JP7730465B2 - Incremental forming method and incremental forming device - Google Patents

Description

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.

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 placed on one side of a plate material and a concave pressing member placed on the other side of the plate material. The rod-shaped pressing member has a flexible member at its tip.

The incremental forming method described above presses the flexible member of the rod-shaped pressing member against the plate material while moving the rod-shaped pressing member while tracing contour lines, forcing the plate material to expand within the concave pressing member and forming it into a three-dimensional shape. By using a rod-shaped pressing member with a flexible member, the incremental forming method described above increases the contact area between the rod-shaped pressing member and the plate material, thereby reducing tool marks.

Japanese Patent No. 3777130

However, the conventional incremental forming method described above uses a rod-shaped pressure member equipped with a flexible member that contacts the plate material, making it difficult to achieve sufficient deformation in the plate material. This requires auxiliary equipment such as a concave pressure member, and the rod-shaped pressure member has a short lifespan and therefore needs to be replaced frequently. As a result, while the conventional incremental forming method reduces tool marks on the molded product, it has the disadvantage of making it difficult to reduce equipment and manufacturing costs.

The present invention was made in consideration of the above-mentioned conventional situation, and aims to provide an incremental molding method and incremental molding apparatus that can improve the appearance quality of molded products while reducing equipment costs and manufacturing costs.

The incremental forming method of the present invention is a method for forming a metal plate into a three-dimensional shape by pressing the tip of a rod-shaped tool against the main surface of the metal plate while holding the periphery and moving it. This incremental forming method is characterized by forming the metal plate while, as the rod-shaped tool moves, creating a processing trajectory that has amplitude in a direction that intersects the direction of movement and follows the forming surface of the metal plate.

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 contour-like 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 locus 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).

By adopting the above-mentioned configuration, the incremental molding method and incremental molding apparatus of the present invention eliminate the need for auxiliary equipment such as molding dies, and by using long-life, hard rod-shaped tools, it is possible to reduce equipment costs and manufacturing costs while improving the appearance quality of molded products.

FIG. 2 is an explanatory cross-sectional view showing an enlarged view of a processing trajectory with a regular amplitude in the first embodiment of the incremental forming method and incremental forming device according to the present invention. FIG. 2 is a cross-sectional view showing the main part of incremental forming. FIG. 10 is an explanatory diagram showing a machining locus with irregular amplitude. FIG. 10 is an explanatory diagram showing machining trajectories with regular amplitudes in adjacent circular paths. FIG. 10 is an explanatory diagram showing a machining locus with irregular amplitude in adjacent circular paths. 1 is a graph showing the relationship between amplitude and surface roughness of the molding surface. 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. FIG. 10 is a side view illustrating a rod-shaped tool according to a second embodiment.

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 for holding the periphery of a metal sheet W, a rod-shaped tool T disposed on one main surface side of the metal sheet W (the upper side in FIG. 1), a tool driving device 2 for driving the rod-shaped tool T, and a main control device 3 for controlling the tool driving device 2.

The metal sheet W is a flat plate that is the raw material for the formed product, and in this embodiment, it is held horizontally at its periphery by the clamp 1. The incremental forming method according to the present invention is a dieless forming method that does not use a forming mold. This incremental forming method also makes it possible to hold the metal sheet W vertically or at an angle, and the rod-shaped tool T and clamp device 1 are positioned according to the orientation of the metal sheet W. The clamp device 1 comprises 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.

In the illustrated example, the rod-shaped tool T is held with its axis in the vertical direction, and is a well-known tool with a suitable shape, such as a spherical lower tip, which 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.

The tool driving device 2 can be a multi-axis controlled work robot or an NC machine tool. 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.

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.

Generally, in incremental forming, as shown in Figure 1, a rod-shaped tool T is moved while pressing its tip against a metal sheet W held at its periphery by a clamping device 1. Figure 2 is a cross-sectional view of the rod-shaped tool T viewed 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 a 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 the pitch feed. In this way, the incremental forming method forms the metal sheet W by gradually pressing down the bottom, ultimately obtaining a three-dimensional molded product.

In the incremental forming method of 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.

In this case, in the incremental forming method, it is possible to select a machining trajectory Fw with a regular amplitude relative to the 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 with an irregular amplitude relative to the machining reference line SL, as shown in Figure 3.

The above-mentioned machining trajectory Fw can be formed by inputting a program in advance into the main control device 3 as the movement path of the rod-shaped tool T and controlling the tool driving device 2 with that program. Alternatively, the machining trajectory 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 Figure 1, and imparting vibrations 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.

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

In the incremental forming method described above, when the machining path Fw has a regular amplitude as shown in Figure 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 inclined surface after forming, is θ (shown in Figure 2), and the amplitude H of the machining path Fw satisfies 2H ≥ 1.2Ps - R * θ, and the spacing G of the machining path Fw, which displaces with amplitude H, satisfies G ≤ 0.25/H (mm), and more preferably, the spacing G satisfies G ≤ 0.225/H (mm). The constant 1.2 in the formula for amplitude H was calculated based on the conditions that led to a pass judgment in the test described below.

Furthermore, in the above-mentioned incremental forming method, when the machining trajectory Fw has an irregular amplitude as shown in Figure 5, a preferred embodiment is one in which the movement path of the rod-shaped tool T includes a contour-like circular path, the amplitude of the machining trajectory Fw is H (mm), the spacing between adjacent circular paths is Ps (mm), the radius of curvature of the tip of the rod-shaped tool T is R (mm), and the forming angle, which is the angle between the main surface of the metal plate W before forming and the inclined surface after forming, is θ, the amplitude H of the machining trajectory Fw is a random value less than Hmax that satisfies 2H≧1.2Ps-R*θ, and the interval G of displacement with amplitude H in the machining trajectory Fw satisfies G≦0.25/H (mm), and more preferably, the interval G satisfies G≦0.225/H (mm).

A test was conducted on the above-mentioned incremental forming method. 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 radius of curvature 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 (displacement spacing) G of the displacement accompanying the amplitude H in the processing trajectory Fw was kept constant at 0.5 mm.

Incremental forming was then performed with the amplitude H varied in 100 μm increments between 100 μm and 500 μm, and the surface roughness (arithmetic mean roughness) Ra of the formed surface was measured. The results showed that when incremental forming was performed while forming a processing trajectory Fw, the width of the processed portion became artificially thicker compared to when the rod-shaped tool T was moved linearly, making tool marks less noticeable. In particular, as shown in Figure 6, the surface roughness Ra of the formed surface decreased as the amplitude H increased, demonstrating that tool marks could be significantly suppressed.

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

As a result, as shown in Figure 7, 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). Figure 7 also shows the relationship between the ratio of the amplitude H to the pitch Ps of the circular path and the displacement interval G.

The above test results have shown that the incremental forming method can produce a good formed surface with less visible tool marks by ensuring that the distance G, which displaces with amplitude H in the processing trajectory Fw, satisfies G≦0.25/H (mm), and more preferably G≦0.225/H (mm).

The incremental forming method described in the above embodiment forms the metal sheet W while forming a processing trajectory Fw having an amplitude H in a direction that intersects the direction of movement of the rod-shaped tool T and that is aligned with the forming surface of the metal sheet W as the tool T moves. 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 to reduce equipment costs and manufacturing costs while forming a forming surface on which tool marks are less visible, thereby improving the appearance quality of the formed product.

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 plate W and the rod-shaped tool T. The metal plate W is formed while forming a machining trajectory Fw using 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 machining trajectory Fw to form the metal plate W.

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

Furthermore, the above-mentioned incremental forming method can enhance the effect of suppressing tool marks when a machining trajectory Fw has a regular amplitude H by ensuring that the amplitude H of the machining trajectory Fw satisfies 2H≧1.2Ps-R*θ and that the interval G of displacement accompanying the amplitude H in the machining trajectory Fw satisfies G≦0.25/H (mm).Furthermore, the above-mentioned incremental forming method can further enhance the effect of suppressing tool marks when a machining trajectory Fw has a regular amplitude H by ensuring that the interval G satisfies G≦0.225/H (mm).

Furthermore, the above-mentioned incremental forming method can enhance the effect of suppressing tool marks when a machining trajectory Fw has an irregular amplitude H by ensuring that 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 that the spacing G of the machining trajectory Fw that displaces with the amplitude H satisfies G≦0.25/H (mm).Furthermore, the above-mentioned incremental forming method can further enhance the effect of suppressing tool marks when a machining trajectory Fw has an irregular amplitude H by ensuring that the spacing G satisfies G≦0.225/H (mm).

Second Embodiment
Figure 8 is a diagram showing a rod-shaped tool T of a second embodiment of the incremental forming method and incremental forming apparatus according to the present invention. Similar to the one shown in Figure 1, the incremental forming apparatus 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 processing locus Fw.

In the first embodiment described above, a 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 its axis, thereby forming a machining path (Fw) with the protrusion 10 to shape the metal plate (W).

As with the first embodiment, the incremental forming method and incremental forming apparatus using the above-mentioned rod-shaped tool T virtually widens the width of the processed portion (processing path) through which the rod-shaped tool T has actually passed, resulting in a 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.

The structure of the incremental forming method and incremental forming apparatus of the present invention is not limited to the above-described embodiments, and can be modified as appropriate within the scope of the present invention.

Fw: machining path H: amplitude T: rod-shaped tool W: metal plate 1: clamping device 2: tool driving device 4, 5: vibration imparting device 10: protrusion

Claims (6)

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