GB2035403A - Straightening of webs of woven material in the weft direction - Google Patents

Abstract

Apparatus for straightening wefts in woven fabric includes a print blanket 6 to apply uniform tension to the fabric web 1, feed roller assembly 3, a scanner 5 and a regulating unit 4, operated in response to the scanner to raise the web 1 against transverse bars 49 to extend the web lengthwise and simultaneously retard the web. The unit 4 includes links 44 carried on screw stem 42 and operated by motors 40. The scanner can be mechanical, photo- electrical or inductive. <IMAGE>

Description

SPECIFICATION Improvements in or relating to methods and apparatus for straightening of webs of woven material in the weft direction The invention relates to a method and apparatus for the straightening of the weft direction of webs of woven material for example textile webs for printing machines.

Propositions for dealing with this problem are known, for instance rollers which sink deeper into the surface of the material on one side for a diagonal form of distortion, or flexible rollers for curvital distortion. Such rollers are however unsuitable for the correction of irregular distortion.

The proposal has been made, for the rectification of distortion in any form in woven fabric webs, to make use of rollers divided into sections, each of which can be driven at different speeds according to the degree of the distortion. The disadvantage here is that all the warp threads lying on one section of the roller are subjected to the same tension, so that adjoining warp threads on different sections of the roller can be stressed to a very different extent, with the result that the weft threads in these areas are distorted anew. The same disadvantage is shown by thrust devices, which sink more or less deeply into the surface of the material according to the degree of distortion.

use is also made of flexible, deformable bands, which are pressed on to the web of material more or less heavily according to the amount of distortion.

The edges, which are unavoidable in such bands however, run too easily into the material.

According to one aspect of this invention a method for the straightening of webs of woven material in the weft direction comprises transporting a web uniformly, moving or impressing the web at an adjustment position to produce a variable extension of the travel and simultaneously retarding the web at this position.

According to another aspect of the invention apparatus for straightening of webs of woven material in the weft direction comprises a regulating unit having positionally-variable link members which perform translatory and rotary motions and which are pivotally connected by lifting elements arranged to receive command signals, which signals are determined by measurement units responsive to the web, the arrangement being such that in use the regulating unit produces a variable extension of the web travel and simultaneously retards the web.

These drawbacks are obviated by the proposals in accordance with the invention.

The invention may be performed in various ways and some specific embodiments for the continuous straightening of the weft direction will now be described by way of example with reference to the accompanying drawings, in which: Figures 1 to 4 show diagrammatically the arrangement possibilities for the individual structural units, as they follow one another in the direction of motion 1 of the material web 2; Figure 5 depicts a scanning unit with mechanical contact element; Figure 6 is a longitudinal sectional view of Figure 5; Figure 7shows a scanning unit with inductive element; Figure 8 is a longitudinal sectional view of Figure 7; Figure 9 depicts a photo-electric scanning unit, and Figure 10 is a longitudinal sectional view of Figure 9; Figure lOa shows a constructional form of the invention with doubly-supported swinging link members;; Figure ii shows a form of control equipment, with chain-type connected link members in the direction of the material transportation; Figure 12 is a vertical section through Figure 11 on the line A-A; Figure 13 shows a form of the hinged joints of the chain link members; Figure 14 is a sectional view of Figure 13; Figure 15 is a further sectional view of Figure 13; Figure 16 depicts a second form of the hinged joint; Figure 17 is a sectional view of Figure 16; Figure 17a shows a detail of Figure 16; Figure 18 is a general view of a further form of construction of the chain link member control equipment; Figure 19 is a detail view from Figure 18; and Figure 20 is a further sectional view of Figure 19.

The weft control is effected by varying the height at the pivot points of link elements, whereby these elements can also sink obliquely into the surface of the material, thus subjecting the warp threads to a tension precisely in accordance with the degree of distortion, with no sudden wide stressing differentials between adjacent warp threads.

Included in the complete installation is a scanning unit of a familiar form of construction with photoelectric, inductive or mechanical transmitters, together with a feed roller assembly, also of wellknown constructional form, which in conjunction with the driven blanket of a printing machine, produces a uniform tension in the web of material.

Figure 1 depicts an embodiment of the overall arrangement in the direction 1 of the transportation of a material web 2, successively enumerated as follows: feed roller assembly 3, link member regulating unit 4, scanner unit 5 and printing machine blanketS. As shown in Figure 1, the structural elements 3,4 and 5 are combined in an assembly and are located immediately in front of the printing machine blanketS, or at some distance from same.

The woven fabric web 2 is drawn by the feed roller assembly 3 from the preceding structural members of the material guide line, not illustrated, and uniformly tensioned through interaction with the blanket 6 of a printing machine, whereby the web passes over a guide roller 30, a delivery roller 31, a pivoted roller 32 and a second guide roller 33. A scanning unit 5 of the desired type, (shown in more detail in Figures 5 to 10), deterines the distortion of the weft threads in the uniformly-tensioned web 2 and transmits command signals according to the degree of distortion to actuating motors 40 of the control unit 4. The motors 40 rotate spindle-nuts 41, whereby screwed spindles 42 and, through pivot pins 43, one or two regulating link members 44 are raised.The link members 44 force the fabric web 2 between two guide bars 49 with a greater or lesser firmness according to the command of the scanning unit 5. This produces a differential lengthening of the travel and eventual retardation, and thereby also a differential tension in the warp threads of the web 2.

In the case of particularly delicate materials or those which show marked extension characteristics even with light application of force, the bars may be substituted by rollers, if necessary segmented or split.

The uniform tension of all warp threads produced by the feed roller assembly 3 and the differential tensioning of these threads induced by the aligning unit 4 are superimposed on one another. The warp threads subjected to most stretch are also those which are subjected to the highest retardation, so that the weft threads are straightened out. As the printing machine blanket 6transports less material with highly-tensioned warp threads than with a lower tension warp, a progressive lagging of the leading portions of the web 2 takes place and the raised screwed spindles 42 gradually fall back. In place of the printing machine blanket, a roughsurfaced roller may be provided after the aligning unit, especially where this installation is operating in a material handling line which does not relate to a printing machine.It is essential that the web of material adheres to the surface of a subsequent transportation device. With all weft threads in a perfectly straight line at right-angles to the direction of transportation 1 of the material, all the screwed spindles 42 are in the zero position. The web 2 then only contacts both the regulating link members 44 and the deflecting rollers 49 tangentially. Afurther distortion leads, through the scanning unit 5, to re-raising of one or more of the screwed spindles 42.

Figure 2 shows another embodiment of the overall arrangement, in which the feed roller assembly 3 and the link member regulating unit 4 form a group at a distance from the printing machine blanket 6, directly in front of which the scanning unit 5 is mounted.

Figure 3 shows an embodiment having the sequence of parts : feed roller assembly 3, scanning unit 5, link member regulating unit 4, printing machine blanket 6.

Figure 4 shows an embodiment having the sequence of parts : scanning unit 5, link member regulating unit 4, feed roller assembly 3, printing machine blanket 6.

Figures 5 and 6 show a scanning device 5 with a mechanical contact member 50. This type of scanner is particularly suitable for textile fabrics 20 with a varying thickness, such as are used, for example, for towelling with a frictional texture. In such material, the boundary 23 between the tufted friction section 21 and the plain section of linen texture 22 runs in the exact direction of the weft threads 24. The scanning contacts 50 are arranged in a row at right-angles to the direction of motion 1 of the material web 20.The contact 50 which first meets the tufted material 21 at the boundary 23 switches on a counter 59 (not illustrated) for each of the other scanners, these scanners 50 switching their counters 59 off as soon as they too reach the boundary 23 of the tufted material 21.The position of the counters 59 after actuation of all scanning contacts 50 is an indexforthe distortion of the material in the direction of the weft and also a value for the magnitude of the control impulse which is passed to the regulating unit 4.

Figures 7 and 8 show a scanning device 5 with inductive scanning heads 55. This device is suitable for example for fabrics of constant thickness also for crepe materials. The inductive scanning heads 55 determine the position of thin metal wires or magnetic dyes 26, which are inserted together with a weft thread 24 at intervals in the fabric of uniform thickness 25. The further functional procedure is as for the mechanical scanning device shown in Figures 5 and 6.

Figures 9 and 10 show a photo-electric scanning unit 5. Such scanning devices are applicable for transparent or translucent materials 27. Photoelectric cells 56 with a slotted light entry are mounted on a beam 57, which swings continuously and uniformly about a central vertical axis in a plane parallel to that of the material. The light penetrates the material 27 and into the photo-electric cell either from a large area light source 58 or from a lighting bar swinging with the cells. Should the slit of a photo-electric cell 56 have the same alignment as the section of the weft thread 28 which lies below it, then the light entering the photo-electric cell 56 exhibits intense pulsating characteristics, these being at the frequency at which the weft threads 24 of the material web 27 are passing the photo-electric cell.

The less the alignment of the section of weft thread 28 coincides, the stronger are the pulsation of the light entering the photo-electric cell 56. A processing calculator (not shown) records the angular position of the beam 57 whenever the photo-electric cell 56 registers the maximum pulsating light and applies this angular position to the co-ordinates of that part of the material to which the relevant photo-electric cell 56 is positioned. The angular positions so recorded represent tangents to the curve of the weft threads. The processing calculator then conducts a Fourier synthesis utilizing the recorded values of the angular position and the width~co-ordinates, and by this means determines the pattern of the weft. In the subsequent sequence, control impulses are transmitted to the regulating unit 4.

Figure 11 shows a general view of the link member aligning unit 4, in the direction of the material transportation. In a machine frame structure 400, actuating motors 40 are mounted, vertically-moving screwed spindles 42 are supported and two slidebars 49 provided above the material web 2. The actuating motors 40 rotate the spindle nuts 41 in accordance with the correcting impulses initiated by the scanning unit 5, thereby raising the spindles 42 and, through the pins 43, also the ends of the regulating link members 44.

In Figure 12, the same reference numbers apply is in Figure 11. It can be seen here, that the slide-bars 49 are adjustable in respect of their distance 491 and 492 from the extension of the centre-line of the screwed spindles 42, with the result that the relation of the retarding effect exerted on the material web by the raised chain link members 44 to the increased traverse distance of the warp threads, can be varied.

It can also be seen in Figure 12, how when the link members 44 are not raised, the material web 2 contacts the deflecting rollers 49 and the link members 44 tangentially. With the raising of the link members 44 beyond the dimension 493, a further lengthening of the warp thread travel can be attained without any further increase in the retarding effect, which is advantageous for different qualities of material.

Figures 13, 14 and 15 illustrate the feasibility of connecting the spindle ends 420 with one or two chain link ends 441 and/or 443 with a hinged joint, whereby the spindle 42 can only move vertically in the bearing 421a.

In Figures 10a, a form of construction of the invention is shown with doubly-supported swinging link members. As described for Figure 2, the spindles 42 are raised by motors 40 and spindle-nuts 41 in conformity with the distortion of the material web.

As a consequence of the double support 424 and 425, the regulating elements 44 adjust themselves in a greater or lesser inclined position according to the differential tensile stressing present in the material web 2. A hinge-pin 43 is secured in the spindle end 420. The end 441 of the link member 44 is pivoted in a drilled hole on the hinge-pin 43, the other end 443 being supported in an elongated hole to both swivel and move longitudinally, so that it is possible for the link members 44to take up an inclined position while the distance between the spindles 42 remain constant.The end 443 of the link member 44 which is provided with an elongated hole is tapered off 445 on the surface 444 facing the material web 2, in order not to project beyond the surface 442 of the other end 441 of the link member 44 when in the inclined position, which would exert an additional, and narrowly-restricted, local retarding, and therefore troublesome, effect on the material. It can also be clearly seen in Figure 14, that all edges of the link members 44 are convered by half-round sections or lengthwise by half-tubing 446 with large radii, so that even with maximum adjustment, no sudden retarding effects can be produced as the result of sharp edges. In Figure 15, it is clearly shown how the half-round coverings 446 are provided with chamferings 447 at their ends, so as not to impede the articulation of the link members 44.Furthermore, in the inclined position of these members, an increasing gap 448 appears between the half-round sections 446. By limiting the vertical travel of the spindles 442, the chamfer 447 is diminished and by providing only the one end 443 of the link member 44 with an elongated hole, and not the other end 441, a further limitation of the alteration in the gap 448 is achieved.

Figures 16, 17 and 17a show a further embodiment. The link member 44 in this case comprises two telescopic halves 441 and 443, which are forced outwards by a compression spring 449. The half 441 is pivoted on the pin, whilst the half 443 is supported through an elongated hole, to both swivel and move lengthwise. The centre-line of the elongated hole in part 443 describes an arc with radius 430 around the point 440, so that the end 441 cannot rise above the other end 443 and, because of the pressure of the spring 449, cannot retract from the other end.

Consequently, the half-round section coverings 446 of two pivot-jointed link members 44 at the surfaces 442 and 444 are always in contact at the points 440.

Chamfers 447 on the coverings 446 provide for differential inclination of the link members 44.

Figures 18, 19 and 20 depict a further form of construction of the link member control equipment.

Here also, the screwed spindles 420 and 421 are supported to move only vertically, i.e., in the direction of their longitudinal axes. Only one screwed spindle 420 is however connected directly by a hinged joint to the regulating members 44. The spindles 421, on the other hand, are connected through pins 422 to swinging links 423, in the other end of which the pins 43 are secured, on which one or two regulating link members 44 are attached to pivot only. The reduction of the horizontal distance 432 between two pins 43, which occurs in the inclined position of the regulating link members 44, is made possible by the swinging links 423. At each end of the pins 43, a hemisphere 431 is provided.

Both ends of the half-round section or half-round coverings 446 are recessed in the form of a quartersphere and provided with a wedge-shaped chamfer 447. The more or less open V-gap 449a between two coverings 446, according to the inclination of the link members 44, does not produce any unfavourable results, as the open gap 449 only exposes the adjoining surface of the hemisphere 431 in the same plane.

The invention is not restricted to the constructional examples which have been depicted. For example, it is possible to dispense with the swinging links in the arrangement of Figure 18 and to pivot the complete raising mechanism of motor, spindle-nut and screwed spindle around a point, orto arrange forthe raising device notto engage two regulating links 44 at their hinged connection, but at another point, for example, in the centre of the link members 44.

Claims (18)

1. A method for the straightening of webs of woven material in the weft direction, comprising transporting a web uniformly, moving or impressing the web at an adjustment position to produce variable extension of the travel and simultaneously retarding the web at this position.

2. A method in accordance with Claim 1, in which the retarding of the web is accomplished by rounded-off coverings of link members, acting in conjunction with brake-rods, deflecting rollers or divided rollers.

3. Apparatus for the straightening of webs of woven material in the weft direction comprising a regulating unit having positionally-variable link members which perform translatory and rotary motions and which are pivotally connected lifting elements arranged to receive command signals, which signals are determined by measurement units responsive to the web, the arrangement being such that in use the regulating unit produces a variable extension of the web travel and simultaneously retards the web.

4. Apparatus in accordance with Claim 3, in which the lifting elements engage the link members at their pivot points.

5. Apparatus in accordance with Claim 3, in which the lifting members pivotally engage the link members at their centres.

6. Apparatus in accordance with Claim 3, in which the lifting elements are movable only in the vertical direction and the link members, to enable an inclined position to be attained, are supported at the pivot points to both rotate and move lengthwise.

7. Apparatus in accordance with Claim 5 or Claim 6, in which the link members comprise two telescopic parts which are urged outwards from one another by a compression spring.

8. Apparatus in accordance with Claim 3, in which the link members are pivoted on one pin only, the inclination of the link members being made possible by swinging links between the lifting elements and the regulating linkmembers.

9. Apparatus in accordance with Claim 3, in which the inclined position of the link members is attained through lifting elements which are pivotmounted.

10. Apparatus in accordance with Claim 9, in which rounded-off coverings of the link members are in permanent contact with the surface of the respective member.

11. Apparatus in accordance with Claim 9, in which gaps which occur in the coverings at the pivot points are bridged by segments of spheres.

12. Apparatus in accordance with Claim 3, in which the elements of the regulating mechanism are opposite to two brake-bars.

13. Apparatus in accordance with Claim 12, in which the web is urged between the brake-bars by the regulating elements in response to the control unit, whereby the web is moved to produce a lengthening of the travel, and as necessary, subjected to an increased retarding force.

14. A method according to Claim 1, in which the web is transported from a regulating unit controlled by lifting elements and operable in conjunction with a scanning unit and a web tensioning device.

15. Apparatus according to Claim 3, in which the lifting elements are operable in conjunction with a web tensioning device, and a scanning unit.

16. Apparatus according to any of claims 3 to 15, in which the signals are received through a processing calculator.

17. A method for the straightening of webs of woven material in the weft direction as claimed in Claim 1 and substantially as hereinbefore described.

18. Apparatus for straightening of webs of woven material in the weft direction, substantially as hereinbefore described with reference to Figure 1, or Figure 2, or Figure 3, or Figure 4, or Figures 5 and 6, or Figures 7 and 8, or Figures 9 and 10, or Figure 10a, or Figures 11 and 12, or Figures 13to 15, or Figures 16,17 and 17a, or Figures 18 to 20, of the accompanying drawings.