Serial molding device and method for manufacturing three-dimensional molding

Abstract

To provide a serial molding device and a method for manufacturing a three-dimensional molding which can suppress occurrence of scratches in workpiece.SOLUTION: In serial molding, a tool 1 is used which has a housing 11 having an opening 16c and a ball storage part 15a, a plurality of rolling balls 12 rotatably arranged along an inner surface 15c of the ball storage part, and a molding ball 13 which has a diameter larger than those of the rolling balls 12 and is rotatably stored in the ball storage part 15a through the rolling balls 12 so as to be partially exposed from the opening 16c.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an incremental forming apparatus for incrementally forming a plate-like workpiece, and a method for manufacturing a three-dimensional molded product by incremental forming. [Background technology]

[0002] Conventionally, in order to form a desired three-dimensional shape, a technique called incremental forming has been used in which a rod-shaped tool or a tool having a rotating ball at its tip is pressed against a plate-shaped workpiece.

[0003] For example, the incremental forming device of Patent Document 1 includes two pressing members as tools and a support means for moving a plate material as a workpiece in three directions, including two orthogonal axial directions in a plane and a direction orthogonal to these two axes. This incremental forming device forms a three-dimensional shape by moving the pressing members in three directions while pressing them against both sides of the plate material. Patent Document 1 also discloses members having rotatable balls at their tips as the first and second pressing parts. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2003-181551 A Summary of the Invention [Problem to be solved by the invention]

[0005] In conventional incremental molding devices, even when a tool equipped with balls is used, the balls may not rotate sufficiently and may slide on the workpiece, resulting in friction between the balls and the workpiece and causing scratches on the surface of the workpiece.

[0006] An object of the present invention is to provide an incremental molding apparatus and a method for manufacturing a three-dimensional molded product that can suppress the occurrence of scratches on a workpiece. [Means for solving the problem]

[0007] The incremental molding apparatus of the present invention comprises a tool having a housing having a ball accommodating portion; a molding ball rotatably accommodated in the ball accommodating portion so that a portion of the molding ball protrudes from the housing; and a plurality of rolling balls which are smaller in diameter than the molding ball and are rotatably arranged in contact with the ball accommodating portion and the molding ball; and a molding unit which incrementally molds a plate-shaped workpiece by pressing the molding ball against at least one side of the workpiece and moving the tool relative to the workpiece.

[0008] In addition, the manufacturing method of a three-dimensional molded product of the present invention includes a step of sequentially molding the workpiece by pressing the molding ball against at least one surface of a plate-shaped workpiece while moving the tool relative to the workpiece. Effect of the Invention

[0009] According to the present invention, by disposing the rolling ball between the ball receiving portion of the housing and the formed ball, the frictional resistance between the formed ball and the ball receiving portion is extremely small, so that the formed ball rotates easily and slippage is unlikely to occur on the contact surface with the workpiece, thereby suppressing the occurrence of scratches on the workpiece. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a perspective view of a tool according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a cross-sectional view of the tool of FIG. [Diagram 3] FIG. 3(a) is a diagram for explaining the frictional resistance between the tool and the workpiece and the frictional resistance within the tool in an embodiment, and FIG. 3(b) is a diagram for explaining the frictional resistance between the tool and the workpiece and the frictional resistance within the tool in a comparative embodiment. [Figure 4] FIG. 4 is a front view of an incremental forming apparatus including the tool of FIG. [Diagram 5] FIG. 5 is a plan view of the incremental forming apparatus of FIG. [Figure 6] FIG. 6 is a diagram for explaining incremental forming using the tool of FIG. 1 in the thickness direction of a workpiece. [Figure 7] FIG. 7 is a diagram for explaining incremental forming using the tool of FIG. 1 in the surface direction of a workpiece. [Figure 8] FIG. 8 is a diagram for explaining incremental forming using the tool of this embodiment on only one side. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Exemplary embodiments will now be described in detail with reference to the accompanying drawings.

[0012] 1.Tools Fig. 1 is a perspective view of a tool 1 of this embodiment, and Fig. 2 is a cross-sectional view of the tool 1. As shown in Figs. 1 and 2, the tool 1 includes a housing 11, rolling balls 12, and a molding ball 13.

[0013] The housing 11 has a base 15 , a ball retainer 16 and a fastener 17 .

[0014] The base 15 is a generally cylindrical member having a ball receiving portion 15a on one bottom surface of the cylinder and two fixing holes 15b on the side surface. The ball receiving portion 15a is a generally hemispherical recess. This recess, i.e., the inner surface of the ball receiving portion 15a, is labeled "15c." The rolling balls 12 and the molded balls 13 are received in the ball receiving portion 15a.

[0015] The ball holder 16 holds the rolling ball 12 and the molded ball 13 so that they do not fall out of the ball accommodating portion 15a while allowing a part of the molded ball 13 to protrude from the housing 11. Specifically, the outer shape of the ball holder 16 is a cylinder with one of the bottom surfaces chamfered all around. In other words, the outer shape of the ball holder 16 is a combination of a truncated cone and a cylinder connected to the bottom surface. The ball holder 16 has a cavity 16a therein for accommodating the base 15. A circular opening 16c leading to the cavity 16a is provided on the upper surface of the truncated cone of the ball holder 16. The diameter of the opening 16c is set smaller than the diameter of the molded ball 13, so that a part of the molded ball 13 accommodated in the ball accommodating portion 15a protrudes from the opening 16c to the outside of the ball holder 16. The ball holder 16 further has two fixing holes 16b leading from its side surface to the cavity 16a. The fixing holes 16b are provided at positions corresponding to the fixing holes 15b of the base 15 housed within the cavity 16a.

[0016] The fastener 17 is inserted into the fixing hole 15 b of the base 15 through the fixing hole 16 b of the ball retainer 16 .

[0017] The rolling balls 12 are arranged along the inner surface 15c of the ball receiving portion 15a, and can freely rotate while in contact with the inner surface 15c of the ball receiving portion 15a and the molded ball 13.

[0018] Molded ball 13 has a diameter larger than that of rolling ball 12, and is rotatably housed in ball housing portion 15a. Rolling ball 12 is interposed between molded ball 13 and inner surface 15c of ball housing portion 15a, and when molded ball 13 rotates, rolling ball 12 rotates in all rotation directions.

[0019] During assembly, with the rolling ball 12 and the molded ball 13 accommodated in the ball accommodating portion 15a, the ball retainer 16 is placed over the base 15 so that a portion of the molded ball 13 protrudes from the opening 16c. By passing the fastener 17 through the fixing hole 16b and the fixing hole 15b, the ball retainer 16 is fixed to the base 15 and the molded ball 13 and the rolling ball 12 are held in the ball accommodating portion 15a. Note that instead of the fastener 17, a male screw may be provided on the outer periphery of the base 15 and a female screw may be provided on the inner periphery of the ball retainer 16, and the ball retainer 16 may be fixed to the base 15 by these screw structures.

[0020] The tool 1 has a so-called rolling bearing structure, more specifically a free ball bearing structure, in which the rolling balls 12, which have a smaller diameter than the forming balls 13, can freely rotate while being in contact with the forming balls 13 and the ball receiving portion 15a (inner surface 15c) as the forming balls 13 rotate. This structure allows the forming balls 13 to rotate lightly without being subjected to a large frictional force, thereby preventing damage to the workpiece during incremental forming.

[0021] The details will be described with reference to Fig. 3(a) and Fig. 3(b). Fig. 3(a) is a diagram for explaining the frictional resistance A between the tool 1 and the workpiece M and the frictional resistance B within the tool 1, and Fig. 3(b) is a diagram for explaining the frictional resistance C between the tool 101 and the workpiece M and the frictional resistance D within the tool 101 in the comparative embodiment.

[0022] As shown in FIG. 3(a), when forming the workpiece M, the tool 1 is pressed against the plate-shaped workpiece M and moved relative to the workpiece M in the surface direction of the workpiece M. The forming ball 13 rotates with this movement, and frictional resistance A due to rolling friction occurs between the forming ball 13 and the workpiece M. As the forming ball 13 rotates, frictional resistance B due to rolling friction is applied to the forming ball 13 in the tool 1 as well. However, since the rolling balls 12 are interposed between the inner surface 15c of the ball receiving portion 15a and the forming ball 13, the frictional resistance B is very small. In comparison, the frictional resistance A is larger than the frictional resistance B. As a result, when the tool 1 is moved relative to the workpiece M, the forming ball 13 rotates following the movement and does not slip on the contact surface of the workpiece M.

[0023] As shown in FIG. 3(b), the comparative tool 101 does not have the rolling ball 12, and a molding ball 113 similar to the molding ball 13 is directly disposed on the inner surface 115c of the ball receiving portion 115a, which is a semispherical recess. The frictional resistance C between the molding ball 113 and the workpiece M is equivalent to the frictional resistance A of the embodiment. On the other hand, the frictional resistance D acting on the molding ball 113 in the tool 101 is generated by sliding friction between the inner surface 115c, and is larger than the frictional resistance C due to rolling friction because the contact surface between the molding ball 113 and the inner surface 115c is large. If the frictional resistance D is large in this way, the rotation of the molding ball 113 cannot sufficiently follow the movement between the workpiece M and the molding ball 113, and the molding ball 113 slides against the workpiece, or even becomes locked and stops rotating. If molding is continued in this state where the rotation of the molding ball 113 is insufficient, the molding ball 113 may rub against the workpiece M, causing scratches. One way to prevent such scratches is to reduce the frictional resistance D by using a lubricant, for example. However, since the lubricant adheres to the workpiece M, a process for removing the lubricant by wiping, washing, or the like after forming is required.

[0024] In contrast, when the tool 1 is used, the forming balls 13 can rotate without slipping on the workpiece M, so that the workpiece M is less likely to be scratched. Due to this effect, even if the workpiece M is coated, it can be formed without peeling off the coating layer. Here, the coating includes plating and painting. In addition, due to the above effect, the tool 1 can be applied to materials with a glossy surface. Furthermore, since such light rotation is realized by the rolling balls 12, the amount of lubricant used can be reduced or no lubricant is required. In other words, compared to the comparative embodiment, the effort required to remove the lubricant from the workpiece M can be reduced or such a process can be omitted. In addition, since the force required to move the tool 1 relative to the workpiece is small, there is also the advantage that the power required for incremental forming can be reduced.

[0025] The material constituting each part of the tool 1 may be selected from known materials such as stainless steel (e.g., SUS440C tempered material) as long as it has a strength sufficient for use in incremental forming. The dimensions of each part, such as the diameter of the rolling ball 12, the diameter of the forming ball 13, and the diameter of the opening 16c, as well as the relationships between the ratios and differences between them, are appropriately set within the range satisfying the restrictions on the overall dimensions of the tool 1 and the strength sufficient for use in incremental forming.

[0026] For example, from the viewpoint of preventing interference of the housing 11 with the workpiece, in the longitudinal section of the tool 1 (Figure 2), the angle θ1 that the common tangent H between the outer shape of the housing 11 (the outer shape of the ball holder 16 in this embodiment) and the molding ball 13 forms with the axis I of the tool 1 is preferably 70° or less, more preferably 60° or less, or even more preferably 45° or less.

[0027] 2, as described above, the ball retainer 16 has a truncated cone shape by chamfering the outer periphery of the surface on which the opening 16c is provided (i.e., the "shoulder"). This chamfering is also preferable from the viewpoint of preventing interference of the housing 11 with the workpiece. For example, the chamfer angle θ2 (the angle between the surface on which the opening 16c is provided and the side surface of the truncated cone) is preferably 160° or less, more preferably 150° or less, and even more preferably 135° or less.

[0028] 2. Incremental molding device and manufacturing method for three-dimensional molded product Hereinafter, an incremental forming apparatus 100 for forming a workpiece M using a first tool, a tool 1, and a second tool, a tool 1', having the same structure as the tool 1, will be described with reference to Figs. 4 and 5. Figs. 4 and 5 are diagrams showing a schematic configuration of the incremental forming apparatus 100, in which Fig. 4 is a front view and Fig. 5 is a plan view. As shown in Figs. 4 and 5, the incremental forming apparatus 100 of this embodiment has a holding frame 2 for holding the workpiece M, an upper forming unit 31 for moving the tool 1 relative to the upper surface of the workpiece M, and a lower forming unit 31' for moving the tool 1' relative to the lower surface of the workpiece M. The x-axis, y-axis, and z-axis in the figure are mutually perpendicular, the x-axis and y-axis are horizontal, and the z-axis is vertical.

[0029] The holding frame 2 is a rectangular frame parallel to the xy plane, having two pairs of sides parallel to the x-axis and y-axis. A plurality of clips 21 are attached to each of the four sides of the holding frame 2. Specifically, one clip 21 has a pressing member, which is a plate-shaped member, and a plurality of fasteners (two in this embodiment) that displace the pressing member between a fixed position where the workpiece M is pressed against the holding frame 2 by contacting the workpiece M, and a released position where the workpiece M is separated from the workpiece M. The plate-shaped workpiece M is placed on the holding frame 2, and is fixed to the holding frame 2 by the clips 21 so that the position does not shift. In this way, the workpiece M is held with its surface direction parallel to the xy plane (i.e. horizontal) and its thickness direction parallel to the z-axis (i.e. vertical). In the area surrounded by the holding frame 2, both sides of the workpiece M are exposed, so that the tool 1 and the tool 1' can abut against both sides of the workpiece M.

[0030] The upper forming unit 31 is an example of a forming unit that moves the tool 1 three-dimensionally. The forming unit may be capable of successively forming the workpiece by pressing forming balls against at least one surface of the plate-shaped workpiece and moving the tool relative to the workpiece. In particular, when pressing tools having forming balls against both surfaces of the workpiece, the tools corresponding to both surfaces may be moved in a state of being shifted from each other in the surface direction of the workpiece.

[0031] For example, the forming unit may include a first shaft body, a second shaft body movably held by the first shaft body, and a third shaft body movably held by the second shaft body, in which case the tool is movably held by the third shaft body. Each shaft body is perpendicular to the other shaft bodies. Here, the "movably held" can be realized by, specifically, attaching a slider that can move along the shaft body to each shaft body, and holding the other shaft bodies on the slider. As a more detailed example, Figs. 4 and 5 show a form in which the first shaft body is arranged parallel to the x-axis, the second shaft body is arranged parallel to the y-axis, and the third shaft body is arranged parallel to the z-axis.

[0032] The upper forming unit 31 shown in FIG. 5 has two first shaft bodies 41, two first sliders 42, a second shaft body 51, a second slider 52, a third shaft body 6, and a tool holder 7.

[0033] The first shaft body 41 is installed above the holding frame 2 in parallel to the x-axis so as to sandwich the holding frame 2 in the y-axis direction. The first slider 42 is attached to the first shaft body 41 so as to move linearly along the first shaft body 41, i.e., along the x-axis. The second shaft body 51 is arranged parallel to the y-axis, and both ends of the second shaft body 51 are held by the first slider 42. In this way, the second shaft body 51 is bridged between the first shaft bodies 41 so as to move in the x-axis direction. The second slider 52 is attached to the second shaft body 51 so as to move linearly along the second shaft body 51, i.e., along the y-axis. In this embodiment, two first shaft bodies 41 are provided parallel to the x-axis, and the first slider 42 is attached to each of them, but this is not limited to the above. The second shaft body 51 may be held in a cantilevered manner by providing only one first shaft body 41 and one first slider 42.

[0034] The third shaft body 6 is held movably in the y-axis direction by having one end held by the second slider 52, and is disposed so as to extend downward parallel to the z-axis. The tool holder 7 is held movably by the third shaft body 6, and holds the tool 1 facing downward with its axis parallel to the z-axis. In other words, the tool 1 is held so that the forming ball 13 faces the upper surface of the workpiece M on the holding frame 2.

[0035] With the above configuration, the second shaft body 51 moves in the x-axis direction while remaining parallel to the y-axis, the third shaft body 6 moves in the y-axis direction while remaining parallel to the z-axis, and the tool holder 7 moves in the z-axis direction. In this way, the upper forming unit 31 can move the tool 1 held by the tool holder 7 in three directions, the x-axis, y-axis, and z-axis directions, relative to the upper surface of the workpiece M. Movement in each direction can be achieved by a drive unit such as a hydraulic cylinder, an air cylinder, or a motor, and a mechanical structure such as a pulley, a belt, or a ball screw. In addition, the drive mechanism for movement in each direction may be the same, or a different drive mechanism may be adopted depending on the direction. In addition, even if the shaft body is held by two sliders like the second shaft body 51, it is not necessary to apply power for movement to both sliders, but only one of them is sufficient.

[0036] The lower forming unit 31' has two first shafts 41', a first slider 42', a second shaft 51', a third shaft 6' and a tool holder 7'. These members have the same structures as the first shaft 41, the first slider 42, the second shaft 51, the third shaft 6 and the tool holder 7 of the upper forming unit 31, respectively, and are arranged upside down with respect to the upper forming unit 31. That is, the lower forming unit 31' holds the tool 1' facing upward by the tool holder 7', and can move the second shaft 51', the third shaft 6' and the tool holder 7' in the x-axis, y-axis and z-axis directions, respectively. That is, with the forming ball 13' of the tool 1' facing the lower surface of the workpiece M, the tool 1' can move in three directions, the x-axis, y-axis and z-axis, relative to the lower surface of the workpiece M.

[0037] In addition, the incremental molding apparatus 100 has a control device (not shown) such as an NC device, and the control device can control the movement of the upper molding unit 31 and the lower molding unit 31' so as to three-dimensionally mold the workpiece M in accordance with data input by the user.

[0038] The incremental forming process in the incremental forming apparatus 100 will be described below. In this process, the forming ball 13 of the tool 1 and the forming ball 13' of the tool 1' are moved while being pressed against the workpiece M, so that a three-dimensional molded product having a desired shape can be produced from the workpiece M by incremental forming. Figures 6 and 7 are diagrams particularly for explaining a case where the workpiece M is molded into an upward convex shape, with Figure 6 being a diagram for explaining the thickness direction of the workpiece M and Figure 7 being a diagram for explaining the surface direction.

[0039] As shown in Fig. 6, when forming the workpiece M into an upward convex shape, the upper tool 1 is aligned with the top surface of the workpiece M, while the tool 1' is pushed in to a position higher than the bottom surface of the workpiece M at a position offset from the tool 1 in the xy plane direction. The distance between the vertices of the tool 1 and the tool 1' in the xy plane direction is illustrated as the distance G. Also, the distance between the vertices of the tool 1 and the tool 1' in the z-axis direction is illustrated as the push-in amount F. Here, the "vertex" refers to the portion of the forming ball 13 that protrudes most in the axial direction of the tool 1 and the tool 1'.

[0040] As shown in FIG. 7, the upper forming unit 31 and the lower forming unit 31' are synchronized while appropriately adjusting the interval G so as to maintain the pushing amount F, and the tool 1 and the tool 1' are rotated in the xy plane so as to draw a trajectory P and a trajectory P' inside the trajectory P, respectively. To increase the height of the convex portion, the tool 1 and the tool 1' are moved so as to draw a further trajectory inside the trajectories P and P', respectively. By repeating the operation to draw a contour line in this way, the convex portion can be gradually made taller. Also, to increase the height while widening the width in the surface direction of the convex portion, the operation is repeated to draw a trajectory outside the previous trajectory.

[0041] When forming the workpiece M into a downward convex shape, that is, when forming a recess, the lower tool 1' is aligned with the lower surface of the workpiece M, and the upper tool 1 is pushed in to a position lower than the upper surface of the workpiece M, with a gap between it and the tool 1' in the xy plane, in the opposite manner to that shown in FIG. 6. The tool 1 and the tool 1' are also moved so that the tool 1 traces an orbit inside the orbit of the tool 1'. To deepen the recess, the operation can be repeated so that the orbit traces an even further inward orbit. Alternatively, to widen and deepen the recess, the operation can be repeated so that the orbit traces a new orbit outside the previously traced orbit. In this way, the workpiece M can be three-dimensionally formed.

[0042] The gap G and the amount of depression F may be set depending on external factors such as the desired shape and thickness of the workpiece M, and internal factors such as the shape of the tool 1 (and tool 1'). For example, the gap G and the amount of depression F are set so that the housing 11, particularly the ball holder 16, does not come into contact with the workpiece M. As described above with reference to Fig. 2, the smaller the angle θ1, the less likely the housing 11 and the workpiece M will interfere with each other, and therefore the degree of freedom in the gap G and the amount of depression F is increased.

[0043] The workpiece M is preferably plate-shaped and flat. The workpiece M is preferably a metal plate such as stainless steel, steel, iron, aluminum, etc. As described above, the surface condition such as the presence or absence of coating or the presence or absence of gloss is not particularly limited, so various materials can be used, such as coated metal plates such as color steel plates and plated steel plates, black materials, and polished materials.

[0044] 3. Other embodiments As described above, the above embodiment has been described as an example of the technology disclosed in this application. However, the technology in this disclosure is not limited to this, and can be applied to embodiments in which modifications, replacements, additions, omissions, etc. are appropriately performed. In addition, it is also possible to combine the components described in the above embodiment to form a new embodiment. In addition, among the components described in the attached drawings and detailed description, not only components essential for solving the problem but also components that are not essential for solving the problem in order to exemplify the technology may be included. Therefore, the fact that these non-essential components are described in the attached drawings and detailed description should not immediately be taken to mean that these non-essential components are essential.

[0045] For example, this application also discloses the following techniques:

[0046] (1) In Fig. 6, the tool 1 and the tool 1' are pressed against both sides of the workpiece M, respectively, but the present invention is not limited to this, and the tool 1 may be pressed against only one side of the workpiece M. For example, as shown in Fig. 8, the workpiece M can be shaped along the mold 10 by pressing a mold 10 against one side while pressing the tool 1 against the other side.

[0047] (2) In Figures 4 and 5, the workpiece M is held with its surface direction horizontal and its thickness direction vertical, but the workpiece M may be positioned in any way during processing, for example, the workpiece M may be positioned so that its surface direction is vertical. In this case, for example, the upper forming unit 31 and the lower forming unit 31' shown in Figure 4 etc. may be positioned on the left and right of the workpiece M.

[0048] (3) In Figures 4 and 5, the tools 1 and 1' are moved by the upper forming unit 31 and the lower forming unit 31'. However, instead of this, a forming unit that moves the workpiece relative to the tools may be used.

[0049] (4) The upper forming unit 31 and the lower forming unit 31' in Figures 4 and 5 have members parallel to three directions of the x-axis, y-axis, and z-axis, and are configured to move the tools 1 and 1' along these members, but other configurations capable of moving the tools can also be applied as the forming unit. For example, a device having a hand to which a tool is attached and an arm having a plurality of joints and links, and configured to move the hand via the joints and links by an actuator, an electric mechanism, or the like, may be applied as the forming unit.

[0050] (5) In Figures 4 and 5, incremental forming using numerical control, such as an NC machine tool, has been described. However, the tool of the present invention may also be applied to incremental forming including manual forming using a general-purpose machine tool.

[0051] (6) Any combination of the above-mentioned embodiments is also included in the disclosure of this application. [Industrial Applicability]

[0052] The present invention can be applied to incremental forming for forming a plate-like workpiece. [Explanation of symbols]

[0053] 1, 1' tool 11. Housing 12 Rolling ball 13, 13' Molded Ball 15 Pedestal 15a Ball storage section 15b Fixing hole 15c Inner surface of ball receiving section 16 Ball Holder 16a Cavity 16b Fixing hole 16c aperture 17 Fasteners A~D Friction resistance M Workpiece 100 Sequential molding equipment 2 Holding frame 21 clips 31 Upper forming unit 31' Lower forming unit 41, 41' First shaft 42, 42' 1st slider 51, 51' Second shaft body 52,52' 2nd slider 6, 6' 3rd axis 7, 7' Tool holder 10-inch G interval F Push-in amount P, P' orbital

Claims

1. a tool including: a housing having a ball receiving portion; a molding ball rotatably received in the ball receiving portion so that a portion of the molding ball protrudes from the housing; and a plurality of rolling balls having a smaller diameter than the molding ball and rotatably disposed in contact with the ball receiving portion and the molding ball; a forming unit that sequentially forms a plate-shaped workpiece by moving the tool relative to the workpiece while pressing the forming ball against at least one surface of the workpiece; An incremental molding apparatus comprising:

2. the frictional resistance between the forming ball and the workpiece is greater than the frictional resistance between the forming ball and the rolling ball; The incremental forming apparatus of claim 1 .

3. The tool includes a first tool pressed against one surface of the workpiece and a second tool pressed against the other surface of the workpiece, The forming unit is configured to move the first and second tools in a state where they are shifted from each other in a surface direction of the workpiece. The incremental molding apparatus according to claim 1 or 2.

4. the step of using a tool having a housing with a ball receiving portion; a molding ball rotatably received in the ball receiving portion so that a part of the molding ball protrudes from the housing; and a plurality of rolling balls having a diameter smaller than that of the molding ball and rotatably disposed in contact with the ball receiving portion and the molding ball, and gradually forming the workpiece by moving the tool relative to the workpiece while pressing the molding ball against at least one surface of the plate-shaped workpiece, A method for manufacturing a three-dimensional molded product.

5. The workpiece is a metal plate having a coating. The method according to claim 4.

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