Sewing device

Abstract

The present invention provides a sewing device capable of properly cutting off top thread and bottom thread. A CPU lowers a middle presser foot to a contact position at a lowering timing (T1) when sewing a final needle before a needle number, and presses a workpiece. After a sewing needle forms a stitch, the CPU does not return the middle presser foot to a separation position at a raising timing (T2). When the workpiece moves to a position corresponding to a drop point of the final needle, the CPU maintains the middle presser foot at the contact position, and presses the workpiece, thereby suppressing the workpiece from shaking up and down.

Description

Technical Field

[0001] This invention relates to sewing devices. Background Technology

[0002] The sewing device includes a presser foot and a thread-cutting mechanism. The presser foot moves up and down between a contact position with the workpiece and a separation position above the contact position. During sewing, the presser foot descends towards the contact position in conjunction with the up and down movement of the needle bar, intermittently pressing the workpiece placed on the upper surface of the needle plate. The thread-cutting mechanism includes a movable blade and a fixed blade. When sewing is complete, the tip of the movable blade plunges into the loop of the top thread to capture the bobbin thread and the top thread on the workpiece side. The movable blade and the fixed blade cross, cutting the captured top and bobbin threads.

[0003] The sewing device described in Patent Document 1 also lowers the pressure foot to the contact position during cutting, and drives the thread cutting mechanism while the workpiece is pressed against the needle plate to cut the bottom thread and the top thread on the workpiece side. As a result, the sewing device shortens the length of the top thread and bottom thread remaining on the back of the workpiece after cutting.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2022-27312 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] During sewing, the workpiece moves up and down, sometimes pulling the bobbin thread excessively out from under the needle plate. If this happens before the sewing is finished, the bobbin thread slackens under the needle plate by pressing down on the workpiece with the presser foot during cutting. This slackened bobbin thread spirals around the loop of the top thread from the outside, reducing the loop's opening. In this situation, the movable blade cannot penetrate the loop of the top thread, potentially cutting off the remaining top thread on the needle side along with the bobbin thread and the workpiece side of the top thread from the outside of the loop.

[0009] The purpose of this invention is to provide a sewing device capable of properly cutting the top and bottom threads.

[0010] Methods for solving problems

[0011] According to one aspect of the present invention, a sewing apparatus is provided, comprising: a needle bar extending in a vertical direction and capable of mounting a sewing needle at its lower end; a needle bar mechanism for moving the needle bar vertically; a middle presser foot bar having a middle presser foot at its lower end and extending vertically parallel to the needle bar; a needle plate having a needle hole for the sewing needle to pass through and for holding a workpiece; and a thread cutting mechanism for cutting the top thread and the bottom thread below the needle plate. The sewing apparatus is characterized by comprising: a drive source for moving the middle presser foot bar vertically, thereby moving the middle presser foot vertically between a contact position in contact with the workpiece and a separation position above the contact position; and a drive control unit that, when sewing a number of stitches at least one stitch before the final stitch before the cutting of the top thread and the bottom thread by the thread cutting mechanism, controls the drive source to lower the middle presser foot to the contact position, and prevents the middle presser foot from returning to the separation position until the final stitch is completed.

[0012] The drive control unit prevents the presser foot from returning to the separation position from the start of sewing (at least the number of stitches preceding the final stitch) until the final stitch is completed, thereby suppressing the up-and-down movement of the workpiece. Consequently, the bobbin thread is not pulled up from below the needle plate before being cut by the thread cutting mechanism, and the top thread does not entangle during cutting. Therefore, when the thread cutting mechanism cuts, the tip of the movable blade thrusts into the loop of the top thread, reliably capturing and cutting both the bobbin thread and the top thread on the workpiece side together.

[0013] Alternatively, the system may also include a position setting unit for setting the contact position and the separation position of the presser foot. The drive control unit controls the drive source to position the presser foot at the set contact position during sewing of the stitch preceding the final stitch and during the sewing of the final stitch, respectively. After these sewing operations, the system does not control the presser foot to return to the set separation position. When the drive control unit moves the presser foot to the contact position during sewing of the stitch number preceding the final stitch, it does not return the presser foot to the separation position. Therefore, when the workpiece moves according to the point where the final stitch lands, it is pressed down by the presser foot and does not wobble up and down. Therefore, before the thread cutting mechanism cuts, the bobbin thread is not pulled up from below the needle plate, and the top thread does not entangle during cutting. Thus, when the thread cutting mechanism cuts, the tip of the movable blade thrusts into the loop of the top thread, reliably capturing and cutting both the bobbin thread and the top thread on the workpiece side together.

[0014] Alternatively, the position setting unit of this solution can set the position of the middle presser foot during the operation of the thread-cutting mechanism to a thread-cutting contact position, which is a position different from the regular contact position. The drive control unit controls the drive source so that when the operation of the thread-cutting mechanism begins, the middle presser foot moves from the contact position during the final needle stitching to the set thread-cutting contact position. With the middle presser foot pressing down on the workpiece, the thread-cutting mechanism cuts the top thread and bottom thread below the needle plate. Therefore, the sewing device can shorten the length of the top thread and bottom thread remaining on the back of the workpiece.

[0015] Alternatively, this solution may also include an input unit, whereby the position setting unit sets the input result from the input unit as the contact position. The sewing device can set the contact position based on the input result from the operator, thus improving operator convenience.

[0016] Alternatively, in this solution, the drive control unit, during the sewing of the stitch count preceding the final stitch, controls the middle presser foot to descend to the contact position in sync with the descent of the needle bar, implemented by the needle bar mechanism. During the rise of the needle bar, the drive control unit does not control the middle presser foot to rise to the separation position, maintaining the middle presser foot in the contact position until the final stitch is completed. After descending the middle presser foot to the contact position during the sewing of the stitch count preceding the final stitch, the drive control unit does not return the middle presser foot to the separation position. Therefore, the drive control unit can easily perform the process of moving the middle presser foot in sync with the movement of the needle bar.

[0017] Alternatively, in this solution, the drive control unit, after controlling the drive source to position the presser foot in the contact position during sewing of the stitch count preceding the final stitch, will not control the presser foot to rise to the separation position until the cutting mechanism finishes cutting the top and bottom threads, thus maintaining the presser foot in the contact position. Conversely, after lowering the presser foot to the contact position during sewing of the stitch count preceding the final stitch, the drive control unit will not return the presser foot to the separation position until the cutting of the top and bottom threads is completed. Therefore, compared to processes where the presser foot is moved to the contact and separation positions during sewing and cutting respectively, the drive control unit can easily control the movement of the presser foot.

[0018] Alternatively, the system may also include a thread-sweeping mechanism that moves the end of the top thread cut by the thread-cutting mechanism of this solution upwards towards the middle presser foot. When the drive control unit controls the drive source to position the middle presser foot at the contact position during sewing (one stitch before the final stitch), it does not control the middle presser foot to rise to the separation position until the thread-sweeping by the thread-sweeping mechanism ends, thus maintaining the middle presser foot at the contact position. When the drive control unit lowers the middle presser foot to the contact position during sewing (one stitch before the final stitch), it does not return the middle presser foot to the separation position until the thread-sweeping of the end of the top thread cut by the thread-cutting mechanism ends. Therefore, compared to the process of moving the middle presser foot to the contact and separation positions during sewing, cutting, and thread-sweeping respectively, the drive control unit can easily control the movement of the middle presser foot.

[0019] It could be an action setting unit that sets whether or not to execute the drive control unit of this solution, and the drive control unit controls the position of the presser foot according to the settings of the action setting unit. The sewing device improves operator convenience by allowing the operator to set whether or not the drive control unit executes the action.

[0020] This can be achieved by having a stitch length comparison unit that compares the number of stitches preceding the final stitch in this solution with the stitch length of the final stitch and a predetermined threshold. The operation setting unit is configured to execute the operation of the drive control unit when the stitch length is less than the threshold. When the stitch length is shorter than the predetermined threshold, the bobbin thread is easily pulled up from below the needle plate when the workpiece moves up and down, potentially causing slack and tangling of the top thread during cutting. Therefore, when the stitch length is shorter than the threshold, the drive control unit maintains the presser foot in a contact position from the start of sewing at least the number of stitches preceding the final stitch, thereby suppressing up and down movement of the workpiece until cutting. Thus, the thread cutting mechanism can reliably capture and cut the bobbin thread and the top thread on the workpiece side together using a movable blade.

[0021] It can be equipped with a sewing control unit that adds a short stitch (cutting off the normal stitch length) immediately before the final stitch specified in the sewing data of this solution. The sewing control unit controls the position of the presser foot during the stitching of this short stitch (which is the number of stitches preceding the final stitch). When a short stitch is present, the bobbin thread is easily pulled up from below the needle plate if the workpiece moves up and down, potentially causing slack and tangling of the top thread during cutting. Therefore, when the sewing control unit adds a short stitch, the drive control unit maintains the presser foot in a contact position from the start of sewing at least the number of stitches preceding the final stitch, thereby suppressing up and down movement of the workpiece until cutting. Thus, the thread cutting mechanism can reliably capture and cut the bobbin thread and the top thread on the workpiece side together using a movable blade.

[0022] It may include a sewing setting unit that determines whether to execute the additional sewing action of the sewing control unit on the short stitches as described in this solution, and the sewing control unit performs the sewing action according to the setting of the sewing setting unit. By allowing the operator to set whether the sewing control unit adds the short stitch sewing action, the sewing device improves the operator's convenience. Attached Figure Description

[0023] Figure 1 This is a three-dimensional view of sewing device 1.

[0024] Figure 2 This is a three-dimensional view of the needle bar mechanism 6 and the shuttle mechanism 7 viewed from the upper right front.

[0025] Figure 3 This is a three-dimensional view of the needle bar mechanism 6 and the shuttle mechanism 7 viewed from the upper left front.

[0026] Figure 4 This is a three-dimensional view of the needle bar mechanism 6 and the shuttle mechanism 7 viewed from the lower left rear.

[0027] Figure 5 This is a block diagram showing the electrical structure of the sewing device 1.

[0028] Figure 6 This is the flowchart for the main processing.

[0029] Figure 7 It is a follow-up to the main processing flowchart.

[0030] Figure 8 It is a follow-up to the main processing flowchart.

[0031] Figure 9It is a graph showing the movement of the needle bar 63, the presser foot mechanism 120, and the tangent mechanism 110 relative to the output shaft of the main motor 32 from the time of sewing from the stitch count before the final stitch to the completion of sewing.

[0032] Figure 10 This is a schematic diagram showing the state of the sewn material W and the presser foot 64 when the tangent is being cut. Detailed Implementation

[0033] The physical structure of a sewing device 1 according to one embodiment of the present invention will be described. In the following description, the left-right, front-back, and up-down directions indicated by arrows in the figures will be used. Figures 1-4 As shown, the sewing device 1 is a gate-type sewing device. The sewing device 1 includes a base section 2, support sections 3 and 4, and a synchronization mechanism 31 (see reference). Figure 5 ), transportation agency 9 (refer to Figure 5 ), Beam 5, Needle bar mechanism 6, Middle pressure foot mechanism 120, Thread sweeping mechanism 130, Shuttle mechanism 7, Thread cutting mechanism 110, Conveying mechanism 10 (refer to) Figure 5 ), holding mechanism 8 and operating section 14.

[0034] The base portion 2 includes a base 21, a first mounting portion 22, a second mounting portion 76, openings 24 and 25, a pleated plate 26 and 27, a pair of rails, a frame 28, and a lower rail 29. The base 21 is generally rectangular. The first mounting portion 22 is a plate extending parallel to the horizontal plane, forming the upper surface of the base 21. The first mounting portion 22 has an opening 23 extending in the left-right direction. The second mounting portion 76 is a rectangular plate-shaped structure arranged coplanarly with the first mounting portion 22 in front of it. The opening 24 extends in the front-rear direction near the left end of the first mounting portion 22. The opening 25 extends in the front-rear direction near the right end of the first mounting portion 22. Openings 24 and 25 are respectively portions extending in a rectangular shape from a top view between the front and rear ends of the first mounting portion 22 and opening upwards. The pleated plates 26 and 27 cover openings 24 and 25, respectively. A pair of tracks are located below the bellows sections 26 and 27. These tracks support the connecting portions 78 and 79 of the conveying mechanism 10 in a manner that allows movement in the front-to-back direction. The frame 28 is a lattice-shaped structure that supports the base 21 from below. The lower track 29 extends in the left-to-right direction below the first mounting section 22. The lower track 29 supports the shuttle mechanism 7 in a manner that allows movement in the left-to-right direction. The base section 2 is positioned below the first mounting section 22, where the lower belt 94, lower spline shaft 34, and shuttle mechanism 7 (described later) are arranged.

[0035] Support sections 3 and 4 are approximately quadrangular prisms. Support section 3 extends upward from approximately the center in the front-rear direction at the left end of the base section 2. Support section 4 extends upward from approximately the center in the front-rear direction at the right end of the base section 2. Support sections 3 and 4 separate the first mounting section 22 in the left-right direction while placing it in the middle. The synchronization mechanism 31 is a mechanism for synchronously driving the needle bar mechanism 6 and the shuttle mechanism 7, and includes a main motor 32 (see reference). Figure 5 The main motor 32 is supported by the support column 3. The upper spline shaft 33 and the lower spline shaft 34 extend in the left-right direction between the support columns 3 and 4. The transmission mechanism of the synchronization mechanism 31 is housed in the support column 3 and transmits the power of the main motor 32 to the upper spline shaft 33 and the lower spline shaft 34.

[0036] The conveying mechanism 9 is capable of transporting relative to the sewn material W (refer to...) Figure 10 The shuttle mechanism 7 and needle bar mechanism 6 move in a left-right direction parallel to the horizontal direction, and include an upper belt 93, a lower belt 94, an X motor 95, and a transmission mechanism (described later). In the sewing device 1 of this example, the holding mechanism 8 holds the workpiece W. The X motor 95 is a pulse motor and is supported by the support column 4. The transmission mechanism of the transport mechanism 9 is housed in the support column 4. The transmission mechanism transmits the power of the X motor 95 to the upper belt 93 and the lower belt 94. The upper belt 93 is fixed to the back of the needle bar mechanism 6. The lower belt 94 is fixed to the back of the shuttle mechanism 7. The shuttle mechanism 7 and needle bar mechanism 6 move left and right according to the rotation of the X motor 95.

[0037] A beam 5 extends in the left-right direction and is mounted between support sections 3 and 4. The beam 5 supports the needle bar mechanism 6 at its rear. The needle bar mechanism 6 is movable in the left-right direction, parallel to the horizontal direction. The beam 5 includes a housing 51, a serpentine 52, and an upper rail 53. The housing 51 extends in the left-right direction at the upper and rear ends of each of the support sections 3 and 4. The serpentine 52 is mounted at the front ends of each of the support sections 3 and 4 and the housing 51, and at the left and right ends of the needle bar mechanism 6 (described later). The upper rail 53 is a rod-shaped structure extending in the left-right direction and is mounted between the support sections 3 and 4. The upper rail 53 supports the needle bar mechanism 6 in a manner that allows it to move in the left-right direction. The housing 51 covers the upper rail 53 and the upper spline shaft 33 of the synchronization mechanism 31 on its upper and rear sides. The serpentine 52 covers the upper rail 53 and the front side of the upper spline shaft 33. The serpentine 52 extends and retracts according to the left-right movement of the needle bar mechanism 6.

[0038] The needle bar mechanism 6 is positioned at the front relative to the beam portion 5. The needle bar mechanism 6 includes a housing 60, an upper shaft 61, a transmission mechanism 62, and a needle bar 63, enabling the needle bar 63 to move vertically. The housing 60 is box-shaped and houses the upper shaft 61. The back of the housing 60 is connected to the upper belt 93. The upper rail 53 supports the housing 60. The needle bar mechanism 6 can move left and right along the upper rail 53 within the beam portion 5, driven by the transport mechanism 9. The upper shaft 61 extends in the left-right direction. The transmission mechanism 62 transmits power from the upper spline shaft 33 to the upper shaft 61. The needle bar 63 extends in the vertical direction and can be fitted with a sewing needle 65 at its lower end. The needle bar 63 is connected to the upper shaft 61 and moves vertically, driven by the main motor 32.

[0039] The middle pressure foot mechanism 120 includes a middle pressure foot rod 69, a middle pressure foot motor 68, and a transmission mechanism 121. Figure 2 The diagram of the presser foot motor 68 and the transmission mechanism 121 is omitted. The presser foot bar 69 extends vertically parallel to the needle bar 63. The presser foot bar 69 has a presser foot 64 at its lower end. The presser foot 64 has a through hole through which the needle 65 passes as the needle bar 63 moves vertically, intermittently pressing the workpiece W from above. The presser foot motor 68 is a pulse motor fixed to the upper surface of the housing 60. The presser foot motor 68 moves the presser foot bar 69 vertically, causing the presser foot 64 to move vertically between a contact position that contacts the workpiece W and a separation position above the contact position. The transmission mechanism 121 connects the output shaft of the presser foot motor 68 and the presser foot bar 69, transmitting the rotation of the output shaft of the presser foot motor 68 to the presser foot bar 69.

[0040] The sweeping mechanism 130 performs the cutting of the surface line M by the cutting mechanism 110 (see reference). Figure 10 The thread sweeping mechanism 130 moves upward toward the center presser foot 64. It includes a cylinder 131, a connecting rod 134, a thread sweeping shaft 135, and a thread sweeping rod 136. The thread sweeping mechanism 130 is fixed to the back of the housing 60 of the sewing device 1. The cylinder 131 draws the output shaft. The connecting rod 134 connects the output shaft of the cylinder 131 and the thread sweeping shaft 135. As the output shaft moves, the thread sweeping shaft 135 rotates via the connecting rod 134. The thread sweeping rod 136 is fixed to the thread sweeping shaft 135 and oscillates as the thread sweeping shaft 135 rotates. The tip of the thread sweeping rod 136 moves from the standby position to the thread sweeping position when the cylinder 131 draws the output shaft. Figure 2 , Figure 3As shown, in the standby position, the top of the thread sweeping lever 136 is to the right of the thread sweeping shaft 135. In the thread sweeping position, the top of the thread sweeping lever 136 is below the thread sweeping shaft 135. During the movement from the standby position to the thread sweeping position, the top of the thread sweeping lever 136 captures the top thread M between the lower end of the sewing needle 65 and the upper end of the cylinder of the presser foot 64. When the suction of the cylinder 131 stops, the top of the thread sweeping lever 136 moves back to the standby position due to the force of the spring. Therefore, the thread sweeping lever 136 can move the top thread M above the presser foot 64. The bottom thread L remains on the back side of the sewn work W (the side opposite the needle plate 74).

[0041] The shuttle mechanism 7 is located below the needle bar mechanism 6 and inside the base portion 2. The shuttle mechanism 7 includes a housing 70, a lower shaft 71, a transmission mechanism 72, and a shuttle 73. The housing 70 is box-shaped and has a needle plate 74 at its upper left end. The needle plate 74 has a needle hole 75 through which a sewing needle 65 can be inserted. The needle hole 75 is located below the needle bar 63. Figure 10 As shown, the pinhole 75 has a countersunk hole 77 at its upper end. The countersunk hole 77 is a tapered portion whose diameter increases towards the upper part. Figure 2 As shown, the back of the housing 70 is connected to the lower belt 94. The housing 70 provides a passage for the lower spline shaft 34. The lower track 29 supports the housing 70. The shuttle mechanism 7 can move left and right along the lower track 29 synchronously with the needle bar mechanism 6, driven by the transport mechanism 9. The transmission mechanism 72 transmits the power of the lower spline shaft 34 to the lower shaft 71. The shuttle 73 is connected to the lower shaft 71 and rotates synchronously with the up and down movement of the needle bar 63, driven by the main motor 32.

[0042] The tangent mechanism 110 cuts the top thread M and the bottom thread L below the needle plate 74. For example... Figure 3 , Figure 4As shown, the tangling mechanism 110 includes a fixed blade 111, a movable blade 112, a tangling motor 113, and a linkage mechanism 114. A portion of the linkage mechanism 114 and the tangling motor 113 are located on the outside of the housing 70. The tangling mechanism 110 moves the movable blade 112 via the linkage mechanism 114 to cut the top thread M and the bottom thread L. The fixed blade 111 is fixed to the lower side of the needle plate 74. The movable blade 112 is arranged in a manner that allows it to rotate horizontally relative to the fixed blade 111. The movable blade 112 can move between a standby position where it is away from the fixed blade 111, a cutting position where it intersects the fixed blade 111 and cuts the top thread M and the bottom thread L, and a maximum movable position opposite to the standby position relative to the cutting position. The tangling motor 113 is a pulse motor that drives the movable blade 112. Linkage mechanism 114 connects the output shaft of tangent motor 113 and movable blade 112, transmitting the rotation of the output shaft to movable blade 112. When movable blade 112 moves from standby position to maximum movable position, the tip 116 of movable blade 112 plunges into the loop of top thread M, capturing top thread M. When movable blade 112 rotates back to standby position from maximum movable position, the cutting edges of movable blade 112 and fixed blade 111 simultaneously cut the top thread M on the workpiece W side of the loop of top thread M in the thread loop of bottom thread L and top thread M at the cutting position between the maximum movable position and standby position.

[0043] The conveying mechanism 10 enables the holding mechanism 8, which holds the workpiece W, to move back and forth relative to the needle bar mechanism 6 and the shuttle mechanism 7. The conveying mechanism 10 includes connecting portions 78 and 79. The lower left end of the connecting portion 78 is positioned on a track at the opening 24 of the machine base 2. The lower right end of the connecting portion 79 is positioned on a track at the opening 25 of the machine base 2. The connecting portions 78 and 79 are connected to the holding mechanism 8. The holding mechanism 8 holds the workpiece W. The holding mechanism 8 includes an upper frame 81, a lower frame 82, and cylinders 83 and 84. The upper frame 81 and the lower frame 82 are rectangular frames in plan view, holding the workpiece W in the middle. The upper frame 81 opens and closes vertically relative to the lower frame 82, driven by cylinders 83 and 84.

[0044] The conveying mechanism 10 has a Y motor 101 below the first mounting section 22 (see reference). Figure 5 The conveying mechanism 10 transmits power from the Y motor 101 to a pair of belts fixed to the connecting parts 78 and 79. The holding mechanism 8 moves back and forth along a pair of tracks on the base part 2 according to the rotation of the Y motor 101.

[0045] The operation unit 14 is supported on the left end of the second mounting unit 76. The operation unit 14 includes a switch assembly 12 and a display unit 13. The switch assembly 12 inputs various instructions according to the operator's operation. The display unit 13 is a liquid crystal display capable of displaying various images.

[0046] Reference Figure 5 The electrical structure of the sewing device 1 is described below. The control unit 15 of the sewing device 1 includes a CPU 16, a ROM 17, a RAM 18, a storage device 19, an input / output interface (I / O) 20, and drive circuits 41-48. The CPU 16 provides overall control over the operation of the sewing device 1. The ROM 17 pre-stores programs for executing various processes. The RAM 18 temporarily stores various information generated during the execution of various processes. The storage device 19 is non-volatile and stores various setting values.

[0047] Each drive circuit 41-48, encoder 55-59, and switch group 12 are connected to I / O 20. Drive circuit 41 is connected to the main motor 32 of the synchronization mechanism 31 and drives the main motor 32 through control commands from CPU 16. Drive circuit 42 is connected to the X motor 95 of the conveying mechanism 9 and drives the X motor 95 through control commands from CPU 16. Drive circuit 43 is connected to the Y motor 101 of the conveying mechanism 10 and drives the Y motor 101 through control commands from CPU 16. Drive circuit 43 is connected to the cylinders 83 and 84 of the holding mechanism 8 and drives the cylinders 83 and 84 through control commands from CPU 16. Drive circuit 45 is connected to the cylinder 131 and drives the cylinder 131 through control commands from CPU 16. Drive circuit 46 is connected to the intermediate pressure foot motor 68 and drives the intermediate pressure foot motor 68 through control commands from CPU 16. Drive circuit 47 is connected to the tangential motor 113 and drives the tangential motor 113 through control commands from CPU 16. The drive circuit 48 is connected to the display unit 13 and displays various information on the display unit 13 through the control instructions of the CPU 16.

[0048] Encoder 55 detects the rotational position and speed of the output shaft of the main motor 32 and inputs the detection result to I / O20. The detection result of encoder 55 indicates the vertical position of the needle bar 63 and the sewing needle 65. Encoder 56 detects the rotational direction, position, and speed of the output shaft of the X motor 95 and inputs the detection result to I / O20. The detection result of encoder 56 indicates the horizontal position of the needle bar mechanism 6 and the shuttle mechanism 7. Encoder 57 detects the rotational direction, position, and speed of the output shaft of the Y motor 101 and inputs the detection result to I / O20. The detection result of encoder 57 indicates the forward and backward position of the holding mechanism 8. Encoder 58 detects the rotational direction, position, and speed of the output shaft of the middle presser foot motor 68 and inputs the detection result to I / O20. The detection result of encoder 58 indicates the vertical position of the middle presser foot 64. Encoder 59 detects the rotational direction, position, and speed of the output shaft of the tangential motor 113 and inputs the detection result to I / O20. The encoder 59 detects the rotational position of the movable blade 112. The switch group 12 detects various indications and inputs the detection results to I / O 20.

[0049] Reference Figures 6-10 The main processing is as follows: After the sewing device 1 forms a stitch on the workpiece W according to the sewing data, the top thread M and the bottom thread L are cut by the thread cutting mechanism 110, and the cut edge of the top thread M is moved upward from below the needle plate 74 by the thread sweeping mechanism 130. During sewing, the sewing device 1 controls the middle presser foot motor 68 to move the middle presser foot 64 to the contact position before the needle 65 descends to the needle drop point, and moves the middle presser foot 64 to the separation position after the needle 65 rises to form a stitch. After the stitch is formed, the sewing device 1 controls the middle presser foot 64 to be in the contact position when the thread cutting mechanism 110 cuts the top thread M and the bottom thread L and when the thread sweeping mechanism 130 sweeps the thread. In this embodiment, in order to suppress the up-and-down movement of the workpiece W, the sewing device 1 moves the presser foot 64 to the contact position during the sewing process with the number of stitches before the final stitch, and then keeps the presser foot 64 in the contact position until the sewing is completed, without returning it to the separation position.

[0050] The main processing is initiated when the operator operates the switch group 12 and selects the start of processing from the menu displayed on the display unit 13. The CPU 16 reads the main processing program from the ROM 17 into the RAM 18 and executes the main processing. The sewing data includes coordinate data that indicates the position of the needle drop point within the sewing area of ​​the holding mechanism 8 for each stitch, and is pre-stored in the storage device 19. Figure 9 As shown, storage device 19 stores data during times T1 to T7. It should be noted that during… Figure 9In the diagram, the vertical position of the needle bar 63 relative to the output shaft of the main motor 32, the rotational position of the movable blade 112, the vertical position of the intermediate pressure foot 64, and the rotational position of the brush sweeping rod 136 are shown in thick lines. Regarding the angle of the output shaft of the main motor 32, the vertical position of the needle bar 63 is set to 0 degrees when the upper dead point is reached.

[0051] like Figure 6 As shown, the CPU 16 obtains sewing data by referring to the storage device 19 (S1). The CPU 16 sets the contact position and separation position of the presser foot 64 during sewing (S2). The contact position is the lower end position of the presser foot 64 when it moves up and down during sewing. As described above, the sewing device 1 maintains the presser foot 64 in the contact position from the start of sewing up to the end of sewing, without returning it to the separation position. The contact position set in S2 can be the same as the contact position of the presser foot 64 from the start of sewing up to the start of sewing up to the end of sewing up to two stitches before the last stitch, or it can be set to a different position. The CPU 16 can also automatically set the contact position according to the sewing conditions such as the thickness and material of the workpiece W, or the conditions specified by the sewing data. The CPU 16 sets the lower end of the presser foot 64 slightly above the upper surface of the workpiece W as the separation position of the presser foot 64 during sewing. CPU16 will move downwards from the position where the central presser foot 64 contacts the workpiece W, away from the thickness D1 of the first mounting portion 22 (refer to...). Figure 10 The size and position of the contact position are set as the contact position. The CPU16 moves downward from the position where the presser foot 64 contacts the workpiece W, away from the thickness D1 of the first mounting part 22 and the height D2 of the countersunk hole 77 of the needle hole 75 (refer to...). Figure 10 The position of the sum of the values ​​is set as the contact position when the tangent is formed, i.e., the tangent position. The CPU16 can also set the contact position, separation position, and tangent position based on the input results of the switch group 12.

[0052] CPU16 sets the descent timings T1 and T3 and the rise timing T2 (S3). Descent timings T1 and T3 occur when, during sewing, the needle bar 63 descends and the needle 65 falls towards the needle drop point, causing the presser foot 64 to move to the contact position, thus pressing the workpiece W down using the presser foot 64. Rise timing T2 occurs when, before the needle bar 63 rises and the workpiece W moves towards the next needle drop point, the presser foot 64 moves to the separation position, thus releasing the pressure on the workpiece W. CPU16 can also set the input results of switch group 12 to descent timings T1, T3, and rise timing T2. CPU16 can also automatically set descent timings T1, T3, and rise timing T2 based on sewing conditions such as the thickness and material of the workpiece W, or conditions specified by sewing data. Figure 9As shown, in this embodiment, the CPU 16 sets descent timings T1 and T3 within a pre-stored range R1 in the storage device 19, and sets an ascent timing T2 within a range R2. The CPU 16 represents the descent timings T1, T3, and ascent timing T2 as the rotation angle of the main motor 32, and stores them in the storage device 19. It should be noted that descent timings T1 and T3 are the same timings under the rotation angle of the main motor 32. For convenience, the descent timing during sewing from the start of sewing to the number of stitches before the final stitch is designated as T1, and the descent timing during the final stitch is designated as T3.

[0053] like Figure 6 As shown, the CPU 16 performs action settings and stitch settings (S4) based on the operator's input to the switch group 12. The action settings determine whether or not the process of preventing the presser foot 64 from returning to the separation position during sewing from the stitch count before the final stitch until the sewing is completed is executed. When the action setting is ON, the CPU 16 executes the process of preventing the presser foot 64 from returning to the separation position during sewing from the stitch count before the final stitch until the sewing is completed. The stitch settings determine whether or not the process of dividing the stitch (stitch) between the stitch point before the final stitch and the stitch point of the final stitch into two short stitches (short stitches) is executed. When the stitch setting is ON, the CPU 16 adds a new stitch point between the stitch point before the final stitch and the stitch point of the final stitch in the sewing data.

[0054] CPU 16 determines whether a sewing start instruction has been detected (S6). The operator operates switch group 12 to input the sewing start instruction. If no sewing start instruction is detected (S6: No), CPU 16 remains in standby mode in S6 until a sewing start instruction is detected. If a sewing start instruction is detected (S6: Yes), CPU 16 begins the following process: it reads the coordinate data of the sewing data obtained in S1 according to the sewing sequence, and drives the transport mechanism 9, the conveying mechanism 10, and the synchronization mechanism 31 according to the coordinate data to perform sewing within the sewing area of ​​the holding mechanism 8 (S7).

[0055] like Figure 7As shown, CPU 16 determines whether the next coordinate data is the coordinate data of the stitch count before the final stitch (S11). The final stitch is the last stitch in the sewing sequence. When the next coordinate data is not the coordinate data of the stitch count before the final stitch (S11: No), CPU 16 executes the processing of S16 to S27, and performs sewing according to the sewing data obtained in S1. CPU 16 determines whether it is the descent timing T1 set in S3 based on the detection result of encoder 55 (S16). When it is not the descent timing T1 (S16: No), CPU 16 stands still in S16 until it becomes the descent timing T1. When it is the descent timing T1 (S16: Yes), CPU 16 determines whether the coordinate data in the sewing process is the coordinate data of the final stitch (S17). When the coordinate data in the sewing process is not the coordinate data of the final stitch (S17: No), the coordinate data in the sewing process is any coordinate data from the start of sewing up to the stitch count before the final stitch. CPU16 drives the intermediate pressure foot motor 68, causing the intermediate pressure foot 64 to descend to the contact position set in S2 (S18). Figure 10 As shown, when the presser foot 64 is in the contact position, it presses the workpiece W towards the needle plate 74. The portion of the workpiece W pressed by the presser foot 64 deforms, and the lower end of the workpiece W becomes lower than the upper end of the first mounting portion 22. The needle bar 63 descends and then rises, forming a stitch on the workpiece W using the needle 65.

[0056] like Figure 7 As shown, CPU 16 determines whether the rising timing T2 set in S3 is occurring based on the detection result of encoder 55 (S19). If it is not rising timing T2 (S19: No), CPU 16 remains in standby mode in S19 until rising timing T2 occurs. If it is rising timing T2 (S19: Yes), CPU 16 determines whether the coordinate data during sewing is the coordinate data of the stitch count before the final stitch (S21). If the coordinate data during sewing is not the coordinate data of the stitch count before the final stitch (S21: No), CPU 16 drives the presser foot motor 68, causing the presser foot 64 to rise to the separation position set in S2 (S27). The workpiece W moves to the next needle drop point. CPU 16 returns the processing to S11 and performs sewing according to the sewing data obtained in S1.

[0057] The sewing continues on the workpiece W. When the next coordinate data is the coordinate data of the stitch count before the final stitch (S11: Yes), CPU 16 determines whether the stitch setting set in S4 is ON (S12). If the stitch setting is OFF (S12: No), CPU 16 moves the process to S16 and does not perform the process of dividing the stitch between the point of the previous stitch and the point of the final stitch. If the stitch setting is ON (S12: Yes), CPU 16 moves the process to S13. CPU 16 performs the stitch segmentation process in the sewing data, adding the coordinate data of the newly added stitch point at the position where the distance between the two points is divided into two segments based on the coordinate data of the point of the previous stitch and the point of the final stitch (S13). CPU 16 sets the coordinate data of the newly added stitch point to the coordinate data of the point of the previous stitch (S14). CPU 16 moves the process to S16.

[0058] When dividing the stitches, the coordinate data during sewing becomes the coordinate data for the number of stitches two stitches before the final stitch. Therefore, CPU 16 performs processes S16 to S27 to sew the number of stitches two stitches before the final stitch. During the sewing of the stitch before the final stitch, after CPU 16 lowers the presser foot 64 to the contact position at the descent timing T1, it checks whether the action setting set in S4 is ON at the rise timing T2 (S21: Yes, S22). If the action setting is OFF (S22: No), CPU 16 moves the processing to S27 and performs the normal sewing action of the presser foot 64. If the action setting is ON (S22: Yes), CPU 16 calculates the stitch length between the point where the stitch before the final stitch lands and the point where the final stitch lands based on the sewing data (S23). If the stitch length is above a predetermined threshold (S24: Yes), CPU 16 moves the processing to S27 and raises the presser foot 64 to the separation position (S27). When the workpiece W moves to the point where the final needle falls, the length of the bobbin thread L released from the bobbin below the needle plate 74, extending at least from the needle hole 75 to the stitch preceding the final needle, is at least a threshold value. In this case, when the workpiece W moves up and down, the bobbin thread L can respond to the movement on the underside of the workpiece W only by the portion extending from the needle hole 75 to the stitch preceding the final needle. Therefore, the bobbin thread L is not pulled up from below the needle plate 74, does not slack during cutting, and thus does not entangle the top thread M. Therefore, the CPU 16 does not perform the process of preventing the presser foot 64 from returning to the separation position when sewing the stitch count preceding the final needle.

[0059] If the length of the stitch is shorter than the specified threshold (S24: No), when sewing the stitch count before the final stitch, the CPU16 maintains the presser foot 64 in the contact position as the needle bar 63 rises (S26), preventing it from returning to the separation position. The CPU16 then returns the process to S11.

[0060] Continue sewing onto the workpiece W. When the coordinate data during sewing at the descent timing T3 is the coordinate data of the final stitch (S17: Yes), such as... Figure 8 As shown, CPU 16 determines whether the action setting is ON (S31). When the action setting is OFF (S31: No), the presser foot 64 returns to the separation position during the stitching of the stitch before the final stitch. Therefore, CPU 16 drives the presser foot motor 68 to lower the presser foot 64 to the contact position (S33), causing the process to proceed to S34. When the action setting is ON (S31: Yes), the presser foot 64 does not return to the separation position from the stitching of the stitch before the final stitch. CPU 16 maintains the presser foot 64 in the contact position (S32), causing the process to proceed to S34.

[0061] CPU 16 determines whether it is tangent timing T4 based on the detection result of encoder 55 (S34). If it is not tangent timing T4 (S34: No), CPU 16 remains in standby mode in S34 until tangent timing T4 is achieved. If it is tangent timing T4 (S34: Yes), CPU 16 drives the intermediate pressure foot motor 68, causing the intermediate pressure foot 64 to move towards the tangent position set in S2 (S36). Figure 10 As shown, when the presser foot 64 is in the tangential position, the lower end of the workpiece W is lower than the upper end of the needle plate 74. That is, a portion of the lower end of the workpiece W is located within the needle hole 75.

[0062] like Figure 8 As shown, the CPU 16 drives the tangent motor 113, causing the movable blade 112 of the tangent mechanism 110 to move to the cutting position, cutting the top thread M and the bottom thread L (S37). During cutting, the movable blade 112 causes its tip 116 to plunge into the loop of the top thread M, capturing the top thread M and the bottom thread L together. Figure 10 As shown, the thread-cutting mechanism 110 simultaneously cuts the top thread M on the workpiece W side of the thread loop in the bottom thread L and top thread M at position P. Since the presser foot 64 presses the workpiece W at the cutting position below the contact position, the thread-cutting mechanism 110 can cut the top thread M and bottom thread L remaining in the workpiece W in a way that makes the length of the remaining top thread M and bottom thread L shorter.

[0063] like Figure 8 As shown, when the needle bar 63, implemented by the needle bar mechanism 6, rises, the CPU 16 maintains the middle pressure foot 64 in the tangential position (S38). When the tangential mechanism 110 cuts the opposite thread M and the bottom thread L, the CPU 16 controls the middle pressure foot motor 68 to move the middle pressure foot 64 to the tangential position, and maintains the vertical position of the middle pressure foot 64 in the tangential position until the sweeping mechanism 130 finishes sweeping.

[0064] CPU16 determines whether it is the thread sweeping timing T5 based on the detection result of encoder 55 (S39). If it is not the thread sweeping timing T5 (S39: No), CPU16 remains in standby mode in S39 until the thread sweeping timing T5 is reached. If it is the thread sweeping timing T5 (S39: Yes), CPU16 drives cylinder 131 to move the thread sweeping rod 136 of the thread sweeping mechanism 130, performing thread sweeping to move the end of the top thread M cut by the thread cutting mechanism 110 upwards towards the upper part of the cylinder of the middle pressure foot 64 (S41). At the rising timing T6, CPU16 drives the middle pressure foot motor 68 to raise the middle pressure foot 64 to the separation position (S42). At the sewing completion timing T7, CPU16 stops the driving of the transport mechanism 9, the conveying mechanism 10, and the synchronization mechanism 31, completing the sewing (S43). CPU16 then ends the main processing.

[0065] As explained above, from the time the CPU16 begins sewing at least the number of stitches preceding the final stitch until the final stitch is completed, the presser foot 64 is not returned to the separation position, thereby suppressing the up-and-down movement of the workpiece W (S18, S26). Therefore, the bobbin thread L is not pulled up from below the needle plate 74 before being cut by the thread cutting mechanism 110, and will not entangle the top thread M during cutting. Thus, when cutting, the thread cutting mechanism 110 causes the tip 116 of the movable blade 112 to plunge into the loop of the top thread M, reliably capturing and cutting both the bobbin thread L and the top thread M on the workpiece W side.

[0066] When the CPU16 moves the presser foot 64 to the contact position during the stitch count preceding the final stitch, it does not return the presser foot 64 to the separation position. Therefore, as the workpiece W moves according to the point where the final stitch lands, it is pressed down by the presser foot 64 and does not wobble. Consequently, the bobbin thread L is not pulled up from below the needle plate 74 before being cut by the thread cutting mechanism 110, and it does not entangle with the top thread M during cutting. Thus, when cutting, the thread cutting mechanism 110 causes the tip 116 of the movable blade 112 to plunge into the loop of the top thread M, reliably capturing and cutting both the bobbin thread L and the top thread M on the workpiece W side.

[0067] With the presser foot 64 pressing down on the workpiece W, the thread cutting mechanism 110 cuts the top thread M and the bottom thread L below the needle plate 74. Therefore, the sewing device 1 can shorten the length of the top thread M and bottom thread L remaining on the workpiece W.

[0068] The sewing device 1 can set the contact position according to the input result input by the operator through the switch group 12, which can improve the convenience of the operator.

[0069] When sewing the stitch count preceding the final stitch, the CPU16 lowers the presser foot 64 to the contact position but does not return it to the separation position. Therefore, the CPU16 can easily perform the process of moving the presser foot 64 synchronously with the movement of the needle bar 63.

[0070] When the CPU16 lowers the presser foot 64 to the contact position during the stitch count preceding the final stitch, it does not return the presser foot 64 to the separation position until the top thread M and bottom thread L are cut. Therefore, compared to the process of moving the presser foot 64 to the contact position and separation position during sewing and cutting respectively, the drive control unit can easily control the movement of the presser foot 64.

[0071] When sewing the stitch count preceding the final stitch, the CPU16 lowers the presser foot 64 to the contact position and does not return it to the separation position until the sweeping of the thread M cut by the thread cutting mechanism 110 ends. Therefore, compared to the process of moving the presser foot 64 to the contact and separation positions during sewing, cutting, and sweeping respectively, the CPU16 can easily control the movement of the presser foot 64.

[0072] The sewing device 1 improves the operator's convenience by allowing the operator to set whether the CPU 16's actions are performed.

[0073] When the stitch length is shorter than a specified threshold, the bobbin thread L is easily pulled up from under the needle plate 74 if the workpiece W moves up and down, resulting in slack during cutting and potentially tangling with the top thread M. Therefore, when the stitch length is shorter than the threshold, the CPU 16 maintains the presser foot 64 in a contact position from the stitch count before the final stitch, thereby suppressing up and down movement of the workpiece W before cutting. Thus, the thread cutting mechanism 110 can reliably capture and cut the bobbin thread L and the top thread M on the workpiece W side together using the movable blade 112.

[0074] In the case of a short-stitch sewing operation, the bobbin thread L is easily pulled up from under the needle plate 74 when the workpiece W moves up and down, which may cause slack during cutting and potentially entangle the top thread M. Therefore, when the short-stitch sewing operation is added to the sewing control unit, the drive control unit maintains the presser foot 64 in the contact position from the stitch count before the last stitch, thereby suppressing the up-and-down movement of the workpiece W before cutting. As a result, the thread cutting mechanism 110 can reliably capture and cut the bobbin thread L and the top thread M on the workpiece W side together using the movable blade 112.

[0075] The sewing device 1 improves operator convenience by allowing the operator to set whether the CPU 16 adds sewing action for short stitches.

[0076] In the above embodiments, the pressure foot motor 68 is an example of the "drive source" of the present invention. The CPU 16 executing S18 and S26 is an example of the "drive control unit" of the present invention. The CPU 16 executing S2 is an example of the "position setting unit" of the present invention. The tangent position is an example of the "tangent contact position" of the present invention. The switch group 12 is an example of the "input unit" of the present invention. The CPU 16 performing action setting in S4 is an example of the "action setting unit" of the present invention. The CPU 16 performing S24 is an example of the "stitch length comparison unit" of the present invention. The CPU 16 performing S13 is an example of the "sewing control unit" of the present invention. The CPU 16 performing stitch setting in S4 is an example of the "sewing setting unit" of the present invention.

[0077] In addition to the embodiments described above, the sewing apparatus of the present invention can be modified in various ways. The type of sewing apparatus 1 can be appropriately changed to various industrial sewing machines, household sewing machines, etc. The sewing apparatus 1 may also omit the switch assembly 12, or it may replace the switch assembly 12 with other input units such as a touch panel.

[0078] The program containing instructions for performing the processing of the sewing device 1 can be stored in the storage device of the sewing device 1 before the program is executed by the sewing device 1. Therefore, the method of obtaining the program, the acquisition path, and the device for storing the program can be appropriately changed. For example, the program executed by the CPU 16 of the sewing device 1 can also be received from other devices via wired or wireless communication and stored in a storage device such as flash memory. Other devices include, for example, PCs and servers connected via a network.

[0079] Some or all of the processes performed by the sewing device 1 may also be performed by an electronic device (e.g., an ASIC) independent of the CPU 16. The processes performed by the sewing device 1 may also be distributed among multiple electronic devices (e.g., multiple CPUs). The order of the steps in the processes performed by the sewing device 1 can be changed, steps can be omitted, or additional steps can be added as needed. The scope of the invention also includes schemes where an operating system (OS) running on the sewing device 1 performs some or all of the processes via instructions from the CPU 16. For example, the following modifications may be appropriately applied to the above embodiments.

[0080] The sewing device 1 may omit or modify at least one of the processes S2, S3, and S4. Regarding the contact position during sewing, the position from the start of sewing to the number of stitches two before the final stitch and the position from the number of stitches one before the final stitch to the final stitch are the same position, but they can also be different positions. In this case, the workpiece W moves between the time of sewing the stitch one before the final stitch and the time of sewing the final stitch, so the contact position during the time of sewing the stitch one before the final stitch is preferably closer to the separation position than its previous contact position. Although the tangent position is included in the contact position, the tangent position and the contact position can also be the same position.

[0081] Although one example sets the contact position as a point downwards from the contact point between the presser foot 64 and the workpiece W, away from the thickness D1, the contact position can be appropriately set according to the thickness and material of the workpiece W. Similarly, although one example sets the contact position for thread cutting as a point downwards from the contact point between the presser foot 64 and the workpiece W, away from the thickness D1+D2, the thread cutting position can also be appropriately set according to the thickness and material of the workpiece W. Although one example sets the separation position as a point slightly above the upper surface of the workpiece W, with the lower end of the presser foot 64 above it, the separation position can be appropriately set according to the thickness of the workpiece W.

[0082] CPU16 controls the presser foot 64 to descend to the contact position during the stitch before the final stitch and prevents it from returning to the separation position until the stitching is completed. Not limited to this, CPU16 can also control the presser foot 64 to descend to the contact position during the stitching two stitches before the final stitch or during stitching up to the last stitch, maintaining it in the contact position until the final stitch. When the thread sweeping mechanism 130 sweeps the thread, CPU16 maintains the presser foot 64 in the tangent position, but it can also return it to the contact position; alternative contact positions can also be set for thread sweeping. CPU16 can also move the presser foot 64 to the tangent position and cause the tangent mechanism 110 to cut the top thread M and bottom thread L, then move the presser foot 64 to the separation position, and then move the presser foot 64 back to the tangent or contact position to perform thread sweeping by the thread sweeping mechanism 130.

[0083] Explanation of reference numerals in the attached figures

[0084] 1. Sewing device

[0085] 6. Needle bar mechanism

[0086] 12 switch groups

[0087] 16 CPU

[0088] 63 needle bar

[0089] 64 medium presser foot

[0090] 65 stitches

[0091] 68 Medium-pressure foot motor

[0092] 69 Medium pressure foot bar

[0093] 74 needle plate

[0094] 75 pinholes

[0095] 110 Tangent Mechanism

[0096] 130 line sweeping mechanism

[0097] L bottom line

[0098] M-line

[0099] W refers to the sewn item.

Claims

1. A sewing device, comprising: The needle bar extends vertically and allows a sewing needle to be mounted at the lower end. The needle bar mechanism allows the needle bar to move up and down. The middle pressure foot bar has a middle pressure foot at its lower end and extends in the vertical direction parallel to the needle bar; A needle plate having needle holes through which the sewing needles pass and for holding the workpiece to be sewn; and The thread-cutting mechanism cuts the top and bottom threads below the needle plate. The sewing device is characterized by having: A drive source causes the middle presser foot rod to move up and down, thereby moving the middle presser foot up and down between a contact position that contacts the sewn material and a separation position that is above the contact position; and The drive control unit controls the drive source to lower the middle presser foot to the contact position when sewing at least one stitch before the final stitch that cuts the top and bottom threads by the tangent mechanism, and prevents the middle presser foot from returning to the separation position until the final stitch is completed.

2. The sewing device according to claim 1, characterized in that, It also includes a position setting unit for setting the contact position and the separation position of the middle pressure foot. The drive control unit controls the drive source to position the presser foot at the set contact position during the sewing of the stitch before the final stitch and during the sewing of the final stitch, respectively, and does not control the presser foot to return to the set separation position after these sewing operations.

3. The sewing device according to claim 2, characterized in that, The position setting unit can set the position of the middle presser foot during the operation of the thread-cutting mechanism to a thread-cutting contact position, which is a position different from the contact position between the middle presser foot and the workpiece. The drive control unit controls the drive source so that when the tangent mechanism starts to operate, the presser foot moves from the contact position where the presser foot contacts the workpiece during the final needle's sewing to the set tangent contact position.

4. The sewing device according to claim 2 or 3, characterized in that, It also has an input section. The position setting unit sets the input result of the input unit to the contact position where the middle presser foot contacts the sewn material.

5. The sewing device according to claim 1, characterized in that, When sewing a number of stitches preceding the final stitch, the drive control unit synchronously controls the descent of the middle presser foot towards the contact position, in sync with the descent of the needle bar achieved by the needle bar mechanism. When the needle bar is raised by the needle bar mechanism, the drive control unit does not control the middle presser foot to rise to the separation position, and maintains the middle presser foot in the contact position until the final needle sewing is completed.

6. The sewing device according to claim 5, characterized in that, When the drive control unit controls the drive source to position the middle presser foot in the contact position during sewing of the stitch number preceding the final stitch, it does not control the middle presser foot to rise to the separation position until the cutting mechanism finishes cutting the top thread and the bottom thread, thus maintaining the upper and lower positions of the middle presser foot at the contact position.

7. The sewing device according to claim 5, characterized in that, It also includes a wire-sweeping mechanism that moves the end of the face wire cut by the tangent mechanism upward toward the middle pressure foot. When the drive control unit controls the drive source to position the middle presser foot in the contact position during sewing of the stitch number preceding the final stitch, it does not control the middle presser foot to rise to the separation position until the thread sweeping mechanism finishes sweeping the thread, thus maintaining the upper and lower positions of the middle presser foot at the contact position.

8. The sewing device according to any one of claims 1 to 3, characterized in that, It has an action setting unit that sets whether to execute the operation of the drive control unit. The drive control unit controls the position of the middle pressure foot according to the settings of the action setting unit.

9. The sewing device according to claim 8, characterized in that, The system includes a stitch length comparison unit that compares the stitch length between the stitch landing point of the stitch preceding the final stitch and the stitch landing point of the final stitch with a predetermined threshold. When the stitch length is less than the threshold, the action setting unit is set to execute the action of the drive control unit.

10. The sewing device according to any one of claims 1 to 3, characterized in that, It has a sewing control unit that, immediately before the final stitch specified in the sewing data is made, divides the normally sewn stitch length into two short stitches, and adds a stitch to the sewing action used to add a new stitch between the stitch point of the previous stitch and the stitch point of the final stitch. The sewing control unit controls the position of the presser foot when sewing an additional stitch as part of the short stitch, or when sewing the stitch count before the final stitch.

11. The sewing device according to claim 10, characterized in that, It has a sewing setting unit that sets whether to perform the additional sewing action of the short stitch by the sewing control unit. The sewing control unit performs sewing actions according to the settings of the sewing setting unit.

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