Pressing System and Method

Abstract

A pressing device and method for manufacturing a thermoformed structural component are provided. The device includes a fixed lower body and a movable upper body. The device includes a cooling die and a pressing die arranged downstream of the cooling die, and a blank transfer mechanism for transferring a blank from the cooling die to the pressing die. The cooling die has an upper gas cooling die connected to the movable upper body and / or a lower gas cooling die connected to the fixed lower body. The pressing die includes an upper press die connected to the upper body and a lower press die connected to the lower body.

Description

Technical Field

[0001] This application claims the priority benefit of European Patent Application 19382899.3, filed on October 14, 2019. The present disclosure relates to a pressing system and method for manufacturing thermoformed structural components. Background Art

[0002] In the field of vehicle manufacturing, in order to meet the standards of lightweight structures, the development and implementation of lightweight materials or components have become increasingly important. The need to reduce weight is particularly driven by the goal of reducing carbon dioxide emissions. The increasing concern for occupant safety has also led to the use of materials that improve the integrity of the vehicle during a collision while also enhancing energy absorption.

[0003] A process called hot forming die quenching (HFDQ) (also known as hot stamping or press hardening) uses boron steel sheets to manufacture stamped parts with ultra-high strength steel (UHSS) properties, having a tensile strength of 1500 MPa or even up to 2000 MPa or higher. Compared with other materials, the increased strength allows the use of thinner materials, resulting in weight reduction compared to traditional cold-stamped low-carbon steel parts.

[0004] The steel sheet can be coated or uncoated. However, in order to improve corrosion protection before, during, or after the hot stamping process, a coating can be applied. For example, the use of an Al-Si coating or a Zn coating is known.

[0005] Depending on the composition of the base steel, it may be necessary to quench (i.e., rapidly cool) the blank to achieve a high tensile strength. Quenching may imply a cooling rate higher than the critical cooling rate of the material used (e.g., approximately 30 °C / s). Other steels may have a relatively low critical cooling rate. Examples of steels that can be hardened at room temperature by air cooling at a lower cooling rate are known.

[0006] The hot stamping process can be performed in such a way that the blank to be thermoformed is heated to a predetermined temperature, e.g., by a furnace system to reach or exceed the austenitization temperature in order to reduce strength, i.e., to facilitate the hot stamping process. The blank to be thermoformed can be formed by a pressure system and temperature control having a lower temperature (e.g., room temperature) compared to the blank, and thus a forming process and heat treatment using a temperature difference can be performed.

[0007] The use of a multi-step pressing system for manufacturing thermoformed elements is known. The multi-step pressing system can include multiple dies configured to perform different operations on the blank simultaneously. With such an arrangement, multiple blanks undergo different manufacturing steps simultaneously using the dies forming the multi-step pressing system in each stroke. One aspect of using such a multi-step press system is that the production volume can be very high.

[0008] The multi-step pressing system may include a conveyor or transfer device that transfers the heated blank to a pressing die configured to press the blank. Other dies that may be included in the multi-step pressing system may be, for example, any one of a perforation die, a calibration die, a cutting die, a trimming die, a secondary pressing die, and the like. In addition, an oven system for heating and softening the blank to be thermoformed may be provided upstream of the multi-step pressing system or apparatus.

[0009] Typically, in such systems, an external pre-cooling die is used to pre-cool the blank to be hot-formed. For example, galvanized steel blanks may need to be cooled prior to the hot-forming process to reduce or minimize issues such as micro-cracking. Once the blank is cooled, it is transferred from the external pre-cooling die to a multi-step pressing machine or system.

[0010] EP3067128 discloses a pressing system for manufacturing thermoformed structural components. The system includes a fixed lower body, a movable upper body, and a mechanism configured to provide an upward and downward pressing progression of the movable upper body relative to the fixed lower body. The system further includes a cooling die configured to cool a previously heated blank, the blank comprising an upper mating die and a lower mating die, the lower die being connected to the lower body using one or more lower biasing elements, and / or the upper die being connected to the upper body using one or more upper biasing elements. The system further includes a pressing die configured to draw the blank, wherein the pressing die is arranged downstream of the cooling die.

[0011] The system disclosed in EP3067128 can accelerate the manufacturing process. To ensure that the cooling die can cool the blank quickly enough, a biasing element forces the upper and lower cooling dies into contact with the blank before the pressing die closes. This allows the cooling die to "close" before the pressing die closes. This allows the pressing dies of the cooling die to remain in contact for a sufficient time to properly cool the blank. Furthermore, by integrating the dies in the same press, the transfer time from the cooling die to the drawing die can be reduced, thereby optimizing the process and increasing productivity while maintaining satisfactory formability without causing cracks in the blank.

[0012] However, cooling molds with contact plates require extensive maintenance. Furthermore, providing uniform and constant cooling during production is complex. Especially when restarting production after an interruption, such as when starting a new batch of product or at the beginning of a workday, it takes a long time (and a corresponding loss of product) to consistently achieve the desired cooling effect.

[0013] The present disclosure seeks to provide improvements to multi-step processes and systems. Summary of the invention

[0014] In a first aspect, a pressing device for manufacturing a thermoformed structural component is provided. The pressing device includes a fixed lower body, a movable upper body, and a mechanism configured to provide an upward and downward pressing process of the movable upper body relative to the fixed lower body. The device further includes a cooling die configured to cool a previously heated blank and a pressing die configured to draw the blank and disposed downstream of the cooling die, and a blank transfer mechanism for transferring the blank from the cooling die to the pressing die.

[0015] Here, the cooling die has an upper gas cooling die connected to the movable upper body and / or a lower gas cooling die connected to the fixed lower body. And the pressing die includes an upper press die connected to the upper body and a lower press die connected to the lower body.

[0016] According to this aspect, a multi-step pressing device combining a cooling die and a pressing die is provided. This can speed up the production process and achieve high output. By integrating the dies in the same press, the transfer time from the cooling die to the drawing die can be reduced, so that the process can be optimized and the productivity can be improved, while maintaining satisfactory formability without causing cracks etc. at the blank.

[0017] One aspect of using gas cooling is that it requires relatively less maintenance. Gas cooling is also relatively easy to provide a constant and uniform cooling process. That is, gas cooling generally does not have the disadvantages of using a contact plate.

[0018] Providing gas cooling dies in a multi-step device also provides versatility. For example, for relatively thin blanks, only the lower gas cooling die can be used. For the same process with blanks of increasing thickness, the upper gas cooling die can be added. Then the cycle time can still be kept short. Depending on the need, the cooling dies disclosed herein allow flexibility in cooling parameters, including cooling time, temperature of the cooling gas, cooling flow rate, etc.

[0019] In some examples, a single cooling die is provided. For example, only the lower gas cooling die connected to the fixed lower body can be provided. In this case, the pressing device can have improved reliability and be relatively cost-effective. In other examples, only the upper gas cooling die connected to the movable upper body can be provided. In this case, the upper gas cooling die can be connected to the movable upper body using a biasing element that forces the upper gas cooling die towards the fixed lower body.

[0020] Due to the biasing element, the upper gas cooling die can reach an appropriate position relative to the blank to be cooled before drawing / pressing with the pressing die. Therefore, in the same pressing device, within one stroke, the cooling cycle may be longer than the drawing cycle.

[0021] In still other examples, the upper gas cooling die is connected to the movable upper body, and the lower gas cooling die is connected to the fixed lower body. In these cases, one or more upper biasing elements may connect the movable upper body to the upper gas cooling die. The upper biasing elements bias the upper gas cooling die away from the movable upper body. The lower gas cooling die may be connected to the fixed lower body using one or more lower biasing elements that bias the lower gas cooling die away from the fixed lower body.

[0022] In some examples, at the bottom of the pressing cycle, the upper gas cooling die is at a predetermined first distance relative to the workpiece, and the lower gas cooling die is at a predetermined second distance relative to the workpiece. Effective and most predictable gas cooling can be achieved when air is blown towards the workpiece from a predetermined distance range relative to the workpiece. At the bottom of the pressing cycle, a certain distance needs to be maintained between the cooling die and the workpiece.

[0023] The predetermined first distance may be equal to the predetermined second distance such that substantially equal cooling can be provided for the upper and lower surfaces of the workpiece.

[0024] In some examples, the cooling die may include a stop that maintains a minimum distance between the upper gas cooling die and the workpiece (or the lower gas cooling die that supports the workpiece).

[0025] In some examples, the stop may be provided on the upper gas cooling die and the stop is arranged to contact the lower gas cooling die (or the lower fixed body) to generate a force opposite to the biasing element. Such a force opposite to the biasing element ensures that this distance is maintained as the pressure stroke continues. As the movable upper body continues to move towards the lower fixed body, the biasing element may be compressed and the distance between the gas cooling die and the workpiece can be maintained.

[0026] In some examples, the stop may be a rod or bar.

[0027] In some examples, the device may be configured to start the cooling cycle when the minimum distance between the upper gas cooling die and the lower gas cooling die is reached. Uniform cooling on both sides can be achieved if the airflows from both sides are substantially equal and from the same distance. For example, for relatively thick workpieces, the cooling effect can be improved by the upper gas cooling die and the lower gas cooling die. The cooling cycles in these examples may be intermittent. Such intermittent cooling cycles may also be used in examples where only the lower gas cooling die or only the upper gas cooling die is provided. Once the workpiece is positioned, the cooling cycle can be started.

[0028] In other examples, the cooling can be substantially continuous, i.e., the flow of the cooling gas can be constant, and thus the cooling can start once the blank is transferred to the cooling die. This can be implemented when using a single gas cooling die and when using two gas cooling dies.

[0029] In some examples, the biasing element can include one or more springs. In further examples, the biasing element can include a hydraulic or pneumatic actuator.

[0030] In some examples, the upper gas cooling die and / or the lower gas cooling die includes a plurality of straight channels connected to a pressurized gas reservoir, and the system further includes a controller for controlling the gas passage through the straight channels from the reservoir. The cooling rate and temperature to be achieved can be controlled by the gas volumetric flow rate, the gas temperature, and the distance from the straight channels to the blank. In some examples, the system can further include temperature control of the pressurized gas in the reservoir.

[0031] In some examples, the straight channels can be oriented substantially perpendicular to the blank.

[0032] In some examples, the gas can be air and can be substantially at ambient temperature. A cost-effective system can be provided in this regard.

[0033] In some examples, the upper die and / or the lower die of the pressing die includes channels for conducting cooling liquid or cooling air. In some examples, the material of the blank and the desired microstructure of the resulting component make a high cooling rate necessary or desirable. The pressing die can be temperature-controlled to provide an appropriately high or appropriately low cooling rate. The cooling rate of one part of the blank may also be different from that of another part of the same blank. The resulting microstructures of these different parts may thus be different.

[0034] In some examples, the temperature at the upper and / or lower die is controlled based on the temperature at the working surface of one of the dies. The pressing equipment can include one or more thermocouples at the working surface of one of the dies.

[0035] In some examples, the pressing equipment can be a mechanical press. In other examples, the pressing equipment can be a servo-mechanical press. In further examples, the pressing equipment can be a hydraulic press. The methods and systems disclosed herein can be implemented in different mainstream pressing equipment. Mechanical and servo-mechanical pressing equipment can provide high output, while the biasing element in the equipment allows for some flexibility in adjusting the cooling cycle.

[0036] In some examples, the pressing device may further include a first post - operation die configured to perform a first post - operation, wherein the first post - operation die is arranged downstream of the pressing die and includes: upper and lower first post - operation die punches, where the upper first post - operation die punch is connected to the upper body and the lower first post - operation die punch is connected to the lower body. Here, the blank transfer mechanism is further configured to transfer the blank from the pressing die to the first post - operation die.

[0037] Multiple stages and processes can be added to the same pressing device. Operations performed after drawing the blank are referred to herein as "post - operations".

[0038] In some examples, the first post - operation includes trimming and / or cutting the blank, and the upper and / or lower first post - operation die punches may include one or more cutting blades.

[0039] To control the temperature during the process, the upper and / or lower first post - operation die punches may include one or more heaters or channels for conducting heat - transfer liquid. To maintain some deformability and to facilitate cutting, trimming, or other machining operations, it may be beneficial for the blank to maintain a minimum temperature. Thus, wear of the post - operation die can be reduced.

[0040] For this purpose, in some examples, the heater or the channel for conducting heat - transfer liquid may be configured to maintain the temperature of the blank above 200 °C based on the temperature measured at the die punch of the first post - operation die.

[0041] In some examples, the upper and / or lower first post - operation die punches may include channels for conducting coolant, optionally cooling water. In some examples, the temperature at the upper and / or lower first post - operation die punches may be controlled based on the temperature at the working surface of one of the die punches. Optionally, a thermocouple may be provided at the working surface of one of the first post - operation die punches.

[0042] In some examples, the pressing device may further include a second post - operation die arranged downstream of the first post - operation die. The blank transfer mechanism may further be configured to transfer the blank from the first post - operation die to the second post - operation die, and the upper second post - operation die punch is connected to the upper body and the lower second post - operation die punch is connected to the lower body.

[0043] In some examples, the second post - operation die is configured for trimming and / or perforating.

[0044] In some examples, the second post - operation die can be configured for calibration. In these cases, the second post - operation die can include an adjustment device configured to adjust the distance between the upper and lower second post - operation die punches to deform the blank, and wherein the adjustment device is controlled based on a sensor system configured to detect the thickness of the blank.

[0045] The temperature control in the second post - operation die can be the same as or similar to the temperature control in the first post - operation die.

[0046] In another aspect, a method for thermoforming a blank is provided. The method includes providing a pressing device according to any of the examples described herein, and providing a blank to be thermoformed made of ultra - high - strength steel (UHSS) with a zinc coating. The method can include heating the blank; placing the blank in a cooling die; and cooling the blank while providing a downward pressing process of the movable upper body relative to the fixed lower body. Then, the method further includes performing an upward pressing process of the movable upper body relative to the fixed lower body; positioning the blank in a pressing die; and drawing the blank by downward and upward pressing processes of the movable upper body relative to the fixed lower body.

[0047] In some examples, the blank can be heated above the austenitization temperature of the UHSS. The blank can be heated above Ac1, and in some examples, the blank can be heated above Ac3.

[0048] In some examples, the blank can be heated to a temperature between 860 °C and 910 °C.

[0049] In some examples, the UHSS can contain by weight: 0.20 - 0.50% C, 0.75 - 1.5% Si, and 1.50 - 2.50% Mn. Preferably, the UHSS contains 0.21 - 0.25% C, 1.05 - 1.33% Si, 2.06 - 2.34% Mn by weight percentage. More preferably, the UHSS can contain approximately 0.22% C, 1.2% Si, 2.2% Mn by weight. UHSS of such composition can be capable of air hardening. Optionally, the UHSS further contains Mn, Al, Ti, B, P, S, N.

[0050] The UHSS can be provided with a protective coating to improve corrosion protection before, during, or after the hot stamping process. The coating can be a zinc coating or an aluminum - silicon coating.

[0051] In some examples, the blank can be cooled in the cooling die to a temperature between 400 and 600 °C. For UHSS with a zinc coating, cooling to this temperature range before drawing can avoid crack formation. This temperature range enables good formability to be maintained during the subsequent drawing process.

[0052] It may be possible to use UHSS blanks with an aluminum-silicon coating, such that shot peening is not required after the hot stamping process to partially or fully remove the zinc oxide layer. The use of multi-step equipment can increase production.

[0053] In some examples, the method may further include cooling the blank during drawing. In some examples, the blank may be cooled to a temperature between 320 °C and 280 °C during drawing.

[0054] In some examples, the temperature of the blank may be maintained above 200 °C in the first and optionally in the second post-operation die.

[0055] In some examples, the blank may be made of UHSS comprising 0.15 - 0.25 wt% C, up to 0.5% Si, up to 2.5% Mn, 0.002 - 0.005% B, and up to 0.05% Cr. In some examples, the UHSS may further comprise Al, Ti, P, and Mo.

[0056] In some examples, the blank may be made of UHSS comprising 0.15 - 0.25 wt% C, up to 1% Si, up to 2.5% Mn, 0.002 - 0.005% B, and 0.5 - 0.7% Cr. Preferably, the UHSS material comprises 0.15 - 0.25 wt% C, up to 0.5% Si, up to 2.5% Mn, 0.002 - 0.005% B, and up to 0.5% Cr. In some examples, the UHSS may further comprise Al, Ti, P, and Mo.

[0057] In alternative examples, the UHSS material comprises 0.15 - 0.25 wt% C, up to 0.5% Si, up to 2.5% Mn, 0.002 - 0.005% B, and up to 0.5% Cr, preferably about 0.3% Cr. In some examples, the UHSS may further comprise Al, Ti, P, and Mo.

[0058] UHSS having the composition according to the foregoing paragraphs is not configured for air hardening, but may require a higher cooling rate to obtain a martensitic microstructure.

[0059] In some examples, the steel that is not hardened by ambient air may be 22MnB5 steel. 1500P is an example of 22MnB5 steel. The composition by weight percentage is summarized as follows (the balance being iron (Fe) and unavoidable impurities):

[0060] C Si Mn P S Cr Ti B N 0.24 0.27 1.14 0.015 0.001 0.17 0.036 0.004 0.003

[0061] After the hot stamping die quenching process, 1500P may have a yield strength of, for example, 1.100 MPa and an ultimate tensile strength of 1.500 MPa.

[0062] 2000 is another higher-strength boron steel. After the hot stamping die quenching process, the yield strength of 2000 can be 1.400 MPa or more, and the ultimate tensile strength can be above 1.800 MPa. The composition of 2000 contains, by weight, at most 0.37% carbon, at most 1.4% manganese, at most 0.7% silicon, and at most 0.005% boron.

[0063] For non-air hardening UHSS, before drawing the billet, the first cooling of the billet may be from above the austenitizing temperature to temperatures between, optionally between During subsequent forming, the temperature of the billet can be reduced to, for example, Optionally between Between. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] Non-limiting examples of the present disclosure will be described below with reference to the drawings, in which:

[0065] Figure 1 Schematically represents a multi-step press system according to an example;

[0066] Figures 1A - 1F Schematically shows the sequence of steps during the method of cooling and forming a billet using a multi-step pressing system according to Figure 1 ;

[0067] Figure 2a Schematically shows another example of a multi-step pressing system;

[0068] Figure 2b Schematically shows the upper gas cooling die according to an example of Figure 2a ;

[0069] Figures 3A - 3F Schematically shows a series of situations that occur during the method of cooling and forming a billet according to an example; and

[0070] Figure 4 Schematically shows another example of a multi-step pressing system. DETAILED DESCRIPTION

[0071] Figure 1ASchematically shows an example of a multi-step pressing device. The device includes a fixed lower body 2, a movable upper body 1, and a mechanism (not shown) configured to provide an upward and downward pressing process of the movable upper body 1 relative to the fixed lower body 2.

[0072] The fixed lower body 2 can be a large piece of metal. In this particular example, the fixed lower body 2 can be stationary. In some examples, a die cushion (not shown) integrated in the fixed lower body 2 can be provided. The cushion can be configured to receive and control the blank holder force. The movable upper body 1 can also be a solid metal sheet. The movable upper body 1 can provide a stroke cycle (up and down movement).

[0073] The pressing system can be configured to perform approximately 30 strokes per minute, so each stroke cycle can be approximately 2 seconds. In further examples, the stroke cycle may be different.

[0074] The mechanism of the press can be mechanically driven, hydraulically driven, or servo-mechanically driven. The process of the movable upper body 1 relative to the fixed lower body 2 can be determined by the mechanism. In this particular example, the press can be a servo-mechanical press, so a constant pressure can be provided during the stroke. The servo-mechanical press can provide infinite slide (slider) speed and position control. The servo-mechanical press can also provide a good pressure availability range at any slide position, thus enabling great flexibility of the press. The servo-driven press can have the ability to improve the metal forming process conditions and productivity. The press can have a pressing force of, for example, 2000 tons.

[0075] In some examples, the press can be a mechanical press, so the pressing force process towards the fixed lower body 2 can depend on the drive and hinge system. Therefore, the mechanical press can achieve a higher unit time cycle. Alternatively, a hydraulic press can also be used.

[0076] Figure 1 Shows a cooling die 10 configured to cool a previously heated blank 80. The cooling die 10 can include a lower gas cooling die 12. The lower gas cooling die can include an air knife. The lower gas cooling die 12 can include a pressurized air chamber that contains a series of holes or continuous straight grooves through which the pressurized air is discharged, and preferably in a laminar flow mode.

[0077] The air discharged from the straight grooves or holes impinges on the heated blank 80. The blank 80 is thus cooled.

[0078] The lower gas cooling die can include various control mechanisms. For example, the gas temperature in the pressurized air chamber can be controlled. Alternatively or additionally, one or more valves can be included to control the air flow towards the blank.

[0079] The advantage of using gas cooling is that the cooling curve (temperature versus time) can be precisely controlled. In addition, it is relatively easy to maintain uniform cooling throughout the production cycle (e.g., one day).

[0080] In the example, the cooling die can be provided with centering elements such as pins, retainers 16, and / or guiding devices.

[0081] The pin or retainer 16 always holds the blank 80 at a distance d1 from the lower gas cooling die 12.

[0082] In this example, a pressing die 20 configured to form or draw a blank is also provided, and the pressing die 20 is integrated in a multi-step pressing device. The pressing die 20 is arranged downstream of the cooling die 10. The pressing die 20 includes an upper pressing die 21 and a lower pressing die 22. The mating herein means that the pressing dies have complementary shapes such that the blank placed between them deforms when the upper pressing die 21 moves towards the lower pressing die 22.

[0083] In this particular case, the blank 70 is shown to undergo a forming or drawing step in the next pressing cycle. It should be clear that the blank 70 in the previous cycle has already undergone a cooling process in the cooling die 10.

[0084] The upper pressing die 21 may include an upper working surface 23 that faces the blank to be thermoformed in use. The lower pressing die 22 may include a lower working surface 24 that faces the blank to be thermoformed in use. The side or part of the upper pressing die opposite to the upper working surface 23 may be connected to the movable upper body 1, and the side or part of the lower pressing die opposite to the lower working surface 24 may be connected to the fixed lower body 2.

[0085] The upper pressing die 21 and the lower pressing die 22 may include channels having a cold fluid (e.g., water and / or cold air passing through the channels provided in the pressing dies). In the water channels, the circulation speed of water at the channels can be very high so that evaporation of water can be avoided. A control system may be further provided to control the temperature of the pressing dies.

[0086] In the example, the pressing die 20 may be provided with a blank retainer (25) that is configured to hold the blank and position the blank onto the lower pressing die 22. The blank retainer may be provided with one or more biasing elements that are configured to bias the blank retainer to a position at a predetermined distance from the lower pressing die 22.

[0087] A first post-operation die 30 configured to perform trimming and / or piercing operations may be provided. In this particular example, the blank 60 will undergo a trimming or cutting operation in the next stroke of the pressing device. It should be clear that the blank 60 has previously undergone a cooling process in the cooling die 10 and a forming process in the pressing die 20.

[0088] The first post - operation die 30 is arranged downstream of the pressing die 20. The first post - operation die 30 may include a first upper post - die 32 and a first lower post - die 31. The first upper post - die 32 may include a first upper post - working surface 33 and the first lower post - die 31 may include a first lower post - working surface 34. Both working surfaces in use face the blank 60.

[0089] One side of the first upper post - die 32 opposite to the first upper post - working surface 33 may be fastened to the movable upper body 1, and one side of the first lower post - die 31 opposite to the first lower post - working surface 34 may be fastened to the fixed lower body 2. The die may include one or more cutting tools or cutting blades (not shown) arranged on the working surface.

[0090] The first post - operation die 30 may include one or more electric heaters or channels for conducting heat - carrying liquid and temperature sensors to control the temperature of the die. The sensors may be thermocouples. In some examples, preferably, the temperature of the blank located between the upper die and the lower die during use is maintained at or near a predetermined temperature, such as above 200 °C, above 250 °C or above 300 °C.

[0091] In some examples, the first upper post - die 32 and the first lower post - die 31 may include channels for a cold fluid (such as water and / or cold air passing through channels provided in the die).

[0092] In an example, the first post - operation die 30 may be provided with a blank holder (not shown), which is configured to hold the blank and position the blank onto the first lower post - die 31. The blank holder may also be provided with one or more biasing elements, which are configured to bias the blank holder to a position at a predetermined distance from the lower die.

[0093] In Figure 1 an example, a second post - operation die 40 is provided. The second post - operation die 40 may also be configured to perform further trimming and / or piercing operations. The second post - operation die 40 is arranged downstream of the first post - operation die 30. The second post - operation die 40 may include a second upper post - die 42 and a second lower post - die 41. The second upper post - die 42 may include a second upper post - working surface 43, and the second lower post - die 41 may include a second lower post - working surface 44. Both working surfaces in use may face the blank to be thermo - formed. The working surfaces may not be flat, for example, they may include protrusions or recesses.

[0094] One side of the second upper post - die 42 opposite to the second upper post - working surface 43 may be connected to the movable upper body 1. One side of the second lower post - die 41 opposite to the second lower post - working surface 44 is connected to the fixed lower body 2.

[0095] The die may include one or more tools or cutting blades disposed on the working surface.

[0096] In some examples, an adjustment device (not shown) may be provided that is configured to adjust the distance between the second rear upper die 42 and the second rear lower die 41. In this way, the blank 50 located between the second rear upper die 42 and the second rear lower die 41 during use can be deformed along the working surfaces of each upper die and lower die.

[0097] Once the adjustment of the distance between the second rear upper die 42 and the second rear lower die 41 has been performed to deform (and thus calibrate) the blank, the tolerances of the thermoformed blank can be improved. In some examples, the blank to be thermoformed may have areas with unoptimized thickness, for example, the thickness of one part of the blank is greater than that of other parts, so the thickness must be optimized.

[0098] Through the arrangement of this uneven working surface, the distance at selected portions of the working surface (such as near the radius in the blank) can be adjusted at or near the areas with unoptimized thickness, so that the material may deform, that is, be forced to flow into the areas adjacent to the unoptimized thickness areas, and thus a constant thickness along the blank can be achieved.

[0099] In an example, the adjustment device can be controlled based on a sensor system configured to detect the thickness of the blank.

[0100] In some examples, the second rear operating die 40 may be provided with a blank holder (not shown) that is configured to hold the blank and position the blank onto the second rear lower die 41. The blank holder may also be provided with one or more biasing elements that are configured to bias the blank holder to a position at a predetermined distance from the lower die.

[0101] In a further example, other ways of adapting the die of the mold to operate at lower or higher temperatures can also be envisaged.

[0102] It should be understood that although the figure depicts a die having a substantially square or rectangular shape, the block can have any other shape and can even have a partially circular shape.

[0103] An automatic transfer device (not shown), such as a plurality of industrial robots or conveyors, may also be provided to perform the transfer of the blank between the molds.

[0104] In all examples, temperature sensors and a control system for controlling the temperature can be provided in any mold or transfer system. The mold may also be provided with a further cooling system, a blank holder, etc.

[0105] Figures 1A - 1FSchematically shows a series of situations that occur during the execution of a method for cooling and shaping a blank according to an example. The same reference numerals denote the same elements.

[0106] For simplicity, references to the pressing cycle angle will occasionally be included in the description related to Figure 1A (and other figures). References to the angle can be used to indicate the approximate position of the upper body relative to the lower body. Thus, for example, it can be referred to that the movable upper body 1 is in the 0° position relative to the lower body, which indicates that the upper body is in the highest position relative to the lower body, and a position of 180° indicates that the upper body is in the lowest position (fully contacting position) relative to the lower body. Then 360° again refers to the upper body being in the highest position and the process cycle having been completed.

[0107] In Figure 1A , a blank 80 to be hot-formed made of ultra-high-strength steel (UHSS) can be provided. In this specific example, the blank 80 can have a zinc coating. In some examples, the UHSS can contain, for example, about 0.22% C, 1.2% Si, 2.2% Mn. Specific amounts of Si and Mn can harden the blank at room temperature and thus quenching can be avoided (and thus the pressing time for blank manufacturing can be reduced). The blank can further include different proportions of Mn, Al, Ti, B, P, S, N.

[0108] Ultra-high-strength steel (UHSS) having such characteristics can have an Ac3 transformation point (austenite transformation point, hereinafter referred to as the "Ac3 point") between 860 and 870 °C. For the above steel composition, Ac3 may be about 867 °C. The Ms transformation point (martensite start temperature, hereinafter referred to as the "Ms point") can be between 380 and 390 °C. For the above steel composition, Ms may be about 386 °C. The Mf transformation point (martensite finish temperature, hereinafter referred to as the "Mf point") can be at or near 270 °C.

[0109] Different steel compositions can be used. In particular, the steel compositions described in EP 2735620 A1 can be considered suitable. Specifically refer to Table 1 of EP 2735620 and paragraphs 0016 - 0021, as well as the considerations in paragraphs 0067 - 0079.

[0110] The blank 80 can be heated to at least reach the austenitization temperature. The heating can be carried out in a heating device (not shown) such as a furnace. In this specific example, the maximum temperature for heating the blank can be determined by the coating. The melting point (and thus the evaporation temperature) of zinc can be at or close to 910 °C, so the maximum temperature for heating the blank 80 in the heating device can be set to be below approximately 910 °C. The blank 80 can be heated to a temperature higher than Ac3 but lower than the evaporation temperature of zinc at 910 °C or close to 910 °C. Thus, the heating can be carried out between 867 °C and 910 °C, especially at 890 °C or close to 890 °C (for the above steel composition). The period of time to be heated can be about 6 minutes, but this depends on, for example, the thickness of the blank.

[0111] Once the blank 80 has been heated to the required temperature for a sufficient length of time, the blank 80 can be transferred to the cooling die 10. This can be done by an automatic transfer device (not shown) such as a plurality of industrial robots or conveyors. The transfer time of the blank between the furnace (not shown) and the cooling die 10 can be between 2 and 3 seconds.

[0112] In some examples, centering elements (such as pins and / or guiding devices) can be provided upstream of the cooling die so that the blank can be properly centered. The blank 80 can be positioned on a pin or blank holder 16 that maintains a small distance between the holding lower gas cooling die 12 and the blank 80.

[0113] The pressing movable upper body 1 can be in the open position (0° position). Then the blank 80 is positioned on the gas cooling die 11. In some examples, the blank can be placed on a blank holder.

[0114] As described above, the biasing element can include, for example, a spring, such as a mechanical spring or a gas spring, but some other biasing elements can also be possible, such as a hydraulic mechanism. The hydraulic mechanism can be a passive mechanism or an active mechanism.

[0115] In Figure 1B the press has started the pressing process of the movable upper body 1 downward relative to the fixed lower body 2. In this specific example, the cooling has started. However, it should be noted that in other examples, the cooling cycle can be continuous, and thus once the blank 80 is positioned in the cooling die, the cooling can start.

[0116] A pressurized cooling air flow (possibly air) may impinge on the blank. The air flow can be controlled based on the measurement of a flow meter. The pressure of the gas can be, for example, approximately 2 bar. The required gas flow rate, gas temperature, and cooling time may vary, for example, according to the thickness of the blank. Thicker blanks will require a longer time to cool unless the gas temperature is reduced and / or the air flow is increased.

[0117] The gas can flow towards the straight grooves or holes of the blank, and the holes can be arranged to be substantially perpendicular to the surface of the blank.

[0118] In Figure 1C for example, within the range of 130 - 180°, the pressing die may start to deform.

[0119] In Figure 1D after reaching the final desired position (180° position), a process of upward pressing the upper body by the pressing mechanism can be provided. The end of the cooling cycle may be between the 210° and 270° positions of the upper body (and thus the upper pressing die) relative to the lower body.

[0120] As previously mentioned, when the blank 80 is pressed, the blank can be cooled by using the cooling device in the pressing die. It has been found that ultra-high-strength steel (UHSS) with a zinc coating can show microcracks when the temperature at the pressing die is higher than 600°C. Thus, the blank can be cooled to a temperature below 600°C before being transported to the pressing die, especially between 500°C and 600°C, and preferably at or close to 550°C.

[0121] As already described, the blank 80 can be preheated (i.e., heated in a furnace) to 890°C or close to 890°C. The blank can be transferred to the cooling die 10, so during the transfer period, the temperature can be reduced to between 850°C and 800°C or 750°C. Then the blank can be cooled to a temperature of approximately 550°C.

[0122] By using the cooling die 10 integrated in the pressing system equipment, the time for cooling the blank can be optimized because additional movements for transferring the blank from an external cooling die can be avoided. It can also save time. In addition, the movement of the blank between the dies can be restricted, so the cooling rate is easily controlled.

[0123] In Figure 1E the blank 80 may have been cooled and thus be ready to be transferred from the cooling die 10 to the pressing die 20. The transfer can be performed by an automatic transfer device (not shown) (such as multiple industrial robots or conveyors). As mentioned above, the blank can be transferred at a temperature of 550°C or close to 550°C. Due to the transfer time, the blank 80 can be cooled before it reaches the forming die.

[0124] While the blank 80 is undergoing the above process, other blanks 50, 60, 70 are undergoing other processes. The blank 70 is being drawn, and the blanks 50 and 60 are undergoing post-operations.

[0125] During forming, the last complete contact between the working surface of the upper die of the forming die and the blank (and thus the end of the drawing operation) may be between the 180° and 210° positions. In this example, the last contact between the blank and the blank holder may be between, for example, 210° - 270°.

[0126] The temperature of the blank 70 can be reduced during forming until a temperature between 300°C and 400°C is reached, in particular around 350 - 370°C. The pressing die can be provided with a cooling system. The cooling system can be controlled by a controller, so that the temperature of the blank 70 can be reduced and maintained at the desired temperature.

[0127] The blank 60 has been drawn and has been transferred from the pressing die 20 to the first post - operation die 30 for, for example, piercing or trimming. The transfer can be performed by an automatic transfer device (not shown) (such as a plurality of industrial robots or conveyors). As described above, the blank 60 can leave the pressing die 20 at a temperature above 300°C, in particular between 350 - 370°C. Due to the transfer time, the blank 60 may have cooled a little further. The blank 100 can be placed on the first post - lower die 31 and between the first post - lower die 31 and the first post - upper die 32.

[0128] The blank 60 has been transferred or positioned on the first post - lower die 31, and the automatic transfer system can operate to supply the blank 200 to the pressing die 20 and the blank 300 to the cooling die 10. As a result, as described above, the cooling die 10 can start operating to cool the blank 300. At the same time, as described above, the pressing die 20 can start operating to draw and cool the blank 300.

[0129] In the first post - operation die, the first post - upper die 32 can contact the blank 60 placed between the first post - upper die 32 and the first post - lower die 31 of the pressing die only when the final desired position (at or near 180° of the pressing cycle) is reached.

[0130] When the press contacts the blank 60, a piercing operation can be performed using a cutting blade or some other cutting element. Once the piercing operation is completed, a trimming operation can be performed. In an alternative example, the trimming operation can be performed first and the piercing operation can be performed after the trimming operation is completed. Trimming and piercing can also occur substantially simultaneously.

[0131] When the blank 60 undergoes post - operations, the blank can be heated by using the heating device described above in order to keep the blank above the minimum temperature and ensure the deformability of the blank.

[0132] Once the final desired position (180° position of the pressing cycle) is reached, an upward pressing process can be provided. The last complete contact between the working surface of the first post-upper die 32 and the workpiece 100 (and thus the end of the operation) can be between the 180° and 210° positions. The last contact between the workpiece and the workpiece holder (if provided in the post-operation die) may occur between 210° and 270° of the pressing cycle.

[0133] Finally, in this particular example, a second post-operation die is included in the pressing device. It should be clear that in further examples, the post-operation die or more than two post-operation dies may not be included in the pressing device.

[0134] The second post-operation die in this example can be used for piercing and / or trimming. Additionally, a calibration operation can be performed, and thus the manufacturing tolerance of the workpiece can be improved. For this purpose, the distance between the second post-upper die 42 and the second post-lower die 41 can be adjusted using an adjustment device. The adjustment device can be controlled based on a sensor system (not shown) configured to detect the thickness of the workpiece 100. According to the example, the workpiece can be pressed by the second post-upper die 42 and the second post-lower die 41, so that a constant thickness of the workpiece can be achieved. Similar to the first post-operation die, the die temperature (and thus the workpiece temperature) can be controlled, and in particular, the minimum temperature of the workpiece can be ensured.

[0135] Once the operation of the second post-operation die is completed, the workpiece can be transferred and hardened at room temperature.

[0136] In some examples, depending on the desired shape of the final component, further drawing and other operations, such as piercing and / or trimming, can be provided. In further examples, the order of the post-operations can be interchanged (e.g., cutting first, then calibration, and vice versa).

[0137] Figure 2a Another example of a multi-step pressing device is shown. In this example, the cooling die 10 includes an upper gas cooling die 11 and a lower gas cooling die 12.

[0138] In this particular example, the upper gas cooling die 11 is connected to the movable upper body 1 by one or more biasing elements. The biasing elements push the upper gas cooling die away from the movable upper body 1 towards the fixed lower body 2. The biasing elements in this example can be springs, such as mechanical springs or gas springs, but in other examples, other biasing elements may be used. Such alternative biasing elements may include, for example, a hydraulic mechanism to force the cooling die towards the opposite cooling die.

[0139] In other examples, the lower gas cooling die 12 can be connected to the fixed lower body 2 via a biasing element. The working principle will be the same as that of the upper gas cooling die described herein. In some examples, biasing elements can be provided for both the upper gas cooling die 11 and the lower gas cooling die 12.

[0140] With the insertion of the upper and / or lower biasing elements, the time available for cooling (the up-and-down movement of the movable upper body 1 relative to the fixed lower body 2) can be adjusted and increased during the stroke cycle.

[0141] Due to the biasing elements in the cooling die, cooling can start before the die contact of the forming die (and other dies arranged downstream).

[0142] The upper gas cooling die is provided with a stop 14. These are also shown in Figure 2b . The stop 14 can be rod-shaped and can contact the lower gas cooling die 12 (or the fixed lower body) when the movable upper body 1 moves downward. The stop 14 can ensure a certain distance is maintained between the upper and lower gas cooling dies. This also means a certain distance is maintained between the upper gas cooling die 11 and the blank 80.

[0143] The stop can be sized and shaped such that when cooling occurs, the distance between the upper gas cooling die 11 and the blank 80 also remains at a distance d1 (the distance between the lower air cooling die 12 and the blank 80) during a part of the pressing cycle.

[0144] Referring to Figure 2b , examples of possible arrangements of multiple stops 14 can be seen. In this example, the stops 14 are generally straight bars. The distal end 14A of the stop can be flat and can provide a contact surface for the lower gas cooling die in this example. As previously mentioned, the functions of the upper and lower gas cooling dies may be opposite. The rod is attached at the side surface 19 of the upper gas cooling die 11. Figure 2b Multiple straight grooves 18 are also shown in

[0145] through which the pressurized cooling gas can be discharged and flow towards the blank.

[0146] Figures 3A - 3F Shows a Figures 1A - 1F similar sequence of steps as in

[0147] Figure 3A However, contrary to the previous example, the cooling die in this example has an upper gas cooling die 11 and a lower gas cooling die 12. Figure 2a A multi-step pressing device is shown before the start of the pressing process (e.g., at 0° of the pressing cycle).

[0148] InFigure 3B In this case, the pressing device has started the downward pressing process of the movable upper body 1 relative to the fixed lower body 2, so the upper gas cooling die 11 has moved downward toward the lower die 12 (and thus the workpiece 80 located on the lower die 11).

[0149] The upper gas cooling die 11 is provided with a stopper 14 extending toward the lower gas cooling die. In Figure 3B this case, the stopper 14 is about to contact the lower gas cooling die 12.

[0150] In Figure 3C this case, for example, within the range between 90° and 150° of the pressing cycle, the stopper 14 contacts the lower gas cooling die. The workpiece 80 is then at a predetermined distance from the upper gas cooling die. The workpiece is also at a predetermined distance from the lower gas cooling die. The workpiece can be arranged at an equal distance from the upper and lower gas cooling dies. When the distances of the workpiece from the upper and lower gas cooling dies are clearly defined, controlled cooling can be carried out.

[0151] As the pressing process continues, the distances between the upper and lower gas cooling dies and between the cooling dies and the workpiece can be maintained because the biasing elements are compressed.

[0152] A pressurized cooling air flow (which may be air) may impinge on the workpiece. As previously described, the air flow can be controlled based on the measurement of the flowmeter. The pressure of the gas can be, for example, about 2 bar. The required gas flow rate and gas temperature may vary, for example, according to the thickness of the workpiece. Unless the gas temperature is reduced and / or the air flow is increased, a thicker workpiece will require a longer time to cool. Even for a thicker workpiece, the simultaneous use of the lower and upper gas cooling dies can ensure a relatively short cooling cycle.

[0153] In Figure 3D this case, after reaching the final required position (180° position), a process of upward pressing the upper body by the pressing mechanism can be provided. The end of the cooling cycle may be between the 210° and 270° positions of the upper body (and thus the upper die) relative to the lower body. In Figure 3D this case, it can be seen that the upper biasing elements 13 that are still partially compressed can start to return to their original position or configuration. By appropriately arranging the biasing elements, the cooling period can be longer than the pressing period and the cooling cycle can last, for example, between 0.33 and 1 second.

[0154] Figure 3E and Figure 3F is generally similar to Figure 1E and 1F as described therein.

[0155] In the examples described herein, gas cooling begins when the blank is disposed at a specific predetermined distance relative to the upper and lower air cooling dies. It should be clear that in other examples, gas cooling can begin before this moment and can also be continuous.

[0156] Figure 4 Another example of a multi-step pressing device is schematically shown. In this example, the cooling die 10 does not have a lower gas cooling die but only has an upper gas cooling die 11. The upper gas cooling die 11 can be connected to the movable upper body 1 by means of an upper biasing element 13.

[0157] The upper gas cooling die can include a stopper 14 as shown previously. As in the previous example, the combination of the biasing element 13 and the stopper allows the minimum distance between the cooling die and the blank to be reached more quickly and then maintained. Thus, the cooling cycle can be longer than the forming cycle.

[0158] For completeness, various aspects of the present disclosure are listed in the following numbered clauses:

[0159] Clause 1. A pressing device for manufacturing a thermoformed structural component, comprising: a fixed lower body, a movable upper body, and a mechanism configured to provide an upward and downward pressing process of the movable upper body relative to the fixed lower body, wherein the device comprises:

[0160] a cooling die configured to cool a previously heated blank, and

[0161] a pressing die configured to draw the blank and disposed downstream of the cooling die, and

[0162] a blank transfer mechanism for transferring the blank from the cooling die to the pressing die

[0163] wherein the cooling die has an upper gas cooling die connected to the movable upper body and / or a lower gas cooling die connected to the fixed lower body,

[0164] wherein the pressing die includes an upper die connected to the upper body and a lower die connected to the lower body.

[0165] Clause 2. The pressing device according to Clause 1, wherein the pressing device is configured such that the cooling time is longer than the drawing time during the pressing cycle.

[0166] Clause 3. The pressing device according to Clause 1 or 2, comprising a lower gas cooling die connected to the fixed lower body.

[0167] Clause 4. The pressing device according to Clause 1 or 2, comprising an upper gas cooling die connected to the movable upper body by means of one or more upper biasing elements that bias the upper gas cooling die away from the movable upper body.

[0168] Clause 5. The pressing device according to Clause 1 or 2, wherein the cooling die has an upper gas cooling die connected to the movable upper body and a lower gas cooling die connected to the fixed lower body.

[0169] Wherein, the upper gas cooling die is connected to the movable upper body by one or more upper biasing elements that bias the upper gas cooling die away from the movable upper body, and / or the lower gas cooling die is connected to the fixed lower body by one or more lower biasing elements that bias the lower gas cooling die away from the fixed lower body.

[0170] Clause 6. The pressing device according to Clause 4 or 5, wherein, at the bottom of the pressing cycle, the upper gas cooling die is at a predetermined first distance relative to the blank, and the lower gas cooling die is at a predetermined second distance relative to the blank.

[0171] Clause 7. The pressing device according to Clause 6, wherein the predetermined first distance is equal to the predetermined second distance.

[0172] Clause 8. The pressing device according to any one of Clauses 4 - 7, wherein the cooling die includes a stopper that maintains a minimum distance between the upper gas cooling die and the blank.

[0173] Clause 9. The pressing device according to Clause 8, wherein the stopper is provided on the upper gas cooling die and is arranged to contact the lower gas cooling die to generate a force opposite to that of the biasing element.

[0174] Clause 10. The pressing device according to Clause 9, wherein the stopper is a rod or bar.

[0175] Clause 11. The pressing device according to any one of Clauses 8 - 10, wherein the device is configured to start the cooling cycle when the minimum distance between the upper gas cooling die and the blank is reached.

[0176] Clause 12. The pressing device according to any one of Clauses 4 - 11, wherein the biasing element includes one or more springs.

[0177] Clause 13. The pressing system according to any one of Clauses 1 - 12, wherein the upper gas cooling die and / or the lower gas cooling die includes a plurality of straight grooves connected to a pressurized gas reservoir, and the system further includes a controller for controlling the gas passage from the reservoir through the straight grooves.

[0178] Clause 14. The pressing system according to Clause 13, wherein the straight grooves are oriented substantially perpendicular to the blank.

[0179] Clause 15. The pressing system according to Clause 14, wherein the gas is air at ambient temperature.

[0180] Clause 16. The pressing system according to any one of Clauses 13 - 15, further comprising temperature control of the pressurized gas in the reservoir.

[0181] Clause 17. The pressing device according to any one of Clauses 1 - 16, wherein the upper die and / or the lower die of the pressing die comprises channels for conducting coolant or cooling air.

[0182] Clause 18. The pressing device according to Clause 17, wherein the temperature at the upper die and / or the lower die is controlled based on the temperature at the working surface of one of the dies.

[0183] Clause 19. The pressing device according to Clause 18, further comprising one or more thermocouples at the working surface of one of the dies.

[0184] Clause 20. The pressing device according to any one of Clauses 1 - 19, wherein the pressing device is a mechanical press.

[0185] Clause 21. The pressing device according to any one of Clauses 1 - 19, wherein the pressing device is a servo-mechanical press.

[0186] Clause 22. The pressing device according to any one of Clauses 1 - 19, wherein the pressing device is a hydraulic press.

[0187] Clause 23. The pressing device according to any one of Clauses 1 - 22, further comprising a first post-operation die configured to perform a first post-operation, wherein the first post-operation die is arranged downstream of the pressing die and comprises:

[0188] Upper and lower first post-operation die punches, wherein

[0189] The upper first post-operation die punch is connected to the upper body, and the lower first post-operation die punch is connected to the lower body, and wherein

[0190] The blank transfer mechanism is further configured to transfer the blank from the pressing die to the first post-operation die.

[0191] Clause 24. The pressing device according to Clause 23, wherein the first post-operation comprises trimming and / or cutting the blank, and wherein

[0192] The upper and / or lower first post-operation die punches comprise one or more cutting blades.

[0193] Clause 25. The pressing device according to Clause 23 or 24, wherein the upper and / or lower first post-operation die stamper includes one or more heaters or channels for conducting heat-transfer liquid.

[0194] Clause 26. The pressing device according to Clause 25, wherein the heater or the channel for conducting heat-transfer liquid is configured to maintain the temperature of the workpiece at 250 °C or above 300 °C based on the temperature measured at the stamper of the first post-operation die.

[0195] Clause 27. The pressing device according to any one of Clauses 23-26, wherein the upper and / or lower first post-operation die stamper includes channels for conducting coolant, optionally cooling water.

[0196] Clause 28. The pressing device according to any one of Clauses 25-27, wherein the temperature at the upper and / or lower first post-operation die stamper is controlled based on the temperature at the working surface of one of the dies.

[0197] Clause 29. The pressing device according to Clause 28, further comprising one or more thermocouples located at the working surface of one of the first post-operation die stampers.

[0198] Clause 30. The pressing device according to any one of Clauses 23-29, further comprising a second post-operation die, which is arranged downstream of the first post-operation die, and the workpiece transfer mechanism is further configured to transfer the workpiece from the first post-operation die to the second post-operation die, and wherein

[0199] the upper second post-operation die stamper is connected to the upper body, and the lower second post-operation die stamper is connected to the lower body.

[0200] Clause 31. The pressing device according to Clause 30, wherein the second post-operation die is configured for trimming and / or piercing.

[0201] Clause 32. The pressing device according to Clause 31, wherein the second post-operation die includes upper and lower second post-operation die stampers, wherein

[0202] the first and / or second post-operation die includes one or more cutting blades.

[0203] Clause 33. The pressing device according to any one of Clauses 30-32, wherein the second post-operation die includes an adjusting device, which is configured to adjust the distance between the upper and lower second post-operation die stampers to deform the workpiece, and wherein the adjusting device is controlled based on a sensor system configured to detect the thickness of the workpiece.

[0204] Clause 34. The pressing device according to any one of Clauses 30 - 33, wherein the temperature at the upper and / or lower first post - operation die punches is controlled based on the temperature at the working surface of one of the dies.

[0205] Clause 35. The pressing device according to Clause 34, further comprising one or more thermocouples located at the working surface of one of the first post - operation die punches.

[0206] Clause 36. A method for thermoforming a blank, comprising:

[0207] - providing a pressing device according to any one of Clauses 1 - 35;

[0208] - providing a thermoforming blank made of ultra - high - strength steel (UHSS) with a zinc coating;

[0209] - heating the blank;

[0210] - placing the blank in a cooling die;

[0211] - cooling the blank while providing a downward pressing process of the movable upper body relative to the fixed lower body;

[0212] - performing an upward pressing process of the movable upper body relative to the fixed lower body;

[0213] - positioning the blank in the pressing die; and

[0214] - drawing the blank through downward and upward pressing processes of the movable upper body relative to the fixed lower body.

[0215] Clause 37. The method according to Clause 36, wherein the blank is heated above the austenitization temperature of the UHSS.

[0216] Clause 38. The method according to Clause 37, wherein the blank is heated to a temperature between 860 °C and 910 °C.

[0217] Clause 39. The method according to any one of Clauses 36 - 38, wherein the UHSS contains approximately 0.22% C, 1.2% Si, and 2.2% Mn.

[0218] Clause 40. The method according to Clause 39, wherein the UHSS further contains Mn, Al, Ti, B, P, S, N.

[0219] Clause 41. The method according to any one of Clauses 36 - 40, wherein the blank is cooled in the cooling die to a temperature between 500 °C and 600 °C.

[0220] Clause 42. The method according to any one of Clauses 36 - 41, further comprising cooling the blank during drawing.

[0221] Clause 43. The method according to Clause 42, wherein during drawing, the workpiece is cooled to a temperature between 400 °C and 300 °C.

[0222] Clause 44. The method according to any one of Clauses 36 - 43, wherein the pressing device includes a first post - operation die, the first post - operation die including upper and lower first post - operation die punches having cutting blades, wherein

[0223] the upper first post - operation die punch is connected to an upper body, and the lower first post - operation die punch is connected to a lower body, and

[0224] the method further includes piercing and / or trimming the workpiece by

[0225] transferring the workpiece from the pressing die to the first post - operation die; and

[0226] providing a downward and upward pressing process of the movable upper body relative to the fixed lower body.

[0227] Clause 45. The method according to Clause 44, wherein the temperature of the workpiece located at the first post - operation die is maintained above 200 °C, particularly above 300 °C.

[0228] Clause 46. The method according to Clause 44 or 45, wherein the pressing device includes a second post - operation die, the second post - operation die including upper and lower second post - operation die punches, wherein

[0229] the upper second post - operation die punch is connected to the upper body, and the lower second post - operation die punch is connected to the lower body, and

[0230] the method further includes:

[0231] transferring the workpiece from the first post - operation die to the second post - operation die; and

[0232] providing a downward and upward pressing process of the movable upper body relative to the fixed lower body.

[0233] Although only a number of examples are disclosed herein, other alternatives, modifications, uses, and / or equivalents are possible. In addition, all possible combinations of the described examples are also covered. Accordingly, the scope of the present disclosure should not be limited by the specific examples, but should be determined only by a fair reading of the appended claims.

Claims

1. A pressing device for manufacturing thermoformed structural components, comprising: A fixed lower body, a movable upper body, and a mechanism configured to provide an upward and downward pressing process of the movable upper body relative to the fixed lower body, wherein the device includes: A cooling die configured to cool a previously heated blank, and A pressing die configured to draw the blank and disposed downstream of the cooling die, and A blank transfer mechanism for transferring the blank from the cooling die to the pressing die Wherein the cooling die has an upper gas cooling die connected to the movable upper body, and wherein the upper gas cooling die is configured to provide a pressurized cooling air flow to impinge on the blank, and Wherein the pressing die includes an upper pressing die connected to the upper body and a lower pressing die connected to the lower body; The upper gas cooling die is connected to the movable upper body by one or more upper biasing elements that bias the upper gas cooling die away from the movable upper body; wherein, The cooling die includes a stopper that maintains a minimum distance between the upper gas cooling die and the blank, such that at the bottom of the pressing cycle, the upper gas cooling die is at a predetermined first distance relative to the blank.

2. The pressing device according to claim 1, wherein The pressing device is configured such that the cooling time is longer than the drawing time during the pressing cycle.

3. The pressing device according to claim 1, further comprising a lower gas cooling die connected to the fixed lower body.

4. The pressing device according to claim 3, wherein, The lower gas cooling die is connected to the fixed lower body by one or more lower biasing elements that bias the lower gas cooling die away from the fixed lower body.

5. The pressing device according to claim 4, wherein the lower gas cooling die is at a predetermined second distance relative to the blank.

6. The pressing device according to claim 5, wherein the predetermined first distance is equal to the predetermined second distance.

7. The pressing device according to claim 3, wherein, The stopper is provided on the upper gas cooling die and is arranged to contact the lower gas cooling die to generate a force opposite to that of the upper biasing element.

8. The pressing device according to claim 4, wherein, Both the upper biasing element and the lower biasing element include one or more springs.

9. The pressing device according to claim 1, wherein, The upper gas cooling die includes a plurality of straight grooves connected to a pressurized gas reservoir, and the pressing device further includes a controller for controlling the gas passage through the straight grooves from the reservoir.

10. The pressing device according to claim 9, wherein, The lower gas cooling die includes a plurality of straight grooves connected to a pressurized gas reservoir, and the pressing device further includes a controller for controlling the gas passage through the straight grooves from the reservoir.

11. The pressing device according to claim 10, wherein, The straight grooves are oriented substantially perpendicular to the blank.

12. The pressing device according to claim 1, wherein, The upper pressing die and / or the lower pressing die of the pressing die include channels for conducting coolant or cooling air.

13. The pressing device according to claim 1, wherein, The pressing device is a mechanical press or a servo-mechanical press.

14. The pressing device according to claim 1, further comprising a first post-operation die configured to perform a first post-operation, wherein, The first post-operation die is disposed downstream of the pressing die and includes: Upper and lower first post-operation die pressing dies, wherein The upper first post-operation die pressing die is connected to the movable upper body, and the lower first post-operation die pressing die is connected to the fixed lower body, and wherein The blank transfer mechanism is further configured to transfer the blank from the pressing die to the first post-operation die.

15. A method for hot forming a blank, comprising: providing a pressing device according to any one of claims 1-14; providing a hot forming blank made of ultra-high strength steel (UHSS) with a zinc coating; heating the blank; placing the blank in the cooling die; cooling the blank while providing a downward pressing process of the movable upper body relative to the fixed lower body; performing an upward pressing process of the movable upper body relative to the fixed lower body; positioning the blank in the pressing die; and drawing the blank by performing downward and upward pressing processes of the movable upper body relative to the fixed lower body.

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