JP2022041603A - Work-piece additional processing method and processing machine - Google Patents

Abstract

To provide a work-piece additional processing method and a processing machine which can suppress occurrence of a crack, a deformation, a breakage or the like on an additionally processed layer, due to a difference between a linear expansion coefficient of a work-piece and a linear expansion coefficient of powder materials.SOLUTION: The work-piece additional processing method comprises: a step of applying stress to a work-piece 51 having a fist linear expansion coefficient; a step of supplying powder materials having a second linear expansion coefficient different from the first linear expansion coefficient and emitting a laser beam to the work-piece 51, while keeping on applying stress to the work-piece; and a step of cooling the work-piece 51 while abating the application of stress to the work-piece, after the step of supplying the powder materials and emitting the laser beam.SELECTED DRAWING: Figure 6

Description

The present invention relates to a work addition processing method and a processing machine.

For example, Japanese Patent Application Laid-Open No. 2010-42524 (Patent Document 1) discloses a method for manufacturing a three-dimensional shaped object. The method for manufacturing a three-dimensional shaped object includes a process of applying stress to the modeling plate by attaching a curved modeling plate to the mounting plate, and a process of forming a powder layer on the modeling plate. The powder layer is provided with a step of forming a sintered layer by irradiating the powder layer with a light beam to form a modeled object, and a step of attaching and removing the modeling plate from the modeling plate after modeling.

Further, in Japanese Patent Application Laid-Open No. 9-295173 (Patent Document 2), the powder is put into a jig for holding and rotating the piston base material and a groove provided along the outer peripheral surface of the piston base material. A powder supply device and a nozzle for charging, a laser oscillator that oscillates a laser beam for heating and melting the charged powder, and an oil tank for circulating silicon oil in a jig so that the piston base material can be heated. , A device for manufacturing a piston for an internal combustion engine including a heater, a pump and the like is disclosed.

Further, Japanese Patent Application Laid-Open No. 60-223681 (Patent Document 3) discloses a method of sintering and bonding metal members having different coefficients of thermal expansion at a low temperature. In the method of sintering and bonding disclosed in Patent Document 3, a plurality of ultrafine powders of metals having different coefficients of thermal expansion are bonded with a resin binder to prepare a plurality of powder alloy sheets. A plurality of powder alloy sheets are arranged between metal members having different thermal expansion coefficients so that the thermal expansion coefficient changes stepwise from a metal member having a large thermal expansion coefficient to a metal member having a small thermal expansion coefficient, and then these are made into ultrafine powder. Sinter by heating to the sintering temperature of.

Japanese Unexamined Patent Publication No. 2010-42524 Japanese Unexamined Patent Publication No. 9-295173 Japanese Unexamined Patent Publication No. 60-22361

A work addition processing method for creating a three-dimensional shape in a work by a directed energy deposition method in which a laser beam is irradiated while supplying a material powder to the work is known.

In such an additional processing method of the work, the linear expansion coefficient of the work and the linear expansion coefficient of the material powder may be different. In this case, at the step of cooling the work on which the additional processing is performed, a difference occurs between the heat shrinkage amount of the work and the heat shrinkage amount of the additional processing layer made of the material powder, and the additional processing layer is cracked, deformed or or deformed. There is a possibility of damage.

Therefore, an object of the present invention is to solve the above-mentioned problems, and cracks, deformations, breakages, etc. occur in the additional processed layer due to the difference between the linear expansion coefficient of the work and the linear expansion coefficient of the material powder. It is to provide an additional processing method and a processing machine of a work to prevent this.

The method of additional processing of a work according to the present invention includes a step of applying stress to a work having a first linear expansion coefficient and a first linear expansion of the work while applying stress to the work. After the step of supplying the material powder having a second linear expansion coefficient different from the coefficient and irradiating the laser beam and the step of supplying the material powder and irradiating the laser beam, while relaxing the stress applied to the work. The work is provided with a step of cooling the work.

According to the work addition processing method configured in this way, strain is generated in the work by applying stress in advance, and the strain is gradually eliminated by relaxing the stress applied when the work is cooled, thereby thermally shrinking the work. It suppresses the occurrence of a difference between the amount and the amount of heat shrinkage of the additional processed layer made of the material powder. This makes it possible to prevent cracks, deformation, breakage, etc. from occurring in the additional processing layer.

Also preferably, the first linear expansion coefficient is larger than the second linear expansion coefficient. The step of applying stress includes a step of applying compressive stress to the work.

According to the work addition processing method configured in this way, when the first linear expansion coefficient is larger than the second linear expansion coefficient, the amount of heat shrinkage of the work during the step of cooling the work is the amount of heat shrinkage of the additional processing layer. It becomes larger than the amount of heat shrinkage. For this reason, the work is compressively deformed by applying compressive stress in advance, and the compressive strain is gradually eliminated when the work is cooled, so that the heat shrinkage between the work and the heat shrinkage of the additional work layer is reached. It is possible to suppress the occurrence of a difference in.

Also preferably, the first linear expansion coefficient is smaller than the second linear expansion coefficient. The step of applying stress includes a step of applying tensile stress to the work.

According to the work addition processing method configured in this way, when the first linear expansion coefficient is smaller than the second linear expansion coefficient, the amount of heat shrinkage of the work during the step of cooling the work is the amount of heat shrinkage of the additional processing layer. It is smaller than the amount of heat shrinkage. For this reason, the work is pulled and deformed by applying tensile stress in advance, and the tensile strain is gradually eliminated when the work is cooled, so that the heat shrinkage between the work and the heat shrinkage of the additional work layer is increased. It is possible to suppress the occurrence of a difference in.

Further, preferably, in the step of applying stress, the amount of strain of the work per unit length is the amount of heat shrinkage per unit length of the additional processing layer made of the material powder at the time of the step of cooling the work, and the amount of heat shrinkage of the work. A step of applying stress to the work is included so as to be equal to the difference from the amount of heat shrinkage per unit length.

According to the work addition processing method configured in this way, it is more effective to suppress the difference between the heat shrinkage amount of the work and the heat shrinkage amount of the addition work layer during the step of cooling the work. can.

Further, preferably, the step of cooling the work includes a step of relaxing the stress applied to the work when the temperature of the processing point of the work is in the range of the liquidus point temperature of the material powder or more and room temperature or more.

According to the work addition processing method configured in this way, cracking, deformation, breakage, etc. may occur in the addition processing layer by relaxing the stress applied to the work at the timing when the heat shrinkage of the addition processing layer progresses. It can be prevented more reliably.

Further, preferably, the work addition processing method is a step of holding one end of the work by the first work spindle and holding the other end of the work by the second work spindle arranged so as to face the first work spindle. Further prepare. By changing the distance between the first work spindle and the second work spindle, the magnitude of the stress applied to the work is changed.

According to the work addition processing method configured in this way, the magnitude of the stress applied to the work can be freely adjusted by using the first work spindle and the second work spindle arranged so as to face each other. can.

Further preferably, the additional machining method further includes a step of removing the work from the first work spindle and the second work spindle after the cooling of the work is completed.

According to the work addition processing method configured in this way, the work is held by the first work spindle and the second work spindle until the heat shrinkage of the addition processing layer is completed, so that the addition processing layer is formed. It is possible to more reliably prevent cracks, deformation, breakage, and the like.

The processing machine according to the present invention is a processing machine that performs additional processing of a work. The processing machine includes an additional processing head that supplies material powder to the work and irradiates a laser beam, a stress applying device that applies stress to the work, and a control device that controls the processing machine. The control device controls the operation of the stress applying device so as to apply stress to the work having the first linear expansion coefficient. The control device applies stress to the work so as to supply the work with a material powder having a second linear expansion coefficient different from the first linear expansion coefficient and to irradiate the work with laser light. Controls the operation of the device and additional machining head. After supplying the material powder and irradiating the laser beam, the control device controls the operation of the stress applying device so as to cool the work while relaxing the stress applied to the work.

According to the processing machine configured in this way, it is possible to prevent cracks, deformations, breakages, etc. in the additional processing layer due to the difference between the linear expansion coefficient of the work and the linear expansion coefficient of the material powder. can.

As described above, according to the present invention, it is possible to suppress the occurrence of cracks, deformation, breakage, etc. in the additional work layer due to the difference between the linear expansion coefficient of the work and the linear expansion coefficient of the material powder. It is possible to provide an additional processing method and a processing machine for a work.

It is a front view which shows the processing machine. It is a perspective view which shows the state in the processing area at the time of additional processing in the processing machine in FIG. It is sectional drawing which shows the conventional phenomenon when the linear expansion coefficient of a work and a material powder is different. It is sectional drawing which shows the conventional phenomenon when the linear expansion coefficient of a work and a material powder is different. It is sectional drawing which shows the 1st step (the 1st linear expansion coefficient> the 2nd linear expansion coefficient) of the addition processing method of the work in this embodiment. It is sectional drawing which shows the 2nd step (the 1st linear expansion coefficient> the 2nd linear expansion coefficient) of the addition processing method of the work in this embodiment. It is sectional drawing which shows the 3rd step (the 1st linear expansion coefficient> the 2nd linear expansion coefficient) of the addition processing method of the work in this embodiment. It is sectional drawing which shows the 1st step (the 1st linear expansion coefficient <the 2nd linear expansion coefficient) of the addition processing method of the work in this embodiment. It is sectional drawing which shows the 2nd step (the 1st linear expansion coefficient <the 2nd linear expansion coefficient) of the addition processing method of the work in this embodiment. FIG. 3 is a block diagram showing a control system related to additional machining of a workpiece in the machining machines in FIGS. 1 and 2. It is a flowchart which shows the flow of the step which executes the additional processing method of the work in this embodiment using the processing machine in FIGS. 1 and 2.

Embodiments of the present invention will be described with reference to the drawings. In the drawings referred to below, the same or corresponding members are assigned the same number.

FIG. 1 is a front view showing a processing machine. In FIG. 1, the inside of the processing machine is shown by seeing through the cover body forming the appearance of the processing machine. FIG. 2 is a perspective view showing a state in the processing area at the time of additional processing in the processing machine in FIG. 1.

With reference to FIGS. 1 and 2, the processing machine 100 can perform AM / SM hybrid processing capable of performing work addition processing (AM (Additive manufacturing) processing) and work removal processing (SM (Subtractive manufacturing) processing). It is a machine. The machining machine 100 has a turning function using a fixed tool and a milling function using a rotary tool as SM machining functions. The machining machine 100 is an NC (Numerically Control) machining machine in which various operations for machining a workpiece are automated by numerical control by a computer.

In the present specification, an axis parallel to the left-right direction (width direction) of the processing machine 100 and extending in the horizontal direction is referred to as a "Z axis", and is parallel to the front-back direction (depth direction) of the processing machine 100 and horizontally. The axis that extends is called the "Y axis", and the axis that extends in the vertical direction is called the "X axis". The right direction in FIG. 1 is referred to as "+ Z axis direction", and the left direction is referred to as "-Z axis direction". In FIG. 1, the front direction of the paper surface is referred to as "+ Y-axis direction", and the back direction is referred to as "-Y-axis direction". The upward direction in FIG. 1 is referred to as "+ X-axis direction", and the downward direction is referred to as "-X-axis direction".

First, the structure of the processing machine 100 used in the work addition processing method in the present embodiment will be described. The processing machine 100 has a bed 136, a first headstock 111, a second headstock 116, a tool spindle 121, and a lower tool post 131.

The bed 136 is a base member for supporting the first headstock 111, the second headstock 116, the tool head shaft 121, and the lower blade base 131, and is installed on the floor surface of a factory or the like. The first headstock 111 (the first work spindle 112 described later), the second headstock 116, the tool headstock 121, and the lower tool post 131 are provided in the machining area 200 partitioned by the splash guard 205.

The processing area 200 is a space where work removal processing and addition processing are performed, and is sealed so that foreign matter such as chips, cutting oil, or fume associated with the work processing does not leak to the outside of the processing area 200.

The first headstock 111 and the second headstock 116 are provided so as to face each other in the Z-axis direction. The first headstock 111 and the second headstock 116 are the first to rotate the work during turning using a fixed tool, and to hold the work during milling or removal using a rotating tool, respectively. It has one work spindle 112 and a second work spindle 117. The first work spindle 112 is rotatably provided around the central axis 201A parallel to the Z axis, and the second work spindle 117 is rotatably provided around the central axis 201B parallel to the Z axis. The central axis 201A and the central axis 201B extend on the same straight line.

The first work spindle 112 and the second work spindle 117 are provided with a chuck 113 and a chuck 118 for gripping the work in a detachable manner, respectively. As shown in FIG. 1, the distance in the Z-axis direction between the spindle end surface 112f of the first work spindle 112 provided with the chuck 113 and the spindle end surface 117f of the second work spindle 117 provided with the chuck 118 is the first. It is referred to as a distance H between the spindles of the 1 work spindle 112 and the 2nd work spindle 117.

As shown in FIG. 2, the work 51 to be machined is held by the first work spindle 112 and the second work spindle 117. The work 51 is made of a metal material such as stainless steel, for example.

The work 51 has a cylindrical shape centered on the central axis 201 extending on the extension of the central axis 201A and the central axis 201B. One end of the work 51 in the axial direction of the central axis 201 is gripped by the chuck 113, and the other end of the work 51 in the axial direction of the central axis 201 is gripped by the chuck 118. When the first work spindle 112 and the second work spindle 117 are rotationally driven in synchronization with each other, the work 51 rotates about the central axis 201.

The second headstock 116 (second work spindle 117) is provided so as to be movable in the Z-axis direction by various feed mechanisms, guide mechanisms, servomotors, and the like. By moving the second headstock 116 in the + Z axis direction, the distance H between the spindles of the first work spindle 112 and the second work spindle 117 increases, and by moving the second headstock 116 in the −Z axis direction. , The distance H between the spindles of the first work spindle 112 and the second work spindle 117 is reduced.

The tool spindle (upper tool post) 121 rotates the rotary tool during milling using the rotary tool. The tool spindle 121 is rotatably provided about a central axis 203 parallel to the X-axis-Z-axis plane. The tool spindle 121 is provided with a clamp mechanism for holding the rotary tool detachably.

The tool spindle 121 is supported on the bed 136 by a column or the like (not shown). The tool spindle 121 is provided so as to be movable in the X-axis direction, the Y-axis direction, and the Z-axis direction by various feed mechanisms, guide mechanisms, servomotors, and the like provided on the column and the like. With such a configuration, the machining position by the rotary tool mounted on the tool spindle 121 moves three-dimensionally.

The tool spindle 121 is further provided so as to be able to swivel around a swivel center shaft 204 parallel to the Y axis (B-axis swivel). The turning range of the tool spindle 121 is a range of ± 120 ° with respect to the posture in which the spindle end surface 123 of the tool spindle 121 faces downward (the posture shown in FIG. 1 and FIG. 2). The turning range of the tool spindle 121 is preferably a range of ± 90 ° or more from the postures shown in FIGS. 1 and 2.

Although not shown in FIG. 1, an automatic tool changer (ATC: Automatic Tool Changer) for automatically changing the tool mounted on the tool spindle 121 is provided around the first headstock 111. A tool magazine for accommodating a replacement tool to be mounted on the tool spindle 121 is provided.

The lower tool post 131 is equipped with a plurality of fixing tools for turning. The lower blade base 131 has a so-called turret type, and a plurality of fixing tools are radially attached to perform swivel indexing.

More specifically, the lower tool post 131 has a swivel portion 132. The swivel portion 132 is provided so as to be swivelable around a central axis 206 parallel to the Z axis. A plurality of tool holders for holding a fixed tool are attached to positions spaced apart from each other in the circumferential direction about the central axis 206. When the swivel portion 132 swivels around the central axis 206, the fixing tool held by the tool holder moves in the circumferential direction, and the fixing tool used for turning is indexed.

The lower blade base 131 is supported on the bed 136 by a saddle or the like (not shown). The lower blade base 131 is provided so as to be movable in the X-axis direction and the Z-axis direction by various feed mechanisms, guide mechanisms, servomotors, and the like provided on the saddle and the like.

The processing machine 100 further includes an additional processing head 21. The additional processing head 21 performs additional processing by supplying material powder to the work and irradiating it with a laser beam (directed energy deposition). As the material powder, for example, a metal powder such as a cobalt-based alloy or an SKD material can be used.

The additional machining head 21 is configured to be detachable from the tool spindle 121. At the time of additional processing, the additional processing head 21 is mounted on the tool spindle 121. As the tool spindle 121 moves in the X-axis direction, the Y-axis direction, and the Z-axis direction, the machining position of the additional machining by the additional machining head 21 is three-dimensionally displaced. Further, when the tool spindle 121 is swiveled around the swivel center shaft 204, the additional machining head 21 is also integrated with the tool spindle 121 and swivels around the swivel center shaft 204. Thereby, the direction of the additional processing (the irradiation direction of the laser beam to the work) by the additional processing head 21 can be freely changed.

At the time of removal machining, the additional machining head 21 is separated from the tool spindle 121 and stored in a head stocker (not shown).

The tool spindle 121 is provided with a clamp mechanism, and when the add-machi head 21 is mounted on the tool spindle 121, the clamp mechanism operates to connect the add-machi head 21 to the tool spindle 121. As an example of the clamping mechanism, there is a mechanism that obtains a clamped state by a spring force and obtains an unclamped state by hydraulic pressure.

The processing machine 100 further includes a powder feeder 70, a laser oscillator 76, and a cable 24.

The powder feeder 70 introduces the material powder used for the additional processing toward the additional processing head 21 in the processing area 200. The powder feeder 70 has a powder hopper 72 and a mixing unit 71. The powder hopper 72 forms a closed space for accommodating the material powder used for the additional processing. The mixing unit 71 mixes the material powder contained in the powder hopper 72 with the gas for the carrier of the material powder.

The laser oscillator 76 oscillates the laser beam used for additional processing. The cable 24 includes an optical fiber for guiding a laser beam from the laser oscillator 76 toward the additional processing head 21, a pipe for guiding material powder from the powder feeder 70 toward the additional processing head 21, and an air flow. It is composed of an air pipe serving as a path, a gas pipe serving as a flow path for an inert gas, a cooling pipe serving as a flow path for a refrigerant, electrical wiring, and a pipe member accommodating these.

Subsequently, the method of additional processing of the work in the present embodiment will be described. 3 and 4 are cross-sectional views showing a conventional phenomenon when the work and the material powder have different linear expansion coefficients.

In FIGS. 3 and 4, it is assumed that the first linear expansion coefficient of the work 51 is larger than the second linear expansion coefficient of the material powder (additional processed layer 56). As an example, the work 51 is made of SUS304 having a linear expansion coefficient of 17.3 × 10 ^-6 / ° C, and the material powder is made of a cobalt-based alloy having a linear expansion coefficient of 10 × 10 ^-6 / ° C.

With reference to FIG. 3, when the work 51 is supplied with the material powder and irradiated with the laser beam, a melt pool 52 formed by melting the work 51 is formed on the surface of the work 51, and the surface of the work 51 is formed. On the top, an additional processing layer 56 formed by melting the material powder is formed so as to overlap with the melt pool 52. At this time, the thermal expansion amount of the work 51 shown by the arrow 62 is larger than the thermal expansion amount of the additional processing layer 56 shown by the arrow 61.

By cooling the work 51 with reference to FIG. 4, the additional processing layer 56 is welded onto the surface of the work 51. At this time, since the amount of heat shrinkage of the work 51 due to solidification is larger than the amount of heat shrinkage of the additional processing layer 56 due to solidification, stress is generated at the boundary between the additional processing layer 56 and the work 51. As a result, the additional processing layer 56 may be cracked, deformed or damaged.

5 to 7 are cross-sectional views showing steps (first linear expansion coefficient> second linear expansion coefficient) of the work addition processing method in the present embodiment.

With reference to FIGS. 5 to 7, the work addition processing method in the present embodiment, as shown in FIG. 5, stresses the work 51 having the first linear expansion coefficient as shown in FIG. And, as shown in FIG. 6, a material powder having a second linear expansion coefficient different from the first linear expansion coefficient is supplied to the work 51 while stress is applied to the work 51. After the step of irradiating the work 51 with the laser beam and the step of supplying the material powder and irradiating the laser beam, the step of cooling the work 51 while relaxing the stress applied to the work 51. And prepare.

The first linear expansion coefficient of the work 51 is larger than the second linear expansion coefficient of the material powder. The step of applying the stress shown in FIG. 5 includes a step of applying the compressive stress shown by the arrow 64 to the work 51.

As shown in FIG. 6, the amount of thermal expansion of the work 51 from which the amount of mechanical deformation of the work 51, which is shown by the arrow 63, is subtracted by causing the work 51 to be compressively strained by applying the compressive stress in advance. The amount of thermal expansion of the additional processing layer 56 shown by the arrow 61 can be approached. Then, as shown in FIG. 7, the heat shrinkage amount of the work 51 and the heat shrinkage amount of the additional work layer 56 are obtained by gradually eliminating the compression strain by relaxing the application of the compressive stress when the work 51 is cooled. It is possible to suppress the occurrence of a difference between. This makes it possible to prevent the additional processing layer 56 from being cracked, deformed, or damaged.

8 and 9 are cross-sectional views showing steps (first linear expansion coefficient <second linear expansion coefficient) of the work addition processing method in the present embodiment. 8 and 9, respectively, show the steps corresponding to FIGS. 5 and 6, respectively.

With reference to FIGS. 8 and 9, if the first linear expansion coefficient of the work 51 is smaller than the second linear expansion coefficient of the material powder, the step of applying the stress shown in FIG. 8 is the work. The step of applying the tensile stress shown by the arrow 68 to 51 is included.

When the first linear expansion coefficient of the work 51 is smaller than the second linear expansion coefficient of the material powder, the thermal expansion amount of the work 51 is smaller than the thermal expansion amount of the additional processing layer 56.

On the other hand, as shown in FIG. 9, the work 51 to which the amount of mechanical deformation of the work 51 shown by the arrow 67 is added by causing the work 51 to have a tensile strain by applying a tensile stress in advance. The amount of thermal expansion can be brought close to the amount of thermal expansion of the additional processing layer 56 shown by the arrow 65. Then, by gradually eliminating the tensile strain by relaxing the application of tensile stress when the work 51 is cooled, a difference is generated between the heat shrinkage amount of the work 51 and the heat shrinkage amount of the additional work layer 56. Can be suppressed. This makes it possible to prevent the additional processing layer 56 from being cracked, deformed, or damaged.

In the work addition processing method of the present embodiment, in the step of applying stress, the strain amount of the work 51 per unit length is the unit of the addition processing layer 56 made of the material powder at the time of the step of cooling the work 51. It is preferable to include a step of applying stress to the work 51 so as to be equal to the difference between the heat shrinkage amount per length and the heat shrinkage amount per unit length of the work 51.

According to such a configuration, it is possible to more effectively suppress the difference between the heat shrinkage amount of the work 51 and the heat shrinkage amount of the additional processing layer 56 during the step of cooling the work 51. As a result, it is possible to more reliably prevent the additional processing layer 56 from being cracked, deformed or damaged.

As an example, the linear expansion coefficient, compression / tensile coefficient, and tensile cross section coefficient of the work 51, the linear expansion coefficient, compression / tensile coefficient, and thickness of the material powder, and the temperature, room temperature, and room temperature of the processing point of the work 51, and By using the cooling rate as a parameter and relaxing the stress according to the cooling rate of the work 51 in accordance with these parameters, it is possible to effectively prevent cracks, deformation, breakage, etc. from occurring in the additional work layer 56. Can be done.

The step of cooling the work 51 preferably includes a step of relaxing the stress applied to the work 51 when the temperature of the processing point of the work 51 is in the range of the liquidus point temperature of the material powder or higher and the room temperature or higher. It is more preferable that the step of relaxing the stress applied to the work 51 is continuously performed while the temperature at the processing point of the work 51 drops from at least the liquid phase temperature of the material powder to the solid phase temperature.

The temperature of the processing point of the work 51 corresponds to the temperature of the additional processing layer 56. The liquid phase temperature of the material powder is the temperature at which a solid begins to appear from the liquid in the material powder. In the additional processed layer 56, crystal nucleation proceeds from the liquid phase temperature of the material powder to the solid phase temperature of the material powder that becomes completely solid.

According to such a configuration, the application of compressive stress to the work 51 is relaxed at the timing when the nucleation of crystals starts in the additional processing layer 56, that is, at the timing when the thermal shrinkage of the additional processing layer 56 starts. As a result, it is possible to more reliably prevent the additional processing layer 56 from being cracked, deformed or damaged.

Subsequently, as a more specific example of the work addition processing method in the present embodiment, a case where the work addition processing method in the present embodiment is executed using the processing machine 100 in FIGS. 1 and 2. explain.

FIG. 10 is a block diagram showing a control system related to additional machining of a workpiece in the machining machines in FIGS. 1 and 2. With reference to FIG. 10, the processing machine 100 further includes a control device 81.

The control device 81 controls the processing machine 100. The control device 81 is provided in the processing machine 100 and is a control panel for controlling various operations in the processing machine 100.

The control device 81 includes a program storage unit 82, a program execution unit 83, a tool spindle control unit 84, an additional machining control unit 85, a first work spindle control unit 86, and a second work spindle control unit 87. ..

The program storage unit 82 stores an execution program (numerical control program) for machining a work created by an operator of the machining machine 100. The program storage unit 82 is, for example, a flash memory.

The program execution unit 83 executes the execution program stored in the program storage unit 82. The program execution unit 83 reads the command of the execution program and outputs a control signal to each of the tool spindle control unit 84, the additional machining control unit 85, the first work spindle control unit 86, and the second work spindle control unit 87.

The tool spindle control unit 84 moves the tool spindle feed motor 89 for moving the tool spindle 121 in the X-axis direction, the Y-axis direction, and the Z-axis direction according to the control signal from the program execution unit 83, and the tool spindle 121 on the B axis. It controls the tool spindle swivel motor 90 for swiveling. The additional processing control unit 85 includes a laser oscillator 76 for supplying laser light to the additional processing head 21 and powder for supplying material powder to the additional processing head 21 according to a control signal from the program execution unit 83. It controls the feeder 70.

The first work spindle control unit 86 controls the first work spindle rotation motor 91 for rotating the first work spindle 112 according to the control signal from the program execution unit 83. The second work spindle control unit 87 moves the second work spindle rotation motor 92 for rotating the second work spindle 117 and the second work spindle 117 in the Z-axis direction according to the control signal from the program execution unit 83. The second workpiece spindle feed motor 93 for this purpose is controlled.

The control device 81 further includes a storage unit 96. In the storage unit 96, data on the relationship between the type of metal used for the work and the material powder and the linear expansion coefficient of each metal, the type of metal used for the material powder, and the liquidus point temperature of each metal are stored. Data about the relationship is stored.

The processing machine 100 further includes an operation unit 95, a temperature sensor 94, and a strain gauge 97. The operation unit 95 is provided outside the processing area 200. The operation unit 95 includes various buttons and switches used by the operator when operating the processing machine 100, a display unit indicating the processing state of the work in the processing machine 100, and the like. The operation unit 95 is configured so that the type of metal used for the work and the type of metal used for the material powder can be input.

The temperature sensor 94 is provided in the machining area 200. The temperature sensor 94 is configured to be able to detect the temperature in the machining area 200 and the temperature at the machining point of the work 51 during additional machining. The temperature sensor 94 may be attached to the additional processing head 21. The temperature sensor 94 may be a non-contact temperature sensor.

The strain gauge 97 is provided on the work 51. The strain gauge 97 is configured to be able to detect the amount of strain of the work 51 in the Z-axis direction.

FIG. 11 is a flowchart showing the flow of steps for executing the additional machining method of the work according to the present embodiment by using the machining machines in FIGS. 1 and 2.

With reference to FIGS. 1, 2, 9 and 10, the work 51 is held by the first work spindle 112 and the second work spindle 117 (S101). In this step, the work 51 is arranged between the first work spindle 112 and the second work spindle 117. The chuck 113 and the chuck 118 grip one end and the other end of the work 51 in the Z-axis direction, respectively.

The type of metal used for the work 51 and the type of metal used for the material powder at the time of additional processing are input to the operation unit 95 (S102). The operation unit 95 outputs the input metal type to the second work spindle control unit 87.

Next, the second work spindle control unit 87 specifies the linear expansion coefficient α1 of the work 51, the linear expansion coefficient α2 of the material powder, and the liquid phase point temperature T1 of the material powder (S103).

In this step, the second work spindle control unit 87 stores data in the storage unit 96 of the type of metal used for the work 51 obtained in the step of S102 and the type of metal used for the material powder. The linear expansion coefficient α1 of the work 51 and the linear expansion coefficient α2 of the material powder are specified in light of the above. The second work spindle control unit 87 identifies the liquidus point temperature T1 of the material powder by comparing the type of metal used in the material powder obtained in the step of S102 with the data stored in the storage unit 96. do.

Next, the temperature sensor 94 detects the temperature T0 in the machining area 200 (S104). The temperature sensor 94 outputs the detected temperature T0 in the machining area 200 to the second work spindle control unit 87 as room temperature.

Next, the second work spindle control unit 87 calculates the target strain amount ΔLt of the work 51 per unit length in the Z-axis direction (S105).

In this step, the second work spindle control unit 87 has the linear expansion coefficient α1 of the work 51 and the linear expansion coefficient α2 of the material powder specified in the step of S103, and the liquid phase of the material powder specified in the step of S103. By substituting the point temperature T1 and the room temperature T0 obtained in the step of S104 into the following formula, the target strain amount ΔLt of the work 51 is calculated.

ΔLt = | α1-α2 | * (T1-T0)
Next, the second work spindle control unit 87 controls the second work spindle feed motor 93 so that the second work spindle 117 moves in the Z-axis direction. The strain gauge 97 detects the strain amount ΔL of the work 51 per unit length in the Z-axis direction (S106).

When the linear expansion coefficient α1 of the work 51 and the linear expansion coefficient α2 of the material powder specified in the step of S103 satisfy the relational expression of α1> α2, the moving direction of the second work spindle 117 is the −Z axis direction. .. When the linear expansion coefficient α1 of the work 51 and the linear expansion coefficient α2 of the material powder specified in the step of S103 satisfy the relational expression of α1 <α2, the moving direction of the second work spindle 117 is the + Z axis direction.

The strain gauge 97 detects the amount of strain of the work 51 generated by the movement of the second work spindle 117 in the Z-axis direction. The strain gauge 97 outputs the detected strain amount ΔL of the work 51 to the second work spindle control unit 87.

The second work spindle control unit 87 determines whether or not the strain amount ΔL of the work 51 reaches the target strain amount ΔLt of the work 51 calculated in the step of S105 (S107). When ΔL <ΔLt, the movement of the second work spindle 117 in the step of S106 and the detection of the strain amount ΔL of the work 51 are continued. When ΔL = ΔLt, in the step of S106, the movement of the second work spindle 117 in the step of S106 and the detection of the strain amount ΔL of the work 51 are stopped, and the process proceeds to the next step of S108. This step completes the step of applying stress to the work 51.

Next, additional processing of the work 51 is carried out (S108). In this step, by executing the additional processing of the work 51 according to the execution program stored in the program storage unit 82, the additional processing layer 56 covering the outer peripheral surface thereof is formed on the work 51.

More specifically, the tool spindle control unit 84 has a tool spindle feed motor 89 and a tool spindle swivel so that the additional machining head 21 mounted on the tool spindle 121 is positioned so as to face the outer peripheral surface of the work 51. Controls the motor 90. The additional processing control unit 85 controls the laser oscillator 76 and the powder feeder 70 so that the laser light and the material powder are supplied from the additional processing head 21 toward the work 51. The first work spindle control unit 86 and the second work spindle control unit 87 include the first work spindle rotation motor 91 and the second work spindle rotation motor 91 and the second work spindle control unit 87 so that the first work spindle 112 and the second work spindle 117 rotate about the central axis 201. The work spindle rotation motor 92 is controlled, and the tool spindle control unit 84 controls the tool spindle feed motor 89 so that the additional machining head 21 mounted on the tool spindle 121 moves in the Z-axis direction.

When the additional processing in the step of S108 is completed, the work 51 is cooled. The temperature sensor 94 detects the temperature t of the machining point (additional machining layer 56) of the work 51 (S109).

In this step, the work 51 is cooled by leaving the work 51 on which the additional processing layer 56 is formed in a state of being held by the first work spindle 112 and the second work spindle 117. The temperature sensor 94 outputs the detected temperature t at the machining point of the work 51 to the second work spindle control unit 87.

The second work spindle control unit 87 determines whether or not the temperature t at the processing point of the work 51 has reached the liquid phase point temperature T1 of the material powder specified in the step S103 (S110). When t> T1, the cooling of the work 51 in the step of S109 and the detection of the temperature t at the processing point of the work 51 are continued as they are. When t = T1, the process proceeds to the next step of S111.

Next, the second work spindle control unit 87 controls the second work spindle feed motor 93 so that the second work spindle 117 moves in the Z-axis direction (S111).

When the linear expansion coefficient α1 of the work 51 and the linear expansion coefficient α2 of the material powder specified in the step of S103 satisfy the relational expression of α1> α2, the moving direction of the second work spindle 117 is the + Z axis direction. When the linear expansion coefficient α1 of the work 51 and the linear expansion coefficient α2 of the material powder specified in the step of S103 satisfy the relational expression of α1 <α2, the moving direction of the second work spindle 117 is the −Z axis direction. ..

From this step onward, by continuing to move the second work spindle 117 in the Z-axis direction, cooling of the work 51 and detection of the temperature t at the machining point of the work 51 are continued while alleviating the stress applied to the work 51. do. The second work spindle control unit 87 controls the second work spindle feed motor 93 so that the second work spindle 117 stops when it returns to the initial position in S101. The moving speed of the second work spindle 117 in this step is preferably slower than the moving speed of the second work spindle 117 in the step S106.

Next, cooling of the work 51 is completed (S112). In this step, the second work spindle control unit 87 completes cooling of the work 51 when the temperature t at the machining point of the work 51 reaches the temperature T0 in the machining area 200 detected in the step of S104. You may judge. The completion of cooling of the work 51 may be notified to the operator by a display on the display unit of the operation unit 95, a sound, or the like. It is preferable that the second work spindle 117 returns to the initial position in S101 when the cooling of the work 51 is completed or before the cooling of the work 51 is completed.

Next, the work 51 is removed from the first work spindle 112 and the second work spindle 117 (S113). By the above steps, the work addition processing method using the processing machine 100 in FIGS. 1 and 2 is completed.

According to such a configuration, the magnitude of the stress applied to the work 51 can be freely adjusted by using the first work spindle 112 and the second work spindle 117 arranged to face each other in the processing machine 100. can.

Further, in order to remove the work 51 from the first work spindle 112 and the second work spindle 117 after the cooling of the work 51 is completed, a state in which the work 51 is held by the first work spindle 112 and the second work spindle 117 is added. It continues until the thermal shrinkage of the processed layer 56 and the melt pool 52 is completed. As a result, it is possible to more reliably prevent the additional processing layer 56 from being cracked, deformed or damaged.

When the removal processing is performed after the addition processing of the work 51, the removal processing of the work 51 is continuously performed while the work 51 is held by the first work spindle 112 and the second work spindle 117 after the step of S112. You may.

The work addition processing method according to the present embodiment described above is a step of applying stress to a work having a first linear expansion coefficient and a step of applying stress to the work while applying stress to the work. After the step of supplying the material powder having a second linear expansion coefficient different from the first linear expansion coefficient and irradiating the laser beam, and the step of supplying the material powder and irradiating the laser beam, the stress on the work is applied. It is provided with a step of cooling the work while relaxing the application.

Further, the processing machine 100 in the present embodiment has a head 21 for additional processing that supplies material powder to the work and irradiates a laser beam, and a second stress applying device that applies stress to the work. A work spindle 117 and a control device 81 for controlling the machining machine 100 are provided. The control device 81 controls the operation of the second work spindle 117 so as to apply stress to the work having the first linear expansion coefficient. The control device 81 supplies the work with a material powder having a second linear expansion coefficient different from the first linear expansion coefficient while applying stress to the work, and irradiates the work with a laser beam. 2 Controls the operation of the work spindle 117 and the additional machining head 21. After supplying the material powder and irradiating the laser beam, the control device 81 controls the operation of the second work spindle 117 so as to cool the work while relaxing the stress applied to the work.

According to such a configuration, it is possible to suppress the occurrence of cracks, deformation, breakage, etc. in the additional processed layer due to the difference between the linear expansion coefficient of the work and the linear expansion coefficient of the material powder. When a thin-walled additional processing layer is laminated on the surface of the work, cracks and the like are likely to occur in the additional processing layer. Therefore, the additional processing method of the work in the present embodiment is such a thin-walled additional processing layer. It is more effective for the laminating process. Further, when the cooling rate of the work is controlled by using a heater, a laser, a cooler, or the like, the stress applied to the work may be relaxed according to the cooling rate.

Further, in the method for manufacturing a three-dimensional shaped object disclosed in Patent Document 1 described above, after the step of modeling the modeled object on the modeled plate, the modeled plate is formed from the mounting plate for applying stress to the modeled plate. I'm removing it. In this case, it is not possible to control the relaxation of the stress applied to the modeling plate. Further, the device for manufacturing a piston for an internal combustion engine disclosed in Patent Document 2 above requires an oil tank, a heater, a pump, and the like for controlling the cooling rate of the piston base material, so that the device becomes large-scale. Further, in the method of sintering and bonding disclosed in Patent Document 3 described above, the thermal expansion coefficient gradually changes from a metal member having a large thermal expansion coefficient to a metal member having a small thermal expansion coefficient between metal members having different thermal expansion coefficients. Since a plurality of powder alloy sheets are arranged as such, there are restrictions on the metal material forming the powder alloy sheet. The work addition processing method and the processing machine 100 in the present embodiment contribute to solving these problems.

It should be considered that the embodiments disclosed this time are exemplary in all respects and not restrictive. The scope of the present invention is shown by the scope of claims rather than the above description, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

The present invention is applied to the additional processing of workpieces by the directed energy deposition method.

21 Add-Machine Head, 24 Cable, 51 Work, 52 Melt Pool, 56 Add-Machine Layer, 70 Powder Feeder, 71 Mixer, 72 Powder Hopper, 76 Laser Oscillator, 81 Controller, 82 Program Storage, 83 Program Execution , 84 Tool spindle control unit, 85 Addition machining control unit, 86 1st work spindle control unit, 87 2nd work spindle control unit, 89 Tool spindle feed motor, 90 Tool spindle swing motor, 91 1st work spindle rotation motor, 92 2nd work spindle rotation motor, 93 2nd work spindle feed motor, 94 temperature sensor, 95 operation unit, 96 storage unit, 97 strain gauge, 100 processing machine, 111 1st spindle base, 112 1st work spindle, 112f, 117f, 123 Spindle end face, 113, 118 chuck, 116 2nd spindle, 117 2nd work spindle, 121 Tool spindle, 131 tool post, 132 swivel part, 136 bed, 200 machining area, 201, 201A, 201B, 203, 206 center axis, 204 swivel center axis, 205 splash guard.

Claims (8)

A step of applying stress to a work having a first linear expansion coefficient, and
A step of supplying a material powder having a second linear expansion coefficient different from the first linear expansion coefficient to the work and irradiating the work with a laser beam while applying stress to the work.
A work addition processing method comprising a step of supplying the material powder and irradiating the laser beam, followed by a step of cooling the work while relaxing the application of stress to the work. The first linear expansion coefficient is larger than the second linear expansion coefficient.
The work addition processing method according to claim 1, wherein the step of applying stress includes a step of applying compressive stress to the work. The first linear expansion coefficient is smaller than the second linear expansion coefficient.
The work addition processing method according to claim 1, wherein the step of applying stress includes a step of applying tensile stress to the work. In the step of applying the stress, the strain amount of the work per unit length is the heat shrinkage amount per unit length of the additional processing layer made of the material powder at the time of the step of cooling the work, and the work. The work addition processing method according to any one of claims 1 to 3, further comprising a step of applying stress to the work so as to be equal to the difference from the heat shrinkage amount per unit length. The step of cooling the work includes a step of relaxing stress application to the work when the temperature of the processing point of the work is in the range of the liquidus point temperature of the material powder or more and room temperature or more. The work addition processing method according to any one of 1 to 4. A step of holding one end of the work by the first work spindle and holding the other end of the work by the second work spindle arranged to face the first work spindle is further provided.
The work according to any one of claims 1 to 5, wherein the magnitude of stress applied to the work is changed by changing the distance between the first work spindle and the second work spindle. Additional processing method. The work addition processing method according to claim 6, further comprising a step of removing the work from the first work spindle and the second work spindle after the cooling of the work is completed. It is a processing machine that performs additional processing of workpieces.
An additional processing head that supplies material powder to the work and irradiates a laser beam,
A stress applying device that applies stress to the work, and
It is equipped with a control device that controls the processing machine.
The control device is
The operation of the stress applying device is controlled so as to apply stress to the work having the first linear expansion coefficient.
While applying stress to the work, the stress is applied so that the work is supplied with a material powder having a second linear expansion coefficient different from the first linear expansion coefficient and is irradiated with laser light. Controls the operation of the device and the additional machining head,
A processing machine that controls the operation of the stress applying device so as to cool the work while relaxing the application of stress to the work after supplying the material powder and irradiating the laser beam.

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