sewing machine

Abstract

Sewing machine (10) with a needle hole (15) formed in a needle plate (17) or in a feed dog (14), comprising: a lower thread insertion mechanism comprising an air blowing mechanism (40) which introduces a sewing start end of a lower thread (D) from an underside of the stitch plate (17) into the needle hole (15) by means of air; a sewing start end holding mechanism (50, 50A) which holds the sewing start end of the inserted lower thread (D) above the stitch plate (17); a first thread cutting device (60) which cuts the sewing start end of the lower thread (D) held by the sewing start end holding mechanism (50, 50A); and a control device (110) which controls operations of the sewing machine (10).

Description

BACKGROUND OF THE INVENTIONField of the invention

[0001] The present invention relates to a sewing machine with a thread cutting device. State of the art

[0002] A prior art sewing machine includes an upper thread catching mechanism which catches a sewing start end of an upper thread from a sewing needle making a stitching point of a first stitch below a needle plate using a catching member, and which releases the sewing start end of the upper thread after the stitching point of several stitches, and prevents occurrence of a sewing error due to deviation of the sewing start end of the upper thread from the stitching point position of the first stitch by lifting a thread take-up lever.

[0003] The catching member of the catching mechanism includes opposing surfaces which can be brought into contact with and separated from each other, carries out a stitching point of a needle between the facing surfaces, closes the facing surfaces to catch the sewing start end of the upper thread when the sewing start end of the upper thread is pulled out downward by an edge of a shuttle.

[0004] However, when the sewing start end of the upper thread is caught in this way, the sewing start end of the upper thread hangs long from the stitch point position of the first stitch on the back of a sewing material.

[0005] Therefore, in the prior art upper thread catching mechanism, a holding force of the facing surfaces of the catching member after the stitching point of the first stitch is reduced more than in a normal state, and the sewing start end of the upper thread is caused to slide such that the sewing start end of the upper thread is not completely pulled out of the catching member by lifting the thread take-up lever, thereby adjusting the holding force to reduce the catching length (see, for example, JP 2006-320365 A).

[0006] A buttonhole sewing machine is known from DE 102 15 011 B4. A method and device for a sewing machine for cutting a thread are described in JP H09-299 663 A. JP H07-52 700 Y2 discloses a sewing machine. SUMMARY OF THE INVENTION

[0007] Although the state-of-the-art sewing machine considers shortening the sewing start end of the upper thread, the sewing start end of the bobbin thread still remains and hangs long from the fabric, resulting in a deterioration in sewing quality. To improve sewing quality, the sewing start end of the bobbin thread must be manually trimmed after sewing is completed, resulting in increased workload.

[0008] It is an object of the present invention to make a sewing start end of a bobbin thread remaining on a sewing material shorter. (1) In a sewing machine according to the present invention, a needle hole is formed in a throat plate or in a feed dog. The sewing machine includes a lower thread insertion mechanism, a sewing start end holding mechanism, a first thread cutting device, and a control device. The lower thread insertion mechanism includes an air blowing mechanism that inserts a sewing start end of a lower thread into the needle hole from a lower surface of the throat plate by air. The sewing start end holding mechanism holds the sewing start end of the inserted lower thread above the throat plate. The first thread cutting device cuts the sewing start end of the lower thread held by the sewing start end holding mechanism. The control device controls operations of the sewing machine. (2) In the sewing machine according to (1), the air-blowing mechanism includes a nozzle that ejects air toward the needle hole. At a tip of the nozzle, the nozzle has a slit. The slit is designed to guide and hold the sewing-start end of the bobbin thread. (3) In the sewing machine according to (1) or (2), the sewing start end holding mechanism comprises a slide plate having an upper thread catching hole and a lower thread catching hole. The upper thread catching hole and the lower thread catching hole are arranged in a sliding direction. The upper thread catching hole and the lower thread catching hole are configured to clamp and hold the sewing start end of the lower thread and a sewing start end of an upper thread between the slide plate and a facing surface of the throat plate. The slide plate is movable to an upper thread insertion position, a lower thread insertion position, and a run-out position. In the upper thread insertion position, the upper thread catching hole is superimposed on the needle hole. In the lower thread insertion position, the lower thread catching hole is superimposed on the needle hole. In the run-out position, both the lower thread catching hole and the upper thread catching hole are separated from the needle hole. (4) In the sewing machine according to (3), the sliding plate clamps and holds the sewing start end of the upper thread and the sewing start end of the lower thread between the sliding plate and the facing surface of the throat plate in the run-out position.The control device controls the sewing machine to: arrange the slide plate in the bobbin thread insertion position before a stitching point of a first stitch, insert the sewing start end of the bobbin thread into the needle hole and the bobbin thread catching hole from the underside by using the air blowing mechanism, arrange the slide plate in the upper thread insertion position after inserting the sewing start end of the bobbin thread, insert the sewing start end of the upper thread into the needle hole and the upper thread catching hole through the stitching point of the first stitch, arrange the slide plate in the run-out position after inserting the sewing start end of the upper thread, and cut the sewing start end of the upper thread and the sewing start end of the bobbin thread by using the first thread cutting device at and after a stitching point of a second stitch. (5) In the sewing machine according to (3) or (4), a knife of the first thread cutting device is arranged below the sliding plate. The sewing machine further comprises a thread pulling mechanism. The thread pulling mechanism performs a downward movement when the sliding plate is arranged in the run-out position, pulls the sewing start end of the upper thread and the sewing start end of the lower thread, which are pulled out by the sliding plate, and engages the sewing start end of the upper thread and the sewing start end of the lower thread with the first thread cutting device. The control device controls the sewing machine to cut the sewing start end of the upper thread and the sewing start end of the lower thread by using the first thread cutting device after the thread pulling mechanism moves downward. (6) The sewing machine according to any one of (3) to (5) further comprises a second thread cutting device. The second thread cutting device cuts the lower thread upon completion of a first sewing operation and holds an end of the cut lower thread on a shuttle side as a sewing start end for a second sewing operation following the first sewing operation. The lower thread insertion mechanism includes a holding release mechanism and a thread handling mechanism. The holding release mechanism releases a holding state of the sewing start end of the lower thread held by the second thread cutting device. The thread handling mechanism draws the sewing start end of the lower thread to the bottom of the needle hole. (7) In the sewing machine according to (6), the thread handling mechanism includes a thread handling member that pulls the sewing start end of the lower thread to the bottom of the needle hole by a forward movement of the thread handling member. The thread handling member includes a first inclined portion, a concave portion, and a second inclined portion. The first inclined portion is formed at a tip of the thread handling member to move the sewing start end of the lower thread upward. The concave portion is formed in an upper part of the tip to catch the sewing start end of the lower thread. The second inclined portion is formed inside the concave portion to move the sewing start end of the lower thread downward. An upper end of the second inclined portion is higher than an upper end of the first inclined portion. (8) In the sewing machine according to (6) or (7), before inserting the sewing start end of the lower thread into the needle hole and the lower thread catching hole by using the air blowing mechanism, the sewing machine is controlled by the control device to drive the thread handling mechanism to pull the sewing start end of the lower thread to the bottom of the needle hole, and to drive the holding release mechanism to release the holding state of the sewing start end of the lower thread held by the second thread cutting device.

[0009] In the sewing machine according to the present invention, a sewing start end of a bobbin thread is blown upward from the bottom side and inserted into the needle hole by the bobbin thread insertion mechanism, the sewing start end of the bobbin thread is held above the throat plate by the sewing start end holding mechanism, and the held sewing start end of the bobbin thread is cut by the first thread cutting device. Accordingly, it is possible to cut a sewing start end of a bobbin thread from a fabric without using a manual operation and to shorten the sewing start end of the bobbin thread remaining in the fabric, thereby achieving an improvement in sewing quality. Since no manual operation is required, it is possible to reduce a workload of an operation for cutting a sewing start end of a bobbin thread. BRIEF DESCRIPTION OF THE CHARACTERS Fig. 1 is a side view showing a configuration around a needle in a mechanical feed sewing machine. Fig. 2 is a plan view of an end opposite to a stand body portion of a bed of the sewing machine. Fig. 3 is a block diagram showing a control system of the sewing machine. Fig. 4 is a side view showing a configuration in the vicinity of a horizontal shuttle. Fig. 5 is a perspective view of a thread handling mechanism. Fig. 6 is a plan view of a thread handling mechanism. Fig. 7A is an enlarged plan view showing positions before and after operation of a thread handling hook when a bobbin thread is arranged at a low position, and Fig. 7B is an enlarged plan view showing positions before and after operation of the thread handling hook when a bobbin thread is arranged at a high position. Fig. 8 is a perspective view showing a state in which a nozzle of an air blowing mechanism moves backward and showing a configuration in the vicinity of a horizontal shuttle. Fig. 9 is a perspective view showing a state in which a nozzle of an air blowing mechanism moves forward and showing a configuration in the vicinity of a horizontal shuttle. Fig. 10 is a perspective view of a flat nozzle. Fig. 11 is a cross-sectional view of the flat nozzle. Fig. 12 is a perspective view of a ring nozzle. Fig. 13 is a cross-sectional view of the ring nozzle. Fig. 14 is a plan view of a throat plate. Fig. 15 is a perspective view of the vicinity of the throat plate, showing an operation of cutting sewing start ends of a lower thread and an upper thread. Fig. 16 is a perspective view of the vicinity of the throat plate, showing the operation of cutting sewing start ends of a lower thread and an upper thread and Fig. 15 connects. Fig. 17 is a perspective view of the vicinity of the throat plate, showing the operation of cutting sewing start ends of a lower thread and an upper thread and Fig. 16 connects. Fig. 18 is a perspective view of the vicinity of the throat plate, showing the operation of cutting sewing start ends of a lower thread and an upper thread and Fig. 17 connects. Fig. 19 is a perspective view of the vicinity of the throat plate, showing the operation of cutting sewing start ends of a lower thread and an upper thread and Fig. 18 connects. Fig. 20 is a perspective view of the vicinity of the throat plate, showing the operation of cutting sewing start ends of a lower thread and an upper thread and Fig. 19 connects. Fig. 21 is a perspective view of a first thread cutting device. Fig. 22 is a perspective view showing a thread cutting operation using a movable knife and a fixed knife of the first thread cutting device. Fig. Fig. 23 is a perspective view showing the thread cutting operation using the movable knife and the fixed knife of the first thread cutting device and Fig. 22 connects. Fig. Fig. 24 is a perspective view showing the thread cutting operation using the movable knife and the fixed knife of the first thread cutting device and Fig. 23 connects. Fig. 25 is a side view showing the thread cutting operation using the movable knife and the fixed knife of the first thread cutting device. Fig. 26A is an operation diagram showing an operation of cutting sewing start ends of a lower thread and an upper thread, Fig. 26B is an operational diagram shown at Fig. 26A, and Fig. 26C is an operational diagram attached to Fig. 26B connects. Fig. 27A is an operation diagram showing an operation of cutting sewing start ends of the lower thread and the upper thread and Fig. 26C connects, Fig. 27B is an operational diagram attached to Fig. 27A, and Fig. 27C is an operational diagram attached to Fig. 27B connects. Fig. 28A is an operation diagram showing an operation of cutting sewing start ends of the lower thread and the upper thread and Fig. 27C connects, Fig. 28B is an operational diagram attached to Fig. 28A, and Fig. 28C is an operational diagram attached to Fig. 28B connects. Fig. 29 is an operation diagram showing an operation of cutting sewing start ends of the lower thread and the upper thread and Fig. 28C. Fig. 30 is a flowchart showing a control flow of the operation of cutting the sewing start ends of the lower thread and the upper thread. Fig. 31 is a perspective view showing another example of a thread pulling mechanism. Fig. 32 is a plan view showing another example of a sewing start end holding mechanism. Fig. 33 is a perspective view showing another example of the sewing start end holding mechanism. Fig. 34 is a perspective view showing a regulating plate of a thread pulling member. DETAILED DESCRIPTIONOverview of the sewing machine

[0010] In the following, a sewing machine 10 according to the present invention will be described with reference to the accompanying drawings. As shown in Fig. 1, the sewing machine 10 is a so-called mechanical feed sewing machine, comprising a needle bar and a sewing needle 11 (see Fig. 18) which moves upwards and downwards and swings forwards and backwards in a material feed direction, a feed foot 12 which moves upwards and downwards and swings forwards and backwards in synchronism with the needle bar, a presser foot 13 which moves alternately upwards and backwards with the feed foot 12, and a feed dog 14 which moves periodically in the feed direction in synchronism with the needle bar.

[0011] That is, in the mechanical feed sewing machine, a through hole 12a through which the sewing needle 11 passes is formed in the feed foot 12, and a needle hole 15 through which the sewing needle 11 passes is formed in the feed dog 14.

[0012] As the sewing needle 11 and the feed foot 12 move downward, the feed dog 14 moves upward, and these move toward the front in the fabric feed direction. Accordingly, a fabric is clamped by the feed foot 12 and the feed dog 14, pierced by the sewing needle 11, and transported toward the front in the fabric feed direction.

[0013] When the sewing needle 11 and the feeding foot 12 move upward, the presser foot 13 moves downward, the sewing needle 11 and the feeding foot 12 move backward while the presser foot 13 presses the fabric, and a stitch point is executed while the fabric is fed again.

[0014] In the mechanical feed sewing machine, the needle hole 15 is formed in the feed dog 14, which moves in a circumferential movement, and the position of the needle hole 15 changes with the circumferential movement of the feed dog 14; however, the following description of the relative positional relationship to the needle hole 15 is based on the premise that the position of the needle hole 15 is the position where the feed dog 14 is located at an arm shaft angle of 0° (a top dead center of the needle bar).

[0015] The sewing machine 10 includes elements commonly included in a mechanical feed sewing machine, such as a needle bar up / down movement mechanism, a fabric feed mechanism, a shuttle drive mechanism, a thread tension trough, and a thread take-up lever; however, these elements are well known, and therefore, a detailed description thereof will be omitted.

[0016] In the following description, in a state where the sewing machine 10 is placed on a horizontal plane, the vertical upper side is defined as "top", the vertical lower side is defined as "bottom", the downstream side in the fabric feeding direction is defined as "front", the upstream side in the fabric feeding direction (operator side) is defined as "rear", the left side in a forward-facing state is defined as "left", and the right side in the forward-facing state is defined as "right".

[0017] Fig. 2 is a plan view of an end located on the opposite side (the left side) from the stand body portion side of a bed 16 of the sewing machine 10, with a top cover and some internal members not shown therein. Fig. Figure 3 is a block diagram illustrating the overall configuration of the sewing machine.

[0018] As shown in the figures, the sewing machine 10 comprises a needle plate 17 arranged on a sewing bed 16, a horizontal shuttle 18 arranged on the lower right side of the needle plate 17, a bobbin thread insertion mechanism 2 which inserts a sewing start end of a bobbin thread into the needle hole 15 from below, a sewing start end holding mechanism 50 which holds the sewing start ends of a bobbin thread passing through the needle hole 15 and an upper thread above the needle plate 17, a first thread cutting device 60 which cuts the sewing start end of the bobbin thread held by the sewing start end holding mechanism 50, a second thread cutting device 70 which cuts a bobbin thread consumed during sewing and holds an end of the cut bobbin thread on the shuttle side as a sewing start end for the next sewing operation, a thread pulling mechanism 80 which pulls the sewing start ends of the upper thread and the bobbin thread,which are pulled downwards by a sliding plate 51 of the sewing start end holding mechanism 50 in a sliding direction, a catching mechanism 19 which catches cut pieces of the lower thread and the upper thread cut by the first thread cutting device 60, and a control device 110 which controls the units of the sewing machine 10.

[0019] The lower thread insertion mechanism 2 includes a holding release mechanism 20 that releases the holding state of the sewing start end of the bobbin thread by the second thread cutting device 70, a thread handling mechanism 30 that pulls the sewing start end of the lower thread to the bottom of the needle hole 15, and an air blowing mechanism 40 that inserts the sewing start end of the bobbin thread, whose holding state is released, into the needle hole 15 using air.

[0020] As described above, the sewing machine 10 includes a needle up / down movement mechanism that causes the needle bar and the sewing needle 11 to move up and down and swing forward and backward, a press up / down movement mechanism that causes the feeding foot 12 and the presser foot 13 to move up and down alternately, a fabric feeding mechanism that causes the feed dog 14 to protrude and retract through the opening of the needle plate 17 and feeds a fabric forward and backward, and a shuttle mechanism that drives the horizontal shuttle 18 to rotate at twice the up and down movement speed of the sewing needle 11, these mechanisms using a sewing motor as a common drive source.

[0021] The above-mentioned elements are described one after the other below.

[0022] Second thread cutting device Fig. Fig. 4 is a side view showing the configuration in the vicinity of the horizontal shuttle 18, and Fig. 8 is a perspective view of this. As shown in the Fig. 2 to 4 and in Fig. As shown in Fig. 8, the second thread cutting device 70 is arranged at a position lower than the throat plate 17 and toward the front of the needle hole 15. The second thread cutting device 70 includes a hook-shaped movable knife 71, a fixed knife 72 fixed to a sewing frame, and a leaf spring 73 that presses the movable knife 71 against the fixed knife 72.

[0023] The second thread cutting device 70 catches and cuts the upper thread and lower thread hanging from the needle hole 15 to the horizontal shuttle 18 after the stitch point of the last stitch, and holds one end of the cut lower thread. The lower thread end serves as the sewing start end for the next sewing operation.

[0024] The movable knife 71 is long in the front-rear direction, is connected to a second thread cutting solenoid 74 via a linkage in a state where the tip faces the rear side, and performs a reciprocating movement including a movement toward the rear side while catching an upper thread and a lower thread and a movement toward the front side to the lower position by the second thread cutting solenoid 74.

[0025] Accordingly, the tip of the movable knife 71 has a sharp-pointed shape, wherein a hook-shaped beveled portion is formed near the tip and a cutting edge directed toward the front is formed inside the beveled portion.

[0026] The fixed knife 72 is arranged above the movable knife 71, and its lower surface comes into sliding contact with the upper surface of the movable knife 71. The fixed knife 72 has a cantilevered shape extending toward the rear, and a rear-facing cutting edge is formed at its tip. Accordingly, the upper thread and the lower thread, which are caught by the chamfered portion of the movable knife 71 in an outward path of the reciprocating movement, are clamped and cut by the cutting edge of the movable knife 71 and the cutting edge of the fixed knife 72 in a return path of the reciprocating movement.

[0027] Since the leaf spring 73 presses the movable blade 71 from the bottom to the top, the movable blade 71 can be pressed against the fixed blade 72 and a gap can be prevented from forming between them, thereby enabling reliable cutting.

[0028] By the leaf spring 73, the end of the cut bobbin thread on the shuttle side (the sewing start end for the next sewing operation) can be clamped and held between the movable knife 71 and the leaf spring 73, and thus it is possible to clarify the position of the sewing start end of the bobbin thread. Thread handling mechanism

[0029] The thread handling mechanism 30 has a function of guiding a sewing start end of a lower thread to an appropriate position such that the air blowing mechanism 40 inserts the sewing start end upward into the needle hole 15, and a function of unwinding the lower thread from a bobbin in the horizontal shuttle 18 by an appropriate length.

[0030] Fig. 5 is a perspective view of the thread handling mechanism 30, Fig. Fig. 6 is an enlarged plan view showing positions of the thread handling mechanism before and after operation of a thread handling hook 31 to be described later, and Fig. 7 is a diagram showing the behavior of the bobbin thread at the tip of the thread handling hook 31. As shown in the Fig. 2 and Fig. 5, the thread handling mechanism 30 is arranged at a position lower than the throat plate 17 and slightly to the left, toward the rear, of the needle hole 15.

[0031] The thread handling mechanism 30 includes a thread handling hook 31 as a thread handling member that catches the sewing start end of the lower thread hanging from the horizontal shuttle 18 to the second thread cutting device 70 by a forward and backward movement, a first thread handling air cylinder 32 that causes the thread handling hook 31 to move forward and backward, a support plate 33 that supports the thread handling mechanism 30 as a whole, a support member 34 that allows the first thread handling air cylinder 32 to slide in a predetermined direction over the support plate 33, and a second thread handling air cylinder 35 that causes the first thread handling air cylinder 32 to reciprocate in the predetermined direction relative to the support plate 33.

[0032] The support plate 33 is configured to be horizontally mounted on the sewing bed 16 and has a slotted hole 331 formed therein, which guides the forward and backward movement direction of the first thread-handling air cylinder 32. The slotted hole 331 is formed obliquely forward to the right, and when the first thread-handling air cylinder 32 is ejected by the second thread-handling air cylinder 35, the first thread-handling air cylinder 32 performs a forward movement in a right-inclusive direction.

[0033] The support member 34 includes a slider (not shown) which slides in the elongated hole 331, and a holding plate which holds the first thread handling air cylinder 32 so that it does not fall off at the rear of the support plate 33, and the first thread handling air cylinder 32 is connected to the support plate 33 to perform a forward and backward movement.

[0034] The first thread handling air cylinder 32 supported by the support plate 33 is maintained in a state where the forward / backward movement direction of a piston matches the length direction of the thread handling hook 31, and the forward / backward movement direction of the piston is an obliquely forward right direction having a rightward component smaller than that of the elongated hole 331.

[0035] The obliquely forward rightward movement of the thread handling hook 31 takes place in two steps starting from the run-out position by the first and second thread handling air cylinders 32 and 35.

[0036] The thread handling hook 31 and the bobbin thread, which are in Fig. 6 are shown with a solid line show the positions in a state where both the first and second thread handling air cylinders 32 and 35 are caused to move forward, and the thread handling hook 31 and the lower thread, which are indicated by a two-dot long dash line, show the positions in a state where only the second thread handling air cylinder 35 is caused to move backward in the state where both the first and second thread handling air cylinders 32 and 35 are caused to move forward.

[0037] By causing the thread handling hook 31 to move forward the furthest, its tip comes to a position where the thread handling hook 31 crosses the bobbin thread hanging from the horizontal shuttle 18 to the second thread cutting device 70.

[0038] By causing only the second thread handling air cylinder 35 to move backward in the state where both the first and second thread handling air cylinders 32 and 35 move forward, the lower thread hanging from the horizontal shuttle 18 to the second thread cutting device 70 can be brought close to the path extending between the tip of the nozzle 41 of the air blowing mechanism 40 and the needle hole 15.

[0039] As in Fig. 7, the tip of the thread handling hook 31 includes a first inclined portion 311 formed at the tip thereof for causing the sewing start end of the bobbin thread to move upward, a concave portion 312 formed in the upper part of the tip thereof for catching the sewing start end of the lower thread, a second inclined portion 313 formed at the rear end (opposite the tip) inside the concave portion 312 for causing the sewing start end of the lower thread to move downward, and a third inclined portion 314 facing the second inclined portion 313 inside the concave portion 312, and is formed such that the upper end of the second inclined portion 313 is higher than the upper end of the first inclined portion 311.

[0040] The first inclined portion 311 has an acute angle as indicated by an inclination angle θ1, is inclined upwardly rearwardly, and can push upward the lower thread that comes into contact with the first inclined portion 311 at the time of forward movement of the thread handling hook 31.

[0041] The second inclined portion 313 has an obtuse angle as indicated by an inclination angle θ2 and is inclined downwardly rearwardly, and the upper end of the second inclined portion 313 is higher than the upper end of the first inclined portion 311. Accordingly, at the time of forward movement of the thread handling hook 31, it is possible to lower and guide the lower thread pushed up from the first inclined portion 311 into the concave portion 312.

[0042] The third inclined portion 314 has an obtuse angle as indicated by an inclination angle θ3 and is inclined downwardly rearward, and its upper end has the same height as the first inclined portion 311. Accordingly, at the time of backward movement of the thread handling hook 31, it is possible to catch the lower thread guided into the concave portion 312 and prevent the lower thread from inadvertently coming out of the concave portion 312.

[0043] By using this structure, the thread handling hook 31 can bring the lower thread into contact with the first inclined portion 311 and push the lower thread upward by moving the thread handling hook 31 forward and catch the lower thread via the second inclined portion 313 and guide it into the concave portion 312 as shown in Fig. 7A, when the lower thread is positioned lower than the upper end of the first inclined portion 311. When the thread handling hook 31 is caused to perform a reverse movement, the lower thread in the concave portion 312 is caught and held by the third inclined portion 314 so as not to come out of the concave portion 312. The lower thread in the concave portion 312 is blown upward by the air blowing mechanism to be described later, but at this time, it moves along the third inclined portion 314, thus not disturbing the movement.

[0044] When the lower thread is arranged at a position higher than the upper end of the first inclined portion 311 but lower than the upper end of the second inclined portion 313, the lower thread can be brought into direct contact with the second inclined portion 313 and guided into the concave portion 312 by a forward movement of the thread handling hook 31, as shown in Fig. 7B. The behavior of the lower thread at the time of the backward movement of the thread handling hook 31 is the same as in Fig. 7A shown. Air blowing mechanism

[0045] Fig. Fig. 8 is a perspective view showing a state in which the nozzle 41 of the air blowing mechanism 40 moves backward, and Fig. 9 is a perspective view showing a state in which the nozzle 41 of the air blowing mechanism 40 moves forward.

[0046] As shown in the figures, the air blowing mechanism 40 comprises a nozzle 41 from the tip of which air is ejected from a position below the needle hole 15 toward the needle hole 15, a nozzle holding portion 43 which detachably holds the nozzle 41 and is connected to an air supply source (for example, a compressor), a nozzle lifting air cylinder 44 which causes the nozzle 41 to move forward and backward via the nozzle holding portion 43, and a switching valve 45 (see Fig. 3), which switches the supply and interruption of air from the air supply source to the nozzle holding portion 43.

[0047] The nozzle holding portion 43 includes a tubular nozzle insertion portion 431 and a frame portion 432 connecting the nozzle insertion portion 431 to the piston of the nozzle lifting air cylinder 44.

[0048] The nozzle insertion portion 431 can insert the nozzle 41 therein and fix the nozzle 41 thereto with a screw. By loosening the screw, the nozzle 41 can be easily removed, and a ring nozzle 42, which will be described later, can also be used instead of a flat nozzle 41.

[0049] The nozzle holding area 43 is connected to an air supply hose and enables the supplied air to expel air from the tip of the nozzle 41.

[0050] The nozzle 41 held by the nozzle holding portion 43 is directed obliquely upward toward the front. The piston of the nozzle lifting air cylinder 44 can cause the nozzle 41 to move forward and backward in the same direction as the length direction of the nozzle 41. As shown in Fig. 9, in the state where the piston of the nozzle lifting air cylinder 44 makes a forward movement, the tip of the nozzle 41 can be brought to a position almost just below the needle hole 15.

[0051] As in the Fig. 10 and Fig. As shown in FIG. 11, the nozzle 41 has a flat opening extending substantially in the right-left direction and capable of forcing and blowing out air at a high speed. A slit 411 is formed centrally in the width direction of the tip of the nozzle 41, which slit can receive the sewing start end of the bobbin thread at the time of forward movement of the nozzle 41. That is, the air blowing mechanism 40 is arranged such that the sewing start end of the bobbin thread, which is brought close to the thread handling hook 31 of the thread handling mechanism 30, is received in the slit 411 at the time of forward movement of the nozzle 41.

[0052] The nozzle 41 can be replaced by the ring nozzle 42, which is Fig. 12 and Fig. 13. The annular nozzle 42 has a slot 421 formed at its tip for receiving the bobbin thread therein.

[0053] The ring nozzle 42 has a wider opening and can therefore blow out air over a wider area. Holding release mechanism

[0054] As in the Fig. 4 and Fig. 8, the holding release mechanism 20 includes a locking member 21 that locks the leaf spring 73 of the second thread cutting device 70, and a release air cylinder 22 that raises and lowers the locking member 21.

[0055] The locking member 21 is arranged vertically, and its upper end is bent vertically to the right. The bent portion 211 of the upper end of the locking member 21 is configured to face the surface of an intermediate portion in the longitudinal direction of the leaf spring 73 from above.

[0056] The release air cylinder 22 can drive the locking member 21, in which the bent portion 211 is in the position closely facing the upper surface of the leaf spring 73, to a downward movement and can pull the leaf spring 73 downward via the locking member 21.

[0057] By this downward pulling, the tip of the leaf spring 73 is separated from the movable knife 71 and releases the sewing start end of the bobbin thread clamped between the movable knife 71 and the leaf spring. Needle plate

[0058] Fig. 14 is a plan view of the throat plate 17. The throat plate 17 is a rectangular flat plate which is adapted to be horizontally mounted on the upper surface of the sewing bed 16 and which is arranged such that the long side direction is parallel to the front-back direction.

[0059] A rectangular opening 171, through which the feed dog 14 protrudes or recedes, is formed in the center of the upper surface of the throat plate 17. Extending from the opening 171 is a through-hole 172 in which the movable knife 61 and the fixed knife 62 of the first thread cutting device 60 and the thread pulling member 81 are arranged. The opening and the through-hole are designed to penetrate the throat plate 17 vertically.

[0060] At the front of the opening 171, a guide groove 173 of the slide plate 51 of the sewing start end holding mechanism 50, which will be described later, is formed continuously from the opening 171. The guide groove 173 has the same lateral width as the opening 171. Sewing start stop mechanism

[0061] The sewing start end holding mechanism 50 comprises a sliding plate 51 (see Fig. 15 to 20), in which a first opening 511 and a second opening 512 are formed as an upper thread catching hole and a lower thread catching hole for holding sewing start ends of an upper thread and a lower thread, a first thread holding air cylinder 52 which causes the sliding plate 51 to move forward and backward, and a second thread holding air cylinder 53 (see Fig. 3), which causes the sliding plate 51 and the first thread holding air cylinder 52 to move forward and backward.

[0062] The slide plate 51 is a long, flat plate extending linearly and disposed in the front-to-back direction in the guide groove 173 of the needle plate 17. The first opening 511, which holds the sewing start end of the upper thread, is configured to penetrate the rear end of the slide plate 51, and the second opening 512, which holds the sewing start end of the lower thread, is configured to penetrate the position slightly forward of the rear end.

[0063] The slide plate 51 positions the first or second opening 511 or 512 immediately above the needle hole 15 by a forward and backward movement, and clamps and holds the sewing start end of the lower thread D or the upper thread U between the lower surface of the slide plate 51 and the inner surface of the guide groove 173 of the throat plate 17 by a forward movement after inserting the sewing start end of the lower thread or the upper thread thereinto.

[0064] The slide plate 51 passes the sewing start end of the lower thread D which is drawn by the air blowing mechanism 40 at a lower thread insertion position at which the second opening 512 is positioned relative to the needle hole 15 ( Fig. 16), is blown upwards, and moves from this state to an upper thread insertion position in which the first opening 511 is positioned relative to the needle hole 15 ( Fig. 19). In the upper thread insertion position, the sewing start end of the lower thread D is clamped and held between the slide plate 51 and the needle plate 17, and the sewing start end of the upper thread U can be inserted through it. After inserting the upper thread U through the opening, the slide plate 51 moves further forward to the run-out position, and the sewing start ends of the lower thread D and the upper thread U are held between the slide plate 51 and the needle plate 17 ( Fig. 20).

[0065] Accordingly, the slide plate 51 must position three positions: the lower thread insertion position, the upper thread insertion position and the run-out position.

[0066] In the first thread holding air cylinder 52, the slide plate 51 is directly connected to the piston thereof, and it causes the slide plate 51 to move between the lower thread insertion position and the upper thread insertion position.

[0067] In the second thread holding air cylinder 53, the body of the first thread holding air cylinder 52 is directly connected to the piston thereof, and it causes the slide plate 51 and the first thread holding air cylinder 52 to move between the upper thread insertion position and the run-out position.

[0068] The first thread holding air cylinder 52 may be supported in the sewing bed 16 by a sliding guide or the like movable in the front-back direction. First thread cutting device

[0069] Fig. 21 is a perspective view of the first thread cutting device 60, Fig. 22 to 24 are perspective views of the movable knife 61 and the fixed knife 62 of the first thread cutting device 60.

[0070] The first thread cutting device 60 comprises a movable knife 61 which is long in the right-left direction and has a right-facing edge at its right end, a fixed knife 62 which is long in the right-left direction and has a hook-shaped portion 621 at its right end, and a first thread cutting air cylinder 63 (see Fig. 3), which causes the movable knife 61 to move back and forth in the right-left direction.

[0071] The movable knife 61 has a tip edge that is flat in the front-to-back direction and is superimposed on the fixed knife 62. The base end of the movable knife 61 is fixed to a support plate 64, which is attached to the piston of the first thread-cutting air cylinder 63.

[0072] The movable knife 61 is arranged on the left side of the sliding plate 51 at the time of non-cutting, and the fixed knife 62 is arranged in the opening 172 of the throat plate 17, and at the time of cutting, it moves to the right and passes under the sliding plate 51.

[0073] The fixed knife 62 has a left-facing edge formed inside the hook-shaped portion 621 at the right end thereof, and clamps and cuts the lower thread and the upper thread entering the hook-shaped portion 621 between the edge of the fixed knife 62 and the edge of the movable knife 61.

[0074] The fixed knife 62 extends to the right of the movable knife 61 at the time of non-cutting and is arranged to pass under the sliding plate 51. Thread pulling mechanism

[0075] As in Fig. 22 to 25, the thread pulling mechanism 80 comprises a thread pulling member 81 which catches the sewing start ends of the bobbin thread D and the upper thread U held by the slide plate 51 and pulls the caught sewing start ends downward, and a thread pulling air cylinder 82 (see Fig. 3), which causes the thread pulling member 81 to move in a predetermined thread pulling direction.

[0076] The thread pulling member 81 includes a holding portion 811 that presses the sewing start ends of the bobbin thread D and the upper thread U from above, a claw portion 812 that is bent downward at the tip (right end) of the holding portion 811 and holds the sewing start ends of the lower thread D and the upper thread U so as not to deviate from the holding portion 811, and an extension portion 813 that extends from the holding portion 811 in the thread pulling direction (in the obliquely downward left direction), and the base end of the extension portion 813 is connected to the piston of the thread pulling air cylinder 82.

[0077] The tip of the thread-pulling member 81 is arranged adjacent to the immediate front of the fixed knife 62 of the first thread cutting device 60. The thread-pulling member 81 is formed into a substantially U-shape by the holding portion 811, the claw portion 812, and the extension portion 813, and is arranged to cause the slide plate 51 to move through the interior of the U-shape. Thus, when the slide plate 51 moves to the front-side run-out position and holds the sewing start ends of the lower thread D and the upper thread U, the sewing start ends of the lower thread D and the upper thread U pass through the interior of the U-shape.

[0078] At this time, by arranging the sewing start ends of the lower thread D and the upper thread U on the right side of the hook-shaped portion 621 of the fixed knife 62 as shown in Fig. 22, the sewing start ends are not cut in this state.

[0079] However, since the thread pulling member 81 moves obliquely downwards to the left by the thread pulling air cylinder 82, as shown in Fig. 25, the sewing start ends of the lower thread D and the upper thread U can be caused to be drawn into the hook-shaped portion 621 of the fixed knife 62 to engage therewith.

[0080] Accordingly, the sewing start ends of the lower thread D and the upper thread U can be cut by causing the movable knife 61 to move to the left. Catch mechanism

[0081] The catching mechanism 19 is arranged inside the sewing bed 16 and below the first thread cutting device 60. The catching mechanism 19 comprises a housing whose upper part is open, a blower 191 (see Fig. 3) which is arranged in the housing, and a trap which catches the cut pieces of the lower thread and the upper thread sucked into the housing, and it can catch the cut pieces in the trap by driving the blower 191. Sewing machine control system

[0082] A control system of the sewing machine is described below with reference to Fig. 3 described.

[0083] Roughly, a control device 110 of the sewing machine 10 includes a ROM 112 in which various programs for various processes, such as control and determination processes, are stored, a CPU 111 which executes various calculation processes according to various programs, a RAM 113 which is used as a working memory in various processes, and an EEPROM 114 in which a variety of sewing data and setting data are stored.

[0084] Via a system bus, a drive circuit, and the like, the control device 110 is connected to the sewing motor 117 serving as a drive source for sewing, the release air cylinder 22 of the holding release mechanism 20, the first thread handling air cylinder 32 and the second thread handling air cylinder 35 of the thread handling mechanism 30, the nozzle lifting air cylinder 44 and the switching valve 45 of the air blowing mechanism 40, the first thread holding air cylinder 52 and the second thread holding air cylinder 53 of the sewing start end holding mechanism 50, the first thread cutting air cylinder 63 of the first thread cutting device 60, the second thread cutting solenoid 74 of the second thread cutting device 70, the thread pulling air cylinder 82 of the thread pulling mechanism 80, the blower 191 of the catching mechanism 19, an operation input unit 115 used for inputting various operations, and a start pedal 116 used for Used to enter the sewing start.

[0085] In fact, the control device 110 controls solenoid valves through which the release air cylinder 22, the first thread handling air cylinder 32, the second thread handling air cylinder 35, the nozzle lifting air cylinder 44, the first thread holding air cylinder 52, the second thread holding air cylinder 53, the first thread cutting air cylinder 63, the second thread cutting solenoid 74, and the thread pulling air cylinder 82 are individually activated; however, the solenoid valves are not shown here.

[0086] The sewing motor 117 and the blower 191 are controlled via the drive circuit, but are also not shown here. Cutting control of the sewing start end

[0087] Fig. 30 is a flowchart showing a control procedure for cutting the sewing start ends of the lower thread D and the upper thread U. The control procedure for cutting the sewing start ends of the lower thread D and the upper thread U, which is executed by the control device 110 of the sewing machine 10 having the above-mentioned configuration at the time of sewing start, will be described below mainly with reference to the perspective views of Fig. 15 to 20, the operational diagrams of Fig. 26 to 29 and the flow chart of Fig. 30 described. In Fig. 26 to 29, a reference symbol C denotes a sewing material as a sewing target.

[0088] The operation of cutting the sewing start ends, which will be described below, is based on the premise that the sewing motor 117 is initially stopped in a state where the needle bar is positioned at the top dead center, and that the tip of the lower thread is clamped by the second thread cutting device 70 due to the preceding sewing operation. The slide plate 51 is in the run-out position ( Fig. 26A) when the power supply of the sewing machine is switched off, and the sliding plate 51 moves to the lower thread insertion position ( Fig. 26B) when the power of the sewing machine is turned on. The following description describes the state in which the slide plate 51 moves to the bobbin thread insertion position when the power of the sewing machine is turned on.

[0089] In the state where the first and second thread holding air cylinders 52 and 53 perform a forward movement, the slide plate 51 is arranged at the bobbin thread insertion position where the second opening 512 is superimposed on the needle hole 15 (step S1 in Fig. 30). At this time, the thread-pulling air cylinder 82 is arranged in the forward-moved position and the thread-pulling member 81 is arranged above the slide plate 51 ( Fig. 15).

[0090] As in Fig. 4, with respect to the sewing start end of the bobbin thread hanging from the horizontal shuttle 18 to the second thread cutter 70, the thread handling hook 31 is caused to perform a forward movement in the state in which the first and second thread handling air cylinders 32 and 35 of the thread handling mechanism 30 are engaged. Accordingly, the sewing start end of the bobbin thread is caught in the concave portion 312, and then only the second thread handling air cylinder 35 is caused to move backward. Accordingly, the bobbin thread is continuously drawn out of the horizontal shuttle 18 and pulled so that the sewing start end of the bobbin thread passes just below the needle hole 15.

[0091] Subsequently, the nozzle lifting air cylinder 44 of the air blowing mechanism 40 is caused to move forward to lift the nozzle 41, and the tip of the nozzle 41 approaches the lower thread and the needle hole 15.

[0092] By causing the release air cylinder 22 of the holding release mechanism 20 to move backward to lower the locking member 21, the holding state of the sewing start end of the bobbin thread by the second thread cutting device 70 is released. The switching valve 45 of the air blowing mechanism 40 is controlled to an air supply state. Subsequently, by blowing air, the sewing start end of the bobbin thread D is blown upward from the position below the needle hole 15 to a position above the needle hole 15 and introduced through the needle hole 15 and the second opening 512 ( Fig. 16 and Fig. 26B and step S5 in Fig. 30).

[0093] Subsequently, the first thread holding air cylinder 52 is caused to move backward, and the slide plate 51 is caused to move to the upper thread insertion position in which the first opening 511 is superimposed on the needle hole 15 ( Fig. 17 and Fig. 26C and step S7 in Fig. 30). Accordingly, the sewing start end of the bobbin thread D is clamped between the slide plate 51 and the throat plate 17. At this time, the nozzle-lifting air cylinder 44 is caused to move backward to lower the nozzle 41.

[0094] Then the sewing motor 117 is driven to start a sewing process ( Fig. 18 and step S9 in Fig. 30).

[0095] Accordingly, the sewing needle 11 is lowered to execute the stitching point of a first stitch, the upper thread U enters the first opening 511 and the needle hole 15, the edge of the horizontal shuttle 18, which starts to rotate with the drive of the sewing motor 117, is lifted, and the sewing start end of the upper thread U is pulled to a position below the needle hole 15 ( Fig. 19 and Fig. 27A).

[0096] Subsequently, the second thread holding air cylinder 53 is caused to move backward at the timing at which the sewing needle 11 is lifted and deviates from the needle hole 15, and the slide plate 51 is caused to move to the run-out position ( Fig. 20 and Fig. 27B and step S11 in Fig. 30).

[0097] Accordingly, the sewing start ends of the lower thread D and the upper thread U are pulled forward and extend forward and backward below the thread pulling member 81.

[0098] The thread-pulling air cylinder 82 is caused to move backward in order to lower the thread-pulling member 81 ( Fig. 27C and step S13 in Fig. 30).

[0099] Accordingly, as in Fig. 23, the sewing start ends of the lower thread D and the upper thread U are caught by the thread pulling member 81 and pulled downward into the hook-shaped portion 621 of the fixed knife 62 of the first thread cutting device 60.

[0100] The needle handling by the sewing motor 117 is carried out continuously and the stitch point of a second stitch is executed ( Fig. 28A).

[0101] At this time, the thread-pulling air cylinder 82 maintains the backward-moving state, and by means of the thread-pulling member 81, a downward pulling force is continuously exerted on the sewing start ends of the lower thread D and the upper thread U. Accordingly, as the sewing process progresses and the sewing material C is advanced, an additional length of the lower thread D and the upper thread U is generated, and the thread-pulling member 81 is further lowered by the same amount ( Fig. 28B) and the sewing start ends of the lower thread D and the upper thread U are pulled further into the hook-shaped area 621 of the fixed knife 62.

[0102] Meanwhile, the control device 110 continuously monitors the position of the needle bar based on the drive of the sewing motor 117 and waits for the needle up-stroke timing of a third stitch (step S15 in Fig. 30).

[0103] When the needle up-stroke timing of the third stitch is reached, the stitch point position of the first stitch is immediately above the thread cutting position of the first thread cutting device 60. At this timing, by switching the first thread cutting air cylinder 63 of the first thread cutting device 60 to the forward-moved state, the movable knife 61 is moved forward to cut the sewing start ends of the lower thread D and the upper thread U ( Fig. 24 and Fig. 28C and step S17 in Fig. 30).

[0104] If the sewing start ends of the lower thread D and the upper thread U are cut at this timing, the sewing start end of the upper thread U can be cut the shortest. Because no knot is formed in the first stitch, the lower thread D hangs from the stitch point position of the second stitch, but the sewing start end of the lower thread D can be satisfactorily shortened.

[0105] If the sewing start end of the bobbin thread D is to be shortened, the thread cutting can be carried out at the sewing needle up timing of a fourth stitch.

[0106] Subsequently, after the sewing is completed, the first and second thread holding air cylinders 52 and 53 are switched to the forward-moved state and the slide plate 51 is caused to move to the lower thread insertion position in which the second opening 512 is superimposed on the needle hole 15 ( Fig. 29 and step S19 in Fig. 30). At the same time, the fan 191 of the catching mechanism 19 is activated (step S21 in Fig. 30).

[0107] Accordingly, the cut pieces of the lower thread D and the upper thread U held by the slide plate 51 are released and dropped and caught by the catching mechanism 19.

[0108] Accordingly, the control sequence for cutting the sewing start ends of the lower thread D and the upper thread U ends. Technical advantages of the embodiment

[0109] The sewing machine 10 includes the lower thread insertion mechanism 2 which inserts a sewing start end of a bobbin thread D into the needle hole from the lower side, the sewing start end holding mechanism 50 which holds the sewing start end of the bobbin thread D inserted into the needle hole 15 above the needle plate 17, and the first thread cutting device 60 which cuts the sewing start end of the lower thread D held by the sewing start end holding mechanism 50.

[0110] Accordingly, it is possible to cut the sewing start end of the lower thread D remaining in the sewing material C to make it shorter and thus achieve an improvement in sewing quality.

[0111] The sewing machine 10 includes the second thread cutting device 70 which cuts the bobbin thread D consumed during sewing and holds the end of the cut bobbin thread D on the shuttle side as a sewing start end for the next sewing operation, and the bobbin thread insertion mechanism 2 includes the holding release mechanism 20 which releases the clamped state of the sewing start end of the bobbin thread D by the second thread cutting device 70, the thread handling mechanism 30 which pulls the sewing start end of the bobbin thread D to the bottom of the needle hole 15, and the air blowing mechanism 40 which introduces the sewing start end of the bobbin thread D, whose clamped state is released, into the needle hole 15 by air.

[0112] Accordingly, at the end of sewing, the end of the lower thread D can be clamped on the shuttle side as a sewing start end for the next sewing operation. Through the cooperation of the clamp release mechanism 20, the thread handling mechanism 30, and the air blowing mechanism 40, it is possible to automatically insert the sewing start end of the lower thread D into the needle hole.

[0113] In addition, since the sewing start end of the lower thread D introduced upward into the needle hole 15 is held by the sewing start end holding mechanism 50 and cut by the first thread cutting device 60, it is possible to automatically perform a series of operations and thus realize a reduction in workload and an improvement in work efficiency.

[0114] The thread handling mechanism 30 of the sewing machine 10 includes the thread handling hook 31 that brings the sewing start end of the bobbin thread D close to the bottom of the needle hole 15 by moving forward. The thread handling hook 31 includes the first inclined portion 311 formed at its tip for causing the sewing start end of the bobbin thread D to move upward, the concave portion 312 formed at the top of the tip for catching the sewing start end of the bobbin thread D, and the second inclined portion 313 formed inside the concave portion 312 for causing the sewing start end of the bobbin thread D to move downward. The upper end of the second inclined portion 313 is formed to be set higher than the upper end of the first inclined portion 311.

[0115] Accordingly, the vertical range in which the sewing start end of the bobbin thread D can be caught by the thread handling hook 31 can be set wider, and thus it is possible to guide the bobbin thread D to the bottom of the needle hole 15 more reliably.

[0116] The air blowing mechanism 40 of the sewing machine 10 includes the nozzle 41 or 42 which blows air toward the needle hole 15, and the nozzle 41 or 42 includes the slit 411 or 412 at the tip of which the sewing start end of the bobbin thread D is inserted.

[0117] Accordingly, since the sewing start end of the bobbin thread D can be guided into and held in the slit 411 or 421 at the time of raising the nozzle 41 or 42, it is possible to blow up and insert the sewing start end of the bobbin thread D into the needle hole 15 more reliably.

[0118] The sewing start end holding mechanism 50 of the sewing machine 10 includes a slide plate 51 in which the first opening 511 and the second opening 512 are arranged in the sliding direction. Accordingly, the sewing start end of the bobbin thread D can be clamped and held between the facing surfaces of the slide plate 51 and the needle plate 17 by causing the slide plate to slide from the lower thread insertion position where the second opening 512 is superimposed on the needle hole 15, and the sewing start ends of the lower thread D and the upper thread U can be clamped and held between the facing surfaces of the slide plate 51 and the needle plate 17 by causing the slide plate to slide from the upper thread insertion position where the first opening 511 is superimposed on the needle hole 15.

[0119] Accordingly, it is possible to hold both the sewing start end of the lower thread D and the sewing start end of the upper thread U using a single link to achieve a reduction in the number of components and to realize a size reduction of the mechanisms and a space saving.

[0120] In the sewing machine 10, the slide plate 51 slides downstream in the feed direction of the feed dog 14 constituting the fabric feed mechanism to hold the sewing start ends of the upper thread U and the lower thread D, and the first thread cutting device 60 is arranged downstream of the needle hole 15 in the feed direction of the feed dog 14 of the feed mechanism.

[0121] The control device 110 controls the sewing start end holding mechanism 50 to hold the sewing start end of the bobbin thread D before the stitching point of the first stitch and to hold the sewing start end of the upper thread U after the stitching point of the second stitch, and controls the first thread cutting device 60 to cut the sewing start ends of the upper thread and the lower thread after the stitching point of the second stitch.

[0122] Accordingly, by bringing the base portions of the sewing start ends of the lower thread D and the upper thread U, which hang down from the sewing material, close to the first thread cutting device 60 arranged downstream in the sewing material transport direction, a further shortening of the sewing start ends of the lower thread and the upper thread, which remain in the sewing material after cutting, is possible.

[0123] In the sewing machine 10, the movable knife 61 and the fixed knife 62 of the first thread cutting device 60 are arranged below the slide plate 51, and the thread pulling mechanism 80 is provided which pulls down the sewing start ends of the upper thread U and the lower thread D, which are pulled by the slide plate 51 in the sliding direction.

[0124] Accordingly, it is possible to protect the fabric by arranging the movable knife 61 and the fixed knife 62 of the first thread cutting device 60 so as not to come into scratching or otherwise damaging contact with the fabric, and it is possible to guide the sewing start ends of the lower thread D and the upper thread U to the movable knife 61 and the fixed knife 62 and thereby perform cutting more reliably. Another example of the thread pulling mechanism

[0125] The thread pulling mechanism 80 pulls the sewing start ends of the lower thread D and the upper thread U to the fixed knife 62 of the first thread cutting device 60 using the single thread pulling member 81; however, two thread pulling members may also be used.

[0126] That is, a thread pulling device 80A, which is Fig. 31, comprises a first thread pulling member 81A which includes a holding portion 811A, a claw portion 812A and an extension portion 813A, a second thread pulling member 83A which includes a holding portion 831A, a claw portion 832A and an extension portion 833A, a first thread pulling air cylinder 82A which supports the second thread pulling member 83A and brings the holding portion 831A of the second thread pulling member 83A into press contact with the holding portion 811A of the first thread pulling member 81A by lifting them, and a second thread pulling air cylinder 84A which supports the first thread pulling member 81A, the second thread pulling member 83A and the first thread pulling air cylinder 82A and lifts them.

[0127] In the above-mentioned configuration, by switching the first thread-pulling air cylinder 82A to the forward-moved state, the holding portion 831A of the second thread-pulling member 83A can be brought into press contact with the holding portion 811A of the first thread-pulling member 81A, and the sewing start ends of the lower thread D and the upper thread U can be clamped therebetween.

[0128] By causing the second thread-pulling air cylinder 84A to move backward in the state where the sewing start ends of the lower thread D and the upper thread U are clamped, it is possible to pull the sewing start ends of the lower thread D and the upper thread U to the knives 61 and 62 of the first thread cutting device 60.

[0129] Thus, by clamping and pulling the sewing start ends of the lower thread D and the upper thread U, the sewing start ends of the lower thread and the upper thread can be prevented from inadvertently deviating from the thread pulling members 81A and 83A, and the thread pulling operation can be performed more reliably. Another example of the sewing start end holding mechanism

[0130] The sewing start end holding mechanism 50 includes the linearly formed slide plate 51; however, the shape is not limited to the straight line shape. For example, as shown in Fig. 32 and Fig. 33, a sewing start end holding mechanism 50A is used which has an arcuate sliding plate 51A.

[0131] In the sewing start end holding mechanism 50A, a first opening 511A and a second opening 512A as an upper thread catching hole and a lower thread catching hole are formed at one end of the arc-shaped sliding plate 51A near the one end, and the sewing start end holding mechanism includes a first thread holding air cylinder 52A that causes an input arm 54A supporting the sliding plate 51A to rotate so as to be rotatable around the center of the arc and to rotate coaxially in conjunction with the sliding plate 51A, and a second thread holding air cylinder 53A that causes the first thread holding air cylinder 52A to move forward and backward in the same direction as the moving direction of the piston of the first thread holding air cylinder 52A.

[0132] In this case, the slide plate 51A is arranged such that the needle hole 15 is located on the circumference including the arc of the slide plate 51A, and the input arm 54A and the piston of the first thread holding air cylinder 52A are connected via a shaft and a slot, slidable over the arc, and meshed with each other.

[0133] The elements are arranged such that the second opening 512A of the sliding plate 51A is superimposed on the needle hole 15 when both the first thread holding air cylinder 52A and the second thread holding air cylinder 53A are in the forward moving state, that the first opening 511A is superimposed on the needle hole 15 when one of the two elements, which are the first thread holding air cylinder 52A and the second thread holding air cylinder 53A, is in the forward moving state, and that the openings are arranged in the run-out position at which the entire sliding plate 51A deviates from the needle hole 15 when both the first thread holding air cylinder 52A and the second thread holding air cylinder 53A are in the backward moving state.

[0134] Accordingly, the sewing start end holding mechanism 50A can switch the slide plate 51A to the insertion position of the sewing start end of the lower thread D, the insertion position of the sewing start end of the upper thread U, and the run-out position by controlling the thread holding air cylinders 52A and 53A in the same manner as in the sewing start end holding mechanism 50.

[0135] When the sliding plate has a rectilinear shape, the arrangement space for the sliding plate 51 in front of the needle hole 15 should be ensured to be wide; however, when the sliding plate 51A has an arcuate shape, the arrangement space in front of the needle hole 15 can be reduced, and thus it is possible to achieve space saving. Regulating plate of the thread pulling link

[0136] When using the sliding plate 51A having an arcuate shape, the openings 511A and 512A move along the arc as shown in Fig. 34. Accordingly, at the time of holding the sewing start end, the sewing start end of the lower thread D or the upper thread U deviates in the right-left direction (to the left when the slide plate 51A is curved to the left as shown in Fig. 34) deviates from the front-to-back direction and is pulled.

[0137] Since the sliding plate 51A is curved, the sliding plate 51A cannot pass through the inside of the holding portion 811 of the thread pulling member 81 unless the width of the holding portion 811 is formed to be larger than the width of the sliding plate 51A.

[0138] Further, the sewing start end of the lower thread D or the upper thread U comes too close to the ends of the holding portion 811 of the thread pulling member 81 in the right-left direction, and thus there is a possibility that the sewing start end of the lower thread D or the upper thread U is not properly guided into the hook-shaped portion 621 even if the thread pulling member 81 moves in a predetermined direction.

[0139] Therefore, when the sliding plate 51A having an arcuate shape is used, it is preferable that regulating plates 85A and 86A, which regulate the sewing start ends of the lower thread and the upper thread so as not to move in the right-left direction more than the width of the sliding plate 51A, are formed on one side in the front-back direction of the thread pulling member 81.

[0140] It is preferable that a slope 851A is formed in the regulating plate 85A located on an inner diameter side in the curvature direction of the slide plate 51A so that the sewing start ends of the lower thread D and the upper thread U do not fall downward. On the outer diameter side, the sewing start ends of the lower thread D and the upper thread U do not gather well, and thus, the regulating plate 86A on the outer diameter side may be omitted if necessary. Another example of the holding mechanism

[0141] The curved portion 211 of the upper portion of the locking member 21 may be configured to approach and face the underside of an intermediate portion in the length direction of the leaf spring 73 from below.

[0142] In this configuration, the leaf spring 73 is supported in a state where the leaf spring is separated from the lower surface of the movable knife 71 when no external force is applied. The release air cylinder 22 drives the clamping member 21, which is located in the position where the bent portion 211 approaches and faces the lower surface of the leaf spring 73, to move upward, and pushes the leaf spring 73 upward via the clamping member 21. By this upward pushing, the tip of the leaf spring 73 presses against the movable knife 71 and holds the sewing start end of the lower thread in the clamped state in cooperation with the movable knife 71.

[0143] When releasing the lower thread holding state, the urging action of the locking member 21 on the leaf spring 73 can be canceled by driving the release air cylinder 22 to lower and separate the locking member 21 from the same. More

[0144] The sewing machine 10 is exemplified as a mechanical feed sewing machine; however, the elements for holding and cutting sewing start ends of a bobbin thread and a top thread may also be applied to another sewing machine (for example, a lockstitch sewing machine) in which a needle bar does not swing.

[0145] For example, the case where the needle hole 15 is formed in the feed dog 14 has been illustrated; however, the present invention is not limited to this case, and the members for holding and cutting the sewing start ends of a lower thread and an upper thread can also be applied to a sewing machine in which the needle hole is formed in the throat plate.

Claims

[1] Sewing machine (10) with a needle hole (15) formed in a needle plate (17) or in a feed dog (14), comprising: a lower thread insertion mechanism including an air blowing mechanism (40) that inserts a sewing start end of a lower thread (D) into the needle hole (15) from a lower side of the needle plate (17) by air; a sewing start end holding mechanism (50, 50A) which holds the sewing start end of the inserted lower thread (D) above the needle plate (17); a first thread cutting device (60) which cuts the sewing start end of the lower thread (D) held by the sewing start end holding mechanism (50, 50A); and a control device (110) which controls operations of the sewing machine (10). [2] Sewing machine according to claim 1, wherein the air blowing mechanism (40) comprises a nozzle (41) which ejects air towards the needle hole (15), wherein the nozzle (41) has a slot (411) at a tip of the nozzle (41) and wherein the slot (411) is designed to guide and hold the sewing start end of the lower thread (D). [3] Sewing machine according to claim 1 or 2, wherein the sewing start end holding mechanism (50, 50A) comprises a sliding plate (51) having an upper thread catching hole and a lower thread catching hole, wherein the upper thread catching hole and the lower thread catching hole are arranged in a sliding direction, wherein the upper thread catching hole and the lower thread catching hole are designed to clamp and hold the sewing start end of the lower thread (D) and a sewing start end of an upper thread (U) between the sliding plate (51) and a facing surface of the throat plate (17), wherein the sliding plate (51) is movable into an upper thread insertion position, a lower thread insertion position and a run-out position, wherein in the upper thread insertion position the upper thread catching hole is superimposed on the needle hole (15), wherein in the bobbin thread insertion position the bobbin thread catching hole is superimposed on the needle hole (15) and wherein in the run-out position both the lower thread catching hole and the upper thread catching hole are separated from the needle hole (15). [4] Sewing machine according to claim 3, wherein the sliding plate (51) clamps and holds the sewing start end of the upper thread (U) and the sewing start end of the lower thread (D) between the sliding plate (51) and the facing surface of the throat plate (17) in the run-out position and wherein the control device (110) controls the sewing machine (10) to: arrange the slide plate (51) in the lower thread insertion position before a stitching point of a first stitch, insert the sewing start end of the lower thread (D) into the needle hole (15) and into the lower thread catching hole from the underside by using the air blowing mechanism (40), arrange the slide plate (51) in the upper thread insertion position after inserting the sewing start end of the lower thread (D), insert the sewing start end of the upper thread (U) into the needle hole (15) and into the upper thread catching hole through the stitching point of the first stitch, arrange the slide plate (51) in the run-out position after inserting the sewing start end of the upper thread (U), and cut the sewing start end of the upper thread (U) and the sewing start end of the lower thread (D) by using the first thread cutting device (60) at and after a stitching point of a second stitch. [5] Sewing machine according to claim 3 or 4, wherein a knife of the first thread cutting device (60) is arranged below the sliding plate (51), wherein the sewing machine (10) further comprises: a thread pulling mechanism (80) which performs a downward movement when the sliding plate (51) is arranged in the run-out position, pulls the sewing start end of the upper thread (U) and the sewing start end of the lower thread (D) which are pulled out by the sliding plate (51), and engages the sewing start end of the upper thread (U) and the sewing start end of the lower thread (D) with the first thread cutting device (60), and wherein the control device (110) controls the sewing machine (10) to cut the sewing start end of the upper thread (U) and the sewing start end of the lower thread (D) by using the first thread cutting device (60) after downward movement of the thread pulling mechanism (80). [6] Sewing machine according to one of claims 3 to 5, further comprising: a second thread cutting device (70) which cuts the lower thread (D) upon completion of a first sewing operation and holds an end of the cut lower thread (D) on a shuttle side as a sewing start end for a second sewing operation which follows next to the first sewing operation, wherein the bobbin thread insertion mechanism comprises: a holding release mechanism (20) which releases a holding state of the sewing start end of the lower thread (D) held by the second thread cutting device (70), and a thread handling mechanism (30) which pulls the sewing start end of the lower thread (D) to the underside of the needle hole (15). [7] Sewing machine according to claim 6, wherein the thread handling mechanism (30) comprises a thread handling member which, by a forward movement of the thread handling member, pulls the sewing start end of the lower thread (D) to the underside of the needle hole (15), wherein the thread handling member comprises a first inclined portion (311), a concave portion (312) and a second inclined portion (313), wherein the first inclined portion is formed at a tip of the thread handling member to move the sewing start end of the lower thread (D) upward, wherein the concave portion (313) is formed in an upper part of the tip to catch the sewing start end of the lower thread (D), wherein the second inclined portion (313) is formed inside the concave portion (312) to move the sewing start end of the lower thread (D) downward, and wherein an upper end of the second inclined portion (313) is higher than an upper end of the first inclined portion (311). [8] Sewing machine according to claim 6 or 7, wherein, before inserting the sewing start end of the lower thread (D) into the needle hole (15) and into the lower thread catching hole by using the air blowing mechanism (40), the control device (110) controls the sewing machine (10) to drive the thread handling mechanism (30) to pull the sewing start end of the lower thread (D) to the underside of the needle hole (15), and to drive the holding release mechanism (20) to release the holding state of the sewing start end of the lower thread (D) held by the second thread cutting device (70).

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