Knitting machine yarn untwisting device and method for untwisting composite yarn

Abstract

The present invention discloses a yarn untwisting device for a knitting machine and a method for untwisting a composite yarn, comprising an upper cover, a lower cover and a side cover which are mutually connected by bolts, a mounting frame being rotatably arranged in the side cover, a fixed shaft and an upper pressing ball head being arranged on the mounting frame, a down-pressing device being arranged in the upper cover and the lower cover, the down-pressing device comprising a pressing block, a piston and a first spring, a space for the piston to extend and slide in the upper cover and the lower cover, and an upper end of the piston having a spherical surface with a diameter smaller than that of the upper pressing ball head, the present invention utilizes that eddy air is formed in the cavity of the spherical surface after gas passes through an airway, the eddy air generates a force in the gas swirl direction on the yarn between the clamping positions, so that the organizational structure of the section of the yarn is broken up, and the clamping position still retains the original shape, so that the partial untwisting of the yarn can be achieved, and the yarn composited after the partial untwisting will not have the problem of side yarn stripping when the cloth is woven by the knitting machine.

Description

Technical Field

[0001] The invention discloses a knitting machine yarn untwisting device and a method for untwisting composite yarn, belonging to the technical field of textile production. Background Art

[0002] Weaving is to twist many animal and plant fibers together to spin them into threads or yarns, which can be used to weave cloth. In the process of knitting cloth, twisting is an important part of the spinning and knitting process. If one end of the spinning is held and the other end is rotated, yarn can be formed. This process is called twisting. Twisting is the process of twisting the thin strips after drafting by rotating motion, like twisting a towel when washing your face, so as to fix the longitudinal connection between the fibers. The twisted yarn is the composite yarn. For fabrics that need to meet different functional requirements, in order to increase their richness, multiple different materials are usually twisted to form composite yarns. However, since the yarns of the two materials are twisted together by twisting, the degree of adhesion between the yarns is limited, and it is very easy to become loose, and there is also torque between them. Especially at the natural length, the yarn is extremely easy to self-wind, which affects the yarn change and subsequent weaving process, and the woven fabric will have the phenomenon of yarn stripping. Therefore, to address this problem, it is necessary to produce a yarn processing device that is convenient for subsequent yarn compounding, can eliminate the torque of the composite yarn, and can also avoid yarn stripping after weaving. Summary of the invention

[0003] The purpose of the present invention is to solve the problems in the prior art and to provide a knitting machine yarn untwisting device and a method for untwisting composite yarn.

[0004] The present invention achieves the above-mentioned purpose through the following technical scheme: a yarn untwisting device for a knitting machine, comprising an upper cover, a lower cover and a side cover connected to each other by bolts, characterized in that a mounting frame is rotatably arranged in the side cover, a fixed shaft and an upper pressure ball head are arranged on the mounting frame, a down-pressor is arranged in the upper cover and the lower cover, the down-pressor comprises a pressure block, a piston and a first spring, a space for the piston to extend and slide in the upper cover and the lower cover, and the upper end of the piston has a spherical surface with a diameter smaller than the upper pressure ball head, the first spring has a force to keep the upper pressure ball head in contact with the spherical surface, an annular groove is arranged on the piston, and first sealing rings are installed on both sides of the piston corresponding to the annular groove, a closed air cavity is formed at the position of the first sealing ring, the piston and the upper cover corresponding to the annular groove, an air nozzle communicated with the air cavity is arranged on the upper cover, the air nozzle can inflate the air cavity and overcome the elastic force of the first spring, the piston has an air channel with a truncated cone structure, and the end with a small diameter of the air channel extends to the spherical surface.

[0005] Preferably, the piston includes a movable shaft and an inlay block fixedly connected by bolts, the upper pressure ball head and the inlay block are both made of ceramics, the air channel runs through the movable shaft and the inlay block at the same time, and a second sealing ring is provided on the side close to the movable shaft and the inlay block.

[0006] Preferably, there is a transmission mechanism between the mounting frame and the movable shaft, and the transmission mechanism includes a toothless tooth block, a first driven gear, a driven shaft and a second driven gear. The toothless tooth block is connected to the mounting frame, and the driven shaft is rotatably installed between the upper cover and the lower cover. The first driven gear is meshed with the toothless tooth block and the second driven gear, and the second driven gear is installed on the movable shaft. A wedge-shaped driving mechanism is provided between the pressure block and the movable shaft, which can overcome the elastic force of the first spring when the mounting frame is rotated.

[0007] Preferably, the wedge-shaped driving mechanism includes a first supporting surface, a first inclined surface, a second supporting surface and a second inclined surface which are sequentially located on the movable axis, the second supporting surface is higher than the first supporting surface, and the central angle formed by the first supporting surface, the first inclined surface, the second supporting surface and the second inclined surface is equal to the rotation angle of the mounting frame.

[0008] Preferably, a force unloading mechanism is provided on the driven shaft, and the force unloading mechanism includes a limiting bolt, a second spring and a stopper. The limiting bolt passes through the stopper and is threadedly connected to the driven shaft. The second spring is located on the outside of the limiting bolt and can apply a force to the stopper to press against the driven shaft.

[0009] Preferably, the side cover is provided with a groove for limiting the rotation angle of the mounting bracket, and the mounting bracket is provided with a third spring for applying a downward force to the fixed shaft.

[0010] Preferably, a fixing block is provided in the side cover, a limiting column for positioning the tooth block with missing teeth is provided at one end of the mounting frame, and the fixing block is connected to the limiting column by a fastening bolt.

[0011] A method for untwisting a composite yarn comprises the following steps:

[0012] S1: Selecting a first yarn and a second yarn that meet the requirements, and feeding them independently by a yarn feeder;

[0013] S2: The first yarn is first subjected to a heating and expansion treatment, and then conveyed to the untwisting device, the upper pressing ball head and the inlay block are kept clamping two places of the first yarn, the yarn between the two places is wrapped on the surface of the upper pressing ball head, and the gas supply device blows gas with a certain pressure from the air channel in an intermittent manner, and the gas nozzle also intermittently introduces gas, so that the movable shaft produces an intermittent telescopic action, so that the upper pressing ball head and the inlay block intermittently clamp the first yarn, and form loose sections and tight sections arranged at intervals on the first yarn;

[0014] S3: The first yarn processed by the untwisting device and the second yarn are simultaneously conveyed by the yarn feeder to the doubling machine for doubling, and a local position of the second yarn is kept wrapped by the loose section of the first yarn.

[0015] Preferably, the second yarn is also processed by the untwisting device before being doubly-wound with the first yarn.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] By setting an upper pressure ball head and a piston, the upper pressure ball head can clamp two positions of the yarn when it contacts the piston, and by intermittent and continuous blowing from the airway, the gas will form vortex air in the cavity of the spherical surface after passing through the airway. The vortex air generates a force in the direction of the gas swirl on the yarn between the clamping positions, so that the organizational structure of the section of yarn is broken up, and the clamped position still retains its original shape, so that the partial untwisting of the yarn can be achieved. The yarn formed by the partial untwisting will not have side yarn detwisting when it is woven by a knitting machine.

[0018] An annular groove is provided on the piston, and a cylinder is formed under the action of the first sealing ring. After gas is introduced into the air nozzle, the piston compresses the first spring, allowing the piston to break away from the resistance state of the upper pressing ball head, thereby releasing the clamping state of the yarn after the first small section of yarn is untwisted, and the yarn is smoothly fed under the action of the yarn feeder, so that continuous and automatic partial untwisting operation of the yarn can be realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic structural diagram of a first state of a yarn untwisting device for a knitting machine according to the present invention;

[0020] Figure 2 The second state structure diagram of a yarn untwisting device for a knitting machine according to the present invention is shown in FIG. Figure 1 ;

[0021] Figure 3 The second state structure diagram of a yarn untwisting device for a knitting machine according to the present invention is shown in FIG. Figure 2 ;

[0022] Figure 4 It is a schematic diagram of the installation structure of the piston, the upper cover and the lower cover in the present invention;

[0023] Figure 5 It is a structural schematic diagram of the transmission mechanism in the present invention;

[0024] Figure 6 It is a structural schematic diagram of the wedge-shaped driving mechanism in the present invention;

[0025] Figure 7 It is a structural schematic diagram of the force unloading mechanism in the present invention;

[0026] Figure 8 It is a structural schematic diagram of the upper pressing ball head and the inlay block in the present invention;

[0027] Fig. 9 It is a schematic diagram of the structure of the side cover in the present invention;

[0028] Fig.10 It is a schematic diagram of the structure of the first yarn after being processed by the untwisting device.

[0029] 1. The camshaft is provided with a plurality of locking cams, and a plurality of locking cams are provided with a plurality of locking cams. The plurality of locking cams are provided with a plurality of locking cams. The plurality of locking cams are provided with a plurality of locking cams. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] like Figure 1-Figure 10 As shown, a yarn untwisting device for a knitting machine comprises an upper cover 6, a lower cover 5 and a side cover 2, wherein the upper cover 6 and the lower cover 5 are divided into two parts in half according to the maximum outer contour of the entire device and are fastened by bolts, and the mounting surfaces of the side cover 2, the upper cover 6 and the lower cover 5 are a plane, which are also connected by bolts, and the three are easy to assemble, and a mounting frame 1 is rotatably arranged on the side cover 2, and the mounting frame 1 is provided with a fixed shaft 34 and an upper pressure ball head 8, and the lower end of the mounting frame 1 is rotatably mounted in the side cover 2, and the upper pressure ball head 8 is movably mounted on the mounting frame 1 through the fixed shaft 34, and a third spring is also arranged in the mounting frame 1, and the third spring has the function of maintaining a downward force on the fixed shaft 34, so that when the upper pressure ball head 8 is pressed upward, the third spring is compressed, and the distance between the third spring and the mounting frame 1 is reduced, and when the pressing state is cancelled, the upper pressure ball head 8 is reset under the action of the third spring. Due to the simple principle, the mounting structure of the third spring is not drawn in the figure.

[0032] Secondly, a down-pressor is arranged inside the upper cover 6 and the lower cover 5, and the main structure of the down-pressor is composed of a pressure block 9, a piston 7 and a first spring 16, wherein the pressure block 9 is fixedly connected to the upper cover 6 by bolts, and the piston 7 is restricted in a space 17 formed by the upper cover 6 and the lower cover 5, and the first spring 16 has a force to keep the piston 7 protruding from the surface of the pressure block 9, and at the same time, one end of the piston 7 protruding from the surface of the pressure block 9 has a spherical surface 20, and the diameter of the spherical surface 20 is smaller than the diameter of the upper pressure ball head 8. When the upper pressure ball head 8 conflicts with the piston 7, the surface of the upper pressure ball head 8 is closely attached to the maximum diameter contour of the spherical surface 20, and the yarn can be clamped when passing between the two, and an air channel 10 is also arranged on the piston 7, and the air channel 10 has a small diameter at one end and a large diameter at the other end. The truncated cone structure has a large diameter, and the end with a small diameter extends to the spherical surface 20. When a certain pressure of gas is quantitatively introduced into the airway 10 instantaneously, a vortex is formed after the gas enters the spherical surface 20 from the airway 10. The principle is the same as that of an air vortex cannon. In this way, vortex gas is generated and an impact force is exerted on the yarn. The yarn located in the spherical surface 20 is attached to the surface of the upper pressure ball head 8 and is subjected to the torsion force of the vortex gas, so that its organizational structure gradually disperses, and the effect of untwisting is achieved through multiple intermittent impacts. The two places where the yarn is clamped by the upper pressure ball head 8 and the edge of the spherical surface 20 are not affected by the gas, thereby forming a loose section 38 and a tight section 37 structure on the yarn. The loose section 38 is composed of the single fibers that make up the yarn in a dispersed state.

[0033] In order to enable the yarn to be partially untwisted continuously, an annular groove 25 is provided on the piston 7, and a first sealing ring 15 is installed on both sides of the annular groove 25. The first sealing ring 15 cooperates with the upper cover 6 and the lower cover 5 to achieve sealing, thereby forming a closed air cavity 19, and an air nozzle 4 is provided on the upper cover 6, and the air nozzle 4 is connected to the air cavity 19. When a certain amount of gas is continuously introduced into the air nozzle 4, the air pressure in the air cavity 19 increases, thereby compressing the first spring 16, and causing the piston 7 to gradually retract into the upper cover 6 and separate from the upper pressure ball head 8. At this time, the yarn is no longer clamped, and after the yarn feeder pulls the yarn for a distance, the air pressure in the air cavity 19 is reduced through the air nozzle 4, and the piston 7 is reset under the action of the first spring 16, thereby achieving the effect of clamping the yarn again. Such a reciprocating cycle can realize the continuous automatic partial untwisting action of the yarn without manual intervention, which can effectively improve the efficiency of automated production. The piston 7 includes a movable shaft 12 and an inlaid block 11, which are fastened by bolts. The upper pressure ball head 8 and the inlaid block 11 are made of ceramics, which can reduce the wear when the yarn is clamped and avoid yarn breakage. It is also beneficial to yarn feeding. The airway 10 runs through the movable shaft 12 and the inlaid block 11 at the same time, and a second sealing ring 28 is provided on the side close to the movable shaft 12 and the inlaid block 11. The second sealing ring 28 can reduce the overflow of gas.

[0034] At the same time, the mounting frame 1 and the movable shaft 12 are provided with a transmission mechanism, which includes a toothless tooth block 22, a first driven gear 21, a driven shaft 33 and a second driven gear 14. The toothless tooth block 22 is connected to the mounting frame 1, and the driven shaft 33 is rotatably installed between the upper cover 6 and the lower cover 5. The first driven gear 21 is meshed with the toothless tooth block 22 and the second driven gear 14. The second driven gear 14 is installed on the movable shaft 12. A wedge-shaped driving mechanism 13 is provided between the pressure block 9 and the movable shaft 12, which can overcome the elastic force of the first spring 16 when the mounting frame 1 is rotated. When disassembling and repairing parts, the upper pressure ball head 8 needs to be moved. After rotating a certain angle from the position of contacting the piston 7, it is located on its side. At this time, the toothless tooth block 22 is rotated, and the first driven gear 21 and the second driven gear 14 are driven to rotate at the same time. When the second driven gear 14 rotates, the wedge-shaped driving mechanism 13 will be subjected to the force of the pressure block 9, and the force is transmitted to the movable shaft 12 to compress the first spring 16, thereby forcing the piston 7 to slowly retract into the upper cover 6 to reduce the contact force between it and the upper pressure ball head 8, thereby reducing the wear of the two. When the two are separated, the wedge-shaped driving mechanism 13 cancels the force on the piston 7, and the piston 7 is reset under the action of the first spring 16.

[0035] The main structure of the wedge-shaped driving mechanism 13 is composed of a first supporting surface 24, a first inclined surface 26, a second supporting surface 27 and a second inclined surface 29. The first supporting surface 24, the first inclined surface 26, the second supporting surface 27 and the second inclined surface 29 are sequentially connected and arranged on the movable shaft 12. The central angle formed by the four is equal to the rotation angle of the mounting frame 1. At the same time, the second supporting surface 27 is higher than the first supporting surface 24, and the central angle of the first supporting surface 24 is the largest. The pressure block 9 is provided with a structure that matches the first supporting surface 24, the first inclined surface 26, the second supporting surface 27 and the second inclined surface 29. When the upper pressure ball head 8 is not in contact with the piston 7, the height of the piston 7 protruding from the pressure block 9 is the largest. At this time, the rotating mounting frame 1 causes the toothless tooth block 22 to mesh with the first driven gear 21 for transmission, and enables The second driven gear 14 rotates synchronously with the movable shaft 12, thereby causing the movable shaft 12 and the pressure block 9 to be misaligned, and the first supporting surface 24 slides to the position of the original first inclined surface 26, so that the second supporting surface 27 is forced to be pressed by the pressure block 9 to cause the movable shaft 12 to descend and compress the first spring 16, so that before the upper pressure ball head 8 contacts the piston 7, the piston 7 is first retracted to form an escape space 17. When the upper pressure ball head 8 slides above the piston 7, the piston 7 slowly resets when the matching position of the movable shaft 12 and the pressure block 9 changes, and reaches the final interference state. The overall structural design is ingenious and simple, thereby effectively reducing the loss caused by the friction between the two, avoiding the generation of a large gap when the yarn is untwisted and affecting its clamping state, thereby ensuring the smooth progress of the untwisting action.

[0036] In this embodiment, a force unloading mechanism 3 is provided on the driven shaft 33, and the force unloading mechanism 3 includes a limiting bolt 31, a second spring 30 and a stopper 32. The limiting bolt 31 passes through the stopper 32 and is threadedly connected to the driven shaft 33. The second spring 30 is located on the outer side of the limiting bolt 31 and can apply a force to the stopper 32 to press against the driven shaft 33. When the air pressure in the air chamber 19 decreases, the piston 7 is quickly reset under the action of the first spring 16. At this time, the stopper 32 will first be subjected to the instantaneous impact force of the piston 7, and a part of it will be offset by the second spring 30 to achieve the effect of unloading, thereby effectively reducing the piston 7 from acting The force is fully transmitted to the upper pressure ball head 8, so as to avoid damage to the parts due to excessive force of the collision between the two, effectively prolonging the service life of the device and reducing the number of maintenance times. In addition, a groove 36 for limiting the rotation angle of the mounting frame 1 is provided on the side cover 2, and the operator can accurately know whether the upper pressure ball head 8 and the piston 7 are assembled in place. A fixing block 18 is provided in the side cover 2, and a limiting column 23 for positioning the toothed tooth block 22 is provided at one end of the mounting frame 1. The fixing block 18 is connected to the limiting column 23 by fastening bolts. The limiting column 23 can be used to accurately locate the installation position of the toothed tooth block 22, which is convenient for the assembly of parts.

[0037] A method for untwisting a composite yarn comprises the following steps:

[0038] S1: Selecting a first yarn 35 and a second yarn that meet the requirements, and feeding them independently by yarn feeders;

[0039] S2: The first yarn 35 is first heated and expanded, and then conveyed to the untwisting device, the upper pressing ball head 8 and the inlay block 11 are kept clamping two places of the first yarn 35, and the yarn between the two places is wrapped on the surface of the upper pressing ball head 8, and the gas supply device blows gas with a certain pressure from the air channel 10 in an intermittent manner, and the gas nozzle 4 also intermittently passes gas, so that the movable shaft 12 produces an intermittent telescopic action, so that the upper pressing ball head 8 and the inlay block 11 intermittently clamp the first yarn 35, and form loose sections 38 and tight sections 37 arranged at intervals on the first yarn 35;

[0040] S3: The first yarn 35 and the second yarn processed by the untwisting device are simultaneously conveyed by the yarn feeder to the doubling machine for doubling, and a local position of the second yarn is kept wrapped by the loose section 38 of the first yarn 35.

[0041] The composite yarn prepared by the method of the present invention relies on the loose section 38 of the first yarn 35 to cover the second yarn when the yarns are combined, and the two yarns are held together by the action of the yarn doubling machine. Since there is no twisting and twisting state between the two, there is no torque after the composite yarn is prepared, and no twisting and winding will occur in the natural state, thereby ensuring that the yarn weaving process is not affected. At the same time, when there is a color difference between the first yarn 35 and the second yarn, when the loose section 38 of the first yarn 35 covers the second yarn, only the color of the first yarn 35 is visually retained, and the color of this section is long The degree of the first yarn 35 depends on the length of the loose section 38, and the tight section 37 of the first yarn 35 does not cover the second yarn. Since the distance of this section is not long, the two will be close together and mixed colors after being processed by the yarn doubling machine, thereby forming another color that distinguishes the first yarn 35 from the second yarn, especially when the second yarn is partially untwisted in the same way as the first yarn 35, and then combined in the yarn doubling, thereby forming two or three colors. When the fabric is woven using the composite yarn, it can have different visual perceptions without making changes to the fabric structure, which greatly enriches the clothing manufacturing style.

[0042] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0043] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A yarn untwisting device for a knitting machine, comprising an upper cover (6), a lower cover (5) and a side cover (2) connected to each other by bolts, characterized in that: A mounting frame (1) is rotatably arranged in the side cover (2), a fixed shaft (34) and an upper pressing ball head (8) are arranged on the mounting frame (1), a presser is arranged in the upper cover (6) and the lower cover (5), the presser comprises a pressing block (9), a piston (7) and a first spring (16), a space (17) for the piston (7) to slide and retract in the upper cover (6) and the lower cover (5), and the upper end of the piston (7) has a spherical surface (20) with a diameter smaller than that of the upper pressing ball head (8), and the first spring (16) has a force to keep the upper pressing ball head (8) in contact with the spherical surface (20), The piston (7) is provided with an annular groove (25), and first sealing rings (15) are installed on both sides of the piston (7) corresponding to the annular groove (25); a sealed air cavity (19) is formed by the first sealing ring (15), the piston (7) and the upper cover (6) at a position corresponding to the annular groove (25); the upper cover (6) is provided with an air nozzle (4) in communication with the air cavity (19); the air nozzle (4) can inflate the air cavity (19) and overcome the elastic force of the first spring (16); the piston (7) is provided with an air channel (10) in a truncated cone structure; a portion of the air channel (10) having a smaller diameter is provided with a gas nozzle (4) in communication with the air cavity (19); and a portion of the gas nozzle (4) in communication with the upper cover (6) is provided with a gas nozzle (4) in communication with the air cavity (19) and can inflate the air cavity (19) and overcome the elastic force of the first spring (16). The end of the mounting frame (1) extends to the spherical surface (20), and a transmission mechanism is provided between the mounting frame (1) and the movable shaft (12), wherein the transmission mechanism comprises a toothless tooth block (22), a first driven gear (21), a driven shaft (33) and a second driven gear (14), wherein the toothless tooth block (22) is connected to the mounting frame (1), and the driven shaft (33) is rotatably mounted between the upper cover (6) and the lower cover (5), wherein the first driven gear (21) meshes with the toothless tooth block (22) and the second driven gear (14), and the second driven gear (14) is mounted on the movable shaft (12), and the pressing block ( A wedge-shaped driving mechanism (13) is provided between the movable shaft (9) and the movable shaft (12) and can overcome the elastic force of the first spring (16) when the mounting frame (1) is rotated. The wedge-shaped driving mechanism (13) comprises a first supporting surface (24), a first inclined surface (26), a second supporting surface (27) and a second inclined surface (29) which are sequentially located on the movable shaft (12). The second supporting surface (27) is higher than the first supporting surface (24). The central angle formed by the first supporting surface (24), the first inclined surface (26), the second supporting surface (27) and the second inclined surface (29) is equal to the rotation angle of the mounting frame (1).

2. A yarn untwisting device for a knitting machine according to claim 1, characterized in that: The piston (7) comprises a movable shaft (12) and an inlay block (11) which are fixedly connected by bolts, the upper pressure ball head (8) and the inlay block (11) are both made of ceramics, the air passage (10) simultaneously passes through the movable shaft (12) and the inlay block (11), and a second sealing ring (28) is provided on the side surfaces of the movable shaft (12) and the inlay block (11).

3. A yarn untwisting device for a knitting machine according to claim 2, characterized in that: The driven shaft (33) is provided with a force unloading mechanism (3), the force unloading mechanism (3) comprising a limiting bolt (31), a second spring (30) and a stopper (32), the limiting bolt (31) passing through the stopper (32) and being threadedly connected to the driven shaft (33), the second spring (30) being located outside the limiting bolt (31) and being capable of exerting a force on the stopper (32) to press against the driven shaft (33).

4. A yarn untwisting device for a knitting machine according to claim 3, characterized in that: The side cover (2) is provided with a groove (36) for limiting the rotation angle of the mounting frame (1), and the mounting frame (1) is provided with a third spring for applying a downward force to the fixed shaft (34).

5. A yarn untwisting device for a knitting machine according to claim 4, characterized in that: A fixing block (18) is arranged inside the side cover (2), and a limiting column (23) for positioning the toothed block (22) is arranged at one end of the mounting frame (1), and the fixing block (18) and the limiting column (23) are connected by fastening bolts.

6. A method for untwisting a composite yarn based on the yarn untwisting device for a knitting machine according to any one of claims 2 to 5, characterized in that: The following steps are involved: S1: Selecting a first yarn (35) and a second yarn that meet the requirements, and feeding them independently through yarn feeders; S2: The first yarn (35) is first subjected to a heating and expansion treatment, and then conveyed to the untwisting device, the upper pressing ball head (8) and the inlay block (11) are kept clamping two places of the first yarn (35), and the yarn between the two places is wrapped on the surface of the upper pressing ball head (8), and the gas supply device blows gas with a certain pressure from the air passage (10) in an intermittent manner, and the gas nozzle (4) also intermittently introduces gas, so that the movable shaft (12) produces an intermittent telescopic movement, so that the upper pressing ball head (8) and the inlay block (11) intermittently clamp the first yarn (35), and form loose sections (38) and tight sections (37) arranged at intervals on the first yarn (35); S3: The first yarn (35) and the second yarn processed by the untwisting device are simultaneously conveyed by the yarn feeder to the doubling machine for doubling, and a local position of the second yarn is kept wrapped by the loose section (38) of the first yarn (35).

7. A method for untwisting a composite yarn according to claim 6, characterized in that: The second yarn is also processed by the untwisting device before being doubly-wound with the first yarn (35).

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