JP5503173B2 - Aluminum alloy sheet forming method - Google Patents

Description

  The present invention relates to a method for forming an aluminum alloy plate on an aluminum alloy automobile panel such as a door, a luggage, and an outer panel of a fender (hereinafter, aluminum is also referred to as Al).

  Conventionally, panels such as outer panels (outer panels) and inner panels (inner panels) of panel structures such as automobile hoods, fenders, doors, luggage, roofs, trunk lids, etc. have been made of thin and high-strength Al alloy panels. As materials, Al-Mg series 5000 series excellent in formability and Al-Mg-Si series 6000 series aluminum alloy sheet (rolled sheet) excellent in formability and bake hardenability have begun to be used.

  As is well known, these automobile panels are formed into a panel (product) shape by press molding of an aluminum alloy plate. Outer panels such as doors, luggages, and fenders of automobile panels, for example, are equipped with equipment and members such as handle seats, lamp seats, license (license plate) seats, or draw wheel arches of a predetermined depth. A concave portion (an overhang portion or an embossed portion) is partially provided. 5 (a) is a perspective view of the handle seat 14 of the door outer panel 11, FIG. 5 (b) is a license seat 15 and a lamp seat 16 of the luggage outer panel 12, and FIG. 5 (c) is a wheel arch 17 of the fender outer panel 13. It shows with.

  Usually, the molds for forming these recesses are integrally arranged in a mold for molding the overall shape (overall curved surface) of the automobile panel, and the recesses and the overall shape of the automobile panel are simultaneously press-molded.

  However, this recess (overhang) needs to have a certain depth, and when the recess connected to the entire curved surface as described above, including the continuous curved surface around the recess shape, is press-molded, Distortion tends to occur, and surface distortion (surface distortion) is inevitable. When press-molding an aluminum alloy plate having a crack limit lower than that of a steel plate, it is necessary to make the tension at the time of forming lower than that in the case of a steel plate, which promotes the occurrence of surface distortion.

  And when this surface distortion generate | occur | produces, since an aluminum alloy plate has a low elastic modulus compared with a steel plate, it is also difficult to erase | eliminate the surface distortion once generated by press molding or correction. Therefore, the occurrence of surface distortion associated with the formation of the concave portion (projecting portion) is a problem unique to an aluminum alloy plate that is not present in a steel plate.

  Such a state of occurrence of surface distortion is disclosed in Patent Document 5, which will be described later, and the mechanism of occurrence of surface distortion will be specifically described using this state. FIG. 6A (FIG. 5 of Patent Document 5) shows a conventional press molding method of the handle seat 14 of the door outer panel 11 after the entire molding in a sectional view of the press device. In FIG. 6A, the door outer panel 11 is partially press-molded in the direction of the arrow by the punch 30 against the molding surface 2b of the handle seat 14 of the mold 20 while the door outer panel 11 is fixed by the wrinkle retainer 4. ing.

  In such a case, as shown in FIG. 6 (b), the door outer panel 11 being molded is shown in plan view, as the material (aluminum alloy plate) flows into the handle seat 14 in the direction of the arrow A1, the arrows A2 and A3 In the horizontal direction, the material inevitably and unevenly moves. For this reason, surface distortion X occurs at the four corners of the peripheral portion 14 a of the handle seat 14. When the surface distortion X occurs in this way, when the mold is removed and the panel 11 is opened, the molded panel outer panel 11 is shown in a plan view in FIG. As a result, a convex portion Y is generated. Therefore, the occurrence of surface distortion deteriorates the shape accuracy such as the flatness of the automobile panel, and in particular, the outer panel for the above-mentioned use impairs the appearance or aesthetics. For this reason, when troublesome correction work is required or the occurrence of surface distortion is significant, it cannot be corrected by correction and cannot be employed as an outer panel.

  There are other causes of such surface distortion X in the vicinity of the overhanging portion (embossing) due to fleshing due to circumferential compressive stress and bending moment due to minute inflow of material at the corner portion of the handle seat 14. Increased surface distortion due to swell and elastic recovery. In addition to the handle seat 14 of the door outer panel 11, the license seat 15 and the lamp seat 16 of the luggage outer panel 12 shown in FIG. 5B, and the wheel arch 17 of the fender outer panel 13 shown in FIG. Surface distortions occur due to the same or different causes such as residual of each of them.

  In addition, such a problem of surface distortion is not only a problem of the above-mentioned concave portion (overhanging portion), but is not limited to the shape of the door outer panel, the vertical wall of the front fender, the wind corner of the rear fender, the trunk lid or the hood outer. This is a problem common to aluminum alloy automobile panels that have concave portions (overhangs) that cause surface distortion, such as the disappearing part of the character line and the base part of the rear fender pillar.

  On the other hand, there is a big limit to the suppression of the surface distortion by improving the formability on the aluminum alloy material side. For this reason, various improvements from the processing side have been proposed in the past in forming into an aluminum alloy panel such as an automobile panel having the concave portion in part.

  For example, after punching (drilling) the central part of the part where the concave part (concave part) is to be molded, the hole expanding process for drawing the peripheral part of this punched part while preventing surface distortion, It has been proposed to form a recessed portion in a material (see Patent Document 1). However, aluminum alloy sheets have a lower hole expansion limit than steel sheets, and cracks are likely to occur from hole edges, making it difficult to apply under effective conditions for forming aluminum alloy panels such as automobile panels. . Further, since the punching process is required, there is a limit that can be applied only to a panel having a hole (allowing a hole).

  In addition, a press molding method for molded products with embossed parts that can prevent cracking and surface distortion during molding by controlling the wrinkle holding force (wrinkle holding pressure: tons) to a certain range is proposed. (See Patent Document 2). However, when the concave portion (projected portion) becomes deep, the effect becomes insufficient, and cracking and surface distortion during molding cannot be prevented. In addition, there is a problem that it cannot be applied to a general-purpose press device, and can only be applied to a special press device having a wrinkle pressing force control function.

  On the other hand, it has also been proposed that the temperature of the punch or mold part necessary for forming the recess (overhang) is heated to a temperature of 300 ° C. or lower (see Patent Documents 3 and 4). ) These techniques are also disclosed in the press molding difficulty handbook, and are techniques for locally suppressing a portion where surface distortion occurs to suppress surface distortion. However, the aluminum alloy has a large coefficient of thermal expansion, and has a new problem of causing distortion (thermal strain) at the boundary between the heated part and the non-heated part. Further, it is necessary to heat most of the mold, which increases the molding cost. For this reason, there was a great limit to the application to partially press-molding the recess including the continuous curved surface around the shape of the recess (overhang).

  On the other hand, in order to suppress the surface distortion when press-molding an aluminum alloy plate on an automobile panel, a combination of electromagnetic forming and normal press forming and electromagnetic forming in the same press forming process or in the same press apparatus A method is proposed in US Pat. In this method, the entire panel curved surface is formed by ordinary press forming, and subsequently, the partial formation of the concave portion (the overhanging portion) is performed by the press device using the electromagnetic forming coil incorporated in the press device. It is something to do while doing. At this time, together with the concave portion, the peripheral portion of the concave portion is combined and simultaneously subjected to electromagnetic forming to suppress the occurrence of the surface distortion.

JP-A-6-304777 JP 9-225549 A JP-A-9-164445 JP 2008-254001 A Japanese Patent No. 4061189

  If the electromagnetic forming method as described in Patent Document 5 can be applied to the forming of an aluminum alloy panel, various problems of forming defects such as cracks and shape defects can be solved. However, a large area electromagnetic forming technology such as an automotive aluminum alloy panel has not yet been put into practical use. This is because even if electromagnetic forming is partially used, electromagnetic forming itself is not yet common, the size of the electromagnetic coil corresponding to the outer panel part to be formed is limited, and the production cost of the electromagnetic coil is high, This is because the coil life is not so long. Accordingly, even when combined with press molding as described above, the molding cost of an aluminum alloy automobile panel is still high. In addition, there is a large practical problem that it cannot be applied to a general-purpose press device and can only be applied to a special press device equipped with an electromagnetic coil. In electromagnetic forming, electromagnetic force acts isotropically and symmetrically, and in an asymmetrical shape, a surplus of material is partially generated and significant wrinkles may be generated, so that applicable shapes are limited.

  Therefore, at present, there is no effective integral molding method for avoiding surface distortion in an aluminum alloy outer panel in which an overhang portion having a predetermined depth is partially provided. For this reason, in order to avoid surface distortion caused by integral molding, various circumvention measures have been taken so far, such as escape by design or bypass by molding separately. For example, there is a workaround in which only the concave portion (projecting portion) of the panel is divided and molded, and then joined to the panel main body separately molded by welding. In addition, in order to absorb the predicted surface distortion, there is a workaround such as providing an uneven line shape called a separate character line along the surface distortion generation part, which is extra in the original design shape.

  However, the division molding / joining of the recesses (projecting parts) and the installation of the character line restrict various appearances such as the outer panel appearance and design itself, and also reduce the strength of the joints and the rigidity of the outer panel. There is. In addition, as compared with the case where the overhang portion is integrally molded, there is a large problem that the molding process itself becomes complicated, such as an extra process. Therefore, the problem of such surface distortion has been a major factor that hinders the application of aluminum alloy plates to automobile outer panels.

  The present invention has been made paying attention to such circumstances, and the object thereof is to integrally form an aluminum alloy panel of an automobile or the like while suppressing the surface distortion of the recessed portion such as the overhanging portion. An object of the present invention is to provide a method for forming an aluminum alloy plate.

The summary of the method for forming an aluminum alloy plate of the present invention for achieving the above object is to provide an aluminum alloy plate for an automobile outer panel selected from a door, luggage, fender, hood, and trunk lid having a concave portion in a continuous curved surface. Using a first male die and a female die, and after forming a curved surface other than the concave portion, the concave portion is formed using a second male die and a female die. When partially forming by overhang processing ,
After pressurizing the curved surface other than the concave portion with a presser mold, the molding surface of the second male mold is heated to a temperature of 150 to 400 ° C., and the molding position of the aluminum alloy plate in the concave portion is 150. While partially heating to a temperature of ˜400 ° C., the second female die and the presser die are at a temperature of 100 ° C. or less and 100 ° C. than the heating temperature of the second male die. It is held or cooled to a temperature lower by at least ° C. to suppress the occurrence of surface strain associated with the formation of the recess.

  Here, when the concave portion is formed by overhanging, the molding surface of the second male mold is heated to 150 to 400 ° C., and the molding position of the aluminum alloy plate in the concave portion is changed to the temperature. It is preferable to heat partially. Further, when the concave portion is formed by overhanging, it is preferable to pressurize the molding curved surface other than the concave portion to 0.6 MPa or more with a presser mold having a shape corresponding to the molding curved surface. Further, when the concave portion is formed by overhanging, the second female die and the presser die are at a temperature of 100 ° C. or lower and the heating temperature of the second male die is 150 to 400 ° C. Also, it is preferable to hold or cool at a temperature lower by 100 ° C. or more.

  After forming the curved surface other than the concave portion, the step of partially forming the concave portion is continuously performed in the same press apparatus, and in the first female mold for molding the curved surface other than the concave portion, A second male mold for forming the concave portion by overhanging is divided and provided so as to be able to advance and retract independently, and the second female mold is provided in the first male mold. After forming the curved surface other than the concave portion using the first male mold and the first female mold, the second male mold whose molding surface is heated to 150 to 400 ° C. is used as the second male mold. It is preferable that the concave portion is partially formed by overhanging using the first male die and the first female die as the presser die. In the above method for forming an aluminum alloy plate of the present invention, the automobile panel is preferably an outer panel.

  In the present invention, a recess (overhanging portion) that is likely to generate surface distortion during the press molding described above is selected in the automobile panel, and a partial molding of the recess is performed by molding a curved surface other than the recess. At a later time, a portion of the aluminum alloy plate to be formed into the recess is partially heated, and then formed by overhanging.

  As described above, the surface distortion is caused by material inflow when the concave portion is formed by drawing or the like as well as forming the curved surface of the entire panel.

  On the other hand, the present invention is a projecting process in which the formation of the curved surface of the entire panel is formed by drawing or the like, but the partial forming of the recess is separated as a process to suppress the material inflow as described above. Molded with However, when performing overhang processing, it is necessary to suppress the material inflow to the molding part, and it is usually done by arranging beads on the outer periphery of the molding part, but the outer peripheral part of the concave part to be molded in this case is The product surface on which the curved surface of the entire panel has already been formed, the beads that obstruct the product surface shape cannot be disposed, and the material inflow due to the beads cannot be suppressed.

  For this reason, this invention suppresses the said material inflow by partially heating the shaping | molding location to this recessed part of an aluminum alloy plate instead of this bead, and reducing the intensity | strength (proof stress) of material. As a result, the curved surface shape of the entire panel formed in advance by drawing or the like is maintained, and the occurrence of surface distortion associated with the formation of the recess is suppressed. In this invention, since only this recessed part is heated partially, heating may be minimal, the whole panel is not heated, and the intensity | strength (proof strength) of the whole panel does not fall.

It is sectional drawing of the press apparatus which shows the one aspect | mode of the press molding of this invention aluminum alloy plate blank. It is a top view which shows the aspect of the door outer panel 11 shape | molded by the press apparatus of FIG. It is a top view which shows another aspect of the shape | molded door outer panel. It is sectional drawing of the press apparatus which shows the one aspect | mode of the press molding of the door outer panel 11 of FIG. It is a perspective view of the automobile panel which illustrates the panel which can apply the present invention. It is explanatory drawing which shows the generation | occurrence | production mechanism of a surface distortion. It is sectional drawing which shows the comparative example press apparatus which shape | molds the whole shape and recessed part of a panel simultaneously.

Embodiments of the present invention will be described below with reference to the drawings.
FIGS. 1A and 1B show a curved surface press molding other than the concave portion of the present invention and the concave portion press molding continuously in the same press apparatus, and are shown in a plan view in FIG. A mode of forming the automobile outer panel 11 is shown in order. 1 and 2, the recess 14 is a door outer panel handle.

(Press machine)
1 (a) and 1 (b) have a second male mold and a female mold for forming the recess, and a first male mold and a female mold for forming the entire curved surface shape of the panel. It shows an aspect in which the press molding of the curved surface other than the concave portion 14 of the aluminum alloy plate 1 and the subsequent press molding of the concave portion are carried out continuously in the press molding step by being incorporated in the press device.

  In addition, after shape | molding curved surfaces (whole curved surface) other than the said recessed part using a 1st male die and a female die, the said recessed part is partially used using a 2nd male die and a female die. When forming into a pressing device having a first male die and a female die, and a pressing device having a second male die and a female die, respectively, as in the embodiments to be described later, respectively. It is also good.

  First, in FIGS. 1A and 1B, 2 is a die that is a first female mold, 3 is a punch that is a first male mold, and 4 is a wrinkle presser. The drawing process for forming the entire 11 curved surface shape is performed.

  Next, 3a is the 2nd female metal mold | die which carries out an overmolding of the said recessed part 14, and it is provided in the position corresponding to the said recessed part 14 shaping | molding of the aluminum alloy plate 1 in the punch 3 which is a 1st male metal mold | die. Yes. Reference numeral 5 denotes a punch 5 which is a second male mold for overmolding the concave portion 14 and is provided in a space in the die 2 which is a first female mold. The punch 5 is provided at a position corresponding to the formation of the concave portion 14 of the aluminum alloy plate 1 so as to be separated from the die 2 and to be independently advanced and retracted. Further, the peripheral portion of the punch 5 of the die 2 that becomes a plate pressing type in the overhanging process of the concave portion 14 is divided from the die 2 main body and can be moved independently as indicated by the alternate long and short dash line. ing.

  Further, 6 is a heater for heating the molding surface of the tip 5a of the punch 5 which is the second male mold. Reference numeral 7 denotes a first female die 3a for overhanging the concave portion 14 and a peripheral portion 3b for cooling, for example, a cooling circuit in which cooling water circulates is incorporated in the first female die 3a. Device.

  Reference numeral 1 denotes an aluminum alloy plate to be formed or being formed, and reference numeral 1a denotes a formed portion corresponding to the recessed portion to be stretch-formed. Reference numeral 14 denotes the projecting recessed portion (door outer panel handle seat), and 14a denotes the peripheral portion (flat portion) of the recessed forming portion.

(Press molding method)
In the press molding method of the present invention, first, as shown in FIG. 1A, the aluminum alloy plate 1 is drawn into the entire curved surface of the automobile outer panel 11 shown in FIG. This press molding itself is the same as a conventionally known method, and the drawing is performed by the cooperation of the punch 3 as the first male die, the die 2 as the female die, and the wrinkle retainer 4 of the aluminum alloy plate 1. Processing is performed. At this time, although not shown, a draw bead (19) on the outer periphery of the product shape as shown in FIG. 3 described later is provided on the wrinkle retainer 4 so that the amount of material flowing into the die 2 from the outer periphery of the product shape is reduced. Be controlled.

(Recess molding method)
After such drawing processing, as shown in FIG. 1 (b), the concave portion (projecting portion) 14 of the door outer panel 11 is formed by a punch 5 which is a second male die and a female die 3a. Partially stretched and molded. At this time, the peripheral portion 14a around the concave portion 14 is low in temperature compared with the concave portion, and thus has a high yield strength and is held by the holding die, so that the material inflow into the concave portion can be suppressed, and the drawing process can be performed in advance. By maintaining the curved shape of the entire molded panel, the occurrence of surface distortion can be suppressed.

  Here, in the present invention, the forming surface of the tip 5a of the punch 5 is heated by the heater 6 so that only the forming portion 1a to the concave portion 14 of the aluminum alloy plate 1 is partially within the temperature range of 150 to 400 ° C. Heat to. On the other hand, the cooling device 7 cools the first female die 3a for projecting the concave portion 14 and its peripheral portion 3b. As a result, heat diffusion to the recessed portion 14 of the aluminum alloy plate 1 other than the forming portion 1a is prevented, and only the forming portion 1a can be partially heated. Here, the region to be heated (required for heating) is only the molding part 1a, but it may be difficult to heat only the region of the molding part 1a strictly. It is possible to spread slightly to the part. Therefore, such a case is also included in the scope of the present invention.

  If the heating temperature of the molding part 1a to the concave part 14 of the aluminum alloy plate 1 is less than 150 ° C., the strength (proof strength) of the material of the molding part to the concave part 14 is not sufficiently lowered regardless of the aluminum alloy. For this reason, the material inflow into the female die 3a in the overhanging process cannot be suppressed. Therefore, it is not possible to suppress the occurrence of surface distortion associated with the formation of the recess 14.

  On the other hand, when the heating temperature is higher than 400 ° C., the strength (proof strength) of the material at the molding position in the recess is too low. For this reason, it becomes difficult to maintain the shape of the recess 14. Further, due to the expansion of the softening of the peripheral edge of the recess 14 due to thermal diffusion and the decrease in the strength of the recess 14, the strength (proof strength) of the entire panel may also decrease.

  Here, in order to partially heat only the forming portion 1a to the concave portion 14 of the aluminum alloy plate 1 in the temperature range of 150 to 400 ° C. by a short contact by forming, the tip 5a of the medium punch 5 is used. The heating temperature of the molding surface may be higher than this temperature range.

  The aluminum alloy plate 1 may be heated in advance by a contact heater, high-frequency heating, or the like. However, depending on the cooling means, only the forming portion 1a to the concave portion 14 of the aluminum alloy plate 1 is 150 to 400 by thermal diffusion. It is difficult to partially heat in the temperature range of ° C. Further, it is difficult to keep only the forming portion 1a of the aluminum alloy plate 1 in the recess 14 in this temperature range during the overhanging process.

  In this regard, if the heating method of the forming surface of the tip 5a of the punch 5 by the heater 6 or the like is used, only the forming portion 1a to the recess 14 of the aluminum alloy plate 1 is combined with the cooling device 7 in the temperature range. In part, it can be held during heating and overhanging.

  In this case, the cooling of the second female die (extrusion molding surface) 3a and its peripheral surface (peripheral molding surface) 3b, which becomes a presser mold of the plate in the extension processing to the recess 14, is 100 ° C. It is preferable to hold or cool at a temperature below 100 ° C. or more lower than the heating temperature 150 to 400 ° C. of the second male mold. For this purpose, as described above, the cooling devices 7 respectively provided on the peripheral portion of the punch 5 of the die 2 and the peripheral portion 3b of the first female die 3a for projecting the concave portion 14 are controlled. To adjust the temperature of these points.

  If the cooling condition is not met, cooling of the second female mold (extrusion molding surface) 3a and the peripheral surface (peripheral molding surface) 3b becomes insufficient, and these temperatures rise. For this reason, softening of the peripheral part of the recessed part 14 by thermal diffusion is expanded, the strength of the peripheral part is lowered, and on the contrary, the amount of material inflow is increased, and surface distortion is likely to occur. Further, due to the expansion of the softening of the peripheral edge of the recess 14 due to thermal diffusion and the decrease in the strength of the recess 14, the strength (proof strength) of the entire panel may also decrease.

  In the overhanging process to the concave portion 14, the pressing force of the peripheral surface (peripheral molding surface) 3 b of the second female die 3 a that becomes the presser die of the plate, or further expanded, is applied to the die 2 (with the one-dot chain line) It is preferable that the pressing force (the pressing force as the presser die) on the surface of the punch 3 in the die 2 shown in FIG. If these pressures are small, depending on the conditions, the material inflow into the female mold 3a in the overhanging process of the recess 14 can not be sufficiently suppressed, the curved shape of the entire pre-formed panel cannot be maintained, There is a possibility that the occurrence of surface distortion cannot be suppressed.

  Here, the peripheral surface (peripheral molding surface) 3b of the second female die (extension molding surface) 3a in the punch 3 is flat in order to mold the flat portion 14a around the overhanging portion. However, the peripheral portion 14a around the overhang portion 14a is not necessarily flat as in this aspect, depending on the design shape of the panel and the panel application, and may have an arbitrary oblique side shape or curved surface shape. In such a case, the peripheral surface (peripheral molding surface) 3b of the second female mold (extrusion molding surface) 3a does not necessarily have to be a flat portion as in this embodiment, and corresponds to the shape of the peripheral portion 14a. Arbitrary shape.

  FIG. 2 is a plan view showing the door outer panel molded product 11 molded in this manner. In the molded article 11, the occurrence of surface distortion accompanying the molding of the overhanging portion 14 is suppressed, the convex portion Y as shown in FIG. 6C is not generated, the flatness of the automobile panel, etc. Excellent shape accuracy and aesthetics. In addition, since the generation of surface distortion is suppressed by such a concave portion forming method, deeper (higher) and larger concave portions can be formed (overhang processing) as compared with press molding. The advantage of increasing the degree of freedom in designing the shape of the recess (projecting portion) is also great.

  According to this aspect, since the press apparatus to be used can be modified only by partially providing the punch 5 and the female mold 3a, which are the second male mold, to the existing press apparatus, It is not necessary to modify the press device.

  The method of forming the door outer panel has been described above. According to the present invention, the license seat 15 and the lamp seat 16 of the luggage outer panel 12 are shown in FIG. 5B, and the wheel arch 17 of the fender outer panel 13 is shown in FIG. It can be applied in the same manner to the molding of other automobile outer panels.

  In addition to the continuous forming method described above, the door outer panel is manufactured in advance by press forming of an aluminum alloy plate, and the overhanging portion of the door outer panel is subjected to overhang processing separately or in a separate process. May be produced.

  The aluminum alloy used for forming in the present invention is generally used for applications such as this kind of structural material. Aluminum alloys such as 5000 series and 6000 series defined in AA to JIS standards have high formability and high strength. It is preferable at the point which combines. An Al—Mg-based 5000-based aluminum alloy is preferable in that it has a high work-hardening amount during molding and high formability. In addition, Al-Mg-Si 6000 series aluminum alloy has artificial age hardenability (bake hardness), making it easy to form in a low yield strength state, and increasing the yield strength by artificial age hardening treatment after forming. This is preferable. Of course, other aluminum alloys can be formed, and can be selected according to the application and required characteristics.

  Examples of the present invention will be described below. For the automobile door outer panel 11 having the shape and dimensions shown in FIG. 3, the entire shape having a continuous curved surface was formed by a normal press device. Then, after that, the handle seat 14 as the concave portion, which is a molding object of the present invention, is subjected to a partial molding test using a press device shown in cross section in FIG. The state of occurrence of distortion was evaluated. These partial molding conditions and molding results are shown in Table 1.

  The forming aluminum alloy plate was a 6000 series aluminum alloy plate of AA6022-T4 tempered material having a 0.2% proof stress of 150 MPa. As shown in FIG. 3A, which is the AA cross section of FIG. 3B, the product panel 11 excluding the peripheral edge portion removed by trimming is an arc-shaped curved surface having a continuous curved surface (cross section) of R1000 mm. . 3B, the overall planar shape of the panel 11 is a rectangular parallelepiped shape having a width of 600 mm and a length of 1000 mm. And the handle seat 14 which is the said recessed part has the ellipsoid shape of length 100mm, width 50mm, and depth 15mm as illustrated in FIG.3 (b), (c).

  First, as described above, the material aluminum alloy plate was formed into an overall panel shape having the continuous curved surface of FIG. Although this press apparatus is not shown, the basic configuration is the same as that of the press apparatus in which the second male mold and the female mold for forming the recess in FIG. 1 are omitted. That is, the material aluminum alloy plate is formed into the overall shape of the panel having the continuous curved surface in FIG. 3 by the punch 3 as the first male die, the die 2 as the female die, and the aluminum in FIG. The drawing was performed by drawing together with the wrinkle retainer 4 of the alloy plate 1.

  Next, the panel 11 after the drawing was set in a press apparatus shown in FIG. 4, and the handle seat 14 was formed. 4 has the same basic configuration as that of the apparatus for partially projecting the recess 14 in the press apparatus of FIG. That is, the handle seat 14 was partially stretched and molded by the punch 5 as the second male mold and the female mold 3a. At this time, the punch 3 corresponding to the first male mold and the die 2 corresponding to the female mold in the press apparatus shown in FIG. 4 have a shape corresponding to the overall shape of the panel 11 having a continuous curved surface. The panel 11 has a presser type.

  At this time, the forming surface of the tip 5a of the punch 5 was heated by the heater 6 built in the punch 5, and only the forming portion 1a of the aluminum alloy plate 1 on the handle seat 14 was partially heated. On the other hand, the second female die 3a and the presser die 2 for extending the handle seat 14 were cooled by the cooling device 7 that circulates the cooling water through the built-in pipe. Then, by the advancement / retraction of the punch 5, only the portion of the handle seat (extended portion) 14 was overmolded in cooperation with the female die 3 a.

  At the time of this molding, as shown in Table 1, the heating temperature of the tip 5a of the punch 5, the pressure and temperature of the presser mold 3b which is the peripheral molding surface of the handle seat 14 serving as a presser mold, the female mold 3a This was done by changing the temperature. Here, the heating temperature at the tip 5a of the punch 5 is equal to the temperature at which the tip 5a of the aluminum alloy plate 1 is formed on the handle 14 so that the tip 5a of the punch 5 contacts the molding 14 on the handle 14. Molding was performed after securing the time in advance.

  The state of occurrence of surface distortion of the handle seat 14 after molding was evaluated. The surface distortion is evaluated by measuring the shape at 4 peripheral positions 5 mm away from the end of the handle 14, which is the recess, as shown in FIG. 3C, and determining the difference from the shape of the female die 3 a. According to the size of the maximum value (mm), evaluation was made in four stages from ◎ to ×. ◎ is 0.2 mm or less, ◯ is 0.2 mm to 0.5 mm, Δ is 0.5 mm to 1 mm, and x is 1 mm.

  As shown in Table 1, in Invention Examples 1 to 6 molded under preferable conditions, occurrence of surface distortion is suppressed. Further, among the invention examples, the heating temperature of the tip 5a of the punch 5, the pressing force of the peripheral molding surface 3b of the handle seat 14 serving as a presser mold, the temperature of the peripheral molding surface 3b, the temperature of the female die 3a, etc. Inventive Examples 1 and 2 that satisfy all of the preferred ranges hold the curved surface shape of the entire pre-formed panel, and suppress the occurrence of surface distortion, compared to Inventive Examples 3 to 6 in which either one is removed. Has been.

  On the other hand, in Comparative Examples 11 and 12, the heating temperature of the tip 5a of the punch 5 that is the heating temperature of the plate is too low. In Comparative Example 13, the temperature of the surrounding molding surface 3b and the temperature of the female die 3a are too high. Therefore, in these comparative examples, although the plate is partially heated and molded, the occurrence of surface distortion is not suppressed.

  For comparison, the second male die 8 and the female die 9 for forming the handle seat (concave portion) 14, the punch 3, the die 2, and the like as shown in the sectional view of FIG. In addition, the example in which the entire shape of the panel 11 and the handle seat 14 are formed at the same time was also implemented. In this example, as in the invention example, the die protrusion 8 corresponding to the tip of the second male mold is partially heated by the heater 6 built in the die 2, and the handle of the aluminum alloy plate 1 is thus obtained. The molding part to the seat 14 was heated to the temperature shown in Table 1. Further, the cooling device 7 that circulates cooling water through a pipe built in the punch 3 cooled 9 corresponding to the second female die 3a for extending the handle seat 14 and its peripheral portion. However, as can be seen from Table 1, in the method of simultaneously molding the overall shape of the panel 11 and the handle seat 14 as in Comparative Examples 9 and 10, even if the molding location on the handle seat 14 is partially heated, The curved shape of the entire molded panel is not maintained, and the occurrence of surface distortion is not suppressed.

  From the above results, the significance for suppressing the occurrence of surface distortion between the requirements of the present invention and the preferable requirements is supported.

  As described above, according to the present invention, it is possible to provide a molding method capable of molding a partial recess with respect to the overall shape of an aluminum alloy panel such as an automobile having a continuous curved surface while suppressing surface distortion. For this reason, it can be suitably used for molding various automobile panel parts that are likely to cause surface distortion.

1: Aluminum alloy plate, 2: Mold, 3: Punch, Wrinkle retainer, 5: Punch, 6: Heater, 7: Cooling means, 11: Door outer panel (panel molded product), 12: Luggage outer panel, 13: Fender outer panel, 14: Handle seat (concave), 15: License seat, 16: Lamp seat, 17: Wheel arch, X: Surface distortion, Y: Convex

Claims (3)

A method of forming an aluminum alloy plate on an automobile outer panel selected from a door, luggage, fender, hood, and trunk lid having a concave portion on a part of a continuous curved surface, the first male mold and female mold after forming a curved surface other than the recess with the door, upon partially molded with overhanging processed with the recess and the second male mold and female mold, a curved surface other than the recess After pressurizing with the presser mold, the molding surface of the second male mold is heated to a temperature of 150 to 400 ° C., and the molding site of the aluminum alloy plate to the concave portion is set to a temperature of 150 to 400 ° C. While partially heating , hold the second female mold and presser mold at a temperature of 100 ° C. or lower and at a temperature 100 ° C. or lower than the heating temperature of 150 to 400 ° C. of the second male mold. Or cool Method of forming an aluminum alloy plate, characterized in that to suppress the occurrence of distortion surfaces due to molding of the recess. The method for forming an aluminum alloy plate according to claim 1 , wherein the pressing force of the presser mold is 0.6 MPa or more. After forming the curved surface other than the concave portion, the step of partially forming the concave portion is continuously performed in the same press apparatus, and in the first female mold for molding the curved surface other than the concave portion, A second male mold for forming the concave portion by overhanging is divided and provided so as to be able to advance and retract independently, and the second female mold is provided in the first male mold. After forming the curved surface other than the concave portion using the first male mold and the first female mold, the second male mold whose molding surface is heated to 150 to 400 ° C. is used as the second male mold. It brought close to the female mold, with the first male mold and the first female mold as the pressing mold, the recess in claim 1 or 2, partially forming at the projecting processing The forming method of the aluminum alloy plate as described.

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