JP5524591B2 - Method for producing aluminum alloy molded product - Google Patents

Description

  The present invention relates to a method for producing a cold press-formed product made of an age-hardening type aluminum alloy, specifically, various members and parts such as automobiles, ships, and aircraft, or building materials, structural materials, and other various machinery and equipment, The present invention relates to a method for producing an age-hardened aluminum alloy cold press-formed product suitably used for home appliances and parts thereof, particularly automobile body panels and automobile structural parts.

Conventionally, cold rolled steel sheets have been mainly used as body seats for automobiles. Recently, however, reduction of CO ₂ emissions has been demanded from the viewpoint of global warming suppression. As a result of recognition, the use of rolled aluminum alloy sheets is increasing. By the way, since the formability of an aluminum alloy rolled sheet is generally inferior to that of a cold-rolled steel sheet, it is an obstacle to expanding its use. In order to improve the formability of the rolled aluminum alloy sheet, improvement of the formability of the material itself and a device for the forming method are strongly demanded.

  Patent Documents 1 and 2 propose applying a warm deep drawing method in order to improve the formability of an aluminum alloy plate. Certainly, according to the warm forming method, it is possible to improve the deep drawability of the aluminum alloy sheet, but there are some problems if large-scale industrial production is assumed.

That is, as a feature of the warm deep drawing method, it is required to perform deep drawing while the flange portion is heated and the punch portion is cooled.
1. It is necessary to provide the press machine with heating and cooling functions for the aluminum alloy sheet. Compared with cold press forming, the total forming time is longer, resulting in lower production efficiency and lower forming costs. To increase.
2. Since the molding is performed warmly, the usual cold forming lubricating oil cannot be used, and therefore, it is necessary to develop a new lubricating oil.
3. The configuration of the press machine becomes complicated and requires high equipment costs.
4). As press machines become more complex, concerns about quality control arise.
There are problems such as.

  Here, the warm deep drawing method is to locally heat and soften a portion having a high degree of processing with respect to the aluminum alloy plate blank at the time of forming. It can be said that it is intended to improve the formability by giving a difference in strength partially in the plane of the blank, but in the same way, by giving a difference in strength in the plane of the aluminum alloy plate blank, As another method for improving, a method in which a local heat treatment (partial heat treatment) is previously applied to a blank is known (for example, Patent Document 3).

  In Patent Document 3, after the age-hardening of the entire blank of the Al-Mg-Si alloy plate is performed, only a peripheral part of the blank is heated to a high temperature of about 500 ° C by contacting a heated metal piece. The technology to improve the formability by giving a strength difference in the blank by performing a solution treatment that completely dissolves the precipitate in that portion, and then softening it, and then cold pressing. It is disclosed.

  Further, in Patent Document 4, as in Patent Document 3, a manufacturing apparatus for industrially manufacturing a difficult-to-form press-molded product by improving the press-formability by subjecting the blank to local heat treatment in advance. And a process are disclosed. In this patent document 4, the process steps for performing partial heating treatment, cooling treatment, straightening, blank cutting, and press molding are continuously arranged on the strip-shaped plate material fed from the coil, and each device is devised. By using the processing equipment appropriately, it is possible to produce highly productive and difficult-to-form press-formed products as compared with the warm forming technology in which a local heat treatment mechanism is added to the press forming machine itself as described above. It can be produced industrially.

However, the present inventors have examined the technique disclosed in Patent Document 4 in more detail, and in order to implement this technique on an actual mass production scale, the following 1 to 4 will be described. It has been found that there are such problems to be solved, and if these are not solved, it is difficult to ensure the same quality as that of a press-molded product manufactured by current ordinary cold press molding.
1. In the current normal cold press molding, if the lubricant is not applied to the blank in advance, the friction between the mold and the blank becomes too large, and galling occurs and the cold press can be performed successfully. Can not. However, Patent Document 4 does not show a process of applying lubricating oil which is indispensable in the press molding process.
2. If an aluminum alloy plate pre-coated with lubricating oil is subjected to a partial heat treatment for the purpose of imparting a strength difference, the lubricating oil will be baked on the surface of the alloy plate, and the ordinary degreasing treatment was performed on the press-formed product. Then, the surface of the molded product cannot be made clean, and further processing such as pickling is required for the molded product. Also, at the time of seizure, the lubricating oil volatilizes and white smoke is generated, so that the surrounding working environment is greatly deteriorated.
3. In addition, if the aluminum alloy plate not coated with lubricating oil is subjected to partial heat treatment by a method in which the heated body is brought into contact, seizure of the lubricating oil will not occur, but the heated body is brought into contact during partial heat treatment. In such a region, the surface of the aluminum alloy plate is scratched, and the appearance characteristics of the molded product are impaired.
4). Furthermore, in Patent Document 4, the temperature range when partially heat-treating an aluminum alloy plate is not necessarily specified, but from the description, at least when the material is an age-hardening type aluminum alloy, precipitates are not present. It is judged that the material is presupposed to be heated to a solution treatment temperature at which it is solid-solved (generally a high temperature of about 500 ° C.). However, when the material is locally heated to such a high temperature of about 500 ° C., the temperature difference between the heated part and the non-heated part becomes large, and a large plate is added to the processed material due to the difference in thermal expansion caused by this. There is a risk that distortion remains, and the press-formed product may be warped, corrugated, or uneven in shape such as irregularities.

  In Patent Document 4, among the above-described problems 1 to 4, it is said that the plate strain can be solved by the subsequent leveler process, but according to the experiment conducted by the present inventors, the material The plate strain that occurs when the plate is locally heated to a high temperature of about 500 ° C. and then rapidly cooled is so large that even if a leveler process is applied thereafter, the plate strain cannot be sufficiently corrected. It has been found that it is difficult to produce a press-molded product that remains as it is and has good appearance properties and dimensional accuracy.

  On the other hand, the present inventors have performed a predetermined heat treatment on an Al—Mg—Si alloy plate, which is a kind of age-hardening type aluminum alloy, so that the precipitate is completely dissolved. Without heating the blank to a solution treatment temperature of about 500 ° C., the heated portion can be restored and softened by heating the blank to a temperature around 250 ° C., which is sufficiently lower than that, and this phenomenon. By applying a treatment (partial heat treatment) to locally heat to a temperature of around 250 ° C. in one or more regions in the plane of the Al—Mg—Si based alloy rolled sheet blank, Similar to the techniques of Patent Documents 3 and 4, the inventors found that it is possible to improve the formability by imparting a difference in strength to the blank surface, and Patent Document 5 discloses the technique.

JP-A-4-351229 JP 2006-205244 A JP 2004-124151 A JP 2008-248342 A JP 2009-161851 A

  As shown in the above-mentioned Patent Document 3 and Patent Document 4, in place of the warm deep drawing method, an aluminum alloy blank is subjected to a partial heat treatment to previously give a strength difference in the plane of the blank. As a forming technique for improving formability by performing cold press forming from a part, particularly as shown in Patent Document 4, a partial heating process and a cooling process are performed on a strip-shaped plate fed out from a coil. However, Patent Document 4 does not show how to apply lubricating oil, which is indispensable for cold press molding. Moreover, in this patent document 4, as a heating temperature condition of the partial heat processing with respect to an age hardening type aluminum alloy, it presupposes that the part is softened by heating locally to the solution treatment temperature of 500 degreeC or more. In that case, the plate distortion due to the temperature difference in the plate surface becomes large, and it is a big problem that this cannot be corrected completely.

  As shown in the above-mentioned Patent Document 5, the present inventors have sufficiently compared with a solution treatment temperature of about 500 ° C. as a heating condition for locally softening an age-hardening type aluminum alloy by partial heat treatment. In particular, it was confirmed that it can be restored and softened at a low temperature of around 250 ° C. And by utilizing the technique shown in this patent document 5 and simultaneously selecting the application timing of the lubricating oil essential for cold press molding, press molding of difficult-to-form members with high production efficiency, An optimum manufacturing process capable of obtaining a press-molded article having the same appearance characteristics as that of the current ordinary cold press-molded article has been developed, and the present invention has been made.

Specifically, the method for producing an aluminum alloy molded article according to claim 1 uses a rolled plate made of an age-hardening type aluminum alloy, and partially defines one or more predetermined regions in the plate surface. A partial heat treatment is applied to restore and soften the heated portion by heating to a temperature of 350 ° C. or lower, and then the press forming lubricant is heated to a temperature of 200 ° C. or lower and 170 ° C. or higher. By applying to the surface of the plate, the heated portion is rapidly cooled to a temperature range lower than 100 ° C., and then press-molded to form a molded product.

  The invention according to claim 2 is the method for producing an aluminum alloy molded article according to claim 1, characterized in that the heating temperature of the heated portion in the partial heat treatment is in the range of 350 ° C. or lower and 200 ° C. or higher. It is what.

  Further, the invention of claim 3 is the method for producing an aluminum alloy molded article according to claim 1, wherein the press molding lubricant is applied to the plate surface until 10 seconds elapses immediately after the oiling. The heated portion is rapidly cooled so that the average cooling rate of the heated portion is 5 ° C./sec or more.

  According to a fourth aspect of the present invention, in the method for producing an aluminum alloy molded article according to the first aspect, as a device for performing the partial heat treatment, a treatment table provided with a heat insulating cushion material on a surface thereof, When performing a partial heat treatment using a device having a heating body facing the cushion material, an aluminum alloy rolled sheet is sandwiched between the heating body heated to a predetermined temperature and the heat insulating cushion material and heated. Thus, one or more regions in the plate surface of the aluminum alloy rolled plate are partially heated, and the surface on the side in contact with the heat insulating cushion material during the partial heat treatment in the aluminum alloy rolled plate is the molded product. It is characterized by being press-molded so as to have an outer surface.

  The invention according to claim 5 is the method for producing an aluminum alloy molded article according to claim 1, wherein any one of 2000 series aluminum alloy, 6000 series aluminum alloy, and 7000 series aluminum alloy is used as the age hardening type aluminum alloy. It is characterized by using or.

  According to the method for producing an aluminum alloy molded product of the present invention, a partial heat treatment is performed on the rolled aluminum alloy sheet to give a strength difference in the surface in advance, and then press molding is performed to form the aluminum alloy. The following effects can be obtained on the premise of the process of manufacturing the product.

In other words, partial heat treatment is applied to rolled plates made of age-hardened aluminum alloy under conditions such that the temperature of the heating part is 350 ° C. or less, thereby locally restoring and softening the material to give a strength difference. As a result, the temperature difference from the non-heated part is greatly reduced compared to the case of heating to a high temperature of about 500 ° C. for solution treatment as in the prior art, so that the plate strain remaining after cooling is greatly reduced. Therefore, it is possible to prevent the occurrence of defective shape and dimensional accuracy of the molded product. In addition, by applying the lubricating oil in a state where the temperature of the heating section after the partial heat treatment is 200 ° C. or lower and 170 ° C. or higher, the heating section is rapidly cooled by utilizing the heat removal effect of the applied lubricating oil. Since the cooling time after the partial heat treatment can be greatly shortened, productivity can be improved, and at the same time, from a temperature in the range of 200 ° C. to 170 ° C. to a temperature range lower than 100 ° C. Since an increase in strength due to precipitation in the material during the cooling process can be suppressed, the strength difference imparted by the partial heat treatment can be utilized to the maximum, and the moldability can be greatly improved. Further, by applying the lubricating oil at a temperature of 200 ° C. or less, the seizure of the lubricating oil does not occur, and the surface of the molded product can be made clean only by ordinary degreasing treatment. Furthermore, in the partial heat treatment, by appropriately selecting the treatment surface that comes into contact with the heating element, it is possible to prevent the outer surface of the molded product from being scratched and to keep the appearance performance of the press molded product good. Become.

FIG. 1 is a schematic perspective view showing an example of a partial heat treatment apparatus used in carrying out the manufacturing method of the present invention. FIG. 2 is a schematic view schematically showing the state of the bottom surface of the heating body used in the partial heat treatment apparatus shown in FIG. FIG. 3 is a schematic view schematically showing an example of a series of steps in the manufacturing method of the present invention. FIG. 4 is a schematic view showing another example of a series of steps in the manufacturing method of the present invention. FIG. 5 is a schematic plan view of a blank showing an example of a heating part and a non-heating part of the blank in the partial heat treatment of the embodiment of the present invention. FIG. 6 is a schematic diagram showing an example of the shape and dimensions of a square tube punch for press forming the blank shown in FIG.

<Aluminum alloy plate material (rolled plate) used for press forming>
The aluminum alloy rolled sheet material used in the production method of the present invention may basically be an age-hardening type aluminum alloy, and its component composition is not particularly limited. Specifically, for example, a 2000 series aluminum alloy (Al—Cu series alloy, Al—Cu—Mg series alloy), a 6000 series aluminum alloy (Al—Mg—Si series alloy, Al—) defined by JIS standard or AA standard. Mg-Si-Cu alloys) and 7000 aluminum alloys (Al-Zn-Mg alloys, Al-Zn-Mg-Cu alloys) are suitably used as age-hardening aluminum alloys in the production method of the present invention. The

  Furthermore, as the aluminum alloy rolled plate of the material for press forming used in the production method of the present invention, preferably the entire plate is made so that the material effectively exhibits restoration softening under the conditions of the partial heat treatment defined in the present invention. After solution treatment at an appropriate predetermined temperature (for example, in the case of a 6000 series alloy, desirably a temperature in the range of 480 to 590 ° C.), the solution is rapidly cooled to room temperature, and then allowed to stand at room temperature for, for example, one day or longer, thereby natural aging It is preferable to use one that is in a state of (normal temperature aging). From the same purpose, as another preferred state, after the whole plate is solution-treated at the same predetermined temperature as described above, it is rapidly cooled to a temperature range of about 100 ° C. or lower, and then 50 to 120 ° C. It may be in a state in which a preliminary aging treatment that is held in a temperature range has been performed (in a so-called sub-aging state).

  As a surface state of the aluminum alloy rolled sheet used for carrying out the method of the present invention, it is preferable that no lubricating oil is applied in advance. When the lubricating oil is pre-applied, when the heating part is heated to a temperature of 350 ° C. or lower during the partial heat treatment, the lubricating oil is baked on the aluminum alloy rolled plate and can be removed by the subsequent degreasing treatment. In this case, the lubricating oil volatilizes during burning and white smoke is generated, resulting in a worse working environment. Further, the surface state of the aluminum alloy rolled sheet is more preferably pickled. This is because the oil and the like adhering during the manufacturing process of the rolled plate is washed away by pickling to become a clean surface, and the surface is cleaned by seizure of the oil in the heating section at the time of the partial heat treatment performed thereafter. This is because the degree of deterioration can be completely prevented.

<Partial heat treatment>
In the method for producing an aluminum alloy molded article according to the present invention, a rolled plate made of an age-hardening type aluminum alloy as described above, preferably the whole plate is subjected to a solution treatment and rapidly cooled to room temperature, and then natural aging (normal temperature aging) is performed. Rolled plate or the whole plate is subjected to solution treatment and rapidly cooled to, for example, 100 ° C. or lower, followed by preliminary aging treatment at, for example, 50 to 120 ° C. The plate is subjected to a partial heat treatment at a stage before press forming. This partial heat treatment means that a part or two or more regions within a predetermined plate surface are partially (partial or local as a place in a two-dimensional surface, No) While being heated and softened, the remaining portion is left as a non-heated portion without being heated, and is a heat treatment for maintaining the strength before the treatment. Such partial heat treatment is performed for the purpose of imparting a difference in strength in the plane of the aluminum alloy plate and improving press formability. That is, in press molding, for example, a region where the punch shoulder is in contact maintains a high strength as a non-heated portion, while a region outside the region where the punch shoulder is in contact, that is, a region corresponding to the wrinkle presser is softened as a heated portion. The deformation resistance of the portion is reduced to allow the inflow of material during press molding, and the press formability is improved by these comprehensive effects.

  In the method of the present invention, the temperature of the heating part is within a range of 350 ° C. or less in order to minimize the plate distortion caused by the temperature difference between the heating part and the non-heating part in the partial heat treatment. Thus, it is locally heated so that the heating portion is restored and softened.

  Here, if the temperature of the heating part is higher than 350 ° C. in the partial heat treatment, the temperature difference from the non-heating part becomes excessive, and a large plate distortion occurs. A more desirable heating range for sufficiently reducing the thermal strain is 300 ° C. or less. In addition, the lower limit of the heating temperature is basically limited as long as restoring softening occurs. However, the optimum temperature differs slightly depending on the alloy system, but in order to sufficiently restore and soften the heated part, it is usually preferable that the temperature reached by the heated part be 200 ° C. or higher.

  The region to be restored and softened as the heating part in the partial heat treatment may basically be a part that is required to be soft in order to improve the formability during press molding, the shape of the molded product, the press It may be determined by the shape of the die / punch for molding, etc., but as already described, for example, the area outside the area where the punch shoulder is in contact during press molding, that is, the part corresponding to the wrinkle presser is the heating part, The part where the punch shoulder is in contact may be a non-heated part and may be subjected to a partial heat treatment. As a result, the portion sandwiched by the wrinkle presser at the time of press molding has a small deformation resistance, while the portion in contact with the punch shoulder portion maintains high strength and can improve press formability, particularly deep drawability. .

<Apparatus for partial heat treatment>
Although the structure of the apparatus for partial heat processing is not specifically limited fundamentally, For example, the apparatus shown in FIG. 1 can be used conveniently.

  A partial heat treatment apparatus 11 shown in FIG. 1 has a surface of a processing table 1 made of a hard material such as a metal having a flat surface, a heat insulating cushioning material having a predetermined thickness, such as a Teflon sheet or a glass wool sheet, A heating member 5 having a heating part shape corresponding to the heating part region shape in the partial heating process is disposed so as to cover the cushioning material 3 made of an alumina fiber sheet or the like and face the surface of the cushioning material 3. By pressing an aluminum alloy rolled plate, for example, a blank 7 cut into a predetermined size and shape, between the heating body 5 and the cushion material 3, and bringing the surface of the heating body 5 into pressure contact with the surface of the blank 7 The predetermined part of the aluminum alloy rolled plate 7 is heated as a heating part. In FIG. 2, an example of the condition of the bottom face of the heating body 5 is shown. In FIG. 2, the peripheral part of the heating body 5 is, for example, a heating part 5A incorporating a heater, and the inside of the heating part 5A is a non-heating part 5B. For example, the non-heating part 5B may have a water-cooled structure inside, or may have a concave shape with respect to the heating part 5A so as not to contact the aluminum alloy rolled sheet.

  Here, in the partial heat processing apparatus shown in FIG. 1, since the surface on the opposite side to the surface which contacts the heating body 5 in an aluminum alloy plate (blank 7) contacts the cushion material 3 as mentioned above, The plate surface on the side in contact with the cushion material 3 can prevent the occurrence of scratches and local deformation due to heat and pressure. That is, if the surface of the aluminum alloy rolled plate (blank 7) is locally heated and pressed by a heating body 5 made of a metal such as a copper alloy or an aluminum alloy for partial heat treatment, the heating body 5 comes into contact with the heating body 5 Although there is a risk that scratches and local deformation may occur on the plate surface on the side to be damaged, the surface on the side in contact with the cushion material 3 is prevented from being scratched or deformed by the elasticity of the cushion material 3. In this case, if the surface on the side in contact with the cushion material is determined to be the outer surface of the final molded product and press molding is performed, a product having a good outer surface property can be obtained as the molded product.

  Here, in FIG. 1, although it has shown so that an aluminum alloy plate may be pinched | interposed in the whole heating body 5, the area | region (heating part) to be heated is limited, Comprising: A small area with respect to the whole aluminum alloy plate In such a case, for example, a heating body is attached to the tip of the robot arm, and the heating body is sequentially contacted and pressurized by controlling the robot arm against one or more heating regions in the plane of the aluminum alloy rolled sheet. Of course, a good configuration is also possible. In this case as well, it is effective to improve the appearance properties of the molded product by bringing the surface to be outside the molded product after press molding into contact with the cushion material.

  The material of the heating body as described above is not particularly limited, but usually a metal having excellent thermal conductivity, such as a copper alloy or an aluminum alloy, may be used.

  Further, as the cushioning material, it is preferable to use a material having excellent heat insulating properties so as not to scratch the aluminum alloy rolled plate subjected to partial heat treatment and to efficiently increase the temperature of the heated portion of the aluminum alloy plate. As described above, for example, a Teflon sheet, a glass wool sheet, an alumina fiber sheet or the like may be used.

  Further, as a partial heat treatment apparatus different from the apparatus shown in FIG. 1, a non-contact heating means, for example, a high temperature gas is locally applied to an aluminum alloy rolled sheet disposed on a treatment table. It may be configured to perform local heating by means such as spraying on the surface, laser heating or induction heating, or a means of bringing a high-temperature heating body close to the surface of the aluminum alloy rolled plate in a non-contact manner. Of course. When such a non-contact heating method is applied, it is possible to effectively prevent the occurrence of scratches and local deformation on the plate surface, as in the case of applying the contact heating method using the cushion material as shown in FIG. As a result, it is possible to obtain a molded article having a good appearance.

<Up to a temperature range of 200 ° C. or lower and 170 ° C. or higher after partial heat treatment>
After the partial heat treatment, when the temperature of the heating part is in a temperature range of 200 ° C. or lower and 170 ° C. or higher, an oil coating process (application process for press molding lubricant) as described in the next section is performed. After the partial heat treatment, cooling may be performed or no cooling may be performed until the temperature of the heating unit reaches a temperature of 200 ° C. or lower. That is, when the heating temperature for the heating portion in the partial heat treatment is 200 ° C. or less, the next oiling treatment may be performed immediately without cooling, while the heating temperature for the heating portion in the partial heat treatment is When the temperature is higher than 200 ° C., or when the temperature is lower than 200 ° C. or close to 200 ° C., it is cooled after the partial heat treatment and reaches the temperature range of 200 ° C. or lower, and then the next oil coating treatment is performed. . In this way, as a cooling method in the case of cooling after partial heat treatment, natural cooling may be basically used. However, when production efficiency is important, forced to spray a gas such as air or a cooling medium such as mist. It is preferable to apply a cooling system. Simultaneously with cooling, when it is desired to eliminate some plate distortion caused by the temperature difference between the heated part and the non-heated part in the partial heat treatment, it is cooled to a temperature range of 200 ° C. or lower by a roll method also serving as a leveler. May be.

<Oil treatment>
When the temperature of the heated part of the aluminum alloy rolled sheet subjected to the partial heat treatment is within a temperature range of 200 ° C. or lower and 170 ° C. or higher, press forming lubricating oil is applied to the surface of the aluminum alloy rolled sheet.

  As the lubricating oil for press molding at this time, commercially available lubricating oils conventionally used in ordinary cold press molding, such as refined mineral oil, refined high boiling point solvent, petroleum sulfonate and the like as main components are used. Use it. Here, the lubricating oil to be applied in the conventional ordinary cold press molding is generally left at room temperature (room temperature), and even in the case of this invention, if lubricating oil at room temperature is used. Although it is good, in order to expect the cooling effect by applying the lubricating oil as will be described later, the desirable temperature of the lubricating oil during application is 80 ° C. or lower and 20 ° C. or higher, and the cooling effect by applying the lubricating oil is ensured. In order to obtain it, it is preferable to set it as 50 degrees C or less.

  Here, if the lubricating oil is applied in a state where the heated portion of the aluminum alloy rolled plate after the partial heat treatment is at a temperature higher than 200 ° C., the lubricating oil will be baked on the surface of the plate and formed even after washing the press-formed product. Since the cleanliness of the product surface is lowered, it is necessary to apply the lubricating oil after the partial heat treatment in a state where the temperature of the heating part is within a temperature range of 200 ° C. or less.

  Thus, by applying the lubricating oil to the surface of the aluminum alloy rolled plate after the partial heat treatment, not only the lubricating effect at the time of press forming can be obtained, but also the heated after the partial heat treatment by the applied lubricating oil. The effect of quenching the heating part is obtained by the heat removal effect on the part.

  The necessity of utilizing the quenching effect by applying the lubricating oil as described above is as described below.

That is, in the technique of the present invention, the partial heat treatment step-cooling step-oiling treatment step needs to be performed efficiently in order to improve the overall production efficiency. Of these, the partial heat treatment and the oil coating treatment can be performed in a relatively short time, but as a cooling treatment, when the temperature of the heating part is cooled to a temperature near room temperature by cooling or the like, The cooling process takes a long time compared to the partial heat treatment and oil coating processes, and the cooling process becomes the rate-determining factor of the overall process. Therefore, if the oil is applied at the stage before the temperature of the heating part of the plate is cooled to room temperature and the heat removal effect is used, the time required for the cooling process can be greatly reduced, and the production as a whole process is achieved. Can greatly improve the performance. In addition to this, in the age-hardening type alloy used in the present invention, aging precipitation of solute elements occurs in the material within the temperature range of 200 ° C. to 130 ° C. during the cooling, and the age hardening progresses. There is a problem that the strength of the heated portion restored and softened by the heat treatment rises again, and the in-plane strength difference imparted by the partial heat treatment becomes small. However, age hardening can be suppressed by applying the effect of quenching from a temperature in the range of 200 ° C. to 170 ° C. to a temperature range lower than 100 ° C. As a result, partial heat treatment The in-plane strength difference imparted by the above can be utilized to the maximum in the subsequent press molding, and high formability can be obtained.

Here, in order to effectively improve both the production efficiency and the formability, after the temperature of the heating part of the plate is cooled to 200 ° C. or lower, it is necessary to apply oil promptly at a temperature as high as possible. preferable. That is, it is necessary to apply oil at a temperature of 170 ° C. or higher. Even if the oil is applied when the temperature is lower than 170 ° C., it becomes difficult to obtain the effect of suppressing the aging precipitation by the rapid cooling as described above. Therefore, in the present invention, the timing of applying the lubricating oil is defined as the stage where the temperature of the heating part becomes 200 ° C. or lower and 170 ° C. or higher after the partial heat treatment .

  In the method of the present invention, it is desirable that the average cooling rate for 10 seconds after oiling is 5 ° C./sec or more. When the average cooling rate for 10 seconds after oiling is less than 5 ° C./sec, the cooling rate becomes insufficient and the production efficiency decreases. At the same time, aging precipitation occurs during cooling, and aging occurs. Curing progresses, the strength of the heated portion restored and softened again increases, and the effect of improving the moldability becomes insufficient.

In addition, in order to acquire said effect, the preferable application quantity of lubricating oil is 0.5 g / m < ² > or more, and a more preferable application quantity is 1 g / m < ² > or more. The specific method for applying the lubricating oil is not particularly limited, and a spray method, an electrostatic oil coating method, or the like may be applied as appropriate.

  In addition, after the partial heat treatment, until the temperature of the heated portion is lowered to 200 ° C. or lower, the age-hardening due to artificial aging does not progress during the cooling during this period, and therefore from the viewpoint of moldability. In the meantime, it is not necessary to rapidly cool, but as described above, it is preferable to cool rapidly from the viewpoint of production efficiency.

<Cutting>
Since the aluminum alloy rolled plate used as a raw material in the manufacturing method of the present invention is generally provided in a long and coiled state, the aluminum alloy fed from the coil is used for press forming. It is necessary to cut the rolled sheet. As illustrated in the process diagram of FIG. 3 to be described later, this cutting is performed in advance before the partial heat treatment, and after the blank 7 having an appropriate size and shape is formed, the partial heat treatment is performed. The subsequent steps may be performed continuously. Alternatively, as illustrated in the process diagram of FIG. 4 (this example includes a cooling device after the partial heat treatment), which will be described later, the plate material fed out in a strip shape from the aluminum alloy plate coil 9, After each treatment is performed sequentially by partial heat treatment equipment, cooling equipment, and oil coating equipment arranged continuously, it is cut with a shear to make a blank 7, and then a blank cut process is added as needed, and then press You may use for shaping | molding. Of course, the present invention is not limited to the above two examples, and the cutting process may be appropriately performed at an optimum position according to the layout of the apparatus.

<Press molding>
Finally, press molding is performed on the blank after application of the lubricating oil. In this press molding, for example, as shown in FIG. 1, when a partial heat treatment is performed using a cushion material, the surface of the plate is arranged so that the surface in contact with the cushion material becomes the outer surface of the molded product. Select the front and back and perform press molding. In addition, the temperature of the part that was the heating part during the partial heat treatment when performing the press molding is not particularly specified, but the present inventors have confirmed that the temperature is lower than 100 ° C. If so, there is no particular problem in press molding. For the same reason, as described above, the cooling by applying the lubricating oil is performed up to a temperature range lower than 100 ° C. As the press molding machine, a cold press molding machine that is normally used in general may be used.

<Overall series of processes>
In the method of the present invention, an age-hardened aluminum alloy rolled sheet is used as a raw material, and partial heating treatment- (cooling) -oiling treatment-press forming is performed in this order. Is usually in the state of a coil as described above. Therefore, usually, at any stage as described above, the aluminum alloy rolled sheet (continuous sheet) fed out of the coil has a predetermined dimension. It is necessary to put a step of cutting into a shape. An example of the overall process for carrying out such a series of processes is shown in FIG.

In the process shown in FIG. 3, the aluminum alloy rolled sheet 13 fed out from the coil 9 as a raw material is first subjected to a cutting process to obtain blanks 7 having dimensions and shapes suitable for press forming, and subsequently to each blank 7. For example, when partial heat treatment is performed by the partial heat treatment apparatus 11 as shown in FIGS. 1 and 2, and the heating portion of the blank 7 is 200 ° C. or lower and 170 ° C. or higher, for example, spray coating is performed. The oiling process with oil is performed, and the pressing process is performed immediately. In the process example of FIG. 3, a cooling process is not inserted between the partial heat treatment process and the oil coating process, but it goes without saying that a cooling process may be inserted in some cases.

  On the other hand, another example of the entire series of steps is shown in FIG.

  In the process shown in FIG. 4, partial heating treatment-cooling (for example, forced air cooling) -lubricating oil application (for example, spray oiling) is continuously performed on the aluminum alloy rolled sheet (continuous sheet) 13 fed from the coil 9. Then, the continuous plate 13 of the aluminum alloy rolled plate is cut into a shape and size suitable for press forming to form a blank 7 and press forming is performed. In the example shown in FIG. 4, a cooling step by forced air cooling is inserted between the partial heat treatment step and the oil coating step, but it goes without saying that this cooling step can be omitted in some cases.

  Whether to apply the process shown in FIG. 3 or the process shown in FIG. 4 may be determined from the viewpoint of equipment, cost, etc., but from the point of production efficiency, as shown in FIG. It is desirable to apply a process of continuously performing.

  Examples of the present invention will be described below together with comparative examples. The following examples are for explaining the operation and effect of the present invention, and the conditions described in the examples do not limit the technical scope of the present invention.

  In this example, a rolled plate of AA6022 alloy, which is a typical 6000 series alloy (Al-Mg-Si series alloy), was used as a material.

  This rolled sheet is manufactured in a general manufacturing process such as DC casting, homogenization, hot rolling, cold rolling, solution treatment, and rapid cooling, and after pickling as the final surface treatment, it is coiled. It is in a wound state. Further, the final heat treatment state of the rolled material sheet was aged at room temperature for 10 days or more after solution treatment / quenching at 550 ° C. × 2 sec, and was in a state suitable for softening by partial heat treatment. It was. The plate width size of the aluminum alloy plate wound up in a coil shape is 420 mm.

  According to the processing mode schematically shown in FIG. 4, the aluminum alloy rolled plate 13 is fed out from the coil 9 in a strip shape, and the partial heating treatment, cooling treatment, oiling treatment, and cutting are successively performed in sequence to obtain an aluminum alloy plate blank 7. Was made. Subsequently, this blank 7 was subjected to cold press molding. Hereinafter, each processing step will be described.

  The partial heat treatment was performed by a method in which a liftable heating element 5 was brought into contact with an aluminum alloy rolled plate and pressurized as in the case schematically shown in FIG. Here, the surface of the processing table 1 for being paired with the heating body 5 was covered with a Teflon sheet having a thickness of 1 mm as a heat-insulating cushion material 3. The region side of the heated part P and the non-heated part Q of the aluminum alloy rolled sheet in this partial heat treatment is shown in FIG. 5 corresponding to the shape and dimensions of the blank 7 after cutting described later. Table 1 shows the temperature conditions of the heating part in the partial heat treatment.

  The subsequent cooling process was performed by forced air cooling. Furthermore, the oil application process (lubricating oil application process) was performed with a spray-type oil application apparatus. The lubricating oil used was press washed rust preventive oil Preton R-303P, and the oil temperature just before coating was normal temperature. Oiling is performed on both sides of the plate, and the amount of oil applied on one side is shown in Table 1. Table 1 shows the temperature of the heated portion of the aluminum alloy rolled sheet at the start of oiling. Moreover, the temperature of the heating part when 10 seconds passed immediately after oiling was measured and shown in Table 1, and the average cooling rate for 10 seconds immediately after oiling is also shown in Table 1. The last cutting process was performed with a shear cutter at a pitch of 300 mm in accordance with the 300 mm width of the heating unit, and a blank 7 was obtained.

  The press molding was continuously performed using a normal press molding machine after shear cutting. The press molding was performed after the temperature of the heating part in the partial heat treatment became lower than 100 ° C. Table 1 shows the correspondence of whether the surface in contact with the heat-insulating cushion material in the partial heat treatment previously performed becomes the outer surface or the inner surface of the press-molded product after press molding. Shown in. Here, the outer surface of the molded product refers to the outer surface of the portion overhanged by press molding, and is the surface on which the surface quality must be guaranteed. The press molding was performed by drawing a rectangular tube using a punch 15 having the shape and dimensions shown in FIG. The forming height was 20 mm as a standard, and press forming was performed, and the production efficiency of the press-formed product was also confirmed. The press-formed product was inspected for surface cleanliness after washing by degreasing. When the surface of the molded product was clean and free from oil and fat, it was judged good, and when the surface was seized and seized, it was judged as poor. Similarly, after washing by degreasing, the outer surface on the overhang side of the press-formed product was visually observed to inspect for scratches. When the scratch was not confirmed visually, it was determined to be good, and when the scratch was confirmed, it was determined to be defective. These determination results are shown in Table 2.

  Separately from this, when the molded product is visually confirmed after press molding, and the molded product can be molded without breaking, the molding height is increased stepwise by 5 mm, and molding can be performed without breaking. The formability was evaluated by the maximum height of the product and is shown in Table 2.

  In Tables 1 and 2, Condition 1 and Condition 2 are examples in which press forming was performed in a series of steps within the condition range of the present invention. In these cases, due to the rapid cooling effect due to the oil coating, aging precipitation during cooling is suppressed, and the effect of improving moldability by restoring softening is sufficiently obtained, and a molded product having a maximum molding height of 45 mm or more can be produced. It was. Moreover, the temperature of the heating part in the partial heat treatment decreased to 100 ° C. or less in 10 seconds after oil coating, and a press-formed product could be produced with a high production efficiency of about 6 pieces / min.

  On the other hand, Condition 3 is an example in which the temperature of the heating part at the time of oil coating was 230 ° C., which was higher than the range specified in the present invention. Other conditions are within the scope of the present invention. In this case, although the maximum molding height of 45 mm or more was obtained, seizure occurred when the oil was applied, so the cleanliness after the degreased cleaning of the molded product was poor.

  Condition 4 is an example in which the average cooling rate for 10 seconds after oiling is lower than the range of the present invention. In this case, the rapid cooling effect due to oiling became insufficient, and it took a long time for cooling after oiling to press molding, and the production efficiency was greatly reduced to 2 pieces / min. Moreover, age hardening occurred in the heating part of the partial heat treatment in the middle of cooling, and the strength of the restored softened part (heating part) increased. For this reason, the maximum molding height of the press-molded product was 25 mm, and the effect of improving moldability was not obtained.

  Further, Condition 5 is an example in which, as is conventionally performed, cutting is performed after oiling and press molding without performing partial heat treatment. In this case, the production efficiency was as high as about 6 pieces / min. However, since no difference in strength was given in the blank, the maximum molding height was only 25 mm, and molding in the case of conditions 1 to 3 where partial heat treatment was performed. Compared with the case of 45 mm in height, it became smaller.

  On the other hand, in condition 6, the temperature condition is within the condition range of the present invention, and as in the case of condition 1 and condition 2, high production efficiency and high moldability could be secured. However, in this example, press molding was performed so that the surface in contact with the heat-insulating cushion material at the time of partial heat treatment was the inner surface of the press-molded product, so the outer surface of the press-molded product was subjected to partial heat treatment. At that time, many scratches due to contact with the heating body were confirmed, resulting in poor appearance performance.

DESCRIPTION OF SYMBOLS 1 Processing stand 3 Cushion material 5 Heating body 7 Aluminum alloy plate blank 11 Partial heat processing apparatus 13 Aluminum alloy rolling plate (continuous plate)
P Heating part Q Non-heating part

Claims (5)

Partial heating that uses a rolled plate made of age-hardened aluminum alloy and partially heats the heated portion by partially heating one or more predetermined regions within the plate surface to a temperature of 350 ° C. or lower. Then, the heated portion is rapidly cooled to a temperature range lower than 100 ° C. by applying a lubricant for press molding to the plate surface in a state where the heated portion is at a temperature of 200 ° C. or lower and 170 ° C. or higher. Then, a method for producing an aluminum alloy molded product, wherein press molding is performed to obtain a molded product. In the manufacturing method of the aluminum alloy molded article according to claim 1,
A method for producing an aluminum alloy molded article, wherein a heating temperature of a heated portion in the partial heat treatment is set to be 350 ° C. or lower and 200 ° C. or higher. In the manufacturing method of the aluminum alloy molded article according to claim 1,
Rapidly cooling the heated part so that the average cooling rate of the heated part is 5 ° C./sec or more by applying press forming lubricant to the plate surface until 10 seconds have passed immediately after the oiling. A method for producing an aluminum alloy molded product, characterized in that: In the manufacturing method of the aluminum alloy molded article according to claim 1,
As a device for performing the partial heat treatment, a device having a treatment table provided with a heat insulating cushion material on the surface and a heating body facing the cushion material is used. One or two or more regions in the plate surface of the aluminum alloy rolled plate are partially heated by sandwiching and heating the aluminum alloy rolled plate between the heating body heated to a temperature of 5 mm and the heat insulating cushioning material. And a method for producing an aluminum alloy molded product, wherein the aluminum alloy rolled plate is press-molded so that a surface on the side in contact with the heat insulating cushion material at the time of partial heat treatment becomes an outer surface of the molded product. In the manufacturing method of the aluminum alloy molded article according to claim 1,
Any one of 2000 series aluminum alloy, 6000 series aluminum alloy, and 7000 series aluminum alloy is used as said age hardening type aluminum alloy, The manufacturing method of the aluminum alloy molded article characterized by the above-mentioned.

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