Abstract:
A process for the production of a face-to-face carpet fabric on a double pile loom having at least two filling insertion planes, uses filling yarns, stuffer warp yarns, and chain warp yarns to form two back cloths. The filling yarns are inserted into each back cloth as back fillings and inner fillings. Groups of chain warp yarns, individual yarns of which between their respective last binding to an inner filling and the succeeding last binding to a back filling form a holding length, are assigned to each back cloth. All patterning pile loops are stretched over back fillings. and the pattern repeat of a group of chain warp yarns is selected to be greater than six. The holding lengths of a chain warp yarn extend over at least three filling insertion cycles.

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to a process for the production of a face-to-face carpet fabric on a double pile loom having at least two filling insertion planes, using filling yarns, stuffer warp yarns, and chain warp yarns to form the back cloths in the form of a bottom cloth and a top cloth, as well as frames of pile yarns per warp course to form the patterned pile layer between the two back cloths, whose respectively non-patterning pile yarns are tied into the back cloths of the top and/or bottom cloths largely under tension and whose respectively patterning pile yarns are stretched alternately between the filling yarns of the top cloth and the bottom cloth; whereby the filling yarns within a pattern repeat in both back cloths are inserted in at least two different filling insertion planes, at least once as a back filling outside the stuffer warp and at least once as an inner filling inside the stuffer warp; whereby in each back cloth, groups of chain warp yarns are fed according to a prescribed pattern repeat, forming weaving sheds, whereby the chain warp yarns of a group staggered within a pattern repeat in the warp direction, loop in harmonizing weaving sequences outside the back fillings and inner fillings with respect to a back cloth, whereby each chain warp yarn of a group—within a weaving sequence—between its respective last binding to an inner filling and the subsequent last binding to a back filling is guided over several filling insertion cycles behind the inner fillings, forming a holding length, and then inside an inner filling in a compensating length, forming a weaving shed, and whereby the pattern repeats of the chain warp yarns are designed so that the tie-in length of the chain warp yarns of a group within each pattern repeat is compensated for between them. 
     A process of this type is known from EP 628 649 A1. It shows, for example, the customary state of the art up to now. The chain warps are arranged regularly in groups of two chain warp yarns. Each group is assigned respectively to a warp course. Each warp course has respectively such a group of chain warp yarns, at least one stuffer warp yarn, and a frame of pile yarns. 
     A group of chain warp yarns is characterized in that it holds within its pattern repeat all the back fillings and all the inner fillings in its effective area on the stuffer warp, which is tied in under tension, and optionally on the dead piles, which are tied in under tension. 
     It is customary thereby to guide the individual chain warp yarns of a group within a pattern repeat of a specific weaving sequence by means of shafts during the formation of the weaving shed. Because only a single warp beam is available as a rule for the chain warp yarns on a double pile loom, the chain warp yarns have been woven in regularly according to a uniform weaving sequence, so that the tie-in length and thus the tension of all chain warp yarns of a group can be held constant within a pattern repeat. 
     Those skilled in the art regularly focus on not exceeding a certain pattern repeat size and a certain temporary difference in consumption in order to ensure that the tension of the chain warp yarns running from a single warp beam is uniform. In practice, a so-called two-course rib weave (cf. Hans Osswald, “Die Teppichindustrie” 1965, Melliand Textilberichte, Heidelberg, p. 112, FIGS. 176 and 177) was used regularly on face-to-face carpet looms for the two-shuttle production of the backing. In this two-shuttle three-shot weave with a pattern repeat of six filling insertion cycles, in one of the two back cloths a chain warp yarn regularly extended diagonally from one inner filling to a back filling inserted four courses later and from there back again to an inner filling in the two immediately succeeding courses. 
     With this type of tie-in, the intermediate pile binding point was drawn very tightly to the previously formed back cloth by means of the diagonal section, let us call it the “holding length”, of the chain warp yarn. The shorter section guided through the back cloth, which we call the “compensating length,” then fixed the position of the chain warp yarn in the back cloth, so that when the chain warp yarn tension slackened in the shed area, the finished fabric could not loosen again. 
     Such a weave already ensures that the quality of the tie-in of the pile legs will be serviceable. There are specific limits to the filling density, however. 
     The asymmetrically tied-in chain warp causes the fillings carrying and supporting the pile loops to be deflected in the warp direction along the stuffer warp or along the dead piles. The exit direction of the pile loops regularly deviates by up to 10° and more from the vertical to the back cloth. Such an inclined position of the pile legs is regularly the reason that certain required resilience properties can only be ensured by increasing the pile density and/or by raising the pile height. Both measures for ensuring the desired resilience properties require a considerable additional expense for pile material. The costs for a carpet produced in this manner are correspondingly high. 
     A further disadvantage of this asymmetrical weave of the back cloth is that the recovery power of the pile cover under partial severe loading—for example by the feet of pieces of furniture—is insufficient. 
     Intensive brushing processes and the like may be required to remove partial pressure points. Usually, however, such pressure points leave permanent and clearly visible deformations in the pile surface. 
     Due to the inclined position of the pile legs, carpets woven in this manner cannot be lined up next to one another for contract use. The differing reflection angles of the incident light, which are caused as a function of the respective weave direction, give an observer the impression that there are color defects. 
     In order to limit the inclination of the pile angles, attempts have already been made (cf. Osswald, p. 112) to increase the thickness of the back cloth by inserting intermediate fillings that separate the stuffer warp from the dead pile strand. It was also hoped that this would enable the deflection of the fillings on the back cloth to be reduced. 
     This measure, with a specific arrangement of the fillings inserted successively or simultaneously in the area of a pattern repeat, had only limited success as far as the orientation of the pile legs was concerned (cf. DE 574 920). 
     There was a distinct increase in the quantity of material used. The pile density was not increased further by these measures. 
     In EP 628 649 A1 referred to initially, a solution to this problem was attempted in that other filling yarn arrangements were used, while keeping the intermediate filling. The chain warp yarns were guided over the filling yarns in such a way that they loaded the filling yarns approximately symmetrically in the warp direction. The filling yarns—inserted as back filling, intermediate filling, or inner filling—are this held largely immobile in the warp direction. The size of the pattern repeat was maintained in the customary manner with four filling insertion cycles. This led to an increased yarn material requirement for chain warp yarns. The pile density, measured in the warp direction, also remained clearly limited in this case. Carpets produced in this manner frequently had to be placed in lower quality categories due to inadequate density. 
     For the said reasons, the production of very dense pile goods was normally previously reserved for the single-shuttle weaving technique, in which not every pile loop is tied to a back filling. Much lower productivity was accepted. 
     EP 922 799 A2 shows an attempt to increase pile density even using a two-shuttle method. In each back cloth. the top cloth and the bottom cloth, the pile loops in a warp course are stretched alternately on a back filling and then on an intermediate filling—which is inserted between the stuffer warp and the dead piles. The pattern repeat of the chain warp yarns extends over eight courses. The initially defined holding length is formed in each weaving direction in three successive courses. 
     The goods achievable using intermediate fillings and back fillings as pile carrying fillings are of lower quality. The appearance of the back of the carpet differs considerably from the appearance of the pile side. The pile loops at the borders of the pattern, which are only bound via an intermediate filling, have a distinctly lower pull-out resistance. During the usual care with a vacuum cleaner, these pile loops are gradually detached from their weave and removed. The final result of this is unclear pattern contours. A higher pile density is only achieved to a limited extent. 
     In Belgian Patent 675 494, an attempt was made to achieve a greater pile density even when all the pile loops are stretched over a back filling, using a similar basic weave of the chain warp. Here, the dead piles were guided under tension on the back of the bottom cloth and after the weaving procedure and the separation of the face-to-face carpet fabric, were scratched off from the back of the bottom cloth in the pile plane. These so-called “scratch-off goods” are known to be of unsatisfactory quality. 
     It is an object of the present invention to provide a process for fixing the back cloths with dead piles distributed in the top cloth and bottom cloth and tied in by means of chain warp yarns, which process on the one hand ensures a largely vertical tie-in of the pile legs in the back cloths, enables a carpet fabric to be produced with a high pile density, and ensures that the quantity of material used in the area of the back cloths can be distinctly reduced. 
     It is furthermore an object of the invention to ensure, by means of the measures found, that the resilience properties of the carpet are the same or better, the quantity of pile material used being reduced. 
     SUMMARY OF THE INVENTION 
     This objective is accomplished by a process in accordance with which the combination of the designated process steps prevents back fillings from being deflected in the warp direction relative to the inner fillings. It prevents the points of intersection of two chain warp yarns of two groups always being positioned in one and the same transversal area of the back cloth in adjacent warp courses during the shed treadle motion. 
     Surprisingly, the combination enables the pile density in the warp direction to be increased by up to 30%, depending on the weave variant selected and the thickness of the filling yarns used. 
     The pile loops project regularly from the back cloth largely vertically and are stable and securely supported in this position. This leads to excellent resilience properties in the finished carpets. 
     The recovery power of the pile surface after partial severe loading is optimized. 
     The varying reflectance of the colors as a function of weave direction is distinctly reduced. The use of pile carpet for contract carpeting is no longer generally excluded. 
     Depending on the weave selected in the scope of the invention, chain warp material can be saved in orders of magnitude of between 10 and 25%. 
     A saving of pile material results from the fact that a lower pile height can be selected to achieve the same resilience properties, due to the vertical pile tie-in. 
     In addition to said advantages, another embodiment has the additional advantage that the pile binding points on the carpet back are distributed uniformly and free of lines, especially when 4 chain warp yarns are used per group. The carpet back resembles the classical hand-knotted carpet and has the additional advantages of the taut stuffer warp. 
     In contrast to known basic weaves, the pile density was able to be increased with a relatively small pattern repeat by up to 15 pile rows/dm, and in variants with a substantially larger pattern repeat by up to more than 100 pile rows/dm. 
     Depending on the length of the pattern repeat, the modification according to a further embodiment enables a distinct saving (up to over 25%) of chain warp material while maintaining the classical back appearance of a carpet—analogous to the conventional 2/2 rib weave. Here too it is possible to increase the pile density considerably. 
     In accordance with an advantageous embodiment of the invention, a group of the chain warp yarns is suitably distributed over 3 to 4 warp courses. Again there is a high pile density and a distinct saving of chain warp material. 
     The advantages of the weave according to a further embodiment are that in addition to an attractive saving of chain warp material, improved pile position, and improved pile density, high wear resistance can be ensured, even in the unbound state. 
     In accordance with another embodiment, a variant is defined that is important in particular for working with three overlapping filling insertion planes. The most essential advantages are a high saving of chain warp material while maintaining high wear resistance of the carpet. 
     Yet a further advantageous embodiment describes a second basic method to achieve the object of the invention in a limited area of the pattern repeat, which has the same results as those described in relation to the initial embodiment described above. 
     A still further embodiment of the invention is directed to an almost equivalent method to the first embodiment described herein. The pile loops do not tie over a back filling in every case. The pattern of the front face of the carpet is not reproduced completely on the back, however. This weave is desirable where the demands on the quality of the carpet are not particularly high and the price is to be kept correspondingly low. 
     The invention is explained in greater detail below by means of examples with reference to the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a sectional view through a face-to-face carpet fabric along the warp direction; 
     FIG. 1 a  is a top view of the face-to-face carpet fabric according to FIG. 1; 
     FIG. 2 is a schematic weave design of one of the back cloths, a top cloth, with an irregular weave pattern of the chain warp yarns; 
     FIG. 3 is a representation as in FIG. 2 with a regular pattern repeat; 
     FIG. 4 is a schematic weave design with chain warp yarns binding irregularly in long lengths in two adjacent warp courses, 
     FIG. 5 is a representation as in FIG. 2 with regularly symmetrically binding chain warp yarns arranged in pairs in two adjacent warp courses; 
     FIG. 6 is a representation as in FIG. 5 with back and inner fillings bound in pairs; 
     FIG. 7 is the representation of a weave pattern with alternating tabby weave over each three back- or inner fillings; 
     FIG. 8 is a representation as in FIG. 7 with an extended tabby weave in the area of the back- and inner fillings, 
     FIG. 9 is a representation of a top cloth with an additional intermediate filling and regular guiding of the chain warps and a distribution of the chain warps on two warp courses; 
     FIG. 10 is a representation according to FIG. 9 with a modified arrangement of the intermediate fillings; 
     FIG. 11 is a representation as in FIG. 9 with a third variant of the arrangement of the intermediate fillings, whereby the group of chain warp yarns consists of four chain warp yarns assigned to two warp courses; 
     FIG. 12 is a representation of a top cloth with the filling arrangement of FIG. 11, whereby the chain warp yarns loop around the back- and intermediate fillings in lengths in tabby weave and in the following length bind the intermediate and inner fillings; 
     FIG. 13 is a representation as in FIG. 7, whereby an additional intermediate filling is provided; 
     FIGS. 14 and 15 are modifications of the weave of FIG. 13; 
     FIG. 16 is a diagram of the paired filling weave for back fillings on a top cloth as in FIGS. 1 and 2; 
     FIG. 17 is a diagram when tabby weave is used on the back fillings on a top cloth; 
     FIG. 18 is a weave diagram with tie-in of the chain warp yarns asymmetrically under tension, using their gripping action in the finished fabric of a top cloth; and 
     FIGS. 19 to  22  show further weave examples with pile loops interlacing unevenly with back-, intermediate, or inner fillings. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The face-to-face carpet fabric shown in FIG. 1 consists of a top and a bottom back. cloth, top cloth OW and bottom cloth UW, and of patterning pile yarns PM alternating regularly between the top and bottom back cloth, which pile yarns are separated in the riddle between top cloth OW and bottom cloth UW after the weaving procedure. 
     Each of back cloths OW, UW contains stuffer warp yarns FK running in the warp direction and non-patterning pile yarns oriented parallel to them that are designated below as dead piles PT or dead pile strand. These two yarn groups FK, PT are held on the outside by back fillings SR and on the inside by inner fillings SI. The position of the back fillings SR. and inner fillings SI is fixed by chain warp yarns B (B 1 , B 2  in FIG.  1 ). Chain warp yarns B are arranged in groups. The size of the group varies normally between two (e.g. B 1 , B 2 ) and four (e.g. B 13  to B 16 ) chain warp yarns B. The number of chain warp yarns B in a group is governed by the minimum number of yarns needed to bind all the back fillings SR and inner fillings SI to the back cloth once each within a pattern repeat R. (Adjacent groups can also augment one another with respect to one or more binding points.) 
     In one pattern repeat of chain warp yarns B we find as a rule at least one holding length Y and at least one compensating length Z. 
     The first holding length Y 1  of chain warp yarn B 1  of the B 1 , B 2  group shown in FIG. 1 begins after inner filling SI shown above left. It encloses upper left back filling SR 1  and then second back filling SR 2 . In the subsequent first compensating length Z 1 , this chain warp yarn B 1  is guided to subsequent inner filling SI and from there in the same plane to the next inner filling SI. If all chain warp yarns B 1 , B 2  of the group were to bind with the same tie-in length, the pattern repeat of a group. would already be ended here. 
     In the present case, however, second chain warp yarn B 2  binds differently. It alternates respectively from a filling yarn lying opposite the first-named filling yarn pair to the net filling yarn, which is inserted three filling insertions later. This chain warp yarn B 2  brings the necessary longitudinal tension to the backing by means of another holding length Y 2  and ensures that back fillings SR that carry pile loops and inner fillings SI that guide pile loops, are drawn against one another so tightly that the pile loops are prevented from lying at an angle. 
     In order to ensure that the tie-in length of both chain warp yarns B 1 , B 2  remains the same within a pattern repeat, both chain warp yarns B 1 , B 2  reciprocally change their weave twice within a pattern repeat R—optionally in a special change length W. As a result, each chain warp yarn B 1 , B 2  has two different holding lengths Y 1 , Y 2  and also two different compensating lengths Z 1 , Z 2 . 
     In both weaves, holding length Y 1 , Y 2  and also respective compensating length Z 1 , Z 2  extend over three filling insertion cycles. Because of change lengths W, the total pattern repeat amounts to e.g. 20 or 28 filling insertion cycles. After three or five fillings respectively, two chain warp yarns B 1 , B 2  change regularly from the back plane inwards or vice versa. 
     The size of pattern repeat R and individual binding lengths X 1 , X 2  (FIG. 2) should be selected thereby such that a temporary slackening of individual chain warp yarns B 1 , B 2  of a group while being doffed from the warp beam can also be avoided with certainty. The tension of chain warp yarns B should be monitored before entry into the shed-forming zone and must-not fall below a value of 2 to 4 N. 
     In the present case, chain warp yarns B 1 , B 2  of the group can be distributed over two adjacent warp courses K 1 , K 2  (FIG. 1 a , FIG.  5  and FIG.  6 ). In spite of this distribution, they hold the relatively voluminous back fillings SR against stuffer warp FK and inner fillings SI securely enough against dead pile strands PT in the respective back cloth OW or UW. 
     In FIGS. 2 to  8  below, weave designs are shown based on top cloths OW in which the back cloth only has back fillings SR and inner fillings SI. 
     FIGS. 9 to  15 , in contrast, show back cloths, for example of top cloths OW, that also have intermediate fillings SZ (SZ 1 , SZ 2 , SZ 3 ) between the taut stuffer warp FK and the voluminous dead piles PT. 
     FIG. 2 shows a weave as was also described in relation to FIG.  1 . Only change lengths W are positioned and formed somewhat differently here. Special change lengths W are provided in FIG. 2 in addition to holding lengths Y 1 , Y 2  and compensating lengths Z 1 , Z 2 . Change lengths W can also be assigned to compensating lengths Z 1 , Z 2 . 
     The weave variant of FIG. 3 shows a regular paired interlacing of back fillings SR and inner fillings SI. It achieves the object of the invention by very simple means. After the first tied-in back filling SR, chain warp yarns B 3 , B 4  in the first warp course maintain their position in the weaving shed until the second back filling of this pair is beaten up. Holding length Y 3  brought from the last inner filling SI before the paired binding of the back fillings is gripped in the already finished fabric such that no elastic component can become active in this yarn length and deflect the last inserted back filling SR laterally. The pile legs are not deflected and stand almost vertical in the back cloth. In the adjacent warp course, a further pair of chain warp yarns B 3 ′ and B 4 ′ of this group binds staggered with respect to the first pair by two courses. 
     The weave design of FIG. 4 shows larger lengths with different weave designs of chain warp yarns B 5 , B 6 , B 7 , B 8 . Two chain warp yarns B 5 , B 6  bind regularly in pairs over back fillings SR or inner fillings SI thereby. 
     Their holding lengths Y 4  and compensating lengths Z 4  each extend over five filling insertion cycles. The two chain warp yarns B 7 , B 8  each bind only over one filling, a back filling SR or an inner filling SI. 
     Holding length Y 4 ′ extends over five filling insertions, while compensating length Z 4 ′ includes seven filling insertions. It is advisable to alternate these weave designs reciprocally after certain lengths—as already mentioned in relation to FIG.  2 . If it is desired to avoid such changes W, the two differently binding pairs of chain warp yarns B 5 , B 6  or B 7 , B 8  respectively must be doffed from two different warp beams. 
     FIG. 5 shows a weave design in which individual chain warp yarns B 9 , B 10 , B 11 , B 12  are interlaced almost symmetrically and regularly according to a single weave design. A deflection of the pile legs in any direction is reliably avoided and individual chain warp yarns B 9 , B 10 , B 11 , B 12  of a group are preferably arranged in pairs in adjacent warp courses K 1 , K 2 . It is also possible to arrange these chain warp yarns B 9 , B 10 , B 11 , B 12  individually respectively in four adjacent warp courses. 
     Holding lengths Y 5  include five filling insertions, while compensating lengths Z 5  finish after three courses each. 
     The embodiment of FIG. 6 is essentially comparable to FIG.  5 . The difference is that chain warp yarns B 13 , B 14 , B 15 , B 16  bind over pairs of filling yarns instead of over individual fillings. In this embodiment a very high fabric density is achieved with an absolutely vertical orientation of the pile legs. At a pattern repeat size of  16 , there are nine courses in holding length Y 6  and seven courses in compensating length Z 6 . When suitable filling yarns are used, it is possible to reduce the need for chain warp yarns distinctly, if the individual chain warp yarns B of a group are distributed over several warp courses. 
     The weave of FIG. 7 differs from FIG. 6 in that the number of by a chain warp yarn B 17 , B 18 , B 19 , B 20  in the area of back fillings SR and inner fillings SI is further increased. In combination with other chain warp yarns B 17 , B 18 , B 19 , B 20  of a group, back fillings SR or inner fillings SI are respectively fixed separately in tabby weave. Holding length Y 7  and also compensating length Z 7  extend respectively over seven filling insertion cycles. 
     In FIG. 8 the number of filling yarns bound in this manner is increased to five fillings per filling yarn plane. Chain warp yarns B 21 , B 22 , B 23 , B 24  of a group are staggered so that on the one hand all back fillings SR and inner fillings SI are woven reliably and that back fillings SR are bound to inner fillings SI at regular intervals. 
     FIGS. 9 to  11  show the regular tie-in of filling yarns SR, SI, SZ by chain warp yarns B 25 , B 26 , B 27 , whereby the chain warp yarns in reciprocal alternation fix filling yarns SR, SI individually almost symmetrically according to a uniform weave design with the pattern repeat R 9 , R 10 , R 11 . 
     The differences between the individual FIGS. 9 to  11  consist only in the different position of the intermediate fillings SZ 1  (above the inner filling), SZ 2  (below the back filling), and SZ 3  (between the back filling and inner filling). 
     Chain warp yarns B 25 , B 26 , B 27 , B 28  of each of these back cloths can be arranged with respect to a group in one to four warp courses. 
     In FIG. 12, a pattern repeat R 12  of a chain warp yarn B 29 , B 30  consists of holding lengths Y 12  and compensating lengths Z 12  with different weave designs of the tabby weave type between inner filling SI and intermediate filling SZ 3  or between back filling SR and intermediate filling SZ 3 . All back fillings SR and all inner fillings SI are loaded symmetrically by chain warp yarns B 29 , B 30 . The tie-in length of chain warp yarns B 29 , B 30  of this group is compensated for by two change lengths W respectively, as in the Example of FIG.  2 . 
     The weave design of FIG. 13 is essentially comparable to the weave design of FIG.  7 . Change lengths W are shortened, however. 
     Holding lengths Y 13  extend over five filling insertion cycles; compensating lengths Z 13  likewise. 
     The additional intermediate fillings SZ 1 , which press stuffer warp FK against back fillings SR, ensure a slight curvature of stuffer warp FK that additionally prevents back fillings SR from sliding in the warp direction. Although individual back fillings SR are loaded unsymmetrically in the warp direction, they maintain their original position in combination with the adjacent fillings. Thus they enable an exact orientation of the pile legs vertical to the back cloth. 
     FIGS. 14 and 15 contain further modifications to FIGS. 7 and 8. Intermediate fillings SZ 2 , SZ 3  serve here to fix back fillings SR additionally, without chain warp yarns B 34 , B 35 , B 36 , or B 37 , B 38 , B 39  extending regularly over the entire cross section of back cloth OW. 
     With the embodiments described here, it is possible distinctly to reduce the number and incorporation of chain warp yarns B 34 , B 35 , B 36 , or B 37 , B 38 , B 39 . All the weave variants described have the effect of causing the pile legs to project vertically: from the back cloth—reliably and with feasible tolerances. 
     The reason for this varies in detail. The subject of FIGS. 16 to  18  is to represent the principles active thereby. 
     In the weave design of FIG. 16, the symmetrical loading of a pair of filling yarns by chain warp B 1  is utilized. Chain warp B 2  with its diagonally oriented holding length Y 2  and compensating length Z 2  deliver the necessary forces to hold filling yarn pair SR 1  and SR 2  against one another in the warp direction. The increase of inner tensions in chain warps B 1 , B 2  is avoided by the looping friction in combination with the friction caused by the gripping action within the finished fabric. Not only the density in the filling direction but also the density in the warp direction can be increased with the distribution of chain warp yarns B 1  and B 2  in adjacent warp courses. Laterally overlapping points of intersection of chain warp yarns B 1 , B 2  are avoided at the densest points in the fabric. 
     In the weave design according to FIG. 17, back fillings SR or inner fillings SI within holding lengths Y 17  (and also in compensating lengths  7 FIG. 7) are held against one another in their respective plane by means of tabby weave. All back fillings SR and also all inner fillings SI are held firmly against stuffer warp FK or dead piles PT respectively by means of at least one diagonal chain warp yarn length. In this manner the back cloth is very stable. Longitudinal forces (in the warp direction) in this system are additionally applied by the diagonal yarn length inside holding length Y 17 . Here too, the gripping forces have a favorable effect on this yarn length in the finished fabric. In the finished fabric, back fillings and inner fillings SR, SI remain where they are positioned during the beat-up (beat-up direction A). 
     FIG. 18 shows a weave design variant according to the invention that enables a vertical tie-in of the pile legs in spite of the asymmetry of the weave pattern. After being bound to inner filling S 14  within holding length Y 18 , chain warp yarn B 40  is guided over eight filling insertion cycles in the area of dead piles PT and stuffer warp FK. In this area it is stretched in the finished fabric and simultaneously gripped on all sides. The tensile force applied by it is exerted uniformly in beat-up direction A on all back fillings positioned in its effective area. 
     Although it appears in this weave that inner fillings SI are loaded in exactly the opposite direction, no deflection in this direction has been found in practice. It is highly probable that the reason for this is that the gripping forces on long holding length Y 18  within the finished fabric are so great that no deflection of the inner fillings takes place during a repeated filling beat-up. Even in this asymmetrical weave, the pile loops regularly project vertically from the back cloth. 
     The number of possible weaves is not yet exhausted with these Examples. It has been found that there must be certain numbers of filling insertion cycles in defining the sum of the lengths of holding lengths Y, chain warp yarns B of a group, and total pattern repeat length R of chain warp yarns B, if the desired effects are to be achieved regularly. 
     The density of the cross connections between back fillings SR and inner fillings SI ensures the necessary stability of the back cloth and the equally necessary friction of the fillings against the warp yarn strand (PT/FK). 
     Finally, we should mention that in particular the weave shown in FIG. 18 can also be woven in the opposite direction with similar effects. The asymmetrical tension on the back fillings will not be capable of changing the position of the back fillings during the repeated filling beat-ups, because of the stretched orientation of the compensating length (this would then be Z 18 ) between back fillings and inner fillings SR, SI. The gripping forces on chain warp yarns B building up within the finished fabric support this procedure. An almost vertical orientation of the pile yarn legs can also be achieved with this variant. 
     The results when a high pile density is achieved are similarly effective when a certain pattern repeat length is ensured. The saving of material for the chain warp overall is also fully effective in this variant. 
     The principles of the present invention can also be used in the weaving of face-to-face carpet fabrics in which not every patterning pile loop is stretched over a back filling. Examples of this are shown in FIGS. 19 and 20 for fabrics that have exclusively back fillings SR and inner fillings SI. Pile loops PM and PM′ are here bound alternately by back fillings SR and inner filling SI. 
     Chain warp B in FIG. 19 follows a pattern repeat R 19  that extends over  16  filling insertion cycles. The weave design is similar to that of FIG.  7 . 
     In FIG. 20 pattern repeat R 20  extends over  12  filling insertion cycles. It is similar to that of FIG.  6 . 
     FIGS. 21 and 22 show weave designs in which fillings SR, SI in top cloth OW are arranged in  3  planes respectively. Chain warp yarns B bind respectively over a pair of back fillings SR or inner fillings SI in the respective back cloth OW or UW. Pile loops PM, PM′ pass alternately once over a back filling SR and then over an intermediate filling SZ. 
     With these weave designs, a distinctly higher pile density and a saving of material for chain warp B are also achieved. The pile loops project sufficiently vertically from the back cloth here too.