Variable or multi-gauge cut pile tufting with backing shifting
11661694 · 2023-05-30
Assignee
Inventors
Cpc classification
D05C15/14
TEXTILES; PAPER
D05C15/22
TEXTILES; PAPER
D05C15/10
TEXTILES; PAPER
International classification
D05C15/10
TEXTILES; PAPER
D05C15/14
TEXTILES; PAPER
Abstract
A shiftable backing feed or shiftable needle assembly is utilized with a tufting machine having reciprocating needles and gauge parts for seizing or cutting yarns wherein yarn placement patterns can be utilized to tuft at different gauge densities while maintaining the same pattern sizes and appearance, and gauge parts are adapted for high density stitching.
Claims
1. A method of operating a tufting machine for forming tufted fabrics of the type comprising at least one needle bar having a series of gauge spaced needles mounted transversely across the width of the tufting machine; a yarn feed mechanism for feeding a series of yarns to said needles, the yarns being carried by said needles; a needle drive for reciprocating the yarn carrying needles through a backing material; a series of gauge parts mounted below the tufting zone in a position to cut or engage yarns carried by needles of said at least one needle bar as the needles are reciprocated into the backing material to form tufts of yarns in the backing material; backing feed rolls for feeding the backing material through a tufting zone of the tufting machine; a shifter to move at least one of the backing fabric or needles and associated gauge parts laterally with respect to the other; and a control system for controlling and synchronizing the shifter, needle drive, backing feed, and gauge parts, including the steps of the control system providing pattern control instructions to create fabrics of different gauges from the same pattern and in the forming of at least some tufts, shifting the backing fabric relative to the needles and associated gauge parts by distances other than the gauge spacing of the needles and multiples thereof in response to said pattern control instructions.
2. The method of claim 1 wherein the yarn feed mechanism is a single end yarn feed.
3. The method of claim 1 wherein the shifter is adapted to move the backing feed rolls laterally.
4. The method of claim 1 wherein the gamed gauge parts are pneumatically operated.
5. The method of claim 1 wherein the shifter is adapted to move the needles laterally.
6. The method of claim 1 wherein the needles are independently controlled for selective penetration of the backing material.
7. The method of claim 1 wherein yarns are seized on gated gauge parts having shortened necks, so that yarns are cut within 0.25 inches from their yarn pickup location.
8. A method of altering the tuft density of a yarn placement pattern for a tufting machine having a needle gauge comprising the steps of inputting a bitmap pattern file for a tufting machine pattern at a first gauge including some cut pile tufts of yarn; inputting yarn feed rates, yarn threadup information sufficient to identify the number of different yarns and the location of the different yarns with respect to specific needles, and shifting pattern; specifying the gauge at which the tufting machine tufts; specifying a second gauge for tufting the pattern; mapping the location of yarn carrying needles at the second gauge to the pattern at the first gauge; selecting yarns to tuft at the second gauge based upon said mapping.
9. The method of claim 8 wherein the gauge at which the tufting machine tufts is specified as the needle gauge which is different from the second gauge.
10. The method of claim 8 wherein the gauge at which the tufting machine tufts is specified to be equal to the second gauge.
11. The method of claim 8 wherein mapping the location of yarn carrying needles computes an applicable shifted distance that is added or subtracted from a neutral location of each needle for each penetration of the backing material.
12. The method of claim 8 wherein a rounding algorithm is applied when mapping the location of yarn carrying needles.
13. The method of claim 12 wherein the rounding algorithm is a round-to-even or round-up algorithm.
14. The method of claim 12 wherein an operator may select the rounding algorithm.
15. The method of claim 8 wherein the second gauge is greater than the needle gauge.
16. The method of claim 8 wherein the second gauge is less than the needle gauge.
17. The method of claim 8 wherein the needle gauge is a composite gauge of two needlebars.
18. The method of claim 8 wherein both a width and length of a pattern pixel may be specified, allowing rescaling in both lateral and longitudinal directions.
19. The method of claim 8 wherein selected yarns tufted in the pattern are seized on gated gauge parts and cut.
20. The method of claim 19 wherein the gated gauge parts have shortened necks so that yarns are cut within 0.25 inches from their yarn pickup location.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) 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:
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DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS
(29) Referring now to the drawings in more detail,
(30) Yarns 18 are supplied to the corresponding needles 14 through corresponding apertures in the yarn guide plate 19 from a yarn supply, not shown, such as yarn feed rolls, beams, creels, or other known yarn supply means, preferably passing through pattern yarn feed control 21 though simpler yarn feed arrangements such as roll feeds may be employed. The yarn feed control 21 interfaces with a controller to feed yarns in accordance with pattern information and in synchronization with the needle drive, shifters, yarn seizing/cutting mechanisms and backing fabric feed.
(31) The needle bar 12 may be fixedly mounted to the needle bar carrier 11 or may slide within the needle bar carrier 11 for transverse or lateral shifting movement by appropriate pattern control needle shifter mechanisms, in well-known manners. The backing fabric 35 is supported upon the needle plate 25 having rearward projecting transversely spaced front needle plate fingers 22, the fabric 35 being adopted for longitudinal movement from front-to-rear in a feeding direction, indicated by the arrow 27, through the tufting machine 10. The needle bar may have a single row of gauge spaced needles as shown, or may be a staggered needle bar with front and rear rows of needles, or may even be two separate needle bars, each with a row of needles and each being operable by needle shifter mechanisms.
(32) The needle drive mechanism, not shown, is designed to actuate the push rods 16 to vertically reciprocate the needle bar 12 to cause the needles 14 to simultaneously penetrate the backing fabric 35 far enough to carry the respective yarns 18 through the back-stitch side 44 of backing fabric 35 to form loops on the face 45 thereof. After the loops are formed in this tufting zone, the needles 14 are vertically withdrawn to their elevated, retracted positions. A yarn seizing apparatus 40 in accordance with this illustration includes a plurality of gated hooks 41, there preferably being at least one gated hook 41 for each needle 14.
(33) Each gated hook 41 is provided with a shank received in a corresponding slot in a hook bar 33 in a conventional manner. The gated hooks 41 may have the same transverse spacing or gauge as the needles 14 and are arranged so that the bill of a hook 41 is adapted to cross and engage with each corresponding needle 14 when the needle 14 is in its lower most position. Gated hooks 41 operate to seize the yarn 18 and form a loop therein when the sliding gate is closed by an associated driver, such as pneumatic cylinder 55, and to shed the loop as the gated hooks 41 are rocked.
(34) The elongated, transverse hook bar 33 and associated pneumatic assembly are mounted on the upper end portion of a C-shaped rocker arm 47. The lower end of the rocker arm 47 is fixed by a clamp bracket 28 to a transverse shaft 49. The upper portion of the rocker arm 47 is connected by a pivot pin 42 to a link bar 48, the opposite end of which is connected to be driven or reciprocally rotated by conventional looper drive. Adapted to cooperate with each hook 41 is a knife 36 supported in a knife holder 37 fixed to knife block 20. The knife blocks 20 are fixed by brackets 39 to the knife shaft 38 adapted to be reciprocally rotated in timed relationship with the driven rocker arm 47 in a conventional manner. Each knife 36 is adapted to cut loops formed by each needle 14 upon the bill of the hook 41 from the yarn 18 when gates are retracted and yarn loops are received on the hooks 41. A preferred gated hook assembly is disclosed in U.S. Pat. No. 7,222,576 which is incorporated herein by reference.
(35) It can be seen in
(36) A variety of techniques can now be practiced that make it possible to operate a backing shifting apparatus with cut pile, or cut/loop, gauge parts in a practical fashion. Generally, by using a relatively large gauge needle bar, such as one-half to ⅜ths gauge, and preferably one-quarter gauge (¼.sup.th inch needle spacing), and tufting at a stitch rate that is at least about two times the gauge (so tufting a ¼.sup.th gauge needle bar at a stitch rate of at least about 8 stitches per inch), and keeping the lateral shifting of the backing within a gauge width (so tufting a ¼.sup.th gauge needle bar without shifting the backing fabric more than ¼.sup.th inch to the left or right), a cut pile greige may be produced. Furthermore, the patterning techniques used for scaling patterns may be employed to determine the operation of gated hooks in the creation of cut/loop fabrics, and the cut/loop or cut pile hooks may be configured to co-operate with either a single large gauge needle bar, or a graphics configuration with two large gauge needle bars.
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(38) The tufting machine controller 26 receives and stores such programmed pattern instructions or information for a series of different carpet patterns. These pattern instructions can be stored as a data file in memory at the tufting machine controller itself for recall by an operator, or can be downloaded or otherwise input into the tufting machine controller by the means of a digital recording medium such as a USB flash drive, direct input by an operator at the tufting machine controller, or from a network server via network connection. In addition, the tufting machine controller can receive inputs directly from or through a network connection from a design center 40. The design center 40 can include a separate or stand-alone design center or work station computer 41 with monitor 42 and user input 43, such as a keyboard, drawing tablet, mouse, etc., through which an operator can design and create various tufted carpet patterns. This design center functionality also can be located with or at the tufting machine or can be much more remote from the tufting machine.
(39) An operator can create a pattern data file or graphic representations of the desired carpet pattern at the design center computer 41, which will calculate the various parameters required for tufting such a carpet pattern at the tufting machine, including calculating yarn feed rates, pile heights, backing feed or stitch rate, and other required parameters for tufting the pattern. These pattern data files typically then will be downloaded or transferred to the machine controller, to a thumb drive or similar recording medium, or can be stored in memory either at the design center or on a network server for later transfer and/or downloading to the tufting machine controller. Further, for design center located work stations and/or where the machine controller has design center functionality or components programmed therein, it is preferable, although not necessarily required, that the design center 40 and/or machine controller 26 be programmed with and use common Internet protocols (i.e., web browser, FTP, etc.) and have a modem, Internet, or network connection to enable remote access and trouble shooting.
(40) The yarn feed system 10 comprises a yarn feed unit or attachment 50 that can be constructed as a substantially standardized, self-contained unit or attachment capable of being releasably mounted to and removable from the tufting machine frame 16 as a one-piece unit or attachment. This enables the manufacture of substantially standardized yarn-feed units capable of controlling the feeding of individual yarns to a predetermined number or set of needles of the tufting machine.
(41) The yarn feed unit 50 further includes a series of yarn feed devices 70 that are received and removably mounted within the housing 56 of the yarn feed unit. The yarn feed devices engage and feed individual yarns to associated needles of the tufting machine for individual or single end yarn feed control, although in some configurations, the yarn feed devices also can be used to feed multiple yarns to selected sets or groups of needles. For example, in a machine with 2,000 needles, each yarn feed unit could control two or more yarns such that 1,000 or fewer yarn feed units can be used to feed the yarns to the needles. Such multiple yarn configurations usefully create mirrored patterns or patterns with multiple repeats across the width of the greige. Each of the yarn feed devices 70 includes a drive motor 71 that is received or releasably mounted within a motor mounting plate 72, mounted to the frame 51 of the yarn feed unit 50 along the front face or side 59 of the housing 56. The motor mounting plates 72 include a series of openings or apertures 73 in which a drive motor 71 is received for mounting.
(42) In some cases, yarns may be directed from the yarn feed device 70 to needles 14 in a direct fashion. In other cases, a series of yarn feed tubes are extended along the open interior area 62 of the yarn feed unit housing 56. Each of the yarn feed tubes 105 is formed from a metal such as aluminum or may be formed from various other types of metals or synthetic materials having reduced frictional coefficients so as to reduce the drag exerted on the yarns. The yarn feed tubes 105 extend from an upper or first end 106 adjacent a yarn guide plate 107 mounted to the front face or surface of the housing 56, and extend at varying lengths, each terminating at a lower or terminal end 108 adjacent a drive motor 71.
(43) The system controller communicates with each of the yarn feed controllers via the network cables 173,174 and 176,177, with feedback reports being provided from the yarn feed controllers to the system controller over the first, feedback or real-time network (via network cable 173) so as to provide a substantially constant stream of information/feedback regarding the drive motors 71. Pattern control instructions or motor gearing/ratio change information for causing the motor controllers 152 to increase or decrease the speed of the drive motors 71 and thus change the rate of feed of the yarns as needed to produce the desired pattern step(s), are sent to the control processors 152 of the yarn feed controllers 140 over the pattern control information network cables 174.
(44) The system controller further can be accessed or connected to the design center computer 40 through such communications package or system, either remotely or through a LAN/WAN connection to enable patterns or designs saved at the design center itself to be downloaded or transferred to the system controller for operation of the yarn feed unit. The system design center computer further has, in addition to drawing or pattern design functions or capabilities, operational controls that allow it to enable or disable the yarn feed motors, change yarn feed parameters, check and clear error conditions, and guide the yarn feed motors. As discussed above, such a design center component, including the ability to draw or program/create patterns also can be provided at the tufting machine controller 26, which can then communicate the programmed pattern instructions to the system controller, or further can be programmed or installed on the system controller itself. Thus, the system controller can be provided with design center capability so as to enable an operator to draw and create desired carpet patterns directly at the system controller.
(45) In operation of the yarn feed control system 10, in an initial step, the system controller 165 of the yarn feed controller system 10, and the tufting machine controller 26 are powered on, after which the tufting machine controller proceeds to establish existing machine parameters such as reciprocation of the needles, backing feed, bed rail height, etc. The operator then selects a carpet pattern to be run on the tufting machine. This carpet pattern can be selected from memory, stored at a network server from which a carpet pattern data file will be downloaded to internal memory of the tufting machine or system controller, or stored directly in memory at the tufting machine controller or system controller.
(46) Alternatively, the pattern or pattern data file can be created at a design center. The design center calculates yarn feed rates and/or ratios, and pile heights for each pattern step, and will create a pattern data file, which is then saved to memory. After the desired carpet pattern has been selected, the pattern information typically is then loaded into the system controller 165 of the yarn feed control system 10. Alternatively, as explained below in connection with the rescaling methods the operator can scale the desired carpet pattern. The operator then starts the operation of the yarn feed control system, whereupon the yarn feed devices 70 pull and feed yarns from a creel (not shown) at varying rates according to the programmed pattern information, which yarns are fed to puller rolls 22, which in turn, feed the yarns directly to the individual needles 13 of the tufting machine 11. The system controller sends pattern control instructions or signals regarding yarn feed rates or motor gearing/feed that are rationed to the rotation of the main drive shaft of the tufting machine, individual yarns to the yarn feed controllers 140 via control information network cables 174. Such pattern control instructions or signals/information are received by the control processors 152, which route specific pattern control instructions to the motor controllers or drives 153, which accordingly cause their drive motors 71 to increase or decrease the feeding of the yarns 12, as indicated at 221, as required for pattern step.
(47) As further indicated at 223, the motor controllers monitor each of the drive motors under their control and provide substantially real-time feedback information 224 to the system controller, which is further receiving control and/or position information regarding the operation of the main shaft and the backing feed from the tufting machine controller that is monitoring the main shaft and backing feed encoders, needle bar shift mechanism(s) and other operative elements of the tufting machine. This feedback information is used by the system controller to increase or decrease the feed rates for individual yarns, as needed for each upcoming pattern step for the formation of the desired or programmed carpet pattern. After the pattern has been completed, the operation of the yarn feed control system will be halted or powered off, as indicated in 225.
(48) Turning now to
(49) Master controller 42 preferably interfaces with machine logic 63, so that various operational interlocks will be activated if, for instance, the controller 42 is signaled that the tufting machine 10 is turned off, or if the “jog” button is depressed to incrementally move the needle bar, or a housing panel is open, or the like. Master controller 42 may also interface with a bed height controller 62 on the tufting machine to automatically effect changes in the bed height when patterns are changed. Master controller 42 also receives information from encoder 68 relative to the position of the main drive shaft 17 and preferably sends pattern commands to and receives status information from controllers 76, 77 for backing tension motor 78 and backing feed motor 79 respectively. Said motors 78, 79 are powered by power supply 70. Finally, master controller 42, for the purposes, sends ratiometric pattern information to the servo motor controller boards 65. The master controller 42 will signal particular servo motor controller board 65 that it needs to spin its particular servo motors 31 at given revolutions for the next revolution of the main drive shaft 17 in order to control the pattern design. The servo motors 31 in turn provide positional control information to their servo motor controller board 65 thus allowing two-way processing of positional information. Power supplies 67, 66 are associated with each servo motor controller board 65 and motor 31.
(50) Master controller 42 also receives information relative to the position of the main drive shaft 17. Servo motor controller boards 65 process the ratiometric information and main drive shaft positional information from master controller 42 to direct servo motors 31 to rotate yarn feed rolls 28 the distance required to feed the appropriate yarn amount for each stitch.
(51) When adapted for use with a reciprocating needleplate as in U.S. Ser. No. 15/721,906 [PCT/US2017/054683], the master controller also has to provide signals to control the additional axis for the rotation of the cam in a fashion that is essentially rotating a cam profile through a single revolution for each tufting cycle. The cam profile and speed of rotation determines the longitudinal movement imparted to the needleplate and the speed of movement.
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(54) Advantageously, and different from prior usage in broadloom tufting machines, the backing assembly can be precisely shifted for substantial distances, typically on the order of 1 to 2.5 inches in each direction from center. This provides tufting machine with great versatility. While it is apparent that a quarter gauge tufting machine may simulate a ⅛.sup.th gauge tufting machine by simply doubling the number of needle bar reciprocations and shifting the backing by ⅛.sup.th inch, precision backing shifting and provides numerous less readily appreciated advantages. patterning advantages.
(55) For instance, a ⅛.sup.th gauge tufting machine can very nearly imitate a 1/10.sup.th gauge tufting machine, although all stitches may not appear in perfectly aligned rows. By way of example, a ⅛.sup.th gauge machine will most commonly tuft at a stitch rate of about 8 stitches per inch, thereby placing 64 stitches in a square inch of backing. A 1/10.sup.th gauge machine will most commonly tuft at about 10 stitches per inch with a resulting 100 stitches being placed in a square inch of backing. However, by increasing the stitch rate of a ⅛.sup.th gauge tufting machine equipped with backing shifter and reciprocating needle plate to 12.5 stitches per inch, a stitch density of 100 stitches per square inch. In cases where the stitch rate is being increased by a multiple of the gauge of the backing shifter and reciprocating needle plate equipped machine, there may be a perfect pattern alignment. In other cases, the stitches may not align in exact longitudinal rows as there may be some rounding adjustments in changing stitch densities and locations.
(56) The failure to align in exact longitudinal rows may be perceived as an advantage in some tufting applications. For instance, solid color shifting is used when manufacturing solid color carpets to break up any streaks or irregularities in the yarns that might otherwise be noticeable. Residential solid color carpets are sometimes sewn on 5/32nds or 3/16.sup.th inch gauge staggered needle bars with two rows of needles. These needle bars require shifts of 0.375 or 0.3125 inches for the streak break-up shifting. With a backing shifter and reciprocating needle plate equipped tufting machine, shifts of as little as 0.10 inches, and perhaps 0.05 inches, could be employed. The smaller shifts permit greater machine speed and require less lateral yarn on the backstitch that is effectively lost to effective use.
(57) It was initially thought that the use of a reciprocating support and backing shifter would not be practical with cut pile fabrics because, as reflected in prior art
(58) In practice, it seems there are two effective options for cut pile operation with backing shifting. In one fashion, a relatively large gauge needle bar for carpet, such as ¼.sup.th gauge, is used (or possibly two ¼.sup.th gauge needle bars in a graphics arrangement. The use of a relatively large gauge facilitates the operation of the cutting apparatus, as 1/12.sup.th gauge single needlebar cut pile is extraordinarily demanding, and even 1/10.sup.th gauge cut piles may limit the choice of yarns to relatively compact size and material choices. With a needle spacing of ¼.sup.th inch, the backing fabric can be shifted within the width of the gauge without pushing the yarns across a needle plate finger 22 and with this limited range of lateral shifting it is not even generally necessary to reciprocate the needle plate fingers 22 so that the reciprocating assembly can be stopped and the tufting machine may be operable at slightly higher speed.
(59) The second option is to permit the customary lateral shifting of the backing for cumulative distances exceeding the gauge width and reciprocating the needle plate fingers 22 and pulling the tufted cut pile greige up and away from the gauge part action as soon as practicable. However, as reflected in
(60) The result is that a hook 141 used in high stitch rate tufting may be carrying significantly more than four loops of yarn before the loops are brought into the cutting action. When too many yarn loops are carried, the tufting machine tends to bind, making it more difficult to laterally shift the backing. Accordingly, the technique of shortening the distance on the hook 141 to the cutting action to ensure that less than eight loops of yarn are being carried is desirable. Ideally, the yarns will be cut before the lateral movement between the needle and backing has moved more than about ¼.sup.th inch, or the gauge spacing of the relatively large gauge needle bar.
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(65) As shown in
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(⅕)/(⅛)=(8/5)=1.6
This would round to 2, so long as an unusual rounding method was not being employed.
(68) The stitch set up has a default rate entry for stitches that are left on the back of the greige, tacking interval in inches and a tack rate for the yarn feed amount to supply for a tacking stitch. The front offset is simply the row of pattern that the tufting machine will start on and the actual stitch offset can be calculated automatically by the tufting machine based upon the calculated stitch rate and the needle bar offset that is provided in the machine configuration, for example in the exemplary operator screen of
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(73) The particulars for stitches are confirmed 207, and with single or graphics needlebar yarn placement, this will typically include a yarn feed rate for stitches that are removed from the backing, a yarn feed increment for tacking stitches, and a tacking interval to insure that unused yarns remain bonded to the backing fabric. An offset is specified, which in the illustrated
(74) Yarn placement practiced by standard tufting machines in single needle bar, as in U.S. Pat. No. 8,141,505 and continuations, or in graphics configurations, as in U.S. Pat. No. 9,663,885 and continuations, is rarely precisely scalable. Certainly, a fifth gauge (⅕.sup.th inch needle spacing) tufting machine can scale precisely to tuft at tenth gauge, however, a tenth gauge single or graphics needlebar machine cannot precisely scale to twelfth gauge—so some approximation is implemented. The pattern is processed to map the pattern pixels to the yarns that the needles will be tufting in the rescaled pattern 209. ICN tufting machines are also not precisely scalable apart from similar doubling of the machine gauge. The pattern rescale feature effectively maps the pattern at the size and tuft density that it was designed to the same size and a newly specified tuft density, preferably using an algorithm similar to that explained in connection with
(75) The ability to rescale patterns is of increasing importance in a tufting industry driven to operate at maximum efficiency, and numerous applications exist for rescaled patterns. In one example, if a tufting facility has both tenth and twelfth gauge graphics tufting machines and all of the twelfth gauge machines are operating at full capacity while the tenth gauge machines are only operating for a single daily shift, there exists the possibility to rescale some twelfth gauge patterns to tenth gauge and obtain extra production. The resulting rescaled tenth gauge patterns will have the same appearance but a reduced tuft density and resulting cost. The possibility also exists to scale tenth gauge patterns to be tufted on a twelfth gauge machine in a fashion that closely approximates tenth gauge appearance and density. Thus, pattern rescaling allows tufting mills to operate at higher capacity without the necessity of changing out all of a tufting machine's gauge parts and reconfiguring the machine. A tufting machine with variable backing shifting can with a fair degree of precision emulate the gauge and appearance of shifted single needle bar or graphics tufting machines of a variety of gauges.
(76) Also, to optimize carpet costs, a fabric with the same appearance can be offered at a variety of densities that can be selected according to their intended use. So, for instance a residential use or even use in a hotel room may be entirely suitable with a lower density than carpet designed for use in a hotel lobby or hallway. Similarly, a manufacturer can offer carpet tiles of the same pattern in different densities at different price points.
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(78) Algorithmically, the tufting machine knows from the original pattern that the first 0.5 inch position is dark. Accordingly, at the new gauge the tufting machine calculates the physical needle position based upon the machine gauge and shift and if the needle is between 0.0 and 0.5 inches in location and carrying dark yarn, then a stitch will be tufted. So, in the example of
(79) In each case, the rescaling determines which longitudinal row of stitching is being addressed and the lateral displacement of each needle based upon physical gauge and the number of shifted steps at the specified sewing gauge. In rescaling from a tenth gauge pattern to a twelfth gauge density in a four-color thread up, on a tufting machine having either a single tenth gauge needle bar or a composite tenth gauge graphics machine with two fifth gauge needle bars it will be realized that a great deal of approximation is required. So for instance, in the four color thread up at tenth gauge, a pattern might be tufted with 40 longitudinal stitches per inch, with four sequential shifted stitches needed for each line of tufts in the pattern, but at twelfth gauge would adjust to 48 stitches per inch. As a result, the fifth line of tufts in the pattern would be the 21-24th reciprocations in the tenth gauge pattern, but the 25-28.sup.th reciprocations in the twelfth gauge pattern. In the intermediate longitudinal stitching, the alignment would be inexact and some rounding is required.
(80) The same rounding issues occur with respect to the lateral position of the needles. The inexact position could be a result of tufting on a tenth gauge machine with only shiftable needles, or tufting on a variable backing shifting machine with a tenth gauge needle bar assembly. In either case, not all of the needles will align precisely on twelfth gauge. Instead, the lateral position of needle must be computed and mapped to the corresponding element of the tenth gauge pattern. When the tenth gauge needles on a needle shifting machine are laterally shifted four positions, or 0.4 inches, and cover four lateral pixels in a line of the pattern, they very nearly transverse the positions that are occupied by five lateral pixels in a twelfth gauge pattern. The calculation of the needle position evaluates the position of the needle at its neutral location, so the needle in the tenth position on a fifth gauge needle bar is at 2.0 inches. This is the physical machine location. Assuming the sew gauge of the needle bar is also fifth gauge, when the needle is shifted three steps to the right it will be at 2.6 inches. If the scale gauge is twelfth gauge, then the 2.6 will be divided by 1/12 and the needle will be in pixel position 31.2 of the twelfth gauge pattern. This leads to the need to determine whether this should be treated as position 31 or 32 for the purposes of tufting, and as might be expected, 31 is generally the best approximation. Even on a tufting machine with variable backing shifting, where shifting could be applied at optimal lateral increments, a problem exists tufting twelfth gauge fabric on a tenth gauge needle bar because there are only ten needles in a width where twelve stitches should be tufted. Approximation is required to produce the best fit of the physical stitch locations to the rescaled pattern.
(81) Accordingly, after computing the physical needle location relative to the pattern a rounding mechanism is applied. The preferred rounding algorithms round fractions to the nearest integer with either mid-to-even (i.e., both 1.5 and 2.5 round to 2.0) or mid-away-from zero (i.e., 1.5 rounds to 2.0 and 2.5 rounds to 3.0). Other alternatives such as round up (i.e., both 2.2 and 2.8 round to 3.0) or round down (i.e., both 2.2 and 2.8 round to 2.0) may be desirable in some instances. Quirks of individual patterns may warrant experimentation with rounding to produce the most aesthetically suitable fit.
(82) The result is the use of conventional pattern information together with a specified sew gauge and scale gauge to scale patterns from one stitch density to another while maintaining the optical integrity of the pattern. Rescaling in this fashion allows designers to create patterns of the size they intend, and the size will not be distorted when the pattern is adapted to a variety of tufting machines. Designs will be better realized and tufting machines may be used more adaptably by the implementation of these rescaling design techniques.
(83) Numerous alterations of the structure herein described will suggest themselves to those skilled in the art. It will be understood that the details and arrangements of the parts that have been described and illustrated in order to explain the nature of the invention are not to be construed as any limitation of the invention. All such alterations which do not depart from the spirit of the invention are intended to be included within the scope of the appended claims.