CZ21228U1 - Needle-thread tensioning device for sewing machine - Google Patents

Description

Technical field

The invention relates to a sewing machine upper thread tensioning device, in particular to a sewing machine upper thread tensioning device having air-operated thread tensioning discs for maintaining or adjusting the thread tension.

BACKGROUND OF THE INVENTION

Joint feed sewing machines are generally used to sew leather materials. In some cases, for example when several materials of different thickness are sewn, the leather materials are sewn in different positions, or the mixed leather materials with the added layers have different thicknesses, the needles and threads should be varied to achieve different stresses.

The prior art sewing machine as described in Chinese Patent Publication No. 1600932, named a sewing machine tensioning machine, comprises a support plate with a first tensioner and a second tensioner. The thread tension applied by the first tensioner and the second tensioner can be eliminated. The release bolt is coupled to the support plate and is movable such that it can abut the release pin of the first tensioner and the second tensioner. The electromagnet drives the releasing barrier to move along a given trajectory. The given trajectory path is divided into different steps including deflection from the first tensioner and then deflection from the second tensioner.

The prior art sewing machine tensioner has several drawbacks, as shown below.

The prior art sewing machine tensioner has two electromagnets for driving two tensioner assemblies with different spring pressure, or has an electromagnet controlling the output force by means of a current value. The tensioners adequately release or maintain voltage. This requires an additional complex circuit system requiring a disproportionately large and costly arrangement.

2. In the prior art, the output force is controlled to release or maintain tensioner tensioners. As the tensioner springs change with pressure adjustment, the accuracy of the output force may be affected.

The essence of the technical solution

It is therefore an object of the present invention to provide a sewing machine top thread tensioning device having a small cylinder air cylinder of a yarn tensioning control disc, thereby saving space and increasing reliability of the operation.

The upper thread tensioning device for the sewing machine according to the present invention comprises a base plate, at least two thread tensioning discs, a rotating plate and an air cylinder. The base plate is formed by an upper surface and a lower surface against the upper surface. At least two separate through holes extend through the top surface and the bottom surface. At least two separate thread tensioning discs are received in the through holes. Each of the thread tension discs is formed by an adjusting column, a regulating unit, a pressure plate, a support plate and a resilient unit that surround the adjusting column, and a pin. The pressure plate is inserted between the base plate and the control unit. The support plate is positioned between the base plate and the pressure plate. The resilient unit is located between the control unit and the pressure plate to push against the pressure plate. The adjusting post has a first coupling portion at one end thereof and a second coupling portion at its other end. The second coupling portion extends from the top surface of the base plate for mounting in the through hole. The first connecting portion has an aperture formed in its axis and the second connecting portion forms a slot for connecting the aperture and the bottom surface. The control unit is threadedly connected to the first coupling part. The pin enters the slot and includes a first adjacent end extending above the bottom surface of the base plate and a second adjacent end adjacent the press plate in the aperture. The rotary plate is pivotally attached to the bottom surface of the base plate and forms an adjacent plate adjacent it

CZ 21228 U1 to the bottom surface. The at least one sliding notch is provided on an adjacent plate to receive a first adjacent end of one pin. The at least one sliding groove is provided on an adjacent plate for receiving a first adjacent end of the second stud. The air cylinder has two separate parts for driving the rotation of the rotary plate. Either only the notch rotates around the pin so that the adjacent plate abuts the pin to extrude it, or the notch and the sliding groove rotate separately about the pin so that the adjacent plate abuts the pins to squeeze them out. The return unit is located at the center of rotation of the rotary plate and has two ends respectively adjacent the base plate and the rotary plate.

BRIEF DESCRIPTION OF THE DRAWINGS

Giant. 1 is a perspective view of the upper thread tensioner of the sewing machine according to the present invention. Giant. 2 is a perspective view of the upper thread tensioner of the sewing machine from another side.

FIG. 3 is an exploded view of the upper thread tensioner of the sewing machine of FIG. 1.

Giant. 4 is a view of the folded upper threading device of the sewing machine.

Giant. 5 is a front view of the upper thread tensioner of the sewing machine.

Giant. 6 is a rear view of the upper thread tensioner of the sewing machine.

Giant. 7 is a cross-sectional view taken along line 7-7 of FIG. 6.

Giant. 8 is a rear view of the upper thread tensioner of the sewing machine showing schematically the first operation.

Giant. 9 is a cross-sectional view taken along line 9-9 of FIG. 8.

Giant. 10 is a rear view of the upper thread tensioner of the sewing machine showing schematically a second operation.

Giant. 11 is a cross-sectional view taken along line 11-11 of FIG. 10.

Examples

Referring to FIG. 1-3, the sewing machine upper thread tensioner comprises a base plate 2, four thread tensioning discs 3, a rotary plate 4, an air cylinder 5 and a return unit 6.

The base plate 2 has an upper surface 21 and a lower surface 22 opposite the upper surface 21. Four through holes 23 extend through the upper surface 21 and the lower surface 22. The first post 24 extends from the lower surface 22.

Four yarn tensioning discs 3 are housed in four through holes 23. Each of the yarn tensioning discs 3 includes an adjusting column 31, a control unit 34, a thrust plate 35, a support plate 36, a spring unit 37 and a pin 38.

The adjusting column 31 has a first connection portion 32 at one end thereof and a second connection portion 33 at the other end. A thread 321 is formed on the outer surface of the first connecting portion 32. The first connecting portion 32 has an aperture 322 therein. During assembly, the second connecting portion 33 extends from the first surface 21 of the base plate 2 to be secured in the through hole 23. 331 for connecting the aperture 322 and the second surface 22.

The control unit 34 is cap-shaped and fits onto the thread 321 of the first connecting portion 32.

The pressure plate 35 surrounds the adjusting column 31 and is interposed between the base plate 2 and the control unit 34.

A support plate 36 surrounds the adjusting column 31 and is located between the base plate 2 and the pressure plate 35.

The spring unit 37 is formed by a tension spring. The spring unit 37 surrounds the adjusting column 31 and is located between the control unit 34 and the thrust plate 35 to push against the thrust plate 35. The end 371 of the spring unit 37 extends into the opening 322.

The pin 38 enters the slot 331 and comprises a first adjacent end 381 extending beyond the bottom surface 22 of the base plate 2 and a second adjacent end 382 adjacent the pressure plate 35 in the bore 322.

The rotary plate 4 has a rotatable portion 41 pivotally connected to the bottom surface 22 of the base plate 2. The rotary plate 4 forms an adjacent plate 42 adjacent the lower surface 22. A pair of notches 43 and a pair of sliding grooves 44 are provided on the adjacent plate 42 for corresponding pins 38. the grooves are arcuate and share a common axis with the ring determined by the rotation of the rotary part 41. The first adjacent ends 381 of the two pins enter the notches 43 and the first adjacent ends 381 of the second two pins enter the slots. The rotary plate 4 has a rotary arm 45 in an arrangement located on the upward path of the air cylinder 5. The second column 46 extends from the rotary plate 4 in the same direction as the first column 24 extends.

The air cylinder 5 comprises a main body 51. In the main body 51 there is an adjacent lever 52, which is movable to slide out of the main body 51 to the corresponding rotary arm 45 of the rotary plate 4, thereby acting by rotation of the rotary plate 4. drive the rotation of the rotary plate 4 two separate parts. The air cylinder 5 has a first air intake 53 providing compressive force to the adjacent lever 52, wherein the adjacent lever 52 primarily provides driving force to the rotary plate 4. First, the notches 43 rotate around the pins 38 and the adjacent plate 42 pushes the pins 38 in the notches 43. to push them out. The air cylinder 5 has a second air intake 54 providing compressive force to the adjacent lever 52, wherein the adjacent lever 52 in the second row provides driving force to the rotary plate 4. In the second row the sliding grooves 44 rotate around the pins 38 and the adjacent plate 42 pushes the pins 38 in grooves 44 to push them out.

The return unit 6 is located in the center of rotation of the rotary plate 4 and has two ends individually adjacent to the base plate 2 and the rotary plate 4. The return unit 6 is a torsion spring which is disposed around the rotatable portion 41 of the rotary plate 4. a pair of stop arms 61 extending from each other in the opposite direction. The stop arms 61 are located on the rotary path of the rotary plate 4 and are biased against the first column 24 of the base plate 2 and the second column 46 of the rotary plate 4.

Referring now to FIG. 3-6, 8, 10 and 11 the second air inlet 54 sucks air to provide compressive force to the adjacent lever 52. The adjacent lever 52 in the second row provides driving force to the rotary arm 45 of the rotary plate 4 (while the first air inlet 53 sucks air independently of the outlet position). adjacent levers 52). The return unit 6 is twisted and compressed. Both the notches 43 and the sliding grooves 44 of the rotary plate 4 rotate around the pins 38. The adjacent plate 42 pushes the pins 38 out of their position. The other adjacent ends 382 abut against the thrust plates 35. Thus, the thrust plates 35 release the support plates 36, thereby releasing the needles and threads 7 around the thread tensioning discs 3.

Referring to FIG. 6 and 7, when the first air inlet 53 and the second air inlet 54 suck in the air, the return unit 6 provides a return force for the rotary plate 4. The notches 43 and the sliding grooves 44 of the rotary plate 4 rotate to match the pins 38 and receive the first adjacent The resilient units 37 restore pressure to the thrust plates 35 and the yarn tension support plates 36. The yarns 7 are tensioned by the yarn tensioning discs 3 and the remaining stresses. The yarn tensioning disc control units 34 rotate around the threads 321 and move relative to the first connecting portions 32. In this way, the pressure of the spring units 37 is adjusted to determine the yarn tension 7.

Referring now to FIG. 3-6, 8 and 10 when thin materials are sewn, the first air inlet 53 sucks air while the second air inlet 54 is released. Adjacent lever 52 provides driving force to the rotary arm 45 at its center. The notches 43 of the rotary plate 4 rotate around the first adjacent ends 381 of the pins 38. The adjacent plate 42 pushes the pins 38 out of their position. The second adjacent ends 382 abut against the thrust plates 35, releasing the two thread tension discs 3. The resilient units 37 restore pressure to the thrust plates 35. The first adjacent ends 381 simply move in the sliding grooves 44 without sliding therefrom. Thus, the two yarn tensioning discs 3 provide tension for the yarn 7 in such a way that each yarn 7 is subjected to the pressure of only one yarn tensioning disc 3. Thus, each yarn 7 is subjected to relatively less pressure when sewing, as shown in FIG. 9 (also referring to FIGS. 7 and 11).

As mentioned above, this technical solution has the following advantages:

1. The first air inlet 53 and the second air inlet 54 of the air cylinder 5 each suck in air to provide a compressive force to the adjacent lever 52, thereby releasing or maintaining the tension of the yarn tensioning disks 3. The overall design is mechanical without additional complex circuitry, thereby simplifying construction and assembly and space saving.

2. The air cylinder 5 provides a pressure force sufficient to achieve a predetermined maximum pressure of the spring unit 37 of the yarn tensioning discs 3 and is not controlled by the control unit 34 of the spring unit 37.

PROTECTION REQUIREMENTS

Claims (6)

1. A top thread tensioner for a sewing machine comprising: 10, a base plate (2) having an upper surface (21) and a lower surface (22) in which at least two separate through holes (23) are formed which open on the upper surface (21) and the lower surface (22); at least two separate yarn tensioning discs (3) housed in the through holes (23), each of the yarn tensioning discs (3) comprising: an adjusting post (31) terminated by a first connecting portion (32) at one end and a second connecting portion 15 parts (33) at the other end, which is fastened in the through hole (23) by its second connecting part (33) from the side of the upper surface (21) of the base plate (2), the first connecting part (32) having its axis formed an opening (322), and a second connecting portion (33) formed by a slot adjoining the opening (322); and a control unit (34) threadedly connected to the first coupling portion (32); 20 and a thrust plate (35) with an orifice sliding on the adjusting column (31) that is disposed between the base plate (2) and the control unit (34); and a support plate (36) with an opening sliding on the adjusting column (31) and disposed between the base plate (2) and the pressure plate (35); and a flexible unit (37) surrounding the adjusting column (31) and disposed between the control unit (34) and the thrust plate (35); and a pin (38) extending into the slot, the first adjacent end (381) of which extends beyond the bottom surface (22) of the base plate (2), while its second adjacent end (382) housed in the bore (322) abuts the pressure plate; and a rotary plate (4) connected to the bottom surface (22) of the base plate (2) and forming an adjacent plate 30 to the bottom surface (22), the rotary plate (4) including at least one notch (43) receiving the first adjacent plate an end (381) of the first stud (38), at least one sliding groove (44) provided on the rotary plate (4) in which the first adjacent end (381) of the second stud (38) is received; and a return unit (6) located at the center of rotation of the rotary plate (4) and having two ends respectively adjacent the base plate (2) and the rotary plate (4), 35 characterized in that an air cylinder (5) formed by a main body (51) is provided on the base plate (2) and is provided with an adjacent lever (52) extending from the main body (51) towards the rotary arm (45) of the rotary plate (4), wherein the air cylinder (5) is provided with a first air intake (53) which is coupled to a lever (52), which engages a rotary arm (45) of a rotary plate (4) provided with notches (43) rotatably supported the air cylinder (5) is further provided with a second air intake (54) which is also connected to a lever (52), which engages a rotary arm (45) of a rotary plate (4) provided with sliding grooves (44) which are rotatably mounted on the pins (38). Thread-tensioning device for sewing machine according to claim 1, characterized in that four through holes (23) are provided in the base plate (2) in which the adjusters are fixed. The columns (31) are arranged on which the rolls (3) of the threads are arranged, and two notches (43) and two sliding grooves (44) in which the pins (38) are rotatably mounted are also provided on the rotary plate (4). A sewing machine upper thread tensioning device according to claim 1, characterized in that a thread (321) is formed on the outer surface of the first connecting portion (32). A sewing machine upper thread tensioning device according to claim 1, characterized in that the rotary plate (4) has a rotatable part (41) pivotally connected to the bottom surface (22) of the base plate (2). A sewing machine upper thread tensioning device according to claim 1, characterized in that the return unit ( 6) is a torsion spring that is located around the rotatable part (41) of the rotary plate (4). Sewing machine upper thread tensioning device according to claim 1, characterized in that the sliding grooves (44) are arcuate and share a common axis with a circle determined by the rotation of the rotary plate (4). Sewing machine upper thread tensioning device according to claim 1, characterized in that the rotary plate (4) has a rotary arm (45) located on the upward path of the air cylinder (5).