Sewing device and method for sewing a material structure comprising a spacer textile

Abstract

Sewing device comprising a machine sewing unit, a presser foot, and a stitch plate with a stitch hole, wherein a foot plate (2) of the presser foot is arranged with its underside at a distance from the stitch plate that corresponds to the height of a sewn material structure (30). According to the invention, a horizontally arranged sliding pin (22) is included, which is movable axially perpendicular to the seam direction and is guided on the side of the needle facing away from the finished seam (32) over the material structure (30) in the region of the resulting seam (32) before the needle penetrates the material structure (30), and is retracted from the region of the seam (32) before the material structure (30) is advanced by a next stitch length (34).Method, comprising the steps: a) the sliding pin (22) is pushed over the seam area; b) the needle is lowered into a needle passage (4) and through the foot plate (2) and the material structure (30) to a bottom dead center, at the same time the needle thread (16) is presented for an interlacing of the needle thread (16) and the bobbin thread (18); c) the interlacing of the needle thread (16) and the bobbin thread (18) takes place; d) the needle is raised to the top dead center, at the same time the needle thread (16) presented for the interlacing is retracted and the stitch (34) is tightened; e) the sliding pin (22) is pulled out under the stitch (34); f) the material structure (30) is advanced by a next stitch length (34).

Description

[0001] The invention relates to a sewing device and a method for sewing a material structure comprising a spacer textile, comprising a machine sewing unit, a presser foot and a lower stitch plate with a stitch hole, wherein a foot plate of the presser foot is arranged with its underside at a distance from the stitch plate which corresponds to the height of a sewn material structure along a seam.

[0002] The stitch-through process is the most commonly used joining method for producing, for example, 3D textile nonwovens for thermal insulation. In such a thermal insulation system, the textile layers fulfill functions such as water resistance, wind resistance, and moisture transport, while the function of the 3D nonwoven is to provide thermal insulation.

[0003] The main problem with joining by sewing is that the thread systems involved in the sewing process compress the 3D shape of the nonwoven fabrics along the entire length of the stitch lines. These compressions are referred to as thermal bridges. These compression points are present along the entire stitch line and force the air trapped in the insulation material to leave the structure. In this way, the joining zone of the sewing process provides a pathway for heat transfer. With the through-stitched sewing method, joining zones generally compromise product functionality, and this is considered a byproduct of current sewing technology.

[0004] Spacer textiles are known as spacer fabrics or spacer wovens for technical applications, but also as composite materials, such as a multi-layer construction of heat-insulating or insulating clothing products suitable for extreme weather conditions, such as quilted jackets, as well as quilted blankets, sleeping bags, and similar products. These are manufactured in a multi-layer construction with insulation material sandwiched between several layers of textile surfaces, which can also be water-repellent, for example.

[0005] Spacer fabrics often require stitching to achieve a specific technical effect or to maintain a final product shape. The spacer fabrics can be stitched to another fabric of lower height, or the spacer fabrics can be stitched to each other. In either case, compression caused by thread tension and / or the presser foot, which results in a reduction in height, is undesirable.

[0006] To prevent unwanted or even functionally damaging displacement of the individual layers of a multi-layer structure, the surface is usually stitched with stitched seams. These seams can then serve a decorative function in addition to their securing function, depending on their arrangement.

[0007] However, the known and commonly used sewing technology compresses the spacer fabric, spacer woven fabric, or intermediate layer, e.g., the insulation material, in the seam area where the needle penetrates the layered material and inserts the sewing threads under tension. This causes the layered material in the seam area, where the seam is to be formed or has already been formed, to become thinner compared to the rest of the material surface due to the tension of the sewing thread, e.g., the needle thread and the bobbin thread. Due to the resulting reduced volume, less heat-insulating or heat-insulating air is present in the porous structure of the insulation material. This leads to local thermal bridges in the seam areas, which cause heat loss at these locations. These locations can therefore be referred to as "cold spots."In industrial practice, these cold spots are inevitably accepted because there is currently no other industrially viable option for product optimization. In spacer fabrics or spacer wovens intended, for example, to provide a filtering effect, clogging occurs in the sewn or quilted areas.

[0008] One attempt to solve this problem is presented in DE 10 2016 110 156 A1, which uses a second stitch plate beneath the upper textile layer of a layered construction. However, this solution cannot be applied to spacer fabrics or woven spacers because the lower and upper textile layers are already connected, preventing the use of an upper stitch plate. Further disadvantages include the inability to create curved seams and the inability to cross seams.

[0009] The document DE 2 226 630 A describes a thermal insulation material that is particularly suitable for quilts, sleeping bags, or clothing. In contrast to previously known quilts with quilted channels, which often have "cold spots," this invention uses a coherent filling material (e.g., felt or fleece) in sheet or strip form. This is attached between two layers of an outer material using loose quilting stitches that fix the material in place but do not exert strong pressure. This ensures that the insulation material remains evenly distributed and is not compressed, enabling uniform thermal insulation without cold bridges.

[0010] US 2003 0 145 773 A1 describes a heat-insulating, conformable blanket for use in high-temperature applications, particularly in aerospace. The blanket consists of a rigid, ceramic fiber batting sandwiched between an outer and inner insulation layer. These layers are sewn together with temperature-resistant threads, with the construction being selected to limit pillowing to a maximum of 0.03 inches and prevent compression of the fiber batt. The outer insulation layer and the adjacent part of the batt can also be coated with a ceramic coating to create a durable surface. The result is a smooth, reusable, and aerodynamically suitable thermal insulation that represents a more cost-effective alternative to ceramic heat-shielding tiles.

[0011] The publication US 2015 0 330 005 A1 relates to a system and method for influencing the knot position when sewing with a sewing machine. The goal is to precisely control the position of the knot between the upper and lower threads to achieve optimal seam quality. For each stitch or group of stitches, a computer calculates a control value for an actuator that regulates the thread tension—in particular, the braking force of the upper thread. This control allows the knot position to be specifically shifted within the material, e.g., toward the center of the material. At the same time, compression of the sewn layers is avoided. The calculation takes into account many parameters such as stitch length, width, needle position, and material feed. Furthermore, the system can prioritize stitch precision or sewing speed using stored reference values ​​and user-defined specifications.

[0012] The technique also allows the definition of stitch groups with deliberately varying node positions for design effects.

[0013] GB 787 151 A describes a sewing device for the continuous sewing of felt or mats made of mineral fibers, particularly glass wool, which are often provided with protective layers (e.g. paper), without compression. In contrast to the usual step-by-step feed, the material is fed continuously here, with the needle moving synchronously with the movement of the material without losing its vertical alignment. This prevents the strong accelerations otherwise necessary with rigid materials during stop-and-go operation. A special mechanism with a needle carrier, eccentric, and control system ensures that the needle moves with the feed movement while penetrating the material. The device is particularly suitable for heavy and stiff materials that are difficult to move jerkily. In addition, it can be operated with several needles simultaneously, which enables multiple seams.

[0014] The state-of-the-art solutions are not suitable for introducing curved and crossed seams into a spacer textile without compressing the spacer textile.

[0015] It is therefore an object of the invention to provide a sewing device and a method for sewing at least one spacer textile, in which there is no compression of the spacer textile in the seam area and curved and crossed seams can be produced.

[0016] The object is achieved by a sewing device comprising a machine sewing unit, a sewing foot and a lower stitch plate with a stitch hole, wherein a foot plate of the sewing foot is arranged with its underside at a distance from the stitch plate which corresponds to the height of a sewn material structure along a seam.

[0017] According to the invention, a horizontally arranged push pin is included, which can be moved axially perpendicular to the seam direction. This push pin is guided over the material buildup in the area of ​​the seam being formed on the side of the needle facing away from the finished seam before the needle penetrates the material buildup, and is retracted from the seam area before the material buildup is advanced by the next stitch length. For this purpose, the lower side of the presser foot has a horizontal recess, in particular a bore, in which the push pin moves back and forth, holding the needle thread during stitch formation.

[0018] With the new invention, the lowest position of the special presser foot and its footplate is not where it touches the needle plate, as is the case with conventional sewing machines. Instead, there is a specific distance between the underside of the presser foot or footplate and the needle plate.

[0019] The 3D stitch formation in the invention can only be achieved in combination with the holding of the needle thread using the inventive mechanism, in particular the push pin, before the needle penetrates the material to be sewn, the material structure. This occurs at approximately 80° - 90° during the stitch formation cycle over a total of 360°, while the push pin is inserted at 50°. The needle thread must be held in place until the thread requirement for stitch formation, the length of the needle thread drawn from the spool, is met. Both the non-compressed material in the sewing zone, in the area of ​​the resulting seam, and the holding of the needle thread to create the stitch height are key components that must be implemented to implement the inventive method.

[0020] It has proven advantageous if the sliding pin slides in a horizontal recess in the foot plate, aligned perpendicular to the seam, in order to emerge from a needle passage in the foot plate above the area of ​​the seam being formed and become effective there. The recess can, for example, be a hole in which the cylindrical sliding pin slides. When the sliding pin is pulled out, it disappears from the needle passage in the foot plate; when it is pushed in, it appears in the needle passage and becomes effective there by holding the needle thread. The needle thread can then no longer cut into the material structure and compress it in an undesirable way when it is pulled back by the thread take-up lever. The result is a stitch with an essentially rectangular cross-section.

[0021] A slide pin isn't required for the bobbin thread, as the hole in the needle plate through which the needle passes can already serve the same purpose. The bobbin thread requirement is regulated by simply pulling on the needle thread, so there's no risk of compression of the fabric from the underside.

[0022] After the needle and bobbin threads are intertwined, the take-up lever pulls in the extra needle thread and thus also regulates the bobbin thread. It is crucial that the slide pin holds the needle thread between 50° and 320° of the stitch formation cycle. This is the time during which the required needle thread is released and then withdrawn. The rectangular shape of the stitch is achieved by regulating the needle thread, the position of the hole in the needle plate, and the loftiness of the fabric. Loftiness is a material property based on the material thickness and the internal force of the material. Loftiness counteracts external forces that attempt to compress the material. All of this together leads to a rectangular stitch formation. This is why a non-compressed state of the fabric, the material structure, is possible and also necessary, in contrast to conventional sewing.

[0023] According to an advantageous embodiment, the push pin is moved by a push pin drive, which generates an intermittent longitudinal movement. According to a particularly advantageous embodiment, the push pin drive comprises a cam disk and a cam roller engaging therein, which is connected to the push pin and causes the intermittent longitudinal movement when the cam disk moves about its axis. The rotating movement of the cam disk, and thus of the push pin drive, is preferably coupled to the rotation of the main axis of the machine sewing unit, so that a phase position of the conventional sewing process always corresponds to a corresponding, firmly linked phase position of the cam disk and thus to a position of the push pin.

[0024] Other variants provide a contour synchronized with or linked to the needle stroke, whose vertical linear movement is also sensed by a cam roller and transmitted as a horizontal linear movement to the push pin. In addition to the drive forms mechanically coupled to the machine sewing unit, non-coupled or electronically coupled versions are also available. For this purpose, the push pin drive, in particular, is electrically implemented and electronically controlled.

[0025] There are other options for moving the push pin into the presser foot. The push pin can also be moved directly from the main shaft using a different drive type. For example, in stitch class 600, a cover stitch can be made visible, with the covering thread placed above the presser foot.

[0026] Advantageously, the needle thread is held by the push pin between 50° and 320° of the stitch formation cycle, the complete cycle of which is specified as 360°. The push pin is used to: During this time, the needle thread is advanced for the subsequent interlacing of the needle thread and bobbin thread and is retracted by a thread take-up lever.

[0027] The object is also achieved by a method for sewing a material structure comprising a spacer textile by means of a machine sewing unit comprising a presser foot and a lower stitch plate with a stitch hole, wherein a foot plate of the presser foot is arranged with its underside at a distance from the stitch plate which corresponds to the height of the sewn material structure.

[0028] According to the invention, a horizontally arranged push pin is moved axially perpendicular to the seam direction, preferably in a recess in the base plate. This push pin is guided over the material buildup in the area of ​​the seam being formed on the side of the needle facing away from the finished seam. Starting with the needle at top dead center and the push pin extended, the method comprises the following steps: a. the push pin is inserted over the seam area; b. the needle descends through the foot plate and the material structure to the bottom dead center, at the same time the needle thread is advanced to intertwine the needle thread and the bobbin thread; c. the interlacing of needle thread and bobbin thread takes place under the needle plate; d. the needle is raised to the top dead center, at the same time the needle thread presented for the looping is retracted and the stitch is tightened; e. the push pin is pulled out under the needle thread of the stitch just formed; f. the material build-up is moved forward by the next stitch length.

[0029] Preferably, process step a) takes place at 50° and process step e) at 320° of the entire stitch formation cycle, which corresponds to 360°. Between 50° and 320° of the stitch formation cycle, the needle thread is held on the surface of the material structure by the push pin and prevented from sinking into the material when the thread take-up lever pulls on the needle thread.

[0030] According to a preferred embodiment, a push pin drive generates an intermittent longitudinal movement of the push pin, which slides in a horizontal recess in the foot plate aligned transversely to the seam, in order to exit into a needle passage of the foot plate above the area of ​​the resulting seam and to become effective there.

[0031] The invention makes it possible to hold the needle thread by means of a mechanism for generating the stitch height by maintaining a distance between the underside of the presser foot and the stitch plate which is predetermined by the height of the material structure.

[0032] To achieve this, the needle thread holding mechanism, specifically the push pin, is retracted once the needle thread feed for a stitch formation has been completed. This allows for curved sewing, top stitches, and easier material handling.

[0033] The inventive stitching technology eliminates the problems of compressed, cold spots in insulation materials through a machine-based technological solution. This stitching method for 3D nonwoven fabric production, for example, spaced fabric layers apart, preventing material compression during stitching.

[0034] The new innovative spacer stitch technology has great potential for a wide range of functional clothing for extreme weather conditions such as jackets, sleeping bags, tents, blankets and other accessories by solving the problem of cold spots.

[0035] The invention also offers great potential in industrial insulation applications. In industries such as power generation, refineries, textile and chemical industries, etc., where large thermal blankets are wrapped around pipes, containers, and equipment used for the transport and storage of liquids and gases, spacer seams can be used.

[0036] With the help of the invention, spacer fabrics can be efficiently sewn for the desired end purpose, even without local compression. The automotive industry and medical textiles can benefit from improved production of spacer fabrics using sewn-through spacer seams. During the production of spacer seams, local compression in composite parts can be reduced, which is caused by sewing in the composites industry, where thicker materials made of high-performance materials are sewn together to prevent delamination between their layers.

[0037] In summary, the following advantages can be achieved: • Thermal bridges in insulation systems are avoided, • Better thermal insulation, • Use of the sewing thread as a sensor in spacer fabrics for smart textile applications, • Sewing in composite manufacturing can avoid compression and achieve better strength in the Z-direction.

[0038] The invention is explained in more detail below based on the description of exemplary embodiments and their illustration in the accompanying drawings. They show: Fig. 1: schematically shows a top view of a drive device of an embodiment of a sewing device according to the invention; Fig. 2: schematically a perspective view of an embodiment of a presser foot of a sewing device according to the invention; Fig. 3: a cross-sectional view of a prior art seam; Fig. 4: schematically shows a cross-sectional view of a seam produced by the method according to the invention; Fig. 5: schematically a perspective view of an embodiment of a drive device of a sewing device according to the invention; Fig. 6: a diagrammatic view of the sequence of a stitch in a sewing device according to the invention.

[0039] Fig. 1 schematically shows a top view of an embodiment of a drive device 20 of a sewing device according to the invention. The horizontal recess 8 (invisibly shown by a dashed line) in the foot plate 2 extends transversely to the orientation of the vertically movable needle (not shown). The sliding pin 22 is inserted into this recess. The needle plate 6 and the material structure 30 form practically the entire base beneath the foot plate 2. Their specific dimensions are not specifically indicated in the illustration. An arrow indicates the direction in which the material structure 30 moves during the sewing process.

[0040] The sliding pin 22 is intermittently, alternately pushed into the recess 8 and pulled out so far that it no longer fits in the needle passage 4 (see Fig. 2) appears. This intermittent movement is caused by a push pin drive 20, which comprises a cam disc 24 with a cam track 26, in which a cam roller 28 runs. As a result of the formation of the cam track 26, which the cam roller 28 follows during the rotation of the cam disc 24, a longitudinal movement of a push assembly 29 and ultimately of the push pin 22 connected to the push assembly 29 is caused. The cam disc 24 is connected to the drive of the entire sewing mechanism, in particular the main shaft, so that at the predetermined phases in the sequence of a stitching process (cf. Fig. 6) the sliding pin 22 can assume the required position within the recess 8.

[0041] Fig. Figure 2 schematically shows a perspective view of an embodiment of a foot plate 2 of a presser foot of a sewing device according to the invention. The material structure 30 rests on the needle plate (not shown). The sliding pin 22 is guided in the direction not shown but shown in Fig. 1 visible recess 8. In the illustrated inserted state, it is shown within the needle passage 4 in order to guide the needle thread 16 (compare Fig. 3) to hold the seam 32 in the manner according to the invention. Only a portion of the pusher assembly 29 of the pusher pin drive 20 is shown.

[0042] Fig. Figure 3 shows a cross-sectional view of a seam 32' according to the prior art. The needle thread 16 pulls the material structure 30 downward at the original height U at each loop, resulting in its compression, which is associated with the disadvantages mentioned above, which are overcome by the invention. The lower thread 18 shows a mirrored shape of the path taken by the upper thread, the needle thread 16.

[0043] Fig. Figure 4 schematically shows a cross-sectional view of a seam 32 produced by the method according to the invention, which overcomes the disadvantages of the prior art. Not only the needle thread 16, but also the bobbin thread 18 has a rectangular course across each stitch 34. As a result, the surface of the material structure 30 remains unaffected; in particular, there is no undesirable compression, so that the material properties, in particular the height U, remain continuous across the surface and, above all, also in the seam area.

[0044] Fig. Figure 5 schematically shows a perspective view of an embodiment of a drive device 20 of a sewing device according to the invention. The push pin 22 is moved in the manner already described for the Fig. 1 and Fig. 2 was explained.

[0045] Fig.Figure 6 shows a diagrammatic view of the sequence of a stitch in a sewing device 1 according to the invention. The entire 360° stitch cycle is plotted on the x-axis, and above it, on the y-axis, the respective needle stroke, specifically of the needle tip and the needle eye, during the creation of a stitch. The two positions where the push pin 22 is pushed in (IN) and pulled out (OUT) are marked. This occurs at 50° and 320° of the stitch cycle, respectively. List of reference symbols 2 base plate 4 Needle passage 8 Recess 16 needle thread 18 bobbin thread 20 sliding pin drive 22 sliding pin 24 cam disc 26 Curved track 28 Cam roller 29 Thrust arrangement 30 Material structure 32 seam 32' conventional seam 34 stitches, stitch length U Material height

Claims

[1] Sewing device, comprising a machine sewing mechanism, a sewing foot and a stitch plate with a stitch hole, wherein a foot plate (2) of the sewing foot is arranged with its underside at a distance from the stitch plate which corresponds to the height U of a sewn material structure (30) along a seam (32), characterized by that a horizontally arranged sliding pin (22) which is movable axially perpendicular to the seam direction is included, which is guided on the side of the needle facing away from the finished seam (32) over the material structure (30) in the region of the resulting seam (32) before the needle penetrates into the material structure (30), and is withdrawn from the region of the seam (32) before the material structure (30) is moved further by a next stitch length (34). [2] Sewing device according to claim 1, wherein the sliding pin (22) slides in a horizontal recess (8) in the foot plate (2) aligned transversely to the seam (32) in order to exit into a needle passage (4) of the foot plate (2) above the area of ​​the resulting seam (32). [3] Sewing device according to claim 1 or 2, wherein the push pin (22) is moved by a push pin drive (20) which produces an intermittent longitudinal movement. [4] Sewing device according to claim 3, wherein the push pin drive (20) comprises a cam disc (24) which is coupled to and driven by a main shaft of the machine sewing unit, the cam disc (24) being connected to the push pin (22) via a cam roller (28) engaging therein and causing the intermittent longitudinal movement. [5] Sewing device according to claim 3, wherein the push pin drive (20) is electrically designed and electronically controlled. [6] Sewing device according to one of claims 3 to 5, wherein the needle thread (16) is held between 50° and 320° of the stitch formation cycle by the push pin (22) inserted into the foot plate (2), while the needle thread (16) is presented for the subsequent interlacing of needle thread (16) and bobbin thread (18) and is retracted by a thread take-up lever. [7] Method for sewing a material structure (30) comprising a spacer textile by means of a machine sewing unit comprising a sewing foot and a stitch plate with a stitch hole, wherein a foot plate (2) of the sewing foot is arranged with its underside at a distance from the stitch plate which corresponds to the height of the material structure (30), characterized bythat a horizontally arranged sliding pin (22) is moved axially perpendicular to the seam direction, which is guided on the side of the needle facing away from the finished seam (32) over the material structure (30) in the area of ​​the resulting seam (32), starting from the needle in a top dead center and the extended sliding pin (22), the method comprises the steps: a. the sliding pin (22) is inserted over the seam area; b. the needle lowers into a needle passage (4) and through the foot plate (2) and the material structure (30) to a bottom dead center, at the same time the needle thread (16) is presented for an interlacing of needle thread (16) and bobbin thread (18); c. the interlacing of needle thread (16) and bobbin thread (18) takes place; d. the needle is raised to the top dead centre, at the same time the needle thread (16) provided for the looping is retracted and the stitch (34) is tightened; e. the sliding pin (22) is pulled out from under the stitch (34); f. the material build-up (30) is moved further by the next stitch length (34). [8] Method according to claim 7, wherein method step a) takes place at 50° and method step e) takes place at 320° of the stitch formation cycle, so that the needle thread (16) is held on the surface of the material structure (30) between 50° and 320° by the push pin (22). [9] Method according to claim 7 or 8, wherein a push pin drive (20) generates an intermittent longitudinal movement of the push pin (22), which slides in a horizontal recess (8) in the foot plate (2) aligned transversely to the seam (32) in order to emerge in a needle passage (4) of the foot plate (2) above the area of ​​the resulting seam (32) and to become effective there.

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