Four Roll Servo Driven Yarn Feed Module for Precision Yarn Feed

Abstract

A yarn feed module may be provided with four small diameter yarn feed rolls and a plasma treated yarn feed surface to optimize secure yarn grip for precise feeding by servo drive with greater durability and fewer yarn entanglements, utilizing a variety of threading configurations.

Claims

1. A multiple needle tufting machine having a plurality of servo motor driven yarn feed modules for feeding yarns from a yarn supply to the needles wherein a servo motor drives a teethed sprocket that cooperates with teethed sections of first and second yarn feed rolls mounted on parallel rotational axes for rotational movement, and the teethed section of the first yarn feed roll cooperates to drive a teethed section of a third yarn feed roll, and the teethed section of the second yarn feed roll cooperates to drive a teethed section of a fourth yarn feed roll.

2. The tufting machine of claim 1 wherein the first, second, third, and fourth yarn feed rolls each have a yarn feeding surface with a diameter of less than 1.5 inches.

3. The tufting machine of claim 1 wherein the first, second, third, and fourth yarn feed rolls each have a polymer yarn feeding surface that is plasma treated to enhance surface adhesion.

4. The tufting machine of claim 1 wherein a single yarn is fed through each of the yarn feed modules to a needle.

5. The tufting machine of claim 1 wherein at least two yarns are fed though each of the yarn feed modules and then through a tube bank and to selected needles.

6. The tufting machine of claim 4 wherein the first, second, third, and fourth yarn feed rolls each have a yarn feeding surface and the yarn is fed around portions of the yarn feeding surfaces of said first, second, third, and fourth yarn feed rolls so that the aggregate amount of wrap of the yarn on the yarn feeding surfaces is at least 3.

7. The tufting machine of claim 4 wherein the first, second, third, and fourth yarn feed rolls each have a yarn feeding surface and the yarn is fed around portions of the yarn feeding surfaces of at least three of said first, second, third, and fourth yarn feed rolls so that the aggregate amount of wrap of the yarn on the yarn feeding surfaces is at least 3.

8. A four roll yarn feed module for feeding yarns from a yarn supply to a needle on a multiple needle tufting machine comprising a servo motor mounted to rotationally drive a teethed sprocket, said teethed sprocket cooperating with and driving teethed sections of first and second yarn feed rolls having yarn feeding surfaces mounted on parallel rotational axes for rotational movement, and the teethed section of the first yarn feed roll cooperating to drive a teethed section of a third yarn feed roll having a yarn feeding surface, and the teethed section of the second yarn feed roll cooperating to drive a teethed section of a fourth yarn feed roll having a yarn feeding surface.

9. The yarn feed module of claim 8 wherein the diameter of the yarn feeding surface portion of the first, second, third, and fourth yarn feed rolls is less than 1.5 inches.

10. The yarn feed module of claim 8 wherein the yarn feeding surfaces of the first, second, third, and fourth yarn feed rolls is a plasma treated polymer material.

11. The yarn feed module of claim 8 wherein a yarn is fed from the yarn supply around portions of the yarn feeding surfaces of said first, second, third, and fourth yarn feed rolls so that the aggregate amount of wrap of the yarn on the yarn feeding surfaces is at least 3.

12. The yarn feed module of claim 8 wherein a yarn is fed from the yarn supply around portions of the yarn feeding surfaces of at least three of said first, second, third, and fourth yarn feed rolls so that the aggregate amount of wrap of the yarn on the yarn feeding surfaces is at least 3.

13. The yarn feed module of claim 8 wherein at least two yarns are fed though the yarn feed module and then through a tube bank and to selected needles.

14. The yarn feed module of claim 13 wherein a first of the at least two yarns is fed from the yarn supply around portions of the yarn feeding surfaces of the first and third yarn feed rolls but not the yarn feeding surfaces of the second and fourth yarn feed rolls.

15. The yarn feed module of claim 14 wherein a second of the at least two yarns is fed from the yarn supply around portions of the yarn feeding surfaces of the second and fourth yarn feed rolls.

16. A method of threading a four roll yarn feed module for feeding yarns from a yarn supply to a needle on a multiple needle tufting machine that comprises a servo motor mounted to rotationally drive a first top left yarn feed roll, a second top right yarn feed roll, a third bottom left yarn feed roll, and a fourth bottom right yarn feed roll, with each of the first, second, third, and fourth yarn feed rolls having a yarn feeding surface, and being mounted on parallel rotational axes for rotational movement, comprising feeding yarn around portions of the yarn feeding surfaces of at least three of said first, second, third, and fourth yarn feed rolls so that the aggregate amount of wrap of the yarn on the yarn feeding surfaces is at least 3.

17. The method of claim 16 wherein the yarn is fed from left to right across the top of the yarn feeding surface of the first yarn feed roll and downward and to the left around the left side and bottom of the yarn feeding surface of the third yarn feed roll, and to the right across the bottom of the yarn feed surface of the fourth yarn feed roll and upward around the right of the yarn feed surface of the fourth yarn feed roll and upward and to the left around the left and top of the yarn feeding surface of the second yarn feed roll and toward a selected tufting needle.

18. The method of claim 16 wherein the yarn is fed from left to right across the bottom of the yarn feeding surface of the third yarn feed roll and upward and to the left around the left side and top of the yarn feeding surface of the first yarn feed roll, and downward to the right across the bottom of the yarn feed surface of the fourth yarn feed roll and upward around the right of the yarn feed surface of the fourth yarn feed roll and upward and to the left around the left and top of the yarn feeding surface of the second yarn feed roll and toward a selected tufting needle.

19. The method of claim 16 wherein the yarn is fed from left to right across the top of the yarn feeding surface of the first yarn feed roll and downward and to the left around the left side and bottom of the yarn feeding surface of the third yarn feed roll, and upward to the right around the left and top of the yarn feeding surface of the second yarn feed roll, and downward to the left across the top and left of the yarn feeding surface of the fourth yarn feed roll and toward a selected tufting needle.

20. The method of claim 16 wherein the yarn is fed from left to right across the top of the yarn feeding surface of the first yarn feed roll and downward and to the left around the left side and bottom of the yarn feeding surface of the third yarn feed roll, and upward around the left and top of the yarn feeding surface of the second yarn feed roll and toward a selected tufting needle.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Particular features and advantages of the present invention will become apparent from the following description when considered in conjunction with the accompanying drawings in which:

[0017] FIG. 1A is a side plan view of a servo scroll yarn feed module as depicted in U.S. Pat. No. 7,089,874.

[0018] FIG. 1B is an end plan view of the yarn feed module of FIG. 1;

[0019] FIG. 2A is an exploded view of a single end yarn feed module with two small diameter yarn feed rolls;

[0020] FIG. 2B is a side plan view of the single end yarn feed module of FIG. 2A.

[0021] FIG. 3 is a perspective view of a yarn feed system with a modular yarn feed motor and yarn feed pinch roller assembly as depicted in U.S. Pat. No. 6,807,927;

[0022] FIG. 4 is an exploded perspective view of the modular yarn feed motor and yarn feed pinch roller assembly of FIG. 3;

[0023] FIG. 5 is a perspective view of a three roll yarn feed module as shown in U.S. Pub. 2018/0363186;

[0024] FIG. 6A is an exploded view of a four yarn feed roll yarn drive module;

[0025] FIG. 6B is a side plan view of the four roll yarn feed module of FIG. 6A;

[0026] FIG. 7 is an exemplary illustration of four yarn feed roll modules with alternative yarn wrap or threading arrangements;

[0027] FIG. 8 is a perspective view of an array of four feed roll yarn feed modules;

[0028] FIG. 9A though 9F depict arrangements of a four yarn feed roll module utilized to separately feed one or two yarns around yarn feed rolls.

DETAILED DESCRIPTION OF THE DRAWINGS

[0029] A presently preferred embodiment of a four-roll yarn feed module is shown in FIGS. 6-9, wherein in FIG. 6A a servo motor 438 is received on one side of a mounting plate 435 and on the opposite side a driven sprocket 439 interfaces with preferably two of the four yarn feed drive rolls 436,437,446,447 on their teethed peripheries 440 that are preferably recessed into the surface of mounting plate 435. Yarn feed bolts 445 are utilized to rotatably secure yarn feed rolls 436,437,446,447 to the mounting plate 435 and serve as parallel axes of rotation for said rolls. Each of the yarn feed rolls 436,437,446,447 has a yarn feed surface 441 that may have differing gripping and durability characteristics as desired. The diameter of the yarn feed surface portions of the rolls is less than 1.5 inches and preferably closer to about one inch. This allows for compact construction and relatively low rotational mass to be controlled. If connected, the axes of rotation of the four yarn feed rolls generally correspond to vertices of a rectangle with roll 436 in the top left, roll 437 in the top right, roll 446 in the bottom left, and roll 447 in the bottom right. FIG. 6B provides a side plan view of an assembled yarn feed module from the side with protruding yarn feed rolls.

[0030] The yarns 416 may be threaded about yarn feed rolls 436,437,446,447 in a variety of ways as shown in FIG. 7. For instance, at the topmost yarn feed module designated A yarn proceeds around the top of yarn feed surface 441 of first yarn feed roll 436 and then rearward and around the bottom yarn feed surfaces 441 of lower yarn feed rolls 446,447 and thence upward and slightly rearward to go around and over the yarn feed surface 441 of yarn feed roll 437 and down to yarn guide 450 typically of ceramic construction. The amount of wrap on this yarn thread configuration is approximately 180 on roll 436, approximately 150 on roll 446, approximately 150 on roll 447 and approximately 270 on roll 437. This in aggregate compromises approximately 750 (25/6.sup.ths ).

[0031] The second thread-up, designated B in FIG. 7, shows yarn proceeding beneath the bottom yarn feed surface 441 of lower left yarn feed roll 446 and upward and rearward to encircle much of the yarn feed surface 441 of upper left yarn feed roll 436 and downward and around yarn feed surface 441 beneath lower right yarn feed roll 447 and up and rearward and around yarn feed surface 441 of upper right yarn feed roll 437 so that aggregate wrap is approximately 180 on roll 446, approximately 270 on roll 436 and approximately 210 on roll 447 and approximately 270 on roll 437 to aggregate 930 of wrap (31/6.sup.ths ).

[0032] The third alternative threading, designated C, around four yarn feed rolls has yarn 416 passing over the yarn feed surface of 441 of top left roll 436 and down and rearward around and beneath roll 446 and up and over roll 437, while entirely omitting the use of roll 447. In this fashion, the yarn is wrapped around slightly more than 180 of each of rolls 436,446,437 for an aggregate of over 540 (3 ).

[0033] The final illustrated threading, designated D, has yarn going over the yarn feed surface 441 of top left roll 436 and rearward around beneath lower left roll 446 and up over and around the yarn feed surface 441 of top right roll 437 and around and rearward beneath roll 447 so that wraps on each of rolls 436,446,447 are approximately 180 while the wrap on roll 437 is approximately in excess of 270 for a total wrap of 810 (9/2 ). The threadings of A-D are illustrative of different possibilities. It will be understood that generally all modules on a tufting machine will be threaded about the yarn feed rolls in the same fashion for a particular pattern and yarn selection.

[0034] FIG. 8 illustrates an array of four roll yarn feeds with yarn guides to allow for feeding four or even five yarns through each yarn feed module, such multi-yarn thread-ups generally being associated with the use of tube banks to distribute yarns from the yarn feed modules to desired needle locations.

[0035] Turning then to FIGS. 9A-F, FIGS. 9B, 9C, 9D and 9F illustrate feeding of single yarns similar to those discussed in connection with FIG. 7. However, FIGS. 9A and 9E illustrate the feeding of two yarns, each being feed about the yarn feed surfaces 441 of two of the four yarn feed rolls. In FIG. 9A, first yarn 416a is fed from yarn guide 413a beneath the yarn feed surface 441 of yarn feed roll 446 then upward and rearward around yarn feed roll 436 and to yarn guide 450. A second yarn 416b emerges from yarn guide 413b and proceeds beneath yarn roll 447 and upward and rearward and over yarn feed roll 437 and thence to yarn guide. In this fashion, the yarn feed module receives two yarns that each are passed around two of the four yarn feed rolls and in that fashion the yarns do not bind with one another although each yarn will necessarily be fed in identical increments to the other on each stitch.

[0036] FIGS. 9E and 9F show detailed degree calculations for the amount of yarn wrap around the yarn feed rolls in their respective thread-ups.

[0037] It has generally been viewed as canon that three techniques could be utilized to minimize yarn slippage in pattern control yarn feed apparatus. One technique was to control the yarn by pinching between yarn feed rollers. Second technique was to use a gripping surface such as sandpaper to advance the yarns. A third technique was to apply the yarn along longer lengths of gripping surface material to increase frictional resistance, such as by using larger diameter yarn feed rolls. In practice, the application of pinching force for gripping created excessive wear on yarn feed roll components and the use of larger diameter yarn feed rolls introduced additional weight and momentum into the yarn feed system which not only created material expense but also the added momentum hindering precise high-speed changes in yarn feed speeds on a stitch-by-stitch basis. Coarse of sandpaper yarn feed surfaces provide increased yarn grip, however with some types of yarn these surfaces lead to snagging and wrapping yarns around the feed rolls instead of onward to the needles. Sandpaper or grit surfaces also wear and may require resurfacing to extend the lives of the yarn feed rolls.

[0038] The present invention is ideally implemented with an improved friction material which is a plasma coated/treated yarn feed roll plastic or polymer surface in lieu of sandpaper. This plasma treated surface provides some friction and enhanced durability while minimizing snagging and wrapping that may occur on sandpaper systems although without aggressively gripping yarns in the fashion of a coarse sandpaper yarn feed surface. The grip provided by the yarn feed rolls on the fed yarn may be adjusted by altering the amount of yarn wrap provided by the threading of the yarn modules. To provide secure yarn friction and grip, it has been determined that the increased yarn wrap provides not only frictional contact, but also the application of a variant of the capstan equation (or belt friction equation) providing that greater wrap around the yarn feed roll significantly increases the holding force of the rolls on the wrapped yarn. The capstan equation or Euler-Eytelwein formula provides:

T.sub.Load=T.sub.Hold.sup.e().

T.sub.Load, is the total load, T.sub.Hold is the total holding load, is the coefficient of static friction between the line or yarn and the roller and is the radians of wrap between the line (yarn) and capstan (yarn feed roll). Since a multi-roll yarn feed is not a single roll capstan, it is surprising to see that the general exponential relationship still seems to be applicable, even though not exactly as the capstan formula would predict.

[0039] The capstan equation provides that the relationship between load force and holding force varies exponentially with the frictional coefficient and the total amount of wrap between the feed roll and the yarn. The four-roll system and intelligent yarn threadup about the rolls greatly increases the radians of yarn wrap. Even though there is a slightly lowered friction coefficient from utilizing plasma treatment to enhance surface adhesion in lieu of a sandpaper of grit surface, the result is overall improvement in yarn control with a reduction in failures due to snagging, wrapping and bunching of yarns.

[0040] Even though the use of separate yarn feed rolls differs from multiple wrappings around a single capstan, experimentation showed a similar result in holding force on yarns. Experiments were conducted with a slick, low friction yarn, a relatively standard yarn, and a relatively hairy yarn with looser fibers more prone to snagging and wrapping. At one end of each test piece of yarn, the holding weight was attached and at the other end a force gauge sensor with a pull hook. Standard two roll and four roll faceplates were prepared so that the attached rolls were in proper arrangement but unable to spin freely, while providing an adjustable freely spinning roll to control yarn entry angle.

[0041] Each test was carried out by wrapping a length of yarn over the free-spinning entry roller and then through a running path of either the four roll or two roll configurations and force was slowly applied until the yarn slipped, and the peak force measured by the gauge was recorded and the test reset. Tests were conducted with the four-roll plasma configuration, a two-roll plasma configuration, and also a two-roll sandpaper configuration. The high friction, hairy yarn was readily grippable and also had a lower breaking force because of the looseness of its fibers so that it was consistently breaking before any slippage occurred. In the case of two-roll plasma configuration, additional weight on the holding side was required because the configuration had such a low coefficient friction there was not adequate gripping force with a light holding force. The greater weight or tension on the yarn increased the amount of friction applied by the two-roll system. Accordingly, the measurements obtained were useful in a relative sense but not completely comparable, and so the testing was only used to confirm the applicability of the capstan equation to multi-roll yarn feed, but did not provide a precise equation for determining grip so that some case-by-case experimentation is still deemed necessary depending upon the yarns and yarn feed requirement for a particular pattern.

[0042] Numerous alterations of the structure herein disclosed will suggest themselves to those skilled in the art. However, it is to be understood that the present disclosure relates to the preferred embodiment of the invention which is for purposes of illustration only and not to be construed as a limitation of the invention. All such modifications which do not depart from the spirit of the invention are intended to be included within the scope of the appended claims.