TECHNICAL FIELD
This invention relates to an apparatus and method for slip-free feeding of yarn strands. It is especially useful where tension force is applied in order to increase or decrease the strand tension.
BACKGROUND
The invention relates to an apparatus and method of controlling the movement of a strand. More specifically, it transmits tension and/or velocity from a control mechanism to a moving strand. Strand materials such as filaments, fiberglass, textile yarns and the like are frequently guided around at least a portion of a pulley or sheave in order to add or reduce the strand tension by means of driving or breaking the pulley or sheave. One common problem with these systems is that the frictional forces between the strand and the pulley are insufficient to prevent slippage. To improve the adherence of the strand to the transporting pulley some sheaves are equipped with a waving groove on their periphery which forces the strand to follow its path and through this undulated path increases the friction between the sheave and the strand. One problem inherited with these systems is that the upstream strands have to have a certain tension in order to be pulled into the wavy groove. Another problem is the release of the downstream strand from the groove in the sheave which again requires a certain tension to assure that all filaments of a multi-fiber strand are released. Especially if some fibers of the strand are broken, they have a chance to be wound up around the sheave, fill up the undulated groove and the sheave loses the effect of the friction increasing groove.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a strand delivery system for controlling the tension and/or rate of delivery of a strand to a downstream located strand processing station by improving the coordination of sheave rotation with strand movement through a positive gripping of the strand by the engaging sheaves.
It is another object of object of the invention to be able to present the upstream strand to the feeding sheaves without the need of applying pretension to the upstream strand but rather by the simple act of laying the strand into an open space in the strand delivery system.
Yet a further object of the present invention is to freely release the downstream strand from the feeding sheaves without the need to forcefully pull the downstream strand out of the feeding sheaves.
Another object of the invention is to provide a feeding system without the possibility of the strand or individual fibers from wrapping themselves around rotating mechanical elements.
It is a further object of the invention to adjust the engagement of the protrusions in two sheaves in order to control the undulation of the transported strand.
Yet another object of the invention is to use flexible means to control the amount of undulation in the transported strand in order to limit the stress in the transported strand during it's engagement with the transporting sheaves.
An additional object of the invention is to be able to adjust the force of the flexible means to control the amount of undulation in the transported strand in order to limit the stress in the transported strand during it's engagement with the transporting sheaves to a desirable level.
It is a further object of the invention to provide a physical clamping action of the transported strand during its passing through the feeding disks through flanks of teeth of the feeding system.
Yet another object of the invention is the provision to adjust the clamping force exerted by the feeding disks on the passing strand.
It is yet another object of the invention to apply a clamping action on a strand while it passes through feeding disks by the application of an elastic material which presses the strand against the apex of teeth on an opposite disk.
BRIEF DESCRIPTION OF THE DRAWINGS
Some of the objects of the invention have been set forth above. Other objects and advantages of the invention will appear as the description of the invention proceeds when taken in conjunction with the following drawings, in which:
FIG. 1 is a perspective view of the strand feeder with the strand wrapped around the two tooth wheels;
FIG. 2 is a side view of the strand feeder and demonstrates the open throat of the unit on the right side and the intermeshing teeth on the left;
FIG. 3 shows the back side of the strand feeder with the undulated configuration of the clamped strand between by the tooth wheels;
FIG. 4 gives a top view of the strand feeder;
FIG. 5 gives a cross section of the strand feeder showing the interior parts of the unit;
FIG. 6 shows the major elements of the strand feeder in exploded view and indicates how the parts are fitted together;
In FIG. 7 the two tooth wheels are shown separated with the strand shown between them;
FIG. 8 gives a variance of the strand feeder in a cross sectional view with an adjustable spring to controlling the clamping force of the strand between the two tooth wheels;
FIG. 9 shows another variance where the strand is held against an elastomer or foam material on the bottom wheel by the tooth apex of the upper wheel;
FIG. 10 is a cross section with a disk brake holding the upper tooth wheel 3 back through which means the strand is clamped between the teeth of the two opposing tooth wheels.
FIG. 11 is a cross-section through both wheels showing the various tooth portions.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now specifically to the drawings, FIG. 1 shows in a perspective overall view the strand feeder. It consists of a tension control body 1 with a rotatable lower tooth wheel 2 on top. An upper tooth wheel 3 is located at a slanted angle above the lower tooth wheel 2 and intermeshes with it's teeth 19 on one side with the teeth 19 of the lower tooth wheel 2. The upper tooth wheel 3 is rotatably mounted on the upper bearing housing 4, which is stationary and being held through the mounting bracket 5 onto the tension control body 1. The upstream strand 6 is wrapped around the teeth 19 of the lower tooth wheel 2 and the upper tooth wheel 3 and the downstream strand 7 exits the feeder-system “A” after approximately 270 degree.
In FIG. 2 the side shows the skewed axis 30 of the upper tooth wheel 3 which is biased in relation to the main axis 29. This results in an open throat 28 of the lower tooth wheel 2 and the upper tooth wheel 3 into which the upstream strand 6 is laid.
Referring to FIG. 3, the rear view shows how the undulated strand 8 is held between the teeth 19 for a positive downstream feeding of the downstream strand 7. In addition it can be seen how the upper bearing housing 4 is mounted onto the tension control body 1 by means of the mounting bracket 5
The top of the feeder-system “A” is revealed in FIG. 4. It also shows the upstream strand 6 entering the feeder-system “A” and the downstream strand 7 leaving it. It reveals the top side of the mounting bracket 5 to which is fastened the upper bearing housing 4.
The cross section of the feeder-system “A” in FIG. 5 details the inside of the unit. The control rotor 9 is firmly mounted over the bottom shaft 12. The rotational velocity of the control rotor 9 with lower tooth wheel 2 firmly connected control the feed rate of the unit by electromagnetic means (not shown). The effect of this is a control of the tension in the downstream strand 7 in relation to the upstream strand 6. It also can be used to control the velocity of the downstream strand 7. The bottom shaft 12 is mounted in two body bearings 10 which also maintain its axial position. The top shaft 13 is mounted in two top wheel bearings 11 which in turn are mounted in the adjustment hub 18. The adjustment hub 18 is provided with an external adjustment thread 14. By turning this adjustment hub 18 in the internally threaded mounting bracket 5 its axial position can be adjusted in order to adjust the engagement of the teeth 19 on the lower tooth wheel 2 with the teeth 19 of the upper tooth wheel 3. Through this adjustment, the possibility is given to run finer as well as coarser strands through the feeder-system “A”. An adjustment lock-screw 15 clamps the adjustment hub 18 firmly onto the mounting bracket 5 in order to maintain a adjusted setting. The lower tooth wheel 2 is mounted onto the bottom shaft 12 by means of a lower mounting-flange 16 and the upper tooth wheel 3 is mounted onto the top shaft 13 by means of the upper mounting-flange 17.
Referring to FIG. 6, the exploded view shows the individual sup-assemblies more clearly. The center lines demonstrate how the individual parts are positioned in assembled mode.
In FIG. 7 the lower tooth wheel 2 and the upper tooth wheel 3 are shown separated to more clearly demonstrate how the strand 36 relates to them. The undulated configuration is caused by the teeth 19 of both, the lower tooth wheel 2 and the upper tooth wheel 3. This zigzagging of the strand generates at each bending point additional friction which assists in the positive transport of the strand through the feeder-system “A”. The thickness of the tension teeth 19 can be designed in such a manner that they touch each other on both tooth flanks 35.
A variant of the clamping action is shown in FIG. 8. Rather than a fixed adjustment as shown particularly in FIG. 5 this variation incorporates a spring loaded downward clamping force induced by the tension spring 21 which presses the axially floating hub 22 downward. The rate of the spring force can be adjusted by threading the spring nut 20 up or down on the fixed mounting plate 23. This arrangement allows the upper tooth wheel 3 to self-adjust according to the thickness and/or stiffness of the strand and thus prevents excess stressing of the undulated strand 8.
FIG. 9 reveals another variation of clamping assistance for the strand material. The undulated strand 8 is pressed by the teeth 19 of the upper tooth wheel 3 into a soft elastomer or foam material 31. This provides sufficient clamping force, together with the friction multiplying undulation to positively feed the strand by the feeder-system “A”.
FIG. 10 shows another variation of the invention where a braking force is applied to the upper tooth wheel 3 by means of the brake spring 25, pushing against the brake disk 24. This generates sufficient drag on the upper tooth wheel 3 by pressing its tooth flank 35 against the tooth flank 35 of the lower tooth wheel 2. This pressure provides sufficient clamping force to the passing strand 36 for slip-less feeding. It should be realized that the material of the teeth 19 can be composed of polyurethane or a similar elastic material. The braking force can be adjusted by threading the adjustment nut 26 up or down the fixed mounting hub 27.
In FIG. 11 a cross-section through the lower tooth wheel 2 and upper tooth wheel 3 illustrate the slight skewing of the skewed axis 30 against the main axis 29. The different portions of the teeth 19 are shown with the tooth lead-in 32 assuring that the upstream strand 6 is properly placed into the open throat 28 of the two wheels. The tooth apex 33 is the portion around which the strand 36 (not shown) is laid during its intermeshing with the teeth 19 of the upper tooth wheel 3. The absence of a shaft between the two disks, the constant intermeshing of the tooth nose 34 and the general shape of the teeth 19 prevents broken filament of the strand 36 from moving into the center of the lower tooth wheel 2 and upper tooth wheel 3 and from wrapping itself around any rotating parts disks of the feeder-system “A”.
Although the invention has been described with reference to specific example embodiments, it will be appreciated that it is intended to cover all modifications and equivalents within the scope of the appended claims. It should also be understood that the present disclosure includes all possible combinations and applications of any individual features recited in any of the appended claims.
NUMBERING IN DRAWINGS
- feeder-system “A”
- tension control body 1
- lower tooth wheel 2
- upper tooth wheel 3
- upper bearing housing 4
- mounting bracket 5
- upstream strand 6
- downstream strand 7
- undulated strand 8
- control rotor 9
- body bearing 10
- top wheel bearings 11
- bottom shaft 12
- top shaft 13
- adjustment thread 14
- adjustment lock-screw 15
- lower mounting-flange 16
- upper mounting-flange 17
- adjustment hub 18
- teeth 19
- spring nut 20
- tension spring 21
- axially floating hub 22
- fixed mounting plate 23
- brake disk 24
- brake spring 25
- adjustment nut 26
- fixed mounting hub 27
- open throat 28
- main axis 29
- skewed axis 30
- elastomer or foam material 31
- tooth lead-in 32
- tooth apex 33
- tooth nose 34
- tooth flank 35
- strand 36
Patent Application
20100287994
