling the operation of the laser light source 110 by supplying power supplied from an external power supply (not shown) to the laser light source 110 in accordance with the operation control of the overall control device 120. The laser driving unit 114 is equipped with a laser control unit 114a that is configured by a microcomputer including a CPU, ROM, RAM, etc. that controls the operation of the constant current power supply in accordance with instructions from the overall control device 120.

[0031] The laser control unit 114a independently controls whether or not to emit the laser light L and the output intensity of the laser light L, causing the laser light source 110 to continuously oscillate the laser light L. The laser control unit 114a also includes an output value storage unit 114b for storing a hardening output value. Here, the hardening output value is an output value that defines the intensity of the laser light L at the start of emission when the laser light source 110 emits the laser light L toward the workpiece WK. The hardening output value is stored in the output value storage unit 114b by the laser control unit 114a executing the hardening output value setting subprograms shown in FIGS. 4 and 5. The laser control unit 114a also executes a laser output control program shown in FIG. 6 to control the output of the laser light L during the hardening process of the workpiece WK.

[0032] An operation panel 114c is connected to this laser control unit 114a. The operation panel 114c is an input / output interface dedicated to the laser control unit 114a, and includes an input device (not shown) consisting of a group of switches that accept instructions from an operator and input them to the laser control unit 114a, and a liquid crystal display device (not shown) that displays the operating status of the laser control unit 114a.

[0033] The overall control device 120 is composed of a microcomputer including a CPU, ROM, RAM, etc., and controls the overall operation of the laser hardening device 100, and also controls the heat treatment processing of the workpiece WK by relatively displacing the table 101 and the laser light source 110 while emitting laser light L from the laser light source 110 in accordance with a hardening processing program (a so-called NC (Numerical Control) program) not shown prepared by an operator.

[0034] This overall control device 120 sets an initial value of the hardening output value by executing the hardening output value setting program shown in Fig. 3. In addition, this overall control device 120 is equipped with an operation panel 121 consisting of a group of operation switches for receiving operations from an operator to the overall control device 120, and a display device 122 consisting of a liquid crystal display for displaying the operating status of the overall control device 120 to the operator.

[0035] (Operation of laser hardening device 100) Next, the operation of the laser hardening apparatus 100 configured as described above will be described. First, the worker who performs the hardening process on the workpiece WK specifies the hardening output value to be used when performing the hardening process on the workpiece WK. Here, the hardening output value is specified by the worker executing a hardening output value setting program, as shown in FIG.

[0036] Specifically, the operator sets the initial values ​​of the hardening temperature and hardening output value in the laser control unit 114a, prepares a test piece TP made of the same metal material as the workpiece WK, sets it on the table 101, and then instructs the overall control device 120 to execute the hardening output value setting program. In this case, the test piece TP is made of the same or the same type of metal material as the workpiece WK, has the same surface properties and shape, and corresponds to the object according to the present invention.

[0037] Here, the term "same kind of metal material" refers to two metal materials being compared that have the same main component (the element with the highest content). For example, pure iron and carbon steel are similar metal materials in that they both contain iron (Fe) as their main component. The term "same material" does not necessarily mean that the materials are completely identical, but rather refers to materials that can be considered substantially identical, even if they have slight differences, to the extent that the differences can be ignored. Furthermore, the term "surface texture" refers to the surface irregularities, surface roughness, or surface color.

[0038] The quenching temperature is a specified temperature or temperature range at which the structure of the test piece TP is brought to an austenitic state and quenching is properly performed. Therefore, the operator inputs the quenching temperature of the test piece TP to the laser control unit 114a via the operation panel 114c. In this embodiment, the operator inputs a quenching temperature range consisting of the minimum and maximum temperatures at which the test piece TP can be quenched to the laser control unit 114a. In this case, the operator may input the minimum and maximum temperatures at which the test piece TP can be quenched, respectively, or may input a specific temperature and an allowable range for that specific temperature (e.g., ±10°C). Suitable quenching temperatures are, for example, approximately 800°C for carbon tool steels (SK materials) and low-alloy tool steels (SKS materials), approximately 1000°C to 1050°C for alloy tool steels (SKD materials), and 1200°C or higher for high-speed tool steels (SKH materials).

[0039] The initial quenching output value is the output value when the laser light source 110 first irradiates the test piece TP with the laser light L, and is a value of magnitude that is not sufficient to heat the test piece TP to its quenching temperature. Therefore, the operator inputs an output value that is the intensity of the laser light L that is not sufficient to heat the test piece TP to its quenching temperature to the laser control unit 114a via the operation panel 114c.

[0040] The operator also sets other parameters necessary for the hardening process on the test piece TP in the overall control device 120 as appropriate, such as the starting position of the hardening process on the test piece TP, the focal length of the laser light source 110 relative to the test piece TP, and the feed speed of the test piece TP (in other words, the feed speed of the light spot SP).However, since these parameters are not directly related to the present invention, their explanation will be omitted.

[0041] The overall control device 120 starts the execution of the hardening output value setting program in step S100, and starts the hardening process on the test piece TP in step S102. Specifically, the overall control device 120 controls the operation of the XY feed device 102 and the Z feed device 113 to position the test piece TP with respect to the laser light source 110, and then instructs the laser driver 114 to emit the laser light L. In response to this instruction, the laser control unit 114a of the laser driver 114 starts the execution of the hardening output value setting subprogram shown in Figures 4 and 5, which will be described later.

[0042] Next, in step S104, the overall control device 120 determines the end of the quenching process. The process of determining the end of the quenching process in step S104 is a process of determining the completion of the quenching process for the test piece TP. In this case, the overall control device 120 determines the end of the quenching process by detecting that the laser light L has moved to the final position of the quenched portion of the test piece TP.

[0043] Therefore, the overall control device 120 continues to determine "No" until the laser beam L reaches the final position of the hardened portion and waits for detection of an instruction to end the hardening process. On the other hand, when the laser beam L has reached the final position of the hardened portion, the overall control device 120 determines "Yes" and proceeds to step S106.

[0044] Next, in step S106, the overall control device 120 executes a hardening end process. Specifically, the overall control device 120 instructs the laser driver 114 to stop emitting the laser light L, and ends the operations of the XY feed device 102 and the Z feed device 113.

[0045] Then, the overall control device 120 ends the execution of the hardening output value setting program in step S108, so the operator removes the test piece TP from the table 101 and ends the hardening output value setting work.

[0046] Meanwhile, in step S102 of this hardening output value setting program, the laser control unit 114a of the laser driving unit 114 receives an instruction to emit laser light L from the overall control device 120, starts execution of the hardening output value setting subprograms shown in Figures 4 and 5 in step S200, and in step S202, causes the laser light source 110 to emit laser light L.

[0047] In this case, the laser control unit 114a causes the laser light source 110 to emit the laser light L at the initial value of the hardening output value preset in the laser control unit 114a. The step of starting emission of the laser light L at an output value that results in an intensity of the laser light L that is not sufficient to heat up to the hardening temperature corresponds to the small-output laser light emission step according to the present invention.

[0048] As a result, a light spot SP is formed on the test piece TP by the laser light L of an intensity that is not sufficient to heat the test piece TP to the hardening temperature. The laser control unit 114a controls the operation of the temperature detector 111 to input a temperature detection signal representing the surface temperature of the test piece TP within the light spot SP, thereby starting detection of the surface temperature of the test piece TP. The overall control device 120 controls the operation of the XY feed device 102 to displace the test piece TP relative to the laser light source 110, thereby displacing the position of the light spot SP on the test piece TP. The direction of displacement of the light spot SP does not necessarily have to be the same as the direction of displacement of the light spot SP in the hardening process on the actual workpiece WK, but it is preferable that it be the same.

[0049] Next, in step S204, the laser control unit 114a determines whether or not an instruction to stop the laser beam has been issued. The process of determining whether or not an instruction to stop the laser beam has been issued in step S204 is a process of determining whether or not an instruction to stop the laser beam L has been issued due to the completion of the hardening process on the test piece TP. In this case, the instruction to stop the laser beam L is issued by detecting the completion of the irradiation of the laser beam L onto the hardened portion of the test piece TP.

[0050] Therefore, the laser control unit 114a continues to determine "No" until it detects an instruction to stop the laser light L, and proceeds to step S206. On the other hand, if the laser control unit 114a detects an instruction to stop the laser light L, it determines "Yes" and proceeds to step S226 shown in "5-1" in FIG.

[0051] Next, in step S206, the laser control unit 114a resets the temperature error counter value to 0. In this case, the temperature error counter value is an integer value for counting the number of processing position temperature errors in which the processing position temperature, which will be described later, was not within the hardening temperature range.

[0052] Next, in step S208, the laser control unit 114a determines whether or not the temperature (hereinafter sometimes referred to as the "processing position temperature") at the position where the light spot SP is formed on the test piece TP (i.e., the position where the hardening process is performed) has reached the hardening temperature. Specifically, the laser control unit 114a identifies the temperature at the position where the light spot SP is formed on the test piece TP using the temperature detection signal output from the temperature detector 111, and determines whether or not the temperature at the position where the light spot SP is formed has reached the hardening temperature preset in the laser control unit 114a.

[0053] In this case, if the processing position temperature has reached the hardening temperature and is within the hardening temperature range, the laser control unit 114a determines "Yes" and proceeds to step S216 shown in "5-2" in FIG. 5. On the other hand, if the processing position temperature is not within the hardening temperature range, the laser control unit 114a determines "No" and proceeds to step S210. In this case, the laser control unit 114a stores information indicating whether the processing position temperature is lower or higher than the hardening temperature range. If it is determined in the determination process of this step S208 that the processing position temperature is not within the hardening temperature range, a processing position temperature error occurs.

[0054] Next, in step S210, the laser control unit 114a determines whether the number of processing position temperature errors has reached a predetermined number. Here, the predetermined number is preset in the laser control unit 114a via the operation panel 114c by the operator. In this embodiment, the predetermined number is set to three times. If the temperature error number counter value is equal to or less than the predetermined value, the laser control unit 114a determines "No" and proceeds to step S212 to increment the temperature error number counter value (add "1"), and then returns to step S208.

[0055] On the other hand, if the temperature error counter value exceeds the predetermined value, the laser control unit 114a determines "Yes" and proceeds to step S214. That is, the process in step S210 is a process for determining whether the processing position temperature error is a temporary error that occurred suddenly or accidentally, or whether the processing position temperature error is a definite error that occurs continuously.

[0056] Next, the laser control unit 114a performs a process of updating the hardening output value in step S214. This process of updating the hardening output value in step S214 is a process of changing the value of the hardening output value depending on whether the processing position temperature is high or low relative to the hardening temperature stored in step S208. Specifically, when the processing position temperature is low relative to the hardening temperature, the laser control unit 114a adds a predetermined value to the hardening output value to obtain a new hardening output value, and when the processing position temperature is high relative to the hardening temperature, the laser control unit 114a subtracts a predetermined value from the hardening output value to obtain a new hardening output value.

[0057] In this case, the predetermined value to be added to or subtracted from the hardening output value is set to a magnitude that can increase or decrease the processing position temperature by a predetermined temperature. In this embodiment, the predetermined value to be added to or subtracted from the hardening output value is set to 1 W. This predetermined value may be fixedly set in the laser control unit 114a, or may be arbitrarily set by the operator. Note that the predetermined value to be added to or subtracted from the hardening output value may be the same absolute value as the value to be added to and the value to be subtracted from the hardening output value, or may be different values. The intensity of the laser light L output from the laser light source 110 is changed by the hardening output value update process in step S216.

[0058] In the process of updating the quenching output value in step S214, since the initial value of the quenching output value is set to a value that cannot heat the surface of the test piece TP to the quenching temperature, the quenching output value increases until the surface temperature of the test piece TP reaches the quenching temperature. The output value of the laser light L when the quenching output value reaches the quenching temperature is stored as the quenching output value in the output value storage unit 114b. In other words, the processes of steps S208 and S214 correspond to the laser output increasing step according to the present invention. After executing step S214, the laser control unit 114a returns to step S204.

[0059] On the other hand, if it is determined in step S208 that the processing position temperature at the position where the light spot SP is formed has reached the hardening temperature, the laser control unit 114a starts measuring the optimum temperature elapsed time in step S216. Here, the optimum temperature elapsed time is the time elapsed since the processing position temperature reached the hardening temperature. Therefore, the laser control unit 114a starts measuring time using its own built-in timer function.

[0060] Next, in step S218, the laser control unit 114a executes a process of determining whether or not a predetermined time has elapsed since the time elapsed since the optimum temperature. Specifically, if the time elapsed since the optimum temperature began to be measured in step S216 has not reached a preset time, the laser control unit 114a determines "No" in this process and proceeds to step S220. On the other hand, if the time elapsed since the optimum temperature has reached a preset time, the laser control unit 114a determines "Yes" in this process and proceeds to step S224. Then, in step S224, the laser control unit 114a resets the value of the time elapsed since the optimum temperature, and proceeds to step S224.

[0061] That is, the process of determining the optimum temperature elapsed time in step S218 is a process of determining whether the processing position temperature has been maintained at the hardening temperature for a predetermined time. The predetermined time is set in advance in the laser control unit 114a by the operator. This predetermined time is not particularly limited, but according to experiments by the inventors, it is preferably 0.1 seconds or more and 1 second or less.

[0062] Next, if the appropriate temperature elapsed time has not reached the preset time, the laser control unit 114a determines in step S220 whether the processing position temperature at the position where the light spot SP is formed has reached the hardening temperature. The determination process in step S220 is the same as the determination process in step S208, and therefore its description will be omitted. The determination process in step S220 is a process for detecting whether the processing position temperature has deviated from the hardening temperature before the appropriate temperature elapsed time reaches the predetermined time.

[0063] In this determination process, if the processing position temperature is within the hardening temperature range, the laser control unit 114a determines "Yes" and returns to step S218. On the other hand, if the processing position temperature is not within the hardening temperature range, the laser control unit 114a determines "No" (i.e., "processing position temperature error") and proceeds to step S222. In this case, the laser control unit 114a stores information indicating whether the processing position temperature is lower or higher than the hardening temperature range. Then, in step S222, the laser control unit 114a resets the value of the optimum temperature elapsed time and returns to step S214 at "4-1" in FIG. 4.

[0064] On the other hand, if the laser control unit 114a detects an instruction to stop the laser light L in step S204, or if it determines in the judgment process in step S220 that the elapsed time at the appropriate temperature has reached a preset time, in step S226, it controls the operation of the laser driving unit 114 to stop the emission of the laser light L.

[0065] Next, in step S228, the laser control unit 114a executes a process for determining the quenching output value. Specifically, the laser control unit 114a stores the current quenching output value in the output value storage unit 114b as the quenching output value resulting from execution of this quenching output value setting subprogram. That is, in this quenching output value setting subprogram, in the process of changing the output value of the laser beam irradiated onto the test piece TP, the output value of the laser beam L that was first obtained when the processing position temperature was maintained at the quenching temperature for a predetermined time is stored as the quenching output value.

[0066] Then, the laser control unit 114a ends the execution of this hardening output value setting subprogram in step S230. Thereafter, the overall control device 120 ends the execution of this hardening output value setting program in step S112, as described above.

[0067] Next, the worker performs a hardening process on the workpiece WK. Specifically, the worker prepares the workpiece WK and sets it on the table 101, and then instructs the overall control device 120 to execute the hardening process. In response to this instruction, the overall control device 120 starts executing a hardening process program and performs the hardening process on the workpiece WK.

[0068] Specifically, the overall control device 120 controls the operation of the XY feed device 102 and the Z feed device 113 to position the workpiece WK relative to the laser light source 110, and then instructs the laser driver 114 to emit laser light L. Then, the overall control device 120 causes the laser light source 110 to emit laser light L onto the workpiece WK set on the table 101, forming a light spot SP, and then displaces the position of the table 101 in the X-axis, Y-axis, and Z-axis directions, thereby performing a hardening process on the portion of the workpiece WK specified by the operator.

[0069] During the execution of this hardening process, the laser control unit 114a in the laser driving unit 114 executes a laser output adjustment program shown in Fig. 6. The laser output adjustment program performs ON / OFF control and intensity control of the laser light L irradiated onto the workpiece WK during the execution of the hardening process program. Specifically, the laser control unit 114a starts execution of the laser output control program in step S300, and in step S302 controls the operation of the laser driving unit 114 to emit the laser light L.

[0070] In this case, the laser control unit 114a causes the laser light source 110 to emit laser light L at the quenching output value set by executing the quenching output value setting subprogram. As a result, a light spot SP with an intensity sufficient to heat the processing position temperature on the workpiece WK to the quenching temperature is formed. Experiments conducted by the inventors have confirmed that the processing position temperature on the workpiece WK can be heated to the quenching temperature in 0.5 to 1 second. In addition, the laser control unit 114a controls the operation of the temperature detector 111 to input a temperature detection signal representing the surface temperature of the test piece TP within the light spot SP, thereby starting detection of the surface temperature of the test piece TP.

[0071] Next, in step S304, the laser control unit 114a determines the end of the hardening process. The process of determining the end of the hardening process in step S304 is a process of determining the end of the hardening process for the workpiece WK. In this case, the laser control unit 114a determines the end of the hardening process by detecting that the laser light L has moved to the final position of the hardened portion of the workpiece WK.

[0072] Therefore, the laser control unit 114a continues to determine "No" until the laser light L reaches the final position of the hardened portion, and proceeds to step S306. On the other hand, when the laser light L has reached the final position of the hardened portion, the laser control unit 114a determines "Yes" and proceeds to step S318.

[0073] Next, in step S306, the laser control unit 114a resets the temperature error counter value to 0. In this case, the temperature error counter value is an integer value for counting the number of processing position temperature errors in which the processing position temperature was not within the hardening temperature range.

[0074] Next, in step S308, the laser control unit 114a determines whether the processing position temperature, which is the temperature at the position where the light spot SP is formed on the workpiece WK (i.e., the position where the hardening process is performed), is within the hardening temperature range. Specifically, the laser control unit 114a identifies the temperature at the position where the light spot SP is formed on the workpiece WK using the temperature detection signal output from the temperature detector 111, and determines whether the temperature at the position where the light spot SP is formed is within the hardening temperature range.

[0075] In this case, the hardening temperature range is the hardening temperature range preset in the laser control unit 114a. Therefore, if the processing position temperature is within the hardening temperature range, the laser control unit 114a determines "Yes" and returns to step S304. On the other hand, if the processing position temperature is not within the hardening temperature range, the laser control unit 114a determines "No" and proceeds to step S310. In this case, the laser control unit 114a stores information indicating whether the processing position temperature is lower or higher than the hardening temperature range. If it is determined in the determination process of step S308 that the processing position temperature is not within the hardening temperature range, a processing position temperature error occurs.

[0076] Next, in step S310, the laser control unit 114a determines whether the number of processing position temperature errors has reached a predetermined number. Here, the predetermined number is set in advance in the laser control unit 114a via the operation panel 114c by the operator. In this embodiment, the predetermined number is set to three times. If the temperature error number counter value is equal to or less than the predetermined value, the laser control unit 114a determines "No" and proceeds to step S212 to increment the temperature error number counter value (add "1"), and then returns to step S308.

[0077] On the other hand, if the temperature error counter value exceeds the predetermined value, the laser control unit 114a determines "Yes" and proceeds to step S314. That is, the process in step S310 is a process for determining whether the processing position temperature error is a temporary error that occurred suddenly or accidentally, or whether the processing position temperature error is a definite error that occurs continuously.

[0078] Next, in step S314, the laser control unit 114a performs a process of updating the hardening output value. This process of updating the hardening output value in step S314 is a process of changing the value of the hardening output value depending on whether the processing position temperature is high or low relative to the hardening temperature stored in step S308. Specifically, if the processing position temperature is low relative to the hardening temperature, the laser control unit 114a adds a predetermined value to the hardening output value to obtain a new hardening output value, and if the processing position temperature is high relative to the hardening temperature, the laser control unit 114a subtracts a predetermined value from the hardening output value to obtain a new hardening output value and stores the result in the output value storage unit 114b.

[0079] In this case, the predetermined value to be added to or subtracted from the hardening output value is set to a magnitude that can raise or lower the processing position temperature by the predetermined temperature. In this embodiment, the predetermined value to be added to or subtracted from the hardening output value is set to 1 W. This predetermined value may be fixedly set in the laser control unit 114a, or may be set arbitrarily by the operator. Note that the predetermined value to be added to or subtracted from the hardening output value may be the same absolute value for the value to be added to and the value to be subtracted from the hardening output value, or may be different values.

[0080] The intensity of the laser light L output from the laser light source 110 is changed by updating the hardening output value in step S314. Then, the laser control unit 114a returns to step S304. As a result, the intensity of the laser light L irradiated onto the workpiece WK is adjusted so as to constantly maintain the hardening temperature. After executing step S314, the laser control unit 114a returns to step S304.

[0081] On the other hand, if an instruction to stop the laser beam L is detected in the process of determining whether or not to stop the laser beam L in step S304, the laser control unit 114a controls the operation of the laser driver 114 in step S316 to stop the emission of the laser beam L, and ends the execution of the output control program for the laser beam L in step S318. In this case, the overall control device 120 ends the execution of the hardening process program and ends the hardening process for the workpiece WK. Therefore, the worker removes the workpiece WK from the table 101 and ends the hardening operation.

[0082] As can be understood from the above operation description, according to the above embodiment, the laser hardening device 100 starts irradiating the laser light L at a hardening output value, which is the output value of the laser light L that can heat the surface of the workpiece WK to the hardening temperature, so that the portion of the workpiece WK irradiated with the laser light L can be prevented from being overheated beyond the hardening temperature, and the accuracy of the hardening process can be improved.

[0083] Furthermore, the present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the scope of the present invention. In the following description of each modification and the accompanying drawings, the same reference numerals are used to designate the same components as those in the above-described embodiment, and their description will be omitted.

[0084] For example, in the above embodiment, the laser hardening apparatus 100 acquired the hardening output value of the laser beam L to be irradiated onto the workpiece WK by executing the hardening output value setting subprogram. However, the hardening output value of the laser beam L to be irradiated onto the workpiece WK can also be determined by a method other than executing the hardening output value setting subprogram. The hardening output value of the laser beam L to be irradiated onto the workpiece WK may be determined, for example, based on the experience of past hardening processes for the workpiece WK, or may be determined theoretically based on the specifications of the laser hardening apparatus 100, the specifications of the workpiece WK, and the processing conditions for the hardening process.

[0085] In the above embodiment, the hardening output value is set to a value that can maintain the surface temperature of the workpiece WK for the time required for hardening. This allows the laser hardening apparatus 100 to perform accurate hardening without requiring control to maintain the hardening temperature for at least the time required for hardening, even after the temperature of the portion to be hardened in the workpiece WK reaches the hardening temperature. However, the hardening output value may be set to a value that cannot maintain the surface temperature of the workpiece WK for the time required for hardening. For example, the hardening output value may be set to a value that heats the surface of the workpiece WK to the lower or upper limit of the hardening temperature. In these cases, the laser hardening apparatus 100 can maintain the hardening temperature for the time required for hardening, even after the temperature of the portion to be hardened reaches the hardening temperature, by executing the laser output control program, as in the above embodiment.

[0086] Furthermore, in the above embodiment, the quenching output value setting subprogram is configured to set the initial output value of the laser beam L at which the processing position temperature is maintained at the quenching temperature for a predetermined time as the quenching output value in the process of changing the output value of the laser beam irradiated onto the test piece TP. In other words, the quenching output value setting subprogram is configured to set the output value at that time as the quenching output value when the intensity (output value) of the laser beam L irradiated onto the test piece TP has stabilized without being changed for a predetermined time. However, the quenching output value setting subprogram can also be configured to determine the quenching output value by a method other than that of the above embodiment.

[0087] For example, the hardening output value setting subprogram can be configured to constantly monitor whether the output value is the largest during the process of changing the intensity (output value) of the laser light L irradiated onto the test piece TP, update the hardening output value while storing it, and set the hardening output value to the largest output value among the output values ​​of the laser light L when the execution of the hardening output value setting subprogram is terminated.

[0088] In addition, the hardening output value setting subprogram can be configured to store a history of changes to each output value each time the intensity (output value) of the laser light L irradiated onto the test piece TP is changed, and to set the largest output value among the history of changes to each output value as the hardening output value when the execution of the hardening output value setting subprogram is terminated.

[0089] Furthermore, in the above embodiment, the hardening output value setting subprogram is configured to update the hardening output value when the processing position temperature measured multiple times (three times) deviates from the hardening temperature (steps S208, S212, S214). However, the hardening output value setting subprogram can also be configured to update the hardening output value when the processing position temperature measured once deviates from the hardening temperature. That is, the hardening output value setting subprogram can be configured to omit the processes of steps S208, S212, and S214. Note that, like the hardening output value setting subprogram, the laser output adjustment program can also be configured to omit the processes of steps S306, S310, and S312.

[0090] In the above embodiment, the laser hardening apparatus 100 is configured to store a hardening output value for one type of workpiece WK. However, the laser hardening apparatus 100 can also store multiple hardening output values ​​for at least one of the types of workpiece WK, the sizes of the light spot SP, and the hardening depths. This allows the laser hardening apparatus 100 to perform hardening by appropriately selecting a hardening output value according to the type of workpiece WK or the specifications of the hardening process.

[0091] In the above embodiment, the laser hardening apparatus 100 is configured such that the output value storage unit 114b is provided in the laser driver 114 and the laser control unit 114a executes the hardening output value setting subprogram and the laser output adjustment program. In other words, the laser control unit 114a corresponds to the control device according to the present invention. As a result, the laser hardening apparatus 100 controls the output value of the laser light L within the laser driver 114, allowing for rapid control of the output intensity according to the temperature of the portion of the workpiece WK to be hardened. However, the laser hardening apparatus 100 can also be configured such that the output value storage unit 114b is provided in the overall control device 120 and the overall control device 120 executes the hardening output value setting subprogram and the laser output adjustment program. In other words, the overall control device 120 corresponds to the control device according to the present invention. In this case, the temperature detector 111 is configured to output a temperature detection signal to the overall control device 120.

[0092] Furthermore, in the above embodiment, the temperature detector 111 is configured to detect the temperature at the measurement position MP, which is the rear side of the light spot SP in the direction of travel of the light spot SP within the region where the light spot SP is formed on the surface of each of the test piece TP and workpiece WK (the rear side of the halfway point of the light spot SP in the direction of travel of the light spot SP). This allows the temperature detector 111 to detect the temperature of the test piece TP and workpiece WK that are sufficiently heated within the light spot SP, thereby improving the temperature detection accuracy. However, the temperature detector 111 may be configured to detect the temperature within the region where the light spot SP is formed on the surface of each of the test piece TP and workpiece WK.

[0093] In the above embodiment, the temperature detector 111 detects the temperatures of the test piece TP and the workpiece WK at the portions where the light spot SP is formed. That is, the temperature detector 111 corresponds to the object temperature detector and the workpiece temperature detector of the present invention, and serves as both of these detectors. However, it goes without saying that the temperature detector 111 may be provided separately and independently from the object temperature detector and the workpiece temperature detector of the present invention.

[0094] In the above embodiment, the laser hardening apparatus 100 is configured so as not to store the change history of the hardening output value in the hardening output value setting subprogram and the laser output adjustment program. However, the laser hardening apparatus 100 can improve traceability by executing an output value change history storage step in the hardening output value setting subprogram and / or the laser output adjustment program that stores the change history of the hardening output value, thereby leaving a record of the processing details of the workpiece WK and enabling tracking at a later date. Furthermore, by checking the change history of the output value of the laser light L, the operator can verify the validity of the hardening output value at the time of emission of the laser light L. [Explanation of symbols]

[0095] WK: Workpiece, TP: Test piece, L: Laser light, SP: Light spot, MP: Temperature measurement position by temperature detector. 100...laser hardening device, 101...table, 102...XY feeder, 110...laser light source, 111...temperature detector, 112...support, 113...Z feed device, 114...laser drive unit, 114a...laser control unit, 114b...output value storage unit, 114c...operation panel, 120...total control device, 121...operation panel, 122...display device.

Claims

1. A laser hardening device for forming a light spot by a laser beam on the surface of a workpiece to harden the surface, a laser light source that emits the laser light; a control device that controls the output of the laser light emitted from the laser light source; an output value storage unit that stores a hardening output value, which is an output value of the laser light that can heat the surface of the workpiece to a hardening temperature; an object temperature detector that outputs a temperature detection signal representing the temperature of the surface of the object on which the light spot is formed by irradiation from the laser light source, The control device a small-output laser light emitting step of emitting the laser light from the laser light source at an output value that is not enough to heat the object that is the same as or of the same type as the workpiece to the hardening temperature; a laser output increasing step of increasing an output value of the laser light emitted from the laser light source until the temperature detected using the temperature detection signal output by the object temperature detector reaches the hardening temperature; an output value of the laser beam when the temperature detected using the temperature detection signal output by the object temperature detector reaches the hardening temperature is stored in the output value storage unit as the hardening output value; a laser hardening device that starts emitting the laser light to the workpiece at the hardening output value;

2. 2. The laser hardening apparatus according to claim 1, The quenching output value is A laser hardening device characterized in that the temperature of the surface of the workpiece is a value that can be maintained at a temperature required for hardening.

3. 3. The laser hardening apparatus according to claim 1 or 2, The output value storage unit a laser hardening device for storing a plurality of hardening output values ​​for at least one of the type of workpiece, the size of the light spot, the feed rate of the light spot, and the hardening temperature.

4. The laser hardening apparatus according to any one of claims 1 to 3, further comprising: a workpiece temperature detector that outputs a temperature detection signal representing the temperature of the surface of the workpiece on which the light spot is formed by irradiation from the laser light source, The control device a laser driving unit that supplies laser driving power to the laser light source, and controls the operation of the laser driving unit using the temperature detection signal output by the workpiece temperature detector so that the temperature of the surface of the workpiece irradiated with the laser light maintains the hardening temperature.

5. 5. The laser hardening apparatus according to claim 1, The control device A laser hardening device characterized in that it stores a history of changes in the output value of the laser light for the workpiece.

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