JP2017217657A - Gradual molding method and gradual molding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problems of being complicated in maintenance-management of a tool, and of increasing manufacturing cost, in a conventional gradual molding method.SOLUTION: When molding in a three-dimensional shape by moving a predetermined passage by pressing a tool T to a surface layer of a metal plate W by holding the periphery of the metal plate W having the surface layer, an advance quantity (h) in the pressing direction of the tool T to the metal plate W is changed in response to a processing angle θ formed by the metal plate W before molding and a processing surface S after molding, and in its case, the advance quantity (h) of the tool T is reduced as the processing angle θ becomes a small part, and the metal plate W is molded by providing the upper limit to the ratio (Fs/Fp) of sliding force Fs in the movement direction of the tool T to pressing force Fp of the tool T. Thus, besides being capable of providing a molding product having a flaking-nonexistent excellent appearance quality, simplification of maintenance-management of the tool and reduction in manufacturing cost, can be realized.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a sequential forming method and a sequential forming apparatus that are used to gradually deform a metal plate into a three-dimensional shape by pressing and moving the tool against the metal plate having a surface layer.

  Conventionally, as a sequential molding method, for example, there is one described in Patent Document 1. The sequential molding method described in Patent Document 1 uses a lower mold having a shape of a molded product, an outer peripheral frame that holds a metal plate on the upper surface side of the lower mold, and a molding tool that is movable in three orthogonal directions. . In the above sequential forming method, on the upper surface side of the lower mold, the periphery of the flat metal plate is held by the outer peripheral frame, and a tool is pressed against the metal plate to move, and the periphery of the metal plate is lowered along the outer peripheral frame. Let Thereby, in the sequential forming method, the metal plate is gradually deformed so as to follow the lower die, and finally a three-dimensional shaped product is formed (extrusion forming).

  In the sequential forming method, since the tip of the tool has a spherical shape, the tool may make point contact with the metal plate, and thereby the scanning line of the tool may be transferred to the metal plate. Therefore, in the sequential forming method described in Patent Document 1, the tool scanning line on the metal plate is formed by forming the tip of the tool with a detachable resin pressing portion and bringing the resin pressing portion into surface contact with the metal plate. Was preventing the transfer of.

JP 2002-102945 A

  By the way, in the sequential forming method as described above, for example, when forming a metal plate having a surface layer such as plating, flaking that the surface layer peels off may occur. This flaking causes a decrease in surface roughness (look) and corrosion resistance. On the other hand, since the conventional sequential molding uses a tool having a resin pressing portion, it is possible to suppress the occurrence of flaking to some extent.

  However, in the sequential molding method using the above-mentioned tool, the wear of the resin pressing portion is severe, and it is necessary to frequently replace the resin pressing portion, so that the maintenance management of the tool is complicated and the manufacturing cost increases. There was a point, and it was a problem to solve such a problem.

  The present invention has been made by paying attention to the above conventional problems, and in the sequential forming of a metal plate having a surface layer, it is possible to obtain a molded product having good appearance quality without flaking, It is an object of the present invention to provide a sequential forming method capable of simplifying tool maintenance management and reducing manufacturing costs.

  In the sequential forming method according to the present invention, the metal plate is gradually deformed in the plate thickness direction by holding the periphery of the metal plate having the surface layer and moving a predetermined path by pressing a tool against the surface layer of the metal plate. This is a method of forming a three-dimensional shape. In this sequential forming method, the amount of advance in the pressing direction of the tool against the metal plate is changed according to the processing angle formed by the metal plate before forming and the processed surface after forming. Reduce the amount of advance. The sequential forming method is characterized in that the metal plate is formed by setting an upper limit on the ratio of the sliding force in the moving direction of the tool to the pressing force of the tool.

  The sequential forming apparatus according to the present invention keeps the periphery of a metal plate having a surface layer, and presses and moves the tool against the surface layer of the metal plate, thereby gradually deforming the metal plate in the plate thickness direction to obtain a three-dimensional shape. It is an apparatus for forming into a shape. This sequential forming apparatus includes a holding jig that holds the periphery of a metal plate, a triaxial moving mechanism that relatively moves the tool and the holding jig in three orthogonal directions, and a tool pressed against the metal plate. The apparatus includes a component force meter that measures a pressing force generated in the axial direction and a sliding force in the moving direction, and a main control unit that controls the three-axis moving mechanism based on the measured value of the force meter.

  According to the sequential forming method according to the present invention, by adopting the above configuration, in the sequential forming of a metal plate having a surface layer, a molded product having good appearance quality without flaking can be obtained, and a tool can be obtained. The maintenance management can be simplified and the manufacturing cost can be reduced.

  In the sequential forming apparatus according to the present invention, the three-axis moving mechanism is controlled by the main control unit so that the pressing force of the tool and the sliding force in the moving direction become appropriate values. As a result, the sequential forming apparatus can obtain a molded product having good appearance quality without flaking in the sequential forming of a metal plate having a surface layer, and also simplifies tool maintenance management and reduces manufacturing costs. Can be achieved.

It is a section explanatory view explaining a 1st embodiment of a sequential forming method and a sequential forming device concerning the present invention. It is a top view explaining the sequential forming with respect to a metal plate. It is explanatory drawing which shows the force of each direction which arises in the processing angle of a metal plate, and a tool. It is sectional drawing of embodiment explaining the processing angle of a metal plate, and the feed pitch of a tool. It is sectional drawing of the comparative example explaining the processing angle of a metal plate, and the feed pitch of a tool. It is a graph which shows the relationship between the frictional force of a tool, and the feed pitch of a tool. It is a graph which shows the relationship between a friction force and the feed pitch of a tool, when the curvature radius R of the front-end | tip of a tool is 3 mm. It is a graph which shows the relationship between the feed pitch of a tool, and a process angle. It is a graph which shows the relationship between the shear stress which arises in a metal plate, and the feed pitch of a tool. It is the top view and AA sectional view taken on the line of the engine hood outer panel explaining 2nd Embodiment of the sequential shaping | molding method concerning this invention. It is the top view explaining the inner panel for engine hoods, AA sectional view, and BB sectional drawing.

<First Embodiment>
FIG. 1 is a diagram illustrating a sequential molding apparatus applicable to the sequential molding method according to the present invention. The sequential forming apparatus shown in the figure holds the periphery of the metal plate W having the surface layer, and presses and moves the tool T against the surface layer of the metal plate W, thereby gradually deforming the metal plate W in the plate thickness direction. It is molded into a three-dimensional shape (molded product shape).

  The sequential forming apparatus includes a holding jig 1 that holds the periphery of the metal plate W, and a triaxial moving mechanism 2 that relatively moves the tool T and the holding jig 1 in three orthogonal directions. . Further, the sequential forming apparatus is based on the force meter 3 that measures the pressing force Fp generated in the axial direction of the tool T pressed against the metal plate W and the sliding force Fs in the moving direction, and the measured value of the force meter 3. And a main control unit 4 for controlling the triaxial moving mechanism 2.

  The tool T has a round bar shape and has a spherical tip portion, and the tip portion is pressed against the metal plate W for molding. The metal plate W has, for example, a plating layer as a surface layer, and is basically flat before being formed.

  As shown in FIG. 2, the holding jig 1 has a frame shape corresponding to the periphery of the metal plate W, and includes a lower fixing tool 1 </ b> A and an upper movable tool 1 </ b> B. By clamping the periphery and fixing the movable tool 1B, the periphery of the metal plate W is firmly restrained.

  As the triaxial moving mechanism 2, for example, an NC machine tool or a multi-axis control type working robot can be used. The triaxial moving mechanism 2 of this embodiment is arranged on the upper side of the holding jig 1 and moves the tool T in three orthogonal directions. That is, the triaxial moving mechanism 2 includes a pair of guide rails 5, 5, a beam 6 that can reciprocate along both guide rails 5, 5, a slider 7 that can reciprocate along the beam 6, and a slider 7 And a holder 8 that can be moved up and down.

  Both guide rails 5 and 5 are supported horizontally and parallel to each other by a post or the like (not shown). The beam 6 is installed between the guide rails 5 and 5, and both end portions thereof are guided by the guide rails 5 and 5 in the horizontal X-axis direction (vertical direction in FIG. 1). The slider 7 is guided in the longitudinal direction of the beam 6, that is, in the horizontal Y-axis direction (left-right direction in FIG. 1) orthogonal to the moving direction (X-axis direction) of the beam 6. The holder 8 moves up and down in the Z-axis direction perpendicular to the slider 7.

  The triaxial moving mechanism 2 has the tool T mounted on the holder 8 via the force meter 3 in a suspended state. In this way, the tool T can be moved by the triaxial moving mechanism 2 in the triaxial directions of the X axis direction, the Y axis direction, and the Z axis direction that are orthogonal to each other. For example, a known three-component force meter can be used as the force meter 3. When the tool T is pressed against the metal plate W and moved, the pressing force Fp generated in the axial direction of the tool T and the tool T The sliding force Fs in the moving direction (tangential direction) can be measured.

  As shown in FIG. 2, the sequential forming apparatus sets a tool T at an initial position, presses the tool T against a flat metal plate W, and moves along a moving path A1 indicated by a solid line arrow in FIG. Move. In this embodiment, the case where the metal plate W is formed into a dish-shaped three-dimensional shape is illustrated. In this case, the initial movement path A1 is a path that circulates along the inside of the holding jig 1.

  Next, the sequential forming apparatus moves the tool T toward the center side of the metal plate W as shown by a thick arrow in FIG. It circulates along the next movement route A2 indicated by a dotted arrow. Thereafter, the sequential forming apparatus gradually moves the movement paths A1 and A2 of the tool T toward the center side of the metal plate W at each turn, and the advance amount (down amount) in the pressing direction of the tool T in steps. Change (increase). That is, as shown by the black arrow in FIG. 1, the tool T moves obliquely downward every time it makes a round.

  As a result, the sequential forming apparatus forms an inclined processing surface so as to push down the central region of the metal plate W, and finally, the processing surface is the side surface S and the center as shown by the dotted line in FIG. It shape | molds sequentially in the dish-shaped three-dimensional shape (molded product shape) which makes an area | region the bottom face B. At this time, the sequential forming apparatus can form the metal plate W into a three-dimensional shape by using the tool T and the holding jig 1 without using a forming die.

  In addition, the sequential forming apparatus inputs the pressing force Fp and the sliding force Fs measured by the force meter 3 to the main control unit 4 when the metal plate W is sequentially formed as described above. The main control unit 4 determines the frictional force of the tool T against the metal plate W based on the measurement value of the force meter 3, the contact area of the tool T with the metal plate W input in advance, the material of the metal plate W, and the like. The shear stress generated in the metal plate W is calculated. Then, the main control unit 4 determines the beam 6 and slider of the triaxial moving mechanism 2 so that the pressing force Fp and the sliding force Fs of the tool T become appropriate values based on the measurement value and calculation result of the force meter 3. 7 and the holder 8 are feedback-controlled.

  Here, in the sequential forming method described below, as shown in FIG. 2, the displacement width between the previous movement path A1 and the subsequent movement path A2 is defined as a feed pitch P. As shown in FIG. 3, the angle formed by the flat metal plate W before forming and the processed surface (side surface S) after forming is defined as a processing angle θ. Furthermore, the pressing force Fp in the axial direction and the sliding force Fs in the moving direction are applied to the tool T being formed, so that the sliding force Fs is in the opposite direction between the tool T and the metal plate W. The frictional force Ff is generated.

  In FIG. 3, for the sake of convenience, the processing angle θ of the metal plate W and the directions of the forces Fp and Fs applied to the tool T are shown together. 3, the actual moving direction of the tool T (the direction of the sliding force Fs / the direction of the moving path) is the direction perpendicular to the paper surface, and the direction in which the moving path of the tool T is displaced is illustrated in FIG. 3 is the right direction. Further, as will be described later, the tool T is composed of a base material Ta and a hard material Tb, and at least a contact portion with the metal plate W, that is, a tip portion is formed of the hard material Tb.

  In the sequential forming method, as described in the previous sequential forming apparatus, the periphery of the metal plate W having the surface layer is held, the tool T is pressed against the surface layer of the metal plate W, and the predetermined path is moved. In this method, the metal plate W is gradually deformed in the thickness direction to form a three-dimensional shape.

  In the sequential forming method, the advance amount (down amount) h in the pressing direction of the tool T against the metal plate W is changed according to the processing angle θ formed by the metal plate W before forming and the processed surface (S) after forming. . At that time, the sequential forming method reduces the advance amount h of the tool T as the machining angle θ is smaller, and also sets the ratio of the sliding force Fs in the moving direction of the tool T to the pressing force Fp of the tool T (Fs / Fp). The metal plate W is formed with an upper limit. As a more desirable embodiment, the sequential forming method sets the upper limit of the ratio (Fs / Fp) of the sliding force Fs to 0.2 or less, and forms the metal plate W while maintaining the upper limit.

  A specific example is shown in FIG. The illustrated three-dimensional shape has a curved processed surface (S) and a flat bottom surface B. In this case, the processing angle θ of the processing surface (S) gradually decreases during the period from the angle θ1 of the molding start site to the angle θx of the molding end site (θ1 to θx). Therefore, in the sequential forming method, the movement path (A1, A2) is displaced for each turn as described with reference to FIG. 2, and the advance amount h of the tool T is decreased as the machining angle θ is smaller. That is, the advance amount h of the tool gradually decreases during the period from the advance amount h1 of the forming start portion to the advance amount hx of the forming end portion (h1 to hx). As a result, in the sequential forming method, the feed pitch P of the tool T is small in the vicinity of the forming start (P1 to P3) and increases thereafter, but is generally uniform until reaching the forming end portion (Px).

  FIG. 5 shows a comparative example. In this comparative example, when the same three-dimensional shape as shown in FIG. 4 is formed, the machining angle θ (θ1 to θx) decreases, whereas the advance amount h (h1 to hx) of the tool T is reduced. It is equalized. In this case, the feed pitch P of the tool T continues to gradually increase during the period from the molding start site to the molding end site (P1 to PX). For this reason, in the case of a comparative example, it becomes easy to produce the flaking which the surface layer of the metal plate W peels.

  On the other hand, in the sequential forming method shown in FIG. 4, the forward movement amount h of the tool T is decreased as the machining angle θ is smaller, so that the feed pitch P of the tool T may continue to increase gradually as in the comparative example. Reduce the occurrence of flaking.

  Therefore, the sequential forming method sets an upper limit on the ratio (Fs / Fp) of the sliding force Fs in the moving direction of the tool T to the pressing force Fp of the tool T in addition to the relationship between the machining angle θ and the advance amount h. Desirably, the occurrence of flaking is prevented by forming the metal plate W while maintaining the upper limit value at 0.2 or less.

  Further, as a more preferable embodiment, the sequential forming method has a curvature radius R of the tip portion of the tool T of 3 mm or less, the tool T is moved along a predetermined path (A1, A2), and then the movement path of the tool T. Is moved stepwise and the advance amount h in the pressing direction of the tool T is changed stepwise. The sequential forming method can form the metal plate W while maintaining the tool feed pitch P, which is the displacement width of the movement path, at P = (0.0087 × working angle + 0.00135) or less. Here, “0.087” in the above equation is the slope of the approximate straight line with respect to the machining angle of the tool feed pitch P (see FIG. 8). Further, “0.00135” in the equation is a value of the pitch P at a processing angle of 0 ° when the approximate straight line is obtained from conditions that pass through processing angles of 30 °, 40 °, and 50 °.

  Furthermore, the successive forming method is a more preferable embodiment, in which the metal plate W is formed while maintaining the shear stress of the metal plate W obtained from the sliding force Fs in the moving direction of the tool T and the contact area of the tool T at 40 MPa or less. Can be molded.

The basis of each numerical value used in the above sequential molding method is as follows.
That is, in order to obtain the ratio of the sliding force Fs to the pressing force Fp of the tool T (Fs / Fp), the relationship between the feed pitch P of the tool T and the forming angle θ, and the optimum value of the shear stress generated in the metal plate W, The following tests were conducted.

  In the test, the metal plate W was sequentially formed by using a tool T having a different curvature radius R at the tip and changing the pressing force Fp, the sliding force Fs, the feed pitch P, and the processing angle θ. The pressing force Fp and the sliding force Fs were measured by the force meter 3 described with reference to FIG. The tool T used had a radius of curvature R at the tip of 3 mm (R3), 5 mm (R5), and 10 mm (R10). These tools T also have different contact areas with the metal plate W. The results are shown in FIGS.

  FIG. 6 is a graph showing the relationship between the frictional force Ff generated between the tool T and the metal plate W and the feed pitch P of the tool T. The frictional force Ff is a value (Fs / Fp) obtained by dividing the sliding force Fs of the tool T by the pressing force Fp. As is apparent from FIG. 6, in any of the tools T, the frictional force Ff increases as the feed pitch P of the tool T increases. In particular, the frictional force Ff increases as the tool T has a smaller radius of curvature R at the tip. The increase was remarkable. And it became clear that the flaking which a surface layer peels generate | occur | produces, when the frictional force Ff becomes larger than 0.2 even if which tool T is used.

  Therefore, in the sequential forming method, in addition to the relationship between the machining angle θ of the metal plate W and the advance amount h of the tool T, the frictional force Ff, that is, the sliding force Fs with respect to the pressing force Fp of the tool T is calculated based on the above test result. By setting the upper limit of the ratio (Fs / Fp) to 0.2 or less, occurrence of flaking is prevented.

  FIG. 7 shows the relationship between the frictional force Ff and the feed pitch P when using a tool T having a radius of curvature R of 3 mm (R3) at the tip and varying the machining angle θ to 30 °, 40 °, and 50 °. It is a graph which shows. As is clear from FIG. 7, the friction force Ff increases as the feed pitch P increases at any machining angle θ, but there is no significant difference in the degree of increase when the friction force Ff is 0.2 or less. It has been found that flaking occurs when Ff is greater than 0.2.

  FIG. 8 is a graph showing the relationship between the machining angle θ and the feed pitch P obtained based on the results of the test. In this case, the radius of curvature R of the tip of the tool T was 3 mm (R3), and the machining angle θ was varied to 30 ° (θ30), 40 ° (θ40), and 50 °. As is clear from FIG. 8, the relationship between the processing angle θ and the feed pitch P, which is a guide for occurrence of flaking, is a direct proportion having a constant gradient, and flaking occurs in the upper region of the gradient. It was found that no flaking occurred in the lower region of the gradient.

  Therefore, in the sequential forming method, when the tool T having the curvature radius R of the tip portion of 3 mm or less is used, flaking does not occur based on the gradient of the relationship between the machining angle θ and the feed pitch P in FIG. The upper limit threshold value of the feed pitch P was calculated. As a result, the feed pitch P was set to P = (0.0087 × processing angle + 0.00135) or less. As a result, in the sequential molding method, flaking is prevented from occurring even if sequential molding is performed at any processing angle θ.

  FIG. 9 is a graph showing the relationship between the feed pitch P obtained based on the result of the test and the shear stress generated in the metal plate W. The shear stress is a value obtained by dividing the sliding force Fs in the moving direction of the tool T by the contact area of the tool T with the metal plate W (Fs / contact area). The tool T used had a radius of curvature R at the tip of 3 mm (R3), 5 mm (R5), and 10 mm (R10). As is apparent from FIG. 9, the shear stress increases as the feed pitch P increases, regardless of which tool T is used. And it became clear that the shear stress tends to increase as the tool radius T becomes smaller, and flaking occurs when the value of the pre-stage stress exceeds 40 MPa.

  Therefore, in the sequential forming method, the shear stress of the metal plate W obtained from the sliding force Fs in the moving direction of the tool T and the contact area of the tool T is set to 40 MPa or less. This prevents flaking from occurring in the sequential molding method.

  As described above, the sequential forming method reduces the advance amount h of the tool T as the machining angle θ is smaller, and the ratio of the sliding force Fs in the moving direction of the tool T to the pressing force Fp of the tool T (Fs / Fp). ) And forming the metal plate W while maintaining the upper limit value at 0.2 or less. As a result, the sequential molding method can obtain a molded product having good appearance quality (glossiness and appearance) without flaking in the sequential molding of the metal plate W having the surface layer, and molding by preventing flaking. High corrosion resistance of the product can be obtained. Moreover, in the sequential molding method, flaking can be prevented after using an integrated tool T made of a hard material without using a tool having a detachable resin pressing portion, so that maintenance management of the tool T is simplified. And manufacturing cost can be reduced.

  Further, in the above-described sequential forming method, the radius of curvature R of the tip of the tool T is 3 mm or less, and the feed pitch P of the tool T, which is the displacement width of the moving path, is P = (0.0087 × working angle + 0.00135). ) Form the metal plate while maintaining the following. As a result, the sequential molding method can more reliably prevent the occurrence of flaking and contribute to further improvement in the appearance quality and corrosion resistance of the molded product. It is possible to satisfactorily mold a portion having a small diameter.

  Furthermore, the above sequential forming method more reliably prevents flaking by forming while maintaining the shear stress of the metal plate W obtained from the sliding force Fs of the tool T and the contact area at 40 MPa or less. This can contribute to further improvement in the appearance quality and corrosion resistance of the molded product.

  Further, in the sequential forming method, as described in the sequential forming apparatus based on FIG. 1, the pressing force Fp of the tool T and the sliding force Fs in the moving direction are feedback controlled based on the measurement values measured by the force meter 3. To do. More precisely, the three-axis moving mechanism 2 is feedback-controlled so that the pressing force Fp and the sliding force Fs of the tool T become appropriate values based on the measurement values measured by the force meter 3.

  Thereby, the sequential molding method and sequential molding apparatus can continuously produce molded products having good appearance quality and high corrosion resistance, for example, in a production line. In addition, since flaking can be prevented after using the integrated tool T made of a hard material, the maintenance and management of the tool T can be simplified and the manufacturing cost can be reduced.

  Further, in the sequential forming method, the metal plate W has a plating layer as a surface layer, and more specifically, the metal plate W is a galvanized steel plate or an alloyed hot-dip galvanized steel plate. Such a metal plate W is used for an automotive panel or the like because it has good adhesion to the coating film and corrosion resistance. On the other hand, the above-described sequential forming method can sequentially form the metal plate W without causing peeling of the plating layer as the surface layer, so that an automotive panel having excellent appearance quality and corrosion resistance can be provided. .

  Further, in the sequential forming method, the surface roughness (Ra) after processing of the metal plate W is set to 0.2 μm or less, more desirably 0.1 μm or less. Thereby, the sequential molding method provides a molded product having excellent appearance quality, particularly glossiness, and high durability.

  Furthermore, the sequential forming method uses, as a more preferred embodiment, a tool T formed of a non-alloyed material in which at least a contact portion with the metal plate W is not alloyed with the metal plate W, and at least a contact portion with the metal plate W A tool T having a surface roughness (Ra) of Ra ≦ 0.2 μm can be used. As a result, the sequential forming method prevents the adhesion between the tool T and the metal plate W in advance, and can perform good sequential forming at high speed without using a lubricant. Time can be shortened and production efficiency can be improved.

  Furthermore, as a more preferable embodiment, the sequential forming method is a tool T which is made of a base material Ta and a hard material Tb and at least a contact portion with the metal plate W is formed of the hard material Tb as shown in FIG. Can be used. Thereby, the sequential forming method can keep the tool cost low and can contribute to the reduction of the manufacturing cost of the molded product.

  Furthermore, the sequential forming method can use, as a more preferred embodiment, a tool T in which the hard material Tb is a hard carbon film selected from polycrystalline diamond, single crystal diamond, and diamond-like carbon. As a result, the sequential forming method prevents adhesion between the tool T and the metal plate W, and can perform good sequential forming at high speed without using a lubricant, shortening the cycle time and producing In addition to improving efficiency, the tool T can have a long service life.

Second Embodiment
FIGS. 10 and 11 are views for explaining a second embodiment of the sequential molding method according to the present invention, and illustrate sequential molding of an outer panel OP and an inner panel IP of an automobile engine hood. In addition, each figure has exaggerated and shown the magnitude | size of the height direction for convenience, and the actual panel is flatter than the illustration shape.

  The outer panel OP shown in a plan view in FIG. 10 has a vehicle body front portion on the lower side, and is gently curved upward as shown in the cross section in the figure. A line CL is formed. The character line CL is a portion that protrudes upward and has an inner radius of curvature R that is smaller than the main body portion (as an example, 1 to 3 mm).

  In the sequential forming method, the outer panel OP is formed from the lower surface side, and a flat metal plate (blank material) is sequentially formed to form curved side surfaces (processed surfaces) S. The side surface S corresponds to the side surface S in FIG. The central region of the outer panel OP corresponds to the bottom surface B in FIG. Thereafter, in the sequential forming method, a character line CL is formed from the back side using a tool T (for example, a tool R3) having a small curvature radius at the tip. In the example shown in FIG. 2, the case where the tool T is moved around has been described. However, when the character line CL is formed, the tool T is moved linearly, and the movement path and the advance amount ( Change the descent amount) appropriately.

  The inner panel IP shown in a plan view in FIG. 11 is joined to the outer panel OP to constitute an engine hood. As shown in the cross section in the figure, the inner panel IP is gently curved downward as a whole, and a plurality of ribs Rb are arranged to increase the mechanical strength. The rib Rb has a groove shape on the back side, and has a smaller radius of curvature R on the inner side (1 to 3 mm as an example) than the main body portion.

  In the sequential forming method, the inner panel IP is formed from the upper surface side, and the curved side surfaces (processed surfaces) S are formed by sequentially forming a flat metal plate (blank material). Thereafter, in the sequential forming method, the rib Rb is formed from the back side using a tool T (for example, R3 tool) T having a small curvature radius at the tip. Even in this case, the tool T is moved linearly, and the rib Rb is formed by appropriately changing the movement path and the forward movement amount (lowering amount) for each movement.

  Here, for the outer panel OP and the inner panel IP, for example, a galvanized steel plate or an alloyed hot-dip galvanized steel plate is used. On the other hand, in the sequential forming method, as described in the previous embodiment, the occurrence of flaking is prevented in the sequential forming of the metal plate W having the surface layer. Therefore, according to the sequential forming method, it is possible to provide the outer panel OP and the inner panel IP having good appearance quality and high corrosion resistance without damaging the plating layer as the surface layer.

<Example>
As Examples 1 to 9, using a sequential forming apparatus as shown in FIG. 1, the curvature radius R of the tip of the tool T, the machining angle θ, the machining speed (movement speed), the feed pitch P, and the movement direction of the tool The metal plate was sequentially formed by changing the sliding force. The material of the tip portion of the tool T was a diamond coating. Further, by changing the pressing force of the tool T, the shear stress (sliding force / tool contact area) generated between the metal plate W and the frictional force Ff (sliding force / pressing force) were also changed. And the presence or absence of flaking was confirmed, the surface roughness (Ra) after a process was measured, and the time until Fe elution was calculated | required.

  As Comparative Examples 1 to 9, the material of the tip of the tool T, the processing angle θ, the processing speed (moving speed), the feed pitch P, the pressing force of the tool, and the sliding force in the moving direction are changed to sequentially form the metal plate. It was. In addition, the curvature radius R of the front-end | tip part of the tool T was all 3 mm. And like the Example, the presence or absence of flaking was confirmed, the surface roughness (Ra) after a process was measured, and the time until Fe elution was calculated | required. Table 1 shows the conditions and results of Examples 1 to 9 and Comparative Examples 1 to 9.

  As apparent from Table 1, in Examples 1 to 9, the ratio of the sliding force Fs to the pressing force Fp of the tool T (Fs / Fp) is set to 0.2 or less, and the shear stress generated in the metal plate W is set to 40 MPa or less. In any case, no flaking was observed when the metal plate W was formed. In Example 6, flaking was not observed although it exceeded 0.2.

  On the other hand, in Comparative Examples 1 to 9, except for Comparative Example 7, the ratio of the sliding force Fs to the pressing force Fp of the tool T (Fs / Fp) exceeds 0.2, and the shear generated in the metal plate W The stress exceeded 40 MPa, and in all cases, occurrence of flaking was confirmed entirely or partially.

  In Examples 1 to 9, Examples 1 and 9 exceeded the surface roughness Ra of 0.2 μm. However, as described above, flaking did not occur and the surface roughness Ra was 0.2 μm. It was as follows, and it was confirmed that both had good appearance quality. On the other hand, in Comparative Examples 1 to 9, the surface roughness Ra clearly exceeded 0.2 μm in any case, and it was confirmed that the appearance quality was inferior to the examples.

  Furthermore, in Examples 1-9, it turned out that time until Fe elution exceeds 500 (Hr) in all. On the other hand, in Comparative Examples 1 to 9, the Fe elution time 124 (Hr) of Comparative Example 6 is the longest and most is 100 (Hr) or less with respect to the time until Fe elution. Obviously low durability

  As is apparent from the comparison between the above-described Examples and Comparative Examples, the sequential molding method is superior to the Comparative Examples in terms of the presence or absence of flaking, the surface roughness after processing (Ra), and the time until Fe elution. It was confirmed that excellent results were obtained and a molded product having good appearance quality and high durability without flaking could be provided.

  The sequential molding method and sequential molding apparatus according to the present invention are not limited to the above embodiments, and the details of the configuration can be changed as appropriate without departing from the gist of the present invention. Further, in each of the above-described embodiments, the case where sequential forming is performed with a tool arranged on the upper side of the metal plate is illustrated, but it is also possible to form the metal plate in a standing state and press the tool from the lateral direction to sequentially form. The holding jig may be movable.

Fs Tool sliding force Fp Tool pressing force h Tool advance amount P Tool feed pitch T Tool Ta Base material Tb Hard material W Metal plate θ Machining angle 1 Holding jig 2 Triaxial moving mechanism 3 Component force meter 4 Main Control unit

Claims (13)

Holding the periphery of the metal plate having the surface layer, pressing a tool against the surface layer of the metal plate and moving a predetermined path, the metal plate is gradually deformed in the plate thickness direction to form a three-dimensional shape,
Depending on the machining angle formed by the metal plate before forming and the processed surface after forming, the amount of advancement in the pressing direction of the tool against the metal plate is changed. With
A sequential forming method characterized by forming an upper limit on a ratio of a sliding force in a moving direction of a tool to a pressing force of the tool to form a metal plate.   The sequential molding method according to claim 1, wherein an upper limit of the ratio of the sliding forces is 0.2 or less. The radius of curvature R of the tip of the tool is 3 mm or less,
After moving the tool along a predetermined path, the tool moving path is displaced stepwise,
The advance amount in the tool pressing direction will be changed in stages,
3. The sequential forming according to claim 2, wherein the metal plate is formed while maintaining a feed pitch P of the tool, which is a displacement width of the moving path, at P = (0.0087 × processing angle + 0.00135) or less. Method.   The metal plate is formed while maintaining the shear stress of the metal plate obtained from the sliding force in the moving direction of the tool and the contact area of the tool at 40 MPa or less. The sequential molding method described in 1. Using a force meter that measures the pressing force of the tool and the sliding force in the moving direction,
The sequential forming method according to any one of claims 1 to 5, wherein feedback control is performed on the pressing force of the tool and the sliding force in the moving direction based on a measurement value measured by a force meter.   The sequential forming method according to any one of claims 1 to 4, wherein the metal plate has a plating layer as a surface layer.   The sequential forming method according to claim 6, wherein the metal plate is a galvanized steel plate or an alloyed hot-dip galvanized steel plate.   The sequential forming method according to claim 6, wherein the metal plate has a surface roughness (Ra) after processing of 0.2 μm or less.   The sequential forming method according to any one of claims 1 to 8, wherein at least a contact portion with the metal plate is formed of a non-alloyed material that is not alloyed with the metal plate. .   10. The sequential forming method according to claim 9, wherein the tool has a surface roughness (Ra) of at least a contact portion with a metal plate of Ra ≦ 0.2 μm.   The sequential forming method according to claim 9 or 10, wherein the tool includes a base material and a hard material, and at least a contact portion with the metal plate is formed of the hard material.   The sequential molding method according to claim 11, wherein the hard material is a hard carbon film selected from polycrystalline diamond, single crystal diamond, and diamond-like carbon. An apparatus for forming a three-dimensional shape by gradually deforming the metal plate in the plate thickness direction by holding the periphery of the metal plate having the surface layer, and pressing and moving the tool against the surface layer of the metal plate,
A holding jig for holding the periphery of the metal plate;
A triaxial moving mechanism for relatively moving the tool and the holding jig in three orthogonal directions;
A force meter that measures the pressing force generated in the axial direction of the tool pressed against the metal plate and the sliding force in the moving direction;
A sequential molding apparatus comprising: a main control unit that controls a triaxial moving mechanism based on a measurement value of a force meter.

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