An inner and outer presser foot with center split alternating function for a sewing machine head

Abstract

The invention provides an inner and outer presser foot with a center-split alternating function of a sewing machine head, belonging to the technical field of sewing machines. It solves the problem that the existing inner and outer presser foot is prone to left-right deviation during sewing and has poor practicality. The inner and outer presser foot with a center-split alternating function of the sewing machine head comprises an inner presser foot and an outer presser foot, a clearance gap is provided in the middle of the outer presser foot along the front-back direction, an outer mounting seat is provided on the outer presser foot, a center-split knife is hinged on the outer mounting seat, a driving member for driving the center-split knife to swing is connected to the outer mounting seat, and a part of the center-split knife is embedded in the clearance gap, the inner presser foot comprises an inner mounting seat, and the left and right sides of the inner mounting seat are respectively connected with a left inner presser foot and a right inner presser foot along the vertical sliding direction, and a clearance space for the center-split knife to be embedded is formed between the left inner presser foot and the right inner presser foot. The inner and outer presser foot with a center-split alternating function of the sewing machine head does not need to replace the left inner presser foot and the right inner presser foot of different heights, and the left inner presser foot and the right inner presser foot can be adjusted according to the height of the cloth itself.

Description

Technical Field

[0001] The invention belongs to the technical field of sewing machines and relates to an inner and outer presser foot with a center-split alternating function of a sewing machine head. Background Art

[0002] When the sewing machine is sewing fabric, the fabric is pressed against the feed dogs, and the friction between the feed dogs and the fabric is used to transport the fabric to ensure normal sewing. When sewing thicker fabrics, the outer presser foot and the inner presser foot need to be moved alternately and the needle plate and the feed dogs need to be coordinated to achieve feeding. Fabrics of different thicknesses also need to be seamed. After seaming, the two fabrics need to be sewn separately. There is a large gap at the joint, which results in different heights of the fabric near the gap, causing inconvenience in sewing.

[0003] In view of the above-mentioned problems, a Chinese patent application [application publication number: CN206666795U] has been developed, which discloses a presser foot structure of a sewing machine, including a presser foot handle and a presser foot plate, the presser foot handle is connected to the presser foot plate, the presser foot structure also includes a backrest, the backrest includes a connecting portion, a transition portion and a supporting portion, the connecting portion is hinged to the presser foot handle through a hinge shaft, the transition portion connects the connecting portion and the supporting portion, the presser foot plate is provided with a yield groove which is arranged along the front and rear directions of the presser foot plate and runs through the upper and lower plate surfaces of the presser foot plate, the supporting portion is plate-shaped and can be embedded in the yield groove, the hinge shaft is also provided with a torsion spring which makes the supporting portion always have a tendency to swing downward and protrude from the lower plate surface of the presser foot, and the transition portion can be abutted against the upper plate surface of the presser foot plate.

[0004] The above structure is that a backrest is installed on the presser foot plate. During the sewing process, the backrest is always against the cloth. The setting of the backrest has a good positioning effect. The above structure adopts a single presser foot. When sewing, both sides of the cloth need to be sewn. The pressing and transfer are achieved by the inner presser foot and the outer presser foot. The inner presser foot and the outer presser foot need to move alternately, which causes the setting of the above backrest to affect the installation and operation of the inner presser foot or the outer presser foot.

[0005] When sewing fabrics of different thicknesses on the left and right sides after seaming, the existing method usually involves replacing an inner presser foot with two high and low limit parts to press the fabrics of two different thicknesses. However, this method requires workers to replace the inner presser foot with one of the corresponding sizes based on their own experience, which results in the need to replace the inner presser foot according to the thickness of the fabrics during use. This makes the use of the inner presser foot complicated and reduces the practicality of the existing inner presser foot. Summary of the invention

[0006] The purpose of the present invention is to address the above-mentioned problems in the existing technology and to propose an inner and outer presser foot with a center-split alternating function for a sewing machine head. The technical problem to be solved by the present invention is: how to solve the problem that the existing inner and outer presser feet are prone to left and right deviations during sewing and have poor practicality.

[0007] The purpose of the present invention can be achieved by the following technical solutions:

[0008] The invention discloses an inner and outer presser foot with a center-split alternating function of a sewing machine head, comprising an inner presser foot and an outer presser foot, wherein a clearance gap is formed in the middle portion of the outer presser foot along the front-rear direction, and the outer presser foot is provided with an outer mounting seat, characterized in that a center-split knife is hinged on the outer mounting seat, a driving member for driving the center-split knife to swing is connected to the outer mounting seat, and the center-split knife is partially embedded in the clearance gap, the inner presser foot comprises an inner mounting seat, and a left inner presser foot and a right inner presser foot are respectively connected to the left and right sides of the inner mounting seat along a vertical sliding manner, a clearance space for the center-split knife to be embedded is formed between the left inner presser foot and the right inner presser foot, and an adjustment component for limiting the rear position of the left inner presser foot and the right inner presser foot when they move up and down is provided in the inner mounting seat.

[0009] Working principle: A center-dividing knife is hinged on the outer mounting seat. When sewing the two sides of the fabric after seaming, the outer presser foot presses the fabric against the needle plate, and the center-dividing knife is driven downward by the driving member to press the fabric against the gap between the two fabrics to guide the sewing. When sewing, the inner presser foot and the outer presser foot move alternately, the outer presser foot presses the fabric against the needle plate, and the inner presser foot presses the fabric against the feed dog, so that the fabric is fed and sewn at the same time. When sewing fabrics of different thicknesses, the heights of the two pieces of fabric near the seam are different. When the inner presser foot presses down, the higher side of the fabric is on the inner presser foot. When the presser foot is pressed down, there is great resistance. A left inner presser foot and a right inner presser foot are vertically slidably connected to the inner mounting seat. Under the resistance of fabrics of different thicknesses, the left inner presser foot and the right inner presser foot slide upward to corresponding heights along with the resistance and are limited by the adjusting component, so that the left inner presser foot and the right inner presser foot can be staggered and stay at corresponding heights, thereby pressing fabrics of different heights and realizing feeding of fabrics. There is no need to replace the left inner presser foot and the right inner presser foot of different heights to sew fabrics, but the inner presser foot can be directly set to be adjustable according to the height of the fabric itself.

[0010] The above structure realizes that the center knife always moves along the seam during the sewing process, and the vertically sliding left inner presser foot and right inner presser foot and the adjustment component on the inner presser foot realize the feeding and sewing of fabrics of different thicknesses or the same thickness, thereby improving the stability and practicality of sewing by the inner and outer presser feet.

[0011] In the above-mentioned inner and outer presser feet with a center-split alternating function of the sewing machine head, the adjustment component includes an adjustment lever arranged in the left and right directions and capable of swinging up and down at both ends, the middle part of the adjustment lever is hinged in the inner mounting seat, one end of the adjustment lever is connected to the left inner presser foot and drives it to slide up and down, and the other end is connected to the right inner presser foot and drives it to slide up and down.

[0012] By adjusting the setting of the lever, when the left inner presser foot or the right inner presser foot is lifted, the right inner presser foot or the left inner presser foot is pressed down, so that the height position of the left inner presser foot and the right inner presser foot can be adjusted according to the height difference of the corresponding cloth. During the pressing process, the higher end is supported by the cloth and pressed on the cloth surface by the downward pressure, and the other end is pressed on the other cloth surface by the downward pressure under the swing of the adjusting lever, thereby realizing the vertical positioning of two pieces of fabric with different heights, so that the inner presser foot can feed and position more stably, and the sewing effect is better; when sewing cloth without height difference, the inner presser foot can be pressed on the cloth by downward pressure. At this time, the adjusting lever will not swing, and sewing of cloth without height difference can also be realized, which improves the practicability of the inner and outer presser feet.

[0013] In the above-mentioned inner and outer presser feet with center-divided alternating function of the sewing machine head, the inner mounting seat includes a mounting block and a cover plate, a hinge groove is opened in the middle of the mounting block along the left-right direction, the cover plate is fixedly connected to the mounting block and blocks the hinge groove, the upper groove wall of the hinge groove protrudes upward to form an upper hinge interface, the lower groove wall of the hinge groove protrudes downward to form a lower hinge interface, the middle part of the adjusting lever protrudes to form an articulated wheel, the adjusting lever is arranged in the articulated groove, and the articulated wheel is embedded in the upper hinge interface and the lower hinge interface and can rotate along the mouth wall of the upper hinge interface and the mouth wall of the lower hinge interface, and the two ends of the adjusting lever are located outside the articulated groove and are respectively connected to the left inner presser foot and the right inner presser foot.

[0014] An articulated wheel is arranged in the middle of the adjusting lever, which is arranged in the articulated groove and the upper and lower ends are respectively embedded in the upper hinge interface and the lower hinge interface. When one end of the adjusting lever moves vertically, the articulated wheel is driven to rotate along the mouth wall of the upper hinge interface and the mouth wall of the lower hinge interface, thereby realizing the articulation of the adjusting lever and the mounting block. The installation of the adjusting lever is realized through the cover plate, so that a relatively simple structure can realize the adjustment of the height difference between the left inner presser foot and the right inner presser foot, thereby improving the convenience and stability of the installation of the inner presser foot.

[0015] In the inner and outer presser feet with the center-split alternating function of the above-mentioned sewing machine head, the upper groove wall of the hinge groove is upwardly tilted on the left and right sides to form an upper stroke wall, and the lower groove wall of the hinge groove is downwardly bent on the left and right sides to form a lower stroke wall, and the upper stroke wall and the lower stroke wall are symmetrically arranged up and down and are arc-shaped, and the upper side wall on one side of the adjusting lever can be fitted with the upper stroke wall, and the lower side wall on the other side of the adjusting lever is fitted with the lower stroke wall.

[0016] The setting of the upper stroke wall and the lower stroke wall increases the ability to achieve limiting through the cooperation of the upper stroke wall and the lower stroke wall when the adjusting lever is adjusted to the maximum value, and the arc-shaped setting can play a guiding effect, reduce the impact between the adjusting lever and the inner mounting seat, and improve the stability of the swing of the adjusting lever.

[0017] In the inner and outer presser feet with center-split alternating function of the above-mentioned sewing machine head, slide grooves are vertically provided on the left and right sides of the mounting block, the left inner presser foot and the right inner presser foot are respectively slidably connected in the corresponding slide grooves, the slide grooves are connected with the hinge grooves, the two ends of the adjusting lever are respectively provided with a left hinge block and a right hinge block, the left inner presser foot is provided with a left hinge interface for the left hinge block to be embedded, the right inner presser foot is provided with a right hinge interface for the right hinge block to be embedded, and the left hinge interface and the right hinge interface are both open to the rear.

[0018] By directly opening a sliding groove on the mounting block, the left hinge block and the right hinge block of the adjusting lever are respectively embedded in the left hinge interface and the right hinge interface, making the installation of the adjusting lever more convenient, and the left hinge block and the right hinge block push the left inner presser foot and the right inner presser foot to move, thereby improving the pushing stability.

[0019] In the above-mentioned inner and outer presser feet with center-split alternating function of the sewing machine head, the upper and lower walls of the right hinge block and the upper and lower walls of the left hinge block are both arc-shaped, and the upper and lower walls of the left hinge interface and the upper and lower walls of the right hinge interface are both flat.

[0020] The setting of this structure reduces the contact area between the left hinge block and the right hinge block and the left hinge interface and the right hinge interface respectively, reduces wear, and through the setting of the arc wall, ensures that during adjustment, the outer wall of the left hinge block always abuts against the upper and lower walls of the left hinge interface, and the outer wall of the right hinge block always abuts against the upper and lower walls of the right hinge interface, thereby improving the adjustment efficiency and stability of the left inner presser foot and the right inner presser foot.

[0021] In the above-mentioned inner and outer presser feet with center-split alternating function of the sewing machine head, the width of the left hinge block and the width of the right hinge block are both smaller than the width of the hinge wheel.

[0022] By setting the size, the movement of the left hinge block and the right hinge block during adjustment can drive the rotation of the hinge wheel more quickly, thereby improving the rapidity and timeliness of the adjustment.

[0023] In the inner and outer presser feet with the center-split alternating function of the above-mentioned sewing machine head, the driving part is a cylinder, and a connecting rod which can be moved forward and backward is connected to the cylinder. A long adjusting groove is provided on the connecting rod along its length direction, and a hinge shaft is also connected to the connecting rod, one end of which passes through the adjusting groove and is fixed to the upper end of the front end of the center-split knife. The lower end of the front end of the center-split knife is rotatably connected to the external mounting seat, and the connecting rod can push the hinge shaft to move to the front and rear ends of the hinge point between the center-split knife and the external mounting seat.

[0024] The cylinder pushes the connecting rod to move backward, and the connecting rod drives the center knife to swing along the hinge point between the center knife and the outer mounting seat until the center knife is aligned with the seam and pressed on the fabric, thereby achieving guidance during the sewing process. The cylinder drives the connecting rod to move forward, and the connecting rod drives the center knife to swing along the hinge point until the center knife is separated from the fabric, thereby achieving the resetting of the center knife and guidance during seaming.

[0025] In the above-mentioned inner and outer presser feet with center-split alternating function of the sewing machine head, the connecting rod is arranged to be inclined downward from front to rear.

[0026] The tilted direction of the connecting rod makes it easy to quickly swing the center knife to press it against the fabric, thereby improving the convenience of adjusting the center knife.

[0027] In the inner and outer presser feet with the center-split alternating function of the above-mentioned sewing machine head, a return spring arranged vertically is also provided on one side of the outer mounting seat, and the lower end of the front end of the center-split knife protrudes forward to form a return part, and the lower end of the return spring abuts against the return part and has a tendency to press the return part downward.

[0028] The setting of the return spring enables the front end of the center-splitting knife to be quickly pressed downward under the elastic force of the return spring, thereby improving the return efficiency of the center-splitting knife.

[0029] Compared with the prior art, the present invention has the following advantages:

[0030] 1. The center-split knife is used to move along the seam during sewing. The vertically sliding left and right inner presser feet and the adjustment assembly on the inner presser foot enable the feeding and sewing of fabrics of different or same thicknesses, thereby improving the stability and practicality of the inner and outer presser foot sewing.

[0031] 2. An articulated wheel is arranged in the middle of the adjusting lever, the articulated wheel is arranged in the articulated groove, and the upper and lower ends are respectively embedded in the upper hinge interface and the lower hinge interface. When one end of the adjusting lever moves vertically, the articulated wheel is driven to rotate along the mouth wall of the upper hinge interface and the mouth wall of the lower hinge interface, thereby realizing the articulation of the adjusting lever and the mounting block. When the adjusting lever is installed through the cover plate, a relatively simple structure is adopted to realize the adjustment of the height difference between the left inner presser foot and the right inner presser foot, thereby improving the convenience and stability of the installation of the inner presser foot. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram of the structure of the first embodiment after assembly.

[0033] Figure 2 yes Figure 1 A partial enlarged view of point A in the middle.

[0034] Figure 3It is a partial structural schematic diagram of the inner presser foot and the adjustment component after assembly in the first embodiment.

[0035] Figure 4 It is a partial exploded view of the inner presser foot and the adjustment assembly after assembly in the first embodiment.

[0036] Figure 5 It is a partial top view of the assembled outer presser foot in the first embodiment.

[0037] Figure 6 yes Figure 5 Partial cross-section along AA.

[0038] Figure 7 It is a partial structural diagram of the first embodiment.

[0039] Figure 8 It is a schematic diagram of the structure of the first embodiment after assembly in another direction.

[0040] In the figure, 1, inner presser foot; 11, left inner presser foot; 11a, left hinge interface; 12, right inner presser foot; 12a, right hinge interface; 13, clearance space; 2, outer presser foot; 21, clearance gap; 22, outer mounting seat; 22a, air inlet channel; 3, middle dividing knife; 31, reset part; 4, driving member; 5, adjustment component; 51, adjustment lever; 52, articulated wheel; 53, left articulated block; 54, right Articulated block; 6, inner mounting seat; 61, mounting block; 61a, articulated groove; 61b, upper hinge interface; 61c, lower hinge interface; 61d, upper stroke wall; 61e, lower stroke wall; 62, cover plate; 63, slide groove; 7, connecting rod; 71, adjusting groove; 72, articulated shaft; 8, return spring; 9, lower base; 91, solenoid valve; 92, boost valve; 92a, air inlet pipe; 92b, air outlet pipe. DETAILED DESCRIPTION

[0041] The following are specific embodiments of the present invention and the accompanying drawings to further describe the technical solution of the present invention, but the present invention is not limited to these embodiments.

[0042] Embodiment 1

[0043] like Figure 1 As shown, the inner and outer presser feet with alternating functions of the sewing machine head include an inner presser foot 1 and an outer presser foot 2. A clearance gap 21 is provided in the middle of the outer presser foot 2 along the front-to-back direction, and an outer mounting seat 22 is provided on the outer presser foot 2.

[0044] Specifically, Figure 1-8As shown, a center-dividing knife 3 is hinged on the outer mounting seat 22, and a driving member 4 for driving the center-dividing knife 3 to swing is connected to the outer mounting seat 22, and the center-dividing knife 3 is partially embedded in the clearance gap 21, and the inner presser foot 1 includes an inner mounting seat 6, and the left and right sides of the inner mounting seat 6 are respectively connected with a left inner presser foot 11 and a right inner presser foot 12 along the vertical sliding connection, and a clearance space 13 for the center-dividing knife 3 to be embedded is formed between the left inner presser foot 11 and the right inner presser foot 12, and an adjustment component 5 is provided in the inner mounting seat 6 for limiting the rear position of the left inner presser foot 11 and the right inner presser foot 12 when they move up and down.

[0045] Working principle: A center-dividing knife 3 is hinged on the outer mounting seat 22. When sewing the two sides of the fabric after seaming, the outer presser foot 2 presses the fabric against the needle plate, and the center-dividing knife 3 is driven downward by the driving member 4 to press the fabric against the gap between the two fabrics, so as to provide positioning guidance for sewing. When sewing, the inner presser foot 1 and the outer presser foot 2 move alternately, the outer presser foot 2 presses the fabric against the needle plate, and the inner presser foot 1 presses the fabric against the feed dog, so as to realize sewing while feeding the fabric. When sewing thicker fabrics, the heights of the two pieces of fabric near the seam are different. When the inner presser foot 1 is pressed downward, the higher side of the fabric is pressed against the inner presser foot 1. When pressing down, there is a large resistance. A left inner presser foot 11 and a right inner presser foot 12 are vertically slidably connected to the inner mounting seat 6. Under the resistance of different fabrics, the left inner presser foot 11 and the right inner presser foot 12 slide upward to a corresponding height along with the resistance and are limited by the adjusting component 5, so that the left inner presser foot 11 and the right inner presser foot 12 can be staggered and stay at a corresponding height, and fabrics of different heights are pressed tightly to realize feeding. It is not necessary to replace the left inner presser foot 11 and the right inner presser foot 12 of different heights to sew fabrics, but directly to set the inner presser foot 1 to be adjustable according to the height of the fabric itself.

[0046] like Figure 2-4As shown, the adjustment component 5 includes an adjustment lever 51 which is arranged in the left-right direction and can swing up and down at both ends. The middle part of the adjustment lever 51 is hinged in the inner mounting seat 6. One end of the adjustment lever 51 is connected to the left inner presser foot 11 and drives it to slide up and down, and the other end is connected to the right inner presser foot 12 and drives it to slide up and down. The inner mounting seat 6 includes a mounting block 61 and a cover plate 62. The middle part of the mounting block 61 is provided with a hinge groove 61a in the left-right direction. The cover plate 62 is fixedly connected to the mounting block 61 and blocks the hinge groove 61a. The upper groove wall of the hinge groove 61a protrudes upward to form an upper hinge interface 61b, and the lower groove wall of the hinge groove 61a protrudes downward to form a lower hinge interface 61c. The middle part of the adjustment lever 51 protrudes to form an articulated wheel 52. The adjustment lever 51 is arranged in the hinge groove 61a, and the hinge wheel 52 is embedded in the upper hinge interface 61b and the lower hinge interface 61c and can rotate along the mouth wall of the upper hinge interface 61b and the mouth wall of the lower hinge interface 61c, the two ends of the adjusting lever 51 are located outside the hinge groove 61a and are respectively connected to the left inner presser foot 11 and the right inner presser foot 12, the upper groove wall of the hinge groove 61a is upwardly tilted on the left and right sides to form an upper stroke wall 61d, and the lower groove wall of the hinge groove 61a is downwardly bent on the left and right sides to form a lower stroke wall 61e, the upper stroke wall 61d and the lower stroke wall 61e are symmetrically arranged up and down and are arc-shaped, the upper side wall of one side of the adjusting lever 51 can be fitted with the upper stroke wall 61d, and the lower side wall of the other side of the adjusting lever 51 is fitted with the lower stroke wall 61e.

[0047] like Figure 2-4 As shown, a slide groove 63 is vertically provided on the left and right sides of the mounting block 61, and the left inner presser foot 11 and the right inner presser foot 12 are respectively slidably connected in the corresponding slide grooves 63, and the slide groove 63 is communicated with the hinge groove 61a, and the two ends of the adjusting lever 51 are respectively provided with a left hinge block 53 and a right hinge block 54, and the left inner presser foot 11 is provided with a left hinge interface 11a for the left hinge block 53 to be embedded, and the right inner presser foot 12 is provided with a right hinge interface 12a for the right hinge block 54 to be embedded, and the left hinge interface 11a and the right hinge interface 12a are both opened toward the rear, and the upper and lower walls of the right hinge block 54 and the upper and lower walls of the left hinge block 53 are both arc-shaped, and the upper and lower walls of the left hinge interface 11a and the upper and lower walls of the right hinge interface 12a are both planes, and the width of the left hinge block 53 and the width of the right hinge block 54 are both smaller than the width of the articulated wheel 52, and the left hinge block 53 and the right articulated block 54 are symmetrically arranged along the vertical center line of the articulated wheel 52.

[0048] like Figure 5-8As shown, a solenoid valve 91 and a boost valve 92 are provided on the lower base 9 of the sewing machine, an air inlet pipe 92a of the boost valve 92 is connected to the air outlet of the solenoid valve 91, an air outlet pipe 92b is connected to the air outlet of the boost valve 92, the air outlet pipe 92b is connected to the outer mounting seat 22, an air inlet passage 22a is provided on the outer mounting seat 22, the air inlet passage 22a is connected to the cylinder, the driving member 4 is a cylinder, a connecting rod 7 which can move forward and backward is connected to the cylinder, a long strip-shaped adjusting groove 71 is provided on the connecting rod 7 along its length direction, and a connecting rod 7 is also connected to one end passing through the adjusting groove 71 and The hinge shaft 72 is fixed to the upper end of the front end of the middle-dividing knife 3, and the lower end of the front end of the middle-dividing knife 3 is rotatably connected to the external mounting seat 22. The connecting rod 7 can push the hinge shaft 72 to move to the front and rear ends of the hinge point between the middle-dividing knife 3 and the external mounting seat 22. The connecting rod 7 is arranged downwardly from front to back. A reset spring 8 arranged vertically is also provided on one side of the external mounting seat 22. The lower end of the front end of the middle-dividing knife 3 protrudes forward to form a reset portion 31. When the middle-dividing knife 3 is reset, the lower end of the reset spring 8 abuts against the reset portion 31 to press the reset portion 31 downward, and the hinge shaft 72 slides along the adjustment slot 71.

[0049] The solenoid valve 91 can control the flow of gas, thereby achieving the purpose of controlling the cylinder. In this model, multiple solenoid valves 91 are centrally arranged on the lower base 9 of the sewing machine.

[0050] Embodiment 2

[0051] The contents of this embodiment are basically the same as those of the first embodiment, except that the adjustment assembly 5 includes a left spring and a right spring arranged on the inner mounting seat 6, the left spring and the right spring are both arranged vertically, the lower end of the left spring abuts against the upper end of the left inner presser foot 11, and the upper end of the right spring abuts against the upper end of the right inner presser foot 12.

[0052] By adopting the setting of the left spring and the right spring, when there is a height difference between two pieces of cloth, the left inner presser foot 11 and the right inner presser foot 12 can be lifted up a certain distance according to the height of the different cloths, thereby improving the practicality and stability of the inner presser foot 1.

[0053] The specific embodiments described herein are merely examples of the spirit of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in similar ways, but they will not deviate from the spirit of the present invention or exceed the scope defined by the appended claims.

Claims

1. An inner and outer presser foot with a center-split alternating function for a sewing machine head, comprising an inner presser foot (1) and an outer presser foot (2), wherein a clearance gap (21) is provided in the middle of the outer presser foot (2) along the front-back direction, and an outer mounting seat (22) is provided on the outer presser foot (2), characterized in that: A center-splitting knife (3) is hingedly connected to the outer mounting seat (22), and a driving member (4) for driving the center-splitting knife (3) to swing is connected to the outer mounting seat (22). The center-splitting knife (3) is partially embedded in the clearance gap (21). The inner presser foot (1) comprises an inner mounting seat (6). The left and right sides of the inner mounting seat (6) are respectively connected to a left inner presser foot (11) and a right inner presser foot (12) in a vertically sliding manner. A clearance space (13) for the center-splitting knife (3) to be embedded is formed between the left inner presser foot (11) and the right inner presser foot (12). An adjusting component (5) is provided in the inner mounting seat (6) for limiting the left inner presser foot (11) and the right inner presser foot (12) after they move up and down. The adjusting component (5) comprises an adjusting lever (51) arranged in the left-right direction and capable of swinging up and down at both ends. The inner mounting seat (6) comprises a mounting block (61) and a cover The mounting block (61) has a hinge groove (61a) in the middle along the left-right direction, the cover plate (62) is fixedly connected to the mounting block (61) and covers the hinge groove (61a), the upper groove wall of the hinge groove (61a) protrudes upward to form an upper hinge interface (61b), the lower groove wall of the hinge groove (61a) protrudes downward to form a lower hinge interface (61c), the middle part of the adjusting lever (51) protrudes to form an articulated wheel (52), the adjusting lever (51) is arranged in the articulated groove (61a), and the articulated wheel (52) is embedded in the upper hinge interface (61b) and the lower hinge interface (61c) and can rotate along the mouth wall of the upper hinge interface (61b) and the mouth wall of the lower hinge interface (61c), and the two ends of the adjusting lever (51) are located outside the articulated groove (61a) and are respectively connected to the left inner presser foot (11) and the right inner presser foot (12).

2. The inner and outer presser feet with center-split alternating function of the sewing machine head according to claim 1, characterized in that: The middle part of the adjusting lever (51) is hinged in the inner mounting seat (6), one end of the adjusting lever (51) is connected to the left inner presser foot (11) and drives it to slide up and down, and the other end is connected to the right inner presser foot (12) and drives it to slide up and down.

3. The inner and outer presser feet with center-split alternating function of the sewing machine head according to claim 1, characterized in that: The upper groove wall of the hinge groove (61a) is tilted upward on the left and right sides to form an upper travel wall (61d), and the lower groove wall of the hinge groove (61a) is bent downward on the left and right sides to form a lower travel wall (61e). The upper travel wall (61d) and the lower travel wall (61e) are symmetrically arranged up and down and are arc-shaped. The upper side wall of one side of the adjustment lever (51) can be in contact with the upper travel wall (61d), and the lower side wall of the other side of the adjustment lever (51) is in contact with the lower travel wall (61e).

4. The inner and outer presser feet with center-split alternating function of the sewing machine head according to claim 3, characterized in that: The left and right sides of the mounting block (61) are provided with sliding grooves (63) in the vertical direction. The left inner presser foot (11) and the right inner presser foot (12) are respectively slidably connected in the corresponding sliding grooves (63). The sliding grooves (63) are communicated with the hinge groove (61a). The two ends of the adjusting lever (51) are respectively provided with a left hinge block (53) and a right hinge block (54). The left inner presser foot (11) is provided with a left hinge interface (11a) for the left hinge block (53) to be embedded. The right inner presser foot (12) is provided with a right hinge interface (12a) for the right hinge block (54) to be embedded. Both the left hinge interface (11a) and the right hinge interface (12a) are open to the rear.

5. The inner and outer presser feet with center-split alternating function of the sewing machine head according to claim 4, characterized in that: The upper and lower walls of the right hinge block (54) and the upper and lower walls of the left hinge block (53) are both arc-shaped, and the upper and lower walls of the left hinge interface (11a) and the upper and lower walls of the right hinge interface (12a) are both planes.

6. The inner and outer presser feet with center-split alternating function of the sewing machine head according to claim 4 or 5, characterized in that: The width of the left hinge block (53) and the width of the right hinge block (54) are both smaller than the width of the hinge wheel (52).

7. The inner and outer presser feet with center-split alternating function of the sewing machine head according to any one of claims 1 to 4, characterized in that: The driving member (4) is a cylinder, and a connecting rod (7) is connected to the cylinder and can move forward and backward. The connecting rod (7) is provided with a long strip-shaped adjustment slot (71) along its length direction. The connecting rod (7) is also connected to a hinge shaft (72) with one end passing through the adjustment slot (71) and fixed to the upper end of the front end of the middle-splitting knife (3). The lower end of the front end of the middle-splitting knife (3) is rotatably connected to the external mounting seat (22). The connecting rod (7) can push the hinge shaft (72) to move to the front and rear ends of the hinge point between the middle-splitting knife (3) and the external mounting seat (22).

8. The inner and outer presser feet with center split alternating function of the sewing machine head according to claim 7, characterized in that: The connecting rod (7) is arranged to be inclined downward from front to rear.

9. The inner and outer presser feet with center-split alternating function of the sewing machine head according to any one of claims 1 to 4, characterized in that: A return spring (8) arranged vertically is also provided on one side of the outer mounting seat (22); the lower end of the front end of the middle dividing knife (3) protrudes forward to form a return portion (31); the lower end of the return spring (8) abuts against the return portion (31) and has a tendency to press the return portion (31) downward.

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