Additive processing apparatus, additive processing method, and additive processing program

Abstract

This technology provides a method for dealing with thermal expansion during additional machining of a workpiece in a way different from conventional methods. [Solution] The additive processing apparatus comprises a laser head for performing additive processing on a workpiece; a first support unit that supports one side of the workpiece in the direction of a predetermined axis and supports the workpiece so as to be rotatable about the predetermined axis; a second support unit that supports the other side of the workpiece in the direction of a predetermined axis and supports the workpiece so as to be rotatable about the predetermined axis; a drive unit that moves the second support unit along the direction of the predetermined axis; a first detection unit that detects a physical quantity correlated with the torque applied to the drive unit; and a control unit. The control unit performs a process to control the drive unit so that the physical quantity detected by the first detection unit approaches a predetermined target value during additive processing of the workpiece or during cooling of the workpiece.

Description

Technical Field

[0001] The present disclosure relates to an additive processing apparatus, an additive processing method, and an additive processing program.

Background Art

[0002] Japanese Patent Application Laid-Open No. 2023-125537 (Patent Document 1) discloses a processing machine capable of maintaining high machining accuracy of a workpiece in additive processing of the workpiece using a directed energy deposition method. The processing machine includes an additive processing head that supplies a powder material to the workpiece and irradiates it with laser light, and a first holding portion and a second holding portion for rotatably holding the workpiece. The first holding portion and the second holding portion are provided opposite to each other in the direction of the rotation axis of the workpiece, and are configured to hold the workpiece from both sides.

[0003] When the workpiece is irradiated with laser light, the workpiece thermally expands (see paragraph

[0005] ). Therefore, when performing additive processing on the workpiece, the processing machine relatively moves the first holding portion and the second holding portion in a direction away from each other. Thereby, the processing machine suppresses the surface of the workpiece from being distorted between the first holding portion and the second holding portion, and improves the additive processing accuracy of the workpiece.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The processing machine disclosed in Patent Document 1 detects the temperature of a workpiece during additive manufacturing and calculates the amount of thermal expansion of the workpiece based on that temperature. The processing machine then moves the first and second holding parts apart by a distance corresponding to the calculated amount of thermal expansion. With such a system, surface distortion of the workpiece due to thermal expansion during additive manufacturing can be suppressed. However, if the shape of the workpiece is not a simple cylindrical shape or something close to it, but has a complex shape, calculating the amount of thermal expansion of the workpiece can take time.

[0006] In light of the above, there is a need for a technology that can address thermal expansion during additional processing of workpieces in a way different from conventional methods. [Means for solving the problem]

[0007] One example of the present disclosure provides an additive processing apparatus for performing additive processing on a workpiece. The additive processing apparatus includes a laser head capable of performing additive processing on a workpiece by supplying powder material to the workpiece and irradiating the workpiece with laser light; a first support part for supporting one side of the workpiece in the direction of a predetermined axis and for supporting the workpiece so as to be rotatable about the predetermined axis; a second support part for supporting the other side of the workpiece in the direction of the predetermined axis and for supporting the workpiece so as to be rotatable about the predetermined axis; a drive unit for moving the second support unit along the direction of the predetermined axis; a first detection unit for detecting a physical quantity correlated with the torque applied to the drive unit; and a control unit for controlling the additive processing apparatus. The control unit performs a process to control the drive unit so that the physical quantity detected by the first detection unit approaches a predetermined target value during additive processing of the workpiece or during cooling of the workpiece.

[0008] In one example of this disclosure, the additive processing apparatus further includes a second detection unit for detecting the position of the second support unit in the direction of the predetermined axis. The control unit further performs a process to monitor whether the position is within a preset range while it is performing a process to control the drive unit, and a process to perform a predetermined abnormality handling process if the position falls outside the preset range.

[0009] In one example of this disclosure, the abnormality handling process includes a process of switching from a process that controls the drive unit so that the physical quantity approaches the predetermined target value to a process that controls the drive unit so that the position detected by the second detection unit approaches the target position.

[0010] In one example of this disclosure, the above-mentioned abnormality handling process includes a process that outputs a warning indicating that the above-mentioned position is outside the above-mentioned preset range.

[0011] In one example of this disclosure, the first support is a first workpiece spindle having a chuck mechanism for gripping one side of the workpiece. The second support is a second workpiece spindle having a chuck mechanism for gripping the other side of the workpiece.

[0012] In one example of this disclosure, the first support is a workpiece spindle having a chuck mechanism for gripping one side of the workpiece. The second support is a tailstock having a tailstock mechanism for tailoring the other side of the workpiece.

[0013] Another example of this disclosure provides an additive processing apparatus for performing additive processing on a workpiece. The additive processing apparatus comprises a laser head capable of performing additive processing on a workpiece by supplying powder material to the workpiece and irradiating the workpiece with laser light; a first support unit for gripping one side of the workpiece in the direction of a predetermined axis and for gripping the workpiece so as to be rotatable about the predetermined axis; a second support unit for gripping the other side of the workpiece in the direction of the predetermined axis and for gripping the workpiece so as to be rotatable about the predetermined axis; a drive unit for moving the second support unit along the direction of the predetermined axis; and a control unit for controlling the additive processing apparatus. The control unit executes a process to disable the control processing of the drive unit when the workpiece is being processed or when the workpiece is being cooled.

[0014] Another example of this disclosure provides a method for additive processing a workpiece using an additive processing apparatus. The additive processing apparatus includes a laser head capable of performing additive processing on a workpiece by supplying a powder material to the workpiece and irradiating the workpiece with laser light; a first support portion for supporting one side of the workpiece in the direction of a predetermined axis and for supporting the workpiece so as to be rotatable about the predetermined axis; and a second support portion for supporting the other side of the workpiece in the direction of the predetermined axis and for supporting the workpiece so as to be rotatable about the predetermined axis. The system includes a drive unit for moving the second support unit along the direction of the predetermined axis, and a first detection unit for detecting a physical quantity correlated with the torque applied to the drive unit. The additional machining method includes a step of controlling the drive unit so that the physical quantity detected by the first detection unit approaches a predetermined target value during additional machining of the workpiece or during cooling of the workpiece.

[0015] Another example of this disclosure provides a program for additive processing of a workpiece using an additive processing apparatus. The additive processing apparatus includes a laser head capable of performing additive processing on a workpiece by supplying powder material to the workpiece and irradiating the workpiece with laser light; a first support part for supporting one side of the workpiece in the direction of a predetermined axis and for supporting the workpiece so as to be rotatable about the predetermined axis; a second support part for supporting the other side of the workpiece in the direction of the predetermined axis and for supporting the workpiece so as to be rotatable about the predetermined axis; a drive unit for moving the second support unit along the direction of the predetermined axis; and a first detection unit for detecting a physical quantity correlated with the torque applied to the drive unit. The additive processing program causes the additive processing apparatus to execute a process that controls the drive unit so that the physical quantity detected by the first detection unit approaches a predetermined target value during additive processing of the workpiece or during cooling of the workpiece.

[0016] The above and other objects, features, aspects and advantages of the present invention will become apparent from the following detailed description relating to the invention, which will be understood in conjunction with the accompanying drawings. [Brief explanation of the drawing]

[0017] [Figure 1] This figure shows an example of the appearance of an additive processing device. [Figure 2] This figure shows an example of the configuration of an additive processing device. [Figure 3] This figure shows a cross-section of the laser head during additive processing. [Figure 4] This diagram schematically shows the control method of the second workpiece spindle during additional machining. [Figure 5] This diagram schematically shows the control mode of the second workpiece spindle after the completion of the additional machining process. [Figure 6] This diagram schematically illustrates the position monitoring function of the second workpiece spindle. [Figure 7] This figure shows an example of a warning screen. [Figure 8] This figure shows an example of a drive mechanism for an additive processing device. [Figure 9] It is a diagram showing an example of the hardware configuration of the control unit. [Figure 10] It is a flowchart showing the flow of the additional processing. [Figure 11] It is a diagram for explaining a modified example of the control method of the second work spindle.

Embodiments for Carrying Out the Invention

[0018] Hereinafter, each embodiment according to the present invention will be described while referring to the drawings. In the following description, the same parts and components are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed descriptions thereof will not be repeated. In addition, each embodiment and each modified example described below may be selectively combined as appropriate.

[0019] <A. Appearance of the Additional Processing Device 100> First, referring to FIG. 1, the additional processing device 100 according to the embodiment will be described. FIG. 1 is a diagram showing an example of the appearance of the additional processing device 100.

[0020] The additional processing device 100 is a processing machine capable of performing additional processing (AM (Additive manufacturing) processing) on a work. The additional processing device 100 performs additional processing by supplying a powder material to the work and irradiating the work with a laser beam.

[0021] Note that the additional processing device 100 may be a processing machine capable of not only additional processing of the work but also removal processing (SM (Subtractive manufacturing)) of the work. Examples of the removal processing function include a milling function and a turning function.

[0022] The additional processing device 100 includes, for example, a cover body 130 and an operation panel 200.

[0023] The cover body 130 is a mechanism for protecting the components provided inside the additional processing device 100. A door DR is provided on the cover body 130. The door DR is, for example, a sliding door. The door DR may be configured to be opened and closed by a drive source such as a motor, or may be configured to be opened and closed manually.

[0024] The operation panel 200 is a general-purpose computer and has a display for displaying various information related to processing. The display is, for example, a liquid crystal display, an organic EL (Electro Luminescence) display, or other display device. Further, the display is provided with a touch panel and accepts various operations on the additional processing device 100 by touch operation.

[0025] <B. Device Configuration of Additional Processing Device 100> Next, referring to FIG. 2, the device configuration of the additional processing device 100 will be described. FIG. 2 is a diagram showing an example of the device configuration of the additional processing device 100. In FIG. 2, as an example of the additional processing device 100, an AM / SM hybrid processing machine capable of both additional processing and removal processing of a workpiece is shown.

[0026] As described above, the additional processing device 100 includes a cover body 130. The cover body 130 forms the appearance of the additional processing device 100 and partitions and forms a processing area AR for performing additional processing on the workpiece W.

[0027] Further, the additional processing device 100 includes a bed 11, a tool rest 16, a first support portion 21, a second support portion 24, a tool spindle 30, and a laser head 140.

[0028] For the sake of explanation, the rotation axis direction of the first support part 21 and the second support part 24 will also be referred to as the "Z axis direction" below. In the example in Figure 2, the Z axis direction is parallel to the rotation axes AX1 to AX3. Furthermore, one side of the Z axis direction will be referred to as the "positive Z axis direction side," and the other side of the Z axis direction will be referred to as the "negative Z axis direction side." In the example in Figure 2, the right side when viewing the machining area AR from the door DR is the "positive Z axis direction side." Also, in the example in Figure 2, the left side when viewing the machining area AR from the door DR is the "negative Z axis direction side."

[0029] Furthermore, one direction on the horizontal plane perpendicular to the Z-axis direction is also called the "Y-axis direction." Additionally, one side of the Y-axis direction is called the "positive Y-axis side," and the other side of the Y-axis direction is called the "negative Y-axis side."

[0030] Furthermore, the direction perpendicular to both the Y-axis and Z-axis directions is also referred to as the "X-axis direction." Additionally, one side of the X-axis direction is called the "positive X-axis direction," and the other side is called the "negative X-axis direction." In the example in Figure 2, the negative X-axis direction corresponds to the direction of gravity.

[0031] The bed 11 is a base member for supporting various devices within the additive processing apparatus 100. In the example shown in Figure 2, the bed 11 supports the tool post 16, the first support section 21, the second support section 24, the tool spindle 30, and the laser head 140. The bed 11 is installed on the floor of a factory or similar facility. The bed 11 is made of a metal such as cast iron.

[0032] The tool post 16 has a turret 18. The turret 18 is configured to rotate around the rotation axis AX1. The turret 18 holds multiple tools spaced apart in the circumferential direction around the rotation axis AX1. The tool post 16 is also configured to move in the X-axis and Y-axis directions by various drive mechanisms such as a motor. The tool post 16 performs turning by bringing the fixed tools held in the turret 18 into contact with the workpiece W, which is rotationally driven by the first support part 21.

[0033] The first support portion 21 is configured to support one side of the workpiece W in the direction of the rotation axis AX2. The rotation axis AX2 is in a direction along the axial direction of the first support portion 21. The first support portion 21 is also configured to be rotatable about the rotation axis AX2, which is in its axial direction. The first support portion 21 is rotationally driven, for example, by 212C (see Figure 8), which will be described later.

[0034] Any mechanism can be used for supporting the workpiece W by the first support part 21. Figure 2 shows a first workpiece spindle 22 as an example of the first support part 21. The first workpiece spindle 22 is provided with a chuck mechanism 23 for gripping one side of the workpiece W. The chuck mechanism 23 is a mechanism for fixing the workpiece W to the first workpiece spindle 22.

[0035] The second support portion 24 is positioned opposite the first support portion 21 in the axial direction of the rotation axis AX2 or rotation axis AX3. The rotation axis AX3 is in a direction along the axial direction of the first support portion 21 and is coaxial with the rotation axis AX2. In other words, the second support portion 24 is configured to support the other side of the workpiece W in the direction of the rotation axis AX3.

[0036] The rotation axis AX3 is aligned with the axial direction of the second support portion 24. The second support portion 24 is configured to rotate about the rotation axis AX3, which is aligned with its axial direction. The second support portion 24 is configured to rotate, for example, in response to the rotation of the first support portion 21.

[0037] Any mechanism can be used for the support mechanism of the workpiece W by the second support part 24. Figure 2 shows a second workpiece spindle 25 as an example of the second support part 24. The second workpiece spindle 25 is provided with a chuck mechanism 26 for gripping the other side of the workpiece W. The chuck mechanism 26 is a mechanism for fixing the workpiece W to the second workpiece spindle 25.

[0038] As another example, the second support portion 24 may be a tailstock (not shown). The tailstock is provided with a tailing mechanism for supporting the other side of the workpiece W. In this case, the tailstock is provided with a center pin (not shown) instead of a chuck mechanism 26. The center pin has a pin shape that extends in the direction of the rotation axis AX3. As a result, the center pin tails the end face of the workpiece W from the side opposite to the first support portion 21.

[0039] In the following explanation, we will assume that the first support portion 21 is the first work spindle 22, but the first support portion 21 is not limited to the first work spindle 22. Also, in the following explanation, we will assume that the second support portion 24 is the second work spindle 25, but the second support portion 24 is not limited to the second work spindle 25.

[0040] The tool spindle 30 is positioned higher than, for example, the first work spindle 22 and the second work spindle 25. The tool spindle 30 is also configured to allow for the attachment and detachment of the tool and the laser head 140. Figure 2 shows an example in which the laser head 140 is mounted on the tool spindle 30.

[0041] The attachment and detachment of the laser head 140 to the tool spindle 30 is achieved, for example, by an automatic tool changer (ATC). When performing additional machining on the workpiece W, the additive machining device 100 attaches the laser head 140 to the tool spindle 30. On the other hand, when performing removal machining on the workpiece W, the additive machining device 100 attaches a tool to the tool spindle 30.

[0042] One example of material removal is milling, in which a rotating tool is brought into contact with a workpiece W fixed to the first workpiece spindle 22. Another example of material removal is turning, in which a tool is pressed against a workpiece W rotating around a rotation axis AX2.

[0043] The laser head 140 performs additive manufacturing by the DED (Direct Energy Deposition) method while being mounted on the tool spindle 30. As a mechanism for realizing additive manufacturing, the laser head 140 has a head body 142 and a laser nozzle 146.

[0044] Powder material is supplied to the head body 142 via a cable (not shown). The supplied powder material may be metal powder, resin powder, or other types of powder that melt upon irradiation with laser light.

[0045] The laser nozzle 146 irradiates the workpiece W with laser light and defines the laser light irradiation region on the workpiece W. The powder material supplied to the laser head 140 is discharged toward the workpiece W through the laser nozzle 146.

[0046] <C. Additive Manufacturing> Next, referring to FIG. 3, the additive manufacturing by the laser head 140 will be described in more detail. FIG. 3 is a diagram showing a cross-section of the laser head 140 during additive manufacturing.

[0047] The additive manufacturing apparatus 100 can realize various additive manufacturing processes by controlling the laser head 140. Examples of the types of additive manufacturing include lamination processing and coating processing. Lamination processing is a process of stacking layers SL on the workpiece W. Coating processing is a process of covering part or all of the surface of the workpiece W with a layer SL.

[0048] The additive manufacturing apparatus 100 according to the embodiment is configured to enable high-speed additive manufacturing. Examples of high-speed additive manufacturing techniques include, for example, EHLA (Extreme High-speed Laser Application).

[0049] More specifically, while moving in the Z-axis direction, the laser head 140 irradiates the rotating workpiece W with the laser beam LS. As a result, the irradiated portion of the laser beam LS melts, and a molten pool MP is formed on the workpiece W.

[0050] Also, while irradiating the laser beam LS, the laser head 140 supplies the powder material PM to the workpiece W. The supplied powder material PM melts before reaching the surface of the workpiece W by the laser beam LS. As a result, the molten powder material PM is put into the molten pool MP. When the molten pool MP hardens on the workpiece W, it becomes a layer SL.

[0051] Note that the additive processing by the additive processing device 100 does not necessarily have to be high-speed additive processing. As an example, the additive processing device 100 may realize the additive processing of the workpiece W by additive processing that rotates the first workpiece spindle 22 at a low speed. In this case, the additive processing device 100 performs the additive processing with the focus F of the laser beam LS positioned on the surface of the workpiece W.

[0052] <D. Control Method of the Second Workpiece Spindle 25 During Additive Processing> Next, referring to FIG. 4, the control method of the second workpiece spindle 25 during additive processing will be described. FIG. 4 is a diagram schematically showing the control mode of the second workpiece spindle 25 during additive processing.

[0053] As described above, the second workpiece spindle 25 is configured to be movable along its axial direction (i.e., the Z-axis direction). The movement is driven by a motor 222Z (drive unit). The drive of the motor 222Z is controlled by the control unit 50 of the additive processing device 100.

[0054] Furthermore, the additive processing device 100 is equipped with a sensor 322 (first detection unit). The sensor 322 is a sensor for detecting a physical quantity correlated with the torque applied to the motor 222Z. This physical quantity is, for example, the output current to the motor 222Z. In this case, the sensor 322 is a current sensor and detects the magnitude (load current value) of the output current to the motor 222Z. The current value detected by the sensor 322 is output to the control unit 50.

[0055] Another example of the above physical quantity is the load on the drive shaft of the motor 222Z. In this case, the sensor 322 is a torque sensor installed on the drive shaft of the motor 222Z, and it directly detects the load (torque) on the drive shaft.

[0056] For the sake of explanation, in the following, the physical quantity correlated with the torque applied to the motor 222Z will also be simply referred to as "torque."

[0057] In step S1, the control unit 50 holds the workpiece W with the first work spindle 22 and the second work spindle 25. Next, the control unit 50 controls the first work spindle 22 to rotate the workpiece W. As a result, the workpiece W rotates around the Z-axis direction. Subsequently, the control unit 50 controls the operation of the laser head 140 to perform additional machining on the workpiece W held by the first work spindle 22 and the second work spindle 25. As a result, the laser head 140 supplies powder material PM and irradiates the rotating workpiece W with laser light LS.

[0058] During the additional processing of the workpiece W, when the laser beam LS is irradiated onto the workpiece W, the workpiece W undergoes thermal expansion. At this time, if both the first workpiece spindle 22 and the second workpiece spindle 25 are fixed to the additional processing device 100, the surface of the workpiece W will be distorted so as to protrude radially outward from the axis of rotation. However, in the additional processing device 100 according to this embodiment, the second workpiece spindle 25 is configured to be movable along its axial direction (i.e., the Z-axis direction). Therefore, the second workpiece spindle 25 moves in accordance with the elongation of the workpiece W in the positive Z-axis direction. In step S2, the workpiece W has elongated by a length ΔL1 in the positive Z-axis direction due to thermal expansion compared to step S1.

[0059] According to this embodiment, the control unit 50 controls the motor 222Z during additional machining of the workpiece so that the torque detected by the sensor 322 approaches a predetermined target value. In other words, the control unit 50 controls the motor 222Z so that the torque detected by the sensor 322 remains constant. The target value is set, for example, to a predetermined percentage (for example, 90 percent) of the maximum allowable torque.

[0060] In the following, the control method that keeps the torque of motor 222Z constant will also be referred to as "torque feedback control." Torque feedback control may be implemented by PI (Proportional-Integral) control, PD (Proportional-Differential) control, or PID (Proportional-Integral-Differential) control.

[0061] More specifically, the control unit 50 controls the motor 222Z to drive the second work spindle 25 in the positive Z-axis direction if the torque detected by the sensor 322 is greater than a predetermined target value. In the example in Figure 4, the control unit 50 moves the second work spindle 25, which was at position "ZR1" in step S1, in the positive Z-axis direction by a length of "ΔZ1" in step S2. As a result, the second work spindle 25 is driven to position "ZR2".

[0062] Thus, it is possible to suppress the surface of the workpiece W from being distorted as the workpiece W thermally expands. As a result, the additive processing apparatus 100 can laminate the powder material PM at an intended position on the surface of the workpiece W, and can perform high-precision additive processing on the workpiece W. Further, the additive processing apparatus 100 can cope with the thermal expansion of the workpiece W without simulating the amount of thermal expansion of the workpiece.

[0063] In the above description, an example in which the second workpiece spindle 25 is driven in the Z-axis direction in response to the thermal expansion of the workpiece W has been described. However, the first workpiece spindle 22 may be driven in the Z-axis direction in response to the thermal expansion of the workpiece W. Alternatively, both the first workpiece spindle 22 and the second workpiece spindle 25 may be driven in the Z-axis direction in response to the thermal expansion of the workpiece W.

[0064] <E. Control Method of the Second Workpiece Spindle 25 When the Workpiece is Cooled> Next, referring to FIG. 5, a control method of the second workpiece spindle 25 when the workpiece is cooled will be described. FIG. 5 is a diagram schematically showing a control mode of the second workpiece spindle 25 when the workpiece is cooled.

[0065] In step S3, it is assumed that the additive processing of the workpiece W is completed. Accordingly, the control unit 50 controls the laser head 140 to stop the supply of the powder material PM and the irradiation of the laser light LS. Thereafter, as the temperature of the workpiece W decreases, the workpiece W thermally contracts. Since the first workpiece spindle 22 is fixed, the workpiece W contracts in the negative Z-axis direction. In step S4, the workpiece W contracts by an amount ΔL2 in the negative Z-axis direction due to thermal contraction as compared with step S3. At this time, if the position of the second workpiece spindle 25 is fixed, residual stress may occur in the workpiece W.

[0066] Therefore, the control unit 50 continues torque feedback control even after the additional processing of the workpiece. More specifically, when the torque detected by the sensor 322 is smaller than a predetermined target value, the control unit 50 controls the motor 222Z so as to drive the second workpiece spindle 25 in the negative Z-axis direction. In the example of FIG. 5, the control unit 50 moves the second workpiece spindle 25, which was at the position "ZR3" in step S3, in the negative Z-axis direction by the length of "ΔZ2" in step S4. As a result, the second workpiece spindle 25 is driven to the position "ZR4".

[0067] Thereby, it is possible to suppress the residual stress from remaining in the workpiece W after the additional processing of the workpiece W. As a result, the quality of the workpiece W after the additional processing is improved.

[0068] In the above description, an example in which the second workpiece spindle 25 is driven in the Z-axis direction according to the thermal contraction of the workpiece W has been described. However, the first workpiece spindle 22 may be driven in the Z-axis direction according to the thermal contraction of the workpiece W. Alternatively, both the first workpiece spindle 22 and the second workpiece spindle 25 may be driven in the Z-axis direction according to the thermal contraction of the workpiece W.

[0069] <F. Position monitoring function> As described above, when performing the additional processing of the workpiece W, the control unit 50 executes the above-described torque feedback control. As a result, the position of the second workpiece spindle 25 moves according to the thermal expansion and thermal contraction of the workpiece W. At this time, preferably, the control unit 50 monitors the position of the second workpiece spindle 25 so that the position of the second workpiece spindle 25 does not deviate from the normal range.

[0070] Hereinafter, the position monitoring function of the second workpiece spindle 25 will be described with reference to FIG. 6. FIG. 6 is a diagram schematically showing the position monitoring function of the second workpiece spindle 25.

[0071] The additive machining apparatus 100 is equipped with a position sensor 324 for detecting the position of the second workpiece spindle 25 in the direction of movement (i.e., the Z-axis direction). The type of position sensor 324 is arbitrary. For example, the position sensor 324 is a linear encoder. The position detected by the position sensor 324 is output to the control unit 50.

[0072] Before the start of the additional machining in step S11, the control unit 50 holds the workpiece W with the first workpiece spindle 22 and the second workpiece spindle 25. At this time, the control unit 50 obtains the position "ZR1" of the second workpiece spindle 25 from the position sensor 324 and sets the normal range ΔR with this position "ZR1" as the reference position. The lower limit of the normal range ΔR is, for example, the value obtained by subtracting a predetermined value (for example, 5 mm) from the reference position "ZR1". The upper limit of the normal range ΔR is, for example, the value obtained by adding a predetermined value (for example, 5 mm) to the reference position "ZR1".

[0073] In step S12, the control unit 50 starts additional machining based on the torque feedback control described above. While the torque feedback control is being performed, the control unit 50 periodically acquires the current position of the second workpiece spindle 25 and monitors whether the acquired current position is within a preset normal range ΔR. If the current position of the second workpiece spindle 25 falls outside the normal range ΔR, the control unit 50 executes a predetermined abnormality handling process.

[0074] As an example of abnormality handling, the control unit 50 executes a process to stop the additional processing. In this case, the control unit 50 controls the laser head 140 to stop the supply of powder material PM and the irradiation of laser light LS.

[0075] As another example of abnormality handling, the control unit 50 stops the drive process of the motor 222Z based on the torque feedback control described above and executes a process to control the motor 222Z so as to maintain the position of the second work spindle 25 at its current position. That is, the control unit 50 switches from torque feedback control, which keeps the torque applied to the second work spindle 25 constant, to position feedback control, which keeps the position of the second work spindle 25 constant. This prevents the position of the second work spindle 25 from deviating significantly from the normal range ΔR.

[0076] More specifically, the control unit 50 controls the motor 222Z to drive the second work spindle 25 to the negative side in the Z-axis direction if the position detected by the position sensor 324 is greater than a predetermined target position. On the other hand, the control unit 50 controls the motor 222Z to drive the second work spindle 25 to the positive side in the Z-axis direction if the position detected by the position sensor 324 is smaller than a predetermined target position.

[0077] The predetermined target position described above is switched as appropriate depending on whether the position of the second work spindle 25 exceeds the upper limit of the normal range ΔR or falls below the lower limit of the normal range ΔR. More specifically, if the position of the second work spindle 25 exceeds the upper limit of the normal range ΔR, the control unit 50 sets the predetermined target position to the upper limit of the normal range ΔR. On the other hand, if it falls below the lower limit of the normal range ΔR, the control unit 50 sets the predetermined target position to the lower limit of the normal range ΔR.

[0078] As yet another example of abnormality handling processing, the control unit 50 executes a process to output a warning indicating that the position of the second work spindle 25 is outside the normal range ΔR. Figure 7 shows an example of the warning screen IM.

[0079] The warning screen IM includes a warning message MS indicating, for example, that the position of the second work spindle 25 is out of the normal range ΔR. The output destination of the warning screen IM may be the display of the additional processing device 100, or may be the display of a terminal different from the additional processing device 100 (for example, a management device or a server). Thereby, the operator can recognize that the position of the second work spindle 25 is out of the normal range ΔR.

[0080] <G. Drive mechanism of the additional processing device 100> Next, referring to FIG. 8, the drive mechanism in the additional processing device 100 will be described. FIG. 8 is a diagram showing an example of the drive mechanism of the additional processing device 100.

[0081] As shown in FIG. 8, the additional processing device 100 includes a control unit 50 and drive units 210, 220, 230A, 230B, 240.

[0082] The control unit 50 controls various devices within the additional processing device 100. The device configuration of the control unit 50 is arbitrary. The control unit 50 may be composed of a single control unit or may be composed of a plurality of control units. As an example, the control unit 50 includes at least one of a CNC (Computer Numerical Control) and a PLC (Programmable Logic Controller). Further, the control unit 50 may include at least one of the motor drivers 211C, 221Z, 231X to 231Z, 231A, 231B, 241Y, 241Z, 241C shown in FIG. 8.

[0083] The drive unit 210 is a drive mechanism for rotationally driving the first work spindle 22. The drive unit 210 may be composed of a single drive unit or may be composed of a plurality of drive units. In the example of FIG. 8, the drive unit 210 is composed of a motor driver 211C and a motor 212C.

[0084] The motor driver 211C sequentially receives input of a target rotation angle or target rotation speed of the first workpiece spindle 22 from the control unit 50 and outputs a current to the motor 212C corresponding to the target rotation angle or target rotation speed. As a result, the workpiece held by the first workpiece spindle 22 rotates with the Z-axis direction as the center of rotation. The motor 212C may be an AC motor, a stepping motor, a servo motor, or any other type of motor.

[0085] The drive unit 220 is a drive mechanism for driving the second workpiece spindle 25. The drive unit 220 may consist of a single drive unit or multiple drive units. In the example shown in Figure 8, the drive unit 220 consists of a motor driver 221Z and a motor 222Z.

[0086] The motor driver 221Z sequentially receives input of a target position for the second workpiece spindle 25 from the control unit 50 and outputs a current corresponding to the target position to the motor 222Z. As a result, the motor 222Z moves the second workpiece spindle 25 to any position in the Z-axis direction. The motor 222Z may be an AC motor, a stepping motor, a servo motor, or any other type of motor.

[0087] The drive unit 230A is a drive mechanism for moving the position of the tool spindle 30. The laser head 140 described above is driven by being mounted on the tool spindle 30. The drive unit 230A may consist of a single drive unit or multiple drive units. In the example in Figure 8, the drive unit 230A consists of motor drivers 231X~231Z and motors 232X~232Z.

[0088] The motor driver 231X sequentially receives input from the control unit 50 regarding the target position of the tool spindle 30 in the X-axis direction, and outputs a current corresponding to the target position to the motor 232X. This allows the motor 232X to drive the tool spindle 30 to any position in the X-axis direction. The motor 232X may be an AC motor, a stepping motor, a servo motor, or any other type of motor.

[0089] The motor driver 231Y sequentially receives input from the control unit 50 regarding the target position of the tool spindle 30 in the Y-axis direction, and outputs a current corresponding to that target position to the motor 232Y. This allows the motor 232Y to drive the tool spindle 30 to any position in the Y-axis direction. The motor 232Y may be an AC motor, a stepping motor, a servo motor, or any other type of motor.

[0090] The motor driver 231Z sequentially receives input from the control unit 50 regarding the target position of the tool spindle 30 in the Z-axis direction, and outputs a current corresponding to the target position to the motor 232Z. As a result, the motor 232Z moves the tool spindle 30 to any position in the Z-axis direction. The motor 232Z may be an AC motor, a stepping motor, a servo motor, or any other type of motor.

[0091] The drive unit 230B is a drive mechanism for rotationally driving the tool spindle 30. The drive unit 230B may consist of a single drive unit or multiple drive units. In the example shown in Figure 8, the drive unit 230B consists of motor drivers 231A and 231B and motors 232A and 232B.

[0092] The motor driver 231A sequentially receives input from the control unit 50 for a target rotation angle or target rotation speed of the tool spindle 30 centered on the Y-axis direction, and outputs a current to the motor 232A corresponding to the target rotation angle or target rotation speed. The motor 232A rotates the tool spindle 30 around the Y-axis direction. The motor 232A may be an AC motor, a stepping motor, a servo motor, or any other type of motor.

[0093] The motor driver 231B sequentially receives input from the control unit 50 for a target rotation angle or target rotation speed of the tool spindle 30, with the axial direction of the tool spindle 30 as the rotation center, and outputs a current to the motor 232B corresponding to the target rotation angle or target rotation speed. The motor 232B rotates the tool spindle 30 with the axial direction of the tool spindle 30 as the rotation center. The motor 232B may be an AC motor, a stepping motor, a servo motor, or any other type of motor.

[0094] The drive unit 240 is a drive mechanism for driving the tool post 16 and the turret 18. The drive unit 240 may consist of a single drive unit or multiple drive units. In the example in Figure 8, the drive unit 240 consists of motor drivers 241C, 241Y, and 241Z, and motors 242C, 242Y, and 242Z.

[0095] The motor driver 241C receives a target value input regarding the rotation angle of the turret 18 around the Z-axis direction and outputs a current to the motor 242C corresponding to that target value. In this way, the motor driver 241C controls the rotation angle of the turret 18 with the Z-axis direction as the center of rotation. The motor 242C may be an AC motor, a stepping motor, a servo motor, or any other type of motor.

[0096] The motor driver 241Y sequentially receives the input of the target position of the tool post 16 in the X-axis direction from the control unit 50, and outputs a current corresponding to the target position to the motor 242Y. Thereby, the motor 242Y moves the tool post 16 to an arbitrary position in the X-axis direction. The motor 242Y may be an AC motor, a stepping motor, a servo motor, or other types of motors.

[0097] The motor driver 241Z sequentially receives the input of the target position of the tool post 16 in the Z-axis direction from the control unit 50, and outputs a current corresponding to the target position to the motor 242Z. Thereby, the motor 242Z moves the tool post 16 to an arbitrary position in the Z-axis direction. The motor 242Z may be an AC motor, a stepping motor, a servo motor, or other types of motors.

[0098] <H. Hardware Configuration of Control Unit 50> Next, referring to FIG. 9, the hardware configuration of the control unit 50 shown in FIG. 8 will be described. FIG. 9 is a diagram showing an example of the hardware configuration of the control unit 50.

[0099] As described above, the control unit 50 may be a CNC or a PLC. FIG. 9 shows the hardware configuration of the control unit 50 as a CNC.

[0100] The control unit 50 includes, for example, a control circuit 101, a ROM (Read Only Memory) 102, a RAM (Random Access Memory) 103, a communication interface 104, and an auxiliary storage device 120. These components are connected to an internal bus 109.

[0101] The control circuit 101 is comprised of, for example, at least one integrated circuit. The integrated circuit may consist of, for example, at least one CPU (Central Processing Unit), at least one GPU (Graphics Processing Unit), at least one ASIC (Application Specific Integrated Circuit), at least one FPGA (Field Programmable Gate Array), or a combination thereof.

[0102] The control circuit 101 controls the operation of the control unit 50 by executing various programs, such as the control program 122. The control program 122 is a program for realizing the various processes described herein. Based on receiving an execution command for the control program 122, the control circuit 101 reads the control program 122 from the ROM 102 into the RAM 103. The RAM 103 functions as working memory and temporarily stores various data necessary for the execution of the control program 122.

[0103] The communication interface 104 is an interface for enabling communication with various devices. The additive machining device 100 communicates with various drive units (for example, the drive units 210, 220, 230A, 230B, 240, etc.) for performing additive machining on a workpiece via the communication interface 104.

[0104] The auxiliary storage device 120 is, for example, a storage medium such as a hard disk or flash memory. The auxiliary storage device 120 stores the control program 122 and the like. The storage location of the control program 122 is not limited to the auxiliary storage device 120, but may also be stored in the storage area of ​​the control circuit 101 (for example, cache memory), ROM 102, RAM 103, external devices (for example, a server), etc.

[0105] Further, the control program 122 may be provided not as a single program but incorporated into a part of an arbitrary program. In this case, various processes according to this embodiment are realized in cooperation with an arbitrary program. Even a program that does not include such a part of the module does not deviate from the gist of the control program 122 according to this embodiment. Further, part or all of the functions provided by the control program 122 may be realized by dedicated hardware. Further, the control unit 50 may be configured in a form such as a so-called cloud service in which at least one server executes a part of the processing of the control program 122.

[0106] <I. Control Flow of Additional Processing> Next, referring to FIG. 10, the control flow of the additional processing will be described. FIG. 10 is a flowchart showing the flow of the additional processing.

[0107] The processing shown in FIG. 10 is realized, for example, when the control unit 50 of the additional processing device 100 executes the above-described control program 122. In other aspects, part or all of the processing may be executed by circuit elements or other hardware.

[0108] In step S110, the control unit 50 causes the first work spindle 22 and the second work spindle 25 to support the work W. As a result, the work W is disposed between the first work spindle 22 and the second work spindle 25.

[0109] In step S112, the control unit 50 starts the additional processing of the work W. More specifically, the control unit 50 controls the above-described drive unit 210 (see FIG. 8) to start the rotation of the work W centered on the Z-axis direction. Thereafter, the control unit 50 supplies the powder material PM to the work W and controls the operation of the laser head 140 so as to irradiate the work W with the laser light LS.

[0110] In step S114, the control unit 50 controls the drive of the second work spindle 25 based on the torque feedback control described above. That is, the control unit 50 controls the motor 222Z described above so that the torque applied to the second work spindle 25 remains constant. As a result, the second work spindle 25 moves along the Z-axis direction in accordance with the thermal expansion and contraction of the workpiece W.

[0111] In step S120, the control unit 50 determines whether the position of the second workpiece spindle is within the normal range ΔR (see Figure 6). If the control unit 50 determines that the position of the second workpiece spindle is within the normal range ΔR (YES in step S120), it switches the control to step S130. Otherwise (NO in step S120), the control unit 50 switches the control to step S150.

[0112] In step S130, the control unit 50 determines whether the laser head 140 has reached the processing end position. The processing end position for the laser head 140 is, for example, described in the processing program. If the control unit 50 determines that the laser head 140 has reached the processing end position (YES in step S130), it switches control to step S132. Otherwise (NO in step S130), the control unit 50 returns control to step S114.

[0113] In step S132, the additional processing by the laser head 140 is stopped. More specifically, the control unit 50 stops the supply of powder material and the irradiation of laser light by the laser head 140. The control unit 50 also controls the drive unit 210 to stop the rotation of the first workpiece spindle 22. Furthermore, the control unit 50 continues torque feedback control for a predetermined time after the completion of the additional processing.

[0114] In step S150, the control unit 50 executes the above-described abnormality countermeasure process. As an example, the control unit 50 stops the additional processing by the laser head 140. As another example, the control unit 50 switches the control of the second work spindle 25 in the position feedback control to the position feedback control. As yet another example, the control unit 50 outputs the above-described warning screen IM (see FIG. 7).

[0115] Note that in the above description, the control flow of the second work spindle 25 in the additional processing has been described, but the control unit 50 may make the control method of the second work spindle 25 different during the additional processing and the removal processing. As an example, the control unit 50 controls the second work spindle 25 by the above-described torque feedback control during the additional processing, and controls the second work spindle 25 by the above-described position feedback control during the removal processing.

[0116] <J. Others> The above-described torque feedback control can be realized by an arbitrary method. As an example, the "contact point stop function" that is standardly installed in the NC device is used. The "contact point stop function" is realized by the FXS command, the FXS command, and the FXST command.

[0117] The FXS command is usually a function for holding the work W on the second work spindle 25. The FXS command is a command for setting the target value of the torque. The FXST command is a command for setting the normal range ΔR of the second work spindle 25.

[0118] The FXS command, the FXS command, and the FXST command are usually commands used when holding the work W on the first work spindle 22 and the second work spindle 25, and are not used during the additional processing. By combining these commands, the torque feedback control during the additional processing is realized.

[0119] <K. Modified Example> Next, with reference to Figure 11, a modified example of the control method for the second workpiece spindle 25 during additional machining will be described. Figure 11 is a diagram illustrating a modified example of the control method for the second workpiece spindle 25.

[0120] In the above-described embodiment, the control unit 50 controlled the drive of the second work spindle 25 based on torque feedback control, thereby moving the second work spindle 25 in accordance with the thermal expansion and contraction of the workpiece W.

[0121] In contrast, in this modified example, the control unit 50 substantially disables the feedback control of the motor 222Z for controlling the position of at least the second work spindle 25 after gripping the workpiece W with the first work spindle 22 and the second work spindle 25. The process of substantially disabling the feedback control of the motor 222Z can be implemented in various ways. As an example, the current feedback gain setting value set in the current feedback loop of the control system in the additive machining device 100 can be set to zero so that there is substantially no feedback. In this case, the position control of the second work spindle 25 is also disabled. As another example, if the current feedback gain is not switched, for example, the current feedback loop can be opened and control can be performed in open loop mode. As yet another example, a function provided on the CNC side can be used to substantially prevent resistance from being generated against changes in the position of the second work spindle 25. After that, the control unit 50 performs the additive machining of the workpiece W. That is, by stopping the control of the motor 222Z, the second work spindle 25 maintains its position in the Z-axis direction by its own weight. As a result, the second workpiece spindle 25 becomes manually movable. Therefore, the second workpiece spindle 25 can move in accordance with the thermal expansion and contraction of the workpiece W.

[0122] More specifically, in step S21, before the start of the additional machining, the motor 222Z is ​​driven to bring the second workpiece spindle 25 closer to the first workpiece spindle 22. As a result, one side of the workpiece W is gripped by the first workpiece spindle 22, and the other side of the workpiece W is gripped by the second workpiece spindle 25.

[0123] Subsequently, in step S22, the control unit 50 stops controlling the motor 222Z and starts additional processing of the workpiece W. More specifically, the control unit 50 controls the drive unit 210 (see Figure 8) to start the rotation of the workpiece W. Then, the control unit 50 supplies powder material PM to the workpiece W and controls the operation of the laser head 140 to irradiate the workpiece W with laser light LS.

[0124] Preferably, in this modified example as well, the control unit 50 sequentially acquires the current position of the second work spindle 25 during the additional machining of the workpiece W and monitors whether the current position is within the normal range ΔR. The method for setting the normal range ΔR is as described above, so it will not be repeated. If the current position of the second work spindle 25 falls outside the normal range ΔR, the control unit 50 executes the abnormality handling process described above.

[0125] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than by the foregoing description, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Explanation of symbols]

[0126] 11 Bed, 16 Tool post, 18 Turret, 21 First support, 22 First work spindle, 23 Chuck mechanism, 24 Second support, 25 Second work spindle, 26 Chuck mechanism, 30 Tool spindle, 50 Control unit, 100 Add-on processing device, 101 Control circuit, 102 ROM, 103 RAM, 104 Communication interface, 109 Internal bus, 120 Auxiliary storage device, 122 Control program, 130 Cover body, 140 Laser head, 142 Head body, 146 Laser nozzle, 200 Control panel, 210 Drive unit, 211C Motor driver, 212C Motor, 220 Drive unit, 221Z Motor driver, 222Z Motor, 230A Drive unit, 230B Drive unit, 231A Motor driver, 231B Motor driver, 231X Motor driver, 231Y motor driver, 231Z motor driver, 232A motor, 232B motor, 232X motor, 232Y motor, 232Z motor, 240 drive unit, 241C motor driver, 241Y motor driver, 241Z motor driver, 242C motor, 242Y motor, 242Z motor, 322 sensor, 324 position sensor, AR processing area, AX1 rotation axis, AX2 rotation axis, AX3 rotation axis, DR door, F focus, IM warning screen, LS laser beam, MP molten pool, MS warning message, PM powder material, SL layer, W workpiece, ΔR normal range.

Claims

1. An additive machining apparatus for performing additional machining on a workpiece, A laser head capable of performing additional processing on a workpiece by supplying powder material to the workpiece and irradiating the workpiece with laser light, A first support portion supports one side of the workpiece in the direction of a predetermined axis and supports the workpiece so that it can rotate around the predetermined axis, A second support portion supports the other side of the workpiece in the direction of the predetermined axis and supports the workpiece so that it can rotate around the predetermined axis, A drive unit for moving the second support portion along the direction of the predetermined axis, A first detection unit for detecting a physical quantity correlated with the torque applied to the drive unit, The system includes a control unit for controlling the aforementioned additional processing device, The control unit performs a process to control the drive unit so that the physical quantity detected by the first detection unit approaches a predetermined target value when the workpiece is being processed or when the workpiece is being cooled.

2. The additional processing apparatus further includes a second detection unit for detecting the position of the second support portion in the direction of the predetermined axis, The control unit further, While the process for controlling the drive unit is being executed, the process of monitoring whether the position is within a predetermined range is performed, The additive processing apparatus according to claim 1, further comprising: a process for performing a predetermined abnormality handling process when the position falls outside the predetermined range.

3. The additional processing apparatus according to claim 2, wherein the abnormality handling process includes a process of switching the drive unit to control the drive unit so that the physical quantity approaches the predetermined target value, to a process of controlling the drive unit so that the position detected by the second detection unit approaches the target position.

4. The additional processing apparatus according to claim 2 or 3, wherein the abnormality handling process includes a process of outputting a warning indicating that the position is outside the preset range.

5. The first support portion is a first workpiece spindle having a chuck mechanism for gripping one side of the workpiece, The additional processing apparatus according to any one of claims 1 to 3, wherein the second support portion is a second workpiece spindle having a chuck mechanism for gripping the other side of the workpiece.

6. The first support portion is a workpiece spindle having a chuck mechanism for gripping one side of the workpiece, The additional processing apparatus according to any one of claims 1 to 3, wherein the second support portion is a tailstock having a tailstock mechanism for tailoring the other side of the workpiece.

7. An additive machining apparatus for performing additional machining on a workpiece, A laser head capable of performing additional processing on a workpiece by supplying powder material to the workpiece and irradiating the workpiece with laser light, A first support portion for gripping one side of the workpiece in the direction of a predetermined axis and for gripping the workpiece so that it can rotate around the predetermined axis, A second support portion for gripping the other side of the workpiece in the direction of the predetermined axis and for gripping the workpiece so that it can rotate around the predetermined axis, A drive unit for moving the second support portion along the direction of the predetermined axis, The system includes a control unit for controlling the aforementioned additional processing device, The control unit performs a process to disable the control processing of the drive unit when the workpiece is being processed or when the workpiece is being cooled, in an additional processing apparatus.

8. A method for performing additional processing on a workpiece using an additional processing device, The aforementioned additional processing apparatus is A laser head capable of performing additional processing on a workpiece by supplying powder material to the workpiece and irradiating the workpiece with laser light, A first support portion supports one side of the workpiece in the direction of a predetermined axis and supports the workpiece so that it can rotate around the predetermined axis, A second support portion supports the other side of the workpiece in the direction of the predetermined axis and supports the workpiece so that it can rotate around the predetermined axis, A drive unit for moving the second support portion along the direction of the predetermined axis, The unit comprises a first detection unit for detecting a physical quantity correlated with the torque applied to the drive unit, The additive machining method comprises the step of controlling the drive unit so that the physical quantity detected by the first detection unit approaches a predetermined target value during the additive machining of the workpiece or during the cooling of the workpiece.

9. A program for additional machining of a workpiece using an additive machining device, The aforementioned additional processing apparatus is A laser head capable of performing additional processing on a workpiece by supplying powder material to the workpiece and irradiating the workpiece with laser light, A first support portion supports one side of the workpiece in the direction of a predetermined axis and supports the workpiece so that it can rotate around the predetermined axis, A second support portion supports the other side of the workpiece in the direction of the predetermined axis and supports the workpiece so that it can rotate around the predetermined axis, A drive unit for moving the second support portion along the direction of the predetermined axis, The unit comprises a first detection unit for detecting a physical quantity correlated with the torque applied to the drive unit, The additive machining program is an additive machining program that causes the additive machining apparatus to execute a process to control the drive unit so that the physical quantity detected by the first detection unit approaches a predetermined target value during the additive machining of the workpiece or during the cooling of the workpiece.

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