Manufacturing method for stitched skin material

Abstract

The present invention aims to provide a method for manufacturing a skin material with decorative stitching that can reduce the occurrence of defective products. [Solution] The method of manufacturing a skin material 10 with decorative stitches according to the present invention involves forming decorative stitches S on a skin material 11 shaped into a three-dimensional shape. Specifically, first, a robot 90 holds the skin material 11 shaped into a three-dimensional shape. Then, the robot 90 moves the skin material 11 to a hook cradle 32 of an automatic sewing machine 20 in a predetermined pattern, and the automatic sewing machine 20 forms the decorative stitches S.

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a skin material with decorative stitches, in which decorative stitches are formed on the skin material. [Background technology]

[0002] Patent Document 1 discloses a method of forming decorative stitches with a sewing machine on a skin material formed into a three-dimensional shape (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2011-46311 A (paragraph

[0028] , Figure 3) Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the method of manufacturing a 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 is particularly pronounced when the upholstery material is shaped into a three-dimensional shape before the decorative stitches are formed.

[0005] The present invention has been made in view of the above circumstances, and has as its object to provide a method for manufacturing a covering material with decorative stitching that can reduce the occurrence of defective products. [Means for solving the problem]

[0006] A first aspect of the invention, made in consideration of the above circumstances, is a method for manufacturing a skin material with decorative stitches, in which decorative stitches are formed on a skin material shaped into a three-dimensional shape, in which the skin material is held by a robot, the robot moves the skin material in a predetermined pattern to a receiving part in an automatic sewing machine that receives the skin material, and the automatic sewing machine forms the decorative stitches.

[0007] A second aspect of the invention is a method for manufacturing a skin material with decorative stitches according to the first aspect, wherein the automatic sewing machine is provided with cutting means for cutting an upper thread connected to the skin material after forming the decorative stitches, and thread breakage detection means for detecting that the upper thread has been broken, and after the upper thread is cut by the cutting means and the thread breakage detection means detects that the upper thread has been cut, the robot or a robot separate from the robot applies the skin material to the receiving part of the automatic sewing machine to form the decorative stitches.

[0008] A third aspect of the invention is the method for manufacturing a skin material with decorative stitching according to the second aspect, wherein 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 skin material, and rotation detection means that detects rotation of the rotating wheel.

[0009] 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, wherein the automatic sewing machine is provided with holding means for holding an upper thread connected to the skin material after forming the decorative stitch, and cutting means for cutting the upper thread connected to the skin material, and after forming the decorative stitch, the skin material is moved by the robot, and 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.

[0010] A fifth aspect of the invention is a method for manufacturing a skin material with decorative stitches according to the fourth aspect, in which the holding means continues to hold the upper thread until the skin 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.

[0011] A sixth aspect of the invention is a method for manufacturing a skin material with decorative stitching according to any one of the first to fifth aspects, wherein the skin material has a laminated structure having a surface layer made of elastomer and a lining layer made of foamed resin. [Effects of the Invention]

[0012] [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, thereby reducing the occurrence of defective products.

[0013] From the viewpoint of the shape retention of the skin material, it is preferable that the skin material has a laminated structure having a surface layer made of elastomer and a lining layer made of foamed resin (sixth aspect of the invention).

[0014] [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 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.

[0015] The yarn 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, as in the third aspect of the invention, that includes a rotating wheel around which the upper thread is wound between a yarn feeder that feeds out the upper thread and the cover material, and rotation detection means that detects the rotation of the rotating wheel. In the third aspect of the invention, detection accuracy is improved compared to when the movement of the upper thread itself is detected.

[0016] [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 is stabilized.

[0017] [Fifth aspect of the invention] In the fifth aspect of the invention, the holding means releases the upper thread after the decorative stitch begins to be sewn, thereby preventing the end of the upper thread at the beginning of sewing from becoming entangled with the upper thread or bobbin thread and forming a lump, a phenomenon known as bird's nest formation. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a perspective view of an instrument panel using a decorative stitched covering material according to an embodiment of the present invention; [Figure 2] (A) Partially cutaway perspective view of the instrument panel, (B) side cross-sectional view [Figure 3] Schematic diagram of the automatic sewing system [Figure 4] Block diagram of automatic sewing system [Figure 5] Front view of an automatic sewing machine [Figure 6] Schematic diagram of a yarn feeding device [Figure 7] Plane cross section of a pulley [Figure 8] Front view of the kettle stand and work guide [Figure 9] (A) Schematic diagram of the thread cutting device, (B) rear view of the clamp and guide member [Figure 10] (A) Front view and (B) side cross-sectional view of the thread breakage sensor when the rotation sensor is in the OFF state [Figure 11] (A) Front view and (B) side cross-sectional view of the thread breakage sensor when the rotation sensor is in the ON state [Figure 12] 10 is a front view of a thread breakage sensor according to another embodiment; [Figure 13] FIG. 10 is a rear view of a clamp and a guide member according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0019] As shown in Fig. 1, the decorative stitching covering material 10 of this embodiment is used in an instrument panel 111 of a vehicle 110. As shown in Fig. 2(A), the decorative stitching covering material 10 is fixed to the surface facing the front side of a base material 112, and forms the design surface of the instrument panel 111. The decorative stitching covering material 10 is formed by forming decorative stitches S on a covering material 11.

[0020] As shown in FIG. 2(A), the base material 112 is generally L-shaped in side view, and the covering material 11 also has a generally L-shape in side view corresponding to the shape of the base material 112. The decorative stitching S is formed at the corners of the L shape of the covering material 11. More specifically, the covering 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.

[0021] As shown in Fig. 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 superimposed 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.

[0022] The covering material 10 with decorative stitches 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. FIG. 3 shows an automatic sewing system 100 for forming the decorative stitches S. In the automatic sewing system 100, a robot 90 takes the covering material 11 from a workpiece table 102 and delivers it to a hook stand 32, which is a receiving portion that receives the covering material 11 in an automatic sewing machine 20. Then, the robot 90 moves the covering material 11, and the automatic sewing machine 20 forms the decorative stitches S on the covering material 11. As shown in FIG. 4, in the automatic sewing system 100, the robot 90 and the automatic sewing machine 20 are controlled by a main control unit 101.

[0023] 3 and 4, the robot 90 is controlled by a robot control unit 90A in accordance with control signals from a main control unit 101. The robot 90 is a general-purpose vertical 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.

[0024] As shown in Fig. 4, the automatic sewing machine 20 is controlled by a sewing machine control unit 20A in accordance with a control signal from the main control unit 101. As shown in Fig. 5, the automatic sewing machine 20 is configured by mounting, on a sewing machine frame 21, a needle drive mechanism 31K that drives the sewing needle 31 up and down, a shuttle mechanism 32K that forms stitches in cooperation with the needle drive mechanism 31K, a feed mechanism 33 that transports the covering material 11 along the feed direction X, and the like.

[0025] The sewing machine frame 21 includes 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 generally U-shape when viewed from the front. The left-right direction Y in which the sewing machine bed 22 and the 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.

[0026] 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 an 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 FIG. 4), the rotation is converted into reciprocating motion in the up-down direction Z via the rotating spindle and the crank rod, and the needle bar 31B and the sewing needle 31 reciprocate in the up-down direction Z.

[0027] The automatic sewing machine 20 is a post-type sewing machine and is provided with a shuttle mechanism 32K on a post 25 that stands upright from the sewing machine bed 22. The shuttle mechanism 32K is provided with 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 a 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), and the horizontal shuttle rotates. As a result, the horizontal shuttle and the sewing needle 31 work together to form a stitch.

[0028] Furthermore, 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 provided 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 shaft (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 located at the lower end of its movable range, the other member is located at the upper end of its movable range.

[0029] 8 and 9(A), the upper feed member 34 has a base portion 34B extending in the up-down direction Z and a feed leg portion 34K protruding from the lower end of the base portion 34B to the front side in the feed direction X, and the feed leg portion 34K is provided with 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 up-down direction Z and presser legs 35K, 35K that branch into two from the lower end of the base portion 35B and protrude to the front side 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.

[0030] 4 and 6, the automatic sewing machine 20 includes a thread feeding device 40 for maintaining a constant tension on the upper thread T. The thread feeding device 40 includes a spool rotation device 41 and a rotation control device 45. The spool rotation device 41 includes a fixed base 41A, a rotary base 42 mounted on the fixed base 41A, and a rotary drive source 42M that drives the rotary base 42 to rotate. A spool base 43 is fixed to the rotary base 42, to which a thread spool 44 around which the upper thread T is wound can be attached. When the rotary base 42 is rotated by the rotary drive source 42M, the upper thread T is fed from the thread spool 44.

[0031] The rotation control device 45 includes a base plate 46 disposed 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 as to be sandwiched laterally between the pair of fixed pulleys 47, 47. The upper thread T supplied from the thread spool 44 is hung on the pair of fixed pulleys 47, 47 from above, and the upper thread T between the pair of fixed pulleys 47, 47 is hung on the movable pulley 48 from below.

[0032] 7, the movable pulley 48 includes a large diameter portion 48A, a small diameter portion 48B overlapping the large diameter portion 48A from the front, and a connecting shaft portion 48C connecting the centers of the large diameter portion 48A and the small diameter portion 48B. An upper thread T is hooked in a thread hooking groove 48M formed on the outer circumferential surface of the small diameter portion 48B.

[0033] 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-rear and lateral directions. As shown in FIG. 6, the pair of support shafts 46S, 46S are supported across a pair of protruding walls 46T, 46T protruding forward from the upper and lower ends of the base plate 46. A vertically extending elongated hole 46A is formed in the base plate 46 to avoid interference with the movable pulley 48.

[0034] 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.

[0035] When abnormality detection switch 49C, which is located at the bottom of the three switches 49A to 49C, detects movable pulley 48, rotation control device 45 determines that abnormal rotation of rotation drive source 42M has occurred. In this case, rotation control device 45 brings spool stand rotation device 41 to an emergency stop and sends an error occurrence signal to sewing machine control unit 20A.

[0036] The switches 49A to 49C detect the movable pulley 48 as follows. Specifically, as shown in FIG. 7, the rotary switch 49A is configured as an optical sensor and includes a light-emitting element 49H and a light-receiving element 49J that face 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 base 43 begins to rotate. 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 base 43 continues to rotate.

[0037] Like the rotation switch 49A, the stop switch 49B is also an optical sensor and includes a light-emitting element and a light-receiving element (both not shown) facing each other in the front-to-rear 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. As described above, 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.

[0038] The abnormality detection switch 49C has a configuration similar to that of the rotation switch 49A and the stop switch 49B, and therefore a description of the configuration of the abnormality detection switch 49C will be omitted. As in the cases of 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.

[0039] As shown in Figure 8, the automatic sewing machine 20 is provided with a work guide 61 that positions the covering material 11 relative to the shuttle hook 32 that receives the covering material 11. When the covering material 11 is applied to the shuttle hook 32 of the automatic sewing machine 20, the work guide 61 is positioned at a location away from the shuttle hook 32 to avoid interference with the covering material 11, and when sewing begins, the work guide 61 is driven by a work guide drive unit 62 (see Figure 4) to be positioned near the shuttle hook 32. More specifically, the work guide 61 is positioned opposite the front wall 11F of the covering material 11 and abuts against the L-shaped corner portion of the covering material 11. The portion of the covering material 11 to be sewn is positioned below the sewing needle 31.

[0040] As shown in FIG. 4, the automatic sewing machine 20 includes a thread cutting device 50 that cuts the upper thread T connected to the upholstery material 11 after forming a decorative stitch S on the upholstery material 11. As shown in FIG. 9(A), the thread cutting device 50 includes 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, by 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 the upper thread T is clamped between the pair of movable parts 52A, 52A. The pair of movable parts 52A, 52A are driven by a clamp drive part 52K (see FIG. 4).

[0041] As shown in FIG. 9(A), the thread cutting device 50 includes 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 FIG. 9(B), the guide member 53 has a notch 54 formed upward from the lower end of the guide member 53. The notch 54 is composed of a narrowed portion 54A that narrows in width as it extends upward, and a linear portion 54B that extends upward from the narrowed portion 54A. Arc-shaped guide portions 55 are formed on both sides of the portion of the guide member 53 facing the narrowed portion 54A, and 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 the 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.

[0042] Incidentally, in the automatic sewing machine 20, if the upper cover material 11 is applied to the hook base 32 in a state in which the upper thread T has not been cut by the thread cutting device 50, a problem may arise in that the upper thread T continuing to the upper cover material 11 is sewn into the upper cover material 11. To solve this problem, the automatic sewing machine 20 is provided with a thread breakage sensor 70 for confirming that the upper thread T has been cut by the thread cutting device 50 (see FIG. 4).

[0043] 5 and 10(A), the thread breakage sensor 70 includes a rotary wheel 71 around which the upper thread T between the thread feeding device 50 and the sewing needle 31 is wound 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, and a thread insertion hole 76A is formed through each side wall 76. The upper thread T that passes through the thread insertion hole 76A of one side wall 76 is wound around the rotary wheel 71 and passes through the thread insertion hole 76A of the other side wall 76.

[0044] As shown in Fig. 10(B), the rotary 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 a portion of the rotary wheel 71 that is sandwiched between the flange 72 and the protruding piece 73 in the axial direction. The protruding piece 73 has a fan shape and is arranged at a portion of the rotary wheel 71 in the circumferential direction (see Fig. 10(A)). In this embodiment, the protruding piece 73 is formed in a semicircular shape.

[0045] As shown in Figure 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 disposed at a portion of the circumference of the rotating wheel 71. Therefore, when 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 Figures 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 Figures 10(A) and 10(B)).

[0046] Here, 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 covering 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 covering 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. As such, in this embodiment, it is possible to know whether the upper thread T has been cut by whether the on / off state of the rotation sensor 75 changes periodically. Note that the thread breakage sensor 70 can also detect breakage of the upper thread T if the upper thread T accidentally breaks during sewing.

[0047] This completes the description 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 detecting means" of the present invention, and the rotation sensor 75 corresponds to the "rotation detecting means" of the present invention.

[0048] Next, a method for manufacturing the decorative stitched covering material 10 using the automatic sewing system 100 will be described. To manufacture the decorative stitched covering material 10, first, the covering material 11 formed into a three-dimensional shape is set in a predetermined position on the workpiece table 102 (see FIG. 3). Once the setting of the covering material 11 on the workpiece table 102 is complete, the robot 90 holds the covering material 11 and positions the portion of the covering material 11 to be sewn below the sewing needle 31 against the hook base 32, which is a receiving portion that receives the covering material 11 in the automatic sewing machine 20.

[0049] When the covering material 11 is applied to the hook base 32 of the automatic sewing machine 20, the automatic sewing machine 20 starts 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 applied to 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 maintain the state in which the portion of the covering material 11 to be sewn is positioned below the sewing needle 31 (see FIG. 8).

[0050] When 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 that has passed through the eye of the sewing needle 31 and is continuing 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. As described above, in this embodiment, the upper thread T is held by the clamp 52 before being cut, thereby stably cutting the upper thread T.

[0051] When the upper thread T has been cut, the robot 90 carries the covering material 11 to a predetermined work collection location, releases the covering material 11, and then picks up the covering material 11 from the work storage area 102 and starts 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 notifies the robot 90 of the abnormality. As will be 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.

[0052] The covering material 11 is applied to the hook base 32 of the automatic sewing machine 20, and the automatic sewing machine 20 starts sewing. Here, the automatic sewing machine 20 continues to hold the upper thread T with the clamp 52 until the covering material 11 is applied to the hook base 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 covering material 11. In this way, in this embodiment, the upper thread T is released from the clamp 52 after sewing on the covering material 11 has started, so that the end of the upper thread T at the start of sewing is prevented from becoming entangled with the upper thread T or the bobbin thread and forming a lump, i.e., the formation of a bird's nest.

[0053] In the automatic sewing system 100, the above-described operation is repeated to sequentially form decorative stitches S on a plurality of skin materials 11. Thus, a plurality of skin materials 10 with decorative stitches are sequentially produced.

[0054] In the manufacturing method of the decorative stitched upholstery material 10 of this embodiment, the decorative stitches S are formed on the upholstery material 11 by the robot 90 and the automatic sewing machine 20, which makes it less likely that the stitches of the decorative stitches S will vary or twist, compared to when the decorative stitches S are formed by hand, making it possible to reduce the occurrence of defective products.

[0055] Furthermore, in this embodiment, the upper cover material 11 is placed on the shuttle hook 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, so that the decorative stitches S are prevented from being formed on the upper cover material 11 while the upper thread T is still uncut. Furthermore, even if an abnormality occurs in which the upper thread T breaks during sewing, it becomes possible to detect the abnormality. Moreover, 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, so that the detection accuracy is improved compared to when the movement of the upper thread T itself is detected.

[0056] [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.

[0057] (1) In the above embodiment, the decorative stitched covering material 10 is used for the instrument panel 111. However, it may also be used for vehicle interior materials such as door trim, pillar garnish, and console box.

[0058] (2) In the above embodiment, the decorative stitch S is of a single type, but it may be of a double stitch or of various other types.

[0059] (3) In the above embodiment, the automatic sewing machine 20 is a post-type sewing machine, but depending on the shape of the covering material 11, it may be a flat-bed sewing machine.

[0060] (4) In the above embodiment, the rotating wheel 71 of the yarn breakage sensor 70 may be configured to have a plurality of protruding pieces 73 (see FIGS. 12(A) and 12(B)). In this case, the plurality of protruding pieces 73 are preferably arranged at equal intervals in the circumferential direction of the rotating wheel 71. As shown in FIG. 12(A), the protruding pieces 73 are preferably fan-shaped, but may also be rectangular (see FIG. 12(B)) or triangular.

[0061] (5) In the above embodiment, the cutter 51 is not limited to a heat cutter, but may be a scissors type cutter that pinches and cuts the upper thread T.

[0062] (6) In the above embodiment, the guide member 53 may be provided integrally with the clamp 52 or may be provided 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 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 having a triangular shape.

[0063] (7) In the above embodiment, one robot 90 is provided, but two robots or three or more robots may be provided. In this case, the robots take turns to feed the covering material 11 to the hook base 32 of the automatic sewing machine 20 to form the decorative stitches S. [Explanation of symbols]

[0064] 10. Decorative stitched leather 11 Skin material 20 Automatic Sewing Machine 40 Yarn feeding device 50 Thread cutting device 51 Cutter 52 Clamp 70 Thread break sensor 71 Rotating body 75 Rotation Sensor 90 Robot 100 Automatic Sewing System S decorative stitching T Needle thread

Claims

[Claim 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.

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