MEANS FOR IMPARTING TENSION TO THE DRAWN-OUT THREAD FOR SEWING MACHINES
United States Patent 3786771
According to the invention, the drawn-out thread of a sewing machine is guided between a roller having a thread releasing notch formed in part of the roller periphery and a thread urging member urged against the roller periphery, with the roller rotated in the direction opposite to the direction of withdrawal of the thread, so that the thread can be effectively rendered taut and loose alternately by the co-operation of the roller and thread urging member.
US Patent References:
Web-feeding arrangement
Wyrick - November 1945 - 2389834
Looper thread take up for double chain stitch sewing machines
Irmscher - December 1958 - 2866427
/1030742.html
Meyer - June 1912 - 1030742
/1565109.html
Rose - December 1925 - 1565109
Web-feeding arrangement
Wyrick - November 1945 - 2389834
Looper thread take up for double chain stitch sewing machines
Irmscher - December 1958 - 2866427
/1030742.html
Meyer - June 1912 - 1030742
/1565109.html
Rose - December 1925 - 1565109
Application Number:
05/213080
Publication Date:
01/22/1974
Filing Date:
12/28/1971
View Patent Images:
Export Citation:
Assignee:
Nara Mishin Kogyo Kabushiki Kaisha (Tokyo, JA)
Primary Class:
Other Classes:
226/195, 242/147R
International Classes:
D05B47/00; D05B47/00
Field of Search:
112/254,255 242/147,149,151 19/237,238 226/195,153
Primary Examiner:
Krizmanich, George H.
Attorney, Agent or Firm:
Cushman, Darby & Cushman
Claims:
What is claimed is
1. In a sewing machine, a sewing machine body and means for imparting tension to a thread being fed comprising:
2. The apparatus of claim 1 wherein the resilient biasing means comprises:
3. The apparatus of claim 1 wherein the notch is shorter, axially of the roller, than said convex arcuate surface to prevent that surface from entering the notch.
1. In a sewing machine, a sewing machine body and means for imparting tension to a thread being fed comprising:
2. The apparatus of claim 1 wherein the resilient biasing means comprises:
3. The apparatus of claim 1 wherein the notch is shorter, axially of the roller, than said convex arcuate surface to prevent that surface from entering the notch.
Description:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention generally relates to sewing machines and, more particularly, to means to impart tension to the progressively payed-out thread in a predetermined relation to the movement of the sewing machine needle.
2. Description of the Prior Art
Means to impart tension to the drawn-out thread for sewing machines are well known in the art.
A typical example of the tension imparting means is shown in FIG. 1 of the accompanying drawing. It comprises a drive shaft 2 rotatably provided in the machine body 1 and carrying an integral cam 3 co-operating with an actuating member 4 coupled through a coupling 5 to a rod 6 adapted to intermittently urge upper and lower dish-like thread clamping members 8 downwardly spring biased with a spring 7. With this construction, the drawn-out thread is intermittently clamped between the clamping members as the rod 6 tied through the coupling 5 to the actuating member 4 is vertically reciprocated by the rotation of the cam 3 with the drive shaft 2. In other words, the clamping members 8 are intermittently urged to each other, so that in some part of one machine operation cycle tension is imparted to the thread guided between the clamping members while in the other cycle the thread is released by the clamping members.
With the above construction, however, the actuating member cannot reliably follow the eccentric cam when the drive shaft is rotated at high speeds. Therefore, the clamping members sometimes fail to execute vertical excursion, resulting in a continued loose state of the thread, which results in sewing irregularity. Also, this imposes restriction upon the sewing speed. Further, intense noise is produced in the high-speed operation of the machine. Furthermore, this construction readily runs short of lubricating oil.
SUMMARY OF THE INVENTION
The inventors have devoted extensive efforts to overcome the above drawbacks and succeeded in completing a tension imparting means which can obviate the above shortcomings.
An object of the invention is to provide a means to impart tension to the drawn-out thread for sewing machines, which is free from the failure of the vertical excursion of clamping members even at high speeds of drive shaft and is capable of exactly and reliably rendering the thread taut and loose to prevent the generation of the sewing irregularity.
A second object of the invention is to provide a means to impart tension to the drawn-out sewing thread for sewing machines, which can exactly and reliably render the thread taut and loose and enable realizing sewing operation at increased speeds.
A third object of the invention is to provide a means to impart tension to the drawn-out sewing thread for sewing machines, which is free from the generation of intense noise even in the high-speed operation of the machine, and in which the lubricating oil will not readily get short.
A fourth object of the invention is to provide a means to impart tension to the drawn-out sewing thread for sewing machines, which is capable of exactly and reliably rendering the thread taut and loose and provides excellent response in the high-speed operation of the machine.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a front elevation, partly broken away, of a conventional sewing machine with a showing of a tension imparting means.
FIG. 2 is a plan view showing part of the tension imparting means embodying the invention.
FIG. 3 is a fragmentary sectional view, to an enlarged scale, showing the embodiment of FIG. 2.
FIGS. 4 and 5 are fragmentary side views showing different states of co-operation of roller and thread urging member.
DESCRIPTION OF THE PREFERRED EMBODIMENT
For the invention to be more fully understood, a preferred embodiment thereof will now be described by having reference to the accompanying drawing.
Referring to FIGS. 2 and 3, reference numeral 10 generally designates a tension imparting means embodying the invention. It has a roller 11 secured to one end of a shaft 12 rotatably mounted in the machine body 1. The roller 11 is formed with a planar notch or groove 13 cut in some part of the roller periphery. This groove 13 provides for the function of alternately rendering the thread clamped and released. That is, a drawn-out thread is rendered taut when a thread urging member designated by numeral 16 is urged against part of the roller periphery other than the part formed with the groove 13, and the drawn-out thread is rendered loose when the thread urging member 16 is urged against the roller periphery part formed with the groove 13 so that the thread is drawn out at higher speeds than the time when it is taut. This alternative taut and loose action of the thread is achieved by the rotation of the roller 11, thus feeding the thread successively. Secured to the other end of the shaft 12 is a bevel gear 14 meshing with another bevel gear 15 secured to a drive shaft 2 rotatably mounted in the machine body 1. The drive shaft 2 also drives a thread draw-out means not shown. The roller 11 is adapted to complete one rotation with one rotation of the drive shaft 2.
The thread urging member has a hooklike form with its arcuate portion 17 urged against the periphery of the roller 11. The thread urging member 16 is pivoted to the machine body 1 by a pin 18 mounted on the machine body.
The opposite end of the thread urging member 16 is freely movably fitted on an angleshaped guide rod 19 mounted on the machine body 1 with a vertical portion 23 embedded in the machine body 1. And on the threaded end of the guide rod 19 there is fitted a nut 21 and a coil spring 22 is intervened between the nut 21 and said opposite end of the thread urging member 16. Thus, the arcular portion 17 of the thread urging member 16 is movably urged against the periphery of the roller 11 with respect to the pin 18 in such a manner that said opposite end of the thread urging member 16 is urged by the coil spring 22, as shown in FIG. 2.
Numeral 24 in FIG. 2 designates the thread being drawn out. The roller 11 is rotated in the direction opposite to the direction of progress of the thread 24. The groove 13 formed in the periphery of the roller 13 is slightly narrower than the width of the urging area of the urging member 16.
In the operation of the tension imparting means of the above construction, the torque of the drive shaft 2 rotated in synchronism with the machine operation is transmitted through the bevel gears 15 and 14 to the shaft 12 to rotate the same. With the rotation of the shaft 12 the roller 11 integral therewith also rotates, while the arcular portion 17 of the urging member 16 is held urged against the revolving roller periphery of the roller 11 by the coil spring 22. The thread 24 is guided in the direction of solid arrow in FIG. 2 between the roller 11 and the arcular portion 17 of the urging member 16. When the arcuate portion 17 is engaging with part of the roller periphery other than the part formed with the groove 13 during part of the machine cycle, as shown in FIG. 4, the drawn-out thread 24 is rendered taut. On the other hand, when the arcuate portion 17 is engaging with the roller periphery part formed with the groove 13, as shown in FIG. 5, the drawn-out thread 24 is rendered loose. In the above manner, the thread is alternately rendered taut and loose in accordance with the machine cycle.
As has been described in the foregoing, with the arrangement according to the invention wherein the drawn-out thread is guided between the periphery of a roller formed with a thread relaxation notch or groove and rotated in the direction opposite to the direction of progress of the thread and a thread urging member urged against the roller periphery, when the urging member is in frictional contact with part of the roller periphery other than the part formed with the thread relaxation groove the thread is frictionally clamped between the roller and the urging member to experience tension, whereas when the urging area of the urging member coincides with the thread relaxiation groove the thread is released from the clamping and is ready to be freely drawn out. In the above manner, the alternate rendering of the thread taut and loose is achieved through the roller and the urging member urged against the roller periphery, so that the response of the tension imparting means particularly in the high speed operation of the machine is excellent and the feed of the thread drawn out can be exactly and reliably timed to the movement of the sewing machine needle. Thus, sewing irregularity which might occur with the conventional sewing machines can be eliminated. Also, noise can be eliminated even in the high-speed operation of the sewing machine.
1. Field of the Invention
This invention generally relates to sewing machines and, more particularly, to means to impart tension to the progressively payed-out thread in a predetermined relation to the movement of the sewing machine needle.
2. Description of the Prior Art
Means to impart tension to the drawn-out thread for sewing machines are well known in the art.
A typical example of the tension imparting means is shown in FIG. 1 of the accompanying drawing. It comprises a drive shaft 2 rotatably provided in the machine body 1 and carrying an integral cam 3 co-operating with an actuating member 4 coupled through a coupling 5 to a rod 6 adapted to intermittently urge upper and lower dish-like thread clamping members 8 downwardly spring biased with a spring 7. With this construction, the drawn-out thread is intermittently clamped between the clamping members as the rod 6 tied through the coupling 5 to the actuating member 4 is vertically reciprocated by the rotation of the cam 3 with the drive shaft 2. In other words, the clamping members 8 are intermittently urged to each other, so that in some part of one machine operation cycle tension is imparted to the thread guided between the clamping members while in the other cycle the thread is released by the clamping members.
With the above construction, however, the actuating member cannot reliably follow the eccentric cam when the drive shaft is rotated at high speeds. Therefore, the clamping members sometimes fail to execute vertical excursion, resulting in a continued loose state of the thread, which results in sewing irregularity. Also, this imposes restriction upon the sewing speed. Further, intense noise is produced in the high-speed operation of the machine. Furthermore, this construction readily runs short of lubricating oil.
SUMMARY OF THE INVENTION
The inventors have devoted extensive efforts to overcome the above drawbacks and succeeded in completing a tension imparting means which can obviate the above shortcomings.
An object of the invention is to provide a means to impart tension to the drawn-out thread for sewing machines, which is free from the failure of the vertical excursion of clamping members even at high speeds of drive shaft and is capable of exactly and reliably rendering the thread taut and loose to prevent the generation of the sewing irregularity.
A second object of the invention is to provide a means to impart tension to the drawn-out sewing thread for sewing machines, which can exactly and reliably render the thread taut and loose and enable realizing sewing operation at increased speeds.
A third object of the invention is to provide a means to impart tension to the drawn-out sewing thread for sewing machines, which is free from the generation of intense noise even in the high-speed operation of the machine, and in which the lubricating oil will not readily get short.
A fourth object of the invention is to provide a means to impart tension to the drawn-out sewing thread for sewing machines, which is capable of exactly and reliably rendering the thread taut and loose and provides excellent response in the high-speed operation of the machine.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a front elevation, partly broken away, of a conventional sewing machine with a showing of a tension imparting means.
FIG. 2 is a plan view showing part of the tension imparting means embodying the invention.
FIG. 3 is a fragmentary sectional view, to an enlarged scale, showing the embodiment of FIG. 2.
FIGS. 4 and 5 are fragmentary side views showing different states of co-operation of roller and thread urging member.
DESCRIPTION OF THE PREFERRED EMBODIMENT
For the invention to be more fully understood, a preferred embodiment thereof will now be described by having reference to the accompanying drawing.
Referring to FIGS. 2 and 3, reference numeral 10 generally designates a tension imparting means embodying the invention. It has a roller 11 secured to one end of a shaft 12 rotatably mounted in the machine body 1. The roller 11 is formed with a planar notch or groove 13 cut in some part of the roller periphery. This groove 13 provides for the function of alternately rendering the thread clamped and released. That is, a drawn-out thread is rendered taut when a thread urging member designated by numeral 16 is urged against part of the roller periphery other than the part formed with the groove 13, and the drawn-out thread is rendered loose when the thread urging member 16 is urged against the roller periphery part formed with the groove 13 so that the thread is drawn out at higher speeds than the time when it is taut. This alternative taut and loose action of the thread is achieved by the rotation of the roller 11, thus feeding the thread successively. Secured to the other end of the shaft 12 is a bevel gear 14 meshing with another bevel gear 15 secured to a drive shaft 2 rotatably mounted in the machine body 1. The drive shaft 2 also drives a thread draw-out means not shown. The roller 11 is adapted to complete one rotation with one rotation of the drive shaft 2.
The thread urging member has a hooklike form with its arcuate portion 17 urged against the periphery of the roller 11. The thread urging member 16 is pivoted to the machine body 1 by a pin 18 mounted on the machine body.
The opposite end of the thread urging member 16 is freely movably fitted on an angleshaped guide rod 19 mounted on the machine body 1 with a vertical portion 23 embedded in the machine body 1. And on the threaded end of the guide rod 19 there is fitted a nut 21 and a coil spring 22 is intervened between the nut 21 and said opposite end of the thread urging member 16. Thus, the arcular portion 17 of the thread urging member 16 is movably urged against the periphery of the roller 11 with respect to the pin 18 in such a manner that said opposite end of the thread urging member 16 is urged by the coil spring 22, as shown in FIG. 2.
Numeral 24 in FIG. 2 designates the thread being drawn out. The roller 11 is rotated in the direction opposite to the direction of progress of the thread 24. The groove 13 formed in the periphery of the roller 13 is slightly narrower than the width of the urging area of the urging member 16.
In the operation of the tension imparting means of the above construction, the torque of the drive shaft 2 rotated in synchronism with the machine operation is transmitted through the bevel gears 15 and 14 to the shaft 12 to rotate the same. With the rotation of the shaft 12 the roller 11 integral therewith also rotates, while the arcular portion 17 of the urging member 16 is held urged against the revolving roller periphery of the roller 11 by the coil spring 22. The thread 24 is guided in the direction of solid arrow in FIG. 2 between the roller 11 and the arcular portion 17 of the urging member 16. When the arcuate portion 17 is engaging with part of the roller periphery other than the part formed with the groove 13 during part of the machine cycle, as shown in FIG. 4, the drawn-out thread 24 is rendered taut. On the other hand, when the arcuate portion 17 is engaging with the roller periphery part formed with the groove 13, as shown in FIG. 5, the drawn-out thread 24 is rendered loose. In the above manner, the thread is alternately rendered taut and loose in accordance with the machine cycle.
As has been described in the foregoing, with the arrangement according to the invention wherein the drawn-out thread is guided between the periphery of a roller formed with a thread relaxation notch or groove and rotated in the direction opposite to the direction of progress of the thread and a thread urging member urged against the roller periphery, when the urging member is in frictional contact with part of the roller periphery other than the part formed with the thread relaxation groove the thread is frictionally clamped between the roller and the urging member to experience tension, whereas when the urging area of the urging member coincides with the thread relaxiation groove the thread is released from the clamping and is ready to be freely drawn out. In the above manner, the alternate rendering of the thread taut and loose is achieved through the roller and the urging member urged against the roller periphery, so that the response of the tension imparting means particularly in the high speed operation of the machine is excellent and the feed of the thread drawn out can be exactly and reliably timed to the movement of the sewing machine needle. Thus, sewing irregularity which might occur with the conventional sewing machines can be eliminated. Also, noise can be eliminated even in the high-speed operation of the sewing machine.