A cloth-piercing mechanism with variable needle bar stroke and a sewing machine

Abstract

The present invention provides a piercing mechanism and a sewing machine with a variable needle bar stroke. The piercing mechanism includes a needle bar eccentric, an adjuster, an adjusting connecting rod, an adjusting crank, an adjusting drive unit, a needle bar connecting rod, a needle bar connecting column, a needle bar, and a needle mounted at the lower end of the needle bar. The needle bar eccentric has an eccentric connecting shaft. The eccentric connecting shaft, one end of the adjusting connecting rod, and one end of the needle bar connecting rod are all hinged to the adjuster. The hinge points of the eccentric connecting shaft and the adjuster, the adjusting connecting rod and the adjuster, and the needle bar connecting rod and the adjuster are staggered. The other end of the adjusting connecting rod is hinged to the adjusting crank, and the other end of the needle bar connecting rod is hinged to the needle bar connecting column, which is fixed to the needle bar. When the adjusting drive unit acts on the adjusting crank, it drives the adjusting crank to rotate, changing the position angle of the adjuster. The present invention enables switching between different needle bar strokes in a single sewing machine, cost-effectively meeting the different needle bar stroke requirements for thin, medium, and thick fabrics.

Description

Technical Field

[0001] The present invention relates to the technical field of sewing machines, in particular to a cloth-piercing mechanism with a variable needle bar stroke and a sewing machine comprising the cloth-piercing mechanism with a variable needle bar stroke. Background Art

[0002] Sewing machines are equipped with a needle bar mechanism, which is used to realize the reciprocating movement of the needle and drive the needle to perform the cloth-piercing action. Figure 1 As shown, it is a crank slider mechanism, which mainly includes a needle bar crank 100, a needle bar connecting rod 200, a connecting column 300, a needle bar 400 extending vertically, and a needle 500 mounted at the lower end of the needle bar. The needle bar crank 100 is fixed to the upper shaft (i.e., the main shaft) of the sewing machine. One end of the needle bar connecting rod 200 is hinged to the needle bar crank 100, and the other end of the needle bar connecting rod 200 is hinged to the connecting column 300, which is fixed to the needle bar 400. When the sewing machine is running, the upper shaft rotates, and the crank slider mechanism composed of the needle bar crank 100, needle bar connecting rod 200, and connecting column 300 drives the needle bar 400 to reciprocate up and down. The needle 500 reciprocates up and down synchronously with the needle bar 400 to pierce the fabric.

[0003] In existing needle bar mechanisms, the reciprocating stroke of the needle bar and needle is determined by the mechanism's parameters. Fixed models correspond to fixed needle bar and needle strokes (i.e., puncture strokes). However, common lockstitch sewing machines require different needle bar strokes for sewing thin, medium, and thick materials. Specifically, there are derivative models of lockstitch sewing machines with different needle bar strokes for thin, medium, and thick materials. This is inconvenient for customers who frequently change styles and materials, and is also very costly. Summary of the Invention

[0004] In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide a puncturing mechanism with a variable needle bar stroke, which can switch between different needle bar strokes in one sewing machine.

[0005] To achieve the above-mentioned objectives, the present invention provides a cloth-piercing mechanism with variable needle bar stroke, comprising a needle bar eccentric wheel fixed on the upper shaft of a sewing machine, an adjuster, an adjusting link, an adjusting crank with a fixed rotating fulcrum, an adjusting drive unit, a needle bar link, a needle bar connecting column, a needle bar, and a machine needle installed at the lower end of the needle bar, wherein the needle bar eccentric wheel has an eccentric connecting shaft, and the eccentric connecting shaft, one end of the adjusting link and one end of the needle bar link are all hinged to the adjuster, and the hinge points of the eccentric connecting shaft and the adjuster, the hinge points of the adjusting link and the adjuster, and the hinge points of the needle bar link and the adjuster are staggered, the other end of the adjusting link is hinged to the adjusting crank, and the other end of the needle bar link is hinged to the needle bar connecting column, and the needle bar connecting column is fixed on the needle bar; when the adjusting drive unit acts on the adjusting crank, it drives the adjusting crank to rotate, thereby changing the position angle of the adjuster.

[0006] Furthermore, the adjustment drive unit includes an adjusting screw and a tension spring. The adjusting screw is threadedly connected to the sewing machine housing and abuts against the adjusting crank. One end of the tension spring is fixed and the other end is connected to the adjusting crank. The spring force applied by the tension spring to the adjusting crank causes the adjusting crank to have a tendency to rotate closer to the adjusting screw.

[0007] Furthermore, the adjustment drive unit further includes a locking nut, which is threadedly connected to the adjustment screw, and the locking nut is located outside the sewing machine casing and abuts against the outer surface of the sewing machine casing.

[0008] Furthermore, a first scale representing the needle rod stroke is provided on the outer surface of the adjusting screw.

[0009] Furthermore, the adjustment drive unit includes a locking screw and a rotation slot provided on the adjustment crank. The locking screw is threadedly connected in the sewing machine housing and abuts against the adjustment crank.

[0010] Furthermore, the cloth-piercing mechanism also includes a scale plate fixed to the sewing machine housing, the scale plate is provided with a second scale representing the needle bar stroke, and the adjusting crank is provided with a pointing portion pointing to the second scale.

[0011] Furthermore, the adjustment drive unit includes a drive motor, and the adjustment crank is fixed on a motor shaft of the drive motor.

[0012] Furthermore, the cloth-piercing mechanism also includes a fixed guide rail and a needle bar slider, the fixed guide rail is provided with a downward extending slide groove, the needle bar connecting column includes a column body portion fixed on the needle bar, and a column connecting shaft portion extending from the column body portion, the column connecting shaft portion is rotatably passed through the needle bar connecting rod and the needle bar slider, and the needle bar slider can be assembled in the slide groove so as to move up and down.

[0013] The present application also provides a sewing machine, in which the cloth-piercing mechanism with variable needle bar stroke as described above is configured.

[0014] As described above, the cloth-piercing mechanism and sewing machine with variable needle bar stroke according to the present invention have the following beneficial effects:

[0015] In the present application, when the adjustment drive unit is not in operation, the current position angle of the adjustment crank is maintained, and the position angle of the regulator does not change, and the stroke of the upper shaft driving the needle bar and the machine needle to move back and forth up and down through the needle bar eccentric, the regulator, the needle bar connecting rod and the needle bar connecting column remains unchanged; when the adjustment drive unit is in operation, the adjustment crank is driven to rotate, and the adjustment crank drives the regulator to rotate around the eccentric connecting shaft through the adjustment connecting rod, and the position angle of the regulator changes, which also changes the stroke of the upper shaft driving the needle bar and the machine needle to move back and forth up and down through the needle bar eccentric, the regulator, the needle bar connecting rod and the needle bar connecting column, thereby achieving the adjustment of the needle bar stroke. Therefore, the piercing mechanism involved in the present application can adjust the needle bar stroke, and can switch different needle bar strokes in a sewing machine, so as to meet the different requirements of thin, medium and thick fabrics for the needle bar stroke at a low cost, while also improving convenience and eliminating the need to replace the machine. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural diagram of the needle bar mechanism in the prior art.

[0017] Figure 2 This is a structural diagram of the first embodiment of the cloth-piercing mechanism with variable needle bar stroke of the present application.

[0018] Figure 3 and Figure 4 for Figure 2 Schematic diagram of the structure of the sewing machine at different viewing angles after omitting the sewing machine casing.

[0019] Figure 5 This is a schematic diagram of the first embodiment of the cloth-piercing mechanism with variable needle bar stroke of this application.

[0020] Figure 6 This is a schematic diagram of the adjustment change of the needle bar stroke in the first embodiment of the cloth-piercing mechanism with variable needle bar stroke of this application.

[0021] Figure 7 and Figure 8 This is a structural schematic diagram of the second embodiment of the cloth-piercing mechanism with variable needle bar stroke at different viewing angles.

[0022] Figure 9 This is a structural diagram of the third embodiment of the application for a puncturing mechanism with variable needle bar stroke.

[0023] Figure 10 This is a schematic structural diagram of the needle bar eccentric wheel in this application.

[0024] Figure 11 This is a schematic structural diagram of the needle rod connecting column in this application.

[0025] Component number description

[0026] 10 Upper shaft

[0027] 20 Needle bar eccentric

[0028] 21 Eccentric connecting shaft

[0029] 30 Regulator

[0030] 40 Adjusting connecting rod

[0031] 50 Adjusting the crank

[0032] 51 Rotating Slot

[0033] 52 Pointing part

[0034] 53 crank body

[0035] 54 Crank adjustment pin

[0036] 61 Adjusting screw

[0037] 611 First Scale

[0038] 62 tension spring

[0039] 63 Lock nut

[0040] 64 Locking screw

[0041] 65 drive motor

[0042] 70 needle bar connecting rod

[0043] 80 Needle bar connecting column

[0044] 81 Column body part

[0045] 82 Column connecting shaft

[0046] 90 needle bar

[0047] 110 needle

[0048] 120 sewing machine case

[0049] 130 scale plate

[0050] 131 Second Scale

[0051] 140 fixed rail

[0052] 141 Chute

[0053] 150 Needle bar slide DETAILED DESCRIPTION

[0054] The following describes the implementation of the present invention through specific embodiments. People skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification.

[0055] It should be noted that the structures, proportions, sizes, etc. depicted in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the conditions for the implementation of the present invention. Therefore, they have no substantial technical significance. Any modification of the structure, change in the proportional relationship or adjustment of the size should still fall within the scope of the technical content disclosed by the present invention without affecting the efficacy and purpose of the present invention. At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" quoted in this specification are only for the convenience of description and are not used to limit the scope of the implementation of the present invention. Changes or adjustments in their relative relationships should also be regarded as the scope of the implementation of the present invention without substantially changing the technical content.

[0056] The present application provides a sewing machine, and in particular provides a cloth-piercing mechanism with a variable needle bar stroke for the sewing machine. The sewing machine is a flat sewing machine. Figure 2 As shown, the sewing machine comprises a sewing machine housing 120, an upper shaft 10 rotatably mounted within the sewing machine housing 120, and a main motor that drives the upper shaft 10. The upper shaft 10 is also referred to as the main shaft of the sewing machine. For ease of description, in the following embodiments, the axial direction of the upper shaft 10 is defined as the left and right directions, with the direction from the upper shaft 10 pointing toward the sewing machine head being the left direction and the direction from the upper shaft 10 pointing toward the sewing machine tail being the right direction. The direction of movement of the fabric during forward sewing of the sewing machine is defined as the forward direction.

[0057] like Figures 2 to 5 ,or Figure 7 and Figure 8 ,or Figure 9 As shown, the needle bar stroke variable puncturing mechanism involved in the present application includes a needle bar eccentric wheel 20, an adjuster 30, an adjusting connecting rod 40, an adjusting crank 50 with a fixed rotation fulcrum, an adjusting drive unit, a needle bar connecting rod 70, a needle bar connecting column 80, a needle bar 90, and a needle 110 installed at the lower end of the needle bar 90; wherein the needle bar eccentric wheel 20 is fixed to the left end of the upper shaft 10 of the sewing machine by a screw, as shown in FIG. Figure 10As shown, the left end face of the needle bar eccentric wheel 20 is provided with an eccentric connecting shaft 21 extending straight to the left as a whole, and the eccentric connecting shaft 21 is eccentrically arranged with the upper shaft 10; the eccentric connecting shaft 21, one end of the adjusting link 40 and one end of the needle bar link 70 are all hinged to the regulator 30, and the hinge point of the eccentric connecting shaft 21 and the regulator 30, the hinge point of the adjusting link 40 and the regulator 30, and the hinge point of the needle bar link 70 and the regulator 30 are staggered; the other end of the adjusting link 40 is hinged to the adjusting crank 50, and the hinge point of the adjusting crank 50 and the adjusting link 40 is staggered with the fixed rotating fulcrum of the adjusting crank 50; the other end of the needle bar link 70 is hinged to the needle bar connecting column 80; the needle bar connecting column 80 is fixed on the needle bar 90.

[0058] Preferably, the middle part of the regulator 30 is sleeved on the eccentric connecting shaft 21 of the needle bar eccentric wheel 20, and the two are rotated together through a bearing, thereby realizing the hinge connection between the regulator 30 and the eccentric connecting shaft 21; pins are fixed at both ends of the regulator 30, the pin at one end is passed through the adjusting link 40, and is rotated together through a bearing, thereby realizing the hinge connection between the regulator 30 and the adjusting link 40; the pin at the other end is passed through the needle bar link 70, and is rotated together through a bearing, thereby realizing the hinge connection between the regulator 30 and the needle bar link 70.

[0059] During normal sewing, the adjustment drive unit is inactive. The adjustment drive unit maintains the current position angle of the adjustment crank 50, which in turn maintains the current position angle of the adjuster 30 via the adjustment link 40, preventing the position angle of the adjuster 30 from changing. Consequently, the upper shaft 10, through the needle bar eccentric 20, adjuster 30, needle bar link 70, and needle bar connecting post 80, drives the needle bar 90 and needle 110 to move up and down, reciprocatingly, and the needle bar stroke, also known as the puncturing stroke, remains unchanged. When the needle bar stroke needs to be adjusted, the adjustment drive unit activates, driving the adjustment crank 50 to rotate about its fixed pivot point. The adjustment crank 50, through the adjustment link 40, drives the adjuster 30 to rotate about the eccentric connecting shaft 21, causing the position angle of the adjuster 30 to change. This, in turn, changes the upper shaft 10, through the needle bar eccentric 20, adjuster 30, needle bar link 70, and needle bar connecting post 80, driving the needle bar 90 and needle 110 to move up and down, reciprocatingly, thereby adjusting the needle bar stroke. Furthermore, the adjuster 30 is hinged relative to the eccentric connecting shaft 21, and the two move relative to each other during the needle-stitching process. Adjustment is unrestricted and can be made at any position when the machine is stopped, or even during high-speed operation. Therefore, the needle-stitching mechanism of the present application is capable of adjusting the needle bar stroke, enabling different needle bar strokes to be switched within a single sewing machine, cost-effectively meeting the varying needle bar stroke requirements for thin, medium, and thick fabrics. This also improves convenience by eliminating the need to change machines.

[0060] Furthermore, the adjustment drive unit has multiple embodiments, and accordingly the puncturing mechanism with variable needle bar stroke has multiple embodiments. The following provides three preferred embodiments of the puncturing mechanism with variable needle bar stroke.

[0061] Example 1 of a cloth-piercing mechanism with variable rod stroke

[0062] like Figures 3 to 5 As shown, the adjustment drive unit includes an adjustment screw 61 and a tension spring 62. The adjustment screw 61 extends vertically and is threadedly connected to the sewing machine housing 120. The lower end of the adjustment screw 61 abuts against the adjustment crank 50, and the abutment point is offset from the fixed rotation fulcrum of the adjustment crank 50. One end of the tension spring 62 is fixed and the other end is connected to the adjustment crank 50. The spring force exerted by the tension spring 62 on the adjustment crank 50 causes the adjustment crank 50 to rotate toward the adjustment screw 61, so that the adjustment crank 50 and the adjustment screw 61 are closely attached, thereby improving the adjustment accuracy of the needle bar stroke. Preferably, the adjustment crank 50 includes a crank body 53 and a crank adjustment pin 54 fixed to the front end of the crank body 53. The crank adjustment pin 54 extends left and right and is rotatably assembled in the sewing machine housing 120. The crank adjustment pin 54 constitutes the fixed rotation fulcrum of the adjustment crank 50. Of course, the crank body 53 and the crank adjusting pin 54 can be an integrated structure.

[0063] Furthermore, if Figure 3 and Figure 4 As shown, the adjustment drive unit further includes a locking nut 63 , which is threadedly connected to the adjustment screw 61 . The locking nut 63 is located outside the sewing machine housing 120 and abuts against the outer surface of the sewing machine housing 120 .

[0064] When the adjustment drive unit is not in action, the upper and lower positions of the adjustment screw 61 are determined. Under the joint action of the adjustment screw 61 and the tension spring 62, as shown in FIG. Figure 5 As shown, the angle φ of the adjustment crank 50 is fixed. When the needle bar stroke needs to be switched, first loosen the locking nut 63, then rotate the adjustment screw 61 to adjust the upper and lower positions of the adjustment screw 61 in the sewing machine housing 120. Under the combined action of the adjustment screw 61 and the tension spring 62, the position angle of the adjustment crank 50 changes. The adjustment crank 50 changes the position angle of the regulator 30 through the adjustment connecting rod 40, thereby causing a change in the transmission efficiency of the needle bar eccentric 20 to the needle bar connecting column 80, which ultimately manifests as a change in the needle bar stroke. Figure 6 As shown, the horizontal axis is the angle φ of the adjustment crank 50, and the vertical axis is the needle rod stroke H; Figure 6It can be seen that the different angles φ1, φ2, and φ3 of the adjustment crank 50 correspond to the needle bar strokes H3, H2, and H1. In a specific embodiment, H3 corresponds to a needle bar stroke of 35 mm, and H1 corresponds to a needle bar stroke of 30.8 mm. The range of the adjustment angle φ of the adjustment crank 50 is 0-20°. After adjustment, tighten the lock nut 63 to maintain the vertical position of the adjustment screw 61. This adjustment drive unit is simple and easy to operate.

[0065] Preferably, if Figure 3 and Figure 4 As shown, a first scale 611 representing the needle bar stroke is provided on the outer surface of the adjusting screw 61, which can intuitively display the change of the needle bar stroke and improve the convenience of adjusting the needle bar stroke.

[0066] Example 2 of a cloth-piercing mechanism with variable rod stroke

[0067] The difference between the second embodiment of the thorn cloth mechanism with variable rod stroke and the first embodiment of the thorn cloth mechanism with variable rod stroke is that the structure of the adjustment drive unit is different. Figure 7 and Figure 8 As shown, the adjustment drive unit includes a locking screw 64 and a rotation slot 51 formed on the left end surface of the adjustment crank 50. The rotation slot 51 can be in a straight line, a cross, a square, or other shapes. The locking screw 64 extends forward and backward, is threadedly connected to the sewing machine housing 120, and abuts against the crank adjustment pin 54 of the adjustment crank 50. When it is necessary to switch the needle bar stroke, the locking screw 64 is loosened to release its abutment against the adjustment crank 50. Thereafter, a tool such as a screwdriver is inserted into the rotation slot 51 and the adjustment crank 50 is rotated. After the adjustment is completed, the locking screw 64 is tightened to abut against the crank adjustment pin 54 of the adjustment crank 50, thereby maintaining the current position angle of the adjustment crank 50, with good retention effect, stability, and reliability, and not easy to loosen.

[0068] Preferably, if Figure 7 and Figure 8 As shown, the cloth-piercing mechanism also includes a scale plate 130 fixed to the sewing machine housing 120, and the scale plate 130 is distributed on the upper side of the crank body 53 of the adjusting crank 50. A second scale 131 representing the needle bar stroke is provided on the scale plate 130, and a pointing portion 52 pointing to the second scale 131 is provided on the left end face of the crank body 53 of the adjusting crank 50, that is, the pointing portion 52 and the rotating groove 51 are distributed on the same surface of the adjusting crank 50. The two cooperate to intuitively display the changes in the needle bar stroke, thereby improving the convenience of adjusting the needle bar stroke.

[0069] Example 3 of a cloth-piercing mechanism with variable rod stroke

[0070] The third embodiment of the thorn cloth mechanism with variable rod stroke differs from the first embodiment of the thorn cloth mechanism with variable rod stroke only in that the structure of the adjustment drive unit is different and the structure of the adjustment crank 50 is different. In the third embodiment of the thorn cloth mechanism with variable rod stroke, Figure 9 As shown, the adjustment drive unit includes a drive motor 65, and the adjustment crank 50 only includes a crank body 53. The adjustment crank 50 is directly fixed to the motor shaft of the drive motor 65, and the motor shaft directly constitutes the fixed rotation fulcrum of the adjustment crank 50. When the needle bar stroke needs to be changed, the drive motor 65 rotates, driving the adjustment crank 50 to rotate, thereby adjusting the needle bar stroke.

[0071] Furthermore, in the three embodiments of the above-mentioned cloth-piercing mechanism with variable rod stroke, Figures 2 to 5 ,or Figure 7 and Figure 8 ,or Figure 9 As shown, the piercing mechanism further includes a fixed guide rail 140 and a needle bar slider 150, and a downwardly extending slide groove 141 is provided in the fixed guide rail 140; Figure 11 As shown, the needle bar connecting column 80 includes a column body portion 81 fixed on the needle bar 90, and a column connecting shaft portion 82 extending axially to the right from the right side of the column body portion 81. The column connecting shaft portion 82 is rotatably inserted into the needle bar connecting rod 70 and the needle bar slider 150, and the needle bar slider 150 is assembled in the slide groove 141 so as to be movable up and down.

[0072] In summary, the present invention enables switching between different needle bar strokes on a single sewing machine. When sewing fabrics with varying thicknesses, the needle bar stroke, and therefore the puncturing stroke, can be switched on a single machine, achieving better sewing results and expanding the sewing adaptability of a single sewing machine. Therefore, the present invention effectively overcomes the various shortcomings of the prior art and possesses high industrial value.

[0073] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A puncture mechanism with variable needle bar stroke, characterized in that: The invention comprises a needle bar eccentric wheel (20) for fixing on an upper shaft (10) in a sewing machine, a regulator (30), an regulating link (40), an regulating crank (50) with a fixed rotation fulcrum, an regulating drive unit, a needle bar link (70), a needle bar connecting column (80), a needle bar (90), and a needle (110) installed at the lower end of the needle bar (90), wherein the needle bar eccentric wheel (20) has an eccentric connecting shaft (21), one end of the eccentric connecting shaft (21), and one end of the regulating link (40) and the needle bar link (70) are all hinged to the regulator (30), and the eccentric connecting shaft (21) and one end of the regulating link (40) are hinged to the regulator (30). The hinge point between the connecting shaft (21) and the regulator (30), the hinge point between the regulating link (40) and the regulator (30), and the hinge point between the needle bar link (70) and the regulator (30) are staggered and distributed; the other end of the regulating link (40) is hinged to the regulating crank (50); the other end of the needle bar link (70) is hinged to the needle bar connecting column (80); and the needle bar connecting column (80) is fixed to the needle bar (90); when the regulating drive unit acts on the regulating crank (50), the regulating crank (50) is driven to rotate, thereby changing the position angle of the regulator (30).

2. The cloth-piercing mechanism according to claim 1, characterized in that: The adjustment drive unit comprises an adjustment screw (61) and a tension spring (62). The adjustment screw (61) is threadedly connected to the sewing machine housing (120) and abuts against the adjustment crank (50). One end of the tension spring (62) is fixed and the other end is connected to the adjustment crank (50). The spring force applied by the tension spring (62) to the adjustment crank (50) causes the adjustment crank (50) to have a tendency to rotate toward the adjustment screw (61).

3. The piercing mechanism according to claim 2, characterized in that: The adjustment drive unit further comprises a locking nut (63), wherein the locking nut (63) is threadedly connected to the adjustment screw (61), and the locking nut (63) is located outside the sewing machine housing (120) and abuts against the outer surface of the sewing machine housing (120).

4. The piercing mechanism according to claim 2, characterized in that: A first scale (611) representing the needle bar stroke is provided on the outer surface of the adjusting screw (61).

5. The cloth-piercing mechanism according to claim 1, characterized in that: The adjustment drive unit comprises a locking screw (64) and a rotation slot (51) provided on the adjustment crank (50); the locking screw (64) is threadedly connected in the sewing machine housing (120) and abuts against the adjustment crank (50).

6. The cloth-piercing mechanism according to claim 5, characterized in that: The invention also includes a scale plate (130) fixed to the sewing machine housing (120), wherein the scale plate (130) is provided with a second scale (131) representing the needle bar stroke, and the adjusting crank (50) is provided with a pointing portion (52) pointing to the second scale (131).

7. The cloth-piercing mechanism according to claim 1, characterized in that: The adjustment drive unit comprises a drive motor (65), and the adjustment crank (50) is fixed on a motor shaft of the drive motor (65).

8. The cloth-piercing mechanism according to claim 1, characterized in that: It also includes a fixed guide rail (140) and a needle bar slider (150), wherein the fixed guide rail (140) is provided with a downwardly extending slide groove (141), and the needle bar connecting column (80) includes a column body (81) fixed on the needle bar (90), and a column connecting shaft (82) extending from the column body (81), wherein the column connecting shaft (82) is rotatably passed through the needle bar connecting rod (70) and the needle bar slider (150), and the needle bar slider (150) is assembled in the slide groove (141) so as to move up and down.

9. A sewing machine, characterized in that: The sewing machine is equipped with a cloth-piercing mechanism with a variable needle bar stroke as described in any one of claims 1 to 8.

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