DE4307020A1 - Aluminium@ (alloy) sheet stamping process - Google Patents

Abstract

An aluminium (alloy) sheet stamping process involves (a) applying, onto the sheet, a lubricant which contains, as main component, either a paraffin of viscosity below 50 cSt at 40 deg.C or an ester with a pour point of -50 to -100 deg.C and a viscosity of below 50 cSt at 40 deg.C; (b) opt. cooling the sheet; and (c) stamping using an uncooled die. Also claimed is an aluminium (alloy) sheet stamping process employing a die (5) which is made of material not subject to a transition temp. and which is of cooling structure type, in which liq. nitrogen circulates within the punch (7) and is expelled at the top for regulating the die temp. and the sheet temp. at -50 to -196 deg.C.

Description

The invention relates to methods for compression molding Sheets of aluminum or an aluminum alloy, the are suitable for such applications, with regard to on complicated, difficult to train designs or Molded parts, e.g. B. for automotive parts, electrical components, Aircraft components and equipment, an excellent form availability is required.

In the shaping of automotive parts, electrical Components, aircraft components and apparatus made of aluminum or aluminum alloys are available in the usual molding presses a processing limit or limitation, and in one Case where the degree of processing is considerable and high Demands, or in the case of an object A compression molding cannot be of a complicated configuration applied or is then only gradually a ge wanted to take shape through a pressing process that runs gradually and in a plurality of steps un is divided.

In the latter case, the production costs are inevitable bar increased. However, the molding of objects is where high demands are placed on the degree of processing and which have complicated configurations, more and more was demanded, and a reduction in costs through the people The shaping steps have been carried out in recent years very much wanted.

Furthermore, weight reduction in automobiles is certain has been carefully and seriously examined and examined to the increase in gaseous carbon dioxide in the atmosphere in terms of environmental issues such as global warming  and suppress the destruction of ozone layers. As one The measure to achieve weight loss is Use of Al or Al alloy sheets in the The main thing as the material for a compression molding for use come, has been increased. However, since the malleability of Al or Al alloy sheets compared to that of Sheet steel is worse, there is an imperative for an improvement with regard to the compression molding corridor.

Taking these requirements into account, one has opted for endeavors to improve the formability of materials, by the component composition and manufacturing steps for aluminum materials with regard to the materials be made suitable or appropriate or chosen, such as in JP Patent OS Sho 63-89649. There however, in recent years, the demand for molded parts or molding processes of complicated configurations with ho hen requirements for the degree of processing have increased, is an improvement in materials alone insufficient.

On the other hand, it was also with a view to the processing technology through the publication "Technical Report 89-15623 ", published by Nippon Hatsumei Kyokai (October 10, 1989) a molding process at a low temperature as a new forming process beat. However, the mentioned method only discloses that aluminum or aluminum alloys a low temperature exposed and it shows the effect of the shape temperature on the mechanical property as well as the Erichsen value of the materials, which is not yet in view on the practical situation for improving the deed physical formability is satisfactory.  

Taking into account the above statements, the Creator of this invention in an improvement for a Be working process suitable for Al alloys, worked and as a result already a low-temperature bear processing method developed and proposed (JP Pat. Note Hei 2-416279). This is an improvement Lich the formability of an Al alloy sheet by An achieved using a cryogenic temperature and in particular a method of applying cryogenic treatment created on a sheet that is a lubricant for a cry verge temperature related to a molding process in which a die does not have a cooling structure tion is equipped. However, with this treatment too formability compared to that of a steel sheet defective.

It is the primary object of this invention that above-mentioned disadvantages occurring in the prior art to overcome and to specify a procedure for an ef fective implementation of compression molding of Al or Al alloy rungsblechen, in particular a considerable and ho he degree of processing is required and complicated configurations or molded parts are affected are ideally suited in practice.

Another object of this invention is to provide a method to show that the effective use of the molding press sens on aluminum and aluminum alloy sheets in the Practice permits, with considerable and high demands be placed on the degree of machining and complicated Refinements are affected as well as a reshaping tool of the type that is not used with a cooling con structure.  

Another object of the invention is to provide a method for To specify compression molding of Al or Al alloy sheets, which improves formability to an extent the same as the formability of steel sheets is by using a forming tool of that kind det, which has a cooling structure.

To overcome the above problems, the He finder conscientiously detailed studies on effectively practi cable process for the compression molding of Al or Al alloy sheet metal and as a result of this invention based on the knowledge that the problems are effective can be offset by a special, species-specific Press lubricant applied and a molding temperature is regulated in a case where a forming tool, the is not equipped with a cooling structure or by a temperature of a shaping tool and a temperature of a raw material in a case because one with a special cooling construction Tool is used, regulated, developed.

Briefly, this invention provides a method for compression molding an Al or Al alloy sheet comprising: using a special lubricant, that is, either a lubricant comprising paraffin as the main component and a viscosity at 40 ° C of less than 50 mm ² / s (cSt), or a lubricant which has an ester as the main component and a pour point in a range from -50 to -100 ° C and a viscosity at 40 ° C of less than 50 mm ² / s has, applying the lubricant to an Al or Al alloy sheet, then cooling the sheet and applying compression molding within a range of -50 ° C to -150 ° C using a forming tool of an uncooled construction.

From another point of view, the invention further proposes a method for compression molding an Al or Al alloy sheet, which comprises using a special lubricant, ie either a lubricant comprising paraffin as the main component and a viscosity at 40 ° C of a few than 50 mm ² / s, or a lubricant, which has an ester as the main component, a pour point in the range of -50 to -100 ° C and a viscosity at 40 ° C of less than 50 mm ² / s has, the application of the lubricant on an Al or Al alloy sheet and the subsequent compression molding using a forming tool of an uncooled construction.

Furthermore, from a further point of view, a method for compression molding an Al or Al alloy sheet provides:
the use of compression molding using a forming tool made of a material which does not cause a transition temperature and of the type with a cooling structure in which a liquid nitrogen is circulated through the inside of a plunger for cooling and from the top thereof Partly being sprayed, regulating the tool temperature to a range from -50 ° C to -196 ° C and regulating the temperature of the Al or Al alloy sheet to a range from -50 ° C to -196 ° C.

The invention is explained in detail below, where reference is also made to the drawings. In the sen shows:

Fig. 1 is a schematic representation of an upwardly extending spherical head die of uncooled construction used in a molding experiment;

Fig. 2 is a schematic representation of a mold of cooled construction, which is used in a Formungsungsver search;

Fig. 3 is a diagram for explaining the influence of the molding temperature and the cooling condition on the extension or molding height in Example 5;

Fig. 4 is a diagram for explaining the temperature change of the sheet when it is immersed in liquid nitrogen in the game 8 and removed from this.

Shaping using a shaping tool cooler construction

Typically, compression molding is performed by applying a press lubricant to a forming material or tool at room temperature, and it has previously been thought that the lubricant will degrade or deteriorate when it is at a cryogenic temperature lower than -40 ° C is cooled, thereby reducing slipperiness. However, it has been found that the slipperiness is improved by using a special type of lubricant, that is, a lubricant containing paraffin as the main component and having a viscosity at 40 ° C which is less than 50 mm ² / s, or a lubricant containing an ester as the main component, which has a pour point of -50 ° C to -100 ° C and a viscosity at 40 ° C of less than 50 mm ² / s. The liquid lubricant is applied to a forming material in advance before it is immersed in a liquid nitrogen. The liquid lubricant is applied as it is. One of the lubricants used in this invention is one which includes paraffin as the main ingredient and has a viscosity at 40 ° C of less than 50 mm ² / s. In general, a lubricant has a higher viscosity the lower the temperature, and when a paraffin-containing lubricant is cooled, paraffin solidifies in a waxy state to form a lubricating membrane or skin, thereby improving the lubricating effect. Furthermore, the lubricity of the lubricant is better, the higher the viscosity. However, if the viscosity at 40 ° C exceeds 50 mm ² / s, the lubricant becomes a solid wax at a normal temperature, which tends to cause a degreasing failure or deficiency in the degreasing step, resulting in a connection failure in the following connection step, such as gluing or welding.

A lubricant rich in paraffin can only be made from paraf fin (100 wt .-%) exist and also contains preferential wise more than 50% by weight of paraffin because it is beneficial is that a homogeneous membrane is formed when the Pa refined as the ingredient at a low temperature will grow. Components other than Paraf fin, e.g. B. also a maximum printing agent as needed with the exception of such components, which coagulate (freeze) at a low temperature and destruction of the lubricant membrane (water or the like) have the result.

Further, as another lubricant usable in this invention, there can be mentioned one containing an ester as the main component and a pour point in a range from -50 ° C to -100 ° C and a viscosity at 40 ° C of less than 50 mm ² / s. If the temperature of the lubricant is lower, the viscosity is higher and the slipperiness is improved more. However, since the pour point of mineral oils is as high as -10 ° C and the sliding effect is remarkably reduced, an ester type synthetic oil is used as the lubricant which is capable of lowering the pour point. The synthetic oil of the ester type can include, for example, a diester and a polyol ester. At a temperature higher than -50 ° C, however, the slipperiness is remarkably deteriorated at a low temperature, whereas the production of a lubricant with a pour point lower than -100 ° C is industrially difficult and in view on the production cost is also not preferred. Accordingly, the pour point of the ester type synthetic oil is limited to a range from -50 ° C to -100 ° C. Furthermore, in the course of cooling the oil, the highest temperature at which the oil loses its fluidity is referred to as a clotting or coagulation point, and a temperature 2.5 ° C higher in contrast is referred to as a pour point, which is a temperature, at which the oil loses fluidity. The reason why the viscosity of the lubricant is limited as described above is the same as in the case of the paraffin-rich lubricant.

The ester type synthetic oil includes a case after it consists only of ester (100 wt .-%), and closes additionally preferably a case after which there is more than Contains 70 wt .-% ester, because it is advantageous that a homogeneous membrane is formed when the ester as the Main ingredient at low temperature a film-like Condition attained. Furthermore, other inventory can be created as needed divide as the ester, e.g. B. a maximum pressure agent, too be added with the exception of such ingredients, which coagulate (freeze) at a low temperature and result in the destruction of the lubricant membrane (Water or the like).  

After applying the lubricant to an Al or Al Alloy sheet is the primary or starting material cools and then within a temperature range of -50 ° C to -150 ° C, because the effect of a ver improvement of formability in a case of a higher temperature temperature than -50 ° C is insufficient, while a formability due to the deterioration of the Lubricant is caused and the cost in the case a temperature lower than -150 ° C is increased become.

It is possible to apply the lubricant to the sheet material, which can then be reshaped immediately (ie at normal temperature) without cooling. Although the effect of an improvement of the forming product is never less, the degreasing ability is better compared to the case of performing a deformation within the above-mentioned temperature range (-50 ° C to -150 ° C). As a mold that is not equipped with a cooling construction, one such as that shown, for example, in FIG. 1 can be used, a die 1 , a blank or sheet metal holder 2 and a punch 3 being shown.

Shaping using a forming tool cooler construction

Previously proposed by the creators of this invention ne method is one in which reshaping at a normal temperature is carried out, although the Alu minium alloy subjected to a low temperature treatment becomes. Accordingly, it is assumed that the sheet temperature is increased by the molding tool as well as the atmosphere and a mode of operation at a cryogenic temperature is not achieved can be. However, lowering the molding leads stuff about its embrittlement fracture, which is not practical.  

With this in mind, the inventors have studies and experiments in terms of material and an in-depth, accurate investigation into the effectiveness of the tool temperature and the atmospheric temperature on the forming availability.

The inventors have confirmed that a conventional one Mold material (die steel SKD 11) in one ver brittle fracture at a temperature below -100 ° C results in an austenitic, stainless steel and a Cu-Ni alloy with face centered cubic Grid does not break in embrittlement even at -196 ° C result and no problem as the die or molding witness material even with repeated pressing operations call.

On the other hand, an aluminum coated with a lubricant Alloy sheet inserted into a tool, the tem temperature from both the sheet and the tool lowers, and has the effect of lowering the temperature the formability is examined. As a result, it was confirmed that the formability when the temperature was lowered was improved and in particular a formability -196 ° C could be achieved with that of a Sheet steel is comparable.

A molding tool, although depending on the Designing the products is different, basically a stamp (male) and a female. Different me Methods can be considered to the tool temperature to a cryogenic temperature (-196 ° C) reduce. What is essential and important is that Way to get the entire tool to low temperature bring.  

Based on the inventors' studies, it has been found that a method of circulating a liquid nitrogen in the die and then spraying or jetting the liquid nitrogen over the entire tool takes a shorter time to reach the low temperature and is effective and efficient. In particular, as shown in Fig. 2, first, liquid nitrogen is circulated spirally or helically through the inside of the punch, and second, the liquid nitrogen is sprayed from the upper part of the tool to cool the entire tool. Fig. 2 shows a template-cooling valve 1, a temperature control valve 2, a stamp-cooling valve 3, a reservoir 4 for liquid nitrogen, a die 5, a blank holder 6 and a punch 7. In the case of the use of liquid nitrogen, the temperature of the liquid nitrogen for cooling the punch 7 and the entire tool is regulated in each case by the temperature control valves 2 , but it is of course possible to use a different coolant in connection with the liquid nitrogen.

According to this cooling method, the tool temperature can be changed without Difficulties within a range of -50 ° C to -196 ° C can be regulated, d. H. it can rapid cooling of the entire tool can be obtained, as well as the tem temperature of the entire stamp with regard to the formability can be made lower. One in particular hangs Improvement in the formability of the balance between the strength of the stamp shoulder and the verfor strength of the die, the improvement in the strength of the stamp shoulder is particularly important is. The stamp main body can be cooled more efficiently by spiraling a tube in the stamp for one Circulation of the coolant (liquid nitrogen) arranged is not.  

With a shape under this condition or this Zu There is a type of shape, the temperature of the tool and the temperature of the Al or Al alloy sheet are made identical, and a type of shape exercise, where a temperature gradient or drop conveys becomes. In each of these cases, it is about formability no improvement at a temperature exceeding -50 ° C temperature (elevated temperature), which is not a significant lower differed with the formability at a normal temperature shows to attain. Furthermore, a low temperature, the is lower than -196 ° C (e.g. -200 ° C), not without sweat obtained when using liquid nitrogen rather, the liquid helium that is in a problem in handling and cost results. As a result, the temperatures for the mold tool and the Al or Al alloy sheet set a range from -50 ° C to -196 ° C.

As with the aforementioned type, if shaping takes place finds the temperature for the Al or Al alloy sheet is identical to that for the tool the formability improves when the temperature Approaching -196 ° C.

On the other hand, in the second case, when the shape is below a temperature gradient is performed for the moldable to achieve further improvement. To him aim, it is necessary to completely source the liquid Nitrogen to the inside of the stamp and open the Adjust the amount of liquid nitrogen from the sheet holder. The formability, which is more excellent than that is obtained in a case where the temperature of the Al- or Al alloy sheet with that of the mold made identical at -196 ° C can be achieved by keeping the temperature for the stamp constant at -196 ° C  and the temperature for the tool corresponding to that Flange and the material to -50 ° C to -100 ° C entered be valid. If the temperature corresponding to the flange is in a range from normal temperature to -50 ° C, is a sudden cooling of the stamp material (cooling from the stamp) inadequate, whereby for the strength of the Shoulder no improvement can be expected and the um formability is not increased. On the other hand, in In the case of a temperature lower than -100 ° C, the Deformation resistance of the flange increased, which for the Formability no noticeable improvement can be achieved can.

It is important for the tool material that it is of an embrittlement break at the cryogenic temperature is, and it is necessary that the tool without difficulty and can be manufactured at low cost. in the In view of this are austenitic, stainless steel and Cu-Ni alloys suitable as the material for the tool net, since there is no abrupt change in the characteristic values and eigen depending on the temperature (transition temperature temperature) show. Than is the austenitic, stainless steel SUS 304 a typical type of steel, while a Ni-3% colson Alloy for the Cu-Ni alloy can be called. It however, it is clear that any materials are used as long as they don't break or crack embrittlement in compression molding at cryogenic temperature.

The Al or Al alloy sheet can be made to a desired one Temperature within the temperature range mentioned above be regulated by a suitable method. Usually is a method for inserting (immersing) the Sheet in the liquid nitrogen or a process of Injecting a coolant onto the sheet just before Forming process applied. A particularly preferred method ren is the following.  

After applying a lubricant to the Al or Al alloy sheet or such a foil or a thin sheet, this is immersed in a liquid nitrogen for more than 15 s, the temperature of the sheet is lowered to a low temperature lower than -100 ° C , and the material is then inserted into the cooling structure within 15 s. After applying the lubricant, the sheet is immersed in the liquid nitrogen. It is desirable that the sheet temperature be at least lower than -100 ° C and uniform. If the immersion time is less than 15 s, such a temperature cannot be guaranteed and, as a result, firstly, an improvement in moldability at a low temperature cannot be obtained, and secondly, an error prevention due to increased strength under the cryogenic temperature temperature cannot be obtained. Accordingly, a longer time than 15 s is required as the immersion time in the liquid nitrogen. Immersion for a long period of time creates a problem in productivity, but it is effective for further improving formability. The material is then removed from the liquid nitrogen and inserted into the cooled design tool shown in FIG. 2. If it is used after a period longer than 15 s, the sheet temperature is increased, which leads to the result described above under "1." was called, leads. As a result, the material taken from the liquid nitrogen is used within 15 s.

The lubricant is applied before cooling the Al or Al alloy sheet or such a sheet or sheet. There is no particular restriction with regard to the lubricant, but it should be noted that this has an effect on the formability at low temperature. In particular, a lubricant that crystallizes in the low temperature range due to the water content (shows an icy surface) is not preferred because it results in unevenness in the molding and produces less effect in improving moldability. Furthermore, a lubricant that has no fluidity at a normal temperature is not preferred because it causes errors in the subsequent process step. Accordingly, a lubricant is preferred which achieves a wax-like or film-like state even at a cryogenic temperature and has a viscosity at 20 ° C. of less than 50 mm ² / s. Liquid paraffin is one of these.

The forming material is an aluminum sheet or an aluminum mini alloy sheet, and there is no particular restriction kung. For example, regarding the material of the Al alloy sheet and a material of a suitable component system stems and a suitable composition of ingredients Choice depending on the required performance level shaft of the end product. For example, who the aluminum in terms of formability and strength High Mg (3-6% Mg) materials preferred. The reason for this is that Mg is an element which Fe stability and formability, and these materials are best suited as the material that own this unite both, but the strength of the Product after molding if the Mg- Proportion is low. As long as Mg in a predetermined amount is included, a constituent composition to it long, who is used for the application of this type can, and consequently, other alloy stocks parts can be contained in a suitable manner as required.  

Most suitable way of carrying out the invention

Examples of this invention are given below. However, it is clear that the invention is not limited to this Examples is limited, but different methods in practice are possible within the scope of the invention fall.

example 1

A JIS 5182-0 alloy material of 1 mm sheet thickness was used as the material for the forming. A deformation test (BHF: 4.0 tonf., Average speed: 15 m / min) was carried out using the ball head tool shown in Fig. 1 and a crank press. In this case, the material was coated with various oils shown in Table 1, which were applied as the lubricant, immersed in a liquid nitrogen for two minutes, and cooled and then used for the experiment. Some of the samples were subjected to the test immediately after application of the lubricant.

For the assessment of the formability, the height of the Umfor product gradually increased by lower dead the press position was changed, and the evaluation was depending on the deformation limit height, at which cracks were caused in the forming product, judged. It was also used for the evaluation of degreasing ability or property that be with the lubricant layered material using a commercially available material degreasing agent (the degreasing agent conditions are given in the table), and the condition of the remaining lubricant was calculated based on the Water leakage area ratio assessed. The results are those shown in Table 1 and it was at the example of this invention in comparison with the  Comparative example an improvement in the deformation limit height determined, and the degreasing property was even if satisfactory. In particular, the formability to emphasize at low temperature (-148 ° C).

Example 2

A JIS 5182-0 alloy material and a steel sheet were used as the starting material, a paraffinic mineral oil with a viscosity at 40 ° C of 10 mm ² / s was applied as a lubricant (polyethylene film was used for a part of the starting material), and The starting materials were molded at different forming temperatures. The results are shown in the accompanying FIG. 3. From this graph it can be seen that the deformation limit height of the aluminum alloy is improved, especially at a low temperature which is lower than -50 ° C, by using the lubricant according to this invention. Further, the amount of deformation is most improved at a raw material temperature of -196 ° C, and it took 20 minutes for a single raw material to cool it to the above-mentioned temperature.

Example 3

A JIS 5182-0 alloy material of 1 mm sheet thickness was used as the material for molding. A molding test (BHF: 4.0 tonf., Average speed: 15 m / min) was carried out using the ball head tool shown in Fig. 1 and a crank press. In this case, various oils shown in Table 2 were applied as the lubricant to the materials, which were immersed in liquid nitrogen for 2 minutes, as well as cooled, and then used for the experiment. Some of the samples were subjected to the test immediately after application of the lubricant. The moldability and degreasing ability were evaluated in the same manner as in Example 1, and the results are shown in Table 2. There was an improvement in the deformation limit height, and the degreasing property was as desired compared to the comparative example in the example according to the invention. The formability at low temperature (-148 ° C) is particularly remarkable.

Example 4

A tool made of SUS 304 having the construction shown in Fig. 2 was used. Test materials made of JIS 5182-0 material (1.0 mm thick) were covered with a liquid paraffin, inserted into a mold for a low temperature, and the workability was evaluated while changing the mold temperature and the temperature for the test material were. The process for lowering the temperature was carried out by spiraling a liquid nitrogen through the inside of the die and by spraying the nitrogen onto the entire tool and the test material. The temperature was controlled from the normal temperature to -196 ° C, and the temperature of the material in contact with the stamp was measured using a contact thermometer. The formability was assessed by the extrusion height of the ball head punch with 50 mm ⌀ (arranged in a 45 t crank press). From the test results given in Table 3, it can be seen that the formability (stretching capacity) was improved together with the temperature drop, and it was comparable to that of sheet steel at -196 ° C.

Example 5

At the test temperatures in Example 4, the factory test material in each of the tests at -100 ° C and -196 ° C changed, and the low-temperature brittleness of the work stuff was rated. As a result, tiny cracks appeared a three-time shaping at -100 ° C for the steel dimension material (die steel SKD 11) and the experiment was interrupted. On the other hand, no tiny ris se even after 100 cycles of pressing tests at -196 ° C in Case of austenitic stainless steel (SUS 304) and Cu-Ni alloy (Colson alloy) found, and it it has been confirmed that these materials are effective and lei were stable.

Example 6

A JIS 5182-0 material (1 mm in thickness) was covered with liquid paraffin, immersed in liquid nitrogen, and taken out from it and left to check the temperature change. From the results shown in Fig. 4, it can be seen that the immersion time was preferably 15 seconds, and the material was preferably inserted into the press in a short period of time under the condition that a temperature lower than that when inserted into the tool -50 ° C in terms of productivity was guaranteed. To ensure a lower temperature, it is necessary to extend the immersion time. However, if it exceeds 40 s, a time loss may be caused according to the result of this experiment.

Example 7

A JIS 5182-0 material (1 mm thick) was flowed with a liquid paraffin coated in a liquid nitrogen immersed and removed from this and during a  Change in sheet temperature assessed. The tool tem temperature was constant for the stamp and the die, and the material was inserted into the tool right after the sheet temperature was reached (within 2 s). The limit for the formability was a stretch machining with a ball head of 50 mm ⌀. The results are shown in Table 4. If the sheet metal Temperature within the range according to this invention formability is satisfactory. Compared with the mate sufficiently cooled in the mold to -196 ° C Performance is moderate, but it is against over processing at room temperature using the conventional process remarkably excellent.

Example 8

A JIS 5182-0 material (1 mm thick) was flowed with a liquid paraffin coated in a liquid nitrogen immersed and then left to set the sheet temperature to change. The stamp temperature was set at -196 ° C, while the temperature for the press flange with -70 ° C and -150 ° C was determined, and the material was put into the factory Stuff used immediately after the sheet temperature has reached was (within 2 s). After about 2 s (stamp part was ge cools) a pressure was applied and the results are shown in Table 5. A satisfactory order malleability is in each of the cases of the procedure according to the determine this invention, and it can be seen that the state one is capable of being deformable to obtain the more excellent than the case of -196 ° C for both the sheet and the tool is one Condition at a temperature on the side of the stamp of -196 ° C and a temperature within a range of -50 ° C to -100 ° C for the sheet as the press flange and the tool is.  

The invention thus discloses a method for compression molding an Al or Al alloy sheet, which includes the use of lubricants of the mineral or synthetic oil series, which serve as liquid lubricants. Further, the formability by a lubricant containing a paraffin as the main component and a viscosity at 40 ° C of less than 50 mm ² / s, or by a lubricant containing an ester as the main component, a pour point within Be a range from -50 ° C to -100 ° C and a viscosity at 40 ° C of less than 50 mm ² / s, by applying the lubricant to the Al or Al alloy sheet, by cooling the sheet and through Applying compression molding in a temperature range from -50 ° C to -100 ° C using a mold of uncooled construction improved. In another molding method, compression molding is carried out by using, as a forming tool, such a cooled structure made of a material which does not give rise to a transition temperature and in which liquid nitrogen is circulated through the inside of a stamp for cooling and sprayed from the upper part of the stamp while the tool temperature is regulated to a range from -50 ° C to -196 ° C and the temperature of the Al or Al alloy sheet to a range from -50 ° C to -196 ° C, thereby the formability, which is superior to that of sheet steel or its formability, can be obtained.

Industrial applicability

As described above, according to the invention the formability can be improved because of a pressbear processing is carried out in a low temperature range. Furthermore, since editing in a preferred Lubricant condition can occur, the formability be further improved. Therefore the procedure  an excellent effect for shaping at ho hen requirements for the degree of processing and for compli graceful designs, it can be the number of form steps and can make it economical in in practice. In particular, the Formability of an Al alloy sheet to an extent be improved that a steel sheet the same or over deformability is achieved by using a Cooling tool equipped and used Temperature set for the tool and the sheet become. In particular, deformability can be achieved those that are superior to that of a steel sheet is by using a cooling process with a temperature gradient is applied. Therefore, by the method according to the Invention an excellent effect for a weight ver reduction in components for automobiles can be obtained can promote the use of aluminum material and it becomes a contribution as a countermeasure to environmental problems such as global warming.

Table 3

Table 4

Table 5

Claims (8)

1. A compression molding process for an Al or Al alloy sheet comprising the steps:

• - Using a lubricant containing paraffin as the main ingredient, having a viscosity at 40 ° C of less than 50 mm ² / s (50 cSt), or a lubricant containing an ester as the main ingredient, a pour point within a range of -50 ° C to -100 ° C and a viscosity at 40 ° C of less than 50 mm ² / s lubricant,
• - Applying this lubricant to the Al or Al alloy sheet,
• - cooling of the sheet and
• - Subsequent compression molding using a mold of uncooled construction.

2. A compression molding process for an Al or Al alloy sheet comprising the steps

• - Use a lubricant containing a paraffin as the main component, having a viscosity at 40 ° C of less than 50 mm ² / s, or a lubricant containing an ester as the main component, a pour point within a range of -50 ° C to -100 ° C and a lubricant having a viscosity at 40 ° C. of less than 50 mm ² / s,
• - Apply this lubricant to the Al or Al alloy sheet and
• - Apply molding using a mold of uncooled construction.

3. A compression molding process for an Al or Al alloy sheet comprising the steps:

• Applying a compression molding using a molding tool which consists of a material which does not give rise to a transition temperature and which has a cooling construction, liquid nitrogen being rolled through the interior of a stamp and being sprayed from the head region thereof,
• - Adjustment of the mold temperature to a range from -50 ° C to -196 ° C and
• - Adjust the temperature of the Al or Al alloy sheet in a range from -50 ° C to -196 ° C.

4. The method according to claim 3, characterized in that the material of the mold is an austenitic, rust is free steel or a Cu-Ni alloy, which is one Do not cause transition temperature. 5. The method according to claim 3, characterized by application of a lubricant on an Al or Al alloy sheet or flat material, immersion of the sheet or flat sheet terials in a liquid nitrogen for a longer Time as 15 s, adjustment of the sheet or flat material Temperature to a cryogenic temperature lower than -100 ° C and then inserting the sheet or Flat material into the mold within 15 s of cooled construction.   6. The method according to claim 3, characterized in that the temperature of the mold and the temperature of the Al or Al alloy sheet within the above temperature range to an essentially identical table temperature value. 7. The method according to claim 3, characterized in that the compression molding is applied while the temperature for the stamp of the mold to -196 ° C and the Temperature for the press flange as well as the Al or Al Alloy sheet in a range from -50 ° C to -150 ° C be lowered. 8. The method according to claim 5, characterized in that a lubricant that is wax-like at a priority temperature and has a viscosity at 20 ° C below 50 mm ² / s is used as a lubricant to be applied.