Sewing machine and stitch skipping prevention device thereof

Abstract

The utility model provides a needle skipping prevention device which is arranged in a sewing machine, and the sewing machine comprises a bottom plate, a needle plate arranged on the upper surface of the bottom plate, a rotating shuttle arranged below the needle plate, and a machine needle which reciprocates up and down. The machine needle guides an upper thread to sequentially penetrate through a sewing material placed on the needle plate and the needle plate from top to bottom and then ascend, a thread ring is formed below the needle plate, the needle skipping prevention device comprises a thread blocking piece arranged between the rotating shuttle and the needle plate, and the thread blocking piece comprises a thread blocking part extending in the direction where the thread ring is located. The utility model further provides a sewing machine which comprises the needle skipping prevention device. The utility model has the beneficial effects that the thread blocking piece is arranged between the rotating shuttle and the needle plate, and the thread blocking piece applies extra resistance to the thread ring, so that the purpose of expanding the thread ring is achieved, the thread hooking of the rotating shuttle is more convenient, and the needle skipping phenomenon is reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of sewing machines, in particular to a sewing machine and an anti-skip stitch device thereof. Background Art

[0002] The existing sewing machine includes a bottom plate, a needle plate arranged on the bottom plate, and a rotary hook arranged under the needle plate. When the sewing machine works, the sewing material is placed on the needle plate, and the machine needle guides the top thread to pass through the sewing material and the needle plate from top to bottom in sequence. After reaching the lower limit position, the machine needle rises. Due to the friction between the sewing material and the top thread, the top thread fails to rise synchronously with the machine needle but stays under the sewing material and expands towards the machine needle side under the elastic action to form a thread loop. Then the rotary hook rotates, and its shuttle tip enters the thread loop and continues to rotate to expand the thread loop, guiding the thread loop around the bobbin to form a lockstitch on the sewing material.

[0003] In practice, it is often found that due to the differences in the types of sewing materials or top threads, the thread loop formed by the top thread is relatively small, which may cause the shuttle tip to miss the thread loop and the rotary hook to fail to hook the thread, ultimately resulting in the skip stitch phenomenon and significantly reducing the sewing quality and efficiency. Summary of the Utility Model

[0004] Aiming at the above defects, the purpose of the utility model is to provide an anti-skip stitch device, which helps to expand the thread loop and reduce the skip stitch rate of the sewing machine.

[0005] The utility model provides an anti-skip stitch device arranged in a sewing machine. The sewing machine includes a bottom plate, a needle plate arranged on the upper surface of the bottom plate, a rotary hook arranged under the needle plate, and a machine needle that moves up and down reciprocally. The machine needle guides the top thread to pass through the sewing material placed on the needle plate and the needle plate from top to bottom in sequence and then rises, forming a thread loop under the needle plate. The anti-skip stitch device includes a thread blocking member arranged between the rotary hook and the needle plate, and the thread blocking member includes a thread blocking portion extending towards the direction where the thread loop is located.

[0006] Preferably, the thread blocking member includes an arc-shaped thread blocking member body, and the thread blocking portion is arranged at one end of the thread blocking member body.

[0007] Preferably, the sewing machine further includes a moving knife rotatably arranged under the needle plate, and the thread blocking member further includes a lifting portion for contacting the moving knife.

[0008] Preferably, the moving knife includes an outer arc surface and a straight section connected to each other, and the lifting portion is used for contacting the outer arc surface and the straight section.

[0009] Preferably, the sewing machine further includes a fixed knife fixed under the needle plate, and the fixed knife and the thread blocking member are respectively arranged on different sides of the rotary hook.

[0010] Preferably, the sewing machine further includes a rotating hook positioning member disposed below the needle plate, and the thread blocking member is disposed between the rotating hook positioning member and the needle plate.

[0011] Preferably, the thread blocking member is mounted on the rotating hook positioning member.

[0012] Preferably, the thread blocking portion is disposed on a side of the sewing needle away from the rotating hook positioning member.

[0013] Preferably, the thread blocking member is mounted on the bottom of the base plate.

[0014] The present utility model also provides a sewing machine, including the anti-jumping needle device described above.

[0015] The beneficial effect of the present utility model is that by disposing a thread blocking member between the rotating hook and the needle plate, an additional resistance is applied to the thread loop by the thread blocking member, so as to achieve the purpose of enlarging the thread loop, which is more convenient for the rotating hook to hook the thread and reduces the phenomenon of needle jumping. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a perspective view of the sewing machine of the present utility model;

[0017] Figure 2 is a schematic diagram of the installation position of the thread blocking member;

[0018] Figure 3 and Figure 4 are schematic diagrams of the relative positions of the thread blocking member, the rotating hook, the rotating hook positioning member, the fixed knife, and the moving knife observed from different angles;

[0019] Figure 5 is a schematic diagram of the structure of the thread blocking member;

[0020] Figure 6 is a schematic diagram of the structure of the moving knife;

[0021] Figure 7 is a schematic diagram of the relative positions of the sewing needle, the needle plate, and the thread blocking member;

[0022] Figure 8 is Figure 7 a cross-sectional view taken along the A-A direction in

[0023] Figure 9 is a comparison diagram of the thread loop sizes generated with and without the thread blocking member.

[0024] Description of Component Numbers:

[0025] 1 Machine housing

[0026] 2 Base plate

[0027] 21 Needle plate

[0028] 3 Needle bar

[0029] 31 Needle

[0030] 4 Rotating hook

[0031] 41 Rotating hook positioning part

[0032] 411 Positioning hook

[0033] 42 Adjusting positioning groove

[0034] 5 Fixed knife

[0035] 51 Fixed knife thread cutting edge

[0036] 6 Moving knife

[0037] 61 Thread cutting bulge

[0038] 611 Moving knife thread cutting edge

[0039] 62 Outer arc surface

[0040] 63 Straight section

[0041] 7 Thread blocking part

[0042] 71 Thread blocking part main body

[0043] 72 Thread blocking part

[0044] 73 Lifting part

[0045] 74 Connecting part

[0046] 8 Thread loop Detailed implementation manners

[0047] The following further elaborates the detailed implementation manners of the present utility model in conjunction with the accompanying drawings. These implementation manners are only used to illustrate the present utility model and do not limit the present utility model.

[0048] In the description of the present utility model, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present utility model.

[0049] In the description of the present utility model, it should be noted that unless otherwise clearly specified and defined, the terms "installation", "connection", and "coupling" shall be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

[0050] Figure 1 The following shows a perspective view of the sewing machine of the present utility model. In the following description, the attached drawings in Figure 1 are used as the reference basis for directions. In Figure 1 , the length direction of the base plate 2 is defined as the left - right direction, the needle plate 21 is located on the left side of the base plate 2; the width direction of the base plate 2 is defined as the front - back direction; the extending direction of the needle bar 3 is defined as the up - down direction, and the machine housing 1 is located above the base plate 2.

[0051] The present utility model provides an anti - skipping - stitch device and a sewing machine including the anti - skipping - stitch device. As shown in Figure 1-4 and Figure 9 , the sewing machine includes a machine housing 1, a base plate 2 provided below the machine housing 1, a needle plate 21 provided on the upper surface of the base plate 2, a rotary hook 4 and a rotary - hook positioning member 41 provided below the needle plate 21, a needle bar 3 that reciprocates up and down, and a sewing needle 31 provided at the lower end of the needle bar 3. Among them, the rotary hook 4 is composed of an outer hook frame and an inner hook frame. The inner hook frame is arranged inside the outer hook frame and is matched with the guide groove inside the outer hook frame through the guide rail on its outer wall. The inner hook frame is provided with an adjustment positioning groove 42, and the rotary - hook positioning member 41 is provided with a positioning hook 411. The circumferential position of the inner hook frame is determined by the engagement of the positioning hook 411 with the adjustment positioning groove 42. During the sewing process, the sewing needle 31 guides the upper thread to pass through the sewing material placed on the needle plate 21 and the needle plate 21 from top to bottom in sequence. After reaching the lower limit position, the sewing needle 31 rises to a certain height again. Due to the obstruction of the sewing material and the sewing needle 31, an upper - thread loop 8 is formed below the needle plate 21. At this time, the hook tip provided on the outer hook frame hooks the upper - thread loop 8 located on the right side of the sewing needle 31 and continues to rotate, expanding the upper - thread loop 8. The expanded upper - thread loop 8 bypasses the bobbin thread in the bobbin center of the inner hook frame to form a lock - stitch on the sewing material, thereby achieving the purpose of sewing. The above - mentioned base plate 2, needle plate 21, rotary hook 4, rotary - hook positioning member 41, needle bar 3, and sewing needle 31 are all prior arts and will not be elaborated here.

[0052] As shown in Figure 2-7 , the anti - skipping - stitch device provided by the present utility model includes a thread - blocking member 7 provided between the rotary hook 4 and the needle plate 21. The thread - blocking member 7 includes a thread - blocking portion 72 extending towards the direction where the upper - thread loop 8 is located. Specifically, the thread - blocking portion 72 is arranged on the side of the sewing needle 31 away from the rotary - hook positioning member 41 (i.e., the right side of the sewing needle 31). Combining Figure 9It can be seen that after the thread loop 8 is formed, the thread blocking part 72 contacts the right side of the thread loop 8, applying an additional resistance to the right side of the thread loop 8 to prevent the thread loop 8 from rising. As a result, the thread on the right side of the needle 31 located below the thread blocking part 72 continues to expand to the right side of the needle under the action of elasticity, thereby playing a role in expanding the thread loop 8. Compared with the thread loop 8 formed without the thread blocking member 7 in the prior art, the thread loop 8 obtained by the action of the anti-skip stitch device of the present utility model is larger, making it more convenient for the shuttle tip to enter and complete the thread hooking, and reducing the skip stitch rate.

[0053] As Figure 2-6 and Figure 9 shown, in a specific embodiment of the present utility model, the sewing machine further includes a thread cutting mechanism. The thread cutting mechanism includes a moving knife 6 and a fixed knife 5 disposed between the needle plate 21 and the rotary hook 4. The moving knife 6 is rotatably disposed above the front of the rotary hook 4, and the fixed knife 5 is fixed above the rear of the rotary hook 4. The moving knife 6 includes an outer arc surface 62 in an arc shape and a straight section 63 connected to the outer arc surface 62. The straight section 63 extends straight; a thread cutting bulge 61 is provided on the outer arc surface 62, and a through hole is provided in the thread cutting bulge 61. The edge where the through hole intersects the surface of the thread cutting bulge 61 constitutes the moving knife thread cutting edge 611. The front end of the fixed knife 5 is provided with a straight fixed knife thread cutting edge 51. The moving knife 6 can rotate towards the fixed knife 5 and insert below the fixed knife 5, so that the moving knife thread cutting edge 611 engages with the fixed knife thread cutting edge 51.

[0054] The thread blocking member 7 is also disposed above the front of the rotary hook 4 and is located above the moving knife 6, that is, the fixed knife 5 and the thread blocking member 7 are respectively disposed on different sides of the rotary hook 4. The thread blocking member 7 includes an arc-shaped thread blocking member main body 71, a thread blocking part 72 and a lifting part 73 both disposed at the rear end of the thread blocking member main body 71. The shape of the thread blocking member main body 71 matches the outer contour shape of the rotary hook 4, so that the thread blocking member main body 71 avoids the rotary hook 4 to prevent affecting the normal operation of the rotary hook 4; the thread blocking part 72 extends to the left, and its left end can contact the thread loop 8 located on the right side of the needle 31; the lifting part 73 extends to the right, and its lower surface is used to contact the moving knife 6. When the straight section 63 of the moving knife 6 contacts the lifting part 73, the height where the lifting part 73 is located does not change with the rotation of the moving knife 6; during the process of the moving knife 6 rotating towards the fixed knife 5, the outer arc surface 62 gradually rotates below the lifting part 73 and contacts the lifting part 73, and the outer arc surface 62 will lift the lifting part 73 upward. The lifting part 73 drives the entire thread blocking member 7 to lift upward, increasing the distance between the thread blocking member 7 and the moving knife thread cutting edge 611, ensuring that the moving knife thread cutting edge 611 can smoothly engage with the fixed knife thread cutting edge 51 to complete the thread cutting action.

[0055] Those skilled in the art can select the fixing position of the wire blocking member 7 as needed. The wire blocking member 7 can be directly fixed to the bottom of the base plate 2, or can be fixed to the rotary hook positioning member 41 through the connecting portion 74 provided at the front end of the wire blocking member main body 71, so that the wire blocking member 7 is arranged between the rotary hook positioning member 41 and the needle plate 21.

[0056] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and substitutions can be made, and these improvements and substitutions should also be regarded as the protection scope of the present invention.

Claims

1. A needle skipping prevention device is provided in a sewing machine, the sewing machine comprising a bottom plate, a needle plate provided on the upper surface of the bottom plate, a rotary shuttle provided below the needle plate, and a needle that reciprocates up and down, the needle guiding the upper thread to pass through the sewing material placed on the needle plate and the needle plate in sequence from top to bottom, and then rises to form a thread loop below the needle plate, characterized in that: The needle jumping prevention device comprises a thread blocking member arranged between the rotary hook and the needle plate, and the thread blocking member comprises a thread blocking portion extending toward the direction where the thread loop is located.

2. The anti-needle skipping device according to claim 1, characterized in that: The wire blocking member comprises an arc-shaped wire blocking member body, and the wire blocking portion is arranged at one end of the wire blocking member body.

3. The anti-needle skipping device according to claim 1, characterized in that: The sewing machine further comprises a movable knife rotatably arranged below the needle plate, and the thread blocking member further comprises a lifting portion for contacting the movable knife.

4. The anti-needle skipping device according to claim 3, characterized in that: The movable knife comprises an outer arc surface and a straight section connected to each other, and the lifting portion is used for contacting the outer arc surface and the straight section.

5. The anti-needle skipping device according to claim 1, characterized in that: The sewing machine further comprises a fixed knife fixed below the needle plate, and the fixed knife and the thread stopper are respectively arranged on different sides of the rotary hook.

6. The anti-needle skipping device according to claim 1, characterized in that: The sewing machine further comprises a rotary hook positioning member arranged below the needle plate, and the thread blocking member is arranged between the rotary hook positioning member and the needle plate.

7. The anti-needle skipping device according to claim 6, characterized in that: The thread blocking member is installed on the rotary hook positioning member.

8. The anti-needle skipping device according to claim 6, characterized in that: The thread blocking portion is arranged on a side of the needle away from the rotary hook positioning member.

9. The anti-needle skipping device according to claim 1, characterized in that: The wire blocking member is installed at the bottom of the bottom plate.

10. A sewing machine, characterized in that: The invention comprises a needle skipping prevention device as claimed in any one of claims 1 to 9.

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