JP5435981B2 - Partial restoration processing equipment for aluminum sheet blank sheet for cold press forming - Google Patents

Description

  The present invention relates to an apparatus for performing a heat treatment for partial restoration processing on a blank sheet made of an aluminum alloy rolled plate of Al-Mg-Si (No. 6000) used by performing cold press forming. In particular, various members and parts of automobiles, ships, aircraft, etc., or building materials, structural materials, other various machinery and equipment, electrical products members, parts, etc., especially Al- which is suitably used for automobile body sheets and body panels The present invention relates to an apparatus that performs a partial restoration process for improving the cold press formability of an Mg—Si based aluminum alloy sheet blank sheet.

Conventionally, cold rolled steel sheets were often used as body sheets and body panels for automobiles. Recently, however, reduction of CO ₂ gas emissions has been strongly demanded from the viewpoint of suppressing global warming, and at the same time, the fuel efficiency of automobiles has been reduced. There is a need for improvement, and therefore there is a strong demand for weight reduction of automobiles. Therefore, for these uses such as body sheets and body panels for automobiles, it is desired to use light aluminum alloy rolled sheets instead of conventional cold-rolled steel sheets. However, the formability of an aluminum alloy rolled sheet is generally inferior to that of a cold-rolled steel sheet. For this reason, the aluminum alloy rolled sheet is currently used only for parts that do not require high formability.

  By the way, various measures for improving the formability of an aluminum alloy rolled sheet, particularly cold press formability, have been proposed. Among these, recent measures that can improve press formability relatively effectively include the development of a texture improving material using warm differential circumferential rolling, and the heating of blank sheets using a press die incorporating a heater. There is a warm press molding method (for example, Patent Literature 1, Patent Literature 2 and the like) or a warm blow molding method of pressing while pressing. However, among these measures, the method of applying the warm different speed rolling is still difficult to apply to large members such as body sheets because the enlargement of the different speed rolling mill has not been achieved yet. . In addition, the latter warm press molding method and warm blow molding method are both very slow compared to ordinary cold press molding, so it is difficult to apply on a mass production scale and produce in small quantities. The reality is that it is limited to luxury cars.

  On the other hand, recently, with respect to aluminum alloy rolled sheets used for cold press forming, by performing a partial recovery process (partial recovery process) in advance before cold press forming, It has been found that even if cold press molding is applied, the formability can be dramatically improved, and the applicant of this application has filed a patent application (unpublished) as Japanese Patent Application No. 2008-226006.

Here, the term “restoration” means that an age-hardening type aluminum alloy plate represented by the Al—Mg—Si based aluminum alloy, which is the subject of the present invention, is rapidly cooled after solution treatment, and the alloying element is dissolved in a supersaturated state at room temperature. After making it into a state of being allowed to stand, at room temperature (ordinary aging temperature) or slightly higher (artificial aging temperature), extremely fine precipitates (mainly Mg ₂ Si-based precipitates) are precipitated in the matrix. It means a phenomenon in which after the strength is improved, fine precipitates are re-dissolved by heating to a temperature higher than the holding temperature for a short time (restoration heat treatment), the strength is lowered, and the material is softened. And in order to raise | generate such a phenomenon, the process which heats the material after solution treatment-rapid cooling and holding | maintenance is called the restoration process. Here, the partial restoration heat treatment is not the entire aluminum alloy plate blank, but only a predetermined portion (region) in the plane thereof, which is selectively heated and restored, and only the predetermined portion. It means the treatment that softens.

  And in the invention of the patent application, the properties required for the aluminum alloy sheet blank sheet during cold press forming are not uniform throughout the entire surface of the blank, and a part where high strength is required partially, Focusing on the fact that there are some parts that are required to have low strength (soft) and good elongation, the surface can be obtained by partially restoring the aluminum alloy sheet blank sheet before cold press forming. It is based on the technology that gives the difference in strength.

  Specifically, among the whole Al-Mg-Si-based aluminum alloy rolled sheet blanks that have been rapidly cooled after solution treatment as described above to increase the strength as a whole by room temperature aging or artificial aging, All or at least a part of the area outside the area where the punch shoulder contacts is heated in the partial restoration process in order to facilitate the inflow of material from the pressing part around the drawing during cold press drawing. On the other hand, the area where the punch shoulder contacts is removed from the heating target part in the partial restoration process (that is, determined as the non-heating target part) in order to maintain high strength so as not to break easily during pressing, By performing a partial restoration process and performing cold deep drawing on a blank that has been optimized for strength distribution, When promoting material inflow to prevent simultaneous rupture of the material, thereby enabling the plate thickness to produce a uniform and deep diaphragm of the molded article.

  And according to the invention of the patent application, it is not only possible to improve the cold press formability by appropriately giving a strength difference in the plane of the Al—Mg—Si based aluminum alloy sheet blank sheet. However, since such partial restoration processing is performed as a separate process before cold press forming, press forming itself can be performed at high speed by a conventional cold press machine, and therefore, warm forming is performed. There is no increase in equipment cost or reduction in production efficiency as in the case of application, and there is no need for special lubricating oil. Furthermore, the shape freezing property of the molded product is improved due to the strength reduction of the wrinkle holding part, and the part that has become low strength due to the restoration phenomenon (the part to be heated) has a high curing speed at the time of paint baking, and the strength recovers rapidly. Therefore, high paint bake hardenability (BH property) can be obtained, and therefore strength deterioration after paint baking can be prevented. And, if bending is to be performed on a part of the molded product after press molding, by setting the part to be bent as a heating target part in the partial restoration process, It is also possible to improve the bending workability of the molded product.

  The specific partial restoration process conditions in the invention of the patent application include a temperature within a range of 150 to 350 ° C. (preferably at a temperature rising rate of 30 ° C./min or more (preferably 50 ° C./min or more)). (Temperature within the range of 180 to 350 ° C.), and after holding for 5 minutes or less (including 0 seconds) at the temperature within the range, 30 ° C./min or more (preferably 50 ° C./min or more, More desirably, it is necessary to cool to a temperature of 100 ° C. or lower at a cooling rate of 100 ° C./min or higher.

JP-A-4-351229 JP 2006-205244 A

  The partial restoration processing method proposed in the invention of the above-mentioned patent application has only just begun, and the process conditions have been established, but it is optimal for carrying out the method on an actual mass production scale. The fact is that the device has not yet been established.

  Here, in the partial restoration processing method according to the above-mentioned patent application, only a part of the blank sheet in the plane (the heating target part) is rapidly heated to a predetermined temperature to dissolve the fine precipitate, and after the heating, Although it is necessary to prevent reprecipitation by cooling to this point and sufficiently restore (soften) it, it is necessary to maintain high strength so that it is not affected by the heating for the non-heating target part. The conventional heating apparatus for heat treatment of a general aluminum alloy sheet is not suitable for carrying out such a special embodiment of heat treatment on a mass production scale.

  This invention was made against the background of the above circumstances, and as described above, the partial restoration process performed before the cold press forming was actually performed on the Al-Mg-Si alloy blank sheet for cold press forming. It is an object of the present invention to provide an apparatus suitable for reliable and effective implementation on a mass production scale.

The partial restoration processing apparatus for cold press-forming aluminum alloy sheet blank sheet according to the present invention basically has the entire Al-Mg-Si aluminum alloy rolled sheet as defined in claim 1. About the blank sheet for cold press forming consisting of an aluminum alloy plate made of aluminum alloy plate that is rapidly cooled after solution treatment and subjected to normal temperature aging or artificial aging to increase the strength, and in the plane of the blank sheet, cold press The whole area or at least a part of the area outside the area where the punch shoulder is in contact with the molding is defined as the heating target part, and at least the area where the punch shoulder is in contact is defined as the non-heating target part. The heating target part is heated to a temperature within a range of 150 to 350 ° C. at a temperature rising rate of 30 ° C./min or more, and the temperature within the range is 5 minutes or less (including 0 seconds). ) Is held, and then cooled to a temperature of 100 ° C. or lower at a cooling rate of 30 ° C./min or more, while the non-heating target portion is not heated, and is partially restored to perform a partial restoration process. In the processing device,
A pedestal for horizontally supporting the blank sheet, with a flat support surface formed on the upper surface ;
A heater is provided, which can be moved up and down to approach and separate from the pedestal, and is in local contact with the portion to be heated on the surface of the blank sheet on the support surface at the time of lowering. A heating block for heating to a temperature in the range of 150 to 350 ° C. at a temperature increase rate of at least 2 seconds;
After-heating cooling means for rapidly cooling the heating target part to a temperature of 100 ° C. or less at a cooling rate of 30 ° C./second or more after heating the heating target part by the heating block;
A temperature sensor for detecting the heating temperature of the part to be heated by the heating block;
Control means for controlling the heater according to the temperature detected by the temperature sensor;
And having
The cooling means after heating is configured to eject a cooling fluid onto a support surface of the pedestal through a plurality of small holes formed in the pedestal,
The heating block heated by the heater is lowered toward the blank sheet supported horizontally on the support surface of the pedestal, and the lower surface is pressed against the heating target part of the blank sheet to locally heat the heating target part. Then, the heating block is raised and separated from the heating target portion of the blank sheet, and the heating target portion is rapidly cooled by the post-heating cooling means.
Moreover, the partial restoration processing apparatus of the aluminum alloy blank sheet for cold press molding of invention of Claim 2 is the partial restoration processing apparatus of the aluminum alloy blank sheet for cold press molding of Claim 1, The said small hole The cooling fluid that is blown out from the base has a function of causing the blank sheet to float on the support surface when the blank sheet is carried in and out of the support surface of the pedestal.

Furthermore, the partial restoration processing apparatus of the aluminum alloy blank sheet for cold press forming of this invention includes the following aspects (1) to (12).
(1) Before Symbol partial reversion processing apparatus that include a non-heat target portion cooling means for cooling the non-heated object part.

(2) pre-Symbol heated while the block is heated it in contact with the heating target portion of the blank sheet, the temperature gradient is 5 ° C. / mm in the boundary area of the heating target portion and the non-heat target portion at that blank sheet A partial restoration processing apparatus configured as described above .

(3 ) In the partial restoration processing apparatus for cold-press-molding aluminum alloy blank sheet according to (1), the non-heating target part cooling means supplies a cooling fluid to the non-heating target part of the blank sheet on the support surface. A partial restoration processing apparatus configured to be sprayed.

(4) In the partial restoration processing apparatus for cold-press forming aluminum alloy blank sheet according to (3) , the non-heating target portion cooling means supplies the cooling fluid to the non-heating target of the blank sheet on the support surface. The partial restoration processing apparatus made into the structure sprayed toward the part near the boundary position with the heating object part in a part.

(5) In the partial restoration processing apparatus of the aluminum alloy blank sheet for cold press forming according to (3) or (4) , the non-heating target part cooling means also serves as the post-heating cooling means, and a heating block A partial restoration processing apparatus in which the cooling fluid is sprayed even after the heater is separated from the heating target portion of the blank sheet.

(6) As the post-heating cooling means, a post-heating cooling fluid spray pipe that sprays a cooling fluid toward the blank sheet immediately after the heating block leaves the heating target portion of the blank sheet is partially provided. Restore processing device .

(7) In the partial restoration processing apparatus for an aluminum alloy blank sheet for cold press forming according to (1) , the non-heating target part cooling means is at least heated among the non-heating target parts in the blank sheet on the support surface. The partial restoration processing apparatus comprised by the cooling block which can contact | abut to the area | region near a boundary position with an object part.

(8) before Symbol contacting surface to contact with the blank sheet in the heating block, partial restoration processing devices that are formed so as to form an annular as a whole along the outer side of the shoulder portion of the punch in the cold press forming.

(9) The contact surface to be in contact with the blank sheet in the heating block is not only an annular portion as a whole along the outside of the punch shoulder in cold press molding, but also locally in a region corresponding to the inside of the punch shoulder. The partial restoration processing apparatus formed in an automatic manner .

(10) before Symbol heating block, partial reversion processing device is constituted by a combination of dividable plurality of small blocks.

(11) to the lower surface of the front Symbol heating block, the separate member from the heating block and a high hardness, a sheet made of a highly heat conductive material is adhered, heating block through the sheet to be heated of the blank sheet The partial restoration processing apparatus comprised so that it might contact and the heating target part of a blank sheet might be heated.

(12) and pressure detecting means for detecting the contact pressure at lowers the pre Symbol heating block being in contact with the heating block to the blank sheet, heating of the blank sheet on the basis of the detected value of the pressure detecting means A partial restoration processing apparatus comprising pressure control means for controlling the contact pressure of the block.

  According to the partial restoration processing apparatus of the present invention, the Al-Mg-Si-based aluminum alloy blank sheet whose strength is increased as a whole by rapidly cooling and holding after the solution treatment is partially restored before cold press forming. The processing can be reliably and effectively performed on a mass production scale at an actual manufacturing site. Therefore, if the partial restoration processing apparatus of the present invention is used to perform partial restoration processing before cold press forming, By ordinary cold press forming, it is possible to efficiently produce a molded product having a uniform plate thickness and a deep drawing.

FIG. 1 is a schematic cutaway front view showing an overall configuration of a partial restoration processing state according to an embodiment of the present invention. FIG. 2 is a bottom view showing the heating block used in the partial restoration processing apparatus shown in FIG. 1 along the line II-II in FIG. FIG. 3 is a plan view showing an example of a blank sheet processed by the partial restoration processing apparatus shown in FIG. 4 (a) to 4 (c) are schematic front views showing step by step how the blank sheet shown in FIG. 3 is processed using the partial restoration processing device shown in FIG. FIG. 5 is a schematic front view showing a situation in the vicinity of the heating block of an embodiment in which the heating block is constituted by a plurality of small blocks and a sheet is attached to the heating block as another embodiment of the present invention. FIG. 6 is a bottom view showing another example of the heating block used in the partial restoration processing apparatus of the present invention at the same position as in FIG.

  Hereinafter, modes for carrying out the present invention will be described with reference to the embodiments shown in FIGS.

FIG. 1 shows an embodiment having a basic configuration of a partial restoration processing apparatus according to the present invention. On a base 1 made of a flat plate, for example, a planar shape as shown in FIG. A pedestal 5 for supporting the blank sheet 3 having substantially horizontal is disposed. The pedestal 5 is made of a material such as a refractory material having good heat insulation properties, and its surface (upper surface) is a flat and smooth support surface 5A on which the blank sheet 3 is placed. Further, near the surface of the pedestal 5, temperature sensors 7 such as a plurality of thermocouples are embedded for detecting the heating temperature of the blank sheet 3 at the time of heating in the partial restoration process. Further, on the pedestal 5, air or the like from the support surface 5 </ b> A to slightly float the blank sheet 3 on the support surface 5 </ b> A as a loading / unloading assisting means when the blank sheet 3 is loaded / unloaded onto the support surface 5 </ b> A. A large number of small holes 9 for blowing out the fluid are formed. The small holes 9 also serve as a post-heating cooling means (first post-heating cooling means) that blows out a cooling fluid for rapid cooling after heating in the partial restoration process, as will be described later. The pedestal 5 is provided with pressure detection means 11 such as a load cell for detecting a pressure (load) when a heating block 15 described later is pressed against the blank sheet 3 during the partial restoration process.

  On the other hand, on the upper surface side of the peripheral part of the base 1, a plurality of guide rods 13 for vertically ascending and descending a lifting platform 17 in which a heating block 15 to be described later is detachably installed are erected vertically. The elevator 17 can be moved in the direction in which the heating block 15 approaches and separates from the support surface 5A of the base 5 so that the elevator 17 can be moved up and down together with the heating block 15 by being guided by the guide rods 13. It is configured as follows. The lifting platform 17 can be moved up and down by a lifting drive means (not shown) such as a hydraulic cylinder or a motor / screw mechanism.

  The heating block 15 has a built-in temperature-controllable heater (temperature-regulating heater) 19, and the whole is made of a hard material having good thermal conductivity and, for example, graphite. On the other hand, it is detachably attached.

  Here, the heating block 15 is in contact with a predetermined region (heating target portion 3A) on the surface (upper surface) of the blank sheet 3 on the support surface 5A at the time of partial restoration processing, and only that portion has a predetermined temperature (described later). In order to heat to 150 to 350 ° C., preferably 180 to 350 ° C., as shown in FIG. The planar shape of the flat portion 15A in contact with the blank sheet 15 in FIG. 3 corresponds to the region to be heated in the partial restoration process in the plane of the blank sheet 15 (heating target portion 3A; see FIG. 3). It has been. Specifically, the shape of the flat surface (contact surface) 15A on the lower side is a shape along the outside of the punch shoulder at the time of cold press forming, that is, a shape similar to the contour of the punch shoulder and the punch. As a whole, it is formed in a substantially annular shape close to a rectangle so as to form a shape slightly larger than the contour of the shoulder.

  Further, the heating block 15 has a cooling fluid spray pipe 21 as a non-heating target part cooling means for cooling the area where the blank sheet 3 should not be heated during the partial restoration process, that is, the non-heating target part 3B. Is provided. The cooling fluid spray pipe 21 directs the cooling fluid such as cooling air downward at a position close to the inner wall surface 15B in the heating block 15 (that is, the heating target portion 3A in the non-heating target portion 3B in the blank sheet 3). It is configured to blow out toward the boundary.

  Such a non-heating target part cooling means (for example, the cooling fluid spray pipe 21) is not necessarily provided. However, if the non-heating target part cooling means is provided, as will be described later, the heating target is cooled. The temperature gradient in the vicinity of the boundary position between the part 3A and the non-heating target part 3B can be increased, especially when the heating target part 3A has a high heating rate or when the heating target part 3A is held at the heating temperature. Is relatively long, it is effective to increase the temperature gradient in the vicinity of the boundary as described above by providing such a non-heating target portion cooling means.

Further, the lifting platform 17 is provided with a deposit removing air blowing pipe 23 for spraying deposit removing air obliquely downward to the right on the surface of the blank sheet 3 on the carry-in side of the apparatus (right side in FIG. 1). It has been. Further, on the lifting platform 17, in order to rapidly cool the blank sheet 3 after the partial restoration processing on the carry-out side (left side in FIG. 1), post- heating cooling different from the first post-heating cooling means is performed. As means (second post-heating cooling means) , a cooling fluid spray pipe 25 is provided for blowing a cooling fluid such as cooling air obliquely downward.

  The small hole 9, the deposit removing air blowing pipe 23, and the cooling fluid blowing pipes 21 and 25 are each one or more pumps for sending cooling air or air through a pipe (not shown). It is connected to a fluid delivery device (not shown) composed of a blower or the like, and this fluid delivery device is configured so that the timing of blowing, the flow rate of fluid, the fluid temperature, etc. are controlled by a control unit (not shown). It has become.

  On the other hand, the heater 19 and the temperature sensor 7 built in the heating block 15 described above are also electrically connected to the above-described control unit (not shown) and detected by the temperature sensor 7 during the partial restoration process. The heater 19 is controlled according to the blank sheet temperature. Further, a pressure detecting means 11 such as a load cell provided on the base 5 is also electrically connected to a control unit (not shown), and a pressure value detected by the pressure detecting means 11 (pressing pressure of the heating block 15 against the blank sheet 3). ), A drive source (not shown) for driving the elevator 17 is controlled.

  When the partial restoration process is performed on the Al-Mg-Si alloy blank sheet for cold press forming using the partial restoration processing apparatus of one embodiment shown in FIGS. The operation and action will be described.

  First, the blank sheet to be treated will be described. The alloy of the blank sheet may be an Al—Mg—Si alloy having age-hardening properties, and the specific component composition is not particularly limited. In general, as described in Japanese Patent Application No. 2008-226006 already mentioned, it contains Mg 0.2-1.5%, Si 0.3-2.0%, and Fe 0.03-1.0. %, Mn 0.03 to 0.6%, Cr 0.01 to 0.4%, Zr 0.01 to 0.4%, V 0.01 to 0.4%, Ti 0.005 to 0.3%, Zn 0.03 It is desirable to use an aluminum alloy containing one or more selected from -2.5% and Cu 0.01-1.5%, with the balance being Al and inevitable impurities. In general aluminum alloys, B may be added at the same time as Ti in order to refine the ingot structure. In the case of this invention, it is not particularly problematic that B is contained in an amount of about 500 ppm or less.

In addition, the blank sheet Al-Mg-Si alloy plate subjected to the partial restoration process is cold-rolled to a predetermined plate thickness, and then subjected to a solution treatment (desirably within a range of a heating temperature of 480 to 590 ° C). And rapidly cooled to dissolve Mg ₂ Si, simple substance Si, etc., and then rapidly cooled to room temperature or a temperature close to room temperature (usually 50 ° C. or lower) to dissolve Mg, Si, etc. in a supersaturated state at room temperature. And a certain amount of clusters and fine precipitates are deposited by room temperature aging (natural aging; usually aging at a temperature in the range of 0 to 50 ° C.) for about 1 day or more, or artificial aging treatment (desirably The sub-aging state is set to 140 ° C. or lower), thereby increasing the strength of the entire plate as compared with the cold-rolled state.

  A blank sheet made of such an Al—Mg—Si alloy plate is subjected to a partial restoration process. In this case, the cold shoulder forming punch shoulder of the cold press forming mold is performed thereafter. The whole or at least part of the area outside the area where the part should abut (that is, the part to be usually sandwiched by wrinkle pressing) is defined as the heating target part 3A in the partial restoration process, while at least the punch shoulder part is in contact with it. The non-heating target portion 3B (usually, the entire region inside the heating target portion 3A or at least a part of the region inside the heating target portion 3A) is determined as the region to be processed. Then, as the heating block 15 of the partial restoration processing apparatus, a heating block 15 corresponding to the planar shape of the heating target portion 3A is prepared, and this is set on the lifting platform 17. That is, the heating block 15 is selected so that at least the planar shape of the flat contact surface 15A below it corresponds to the heating target portion 3A of the blank sheet to be subjected to the partial restoration process.

  The situation where such a blank sheet is processed by the partial restoration processing apparatus of the embodiment shown in FIG. 1 is shown step by step in (a), (b) and (c) of FIG.

  FIG. 4A shows a situation in which the blank sheet 3 is being carried into the apparatus from the right side of the drawing. The lifting platform 17 is at the rising end, and the heating block 15 is the support surface 5A of the base 5. It is in the state away from. Then, fluid such as air is blown out from a large number of small holes 9 in the pedestal 5, and the blank sheet 3 is carried on the support surface 5 </ b> A of the pedestal 5 while being floated while being kept substantially horizontal. At this time, the deposit removing air is blown out from the blowing pipe 23 provided on the lifting platform 17, and dust and the like existing on the surface of the blank sheet 3 are blown off.

  When the blank sheet 3 is loaded and the blank sheet 3 arrives at a predetermined position on the support surface 5A of the pedestal 5, the blowing of the floating fluid from the small hole 9 is stopped and the blank sheet 3 is supported. The surface is placed in contact with the surface 5A and placed horizontally. Then, the elevator 17 is lowered until the lower surface (contact surface 15A) of the heating block 15 contacts the surface of the blank sheet 3 and presses it with a certain pressure. The state at this time is shown in FIG.

  Here, when the elevator 17 is lowered as described above and the heating block 15 is pressed against the surface of the blank sheet 3, the pressing pressure is detected by the pressure detection means 11 such as a load cell provided on the pedestal 5. A lift drive source (not shown) is feedback-controlled so as to have a pressure. That is, heat is sufficiently transferred from the heating block 15 to the surface of the blank sheet 3, and local deformation is not generated on the surface of the blank sheet 3 due to the pressing pressure of the heating block 15 (for example, indentation is generated). The contact pressure between the two is adjusted within an appropriate range.

  Further, as described above, when the elevator 17 is lowered and the heating block 15 is pressed against the blank sheet 3, the heating target portion of the blank sheet is instantaneously contacted with the heating target portion 3A of the blank sheet 3 when the lower surface 15A of the heating block 15 contacts the heating target portion 3A. Specifically, in order to perform rapid heating of 3A, the heating target portion 3A rapidly moves at a temperature rising rate of 30 ° C./min or more (preferably 50 ° C./min or more, more preferably 100 ° C./min or more). The heater 19 of the heating block 15 is operated before the start of contact so that the temperature rises, and the surface temperature of the heating block 15 is raised to a predetermined temperature. Furthermore, when the heating block 15 contacts the heating target part 3A of the blank sheet 3 and starts heating the heating target part 3A, the heat is transmitted to the adjacent non-heating target part 3B in the same blank sheet 3. A cooling fluid, for example, cooling air, is blown out in advance from a cooling fluid spray tube 21 as a non-heating target portion cooling means so that the temperature of the portion does not rise.

  If the lower surface (contact surface) 15A of the heating block 15 is pressed against the heating target portion 3A of the blank sheet 3 as described above, the heating target portion 3A is rapidly heated and the temperature rises. Here, the heating temperature increase rate of the heating target portion in the partial restoration process is more preferably 100 ° C./min or more as described above, but the preheated heating block 15 is pressed against the heating target portion 3A. When the heating target portion 3A is heated, it can be rapidly heated at a remarkably high temperature increase rate of 30 ° C./second or more in practice.

  In this way, when the heating block 15 is pressed against the heating target portion 3A, the heating temperature is detected by the temperature sensor 7 embedded near the surface of the pedestal 5, and the temperature of the heating target portion 3A of the blank sheet 3 is determined in advance. The heater 19 is controlled by a control unit (not shown) so as to reach a predetermined restoration processing temperature, that is, a temperature within a range of 150 to 350 ° C. (preferably 180 to 350 ° C.). Thereby, the restoration process about the heating target part 3A of the blank sheet 3 is performed. That is, as described above, fine precipitates are re-dissolved in the Al matrix in the heating target portion 3A, and the portion is softened.

  On the other hand, about the non-heating target part 3B of the blank sheet 3, not only the heating block 15 does not contact but also a cooling fluid, for example, cooling air, is sprayed from the cooling fluid spray tube 21, so that the temperature does not rise. Therefore, the portion is restored and does not soften. However, when the heating temperature raising rate of the heating target portion 3A is relatively low, it may not be necessary to spray such a cooling fluid.

  Here, when the lower surface of the heating block 15 is pressed against the heating target part 3A of the blank sheet 3 and the temperature of the heating target part 3A rises, the heating sheet 15 moves from the heating target part 3A to the adjacent non-heating target part 3B in the blank sheet 3. Heat is transferred (thermal diffusion) while the non-heating target part 3B is forcibly cooled, so that a temperature gradient is avoided in the region near the boundary between the heating target part 3A and the non-heating target part 3B. I don't get it. If the temperature gradient in the vicinity of the boundary as described above is small, the temperature of the portion near the heating target portion 3A in the non-heating target portion 3B becomes high and the portion tends to soften, but as already described In addition, since the non-heating target portion 3B is a portion that comes into contact with the shoulder portion of the punch at the time of cold press forming, if this portion is softened (decrease in strength), there is a high possibility that the portion will be broken at the time of press forming. Similarly, if the above-mentioned temperature gradient is small, the temperature of the portion close to the non-heating target portion 3B in the heating target portion 3A tends to be low, and the restoration (softening) of that portion is not sufficient, and cold press molding is performed. At that time, sufficient elongation cannot be obtained at that portion. Therefore, it is desirable to make the temperature gradient near the boundary between the heating target portion 3A and the non-heating target portion 3B as large as possible. According to the experiments by the present inventors, in the case of a drawn product having a size that is usually used as a body panel or body seat of an automobile (generally, each side is about 1 m × 1 m or more), If the temperature gradient is 5 ° C./mm or more, it has been found that the effect of the partial restoration treatment can be sufficiently exerted.

  In order to increase the temperature gradient in the vicinity of the boundary in this way, in the apparatus of the embodiment, the cooling fluid spray pipe 21 as the non-heating target portion cooling means is positioned near the inner wall surface 5B in the heating block 15 as described above. Therefore, the cooling fluid is sprayed at a position close to the boundary with the heating target portion 3A in the non-heating target portion 3B of the blank sheet 3. In actual operation, the temperature near the boundary as described above can be selected by appropriately selecting and adjusting the type of cooling fluid (cooling air or cooling water, etc.), fluid temperature, spray flow rate, flow velocity, etc. What is necessary is just to control so that a gradient may be 5 degrees C / mm or more.

  However, when the heating temperature rise rate of the heating target part 3A is relatively small, even if the non-heating target part 3B is not forcibly cooled by such non-heating target part cooling means, the vicinity of the boundary as described above It may be possible to ensure a certain temperature gradient.

As described above, while forcibly cooling the non-heating target portion 3B of the blank sheet 3, the heating block 15 is pressed against the heating target portion 3A of the blank sheet 3, and the heating target portion 3A is 150 to 350 ° C. (preferably 180 ° C.). The partial restoration process for the blank sheet 3 is performed by heating at a temperature within a range of ˜350 ° C. for a predetermined time (5 minutes or less, including 0 seconds). And after the said predetermined time progress, the raising / lowering stand 17 is raised and the heating block 15 is separated from the surface of the blank sheet 3. FIG. At this time, the cooling fluid, for example, cooling air or cooling water is continuously blown out from the cooling fluid spray tube 21 described above. Further, at the same time when the heating block 15 is separated from the surface of the blank sheet 3, a cooling fluid, for example, cooling air or cooling water is blown out from the cooling fluid spray tube 25 as the second post-heating cooling means . Further, at the same time or immediately after this, cooling fluid, for example, cooling air, is blown out from a large number of small holes 9 formed in the pedestal 5 as first post-heating cooling means .

  Thereby, the entire blank sheet 3 (particularly the heating target portion 3A) is rapidly cooled. At this time, the cooling rate of the heating target portion 3A is 30 ° C./min or more (preferably 50 ° C./min or more, more preferably 100 ° C./min or more), and the cooling temperature is 100 ° C. or less. Adjust the temperature, flow rate, and flow rate of each cooling fluid.

Also, as described above, the blank sheet 3 on the pedestal 5 floats while maintaining the horizontal by blowing out fluid such as air from the many small holes 9 of the pedestal 5 as the first post-heating cooling means as described above. Thus, by appropriately applying a thrust force in the unloading direction (left side in the figure), the blank sheet 3 can be smoothly unloaded to the left as shown in FIG . Therefore, fluid such as air ejected from a large number of small holes 9 of the pedestal 5 as the first post-heating cooling means floats the blank sheet on the support surface when the blank sheet is carried in and out of the support surface of the pedestal. It also has a function to make it.

  In the above embodiment, the heating block 15 has been described as an integral body having a substantially annular shape as a whole, but the heating block 15 may be constituted by a plurality of small blocks that can be divided. That is, in actual production sites, it is normal to produce molded products of various sizes and shapes, and therefore the shape of the punch in cold press molding is usually of various sizes and shapes. It is. In that case, preparing a large number of heating blocks corresponding to the sizes and shapes of the punch and the molded product causes an increase in cost. Therefore, if the heating block 15 is configured by a combination of a plurality of small blocks, it is possible to cope with different sizes and different shapes with a common small block to a considerable degree, thereby reducing the cost. It becomes possible to plan.

  On the other hand, in the above-described embodiment, it has been described that the lower surface (contact surface 15A) of the heating block 15 is brought into direct contact (pressing) with the heating target portion 3A of the blank sheet 3. A sheet having a high hardness and high thermal conductivity, such as a diamond sheet, may be adhered to the lower surface, and the heating target portion 3A may be indirectly heated through the sheet.

  Thus, sticking a sheet having high hardness and high thermal conductivity to the lower surface of the heating block 15 is particularly effective when the heating block 15 is constituted by a plurality of small blocks that can be divided as described above. That is, when the heating block 15 is configured by combining a plurality of small blocks, a slight step is formed on the lower surface (contact surface) of the adjacent small blocks, or a notch-shaped small recess is formed. In such a case, when a heating block (comprising a plurality of small blocks) is pressed against the surface of the blank sheet and heated, the blank sheet surface may be deformed such as indentations. There is. On the other hand, if a sheet as described above is stuck so as to cover the entire lower surface of the heating block composed of a plurality of small blocks, it is possible to prevent deformation such as indentations on the blank sheet surface during pressing heating.

  Here, in FIG. 5, as described above, the heating block 15 is configured by a combination of a plurality of small blocks 27, and the entire surface is covered with the lower surface 15 </ b> A of the heating block 15 including the plurality of small blocks 27. The example which stuck the sheet | seat 29 of high hardness and high heat conductivity is shown.

  Furthermore, in the above-described embodiment, when heating the heating target part 3A by pressing the heating block 15 against the heating target part 3A of the blank sheet 3, the non-heating target part cooling means for forcibly cooling the non-heating target part 3B is used. As a specific configuration, a cooling fluid is sprayed from the cooling fluid spray tube 25 to the non-heating target portion 3B. Instead, a solid cooling block may be brought into contact with the non-heating target portion 3B. good. That is, a cooling block (not shown) made of a highly heat-conductive material such as metal in which a cooling medium such as cooling water is circulated is disposed inside the heating block 15 and is cooled as the heating block 15 is lowered. The block may be lowered, and the lower surface thereof may be pressed against the surface of the non-heating target part 3B of the blank sheet 3 so that the non-heating target part 3B is directly removed (cooled). . If the cooling block is used in this way, it is possible to cool the non-heating target portion 3B more effectively than when the cooling fluid is sprayed as described above, and to increase the temperature gradient in the vicinity of the boundary. In order to increase the temperature gradient in the vicinity of the boundary between the heating target portion 3A and the non-heating target portion 3B of the blank sheet 3 as described above, the cooling block may be disposed as close as possible to the inner surface of the heating block 15. desirable.

  Moreover, in the above-mentioned Example, the shape of the heating block 15 is made into the substantially cyclic | annular form, and this is the planar shape of 3 A of heating object parts of the blank sheet 3, and the outer side of the punch shoulder part at the time of cold press molding However, depending on the shape of the press-molded product, it may be narrowed like a small island, leaving some or several parts inside the blank sheet during cold press molding. A part or several places inside the non-heating target part 3B as described above in the sheet 3 may be separated from each other as a heating target part. In that case, in correspondence with the shape of the heating target portion that is like a small island on the inside, the small island is separated from the substantially annular heating block 15 on the inner side of the substantially annular heating block 15 as shown in FIG. For example, the small heating blocks 31 may be provided at one place or several places.

DESCRIPTION OF SYMBOLS 3 Blank sheet 3A Heating target part 3B Non-heating target part 5 Base 7 Temperature sensor 9 Small hole 11 Pressure detection means 15 Heating block 15A Contact surface 19 Heater 21 Non-heating target part cooling fluid spray pipe 25 Fluid heating for cooling after heating Tubing 31 Small heating block

Claims (2)

Covering the whole sheet of Al-Mg-Si-based aluminum alloy rolled sheet for cold press forming blank sheet made of aluminum alloy sheet that is rapidly cooled after solution treatment and subjected to room temperature aging or artificial aging to increase strength. In the plane of the blank sheet, all or at least a part of the area outside the area where the punch shoulder is in contact during cold press molding is defined as the heating target area, and at least the punch shoulder is in contact The region to be used is determined as a non-heating target part, and the heating target part is heated to a temperature within a range of 150 to 350 ° C. at a temperature rising rate of 30 ° C./min or more, and the temperature within the range is 5 After holding for less than a minute (including 0 seconds), while cooling to a temperature of 100 ° C. or less at a cooling rate of 30 ° C./min or more, the non-heating target part is not heated, In the partial reversion processing apparatus for performing a partial restitution process,
A pedestal for horizontally supporting the blank sheet, with a flat support surface formed on the upper surface ;
A heater is provided, which can be moved up and down to approach and separate from the pedestal, and is in local contact with the portion to be heated on the surface of the blank sheet on the support surface at the time of lowering. A heating block for heating to a temperature in the range of 150 to 350 ° C. at a temperature increase rate of at least 2 seconds;
After-heating cooling means for rapidly cooling the heating target part to a temperature of 100 ° C. or less at a cooling rate of 30 ° C./second or more after heating the heating target part by the heating block;
A temperature sensor for detecting the heating temperature of the part to be heated by the heating block;
Control means for controlling the heater according to the temperature detected by the temperature sensor;
And having
The cooling means after heating is configured to eject a cooling fluid onto a support surface of the pedestal through a plurality of small holes formed in the pedestal,
The heating block heated by the heater is lowered toward the blank sheet supported horizontally on the support surface of the pedestal, and the lower surface is pressed against the heating target part of the blank sheet to locally heat the heating target part. Then, the heating block is raised and separated from the heating target portion of the blank sheet, and the heating target portion is rapidly cooled by the cooling means after heating, and the aluminum alloy blank for cold press forming is characterized in that Sheet partial restoration processing device. In the partial restoration processing apparatus of the aluminum alloy blank sheet for cold press forming according to claim 1,
The cooling fluid blown out from the small holes also has a function of floating the blank sheet on the support surface when the blank sheet is carried in and out of the support surface of the pedestal. Partial restoration processing equipment for aluminum alloy blank sheet for hot press forming.

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