Incremental forming method and incremental forming device

Abstract

Provided is a sequential shaping method for shaping a metal plate W, being held at the periphery thereof, into a three-dimensional shape by moving the tip-end part of a bar-shaped tool T pressed against the main surface of the metal plate W. As the bar-shaped tool T moves, the metal plate W is shaped while forming a machining trajectory Fw having an amplitude H in a direction intersecting the movement direction of the bar-shaped tool T and extending along the shaping surface of the metal plate W. In this way, the machined portion along which the bar-shaped tool T has passed can be made virtually wider and tool trace can be suppressed during shaping, thus enhancing the appearance quality of the shaped product, while achieving reductions in facility expenses and manufacturing costs.

Description

[Technical Field]

[0001] The present invention relates to an incremental forming method and an incremental forming apparatus for forming a metal plate into a three-dimensional shape by pressing and moving a rod-shaped tool against the metal plate. [Background technology]

[0002] A conventional incremental forming method is described, for example, in Patent Document 1. The incremental forming method described in Patent Document 1 uses a rod-shaped pressing member arranged on one side of a plate material and a concave pressing member arranged on the other side of the plate material. The rod-shaped pressing member has a flexible member at its tip.

[0003] In the incremental forming method, the flexible member of the rod-shaped pressing member is pressed against the plate material, and the rod-shaped pressing member is moved while tracing contour lines, so that the plate material is pressed and expanded into the concave pressing member to form a three-dimensional shape. By using a rod-shaped pressing member having a flexible member, the incremental forming method increases the contact area between the rod-shaped pressing member and the plate material, thereby suppressing tool marks. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent No. 3777130 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the conventional incremental forming method described above, because a rod-shaped pressure member equipped with a flexible member that contacts the plate material is used, it is difficult to cause sufficient deformation of the plate material, and auxiliary equipment such as a concave pressure member is required. In addition, the rod-shaped pressure member has a short lifespan and must be replaced frequently. As a result, while the conventional incremental forming method can suppress tool marks on the molded product, it has the problem of making it difficult to reduce equipment costs and manufacturing costs.

[0006] The present invention has been made in consideration of the above-mentioned conventional situation, and aims to provide an incremental molding method and an incremental molding apparatus that can improve the appearance quality of molded products while reducing equipment costs and manufacturing costs. [Means for solving the problem]

[0007] The incremental forming method according to the present invention is a method for forming a metal sheet into a three-dimensional shape by pressing the tip of a rod-shaped tool against a main surface of the metal sheet whose periphery is held and moving the tool. This incremental forming method is characterized in that, as the rod-shaped tool moves, the metal sheet is formed while forming a processing locus that has an amplitude in a direction that intersects the moving direction of the rod-shaped tool and that follows the forming surface of the metal sheet.

[0008] The incremental forming apparatus according to the present invention is an incremental forming apparatus used in the incremental forming method described above, and includes a clamping device that holds the periphery of a metal plate, a rod-shaped tool arranged on one side of the metal plate, a tool driving device that moves the rod-shaped tool in three mutually perpendicular axial directions, and a vibration imparting device that imparts vibration to at least one of the clamping device and the rod-shaped tool, and forms the metal plate while forming a processing locus by the vibration imparted by the vibration imparting device, In this case, the movement path of the bar-shaped tool includes a contoured circular path, the amplitude of the processing trajectory is H (mm), the interval between adjacent circular paths is Ps (mm), the radius of curvature of the tip of the bar-shaped tool is R (mm), and the forming angle, which is the angle between the main surface of the metal plate before forming and the inclined surface after forming, is θ. The amplitude H of the processing trajectory is a random value equal to or less than Hmax that satisfies 2H≧1.2Ps−R*θ, The distance G of the displacement with the amplitude in the machining path satisfies G≦0.25 / H (mm). [Effects of the Invention]

[0009] By adopting the above-mentioned configuration, the incremental forming method and incremental forming apparatus of the present invention do not require auxiliary equipment such as molding dies, and by using hard rod-shaped tools with a long life, it is possible to reduce equipment costs and manufacturing costs while improving the appearance quality of the molded product. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 2 is an explanatory cross-sectional view showing an enlarged view of a processing locus with a regular amplitude in the first embodiment of the incremental forming method and incremental forming device according to the present invention. [Figure 2] FIG. 2 is a cross-sectional view showing the main part of incremental forming. [Figure 3] FIG. 10 is an explanatory diagram showing a machining locus with irregular amplitude. [Figure 4] FIG. 10 is an explanatory diagram showing machining trajectories with regular amplitudes in adjacent circular paths. [Figure 5] FIG. 10 is an explanatory diagram showing machining trajectories with irregular amplitudes in adjacent circular paths. [Figure 6] 1 is a graph showing the relationship between amplitude and surface roughness of the molding surface. [Figure 7] 10 is a graph showing the relationship between the ratio of amplitude to the interval between adjacent circular paths and the displacement interval in the machining trajectory. [Figure 8] FIG. 10 is a side view illustrating a rod-shaped tool according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] First Embodiment 1 is a diagram showing an incremental forming apparatus to which the incremental forming method according to the present invention can be applied. The illustrated incremental forming apparatus basically comprises a clamping device 1 that holds the periphery of a metal sheet W, a rod-shaped tool T arranged on one main surface side of the metal sheet W (the upper side in FIG. 1), a tool driving device 2 that drives the rod-shaped tool T, and a main control device 3 that controls the tool driving device 2.

[0012] The metal sheet W is a flat plate that is the raw material for the formed product, and in this embodiment, the periphery is held horizontally by clamps 1. The incremental forming method according to the present invention is a dieless forming method that does not use a forming mold. In this incremental forming method, the metal sheet W can also be held vertically or inclined, and a rod-shaped tool T and clamping device 1 are positioned according to the orientation of the metal sheet W. The clamping device 1 has a fixed lower frame portion 1A and an upper frame portion 1B that can be raised and lowered relative to the lower frame portion 1A, and the periphery of the metal sheet W is firmly clamped between the lower frame portion 1A and the upper frame portion 1B.

[0013] In the illustrated example, the rod-shaped tool T is held in a position with its axis in the vertical direction, and is a well-known tool with a lower tip having an appropriate shape such as a spherical shape, and is driven in three orthogonal axial directions by the tool driving device 2. This rod-shaped tool T is hard and has a long life, and is typically made of metal.

[0014] A multi-axis controlled work robot or an NC machine tool can be used as the tool driving device 2. The tool driving device 2 in the illustrated example moves the attached rod-shaped tool T in the horizontal X and Y directions and the vertical Z direction. The rod-shaped tool T can also be rotated around each axis.

[0015] The main control device 3 is a computer, and data for driving the rod-shaped tool T, such as all movement paths from the forming start point to the forming end point, movement speeds, and amount of pressure applied to the metal plate W, are input in advance.

[0016] Generally, in the incremental forming method, as shown in Figure 1, the tip of a rod-shaped tool T is pressed against a metal sheet W whose periphery is held by a clamping device 1 and moved. Figure 2 is a cross-sectional view of the rod-shaped tool T as seen from the direction of movement. After moving along a circular path at the position shown by the solid line in Figure 2, the rod-shaped tool T performs pitch feed, moving toward the center of the metal sheet W (to the right in Figure 2) and downward, as shown by the imaginary line in the figure, and then repeats the movement along the next circular path and pitch feed operation. In this way, the incremental forming method forms the metal sheet W by gradually pressing down the bottom, and finally obtains a molded product with a three-dimensional shape.

[0017] In the incremental forming method according to the present invention, when incremental forming is performed as described above, the metal plate W is formed while forming a processing trajectory Fw having an amplitude perpendicular to the direction of movement of the rod-shaped tool T and in a direction along the forming surface of the metal plate W (in the direction of arrow A in the figure) as the rod-shaped tool T moves.

[0018] In this case, in the incremental forming method, it is possible to select a machining trajectory Fw having a regular amplitude relative to a machining reference line SL, which is the center of movement of the rod-shaped tool T, as shown in the enlarged view in Figure 1, or a machining trajectory Fw having an irregular amplitude relative to the machining reference line SL, as shown in Figure 3.

[0019] The above-mentioned machining path Fw can be formed by inputting a program in advance into the main control device 3 as a movement path of the rod-shaped tool T and controlling the tool driving device 2 with the program. Alternatively, the machining path Fw can be formed by providing vibration imparting devices 4, 5 to at least one of the clamping device 1 and the tool driving device 2, as shown in FIG. 1, and imparting vibration to at least one of the metal plate W held by the clamping device 1 and the rod-shaped tool T attached to the tool driving device 2.

[0020] The illustrated machining path Fw is a line through which the center of the bar-shaped tool T passes. In incremental forming, the bar-shaped tool T comes into contact with the metal sheet W over a predetermined area. Therefore, the machined portion (machining path Fw) actually formed by the passage of the bar-shaped tool T has a certain width according to the contact area, as shown in part in the upper left of FIGS. 1 and 3. In other words, in the incremental forming method of this embodiment, the bar-shaped tool T is moved based on a program, and the bar-shaped tool T and the metal sheet W are vibrated relatively to each other, so as to obtain the actual machining path Fw.

[0021] In the incremental forming method described above, when the machining path Fw has a regular amplitude as shown in Fig. 4, a preferred embodiment is one in which the movement path of the bar-shaped tool T includes a contoured circular path, the amplitude of the machining path Fw is H (mm), the spacing between adjacent circular paths is Ps (mm), the radius of curvature of the tip of the bar-shaped tool is R (mm), and the forming angle, which is the angle between the main surface of the metal sheet W before forming and the slope after forming, is θ (shown in Fig. 2), and the amplitude H of the machining path Fw satisfies 2H ≥ 1.2Ps - R * θ, and the interval G of displacement along the machining path Fw with the amplitude H satisfies G ≤ 0.25 / H (mm), more preferably, G ≤ 0.225 / H (mm). Note that the constant 1.2 in the equation for amplitude H was calculated based on the conditions that led to a pass judgment in the test described below.

[0022] Furthermore, in the above-described incremental forming method, when the machining locus Fw has an irregular amplitude as shown in FIG. 5, a preferred embodiment is such that the movement path of the bar-shaped tool T includes a contoured circular path, the amplitude of the machining locus Fw is H (mm), the interval between adjacent circular paths is Ps (mm), the radius of curvature of the tip of the bar-shaped tool T is R (mm), and the forming angle, which is the angle between the main surface of the metal sheet W before forming and the slope after forming, is θ, the amplitude H of the machining locus Fw is a random value equal to or less than Hmax that satisfies 2H≧1.2Ps−R*θ, and the interval G of displacement with the amplitude H in the machining locus Fw satisfies G≦0.25 / H (mm), and more preferably, the interval G satisfies G≦0.225 / H (mm).

[0023] A test was conducted on the incremental forming method described above. In the test, an aluminum plate (metal plate W) with a thickness of 0.95 mm was used, and a rod-shaped tool T with a diameter of 20 mm and a tip curvature radius R of 3 mm was used to form the workpiece at a forming angle θ of 15 degrees. In both cases where the amplitude H was regular and irregular, the spacing Ps of the circular path was kept constant at 1,159 mm, and the spacing G (displacement spacing) of the displacement accompanying the amplitude H in the processing trajectory Fw was kept constant at 0.5 mm.

[0024] Then, incremental forming was performed while changing the amplitude H between 100 μm and 500 μm in 100 μm increments, and the surface roughness (arithmetic mean roughness) Ra of the formed surface was measured. As a result, it was found that when incremental forming was performed while forming a processing locus Fw, the width of the processed portion became artificially thicker and tool marks became less noticeable compared to when the rod-shaped tool T was moved linearly, and in particular, as shown in Figure 6, the surface roughness Ra of the formed surface decreased as the amplitude H increased, and tool marks could be significantly suppressed.

[0025] In the above test, the interval Ps of the circular path and the displacement interval G of the processing trajectory Fw were kept constant at 0.5 mm, as described above, and incremental forming was performed by changing the amplitude H to 30 (μm), 150 (μm), 300 (μm), and 400 (μm).

[0026] As a result, it was found that the effect of suppressing tool marks was more pronounced when the amplitude H was set to 300 μm and 400 μm (circles in the figure) than when the amplitude H was set to 30 μm and 150 μm (triangles in the figure), as shown in Figure 7. Note that Figure 7 shows the relationship between the ratio of the amplitude H to the pitch Ps of the circular path and the displacement interval G.

[0027] The test results above have shown that the incremental forming method can obtain a good formed surface with less visible tool marks by ensuring that the spacing G of displacement with amplitude H in the processing trajectory Fw satisfies G≦0.25 / H (mm), and more preferably G≦0.225 / H (mm).

[0028] The incremental forming method described in the above embodiment forms the metal sheet W while, as the rod-shaped tool T moves, forming a processing locus Fw having an amplitude H in a direction that intersects the direction of movement and that is along the forming surface of the metal sheet W. As a result, the incremental forming method does not require auxiliary equipment such as a forming mold, and can use a hard rod-shaped tool T with a long life, thereby reducing equipment costs and manufacturing costs, while forming a forming surface on which tool marks are difficult to see and improving the appearance quality of the formed product.

[0029] The incremental forming apparatus described in the above embodiment includes a clamping device 1, a rod-shaped tool T, a tool driving device 2, and vibration imparting devices 4 and 5 that impart vibrations to at least one of the metal sheet W and the rod-shaped tool T. The metal sheet W is formed while forming a processing locus Fw by the vibrations imparted by the vibration imparting devices 4 and 5. Alternatively, the tool driving device 2 moves the rod-shaped tool T along a movement path that forms the processing locus Fw to form the metal sheet W.

[0030] As a result, the incremental molding device does not require auxiliary equipment such as molding molds, and by using a long-life, hard rod-shaped tool T, it is possible to reduce equipment costs and manufacturing costs while forming a molding surface on which tool marks are difficult to see, thereby improving the appearance quality of the molded product.

[0031] Furthermore, the incremental forming method described above can enhance the effect of suppressing tool marks when the machining locus Fw has a regular amplitude H by making the amplitude H of the machining locus Fw satisfy 2H≧1.2Ps-R*θ and making the interval G of displacement accompanying the amplitude H in the machining locus Fw satisfy G≦0.25 / H (mm). Furthermore, the incremental forming method described above can further enhance the effect of suppressing tool marks when the machining locus Fw has a regular amplitude H by making the interval G satisfy G≦0.225 / H (mm).

[0032] Furthermore, in the above incremental forming method, the amplitude H of the machining trajectory Fw is a random value equal to or less than Hmax that satisfies 2H≧1.2Ps-R*θ, and by making the interval G of displacement accompanying the amplitude H in the machining trajectory Fw satisfy G≦0.25 / H (mm), it is possible to enhance the effect of suppressing tool marks in the case of a machining trajectory Fw having an irregular amplitude H. Furthermore, in the above incremental forming method, by making the interval G satisfy G≦0.225 / H (mm), it is possible to achieve a further improvement in the effect of suppressing tool marks in the case of a machining trajectory Fw having an irregular amplitude H.

[0033] Second Embodiment 8 is a diagram showing a rod-shaped tool T of a second embodiment of the incremental forming method and incremental forming device according to the present invention. Similar to the device shown in FIG. 1, the incremental forming device includes a clamping device (1) that holds the periphery of a metal plate (W), a rod-shaped tool T arranged on one side of the metal plate (W), and a tool driving device (2) that moves the rod-shaped tool T in three mutually perpendicular axial directions, and the tool driving device (2) holds the rod-shaped tool T rotatably about its axis. The rod-shaped tool T in this embodiment has a wave-shaped protrusion 10 around the entire circumference of its tip that forms a machining locus Fw.

[0034] In the first embodiment described above, the metal plate (W) is shaped while forming a machining path (Fw) having an amplitude (H) by pre-programmed movement of the rod-shaped tool T or by applying vibration to the rod-shaped tool T. In contrast, when the rod-shaped tool T of this embodiment is used, the rod-shaped tool T is pressed against the metal plate (W) and moved while rotating around the axis, whereby the metal plate (W) is shaped while forming a machining path (Fw) with the protrusion 10.

[0035] As with the first embodiment, the incremental forming method and incremental forming apparatus using the above-mentioned rod-shaped tool T can virtually increase the width of the processed portion (processing path) through which the rod-shaped tool T has actually passed, resulting in good appearance quality with inconspicuous tool marks. In particular, the protrusion portion 10 of the rod-shaped tool T can form a processing path with amplitude, which can contribute to simplifying the device structure and further reducing equipment costs and manufacturing costs.

[0036] The structures of the incremental forming method and incremental forming device according to the present invention are not limited to the above-described embodiments, and can be modified as appropriate within the scope of the present invention. [Explanation of symbols]

[0037] Fw Machining trajectory H amplitude T bar tool W Metal plate 1. Clamping device 2 Tool drive unit 4,5 Vibration device 10 Projection part

Claims

1. 1. An incremental forming method for forming a metal plate into a three-dimensional shape by pressing a tip end of a rod-shaped tool against a main surface of a metal plate whose periphery is held and moving the tool, As the rod-shaped tool moves, the metal plate is formed while forming a processing locus that intersects with the moving direction of the rod-shaped tool and has an amplitude in a direction along the forming surface of the metal plate, At this time, the moving path of the rod-shaped tool includes a contoured circular path, The amplitude of the machining trajectory is H (mm), the interval between adjacent circular paths is Ps (mm), the radius of curvature of the tip of the bar-shaped tool is R (mm), and the forming angle, which is the angle between the main surface of the metal plate before forming and the inclined surface after forming, is θ. The amplitude H of the machining path satisfies 2H≧1.2Ps−R*θ, An incremental forming method, characterized in that the interval G of displacement with the amplitude on the processing trajectory satisfies G≦0.25 / H (mm).

2. 1. An incremental forming method for forming a metal plate into a three-dimensional shape by pressing a tip end of a rod-shaped tool against a main surface of a metal plate whose periphery is held and moving the tool, As the rod-shaped tool moves, the metal plate is formed while forming a processing locus that intersects with the moving direction of the rod-shaped tool and has an amplitude in a direction along the forming surface of the metal plate, At this time, the moving path of the rod-shaped tool includes a contoured circular path, The amplitude of the machining trajectory is H (mm), the interval between adjacent circular paths is Ps (mm), the radius of curvature of the tip of the bar-shaped tool is R (mm), and the forming angle, which is the angle between the main surface of the metal plate before forming and the inclined surface after forming, is θ. The amplitude H of the processing trajectory is a random value equal to or less than Hmax that satisfies 2H≧1.2Ps−R*θ, An incremental forming method, characterized in that the interval G of displacement with the amplitude on the processing trajectory satisfies G≦0.25 / H (mm).

3. 3. The incremental forming method according to claim 1, wherein the gap G satisfies G≦0.225 / H (mm).

4. An incremental forming apparatus used in the incremental forming method according to claim 1 or 2, the rod-shaped tool is disposed on one side of the metal plate; a tool driving device is configured to move the rod-shaped tool in three axial directions perpendicular to each other; and a vibration imparting device is configured to impart vibration to at least one of the clamping device and the rod-shaped tool, an incremental forming apparatus for forming the metal plate while forming the processing locus by vibrations applied by the vibration applying device;

5. An incremental forming apparatus used in the incremental forming method according to claim 1 or 2, a clamping device that holds the periphery of the metal plate; the rod-shaped tool that is disposed on one side of the metal plate; and a tool driving device that moves the rod-shaped tool in three axial directions that are perpendicular to one another, An incremental forming apparatus, wherein the tool driving device moves the bar-shaped tool along a movement path that forms the processing locus.

6. An incremental forming apparatus used in the incremental forming method according to claim 1 or 2, a clamping device that holds the periphery of the metal plate; the rod-shaped tool that is disposed on one side of the metal plate; and a tool driving device that moves the rod-shaped tool in three axial directions that are perpendicular to one another, the tool drive device holds the rod-shaped tool so as to be rotatable about its axis, and the rod-shaped tool has a wave-shaped protrusion portion around the entire circumference of its tip portion that forms the machining locus.

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