JP7724184B2 - Manufacturing method for stitched skin material - Google Patents

Description

The present invention relates to a method for manufacturing a decorative stitched upholstery material, which forms decorative stitches on the upholstery material.

Patent Document 1 discloses a method for forming decorative stitches using a sewing machine on a covering material that has been molded into a three-dimensional shape (see, for example, Patent Document 1).

JP 2011-46311 A (paragraph [0028], FIG. 3)

However, with the method of manufacturing decorative stitched upholstery material shown in Patent Document 1, the decorative stitches are formed by hand, which makes it easy for the stitches to vary or twist, resulting in defective products. This problem of defective products is particularly pronounced when the upholstery material is shaped into a three-dimensional shape before the decorative stitches are formed.

The present invention was made in consideration of the above circumstances, and aims to provide a method for manufacturing decorative stitched covering materials that can reduce the occurrence of defective products.

The first aspect of the invention, developed in consideration of the above circumstances, is a method for manufacturing a decorative stitched upholstery material in which decorative stitches are formed on a three-dimensionally shaped upholstery material. The method involves having a robot hold the upholstery material, moving the upholstery material in a predetermined pattern to a receiving section in an automatic sewing machine that receives the upholstery material, and forming the decorative stitches using the automatic sewing machine.

A second aspect of the invention is a method for manufacturing a covering material with decorative stitches according to the first aspect, in which the automatic sewing machine is provided with cutting means for cutting the upper thread connected to the covering material after forming the decorative stitches, and thread breakage detection means for detecting that the upper thread has broken; the upper thread is cut by the cutting means, and after the thread breakage detection means detects that the upper thread has been cut, the robot or a robot separate from the robot places the covering material on the receiving part of the automatic sewing machine to form the decorative stitches.

A third aspect of the invention is the method for manufacturing a decorative stitched covering material according to the second aspect, in which the thread breakage detection means includes a rotating wheel around which the upper thread is wound, located between a thread feeder that feeds out the upper thread and the covering material, and rotation detection means that detects the rotation of the rotating wheel.

A fourth aspect of the invention is a method for manufacturing a skin material with decorative stitches according to any one of the first to third aspects, in which the automatic sewing machine is provided with a holding means for holding an upper thread connected to the skin material after forming the decorative stitches, and a cutting means for cutting the upper thread connected to the skin material; after forming the decorative stitches, the skin material is moved by the robot, the upper thread connected to the skin material is held by the holding means, and then the upper thread is cut by the cutting means.

A fifth aspect of the invention is a method for manufacturing a decorative stitched covering material according to the fourth aspect, in which the holding means continues to hold the upper thread until the covering material is placed on the receiving part of the automatic sewing machine, and the holding means releases the upper thread after sewing of the decorative stitches begins.

A sixth aspect of the invention is a method for manufacturing a decorative stitched skin material according to any one of the first to fifth aspects, in which the skin material has a laminated structure having a surface layer made of elastomer and a lining layer made of foamed resin.

[First and sixth aspects of the invention]
In the first aspect of the invention, decorative stitches are formed on the upholstery material using a robot and an automatic sewing machine, which makes it less likely for the stitches to become uneven or twisted compared to when decorative stitches are formed by hand, making it possible to reduce the occurrence of defective products.

In addition, from the perspective of the shape retention of the skin material, it is preferable that the skin material have a laminated structure having a surface layer made of elastomer and a lining layer made of foamed resin (sixth aspect of the invention).

[Second and third aspects of the invention]
In the second aspect of the invention, the upper cover material is placed on the receiving part of the automatic sewing machine and decorative stitches are formed after the breakage of the upper thread is detected by the thread breakage detection means, so that decorative stitches are prevented from being formed on the upper cover material with the upper thread still uncut.In addition, even if an abnormality such as the upper thread breaking occurs during sewing, it is possible to detect the abnormality.

The thread breakage detection means may be configured to directly detect the movement of the upper thread, or to indirectly detect it. An example of the latter is a configuration such as the third aspect of the invention, which includes a rotating wheel around which the upper thread is wound, located between the thread feeder that feeds out the upper thread and the cover material, and rotation detection means that detects the rotation of the rotating wheel. This third aspect of the invention provides improved detection accuracy compared to detecting the movement of the upper thread itself.

[Fourth aspect of the invention]
In the fourth aspect of the invention, the upper thread is held by the holding means and then cut, so that cutting of the upper thread can be stabilized.

[Fifth aspect of the invention]
In the fifth aspect of the invention, the holding means releases the upper thread after the decorative stitch has started to be sewn, thereby preventing the end of the upper thread at the start of sewing from becoming entangled with the upper thread or bobbin thread and forming a lump, which is known as a bird's nest.

1 is a perspective view of an instrument panel using a decorative stitched covering material according to an embodiment of the present invention; (A) A partially cutaway perspective view of an instrument panel, (B) A side cross-sectional view Schematic diagram of the automatic sewing system Block diagram of automatic sewing system Front view of an automatic sewing machine Schematic diagram of a yarn feeding device Plane cross section of a pulley Front view of the kettle stand and work guide (A) A schematic diagram of the thread cutting device, (B) A rear view of the clamp and guide member FIG. 1A is a front view of the yarn breakage sensor when the rotation sensor is in an off state, and FIG. 1B is a side cross-sectional view of the yarn breakage sensor when the rotation sensor is in an off state. FIG. 1A is a front view of the yarn breakage sensor when the rotation sensor is in an ON state, and FIG. 1B is a side cross-sectional view of the yarn breakage sensor. 10 is a front view of a thread breakage sensor according to another embodiment; FIG. 10 is a rear view of a clamp and a guide member according to another embodiment.

As shown in FIG. 1, the decorative stitching covering material 10 of this embodiment is used in the instrument panel 111 of a vehicle 110. As shown in FIG. 2(A), the decorative stitching covering material 10 is fixed to the front surface of the base material 112, forming the design surface of the instrument panel 111. The decorative stitching covering material 10 is formed by forming decorative stitches S on the covering material 11.

As shown in FIG. 2(A), the base material 112 is generally L-shaped in side view, and the cover material 11 also has a generally L-shape in side view that corresponds to the shape of the base material 112. The decorative stitching S is formed at the corners of the L shape on the cover material 11. In detail, the cover material 11 has a top wall 11T extending in the left-right direction and a front wall 11F hanging down from the front end of the top wall 11T, and the decorative stitching S is formed at the front end of the top wall 11T. The top wall 11T is curved so that the upper side is convex. The front wall 11F also has a protruding portion 11S that protrudes forward in a tiered manner as it extends downward.

As shown in Figure 2 (B), the substrate 112 is made of synthetic resin. The skin material 11 has a laminated structure in which a lining layer 13 is layered on the back side of a surface layer 12. The surface layer 12 is made of a thermoplastic elastomer (e.g., TPO). The lining layer 13 is made of a foamed resin (e.g., PP foam or PE foam). This stabilizes the shape retention of the skin material 11.

The decorative stitch-equipped covering material 10 is obtained by forming decorative stitches S on a covering material 11 that has been shaped into a three-dimensional shape corresponding to the base material 112. Figure 3 shows an automatic sewing system 100 for forming decorative stitches S. In the automatic sewing system 100, a robot 90 removes the covering material 11 from a workpiece table 102 and places it on a hook stand 32, which is a receiving portion for receiving the covering material 11 in the automatic sewing machine 20. The robot 90 then moves the covering material 11, and the automatic sewing machine 20 forms decorative stitches S on the covering material 11. As shown in Figure 4, in the automatic sewing system 100, the robot 90 and the automatic sewing machine 20 are controlled by a main control unit 101.

As shown in Figures 3 and 4, the robot 90 is controlled by a robot control unit 90A in accordance with control signals from the main control unit 101. The robot 90 is a general-purpose vertically articulated type, and has an arm 91 consisting of multiple arm components 91A, an arm driver 92 that drives each arm component 91A, a position sensor 93 that detects the position of each arm component 91A, and a robot hand 94 attached to the tip of the arm 91. A suction pad (not shown) for holding the covering material 11 is fixed to the robot hand 94.

As shown in FIG. 4, the automatic sewing machine 20 is controlled by a sewing machine control unit 20A in accordance with control signals from the main control unit 101. As shown in FIG. 5, the automatic sewing machine 20 is configured by attaching to a sewing machine frame 21 a needle drive mechanism 31K that drives the sewing needle 31 up and down, a shuttle mechanism 32K that cooperates with the needle drive mechanism 31K to form stitches, a feed mechanism 33 that transports the covering material 11 along the feed direction X, and the like.

The sewing machine frame 21 comprises a sewing machine bed 22 that forms the lower part of the sewing machine frame 21 and extends in the left-right direction Y, a sewing machine arm 23 that forms the upper part of the sewing machine frame 21 and faces the sewing machine bed 22 from above, and an arm support part 24 that is erected at one end of the sewing machine bed 22 and connects to the sewing machine arm 23, and is formed in a roughly U-shape as a whole when viewed from the front. The left-right direction Y in which the sewing machine bed 22 and sewing machine arm 23 extend is perpendicular to the feed direction X in which the automatic sewing machine 20 feeds the material to be sewn.

The needle drive mechanism 31K includes a rotating spindle (not shown) fixed to an upper shaft extending in the left-right direction Y within the sewing machine arm 23, a crank rod (not shown) whose upper end is rotatably connected to the eccentric portion of the rotating spindle, a needle bar 31B rotatably connected to the lower end of the crank rod, and a sewing needle 31 supported at the lower end of the needle bar 31B. When the upper shaft rotates in response to the driving force of the sewing machine motor 37 (see Figure 4), the rotation is converted into reciprocating motion in the up-down direction Z via the rotating spindle and crank rod, causing the needle bar 31B and sewing needle 31 to reciprocate in the up-down direction Z.

The automatic sewing machine 20 is a post-type sewing machine and is equipped with a shuttle mechanism 32K on a post 25 that extends upward from the sewing machine bed 22. The shuttle mechanism 32K includes a shuttle stand 32 fixed to the upper end of the post 25, a shuttle shaft (not shown) that extends in the vertical direction Z within the post 25, and a horizontal shuttle (not shown) that is supported by the shuttle shaft and rotates around the shuttle shaft within the shuttle stand 32. When the lower shaft extending in the horizontal direction Y within the sewing machine bed 22 rotates together with the upper shaft, the shuttle shaft rotates via a gear (not shown), causing the horizontal shuttle to rotate. This causes the horizontal shuttle and sewing needle 31 to work together to form a stitch.

The automatic sewing machine 20 is an integrated feed sewing machine or an upper feed sewing machine, and as shown in Figures 8 and 9(A), the feed mechanism 33 is equipped with an upper feed member 34 and an upper presser member 35. The upper feed member 34 is driven to trace an elliptical trajectory centered on an upper feed axis (not shown) extending in the left-right direction Y in conjunction with the up-and-down movement of the sewing needle 31, and moves in the feed direction X while moving in the up-and-down direction Z. The upper presser member 35 is driven linearly along the up-and-down direction Z. The upper feed member 34 and the upper presser member 35 are driven so that when one member is positioned at the lower end of their movable range, the other member is positioned at the upper end of their movable range.

8 and 9(A), the upper feed member 34 has a base portion 34B extending in the vertical direction Z and a feed leg portion 34K protruding from the bottom end of the base portion 34B toward the front in the feed direction X, with the feed leg portion 34K having a through-hole 34A (see FIG. 8) through which the sewing needle 31 is inserted. The upper presser member 35 has a base portion 35B extending in the vertical direction Z and presser legs 35K, 35K that branch into two from the bottom end of the base portion 35B and protrude toward the front in the feed direction X. The presser legs 35K, 35K are arranged to sandwich the feed leg portion 34K of the upper feed member 34 in the left-right direction Y.

As shown in Figures 4 and 6, the automatic sewing machine 20 is equipped with a thread feeder 40 for maintaining a constant tension on the upper thread T. The thread feeder 40 includes a spool rotation device 41 and a rotation control device 45. The spool rotation device 41 includes a fixed base 41A, a rotating base 42 mounted on the fixed base 41A, and a rotary drive source 42M that drives the rotating base 42 to rotate. A spool base 43 is fixed to the rotating base 42, to which a thread spool 44 around which the upper thread T is wound can be attached. When the rotating base 42 is rotated by the rotary drive source 42M, the upper thread T is fed from the thread spool 44.

The rotation control device 45 comprises a base plate 46 arranged substantially vertically and a movable pulley 48 that moves up and down in front of the base plate 46. Specifically, a pair of fixed pulleys 47, 47 are rotatably attached to the upper front surface of the base plate 46, and the movable pulley 48 is arranged so that it is sandwiched horizontally between the pair of fixed pulleys 47, 47. The upper thread T supplied from the thread spool 44 is hooked from above around the pair of fixed pulleys 47, 47, and the upper thread T between the pair of fixed pulleys 47, 47 is hooked from below around the movable pulley 48.

As shown in Figure 7, the movable pulley 48 has a large diameter portion 48A, a small diameter portion 48B that overlaps the large diameter portion 48A from the front, and a connecting shaft portion 48C that connects the centers of the large diameter portion 48A and the small diameter portion 48B. The upper thread T is threaded through a thread threading groove 48M formed on the outer peripheral surface of the small diameter portion 48B.

A pair of support shafts 46S, 46S fixed to the base plate 46 are received between the large diameter portion 48A and the small diameter portion 48B. A connecting shaft portion 48C is sandwiched between the pair of support shafts 46S, 46S. These restrict the movement of the movable pulley 48 in the front-to-rear and lateral directions. As shown in Figure 6, the pair of support shafts 46S, 46S are supported by a pair of protruding walls 46T, 46T that protrude forward from the upper and lower ends of the base plate 46. The base plate 46 also has a vertically extending elongated hole 46A formed in it to avoid interference with the movable pulley 48.

As shown in FIG. 6, the rotation control device 45 includes, in order from top to bottom, a rotation switch 49A, a stop switch 49B, and an abnormality detection switch 49C. These switches 49A-49C detect the vertical position of the movable pulley 48. When the movable pulley 48 is located between the rotation switch 49A and the stop switch 49B, the tension of the upper thread T is appropriate. When the rotation switch 49A, which is located at the top of the three switches 49A-49C, detects the movable pulley 48, the rotation control device 45 rotates the rotation drive source 42M of the spool stand rotation device 41. This causes the upper thread T to sag, and the movable pulley 48 to move downward. When the stop switch 49B, which is located in the middle of the three switches 49A-49C, detects the movable pulley 48, the rotation control device 45 stops the rotation drive source 42M of the spool stand rotation device 41. This causes the upper thread T to become taut, and the movable pulley 48 to move upward. In this way, the rotation control device 45 controls the spool stand rotation device 41 so that the tension of the upper thread T is appropriate by positioning the movable pulley 48 between the rotation switch 49A and the stop switch 49B.

If the abnormality detection switch 49C, which is located at the bottom of the three switches 49A-49C, detects the movable pulley 48, the rotation control device 45 determines that abnormal rotation of the rotation drive source 42M has occurred. In this case, the rotation control device 45 brings the spool stand rotation device 41 to an emergency stop and sends an error occurrence signal to the sewing machine control unit 20A.

The movable pulley 48 is detected by each switch 49A-49C as follows. Specifically, as shown in FIG. 7, the rotary switch 49A is composed of an optical sensor and includes a light-emitting element 49H and a light-receiving element 49J facing each other in the front-to-rear direction. A space is provided between the light-emitting element 49H and the light-receiving element 49J to allow the large-diameter portion 48A of the movable pulley 48 to pass through. When the movable pulley 48 approaches the rotary switch 49A and the light emitted from the light-emitting element 49H is blocked by the large-diameter portion 48A and is no longer detected by the light-receiving element 49J, the rotary switch 49A turns on and the spool stand 43 begins to rotate. Then, when the movable pulley 48 moves away from the rotary switch 49A and the light from the light-emitting element 49H is detected by the light-receiving element 49J, the rotary switch 49A turns off, but the spool stand 43 continues to rotate.

Like the rotation switch 49A, the stop switch 49B is also composed of an optical sensor and includes a light-emitting element and a light-receiving element (both not shown) facing each other in the front-to-back direction. A space is provided between the light-emitting element and the light-receiving element of the stop switch 49B to allow the large-diameter portion 48A of the movable pulley 48 to pass through. When the movable pulley 48 approaches the stop switch 49B and the light emitted from the light-emitting element of the stop switch 49B is blocked by the large-diameter portion 48A and is no longer detected by the light-receiving element, the stop switch 49B turns on, stopping the rotation of the spool base 43. When the movable pulley 48 moves away from the stop switch 49B and the light from the light-emitting element is detected by the light-receiving element, the stop switch 49B turns off, but the rotation of the spool base 43 remains stopped. In this way, in this embodiment, the turning-on of the rotation switch 49A and the stop switch 49B keeps the position of the movable pulley 48 in the rotation control device 45 within a certain range, preventing large fluctuations in the tension of the upper thread T.

The abnormality detection switch 49C has a similar configuration to the rotation switch 49A and the stop switch 49B, so a description of the configuration of the abnormality detection switch 49C will be omitted. As with the rotation switch 49A and the stop switch 49B, when the abnormality detection switch 49C is turned on, the rotation control device 45 detects that the movable pulley 48 is near the abnormality detection switch 49C and stops the automatic sewing system 100.

As shown in FIG. 8, the automatic sewing machine 20 is equipped with a work guide 61 that positions the upholstery material 11 relative to the hook base 32 that receives the upholstery material 11. When the upholstery material 11 is placed on the hook base 32 of the automatic sewing machine 20, the work guide 61 is positioned away from the hook base 32 to avoid interference with the upholstery material 11, and when sewing begins, the work guide 61 is driven by a work guide drive unit 62 (see FIG. 4) to be positioned near the hook base 32. More specifically, the work guide 61 is positioned opposite the front wall 11F of the upholstery material 11 and abuts against the L-shaped corner of the upholstery material 11. The portion of the upholstery material 11 to be sewn is positioned below the sewing needle 31.

As shown in FIG. 4, the automatic sewing machine 20 is equipped with a thread cutting device 50 that cuts the upper thread T connected to the upholstery material 11 after forming the decorative stitch S on the upholstery material 11. As shown in FIG. 9(A), the thread cutting device 50 is equipped with a cutter 51 for cutting the upper thread T and a clamp 52 for holding the upper thread T, located behind the sewing needle 31. The cutter 51 is configured, for example, as a heat cutter. As shown in FIG. 9(B), the clamp 52 has a pair of movable parts 52A, 52A that move toward and away from each other in the left-right direction Y, and clamps the upper thread T between the pair of movable parts 52A, 52A. The pair of movable parts 52A, 52A are driven by a clamp drive unit 52K (see FIG. 4).

As shown in Figure 9(A), the thread cutting device 50 is provided with a guide member 53 between the clamp 52 and the sewing needle 31 for guiding the upper thread T to the clamp 52. As shown in Figure 9(B), the guide member 53 has a notch 54 formed upward from the lower end of the guide member 53. The notch 54 consists of a narrowed portion 54A that narrows upward, and a linear portion 54B that extends upward from the narrowed portion 54A. On both sides of the portion of the guide member 53 facing the narrowed portion 54A, arc-shaped guide portions 55 are formed, which curve upward as they approach each other in the left-right direction Y. The linear portion 54B is positioned so as to be sandwiched between a pair of movable portions 52A, 52A of the clamp 52 in the left-right direction Y. Then, when the robot 90 moves the cover material 11 upward and the upper thread T, which has passed through the eye of the sewing needle 31 and is connected to the cover material 11, hits the lower end of the guide member 53, the upper thread T is guided to the linear portion 54B by the arc-shaped guide portion 55. As a result, the upper thread T is guided between the pair of movable portions 52A, 52A of the clamp 52.

However, with the automatic sewing machine 20, if the upper cover material 11 is placed on the hook base 32 without the upper thread T being cut by the thread cutting device 50, a problem may occur in which the upper thread T continuing from the upper cover material 11 is sewn into the upper cover material 11. To solve this problem, the automatic sewing machine 20 is equipped with a thread breakage sensor 70 to confirm that the upper thread T has been cut by the thread cutting device 50 (see Figure 4).

As shown in Figures 5 and 10(A), the thread breakage sensor 70 includes a rotary wheel 71 around which the upper thread T is wound between the thread feeder 50 and the sewing needle 31 and which rotates as the upper thread T moves, and a rotation sensor 75 that detects the rotation of the rotary wheel 71. In detail, the thread breakage sensor 70 is disposed between a pair of side walls 76, 76, each of which has a thread insertion hole 76A formed therethrough. The upper thread T that passes through the thread insertion hole 76A in one side wall 76 is wound around the rotary wheel 71 and passes through the thread insertion hole 76A in the other side wall 76.

As shown in Figure 10 (B), the rotating wheel 71 has a flange 72 and a protruding piece 73 that protrude radially outward and are offset in the axial direction. The upper thread T is wound, for example, once around the portion of the rotating wheel 71 that is sandwiched between the flange 72 and the protruding piece 73 in the axial direction. The protruding piece 73 is fan-shaped and is located at a portion of the circumference of the rotating wheel 71 (see Figure 10 (A)). In this embodiment, the protruding piece 73 is formed in a semicircular shape.

As shown in FIG. 10(B), the rotation sensor 75 includes a light-emitting element 75H and a light-receiving element 75J that face each other in the axial direction of the rotating wheel 71. A space is formed between the light-emitting element 75H and the light-receiving element 75J, allowing the protruding piece 73 of the rotating wheel 71 to pass through. As described above, the protruding piece 73 is located at a portion of the circumference of the rotating wheel 71. Therefore, as the rotating wheel 71 rotates, the rotation sensor 75 changes between a state in which light from the light-emitting element 75H is received by the light-receiving element 75J and the rotation sensor 75 is turned on (the state shown in FIGS. 11(A) and 11(B)), and a state in which light emitted from the light-emitting element 75H toward the light-receiving element 75J is blocked by the protruding piece 73 and the rotation sensor 75 is turned off (the state shown in FIGS. 10(A) and 10(B)).

If the upper thread T has been cut by the thread cutting device 50, the upper thread T between the thread feeding device 50 and the sewing needle 31 will not move even if the robot 90 moves the upholstery material 11 on which the decorative stitches S have been formed. At this time, the rotary wheel 71 does not rotate, and the on/off state of the rotation sensor 75 does not change. On the other hand, if the upper thread T has not been cut by the thread cutting device 50, the upper thread T between the thread feeding device 50 and the sewing needle 31 will move when the robot 90 moves the upholstery material 11 on which the decorative stitches S have been formed. At this time, the rotary wheel 71 rotates, and the on/off state of the rotation sensor 75 changes periodically. In this way, in this embodiment, it is possible to determine whether the upper thread T has been cut by checking whether the on/off state of the rotation sensor 75 changes periodically. The thread breakage sensor 70 can also detect breakage of the upper thread T if the upper thread T accidentally breaks during sewing.

This concludes the explanation of the configuration of the automatic sewing system 100. In this embodiment, the cutter 51 corresponds to the "cutting means" of the present invention, and the clamp 52 corresponds to the "holding means" of the present invention. Furthermore, the thread breakage sensor 70 corresponds to the "thread breakage detection means" of the present invention, and the rotation sensor 75 corresponds to the "rotation detection means" of the present invention.

Next, we will explain the method for manufacturing the decorative stitched covering material 10 using the automatic sewing system 100. To manufacture the decorative stitched covering material 10, first, the three-dimensionally shaped covering material 11 is set in a predetermined position on the work table 102 (see Figure 3). Once the covering material 11 has been set on the work table 102, the robot 90 holds the covering material 11 and places it against the hook base 32, which is the receiving part that receives the covering material 11 in the automatic sewing machine 20, and positions the portion of the covering material 11 to be sewn below the sewing needle 31.

Once the covering material 11 is placed on the hook base 32 of the automatic sewing machine 20, the automatic sewing machine 20 begins sewing, and the robot 90 moves the covering material 11 in a predetermined pattern to form decorative stitches S on the covering material 11. Specifically, the robot 90 moves the covering material 11 in the feed direction X of the automatic sewing machine 20, from a state in which the L-shaped corner portion of the covering material 11 is placed on the hook base 32. At this time, the L-shaped corner portion of the covering material 11 abuts against the work guide 61 of the automatic sewing machine 20, making it easier to keep the sewn portion of the covering material 11 positioned below the sewing needle 31 (see Figure 8).

Once the decorative stitches S are formed on the cover material 11, the automatic sewing machine 20 finishes sewing, and the robot 90 removes the cover material 11 from above the hook base 32. At this time, the automatic sewing machine 20 cuts the bobbin thread using a bobbin thread cutting device (not shown). Next, the robot 90 moves the cover material 11 behind the sewing needle 31, and the automatic sewing machine 20 uses the clamp 52 to hold the upper thread T, which has passed through the eye of the sewing needle 31 and is connected to the cover material 11. Then, with the upper thread T held by the clamp 52, the automatic sewing machine 20 uses the cutter 51 to cut the upper thread T between the cover material 11 and the clamp 52 near the clamp 52. In this way, in this embodiment, the upper thread T is held by the clamp 52 before being cut, ensuring stable cutting of the upper thread T.

Once the upper thread T has been cut, the robot 90 carries the covering material 11 to a designated work collection location and releases it. Then, it picks up the covering material 11 from the work storage area 102 and begins forming decorative stitches S with the automatic sewing machine 20. If the upper thread T is not cut, the upper thread T moves along with the covering material 11 when the robot 90 carries the covering material 11 to the work collection location. The thread breakage sensor 70 then detects that the upper thread T is not cut and signals an abnormality. As described below, the upper thread T is held by the clamp 52 when the robot 90 carries the covering material 11 to the work collection location. However, the holding force of the clamp 52 is small enough not to interfere with the robot 90's movement of the covering material 11.

The upper cover material 11 is placed on the bobbin stand 32 of the automatic sewing machine 20, and the automatic sewing machine 20 begins sewing. The automatic sewing machine 20 continues to hold the upper thread T with the clamp 52 until the upper cover material 11 is placed on the bobbin stand 32 of the automatic sewing machine 20. The automatic sewing machine 20 releases the upper thread T from the clamp 52 after one or two stitches have been made with the upper thread T on the upper cover material 11. In this way, in this embodiment, the upper thread T is released from the clamp 52 after sewing on the upper cover material 11 begins, preventing the end of the upper thread T at the start of sewing from becoming entangled with the upper thread T or the bobbin thread and forming a clump; in other words, preventing the formation of bird's nests.

In the automatic sewing system 100, the above-described operations are repeated to sequentially form decorative stitches S on multiple upholstery materials 11. This results in the sequential production of multiple upholstery materials 10 with decorative stitches.

In the manufacturing method for the decorative stitched upholstery material 10 of this embodiment, the decorative stitches S are formed on the upholstery material 11 using a robot 90 and an automatic sewing machine 20. This means that the stitches of the decorative stitches S are less likely to be uneven or twisted compared to when the decorative stitches S are formed by hand, making it possible to reduce the occurrence of defective products.

In addition, in this embodiment, the upper cover material 11 is placed on the hook base 32 of the automatic sewing machine 20 and the formation of the decorative stitches S begins after the thread breakage sensor 70 detects the breakage of the upper thread T. This prevents the decorative stitches S from being formed on the upper cover material 11 while the upper thread T is still uncut. It also makes it possible to detect an abnormality in which the upper thread T breaks during sewing. Furthermore, because the breakage of the upper thread T is detected by detecting the rotation of the rotary wheel 71 around which the upper thread T is wound, detection accuracy is improved compared to detecting the movement of the upper thread T itself.

Other Embodiments
The present invention is not limited to the above-described embodiments, and for example, the embodiments described below are also included in the technical scope of the present invention. Furthermore, various modifications other than those described below can be made without departing from the spirit of the present invention.

(1) In the above embodiment, the decorative stitched upholstery material 10 was used on the instrument panel 111, but it may also be used on vehicle interior materials such as door trim, pillar garnish, and console box.

(2) In the above embodiment, the decorative stitch S was a single type, but it may also be a double stitch or have various other shapes.

(3) In the above embodiment, the automatic sewing machine 20 was a post-type sewing machine, but depending on the shape of the cover material 11, it may also be a flatbed sewing machine.

(4) In the above embodiment, the rotating wheel 71 of the yarn breakage sensor 70 may be configured to have multiple protruding pieces 73 (see Figures 12(A) and 12(B)). In this case, the multiple protruding pieces 73 are preferably arranged at equal intervals around the circumference of the rotating wheel 71. As shown in Figure 12(A), the protruding pieces 73 are preferably fan-shaped, but may also be rectangular (see Figure 12(B)) or triangular.

(5) In the above embodiment, the cutter 51 is not limited to a heat cutter, but may be a scissors-type cutter that clamps and cuts the upper thread T.

(6) In the above embodiment, the guide member 53 may be provided integrally with the clamp 52 or separately from the clamp 52. The guide member 53 may have a guide portion (the notch 54 in the above embodiment) for guiding the upper thread T to the clamp 52, and may have a configuration including the notch 54 shown in FIG. 13(A) or FIG. 13(B), for example. In the example of FIG. 13(A), the narrowed portion 54A of the notch 54 is formed in a trapezoidal shape. In the example of FIG. 13(B), the entire notch 54 is formed by the narrowed portion 54A that is triangular.

(7) In the above embodiment, one robot 90 was provided, but two robots or three or more robots may be provided. In this case, the robots take turns placing the cover material 11 on the hook base 32 of the automatic sewing machine 20 to form the decorative stitches S.

REFERENCE SIGNS LIST 10: Upholstery material with decorative stitches 11: Upholstery material 20: Automatic sewing machine 40: Thread feeding device 50: Thread cutting device 51: Cutter 52: Clamp 70: Thread breakage sensor 71: Rotating body 75: Rotation sensor 90: Robot 100: Automatic sewing system S: Decorative stitch T: Upper thread

Claims (1)

A method for manufacturing a skin material with decorative stitches, comprising the steps of: having a robot hold a skin material shaped into a three-dimensional shape, and having the robot place the skin material on a receiving part of an automatic sewing machine and move the robot in a predetermined pattern; and forming decorative stitches with the automatic sewing machine;
The automatic sewing machine includes:
a cutting means for cutting the needle thread connected to the cover material after forming the decorative stitch;
a thread breakage detection means for detecting that the upper thread has broken,
The method for manufacturing a covering material with decorative stitches includes cutting the upper thread with the cutting means, detecting that the upper thread has been cut with the thread breakage detecting means, and then applying the covering material to the receiving part of the automatic sewing machine by the robot or a robot different from the robot, thereby forming the decorative stitches.