Method for producing a support structure for a vehicle door

Abstract

A method (1000) for manufacturing a load bearing structure (100) for a tailgate (200) of a vehicle by thermoforming, the method comprising: obtaining a thermoforming press comprising a punch (1050a) and a die (1050b), where the punch and die (1050a, 1050b) comprise a variable maximum distance between the punch and die; heating (1200) a sheet (1010) of thermoplastic material having a size equal to that of the load-bearing structure (100) of the vehicle tailgate; cooling the male die and the female die; placing the sheet of thermoplastic material (1010) between the male and female dies (1050a, 1050b), operating (1300, 1400) the male and female dies (1050a, 1050b) such that the sheet of thermoplastic material (1010) is pressed to obtain a load bearing structure (100); and dimensionally stabilizing (1500) the load bearing structure (100).

Description

[0001] Purpose of the Invention

[0002] The object of the invention relates to a method for producing a load-bearing structure for a vehicle door and a method for producing a tailgate of a vehicle comprising such a load-bearing structure.

[0003] The load-bearing structure is obtained from a thermoplastic material by a thermoforming method. Background Art

[0004] Door openers or tailgates for cars are constantly evolving to achieve lower cost and weight. Traditionally, these door openers or tailgates for cars have been made of steel or aluminum, the latter seeking to reduce weight.

[0005] It is known that weight reduction can be achieved using compression molding methods CMS and glass fiber reinforced thermoplastics GMT or injection thermoplastics, but the high cost of thermosetting technologies or the limitations of injection mold size, as well as the costs and investments associated with injection technology for large parts, have prevented the development of these technologies from becoming mainstream in the manufacture of large load-bearing structures in the automotive industry.

[0006] The present invention solves the disadvantages of existing manufacturing methods for obtaining a load-bearing structure suitable for a car tailgate. Summary of the invention

[0007] The present invention relates to a method for manufacturing a load-bearing structure for a vehicle door opener, in particular for a vehicle tailgate. In other aspects, the present invention relates to a load-bearing structure obtained by the manufacturing method, and to a vehicle tailgate comprising the load-bearing structure.

[0008] In a preferred embodiment, the structure comprises a tailgate made of thermoplastic material with a high content of structural fibers, glass, carbon, Kevlar, etc. The manufacturing method according to the invention uses thermoforming technology.

[0009] Furthermore, one of the great advantages of the invention is the possibility of making in a thermoforming press a load-bearing structure that can have large dimensions, which, taking into account current syringe size limitations, is a distinct advantage compared to the injection method, in addition to its enormous cost, which often forces it to be divided into two or more parts that must be assembled later, which also adds additional cost and complexity.

[0010] In the present invention, the use of various materials is proposed by thermoforming methods and thermoplastic methods, such as short fiber, long fiber polypropylene sheets or materials formed by layers or continuous fiber fabrics embedded in a thermoplastic substrate.

[0011] In one particular embodiment, the manufacturing method consists in introducing inside the door an internal metal substructure formed by profiles and / or tubes, by means of connection means, so as to increase the rigidity of the door and allow a reduction in the structural loads of the thermoformable plastic.

[0012] Another advantage obtained with the manufacturing method according to the invention is the use of the excess material found in the opening of the door in which the door glass will later be installed. The manufacturing method thus makes it possible to exploit this excess thermoformed material from the opening of the door to produce an auxiliary part which, after the finishing step, can form part of an assembly, such as a reinforcement or a structural support.

[0013] In another aspect according to the invention, the structure or door can be divided into two parts, upper and lower, for the purpose of demoulding or other technical interests. In this case, the manufacturing method according to the invention proposes in an innovative way to create a central overlap between the two parts, which makes it possible to provide rigidity to the final assembly and to accommodate elements such as a windshield wiper motor or other elements.

[0014] Finally, as a possibility of the invention, a design is included which comprises a visible part of the interior, making it unnecessary to install a supplementary decoration, thus converting the structural part into a part visible to the passengers of the vehicle.

[0015] This manufacturing method thus allows obtaining a structural support which is visible from the inside of the vehicle and on which other elements such as glass, skins, locks, windscreen wipers, wiring, shock absorbers, etc. are mounted.

[0016] Thermoforming of thermosets is widely used in industry due to their high rigidity characteristics, but thermoforming of thermoplastics in large parts is not common because large parts mean high complexity. The present invention solves this complexity through the following manufacturing method:

[0017] In a first aspect, the invention relates to a method for manufacturing a load-bearing structure for a tailgate of a vehicle by thermoforming. The method comprises heating a sheet of thermoplastic material having dimensions equal to the load-bearing structure of the vehicle tailgate to a temperature between [200,400]°C, obtaining a male mould and a female mould. The dimensions of the sheet of thermoplastic material are calculated based on the dimensions of the load-bearing structure and its flat development, introducing elongated thermoplastic material in specific areas and increasing the dimensions for correct positioning and fixing of the thermoplastic material on the mould.

[0018] In the pressing step, the punch and the die include a variable maximum distance between the punch and the die. The method also includes calculating a maximum distance d1 between the punch and the die, wherein d1 is equal to the thickness of the load-bearing structure in a flat area of ​​the load-bearing structure, calculating a maximum distance d2 between the punch and the die, wherein d2 is the thickness of the load-bearing structure in a curved area of ​​the load-bearing structure, and wherein d2 is less than d1 in one or more areas of the load-bearing structure. The method also includes cooling the punch and the die between [30,50]°C, placing a thermoplastic material sheet between the punch and the die, actuating the punch and the die so that the thermoplastic material sheet is pressed at a temperature between [180,210]°C and a pressure between [50,100]Kg / cm2 to obtain a load-bearing structure, wherein the flat area and the curved area of ​​the load-bearing structure are equal to d1 and d2, and the load-bearing structure is dimensionally stable.

[0019] In one example, the method further comprises introducing an inner metal substructure consisting of profiles and / or tubes into the load-bearing structure by means of a connecting device.

[0020] In a first example, the manufacturing method further comprises, during the pressing step or the pressing actuation step, obtaining an opening configured to accommodate the glass of the tailgate, and generating an additional thermoplastic material block by obtaining the opening. In addition, the method comprises thermoforming an auxiliary element of the tailgate structure by using the additional thermoplastic material block.

[0021] In a second example, the manufacturing method further comprises obtaining an opening configured to accommodate the tailgate glass during a cutting step after the pressing or pressing actuation step, and producing an additional thermoplastic material block by obtaining the opening. In addition, the method comprises obtaining an auxiliary element of the tailgate structure by thermoforming using the additional thermoplastic material block.

[0022] In a second aspect, the present invention relates to a load-bearing structure for a vehicle tailgate obtained by the manufacturing method according to the first aspect of the present invention.

[0023] The invention also relates to the use of a load-bearing structure as an interior decoration of a tailgate of a vehicle.

[0024] In a third aspect, the invention relates to a second method for manufacturing a load-bearing structure for a tailgate of a vehicle by thermoforming, wherein the load-bearing structure comprises an upper substructure and a lower substructure. The method comprises heating a first thermoplastic material sheet having dimensions equal to the upper substructure of the load-bearing structure to a temperature between [200, 400]°C, and heating a second thermoplastic material sheet having dimensions equal to the lower substructure of the load-bearing structure to a temperature between [200, 400]°C.

[0025] The method includes: obtaining a punch and a die for each material sheet, wherein the punch and the die include a variable maximum distance between the punch and the die during a pressing step; calculating at least one maximum distance d1 between the punch and the die, wherein d1 is equal to the thickness of a flat area in each substructure; calculating at least one maximum distance d2 between the punch and the die, wherein d2 is equal to the thickness of a curved area in each substructure, and wherein in one or more areas of the load-bearing structure, d2 is less than d1.

[0026] The method further comprises cooling the male and female dies at a temperature between [30, 50]°C, placing each thermoplastic sheet between the male and corresponding female dies, and actuating the dies so as to press the thermoplastic sheet at a temperature between [180, 210]°C and a pressure between [50, 100] Kg / cm2 to obtain a substructure, wherein the flat area and the curved area of ​​the substructure are equal to d1 and d2. The method further comprises dimensionally stabilizing the substructure.

[0027] Finally, the method comprises a step of assembling the upper substructure and the lower substructure to obtain a load-bearing structure.

[0028] In one example, the method further comprises introducing an inner metal substructure consisting of profiles and / or tubes into the load-bearing structure by means of connecting means.

[0029] In a first example, the method further comprises obtaining during the pressing step an opening configured for receiving a tailgate glass, wherein said obtaining produces an additional piece of thermoplastic material, and obtaining the auxiliary element of the tailgate structure by thermoforming using the additional piece of thermoplastic material.

[0030] In a second example, the method further comprises obtaining an opening configured for receiving a tailgate glass during a cutting step after the pressing step, wherein the obtaining produces an additional piece of thermoplastic material, and obtaining an auxiliary element of the tailgate structure by thermoforming using the additional piece of thermoplastic material.

[0031] In a fourth aspect, the invention relates to a load-bearing structure for a tailgate of a vehicle obtained by the manufacturing method according to the invention.

[0032] The invention also relates to the use of a load-bearing structure according to the invention as a decoration for a tailgate of a vehicle.

[0033] In a last aspect, the invention relates to a tailgate comprising a load-bearing structure according to the invention and one or more of the following elements: glass, plastic or metal skin, motor and / or electronics. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] To supplement the description that is being made, and to help better understand the characteristics of the manufacturing method according to a preferred example of its practical implementation, a set of drawings is attached as an integral part of said description, in which, by way of illustration and not limitation, the following are represented:

[0035] Figure 1 A manufacturing method according to the present invention is shown.

[0036] FIG. 2 shows a load-bearing structure obtained by the manufacturing method according to the present invention.

[0037] Figure 3 A load-bearing structure integrated as part of a vehicle tailgate is shown.

[0038] Figure 4 A first exploded view of an example of a load-bearing structure obtained by the manufacturing method according to the invention is shown and wherein the load-bearing structure comprises an inner metal substructure formed by profiles and / or tubes.

[0039] Figure 5 A second exploded view of an example of a load-bearing structure obtained by the manufacturing method according to the invention is shown and wherein the load-bearing structure comprises an inner metal substructure formed by profiles and / or tubes.

[0040] Figure 6 Examples of load-bearing structures comprising an inner metal substructure formed from profiles and / or tubes are shown.

[0041] Figure 7 A vehicle tailgate comprising a load-bearing structure obtained by the manufacturing method according to the invention is shown. DETAILED DESCRIPTION

[0042] Figure 1 A method 1000 for manufacturing a load-bearing structure 100 for a vehicle tailgate 200 by thermoforming is shown.

[0043] The manufacturing method 1000 includes obtaining 1100 a sheet of thermoplastic material 1010 having dimensions equivalent to a load-bearing structure 100 for a tailgate 200 of a vehicle, and obtaining a thermoforming press including a male mold 1050a and a female mold 1050b, wherein the male mold 1050a, and the female mold 1050b include a variable maximum distance between the male and female molds 1050a, 1050b.

[0044] In order to obtain the variable distance, the manufacturing method 1000 includes calculating at least one maximum distance d1 between the punch 1050a and the die 1050b, wherein d1 is equal to the thickness of the load-bearing structure 100 in a flat area of ​​the load-bearing structure 100 or is proportional to the thickness of the load-bearing structure 100 in a flat area of ​​the load-bearing structure 100, and calculating at least one maximum distance d2 between the punch 1050a and the die 1050b, wherein d2 is the thickness of the load-bearing structure 100 in a curved area of ​​the load-bearing structure 100, wherein in one or more areas of the load-bearing structure 100, d2 is less than d1.

[0045] The manufacturing method 1000 includes heating 1200 a sheet of thermoplastic material 1010 at a temperature between [200, 400]°C.

[0046] The manufacturing method 1000 includes cooling the male mold 1050a and the female mold 1050b within a temperature range between [30, 50]°C.

[0047] The manufacturing method 1000 includes placing a sheet of thermoplastic material 1010 between a male mold 1050a and a female mold 1050b, as shown at 1300.

[0048] Manufacturing method 1000 includes: actuating 1300, 1400 the male and female molds so as to press the thermoplastic material sheet at a temperature range between [180, 210] ° C and a pressure range between [50, 100] Kg / cm2 to obtain a load-bearing structure 100, wherein the flat area and the curved area of ​​the load-bearing structure are equal to d1 and d2.

[0049] Finally, the manufacturing method 1000 includes dimensionally stabilizing 1500 the load-bearing structure 100 .

[0050] The advantages of the manufacturing method 1000 are multiple:

[0051] The cost is much lower than other manufacturing methods using injection or metal stamping, especially in large parts such as the tailgate of an automobile described in this invention. Another advantage is the lower cost of thermoforming molds compared to injection molds.

[0052] In a particular example, this manufacturing method 1000 comprises a step of introducing an internal metal substructure 160 formed by a profile and / or a tube into the load-bearing structure 100 by means of connecting means.

[0053] Figure 2a The load-bearing structure 100 obtained by the manufacturing method 1000 is shown.

[0054] In another example, the load-bearing structure 100 may be obtained by assembling an upper substructure and a lower substructure to obtain the load-bearing structure 100. The upper substructure and the lower substructure may also be obtained by the manufacturing method 1000 and assembled by a connecting device.

[0055] The load-bearing structure 100 may include an opening 150 obtained during the pressing step, the opening 150 being configured to receive the tailgate 200 ( Figure 4 The glass of the tailgate 200 shown in FIG. Figure 2b As shown, the additional or excess thermoplastic material from the opening 150 may result in a set of auxiliary elements 150 a of thermoplastic material. The set of auxiliary elements 150 a may be used as an integral part of the structure of the tailgate 200 .

[0056] In another example, the opening 150 may be obtained during a cutting step after the pressing step.

[0057] Figure 2c The load-bearing structure 100 obtained by the manufacturing method 1000 is shown, and in which the opening 150 can be seen, without the set of auxiliary elements 150a obtained from the additional thermoplastic material.

[0058] Figure 3 The integral parts of the tailgate 200 are shown, such as the load-bearing structure 100 and a set of parts 200 a, such as glass, plastic or metal skin, engine and / or electronics.

[0059] Figure 4 and Figure 5 Two exploded views of another example of a load-bearing structure 100 obtained by a manufacturing method 1000 according to the invention are shown. The load-bearing structure 100 comprises an opening 150 and a set of auxiliary elements obtained by additional or excess thermoplastic material of said opening 150. Furthermore, this example of the load-bearing structure 100 comprises an internal metal substructure 160 formed by profiles and / or tubes, by means of connection means to increase the rigidity of the tailgate 200 and allow reducing the structural loads of the thermoformable plastic.

[0060] Figure 6 Shows Figure 4 and Figure 5 An example of a load-bearing structure 100 comprising an inner metal substructure 160 formed by profiles and / or tubes and connected to the load-bearing structure 100 by connecting means.

[0061] Figure 7 A tailgate 200 comprising the load-bearing structure 100 obtained by the manufacturing method 1000 is shown.

Claims

1. A method (1000) for manufacturing a load-bearing structure (100) for a tailgate (200) of a vehicle by thermoforming, the method comprising: - obtaining a thermoforming press comprising a male die (1050a) and a female die (1050b), wherein said male die and said female die (1050a, 1050b) comprise a variable maximum distance between said male die and said female die (1050a, 1050b); - calculating at least one maximum distance (d1) between the male mould and the female mould (1050a, 1050b), wherein (d1) is equal to the thickness of the support structure (100) in a flat area of ​​the support structure (100); - calculating at least one maximum distance (d2) between the male die and the female die (1050a, 1050b), wherein (d2) is the thickness of the load-bearing structure (100) in a curved region of the load-bearing structure (100), wherein in one or more regions of the load-bearing structure (100), (d2) is less than (d1); - heating (1200) a sheet of thermoplastic material (1010) having dimensions equal to the load-bearing structure (100) of the tailgate (200) of the vehicle to a temperature between [200,400]°C; - Cooling the male and female dies (1050a, 1050b) at a temperature between [30,50]°C; - placing the sheet of thermoplastic material (1010) between the male and female moulds (1050a, 1050b); - actuating (1300, 1400) the male and female dies (1050a, 1050b) so as to compress the thermoplastic sheet (1010) at a temperature between [180, 210]°C and a pressure between [50, 100] Kg / cm2 to obtain the load-bearing structure (100), wherein the flat area and the curved area of ​​the load-bearing structure (100) are proportional to (d1) and (d2), and - Dimensionally stabilizing (1500) the load-bearing structure (100).

2. The method (1000) for manufacturing a load-bearing structure (100) for a tailgate (200) of a vehicle according to claim 1, further comprising: - Inserting an internal metal substructure (160) comprising profiles and / or tubes into the load-bearing structure (100) by means of connecting means.

3. The method (1000) for manufacturing a load-bearing structure (100) for a tailgate (200) of a vehicle according to claim 1 or 2, the method further comprising: - obtaining an opening (150) configured to receive the glass of said tailgate (200) during said actuation step (1300, 1400), wherein obtaining said opening (150) generates an additional block of thermoplastic material; or - obtaining an opening (150) for receiving the glass of said tailgate (200) during a cutting step subsequent to said actuation step (1300, 1400), wherein obtaining said opening (150) generates an additional block of thermoplastic material; as well as - Obtaining the auxiliary element (150a) of the tailgate structure (200) by thermoforming the additional piece of thermoplastic material.

4. A load-bearing structure (100) for a tailgate (200) of a vehicle, the load-bearing structure (100) being obtained by the manufacturing method according to claims 1 to 3.

5. Use of the load-bearing structure (100) according to claim 4 as a decoration for a tailgate (200) of a vehicle.

6. A method (1000) for manufacturing a load-bearing structure (100) for a tailgate (200) of a vehicle by thermoforming, wherein: The load-bearing structure (100) comprises an upper substructure and a lower substructure, and for each substructure, the manufacturing method (1000) comprises: - obtaining a thermoforming press comprising a male die (1050a) and a female die (1050b), wherein said male die and said female die (1050a, 1050b) comprise a variable maximum distance between said male die and said female die (1050a, 1050b); - calculating at least one maximum distance (d1) between the male mould and the female mould (1050a, 1050b), wherein (d1) is equal to the thickness of the upper substructure or the lower substructure in a flat area of ​​the upper substructure or the lower substructure; - calculating at least one maximum distance (d2) between the male mould and the female mould (1050a, 1050b), wherein (d2) is the thickness of the load-bearing structure (100) in a curved region of the upper substructure or the lower substructure, wherein in one or more regions of the upper substructure or the lower substructure, (d2) is smaller than (d1); - heating (1200) a sheet of thermoplastic material (1010) having dimensions equal to the upper substructure or the lower substructure of the tailgate (200) of the vehicle to a temperature between [200,400]°C; - Cooling the male and female dies (1050a, 1050b) at a temperature between [30,50]°C; - placing the sheet of thermoplastic material (1010) between the male and female moulds (1050a, 1050b); - actuating (1300, 1400) the male and female dies (1050a, 1050b) so as to press the thermoplastic sheet (1010) at a temperature between [180, 210]°C and a pressure between [50, 100] Kg / cm2 to obtain the upper substructure or the lower substructure, wherein the flat area and the curved area of ​​the upper substructure or the lower substructure are proportional to (d1) and (d2), and - Assembling the upper substructure and the lower substructure by means of connecting means to obtain the load-bearing structure (100).

7. The method (1000) for manufacturing a load-bearing structure (100) for a tailgate (200) of a vehicle according to claim 6, further comprising: - An internal metal substructure (160) formed of profiles and / or tubes is introduced into the load-bearing structure (100) by means of connecting means.

8. The method (1000) for manufacturing a load-bearing structure (100) for a tailgate (200) of a vehicle according to claim 6 or 7, the method further comprising: - obtaining an opening (150) configured to receive the glass of the tailgate (200) during the actuation step (1300, 1400), wherein obtaining the opening (150) generates an additional block of thermoplastic material; or - obtaining an opening (150) configured to receive the glass of said tailgate (200) during a cutting step subsequent to said actuation step (1300, 1400), wherein obtaining said opening (150) generates an additional block of thermoplastic material; as well as - Obtaining the auxiliary element (150a) of the tailgate structure (200) by thermoforming the additional piece of thermoplastic material.

9. A load-bearing structure (100) for a tailgate (200) of a vehicle, the load-bearing structure (100) being obtained by the manufacturing method according to claims 6 to 8.

10. Use of the load-bearing structure (100) according to claim 9 as a decoration for a tailgate (200) of a vehicle.

11. A tailgate (200) for a vehicle, comprising the load-bearing structure (100) according to claim 4 or 9.

12. The tailgate (200) for a vehicle according to claim 11, further comprising one or more of the following elements: - glass or plastic glass; - Plastic or metal cover; - one or more motors; -Electronic devices; - at least one lock; - shock absorbers; - Windshield wipers; -Spoilers to improve aerodynamics; - Headlights; -sensor; -wiring; and / or - Components for improving the vibroacoustic properties of the tailgate (200).

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