Sewing machine and automatic sewing and cutting method for sewing machine

Abstract

The application belongs to the technical field of sewing equipment, and particularly relates to a sewing machine and an automatic sewing and cutting method of the sewing machine; two ends of a driving shaft of a double-head motor are respectively provided with a presser foot lifting cam, a thread loosening cam and a thread cutting cam; one end of a presser foot lifting crank is connected with a presser foot lever shaft of a presser foot lifting mechanism, and the other end is provided with a first roller and a pressing block; the first roller is in abutting cooperation with the presser foot lifting cam and the thread loosening cam; a thread loosening driving lever is located below the pressing block; one end of the thread loosening driving lever is rotationally connected with a machine shell, and the other end is provided with a thread loosening driving hole; one end of a thread loosening crank is fixed on a thread loosening shaft of a thread loosening mechanism, and the other end is provided with a thread loosening rod; the thread loosening rod is arranged in the thread loosening driving hole; one end of a thread cutting driving push block is fixed on a thread cutting shaft, and the other end is provided with a second roller in abutting cooperation with the thread cutting cam; the presser foot lifting action, the thread loosening action and the thread cutting action are respectively performed by one double-head motor, the driver used is reduced in production cost, and the structure is compact.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of sewing equipment, and particularly relates to a sewing machine and an automatic sewing and cutting method of the sewing machine. BACKGROUND

[0002] A presser foot lifting mechanism is usually arranged on a sewing machine to perform the lifting and placing of a presser foot, a thread loosening mechanism performs the action of loosening thread, and a thread cutting mechanism performs the cutting of thread braids or cloth strips or elastic bands. With the improvement of technical level and the popularization of automation technology, the presser foot lifting mechanism, the thread loosening mechanism and the thread cutting mechanism can also perform automatic presser foot lifting, automatic presser foot placing, automatic thread loosening and automatic thread cutting, but a corresponding driver is needed to drive the action of the above mechanisms. Common drivers include motors, electromagnets and air cylinders, and each mechanism is driven by a driver to perform the action, which has the defects of high cost and large space occupation caused by the need for multiple drivers.

[0003] In addition, the action of the presser foot lifting mechanism of the existing sewing machine is realized by a worker's foot control. When sewing is needed, the worker steps on the foot pedal with his foot to control the presser foot to be lifted, places the sewing material after the presser foot is lifted, and then resets the foot pedal and places the presser foot. After starting sewing, the controller calculates the number of stitches, and when the number of stitches reaches a pre-set number, the controller controls the action of the thread cutting mechanism to cut thread braids or cloth strips, elastic bands (such as placing an elastic band on the sewing material and sewing the two together) and the like. The existing foot-controlled presser foot needs manual operation and has low automation. As for automatic thread cutting, since the needle code of the needle has a size, different needle codes of the needle need to be adjusted to different set numbers of stitches, which is inconvenient to use and has high professional nature, and the precision of thread cutting is also low. Often, the thread braid or elastic band left on the sewing material is very long after sewing for a distance, which results in a large amount of loss of the elastic band. SUMMARY

[0004] The purpose of the present application is to provide a sewing machine with the actions of presser foot lifting, thread loosening and thread cutting driven by one driver.

[0005] The purpose of the present application is also to provide an automatic sewing and cutting method of a sewing machine with high automation and high cutting precision.

[0006] The present application is implemented as follows:

[0007] One of the purposes of the present application is to provide a sewing machine, comprising an automatic presser foot, thread loosening, thread cutting drive mechanism, presser foot mechanism, thread loosening mechanism and thread cutting mechanism, the automatic presser foot, thread loosening, thread cutting drive mechanism comprising a double-head motor, a presser foot crank, a thread cutting drive push block, a thread loosening drive lever, both ends of the drive shaft of the double-head motor are respectively provided with a presser foot and thread loosening cam, a thread cutting cam, the presser foot and thread loosening cam comprises a first idle stroke section, a presser foot and thread loosening drive section, the thread cutting cam comprises a second idle stroke section, a thread cutting drive section, one end of the presser foot crank is connected with the presser foot lever shaft of the presser foot mechanism, the other end is provided with a first roller and a pressing block, the first roller is in abutting fit with the presser foot and thread loosening cam, the thread loosening drive lever is below the pressing block, one end of the thread loosening drive lever is rotatably connected with the machine shell, the other end is provided with a thread loosening drive hole, one end of the thread loosening crank is fixed on the thread loosening shaft of the thread loosening mechanism, the other end is provided with a thread loosening lever, the thread loosening lever is arranged in the thread loosening drive hole, one end of the thread cutting drive push block is fixed on the thread cutting shaft, the other end is suspended and provided with a second roller in abutting fit with the thread cutting cam.

[0008] In the above-mentioned sewing machine, the first idle stroke section is an equal-diameter circular arc surface, the second idle stroke section is an equal-diameter circular arc surface, the presser foot and thread loosening drive section is a variable-diameter cam surface, and the thread cutting drive section is a variable-diameter cam surface.

[0009] When the presser foot and thread loosening drive section of the presser foot and thread loosening cam is in abutting fit with the first roller, the second idle stroke section of the thread cutting cam is in abutting fit with the second roller.

[0010] When the thread cutting drive section of the thread cutting cam is in abutting fit with the second roller, the first idle stroke section of the presser foot and thread loosening cam is in abutting fit with the first roller.

[0011] In the above-mentioned sewing machine, the presser foot crank comprises a presser foot crank body and a bent plate at the other end of the presser foot crank body, the first roller is rotatably connected at the other end of the presser foot crank body through a roller shaft, and the pressing block is arranged on the bent plate through a fastener.

[0012] In the above-mentioned sewing machine, the presser foot lever shafts on both sides of the presser foot crank are respectively provided with a presser foot crank stop ring and a presser foot crank spacer, the presser foot crank is provided with a notch, the presser foot crank stop ring is provided with an extension part, the extension part is located in the notch of the presser foot crank, one end of the presser foot crank spacer abuts on the corresponding shaft sleeve of the presser foot lever shaft, and the presser foot crank spacer and the presser foot crank stop ring axially limit the presser foot crank.

[0013] In the sewing machine, a first reset torsion spring is sleeved on the lifting presser foot crank spacer, a first arm of the first reset torsion spring is inserted on the machine shell, and a second arm abuts against the bottom surface of the lifting presser foot crank.

[0014] In the sewing machine, a convex column is arranged on the machine shell, one end of the thread loosening driving lever is rotatably connected to the convex column, a second reset torsion spring is sleeved on the convex column, a third arm of the second reset torsion spring is inserted on the machine shell, and a fourth arm abuts against the bottom surface of the thread loosening driving lever.

[0015] In the sewing machine, the thread cutting mechanism comprises a mounting seat arranged on the machine shell, a sliding plate arranged at the lower end of the mounting seat, and a cutting knife slidably arranged on the sliding plate through a sliding block, the thread cutting shaft is movably arranged on the mounting seat and can reciprocate up and down along the axial direction of the mounting seat, a stop ring and a thread cutting reset spring are further sleeved on the thread cutting shaft, one end of the thread cutting reset spring is arranged on the stop ring, and the other end is arranged on the mounting seat, and a driving frame is arranged at the lower end of the thread cutting shaft and connected with the sliding block.

[0016] In the sewing machine, a lower light eye assembly arranged on the sewing table and an upper light eye assembly arranged on the machine shell are further arranged, the lower light eye assembly comprises a first lower light eye, a second lower light eye and a third lower light eye, the upper light eye assembly comprises a first upper light eye, a second upper light eye and a third upper light eye which are respectively opposite to the first lower light eye, the second lower light eye and the third lower light eye, the first upper light eye and the first lower light eye control the automatic lifting presser foot, thread loosening and thread cutting driving mechanism to drive the lifting presser foot and the presser foot, the second upper light eye and the second lower light eye control the automatic lifting presser foot, thread loosening and thread cutting driving mechanism to drive the cutting knife to cut the thread braid, cloth strip or elastic band, and the third upper light eye and the third lower light eye control the automatic lifting presser foot, thread loosening and thread cutting driving mechanism to be inactivated when the sewing material does not pass through the third lower light eye.

[0017] Another object of the present application is to provide an automatic sewing and cutting method of the sewing machine, which comprises the following steps:

[0018] S1, when the sewing material covers the first lower light eye, the opposite between the first upper light eye and the first lower light eye is blocked, the controller receives the signal to control the lifting presser foot mechanism to lift the presser foot;

[0019] S2, the worker manually drives the sewing material to continue to move forward, and after a certain time is delayed by the controller, the lifting presser foot mechanism is controlled to lower the presser foot, and the sewing machine starts to sew;

[0020] S3, during the sewing process of the sewing material, the sewing material moves forward, when the sewing material covers the second lower light eye, the opposite between the second upper light eye and the second lower light eye is blocked, the controller receives the signal to control the thread cutting mechanism to drive the cutting knife to cut the material at the front end of the sewing material, and then reset;

[0021] S4, the sewing continues to sew through the second lower light eye, the controller delays for a certain time to control the thread cutting mechanism to act to cut off the material at the rear end of the sewing material, and then reset;

[0022] S5, when the sewing material passes through the presser foot but does not pass through the third lower light eye, the thread cutting mechanism does not act.

[0023] In the automatic sewing and cutting method of the sewing machine, the presser foot lifting mechanism and the thread cutting mechanism are driven by the same driver.

[0024] The present application has the following outstanding advantages compared with the prior art:

[0025] 1. The present application uses a double-head motor to drive the presser foot lifting and thread loosening actions and the thread cutting action, so that the driver used is reduced in production cost, the structure is compact, and the sewing machine is easy to optimize design;

[0026] 2. The present application uses the light eye assembly and the lower light eye assembly as signal sources to drive the automatic presser foot lifting mechanism and the thread cutting mechanism, so that the degree of automation is high, the precision is high, the material left on the sewing material after cutting (such as a thread braid or a cloth strip or an elastic band) is short, the loss of the material is small, and the quality, the sewing efficiency, and the product yield of the whole machine are greatly improved. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 is one of the schematic diagrams of the present application;

[0028] Figure 2 is the second schematic diagram of the present application;

[0029] Figure 3 is the schematic diagram of the thread clamping mechanism arranged on the machine shell of the present application;

[0030] Figure 4 is the third schematic diagram of the present application;

[0031] Figure 5 is the first schematic diagram of the automatic presser foot lifting, thread loosening, and thread cutting driving mechanism connected with the presser foot lifting mechanism, the thread loosening mechanism, and the thread cutting mechanism of the present application;

[0032] Figure 6 is the second schematic diagram of the automatic presser foot lifting, thread loosening, and thread cutting driving mechanism connected with the presser foot lifting mechanism, the thread loosening mechanism, and the thread cutting mechanism of the present application;

[0033] Figure 7 is the schematic diagram of the presser foot lifting and thread loosening cam of the present application;

[0034] Figure 8 is the schematic diagram of the thread cutting cam of the present application;

[0035] Figure 9Fig. 1 is a schematic view of the lifting presser foot crank of the present application.

[0036] Fig. 1 is a schematic view of the lifting presser foot crank of the present application. DETAILED DESCRIPTION

[0037] The present application will be further described in conjunction with the following specific examples, with reference to the accompanying drawings, in which Figures 1-9 :

[0038] Example 1

[0039] The embodiment provides a sewing machine which comprises an automatic presser foot lifting mechanism, a thread loosening mechanism, a thread cutting driving mechanism, a presser foot lifting mechanism, a thread loosening mechanism and a thread cutting mechanism, the thread cutting mechanism has a thread cutting shaft 20 which drives the action of a thread cutter 23. The automatic presser foot lifting mechanism, the thread loosening mechanism and the thread cutting driving mechanism comprise a double-head motor 1, a presser foot lifting crank 2, a thread cutting driving push block 3, a thread loosening driving lever 4, the double-head motor 1 is arranged on a machine shell 15 through a motor mounting plate 14. The two ends of the driving shaft of the double-head motor 1 are respectively provided with a presser foot and thread loosening cam 5 and a thread cutting cam 6, the presser foot and thread loosening cam 5 comprises a first idle stroke section 7 and a presser foot and thread loosening driving section 8, the thread cutting cam 6 comprises a second idle stroke section 9 and a thread cutting driving section 10, one end of the presser foot lifting crank 2 is connected with a presser foot lever shaft 11 of the presser foot lifting mechanism, the other end is provided with a first roller 12 and a press block 13, it is to be noted that the first roller 12 usually adopts a deep groove ball bearing. The first roller 12 is in abutting fit with the presser foot and thread loosening cam 5, the thread loosening driving lever 4 is arranged below the press block 13, one end of the thread loosening driving lever 4 is rotationally connected with the machine shell 15, the other end is provided with a thread loosening driving hole 16, one end of a thread loosening crank 17 is fixedly arranged on a thread loosening shaft 18 of the thread loosening mechanism, the other end is provided with a thread loosening lever 19, the thread loosening lever 19 is arranged in the thread loosening driving hole 16, one end of the thread cutting driving push block 3 is fixedly arranged on the thread cutting shaft 20, the other end is arranged in the air and is provided with a second roller 21 which is in abutting fit with the thread cutting cam 6. Similarly, the second roller 21 usually adopts a deep groove ball bearing.

[0040] Specifically, the first idle stroke section 7 of the presser foot and thread loosening cam 5 is an equal-diameter circular arc surface, the second idle stroke section 9 of the thread cutting cam 6 is an equal-diameter circular arc surface, the presser foot and thread loosening driving section 8 of the presser foot and thread loosening cam 5 is a variable-diameter cam surface, the variable-diameter cam surface can control the lifting height of the presser foot 22. The thread cutting driving section 10 of the thread cutting cam 6 is a variable-diameter cam surface; the two cams are rotated with the driving shaft of the double-head motor 1, drive the first roller 12 and the second roller 21 to move respectively, realize the actions of the automatic presser foot lifting, the thread loosening and the thread cutting by the same power source, and the three actions do not interfere with each other, specifically:

[0041] When the presser foot and thread loosening driving section 8 of the presser foot and thread loosening cam 5 is in abutting fit with the first roller 12, the second idle stroke section 9 of the thread cutting cam 6 is in abutting fit with the second roller 21, at this time, the presser foot and thread loosening driving section 8 drives the first roller 12 to move downward, drives the presser foot lifting crank 2 to rotate downward, further drives the presser foot lever shaft 11 to rotate, the rotation of the presser foot lever shaft 11 drives the press rod guide bracket connecting plate 41 to lift upward, the press rod guide bracket connecting plate 41 drives the press rod guide bracket 43 to move upward, at the same time, the presser foot shaft 42 also moves upward through the press rod guide bracket 43, thus the action of the automatic presser foot lifting is completed.

[0042] In addition, the pressing block 13 on the presser foot lifting crank 2 also moves downward with the presser foot lifting crank 2, acts on the thread loosening driving lever 4, drives the thread loosening driving lever 4 to rotate around a section thereof, the thread loosening lever 19 in the thread loosening driving hole 16 drives the thread loosening crank 17 to rotate clockwise (here, clockwise is taken as the reference direction), the thread loosening shaft 18 also rotates clockwise, drives the thread loosening plate 44 connected to the other end of the thread loosening shaft 18 to move downward, and the thread loosening effect is achieved. Figure 1 、 Figure 2 、 Figure 5 、 Figure 6 The setting position is taken as the reference), the thread loosening shaft 18 also rotates clockwise, drives the thread loosening plate 44 connected to the other end of the thread loosening shaft 18 to move downward, and the thread loosening effect is achieved.

[0043] Since the second idle stroke section 9 is a constant diameter section, the thread cutting driving push block 3 does not displace, and the thread cutting mechanism does not act.

[0044] When the thread cutting driving section 10 of the thread cutting cam 6 is in abutting cooperation with the second roller 21, the first idle stroke section 7 of the presser foot lifting and thread loosening cam 5 is in abutting cooperation with the first roller 12, at this time, the thread cutting driving section 10 acts on the second roller 21 to drive the thread cutting driving push block 3 to move downward, further drives the thread cutting shaft 20 to move downward to drive the thread cutter 23 to move downward to cut the material, and the automatic thread cutting action is completed; since the first idle stroke section 7 is a constant diameter section, the first roller 12 does not displace, and the presser foot lifting mechanism and the thread loosening mechanism do not act.

[0045] It should be noted that the presser foot lifting mechanism and the thread loosening mechanism of the present application are conventional structures in the field, and the thread cutting mechanism also has various existing mechanisms, which are not described in detail in the present embodiment. Since the thread cutting mechanism is various, the present embodiment preferably has the following structure: the thread cutting mechanism comprises a mounting seat 24 arranged on the machine shell 15, a sliding plate 25 arranged at the lower end of the mounting seat 24, a thread cutter 23 slidably arranged on the sliding plate 25 through a sliding block, the thread cutting shaft 20 movably arranged on the mounting seat 24 and capable of reciprocating along the axial direction of the mounting seat 24, a retaining ring 26 and a thread cutting return spring 27 further sleeved on the thread cutting shaft 20, one end of the thread cutting return spring 27 abutting on the retaining ring 26 and the other end abutting on the mounting seat 24, and a driving frame 28 arranged at the lower end of the thread cutting shaft 20 and connected with the sliding block.

[0046] As can be seen from the above, the thread cutting shaft 20 is driven by the thread cutting driving push block 3 to move downward, the thread cutting return spring 27 is compressed, further drives the driving frame 28 and the sliding block to move downward, and finally drives the thread cutter 23 to move downward to cut the material. When the force acting on the thread cutting driving push block 3 disappears, the thread cutting return spring 27 resets the thread cutting shaft 20, the thread cutting driving push block 3 and the thread cutter 23. At the same time, the thread cutting return spring 27 can also ensure that the second roller 21 is in abutting cooperation with the second idle stroke section 9 or the thread cutting driving section 10 of the thread cutting cam 6.

[0047] Further, the presser foot crank 2 comprises a presser foot crank body 29 and a bent plate 30 at the other end of the presser foot crank body 20, the first roller 12 is rotatably connected to the other end of the presser foot crank body 20 through a roller shaft, and the presser block 13 is arranged on the bent plate 30 through fasteners.

[0048] The presser foot crank 2 is provided with a presser foot crank stop ring 31 and a presser foot crank spacer 32 on the presser foot lever shaft 11 at both sides, respectively, one end of the presser foot crank spacer 32 is tightly abutted against the shaft sleeve of the presser foot lever shaft 11, and the other end is tightly abutted against the presser foot crank 2, in addition, in order to realize the rotation of the presser foot crank 2 driving the presser foot lever shaft 11, the presser foot crank 2 is provided with a notch 45, and the presser foot crank stop ring 31 is provided with an extension part which is clamped in the notch 45. In addition to the above-mentioned mode, a spline groove can also be arranged on the hole wall of the hole of the presser foot crank 2 where the presser foot lever shaft 11 is installed, and a spline is arranged on the presser foot lever shaft 11, and such structure can also realize the linkage of the presser foot crank 2 and the presser foot lever shaft 11. At the same time, the presser foot crank stop ring 31 and the presser foot crank spacer 32 together axially limit the presser foot crank 2.

[0049] In order to ensure that the first roller 12 is in abutting cooperation with the first idle stroke section 7 or the presser foot and thread loosening driving section 8 of the presser foot and thread loosening cam 5, a first reset torsion spring 33 is sleeved on the presser foot crank spacer 32, the first arm of the first reset torsion spring 33 is inserted on the shell 15, and the second arm is abutted against the bottom surface of the presser foot crank 2, the first reset torsion spring 33 drives the presser foot crank 2 to reset in time.

[0050] In order to ensure that the thread loosening driving lever 4 resets in time, the second reset torsion spring 34 is arranged, a convex column 35 is arranged on the shell 15, one end of the thread loosening driving lever 4 is rotatably connected to the convex column 35, the second reset torsion spring 34 is sleeved on the convex column 35, the third arm of the second reset torsion spring 34 is inserted on the shell 25, and the fourth arm is abutted against the bottom surface of the thread loosening driving lever 4.

[0051] In order to further realize automation, the present application further comprises a lower light eye assembly arranged on the sewing table 36 and an upper light eye assembly 37 arranged on the machine housing 15. Specifically, the lower light eye assembly comprises a first lower light eye 38, a second lower light eye 39 and a third lower light eye 40, and the upper light eye assembly 37 comprises a first upper light eye, a second upper light eye and a third upper light eye which are respectively in alignment with the first lower light eye 38, the second lower light eye 39 and the third lower light eye 40. The upper light eye assembly 37 and the lower light eye assembly are connected with the controller, and signals are sent to the controller so as to control the automatic lifting of the presser foot, the loosening of the thread and the driving of the thread cutting mechanism. In the present embodiment, the first upper light eye and the first lower light eye 38 control the automatic lifting of the presser foot, the loosening of the thread and the driving of the thread cutting mechanism to drive the lifting and lowering of the presser foot 22. The second upper light eye and the second lower light eye 39 control the automatic lifting of the presser foot, the loosening of the thread and the driving of the thread cutting mechanism to drive the lowering of the cutting knife 23 to cut the material (such as a thread braid or a cloth strip or an elastic band). The third upper light eye and the third lower light eye 40 control the automatic lifting of the presser foot, the loosening of the thread and the driving of the thread cutting mechanism to prevent the cutting of the material when the material passes through the presser foot 22 but does not pass through the third lower light eye 40.

[0052] The cutting of the thread is controlled by the upper light eye assembly 37 and the lower light eye assembly, and the material (such as a thread braid or a cloth strip or an elastic band) left on the sewing material after cutting is relatively short, and the loss of the material is small. For example, when an elastic band is placed on the sewing material and the two are sewn together, the elastic band needs to be cut after the sewing is completed. The elastic band left on the sewing material is relatively short, the loss of the elastic band is reduced, and the cost of the user is reduced.

[0053] Embodiment 2

[0054] The present embodiment provides an automatic sewing and cutting method of a sewing machine, which comprises the following steps:

[0055] Step S1: When the sewing material covers the first lower light eye 38, the alignment between the first upper light eye and the first lower light eye 38 is blocked, and the controller receives the signal to control the lifting of the presser foot mechanism to lift the presser foot 22.

[0056] Step S2: The worker manually drives the sewing material to continue to move forward to below the presser foot 22, and after a certain time is delayed by the controller, the presser foot mechanism is controlled to lower the presser foot 22, and the sewing machine starts the sewing work.

[0057] It should be noted that the specific time of the delay is set according to the actual processing condition, such as 5 seconds, 10 seconds, etc.

[0058] The first upper light eye and the first lower light eye 38 control the lifting and lowering of the presser foot 22 without manual control, and the degree of automation is high.

[0059] Step S3, the sewing material is moved forward during the sewing process, usually by the feeding tooth driving the sewing material to move, when the sewing material moves to cover the second lower light eye 39, the light transmission between the second upper light eye and the second lower light eye 39 is blocked, the controller receives the signal to control the action of the cutting mechanism to drive the cutting knife 23 to cut the material (thread cutting braid or cloth strip or elastic band, etc.) at the front end of the sewing material, and then reset;

[0060] It should be noted that in the original state, the cutting knife 23 is in the raised state.

[0061] Step S4, the sewing material continues to sew to the second lower light eye 39, the controller delays for a certain time to control the action of the cutting mechanism to cut the material (thread cutting braid or cloth strip or elastic band, etc.) at the rear end of the sewing material, and then reset;

[0062] Similarly, the specific time of the delay is set according to the actual processing condition, such as 5 seconds, 10 seconds, etc.

[0063] This step can ensure that the length of the material left on the sewing material after cutting is short, thereby improving the precision.

[0064] Step S5, when the sewing material passes the presser foot 22 but has not passed the third lower light eye 40, the light transmission between the third upper light eye and the third lower light eye 40 is in a blocked state, and the cutting mechanism does not act, which can prevent accidental cutting and improve safety, and can also prevent the sewing material from being cut and damaged, thereby improving the product yield.

[0065] The above method can be applied to a sewing machine with an automatic presser foot lifting mechanism and an automatic thread cutting mechanism. When the presser foot is lifted, the driver of the automatic presser foot lifting mechanism is controlled by the controller to act, and when the cloth needs to be cut, the driver of the automatic thread cutting mechanism is controlled by the controller to act.

[0066] In order to make the structure more compact, the embodiment further provides a driving mechanism for simultaneously driving the lifting of the presser foot mechanism and the action of the thread cutting mechanism, such as the automatic presser foot, thread loosening and thread cutting driving mechanism driving action described in Embodiment 1.

[0067] The above embodiments are only one of the preferred embodiments of the present application, and do not limit the scope of the present application, so: any equivalent changes made in shape, structure, principle according to the present application should be covered within the protection scope of the present application.

Claims

1. A sewing machine characterized by: The automatic lifting presser foot, thread loosening, thread cutting drive mechanism, lifting presser foot mechanism, thread loosening mechanism and thread cutting mechanism, the automatic lifting presser foot, thread loosening, thread cutting drive mechanism includes double head motor (1), lifting presser foot crank (2), thread cutting drive push block (3), thread loosening drive lever (4), the two ends of the drive shaft of double head motor (1) are respectively provided with lifting presser foot and thread loosening cam (5), thread cutting cam (6), the lifting presser foot and thread loosening cam (5) include first empty stroke section (7), lifting presser foot and thread loosening drive section (8), the thread cutting cam (6) includes second empty stroke section (9), thread cutting drive section (10), the one end of the lifting presser foot crank (2) is connected with the lifting presser foot mechanism's lifting presser foot lever shaft (11), the other end is provided with first roller (12), press block (13), the first roller (12) is in abutment with the lifting presser foot and thread loosening cam (5), the thread loosening drive lever (4) is located below the press block (13), one end of thread loosening drive lever (4) is rotatably connected with the shell (15), the other end is provided with thread loosening drive hole (16), one end of thread loosening crank (17) is fixed on the thread loosening mechanism's thread loosening shaft (18), the other end is provided with thread loosening lever (19), the thread loosening lever (19) is arranged in the thread loosening drive hole (16), one end of the thread cutting drive push block (3) is fixed on the thread cutting shaft (20), the other end is suspended and is provided with the second roller (21) in abutment with the thread cutting cam (6);The lifting presser foot crank (2) includes lifting presser foot crank main body (29) and the bending plate (30) at the other end of lifting presser foot crank main body (29), the first roller (12) is rotatably connected at the other end of lifting presser foot crank main body (29) by roller shaft, the press block (13) is arranged on the bending plate (30) by fastener.

2. A sewing machine according to claim 1, characterized in that: The first empty stroke section (7) is equal-diameter circular arc surface, the second empty stroke section (9) is equal-diameter circular arc surface, the lifting presser foot and thread loosening drive section (8) is variable-diameter cam surface, the thread cutting drive section (10) is variable-diameter cam surface; When the lifting presser foot and thread loosening drive section (8) of the lifting presser foot and thread loosening cam (5) is in abutment with the first roller (12), the second empty stroke section (9) of the thread cutting cam (6) is in abutment with the second roller (21); When the thread cutting drive section (10) of the thread cutting cam (6) is in abutment with the second roller (21), the first empty stroke section (7) of the lifting presser foot and thread loosening cam (5) is in abutment with the first roller (12).

3. A sewing machine according to claim 1 or 2, characterised in that: The lifting presser foot lever shaft (11) on the two sides of the lifting presser foot crank (2) is respectively provided with lifting presser foot crank stop ring (31) and lifting presser foot crank spacer (32), the lifting presser foot crank (2) is provided with notch (45), the lifting presser foot crank stop ring (31) is provided with extension, the extension is located in the notch (45) of the lifting presser foot crank (2), one end of the lifting presser foot crank spacer (32) is abutted on the corresponding shaft sleeve of the lifting presser foot lever shaft (11), the lifting presser foot crank spacer (32) and the lifting presser foot crank stop ring (31) axially limit the lifting presser foot crank (2).

4. A sewing machine according to claim 3, characterised in that: The lifting presser foot crank spacer (32) is sleeved with a first reset torsion spring (33), the first arm of the first reset torsion spring (33) is inserted on the casing (15), and the second arm abuts against the bottom surface of the lifting presser foot crank (2).

5. A sewing machine according to claim 1 or 2, characterised in that: A convex column (35) is arranged on the casing (15), one end of the thread loosening driving lever (4) is rotatably connected on the convex column (35), the convex column (35) is sleeved with a second reset torsion spring (34), the third arm of the second reset torsion spring (34) is inserted on the casing (15), and the fourth arm abuts against the bottom surface of the thread loosening driving lever (4).

6. The sewing machine of claim 1, wherein: The thread cutting mechanism comprises a mounting seat (24) arranged on the casing (15), a sliding plate (25) is arranged at the lower end of the mounting seat (24), a thread cutter (23) is slidably arranged on the sliding plate (25) through a sliding block, the thread cutting shaft (20) is movably arranged on the mounting seat (24) and can reciprocate up and down along the axial direction of the mounting seat (24), a stop ring (26) and a thread cutting reset spring (27) are further sleeved on the thread cutting shaft (20), one end of the thread cutting reset spring (27) abuts against the stop ring (26), and the other end abuts against the mounting seat (24), a driving frame (28) is arranged at the lower end of the thread cutting shaft (20), and the driving frame (28) is connected with the sliding block.

7. A sewing machine according to claim 1 or 2, characterised in that: Further comprising a lower light eye assembly arranged on the sewing table (36) and an upper light eye assembly (37) arranged on the casing (15), the lower light eye assembly comprises a first lower light eye (38), a second lower light eye (39) and a third lower light eye (40), the upper light eye assembly (37) comprises a first upper light eye, a second upper light eye and a third upper light eye which are respectively in alignment with the first lower light eye (38), the second lower light eye (39) and the third lower light eye (40), the first upper light eye and the first lower light eye (38) control the automatic lifting presser foot, thread loosening and thread cutting driving mechanism to drive the lifting and releasing of the presser foot, the second upper light eye and the second lower light eye (39) control the automatic lifting presser foot, thread loosening and thread cutting driving mechanism to drive the thread cutting cutter (23) to cut the thread braid or cloth strip or elastic band, and the third upper light eye and the third lower light eye (40) control the automatic lifting presser foot, thread loosening and thread cutting driving mechanism to be inactivated when the sewing material passes through the presser foot (22) and does not pass through the third lower light eye (40).

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