Sequential molding method and sequential molding device

Abstract

In the present invention, a sub-drive device 1 for driving a tool T in a direction parallel to a metal plate W, and a main drive device 2 for driving the sub-drive device 1 in three orthogonal axial directions are used. According to the present invention: a target trajectory P1 corresponding to the shape of the molding portion on the metal plate W is set; an entire movable range A of the tool T by the sub-drive device 1 is set on the basis of the target trajectory P1; within the entire movable range A, a basic trajectory P2 of the sub-drive device 1 by the main drive device 2 is set in a simple shape; and while the sub-drive device 1 is driven along the basic trajectory P2 by the main drive device 2, the tool T is driven along the target trajectory P1 by the sub-drive device 1, which has less mass than the main drive device 2. This enables the shortening of the molding time, even when the target trajectory P1 has a complex shape.

Description

Incremental forming method and incremental forming device

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

[0002] An example of a conventional incremental forming method is described in Patent Document 1. Patent Document 1 describes an incremental forming apparatus in which a pressing tool is attached to the hand of an articulated robot. The pressing tool includes a rod-shaped first pressing tool and a second pressing tool having a roller, which can be moved toward and away from each other. In this incremental forming method using the incremental forming apparatus, the articulated robot operates to press and move the first pressing tool of the pressing tool against a plate material, thereby forming the plate material into a three-dimensional shape, and during this process, the second pressing tool suppresses warping of the plate material.

[0003] Japanese Patent No. 5381075

[0004] In the conventional incremental forming method described above, a numerically controlled processing machine such as an articulated robot is used, and in the teaching process, the tool trajectory is specified by inputting set points through which the tool will pass. The processing machine decelerates before passing each set point, and sometimes stops temporarily, repeating this process, so that the tool passes accurately through each set point. For this reason, in the conventional incremental forming method, the processing machine speed is determined by the number of set points rather than the length of the trajectory, and as the shape of the formed part becomes more complex, the number of set points increases, resulting in a correspondingly longer forming time. It was therefore an issue to solve this problem.

[0005] The present invention has been made in response to the above-mentioned conventional problems, and aims to provide an incremental forming method and an incremental forming apparatus that can shorten the forming time even when the formed part has a complex shape.

[0006] The incremental forming method according to the present invention gradually deforms a metal plate in the thickness direction by pressing and moving the tip of a tool against the metal plate to form a three-dimensional shape. This incremental forming method uses a sub-drive unit that drives the tool in a direction parallel to the metal plate and a main drive unit that drives the sub-drive unit in three orthogonal axial directions. The incremental forming method sets a target trajectory corresponding to the shape of the forming portion of the metal plate, sets a total range of movement of the tool by the sub-drive unit based on the target trajectory, and sets a basic trajectory of the sub-drive unit by the main drive unit within the total range of movement. The incremental forming method is characterized in that the main drive unit drives the sub-drive unit along the basic trajectory, while the sub-drive unit drives the tool along the target trajectory.

[0007] The incremental forming apparatus according to the present invention is an apparatus used in the incremental forming method described above, and includes an auxiliary drive unit that drives a tool in a direction parallel to the metal plate, a main drive unit that drives the auxiliary drive unit in three orthogonal axial directions, and a control unit that controls the auxiliary drive unit and the main drive unit. The incremental forming apparatus is characterized in that the control unit has a function of setting a target trajectory corresponding to the shape of a forming portion in the metal plate, a function of setting an entire movable range of the tool by the auxiliary drive unit based on the target trajectory, a function of setting a basic trajectory of the auxiliary drive unit by the main drive unit within the entire movable range, and a function of driving the tool along the target trajectory by the auxiliary drive unit while driving the auxiliary drive unit along the basic trajectory by the main drive unit.

[0008] In the incremental forming method and the incremental forming apparatus, the main drive unit can be a processing machine such as an articulated work robot or a numerically controlled machine tool, and the auxiliary drive unit attached to the main drive unit handles the main drive unit. Therefore, the auxiliary drive unit can be significantly smaller in mass and more responsive than the main drive unit.

[0009] By adopting the above-described configuration, the incremental forming method and incremental forming device according to the present invention can simplify the basic trajectory, even if the shape of the forming portion in the metal plate, i.e., the target trajectory, is complex, because the basic trajectory of the sub-drive device is set by the main drive device within the entire movable range of the tool based on the target trajectory. In other words, it is sufficient to input a basic trajectory with a simple shape that passes through few set points to the main drive device.

[0010] In the incremental forming method and incremental forming device, the tool is pressed against the metal plate, and the main drive device moves the sub-drive device along a basic trajectory having a simple shape, while the sub-drive device moves the tool according to the difference between the basic trajectory and the target trajectory. As a result, the tool moves along the target trajectory, and then the tool is moved in a circular motion along the contour lines, gradually pressing down the bottom to form a concave formed portion.

[0011] In this way, the incremental forming method and incremental forming device use the main drive device to move the secondary drive device along a basic trajectory with a simple shape, and the secondary drive device, which has a small mass and high responsiveness, to move the tool along the target trajectory, thereby making it possible to shorten the forming time even if the formed portion of the metal plate has a complex shape.

[0012] 7 is a side view (left) showing a main part of an incremental forming device and a bottom view (right) of a drive sub-device in a first embodiment of the incremental forming method according to the present invention. FIG. 8 is an explanatory plan view showing a target trajectory, a movable range of the drive sub-device, and a basic trajectory. FIG. 9 is an explanatory plan view showing the operation of a tool on the basic trajectory. FIG. 10 is an explanatory plan view (left) showing set points when the tool is driven by only the processing machine, and a graph (right) showing the relationship between the number of set points and processing time. FIG. 11 is an explanatory plan view showing the movable range of the drive sub-device and an elliptical basic trajectory. FIG. 12 is an explanatory side view showing a second embodiment of the incremental forming method according to the present invention. FIG. 13 is a perspective view showing a state in which a target trajectory is projected onto a metal plate in a third embodiment of the incremental forming method according to the present invention. FIG. 14 is an explanatory view showing an incremental forming device that uses the target trajectory shown in FIG.

[0013] 1 is an explanatory diagram showing the main parts of an incremental forming apparatus applicable to the incremental forming method according to the present invention. The incremental forming apparatus shown on the left side of the figure includes a sub-drive unit 1 that drives a tool T in a direction parallel to a metal plate (not shown), a main drive unit 2 that drives the sub-drive unit 1 in three orthogonal axial directions, and a control unit 3 that controls the sub-drive unit 1 and the main drive unit 2.

[0014] The metal plate (not shown) is set horizontally under the drive sub-unit 1 with its periphery restrained by clamps. The tool T is rod-shaped with an appropriately shaped tip, and is held by the drive sub-unit 1 with the tip pointing downward.

[0015] 1, the drive sub-unit 1 includes a rectangular frame 1A, a beam 1B held by the frame 1A so as to be able to reciprocate in the X direction, and a slider 1C held by the beam 1B so as to be able to reciprocate in the Y direction, with a tool T fixed to the slider 1C. This allows the drive sub-unit 1 to drive the tool T in two horizontal axial directions (X and Y directions).

[0016] The main drive unit 2 is a numerically controlled processing machine, and can be an articulated work robot or machine tool. For example, the sub-drive unit 1 is attached to the hand of the work robot. This drives the sub-drive unit 1 in three orthogonal axial directions (X, Y, and Z directions). The main drive unit 2 may also be configured to rotate the sub-drive unit 1 around the three orthogonal axes.

[0017] In the incremental molding apparatus equipped with the above-mentioned sub-drive unit 1 and main drive unit 2, the mass of the sub-drive unit 1 is significantly smaller than that of the main drive unit 2, so it is possible to use a sub-drive unit 1 with high operational responsiveness.

[0018] The control device 3 is a computer, and it is possible to use one that is installed in the main drive device 2, for example, but in the illustrated example, in order to simplify control, the secondary drive device 1 and the main control device 2 are controlled individually.

[0019] In order to execute the incremental forming method described below, the control device 3 has the functions of setting a target trajectory corresponding to the shape of the forming portion in the metal plate, setting a movable range of the tool T by the sub-drive unit 1 based on the target trajectory, setting a basic trajectory of the sub-drive unit 1 by the main drive unit 2 within the movable range, and driving the tool T along the target trajectory by the sub-drive unit 1 while driving the sub-drive unit 1 along the basic trajectory by the main drive unit 2.

[0020] The operation of the incremental forming apparatus and the incremental forming method will be described below. That is, in the incremental forming method, a target trajectory P1 corresponding to the shape of the forming portion of the metal plate is set, as shown in Figure 2. In the illustrated example, the forming portion is the engine hood of an automobile, with the upper side being the front side of the vehicle body. Therefore, the target trajectory P1 is a trajectory that follows the contour of the forming portion (engine hood).

[0021] Next, in the incremental forming method, the total movable range A of the tool T by the drive sub-unit 2 is set based on the target trajectory P1 (the range of the matte finish). At this time, the movable range of the tool T by the drive sub-unit 2 is the range in the X and Y directions parallel to the metal plate, as shown at four points in Figure 2, so the total movable range A based on the target trajectory P is the entire area when the center of the drive sub-unit 1 is moved along the target trajectory P1, and has a certain width on both sides of the target trajectory P1.

[0022] Then, in the incremental forming method, a basic trajectory P2 of the sub-drive unit 2 is set by the main drive unit 2 within the entire movable range A. The basic trajectory P2 can have a simpler shape than the target trajectory P1, which has a complex shape. In the illustrated example, the basic trajectory P2 is rectangular with curvature (curves) at the corners.

[0023] In this case, in order to move the center of the secondary drive unit 1 along the basic trajectory P2, the main drive unit 2 sets set points (coordinates) PP to be passed on the basic trajectory P2, but because the basic trajectory P2 has a simple shape, the number of set points PP can be significantly reduced. In the illustrated example, two set points PP are set at each of the four corners of the basic trajectory P2, for a total of eight set points PP, and these set points PP are input into the control of the main drive unit 2.

[0024] In the incremental forming method, the tool T is pressed against the metal plate, and the main drive unit 1 moves the sub-drive unit 2 along a basic trajectory P2, which has a simple shape, while the sub-drive unit 1 moves the tool T in accordance with the difference and direction between the basic trajectory P2 and the target trajectory P1, as shown in Fig. 3. At this time, the incremental forming apparatus uses the main drive unit 2 to hold and move the sub-drive unit 1 in a fixed orientation, and the sub-drive unit 1 moves the tool T in the X and Y directions.

[0025] As a result, the tool T moves along the target trajectory P1 while contacting the metal plate, and then moves in a contoured circle to gradually press down the bottom, thereby forming a concave portion. Therefore, the target trajectory P1 and the basic trajectory P2 become smaller each time the tool T makes a circle, but the control for moving the tool T based on the difference between the two remains the same.

[0026] Here, in the case of incrementally forming an engine hood by directly attaching a tool to a processing machine, as in the past, it is necessary to set a large number of set points PP in order to move the tool accurately, because the target trajectory P1 corresponding to the shape of the engine hood is a complex shape that includes curves, as shown on the left side of Figure 4. The right side of Figure 4 is a graph showing the relationship between the number of set points PP and the processing time, and it can be seen that the more set points PP there are, the longer the processing time.

[0027] In contrast, in the incremental forming method and incremental forming apparatus described in the above embodiment, the number of set points PP on the basic trajectory P2 is significantly reduced, so the movement speed of the auxiliary drive unit 1 by the main drive unit 2 can be increased accordingly. Furthermore, the auxiliary drive unit 1 has a smaller mass and higher responsiveness than the main drive unit 2, so it can drive the tool T at high speed so as to follow the target trajectory P1 while moving at high speed. As a result, the above incremental forming method and incremental forming apparatus can shorten the forming time even if the formed portion of the metal plate has a complex shape.

[0028] Furthermore, the above-mentioned incremental forming method and incremental forming apparatus adopt a rectangular shape with curvature at the corners as the shape of the basic trajectory P2, which makes it easy to control the main drive unit 1 and allows continuous forming without having to stop the secondary drive unit 2 at the corners, thereby contributing to further shortening the forming time.

[0029] 5 to 8 are diagrams illustrating second to fourth embodiments of the incremental forming method and incremental forming apparatus according to the present invention. In the following embodiments, the same components as those in the first embodiment are designated by the same reference numerals, and detailed descriptions thereof will be omitted.

[0030] 5 is a diagram showing a second embodiment of the incremental forming method according to the present invention, in which an elliptical basic trajectory P2 is set within the entire movable range A of the sub-drive unit 1 based on the target trajectory P1. In this case, the set points PP input to the main drive unit 2 are set at a total of four locations, for example, on both sides of the minor axis and both sides of the major axis.

[0031] In the above-described incremental forming method, the main drive unit 2 causes the center of the sub-drive unit 1 to move along an elliptical basic orbit P2, and the sub-drive unit 2 drives the tool T in the X and Y directions based on the difference and direction between the target orbit P1 and the basic orbit P2, thereby moving the tool T along the target orbit P1, and as in the first embodiment, the tool T is moved in a circular motion along the contour lines to form the formed portion.

[0032] In the incremental forming method of the above embodiment, the number of set points PP on the basic trajectory P2 is further reduced compared to the first embodiment, and therefore, the forming time can be further shortened. Note that the shape of the basic trajectory P2 can be a rectangle, an ellipse, a circle, a polygon with curvature at the corners, or the like, and in any case, the forming time can be shortened.

[0033] 6 uses an imaging device 4 that captures an image of a forming portion of a metal plate. In this case, the incremental forming apparatus includes the imaging device 4, and the control device (3) has a function of controlling the driving sub-unit (1) based on the difference between the target trajectory P1 and the actual forming portion captured by the imaging device 4. The imaging device 4 is, for example, a camera, and is attached to the frame 1A of the driving sub-unit 1. In this case, the control device (3) has functions of image recognition and image processing.

[0034] In the above-described incremental forming method, a difference α1 between the target trajectory P1 and the forming portion F imaged by the imaging device 4 is detected, and a correction amount β1 for the next circular path of the tool T is calculated based on the difference α1, and the tool (T) is driven by the auxiliary driving device (1) based on the correction amount β1.

[0035] According to the incremental forming method and incremental forming device described above, it is possible to obtain the same effects as in the first embodiment, and in addition, it is possible to detect deviations in the shape of the actual formed part during forming and perform feedback control of the secondary drive unit (1), thereby achieving improved shape accuracy.

[0036] 7 and 8 are diagrams showing a fourth embodiment of the incremental forming method and incremental forming device according to the present invention, and the incremental forming method of this embodiment uses the above-mentioned imaging device 4 and a projection device 5 that projects a target trajectory P1 onto the metal sheet W. In this case, the incremental forming device is equipped with the above-mentioned imaging device 4 and projection device 5, and the control device (3) has a function of controlling the drive sub-device (1) based on the difference between the target trajectory P1 imaged by the imaging device 4 and the actual formed portion.

[0037] 7, in the incremental forming method, a target trajectory P1 corresponding to the shape of the formed portion is projected onto the metal plate W by a projection device 5. As this projection device 5, for example, a device that scans with laser light can be used.

[0038] In the incremental forming method and incremental forming apparatus described above, as shown in FIG. 8, the target trajectory P1 is imaged by an imaging device 4 attached to the sub-drive unit 1, and the difference α2 between the center C of the sub-drive unit 1 and the target trajectory P1 is detected, and the position of the tool T on the sub-drive unit 1 is feedback-controlled, thereby moving the tool T along the target trajectory P1.

[0039] According to the incremental forming method and incremental forming device described above, it is possible to obtain the same effects as those of the first embodiment, and in addition, it is not necessary to actually draw the target trajectory P1, and it is possible to change the drawing content for each forming stage in which the tool T is moved along the contour line. This makes it possible to further simplify the feedback control of the driving sub-unit (1) and contribute to further improvement of the shape accuracy.

[0040] The configurations 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 modified as appropriate within the scope of the present invention.

[0041] REFERENCE SIGNS LIST 1 Auxiliary drive unit 2 Main drive unit 3 Control unit 4 Imaging device 5 Projection device A Total movable range P1 Target trajectory P2 Basic trajectory T Tool W Metal plate

Claims

1. An incremental forming method in which a metal plate is gradually deformed in the thickness direction by pressing and moving the tip of a tool against the metal plate to form a three-dimensional shape, the incremental forming method comprising the steps of: using a sub-drive unit that drives the tool in a direction parallel to the metal plate; and a main drive unit that drives the sub-drive unit in three orthogonal axial directions; setting a target trajectory corresponding to the shape of the forming portion of the metal plate; setting a total range of movement of the tool by the sub-drive unit based on the target trajectory; setting a basic trajectory of the sub-drive unit by the main drive unit within the total range of movement; and driving the sub-drive unit along the basic trajectory by the main drive unit while driving the tool along the target trajectory by the sub-drive unit.

2. The incremental forming method according to claim 1, characterized in that the basic trajectory is any one of a circle, an ellipse, and a polygon having curvature at the corners that fits within the entire movable range of the tool.

3. The incremental forming method described in claim 1 or 2, characterized in that an imaging device is used to image the forming portion of the metal plate, and the sub-drive device is controlled based on the difference between the target trajectory and the actual forming portion imaged by the imaging device.

4. The incremental forming method described in claim 3, characterized in that a projection device is used to project the target trajectory onto the metal plate, and the sub-drive device is controlled based on the difference between the target trajectory imaged by the imaging device and the actual forming portion.

5. An incremental forming apparatus used in the incremental forming method according to claim 1 or 2, comprising: a sub-drive unit which drives the tool in a direction parallel to the metal plate; a main drive unit which drives the sub-drive unit in three orthogonal axial directions; and a control unit which controls the sub-drive unit and the main drive unit, wherein the control unit has the functions of setting a target trajectory corresponding to the shape of the forming portion of the metal plate, setting an overall range of movement of the tool by the sub-drive unit based on the target trajectory, setting a basic trajectory of the sub-drive unit by the main drive unit within the overall range of movement, and driving the tool along the target trajectory by the sub-drive unit while driving the sub-drive unit along the basic trajectory by the main drive unit.

6. The incremental forming apparatus according to claim 5, further comprising an imaging device for imaging the forming portion of the metal plate, and the control device has a function of controlling the sub-drive device based on the difference between the target trajectory and the actual forming portion imaged by the imaging device.

7. The incremental forming apparatus as described in claim 6, further comprising a projection device for projecting the target trajectory onto the metal plate, and the control device has a function of controlling the sub-drive device based on the difference between the target trajectory imaged by the imaging device and the actual forming portion.

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