JP7555241B2 - Additive manufacturing device and method for manufacturing three-dimensional objects - Google Patents

Description

The present disclosure relates to an additive manufacturing apparatus and a method for manufacturing a three-dimensional object by repeating a process of supplying an additive material and a process of melting and solidifying the additive material.

A technology called additive manufacturing has long been known as a method for manufacturing three-dimensional objects using metal as a material. Additive manufacturing methods are divided into several types depending on the material and layering method, and one of the additive manufacturing methods is the directed energy deposition (DED) method. The DED method includes a process of sending out additive material, which is the material to be layered, from a nozzle attached to the processing head, and a process of selectively melting and solidifying the additive material by inputting energy that serves as a heat source such as a laser, electron beam, or arc discharge. A three-dimensional object is then formed from the deposit obtained by repeating these processes.

Compared to other additive manufacturing methods, the DED method has advantages such as a fast modeling speed, easy switching of additive materials, and fewer limitations on modeling size. In addition, with the DED method, additive material is added only to the necessary parts, so the yield of additive material is good, and when wire is used as the additive material, ready-made welding wire can be reused. In other words, the DED method has the advantages of being inexpensive and the additive material is easy to obtain.

In addition, in the wire-based DED method, the wire is inserted as an additive material, so air and shielding gas are less likely to mix with the modeling material. Therefore, the wire-based DED method has the advantage of having a higher modeling density than other additive manufacturing methods. However, if the wire position is not set appropriately, modeling defects may occur. Therefore, in the wire-based DED method, a method for controlling the wire displacement is very important. Patent Document 1 discloses a technology in which the wire is imaged from the Y-axis direction when the wire supply direction is the Z-axis direction, the welding direction is the Y-axis direction, and the direction perpendicular to both the Z-axis direction and the Y-axis direction is the X-axis direction, and the wire is imaged from the Y-axis direction, the displacement in the X-axis direction is measured from the imaged data, and the position of the wire in the X-axis direction is corrected based on the measurement results.

Patent No. 2607691

However, when the above conventional technology is applied to additive manufacturing using a wire using the DED method, it is possible to correct and control the displacement of the wire in the X-axis direction, but it is not possible to measure the penetration depth of the wire in the Z-axis direction in the molten pool where the wire is molten, or the impact of the wire in the molten pool on the model. Furthermore, if the space between the camera and the wire is blocked by part of the model, it is not possible to measure the displacement of the wire in the X-axis and Y-axis directions. Thus, when the above conventional technology is applied to additive manufacturing using the DED method, there is a problem in that it is not possible to accurately measure and control the displacement in the X-axis and Y-axis directions and the position in the Z-axis direction of the tip of the additive material that penetrates the energy irradiation point.

The present disclosure has been made in consideration of the above, and aims to provide an additive manufacturing device that can more accurately measure and control the displacement in the X-axis and Y-axis directions and the position in the Z-axis direction of the tip of the additive material that penetrates the energy irradiation point than ever before.

In order to solve the above-mentioned problems and achieve the object, the additive manufacturing apparatus according to the present disclosure includes a stage, a nozzle, an additive material supply unit, a heat source generation unit, an oscillator, a vibration sensor, a displacement measuring instrument, a first control unit, and a second control unit. The stage supports a base plate having a first surface parallel to an XY plane formed by an X-axis and a Y-axis perpendicular to each other. The nozzle supplies additive material toward a processing surface, which is either the first surface of the base plate or a surface constituting a deposit formed on the base plate, and is movable within the XY plane. The additive material supply unit supplies additive material to the nozzle. The heat source generation unit generates a heat source on the processing surface. The oscillator is capable of applying vibration to one of the stage and the additive material. The vibration sensor is capable of detecting vibration on the other of the stage and the additive material to which vibration is not applied by the oscillator. The displacement measuring instrument measures the amount of displacement of the additive material in the X-axis and Y-axis directions. The first control unit performs control to correct the position of the nozzle on the XY plane based on the measurement result of the displacement measuring instrument. The second control unit obtains the detection results of the vibrations generated by the vibrator from the vibration sensor, estimates the positional relationship between the tip of the additional material and the processing surface in the Z-axis direction perpendicular to the XY plane based on the detection results, and controls the supply state of the additional material in the additional material supply unit based on the estimation results.

The present disclosure has the advantage of being able to measure and control the displacement in the X-axis and Y-axis directions and the position in the Z-axis direction of the tip of the added material penetrating the energy irradiation point more accurately than ever before.

FIG. 1 is a diagram showing a schematic configuration example of an additive manufacturing apparatus according to a first embodiment; FIG. 1 is a cross-sectional view showing a schematic diagram of a moving stage and a processing head of an additive manufacturing apparatus according to a first embodiment; FIG. 1 is a schematic diagram showing an example of an outline of control of an additive manufacturing apparatus according to a first embodiment; FIG. 1 shows an example of wire displacement on a processing surface. FIG. 1 is a diagram showing an example of a state in which the tip of the wire is in contact with the processing surface; FIG. 1 is a schematic diagram showing an example of a state in which the tip of the wire comes into contact with the processing surface via the molten pool. FIG. 1 is a schematic diagram showing an example of a state in which the tip of the wire is not in contact with either the processing surface or the molten pool. FIG. 1 is a block diagram showing an example of an outline of a wire supply control process of an additive manufacturing apparatus according to a first embodiment; 1 is a flowchart showing an example of a procedure for a method for manufacturing a three-dimensional object according to the first embodiment. A flowchart showing an example of a procedure for correcting the position of a wire nozzle in an XY plane. A flowchart showing an example of a procedure for a wire supply control process of a wire supply unit. FIG. 1 is a cross-sectional view showing a schematic example of a state in which a gas layer is formed in a method for producing a three-dimensional object. FIG. 1 is a cross-sectional view showing a schematic example of a state in which a gas layer is formed in a method for producing a three-dimensional object. FIG. 13 is a schematic diagram showing an example of the configuration of the movable stage and its surroundings in an additive manufacturing apparatus according to a second embodiment; FIG. 13 is a schematic diagram showing an example of the configuration of the movable stage and its surroundings in an additive manufacturing apparatus according to a second embodiment; FIG. 13 is a schematic diagram showing an example of the configuration of an additive manufacturing apparatus according to a third embodiment; FIG. 11 is a block diagram showing an example of an outline of a wire supply control process of an additive manufacturing apparatus according to a third embodiment; FIG. 1 is a block diagram showing an example of a hardware configuration of a control unit, an XY-axis control unit, and a Z-axis control unit provided in an additive manufacturing device according to embodiments 1 to 3;

Below, the additive manufacturing device and the method for manufacturing a three-dimensional object according to the embodiment of the present disclosure are described in detail with reference to the drawings.

Embodiment 1.
The additive manufacturing device described in the following embodiments is an additive manufacturing device that applies a DED-type additive manufacturing method using a wire as an additive material. The DED-type additive manufacturing method using a wire includes a supplying step of supplying a wire from a wire nozzle toward a processing surface, and a melting and solidifying step of irradiating a heat source onto the wire on the processing surface to melt and solidify the material to obtain a deposit, and is a method for manufacturing a three-dimensional object, which is a three-dimensional object, by repeating the supplying step and the melting and solidifying step. Here, the object refers to an object manufactured by stacking deposits. An example of the heat source is a laser beam, an electron beam, or an arc discharge.

Figure 1 is a schematic diagram showing an example of the configuration of an additive manufacturing device according to embodiment 1. The additive manufacturing device 1 includes a moving stage 11, a laser oscillator 21, a gas supply unit 22, a chiller 23, a wire supply unit 30, a processing head 40, and a control unit 50. In Figure 1, in a plane parallel to the base plane on which the three-dimensional object 61 is formed, the X-axis and Y-axis are taken in directions perpendicular to each other, and the Z-axis is taken in a direction perpendicular to both the X-axis and the Y-axis.

The moving stage 11 supports a base plate 12 that serves as a base for stacking the three-dimensional object 61, and the base plate 12 can be moved to a desired position by a drive mechanism (not shown). FIG. 2 is a cross-sectional view that shows a schematic diagram of the moving stage and processing head of the additive manufacturing device according to the first embodiment. The moving stage 11 can be moved along the X-axis, Y-axis, and Z-axis directions by a drive mechanism (not shown). As shown in FIG. 2, the moving stage 11 can also be moved in the rotational directions of the A-axis and Θ-axis. The A-axis is a rotational axis that passes through the center of the moving stage 11 in the Y-axis direction and is parallel to the X-axis. The Θ-axis is a rotational axis that passes through the center of the moving stage 11 in the Y-axis direction and is parallel to the Z-axis. The moving stage 11 corresponds to a stage.

The base plate 12 is provided on the upper surface of the moving stage 11. The base plate 12 is a metal plate having a first surface parallel to the XY plane. The base plate 12 may be something other than a metal plate having a flat surface, and may have a shape that can be installed on the moving stage 11, such as a cylinder or a blade shape.

Returning to FIG. 1, the laser oscillator 21 is an example of a heat source generating unit that generates a heat source on the processing surface, which is the surface on which the wire 31, which is the additional material, is deposited. The laser oscillator 21 oscillates a laser beam L, which serves as a heat source, based on instructions from the control unit 50. In the first embodiment, the laser beam L from the laser oscillator 21 passes through a fiber cable 24, which is an optical transmission path, and a condenser lens and a protective lens, which are not shown, and propagates to a beam nozzle 42 of the processing head 40, which will be described later. Then, the laser beam L from the beam nozzle 42 is irradiated onto the processing surface. In the following embodiment, the heat source for melting the wire 31 is the laser beam L, but an electron beam, arc discharge, and the like can be selected in addition to the laser beam L. When an electron beam is selected, the heat source generating unit becomes an electron gun, and when an arc discharge is selected, the heat source generating unit becomes a power source that applies a voltage between the arc welding rod, which is the supply source of the additional material, and the moving stage 11.

The gas supply unit 22 supplies gas to the gas nozzle 43 of the processing head 40, which will be described later, based on instructions from the control unit 50. As the gas, a shielding gas G is used, which is a gas for suppressing oxidation of and cooling the deposit 63 when the wire 31 is melted and solidified by the laser beam L to form the deposit 63 on the processing area 62. Examples of the shielding gas G include nitrogen gas and argon gas. The processing area 62 will be described later.

The chiller 23 cools the additive manufacturing device 1. In one example, the chiller 23 circulates a cooling medium such as water between the processing head 40 and the laser oscillator 21 to prevent the processing head 40 from becoming hotter than a predetermined temperature.

The wire supply unit 30 is a device that supplies the wire 31, which is an additional material, to the wire nozzle 41 of the processing head 40 described later. The wire supply unit 30 includes a wire reel 32, a motor 33, a wire holder 34, a wire feed roller 35, and a wire cable 36. The wire reel 32 is the source of the wire 31 to be supplied to the wire nozzle 41. The wire 31 is wound around the wire reel 32. The motor 33 is connected to the rotation shaft of the wire reel 32 and rotates the wire reel 32. The wire holder 34 holds the wire reel 32 to which the motor 33 is connected. The wire feed roller 35 is disposed between the wire reel 32 and the wire nozzle 41 and straightens the wire 31 from the wire reel 32. The wire cable 36 is a hollow cylindrical member that covers the exposed surface of the wire 31 between the wire feed roller 35 and the wire nozzle 41. The wire supply unit 30 corresponds to the additional material supply unit.

The processing head 40 is disposed opposite the base plate 12, and in accordance with instructions from the control unit 50, supplies the wire 31 onto the processing area 62, irradiates the laser beam L onto the processing area 62, and sprays shielding gas G around the wire 31 on the processing area 62. The processing area 62 is an area on the base plate 12 where the traveling direction of the laser beam L intersects with the area to which the wire 31 is supplied. The processing head 40 can be moved in the X-axis direction, the Y-axis direction, and the Z-axis direction by a drive mechanism (not shown). As shown in FIG. 2, the processing head 40 has a wire nozzle 41, a beam nozzle 42, and a gas nozzle 43.

The wire nozzle 41 is connected to the wire cable 36 of the wire supply unit 30, and supplies the wire 31 from the supply port 41a toward the processing area 62 on the base plate 12. The wire nozzle 41 corresponds to a nozzle that supplies additional material toward the processing surface, which is either the upper surface, which is the first surface of the base plate 12, or one of the surfaces that constitute the deposit 63 formed on the base plate 12.

The beam nozzle 42 is connected to the laser oscillator 21 via a fiber cable 24, and emits the laser beam L emitted from the laser oscillator 21. The beam nozzle 42 is positioned so that the exit port of the laser beam L faces the base plate 12.

The gas nozzle 43 is connected to the gas supply unit 22 via piping, and sprays the shielding gas G from the gas supply unit 22. The gas nozzle 43 is arranged coaxially with the wire nozzle 41, and the shielding gas G is sprayed around the wire 31. The beam nozzle 42 is arranged so that the laser beam L is irradiated within the area surrounded by the shielding gas G.

Returning to FIG. 1, the control unit 50 controls the entire additive manufacturing apparatus 1. FIG. 3 is a diagram showing a schematic example of an overview of the control of the additive manufacturing apparatus according to embodiment 1. As shown in FIG. 3, the control unit 50 controls the movement of the moving stage 11, the operation of the laser oscillator 21, the gas supply of the gas supply unit 22, the wire supply of the wire supply unit 30, and the movement of the processing head 40. In one example, the control unit 50 performs these controls according to a predetermined program. In addition, cooling water, which is a cooling medium, is circulated between the chiller 23 and the laser oscillator 21 and processing head 40.

In controlling the movement of the movable stage 11, the control unit 50 moves the position of the processing surface of the base plate 12 placed on the movable stage 11. The control unit 50 moves the movable stage 11 in any of the X-axis, Y-axis, and Z-axis directions, and in some cases also rotates it around the A-axis and Θ-axis. This positions the processing surface facing the processing head 40. The area on the processing surface where the deposit 63 is formed is the part that becomes the processing area 62. At the start of modeling, the upper surface of the base plate 12 in the Z direction becomes the processing surface, but as modeling progresses, one of the surfaces that make up the deposit 63 formed on the base plate 12 becomes the processing surface.

In controlling the operation of the laser oscillator 21, the control unit 50 controls the intensity of the laser beam L, whether or not to emit the laser beam L, etc. In controlling the gas supply of the gas supply unit 22, the control unit 50 controls the flow rate of the shielding gas G supplied from the gas supply unit 22, whether or not to supply the shielding gas G, etc.

In the wire supply control of the wire supply unit 30, the control unit 50 controls the supply state of the wire 31 fed from the wire nozzle 41. Examples of the supply state of the wire 31 include the supply speed of the wire 31 and correction of the tip position of the wire 31.

In controlling the movement of the processing head 40, the control unit 50 moves the position of the processing head 40 on the base plate 12. In other words, the control unit 50 moves the irradiation position of the laser beam L toward the processing surface. The control unit 50 moves the processing head 40 in any of the X-axis direction, Y-axis direction, and Z-axis direction. In one example, the control unit 50 controls the position of the processing head 40 on the base plate 12 according to data for forming the three-dimensional object 61.

In the additive manufacturing device 1 having such a configuration, the wire reel 32 is usually cylindrical in shape, and has a groove in the center of the cylindrical surface for fitting the wire reel 32 into the wire holder 34, and a groove in the cylindrical side surface for holding the wire 31. The wire reel 32 holds the wire 31 by winding it in a circular shape in the groove on the side surface of the cylinder. The wire supply unit 30 supplies the wire 31 to the wire nozzle 41 of the processing head 40. For this reason, a circular distortion occurs in the central axis of the wire 31 when it is held by the wire reel 32, and this circular distortion remains in the central axis of the wire 31 even when the wire 31 is fed out from the wire supply unit 30. Therefore, the wire supply unit 30 or the processing head 40 uses a wire feed roller 35 that corrects the wire 31. The wire feed roller 35 has multiple rollers. When the wire 31 passes through the wire feed roller 35, pressure is applied to the wire 31 between the rollers, and the distortion of the wire 31 is corrected. The wire 31 sent out from the wire feed roller 35 passes through the inside of the wire cable 36 and is sent to the wire nozzle 41. The wire cable 36 is a hollow cylinder made of a flexible resin that deforms in accordance with the movement of the wire 31. However, it is difficult to completely remove distortion with the wire feed roller 35, and even with a straightened wire 31, the portion exposed from the wire nozzle 41 often has a deflection in either the X-axis or Y-axis direction.

The wire 31 supplied from the wire supply unit 30 is fed by the wire nozzle 41 toward the machining surface. The wire 31 travels from the supply port 41a in the Z-axis direction, which is the supply direction of the wire 31, and the laser beam L is irradiated onto the fed wire 31. However, the central axis of the wire 31 exposed from the supply port 41a of the wire nozzle 41 is displaced from the originally intended supply point in the absence of distortion due to the circular distortion caused by being held by the wire reel 32 as described above. As a result, a displacement occurs in the X-axis or Y-axis direction from the set value set in the positional relationship between the wire 31 and the focus of the laser beam L.

Figure 4 is a diagram showing an example of the displacement of the wire on the machining surface. Figure 4 shows an example of the relationship between the base plate 12 and the wire nozzle 41 in the XZ plane. As shown in Figure 4, the wire 31 supplied from the wire nozzle 41 contacts the machining surface through the molten pool 64 in which the wire 31 is melted. In addition, the wire 31 has distortion, and the tip of the wire 31 is slightly bent in the negative direction of the X axis. In other words, if the central axis of the wire 31 near the supply port 41a of the wire nozzle 41 is the ideal central axis A0, the position of the center of the tip of the wire 31 near the machining surface is displaced in the negative direction of the X axis compared to the position of the ideal central axis A0. As a result, the actual central axis A1 parallel to the Z axis passing through the center of the tip of the wire 31 is deviated from the ideal central axis A0. Figure 4 shows the case when viewed from the Y axis direction, but the same is true when viewed from the X axis direction. If the amount of displacement in the X-axis or Y-axis direction exceeds the irradiation range of the laser beam L that melts the wire 31, the wire 31 will not melt sufficiently, resulting in defective molding. Hereinafter, the appropriate irradiation range of the laser beam L, which is the heat source that melts the wire 31, will be referred to as the appropriate irradiation range.

Therefore, in the first embodiment, a configuration is maintained in which the amount of displacement in the X-axis or Y-axis direction caused by distortion of the wire 31 does not exceed the appropriate range for irradiation of the laser beam L. In other words, as shown in FIG. 1, the additive manufacturing device 1 according to the first embodiment further includes a displacement measuring device 37, an actuator 44, and an XY-axis control unit 51.

The displacement meter 37 measures the displacement of the wire 31 in the X-axis and Y-axis directions. Specifically, the displacement meter 37 measures the displacement from the wire feed roller 35's feed position in the XY plane at a position at a predetermined distance downstream of the wire 31's feed direction from the wire feed roller 35's feed position. In one example, the wire feed roller 35's feed position can be the end of the roller located downstream of the wire feed roller 35's feed direction. The displacement meter 37 measures the displacement of the wire 31 in the X-axis or Y-axis direction for a certain section, such as a section having an invariable or measurable distance, such as from the wire feed roller 35's feed position to the displacement meter 37 attached downstream of the wire 31's feed direction. One example of the displacement meter 37 is two laser displacement meters installed in the X-axis and Y-axis directions at the end of a section having a measurable distance. Furthermore, when the XY plane is a horizontal plane, the wire feed roller 35 is positioned so that the wire 31 is fed in a vertical direction in order to measure the displacement of the wire 31 in the horizontal plane. The displacement measuring device 37 outputs the measurement results to the XY axis control unit 51.

The actuator 44 is a movement mechanism that moves the position of the wire nozzle 41 in the processing head 40 in the X-axis and Y-axis directions according to instructions from the XY-axis control unit 51. In other words, the position of the wire nozzle 41 is variable in the X-axis and Y-axis directions. As an example, the wire nozzle 41 is provided with an actuator 44 that moves the wire nozzle 41 in the X-axis direction, and an actuator 44 that moves the wire nozzle 41 in the Y-axis direction. The actuator 44 operates according to instructions from the XY-axis control unit 51, and moves the wire nozzle 41 by the value given by the instruction.

The XY-axis control unit 51 performs control to correct the position of the wire nozzle 41 on the XY plane based on the measurement results of the displacement measuring device 37. The XY-axis control unit 51 corresponds to the first control unit. In FIG. 1, the XY-axis control unit 51 is shown separately from the control unit 50, but is one of the processing units that performs wire supply control of the wire supply unit 30 of the control unit 50. For this reason, the XY-axis control unit 51 may be configured to be provided within the control unit 50.

The XY-axis control unit 51 calculates the unit displacement amount, which is the amount of displacement in the X-axis and Y-axis directions per unit length of the wire 31, from the measurement results of the displacement measuring device 37. For example, in the simplest configuration, the distance from the feed position of the wire feed roller 35 to the end of the section with a measurable distance is defined as α, the origin is the feed position of the wire feed roller 35, the amount of displacement in the X-axis direction at the end of the section with a measurable distance is defined as β, and the amount of displacement in the Y-axis direction is defined as γ. In this case, the unit displacement amount of the wire 31 in the X-axis and Y-axis directions can be calculated as β/α and γ/α, respectively.

Alternatively, there may be two sections with measurable distances. In this case, the distances to the ends of the two sections with measurable distances are defined as α1 and α2, respectively, the origin is defined as the feed position of the wire feed roller 35, the displacement amounts in the X-axis direction at the ends of the two sections with measurable distances are defined as β1 and β2, respectively, and the displacement amounts in the Y-axis direction are defined as γ1 and γ2, respectively, to generate a function. By using this function, the XY-axis control unit 51 can more accurately calculate the displacement amounts in the X-axis direction and the Y-axis direction per unit length. This allows the XY-axis control unit 51 to obtain the amount of distortion of the wire 31 fed out from the wire nozzle 41.

The wire 31 that has passed through the displacement measuring device 37 passes through the inside of the wire cable 36 and is supplied to the wire nozzle 41. At this time, the wire cable 36 moves in accordance with the movement of the wire 31. Therefore, the wire cable 36 does not affect the amount of distortion of the wire 31. Therefore, it can be assumed that the unit displacement amount of the wire 31 in the X-axis and Y-axis directions calculated by the XY-axis control unit 51 is also maintained for the wire 31 that is supplied downstream in the supply direction from the feed position of the wire feed roller 35.

The XY-axis control unit 51 also uses the unit displacement amount of the wire 31 in the X-axis direction and the Y-axis direction to calculate the displacement amount of the tip of the wire 31 in the X-axis direction and the Y-axis direction with the position of the wire nozzle 41 as the origin, and determines whether the wire 31 is in the appropriate irradiation range of the laser beam L. Hereinafter, the displacement amount in the X-axis direction and the Y-axis direction are referred to as the displacement amount in the XY plane. When the wire 31 is not in the appropriate irradiation range of the laser beam L, the XY-axis control unit 51 generates an instruction to move the wire nozzle 41 so that the tip of the wire 31 is in the appropriate irradiation range of the laser beam L, and controls the actuator 44. Here, the appropriate irradiation range of the laser beam L is the range in the irradiation area of the laser beam L where the laser beam L is irradiated to the tip of the wire 31, the tip of the wire 31 melts and solidifies, and the deposit 63 can be appropriately formed on the processing surface. Since the position of the beam nozzle 42 in the processing head 40 is fixed, if the position of the wire nozzle 41 relative to the beam nozzle 42 and the amount of displacement at the tip of the wire 31 are known, it is possible to determine whether the tip of the wire 31 is within the appropriate range for irradiation with the laser beam L.

For example, the displacement amount of the tip of the wire 31 from the reference position in the XY plane is calculated by multiplying the calculated unit displacement amount of the wire 31 in the X-axis and Y-axis directions by the distance from the supply port 41a of the wire 31 of the wire nozzle 41 to the processing surface. In one example, the displacement amount of the tip of the wire 31 can be used as the correction value of the wire nozzle 41. The XY-axis control unit 51 then controls the actuator 44 of the wire nozzle 41 using the correction value of the wire nozzle 41 as an instruction.

When an instruction is input, the actuator 44 operates according to the instruction. This causes the wire nozzle 41 to move in the XY plane so that the tip of the wire 31 is positioned within the appropriate range for irradiation by the laser beam L. This series of operations makes it possible to correct the amount of displacement in the X-axis or Y-axis direction caused by distortion of the wire 31, and makes it possible to maintain appropriate modeling conditions without the tip of the wire 31 going beyond the appropriate range for irradiation by the laser beam L.

Here, the actuator 44 that drives the wire nozzle 41 has been described as being configured to move the wire nozzle 41 in the X-axis and Y-axis directions in response to the amount of distortion acquired by the displacement measuring device 37, but the method of correcting the tip of the wire 31 is not limited to this. For example, it is of course possible to move the wire nozzle 41 in the Z-axis direction by the actuator 44. When the amount of distortion of the wire 31 is large, it is possible to correct the amount of distortion in a small space by moving in the X-axis, Y-axis, and Z-axis directions.

1, the displacement measuring device 37 is installed downstream of the wire feed roller 35 in the supply direction of the wire 31, but the location of the displacement measuring device 37 is not limited as long as it is on the path from the wire feed roller 35 to the wire nozzle 41. It is also desirable that the distance from the displacement measuring device 37 to the wire nozzle 41 is as short as possible. For this reason, the displacement measuring device 37 may be provided below the actuator 44 inside the processing head 40. In this case, the XY-axis control unit 51 calculates the unit displacement amount of the wire 31 in the XY plane from the distortion amount of the wire 31 in the XY plane at the distance from the actuator 44 to the displacement measuring device 37. Then, the XY-axis control unit 51 uses this unit displacement amount to calculate the position of the tip of the wire 31 supplied from the wire nozzle 41 to the processing surface side, and corrects the position of the wire nozzle 41 based on this position. This configuration shortens the distance from the displacement measuring device 37 to the wire nozzle 41, making it possible to reduce errors when calculating the displacement of the wire 31 supplied from the wire nozzle 41 in the XY directions.

The above describes a configuration for correcting the amount of displacement of the tip of the wire 31 in the XY plane due to distortion of the wire 31. In the additive manufacturing device 1, it is also required to appropriately control the position of the tip of the wire 31 in the Z-axis direction. Figures 5, 6, and 7 are diagrams that show an example of the positional relationship of the tip of the wire, the processing surface, and the molten pool in the Z-axis direction. Figure 5 is a diagram that shows an example of a state in which the tip of the wire contacts the processing surface, Figure 6 is a diagram that shows an example of a state in which the tip of the wire contacts the processing surface via the molten pool, and Figure 7 is a diagram that shows an example of a state in which the tip of the wire is not in contact with either the processing surface or the molten pool. The molten pool 64 is a portion of the wire 31 that is in a melted state by the laser beam L. In addition, these figures show the state as viewed from the Y-axis direction.

As shown in FIG. 6, the optimum state for forming is when the tip of the wire 31 is in the molten pool 64 but not in contact with the processing surface. However, since the wire 31 is melted by the laser beam L while being fed toward the processing surface, the position of the tip is constantly changing. In addition, if the feed speed of the wire 31 is too high in the Z-axis direction of the processing surface, as shown in FIG. 5, the wire 31 will bend as the wire 31 pokes the three-dimensional object 61 or the base plate 12, resulting in defective forming. Conversely, if the feed speed of the wire 31 is too low, as shown in FIG. 7, the molten wire 31m will not be deposited on the processing surface and will remain as droplets at the tip of the wire 31. As a result, discontinuous forming may occur, or the droplets generated at the tip of the wire nozzle 41 may solidify, causing clogging of the wire nozzle 41.

Therefore, in the first embodiment, a configuration is retained for acquiring information on the positional relationship between the machining surface and the wire 31 in the Z-axis direction, and controlling the supply state of the wire 31 in the wire supply unit 30 based on the acquired information. The positional relationship is one of the following: a state in which the machining surface of the three-dimensional object 61 and the wire 31 are in direct contact with each other, as shown in FIG. 5; a state in which the molten pool 64 is interposed between the machining surface of the three-dimensional object 61 and the wire 31, as shown in FIG. 6; and a state in which the wire 31 is separated from both the machining surface of the three-dimensional object 61 and the molten pool 64, as shown in FIG. 7. In the following, the states shown in FIG. 5, FIG. 6, and FIG. 7 are referred to as state A, state B, and state C, respectively. These three states A, B, and C can be detected by adding vibration to the three-dimensional object 61. For this reason, as shown in FIG. 1, the additive manufacturing device 1 according to the first embodiment further includes a vibrator 13, a vibration sensor 38, and a Z-axis control unit 52.

The oscillator 13 applies vibration to the moving stage 11. In this specification, vibration includes rocking. In one example, the oscillator 13 is provided on the underside of the moving stage 11 opposite the surface on which the base plate 12 is placed, in correspondence with the position of the base plate 12 in the XY plane. The oscillator 13 vibrates based on instructions from the control unit 50 or the Z-axis control unit 52.

The vibration sensor 38 is applied to the moving stage 11 by the vibrator 13 and detects the vibration transmitted through the three-dimensional model 61, the molten pool 64, and the wire 31. The vibration sensor 38 may be any sensor capable of detecting the intensity of longitudinal waves, the intensity of transverse waves, and the propagation speed. The vibration sensor 38 is provided in the wire nozzle 41 or the wire supply unit 30. In the example of FIG. 1, the vibration sensor 38 is attached to the wire feed roller 35 constituting the wire supply unit 30. The vibration sensor 38 outputs the vibration detection result to the Z-axis control unit 52. The vibration detection result includes the intensity of longitudinal waves, the intensity of transverse waves, and the propagation speeds of longitudinal waves and transverse waves. By providing the vibration sensor 38, it is possible to detect the vibration applied by the vibrator 13 in order to obtain the positional relationship between the machining surface and the tip of the wire 31.

The Z-axis control unit 52 obtains the detection result of the vibration generated by the vibrator 13 from the vibration sensor 38, estimates the positional relationship between the tip of the wire 31 in the Z-axis direction and the machining surface based on the detection result, and controls the supply speed of the wire 31 in the wire supply unit 30 and the supply state of the wire 31, which is the position of the tip of the wire 31, based on the estimation result. Note that in FIG. 1, the Z-axis control unit 52 is displayed separately from the control unit 50, but it is one of the processing units that controls the wire supply of the wire supply unit 30 of the control unit 50. For this reason, the Z-axis control unit 52 may be configured to be provided within the control unit 50. The Z-axis control unit 52 corresponds to the second control unit.

Here, the details of the processing in the Z-axis control unit 52 will be described. As shown in Figures 5 to 7, the moving stage 11, base plate 12, and three-dimensional object 61 are solids, the molten pool 64 is liquid, and the wire 31 is solid. A solid can propagate both longitudinal waves and transverse waves from the oscillator 13. A liquid can propagate longitudinal waves, but cannot propagate transverse waves. Furthermore, if the wire 31 is separated from both the machining surface of the three-dimensional object 61 and the molten pool 64, the longitudinal waves and transverse waves cannot propagate to the vibration sensor 38.

In the first embodiment, by utilizing these characteristics, it is estimated whether the positional relationship between the processing surface and the wire 31 is in state A, B, or C. First, as shown in FIG. 5, in state A where the tip of the wire 31 is in contact with the processing surface of the three-dimensional model 61, the vibration of the vibrator 13 installed on the moving stage 11 propagates to the wire 31 through the three-dimensional model 61 as longitudinal waves and transverse waves. Therefore, the vibration sensor 38 installed on the wire feed roller 35 detects both longitudinal waves and transverse waves. In other words, when both longitudinal waves and transverse waves are detected by the vibration sensor 38, the Z-axis control unit 52 estimates that the state is A shown in FIG. 5, and controls the wire supply unit 30 so that the state is the appropriate state shown in FIG. 6, that is, the tip of the wire 31 is not in contact with the processing surface. In this case, the supply speed of the wire 31 is greater than the speed at which the wire 31 melts, so that the tip of the wire 31 comes into contact with the three-dimensional model 61. For this reason, the Z-axis control unit 52 performs control to reduce the speed at which the wire 31 is supplied from the wire supply unit 30 so that the melting speed of the wire 31 becomes equal to the supply speed of the wire 31. Alternatively, if the actuator 44 is capable of moving the wire nozzle 41 in the Z-axis direction, the Z-axis control unit 52 may perform control to raise the tip of the wire 31 in the Z-axis direction using the actuator 44. In this case, the Z-axis control unit 52 may perform both controls, such as raising the tip of the wire 31 using the actuator 44 while lowering the supply speed of the wire 31.

Next, as shown in FIG. 6, in the state B where the machining surface of the three-dimensional object 61 and the wire 31 are in contact with each other through the molten pool 64, the longitudinal waves can propagate through the molten pool 64, but the transverse waves cannot propagate through the molten pool 64. Therefore, the vibration sensor 38 detects only the longitudinal waves and not the transverse waves. In this state, the positional relationship between the three-dimensional object 61, the wire 31, and the molten pool 64 is appropriate. In addition, since the propagation speed of the longitudinal waves differs by about 10 times between a liquid and a solid, the vibration applied to the vibrator 13 can be a pulse wave or a waveform that can detect the time history, such as a different waveform, to estimate the distance between the tip of the wire 31 and the machining surface of the three-dimensional object 61 from the propagation time. The Z-axis control unit 52 can control the supply speed of the wire 31 so as to obtain a distance that is desirable for performing the molding process, using the estimated distance between the tip of the wire 31 and the machining surface.

Next, as shown in FIG. 7, when the wire 31 is in state C, where the wire 31 is separated from both the machining surface of the three-dimensional object 61 and the molten pool 64, the vibration sensor 38 detects neither longitudinal waves nor transverse waves. In this case, the Z-axis control unit 52 may stop the modeling process, or may increase the feed speed of the wire 31 so that the tip of the wire 31 is directed toward the machining surface.

In this way, the Z-axis control unit 52 estimates the positional relationship between the three-dimensional object 61, the wire 31, and the molten pool 64 by evaluating the vibrations caused by the vibrator 13 in the additive manufacturing device 1 using the detection results of the vibration sensor 38, and can control the supply speed of the wire 31 or the position of the tip of the wire 31 based on the estimated positional relationship. In the above description, the vibrator 13 is installed on the moving stage 11 and the vibration sensor 38 is installed on the wire feed roller 35, but this is just one example. For example, it is also possible to install the vibrator 13 on the side where the three-dimensional object 61 is placed, and install the vibration sensor 38 at any location from the wire supply unit 30 to the wire nozzle 41. In one example, the vibrator 13 may be installed on the three-dimensional object 61, and the vibration sensor 38 may be installed directly below the wire nozzle 41. Also, since it is only necessary to detect the vibration transmitted between the three-dimensional object 61 and the wire 31, the vibrator 13 may be installed at any position between the wire supply unit 30 and the wire nozzle 41, and the vibration sensor 38 may be installed on the side where the three-dimensional object 61 is placed, in the opposite manner to the above. In other words, the vibrator 13 may be installed at a position where it can impart vibration to one of the moving stage 11 and the wire 31, which is the added material, and the vibration sensor 38 may be installed at a position where it can detect vibration on the other of the moving stage 11 and the wire 31 that is not imparted vibration by the vibrator 13.

Figure 8 is a block diagram showing a schematic example of an overview of the wire supply control process of the additive manufacturing device according to the first embodiment. As shown in Figure 8, the wire supply unit 30 is provided with a displacement meter 37 that detects the distortion of the wire 31 in the X-axis direction and the Y-axis direction. The XY-axis control unit 51 calculates the amount of displacement of the tip of the wire 31 based on the position of the wire 31 fed from the wire nozzle 41 in the XY plane according to the measurement result of the displacement meter 37. In addition, the XY-axis control unit 51 outputs an instruction to the actuator 44 to correct the position of the wire nozzle 41 based on the calculated amount of displacement so that the tip of the wire 31 falls within the appropriate irradiation range of the laser beam L. The actuator 44 then corrects the position of the wire nozzle 41 in the XY direction.

On the other hand, during the modeling process, the vibrator 13 applies vibration to the base plate 12. This vibration is transmitted from the base plate 12 to the wire 31 via the three-dimensional model 61. The intensity of the longitudinal wave, the intensity of the transverse wave, and the propagation speed are detected by a vibration sensor 38 provided between the wire supply unit 30 and the wire nozzle 41. The Z-axis control unit 52 estimates the positional relationship between the tip of the wire 31 and the processing surface based on the detection result by the vibration sensor 38. Based on the estimation result, the Z-axis control unit 52 determines the supply speed of the wire 31 or the displacement amount of the tip of the wire 31 in the Z-axis direction, and outputs an instruction to the wire supply unit 30 to control the operation of the wire supply unit 30. The wire supply unit 30 then changes the supply speed of the wire 31 or the position of the tip of the wire 31 according to the instruction.

Next, a method for manufacturing a three-dimensional object 61 in the additive manufacturing device 1 shown in FIG. 1 will be described. FIG. 9 is a flowchart showing an example of the procedure of the method for manufacturing a three-dimensional object according to the first embodiment. First, the control unit 50 moves the processing head 40 to a position facing the position on the base plate 12 where the three-dimensional object 61 is to be formed (step S11). Next, the control unit 50 causes the wire nozzle 41 to supply the wire 31 toward the processing surface on the base plate 12 (step S12). At this time, the XY-axis control unit 51 performs a position correction process on the XY plane of the wire nozzle 41 (step S13). After that, the control unit 50 causes the laser oscillator 21 to irradiate the laser beam L onto the processing surface (step S14). At this time, the tip of the wire 31 is within the appropriate irradiation range of the laser beam L due to the position correction process on the XY plane of the wire nozzle 41. In addition, the tip of the wire 31 is melted by irradiating the tip of the wire 31 with the laser beam L, and a molten pool 64 is formed on the processing surface.

Then, the Z-axis control unit 52 acquires the positional relationship between the tip of the wire 31 and the machining surface, and performs wire supply control processing of the wire supply unit 30 if necessary (step S15). An example of control processing of the supply state of the wire 31 by the wire supply unit 30 is correction of the supply speed of the wire 31 or the position of the tip of the wire 31 in the Z-axis direction. Then, the control unit 50 judges whether the modeling process has been completed (step S16). If it is determined that the modeling process has not been completed (No in step S16), the process returns to step S11. On the other hand, if it is determined that the modeling process has been completed (Yes in step S16), the three-dimensional object 61 is completed on the base plate 12, and the modeling process is completed.

Here, the position correction process in the XY plane of the wire nozzle 41 in step S13 in FIG. 9 will be described. FIG. 10 is a flowchart showing an example of the procedure for the position correction process in the XY plane of the wire nozzle. First, the displacement measuring device 37 measures the distortion in the X-axis and Y-axis directions of the wire 31 sent out from the sending position of the wire feed roller 35 (step S31). The XY-axis control unit 51 calculates the unit displacement amount in the X-axis and Y-axis directions of the wire 31 using the distortion in the X-axis and Y-axis directions measured by the displacement measuring device 37 (step S32). Next, the XY-axis control unit 51 calculates the displacement amount of the tip of the wire 31 based on the sending position of the wire nozzle 41 in the XY plane from the calculated unit displacement amount in the X-axis and Y-axis directions and the distance between the sending position of the wire nozzle 41 and the processing surface (step S33). The XY-axis control unit 51 outputs a correction command to the actuator 44 to correct the position of the wire nozzle 41 based on the calculated displacement of the tip of the wire 31 (step S34). The actuator 44 corrects the position of the wire nozzle 41 based on the correction command (step S35), and the process returns to FIG. 9.

Next, the wire supply control process of the wire supply unit 30 in step S15 of FIG. 9 will be described. FIG. 11 is a flowchart showing an example of the procedure of the wire supply control process of the wire supply unit. First, the Z-axis control unit 52 causes the vibrator 13 to generate vibrations (step S51). The vibration sensor 38 detects the result of the vibration generated by the vibrator 13 and outputs the detection result to the Z-axis control unit 52.

The Z-axis control unit 52 determines whether vibration is detected by the vibration sensor 38 (step S52). If vibration is detected by the vibration sensor 38 (Yes in step S52), the Z-axis control unit 52 determines the type of wave detected (step S53). If both longitudinal and transverse waves are detected (longitudinal and transverse waves in step S53), the Z-axis control unit 52 estimates that the tip of the wire 31 is in contact with the processing surface (step S54). Then, the Z-axis control unit 52 outputs an instruction to the wire supply unit 30 to reduce the supply speed of the wire 31 or to raise the tip of the wire 31 in the Z-axis direction (step S55). In accordance with the instruction, the wire supply unit 30 reduces the supply speed of the wire 31 or raises the tip of the wire 31 in the Z-axis direction (step S56). After that, the process returns to FIG. 9.

If only longitudinal waves are detected in step S53 (if only longitudinal waves are detected in step S53), the Z-axis control unit 52 estimates that the tip of the wire 31 is in contact with the machining surface via the molten pool 64 (step S57). In other words, the positional relationship between the tip of the wire 31 and the molten pool 64 is appropriate, and the feed speed of the wire 31 and the position of the tip of the wire 31 are also appropriate. The Z-axis control unit 52 calculates the distance between the machining surface and the tip of the wire 31 from the propagation speed detected by the vibration sensor 38 (step S58). The Z-axis control unit 52 also controls the feed speed of the wire 31 based on the calculated distance between the machining surface and the tip of the wire 31 (step S59). Then, the process returns to FIG. 9.

When in state B, the molding process is being performed in an appropriate state, but even in state B, if the tip of the wire 31 is close to the machining surface or close to the upper end of the molten pool 64, there is a possibility that the state may transition to state A or state C. For this reason, in such cases, the Z-axis control unit 52 controls the feed speed of the wire 31 or the position of the tip of the wire 31 so that the tip of the wire 31 is located near the center of the molten pool 64.

If no vibration is detected by the vibration sensor 38 in step S52 (No in step S52), the Z-axis control unit 52 estimates that the tip of the wire 31 is separated from both the machining surface and the molten pool 64 (step S60). The Z-axis control unit 52 then controls the supply speed of the wire 31 or the position of the tip of the wire 31 so that the tip of the wire 31 contacts the molten pool 64 (step S61), and the process returns to FIG. 9. Note that in step S61, the tip of the wire 31 may have melted and then solidified into a lump. For this reason, the control unit 50 may end the molding process.

The additive manufacturing device 1 of the first embodiment is provided with an oscillator 13 on one side of the base plate 12 and the members from the wire supply unit 30 to the wire nozzle 41, and a vibration sensor 38 on the other side. The additive manufacturing device 1 also has a Z-axis control unit 52 that estimates the positional relationship between the tip of the wire 31 and the machining surface in the Z-axis direction based on the detection result of the vibration sensor 38 of the vibration generated by the oscillator 13. Specifically, the Z-axis control unit 52 estimates that the tip of the wire 31 is in any one of state A in contact with the machining surface, state B in contact with the machining surface via the molten pool 64, and state C in which the tip of the wire 31 is separated from both the machining surface and the molten pool 64. This makes it possible to estimate the positional relationship between the tip of the wire 31 and the machining surface without requiring an imaging device to grasp the positional relationship between the tip of the wire 31 and the machining surface. In addition, if there is an interfering object between the imaging unit and the machining surface, such as a part of the three-dimensional object 61, during the molding process of the inner surface of the cylinder, the state of the tip of the wire 31 cannot be observed by the imaging unit, and control becomes impossible. However, since the additive manufacturing device 1 of the first embodiment does not use an imaging unit, it is possible to grasp the positional relationship between the tip of the wire 31 and the machining surface even in such a situation, and control of the molding process can be continued. In one example, the position of the tip of the wire 31 can be controlled even during the molding process of the inner surface of the cylinder. In addition, in the Z-axis direction, it is possible to suppress the wire 31 from poking the machining surface or bending the wire 31 due to an excessively high supply speed of the wire 31, or the occurrence of a defective liquid droplet state at the tip of the wire 31 or clogging of the wire nozzle 41 due to an insufficient supply speed of the wire 31. Furthermore, the state of the wire 31 in the molten pool 64, which is in a liquid metal state, can also be evaluated.

The additive manufacturing device 1 also includes a displacement meter 37 that measures the displacement of the wire 31 in the XY plane downstream of the feed position of the wire feed roller 35, an actuator 44 that moves the wire nozzle 41 in the XY plane, and an XY axis control unit 51 that calculates the amount of displacement of the tip of the wire 31 in the XY plane based on the measurement result by the displacement meter 37 and instructs the actuator 44 to correct the position of the wire nozzle 41 based on the calculated amount of displacement. As a result, even if the tip of the wire 31 is displaced due to distortion caused in the central axis of the wire 31, the position of the wire nozzle 41 can be corrected so that the tip of the wire 31 falls within the appropriate irradiation range of the laser beam L. In other words, the amount of displacement in the XY plane caused by the distortion of the wire 31 can be prevented from exceeding the appropriate irradiation range of the laser beam L. As described above, according to the first embodiment, in the additive manufacturing device 1 of the DED method using the wire 31, the displacement amount in the XY plane and the position in the Z-axis direction of the tip of the wire 31 that enters the energy irradiation point can be measured and controlled more accurately than in the past.

Embodiment 2.
In additive manufacturing, a three-dimensional object 61 is formed by repeating the process of forming a deposit 63 and stacking it until a predetermined thickness is reached. However, when a new deposit 63 is formed by repeating these processes and is integrated with an already formed lower deposit 63, a molding defect such as voids may occur due to solidification with a gas layer such as external air or shielding gas G contained between the deposits 63. Therefore, in the second embodiment, an additive manufacturing device 1 is described that can promote the detachment of the gas layer generated between the deposits 63 by applying vibration to the molten pool 64, thereby reducing voids.

First, an overview of the gas layer formed in the manufacturing method of the three-dimensional object 61 will be described. Figures 12 and 13 are cross-sectional views showing an example of the gas layer formed in the manufacturing method of the three-dimensional object. Figure 12 is a cross-sectional view perpendicular to the X axis, and Figure 13 is a cross-sectional view perpendicular to the Y axis. As described in the first embodiment, Figures 12 and 13 show a case where a first layer of deposit 63 extending in the X direction is formed on the base plate 12, and then a second layer of deposit 63 is formed on the first layer of deposit 63. As described above, when the newly formed deposit 63 and the already formed lower layer deposit 63 are integrated, molding defects such as voids may occur. As shown in Figures 12 and 13, it has been found by experiments that the gas layer 65 generated between the deposits 63 occurs on the line where the deposits 63 overlap. That is, when a new deposit 63 is formed so as to come into contact with an already formed deposit 63, a gas layer 65 is generated on the line where the outline of the new deposit 63 intersects with the outline of the already formed deposit 63. It has also been found that, as shown in FIG. 13, after the gas layer 65 is generated on the line, it behaves as if it rises in the melting direction. This is thought to be because voids are generated when the metal components of the molten pool 64 solidify before the gas layer 65 is detached. In other words, it is thought that voids are generated because the molten metal components solidify before the gas layer 65 escapes to the outside of the deposit 63.

The additive manufacturing device 1 of the second embodiment is configured to add momentum to the molten pool 64 by imparting oscillation to the molten pool 64 even during the modeling process, and to vibrate the internal gas layer 65 to promote bonding by forming larger air. In the second embodiment, oscillation is also included in the vibration. The gas layer 65 gains buoyancy toward the top more quickly compared to when no oscillation is added. As a result, detachment of the gas layer 65 from the deposit 63 is promoted. The configuration of the additive manufacturing device 1 of the second embodiment is the same as that of the first embodiment. However, in the first embodiment, the control unit 50 imparts oscillation to the vibrator 13 when detecting the positional relationship in the Z-axis direction between the tip of the wire 31 and the processing surface, but in the second embodiment, the control unit 50 imparts oscillation to the vibrator 13 even during the modeling process.

In addition, to promote bonding between the gas layers 65, it is desirable to effectively vibrate the molten pool 64. Since the molten pool 64 is liquid and does not propagate transverse waves, it is desirable to position the vibrator 13 at the shortest position in the Z-axis direction of the molten pool 64, for example.

14 and 15 are diagrams showing an example of the configuration near the moving stage of the additive manufacturing device according to the second embodiment. FIG. 14 is a cross-sectional view perpendicular to the X-axis, and FIG. 15 is a cross-sectional view perpendicular to the Y-axis. As shown in FIG. 14 and FIG. 15, in the additive manufacturing device 1 of the second embodiment, a vibrator 13a that is smaller than the size of the lower surface of the moving stage 11 and can move in the XY plane is provided. In the first embodiment, the vibrator 13 is provided at a position corresponding to the mounting position of the base plate 12 on the lower surface of the moving stage 11, but in the second embodiment, the vibrator 13a that can move in the XY plane is provided on the lower surface of the moving stage 11. In one example, the additive manufacturing device 1 further includes an adjuster (not shown) that allows the vibrator 13a to move in the XY plane on the lower surface of the moving stage 11. The adjuster moves the vibrator 13a in the XY plane according to an instruction from the control unit 50 or the Z-axis control unit 52.

As shown in Figures 14 and 15, the vibrator 13a is moved below the molten pool 64 and vibration is applied during the molding process. That is, the position of the vibrator 13a in the XY plane is controlled so that it corresponds to the position of the processing head 40. This shortens the distance from the molten pool 64 to the vibrator 13a, making it possible to effectively apply longitudinal wave vibration to the molten pool 64. As a result, the gas layer 65 moves in the molten pool 64 and rises in the melting direction, making it possible to promote the detachment of the deposits 63 of the gas layer 65 to the outside before the molten pool 64 solidifies. The other configurations are the same as those in embodiment 1, so their description will be omitted.

In the above explanation, an adjuster that can move in the XY plane is provided below the moving stage 11, and a vibrator 13a is attached to the adjuster, but the method of applying vibration to the molten pool 64 is not limited to this.

In one example, the laser oscillator 21 may be provided with a function for generating a pulsed laser beam L. This causes vibrations in the molten pool 64 each time the pulsed laser beam L is irradiated onto the molten pool 64. As a result, the desorption of the gas layer 65 generated between the deposits 63 is promoted, and voids in the three-dimensional object 61 formed by the accumulation of the deposits 63 can be reduced. Furthermore, irradiating the pulsed laser beam L can reduce the peak temperature of the molten pool 64 and improve the cooling rate of the weld.

In another example, the wire supply unit 30 may include a wire swinging unit that swings the wire 31. Examples of methods for swinging the wire 31 using the wire swinging unit include swinging in a direction perpendicular or parallel to the direction of travel of the wire 31, circular motion in a direction perpendicular to the direction of travel of the wire 31, or a combination of these. This can impart momentum to the gas layer 65 generated between the deposits 63, and promote desorption of the gas layer 65. In this case, the swinging of the wire 31 for imparting momentum to the gas layer 65 and the vibration detected by the vibration sensor 38 can be detected separately, for example, by shifting the timing. The wire swinging unit corresponds to the additional material swinging unit.

Furthermore, in the case of arc welding, in which the wire 31 is melted by arc discharge, the molten pool 64 may be vibrated by the arc current flowing through the molten pool 64 and the magnetic stirring caused by the direction of the magnetic field. In other words, in this case, the additive manufacturing device 1 further includes a magnetic stirring unit that applies a current and a magnetic field to the molten pool 64 to generate magnetic stirring. In one example, a magnetic field can be applied to the molten pool 64 by providing an excitation coil on the arc welding rod.

In the second embodiment, a longitudinal wave vibration is applied to the molten pool 64 during the molding process. This gives momentum to the gas layer 65 that is generated between the deposits 63, and promotes the detachment of the gas layer 65 to the outside of the molten pool 64 before the molten pool 64 solidifies. As a result, there is an effect that the amount of voids in the three-dimensional object 61 formed by the accumulation of the deposits 63 can be reduced compared to the first embodiment.

Embodiment 3.
In the first embodiment, a case has been described in which the vibration applied to the wire 31 is detected by the vibration sensor 38 capable of detecting the intensity of longitudinal waves, the intensity of transverse waves, and the propagation speed in order to obtain the positional relationship between the three-dimensional object 61 and the wire 31. In the third embodiment, a case will be described in which the positional relationship between the three-dimensional object 61 and the wire 31 is obtained by using a current.

Figure 16 is a diagram showing a schematic example of the configuration of an additive manufacturing apparatus according to embodiment 3. Below, differences from embodiment 1 will be described, and explanations of configurations similar to embodiment 1 will be omitted. The additive manufacturing apparatus 1a according to embodiment 3 is obtained by removing the oscillator 13 and vibration sensor 38 from the additive manufacturing apparatus 1 of embodiment 1, and is equipped with a current supply unit 71, a current sensor 14, and a voltage sensor 72.

In one example, the current supply unit 71 supplies current to the wire 31 in response to an instruction from the Z-axis control unit 52. The current supply unit 71 is provided so as to be in contact with the wire 31 between the wire supply unit 30 and the wire nozzle 41. The current sensor 14 is provided on the moving stage 11. The current sensor 14 outputs the presence or absence of detection of current to the Z-axis control unit 52. The voltage sensor 72 measures the voltage, which is the load of the motor 33 provided on the wire reel 32. The voltage sensor 72 outputs the measured voltage to the Z-axis control unit 52. It is sufficient that the current supplied to the wire 31 is one that can be detected by the current sensor 14.

Figure 17 is a block diagram showing an example of an outline of the wire supply control process of the additive manufacturing device according to the third embodiment. Below, differences from Figure 8 of the first embodiment will be described, and the same configuration as that of Figure 8 will not be described. As shown in Figure 17, in the third embodiment, the Z-axis control unit 52 controls the position of the wire 31 in the Z-axis direction based on the measurement result of the current sensor 14. For example, the wire 31 is energized and brought into contact with the molten pool 64 or the three-dimensional object 61. In this case, if the molten pool 64 and the three-dimensional object 61 are metal, and the base plate 12 and the moving stage 11 are also metal, the Z-axis control unit 52 can detect that it is in state A of Figure 5 or state B of Figure 6 by detecting the current with the current sensor 14. Regarding the detection of whether it is state A of Figure 5 or state B of Figure 6, for example, when the wire 31 comes into contact with the three-dimensional object 61, the load of the motor 33 of the wire supply unit 30 increases. For this reason, in the third embodiment, the Z-axis control unit 52 uses the measurement results from the voltage sensor 72 to determine whether the load on the motor 33 is increasing. If the load on the motor 33 is increasing, the Z-axis control unit 52 can estimate that the state is A in FIG. 5, and if the load on the motor 33 is not increasing, the Z-axis control unit 52 can estimate that the state is B in FIG. 6. Furthermore, if the current sensor 14 does not measure a current even though a current is supplied to the wire 31, the Z-axis control unit 52 estimates that the state is C in FIG. 7, in which the wire 31 is not in contact with the molten pool 64 and the three-dimensional object 61. Note that the control of the wire supply unit 30 after estimating the positional relationship between the tip of the wire 31 and the machining surface is the same as in the first embodiment, and therefore will not be described.

In addition, in FIG. 17, instead of providing the voltage sensor 72, as in the first embodiment, the vibrator 13 may be provided on one side between the moving stage 11 and the area from the wire supply unit 30 to the wire nozzle 41, and the vibration sensor 38 may be provided on the other side. In this way, to estimate whether the state is as shown in FIG. 5 or FIG. 6, the result of detecting the vibration from the vibrator 13 by the vibration sensor 38 can be used, as in the first embodiment.

Alternatively, as described in the second embodiment, a movable vibrator 13a may be provided under the moving stage 11 to remove the gas layer 65, and a vibration sensor 38 may be provided between the wire supply unit 30 and the wire nozzle 41.

In the third embodiment, the additive manufacturing device 1 includes a current supply unit 71 that supplies a current to the wire 31, and a current sensor 14 that is provided on the moving stage 11. This allows the positional relationship in the Z-axis direction between the tip of the wire 31 and the machining surface to be estimated based on whether or not the current supplied to the wire 31 is detected by the moving stage 11. The additive manufacturing device 1 also includes a voltage sensor 72 that detects the load on the motor 33 that is provided on the wire reel 32 that supplies the wire 31. This allows the estimation that when the load on the motor 33 increases, the tip of the wire 31 is in contact with the machining surface, and when the load on the motor 33 does not increase, the tip of the wire 31 is in contact with the machining surface via the molten pool 64. This also allows the same effect as in the first embodiment to be obtained.

The control unit 50, the XY-axis control unit 51, and the Z-axis control unit 52 in the first to third embodiments are realized as a processing circuit. The processing circuit may be dedicated hardware or a circuit equipped with a processor. FIG. 18 is a block diagram showing an example of a hardware configuration of the control unit, the XY-axis control unit, and the Z-axis control unit provided in the additive manufacturing apparatus according to the first to third embodiments. The control unit 50, the XY-axis control unit 51, and the Z-axis control unit 52 have a processor 501 and a memory 502. The processor 501 and the memory 502 are connected via a bus line 503. The control unit 50, the XY-axis control unit 51, and the Z-axis control unit 52 are realized by the processor 501 executing a program stored in the memory 502. In addition, a plurality of processors 501 and a plurality of memories 502 may cooperate to realize the above functions. Furthermore, some of the functions of the control unit 50, the XY-axis control unit 51, and the Z-axis control unit 52 may be implemented as an electronic circuit, which is dedicated hardware, and the other parts may be realized using the processor 501 and the memory 502. The XY-axis control unit 51 controls the actuator 44 provided on the wire nozzle 41 with an electrical signal, and the Z-axis control unit 52 controls the wire supply unit 30 with an electrical signal.

The configurations shown in the above embodiments are merely examples, and may be combined with other known technologies, or the embodiments may be combined with each other. In addition, parts of the configurations may be omitted or modified without departing from the spirit of the invention.

1, 1a additive manufacturing device, 11 moving stage, 12 base plate, 13, 13a transducer, 14 current sensor, 21 laser oscillator, 22 gas supply unit, 23 chiller, 24 fiber cable, 30 wire supply unit, 31 wire, 32 wire reel, 33 motor, 34 wire holder, 35 wire feed roller, 36 wire cable, 37 displacement measuring device, 38 vibration sensor, 40 processing head, 41 wire nozzle, 41a supply port, 42 beam nozzle, 43 gas nozzle, 44 actuator, 50 control unit, 51 XY-axis control unit, 52 Z-axis control unit, 61 three-dimensional object, 62 processing area, 63 deposit, 64 molten pool, 65 gas layer, 71 current supply unit, 72 voltage sensor, G shielding gas, L laser beam.

Claims (16)

a stage supporting a base plate having a first surface parallel to an XY plane defined by an X-axis and a Y-axis perpendicular to each other;
a nozzle that supplies an additional material toward a processing surface, which is either the first surface of the base plate or a surface that constitutes a deposit formed on the base plate, and that is movable within an XY plane;
an additional material supply unit that supplies the additional material to the nozzle;
A heat source generating unit that generates a heat source on the processing surface;
an oscillator capable of applying vibration to one of the stage and the additional material;
a vibration sensor capable of detecting vibrations in the other of the stage and the additional material to which vibration is not applied by the vibrator;
a displacement measuring device for measuring the amount of displacement of the additional material in the X-axis direction and the Y-axis direction;
a first control unit that performs control to correct a position of the nozzle on an XY plane based on a measurement result by the displacement measuring device;
a second control unit that acquires a detection result of the vibration generated by the vibrator from the vibration sensor, estimates a positional relationship between the tip of the additional material and the processing surface in a Z-axis direction perpendicular to the XY plane based on the detection result, and controls a supply state of the additional material in the additional material supply unit based on the estimation result;
An additive manufacturing apparatus comprising: The displacement measuring device measures the amount of displacement of the additional material in the X-axis direction and the Y-axis direction for a section of a predetermined length,
The additive manufacturing apparatus according to claim 1, characterized in that the first control unit calculates a unit displacement amount, which is a displacement amount in the X-axis direction and Y-axis direction of the added material per unit length, from the measurement result of the displacement measuring device, and corrects the position of the nozzle in the XY plane based on the displacement amount of the tip of the added material calculated from the unit displacement amount with reference to the discharge position of the added material from the nozzle in the XY plane. The additive manufacturing device according to claim 1 or 2, characterized in that the first control unit controls the position of the nozzle in the XY plane so that the tip of the additive material is positioned within the irradiation range of the heat source where the additive material melts. Further comprising an actuator capable of moving the nozzle in an XY plane;
The additive manufacturing apparatus according to any one of claims 1 to 3, wherein the displacement measuring device is provided downstream of the actuator in the supply direction of the additive material. The vibration sensor can detect the intensity of longitudinal waves, the intensity of transverse waves, and the propagation speed of vibration;
The additive manufacturing device described in any one of claims 1 to 4, characterized in that the second control unit estimates, from the detection results of the vibration sensor, one of the following states: a state in which the tip of the additional material is in contact with the machining surface, a state in which the tip of the additional material is in contact with the machining surface via a molten pool in which the additional material is melted, and a state in which the tip of the additional material is separated from both the machining surface and the molten pool. The additive manufacturing device according to claim 5, characterized in that the second control unit controls the supply state of the additive material in the additive material supply unit based on the estimated state so that the tip of the additive material does not come into contact with the processing surface. The additive manufacturing device according to claim 5, characterized in that the second control unit controls the supply state of the additive material in the additive material supply unit based on the propagation speed of the vibration so that the tip of the additive material does not leave the molten pool. The additive manufacturing device according to claim 6 or 7, characterized in that the second control unit controls the supply speed of the additive material so that the tip of the additive material does not come into contact with the processing surface. The additive manufacturing device according to claim 6 or 7, characterized in that the second control unit controls the supply speed of the additive material so that the tip of the additive material does not leave the molten pool. The oscillator generates vibrations having a waveform that allows detection of a time history;
The vibration sensor detects vibration having the waveform capable of detecting a time history;
The additive manufacturing apparatus according to any one of claims 5 to 9, characterized in that the second control unit estimates the distance between the tip of the additive material and the machining surface from the waveform detected by the vibration sensor. An additive manufacturing device according to any one of claims 1 to 10, characterized in that the oscillator is provided on the surface of the stage opposite the surface on which the base plate is placed, and is movable within the XY plane. An additive manufacturing device according to any one of claims 1 to 10, characterized in that the heat source generating unit is a laser oscillator that generates a pulsed laser beam that melts the additive material. The additive manufacturing device according to any one of claims 1 to 10, further comprising an additive material oscillating unit that oscillates the additive material. The additive manufacturing device according to any one of claims 1 to 10, further comprising a magnetic stirring unit that applies an electric current and a magnetic field to the molten pool in which the additive material is molten to generate magnetic stirring. a stage supporting a base plate having a first surface parallel to an XY plane defined by an X-axis and a Y-axis perpendicular to each other;
a nozzle that supplies an additional material toward a processing surface, which is either the first surface of the base plate or a surface that constitutes a deposit formed on the base plate, and that is movable within an XY plane;
an additional material supply unit that supplies the additional material to the nozzle;
A heat source generating unit that generates a heat source on the processing surface;
A current supply unit that supplies a current to the additional material;
a current measuring device provided on a surface of the stage opposite to a surface on which the base plate is placed;
a voltage meter that measures a load of a motor that supplies the additional material in the additional material supply unit;
a displacement measuring device for measuring the amount of displacement of the additional material in the X-axis direction and the Y-axis direction;
a first control unit that performs control to correct a position of the nozzle on an XY plane based on a measurement result by the displacement measuring device;
a second control unit that estimates a positional relationship between a tip end of the additional material and the processing surface in a Z-axis direction perpendicular to both the X-axis and the Y-axis based on a measurement result by the current meter of the current supplied to the additional material from the current supply unit and a measurement result by the voltage meter, and controls a supply state of the additional material from the additional material supply unit based on the estimation result;
Equipped with
The second control unit estimates whether the tip of the additional material is in a contact state in which it is in contact with the machining surface or the molten pool in which the additional material is melted, or in a disengaged state in which it is not in contact with the molten pool, based on whether or not the current is detected by the current meter, and estimates that, among the contact states, if the load increases compared to a state in which the tip of the additional material is in contact with the molten pool but not in contact with the machining surface, the tip of the additional material is in contact with the machining surface, and if the load does not increase, the tip of the additional material is in contact with the molten pool but not in contact with the machining surface . a supply step of supplying an additional material from a nozzle toward a processing surface which is either a first surface of a base plate arranged on a stage and having a first surface parallel to an XY plane formed by an X-axis and a Y-axis perpendicular to each other, or a surface constituting a deposit formed on the base plate;
a melting and solidifying step of melting and solidifying a tip of the additional material by irradiating a heat source generated on the processing surface by a heat source generating unit;
A method for producing a three-dimensional object, comprising repeating the supplying step and the melting and solidifying step to form a three-dimensional object,
measuring the amount of displacement of the additional material in the X-axis direction and the Y-axis direction;
correcting the position of the nozzle on an XY plane based on the measurement results of the displacement amounts in the X-axis direction and the Y-axis direction;
applying vibration generated by a vibrator to one of the stage and the additional material, and detecting vibration with a vibration sensor in the other of the stage and the additional material to which vibration is not applied by the vibrator;
obtaining a detection result of the vibration generated by the vibrator from the vibration sensor, estimating a positional relationship between the tip of the additional material and the processing surface in a Z-axis direction perpendicular to the XY-axis plane based on the detection result, and controlling a supply state of the additional material based on the estimation result;
A method for producing a three-dimensional object, comprising:

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