Method and apparatus for automatic decorative stitches

Abstract

A decorative chain stitch head, comprising an upper head assembly that controls the movement of a needle bar and a walking foot mechanism, a walking foot eccentric configured to enable adjustment of both walking foot forward movement and needle bar forward movement through adjustment of a swing frame whose stitch length eccentric determines the length of stitches created by the decorative chain stitch head, while also being configured to enable adjustment of foot lift, a lower head assembly, and a needle bar cam assembly that drives the rotation of the needle bar during each stitch cycle of the decorative chain stitch head to achieve a desired stitch pattern, the needle bar cam assembly being directly driven by an upper shaft via a pair of gears that reduce the speed of the needle bar cam assembly according to the size ratio of the pair of gears. A decorative chain stitch head is disclosed.

Description

Cross - reference to related applications

[0001]

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 357,644, filed on July 1, 2022, the content of which is incorporated herein by reference.

Technical Field

[0002]

[0002] Exemplary embodiments of the present disclosure relate to methods and apparatuses for sewing decorative stitches onto the surface of three - dimensional parts.

Background Art

[0003]

[0003] Decorative stitches for automotive trim materials and parts are available. Decorative stitches typically refer to patterns that have some lateral movement of the stitch in addition to forward movement.

[0004]

[0004] Under current state - of - the - art, when decorative stitches are desired on automotive trim panels, the stitches are applied via an operator who supports and guides the part as it is fed into a manually - modified machine that is adjusted to produce any number of different decorative patterns. The material to be sewn can be either flat or pre - formed. When pre - formed, the size and shape of the part and the location of the sewing path on the part must be such that a human operator can relatively easily control the placement of the stitches.

[0005]

[0005] Many sewing machine manufacturers offer manual sewing equipment that is used to apply decorative stitches to trim materials. Manual machines constructed for such stitches can be of the flat bed or post bed type. Manual flat bed sewing machines are mainly used to sew flat materials that are used in the cut-sew-wrap process of covering trim components. Manual post bed sewing machines are often utilized to sew parts that have obtained a certain shape from two components, which are stitched seams sewn in previous process steps. The post enables decorative stitches to be applied to the part without the need to flatten the entire part as in the case of a normal flat bed type sewing machine. However, as the size and / or shape of the part increases, manual sewing of such parts becomes more difficult.

[0006]

[0006] Recent customer requests include the desire to place decorative stitches on 3D pre-formed automotive parts. As the size and complexity of the part's shape increase, especially in the case of instrument panels, manual sewing of such parts becomes more difficult and sometimes impossible, increasing the need for automation.

[0007]

[0007] Brief Description This specification discloses a method and apparatus for robotically sewing decorative stitches onto the surface of 3D shaped parts. The decorative stitch sewing head utilizes chain stitch technology to eliminate the need for frequent bobbin thread changes.

[0008]

[0008] Lock stitch technology can also be utilized, taking into account the need to change the lower bobbin and redesign the post assembly to accommodate a hook instead of a looper.

[0009]

[0009] The sewing head is attached as an end effector to a 6-axis robot that serves to position the sewing head as required relative to the part being sewn.

[0010]

[0010] Alternatively, while the robot positions the part relative to the sewing head to perform the stitch process, the sewing head can be kept stationary.

[0011]

[0011] A decorative chain stitch head, comprising an upper head assembly that controls the movement of a needle bar and a walking foot mechanism, and a swing frame adjustment where a stitch length eccentric determines the length of the stitches created by the decorative chain stitch head, configured to enable adjustment of both walking foot advancement and needle bar advancement, while a walking foot eccentric configured to enable adjustment of the foot lift, a lower head assembly, and a needle bar cam assembly that drives the rotation of the needle bar during each stitch cycle of the decorative chain stitch head to achieve a desired stitch pattern, the needle bar cam assembly being directly driven by an upper shaft via a pair of gears that reduce the speed of the needle bar cam assembly according to the size ratio of the pair of gears, is disclosed.

[0012]

[0012] In addition to one or more of the above-described features, or as an alternative to any of the foregoing embodiments, two different cam profiles are machined into the needle bar cam assembly.

[0013]

[0013] In addition to one or more of the above-described features, or as an alternative to any of the foregoing embodiments, a cam follower engages one of two different cam profiles and drives a link mechanism connected to a drive gear.

[0014]

[0014] In addition to one or more of the above-described features, or as an alternative to any of the foregoing embodiments, the lateral movement of the link mechanism is managed by two bearing blocks that engage a guide rail.

[0015]

[0015] Also disclosed is an ornamental chain stitch head, which includes an upper head assembly for controlling the movement of a needle bar and a walking foot mechanism, the upper head assembly having a needle bar with a pair of needles, and a lower head assembly including a pair of loopers each having a scarf facing each other, and a pair of spreaders. The lower head assembly is configured to move the pair of loopers towards and away from the pair of spreaders during the stitch sequence of the ornamental chain stitch head, and the lower head assembly is configured to move the pair of spreaders towards and away from each other during the stitch sequence of the ornamental chain stitch head.

[0016]

[0016] In addition to one or more of the above-described features, or as an alternative to any of the foregoing embodiments, the pair of needles are received within the pair of loopers during the stitch sequence of the ornamental chain stitch head.

[0017]

[0017] In addition to one or more of the above-described features, or as an alternative to any of the foregoing embodiments, the lower head assembly further includes a pair of concentric shafts rotatably fixed to each other such that one of the pair of concentric shafts rotates around the other of the pair of concentric shafts and the other of the pair of concentric shafts rotates within the one of the pair of concentric shafts. The rotation of the pair of concentric shafts relative to each other causes the pair of spreaders to move towards and away from each other during the stitch sequence of the ornamental chain stitch head. One of the pair of concentric shafts is operably fixed to one of the pair of spreaders, and the other of the pair of concentric shafts is fixed to the other of the pair of spreaders.

[0018] In addition to one or more of the above-described features, or as an alternative to any of the foregoing embodiments, the pair of concentric shafts is rotated by a spreader cam that engages a spreader cam follower directly connected to the bearing block, and rotation of the spreader cam causes relative rotation of the pair of concentric shafts with respect to each other.

[0019] In addition to one or more of the above-described features, or as an alternative to any of the foregoing embodiments, the bearing block rides on a guide rail.

[0020] In addition to one or more of the above-described features, or as an alternative to any of the foregoing embodiments, the bearing block further includes pins that serve as hubs for rotatably receiving one end of each of a pair of connecting rods, and the opposite ends of each of the pair of connecting rods are rotatably fixed to one of a pair of crank arms, one of the pair of crank arms is fixed to one of the pair of concentric shafts, and the other of the pair of crank arms is fixed to the other of the pair of concentric shafts.

[0021] In addition to one or more of the above-described features, or as an alternative to any of the foregoing embodiments, linear movement of the bearing block causes rotational movement of the pair of concentric shafts relative to each other.

[0022]

[0022] Also, a method of providing stitches to a component using a decorative chain stitch head, the method comprising: moving a pair of needles up and down using an upper head assembly; engaging the upper thread of each of the pair of needles with a pair of loopers of a lower head assembly during a stitch sequence of the decorative chain stitch head, wherein the pair of loopers each have scarves facing each other; engaging the lower thread of each of the pair of loopers with a pair of spreaders during a stitch sequence of the decorative chain stitch head, wherein the lower head assembly moves the pair of loopers towards and away from the pair of spreaders during a stitch sequence of the decorative chain stitch head, and the lower head assembly moves the pair of spreaders towards and away from each other during a stitch sequence of the decorative chain stitch head.

[0023]

[0023] In addition to one or more of the above features, or as an alternative to any of the foregoing embodiments, the pair of needles are received within the pair of loopers during a stitch sequence of the decorative chain stitch head.

[0024]

[0024] In addition to one or more of the above features, or as an alternative to any of the foregoing embodiments, the lower head assembly further comprises a pair of concentric shafts rotatably fixed to each other such that one of the pair of concentric shafts rotates around the other of the pair of concentric shafts and the other of the pair of concentric shafts rotates within the one of the pair of concentric shafts, and rotation of the pair of concentric shafts relative to each other causes the pair of spreaders to move towards and away from each other during a stitch sequence of the decorative chain stitch head, wherein one of the pair of concentric shafts is operably fixed to one of the pair of spreaders and the other of the pair of concentric shafts is fixed to the other of the pair of spreaders.

[0025] In addition to one or more of the above-described features, or as an alternative to any of the foregoing embodiments, a pair of concentric shafts is rotated by a spreader cam that engages a spreader cam follower directly connected to a bearing block, and rotation of the spreader cam causes relative rotation of the pair of concentric shafts with respect to each other.

[0026] In addition to one or more of the above-described features, or as an alternative to any of the foregoing embodiments, the bearing block rides on a guide rail.

[0027] In addition to one or more of the above-described features, or as an alternative to any of the foregoing embodiments, the bearing block further comprises a pin serving as a hub for rotatably receiving one end of each of a pair of connecting rods, and the opposite ends of each of the pair of connecting rods are rotatably fixed to one of a pair of crank arms, one of the pair of crank arms is fixed to one of the pair of concentric shafts, and the other of the pair of crank arms is fixed to the other of the pair of concentric shafts.

[0028] In addition to one or more of the above-described features, or as an alternative to any of the foregoing embodiments, linear movement of the bearing block causes relative rotational movement of the pair of concentric shafts with respect to each other.

[0029] In addition to one or more of the above-described features, or as an alternative to any of the foregoing embodiments, movement of the pair of loopers and the pair of spreaders is limited to a region defined by a stitch plate having a width of 35 mm or less and a length of 56 mm or less during the stitch sequence of a decorative chain stitch head.

[0030] In addition to one or more of the above features, or as an alternative to any of the foregoing embodiments, a pair of needles is received within a pair of loops during the stitch sequence of a decorative chain stitch head, and the lower head assembly further comprises a pair of concentric shafts, one of the pair of concentric shafts being rotatable about the other of the pair of concentric shafts and the other of the pair of concentric shafts being rotatable within the one of the pair of concentric shafts, the pair of concentric shafts being rotatably fixed to each other such that rotation of the pair of concentric shafts relative to each other causes a pair of spreaders to move towards each other and away from each other during the stitch sequence of the decorative chain stitch head, one of the pair of concentric shafts being operably fixed to one of the pair of spreaders and the other of the pair of concentric shafts being fixed to the other of the pair of spreaders.

[0031] The following description should not be regarded as in any way limiting. Referring to the accompanying drawings, like elements are numbered alike.

Brief Description of the Drawings

[0032]

Figure 1

Figure 2

Figure 3

Figure 3A

Figure 4

Figure 5

Figure 6

Figure 7A

Figure 7B

Figure 7C

Figure 7D

Figure 7E

Figure 7F

Figure 7G

Figure 7H

Figure 8

Figure 9A

Figure 9B

Figure 9C

Figure 9D

Figure 9E

Figure 9F

Figure 9G

Figure 9H

DETAILED DESCRIPTION OF THE INVENTION

[0033]

[0041] A detailed description of one or more embodiments of the disclosed apparatus and method is presented herein by way of example and not limitation with reference to the drawings.

[0034]

[0042] As described above, when decorative stitches are desired on automotive trim panels, manual sewing of such parts becomes more difficult as the size and / or shape of the parts increases. Thus, especially in the case of instrument panels, as the complexity of the part size and shape increases, manual sewing of such parts becomes more difficult and sometimes impossible, increasing the need for automation.

[0035]

[0043] Disclosed herein are methods and apparatus for robotically sewing decorative stitches onto the surface of 3D formed parts. Non-limiting examples of three-dimensional parts include vehicle interiors, vehicle instrument panels, any automotive interior surface, or any other part where access to the opposite side of the part or panel being sewn or the item being sewn for the construction of the part or panel is restricted. The part or panel to be sewn may include several layers or only a single layer. In one embodiment, the part or panel may have an exterior display surface with a substantially smooth outer surface and a lower surface facing away from the outer surface. The exterior display surface may be formed from a plastic material, vinyl, thermoplastic olefin (TPO), leather, etc., having substantially flexibility and aesthetic appeal.

[0036]

[0044] To increase the flexibility of the part or panel, a layer of cushioning support material may be added to the part or panel before or after the part is sewn. The part or panel can also include a substrate panel of dimensionally stable plastic or other suitable material applied before or after the stitch process. Further, in one embodiment, the part or panel may include only a single layer of structural panel.

[0037]

[0045] The decorative stitch sewing head utilizes chain stitch technology to eliminate the need for frequent bobbin changes.

[0038]

[0046] Lock stitch technology can also be utilized, taking into consideration the need to change the lower bobbin and redesign the post assembly for accommodating a hook instead of a looper.

[0039]

[0047] The sewing head is attached as an end effector to a 6-axis robot that serves to position the sewing head as required with respect to the parts to be sewn.

[0040]

[0048] Alternatively, while the robot positions the parts with respect to the sewing head to execute the stitch process, the sewing head can be kept stationary.

[0041]

[0049] Figure 1 is a perspective view of a decorative chain stitch head according to the present disclosure.

[0042]

[0050] Figure 2 is a perspective view of the upper head assembly of the decorative chain stitch head shown in Figure 1.

[0043]

[0051] Figure 3 is an enlarged perspective view of at least a part of the upper head assembly of the decorative chain stitch head shown in Figure 2.

[0044]

[0052] Figure 3A shows a stitch pattern that can be produced with a decorative chain stitch head according to the present disclosure.

[0045]

[0053] Figure 4 is a perspective view of the lower head assembly of the decorative chain stitch head shown in Figure 1.

[0046]

[0054] Figure 5 is an enlarged perspective view of at least a part of the lower head assembly of the decorative chain stitch head shown in Figure 4.

[0047]

[0055] FIG. 6 is an enlarged perspective view of a portion of the lower head assembly of at least the decorative chain stitch head shown in FIG. 4.

[0048]

[0056] FIGS. 7A-7H illustrate a stitch formation cycle according to the present disclosure.

[0049]

[0057] FIG. 8 shows the upper portion of the stitch plate of the lower head assembly of the present disclosure.

[0050]

[0058] FIGS. 9A-9H show top views of a stitch formation cycle according to the present disclosure.

[0051]

[0059] Referring to FIG. 1, a decorative chain stitch sewing head 100 of the present disclosure is shown. According to an embodiment of the present disclosure, the decorative chain stitch sewing head 100 is intended for use as the head of a robotic stitch machine. In one embodiment, the decorative chain stitch sewing head 100 is attached as an end effector to a six-axis robot 101 (shown in the photograph) that serves to position the sewing head 100 as needed with respect to the part to be sewn. Alternatively, the sewing head can be kept stationary while the robot positions the part with respect to the sewing head 100 to perform the stitch process. The decorative chain stitch sewing head 100 includes an upper head assembly 1 and a lower head assembly 2.

[0052]

[0060] As shown in FIG. 2, the upper head assembly 1 controls the movement of the needle bar 3 and the walking foot 4 mechanism. The walking foot eccentric 5 allows adjustment of the foot lift, and the stitch length eccentric 6 allows adjustment of both the walking foot advance and the needle bar advance through adjustment of the oscillating frame 6a that determines the length of the stitch.

[0053]

[0061] The assembly of the needle bar cam 7 drives the rotation of the needle bar 3 around the axis A during each stitch cycle to achieve the desired stitch pattern 8 shown in FIG. 3A. The needle bar cam 7 is directly driven by the upper shaft 9 via a pair of gears 10a, 10b that reduce the cam speed according to the size ratio of the two gears 10a, 10b. Two different cam profiles 11a, 11b are machined into the cam shown in FIG. 3. Other profiles can be added and integrated with the illustrated profile, or existing cams arranged within the sewing head can be replaced.

[0054]

[0062] The cam follower 12 engages with one of the two cam profiles 11a, 11b and then drives a link mechanism 13 connected to the cam follower 12 at one end. The link mechanism 13 is connected to the drive gear 14 at the other end via a pin 50 such that the linear movement of the link mechanism in the direction of arrow 52 enables the rotational movement of the gear 50. The smooth lateral movement of the link mechanism 13 in the direction of arrow 52 is controlled by two bearing blocks 15 that engage with a guide rail 16 that slides between the two bearing blocks 15. In FIG. 2, a portion of the guide rail 16 is shown in dashed lines. The bearing blocks 15 are fixed to a block 102 fixed to the link mechanism 13 and the cam follower 12. The drive gear 14 engages with a drive gear 17 that surrounds and is fixed to the needle bar 3, and thus rotates the needle bar 3 around the axis A as indicated by the selected cam gear profile 11a, 11b during machine operation (e.g., rotation of the shaft 9 by a motor or other device operably connected to the shaft 9).

[0055]

[0063] Alternatively, the rotation of the needle bar can be controlled by pneumatic or electric actuation instead of the aforementioned cam.

[0056]

[0064] The lower head assembly 2 is shown in FIG. 4 and incorporates a post assembly 18 that houses a looper drive mechanism 19 and a spreader shaft assembly 20. The looper cam 21 controls all rotational movement of a looper arm 51 that is rotatably fixed to a shaft 53. The looper arm 51 engages the looper cam 21 at one end and is fixed to a pair of loopers 31 at the other end of the looper arm 51. Thus, the position of the loopers 31 and the acceleration and deceleration of the loopers are controlled by the rotation of the looper cam 21. The looper cam 21 is directly driven from a lower arm shaft 22 and a belt 56 (shown in dashed lines) operably connected to the looper cam 21. The lower arm shaft 22 is rotated by a motor or other equivalent device operably coupled to the lower arm shaft 22. Thus, the rotation of the looper cam 21 causes movement of the loopers 31 via movement of the looper arm 51 (e.g., the cam follower of the looper arm 51 engages the cam path of the looper cam 21 when the looper cam 21 is rotated, and thus the looper arm 51 rotates about the shaft 53 when the looper cam 21 is rotated, changing the position of the loopers 31).

[0057]

[0065] In FIG. 5, the spreader shaft assembly 20 includes a pair of concentric shafts or spreader shafts 20a, 20b that are rotatably fixed to each other (e.g., shaft 20b is disposed around shaft 20a and shaft 20b rotates around shaft 20a). In other words, shaft 20a has an outer peripheral circle that is slightly smaller than the inner diameter of the inner opening of shaft 20b into which shaft 20a is received. Both shafts 20a, 20b are driven by a spreader cam 23 located at the base of a post on the lower shaft. The spreader cam 23 engages a spreader cam follower 24 that is directly connected to a bearing block 25 that rides on a guide rail 26 to ensure smooth linear operation.

[0058]

[0066] At the upper part of the bearing block 25 in FIG. 6, there is a pin 27 that serves as a hub for rotatably receiving one end of a pair of connecting rods 28. The other end of each of the pair of connecting rods 28 is rotatably or operably connected to one of a pair of crank arms 29. One of the pair of crank arms 29 is fixed to one of a pair of concentric shafts 20a, 20b, and the other of the pair of crank arms 29 is connected to the other of the pair of concentric shafts 20a, 20b. Accordingly, the pair of crank arms 29 and the pair of connecting rods 28 operably connect the pair of concentric shafts 20a, 20b to the spreader cam 23 such that the rotation of the spreader cam 23 rotates the pair of concentric shafts 20a, 20b relative to each other in the directions of arrows 53, 55. Accordingly, the linear motion of the bearing block 25 in the direction of arrow 57 via the pin 24 engaged with the spreader cam 23 is converted into a rotational motion of each spreader shaft 20a, 20b or the pair of concentric shafts 20a, 20b in opposite directions to each other. This rotational movement of the spreader shafts 20a, 20b also causes the rotation of the spreader 30 fixed to the opposite ends of the concentric shafts 20a, 20b.

[0059]

[0067] An explanation of the stitch formation cycle using the decorative chain stitch sewing head 100 of the present disclosure is shown in at least FIGS. 7A to 7H. FIG. 7A shows the needle 32 at the bottom dead center (BDC) position and the looper 31 retracted or in the rear position, and the spreader 30 is fully open at the start of the stitch cycle (e.g., completely separated from each other). During the stitch cycle, the looper 31 moves between the rear position and the front position, while the spreader 30 is understood to move between the fully open position and the closed position where the spreader 30 is closer to each other than the fully open position. It is understood that the spreaders do not need to contact each other when in the closed position.

[0060]

[0068] In Figure 7B, the needle 32 begins to move upward in the direction of arrow 70, while the looper 31 moves forward in the direction of arrow 72 from the rear position in Figure 7A (e.g., by the rotation of the looper cam 21) to pick up the upper thread or top thread 33 of the stitch from each of the needles 32 (e.g., each needle 32 has the upper thread or top thread 33). During this movement, the spreader 30 remains stationary in the open position.

[0061]

[0069] Figure 7C shows the looper 31 in the fully forward position in the direction of arrow 72, and the upper thread 33 and the spreader 30 are still in the fully open position. As the needle 32 approaches the top dead center (TDC) position, it begins to rotate around the needle bar axis 3a (by the rotation of the gears 14 and 17 as described above). Here, each upper thread or top thread 33 is looped around the rear end of its respective looper 31, the looper moves to the full forward position, and the spreader 30 begins to close around each lower thread 34.

[0062]

[0070] In Figure 7D, when the needle 32 moves downward from the top dead center (TDC) position in the direction opposite to arrow 70, the rotation of the needle is completed. Here, the spreader 30 is closed (e.g., it moves towards each other in the direction of arrow 76 (by the rotation of the spreader shafts 20a, 20b or the concentric shafts 20a, 20b as described above)) and pulls the bottom thread 34 out of each looper 31 (e.g., each looper 31 supplies the bottom thread 34). Here, both loopers 31 are still in the fully forward position. Since one of the shafts 20a, 20b is fixed to one side of the spreader 30 and the other of the shafts 20a, 20b is fixed to the other side of the spreader 30, the rotational movement of each spreader shaft or concentric shaft 20a, 20b relative to each other facilitates the movement of the spreader 30 towards each other and away from each other. Thus, the rotation of the shafts 20a, 20b causes the spreader 30 to move towards each other and away from each other.

[0063]

[0071] Figure 7E shows each needle 32 moving downward through a triangle created between each bottom thread 34 of each loop 31. Here, the upper thread 33 is still wrapped around the loop 31 when it begins to move backward in a direction opposite to arrow 72, at least starting from the full forward position of the loop 31 shown in Figure 7C. Here, the spreader 30 is fully closed and holds the bottom thread 34 (for example, the hook portion at the distal end of each spreader 30 engages with each of the bottom threads 34 provided by each loop 31).

[0064]

[0072] In Figure 7F, the needle 32 approaches the bottom dead center (BDC), while the loop 31 moves backward to the point where the upper thread 33 is released from the tip or distal end of the loop 31. Here, the spreader 30 remains closed or remains close to each other while each lower thread or bottom thread 34 is held by each of the pair of spreaders 30.

[0065]

[0073] In Figure 7G, the spreader 30 moves in a direction opposite to arrow 76 to the point where the bottom thread 34 is released from the tip or distal end of the spreader 30, thereby completing the stitch. The loop 31 continues to move backward in a direction opposite to arrow 72, while the spreader 30 moves toward the fully open position in a direction opposite to arrow 76, and the needle 32 is at the bottom dead center (BDC) position.

[0066]

[0074] In Figure 7H, the loop 31 is fully backward, the spreader 30 is fully open, the needle 32 remains at the bottom dead center (BDC) position, and preparations are made for the start of the next stitch cycle where the needle 32 begins to move upward in the direction of arrow 70 again.

[0067]

[0075] In FIG. 8, a top view of the stitch plate 36 of the decorative chain stitch sewing head 100 is shown. The figure shown in FIG. 8 is one of the positions during the stitch sequence described above. As shown, the loopers 31 are configured and arranged such that the scarves 35 of each looper 31 face each other (e.g., in the directions of arrows 104, 106, as opposed to both scarves 35 facing in the same direction of arrow 104 or 106). This looper orientation allows both needles 32 to pass inside each looper 31 or between both loopers 31 as shown, whereas with scarves 35 facing in the same direction, only one needle 32 passes between the two loopers and the other needle 32 must engage the other scarf 35 facing in the same direction as the other scarf 35. The spreader 30 rotates and moves laterally in opposite directions (e.g., in and out, or open and closed) relative to each other in the direction of arrow 82 rather than in the same direction in front of the tips of the loopers 31, which is required when the scarves 35 face in the same direction as opposed to facing each other according to the present disclosure. In other words, in the present disclosure, the scarves 35 face each other (e.g., are opposing faces) as opposed to scarves 35 facing in the same general direction. This configuration, in combination with the rotating concentric spreader shafts 20a, 20b, minimizes the package space requirements at the top of the lower post.

[0068]

[0076] Also shown is that the looper 31 moves between a rear position and a front position in the direction of arrow 108.

[0069]

[0077] In one embodiment, in view of the configuration of the present disclosure, the width “W” × length “L” of the stitch plate 36 can be 35 mm × 56 mm or less so as to pass the stitch plate 36 through a limited or small area of a three-dimensional part during sewing. This configuration also eliminates the tendency for the thread to become untangled during sewing.

[0070]

[0078] The foregoing configuration of width “W” 35 mm × length “L” 56 mm has been shown to produce the desired results, but the present disclosure also contemplates using dimensions smaller or larger than the foregoing dimensions.

[0071]

[0079] The rotational frequency of the needle bar and the use of a 1 to 2 needle indicate the type of stitch pattern produced.

[0072]

[0080] Referring now to FIGS. 9A - 9H, top views of the stitch forming cycle according to the present disclosure are shown.

[0073]

[0081] In FIG. 9A, the needle 32 is at the bottom dead center, the looper 31 is retracted, and the spreader 30 is open. In FIG. 9B, the needle 32 moves upward, the looper 31 moves forward to engage the upper thread 33, and the spreader 30 remains in the open position. In FIG. 9C, the needle 32 rotates around the needle bar 3 during upward movement towards the top dead center to create the desired stitch pattern, the looper 31 moves to the full forward position, and the upper thread 33 is looped around the rear end of the looper 31. Further, the spreaders 30 move towards each other in the direction of arrow 82 and engage the lower thread 34.

[0074]

[0082] In FIG. 9D, the needle 32 completes its rotation when starting the downward movement. Here, the looper 31 is fully forward, the spreaders 30 close around their respective lower threads 34, and pull the lower threads 34 out of their respective loopers 31. In FIG. 9E, the needle 32 moves downward between the triangles 135 created between the respective lower threads 34 and the arms of the looper 31, the looper 31 starts its backward movement, and the upper thread 33 remains wrapped around the looper 31. Here, the spreaders 30 are closed and the respective lower threads 34 are still held by the tips of the spreaders 30.

[0075]

[0083] In FIG. 9F, the needle 32 is near the bottom dead center, the looper 31 continues its backward movement, releases the respective upper threads 33, the spreaders 30 remain closed, and the respective lower threads 34 are held.

[0076]

[0084] In FIG. 9G, the needle 32 is at the bottom dead center, and the looper 31 is moving rearward in the direction of arrow 109. The spreader 30 is open, releasing each lower thread 34 from the tip of the spreader, thereby completing the stitch.

[0077]

[0085] In FIG. 9H, the needle 32 remains at the bottom dead center, the looper 31 is in the rear position, the spreader 30 is fully open, and preparations are complete for the start of the next stitch cycle.

[0078]

[0086] By eliminating parts and simplifying the needle bar rotation and spreader drive systems, this robotic sewing head design becomes compact enough to provide access for stitching most of the outermost areas of almost all preformed automotive trim components.

[0079]

[0087] The term "about" is intended to include the degree of error associated with the measurement of a particular quantity based on the equipment available at the time of filing. For example, "about" may include a range of ±8% or 5% or 2% of a given value.

[0080]

[0088] The terms used in this specification are for the purpose of describing particular embodiments only and are not intended to limit the disclosure. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising", when used in this specification, specify the presence of the stated features, integers, steps, operations, elements and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof.

[0081]

[0089] Although the present disclosure has been described with reference to one or more exemplary embodiments, it will be understood by those skilled in the art that various changes can be made without departing from the scope of the present disclosure, and its elements can be replaced with equivalents. Further, many modifications can be made to adapt a particular situation or material to the teachings of the present disclosure without departing from the essential scope thereof. Accordingly, the present disclosure is not limited to the particular embodiments disclosed as the best mode contemplated for carrying out the present disclosure, but the present disclosure is intended to cover all embodiments falling within the scope of the claims.

Claims

1. A decorative chain stitch head, comprising: an upper head assembly that controls the movement of a needle bar and a walking foot mechanism; a walking foot eccentric part configured to enable adjustment of both the walking foot forward movement and the needle bar forward movement through adjustment of a swing frame that determines the length of stitches created by the decorative chain stitch head, while being configured to enable adjustment of the foot lift; a lower head assembly; a needle bar cam assembly that drives the rotation of the needle bar during each stitch cycle of the decorative chain stitch head to achieve a desired stitch pattern, and is directly driven by an upper shaft through a pair of gears that reduce the speed of the needle bar cam assembly according to the size ratio of the pair of gears; A decorative chain stitch head comprising the above.

2. The decorative chain stitch head according to claim 1, wherein two different cam profiles are machined on the needle bar cam assembly.

3. The decorative chain stitch head according to claim 2, wherein a cam follower engages with one of the two different cam profiles and drives a link mechanism connected to a drive gear.

4. The decorative chain stitch head according to claim 3, wherein the lateral movement of the link mechanism is managed by two bearing blocks that engage with a guide rail.

5. A decorative chain stitch head, comprising: an upper head assembly that controls the movement of a needle bar and a walking foot mechanism, wherein the needle bar has a pair of needles; a lower head assembly, comprising: a pair of loopers each having a scarf facing each other; a pair of spreaders, wherein the lower head assembly is configured to move the pair of loopers towards and away from the pair of spreaders during the stitch sequence of the decorative chain stitch head, and the lower head assembly is configured to move the pair of spreaders towards and away from each other during the stitch sequence of the decorative chain stitch head; A lower head assembly including the above; A decorative chain stitch head comprising the above.

6. The decorative chain stitch head according to claim 5, wherein the pair of needles is received within the pair of loopers during the stitch sequence of the decorative chain stitch head.

7. The decorative chain stitch head according to claim 5, further comprising a pair of concentric shafts in the lower head assembly, wherein one of the pair of concentric shafts rotates around the other of the pair of concentric shafts, and the other of the pair of concentric shafts rotates within the one of the pair of concentric shafts, and the pair of concentric shafts are rotatably fixed to each other such that rotation of the pair of concentric shafts relative to each other causes the pair of spreaders to move towards each other and away from each other during the stitch sequence of the decorative chain stitch head, wherein one of the pair of concentric shafts is operably fixed to one of the pair of spreaders, and the other of the pair of concentric shafts is fixed to the other of the pair of spreaders.

8. The decorative chain stitch head according to claim 7, wherein the pair of concentric shafts is rotated by a spreader cam that engages a spreader cam follower directly connected to the bearing block, and rotation of the spreader cam causes rotation of the pair of concentric shafts relative to each other.

9. The decorative chain stitch head according to claim 8, wherein the bearing block rides on a guide rail.

10. The decorative chain stitch head according to claim 8, wherein the bearing block further comprises a pin that serves as a hub for rotatably receiving one end of each of a pair of connecting rods, wherein the opposite ends of each of the pair of connecting rods are rotatably fixed to one of a pair of crank arms, wherein one of the pair of crank arms is fixed to one of the pair of concentric shafts, and the other of the pair of crank arms is fixed to the other of the pair of concentric shafts.

11. The decorative chain stitch head according to claim 10, wherein linear movement of the bearing block causes rotational movement of the pair of concentric shafts relative to each other.

12. A method of providing stitches to a component using a decorative chain stitch head, comprising: moving a pair of needles up and down using an upper head assembly; During the stitch sequence of the decorative chain stitch head, engaging the upper thread of each of the pair of needles with a pair of loopers of the lower head assembly, wherein each of the pair of loopers has scarves facing each other; During the stitch sequence of the decorative chain stitch head, engaging the lower thread of each of the pair of loopers with a pair of spreaders, wherein the lower head assembly moves the pair of loopers towards and away from the pair of spreaders during the stitch sequence of the decorative chain stitch head, and the lower head assembly moves the pair of spreaders towards and away from each other during the stitch sequence of the decorative chain stitch head; A method comprising the above.

13. The method according to claim 12, wherein the pair of needles are received within the pair of loopers during the stitch sequence of the decorative chain stitch head.

14. The method according to claim 12, wherein the lower head assembly further comprises a pair of concentric shafts rotatably fixed to each other such that one of the pair of concentric shafts rotates around the other of the pair of concentric shafts and the other of the pair of concentric shafts rotates within the one of the pair of concentric shafts, and the rotation of the pair of concentric shafts relative to each other causes the pair of spreaders to move towards and away from each other during the stitch sequence of the decorative chain stitch head, wherein one of the pair of concentric shafts is operably fixed to one of the pair of spreaders and the other of the pair of concentric shafts is fixed to the other of the pair of spreaders.

15. The method according to claim 14, wherein the pair of concentric shafts are rotated by a spreader cam that engages a spreader cam follower directly connected to a bearing block, and the rotation of the spreader cam causes the pair of concentric shafts to rotate relative to each other.

16. The method according to claim 15, wherein the bearing block rides on a guide rail.

17. The bearing block further comprises a pin serving as a hub for rotatably receiving one end of each of the pair of connecting rods, wherein the opposite ends of each of the pair of connecting rods are rotatably fixed to one of the pair of crank arms, one of the pair of crank arms is fixed to one of the pair of concentric shafts, and the other of the pair of crank arms is fixed to the other of the pair of concentric shafts. The method according to claim 15.

18. The method according to claim 17, wherein the linear movement of the bearing block causes a rotational movement of the pair of concentric shafts relative to each other.

19. The method according to claim 12, wherein the movement of the pair of loopers and the pair of spreaders is restricted to an area defined by a stitch plate having a width of 35 mm or less and a length of 56 mm or less during the stitch sequence of the decorative chain stitch head.

20. The pair of needles are received within the pair of loopers during the stitch sequence of the decorative chain stitch head, and the lower head assembly further comprises a pair of concentric shafts, wherein one of the pair of concentric shafts rotates around the other of the pair of concentric shafts, and the other of the pair of concentric shafts rotates within the one of the pair of concentric shafts, and the pair of concentric shafts are rotatably fixed to each other. The rotation of the pair of concentric shafts relative to each other causes the pair of spreaders to move towards each other and away from each other during the stitch sequence of the decorative chain stitch head. One of the pair of concentric shafts is operably fixed to one of the pair of spreaders, and the other of the pair of concentric shafts is fixed to the other of the pair of spreaders. The method according to claim 12.

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