JP5342161B2 - Method for producing aluminum alloy automotive panel member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing an aluminum alloy panel member for an automobile capable of stably press-forming the aluminum alloy panel member for an automobile by surely preventing cracks and wrinkles from occurring during the press working of an Al-Mg-based aluminum alloy sheet and manufacturable at low cost by reducing a manufacturing time. <P>SOLUTION: The panel member for an automobile is manufactured by continuously performing a working by a blank cut step, a working by a local heating step, a working by a cooling step, and a working by a press working for the Al-Mg-based aluminum alloy sheet in a cold-rolled state. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a method for manufacturing an aluminum alloy automobile panel member suitable for use in an automobile body panel.

  In recent years, automobiles have a tendency to increase in body weight with each model change due to the background of improvement in safety and enhancement of comfort equipment, which causes deterioration of fuel consumption. In addition, in the body field of the entire transportation equipment including automobiles, improvement of fuel efficiency by pursuing light weight is pursued for global environmental problems caused by exhaust gas and the like. Therefore, instead of the steel plate conventionally used for the body of a transport machine such as an automobile, a lighter aluminum alloy plate is adopted as a rolled plate or extrusion mold material used for the body of a transport machine such as an automobile. A lot is happening.

  Of these, high-strength Al-Mg-based aluminum alloy plates are used for body panels such as outer panels (outer plates) and inner panels (inner plates) such as automobile hoods, fenders, doors, roofs, and trunk lids. Is being considered.

  Conventionally, an Al-Mg aluminum alloy sheet is a process in the order of melting / casting → homogenization treatment → hot rolling → cold rolling, or a process including intermediate annealing between the hot rolling and cold rolling. Then, after a predetermined plate thickness, a product that has been heat-treated in a batch-type or continuous-type annealing furnace has been commercialized in the state of a coil or a sheet.

  This coil- or sheet-like product is cut into a predetermined size by a press maker, and then processed by a press forming process such as drawing, wrist-like, and piercing, and an automobile made of an Al-Mg aluminum alloy plate The panel member for manufacture was manufactured.

  The automotive panel member made of an Al—Mg-based aluminum alloy plate has been manufactured through such a large number of manufacturing processes as described above, and therefore requires a long time for manufacturing and also increases the cost. was there.

  Further, the Al—Mg-based aluminum alloy plate has poor ductility and inferior formability as compared with steel plates conventionally used for automotive panel members. For this reason, even if it is going to be press-formed under exactly the same conditions as the steel plate, cracks may occur during press forming at difficult-to-form parts. There was also a problem that it occurred.

  As a forming method for improving the formability of this Al—Mg-based aluminum alloy plate, there is a forming method called a local softening blank forming method, which has already been carried out. In this molding method, among the blank materials used for drawing, the material strength of the entire circumference that undergoes shrinkage deformation by drawing is set lower than the center surrounded by the entire circumference where the forming force can be applied by the punch. This is a method for improving the drawability.

  There are various proposals applying this method. For example, Patent Document 1 discloses a method of pressing a mold heated to 350 ° C. to 500 ° C. to a portion to be softened in a blank material cut into a predetermined size and then cooling the blank material. Have been described.

  Patent Document 2 describes a technique for heating a blank flange portion at the time of molding by heating a plate presser and a die for sandwiching the flange portion of the blank with respective heaters. . In Patent Document 3, the end face of a punch that is affected by heating while holding a plate material with a wrinkle presser provided with an electric heater inside and a die provided with an electric heater inside, and heating the holding portion at the same time. Describes a technique for cooling a portion of a plate material in contact with a cooling gas from a cooling air supply device provided on the opposite side of the punch. In Patent Document 4, the end face of a punch that is affected by heating while sandwiching a plate material with a wrinkle presser provided with an electric heater inside and a die provided with an electric heater inside, and simultaneously heating the holding portion. Describes a technique for cooling a portion of a plate material in contact with a non-oxidizing gas blown from a non-oxidizing gas supply device provided on the opposite side of the punch.

  In addition, in Patent Document 5, a heating medium such as an electric heater is installed in the attachment portion of the die and / or the plate presser, and a cooling medium such as cooling water is refluxed by drilling a through passage in the punch. A technique for deep drawing a thin metal plate using a plate press and a punch is described. In Patent Document 6, as a technique related to warm press working for a 5000 series aluminum alloy (Al-Mg series aluminum alloy), a die in which a heater is embedded and a wrinkle holding metal fitting, and a punch in which piping for circulating a refrigerant is embedded is disclosed. Describes a technique for warm-forming an aluminum alloy plate. Patent Document 7 discloses a technique for warm forming an aluminum alloy plate using a forming apparatus having a punch, a die and a wrinkle presser with a built-in heater as a technique related to warm forming for a 6000 series aluminum alloy. Is described.

  However, these technologies can prevent the generation of cracks and wrinkles during press forming of an aluminum alloy plate. However, even if an Al-Mg aluminum alloy plate is formed using these technologies, The problem that it takes a long time and the manufacturing cost is high cannot be solved.

JP 2004-124151 A JP-A-4-351229 JP-A-5-237558 JP-A-5-309425 Japanese Patent Laid-Open No. 11-309518 JP 2007-125601 A JP 2006-205244 A

The present invention has been made as a solution to the above-mentioned conventional problems, and by continuously performing the steps up to press forming on an Al—Mg-based aluminum alloy sheet in a cold-rolled state, Al— It is possible to reliably prevent the generation of cracks and wrinkles during the pressing of Mg-based aluminum alloy sheets, to stably press-mold aluminum alloy automotive panel members, and to reduce manufacturing time. It is an object of the present invention to provide a method for manufacturing an aluminum alloy automobile panel member that can be manufactured at low cost.

According to the first aspect of the present invention, a blank cut process and a local heating process are simultaneously performed on an Al—Mg-based aluminum alloy sheet in a cold-rolled state, followed by a cooling process and a press. An aluminum alloy automotive panel member manufacturing method for manufacturing an automotive panel member by continuously performing processing by a forming process, wherein the part heated by processing by the local heating step and local heating are performed. An automobile panel member is produced by producing an automobile panel member such that the difference in strength between the unexposed portions is more than 40 MPa and less than 120 MPa.

According to a second aspect of the present invention, the processing by the local heating step is performed by a heating means provided in a blank cut mold for performing a blank cut of the Al-Mg based aluminum alloy plate in the blank cut step. The method for producing an aluminum alloy automobile panel member according to claim 1.

According to a third aspect of the present invention, the part to be heated by the processing by the local heating step is the entire peripheral part of the blank material obtained by the processing by the blank cutting process and the part surrounded by the peripheral part. 3. The method for producing an aluminum alloy automobile panel member according to claim 1, wherein at least one local part is provided.

According to the method for manufacturing an aluminum alloy automobile panel member according to claim 1 of the present invention, by continuously processing using an Al—Mg-based aluminum alloy plate in a cold-rolled state, the press It is possible to reliably prevent the occurrence of cracks and wrinkles during processing, to stably manufacture aluminum alloy automotive panel members, to ensure sufficient formability, and to shorten the manufacturing time. The manufacturing cost can be reduced. Further, by simultaneously performing the processing by the blank cutting step and the processing by the local heating step, the manufacturing steps can be further reduced, and the aluminum alloy automobile panel member can be manufactured more stably, quickly and inexpensively.

According to the method for manufacturing an aluminum alloy automobile panel member according to claim 2 of the present invention, the blank cut process and the local heating process are simultaneously performed using a blank cut mold provided with heating means. By carrying out the manufacturing process, the number of manufacturing steps is reduced, and the aluminum alloy automobile panel member can be manufactured more stably, quickly and inexpensively.

According to the method for manufacturing an aluminum alloy automobile panel member according to claim 3 of the present invention, the portion heated in the local heating step of the blank material is surrounded by the entire periphery of the blank material and the entire periphery thereof. By using one or more local parts in the part, the aluminum alloy automobile panel member having a complicated shape can be stably produced without generation of cracks or wrinkles during pressing.

  Hereinafter, the present invention will be described in more detail based on embodiments shown in the accompanying drawings.

  The aluminum alloy plate used in the method for producing an aluminum alloy automobile panel member of the present invention is an Al—Mg-based aluminum alloy plate. The component composition of the Al—Mg-based aluminum alloy plate is not particularly limited, but a more preferable component range is exemplified below.

  The Al—Mg-based aluminum alloy plate having a preferable component range is, for example, an Al—Mg-based aluminum alloy plate containing Mg: 1.5 to 6.5% by mass with the balance being Al and inevitable impurities.

  Mg is an element that contributes to strength and formability. If it is less than 1.5% by mass, the strength is not always sufficient, and the formability is poor. On the other hand, if it exceeds 6.5% by mass, rolling becomes difficult and the formability decreases. Therefore, the content of Mg is more preferably 1.5 to 6.5% by mass. Moreover, it is still more preferable that it is 2.0-6.0 mass%.

  FIG. 1 is a process diagram showing an embodiment of a method for producing an aluminum alloy automobile panel member according to the present invention, wherein the upper part is mainly a production apparatus and the lower part is a blank obtained by cutting an Al—Mg-based aluminum alloy plate. The material 1 and the automotive panel member 2 obtained by press molding are shown.

  Although FIG. 1 shows a blank cutting process, a local heating process, a cooling process, and a press molding process, in the present invention, even if the process in each process is heating, cooling, etc., the processing of its superordinate concept Will be described.

  3 is a coil made of an Al—Mg-based aluminum alloy plate in a state of being cold-rolled and not finally annealed. In this way, in the present invention, an automotive panel member can be manufactured using an Al—Mg-based aluminum alloy plate that has not been subjected to final annealing. Therefore, the heat treatment step of final annealing that requires both time and cost is omitted. be able to. Therefore, the manufacturing time can be shortened and the manufacturing cost can be reduced.

  In the method for manufacturing an aluminum alloy automobile panel member of the present invention, first, a strip-shaped aluminum alloy plate continuously and sequentially drawn from the coil 3 is cut with a shear 4 to obtain a blank 1A. Or it is good also as the blank material 1A with the cut board cut | disconnected previously.

  Next, the outer periphery of the blank material 1A is cut (blank cut) into an outer peripheral shape close to a molded shape using a blank cut die 5 to obtain a blank material 1B. This process is called a blank cut process. In the embodiment shown in FIG. 1, processing by the local heating step is performed simultaneously with processing by the blank cut step. The blank cut mold 5 has a built-in heater as a heating means, and the heater is built in the blank cut mold 5 in accordance with the heated portion of the blank 1B. In addition, the process by a blank cut process and the process by a local heating process do not necessarily need to be implemented simultaneously. In that case, a heater is not built in the blank cut mold 5, and a heating means is provided independently of the next process separately from the blank cut mold 5.

  The part to be heated of the blank 1B is generally the entire peripheral portion a (flange) of the blank 1B. In addition, when the blank 1B is press-molded into a complicated shape in a subsequent press-molding process, a necessary part (local part b) in the part surrounded by the entire peripheral part a (flange part) is also heated. In addition, if the heating conditions in this local heating process are heating temperature: 450 ° C. or higher and lower than 580 ° C. and heating time: within 30 seconds (excluding 0 seconds), heat is not transmitted to the surroundings and heating is required. Only the part can be reliably heated.

  If this heating temperature is less than 450 ° C., the heated portion is not recrystallized and the processed structure remains as it is, and sufficient formability cannot be obtained in the subsequent press forming step. On the other hand, if the heating temperature is 580 ° C. or higher, burning occurs during heating. Therefore, the heating temperature is set to 450 ° C. or higher and lower than 580 ° C.

  In addition, if the heating time is longer than 30 seconds, the press line speed is delayed to affect the next process, or the heat due to heating is transferred to the surroundings other than the part that requires heating, and the heated part and It becomes impossible to obtain a difference in strength at a portion not heated (base material portion). Accordingly, the heating time is within 30 seconds (excluding 0 seconds).

  Thereafter, the blank 1 </ b> B is sent to a cooling process in the cooling device 6. The blank material 1B is sandwiched between the cooling bodies facing the upper and lower sides of the cooling device 6 and quickly cooled to become the blank material 1C, and the strength difference in the blank material 1C is fixed.

  The blank material 1 </ b> C that has been processed in the cooling process is sent to the press molding process in the press mold 7, and is molded into the automotive panel member 2 having a predetermined shape by the press mold 7.

  Of the blank material 1C, the entire peripheral part a and local part b heated in the local heating step are deformed by press molding, so that the part is relatively soft and the base material part (part not locally heated) is relatively hard. However, the strength difference between the material strength (proof strength) of the soft portion and the strength (proof strength) of the hard portion is more than 40 MPa and less than 120 MPa. When the strength difference is 40 MPa or less, the moldability is not sufficiently improved. On the other hand, in the case of 120 MPa or more, there is a possibility that the material strength of the locally heated portion becomes lower and cracking occurs.

It is process drawing which shows one Embodiment of this invention, Comprising: The upper stage mainly shows a manufacturing apparatus, and the lower stage shows the blank material which cut | disconnected the Al-Mg type aluminum alloy plate, and the panel member for motor vehicles obtained by press molding.

1 (1A, 1B, 1C) ... Blank material 2 ... Automotive panel member 3 ... Coil 4 ... Shear 5 ... Blank cut die 6 ... Cooling device 7 ... Press die a ... Full circumference b ... Local

Claims (3)

For the Al-Mg-based aluminum alloy sheet in the cold-rolled state, the blank cut process and the local heating process are simultaneously performed, and then the cooling process and the press molding process are continuously performed. A method for producing an automotive panel member made of aluminum alloy for producing an automotive panel member by carrying out :
A panel member for an automobile is manufactured such that a difference in strength between a portion heated by processing in the local heating step and a portion not subjected to local heating is more than 40 MPa and less than 120 MPa. Manufacturing method of panel member.   2. The processing by the local heating step is performed by a heating means provided in a blank cut mold for performing a blank cut of the Al—Mg-based aluminum alloy plate in the blank cut step. Of manufacturing an aluminum alloy automobile panel member.   The part heated by the process by the said local heating process is one or more local parts in the whole periphery of the blank material obtained by the process by the said blank cut process, and the site | part enclosed by the all the periphery. The method for producing an aluminum alloy automobile panel member according to claim 1 or 2.

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