Sewing machine feeding tooth adjusting device and sewing machine

Abstract

The invention provides a sewing machine feed dog adjusting device and a sewing machine, the sewing machine feed dog adjusting device comprises a bottom plate, a feed dog lifting shaft, a feed dog frame, a feed dog, a feed dog lifting crank, a feed dog lifting connecting rod, a feed dog lifting adjusting eccentric pin and a feed dog lifting adjusting knob, the feed dog lifting crank is fixed on the feed dog lifting shaft, and the feed dog lifting adjusting eccentric pin comprises a first shaft part and a second shaft part which are eccentrically arranged; the first shaft part is in running fit with the feed lifting crank and is fixed with the feed lifting adjusting knob, the second shaft part is in running fit with one end of the feed lifting connecting rod, and the other end of the feed lifting connecting rod is hinged with the feed rack; the feed lifting crank and the feed lifting adjusting knob are respectively provided with a plurality of adjusting positioning grooves and telescopic adjusting positioning pieces; when the feed lifting adjusting knob is rotated, the feed lifting adjusting eccentric pin synchronously rotates along with the feed lifting adjusting knob, the relative position between the second shaft part and the feed lifting connecting rod is changed, and the adjusting positioning piece moves out of the current adjusting positioning groove and is clamped into the other adjusting positioning groove. The height of the feeding teeth can be easily and conveniently adjusted by a lathe worker.

Description

Technical Field

[0001] This invention relates to the field of sewing machine technology, and in particular to a sewing machine feed dog adjustment device and a sewing machine equipped with the sewing machine feed dog adjustment device. Background Technology

[0002] Flatbed sewing machines used in the sewing industry are equipped with a dog-lifting mechanism and a feeding mechanism. The dog-lifting mechanism mainly includes a dog-lifting shaft rotatably mounted in the sewing machine base plate, a dog-lifting fork-shaped crank fixed and locked to the dog-lifting shaft by screws, and a dog-lifting slider that slides in a groove with the dog-lifting fork-shaped crank. The dog-lifting slider is hinged to the dog holder by a shaft screw, and the dog holder has a feed dog fixed on it. During the operation of the flatbed sewing machine, the dog-lifting mechanism drives the dog holder and feed dog to move up and down reciprocally, causing the feed dog to protrude from the upper surface of the needle plate and press against the lower surface of the fabric. Combined with the feeding mechanism driving the dog holder and feed dog to move back and forth, it pushes the fabric on the upper surface of the needle plate.

[0003] Typically, the different heights of the feed dog protruding from the needle plate surface can adapt to different sewing conditions. Existing flatbed sewing machines are divided into thin-material and thick-material models. One of the main differences between the two models is the height at which the feed dog protrudes from the needle plate surface; in the thick-material model, the feed dog protrudes higher than the needle plate surface in the thin-material model. Thus, the feed dog in the thick-material model exerts a deeper pressure on the fabric, providing stronger fabric feeding capability.

[0004] In the sewing industry, as market demand for clothing becomes more diversified, with trends towards small-batch, quick-response production and a wider variety of sewing materials, users often need to change styles. Changing styles usually means a change in fabric, requiring users to frequently adjust their sewing machines to adapt to the new materials. In particular, changes in fabric thickness typically require users to adjust the height of the feed dog above the needle plate in the sewing machine to suit the sewing conditions.

[0005] When sewing fabrics of different thicknesses and materials, users need to adjust the angle of the feed dog fork crank to adjust the feed dog height. The adjustment process involves: first, flipping the sewing machine head over; then, using considerable force, loosening the screw securing the feed dog fork crank; and finally, adjusting the vertical position of the feed dog fork crank on the feed dog shaft to roughly adjust the feed dog height. This feed dog height adjustment is generally not a problem for machine repair technicians in garment factories. However, the limited number of repair technicians means they cannot handle this promptly, requiring sewing machine operators to perform the adjustments themselves. However, garment factory sewing machine operators are predominantly women with less strength, making it very difficult for them to flip the sewing machine head and loosen the screw securing the feed dog fork crank. Furthermore, they rarely have the necessary tools to loosen the screws; and they often lack a clear understanding of how much feed dog height to adjust. Ultimately, when sewing machine operators need to adjust the feed dog height to suit different sewing styles, the cumbersome adjustment process forces them to wait for machine repair, impacting the garment factory's operational efficiency. Summary of the Invention

[0006] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a sewing machine feed dog adjustment device that can conveniently adjust the feed dog height.

[0007] To achieve the above objectives, the present invention provides a sewing machine feed dog adjustment device, comprising a fixed base plate, a feed dog shaft rotatably supported in the base plate, a feed dog bracket, a feed dog fixed on the feed dog bracket, and a feed dog transmission adjustment unit pulsatingly connected between the feed dog shaft and the feed dog bracket. The feed dog transmission adjustment unit includes a feed dog crank, a feed dog connecting rod, a feed dog adjustment eccentric pin, and a feed dog adjustment knob. The feed dog crank is fixed on the feed dog shaft. The feed dog adjustment eccentric pin includes an eccentrically arranged first shaft portion and a second shaft portion. The first shaft portion is rotatably engaged with the feed dog crank and fixed to the feed dog adjustment knob. The second shaft portion is rotatably engaged with one end of the feed dog connecting rod, and the other end of the feed dog connecting rod is hinged to the feed dog bracket.

[0008] The lifting crank and the lifting adjustment knob each have several circumferentially spaced adjustment positioning grooves on their end faces, and the other end face is equipped with an adjustment positioning component that can extend or retract along the direction of approaching or moving away from the adjustment positioning grooves. The adjustment positioning component is engaged in an adjustment positioning groove.

[0009] When the tooth lifting adjustment knob is rotated, the tooth lifting adjustment eccentric pin rotates synchronously with the tooth lifting adjustment knob, changing the relative position between the second shaft and the tooth lifting connecting rod, and the adjustment positioning member moves out of the current adjustment positioning groove and is inserted into another adjustment positioning groove.

[0010] Furthermore, the adjustment positioning groove has three sections, namely a conventional gear groove, a high gear groove, and a low gear groove. The high gear groove and the low gear groove are distributed on both sides of the conventional gear groove. The height of the feed tooth corresponding to the high gear groove, the height of the feed tooth corresponding to the conventional gear groove, and the height of the feed tooth corresponding to the low gear groove gradually decrease.

[0011] Furthermore, the tooth lifting adjustment knob abuts against one side of the tooth lifting crank along the extension direction of the tooth lifting adjustment eccentric pin, several adjustment positioning grooves are provided on the end face of the tooth lifting crank, and the adjustment positioning component is telescopically mounted on the end face of the tooth lifting adjustment knob.

[0012] Furthermore, the tooth lifting transmission adjustment unit also includes a positioning pin, which includes a housing fixed in the tooth lifting adjustment knob, a spring housed in the housing, and a positioning bead provided at the opening of the housing. The two ends of the spring abut against the housing and the positioning bead respectively, and the positioning bead constitutes the adjustment positioning component.

[0013] Furthermore, the lifting crank includes a crank body and a pair of crank arms extending from the crank body, and one end of the lifting connecting rod abuts between the pair of crank arms; the first shaft has two sections, and the two sections of the first shaft are rotatably inserted into the pair of crank arms, and the second shaft is connected between the two sections of the first shaft.

[0014] Furthermore, the sewing machine feed dog adjustment device also includes a push plate assembly; a wrench is fixedly provided on the feed dog adjustment knob, the base plate is provided with an adjustment opening groove and push plate slide grooves provided on both sides of the adjustment opening groove, the push plate assembly is movably assembled in the push plate slide groove, and the push plate assembly can open or close the adjustment opening groove.

[0015] When the adjustment slot is opened, the wrench portion is exposed in the adjustment slot.

[0016] Furthermore, the tooth lifting adjustment knob is threaded with several fastening screws, and the first shaft portion passes through the tooth lifting adjustment knob, with the ends of the fastening screws abutting against the outer periphery of the first shaft portion.

[0017] Furthermore, the tooth frame is riveted with rivets, which pass through the tooth lifting link and rotate in cooperation with the tooth lifting link.

[0018] The present invention also provides a sewing machine equipped with the sewing machine feed dog adjustment device as described above.

[0019] As described above, the sewing machine feed dog adjustment device and sewing machine of the present invention have the following beneficial effects:

[0020] This application allows for adjustment of the feed dog height by rotating a feed dog adjustment knob. The knob's rotation is positioned by an adjusting positioning component that engages with an adjusting positioning groove. Different grooves correspond to different feed dog heights, making it easy and convenient for the sewing machine operator to adjust the feed dog height. Furthermore, this application features a simple overall structure and low cost, contributing to reduced overall sewing machine costs and enhanced competitiveness. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the sewing machine feed dog adjustment device of this application.

[0022] Figure 2 for Figure 1 A schematic diagram of the structure after the middle pusher plate assembly has been removed.

[0023] Figure 3 for Figure 1 A structural diagram omitting the base plate, push plate assembly, and needle plate.

[0024] Figure 4 for Figure 3 Exploded view.

[0025] Figure 5 This is a schematic diagram of the lifting crank in the feed dog adjustment device of the sewing machine in this application.

[0026] Figure 6 This is a schematic diagram of the tooth lifting adjustment knob in the sewing machine feed adjustment device of this application.

[0027] Figure 7 This is a schematic diagram of the positioning pin in the feed dog adjustment device of the sewing machine in this application.

[0028] Figure 8 This is a schematic diagram of the adjustment of the feed dog adjustment device of the sewing machine in this application.

[0029] Component designation explanation

[0030] 10. Base plate

[0031] 101 Adjustable opening groove

[0032] 102 Push plate slide

[0033] 20 Tooth-lifting shaft

[0034] 30 Dental Bracket

[0035] 40 feed dog

[0036] 50 Crank crank

[0037] 51 Adjusting the positioning groove

[0038] 52 Standard gear slots

[0039] 53 High-end slot

[0040] 54 Low-gear slot

[0041] 55 Crank body section

[0042] 56 Crank arm

[0043] 60 lifting linkage

[0044] 70 Tooth-lifting adjustment eccentric pin

[0045] 71 First Shaft

[0046] 72 Second Shaft

[0047] 80 Tooth lifting adjustment knob

[0048] 81 Wrench section

[0049] 90 Adjustable positioning component

[0050] 110 positioning pin

[0051] 111 Outer shell

[0052] 112 Spring

[0053] 113 Positioning Beads

[0054] 120 pusher plate assembly

[0055] 130 Fastening Screw

[0056] 140 rivets

[0057] 150 feed shaft

[0058] 160 needle plate

[0059] 170 dental bracket

[0060] 180 dental bracket pin Detailed Implementation

[0061] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0062] It should be understood that the structures, proportions, sizes, etc., depicted in the accompanying drawings are merely for illustrative purposes to aid those skilled in the art and to facilitate understanding. They are not intended to limit the scope of the invention and therefore have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, without affecting the effectiveness and objectives of the invention, should still fall within the scope of the technical content disclosed herein. Furthermore, the terms "upper," "lower," "left," "right," "middle," and "one" used in this specification are merely for clarity and not intended to limit the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention's implementation.

[0063] It should also be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on the other component or may be connected to an intermediary component. When a component is referred to as being "connected to" another component, it can be directly connected to the other component or indirectly connected to the other component through an intermediary component.

[0064] Furthermore, the use of terms such as "first" and "second" in this application is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed in this application.

[0065] This application provides a sewing machine feed dog adjustment device and a sewing machine equipped with the sewing machine feed dog adjustment device.

[0066] like Figures 1 to 4 As shown, the sewing machine involved in this application includes a fixedly mounted base plate 10, a feed dog 30, a feed dog 40 fixed on the feed dog 30, a lifting mechanism connected to one end of the feed dog 30, and a feeding mechanism connected to the other end of the feed dog 30. The lifting mechanism includes a lifting shaft 20 rotatably supported in the base plate 10, and the feeding mechanism includes a feeding shaft 150 rotatably supported in the base plate 10. The lifting shaft 20 and the feeding shaft 150 are parallel. For ease of description, the axial direction of the lifting shaft 20 is defined as the left-right direction, and the direction of the lifting shaft 20 toward the sewing machine head is the left direction.

[0067] like Figures 1 to 4As shown, the sewing machine feed dog adjustment device involved in this application includes the aforementioned base plate 10, feed dog shaft 20, feed dog frame 30, and feed dog 40. The sewing machine feed dog adjustment device also includes a feed dog transmission adjustment unit, which is connected between the feed dog shaft 20 and the feed dog frame 30. The feed dog transmission adjustment unit includes a feed dog crank 50, a feed dog connecting rod 60, a feed dog adjustment eccentric pin 70, and a feed dog adjustment knob 80. The feed dog crank 50 is fixed and locked to the left end of the feed dog shaft 20 by screws. The feed dog adjustment eccentric pin 70 includes an eccentrically arranged first shaft portion 71 and a second shaft portion 72, both of which extend horizontally. The first shaft portion 71 is rotatably engaged with the feed dog crank 50 and fixed to the feed dog adjustment knob 80. The second shaft portion 72 is rotatably engaged with one end of the feed dog connecting rod 60, and the other end of the feed dog connecting rod 60 is hinged to the rear end of the feed dog frame 30.

[0068] Furthermore, such as Figure 4 As shown, the lifting crank 50 and the lifting adjustment knob 80 each have several circumferentially spaced adjustment positioning grooves 51 on their end faces, while the other end face is equipped with an adjustment positioning element 90 that is retractable along the direction of approaching or moving away from the adjustment positioning grooves 51. The adjustment positioning element 90 is engaged in one of the adjustment positioning grooves 51. Furthermore, the adjustment positioning element 90 is engaged in different adjustment positioning grooves 51, corresponding to different feed tooth heights 40. Thus, by engaging the adjustment positioning element 90 with different adjustment positioning grooves 51, positioning is provided for the rotation of the lifting adjustment knob 80, that is, positioning is provided for the operation of adjusting the height of the feed tooth 40.

[0069] During normal operation of the sewing machine, the feed dog power source drives the feed dog shaft 20 to rotate. The feed dog shaft 20, through the feed dog transmission adjustment unit, drives the feed dog holder 30 and the feed dog 40 to reciprocate up and down, with the feed dog 40 performing the feed dog lifting action. Simultaneously, the feed dog power source drives the feed shaft 150 to rotate, and the feed mechanism drives the feed dog holder 30 and the feed dog 40 to reciprocate back and forth, with the feed dog 40 performing the feed action. Thus, the feed dog 40 performs a combined up-and-down reciprocating motion and a back-and-forth reciprocating motion. When the feed dog 40 emerges upward from the tooth groove of the needle plate 160, it drives the fabric on the upper surface of the needle plate 160 to move forward, combining with the needle's needle-piercing action to sew the fabric. Furthermore, the power source driving the feed dog shaft 20 and the feed shaft 150 can be the same power source or two different power sources.

[0070] When it is necessary to adjust the lifting height of the feed dog 40, stop the sewing machine and turn the lifting adjustment knob 80, as follows. Figure 8As shown, since the tooth lifting adjustment knob 80 is fixed to the first shaft portion 71 of the tooth lifting adjustment eccentric pin 70, the tooth lifting adjustment eccentric pin 70 rotates synchronously with the tooth lifting adjustment knob 80 around the first shaft portion 71. Since the first shaft portion 71 and the second shaft portion 72 of the tooth lifting adjustment eccentric pin 70 are eccentrically set, when the tooth lifting adjustment knob 80 drives the tooth lifting adjustment eccentric pin 70 to rotate around the first shaft portion 71, the relative position of the second shaft portion 72 of the tooth lifting adjustment eccentric pin 70 and the tooth lifting connecting rod 60 changes, thereby changing the vertical position of the tooth frame 30 hinged to the tooth lifting connecting rod 60, and thus the height of the feeding tooth 40 also changes, realizing the height adjustment of the feeding tooth 40. Meanwhile, during the rotation of the tooth lifting adjustment knob 80, the retraction of the adjustment positioning member 90 causes it to move out of the current adjustment positioning groove 51. Then, the extension of the adjustment positioning member 90 causes it to engage with another adjustment positioning groove 51, thus providing positioning for the rotation of the tooth lifting adjustment knob 80, and also for the height adjustment of the feed dog 40. This makes the height adjustment of the feed dog 40 very easy and convenient, allowing garment factory workers to adjust it themselves, effectively improving the factory's operational efficiency. Furthermore, this application has a simple overall structure and low cost, which helps reduce the overall cost of the sewing machine and enhances its competitiveness.

[0071] Furthermore, such as Figure 3 and Figure 4 As shown, the feeding mechanism also includes a toothed bracket seat 170 fixed to the left end of the feeding shaft 150 and toothed bracket pins 180 extending to the left and right. The toothed bracket seat 170 is connected to the front end of the toothed bracket 30 through the toothed bracket pins 180.

[0072] Furthermore, such as Figures 3 to 5 As shown, the lifting crank 50 includes a crank body 55 and a pair of crank arms 56 extending from the crank body 55. The pair of crank arms 56 are arranged side by side, and the end of the lifting connecting rod 60 connected to the second shaft 72 abuts between the pair of crank arms 56. The first shaft 71 has two sections, left and right, and the two sections of the first shaft 71 are rotatably inserted into the pair of crank arms 56 respectively. The second shaft 72 is connected between the two sections of the first shaft 71, thereby realizing the cooperative connection between the lifting crank 50, the lifting connecting rod 60, and the lifting adjusting eccentric pin 70. In addition, the pair of crank arms 56 of the lifting crank 50 can limit the left and right movement of the lifting connecting rod 60, ensuring the reliability of the lifting of the feed tooth 40 and the accuracy of the lifting height adjustment.

[0073] Preferably, in the tooth-lifting adjusting eccentric pin 70, the diameters of the right first shaft portion 71, the second shaft portion 72, and the left first shaft portion 71 decrease sequentially. Thus, in the tooth-lifting crank 50, the shaft hole in the right crank arm portion 56 that rotatably engages with the right first shaft portion 71 is a large hole, while the shaft hole in the left crank arm portion 56 that rotatably engages with the left first shaft portion 71 is a small hole.

[0074] Furthermore, such as Figure 3 and Figure 4 As shown, the tooth lifting adjustment knob 80 abuts against the left side of the end of the tooth lifting crank 50 along the extension direction of the tooth lifting adjustment eccentric pin 70. Several adjustment positioning grooves 51 are provided on the left end face of the tooth lifting crank 50. The adjustment positioning component 90 is telescopically mounted on the right end face of the tooth lifting adjustment knob 80.

[0075] Preferably, the mounting structure of the adjusting positioning member 90 is as follows: Figure 4 and Figure 7 As shown, the tooth lifting transmission adjustment unit also includes a positioning pin 110. The positioning pin 110 includes a housing 111 fixed in the tooth lifting adjustment knob 80, a spring 112 housed in the housing 111 and extending to the left and right, and a positioning bead 113 provided at the opening at the right end of the housing 111. The tooth lifting adjustment knob 80 is provided with a fixing hole for accommodating the housing 111. The left and right ends of the spring 112 abut against the housing 111 and the positioning bead 113 respectively. The positioning bead 113 constitutes the adjustment positioning element 90. When adjusting the height of the feed tooth 40 by rotating the tooth lifting adjustment knob 80, the positioning pin 110 rotates together with the knob. During rotation, the positioning bead 113, pressed by the left end face of the tooth lifting crank 50, first retracts to the left into the housing, disengaging from the current adjustment positioning slot 51. As the tooth lifting adjustment knob 80 rotates along with the positioning pin 110, and with the action of the spring 112, the positioning bead 113 extends to the right and engages in the next adjustment positioning slot 51. When the height of the feed tooth 40 is not adjusted, the positioning bead 113 remains engaged in the current adjustment positioning slot 51, more reliably ensuring that the relative position of the tooth lifting adjustment knob 80 and the tooth lifting crank 50 does not change. Furthermore, this structure provides a tactile feedback when the user adjusts the height of the feed tooth 40, facilitating more precise and convenient adjustment of the feed tooth 40 height by the machinist.

[0076] Furthermore, such as Figure 5As shown, there are three adjustment positioning grooves 51 on the left side of the outer end of the lifting crank 50. These three grooves are a standard gear groove 52, a high gear groove 53, and a low gear groove 54. The high gear groove 53 and the low gear groove 54 are located on either side of the standard gear groove 52. The height of the feed dog 40 corresponding to the standard gear groove 52 is the height of the feed dog 40 used for conventional sewing. The height of the feed dog 40 corresponding to the high gear groove 53 is the height of the feed dog 40 used for sewing thick materials. The height of the feed dog 40 corresponding to the low gear groove 54 is the height of the feed dog 40 used for sewing thin materials. Therefore, the heights of the feed dog 40 corresponding to the high gear groove 53, the standard gear groove 52, and the low gear groove 54 gradually decrease. In this embodiment, using... Figure 8 Taking a view angle as an example, the high-gear groove 53 is located on the clockwise side of the regular-gear groove 52, and the low-gear groove 54 is located on the counterclockwise side of the regular-gear groove 52. During regular sewing, such as... Figure 8 As shown, the positioning bead 113 is engaged in the regular position slot 52. When sewing thick materials, the height of the feed dog 40 needs to be increased. In this case, the feed dog adjustment knob 80 is rotated clockwise, and the positioning bead 113 moves out of the regular position slot 52 and into the high position slot 53. Conversely, when sewing thin materials, the height of the feed dog 40 needs to be decreased. In this case, the feed dog adjustment knob 80 is rotated counterclockwise, and the positioning bead 113 moves out of the regular position slot 52 and into the low position slot 54. This makes it easier for the operator to adjust the height of the feed dog 40.

[0077] Furthermore, such as Figure 1 and Figure 2 As shown, the sewing machine feed dog adjustment device also includes a pusher plate assembly 120, which is located on the left end of the needle plate 160. Figure 4 and Figure 6As shown, a wrench portion 81 extends integrally to the left from the left end face of the tooth lifting adjustment knob 80. The wrench portion 81 has a flat structure. The base plate 10 has an adjustment opening groove 101 on the left side of the needle plate 160, and push plate slide grooves 102 extending left and right on both sides of the adjustment opening groove 101. The adjustment opening groove 101 extends to the left edge of the base plate 10. The push plate assembly 120 is movably mounted in the push plate slide groove 102. The push plate assembly 120 can open or close the adjustment opening groove 101. When the height of the feed dog 40 needs to be adjusted, push the push plate assembly 120 to the left, opening the adjustment slot 101. At this time, the lever part 81 on the feed dog adjustment knob 80 is exposed in the adjustment slot 101. The user can reach under the base plate 10 or use other tools to turn the lever part 81 clockwise or counterclockwise, thus driving the feed dog adjustment knob 80 to rotate clockwise or counterclockwise, thereby increasing or decreasing the height of the feed dog 40. This makes it easier to turn the feed dog adjustment knob 80 and adjust the height of the feed dog 40. After the height of the feed dog 40 is adjusted, push the push plate assembly 120 to the right, closing the adjustment slot 101 to prevent dust, lint, and other impurities from entering the sewing machine through the adjustment slot 101.

[0078] Furthermore, the structure in which the tooth-lifting adjustment knob 80 is fixed on the first shaft portion 71 is as follows: Figure 4 As shown, the tooth lifting adjustment knob 80 is threaded with two fastening screws 130. The left section of the first shaft 71 extends from the tooth lifting crank 50 and passes through the tooth lifting adjustment knob 80. The tooth lifting adjustment knob 80 is provided with a shaft hole for accommodating the first shaft 71. The end of the fastening screw 130 abuts against the outer periphery of the first shaft 71, thereby fixing the tooth lifting adjustment knob 80 to the left end of the first shaft 71.

[0079] Furthermore, the hinge structure between the tooth-lifting linkage 60 and the tooth frame 30 is as follows: Figure 3 and Figure 4 As shown, a rivet 140 is riveted in the tooth frame 30. The rivet 140 passes through the tooth lifting link 60 and rotates with the tooth lifting link 60, thereby hinged the tooth lifting link 60 to the rear end of the tooth frame 30.

[0080] In summary, this invention effectively overcomes the various shortcomings of the prior art and has high industrial application value.

[0081] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can 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 those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A sewing machine feed dog adjusting device, comprising a fixed base plate (10), a feed dog lifting shaft (20) rotatably supported in the base plate (10), a feed dog holder (30), a feed dog (40) fixed on the feed dog holder (30), and a feed dog lifting transmission adjusting unit drively connected between the feed dog lifting shaft (20) and the feed dog holder (30), characterized in that: The tooth lifting transmission adjustment unit includes a tooth lifting crank (50), a tooth lifting connecting rod (60), a tooth lifting adjustment eccentric pin (70), and a tooth lifting adjustment knob (80). The tooth lifting crank (50) is fixed on the tooth lifting shaft (20). The tooth lifting adjustment eccentric pin (70) includes an eccentrically set first shaft portion (71) and a second shaft portion (72). The first shaft portion (71) is rotatably engaged with the tooth lifting crank (50) and fixed with the tooth lifting adjustment knob (80). The second shaft portion (72) is rotatably engaged with one end of the tooth lifting connecting rod (60). The other end of the tooth lifting connecting rod (60) is hinged to the tooth frame (30). Of the lifting crank (50) and the lifting adjustment knob (80), one end face is provided with several circumferentially spaced adjustment positioning grooves (51), and the other end face is provided with an adjustment positioning element (90) that can extend or retract along the direction of approaching or moving away from the adjustment positioning groove (51). The adjustment positioning element (90) is engaged in one adjustment positioning groove (51). When the tooth lifting adjustment knob (80) is rotated, the tooth lifting adjustment eccentric pin (70) rotates synchronously with the tooth lifting adjustment knob (80), changing the relative position between the second shaft (72) and the tooth lifting connecting rod (60), and the adjustment positioning member (90) moves out of the current adjustment positioning groove (51) and is inserted into another adjustment positioning groove (51).

2. The sewing machine feed dog adjustment device according to claim 1, characterized in that: The adjustment positioning groove (51) has three sections, namely the conventional gear groove (52), the high gear groove (53), and the low gear groove (54). The high gear groove (53) and the low gear groove (54) are distributed on both sides of the conventional gear groove (52). The height of the feed tooth (40) corresponding to the high gear groove (53), the height of the feed tooth (40) corresponding to the conventional gear groove (52), and the height of the feed tooth (40) corresponding to the low gear groove (54) gradually decrease.

3. The sewing machine feed dog adjustment device according to claim 1 or 2, characterized in that: The tooth lifting adjustment knob (80) abuts against one side of the tooth lifting crank (50) along the extension direction of the tooth lifting adjustment eccentric pin (70), and several adjustment positioning grooves (51) are provided on the end face of the tooth lifting crank (50). The adjustment positioning element (90) is telescopically mounted on the end face of the tooth lifting adjustment knob (80).

4. The sewing machine feed dog adjustment device according to claim 3, characterized in that: The tooth lifting transmission adjustment unit also includes a positioning pin (110), which includes a housing (111) fixed in the tooth lifting adjustment knob (80), a spring (112) housed in the housing (111), and a positioning bead (113) provided at the opening of the housing (111). The two ends of the spring (112) abut against the housing (111) and the positioning bead (113) respectively, and the positioning bead (113) constitutes the adjustment positioning element (90).

5. The sewing machine feed dog adjustment device according to claim 1, characterized in that: The lifting crank (50) includes a crank body (55) and a pair of crank arms (56) extending from the crank body (55). One end of the lifting connecting rod (60) abuts between the pair of crank arms (56). The first shaft (71) has two sections, and the two sections of the first shaft (71) are rotatably inserted into the pair of crank arms (56). The second shaft (72) is connected between the two sections of the first shaft (71).

6. The sewing machine feed dog adjustment device according to claim 1, characterized in that: It also includes a push plate assembly (120); a wrench part (81) is fixed on the tooth lifting adjustment knob (80), and the base plate (10) is provided with an adjustment opening groove (101) and push plate slide grooves (102) on both sides of the adjustment opening groove (101). The push plate assembly (120) is movably assembled in the push plate slide groove (102), and the push plate assembly (120) can open or close the adjustment opening groove (101). When the adjustment opening slot (101) is opened, the wrench part (81) is exposed in the adjustment opening slot (101).

7. The sewing machine feed dog adjustment device according to claim 1, characterized in that: The tooth lifting adjustment knob (80) has several fastening screws (130) threaded in it. The first shaft (71) passes through the tooth lifting adjustment knob (80), and the end of the fastening screw (130) abuts against the outer periphery of the first shaft (71).

8. The sewing machine feed dog adjustment device according to claim 1, characterized in that: The tooth frame (30) is riveted with rivets (140), which are inserted into the tooth lifting link (60) and rotate in cooperation with the tooth lifting link (60).

9. A sewing machine, characterized in that: The sewing machine is equipped with the sewing machine feed dog adjustment device according to any one of claims 1-8.

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