METHOD FOR SEALING A SEAM OF SEWING MATERIAL

Abstract

Method for manufacturing an interior component of a motor vehicle comprising the following steps: - Sewing (100) a fabric (3) using at least one upper thread (1) and at least one lower thread (2), wherein the lower thread (2) has at least one fusible component and a core made of a conductive material, - Heating (200) the fusible component of the lower thread (2) to form a form-fitting seal of a seam hole (6) of the seam, and - Back-foaming (400) of the sewing material (3) with a curable component.

Description

Technical field

[0001] The present invention relates to a method for sealing a seam of sewn material, as well as to a method for manufacturing an interior component of a motor vehicle. State of the art

[0002] Sewing textiles together, whether woven, knitted, or made of leather, is common practice in clothing manufacturing. But textiles also need to be sewn and subsequently processed in the production of sewn garments, such as leather or imitation leather upholstery, as well as molded skins, which are primarily used as interior components in automotive manufacturing.

[0003] However, the sewing process creates a hole in the fabric when the needle and thread pass through the woven or knitted material, resulting in a leak. Under unfavorable climatic conditions, moisture can penetrate through this hole, which, if a sewn garment is glued to a garment, can negatively affect the adhesive strength.

[0004] Often, garments made of sewing are coated with foam or similar components from the back, so that foam can penetrate through the needle holes on the visible side during the foaming process.

[0005] To avoid these disadvantages, it is a known and common practice to seal the seams. According to the state of the art, this is done, for example, using seam tapes that are glued or welded onto the seams. Such methods are described, for example, in DE 20 2015 106 803 U1, DE 197 19 282 A1, DE 603 ​​04 700 T2, DE 23 14 090 A or US 2012 / 0 042 817 A1. Another possibility is sealing the seams using reactive liquids or pastes.

[0006] DE 10 2011 075 827 A1 discloses an alternative method for sewing together a first and a second piece of material. In this method, the seam stub is thermally flattened by applying a force to the seam stub and simultaneously heating it.

[0007] The German patent application DE 10 2014 107 108 A1 describes a method for equipping a multi-layered molded body with a decorative seam. The yarn material of the decorative seam is coated with a thermally activatable adhesive.

[0008] However, these established methods have the disadvantage of requiring an additional process step and are therefore more time-consuming. They also result in increased material costs. Furthermore, these methods are disadvantageous because applying a seam tape adds an extra layer of material, which increases the thickness and can lead to undesirable unevenness or visible marks on the front surface caused by the sealing tape. Additionally, the extra layer of material reduces the flexibility of the seam.

[0009] Furthermore, lighting design in vehicle interiors is gaining increasing importance, leading to the use of sewn components in backlit applications. In this context, translucent or perforated materials are increasingly used in the decorative area, illuminated by lighting technology positioned on the reverse side, particularly across the entire surface. Design requirements necessitate the placement of functional or decorative seams within the sewn trim in the lighting design.

[0010] If the seam area lies on or near the illuminated area of ​​the decoration, unwanted light spots or light leaks occur at the needle holes, and light can penetrate through the seam holes to the viewer. These light spots appear in curved areas as well as flat areas, creating an uneven appearance or an inhomogeneous lighting design, and are therefore undesirable.

[0011] To seal the light spots at the needle holes, the use of standard seam tape would be conceivable, according to current technology. However, especially with components that are backlit across their entire surface, the seam tape can cast a shadow on the visible side, which disrupts the lighting design. Description of the invention

[0012] The invention is therefore based on the objective of providing a process-economically improved seam sealing of sewn materials, in particular for textiles or leather, without the use of seam tapes or reactive sealing materials.

[0013] This problem is solved by the subject matter of the independent claim. Further possible embodiments of the invention are specified in particular in the dependent claims.

[0014] One possible solution is to provide a method for sealing a seam of sewn material, comprising the steps of sewing the material using at least one top thread and at least one bottom thread, wherein at least the bottom thread has at least one meltable component, and heating at least the meltable component of the bottom thread to form a form-fitting seal of a seam hole in the seam.

[0015] It may also be provided that the upper thread has a meltable component to form a form-fitting seal of a seam hole in the seam.

[0016] By heating the meltable component of the lower thread and, if necessary, the meltable component of the upper thread, a form-fitting seal of a seam hole is created.

[0017] This offers several advantages: Firstly, the seal prevents moisture from penetrating through the seam. Secondly, the form-fitting seal prevents foaming or curing components, for example, from penetrating the fabric when the reverse side is exposed.

[0018] Furthermore, it is possible to prevent light from shining through the seam hole and, through the spot sealing, to prevent unwanted shadows. This is particularly important for components that are to be backlit across their entire surface, as it ensures that the defined lighting design remains unaffected.

[0019] These advantages can be particularly emphasized by using a dark or blackened underthread.

[0020] For the purposes of this invention, "sewing material" can be understood to mean any known woven, knitted, braided, sewn-in fabric, nonwoven fabric, felt, leather, plastics, 3D skins, textiles, or combinations thereof. Likewise, the materials of the textiles are not limited and can, for example, consist of natural or synthetic fibers.

[0021] Textiles made from commercially available synthetic leather, consisting of materials known in this field, are particularly preferred. Synthetic leather refers, for example, to imitation leather. Leather imitations may include an additional textile backing, but are not limited to this.

[0022] Furthermore, there are no restrictions on the types of leather, as any tanned animal hide can be used.

[0023] According to the present invention, sewing is carried out using at least one top thread and at least one bobbin thread, the bobbin thread having at least one fusible component. The type of seam is not limited, as any type of seam is suitable. Double lockstitch or chain stitch are preferred. During the sewing process, an interlocking of a top thread and a bobbin thread occurs in or below the needle hole, thereby creating a seam. A top thread is understood to be the thread that, when sewing with a sewing machine, is guided from above through the material by the sewing needle. Bobbin threads are those threads that, when sewing with a sewing machine, are fed to the material from the opposite direction to the top thread.

[0024] For example, stitch type 401, also known as a double chain stitch, can be used. In the double chain stitch 401, a three-layer thread build-up is achieved by interlacing the upper and lower threads. This allows for the use of a particularly thin lower thread compared to the upper thread. Specifically, the lower thread can be approximately 50% thinner than the upper thread. However, this does not preclude the use of a thicker lower thread.

[0025] Furthermore, the melting component is designed to bond with the decorative element itself, fusing the bobbin thread to the top thread. The top thread's stability is not affected during this fusing process. Depending on the specific fusing process, a slight fusing of the portion of the bobbin thread outside the needle hole may also occur.

[0026] The melting point in the lower part of the needle hole is located more towards the decorative side in the double chain stitch 401 than, for example, in a stitch type 301. It is designed so that the fusion on the reverse side of the decorative fabric is particularly even and does not bleed onto the front side, while also ensuring that the fusion does not detach from the needle holes during any subsequent processing.

[0027] Alternatively, stitch type 301, also known as double lockstitch, can be used. With double lockstitch 301, the bobbin thread must have a thickness that is either equal to or greater than the top thread.

[0028] As with stitch type 401, in stitch type 301 the melt component interlocks with the decorative fabric, creating at least a slight fusion between the bobbin and top threads. The top thread's stability is not affected by this fusion process. Also similar to stitch type 401, stitch type 301 ensures that the fusion on the reverse side of the decorative fabric is particularly even and does not bleed onto the front side. Furthermore, it is guaranteed that the fusion will not detach from the needle holes during any subsequent processes.

[0029] The fusion point in the needle hole is located in the lower part on the reverse side of the decorative fabric. Depending on the intended fusion process, a bobbin thread that is not in the needle holes will also be slightly fused and thus smoothed or displaced.

[0030] Furthermore, it should be noted that for both stitch type 301 and stitch type 401, process characteristics such as the material thickness of the decoration, the needle selection (point and thickness) of the sewing machine, the thread thickness of the upper thread and / or lower thread and the melt component are individually tailored to the product to be produced.

[0031] The seams can serve to connect individual parts of the fabric together, or they can be decorative seams, i.e., they have a decorative function without serving to connect individual parts of the fabric.

[0032] Sewing is preferably done using sewing machines commonly used in this field.

[0033] Commercially available threads of any standard thickness and material can be used as top threads for the process according to the invention. The top thread preferably does not contain a fusible component. The thread thickness is specified in Nm. The abbreviation Nm indicates how many meters of thread weigh 1 gram. The thickness of the top thread is not limited; preferably, the top thread has a thickness of approximately 12 to approximately 40 Nm, and particularly preferably of approximately 16 to approximately 20 Nm.

[0034] The meltable component may preferably be a thermoplastic component. A thermoplastic component of the present application is a plastic that exhibits deformability within a specific temperature range.

[0035] The thermoplastic component is not limited, as any suitable thermoplastic material can be used as the thermoplastic component.

[0036] The method according to the invention satisfactorily solves the problem. In particular, heating the meltable component of the lower thread results in a form-fitting seal of a seam hole and thus a sealing of the seam.

[0037] According to an advantageous further development of the invention, the seam is pressed together after heating.

[0038] Pressing the seam offers the advantage of improved sealing. Another benefit is that not only is the bobbin thread, including its fusible component, pressed into the stitch hole, but also the decorative foil's needle hole projections. Pressing can be performed using any known method. However, pressing with rollers, cylinders, or punches is preferred.

[0039] According to an advantageous embodiment of the invention, heating and pressing are carried out in a single step. This saves time, and pressing also improves the sealing effect.

[0040] According to a further preferred embodiment of the invention, the lower thread is selected from monofilament threads comprising a core sheathed with at least one meltable component, and multifilament threads comprising at least one meltable filament.

[0041] A monofilament thread preferably comprises a core encased in at least one meltable component. The core is not limited to specific components; preferably, it comprises natural or synthetic filaments. Thermosetting synthetic filaments and thermoplastic synthetic filaments with a melting point of 200°C or higher are particularly preferred. Monofilament threads have a smoother surface than multifilament threads.

[0042] Alternatively, the underlayer thread comprises a multifilament thread. In a multifilament thread, at least one filament comprising a meltable component and at least one filament comprising a non-meltable component are twisted together with a core. Furthermore, the meltable component is not limited and can be defined as previously described. The non-meltable component is also not limited and can preferably comprise natural or synthetic filaments. Thermoset synthetic filaments and thermoplastic synthetic filaments with a melting point of 200°C or higher are particularly preferred. The filaments can be obtained as chemically or mechanically produced spun fibers. Increased mechanical strength can be achieved by using a multifilament thread.

[0043] The thickness of the individual filaments is not limited; preferably, the thickness of the filaments is in the range of approximately 0.1 tex to approximately 0.9 tex. The thickness is specified in the unit tex, where 1 tex corresponds to a thickness of 1 gram per 1000 meters.

[0044] The length of the filaments is also not limited; preferably, staple fibers (i.e., finite fibers) or infinite filaments can be used. Depending on the desired thread thickness, approximately 2 to 5 filaments are twisted together with the core, resulting in a mini-filament thread, or a large number of filaments are twisted together with the core, resulting in a multi-filament thread.

[0045] A multifilament thread is particularly preferred, in which a core is twisted with a multitude of thermoplastic filaments.

[0046] Furthermore, the threads can be smooth or textured, which affects the volume formation.

[0047] According to an advantageous embodiment of the invention, the lower thread comprises a core made of a conductive material. A metal wire or a carbon fiber is particularly preferred. This offers the advantage that the seam can be fused by applying electrical energy.

[0048] According to a further development of the invention, the melting and pressing is carried out by means of hot air and direct roller pressing, IR irradiation with direct roller pressing, hot roller, hot wheel, hot pressing with forming tool, ultrasonic wheel, ultrasonic punch and application of electrical energy and pressing.

[0049] For fusing and pressing, an activation unit is provided, which is preferably arranged directly behind the sewing unit. Preferably, this activation unit is designed so that it can be switched off, swiveled away, or rotated. These represent cost-effective, readily available, and simple methods of fusing and pressing.

[0050] Another possible embodiment of the invention provides that the meltable component has a melting range of approximately 60°C to approximately 200°C. Within this melting range, the meltable component can be melted particularly easily, meaning under gentle conditions for the material being sewn.

[0051] According to an advantageous embodiment of the invention, the lower thread has a thickness of approximately 12 to approximately 40 Nm, preferably approximately 16 to approximately 20 Nm. Within this range, the thread offers easy processing combined with advantageous mechanical strength.

[0052] The solution according to the invention further comprises providing a method for manufacturing an interior component of a motor vehicle, which includes the following steps: sewing a material using at least one upper thread and at least one lower thread, wherein at least the lower thread has at least one meltable component, heating the meltable component of the lower thread to form a positive-locking seal of a seam hole of the seam, and back-foaming the material with a curable component.

[0053] Similar advantages arise as those already described in connection with the preceding embodiments. In the context of manufacturing an interior component, for example, preventing moisture from penetrating through the seam hole, but especially preventing the penetration of foaming or curing components, should be mentioned.

[0054] Furthermore, it can be ensured that the interior fittings component manufactured according to the invention can be used in a component that is backlit, in particular, because the occurrence of unwanted light leakage or shadows in the design is avoided.

[0055] Furthermore, the invention relates to a non-inventive use of a lower thread comprising at least one meltable component for sealing a seam of sewn material. The lower thread can be a lower thread as already defined in one of the preceding embodiments. Likewise, the meltable component can be a component as already defined in one of the preceding embodiments.

[0056] The use of a bobbin thread containing a meltable component offers comparable advantages to those already described above. In this case, using a bobbin thread with a meltable component allows for a form-fitting seal of the seam hole by heating the meltable component after the fabric has been sewn using a top thread and the bobbin thread. This seal prevents moisture and foaming or hardening components from passing through the seam hole.

[0057] The use of textiles or leather obtainable according to the present invention is not limited; a wide variety of applications are conceivable.

[0058] Preferred use is as sewn-in garments or molded skins as interior trim components in the automotive sector. Individual pieces of textiles or leather can be sewn together and the seam sealed according to the present invention. When used as interior trim components, these are often coated with foams or adhesives from the reverse side. The seam sealing according to the present invention prevents the foams or adhesives from penetrating the seam. Furthermore, it also prevents moisture from penetrating through the seams. Brief description of the drawings

[0059] The drawing used to explain the exemplary embodiment shows: Fig. 1 an exemplary illustration of the merging of a seam made using a double lockstitch, and Fig. 2 a flowchart of an embodiment of the method according to the invention.

[0060] The Fig. Figure 1 shows an exemplary representation of the fusing of a seam made using a double lockstitch. The material 3 is shown schematically but can comprise any known form of a flat material, preferably a textile or leather, as already described in connection with the preceding embodiments. The upper thread 1 corresponds to a commercially available thread, which does not contain a fusible component. The lower thread 2 includes a fusible component which exhibits deformability above a certain temperature range.

[0061] The illustration shows the heating and simultaneous pressing of a seam made with a double lockstitch. The sewing of the material 3, using a top thread 1 and a bobbin thread 2, the bobbin thread 2 having a fusible component, has already been completed. The top thread 1 passes through the material 3 and is intertwined with the bobbin thread 2, thus forming a seam opening 6. The fusible component of the bobbin thread 2 is heated by a hot wheel 4 to create a positive seal of the seam opening 6. This melts the fusible component of the bobbin thread 2, forming a fused area 5 that creates a positive connection between the material 3, the top thread 1, and the bobbin thread 2, thus sealing the seam opening 6.On the other hand, the seam is pressed using the hot wheel 4, whereby heating and pressing occur in a single step. Thus, the use of a hot wheel 4 enables a particularly efficient implementation of the inventive method. Heating with the hot wheel 4 takes place immediately after sewing 100. Instead of the hot wheel 4, heating and pressing can be carried out using hot air and direct roller pressing, infrared irradiation with direct roller pressing, a hot roller, hot pressing with a forming tool, an ultrasonic wheel, an ultrasonic punch, and application of electrical energy and pressing. After pressing, a fused area 5 is formed, which creates the positive-locking seal of the seam hole 6.

[0062] The lower thread 2 is a multifilament thread with a melting range of approximately 60°C to approximately 200°C. Furthermore, the lower thread 2 in this example has a favorable thickness of approximately 12 to approximately 40 Nm. Alternatively, instead of a multifilament thread of... Fig. 1. A monofilament thread can be used.

[0063] The Fig. Figure 2 shows a flowchart of an embodiment of the inventive method for sealing a seam of sewing material 3.

[0064] The process comprises, in a first step, sewing 100 of the material 3 using at least one upper thread 1 and at least one lower thread 2, wherein the lower thread 2 has at least one meltable component.

[0065] In a second step, the process includes heating 200 of the meltable component of the lower thread 2 to form a form-fitting seal of a seam hole 6 of the seam.

[0066] In a third step, the seam is pressed 300 mm. According to the in Fig. In the embodiment shown in Figure 2, the heating 200 of the meltable component of the lower thread 2 takes place separately from the pressing step 300, which is carried out subsequently. However, it is particularly efficient if the heating step 200 and the pressing step 300 are carried out in a single step. REFERENCE MARK LIST 1 upper thread 2 lower threads 3 Sewing materials 4 Hot Wheel 5 merged area 6 stitch holes 100 Sewing 200 Merge 300 Pressing 400 back-foaming

Claims

[1] Method for manufacturing an interior component of a motor vehicle comprising the steps: - Sewing (100) a fabric (3) using at least one upper thread (1) and at least one lower thread (2), wherein the lower thread (2) has at least one fusible component and a core made of a conductive material, - Heating (200) the fusible component of the lower thread (2) to form a form-fitting seal of a seam hole (6) of the seam, and - Back-foaming (400) of the sewing material (3) with a curable component. [2] Method according to claim 1, wherein after heating (200) the seam is pressed (300). [3] Method according to claim 1, wherein the heating (200) and pressing (300) of the seam is carried out in a common step. [4] Method according to any one of claims 1 to 3, wherein the lower thread (2) is selected from monofilament threads comprising a core sheathed with at least one fusible component, and multifilament threads comprising at least one fusible filament. [5] Method according to any one of claims 1 to 4, wherein the lower thread (2) comprises a core made of a conductive material. [6] Method according to any one of claims 2 to 5, wherein the heating (200) and pressing (300) is selected from heating (200) and pressing (300) by means of hot air and direct roller pressing, infrared irradiation with direct roller pressing, hot roller, hot wheel (4), hot pressing with forming tool, ultrasonic wheel, ultrasonic punch and application of electrical energy and pressing. [7] Method according to any one of claims 1 to 6, wherein the fusible component has a melting range of about 60°C to about 200°C. [8] Method according to any one of claims 1 to 7, wherein the lower thread (2) has a thickness of about 12 to about 40 Nm, preferably of about 16 to about 20 Nm.

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