Additive manufacturing system

Abstract

To provide an additive manufacturing system that can generate a lamination route capable of preventing a laminate material from sagging without a support material.SOLUTION: An additive manufacturing system comprises: a welding robot which performs additive manufacturing; a lamination route generating device which generates a lamination route of the welding robot; and a control device which controls the welding robot on the basis of the lamination route. The lamination route generating device generates the lamination route by using a potential field for calculation of a branch lamination plane.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an additive manufacturing system. [Background technology]

[0002] Patent Document 1 below discloses an additive manufacturing method that can manufacture highly accurate additively manufactured objects by accurately determining the target position for bead formation. This additive manufacturing method is a manufacturing technology categorized as a wire and arc additive manufacturing (WAAM) method, and uses an arc welding robot to laminate metal materials (laminate materials) to obtain a three-dimensional object (additively manufactured object) of a desired shape.

[0003] In other words, this additive manufacturing method, when manufacturing an additively manufactured object based on a layered path plan, measures the shape profile of an existing weld bead using a non-contact shape sensor that is integrally provided on the robot tip axis with the welding torch, extracts first geometric information of the bead shape from the shape profile and the target position of the welding torch, extracts second geometric information corresponding to the first geometric information from the layered path plan to calculate the amount of deviation between the first geometric information and the second geometric information, updates the layered path plan by changing at least one of the bead height and bead width of the weld bead defined in the layered path plan in accordance with the amount of deviation, and changes the welding conditions in accordance with the results of updating the layered path plan, thereby manufacturing a highly accurate additively manufactured object. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6797324 Summary of the Invention [Problem to be solved by the invention]

[0005] In the above-mentioned WAAM, for example, when complex lamination is performed, support materials are used to prevent the molten laminate material from dripping. However, when the laminate material is aluminum, for example, support materials cannot be used, so the laminate material is laminated non-parallel. A method for achieving this non-parallel lamination is known, which involves obtaining the geodesic curves of the laminate.

[0006] However, the method for obtaining the geodesic line is difficult to apply when the edge of the laminate is drawn as a surface or a curve, or when the laminate has a branched shape with multiple top and bottom surfaces. That is, the above-mentioned background art has a problem in that it is difficult to generate a stacking path that can prevent sagging of the laminate without using support materials.

[0007] The present invention has been made in consideration of the above-mentioned circumstances, and aims to provide an additive manufacturing system that is capable of generating a stacking path that can prevent sagging of the stacked material without using support material. [Means for solving the problem]

[0008] In order to achieve the above object, the present invention provides, as a first solution relating to an additive manufacturing system, an additive manufacturing system comprising a welding robot that performs additive manufacturing, a stacking path generation device that generates a stacking path for the welding robot, and a control device that controls the welding robot based on the stacking path, wherein the stacking path generation device generates the stacking path by using a potential field to calculate branching stacking surfaces.

[0009] In the present invention, as a second solution related to an additive manufacturing system, in the above-mentioned first solution, the stacking path generation device sets virtual potential values ​​on the bottom and top surfaces of the stack, calculates a potential field on the stack by solving a Poisson's equation for the potential values ​​using the finite element method, obtains a point cloud of the same potential value by extracting surface information of the stack from the potential field, obtains a non-intersecting unicursal line that minimizes the length of the stacking path by solving a traveling salesman problem to determine the order in which to traverse the point cloud, divides the path at each of the potential values ​​into a predetermined number of points, obtains a direction vector with the surface one below at each point, and obtains the stacking path by connecting each point with the direction vector.

[0010] The present invention employs, as a third solution related to an additive manufacturing system, the solution according to the second solution, in which the potential value is a temperature potential value related to temperature. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide an additive manufacturing system that is capable of generating a stacking path that can prevent sagging of the stacked material without using support material. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a block diagram showing the overall configuration of an additive manufacturing system according to an embodiment of the present invention. [Figure 2] 1 is a block diagram showing the functional configuration of an additive manufacturing system according to an embodiment of the present invention. [Figure 3] 3 is a flowchart illustrating the operation of the additive manufacturing system according to one embodiment of the present invention. [Figure 4] FIG. 10 is a schematic diagram illustrating a process for generating a stacking path in one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The additive manufacturing system A according to this embodiment performs additive manufacturing using the Wire and Arc Additive Manufacturing (WAAM) method. That is, the additive manufacturing system A manufactures a three-dimensional object (additive manufactured object) of a desired shape by stacking predetermined metal materials (laminate materials) as weld metals.

[0014] As shown in Fig. 1, the additive manufacturing system A includes a welding robot 1, a control information generating device 2, and a control device 3. Of the welding robot 1, the control information generating device 2, and the control device 3, the welding robot 1 includes a welding torch 1a and a measuring device 1b. In Fig. 1, a laminate W is a three-dimensional object in the process of being manufactured by the additive manufacturing system A by stacking multiple layers of laminated material.

[0015] Welding robot 1 is an articulated robot that sequentially moves welding torch 1a. Welding robot 1 sequentially moves welding torch 1a three-dimensionally based on control commands input from control device 3. Welding torch 1a is provided at the tip of welding robot 1, and sequentially melts wire-like laminated material (welding wire) that is fed in sequentially, arc-welding the laminated material.

[0016] The above-mentioned laminate W is formed by laminating (arc welding) laminate materials into multiple layers using a welding torch 1a. The measuring device 1b is provided at the tip of the welding robot 1, similar to the welding torch 1a, and measures the three-dimensional shape of the laminate W.

[0017] The control information generating device 2 generates control information for controlling the welding robot 1 based on a pre-installed control information generating program. Although details will be described later, the control information generating device 2 generates the control information by processing three-dimensional shape data of the laminate W as the final completed product based on the control information generating program.

[0018] The control information includes at least the movement trajectory of the tip of welding torch 1a in welding robot 1, i.e., the lamination path. In other words, control information generating device 2 according to this embodiment corresponds to a lamination path generating device that generates the lamination path of welding robot 1.

[0019] The control device 3 controls the welding robot 1 based on the control information input from the control information generating device 2. As will be described in detail later, the control device 3 generates control commands based on a pre-installed control program and outputs them to the welding robot 1, thereby controlling the movement of the welding torch 1a by the welding robot 1.

[0020] 2, the functional configurations of the control information generating device 2 (lamination path generating device) and the control device 3 will be described. The control information generating device 2 according to this embodiment includes a 3D model acquiring unit 2a, a 3D model slicing unit 2b, a lamination control information generating unit 2c, and a measurement control information generating unit 2d. On the other hand, the control device 3 includes a control information storage unit 3a and a robot control unit 3b.

[0021] The 3D model acquisition unit 2a acquires three-dimensional shape data (3D model data) of the laminate W as a final completed product from the outside and outputs it to the 3D model slicing unit 2b. The 3D model slicing unit 2b slices the three-dimensional shape of the laminate W indicated by the 3D model data using a non-planar slicing method to determine a stacking path, and outputs the slicing result to the stacking control information generation unit 2c.

[0022] Unlike the general planar slicing method, the non-planar slicing method does not necessarily use a flat slice surface. For example, by slicing the object perpendicular to the surface, the non-planar slicing method can eliminate the need for support materials even in the case of an overhanging shape that would require support materials if sliced ​​horizontally.

[0023] Based on the slicing result, the lamination control information generator 2c generates lamination control information for the welding robot 1 when forming the laminated body W. That is, the lamination control information generator 2c generates, as lamination control information, a lamination path for moving the tip of the welding torch 1a in accordance with the slicing result by the 3D model slicing unit 2b and a posture indicating the posture of the welding torch 1a at each position on the lamination path, and outputs the lamination control information to the measurement control information generator 2d and the control device 3.

[0024] Here, the above-mentioned 3D model slicing unit 2b generates the stacking path by using a potential field to calculate the branch stacking surface. That is, the 3D model slicing unit 2b sets virtual temperature potential values ​​on the bottom and top surfaces of the stack W, calculates the temperature potential field on the stack W by solving the Poisson equation using the finite element method, and obtains a point group with the same temperature potential value by extracting surface information of the stack W from the temperature potential field.

[0025] In addition, the 3D model slicing unit 2b solves the traveling salesman problem to determine the order in which to traverse the above point cloud, thereby obtaining a single, non-intersecting line that minimizes the length of the stacking path, dividing the path at each temperature potential value into a predetermined number of points, obtaining a direction vector with the surface one level below at each point, and setting the direction vector as the orientation of the welding torch 1a at each point.

[0026] Furthermore, this 3D model slicing unit 2b aligns the divided points with the direction of the welding torch 1a to form a lamination path. The lamination control information generating unit 2c generates the movement of the welding robot 1 so as to follow the lamination path generated by the 3D model slicing unit 2b.

[0027] In this embodiment, a temperature potential value is virtually set on the bottom and top surfaces of the stack W, but the present invention is not limited to this. In other words, instead of a temperature potential value, a potential value related to a physical quantity other than temperature related to the stack W may be virtually set on the bottom and top surfaces of the stack W.

[0028] The measurement control information generator 2d generates measurement control information based on the stacking control information input from the stacking control information generator 2c and the position and posture of the measuring instrument 1b input from the measuring instrument 1b via the control device 3. That is, the measurement control information generator 2d generates measurement control information so that the posture of the measuring instrument 1b is such that the laser is emitted in the direction of the previous stack height and the tangent direction of the previous stacking path is perpendicular to the laser scanning direction. The measurement control information generator 2d outputs the measurement control information to the control device 3.

[0029] The control information memory unit 3a temporarily stores the stacking control information input from the stacking control information generation unit 2c and the measurement control commands input from the measurement control information generation unit 2d, and sequentially outputs this stacking control information and measurement control commands to the robot control unit 3b.

[0030] The robot control unit 3b controls the welding robot 1 based on the stacking control information, out of the stacking control information and the measurement control information, to set the tip position of the welding torch 1a and the posture of the welding torch 1a, and also causes the measuring instrument 1b to measure the shape (cross-sectional profile) of the stack W based on the measurement control information.

[0031] Next, the operation of the layered manufacturing system A according to this embodiment, that is, the operation of the main parts of the control information generating device 2 (layered path generating device) according to this embodiment will be described.

[0032] First, the operation of the welding robot 1 in the additive manufacturing system A, that is, the operation of manufacturing the laminated body W, will be described with reference to the flowchart shown in Fig. 3. When the welding robot 1 performs the operation of manufacturing the laminated body W, the control information generating device 2 stores the lamination control information and measurement control information for N layers in the control information storage unit 3a of the control device 3.

[0033] The robot control unit 3b of the control device 3 reads out the lamination control information for N layers from the control information storage unit 3a, and controls the welding robot 1 based on the lamination control information for N layers to perform additive manufacturing of the laminated body W. That is, when the robot control unit 3b starts operation, it sets the arc discharge of the welding torch 1a to the ON state (step S1).

[0034] Then, the robot control unit 3b performs additive manufacturing of the first layer (initial layer) by sequentially moving the welding torch 1a of the welding robot 1 along the lamination path included in the lamination control information for the first layer (step S2).The robot control unit 3b then sets the arc discharge of the welding torch 1a to the OFF state (step S3), completing additive manufacturing of the Nth layer.

[0035] Next, the main operation of the control information generating device 2 (stacking path generating device) according to this embodiment, that is, the process of generating a stacking path, will be described with reference to Fig. 4. This stacking path generating process is characterized by using a potential field to calculate non-parallel branch stacking surfaces in the stack W, as will be described below.

[0036] 4, in the process of generating a stacking path in the control information generating device 2 (stacking path generating device), the stacking control information generating unit 2c first sets virtual temperature potential values ​​for the top and bottom surfaces of the stack W. Then, the stacking control information generating unit 2c calculates (obtains) the temperature potential field on the stack W by solving a Poisson equation related to the temperature potential values ​​using the well-known finite element method.

[0037] The stacking control information generator 2c then obtains a group of points with the same temperature potential value by extracting surface information of the stack W from the temperature potential field, and then obtains a unicursal line by solving the group of points as the well-known traveling salesman problem.

[0038] Furthermore, the stacking control information generator 2c divides the stacking path at each temperature potential value into a predetermined number of points, obtains a direction vector with respect to the surface immediately below at each point, and generates the stacking path by connecting these multiple direction vectors.

[0039] The additive manufacturing system A of this embodiment comprises a welding robot that performs additive manufacturing, a control information generating device 2 (lamination path generating device) that generates a lamination path for the welding robot, and a control device that controls the welding robot based on the lamination path, and the control information generating device 2 (lamination path generating device) generates the lamination path by using a temperature potential field to calculate the branch lamination surface.

[0040] According to this embodiment, a temperature potential field is used to calculate the branching stacking surface, making it possible to provide an additive manufacturing system A that can generate a stacking path that can prevent sagging of the stacked material without support material.

[0041] In this additive manufacturing system A, the control information generating device 2 (lamination path generating device) sets virtual temperature potential values ​​(potential values) on the bottom and top surfaces of the laminate W, solves the Poisson equation for the temperature potential values ​​(potential values) using the finite element method to calculate the temperature potential field (potential field) on the laminate W, extracts surface information of the laminate W from the temperature potential field (potential field) to obtain a point cloud of identical temperature potential values ​​(potential values), solves the traveling salesman problem to determine the order in which to trace the point cloud, obtains a non-intersecting, single-stroke line that minimizes the length of the laminate path, divides the path at each temperature potential value (potential value) into a predetermined number of points, obtains a direction vector with respect to the surface one below at each point, and connects the direction vectors to obtain the laminate path. According to this embodiment, it is possible to generate a laminate path that can more accurately prevent sagging of the laminate material without support material.

[0042] Furthermore, the control information generating device 2 (lamination path generating device) employs a temperature potential value related to temperature as the potential value. According to this embodiment, it is possible to generate a lamination path that can more accurately prevent sagging of the laminated material without using a support material. [Explanation of symbols]

[0043] A. Additive manufacturing system W laminate 1. Welding robot 1a Welding torch 1b Measuring instrument 2. Control information generator (lamination path generator) 2a 3D model acquisition section 2b 3D model slice section 2c Stacking control information generation unit 2d Measurement control information generation unit 3. Control device 3a Control information storage unit 3b Robot control unit

Claims

1. 1. An additive manufacturing system comprising: a welding robot that performs additive manufacturing; a lamination path generating device that generates a lamination path for the welding robot; and a control device that controls the welding robot based on the lamination path, The stacking path generation device is an additive manufacturing system that generates the stacking path by using a potential field to calculate a branching stacking surface.

2. The stacking path generating device includes:

2. The additive manufacturing system according to claim 1, wherein virtual potential values ​​are set on the bottom and top surfaces of the stack, a Poisson's equation for the potential values ​​is solved using the finite element method to calculate a potential field on the stack, a cloud of points with the same potential values ​​is obtained by extracting surface information of the stack from the potential field, a traveling salesman problem is solved to determine the order in which to trace the cloud of points to obtain a non-intersecting, unicursal line that minimizes the length of the stack path, the path at each potential value is divided into a predetermined number of points, a direction vector with respect to the surface one below is obtained at each point, and the stack path is obtained by connecting each point with the direction vector.

3. The additive manufacturing system according to claim 2 , wherein the potential value is a temperature potential value related to temperature.

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