US3717909A - Cloth straightening apparatus - Google Patents

Abstract

A CLOTH STRAIGHTENER FOR KNITTED OR WOVEN CLOTH COMPRISES A SERIES OF FEED ROOLS AND CLOTH STRAIGHTENING ROOLS, AT LEAST SOME OF WHICH ARE DRIVEN AT DIFFERENT OR DIFFERENTIABLE LINEAR SURFACE VELOCITIES IN PREDETERMINED, ADJUSTABLE RATIOS. VARIOUS ZONES OF THE CLOTH, DEFINED BETWEEN SUCCESSIVE DRIVEN ROLLS, CAN THUS BE SUBJECTED TO DIFFERENT DEGREES OF TENSION. IN EACH ZONE, THE MINIMUN LEVEL OF TENSION IS APPLIED THAT IS FOUND NECESSARY TO THE OPTIMUM PERFORMANCE OF VARIOUS FEEDING, STRAIGHTENING, AND DETECTING OPERATIONS.

Description

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CLOTH STRAIGHTENING APPARATUS Filed May 13, 1970 6 Sheets-Sheet 5 1212242212107 11701292008 IloZzeTZS'om 3 M (if/M46 flfior gys United States Patent 3,717,909 CLOTH STRAIGHTENING APPARATUS J. Douglas Robertson, Taunton, Mass., assignor to Mount Hope Machine Company, Incorporated, Taunton, Mass. Filed May 13, 1970, Ser. No. 36,848 Int. Cl. D06h 3/12 US. Cl. 26-514 20 Claims ABSTRACT OF THE DISCLOSURE BACKGROUND AND BRIEF DESCRIPTION OF THE INVENTION This invention has as its general object the reduction of deleterious stretching of light, delicate, or otherwise stretchable knitted or woven cloth in the process of straightening and aligning the cloth. It is another object to provide an improved cloth straightening apparatus which feeds, straightens, and detects the condition of the goods in separate zones in which the goods are subjected only to the various minimum degrees of tension required to perform these operations most effectively. Further objects and advantages of the invention will become apparent as the following description proceeds.

The weft or transverse filler threads of woven goods frequently become distorted in finishing processes, and it is necessary to restore the thread formations to their original appearance at the time the cloth was woven. This requires removal of bow to straighten the weft threads, and removal of skew to align them at right angles to the warp or longitudinal threads. Similarly, the courses of knit goods, which are the rows of stitches extending across the cloth, sometimes become bowed and/ or skewed in finishing, and must be returned to their original appearance as knitted, in the intended relation and at proper angles to the wales or ribs of the knit goods.

It is conventional practice to correct distorted or misaligned threads or courses by passing the cloth through a series of rolls which include at least one curved roll, a straight roll which is mounted for tilting motion about an axis perpendicular to its rotational axis, and feed or propelling rolls for maintaining tension in the goods as they pass over the other rolls. The curved roll or rolls cause the length of travel of the central portion of the cloth to differ from the length of travel of the edges through the set of rolls. These rolls therefore serve to correct bow distortion, or curvature from edge to edge of the cloth, of the weft threads or courses of the woven or knitted cloth. The axle of the curved roll has a curvature parallel to an axial plane. The extent of the correction can be controlled by turning this plane of curvature to different angular positions about the longitudinal axis of the roll.

Tilting of the straight roll creates a difference in the length of travel of opposite edges of the goods, and proportionate differences in the travel of the warp threads or wales located at various distances across the Width. This roll therefore serves to correct skew distortions, in which the weft threads of courses are not perpendicular to the warp threads or wales, respectively.

Both the two types of straightening rolls require that the goods must be held under some degree of longitudinal tension, so that any parts of the goods whose length of travel is relatively reduced will not separate from the roll surfaces. Such a separation produces a hook-shaped, sinous distortion of the weft threads or courses, which is not economically feasible to remove and therefore results in a waste of cloth. The required degrees of tension to prevent this happening are not, however, the same for both types of straightening rolls.

The condition of the weft threads or courses is usually detected shortly after the goods emerge from the straightening rolls. Detection by mechanical means, which is the most satisfactory method, requires that the goods be held under a proper degree of longitudinal tension, and this may have quite a differenent value than the optimum tension level required in the straightening processes. Again, the feeding of the goods to and from the straightening rolls may desirably take place under still another level of tension.

The net effect of these differing tension requirements for feeding, straightening, and detecting, has hitherto been that the entire span of goods through the roll array had to be subjected to the maximum tension required for any one of the operations. This was necessary even though such a high level of tension might be undesirable or even injurious in the other operations; and it caused the goods to be stretched to a maximum extent over the entire span through the apparatus. It should be noted that the amount of permanent stretch imparted to such goods per unit length depends not only on the applied tension, but also on the amount of time they are subjected to this tension, and hence on the length of the span in which the tension is applied.

Briefly stated, according to a preferred embodiment of my invention, certain of the rolls in a cloth straightening array are driven with different, or controllably difierentiable, linear surface velocities to establish different tension levels in several zones extending between adjacent driven rolls. The differing minimum degrees of tension compatible with optimum performance can thus be established in the several zones where the feeding, bow correction, skew correction, and detection processes are carried out. The ratios between the different tension levels are established and maintained constant by proportioning the speed of each roll to the measured speed of the next successive roll in the processing sequence. The speed ratios are controllable by manually adjustable means, to obtain the optimum tension levels for processing various goods of greater or lesser delicacy and stretchability.

While the specification concludes with claims particularly pointing out the subject matter which I regard as my invention, it is believed that a clearer understanding may be gained from the following detailed description of preferred embodiments thereof, referring to the accompanying drawing, in which:

FIG. 1 is a sectional view in side elevation of a first form of cloth straightening apparatus made according to the invention, taken along line 1-1 in 'FIG. 2, looking to the right in the direction of the arrows;

FIG. 2 is a plan view of the apparatus of FIG. 1;

FIG. 3 is a sectional view in side elevation, taken along line 3-3 in FIG. 2, looking to the left in the direction of the arrows;

FIG. 4 is a sectional view in side elevation, taken along line 4-4 in FIG. 2, looking to the right in the direction of the arrows; I

FIG. 5 is a fragmentary sectional view showing details of a drive connection with a curved roll forming a part of the apparatus;

FIG. 6 is a diagram of an electrical speed control circuit forming a part of the apparatus; and

FIG. 7 is a schematic view in side elevation of a modified embodiment of the invention.

Referring first to FIGS. 1-4, a preferred embodiment of the improved weft straightening apparatus includes a series of rolls comprising, in order of the sequence of their engagement with the sheet of woven goods 30; straight or right circular cylindrical rolls 1, 2 and 3; longitudinally curved bow-correcting rolls 4 and 5; a straight roll 6; a straight skew-correcting roll 7; straight rolls 8, 9 and 10; and a further straight roll 11 which does not form a part of the cloth straightener assembly proper, but is used as a reference indicator of the velocity of the sheet as it leaves the apparatus.

The rolls are rotatably mounted in a frame comprising a pair of parallel rectangular plates 14 and 16 and a series of transverse tubular bars 18. Equipment mounted outboard of the plates 14 and 16 is enclosed by housings 20 and 22, respectively, (FIG. 2) having removable cover plates 24 and '26. The axles of the straight rolls 1, 2 3, 6, 8, 9 and 10 are mounted in pairs of conventional bearings 28 carried by the plates 14 and 16.

An indefinite length of a sheet 30 of cloth is fed through the apparatus along the sinuous path show in FIG. 1, in the direction shown by the arrows. The cloth is guided into correct alignment by suitable guiding apparatus, illustrated as a pair of precision guiders 32, of a type described by my U.S. Pat. No. 2,417,447, issued Mar. 18, 1947. Each of these guiders comprises a pair of rolls 34 carried on a swinging arm 36, which is pivoted on an axis perpendicular to the plane of the goods 30. The rolls nip the cloth with a resilient grip. Turning the swinging arms 36 tilts the rolls more or less relative to the length of the goods, and thereby serves to guide the goods to left or right. Tension springs 38 bias eacharm 36 in a direction to engage peripherally-grooved wheels 40 with the selvages of the goods. A balanced condition is achieved by designing the arms 36 with a suitable gravitational bias, opposed to the springs 38, so that the wheels 40 continuously engage the selvages. If the selvages move to left or right, the resulting change in the angle of the arms 36 and the rolls 34 guides the goods back to their original track.

Each of the guiders 32 is carried on a frame 42, having grooved rollers 44 which engage transverse rods 46 attached to the plates 14 and 16. The spacing between the guiders may be adjusted to suit different cloth widths by operating a small motor 48 (FIGS. 2 and 3) mounted on the plate 14. This motor is arranged to drive a chain 49, which is trained around sprockets 50 and 52, and thence around idler sprockets (not shown) mounted inboard of the plate 16, and is connected to the guider frames 42.

The goods 30 are led by the guiders 32 to the rolls 1, 2, and 3, some of which may be provided with brakes for the purpose of applying back tension against forward passage of the goods. Whether such brakes are desirable or not will depend upon the particular application of the cloth straightener and the types of goods to be handled. In the illustrated construction, disc brake shoes 54 and 56 (FIG. 1) are arranged to act on a radial end surface of each of the rolls 1 and 3, respectively. These brakes are of a conventional type, and no further detailed description is believed necessary. The span of the goods extending from the roll 1 to the curved roll 4 constitutes a first tension zone, that is, a region in which a first differentiably-controlled tension may be created.

The curved bow-correcting rolls 4 and 5 have axles 60 and 62, respectively, which are longitudinally curved parallel to an axial plane. The outer sleeves of these rolls are flexible, so that they may rotate freely about the curved axles. Rolls of this nature are Well-known, and are described for example by my U.S. Pat. No. 2,393,191, issued Jan. 15, 1946.

The relative lengths of the paths of the central portions and selvages of the goods, from the roll 3 through the curved rolls 4 and 5 to the roll 6, may be changed by turning the planes of curvature of the axles 60 and 62 of the curved rolls about their longitudinal axes. As

shown in FIG. 1, the rolls 4 and 5 are aligned, with the planes of curvature of their axles lying in or parallel to a plane P. The rolls are so arranged that the length of the paths of the selvages E and central portion C of the goods are then equal, and no bow correction takes place. Means are provided for changing the positions of the planes of curvature of the axles 60 and 62 about their longitudinal axes, in such a manner that they turn in unison through equal arcs, but in opposite angular direction. This has the effect of changing the relative path lengths of the selvages E and central portion C; either may be made the longer, depending on the sense of the angular displacements of the axles. By these means, either a leading or a lagging bow of the weft threads or courses can be straightened. A more detailed description of the bow-straightening action appears in U.S. Pat. No. 3,167,843, issued Feb. 2, 1965 to William P. McCleary and myself.

The curved axles 60 and 62 are mounted for angular adjustment about longitudinal axes x and y, respectively, which are offset from the ends of the axles as shown in FIG. 1. The axes x and y are determined by tWo pairs of bearing assemblies 64, which are mounted on the plates 14 and 16, and which rotatably support pairs of stub shafts 68 at either end of each roll 4 and 5. These shafts carry transverse arms 66, to which the protruding ends of the curved axles 60 are pinned at 67 (FIG. 5). As best shown in FIGS. 2 and 4, a pair of sprockets 72 are secured on the shafts 68 projecting through the plate 16, and a drive chain 76 is trained around these sprockets in a manner to turn them in opposite angular directions, together with the shafts 68, arms 66, and the curved axles 60 and 62. A stepping motor 77 and a gear reducer 78 drive a sprocket 80 for positioning the curved rolls.

The surface sleeves of the curved rolls 4 and 5 are continuously rotated, independently of the angular positioning of the roll axles, by variable- speed motors 82 and 84 mounted outboard of the plate 14 (FIGS. 2 and 3). The curved rolls 4 and 5 thus serve not only for bow correcting, but also act as cloth-propelling or feed rolls. The motors 82 and 84 drive tachometer generators 92, 93, and 94 through sprockets 95, chains 96, and sprockets 98. The generators 93 and 94 are coaxial, and are driven in common by the motor 84. The same motors drive sprockets 85, chains 86, and sprockets 88 which are attached to stub shafts 90.

The shafts are received coaxially in the shafts 68, as shown in FIG. 5, to drive the outer rotatable sleeve of each curved roll 4 and 5. Each shaft 68 has an axial bore 102 receiving bearings 104 which rotatably support the associated shaft 90, an extension shaft 106, and a universal joint 108 which drivingly couples the shafts 90 and 106. The latter shaft is rotatably mounted on an axis which is parallel to the adjacent end of the roll axle 60, by means of bearings 110 set into the arm 66. A toothed wheel 112 afiixed to the end of the shaft 106 drives a belt 114 and a toothed wheel 116 which is attached to the end of the roll sleeve 100. The belt drive is enclosed by a casing 118 mounted on the arm 66, which is afiixed to the shaft 68 by machine screws 120, only one of which is shown. It will be understood from the foregoing that the motors 82 and 84 may continuously drive the sleeves of the rolls 4 and 5 independently of the angular positioning of the curved roll axles 60 and 62 by means of the shafts 68 and arms 66. By proper control of the relative surface velocities of the rolls 4 and 5, a second tension zone can be set up in the span between them, in which a level of tension different from that in other portions of the goods can be created.

Referring again to FIGS. 1 and 2, the goods 30 departing from the curved rolls 4 and 5 pass over the straight roll 6, and thence through a large angle of wrap around the straight skew-correcting roll 7 to the straight roll 8. The skew-correcting roll 7 is supported by a tilting frame 124 which has L-shaped brackets 126 affixed at either end for supporting the axle 128 of the roll. The frame 124 is pivotally supported at 130 on a tongue 132, which is welded to an L-shaped transverse beam 134 forming a part of the frame of the apparatus. The assembly of the tilting frame 124 and the roll 7 are supported for angular movement about the pivot 130 by means of two pairs of rollers 136' mounted in arms 138 and 140 afiixed to the outboard ends of the tilting frame. The arms extend through elongated horizontal slots 142 formed in the plates 14 and 16, and these slots guide and support the rollers 136.

The drive gear mounted outboard of the plates 14 and 16 is protected from entry of lint and dust by attaching flexible spring strips 144 (FIGS. 3 and 4) to the arms 138 and 140 to cover the slots 142. The strips are rolled up on spring-loaded drums 146 mounted at either end of the slots 142, so that the slots remain completely covered as the arms 138 and 140 move back and forth.

As best shown in FIGS. 2 and 4, the assembly of the tilting frame 124 and roll 7 is angularly positioned about the pivot 130 by a reversible motor 148, :which drives a sprocket 150 through a gear reducer 152. A chain 154 is trained about the sprocket 150 and an idler sprocket 156, and has its ends attached to the arm 140 by means which include a tension-adjusting device 158.

Operation of the motor 148 in either angular direction drives the chain 154 to re-position the tilting frame 124 and the roll 7 about the pivot 130. This allows for an increase in the path length of either edge of the goods 30 from the roll 6 to the roll 8 about the roll 7, and a proportionately shorter path length for all other longitudinal elements of the goods. A skew distortion of the weft threads or courses can be corrected by tilting the roll 7 to increase the, path length of the edge at which the weft threads or courses are leading, and to adjust to proportionately shorter path lengths the longitudinal warp threads or wales spaced across the Width of the goods.

The roll 8 is shown in FIGS. 2 and 3 to have a drive sprocket 160 fixed at one end of its axle 162, for the purpose of driving this roll through a chain 164 and an additional variable-speed motor (not shown). This roll thus serves as a cloth-propelling or feed roll. Independent control of the surface velocity of this roll makes it possible to set up a third tension zone in the span extending from the second curved roll 5, about the rolls 6 and 7 to the roll 8. A different level of tension than that existing in other parts of the goods can be created in this span, to suit optimally the paticular requirements of the skew-straightening opertions of the roll 7.

A short span is established between the rolls 8 and 9 for the purpose of detecting distortions of the weft threads or courses as the goods depart from the straightening rolls. A series of detectors 166 are provided, of which any number may be used as appropriate to a particular application, although four are shown by way of illustration. The detectors are supported by frames 167 and grooved rollers 168 on parallel transverse rods 170, attached at their ends to the plates 14 and 16. The spacing of the detectors transversely of the goods may be adjusted to suit diflt'erent cloth widths by operating a small motor 172 (FIGS. 2 and 3) mounted on the plate 14. This motor is arranged to drive a chain 174, which is trained around sprockets 180 and 182 (FIG. 4) mounted on the plate 16, and is connected to the detector frames 167.

The illustrated detectors 166 are made in accordance with US. Pat. No. 3,350,933 issued to L. J. Smith on Nov. 7, 1967, which is assigned to the assignee of this application. These detectors employ caster wheels 184, which are pressed slightly into the plane of the cloth defined by the rolls *8 and 9 to create local distortion patterns. The caster wheels are deflected angularly from a normal alignment with the length of the goods, if the thread formation of the weft threads or courses are distorted from their normal and proper relationship to the longitudinal warp threads or Wales of the goods. Such angular deflections are measured electrically and transmitted by cables 186 to a control circuit 188 (FIG. 4).

The deflections of two or more caster wheels are simultaneously added and substracted by the control circuit 188, to produce control signals separately indicating skew and bow distortions. A distortion of the weft threads or courses which involves a combination of both types of distortions is divided into component skew and bow control signals. Any resulting skew distortion signal is applied by leads 190 to operate the reversible motor 148 in a manner to tilt the skew-correcting roll 7 to a position which will remove this distortion. Bow distortion signals are applied by leads 192 to operate the reversible motor 77 in a manner to rotate the axles of the curved rolls 4 and 5 to positions which will remove this distortion. The details of the illustrated detection and control means are described more fully by the aforementioned U .S. Pat. No. 3,350,933, and as they form in themselves no part of the present invention, no further detailed description is believed necessary. Other well-known types of detection and control means may be used alternatively to control the operation of the straightening rolls 4, 5, and 7.

The axle 194 of the cloth-propelling or feed roll '10 is driven by a variable-speed motor 196 (FIG. 3), through sprockets 198 and 200 and a chain 202. This establishes a fourth tension zone extending between the rolls 8 and 10, in which the tension level most suitable to the detecting operation may be set up by appropriate control of the linear velocity of the roll 10.

The skewing motion of skew correcting roll 7 tends to stretch one edge of the web passing over it, and slacken the other edge. If the web reaches the detecting zone between rolls 8 and 9 in this condition, the detectors do not func' tion properly and false signals may be developed. To avoid this the roll *8, and optionally also the roll 9, are wrapped with a material with a high coefiicient of friction. This tends to prevent one selvage from slipping over the roll '8 with respect to the other selvage, thus maintaining a substantially constant tension across the web in the detecting zone between the rolls 8 and 9. In some applications, it may prove satisfactory to omit a separate drive for the axle 162 of the roll 8, thus extending the third tension zone through the entire span from the curved roll 5 to the roll 10. The same tension level would then prevail in the skew-straightening operation between the rolls 5 and 8 as in the detecting operation between the rolls 8 and 10, but this may prove acceptable for some uses.

The motor 196 also drives two co-axial tachometer-generators 204 and 206 (FIG. 3) through sprockets 208 and 210, and a chain 212. An additional tachometer generator 214 (FIG. 1) is driven by a roll 11 spaced in the downstream direction of movement of the goods 30, by means of sprockets 216 and 218 and a chain 220. This provides a reference velocity signal. The roll 11 is not a part of the cloth straightener proper, and any roll provided in a specific installation for other processing purposes will serve the purpose if it is located upstream or downstream and delivers or receives the cloth in a continuous, uninterrupted flow to or from the cloth straightener.

Referring now to FIG. 6, a circuit for controlling the relative speeds of the rolls 4, 5, and 10 is shown schematically. As the system is illustrated, it is assumed that the roll 8 is not to be driven independently, and that there are accordingly only three separate tension zones Within the cloth straightening apparatus: a first feeding zone extending through the braked rolls 1 and 3 to the first curved roll 4; a second bow-straightening zone extending between the curved rolls 4 and 5; and a third combination skew-straightening and detection zone extending from the curved roll 5 to the driven roll 10. The tension applied to the goods before arrival at the roll 1, and after departure from the roll 10, is controlled by other apparatus suitable to a particular application, and of a conventional nature.

The circuit includes speed control units 232, 234, and 236, which may be identical commercially-available units suitable for controlling the speeds of the DC. motors 196, 84, and 82, respectively, by supplying them with armature excitation voltages which are controlled by silicon-controlled rectifiers in response to applied signal voltages. The output armature excitation voltages of the respective speed control circuits are subject to manual adjustment by the potentiometers 238, 240, and 242.

The roll 11 drives the tachometer-generator 214 to provide a reference signal, which represents the overall velocity of motion of the running length of goods. For this purpose, the roll 11 may equally well be located ahead of the weft straightener, relative to the direction of feeding of the goods, instead of downstream as it is illustrated.

The reference signal generated by the tachometer 214 is supplied by a lead 244 to the unit 232, whose output voltage is supplied by a lead 246 to control the speed of the motor 196, and hence the linear surface velocity of the roll 10. This velocity may be adjusted by the potentiometer 238 to be equal to, greater, or less than the linear velocity of the roll 11. In a similar fashion, the roll drives a tachometer-generator 204, whose output voltage is supplied by a lead 248 to the control unit 234, which in turn supplies a voltage through the lead 250 for controlling the speed of the motor 84 and the roll 5, subject to variation by adjustment of the potentiometer 240. The roll 5 in turn drives the tachometer-generator 94, whose signal voltage is supplied by a lead 252 to the unit 236, which supplies armature excitation voltage through a lead 254 for controlling the speed of the motor 82 and the roll 4, subject to variation by the potentiometer 242.

In the illustrated circuit, a closed loop system is used to obtain very precise speed control. The system accordingly includes the additional tachometer- generators 206, 93, and 92, which are connected by the leads 254, 256, and 258 to the input leads of the control units 232, 234, and 236, respectively. The feedback signals thus supplied provide a more precise speed regulation, but the addi tional tachometers may be omitted in applications for which an open-loop system affords sufficiently accurate regulation.

It will be observed from this description that the linear surface velocities of the rolls 10, 5, and 4 may all be made equal to that of the reference roll 11, by appropriate adjustments of the potentiometers 238, 240, and 242. In that case, a uniform degree of tension would be applied to the goods in every zone through the weft straightener. However, in accordance with the principles of practice of the invention, the speeds of the rolls 10, 5, and 4 are diiferentiable; that is, the potentiometers may be so adjusted that the speed of these rolls will assume a relationship that applies different degrees of tension to the goods in each zone defined between these rolls. It will be understood that the tension in a given zone may be relatively reduced by running the roll at its origin somewhat faster than the roll at its terminus; and the tension in any zone may be relatively increased by reversing this speed relation. The relative degree of tension in each succeeding zone can be controlled in an independent manner, and can be either more or less than that applied to the goods in other zones or in the runs external to the cloth straightener.

The various degrees of tension applied in the different zones are so selected that the minimum tension consistent with the optimum performance of each of the operations of feeding, bow correction, skew correction, and weft detection, is applied in each of the corresponding zones. In this way, the minimum tension is applied to the cloth for the minimum time, and the adverse eifect to delicate goods is reduced, while the various operations necessary to rectifying the weft threads or courses are performed under the optimum tension levels. These different tension levels are readily ascertainable in the operation of the cloth straightener on various types of woven or knitted goods, as will be appreciated by those skilled in the art.

A modified construction is schematically illustrated in FIG. 7, in which the straightening operations are carried out in the reverse order to that of the apparatus in FIG. 1. That is, skew distortions are removed before how distortions. The operation of the skew-straighting rolls, if placed next adjacent to the detection zone, may disturb the detectors more than would bow-correcting rolls operating in the same location. This relatively greater disturbance is caused by large and rapid excursions of the skewstraighting rolls, necessary because of the often-sudden appearance of skew distortions.

The apparatus schematically illustrated in FIG. 7 includes the rolls shown in FIG. 1, all similarly numbered. In addition, straight rolls 270, 274, and a curved roll 276 are provided for guiding the cloth 30 in the direction indicated by the arrows, in a predetermined path through the apparatus with proper angle of wrap about the other rolls.

- Roll 270 might be equipped with a brake like that of rolls 1 or 3 in FIG, 1. A second straight skew-correcting roll 272, identical with the roll 7, is also provided to reduce the amount of angular displacement required of these rolls by doubling the cumulative skew-correcting effort. The rolls 7 and 272 are supported by a pair of tilting frames 124 and L-shaped brackets 126, both frames being pivotally supported on pins on a common axis, normal to the planes of travel of the cloth to and from these rolls. The positioning arm 140, previously described in connection with FIGS. 2 and 4, is connected to both brackets 126, and the motor 148 angularly positioned both rolls 7 and 272 jointly about the axis of the pins 130. The consequent increase or decrease of the path length of either edge of the cloth 30 is doubled with respect to the change attained by a single skew correcting roll, for a given angle of tilt.

The cloth is passed by the roll 6 to the curved rolls 5 and 4, both of which are angularly adjustable as described in connection with FIGS. 1-6 for correcting bow distortions.

The curved roll 276, receiving the cloth from the rolls 3, 2, and 1, none of which are braked rolls in this embodiment, expands the cloth as it travels to the rolls 8 and 9, which form a short span for cooperation with the detectors 184.

The rolls 4, 5, and 10 are driven by motors in the manner described in connection with FIGS. 1-6. In addition, the curved roll 276 is preferably driven by an additional motor (not shown) similar to the motors 82, 84, and 196 (see FIG. 6). This motor is coupled to an additional tachometer similar to the tachometers 92, 94 and 204, and is connected in a like manner to a speed-control unit similar to the units 232, 234, or 236. The roll 276 is thus driven at a speed having a regulated and adjustable ratio to that of the roll 10, and takes its place in the speedcontrol chain to regulate the speed ratio of the roll 5. Consequently, there are at least four separate tension zones defined within the apparatus: a first skew-straightening zone extending through the rolls 272 and 7 to the first curved roll 5; a second bow-straightening zone extending between the curved rolls 5 and 4; a third clothpropelling zone extending from the curved roll 4 to the driven roll 276; and a fourth detection zone extending between the driven ralls 276 and 10, in which the detector wheels 184 operate. This system isolates the disturbances of the skew-straightening zone completely from the detection zone.

It should be noted that the illustrated drive system comprising separate variable-speed motors for each driven roll, may be replaced by other well-known variable-speed motive means capable of driving the various rolls at controllably-differentiable linear surface velocities. For example, a common variable-speed motor, which in itself establishes the reference velocity of the cloth, may drive a series of variable-speed mechanical drives, such as the belt-and-cone type, one connected With each driven roll, and each arranged for individual speed control to maintain predetermined ratios between the surface velocities of the various driven rolls.

What I claim is:

1 Apparatus for straightening and aligning the crosswise thread formations of a running length of distorted cloth to restore it to substantially its form when first made, while limiting the tension applied to that required for optimum performance of the straightening operation, said apparatus comprising, in combination:

an infeed roll engaging the cloth first and defining an infeed zone extending therefrom toward the source of the cloth; at least one straightening element engaging the cloth second and defining a straightening zone extending from said infeed roll to said straightening element;

adjusting means for said straightening element for selectively varying the path lengths of edge portions relative to central portions of said cloth to correct bow distortions of the crosswise thread formations thereof, and for selectively varying the path lengths of longitudinal thread formations spaced across said cloth to correct skew distortions of said crosswise thread formations;

at least one cloth propelling element engaging the cloth third and defining a zone for detection of the orientation of said crosswise thread formations, said detection zone extending from said straightening element to said propelling element; and

motive means constructed and arranged for driving said straightening element and said propelling element at different linear surface velocities having a predetermined continuously-maintained ratio, to create different levels of tension in the cloth in said infeed, straightening, and detection zones as required for optimum feeding, straightening, and weft detection.

2. Apparatus as recited in claim 1, together with speedcontrol means constructed and arranged for detecting the linear surface velocity of one of said elements, and operatively connected with said motive means for driving the other of said elements at a different linear surface velocity in said predetermined ratio to the velocity of said one element.

3. Apparatus as recited in claim 1, together with speed control means constructed and arranged for detecting the speed of said cloth and the linear surface velocity of one of said elements; said speed control means being operatively connected with said motive means for driving said one of said elements at a linear surface velocity different from the speed of the cloth and having a predetermined ratio thereto, and for driving the other of said elements at a linear surface velocity different from that of said one of said elements and having a predetermined ratio thereto.

4. Apparatus as recited in claim 1, in which said one straightening element comprises a curved roll.

5. Apparatus as recited in claim 4, together with a further straightening element comprising a tiltable straight roll engaging the cloth in said straightening zone.

6. Apparatus as recited in claim 4, together with a further straightening element comprising a tiltable straight roll engaging the cloth in said detection zone.

7. Apparatus as recited in claim 1, together with manually-adjustable speed control means operatively connected with said motive means for controlling the ratio between said linear surface velocities in response to the observed straightening action of the apparatus.

8. Apparatus as recited in claim 1, together with means engaging the cloth in said detection zone for detecting distortions of said crosswise thread formations and operatively connected for controlling said adjusting means to straighten and align said crosswise thread formations.

9. Apparatus for straightening and aligning the crosswise thread formations of a running length of distorted cloth to restore it to substantially its form when first made, while limiting the tension applied to that required for 10 optimum performance of the straightening operation, said apparatus comprising, in combination:

an infeed roll engaging the cloth first and defining an infeed zone extending therefrom toward the source of the cloth;

straightening elements including at least one straight roll and one curved roll engaging the cloth second and defining a straightening zone extending from said infeed roll to said straightening elements;

means for adjusting said curved roll to vary the path lengths of edge portions relative to central portions of said cloth to correct =bow distortions of the crosswise thread formations thereof, and means for adjustably tilting said straight roll to vary the relative path lengths of longitudinal thread formations spaced across said cloth to correct skew distortions of said crosswise thread formations;

at least one cloth propelling element engaging the cloth third and defining a zone for detection of the orientation of said crosswise thread] formations, said detection zone extending from said straightening elements to said propelling element; and

motive means constructed and arranged for driving at least one of said straightening elements and said propelling element at different linear surface velocities having a predetermined continuously-maintained ratio, to create different levels of tension in the cloth in said infeed, straightening, and detection zones as required for optimum feeding, straightening, and weft detection.

10. Apparatus as recited in claim 9, said infeed roll, said curved roll, said straight roll, and said propelling element being arranged in sequential order of engagement with the cloth.

11. Apparatus as recited in claim 9, said infeed roll, said straight roll, said curved roll, and said propelling element being arranged in sequential order of engagement with the cloth.

12. Apparatus as recited in claim 9, said straightening elements including two of said curved rolls.

13. Apparatus as recited in claim 9, said straightening elements including two of said straight rolls.

14. Apparatus as recited in claim 9, said propelling element comprising a roll, said motive means rotationally driving at least three of said rolls at different linear surface velocities, together with speed-control means constructed and arranged for detecting the linear surface velocities of a plurality of said driven rolls other than the first in the sequence of said driven rolls; said speed-control means being operatively connected with said motive means for controlling the ratio between the surface velocities of each sequential pair of said driven rolls in response to the linear velocity of the second of that pair.

15. Apparatus as recited in claim 14, together with speed-control means including manual speed-adjusting means operatively connected with said motive means for independent adjustment of the ratio between the linear surface velocities of each sequential pair of said driven rolls, in response to the observed straightening action of the apparatus.

16. Apparatus as recited in claim 9, together with means engaging the cloth in said detection zone for detecting distortions of said crosswise thread formations, and operatively connected for selectively controlling said adustmg means and said tilting means to straighten and align said crosswise thread formations.

17. Apparatus as recited in claim 9, said motive means being drivingly connected with at least said curved roll and said propelling element.

18 Apparatus as recited in claim 9, said rolls includmg, in sequential order of engagement with the cloth, two of said curved rolls, said straight roll, and said propelling element; said motive means being drivingly connected with at least said two curved rolls and said propelling element.

19. Apparatus as recited in claim 18, together with ad- 11 justable means acting to control the surface velocity of said infeed roll to control independently the tension in the cloth in said infeed zone.

20. Apparatus as recited in claim 9, said propelling element comprising at least two propelling rolls; said motive means being drivingly connected with said curved roll and said two propelling rolls; said detection zone extending between said propelling rolls and being isolated thereby from said straightening elements.

References Cited UNITED STATES PATENTS 10 ton, Mass.

12 Robertson et a1. 2651.9

Sciola 2651.3

Robertson et a1 2651.4

Strandberg 2618.6 X Leitner et a1. 2651.5

OTHER REFERENCES The Easiest Way to Get Rid of Bows or SkeWs or Both, Mount Hope Machinery Co., 15 Fifth St., Taun- ROBERT R. MACKEY, Primary Examiner

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