JP7304201B2 - thread tension device for sewing machine - Google Patents

Description

The present invention relates to a thread tensioning device for a sewing machine and to machines equipped with this type of thread tensioning device.

A thread tensioning device for a sewing machine is known from US Pat. US Pat. No. 6,330,001 discloses a device for thread tensioning of a thread processing machine. U.S. Pat. No. 5,900,000 discloses an upper thread tensioning device having two thread tensioning discs. U.S. Pat. No. 5,400,000 discloses a thread tensioning device for a sewing machine. US Pat. No. 4,900,005 discloses a tensioning device for needle threads in a two-needle sewing machine. U.S. Pat. No. 6,300,009 discloses a spool device for sewing machines.

DE19633223C2 DE2157016A DE202012100110U1 DE10344982A1 DE962568C DE202009004845U1

SUMMARY OF THE INVENTION It is an object of the present invention to improve a thread tensioning device of the type mentioned at the outset so as to improve its influence on the thread to be stretched.

According to the invention, this object is achieved by a thread tensioning device with the features defined in claim 1 .

According to the invention, the division of the tensioning effect of the tensioning device into two tensioning contributions, between which the deflection of the threadpath (yarn elongation) is performed by the threadpath deflection element, is performed by the tensioning device. It has been found to help distribute the force exerted by the device on the sutures in an advantageous manner. In particular, twisting of the sewing thread is avoided, thereby preventing undesirable twisting forces on the sewing thread, particularly stacking along the thread path of the tensioning device (so-called undesirable snarling). By dividing the effect of the tensioning device into two tensioning contributions, each produced by forming multiple loops around the same tensioning shaft, a compact arrangement of the tensioning device is achieved. can get. In particular, it is also conceivable to generate a number of different thread tension contributions which can be operated differently, with the result that the overall thread tension range is advantageously increased. The sewing thread may be the top thread of a sewing machine. The tension device can also generate more than two tension contributions. A corresponding additional thread path may then be provided by the thread path deflection element or by another thread path deflection element providing another thread path on the tensioning shaft, the additional thread tension contribution is generated. A thread tensioning device may have exactly one tensioning unit. Alternatively, the tensioning device may have at least two tensioning units. The tuning unit may be biased by a bias spring. The bias spring may be a compression spring. The compression spring may be configured as a helical spring or as a wave spring.

A thread path deflection element configured as a rotatable pin or roll as claimed in claim 2 is particularly neutral with respect to the force exerted on the sewing thread. A rotatable pin or rotatable roller can rotate with the suture extending thereon.

Considered alone, embodiments of the conditioning unit as claimed in claims 1 and 3 are known from the prior art, e.g. The pressure tone discs may be configured as Belleville washers. The tone unit may have two sets of pressure tone pans or more than three sets, such as 3, 4, 5 or 6 or more pressure tone pans. Instead of electric actuators, manually operable adjusting elements, such as adjusting screws, can also be used to adjust the tensioning force of the tone unit. The pressure tone dish is arranged so as not to rotate with respect to the tension adjustment shaft.

The tensioning unit according to claims 1, 4 is particularly suitable for generating a yarn tension force with an advantageously large tension range and is particularly suitable for reproducibly generating a given yarn tension force. found to be suitable. The disc portions of respective wheel tension discs configured to accommodate the thread to be tensioned may be fixedly connected to each other, for example welded to each other. The retaining effect of the wheel tuning disc is produced by a peripheral retaining portion which is configured in particular as a tongue-shaped retaining portion. These holding parts are mutually engageable so that a reproducible frictional connection is obtained between the holding parts and the thread to be stretched. A wheel tuning disc is rotatably fitted to the tension adjusting shaft. In this case, the wheel tension disc can rotate with the thread to be tensioned as the thread is guided around the tensioning shaft. Thread tension is produced by actuator pressure with a corresponding pressure dependent braking effect applied to the wheel tension disc by the brake body actuated by the actuator.

Actuators acting on a set of tone discs may act on the set of tune discs via wire springs or wave springs.

The stepper motor according to claim 5 allows particularly fine-tuning, reproducible thread tension settings. The stepper motor may act on at least one tuning unit via a gear unit. The gear unit serves to improve the sensitivity of the stepper motor's influence on the generated thread tension contribution or the speed of the adjustment process or opening of the respective tension unit. Linear motors can also be used instead of stepper motors. The actuator may have a gear unit. A multiple-start screw thread can be used for force transmission between the actuator and the tension disc. The stepper motor may be torque controlled.

By means of at least two tensioning units according to claim 6 different thread tension contributions can be set particularly independently.

Instead of designing the tuning unit as a set of tensioning discs, the tuning unit itself may be formed by at least one stepper motor as claimed in claim 7 . The tensioning shaft may form the motor shaft of the stepper motor or may be connected to said motor shaft via a gear unit.

The advantages of the sewing machine according to claim 8 correspond to those already explained above with regard to the thread tensioning device. In addition to the thread tensioning devices described above being used as the main tensioning device, a thread pretensioning device may be positioned in the thread path of the sewing thread upstream of the main tensioning device.

Exemplary embodiments of the invention are explained in more detail below with reference to the drawings.

Fig. 2 is a schematic front view showing some inner details of a double lockstitch sewing machine; The upper thread path is interrupted in the region of the thread tension component not shown in FIG. 1, in other words it is not shown. FIG. 4 is a front elevational view showing additional detail of the housing portion of the sewing machine, the components of the tensioning device being shown in Sections I/II; It corresponds to Sections I/II of FIG. Figure 3 is a cross-sectional view along line III-III in Figure 2; Figure 3 shows a side view of the housing part, viewed in viewing direction IV in Figure 2; Figure 3 shows a perspective front view of the housing portion as shown in Figure 2; Figure 3 shows a wheel tensioning disk with two disk portions forming the tensioning unit of the main tensioning device of the tensioning device in place of a set of pressure tensioning disks; FIG. 10 is a side view of an embodiment of a tone unit having two sets of pressure tone discs with thread path deflection elements; The figure shows the thread path in the area of the thread tensioning device.

A lockstitch sewing machine 1 has a machine frame 1a with a base plate 2, a stand 3 extending upwardly therefrom, and a bending arm 4. - 特許庁The bending arm terminates in head 5 . An arm shaft 6 is mounted within the arm 4 for rotation. At the head 5 the arm shaft 6 drives a crank drive 7 with a thread lever 8 . A crank drive 7 is drivingly connected to a needle bar 9 mounted in the head 5 in an axially displaceable manner. Said needle bar 9 has a needle 10 at its lower end. A crank drive 7 allows the needle 10 to move up and down along a vertical axis 11 .

In the following, a Cartesian xyz coordinate system is used to facilitate the illustration of positional relationships. A vertical axis 11 extends along the z-direction of this coordinate system. The x direction is perpendicular to and extends into the drawing plane of FIG. 1 and parallel to the sewing direction of the sewing machine 1 . The y-direction extends to the left in FIG.

The needle 10 guides the needle thread 13 to the eyelet. The needle thread 13 is supplied via a thread tensioning device by a needle thread supply configured as a reel 12 and a thread lever 8, also referred to as needle thread. The tensioning device will be described in more detail in connection with Figures 2 et seq. The needle thread 13 has a loose (free) upper thread start segment 13a.

The base plate 2 carries a support plate 14 on which the piece of fabric 15 rests, said support plate 14 being fixed by means of screws. The part of the support plate 14 configured as a stitch plate 16 has a recess through which the lower feed dog 17, also called drop feed, can pass. The feed dog 17 has a stitch hole 18 through which the needle 10 passes. The feed dog 17 is drivingly connected in a known manner with the sliding and lifting gear unit. The sliding and lifting gear unit is arranged under the base plate 2 .

Underneath the support plate 14 is a looper 19 having a looper body 20 with a looper tip 21 . A cup-shaped bobbin case is installed in the looper body 20 to accommodate the looper thread supply in the form of a thread winding 22 or thread spool. The spool 22 is a bobbin thread supply section. The looper thread is also called bobbin thread.

Looper 19 forms a stitch forming tool with needle 10 . A needle 10 is used to guide the upper thread. A looper 19 is used to interweave (entangle) the top thread and the bobbin thread.

Looper 19 is rotatable about a vertical looper axis 23 extending in the z-direction. The looper body 20 is fixedly connected to a shaft 25 extending coaxially with the looper axis 23 . A shaft 25 is mounted for rotation in a bearing block 26 screwed to the base plate 2 . Mounted on this bearing block 26 is a drive shaft 27 connected to a toothed gear unit located inside the bearing block 26 . The gear unit has a transmission ratio of 1:2, which means that the looper body 20 arranged on the shaft 25 rotates twice during one revolution of the drive shaft 27 . The drive shaft 27 is drivingly connected with the arm shaft 6 via a belt drive 28 .

The tensioning device 29, located in the housing portion 30 of the arm 4 in sections I/II of FIGS. Viewed along the thread path of the needle thread 13, the thread spool 12 is first positioned in front of the thread pretensioning device, which is not shown in more detail. The thread pretensioning device is then positioned before the main thread tensioning device 32 . Depending on the design of sewing machine 1, the thread pretensioning device may be omitted.

The main tensioning device 32 has a tensioning shaft 33 (see FIG. 3) around which the needle thread 13 to be tensioned is wound. Two tensioning units 34 , 35 each configured to generate a tensioning contribution interact with the tensioning shaft 33 . Each of the tensioning units 34 , 35 functions to generate a tension contribution or tension of the needle thread 13 in the path of the needle thread 13 following the tensioning shaft 33 . Depending on the design of the main tensioning device 32, it is also conceivable to have just one tensioning unit, eg the tensioning unit 34, used to generate the tensioning.

Each of the tone units 34, 35 is formed by a pair of pressure tone pans 36 and actuators. The pressure tension discs 36 of each set of tension discs are arranged such that the needle thread 13 to be tensioned passes between the tension discs 36 of this set. Each set of tone plates 36 interacts with an actuator 37 to set pressure between the tone plates 36 . This effect of the pair of pressure tone plates 36 and actuators 37 is known from the prior art and is described, for example, in US Pat.

Actuator 37 may be an electromagnet. Actuator 37 may also be a stepper motor.

The two tuning units 34 , 35 interact with the same actuator 37 . The two tone units 34, 35 are arranged on the tone shaft 33 immediately axially adjacent to each other. Between the two tensioning units 34, 35 is arranged a bearing disk 37a against which the tensioning discs 36 of the two tensioning units 34, 35 which are arranged axially immediately adjacent to this bearing disk 37a. touch. Like the tone disk 36, the bearing disk 37a is fitted onto the tone shaft 33 and functions to radially support the tone disk 36 facing the bearing disk 37a. For this purpose, the bearing disc 37a has a circumferential bearing groove on its side which engages the edge portion of the respective tone plate 36 facing it.

In addition to the two tensioning units 34 , 35 the main tensioning device has a thread path deflection element 38 for deflecting the thread path of the needle thread 13 . This thread path of the needle thread 13 in the main tensioning device 32 is such that the needle thread 13 is first wound around the tensioning shaft 33 in the first region of the two tensioning units 34 , 35 to form the first tensioning of the tensioning shaft 33 . generates a contribution and then extends over the thread path deflection element 38 before being wound again around the tone shaft 33 in a second region of the two tensioning units 34, 35 to generate a second tension contribution. , is a thing. This thread path in the main tension device 32 may produce more than two tension contributions. In this case, an additional thread path around the tension shaft 33 again over the same thread path deflection element 38 or over another thread path deflection element (not shown) to generate the next thread tension contribution. There may be For this purpose, the tuning shaft 33 may carry further tuning units configured like the tuning units 34, 35, not shown in the drawings.

The yarn path deflection element 38 is constructed as a deflection pin. A deflection pin of this type may be rigidly mounted in the housing portion 30 or alternatively configured to be rotatable about its pin axis. In this case the pin is mounted in the housing part 30 like a roll via a radial bearing.

Alternatively, it is conceivable to design the tuning units 34, 35 as respective pairs of wheel tuning pan pan portions. A set of pan portions of this type of wheel tuner pan 39, for example forming one of the tuner units 34 or 35, is shown in FIG.

The two disk portions 39a of the wheel tuning disk 39 are rigidly connected together, for example by welding. The outer periphery of the set of disc portions 39a of the wheel tuning disc 39 has a generally U-shaped or generally V-shaped groove profile in which the needle thread 13 is routed over the angular range of the outer periphery, e.g. It is guided by wrapping it around 33.

The outer profile of the set of disk portions 39a of the wheel tuning disk 39 is formed by two web rings 40 each having a number of webs 41 bent axially outwardly in the ±x-directions. The arrangement of the webs 41 of the two web rings 40 in the circumferential direction is such that the webs 41 are alternately associated with one of the two web rings 40 and then with the other of the two web rings 40 . be. The profile base of the groove profile is formed by a plurality of retaining portions 42 of a plurality of webs 41 overlapping each other in the x-direction. This ensures that the needle thread 13, when wound around the set of disc portions 39a of the tuner disc 39, extends at a precisely defined radius with respect to the axial centerline of the tuner shaft 33. .

The retaining portion 42 may be configured as a tongue portion.

At least one of the tensioning units of the main tensioning device 32 , regardless of whether the tensioning units 34 , 35 are configured as a set of pressure tensioning discs 36 or a set of disc portions 39 a of the wheel tensioning discs 39 . It may be formed by at least one stepper motor driving rotation. The tuning shaft 33 may then be configured directly as the motor shaft of a stepper motor of this type, or the tuning shaft may be connected via a gear unit to the motor shaft of the stepper motor. When the tuning unit or units are configured as stepper motors, the needle thread 13 may be wholly wound around the tuning shaft 33 more than once, in particular.

As can be seen from FIGS. 2-5, the housing portion 30 includes a plurality of threads which can be formed by correspondingly guiding the needle thread 13 through two main tensioning devices, such as the main tensioning device 32 described above. may be equipped with components of In other words, as shown in these figures, housing portion 30 carries two main tensioning devices with associated tensioning shafts, associated actuators, associated tensioning units and associated yarn path deflection elements. You may

The actuator 37 acts via the compression spring 34 on the tension discs 36 or 39 of the tension units 34, 35 respectively. The compression spring 34 may be a helical spring, in particular a helical wire spring. When using actuators 37 configured as torque controlled servo motors or stepper motors, this type of tensioning spring may be omitted.

In embodiments of the tensioning units 34 , 35 with pressure tensioning discs 36 , the thread tension is generated by pressure exerted by an actuator 37 between the respective tensioning discs 36 on the thread disposed therebetween. A tuning plate 36 can be arranged on the tuning shaft 33 so as not to rotate. In embodiments having a plate portion 39a of each wheel tune plate 39, the tune is produced by the braking effect. The braking effect of the actuator 37 is between the respective wheel tuning disc 39, which rotates in its thread path with the thread wound thereon, and the brake body, which may be arranged non-rotatably with respect to the tuning shaft 33. generated by pressure. The brake body is for example the bearing disk 37a.

In the thread path downstream of the main tensioning device 32 the needle thread 13 passes through a thread clamping device 44 (see also FIG. 1) and then through the thread lever 8 to the eyelet of the needle 10 .

FIG. 7 shows the thread path of the thread tensioning device 32. As shown in FIG. This figure shows one of the two tensioning devices 32 of the embodiment shown in FIGS. 1-5. Therefore, the thread paths in other thread tension devices 32 also correspond to this.

Needle thread 13 first extends from a thread pretensioning device, not shown in FIG. 7, over a first pair 45 of pressure tuning discs 36 (first tuning unit). In doing so, the needle thread is wound around the tension shaft 33 by more than 180°, but may be wound around the tension shaft 33 more than twice as a whole. In the illustrated embodiment, the needle thread is wound around the tensioning shaft 33 in the area of the first pair 45 of pressure tensioning discs 36 over an angular range of about 270°. As the needle threads are wound around the first pair 45 , a first tension contribution is generated for the sewing threads 13 .

The needle thread 13 is wound around the thread path deflection element 38 with a contact angle of about 180° and then extends to the second pair 46 of the pressure tuning discs 36 (second tuning unit) of the thread tensioning device 32 where the first Wrapped around tune shaft 33 in the same manner as in pair 45 . As the needle threads are wound around the second pair 46 , a second tension contribution is generated for the sewing threads 13 .

The needle thread 13 then extends to a thread clamping spring not shown in FIG.

A first pair 45 of pressure tune plates 36 are located in the housing, while a second pair 46 are located toward the free end of tune shaft 33 .

In the embodiment shown in Figure 7, the compression spring 43 is configured as a wave spring. Wave spring blocks can also be used here.

The thread 13 may be wound around the tone shaft 33 in the region of the respective tone units 45, 46 in the same direction of rotation or in opposite directions of rotation. Depending on the yarn type and operating conditions, one of the two orientations "same rotation direction" and "counter rotation direction" is more desirable to avoid entanglement.

13 sewing thread 32 thread tensioning device 33 tensioning shafts 34, 35 tensioning unit 38 thread path deflection element

Claims (8)

A thread tensioning device (32) for a sewing machine, comprising:
- at least one tensioning shaft (33) configured such that the thread (13) to be tensioned is wound around the tensioning shaft (33);
- at least two tensioning units (34, 35) interacting with said tensioning shaft (33) to generate tension in the path of said thread (13) downstream of said tensioning shaft (33);
- a thread path deflection element (38) for deflecting the thread path of said thread (13);
- the thread path of said thread tensioning device (32) is as follows:
Said sewing thread (13) is
--First, wound around said tensioning shaft (33) to produce a first tensioning contribution,
--then extending over said yarn path deflection element (38);
--then again wound around said tension shaft (33) to produce a second tension contribution ;
- each said conditioning unit (34, 35),
-- said pressure-conditioning discs (36) formed by at least one set of pressure-conditioning discs (36) and at least one actuator (37), such that said thread (13) to be tensioned passes between said pressure-conditioning discs (36); (36) are arranged in pairs, said pressure-conditioning plates (36) interacting with said actuators (37) to set the pressure between said pressure-conditioning plates (36), or
-- formed by a wheel tensioning disk (39), a brake body (37a) and at least one actuator (37), which allow said thread (13) to be tensioned to pass between the disk portions of said wheel tensioning disk (39); arranged to pass through, said wheel tuning disc (39) interacting with said actuator (37) to set the pressure applied to said wheel tuning disc (39) by said brake body;
- a tensioning device, wherein said at least two tensioning units (34,35) are arranged on said tensioning shaft (33), said tensioning units (34,35) being adapted to generate respective tensioning contributions; . CHARACTERIZED IN THAT said thread path deflection element (38) is configured as a pin rotatable about a pin axis, said pin being configured such that said thread (13) is wound around said pin. The thread tension device according to claim 1. 3. A thread tensioning device according to claim 1 or 2, wherein each said tensioning unit has at least two sets of pressure tensioning discs. 3. A thread tensioning device according to claim 1, wherein each said tensioning disc is constructed as a tongue-shaped retaining portion. 3. Thread tensioning device according to claim 1 or 2 , characterized in that the actuator (37) is constructed as a stepper motor. 3. A thread tensioning device according to claim 1 or 2, wherein the tensioning unit is configured such that different thread tension contributions are independently set. 7. Thread tensioning device according to claim 1 or 2 and 6, characterized in that said tensioning unit is formed by at least one stepper motor and said tensioning shaft (33) is driven by said stepper motor. A sewing machine comprising the thread tension device (32) according to claim 1 or 2 .

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