TW201947079A - Thread tensioning device for a machine - Google Patents

Abstract

A thread tensioning device (32) for a sewing machine has a tensioning shaft (33) configured such as to allow a sewing thread (13) to be tensioned to be wound around said tensioning shaft (33). At least one tensioning unit (34, 35) interacts with the tensioning shaft (33) to generate a thread tension in the path of the sewing thread (13) downstream of the tensioning shaft (33). A thread path deflecting element (38) is used to deflect a thread path of the sewing thread (13). A thread path of the thread tensioning device (32) is such that the sewing thread (13) is first wound around the tensioning shaft (33) to generate a first thread tension contribution, then runs over the thread path deflecting element (38), and is then wound around the tensioning shaft (33) again to generate a second thread tension contribution. As a result, a thread tensioning device is obtained, which has an improved influence on the thread to be tensioned.

Description

Thread tensioning device for sewing machine and sewing machine with thread tensioning device

The invention relates to a thread tensioning device for a sewing machine and a machine having such a thread tensioning device.

A thread tensioning device for a sewing machine is known from DE 196 33 223 C2. DE 2 157 016 A discloses a device for thread tensioning on a yarn processing machine. DE 20 2012 100 110 U1 discloses an upper thread tensioning device comprising two thread tensioning disks. DE 103 44 982 A1 discloses a thread tensioning device for a sewing machine. German patent specification No. 962 568 discloses a tensioning device for needle threads in a two-needle sewing machine. DE 20 2009 004 845 U1 discloses a spool device for a sewing machine.

The object of the invention is to improve a thread tensioning device of the type described above in such a way that its influence on the tensioned thread is improved.

According to the present invention, the object is achieved by a thread tensioning device for a sewing machine, the thread tensioning device having at least one tensioning shaft configured to allow a sewing thread to be tensioned to surround a sewing thread. The tensioning shaft is wound; at least one tensioning unit interacting with the tensioning shaft to generate a thread tension in a path of the sewing thread downstream of the tensioning shaft; a thread path deflecting element to deflect a thread path of the sewing thread; wherein, The thread path of the thread tensioning device is such that the sewing thread is first wound around the tensioning axis to generate a first thread tension effect, then is wound (extended) around the line path deflection element, and then is wound again around the tensioning axis to generate a second Line tension effect.

According to the present invention, it is found that the line tension effect of the thread tensioning device is divided into two line tension effects, and between the two line tension effects, the line path deflection element performs the deflection of the line path to assist the distribution of the line by the advantageous way The force exerted by the tensioning device on the sewing thread. In particular, twisting of the sewing thread can be avoided, thereby preventing any undesired torsional force from being applied to the sewing thread, and particularly preventing accumulation of thread paths along the thread tensioning device (so-called unwanted tangles). The effect of the wire tensioning device is divided into two wire tension effects, each of which is generated by forming a loop around the same tensioning shaft, resulting in a compact arrangement of the wire tensioning device. It is also conceivable to generate many different thread tension effects, which are particularly differently executable, with the result that the total thread tension range can be increased in an advantageous manner. The sewing thread may be the upper thread of a sewing machine. The thread tensioner also allows more than two thread tension effects to be generated. A corresponding additional line path may then be provided by the line path deflection element or another line path deflection element that provides another line path above the tensioning shaft to generate the additional line tension effect. The thread tensioning device may have exactly one tensioning unit. Alternatively, the wire tensioning device may also have at least two tensioning units. The tensioning unit can be biased by a bias spring. The bias spring may be a compression spring. The compression spring may be configured as a coil spring or a ripple spring.

The thread path deflecting element is configured as a rotatable pin or a roll rotatable about a pin axis, the pin being configured such that a sewing thread is allowed to wind around the pin, which is particularly neutral in terms of the force applied to the sewing thread. The rotatable pin or rotatable roller can then be rotated with the sewing thread extending thereon.

Considered separately, in an embodiment of the tensioning unit formed by at least one pair of pressure tensioning discs and at least one actuator, the pressure tensioning discs are arranged in pairs so that the sewing thread to be tensioned passes between the pressure tensioning discs The pressure tensioning disc interacts with the actuator to set the pressure between the pressure tensioning discs, which is known from the prior art, for example from DE 196 33 223 C2. The compression tensioner can be configured as a Belleville washer. The tensioning unit may have two pairs of pressure tension discs or even more than two pairs of pressure tension discs, such as three, four, five or even more pairs of pressure tension discs. It is also possible to use a manually operable adjustment element, such as an adjustment screw instead of an electric actuator, to adjust the tensioning force of the tensioning unit. The pressure tensioning disc may be arranged so as to be non-rotatable relative to the tensioning shaft.

A tensioning unit formed of a wheeled tensioning disc, a brake body and at least one actuator, which is arranged such that a sewing thread to be tensioned passes between the disc portions of the wheeled tensioning disc, the wheeled tensioning disc Interaction with the actuator to set the pressure exerted by the brake body on the wheeled tensioning disc has proven to be particularly suitable for generating a line tension with a favorable large range of tension, and in particular reproducibly generating a predetermined line tension. The disk sections of the respective wheeled tensioning disks configured to receive the wires to be tensioned may be rigidly connected to each other, for example welded to each other. The retaining effect of the wheel-type tensioning disc can be generated by the circumferential retaining section, which can be configured in particular as a tongue-shaped retaining section. These holding sections can be engaged with each other in such a way that a reproducible frictional connection is obtained between the holding section and the line to be tensioned. The wheel-type tensioning disc can be rotatably mounted on the tensioning shaft. In this case, when the tensioning disc is guided around the tensioning axis, the wheeled tensioning disc can be co-rotated with the line to be tensioned. The linear tension can then be generated from the actuator pressure through the corresponding pressure-dependent braking effect exerted on the wheel tensioner by the brake body operated by the actuator.

An actuator acting on a pair of tension discs may act on the pair of tension discs via a wire spring and / or a ripple spring.

An actuator configured as a stepper motor allows for particularly fine-tuning and reproducible wire tension settings. The stepper motor can act on at least one tensioning unit by means of a gear unit, which helps to increase the sensitivity of the stepper motor to the effect of the generated wire tension or to adjust the speed of the program or the corresponding tensioning unit Opening. Instead of a stepper motor, a linear motor can also be used. The actuator may have a gear unit. Multi-head sewing threads can be used to transfer force between the actuator and the tensioning disc. Stepper motors can be torque controlled.

At least two tensioning units, which are arranged on the tensioning shaft and are configured such that corresponding thread tension effects are generated, allowing different thread tension effects to be set in a particularly independent manner.

As an alternative to designing the tensioning unit as a pair of tensioning disks, the tensioning unit itself may be formed by at least one stepper motor, and the tensioning shaft is driven by the stepper motor. The tensioning shaft may form a motor shaft of a stepper motor, or may be connected to the motor shaft via a gear unit.

The advantages of a sewing machine with a thread tensioning device according to the invention correspond to those already explained above with reference to the thread tensioning device. In addition to the thread tensioning device described above, which then serves as the main thread tensioning device, the thread pre-tensioning device may be arranged in the thread path of the sewing thread upstream of the main thread tensioning device.

The double-lock stitch sewing machine 1 has a frame 1a, which includes a base plate 2 with a bracket 3 and an angled arm 4, the bracket extending upward from the base plate. The arm terminates in the head 5. The arm shaft 6 is mounted for rotation in the arm 4. In the head 5, an arm shaft 6 drives a crank drive 7 through a wire rod 8. The crank driver 7 is drivingly connected to a needle bar 9 which is mounted in the head 5 in an axially displaceable manner. The needle bar 9 has a needle 10 at its lower end. By means of the crank drive 7, the needle 10 can be moved up and down along the vertical axis 11.

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

The needle 10 guides the needle thread 13 into the eyelet, said needle thread 13 being supplied via a thread tensioning device and a thread rod 8 by a surface thread supply configured as a reel 12 and also referred to as a surface thread, said thread tensioning device will be referred to the drawing 2 and below are explained in more detail. The needlework 13 has a free upper thread start section 13a.

The bottom plate 2 carries a support plate 14 on which the fabric sheet 15 is placed, and the support plate 14 is fastened by means of screws. The support plate 14 is configured such that a part of the suturing plate 16 is provided with a recess that allows a lower feeding dog tooth 17 (also referred to as a drop feeding) to pass through. The dog feeder 17 has a suture hole 18 that allows the needle 10 to pass through. The dog feeder 17 is drivingly connected in a known manner to a sliding and lifting gear unit which is arranged below the base plate 2.

A ring maker 19 is provided below the support plate 14 and has a ring maker body 21 with a ring maker tip 21. In the looper body 21, a cup-shaped bobbin case is installed, and the looper wire supply is received by the reel 22 or the spool. The reel 22 is a lower thread supply. The looper line is also called the bottom line.

The looper 19 forms a stitch forming tool with the needle 10. The needle 10 is used to guide the upper thread. The looper 19 is used to interweave the upper and lower threads.

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

The thread tensioning device 29 in the I / II section of FIGS. 1 and 2 arranged on the housing part 30 of the arm 4 has a plurality of thread tensioning members which are in the line path of the upper thread 13 One by one. Looking along the line path of the upper thread 13, behind the reel 12 is firstly a wire pretensioning device (not shown in detail), which is followed by a main wire tensioning device 32. Depending on the design of the sewing machine 1, the thread pre-tensioning device may be omitted.

The main wire tensioning device 32 has a tensioning shaft 33 (see FIG. 3), and the face thread 13 to be tensioned is wound around the tensioning shaft 33. The two tensioning units 34, 35, each configured to generate a linear tension effect, interact with the tensioning shaft 33. Each of the tensioning units 34, 35 is used to generate a line tension or a line tension effect of the surface thread 13 in the path of the surface thread 13 behind the tensioning shaft 33. Depending on the design of the main thread tensioning device 32, it is also conceivable to precisely provide a tensioning unit, such as the tensioning unit 34, which is used to generate thread tension.

Each of the tensioning units 34, 35 is formed by a pair of pressure tensioning disks 36 and an actuator 37. The pressure tensioning disks 36 of the corresponding pair of tensioning disks are arranged such that the face threads 13 to be tensioned pass between the pair of tensioning disks 36. A corresponding pair of tensioning disks 36 interacts with the actuator 37 to set a pressure between the tensioning disks 36. This effect of a pair of pressure tensioning discs 36 and actuators 37 is known from the prior art and is described, for example, in DE 196 33 223 C2, with particular reference to FIG. 4.

The actuator 37 may be an electromagnet. The actuator 37 may be a stepping motor.

The two tensioning units 34, 35 interact with the same actuator 37. The two tensioning units 34, 35 are arranged directly axially adjacent to each other on the tensioning shaft 33. Between the two tensioning units 34, 35, a bearing disk 37a is arranged for those tensioning disks 36 of the two tensioning units 34, 35 to withstand the axially-adjacent arrangement directly adjacent to the bearing disk 37a. Tension plate 36. As with the tensioning disk 36, a bearing disk 37a is fitted on the tensioning shaft 33 and serves to radially support the tensioning disk 36 facing the bearing disk 37a. To this end, the bearing disks 37a have circumferential bearing grooves on either side, said bearing grooves engaging the edge portions of the corresponding tensioning disks 36 facing said bearing grooves.

In addition to the two tensioning units 34, 35, the main thread tensioning device also has a line path deflection element 38 to deflect the line path of the face line 13. This line path of the upper thread 13 in the main thread tensioning device 32 causes the upper thread 13 to first be wound around the tensioning shaft 33 in the region of the first of the two tensioning units 34, 35 to generate the tensioning shaft 33. The first thread tension acts and then, before winding again around the tensioning axis 33 in the area of the second of the two tensioning units 34, 35, it is passed over the line path deflection element 38 to generate a second thread tension effect. This thread path in the main thread tensioning device 32 may also cause more than two thread tension effects to be generated. In this case, an additional line path may exist on the same line path deflection element 38 or on another line path deflection element, not shown, and then around the tensioning shaft 33 again to generate the next line tension effect . For this purpose, the tensioning shaft 33 can carry further tensioning units arranged in the manner of tensioning units 34, 35, which are not shown in the figure.

The linear path deflection element 38 is configured as a deflection pin. This type of deflection pin may be securely mounted to the housing portion 30 or, alternatively, it may be configured so as to be rotatable about its pin axis. In this case, the pin is mounted in the housing portion 30 in a roller manner via a radial bearing.

Alternatively, it is conceivable to design the tensioning units 34, 35 as a corresponding pair of disk sections of a wheeled tensioning disk. For example, a pair of disk portions of this type of wheeled tensioning disk 39 is shown in FIG. 6, which disk portions may form one of the tensioning units 34 or 35.

The two disk portions 39a of the wheel-type tensioning disk 39 are rigidly connected to each other, for example, by welding. The outer circumference of the pair of disk portions 39a of the wheel-type tensioning disk 39 has an approximately U-shaped or V-shaped groove profile in which the face line 13 is guided within an angular range of the circumference, for example By winding it around the tensioning shaft 33 in a range of 360 °.

The outer contour of the pair of disk portions 39a of the wheel-type tensioning disk 39 is formed by two ribbon loops 40 each having a plurality of ribbons that are bent axially outward in the +/- x direction. 41. The arrangement of the ribbons 41 of the two ribbon loops 40 in the circumferential direction causes the ribbons 41 to be associated with one of the two ribbon loops 40 and then to the two ribbon loops 40 in an alternating manner. Associated with another. The contour base of the groove contour is formed by a holding portion 42 of the ribbon 41, which holding portions overlap each other in the x direction. This ensures that the upper thread 13 extends with a precisely defined radius relative to the axis of the tensioning shaft 33 when wound around a pair of disk portions 39 a of the tensioning disk 39.

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

Regardless of whether the tensioning units 34, 35 are configured as a paired pressure tensioning disk 36 or a paired disk portion 39a of a wheel-type tensioning disk 39, at least one tensioning unit of the main wire tensioning device 32 may be composed of A stepping motor is formed, and the stepping motor drives the rotation of the tension shaft 33. Then, the tensioning shaft 33 may be directly configured as a motor shaft of a stepping motor of this type, or the tensioning shaft may be connected to the motor shaft of the stepping motor via a gear unit. When the tensioning unit is configured as a stepping motor, the upper thread 13 can be completely wound on the tensioning shaft 33, especially more than once.

As can be seen from FIGS. 2 to 5, the housing part 30 can be equipped with components which, by guiding the face line 13 accordingly, allow the two main line tensioning devices to be formed in the manner described above for the tensioning device 32. In other words, as shown in these figures, the housing portion 30 may carry two mainline tensioning devices with associated tensioning shafts, associated actuators, and associated tensioning Unit and associated line path deflection element.

The actuators 37 act on the tensioning disks 36 or 39 of the tensioning units 34, 35 via compression springs 34, respectively. The compression spring 34 may be a coil spring, particularly a coil wire spring. When an actuator 37 configured as a torque motor-controlled servo motor or stepper motor is used, this type of tension spring may also be omitted.

In the embodiment of the tensioning units 34, 35 with a pressure tensioning disk 36, the thread tension is generated by the pressure exerted by the actuator 37 between the corresponding tensioning disks 36 on a line disposed therebetween. The tensioning disk 36 may be non-rotatably arranged on the tensioning shaft 33. In the embodiment of the disk portion 39a with the corresponding wheeled tensioning disk 39, the tension is generated by the braking effect of the pressure of the actuator 37 between the corresponding wheeled tensioning disk 39 and the brake body The wheel-type tensioning disc rotates together with the wire wound thereon in its thread path, and the brake body can be arranged non-rotatably with respect to the tensioning shaft 33. For example, the brake body may be a bearing disk 37a.

In the thread path downstream of the main thread tensioning device 32, the upper thread 13 passes through the thread fastening spring 44 (see also FIG. 1) to the eyelet of the needle 10 before extending through the thread rod 8.

FIG. 7 shows the wire path of the wire tensioner 32. The figure shows one of the two wire tensioning devices 32 of the embodiment shown in FIGS. 1 to 5. Then, the thread path in the other thread tensioner 32 corresponds to it.

The needle thread 13 is first bypassed from a thread pretensioning device (not shown in FIG. 7) over a first pair 45 of a pressure tensioning disk 36 (first tensioning unit). In doing so, the needle thread is wound more than 180 ° around the tensioning shaft 33 and can also be completely wound more than once around the tensioning shaft 33. In the illustrated embodiment, in the region of the first pair 45 of the pressure tensioning disks 36, the needle thread is wound around the tensioning shaft 33 at an angular range of approximately 270 °. When the needle thread is wound around the first pair 45, a first thread tension effect is generated on the sewing thread 13.

Then, before extending into the second pair 46 of the pressure tensioning disks 36 (second tensioning units) of the thread tensioning device 32, the needle thread 13 is wound around the thread path deflecting element 38 at a contact angle of about 180 °, and The first pair 45 is wound around the tensioning shaft 33 in the same manner. When the needle thread is wound around the second pair 46, a second thread tension effect is generated on the sewing thread 13.

Then, the needle thread 13 extends to a thread fastening spring which is not shown in FIG. 7.

A first pair 45 of the pressure tensioning discs 36 is arranged on the housing, while a second pair 46 is arranged towards the free end of the tensioning shaft 33.

In the embodiment shown in FIG. 7, the compression spring 43 is configured as a ripple spring. Corrugated spring blocks can also be used here.

The sewing thread 13 can be wound around the tensioning shaft 33 in the same rotation direction or in the opposite rotation direction in the region of the corresponding tensioning unit 45, 46. Depending on the type of wire and operating conditions, one of the two directions, "the same direction of rotation" or "opposite direction of rotation," may be more beneficial to avoid tangling.

1‧‧‧ sewing machine

1a‧‧‧rack

2‧‧‧ floor

3‧‧‧ bracket

4‧‧‧ arm

5‧‧‧ head

6‧‧‧ arm shaft

7‧‧‧ crank drive

8‧‧‧ pole

9‧‧‧ Needle bar

10‧‧‧ needle

11‧‧‧ vertical axis

12‧‧‧Scrolls

13‧‧‧ needlework; upper thread

13a‧‧‧Beginning of the upper line

14‧‧‧ support plate

15‧‧‧fabric sheet

16‧‧‧ suture plate

17‧‧‧Feed dog teether

18‧‧‧ suture hole

19‧‧‧ Looper

20‧‧‧looper body

21‧‧‧ tip of the looper

22‧‧‧Scrolls

23‧‧‧ Looper axis

25‧‧‧axis

26‧‧‧bearing

27‧‧‧Drive shaft

28‧‧‧Belt Drive

29‧‧‧Thread tensioner

30‧‧‧shell part

32‧‧‧ main line tensioning device

33‧‧‧Tightening shaft

34‧‧‧ tensioning unit; compression spring

35‧‧‧ tensioning unit

36‧‧‧Pressure tensioner

37‧‧‧Actuator

37a‧‧‧bearing disc

38‧‧‧line path deflection element

39‧‧‧ Wheel tensioner

39a‧‧‧ plate section

40‧‧‧ Ribbon Ring

41‧‧‧ Ribbon

42‧‧‧Maintained

43‧‧‧Compression spring

44‧‧‧Wire fastening spring

45‧‧‧ the first pair; tensioning unit

46‧‧‧ second pair; tensioning unit

Exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings, in which:

Fig. 1 shows a schematic front view showing some internal details of a double-lock stitch sewing machine, in which the upper thread path is interrupted in the area of a thread tensioning member not shown in Fig. 1, in other words, not shown;

FIG. 2 shows a front view showing additional details of the housing part of the sewing machine, wherein the components of the thread tensioning device are shown in section I / II, which corresponds to section I in FIG. 1 / II;

3 shows a cross-sectional view taken along the line III-III in FIG. 2;

FIG. 4 illustrates one side of the housing portion as viewed from the viewing direction IV in FIG. 2;

Fig. 5 shows a perspective oblique front view of the housing part shown in Fig. 2;

Figure 6 shows a wheeled tensioning disc with two disc sections, which can form the tensioning unit of the main thread tensioning device of the thread tensioning device, instead of a pair of pressure tensioning discs; and

Fig. 7 shows a side view of one embodiment of a tensioning unit comprising two pairs of pressure tensioning discs and a line path deflection element, the figure showing the line path in the region of the line tensioning device.

Claims (8)

A thread tensioning device for a sewing machine includes: At least one tensioning shaft configured to allow a sewing thread to be tensioned to be wound around the tensioning shaft, At least one tensioning unit that interacts with the tensioning shaft to generate thread tension in the path of the sewing thread downstream of the tensioning shaft, Thread path deflection element to deflect the thread path of the sewing thread, Among them, the thread path of the thread tensioning device makes the sewing thread First, it is wound around the tension axis to generate the first linear tension effect. Then bypass over the line path deflection element, and Wind again around the tensioning axis to generate a second thread tension effect. The thread tensioning device according to claim 1, wherein the thread path deflecting element is configured as a pin rotatable about a pin axis, and the pin is configured to allow a sewing thread to be wound around the pin. The thread tensioning device according to claim 1, wherein the corresponding tensioning unit is formed by at least a pair of pressure tensioning discs and at least one actuator, and the pressure tensioning discs are arranged in pairs so that The tensioned sewing thread passes between the pressure tension discs, which interact with the actuator to set the pressure between the pressure tension discs. The thread tensioning device according to claim 1, characterized in that the corresponding tensioning unit is formed by a wheel-type tensioning disc, a brake body and at least one actuator, which are arranged so that the sewing thread to be tensioned The wheel tensioning disc passes between the disc portions, and the wheel tensioning disc interacts with the actuator to set the pressure exerted on the wheel tensioning disc by the brake body. The thread tensioner according to claim 1, wherein the actuator is configured as a stepper motor. The thread tensioning device according to claim 3, comprising at least two tensioning units arranged on the tensioning shaft, the tensioning units being configured to generate a corresponding thread tension effect. The thread tensioning device according to claim 1, wherein the tensioning unit is formed by at least one stepping motor, and the tensioning shaft is driven by the stepping motor. A sewing machine having the thread tensioning device according to claim 1.