Sequential shaping method

Abstract

In this sequential shaping method for shaping a metal plate W into a three-dimensional shape by pressing a rod-shaped tool T against the metal plate W and moving the rod-shaped tool T: the rod-shaped tool T, which is disposed on one side of the metal plate W, and a heating device H1 disposed on the other side of the metal plate W are used; a local range of movement of the rod-shaped tool T on the metal plate W is determined on the basis of a predetermined movement path and movement speed of the rod-shaped tool T; and the local range of movement is heated from a rear side for a certain period of time, and the metal plate W is shaped by means of the rod-shaped tool T, after which the metal plate W is shaped while successively performing heating corresponding to the next local range of movement continuous with the previous local range of movement, thereby heating and annealing a part subjected to plastic deformation by means of the rod-shaped tool T during the shaping step, and eliminating residual stress generated in the metal plate W, thereby increasing a shape-fixability of the shaped product.

Description

Sequential molding method

[0001] The present invention relates to an incremental forming method for forming a metal plate into a three-dimensional shape using a rod-shaped tool, and more particularly to an incremental forming method and an incremental forming apparatus that anneal the formed portion of the metal plate.

[0002] An example of a conventional incremental forming method is described in Patent Document 1. The incremental forming method described in Patent Document 1 uses a rod-shaped tool equipped with a laser irradiator as a heating means. The rod-shaped tool is equipped with the laser irradiator on the front side in the moving direction of the rod-shaped tool. In the incremental forming method, when the rod-shaped tool is pressed against a metal plate and moved, a laser beam is irradiated on the front side of the rod-shaped tool to heat the metal plate, and the heated portion is pressed with the rod-shaped tool to cause plastic deformation, thereby releasing and reducing residual stress in the metal plate.

[0003] Japanese Patent No. 3959455

[0004] In the incremental forming method described above, a rod-shaped tool moves around the contour line multiple times to form a metal plate. In contrast, in conventional incremental forming methods, the rod-shaped tool and the laser irradiator move integrally, making it difficult to ensure a laser beam transmission path from the outside to the laser irradiator in order to constantly irradiate the front side of the rod-shaped tool with laser beam. Furthermore, in conventional incremental forming methods, the part before forming with the rod-shaped tool is heated, which may prevent the removal of residual stress after forming, making it difficult to improve the shape fixability of the formed product. Furthermore, in order to heat the part sufficiently, it is necessary to reduce the moving speed of the rod-shaped tool, but this is not practical because it would significantly reduce productivity.

[0005] The present invention has been made in consideration of the above-mentioned conventional situation, and aims to provide an incremental forming method and an incremental forming apparatus that can anneal the portion of a metal plate that has been plastically deformed by a rod-shaped tool by heating the metal plate from the back side during the forming process, thereby removing residual stress generated in the metal plate and improving the shape fixability of the formed product.

[0006] The incremental forming method according to the present invention forms a metal plate into a three-dimensional shape by pressing and moving a tip of a rod-shaped tool against the metal plate, and uses a rod-shaped tool arranged on one main surface of the metal plate and a heating device arranged on the other main surface of the metal plate for heating the metal plate. The incremental forming method is characterized in that a local movement range of the rod-shaped tool on the metal plate is determined based on a preset movement path and movement speed of the rod-shaped tool, the local movement range is heated from the back side for a certain period of time, and the metal plate is shaped with the rod-shaped tool, and then the metal plate is shaped while heating a next local movement range that is successive to the previous local movement range along the movement path of the rod-shaped tool.

[0007] The incremental forming apparatus according to the present invention is an incremental forming apparatus used in the incremental forming method described above. The incremental forming apparatus includes a bar-shaped tool arranged on one main surface of a metal plate, a heating device arranged on the other main surface of the metal plate, a tool driving device that drives the bar-shaped tool in at least three orthogonal axial directions, and a main control device that controls the tool driving device. The incremental forming apparatus is characterized in that the heating device is capable of individually heating, from the back side, a plurality of local movement ranges that divide the movement path of the bar-shaped tool, and the main control device has a function of controlling the heating device based on drive data for the bar-shaped tool.

[0008] By adopting the above-described configuration, the incremental forming method and incremental forming apparatus of the present invention can heat the metal plate from the back side during the forming process, thereby annealing the area that has been plastically deformed by the rod-shaped tool, removing residual stress that occurs in the metal plate, and improving the shape fixability of the formed product.

[0009] 6 is an explanatory diagram showing an example of an incremental forming apparatus applicable to the incremental forming method according to a first embodiment of the present invention; FIG. 7 is a plan view showing the relationship between the movement path of a bar-shaped tool on a metal plate and the heating range by a heating device; FIG. 8 is a side view showing the projected range of a bar-shaped tool on a metal plate; FIG. 9 is a graph showing the relationship between time and temperature when heating a metal plate; FIG. 10 is an explanatory diagram showing another example of a heating device in a second embodiment of the incremental forming method according to the present invention; FIG. 11 is a plan view showing yet another example of a heating device in a third embodiment of the incremental forming method according to the present invention; FIG. 12 is a side view of the heating device shown in FIG. 6; FIG. 13 is a perspective view of the nozzle shown in FIG. 10; FIG. 14 is a plan view showing yet another example of a heating device in a fourth embodiment of the incremental forming method according to the present invention; FIG. 15 is a side view of the heating device shown in FIG. 16; FIG. 17 is a perspective view of the nozzle shown in FIG. 17;

[0010] 1 is a diagram showing an example of an incremental forming apparatus applicable to an incremental forming method according to a first embodiment of the present invention. The illustrated incremental forming apparatus includes a rod-shaped tool T disposed on one main surface side (the upper surface side in the figure) of a metal sheet W, and a heating device H1 disposed on the other main surface side (the lower surface side in the figure) of the metal sheet W.

[0011] The incremental forming apparatus also includes a tool driving device 1 that drives the rod-shaped tool T in at least three orthogonal axial directions, and a main control device 2 that controls the tool driving device 1. The heating device H1 can individually heat a plurality of local movement ranges that divide the movement path of the rod-shaped tool T from the back side of the respective local movement ranges. The main control device 2 has a function of controlling the heating device H1 based on drive data for the rod-shaped tool T.

[0012] The metal sheet W is a flat plate that is the raw material for a molded product. During incremental molding, the periphery of this metal sheet W is held by a clamp 3. The clamp 3 includes a fixed lower frame portion 3A and an upper frame portion 3B that can be raised and lowered relative to the lower frame portion 3A, and the periphery of the metal sheet W is firmly clamped between the lower frame portion 3A and the upper frame portion 3B.

[0013] In the illustrated example, the rod-shaped tool T is held with its axis oriented vertically, and its lower tip is a well-known type having an appropriate shape such as a spherical surface, and is driven in three orthogonal axial directions by the tool driving device 1. A multi-axis control work robot or an NC machine tool can be used as the tool driving device 1. The tool driving device 1 can move the attached rod-shaped tool T in the horizontal X and Y directions and the vertical Z direction. It is also possible to rotate the rod-shaped tool T about each axis.

[0014] The heating device H1 is preferably a device that heats the metal plate W in a non-contact manner. The heating device H1 in this embodiment is a device that heats the metal plate W by irradiating it with laser light L. That is, the heating device H1 includes a laser oscillator 11, a laser scanner 12 that scans the metal plate W with the laser light L, and an optical fiber 13 that transmits the laser light from the laser oscillator 11 to the laser scanner 12.

[0015] The laser scanner 12 can scan the laser light L at high speed within an arbitrarily set range on the other main surface (lower surface) of the metal plate W. This allows the heating device H to individually heat the arbitrarily set range, i.e., a plurality of local movement ranges obtained by dividing the movement path of the rod-shaped tool T, from the back side thereof.

[0016] The main control device 2 is a computer, and all the movement paths from the forming start point to the forming end point, the movement speed, the amount of pressure applied to the metal plate W, etc. are input in advance as drive data for the rod-shaped tool T for forming the metal plate W into a formed product.

[0017] The main control device 2 has a function of controlling the heating device H1 based on the drive data of the rod-shaped tool T. Specifically, the main control device 2 determines a local movement range of the rod-shaped tool T on the metal plate W based on the movement path and movement speed of the rod-shaped tool T, and mainly controls the laser scanner 12 so that the back side of this local movement range is scanned with laser light L to heat it for a certain period of time.

[0018] Next, the incremental forming method will be described along with the operation of the incremental forming apparatus. In the well-known incremental forming method, as shown in FIG. 1 , a rod-shaped tool T is moved while pressing its tip against a metal sheet W whose periphery is held by clamps 3. Specifically, after moving the rod-shaped tool T along a circular path, the rod-shaped tool T is displaced inward and downward by a predetermined pitch (pitch feed), and the movement along the next circular path and pitch feed operation are repeated. In this way, the incremental forming method moves the rod-shaped tool T along a contour line, gradually pressing down the bottom of the metal sheet W, and finally obtains a formed product with a three-dimensional shape.

[0019] In the incremental forming method according to the present invention, when incremental forming is performed as described above, a local movement range of the rod-shaped tool T on the metal sheet W is determined based on a preset movement path and movement speed of the rod-shaped tool T, and the local movement range is heated from the back side for a certain period of time while the metal sheet W is formed by the rod-shaped tool T. Then, in the incremental forming method, the metal sheet W is formed while sequentially performing heating corresponding to the next local movement range that is successive to the previous local movement range.

[0020] In the incremental forming method of this embodiment, as shown in Figure 2, a circular path P of one circumference indicated by a solid line is determined as the local movement range of a rod-shaped tool T on a metal sheet W, and the local movement range is heated from the back side for a certain period of time as indicated by a dotted line A in Figure 2. That is, based on the drive data of the rod-shaped tool T in the main control device 2, the laser scanner 12 is controlled so as to scan a laser beam L on the back side of the local movement range and heat it for a certain period of time, as shown in Figure 1. The laser beam L is repeatedly scanned in one direction at high speed. Note that the scanning speed of the laser beam L is clearly faster than the movement speed of the rod-shaped tool T.

[0021] In this case, in a more preferred embodiment of the incremental forming method, when the local movement range of the rod-shaped tool T on the metal sheet W is heated from the back side for a certain period of time, heating is started from the projected range in the axial direction of the rod-shaped tool T, as shown in Fig. 3. In addition, when the thickness of the metal sheet W is t (mm), the heating time of the metal sheet W is set to 2.4 x t (minutes) or more.

[0022] Here, in incremental forming using the incremental forming device, for example, it is possible to heat the area on the metal sheet W that has been plastically deformed by the rod-shaped tool T from the back side for a certain period of time when the rod-shaped tool T has been moved a certain distance. In contrast, in the incremental forming method described above, the local movement range is determined, heating is started from the projected range in the axial direction of the rod-shaped tool T, and the metal sheet W is formed by the rod-shaped tool T.

[0023] As a result, in the above-mentioned incremental forming method, preheating is performed from the back side of the unformed area that the rod-shaped tool T has not passed through, and since the rod-shaped tool T continues to move during this time, as a result, heating is performed for a certain period of time from the back side of all areas that have been plastically deformed by the rod-shaped tool T.

[0024] In the incremental forming method of this embodiment, a heating device H1 is used that repeatedly scans the laser light L in one direction, so the temperature fluctuates up and down as shown by the dotted line in Figure 4. However, as long as the temperature fluctuation range exceeds the target temperature as shown, sufficient annealing is possible.

[0025] The heating time of the metal sheet W was set to 2.4 x t (minutes) or more based on the standard in the heat treatment industry that the heating holding time required for annealing is one hour per inch of sheet thickness, with the sheet thickness converted to millimeters. Furthermore, an experiment was conducted in which a steel sheet was heated to 510°C by electromagnetic induction heating and the heating time was changed in one-minute increments from one minute to eight minutes. As a result, it was found that a heating time of 2.4 x t (minutes) or more is desirable.

[0026] Furthermore, in the above-mentioned incremental forming method, depending on the amount of pitch feed of the rod-shaped tool T and the size of the spot diameter of the laser light L, it is possible to perform heating, including preheating, not only on the back side of the area that has been plastically deformed by the rod-shaped tool T, but also on the surrounding area, i.e., the unformed area, which is the next circular path or pitch feed path.

[0027] As described above, in the incremental forming method, the rod-shaped tool T is moved to the forming end point while sequentially performing heating corresponding to the next local movement range (e.g., the next circular path) that is continuous with the previous local movement range, to form the metal sheet W. At this time, in the incremental forming method, if the heating for the previous local movement range has not exceeded a certain time, the scanning range of the laser light L is expanded by adding the next local movement range to the previous local movement range, and when the heating for the previous local movement range has exceeded the certain time, the scanning range of the laser light L is set to the next local movement range. This ends the heating for the previous local movement range.

[0028] In this way, the incremental forming method and incremental forming apparatus described in the above embodiment heat the metal plate from the back side during the forming process to anneal the area that has been plastically deformed by the rod-shaped tool, remove residual stress generated in the metal plate, and improve the shape fixability of the formed product. Furthermore, in the above incremental forming method and incremental forming apparatus, the rod-shaped tool T and the heating device are arranged with the metal plate W between them, so there is no need to worry about the free movement of the rod-shaped tool T being hindered.

[0029] Furthermore, in the incremental forming method described above, heating is started from the projected range in the axial direction of the rod-shaped tool T, and the metal sheet W is formed by the rod-shaped tool T, so preheating can be performed from the back side of the unformed range that has not been passed by the rod-shaped tool T. This allows the plastically deformed range of the metal sheet W to be efficiently heated and annealed, and residual stress can be sufficiently removed, contributing to improved shape fixability.

[0030] Furthermore, in the above-mentioned incremental forming method, by setting the heating time of the metal plate W to 2.4 x t (minutes) or more, the plastically deformed area of ​​the metal plate W can be efficiently heated and annealed, which can contribute to sufficient removal of residual stress and further improvement of shape fixability.

[0031] Furthermore, in the incremental forming method, the metal sheet W is formed while being held around its periphery by the clamps 3, so that the metal sheet W can be incrementally formed by a relatively simple device without using a forming die, etc. In the incremental forming method, the shape fixability of the formed product is well maintained, so that the formed product can be easily removed from the clamps 3.

[0032] Furthermore, in the incremental forming method, the heating device H1 is a device that heats the metal sheet W in a non-contact manner, and in particular, a device that heats the metal sheet W by irradiating it with laser light L, so that the scanning range of the laser light L can be freely set based on the drive data of the rod-shaped tool T, and the required range can be heated in a concentrated manner. Also, in the incremental forming method, the metal sheet W is formed so that it protrudes downward, but it is possible to heat the metal sheet W without changing the height position of the laser scanner 12.

[0033] 5 to 11 are diagrams illustrating an incremental forming apparatus applicable to the incremental forming method according to second to fourth embodiments of the present invention. In the following embodiments, components equivalent to those in the first embodiment are designated by the same reference numerals, and detailed descriptions thereof will be omitted.

[0034] Second Embodiment The incremental forming method according to the present invention uses, as the heating device H2, a device that heats the metal sheet W in a non-contact manner. In the incremental forming apparatus shown in Fig. 5, the heating device H2 is an electromagnetic induction heating device, and although not shown in detail, has a structure in which a plurality of individually operable heating units are arranged on a surface (upper surface in the drawing) facing the other main surface of the metal sheet W, and is capable of locally heating the metal sheet W.

[0035] In the incremental forming method, the bottom of the metal sheet W is gradually pressed down to form it. In contrast, the heating device H2 can be made movable up and down to maintain a constant distance from the bottom of the metal sheet W, depending on the amount of forming of the metal sheet W. Note that the heating device H2 can have an uneven upper surface shape that matches the formed shape of the metal sheet W, and a heating unit can be arranged on the upper surface of the heating device H2, but if multiple heating units are arranged on the same plane and the entire device is configured to move up and down, it can accommodate a variety of formed shapes.

[0036] As in the previous embodiment, the incremental forming method using the incremental forming apparatus determines the local movement range of the rod-shaped tool T on the metal plate W based on the predetermined movement path and movement speed of the rod-shaped tool T, heats the local movement range from the back side for a certain period of time, and forms the metal plate W using the rod-shaped tool T. Thereafter, the metal plate W is formed by sequentially heating the next local movement range that is successive to the previous local movement range.

[0037] At this time, the heating device H2 activates the heating section corresponding to the rear side of the local movement range of the rod-shaped tool T to heat the local movement range from the rear side, and sequentially starts and stops the operation of the corresponding heating section as the local movement range is updated.

[0038] As a result, the above-mentioned incremental forming method and incremental forming apparatus heat the metal plate W from the back side during the forming process, thereby annealing the area that has been plastically deformed by the rod-shaped tool T, removing residual stress that occurs in the metal plate W, and improving the shape fixability of the formed product.

[0039] 6 to 8 are diagrams illustrating yet another example of an incremental forming apparatus applicable to the incremental forming method according to a third embodiment of the present invention. The incremental forming apparatus shown in Fig. 6 has a structure in which a heating device H3 has multiple heaters 14 arranged on the other main surface side of the metal sheet W. As shown in Figs. 7 and 8, the heater 14 has a nozzle 17 at the tip of a pipe 16 with a heater 15 in the middle, which sprays hot air heated by the heater 15.

[0040] In the incremental forming method, as described in the previous embodiment, the rod-shaped tool (T) is moved along a circular path, and then the rod-shaped tool is displaced inward and downward and moved along the next circular path. In other words, in the incremental forming method, the rod-shaped tool is moved along the contours of the metal sheet W, gradually pressing down the bottom of the metal sheet W to form it.

[0041] In contrast, the heating device H3 shown in the figure has a heater 14 with a square-shaped nozzle 17 in the center, and four heaters 14 with slit-shaped nozzles 17 arranged around it, with the nozzles 17 arranged to form the four sides of a rectangle. The heating device H3 also has four heaters 14 as a group, and the nozzles 17 of the multiple groups of heaters 14 are arranged in a contour line. Therefore, each heater 14 has nozzles 17 with longer slits toward the outside.

[0042] In the incremental forming method using the incremental forming device having the above-mentioned heating device H3, as in the previous embodiment, the local movement range of the rod-shaped tool on the metal plate W is determined, and in the heating device H3, the heater 14 corresponding to the back side of the local movement range of the rod-shaped tool T is activated to supply hot air to the back side of the local movement range to heat it, and the corresponding heater 14 is sequentially started and stopped as the local movement range is updated.

[0043] As a result, the above-mentioned incremental forming method and incremental forming apparatus heat the metal plate W from the back side during the forming process, thereby annealing the area that has been plastically deformed by the rod-shaped tool, removing residual stress that occurs in the metal plate W, and improving the shape fixability of the formed product.

[0044] In addition, the heating device H3 in the incremental forming apparatus of the above embodiment may be structured so that the height of each heater 14 is changed to match the forming shape of the metal plate W, or each heater 14 may be able to move up and down individually, or all heaters 14 may be able to move up and down simultaneously.

[0045] 9 to 11 are diagrams illustrating yet another example of an incremental forming apparatus applicable to the incremental forming method according to a fourth embodiment of the present invention. The incremental forming apparatus shown in Fig. 9 has a structure in which a heating device H4 has a number of heaters 14 arranged vertically and horizontally on the other main surface side of a metal sheet W. As shown in Figs. 10 and 11, each heater 14 has a square nozzle 17 at the tip of a pipe 16 with a heater 15 in the middle, which sprays hot air heated by the heater 15, and these nozzles 17 are arranged in a vertical and horizontal array.

[0046] In the incremental forming method using the incremental forming device having the above-mentioned heating device H4, as in the previous embodiment, the local movement range of the rod-shaped tool on the metal plate W is determined, and in the heating device H4, the heater 14 corresponding to the back side of the local movement range of the rod-shaped tool T is activated to heat the local movement range from the back side with hot air, and the corresponding heater 14 is started and stopped sequentially as the local movement range is updated.

[0047] As a result, the above-mentioned incremental forming method and incremental forming apparatus heat the metal plate W from the back side during the forming process, thereby annealing the area that has been plastically deformed by the rod-shaped tool, removing residual stress that occurs in the metal plate W, and improving the shape fixability of the formed product.

[0048] In addition, the heating device H4 in the incremental forming apparatus of the above embodiment may be structured so that the height of each heater 14 is changed to match the forming shape of the metal plate W, or each heater 14 may be able to move up and down individually, or all heaters 14 may be able to move up and down simultaneously.

[0049] Furthermore, in the second embodiment (see FIG. 5) described above, the detailed structure of the heating section of the heating device H2 is not shown, but an electromagnetic induction heating section can be arranged in place of the nozzle 17 shown in FIGS. 6 and 8.

[0050] The structures of the incremental forming method and incremental forming apparatus according to the present invention are not limited to the above-described embodiments, and can be appropriately modified within the scope of the present invention. In each embodiment, the metal sheet W is held horizontally, but in incremental forming (dieless forming) that does not use a forming die, the metal sheet W can also be held vertically or inclined.

[0051] 1 Tool driving device 2 Main control device H1 to H4 Heating device T Rod-shaped tool W Metal plate

Claims

1. 1. An incremental forming method for forming a metal plate into a three-dimensional shape by pressing and moving a tip of a rod-shaped tool against the metal plate, comprising: using the rod-shaped tool arranged on one main surface side of the metal plate and a heating device arranged on the other main surface side of the metal plate to heat the metal plate, a local movement range of the rod-shaped tool on the metal plate is determined based on a preset movement path and movement speed of the rod-shaped tool, and a heating time of the metal plate is determined based on a thickness of the metal plate, and the entire local movement range is heated from the back side for the heating time while the metal plate is shaped by the rod-shaped tool; Thereafter, the metal plate is formed while successively performing heating corresponding to the entire area of ​​the next local movement range that is continuous with the previous local movement range.

2. The sequential forming method according to claim 1, characterized in that when the entire area of ​​the local movement range of the rod-shaped tool on the metal plate is heated from the back side for the heating time, heating is started from the axial projection range of the rod-shaped tool.

3. When the thickness of the metal plate is t (mm), The incremental forming method according to claim 1, characterized in that the heating time of the metal plate is 2.4 × t (min) or more.

4. The incremental forming method according to claim 1, wherein the metal plate is formed while holding a periphery thereof.

5. The incremental forming method according to claim 1 , wherein the heating device is a device for heating the metal plate in a non-contact manner.

6. 6. The incremental forming method according to claim 5, wherein the heating device is a device that heats the metal plate by irradiating it with a laser beam.

7. 6. The incremental forming method according to claim 5, wherein the heating device is a device for heating the metal plate by blowing hot air onto the metal plate.

8. An incremental forming apparatus for use in the incremental forming method according to claim 1, The rod-shaped tool is disposed on one main surface side of the metal plate; The heating device is disposed on the other main surface side of the metal plate; A tool driving device that drives the rod-shaped tool in at least three axial directions perpendicular to each other; A main control device that controls the tool driving device, the heating device is capable of individually heating a plurality of local movement ranges obtained by dividing a movement path of the bar-shaped tool from the rear side thereof; An incremental forming apparatus characterized in that the main control device has a function of controlling the heating device based on drive data of the bar-shaped tool, and a function of determining a heating time of the metal plate based on a thickness of the metal plate.