Method for controlling lamination molding device, control device for lamination molding device, and program

Abstract

To keep the width of a gap within an appropriate range when molding a molded object in which a plurality of weld beads form the gap.SOLUTION: A method for controlling a lamination molding device that molds a molded object by laminating weld beads with a welding torch, includes the steps of: acquiring, from a lamination plan related to a process of molding the molded object, a planned value of the width of a gap formed by the plurality of weld beads; measuring a plurality of shape profiles corresponding respectively to the plurality of weld beads laminated on the basis of the lamination plan; deriving an actual value of the width of the gap on the basis of the plurality of shape profiles; and correcting lamination conditions of the plurality of weld beads so that a deviation between the planned value of the width of the gap and the actual value of the width of the gap is reduced.SELECTED DRAWING: Figure 9

Description

Technical Field

[0001] The present invention relates to a control method for a laminated manufacturing apparatus, a control device for a laminated manufacturing apparatus, and a program.

Background Art

[0002] Patent Document 1 discloses a first control means for detecting a weld bead width by a groove information detection means using an optical sensor or an arc voltage or the like, storing the result, and controlling welding conditions based on the weld bead width, and detecting and storing an arc voltage during welding, and a second control means for controlling welding conditions based on a differential voltage between the arc voltage and a predetermined reference voltage, and configured to control welding conditions so as to obtain a predetermined bead lamination height. An automatic multi-layer overlay welding apparatus is described.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When forming a shaped article in which a plurality of weld beads form a gap, if a configuration that corrects lamination conditions only from the viewpoint of the lamination height of the weld beads is adopted, the width of the gap cannot be kept within an appropriate range.

[0005] An object of the present invention is to keep the width of a gap within an appropriate range when forming a shaped article in which a plurality of weld beads form a gap.

Means for Solving the Problems

[0006] For this purpose, the present invention provides a control method for a laminating apparatus that forms a shaped object by laminating welding beads with a welding torch, the method including: obtaining a planned value of the width of a gap formed by a plurality of welding beads from a lamination plan for a step of forming the shaped object; measuring a plurality of shape profiles respectively corresponding to the plurality of welding beads laminated based on the lamination plan; deriving an actual value of the width of the gap based on the plurality of shape profiles; and correcting the lamination conditions of the plurality of welding beads so that the deviation amount between the planned value of the width of the gap and the actual value of the width of the gap is reduced. In the deriving step, the distance between specific positions of each of the plurality of shape profiles may be derived as the actual value of the width of the gap. In that case, the specific position may be the tip position protruding in the direction of the gap of each of the plurality of shape profiles. In the deriving step, from the specific position of each of the plurality of shape profiles, the tip position protruding in the direction of the gap of each of the plurality of welding beads may be estimated, and the distance between the tip positions may be derived as the actual value of the width of the gap. In that case, the specific position may be the tip position protruding in the direction of the gap of each of the plurality of shape profiles. In the correcting step, the lamination conditions may be corrected using a correction formula in which at least one of a proportional term, a differential term, and an integral term corresponding to the deviation amount is added to a standard set value of the lamination conditions. In that case, in the correcting step, in accordance with the progress of lamination, the correction formula in which the integral term is not added to the standard set value of the lamination conditions may be switched to the correction formula in which the integral term is added to the standard set value of the lamination conditions. In the correcting step, the planned value of the target position when laminating each of the plurality of welding beads in the next layer may be corrected to the specific position of each of the plurality of shape profiles. In that case, the specific position may be the position where the planned value of the target position extends in the lamination direction and intersects each shape profile. In the correction step, according to the progress of the lamination, the correction method for correcting the lamination conditions may be switched from the first correction method to the second correction method. The first correction method may be a method of correcting the lamination conditions so that the deviation amount between the planned value of the growth amount in the lamination direction of each welding bead of a plurality of welding beads and the actual value of the growth amount derived based on the shape profile becomes small. Further, the second correction method may be a method of correcting the lamination conditions so that the deviation amount between the planned value of the width of the gap and the actual value of the width of the gap becomes small.

[0007] Further, the present invention provides a control device for a laminated manufacturing apparatus that manufactures a shaped object by laminating welding beads with a welding torch, the control device including: an acquisition unit that acquires a planned value of the width of a gap formed by a plurality of welding beads from a lamination plan regarding a process of manufacturing the shaped object; a measurement unit that measures a plurality of shape profiles respectively corresponding to the plurality of welding beads laminated based on the lamination plan; a derivation unit that derives an actual value of the width of the gap based on the plurality of shape profiles; and a correction unit that corrects the lamination conditions of the plurality of welding beads so that the deviation amount between the planned value of the width of the gap and the actual value of the width of the gap becomes small.

[0008] Furthermore, the present invention provides a program for realizing, in a control device for a laminated manufacturing apparatus that manufactures a shaped object by laminating welding beads with a welding torch, a function of acquiring a planned value of the width of a gap formed by a plurality of welding beads from a lamination plan regarding a process of manufacturing the shaped object, a function of measuring a plurality of shape profiles respectively corresponding to the plurality of welding beads laminated based on the lamination plan, a function of deriving an actual value of the width of the gap based on the plurality of shape profiles, and a function of correcting the lamination conditions of the plurality of welding beads so that the deviation amount between the planned value of the width of the gap and the actual value of the width of the gap becomes small.

Advantages of the Invention

[0009] According to the present invention, when manufacturing a shaped object in which a plurality of welding beads form a gap, the width of the gap can be kept within an appropriate range.

Brief Description of the Drawings

[0010]

Figure 1

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[0011] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0012] [Configuration of Metal Laminated Manufacturing System] FIG. 1 is a diagram showing a schematic configuration example of a metal laminated manufacturing system 1 according to the present embodiment. As shown in the figure, the metal laminated manufacturing system 1 includes a welding robot (manipulator) 10, a CAD device 20, a lamination planning device 30, and a control device 50. Further, the lamination planning device 30 writes a control program for controlling the welding robot 10 to a removable recording medium 70 such as a memory card, and the control device 50 can read the control program written to the recording medium 70.

[0013] The welding robot 10 includes an arm 11 having a plurality of joints and performs welding work by operating according to the control program read by the control device 50. Further, the welding robot 10 has a welding torch 13 for forming the laminated object 100 via a wrist portion 12 at the tip of the arm 11. In the case of the metal laminated manufacturing system 1, the welding robot 10 melts the filler metal (wire) 14 made of mild steel and moves the welding torch 13 to manufacture the laminated object 100. Specifically, the welding torch 13 supplies the filler metal 14 and generates an arc while flowing a shielding gas to melt and solidify the filler metal 14, and laminates a plurality of layers of welding beads (hereinafter simply referred to as "beads") on the base material 90 to manufacture the laminated object 100. Here, an arc is used as a heat source for melting the filler metal 14, but a laser or plasma may be used. In addition, the welding robot 10 also includes a feeding device for feeding the filler metal 14 and the like, but the description thereof is omitted. The welding robot 10 is an example of a laminated manufacturing device that forms a shaped object by laminating welding beads with a welding torch.

[0014] Further, the welding robot 10 is provided with a shape measuring device 15 at the tip of the arm 11. The shape measuring device 15 measures the shape of the stacked object 100 during stacking by the welding robot 10. The shape measuring device 15 preferably can acquire the shape profile of the cross section of the stacked object 100. As such a shape measuring device 15, for example, a shape measuring sensor that acquires the shape profile of the cross section based on the reflected light intensity of the irradiated laser light can be used. Alternatively, as the shape measuring device 15, not limited to this, a device that can measure a three-dimensional shape may be used, but hereinafter, a device that acquires the shape profile of the cross section based on the reflected light intensity of the irradiated laser light will be described as being used.

[0015] The CAD device 20 has a function of designing a shaped object using a computer and holding three-dimensional data (hereinafter referred to as "three-dimensional CAD data") obtained by the design.

[0016] The lamination planning device 30 creates a lamination plan for the stacked object 100 based on the three-dimensional CAD data held by the CAD device 20. That is, the lamination planning device 30 determines the trajectory of the welding torch 13 and determines the welding conditions when the welding robot 10 performs welding. Then, the lamination planning device 30 generates a control program for controlling the welding robot 10 to form beads under the welding conditions determined along the determined trajectory, and outputs this control program to the recording medium 70.

[0017] The control device 50 reads and holds the control program from the recording medium 70. Then, by operating this control program, the control device 50 controls the welding robot 10 to form beads under the welding conditions determined by the lamination planning device 30 along the trajectory determined by the lamination planning device 30, that is, according to the lamination plan created by the lamination planning device 30. The control device 50 is an example of a control device for a stacked manufacturing device.

[0018] [Hardware Configuration of Control Device] FIG. 2 is a diagram showing an example of the hardware configuration of the control device 50. As shown in the figure, the control device 50 is realized by, for example, a general-purpose PC (Personal Computer) or the like, and includes a CPU 51 which is an arithmetic means, a main memory 52 which is a storage means, and a magnetic disk device (HDD: Hard Disk Drive) 53. Here, the CPU 51 executes various programs such as an OS (Operating System) and application software, and realizes each function of the control device 50. Further, the main memory 52 is a storage area for storing various programs and data used for their execution, and the HDD 53 is a storage area for storing input data for various programs and output data from various programs. Also, the control device 50 includes a communication I / F 54 for communicating with the outside, a display mechanism 55 including a video memory and a display, an input device 56 such as a keyboard and a mouse, and a driver 57 for reading and writing data to and from a recording medium 70. Note that FIG. 2 only illustrates the hardware configuration when the control device 50 is realized by a computer system, and the control device 50 is not limited to the illustrated configuration.

[0019] Also, the hardware configuration shown in FIG. 2 can also be regarded as the hardware configuration of the stacking planning device 30. However, when describing the stacking planning device 30, the CPU 51, main memory 52, magnetic disk device 53, communication I / F 54, display mechanism 55, input device 56, and driver 57 in FIG. 2 are respectively denoted as CPU 31, main memory 32, magnetic disk device 33, communication I / F 34, display mechanism 35, input device 36, and driver 37.

[0020] [Background and Outline of the Present Embodiment] In the metal laminated forming system 1, the control device 50 controls the welding robot 10 so as to perform laminated welding based on the lamination plan created by the lamination planning device 30. However, even if laminated welding is carried out based on the lamination plan in this way, due to individual differences in welding power sources and devices, and subtle diameter differences due to lots of the filler metal 14, the amount of weld deposited each time is not constant and deviates from the plan. For example, consider a case where a flow path having a cavity is laminated and formed from the left and right to form left and right laminated formed objects 100, and finally the left and right laminated formed objects 100 are closed and completed. In this case, if the gap width between the left and right laminated formed objects 100 exceeds the reference range, various problems occur, such as melting away, no back wave and insufficient penetration, resulting in insufficient strength.

[0021] In the present embodiment, for a laminated formed object 100 such as a flow path having a cavity shape formed by laminating beads symmetrically left and right, in order to stably perform closing welding with a back wave without defects in the final welding, the gap width is controlled so as to fall within the target numerical range.

[0022] In addition, in the present embodiment, as the lamination of the laminated formed object 100, the lamination of a flow path having a circular arch-shaped cross section will be described as an example, but it is not limited to this. The present embodiment can be widely applied to laminations of those having other cross-sectional shapes such as square pipes, and those having a specified interval in the shape in a structure. That is, the present embodiment is applicable to a laminated formed object 100 in which two independent beads form a gap. Or, the number of independent beads does not have to be two, and it can also be said that the present embodiment is applicable to a laminated formed object 100 in which a plurality of independent beads form a gap. Hereinafter, the laminated formed object 100 will be described as being composed of n layers.

[0023] [First Embodiment] (Overview) FIG. 3 is a diagram showing an overview of the control by the control device 50 in the first embodiment. As shown in the figure, first, the control device 50 causes the welding robot 10 to execute the control program acquired from the lamination planning device 30, and forms the first layer of the flow path with the welding torch 13 (S11).

[0024] Next, the control device 50 measures the shape of the cross-section of the first layer of the flow path with the shape measuring device 15, and acquires a shape profile that is the measurement result of the cross-sectional shape (S12). Next, the control device 50 derives the gap width of the specified part and the target position of the next layer from the shape profile acquired in S12 (S13). Next, the control device 50 compares the planned values with the values derived in S13 for the gap width and the target position, and corrects the lamination conditions and the target position based on the comparison result (S14). Next, the control device 50 updates the control program based on the lamination conditions and the target position corrected in S14 (S15).

[0025] Thereafter, the control device 50 repeats S11 to S15 from the second layer to the nth layer (S16). At this time, in S11, the control device 50 causes the welding robot 10 to execute the control program updated in S15. Also, in the figure, for the sake of convenience, S12 to S15 are shown as being executed for the nth layer as well, but since the flow path closes after forming the nth layer, strictly speaking, S12 to S15 do not need to be executed for the nth layer.

[0026] Finally, the control device 50 causes the welding robot 10 to execute the lamination of the closing bead for closing the gap, and laminates the closing bead with the welding torch 13 (S17).

[0027] (Functional Configuration of Lamination Planning Device) FIG. 4 is a diagram showing a functional configuration example of the lamination planning device 30 in the first embodiment. As shown in the figure, the lamination planning device 30 in the first embodiment includes a CAD data acquisition unit 41, a CAD data division unit 42, a lamination plan generation unit 43, and a lamination plan output unit 44.

[0028] The CAD data acquisition unit 41 acquires three-dimensional CAD data representing the three-dimensional shape of the laminated object 100 from the CAD device 20. The CAD data splitting unit 42 generates a plurality of layer shape data representing the shape of each layer by splitting (slicing) the three-dimensional CAD data acquired by the CAD data acquisition unit 41 into a plurality of layers. At this time, the CAD data splitting unit 42 may convert the three-dimensional CAD data into an internal format that is easy to split into a plurality of layers.

[0029] The lamination plan generation unit 43 generates a lamination plan including welding conditions and aiming positions when welding beads that match the height and width of each layer of the plurality of layer shape data generated by the CAD data splitting unit 42. To generate such a lamination plan, in addition to the height and width of the bead, a model approximating the cross-sectional shape of the bead is required. These may be measured values from measurement experiments or estimated by calculation from the cross-sectional area of the deposited metal amount. In the present embodiment, while varying the welding speed and wire feeding speed under several conditions to change the deposition amount, bead-on-plate welding and vertical lamination of several layers are performed, and the results of measuring the height and width per layer under each condition are stored in a database. Then, the welding speed and deposition amount that satisfy the desired height and width to be laminated are selected, the estimated shape of each layer is calculated as needed from the measured results, and the aiming position is determined. Note that the calculation method of the welded cross-section may be changed according to the material of the filler metal 14 and the shape state of the already laminated part. The lamination enclosing the shaped object is planned according to this calculation method.

[0030] The lamination plan output unit 44 outputs the lamination plan generated by the lamination plan generation unit 43 to the recording medium 70.

[0031] (Functional configuration of the control device) FIG. 5 is a diagram showing a functional configuration example of the control device 50 in the first embodiment. As shown in the figure, the control device 50 in the first embodiment includes a lamination plan acquisition unit 61, a control program storage unit 62, a control program execution unit 63, a planned value storage unit 64, a shape profile reception unit 65, a gap width derivation unit 66, a lamination condition correction unit 68, and a control program update unit 69.

[0032] The lamination plan acquisition unit 61 acquires the lamination plan recorded on the recording medium 70. Here, the lamination plan may include a control program for controlling the welding robot 10. Further, the lamination plan may include planned values such as the target position where the welding robot 10 laminates beads, the welding speed, the feeding speed of the filler material 14 (hereinafter simply referred to as the "feeding speed"), the welding current, the welding voltage, the posture of the welding torch 13, and the order in which the beads are laminated. Furthermore, the lamination plan may include at least one of the planned values of the shape information of the laminated object 100, the height or width of the bead, and the cumulative value of the width or height of the bead during lamination. Additionally, the lamination plan may include a planned shape profile. As will be described later, the planned value of the gap width between the beads is specified by this planned shape profile. Then, the lamination plan acquisition unit 61 extracts the control program and the planned values from the lamination plan. In the present embodiment, as an example of an acquisition unit that acquires the planned value of the width of the gap formed by a plurality of welding beads from the lamination plan for the process of forming the object, a lamination plan acquisition unit 61 is provided.

[0033] The control program storage unit 62 stores the control program extracted by the lamination plan acquisition unit 61 from the lamination plan.

[0034] The control program execution unit 63 executes the control program stored in the control program storage unit 62 or the control program updated by the control program update unit 69. Thereby, the control program execution unit 63 controls the welding robot 10 so as to form beads according to the lamination plan generated by the lamination plan generation unit 43 or the lamination plan modified thereafter.

[0035] Specifically, the control program execution unit 63 controls the welding robot 10 to form beads from the first layer to the nth layer. Thereafter, the control program execution unit 63 controls the welding robot 10 to close the opened gap. When beads of each layer are formed, by each functional unit described later keeping the gap width within a predetermined range, the welding robot 10 can stably close the gap. Incidentally, when closing the gap, the control program execution unit 63 may perform control different from that when forming beads from the first layer to the nth layer. In particular, since it is necessary to obtain sufficient penetration for the closing bead to be sufficiently fused with the beads at both ends of the gap, the control program execution unit 63 may perform control to adjust the heat input amount according to the shape of the opening. Here, as control for adjusting the heat input amount, the control program execution unit 63 may perform control to adjust the mixing ratio of the mixed shielding gas in addition to the welding current and the welding voltage.

[0036] The planned value storage unit 64 stores the planned values retrieved by the lamination plan acquisition unit 61 from the lamination plan.

[0037] The shape profile receiving unit 65 receives, from the shape measuring instrument 15, the shape profile of the cross section of the laminated object 100 laminated by the control program execution unit 63 executing the control program. Here, when a plurality of independent beads form a gap in the laminated object 100, the shape profile includes a plurality of shape profile portions corresponding to the plurality of independent beads respectively. In the present embodiment, as an example of a measuring unit that measures a plurality of shape profiles respectively corresponding to a plurality of welding beads laminated based on a lamination plan, a shape profile receiving unit 65 is provided.

[0038] FIG. 6 shows an example of the shape profile received by the shape profile receiving unit 65. As shown in the figure, by updating the shape profile in accordance with the progress of lamination, it becomes possible to grasp the transition of the laminated shape from the shape profile. Also, as shown in the figure, by overlapping and arranging the target positions T1, T2,..., Tn corresponding to the laminated beads B1, B2,..., Bn in the shape profile, it becomes possible to compare the positional relationship between the shape of the bead and the target position.

[0039] Based on the shape profile received by the shape profile receiving unit 65 and the planned value stored in the planned value storage unit 64, the gap width derivation unit 66 derives the gap width and the target position of the next layer.

[0040] When the shape profile receiving unit 65 receives a shape profile as shown in FIG. 6, in this shape profile, there are bead walls curved on the left and right respectively. Therefore, the gap width derivation unit 66 derives the distance between the beads located at the tops of those bead walls as the gap width.

[0041] FIG. 7 shows a method for deriving the gap width in this case. In FIG. 7, the planned shape profile 610 is shown by a dashed line, and the actual shape profile 620 is shown by a solid line. Also, the planned value of the gap width obtained from the planned shape profile 610 is denoted as GapP, and the actual values of the gap width obtained from the actual shape profile 620 are denoted as GapG and GapR. In the shape profile obtained using the laser beam (hereinafter referred to as the "sensor profile 630"), there may be a case where information can be obtained only up to a part of the actual shape, as shown by the thick solid line. In this case, there may be a difference between GapG, which is the apparent closest distance between beads, and GapR, which is the actual closest distance between beads. When the closing of the flow path roof or the like is planned, it is preferable to grasp GapR. Therefore, the gap width derivation unit 66 may estimate GapR from GapG or the like. Specifically, the gap width derivation unit 66 may convert GapG to GapR by obtaining an offset value corresponding to the relationship between GapG and GapR from a simple test body or the like. Alternatively, the gap width derivation unit 66 may estimate GapR by inputting GapG into a model that has learned the relationship between GapG and GapR obtained from a simple test body. Incidentally, when deriving GapG, the gap width derivation unit 66 may use a specific position on the sensor profile 630, but it is preferable to use the tip position that protrudes most in the gap width direction on the sensor profile 630 as this specific position. In FIG. 7, this tip position may be the boundary point between the range 621 where the sensor profile 630 shown by the thick solid line can be obtained and the range 622 where the sensor profile 630 shown by the thin solid line could not be obtained. Also, the new target position TR R ,TR L may be regarded as the tip position, or the tip position may be extracted in consideration of the acquisition range of the sensor profile 630 or the like.

[0042] In the present embodiment, as an example of a derivation unit that derives the actual value of the gap width based on a plurality of shape profiles, this function of the gap width derivation unit 66 is provided. In addition, in the present embodiment, as an example of a derivation unit that derives the distance between specific positions of each of a plurality of shape profiles as an actual value of the gap width, this function of the gap width derivation unit 66 is provided. Furthermore, in the present embodiment, as an example of a derivation unit that estimates the tip positions protruding in the gap direction of each of the plurality of welding beads from specific positions of each of the plurality of shape profiles and derives the distance between the tip positions as an actual value of the gap width, this function of the gap width derivation unit 66 is provided.

[0043] Also, when the target position of the next layer is set at a position away from the surface of the bead, there is a risk of poor arc generation or poor lamination shape. Therefore, the gap width derivation unit 66 also derives the target position of the next layer.

[0044] FIG. 7 also shows a method for deriving the target position in this case. The gap width derivation unit 66 extends the planned target positions TP R , TP L in the stacking direction of the overhang angle θ OH in the V R , V L direction and intersects with the sensor profile 630 to derive a new target position TR R , TR L . Note that when the sensor profile 630 does not intersect with the V R , V L direction, the target position of the next layer may be derived from a shape profile obtained by complementing with a predetermined bead shape model.

[0045] The lamination condition correction unit 68 compares the actual value of the gap width and the new target position derived by the gap width derivation unit 66 with the planned gap width and target position stored in the planned value storage unit 64.

[0046] Specifically, the lamination condition correction unit 68 compares the planned value of the gap width stored in the planned value storage unit 64 with the actual value of the gap width derived by the gap width derivation unit 66, and calculates the deviation amount ε. Here, the actual value of the gap width may be a value directly obtained from the sensor profile (for example, GapG), or may be a value obtained by estimation based on the sensor profile (for example, GapR). The lamination condition correction unit 68 corrects the lamination conditions of the bead to be laminated in the next layer using a correction amount corresponding to the calculated deviation amount ε. For example, assuming that the target next layer is the k-th layer and the deviation amount at that time is ε k , and the change amount of the deviation amount from the previous time is Δε k , then the lamination condition correction unit 68 may correct the welding speed WeldV k by the correction amount shown in the following formula (1).

[0047]

Equation

[0048] Formula (1) is the formula for PID control, where Kp is the proportional gain, Kd is the derivative gain, Ki is the integral gain, and θ OH is the overhang angle, and φ represents the inclination angle of the welding torch 13 with respect to the horizontal plane. In formula (1), the standard set value of the welding speed is corrected based on the overhang angle θ OH and the inclination angle φ of the welding torch 13, and the corrected welding speed is further corrected by a correction term depending on the deviation amount ε of the gap width. Note that it is not necessary to provide all the terms from the second term to the fourth term on the right side of formula (1). It is sufficient if at least one of the second term to the fourth term is provided. Also, terms may be added or omitted according to the progress of lamination. For example, the fourth term on the right side of formula (1) may be added starting from the m-th layer which is an intermediate layer. In this case, the value of m may be adjusted according to the convergence of the deviation amount ε. Further, the gains Kp, Kd, and Ki may be adjusted according to the situation of the bead to be laminated, such as the overhang angle θ OH . In formula (1), the gain Kp is corrected based on the overhang angle θ OH . As shown in FIG. 7, even if the welding amount of the bead is the same, the overhang angle θOH This is because the contributions in the gap width direction are different depending on [the situation]. Thus, the lamination condition correction unit 68 corrects the welding speed according to Equation (1), but it may also correct the feeding speed according to an equation similar to Equation (1).

[0049] In the present embodiment, as an example of a correction unit that corrects the lamination conditions of a plurality of welding beads so that the deviation amount between the planned value of the gap width and the actual value of the gap width becomes small, this function of the lamination condition correction unit 68 is provided. Also, in the present embodiment, Equation (1) is used as an example of a correction formula in which at least one of a proportional term, a differential term, and an integral term corresponding to the deviation amount is added to the standard set value of the lamination conditions. And in the present embodiment, as an example of a correction unit that corrects the lamination conditions using the correction formula, this function of the lamination condition correction unit 68 is provided. Furthermore, in the present embodiment, as an example of a correction unit that switches a correction formula in which no integral term is added to the standard set value of the lamination conditions to a correction formula in which an integral term is added to the standard set value of the lamination conditions according to the progress of lamination, this function of the lamination condition correction unit 68 is provided.

[0050] Also, the lamination condition correction unit 68 compares, on the shape profile, the planned target position stored in the planned value storage unit 64 with the new target position derived by the gap width derivation unit 66. At this time, the lamination condition correction unit 68 calculates the planned target position TP R , TP L and the new target position TR R , TR L and the distance A R , A L together (see FIG. 7). Here, the new target position TR R , TR L may be a specific position on the sensor profile 630. However, as described above, this specific position is the planned target position TP R , TP L in the lamination direction of the overhang angle θ OH which is V R , V LIt is preferably set at a position extending in the direction and intersecting the sensor profile 630 (see FIG. 7). Then, the lamination condition correction unit 68 corrects the target position instructed to the welding robot 10 by a correction vector, which is a correction amount using the distance A R , A L between the target positions in the following formula (2), to a new target position TR R , TR L .

[0051]

Equation

[0052] Here, V j is a unit vector in the direction from the target position of the current layer to the target position of the next layer. However, the angle formed by V j with the horizontal plane shall be an acute angle. If such an update of the target position is not performed, the arc may not be correctly generated at the tip of the bead that has already been laminated, the arc may become unstable, or an error may occur in the welding power source, resulting in the device stopping.

[0053] In this embodiment, as an example of a correction unit that corrects the planned value of the target position when laminating each welding bead of a plurality of welding beads in the next layer to a specific position of each shape profile of the plurality of shape profiles, this function of the lamination condition correction unit 68 is provided.

[0054] The control program update unit 69 updates the control program according to the correction amount obtained by the lamination condition correction unit 68. The beads to be updated are the beads at both ends that form a gap. In particular, since the welding amount is independently adjusted, the shapes of the left and right beads are likely to be unbalanced (asymmetric). Therefore, the correction amount of the welding speed or the feeding speed derived from formula (1) is applied to the lamination of the beads at both ends of the gap. On the other hand, individual adjustments may be made for the correction amount of the target position on the left and right sides of the gap. For example, when the filler 14 bends from the tip of the welding torch 13 in a predetermined direction, the way of giving the offset value according to the bending direction may be different for the bead laminated on the left side of the gap and the bead laminated on the right side of the gap. Further, the control program update unit 69 may also correct the posture of the welding robot 10 and the like in accordance with the correction of the target position and the welding amount.

[0055] (Operation of the Lamination Planning Device) FIG. 8 is a flowchart showing an operation example of the lamination planning device 30 in the first embodiment. As shown in the figure, in the lamination planning device 30, first, the CAD data acquisition unit 41 acquires three-dimensional CAD data from the CAD device 20 (step 301). Next, the CAD data division unit 42 divides the three-dimensional CAD data acquired in step 301 into a plurality of layers and generates layer shape data (step 302). Next, the lamination plan generation unit 43 generates a lamination plan from the layer shape data generated in step 302 (step 303). Next, the lamination plan output unit 44 outputs the lamination plan generated in step 303 to the recording medium 70 (step 304).

[0056] (Operation of the Control Device) In the control device 50, first, the lamination plan acquisition unit 61 acquires the lamination plan from the recording medium 70, stores the control program included in the lamination plan in the control program storage unit 62, and stores the planned values included in the lamination plan in the planned value storage unit 64. Then, the control program execution unit 63 reads out the control program stored in the control program storage unit 62 and executes it, thereby starting the execution of the manufacturing control process in the first embodiment.

[0057] FIG. 9 is a flowchart showing the content of such a manufacturing control process. As shown in the figure, first, the control program execution unit 63 sets the layer index i to 1 (step 501). Next, the control program execution unit 63 performs the following processing for each index i while incrementing the layer index i by 1 up to the number of layers n.

[0058] That is, the control program execution unit 63 controls the welding robot 10 to form the i-th layer of the laminated object 100 (step 502). Next, the control program execution unit 63 determines whether the layer index i has reached the number of layers n (step 503).

[0059] As a result, if it is determined that the layer index i has not reached the number of layers n, the shape profile reception unit 65 receives the shape profile from the shape measuring instrument 15 (step 504). Next, the gap width derivation unit 66 derives the actual value of the gap width and the new target position of the next layer based on the planned value stored in the planned value storage unit 64 and the shape profile received in step 504 (step 505). Next, the lamination condition correction unit 68 compares the planned value of the gap width stored in the planned value storage unit 64 with the actual value of the gap width derived in step 505, and corrects the lamination condition so that the deviation amount becomes small (step 506). Specifically, the lamination condition correction unit 68 obtains a correction amount corresponding to the deviation amount, and corrects the lamination condition by this correction amount. Next, the lamination condition correction unit 68 compares the planned value of the target position of the next layer stored in the planned value storage unit 64 with the new target position of the next layer derived in step 505, and corrects the target position of the next layer (step 507). Specifically, the lamination condition correction unit 68 obtains a correction amount regarding the target position, and corrects the target position by this correction amount. Next, the control program update unit 69 updates the control program being executed by the control program execution unit 63 based on the correction amounts obtained in step 506 and step 507 (step 508). Thereafter, the control program execution unit 63 adds 1 to the layer index i (step 509), and returns the process to step 502.

[0060] On the other hand, if it is determined that the layer index i has reached the number of layers n, the control program execution unit 63 controls the welding robot 10 to close the gap (step 510), and ends the process.

[0061] (Effect) In the first embodiment, when forming a shaped object in which a plurality of weld beads form a gap, the lamination conditions of the plurality of weld beads are corrected so that the deviation amount between the planned value and the actual value of the width of the gap is reduced. As a result, it becomes possible to keep the width of the gap within an appropriate range.

[0062] [Second Embodiment] (Overview) The control by the control device 50 in the first embodiment may be combined with other controls. For example, in the second embodiment, the control based on the gap width in the first embodiment is combined with the control based on the growth amount of the bead (hereinafter simply referred to as "growth amount"). For example, in the circular arch-shaped laminated object 100, since the layers that bear most of the height of the laminated object 100 are the front layers (the 1st, 2nd, 3rd,..., (m - 1)th layers), it is preferable to control the growth amount from the viewpoint of managing the lamination height in the front layers. In the latter layers (the mth, (m + 1)th,..., nth layers), even if the number of layers increases, the increase amount of the lamination height is small, and the bead interval on the left and right changes more greatly for each layer than the lamination height. Therefore, by regarding the bead interval on the left and right as the gap width and switching to the control based on the gap width, the interval between the bead walls can be adjusted to an appropriate amount, and it is easy to ensure the quality of the closed bead. Conversely, if the interval between the bead walls is not an appropriate amount, there is a risk of problems such as poor formation of the back wave bead and holes due to melting of the welding metal.

[0063] FIG. 10 is a diagram showing an overview of other controls by the control device 50 in the second embodiment. As shown in the figure, first, the control device 50 causes the welding robot 10 to execute the control program acquired from the lamination planning device 30, and forms the first layer of the flow path with the welding torch 13 (S21).

[0064] Next, the control device 50 measures the shape of the cross section of the first layer of the flow path with the shape measuring instrument 15, and acquires the shape profile which is the measurement result of the shape of the cross section (S22). Next, the control device 50 derives the growth amount and the target position of the next layer from the shape profile acquired in S22 (S23). Next, the control device 50 compares the planned values with the values derived in S23 for the growth amount and the target position, and corrects the lamination conditions and the target position based on the comparison results (S24). Next, the control device 50 updates the control program based on the lamination conditions and the target position corrected in S24 (S25).

[0065] Thereafter, the control device 50 repeats S21 to S25 from the second layer to the m-th layer (S26). At this time, in S21, the control device 50 causes the welding robot 10 to execute the control program updated in S25. Also, for the sake of convenience, in the figure, S22 to S25 are shown as being executed for the m-th layer as well. However, since control is performed based on the gap width after forming the m-th layer of the flow path, strictly speaking, instead of S22 to S25, S12 to S15 in FIG. 3 may be executed for the m-th layer.

[0066] (Functional configuration of the lamination planning device) The functional configuration example of the lamination planning device 30 in the second embodiment is the same as the functional configuration example of the lamination planning device 30 in the first embodiment, and thus the description thereof is omitted.

[0067] (Functional configuration of the control device) FIG. 11 is a diagram showing a functional configuration example of the control device 50 in the second embodiment. As shown in the figure, the control device 50 in the second embodiment includes a lamination plan acquisition unit 61, a control program storage unit 62, a control program execution unit 63, a planned value storage unit 64, a shape profile reception unit 65, a gap width derivation unit 66, a growth amount derivation unit 67, a lamination condition correction unit 68, and a control program update unit 69.

[0068] The lamination plan acquisition unit 61, the control program storage unit 62, the control program execution unit 63, the planned value storage unit 64, the shape profile reception unit 65, and the gap width derivation unit 66 are the same as those in the first embodiment, and thus the description thereof is omitted.

[0069] The growth amount derivation unit 67 derives the growth amount and the target position of the next layer based on the shape profile received by the shape profile reception unit 65 and the planned value stored in the planned value storage unit 64.

[0070] For the first layer to the (m - 1)-th layer, the lamination condition correction unit 68 performs the following operations. That is, the lamination condition correction unit 68 compares the actual value of the growth amount and the new target position derived by the growth amount derivation unit 67 with the planned growth amount and the target position in the plan stored in the planned value storage unit 64. Then, the lamination condition correction unit 68 sets the deviation amount between the planned value of the growth amount stored in the planned value storage unit 64 and the actual value of the growth amount derived by the growth amount derivation unit 67 as ε, and updates the lamination conditions by an equation similar to Equation (1). Also, the lamination condition correction unit 68 updates the target position of the next layer by the same equation as Equation (2). In the present embodiment, as an example of a correction unit that executes a first correction method, which is a method of correcting the lamination conditions so that the deviation amount between the planned value of the growth amount in the lamination direction of each welding bead of a plurality of welding beads and the actual value of the growth amount derived based on the shape profile is reduced, this function of the lamination condition correction unit 68 is provided.

[0071] Also, for the m-th layer to the n-th layer, the lamination condition correction unit 68 performs the same operations as in the first embodiment. In the present embodiment, as an example of a correction unit that executes a second correction method of correcting the lamination conditions so that the deviation amount between the planned value of the gap width and the actual value of the gap width is reduced, this function of the lamination condition correction unit 68 is provided.

[0072] Furthermore, in the present embodiment, as an example of a correction unit that switches the correction method for correcting the lamination conditions from the first correction method to the second correction method as the lamination progresses, the lamination condition correction unit 68 is provided.

[0073] Since the control program update unit 69 is the same as in the first embodiment, the description thereof is omitted.

[0074] (Operation of the Lamination Planning Device) The operation example of the lamination planning device 30 in the second embodiment is the same as that of the lamination planning device 30 in the first embodiment, so the description thereof is omitted.

[0075] (Operation of the control device) In the control device 50, first, the lamination plan acquisition unit 61 acquires a lamination plan from the recording medium 70, stores the control program included in the lamination plan in the control program storage unit 62, and stores the planned values included in the lamination plan in the planned value storage unit 64, respectively. Then, the control program execution unit 63 reads out the control program stored in the control program storage unit 62 and executes the same, thereby starting the execution of the shaping control process in the second embodiment.

[0076] FIG. 12 is a flowchart showing the content of such a shaping control process. As shown in the figure, first, the control program execution unit 63 sets the index i of the layer to 1 (step 551). Next, the control program execution unit 63 performs the following process for each index i while incrementing the index i of the layer by 1 up to the number of layers n.

[0077] That is, the control program execution unit 63 controls the welding robot 10 so as to shape the i-th layer of the laminated object 100 (step 552). Next, the control program execution unit 63 determines whether or not the index i of the layer has reached the number of layers n (step 553).

[0078] As a result, if it is determined that the index i of the layer has not reached the number of layers n, the shape profile receiving unit 65 receives a shape profile from the shape measuring instrument 15 (step 554). Next, the shape profile receiving unit 65 determines whether or not the index i of the layer has reached the number of layers m (step 555).

[0079] As a result, if it is determined that the layer index i has not reached the number of layers m, the growth amount derivation unit 67 derives the actual value of the growth amount and the new target position of the next layer based on the planned value stored in the planned value storage unit 64 and the shape profile received in step 554 (step 556). Next, the lamination condition correction unit 68 compares the planned value of the growth amount stored in the planned value storage unit 64 with the actual value of the growth amount derived in step 556, and corrects the lamination condition so that the deviation amount becomes smaller (step 557). Specifically, the lamination condition correction unit 68 obtains a correction amount corresponding to the deviation amount, and corrects the lamination condition by this correction amount.

[0080] On the other hand, if it is determined that the layer index i has reached the number of layers m, the gap width derivation unit 66 derives the actual value of the gap width and the new target position of the next layer based on the planned value stored in the planned value storage unit 64 and the shape profile received in step 554 (step 558). Next, the lamination condition correction unit 68 compares the planned value of the gap width stored in the planned value storage unit 64 with the actual value of the gap width derived in step 558, and corrects the lamination condition so that the deviation amount becomes smaller (step 559). Specifically, the lamination condition correction unit 68 obtains a correction amount corresponding to the deviation amount, and corrects the lamination condition by this correction amount.

[0081] Next, the lamination condition correction unit 68 compares the planned value of the target position of the next layer stored in the planned value storage unit 64 with the new target position of the next layer derived in step 556 or step 558, and corrects the target position of the next layer (step 560). Specifically, the lamination condition correction unit 68 obtains a correction amount regarding the target position, and corrects the target position by this correction amount. Next, the control program update unit 69 updates the control program being executed by the control program execution unit 63 based on the correction amounts obtained in step 557 and step 560, or step 559 and step 560 (step 561). Thereafter, the control program execution unit 63 adds 1 to the layer index i (step 562), and returns the process to step 552.

[0082] On the other hand, if it is determined that the index i of the layer has reached the number of layers n, the control program execution unit 63 controls the welding robot 10 to close the gap (step 563) and ends the process.

[0083] (Effect) In the second embodiment, when forming a shaped article in which a plurality of welding beads form a gap, the deviation amount between the planned value and the actual value of the growth amount is small in the first half, and the deviation amount between the planned value and the actual value of the width of the gap is small in the second half. Thus, the lamination conditions of the plurality of welding beads are corrected. As a result, it is possible to keep the width of the gap within an appropriate range while satisfying the height and width of the shaped article.

Description of Reference Numerals

[0084] 1... Metal additive manufacturing system, 10... Welding robot, 13... Welding torch, 15... Shape measuring instrument, 20... CAD device, 30... Lamination planning device, 41... CAD data acquisition unit, 42... CAD data division unit, 43... Lamination plan generation unit, 44... Lamination plan output unit, 50... Control device, 61... Lamination plan acquisition unit, 62... Control program storage unit, 63... Control program execution unit, 64... Planned value storage unit, 65... Shape profile reception unit, 66... Gap width derivation unit, 67... Growth amount derivation unit, 68... Lamination condition correction unit, 69... Control program update unit, 70... Recording medium

Claims

1. A control method for a laminated manufacturing apparatus that manufactures a shaped object by laminating welding beads with a welding torch, comprising: obtaining a planned value of the width of a gap formed by a plurality of welding beads from a lamination plan related to the step of manufacturing the shaped object; measuring a plurality of shape profiles respectively corresponding to the plurality of welding beads laminated based on the lamination plan; deriving an actual value of the width of the gap based on the plurality of shape profiles; correcting the lamination conditions of the plurality of welding beads so that the deviation amount between the planned value of the width of the gap and the actual value of the width of the gap is reduced; A control method for a laminated manufacturing apparatus, comprising the steps described above.

2. The control method for a laminated manufacturing apparatus according to claim 1, wherein in the step of deriving, the distance between specific positions of each of the plurality of shape profiles is derived as the actual value of the width of the gap.

3. The control method for a laminated manufacturing apparatus according to claim 2, wherein the specific position is the tip position protruding in the direction of the gap of each of the plurality of shape profiles.

4. The control method for a laminated manufacturing apparatus according to claim 1, wherein in the step of deriving, the tip position protruding in the direction of the gap of each welding bead of the plurality of welding beads is estimated from the specific position of each of the plurality of shape profiles, and the distance between the tip positions is derived as the actual value of the width of the gap.

5. The control method for a laminated manufacturing apparatus according to claim 4, wherein the specific position is the tip position protruding in the direction of the gap of each of the plurality of shape profiles.

6. The control method for a laminated manufacturing apparatus according to claim 1, wherein in the step of correcting, the lamination conditions are corrected using a correction formula in which at least one of a proportional term, a differential term, and an integral term corresponding to the deviation amount is added to a standard set value of the lamination conditions.

7. The control method for a laminated manufacturing apparatus according to claim 6, wherein in the step of correcting, as the lamination progresses, the correction formula in which the integral term is not added to the standard set value of the lamination conditions is switched to the correction formula in which the integral term is added to the standard set value of the lamination conditions.

8. In the step of correction, a planned value of a target position when laminating each of the plurality of weld beads in the next layer is corrected to a specific position of each of the plurality of shape profiles. The control method of the additive manufacturing apparatus according to claim 1.

9. The specific position is a position where a planned value of the target position is extended in the lamination direction and intersects with each of the shape profiles. The control method of the additive manufacturing apparatus according to claim 8.

10. In the step of correction, in accordance with the progress of lamination, a correction method for correcting the lamination conditions is switched from a first correction method to a second correction method. The first correction method is a method of correcting the lamination conditions such that a deviation amount between a planned value of a growth amount in the lamination direction of each of the plurality of weld beads and an actual value of the growth amount derived based on the shape profile becomes small. The second correction method is a method of correcting the lamination conditions such that a deviation amount between a planned value of the width of the gap and an actual value of the width of the gap becomes small. The control method of the additive manufacturing apparatus according to claim 1.

11. A control device for an additive manufacturing apparatus that forms a weld bead by a welding torch to form a shaped object, an acquisition unit that acquires a planned value of the width of a gap formed by a plurality of weld beads from a lamination plan regarding the step of forming the shaped object; a measurement unit that measures a plurality of shape profiles respectively corresponding to the plurality of weld beads laminated based on the lamination plan; a derivation unit that derives an actual value of the width of the gap based on the plurality of shape profiles; and a correction unit that corrects the lamination conditions of the plurality of weld beads such that a deviation amount between the planned value of the width of the gap and the actual value of the width of the gap becomes small. A control device for an additive manufacturing apparatus, comprising the above components.

12. In a control device for an additive manufacturing apparatus that forms a weld bead by a welding torch to form a shaped object, a function of acquiring a planned value of the width of a gap formed by a plurality of weld beads from a lamination plan regarding the step of forming the shaped object; a function of measuring a plurality of shape profiles respectively corresponding to the plurality of weld beads laminated based on the lamination plan; a function of deriving an actual value of the width of the gap based on the plurality of shape profiles; and a function of correcting the lamination conditions of the plurality of weld beads such that a deviation amount between the planned value of the width of the gap and the actual value of the width of the gap becomes small. A program for realizing the above functions.

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