Sewing machine

Abstract

The invention provides a sewing machine, which is provided with a cam type take-up lever and uses a plurality of upper threads, and can make sewing completion of each thread consistent. The sewing machine includes: a needle bar that holds a first sewing machine needle and a second sewing machine needle and is driven in a vertical direction; a take-up lever through which a first top thread supplied to the first sewing machine needle and a second top thread supplied to the second sewing machine needle are inserted and which operates in conjunction with the needle bar; a cam portion including a first cam that guides a first top thread passing through the take-up lever and adjusts thread tightening, and a second cam that is provided separately from the first cam and guides a second top thread passing through the take-up lever and adjusts thread tightening; and a sewing machine main body provided with a needle bar, a take-up lever, and a cam portion, the first cam and the second cam being attached to the sewing machine main body so as to be adjustable in position.

Description

Technical Field

[0001] The invention relates to a sewing machine. Background Art

[0002] A cam-type thread take-up lever type sewing machine is known. As an example of a cam-type thread take-up lever type sewing machine, a sewing machine is disclosed in Patent Document 1, which comprises: a needle bar thread take-up lever; and a thread winding plate, which is formed with a cam surface capable of tightening the needle thread along with the reciprocating motion of the needle bar thread take-up lever. The sewing machine of Patent Document 1 is a double-needle sewing machine, and the two upper threads of the right needle thread and the left needle thread pass through the needle bar thread take-up lever. The thread winding plate is a flat plate component formed with two cam surfaces, a cam surface for the right needle thread and a cam surface for the left needle thread. When the needle bar thread take-up lever reciprocates with the right needle thread and the left needle thread, the thread winding plate moves the right needle thread and the left needle thread along the corresponding cam surfaces respectively. Each cam surface is curved into a mountain shape. As the right needle thread and the left needle thread move toward the top of the mountain, the path length of the needle thread from the sewing machine needle to the cam surface changes, and the needle thread is pulled by a length equivalent to the change in the path length, thereby tightening the thread.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 7-96088 Summary of the invention

[0006] 1. Technical issues to be resolved

[0007] Regarding the above-mentioned Patent Document 1, when it is desired to adjust the thread tightening degree, it is considered to adjust the installation position of the thread plate. However, since the installation position of the thread plate affects the thread tightening of all needles and threads, it is difficult to make the sewing of the right needle and the left needle be consistent when the sewing completion state is different.

[0008] The present disclosure has been made in view of the above circumstances, and an object thereof is to provide a sewing machine which includes a cam-type thread take-up lever and uses a plurality of upper threads, and in which the sewing of each thread can be completed uniformly.

[0009] (II) Technical solution

[0010] According to the present invention, there is provided a sewing machine comprising: a needle bar, which holds a first sewing machine needle and a second sewing machine needle and is driven in an up-and-down direction; a thread take-up lever, through which a first upper thread supplied to the first sewing machine needle and a second upper thread supplied to the second sewing machine needle are inserted and which moves in conjunction with the needle bar; a cam portion, which includes a first cam and a second cam, the first cam guides the first upper thread passing through the thread take-up lever and adjusts the thread tension, and the second cam is separately arranged with the first cam to guide the second upper thread passing through the thread take-up lever and adjust the thread tension; and a sewing machine body, which is provided with the needle bar, the thread take-up lever and the cam portion, and the first cam and the second cam are respectively installed relative to the sewing machine body in a manner that allows for position adjustment.

[0011] (III) Beneficial effects

[0012] According to an aspect of the present invention, there is provided a sewing machine which includes a cam-type thread take-up lever and uses a plurality of upper threads and can make the sewing of the respective threads uniform. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a side view schematically showing an example of the sewing machine according to the present embodiment.

[0014] Figure 2 It is a side view schematically showing an example of the internal structure of the sewing machine according to the present embodiment.

[0015] Figure 3 It is a perspective view for explaining the path of the upper line in the embodiment.

[0016] Figure 4 These are diagrams for explaining each stage (A) to (D) of the operation of the sewing machine needle and the looper according to the present embodiment.

[0017] Figure 5 is a schematic diagram of the shape of the stitch formed by the double loop stitch.

[0018] Figure 6 This is a perspective view of the thread take-up lever and the cam portion according to the embodiment as viewed from the -X direction.

[0019] Figure 7 This is a perspective view of the thread take-up lever and the cam portion according to the embodiment as viewed from the +X direction.

[0020] Figure 8 It is an exploded perspective view of the cam portion according to the embodiment.

[0021] Fig. 9 It is a front view of the cam portion showing a state in which the screw member is removed.

[0022] Fig.10 It is a schematic diagram showing the positional relationship between the thread take-up lever and the cam portion when the thread take-up lever is located near the lower inclined surface of the cam portion.

[0023] Fig.11 It is a schematic diagram showing the positional relationship between the thread take-up lever and the cam portion when the thread take-up lever is located near the top of the cam portion.

[0024] Fig.12 Yes means Fig.11 Schematic diagram of the cross section of the thread take-up lever and the cam portion.

[0025] Fig.13 It is a schematic diagram showing the positional relationship between the thread take-up lever and the cam portion when the thread take-up lever is located near the upper inclined surface of the cam portion.

[0026] Description of Reference Numerals

[0027] 1-sewing machine, 2-sewing machine body, 2A-first arm, 2B-base, 2C-second arm, 2D-head, 3-needle bar, 4-thread take-up lever, 4A-first part, 4B-second part, 4C-third part, 5-cam part, 6-sewing machine needle, 6A-first sewing machine needle, 6B-second sewing machine needle, 6C-third sewing machine needle, 7-needle hole, 8-needle plate, 9-bend needle, 9A-first bend needle, 9B-second bend needle, 9C-third bend needle, 10-upper thread adjuster, 10A-first upper thread adjuster, 10B-second upper thread adjuster, 10C-third upper thread adjuster, 11-lower thread adjuster , 11A-first lower line adjuster, 11B-second lower line adjuster, 11C-third lower line adjuster, 12-actuator, 13-transmission device, 13A-arm shaft, 13B-base shaft, 13C-bending needle shaft, 13C1-swing arm, 13D-pulley, 13E-pulley, 13F-timing belt, 13G-transmission mechanism, 13H-transmission mechanism, 15-upper line guide, 15A, 15B, 15C-guide hole, 16-lower line guide, 21, 25-line guide, 22, 23, 24-line adjuster, 31-first cam, 31A-first guide surface, 31B-top , 31C-lower inclined surface, 31D-upper inclined surface, 32-second cam, 32A-second guide surface, 32B-top, 32C-lower inclined surface, 32D-upper inclined surface, 32E-opposing surface, 33-third cam, 33A-third guide surface, 33B-top, 33C-lower inclined surface, 33D-upper inclined surface, 33E-opposing surface, 34-fixing component, 34A-first fixing component, 34A1-first threaded hole, 34A2-second threaded hole, 34A3-third threaded hole, 34B-second fixing component, 34B1-first threaded hole, 34B2-second threaded hole Grooved hole, 34B3-third threaded hole, 35-cam guide part, 35A, 35B, 35C-hole, 36A, 36B, 36C-screw insertion part, 37-screw component, 41A, 41B, 41C-entrance hole, 42A, 42B, 42C-exit hole, 43-mounting part, AX-rotation axis, BS-lower surface, LT-lower line, LT1-first lower line, LT2-second lower line, LT3-third lower line, P1, P2, P3-contact position, TP1, TP2-line passage, UT-upper line, UT1-first upper line, UT2-second upper line, UT3-third upper line. DETAILED DESCRIPTION

[0028] Hereinafter, the embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited thereto. The constituent elements of the embodiments described below can be combined as appropriate. In addition, there are also cases where some constituent elements are not used.

[0029] In the following description, an XYZ orthogonal coordinate system is set, and the positional relationship of each part is described with reference to the XYZ orthogonal coordinate system. The direction parallel to the X-axis in the specified plane is set as the X-axis direction. The direction parallel to the Y-axis in the specified plane that is orthogonal to the X-axis is set as the Y-axis direction. The direction parallel to the Z-axis that is orthogonal to the specified plane is set as the Z-axis direction. In addition, the rotation direction or tilt direction centered on the X-axis is set as the θX direction. The rotation direction or tilt direction centered on the Y-axis is set as the θY direction. The rotation direction or tilt direction centered on the Z-axis is set as the θZ direction. In addition, the plane containing the X-axis and the Y-axis is appropriately referred to as the XY plane. The plane containing the X-axis and the Z-axis is appropriately referred to as the XZ plane. The plane containing the Y-axis and the Z-axis is appropriately referred to as the YZ plane. The XY plane is parallel to the specified plane. The XY plane, the XZ plane, and the YZ plane are orthogonal. In addition, in the following description, the XY plane is set to be parallel to the horizontal plane. The Z-axis direction is the up and down direction. The +Z direction is the upward direction, and the -Z direction is the downward direction. In addition, the XY plane may be inclined relative to the horizontal plane.

[0030] (Sewing Machine)

[0031] Figure 1 It is a side view schematically showing an example of the sewing machine 1 according to the present embodiment. Figure 2 It is a side view schematically showing an example of the internal structure of the sewing machine 1 according to the present embodiment. Figure 3 1 is a perspective view for explaining the path of the upper thread UT according to the embodiment. In the present embodiment, the sewing machine 1 is a double loop sewing machine for performing double loop sewing.

[0032] like Figure 1 , Figure 2 and Figure 3 As shown, the sewing machine 1 includes: a sewing machine body 2; a needle bar 3, which holds the sewing machine needle 6 and reciprocates in the Z-axis direction; a thread take-up lever 4, which supplies the upper thread to the sewing machine needle 6; and a cam portion 5, which adjusts the thread tension of the upper thread by cooperating with the thread take-up lever 4.

[0033] In addition, the sewing machine 1 has: a needle plate 8, which has a needle hole 7 through which the sewing machine needle 6 can pass and supports the sewing object; and a curved needle 9, which swings around a rotation axis AX parallel to the Y axis, picks up the upper thread from the sewing machine needle 6 that has passed through the sewing object and the needle hole 7, and winds it with the lower thread (curved needle thread).

[0034] In addition, the sewing machine 1 has: an upper thread regulator 10, which supplies the upper thread from the thread supply source; a lower thread regulator 11, which supplies the lower thread from the thread supply source; an actuator 12, which generates power; and a transmission device 13, which transmits the power generated by the actuator 12 to the needle bar 3 and the curved needle 9 respectively.

[0035] The sewing machine body 2 is a structure provided with various components including a needle bar 3, a thread take-up lever 4, and a cam portion 5. The sewing machine body 2 includes: a first arm 2A provided with an actuator 12; a base 2B opposed to the first arm 2A; a second arm 2C connecting one end of the first arm 2A on the +X side to the base 2B; and a head 2D provided at the other end of the first arm 2A on the -X side and supporting the needle bar 3. In addition, although the first arm 2A, the second arm 2C, and the head 2D are described as being divided into three parts, they are structurally integrated.

[0036] The first arm 2A extends in the X-axis direction. The base 2B is arranged at a position closer to the -Z direction than the first arm 2A and extends in the X-axis direction. The second arm 2C extends in the Z-axis direction and connects one end of the +X side of the first arm 2A to one end of the +X side of the base 2B. The head 2D protrudes in the -Z direction from the other end of the -X side of the first arm 2A.

[0037] The needle bar 3 holds the sewing machine needle 6. In the embodiment, the sewing machine 1 is capable of installing a plurality of sewing machine needles 6 on the needle bar 3, and forming stitches using each sewing machine needle 6 in parallel. That is, the needle bar 3 holds the first sewing machine needle 6A and the second sewing machine needle 6B, and is driven in the up and down direction. In the embodiment, the needle bar 3 holds the third sewing machine needle 6C in addition to the first sewing machine needle 6A and the second sewing machine needle 6B. The sewing machine 1 is configured as a so-called three-needle double-loop sewing machine. Hereinafter, the three sewing machine needles are collectively referred to as the sewing machine needles 6. When distinguishing between the individual sewing machine needles 6, they are respectively referred to as the first sewing machine needle 6A, the second sewing machine needle 6B, and the third sewing machine needle 6C.

[0038] The needle bar 3 holds the sewing machine needle 6 in such a manner that the sewing machine needle 6 is parallel to the Z axis. The needle bar 3 reciprocates in the Z axis direction. The needle bar 3 is supported by the head 2D. The sewing machine needle 6 has a threading hole for passing the upper thread UT. The sewing machine needle 6 holds the upper thread UT on the inner surface of the threading hole. A different upper thread UT is supplied to each sewing machine needle 6. That is, the first upper thread UT1 is supplied to the first sewing machine needle 6A. The second upper thread UT2 is supplied to the second sewing machine needle 6B. The third upper thread UT3 is supplied to the third sewing machine needle 6C. The upper thread UT is a general term for the first upper thread UT1, the second upper thread UT2, and the third upper thread UT3. As the needle bar 3 reciprocates in the Z axis direction, the sewing machine needle 6 reciprocates in the Z axis direction while holding the upper thread UT.

[0039] The thread take-up lever 4 supplies the upper thread UT to the sewing machine needle 6. The thread take-up lever 4 is inserted through the first upper thread UT1 supplied to the first sewing machine needle 6A, the second upper thread UT2 supplied to the second sewing machine needle 6B, and the third upper thread UT3 supplied to the third sewing machine needle 6C, and moves in conjunction with the needle bar 3. The thread take-up lever 4 reciprocates in the Z-axis direction. In the embodiment, the thread take-up lever 4 is a so-called needle bar thread take-up lever that is fixed to the needle bar 3 and reciprocates integrally with the needle bar 3. The thread take-up lever 4 reciprocates in the Z-axis direction while holding each upper thread UT. The thread take-up lever 4 pulls out the upper thread UT or lifts the upper thread UT by reciprocating in the Z-axis direction.

[0040] The needle plate 8 supports the sewing object. The needle plate 8 is arranged at a position closer to the -Z direction than the needle bar 3. The sewing machine needle 6 held by the needle bar 3 faces the needle plate 8. The needle plate 8 has a needle hole 7 through which the sewing machine needle 6 can pass. The sewing machine needle 6 that penetrates the sewing object supported by the needle plate 8 passes through the needle hole 7.

[0041] The looper 9 picks up the upper thread UT from the sewing machine needle 6 that penetrates the sewing object supported by the needle plate 8 and passes through the needle hole 7 of the needle plate 8. The looper 9 is arranged at a position closer to the -Z direction than the needle plate 8. The looper 9 is arranged inside the base 2B. The looper 9 is supported by the base 2B in a manner that allows it to rotate in the θY direction. The looper 9 holds the lower thread LT that is entangled with the upper thread UT to form a stitch. The same number of loopers 9 as the sewing machine needle 6 are provided. For convenience, Figure 2 Only one looper 9 is shown in the figure, but in the embodiment, the looper 9 includes a first looper 9A corresponding to the first sewing machine needle 6A, a second looper 9B corresponding to the second sewing machine needle 6B, and a third looper 9C corresponding to the third sewing machine needle 6C.

[0042] The upper thread regulator 10 applies tension to the upper thread UT supplied to the sewing machine needle 6. The upper thread regulator 10 is supported by the first arm 2A. The upper thread regulator 10 is provided for each upper thread UT. That is, the upper thread regulator 10 includes: a first upper thread regulator 10A, which applies tension to the first upper thread UT1 supplied to the first sewing machine needle 6A; a second upper thread regulator 10B, which applies tension to the second upper thread UT2 supplied to the second sewing machine needle 6B; and a third upper thread regulator 10C, which applies tension to the third upper thread UT3 supplied to the third sewing machine needle 6C. Figure 3 As shown, each upper thread regulator 10 has the same structure. Each upper thread regulator 10 includes: a group of a thread guide 21, a thread regulator 22, a thread regulator 23, a thread regulator 24 and a thread guide 25. The corresponding upper thread UT is supplied to each upper thread regulator 10 from an upper thread holder 14 provided on the upper surface of the first arm 2A. The upper thread holder 14 includes: an upper thread holder 14A for holding the first upper thread UT1, an upper thread holder 14B for holding the second upper thread UT2, and an upper thread holder 14C for holding the third upper thread UT3.

[0043] The upper thread regulator 10 is arranged between the upper thread seat 14 and the thread take-up lever 4. An upper thread guide 15 is arranged between the thread take-up lever 4 and the sewing machine needle 6. The upper thread guide 15 is provided on the head 2D. The upper thread guide 15 has three holes through which the upper threads UT are respectively inserted. The upper thread guide 15 guides the first upper thread UT1, the second upper thread UT2, and the third upper thread UT3 to the corresponding first sewing machine needle 6A, the second sewing machine needle 6B, and the third sewing machine needle 6C.

[0044] like Figure 1 As shown, the lower thread adjuster 11 applies tension to the lower thread LT supplied to the bending needle 9. The lower thread adjuster 11 is supported by the first arm 2A. The lower thread adjuster 11 is provided for each lower thread LT. That is, the lower thread adjuster 11 includes: a first lower thread adjuster 11A, which applies tension to the first lower thread LT1 supplied to the first bending needle 9A; a second lower thread adjuster 11B, which applies tension to the second lower thread LT2 supplied to the second bending needle 9B; and a third lower thread adjuster 11C, which applies tension to the third lower thread LT3 supplied to the third bending needle 9C.

[0045] The second arm 2C is provided with a plurality of lower thread guides 16. Each lower thread guide 16 guides each lower thread LT along the path from the lower thread adjuster 11 to the looper 9. Each lower thread LT is guided from the lower thread adjuster 11 along the second arm 2C in the -Z direction through the lower thread guide 16 and introduced into the base 2B. Each lower thread LT is supplied to the corresponding looper 9 through the lower thread guide not shown in the figure in the base 2B.

[0046] like Figure 2 As shown, the actuator 12 generates power to reciprocate the needle bar 3 in the Z-axis direction. In addition, the actuator 12 generates power to swing the looper 9 in the θY direction. The actuator 12 includes a pulse motor. The actuator 12 is supported by the first arm 2A.

[0047] The transmission device 13 transmits the power generated by the actuator 12 to the needle bar 3 and the curved needle 9, respectively. The power generated by the actuator 12 is transmitted to the needle bar 3 via the transmission device 13. Therefore, the needle bar 3, the thread take-up lever 4 fixed to the needle bar 3, and the sewing machine needle 6 held by the needle bar 3 reciprocate in the Z-axis direction. In addition, the power generated by the actuator 12 is transmitted to the curved needle 9 via the transmission device 13. Therefore, the curved needle 9 swings in the θY direction in synchronization with the reciprocating movement of the needle bar 3 in the Z-axis direction. The sewing machine 1 sews the sewing object by the cooperation of the sewing machine needle 6 held by the needle bar 3 and the curved needle 9.

[0048] Figure 2 1 shows a schematic structure of the transmission device 13. Figure 2As shown, the transmission device 13 includes an arm shaft 13A arranged inside the first arm 2A, a base shaft 13B arranged inside the base 2B, and a looper shaft 13C arranged inside the base 2B.

[0049] The transmission device 13 also includes a pulley 13D provided on the arm shaft 13A, a pulley 13E provided on the base shaft 13B, and a timing belt 13F stretched between the pulley 13D and the pulley 13E.

[0050] The arm shaft 13A extends in the X-axis direction. The actuator 12 is connected to one end portion on the +X side of the arm shaft 13A. The arm shaft 13A rotates in the θX direction by the operation of the actuator 12.

[0051] The other end of the arm shaft 13A on the -X side is connected to the needle bar 3 via the transmission mechanism 13G. The power generated by the actuator 12 is transmitted to the needle bar 3 via the arm shaft 13A and the transmission mechanism 13G. As a result, the needle bar 3, the thread take-up lever 4 and the sewing machine needle 6 reciprocate in the Z-axis direction.

[0052] The base shaft 13B extends in the X-axis direction. The base shaft 13B is arranged parallel to the arm shaft 13A. The base shaft 13B can rotate in the θX direction. The power of the actuator 12 is transmitted to the base shaft 13B via a pulley 13D provided on the arm shaft 13A, a pulley 13E provided on the base shaft 13B, and a timing belt 13F mounted on the pulley 13D and the pulley 13E.

[0053] The other end of the -X side of the base shaft 13B is connected to the bending needle shaft 13C via the transmission mechanism 13H. The power generated by the actuator 12 is transmitted to the bending needle shaft 13C via the arm shaft 13A, the base shaft 13B and the transmission mechanism 13H. The transmission mechanism 13H is an eccentric cam mechanism. The transmission mechanism 13H connects the swing arm 13C1 connected to the bending needle shaft 13C and the base shaft 13B. The transmission mechanism 13H causes the front end of the swing arm 13C1 to reciprocate up and down through the power generated by the actuator 12.

[0054] The bending needle shaft 13C is arranged at a position closer to the +Z direction than the base shaft 13B. The bending needle shaft 13C extends in the Y-axis direction. The bending needle shaft 13C can rotate in the θY direction. The bending needle shaft 13C is supported by the base 2B. The swing arm 13C1 extends from the bending needle shaft 13C in the radial direction. The bending needle shaft 13C reciprocates within a specified angle range as the front end of the swing arm 13C1 reciprocates in the upward and downward directions.

[0055] The bending needles 9 (the first bending needle 9A, the second bending needle 9B and the third bending needle 9C) are fixed to the bending needle shaft 13C. As a result, the bending needle 9 and the bending needle shaft 13C reciprocate integrally around the rotation axis AX (i.e., in the θY direction) within a specified angle range. The rotation axis AX is the central axis of the bending needle shaft 13C. The bending needle 9 reciprocates in a manner that the trajectory of the up and down reciprocating motion of the front end portion relative to the sewing machine needle 6 intersects in the X direction. The bending needle 9 has a hook-shaped front end portion. The bending needle 9 has a threading hole for passing the lower thread LT at the front end portion. The bending needle 9 holds the lower thread LT on the inner surface of the threading hole. Each lower thread LT is supplied to each bending needle 9.

[0056] (The movement of sewing machine needle and looper)

[0057] Figure 4 1 is a diagram for explaining an example of the operation of the sewing machine needle 6 and the looper 9 according to the present embodiment. Figure 4 In the figure, the needle plate 8 and the sewing object are omitted.

[0058] The sewing machine needle 6 reciprocates in the Z-axis direction such that the tip of the sewing machine needle 6 alternately switches between a state in which the tip of the sewing machine needle 6 is located closer to the sewing object in the +Z direction and a state in which the tip of the sewing machine needle 6 is located closer to the sewing object in the −Z direction.

[0059] During the reciprocating movement of the sewing machine needle 6, the sewing machine needle 6 penetrates the sewing object. In the following description, within the movable range of the sewing machine needle 6 in the Z-axis direction, the position of the sewing machine needle 6 when the front end of the sewing machine needle 6 is appropriately arranged at the position closest to the +Z direction is called the highest point, and the position of the sewing machine needle 6 when the front end of the sewing machine needle 6 is appropriately arranged at the position closest to the -Z direction is called the lowest point.

[0060] Below, refer to Figure 4 , the steps of performing double loop sewing using a sewing machine needle 6 holding the upper thread UT and a curved needle 9 holding the lower thread LT are described.

[0061] like Figure 4 As shown in (A), the sewing machine needle 6 penetrates the sewing object and passes the upper thread through the thread loop of the lower thread LT to reach the lowest point. The looper 9 passes through the thread loop of the upper thread UT formed by the sewing machine needle 6 in the previous stitch, thereby forming a thread loop of the lower thread LT.

[0062] like Figure 4As shown in (B), when the sewing machine needle 6 rises from the lowest point, the upper thread UT below the sewing object is relaxed, forming a thread loop of the upper thread UT. The bent needle 9 enters the thread loop of the upper thread UT formed by the sewing machine needle 6. At this time, the thread of the upper thread UT is tightened by the cooperation of the thread take-up lever 4 and the cam portion 5 described later. That is, the upper thread UT constituting the thread loop is pulled by the thread take-up lever 4 and pulled upward from the sewing object, so that the thread loop of the upper thread UT is reduced.

[0063] like Figure 4 As shown in (C), if the sewing machine needle 6 reaches the vicinity of the highest point, the curved needle 9 advances to the maximum forward position in the thread loop of the upper thread UT. At this moment, the sewing object is fed by the feeding mechanism (not shown). With the feeding movement of the sewing object, the final thread tightening of the upper thread UT is performed.

[0064] like Figure 4 As shown in (D), if the sewing machine needle 6 starts to descend again, the looper 9 retreats from the thread loop of the upper thread UT. As the looper 9 retreats from the maximum forward position, a thread loop of the lower thread LT is formed. The sewing machine needle 6 enters the thread loop of the lower thread LT and picks up the lower thread LT. After that, the movement of the sewing machine needle 6 and the looper 9 is restored to Figure 4 (A).

[0065] Figure 5 is a schematic diagram of the shape of the stitch formed by the double loop stitch. Figure 5 In the double loop stitch, the sewing object between the upper thread UT and the lower thread LT is omitted. In the double loop stitch, the upper thread UT and the lower thread LT are wound in a chain shape on the lower side of the sewing object to form a stitch woven by the upper thread UT and the lower thread LT.

[0066] exist Figure 4 and Figure 5 In the embodiment, it is described that a stitch is formed by a pair of sewing machine needles 6 and a looper 9, but in the embodiment, three stitches are formed in parallel by three pairs of sewing machine needles 6 and loopers 9. The first upper thread UT1, the second upper thread UT2, and the third upper thread UT3 form stitches by different pairs of sewing machine needles 6 (6A, 6B, 6C) and loopers 9 (9A, 9B, 9C), but the thread is tightened by the same thread take-up lever 4 and cam section 5. The degree of thread tightening can be adjusted by adjusting the position of the cam section 5, but when the sewing completion states of the first upper thread UT1, the second upper thread UT2, and the third upper thread UT3 are deviated, it is difficult to reduce the deviation in the overall position adjustment of the cam section 5. Therefore, in the embodiment, even if the cam section 5 is provided in common for the first upper thread UT1, the second upper thread UT2, and the third upper thread UT3, the degree of thread tightening can be adjusted independently for each upper thread UT.

[0067] (Thread take-up lever and cam)

[0068] Figure 6 This is a perspective view of the thread take-up lever 4 and the cam portion 5 according to the embodiment as viewed from the -X direction. Figure 7 This is a perspective view of the thread take-up lever 4 and the cam portion 5 according to the embodiment as viewed from the +X direction.

[0069] like Figure 3 , Figure 6 and Figure 7 As shown in FIG. 1 , the cam portion 5 is installed so as to extend in the -Y direction from the side surface of the head 2D in the -Y direction in the sewing machine body 2. The cam portion 5 is arranged near the thread take-up lever 4 and is arranged so that the upper thread UT held by the thread take-up lever 4 contacts the cam portion 5. The cam portion 5 has holes 35A, 35B, and 35C (see FIG. 1 ) through which the upper thread UT is inserted. Figure 7 ) cam guide portion 35, first cam 31, second cam 32 and third cam 33, fixing member 34. The thread take-up lever 4 has inlet holes 41A, 41B, 41C and outlet holes 42A, 42B and 42C and a mounting portion 43. Each member constituting the cam portion 5 is made of metal, for example.

[0070] The first online UT1 from Figure 3 The upper thread seat 14A shown in the figure passes through the first upper thread adjuster 10A and the hole 35A of the cam guide 35 (refer to Figure 7 )、The entrance hole 41A of the thread take-up lever 4 (refer to Figure 7 ), the first cam 31, the outlet hole 42A of the thread take-up lever 4 (refer to Figure 6 )、The guide hole 15A of the upper wire guide portion 15 (refer to Figure 6 ), and is supplied to the first sewing machine needle 6A. The second upper thread UT2 is supplied from the upper thread seat 14B to the second sewing machine needle 6B through the second upper thread regulator 10B, the hole 35B of the cam guide 35, the entrance hole 41B of the thread take-up lever 4, the second cam 32, the exit hole 42B of the thread take-up lever 4, and the guide hole 15B of the upper thread guide 15. The third upper thread UT3 is supplied from the upper thread seat 14C to the third sewing machine needle 6C through the third upper thread regulator 10C, the hole 35C of the cam guide 35, the entrance hole 41C of the thread take-up lever 4, the third cam 33, the exit hole 42C of the thread take-up lever 4, and the guide hole 15C of the upper thread guide 15.

[0071] The thread take-up lever 4 is mounted on the needle bar 3 at a mounting portion 43 provided at one end. The thread take-up lever 4 has a shape extending from the mounting portion 43 in the -Y direction and bent in a manner surrounding the cam portion 5. That is, the thread take-up lever 4 has a first portion 4A extending from the mounting portion 43 in the -Y direction, a second portion 4B bent from the end of the first portion 4A in the +X direction, and a third portion 4C extending from the end of the second portion 4B in the +Y direction. The end of the third portion 4C is the other end of the thread take-up lever 4. The first portion 4A is located in the -X direction relative to the cam portion 5, and the third portion 4C is located in the +X direction relative to the cam portion 5. The first portion 4A and the third portion 4C are opposed to each other in the X-axis direction with the cam portion 5 interposed therebetween. In the third portion 4C, inlet holes 41A, 41B, and 41C are formed at intervals in the Y-axis direction. In the first portion 4A, outlet holes 42A, 42B, and 42C are formed at intervals in the Y-axis direction. The inlet holes 41A, 41B, 41C and the outlet holes 42A, 42B, 42C are opposed to each other in the X-axis direction. Thus, the thread take-up lever 4 brings each upper thread UT into contact with the cam portion 5 between the inlet holes 41A, 41B, 41C and the outlet holes 42A, 42B, 42C.

[0072] The first cam 31 , the second cam 32 , and the third cam 33 of the cam portion 5 are arranged in an inner region surrounded by the first portion 4A, the second portion 4B, and the third portion 4C of the thread take-up lever 4 .

[0073] The first cam 31 guides the first upper thread UT1 passing through the thread take-up lever 4 and adjusts the thread tension. The second cam 32 guides the second upper thread UT2 passing through the thread take-up lever 4 and adjusts the thread tension. The third cam 33 guides the third upper thread UT3 passing through the thread take-up lever 4 and adjusts the thread tension. The first cam 31, the second cam 32, and the third cam 33 are provided separately. The first cam 31, the second cam 32, and the third cam 33 are independent components.

[0074] The first cam 31 is arranged on the passage path of the first upper thread UT1 between the entrance hole 41A and the exit hole 42A of the thread take-up lever 4. The first cam 31 has a first guide surface 31A. The first cam 31 guides the first upper thread UT1 moving in the vertical direction together with the thread take-up lever 4 along the first guide surface 31A. The second cam 32 is arranged on the passage path of the second upper thread UT2 between the entrance hole 41B and the exit hole 42B of the thread take-up lever 4. The second cam 32 has a second guide surface 32A. The second cam 32 guides the second upper thread UT2 moving in the vertical direction together with the thread take-up lever 4 along the second guide surface 32A. The third cam 33 is arranged on the passage path of the third upper thread UT3 between the entrance hole 41C and the exit hole 42C of the thread take-up lever 4. The third cam 33 has a third guide surface 33A. The third cam 33 guides the third upper thread UT3 moving in the vertical direction together with the thread take-up lever 4 along the third guide surface 33A.

[0075] Figure 8 It is an exploded perspective view of the cam portion 5 according to the embodiment. Fig. 9 It is a front view showing the cam portion 5 in a state where the screw member 37 is removed.

[0076] like Figure 8 As shown, the first guide surface 31A is formed on a part of the outer peripheral surface of the first cam 31. The first guide surface 31A is a side surface on the -Y direction side of the first cam 31. The first guide surface 31A is a surface of the first cam 31 that is open to the outside. In other words, the first guide surface 31A is not the inner peripheral surface of the through-hole (through hole, slit, etc.) that penetrates the first cam 31, but is a surface exposed to the outside of the first cam 31. The first guide surface 31A is polished to become a smooth surface to avoid damage and fray of the upper wire UT due to contact with the upper wire UT. The first guide surface 31A extends in the Z-axis direction (up and down direction) as a whole, and is composed of a curved surface having a top 31B protruding in the -Y direction. The top 31B is formed at a position on the lower end side between the upper end and the lower end of the first guide surface 31A. The first guide surface 31A has a lower inclined surface 31C inclined from the lower end of the first guide surface 31A toward the top 31B and an upper inclined surface 31D inclined from the upper end toward the top 31B.

[0077] The first cam 31 has screw insertion portions 36A at one end (upper end) and the other end (lower end). The screw insertion portion 36A is a through hole that penetrates the first cam 31. The screw insertion portion 36A is a long hole that is long in the Y-axis direction.

[0078] The second guide surface 32A is formed on a part of the outer peripheral surface of the second cam 32. The second guide surface 32A is a side surface on the -Y direction side of the second cam 32. The second guide surface 32A is a surface of the second cam 32 that is open to the outside. In other words, the second guide surface 32A is a surface exposed on the outside of the second cam 32. The second guide surface 32A is polished to become a smooth surface to avoid damage and wear to the upper line UT due to contact with the upper line UT. The second guide surface 32A extends in the Z-axis direction (up and down direction) as a whole, and is composed of a curved surface having a top 32B protruding in the -Y direction. The top 32B is formed at a position on the lower end side between the upper end and the lower end of the second guide surface 32A. The second guide surface 32A has a lower inclined surface 32C inclined from the lower end of the second guide surface 32A toward the top 32B and an upper inclined surface 32D inclined from the upper end toward the top 32B.

[0079] The third cam 33 has screw insertion portions 36B at one end (upper end) and the other end (lower end). The screw insertion portion 36B is a through hole that penetrates the third cam 33. The screw insertion portion 36B is a long hole that is long in the Y-axis direction.

[0080] The third guide surface 33A is formed on a part of the outer peripheral surface of the third cam 33. The third guide surface 33A is a side surface on the -Y direction side of the third cam 33. The third guide surface 33A is a surface of the third cam 33 that is open to the outside. In other words, the third guide surface 33A is a surface exposed on the outside of the third cam 33. The third guide surface 33A is polished to become a smooth surface to avoid damage and wear of the upper line UT due to contact with the upper line UT. The third guide surface 33A extends in the Z-axis direction (up and down direction) as a whole, and is composed of a curved surface having a top 33B protruding in the -Y direction. The top 33B is formed at a position on the lower end side between the upper end and the lower end of the third guide surface 33A. The third guide surface 33A has a lower inclined surface 33C inclined from the lower end of the third guide surface 33A toward the top 33B and an upper inclined surface 33D inclined from the upper end toward the top 33B.

[0081] The third cam 33 has screw insertion portions 36C at one end (upper end) and the other end (lower end). The screw insertion portion 36C is a through hole that penetrates the third cam 33. The screw insertion portion 36C is a long hole that is long in the Y-axis direction.

[0082] The first cam 31, the second cam 32, and the third cam 33 are each mounted on a fixing member 34. The fixing member 34 includes a first fixing member 34A fixing one end (upper end) of each cam, and a second fixing member 34B fixing one end (lower end) of each cam. The first fixing member 34A and the second fixing member 34B are respectively fixed to the head 2D of the sewing machine body 2.

[0083] The first fixing member 34A is provided with a cam guide 35. The first fixing member 34A has a first threaded hole 34A1 for fixing one end of the first cam 31, a second threaded hole 34A2 for fixing one end of the second cam 32, and a third threaded hole 34A3 for fixing one end of the third cam 33. The first threaded hole 34A1, the second threaded hole 34A2, and the third threaded hole 34A3 are arranged in the Y-axis direction. The second fixing member 34B has a first threaded hole 34B1 for fixing the other end of the first cam 31, a second threaded hole 34B2 for fixing one end of the second cam 32, and a third threaded hole 34B3 for fixing one end of the third cam 33. The first threaded hole 34B1, the second threaded hole 34B2, and the third threaded hole 34B3 are arranged in the Z-axis direction.

[0084] The first cam 31, the second cam 32, and the third cam 33 are mounted on the fixing member 34 in such a manner that they can be adjusted in the adjustment direction of approaching and moving away from the needle bar 3. In the embodiment, the adjustment direction is the Y-axis direction. Since the sewing needle 6 is mounted on the lower end of the needle bar 3, when the distance between the first cam 31, the second cam 32, and the third cam 33 and the needle bar 3 in the Y-axis direction changes, the path length of the upper thread UT from the first cam 31, the second cam 32, and the third cam 33 to the corresponding sewing needle (the first sewing needle 6A, the second sewing needle 6B, and the third sewing needle 6C) will change.

[0085] The first cam 31 is mounted on the fixing member 34 by a screw member 37 passing through the screw insertion portion 36A. One end of the first cam 31 is fastened to the first fixing member 34A by a screw member 37 mounted in the first threaded hole 34A1 via the screw insertion portion 36A. The other end of the first cam 31 is fastened to the second fixing member 34B by a screw member 37 mounted in the first threaded hole 34B1 via the screw insertion portion 36A.

[0086] The second cam 32 is mounted on the fixing member 34 by means of a screw member 37 passing through the screw insertion portion 36B. One end of the second cam 32 is fastened to the first fixing member 34A by means of a screw member 37 mounted in the second threaded hole 34A2 via the screw insertion portion 36B. The other end of the second cam 32 is fastened to the second fixing member 34B by means of a screw member 37 mounted in the second threaded hole 34B2 via the screw insertion portion 36B.

[0087] The third cam 33 is mounted on the fixing member 34 by means of a screw member 37 passing through the screw insertion portion 36C. One end of the third cam 33 is fastened to the first fixing member 34A by means of a screw member 37 mounted in the third threaded hole 34A3 via the screw insertion portion 36C. The other end of the third cam 33 is fastened to the second fixing member 34B by means of a screw member 37 mounted in the third threaded hole 34B3 via the screw insertion portion 36C.

[0088] like Fig. 9As shown, the first cam 31, the second cam 32, and the third cam 33 are arranged in a row. The first cam 31, the second cam 32, and the third cam 33 are arranged in the Y-axis direction. The length of the screw insertion portion (36A, 36B, 36C) of each of the first cam 31, the second cam 32, and the third cam 33 in the Y-axis direction is larger than the diameter of each threaded hole of the first fixing member 34A and the second fixing member 34B (that is, the diameter of the shaft portion of the screw member 37). Therefore, the first cam 31 can change the installation position of the first cam 31 in the Y-axis direction (adjustment direction) within the range of the gap CL between the screw member 37 and the screw insertion portion 36A by loosening each screw member 37. Similarly, the second cam 32 can change the installation position of the second cam 32 in the Y-axis direction (adjustment direction) within the range of the gap between the screw member 37 and the screw insertion portion 36B by loosening each screw member 37. The third cam 33 can be installed in a position that can be changed in the Y-axis direction (adjustment direction) within the range of the gap between the screw member 37 and the screw insertion portion 36C by loosening each screw member 37. With such a structure, the first cam 31, the second cam 32, and the third cam 33 are installed in a positionally adjustable manner.

[0089] The second cam 32 has an opposing surface 32E (see FIG. 32E ) on the side of the outer peripheral surface opposite to the second guide surface 32A, which is opposed to the first cam 31. Figure 8 ). The opposing surface 32E is spaced apart from the first guide surface 31A and is opposed to the first guide surface 31A in the Y-axis direction. Thus, the cam portion 5 forms a slit-shaped linear path TP1 surrounded by the inner peripheral surface with the first guide surface 31A and the opposing surface 32E as the inner peripheral surface. That is, the first guide surface 31A is the outer peripheral surface of the first cam 31 that is open to the outside, but by combining the first cam 31 (first guide surface 31A) and the second cam 32 (opposing surface 32E), a closed linear path TP1 is formed (refer to Fig. 9 ).

[0090] Similarly, the third cam 33 has an opposing surface 33E (see FIG. 3E ) on the side of the outer peripheral surface opposite to the third guide surface 33A, which is opposed to the second cam 32. Figure 8 ). The facing surface 33E is spaced apart from the second guide surface 32A and faces the second guide surface 32A in the Y-axis direction. Thus, the cam portion 5 forms a slit-shaped line passage TP2 surrounded by the inner peripheral surface with the second guide surface 32A and the facing surface 33E as the inner peripheral surface (see Fig. 9 ).

[0091] When the position of the first cam 31 is adjusted in the +Y direction or the position of the second cam 32 is adjusted in the -Y direction, a gap is formed between the upper end of the first guide surface 31A and the upper end of the opposing surface 32E, but the gap is blocked by the lower surface BS of the first fixing member 34A (see Figure 8 Therefore, even if the first cam 31 and the second cam 32 are offset in the Y-axis direction, the line passage TP1 remains closed. The same is true for the line passage TP2.

[0092] (Function of thread take-up lever and cam)

[0093] Next, the operations of the thread take-up lever 4 and the cam portion 5 will be described. Fig.10 1 is a schematic diagram showing the positional relationship between the thread take-up lever 4 and the cam portion 5 when the thread take-up lever 4 is located near the lower inclined surface of the cam portion 5 . Fig.11 1 is a schematic diagram showing the positional relationship between the thread take-up lever 4 and the cam portion 5 when the thread take-up lever 4 is located near the top of the cam portion 5 . Fig.12 Yes means Fig.11 Schematic diagram of the cross section of the thread take-up lever 4 and the cam portion 5. Fig.13 Schematic diagram showing the positional relationship between the thread take-up lever 4 and the cam portion 5 when the thread take-up lever 4 is located near the upper inclined surface of the cam portion 5. Fig.10 , Fig.11 and Fig.13 In the figure, the thread take-up lever 4 is indicated by a dotted line.

[0094] The thread take-up lever 4 moves up and down in conjunction with the needle bar 3, so that the held upper thread UT moves up and down while in contact with the cam portion 5. The contact position between the cam portion 5 and the upper thread UT changes with the movement of the thread take-up lever 4. The cam portion 5 changes the path length of the upper thread UT (the path length from the upper thread regulator 10 to the sewing machine needle 6) in accordance with each contact position with the upper thread UT. The cam portion 5 achieves thread tightening by changing the path length of the upper thread UT.

[0095] like Fig.10 and Figure 4 As shown in (B), when the sewing machine needle 6 starts to rise from the vicinity of the lowest point, the thread take-up lever 4 moves the formation position of the lower inclined surface (31C, 32C, 33C) of the cam portion 5 in the +Z direction. Fig.10 In the embodiment, the positions of the inlet holes 41A, 41B, 41C and the outlet holes 42A, 42B, 42C of the thread take-up lever 4 do not reach the corresponding lower inclined surfaces (31C, 32C, 33C), so each upper thread UT passes through the straight path connecting the inlet hole and the outlet hole. Fig.10When the thread take-up lever 4 moves in the +Z direction, each upper thread UT contacts the corresponding lower inclined surface 31C, 32C, 33C, and each upper thread UT bends along the lower inclined surface 31C, 32C, 33C. As each upper thread UT approaches the top 31B, 32B, 33B, the contact position of each upper thread UT with the lower inclined surface 31C, 32C, 33C gradually shifts in the -Y direction.

[0096] like Fig.11 and Fig.12 As shown, after the curved needle 9 enters the wire loop of the upper wire UT (refer to Figure 4 (B)), the upper threads UT of the thread take-up lever 4 reach the positions of the tops 31B, 32B, and 33B of the cam portion 5. At this time, Fig.12 As shown, the degree of deviation of the contact position (P1, P2, P3) between the upper thread UT and the cam portion 5 is the largest. Each upper thread UT is bent between the inlet hole (41A, 41B, 41C) and the outlet hole (42A, 42B, 42C) by the deviation, thereby increasing the path length to the sewing machine needle 6. The upper thread UT is pulled from the sewing machine needle 6 to loosen (thread loop) according to the increment of the path length from the thread take-up lever 4 and the cam portion 5 to the sewing machine needle 6. Thus, until the thread take-up lever 4 passes through the top (31B, 32B, 33B) from the lower inclined surface (31C, 32C, 33C) of the cam portion 5, the upper thread UT is gradually pulled from the sewing machine needle 6 to tighten the thread.

[0097] like Fig.13 As shown, after the thread take-up lever 4 passes the top of the cam portion 5, the upper thread UT is guided along the upper inclined surfaces 31D, 32D, and 33D until it reaches the highest point. In this process, since the deviation of the contact position between the upper thread UT and the cam portion 5 is reduced, the tension of the upper thread UT is gradually relaxed.

[0098] In the embodiment, the first cam 31, the second cam 32 and the third cam 33 can each be positionally adjusted, so that the positions of the upper lines UT can be adjusted independently. Fig.12 That is, by adjusting the position of the first cam 31, the Y-axis distance from the inlet hole 41A and the outlet hole 42A of the thread take-up lever 4 to the contact position P1 of the first upper thread UT1 and the first cam 31 can be adjusted. As a result, the degree of thread tightening can be adjusted according to the change in the path length of the first upper thread UT1 passing through the inlet hole 41A, the contact position P1, and the outlet hole 42A.

[0099] Similarly, by adjusting the position of the second cam 32, the distance from the entrance hole 41B and the exit hole 42B of the thread take-up lever 4 to the contact position P2 of the second upper thread UT2 and the second cam 32 can be adjusted. As a result, the thread tightening degree can be adjusted according to the change in the path length of the second upper thread UT2 passing through the entrance hole 41B, the contact position P2, and the exit hole 42B. By adjusting the position of the third cam 33, the distance from the entrance hole 41C and the exit hole 42C of the thread take-up lever 4 to the contact position P3 of the third upper thread UT3 and the third cam 33 can be adjusted. As a result, the thread tightening degree can be adjusted according to the change in the path length of the third upper thread UT3 passing through the entrance hole 41C, the contact position P3, and the exit hole 42C. As a result, even if there is a deviation in the sewing completion of each upper thread UT, the sewing completion of each of the first upper thread UT1, the second upper thread UT2, and the third upper thread UT3 can be adjusted independently.

[0100] When the thread of any one of the first upper thread UT1, the second upper thread UT2, and the third upper thread UT3 is tightened too strongly, the sewing operator adjusts the position of the corresponding cam among the first cam 31, the second cam 32, and the third cam 33 in the +Y direction. When the thread of any one of the first upper thread UT1, the second upper thread UT2, and the third upper thread UT3 is tightened too weakly, the sewing operator adjusts the position of the corresponding cam among the first cam 31, the second cam 32, and the third cam 33 in the -Y direction. In this way, the stitches of the first upper thread UT1, the second upper thread UT2, and the third upper thread UT3 can be completed uniformly, forming uniform stitches.

[0101] (Effect)

[0102] As described above, according to the present embodiment, the sewing machine 1 comprises: a needle bar 3, which holds the first sewing machine needle 6A and the second sewing machine needle 6B and is driven in the up-down direction; a thread take-up lever 4, through which the first upper thread UT1 supplied to the first sewing machine needle 6A and the second upper thread UT2 supplied to the second sewing machine needle 6B are inserted, and which moves in conjunction with the needle bar 3; a cam portion 5, which includes a first cam 31 and a second cam 32, the first cam 31 guides the first upper thread UT1 passing through the thread take-up lever 4 and adjusts the thread tension, and the second cam 32 is separately provided with the first cam 31, guides the second upper thread UT2 passing through the thread take-up lever 4 and adjusts the thread tension; and a sewing machine body 2, which is provided with the needle bar 3, the thread take-up lever 4 and the cam portion 5, and the first cam 31 and the second cam 32 are respectively installed in a manner that allows position adjustment relative to the sewing machine body 2.

[0103] Thus, the following can be done independently: the adjustment of the thread tightening of the first upper thread UT1 based on the position adjustment of the first cam 31, and the adjustment of the thread tightening of the second upper thread UT2 based on the position adjustment of the second cam 32. Thus, it is possible to make the sewing completion based on the first sewing machine needle 6A and the first upper thread UT1 consistent with the sewing completion based on the second sewing machine needle 6B and the second upper thread UT2. As a result, in the sewing machine 1 having a cam-type thread take-up lever and using a plurality of upper threads UT, the sewing completion of each thread can be made consistent. In the embodiment, the cam portion 5 further has a third cam 33, and the first cam 31, the second cam 32, and the third cam 33 are respectively installed in a manner that allows position adjustment relative to the sewing machine body 2, so that adjustment can be made so that the sewing completion of the first upper thread UT1, the second upper thread UT2, and the third upper thread UT3 are consistent.

[0104] In addition, in the present embodiment, the first cam 31 has a first guide surface 31A open to the outside on a part of the outer peripheral surface, and the first upper thread UT1 moving in the vertical direction together with the thread take-up lever 4 is guided along the first guide surface 31A. The second cam 32 has a second guide surface 32A open to the outside on a part of the outer peripheral surface, and the second upper thread UT2 moving in the vertical direction together with the thread take-up lever 4 is guided along the second guide surface 32A. Thus, the first guide surface 31A and the second guide surface 32A can be formed as an outer peripheral surface open to the outside, rather than an inner peripheral surface of a slit or the like. Thus, the first guide surface 31A and the second guide surface 32A for sliding the upper thread UT can be polished to be smooth easily and evenly. For example, when the guide surface is formed on the inner peripheral surface of a long and narrow slit, a polishing operation using a precision grinder (a polisher is provided on the front end chuck of an electric drill) or the like is required. In contrast, in the present embodiment where the guide surface is formed on the outer peripheral surface, a polishing device that can easily and evenly polish a wide range can be used for polishing.

[0105] In addition, in the present embodiment, the second cam 32 has an opposing surface 32E on the side of the outer circumference opposite to the second guide surface 32A, which is opposed to the first cam 31, and the cam portion 5 forms a slit-shaped thread passage surrounded by the inner circumference, with the first guide surface 31A and the opposing surface 32E as the inner circumference. Thus, the first guide surface 31A can be formed on the outer circumference of the first cam 31, and the area along the first guide surface 31A for guiding the first upper thread UT1 can be configured as a closed thread passage TP1. Thus, for example, it is possible to prevent the operator from mistakenly moving the upper thread UT during sewing preparation, and the first upper thread UT1 from accidentally moving toward the second guide surface 32A.

[0106] In addition, in the present embodiment, the cam portion 5 has a fixing member 34, the fixing member 34 is fixed to the sewing machine body 2, and the first cam 31 and the second cam 32 are mounted thereon, and the first cam 31 and the second cam 32 are mounted on the fixing member 34 in a manner that allows position adjustment in the adjustment direction (Y-axis direction) for approaching and moving away from the needle bar 3. The first cam 31 and the second cam 32 can be easily mounted and position adjusted with respect to the common fixing member 34. In addition, the first cam 31 and the second cam 32 respectively have screw insertion portions 36A, 36B, and 36C formed in a manner extending in the adjustment direction (Y-axis direction), and are mounted on the fixing member 34 by means of screw members 37 passing through the screw insertion portions 36A, 36B, and 36C. Thus, the first cam 31 and the second cam 32 can be respectively positionally adjusted with a simple structure.

[0107] The technical scope of the present disclosure is not limited to the above-described embodiments, and appropriate changes can be made within the scope not departing from the gist of the present disclosure.

[0108] For example, in the above-mentioned embodiment, an example of providing three cams, namely, the first cam 31, the second cam 32, and the third cam 33, is shown, but only the first cam 31 and the second cam 32 may be provided in the cam portion 5, or four or more cams may be provided. The cams may be provided according to the number of upper threads (the number of sewing machine needles) used.

[0109] For example, in the above-mentioned embodiment, the first guide surface 31A is provided as a part of the outer peripheral surface of the first cam 31 and the second guide surface 32A is provided as a part of the outer peripheral surface of the second cam 32 and is open to the outside, but the first guide surface 31A may be formed by the inner peripheral surface of the through hole (slit) formed in the flat plate-shaped first cam 31. The second guide surface 32A may be formed by the inner peripheral surface of the through hole (slit) formed in the flat plate-shaped second cam 32.

Claims

1. A sewing machine comprising: A needle bar, which holds the first sewing machine needle and the second sewing machine needle and is driven in the up-down direction; a thread take-up lever, through which a first upper thread supplied to the first sewing machine needle and a second upper thread supplied to the second sewing machine needle are inserted, and which moves in conjunction with the needle bar; The cam portion includes a first cam and a second cam, wherein the first cam guides the first upper thread passing through the thread take-up lever and adjusts the thread tightening, and the second cam is provided separately from the first cam and guides the second upper thread passing through the thread take-up lever and adjusts the thread tightening; as well as The sewing machine body is provided with the needle bar, the thread take-up lever and the cam portion. The first cam and the second cam are respectively mounted on the sewing machine body in a manner that allows position adjustment.

2. The sewing machine according to claim 1, characterized in that: The first cam has a first guide surface open to the outside on a part of the outer peripheral surface, and guides the first upper thread moving in the vertical direction together with the thread take-up lever along the first guide surface. The second cam has a second guide surface open to the outside on a part of the outer peripheral surface, and guides the second upper thread moving in the vertical direction together with the thread take-up lever along the second guide surface.

3. The sewing machine according to claim 2, characterized in that: The first cam and the second cam are arranged in an array, The second cam has an opposing surface facing the first cam on the side of the outer peripheral surface opposite to the second guide surface. The cam portion forms a slit-shaped wire passage having the first guide surface and the facing surface as inner peripheral surfaces and surrounded by the inner peripheral surfaces.

4. The sewing machine according to any one of claims 1 to 3, characterized in that The cam portion has a fixing component, which is fixed to the sewing machine body and has the first cam and the second cam installed thereon. The first cam and the second cam are mounted on the fixing member so as to be positionally adjustable in an adjustment direction for approaching and moving away from the needle bar.

5. The sewing machine according to claim 4, characterized in that The first cam and the second cam each have a screw insertion portion formed to extend in the adjustment direction, and are attached to the fixing member using a screw member passing through the screw insertion portion.

6. The sewing machine according to any one of claims 1 to 3, characterized in that The needle bar also holds a third sewing machine needle, The thread take-up lever is also used to insert the third upper thread supplied to the third sewing machine needle. The cam portion further includes a third cam, and the third cam guides the third upper thread passing through the thread take-up lever and adjusts the thread tension. The first cam, the second cam, and the third cam are respectively mounted on the sewing machine body in a manner that allows position adjustment.

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