Title:
Device to detect skew in fabrics
United States Patent 2355465


Abstract:
This invention relates to the textile art and more especially to a device for detecting skew of the weft strands of woven fabrics. In the art of manufacturing textiles it is common practice to pass the fabric through one or more tenter frames, the purpose of which is well known. As the fabric...



Inventors:
Oberkirk, William C.
Application Number:
US50469743A
Publication Date:
08/08/1944
Filing Date:
10/02/1943
Assignee:
UNITED MERCHANTS & MFG
Primary Class:
Other Classes:
26/51.5, 250/559.37, 356/23, 356/391, 356/398, 356/429
International Classes:
D06H3/12
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Description:

This invention relates to the textile art and more especially to a device for detecting skew of the weft strands of woven fabrics.

In the art of manufacturing textiles it is common practice to pass the fabric through one or more tenter frames, the purpose of which is well known. As the fabric continuously passes through these frames it is grabbed by the fingers thereof and stretched laterally. This action is apt to throw the weft strands out of their desired relation perpendicular to the longitudinal axis of the fabric and perpendicular to the warp strands.

Means are available and used in the art for the purpose of preventing this distortion or skew.

Such means are known and need not be described in detail since they do not form part of the present invention. For purposes of identification, reference may be had to United States Patents 2,209,220, 2,106,611, 2,106,612, and 2,311,406, which describe certain forms of the devices mentioned. While such devices are useful, they can not be depended upon completely to prevent skew.

It is an object of the present invention to devise apparatus which will enable skew to be readily detected. The apparatus of the present invention may be employed in conjunction with the above mentioned skew controlling device, or independently thereof.

In accordance with the present invention, the fabric may be continuously passed in sheet form from a tenter frame to a place of disposal at a predetermined linear speed, and in the course of this passage may be inspected for skew distortion. For this purpose and in accordance with the invention, selected areas of each of the opposite edge portions of said fabric are illuminated by a series of light flashes of controllable frequency. These flashes may be emitted from h', gaseous discharge lamp by discharging an electric current through the gaseous filling of said lamp at a controlled frequency. The light from each of the illuminated areas may then be projected on any suitable viewing means such as a screen, and said light directed from said areas so that the pair of images of the weft strand at opposite sides of said fabric are grouped in closely juxtaposed positions visible to the eye of an observer. By suitably correlating the frequency of the light flashes with the speed of travel of the web or fabric, the images of the weft threads cast upon the screen may appear stationary or moving at such a low rate of speed as to be clearly visible, and by juxtaposing the image of the weft threads of one edge of the fabric with those of other, any skew or distortion will be readily apparent. In the absence of distortion the lines of the images corresponding to the weft threads at opposite edges of the fabric will be substantially aligned, The presence of skew or distortion is indicated by an offset relation of the lines of the pairs of images.

The principles of the invention will be defined in the claims and illustrated by the following description taken in conjunction with the accompanying drawing, in which: Fig. 1 shows diagrammatically a train of fabric treating apparatus including an embodiment of the present invention; Fig. 2 is an enlarged diagrammatic sectional view taken on the line 2-2 of Fig. 1; Fig. 3 is a diagrammatic view of a pair of images of the weft threads at opposite edges of the fabric when the weft strands are properly arranged and aligned; and Fig. 4 is a diagrammatic view showing a pair of images of the weft threads at opposite edges of the fabric when the weft threads are skewed or distorted.

Referring first to Fig. 1, this is essentially a flow sheet or diagrammatic view showing a typical or specific treatment of fabric involving the use of tenter frames, in conjunction with which apparatus an embodiment of the invention is diagrammatically indicated at the extreme left, it being understood that this view shows merely one of the many instances in which the invention as disclosed and claimed herein may be utilized. The fabric I passes from an accumulation 2 thereof through a mangle 5 provided with treatment rolls 6, in which the fabric may be subjected to treatment with any desirable finishing agent, and then to a straightening tenter frame 7, suitable guide rolls 9 being employed to direct the fabric. A skew controlling device indicated generally at 10 may be provided with the object of automatically preventing skew and enabling the tenter frame to straighten out the weft threads or strands.

The fabric then passes over guide roll 12 and drying cans 14 and then passes, via guide rolls 15, to a finishing tenter frame 17 provided with a hot air drier 18, the tenter frame 17 being provided with drive motor 19. The fabric then passes over guide rolls 20, 21, 22 and is taken up on accumulation roll 23. Intermediate the rolls 22 and 23 the inspection and detection device of the present invention is employed, that device being further shown in Fig. 2. Opposite each of the edges 26 and 27 of the fabric or web 1, there are arranged a pair of stroboscope lamps 28. Such lamps per se are known and the structure need not be described in detail except to state that they commonly include a transparent envelope containing a rare gas or mixture of gases and provided with electrodes connected to a source of discontinuous electric current, usually alternating, the frequency of which is controllable by the timer 30, current being delivered to the lamp through leads 31, 32, and 33. Between the lamps 28 and the edges 26, 27, condensing lens means, indicated generally by 34, are arranged. The lens means 34 concentrates light from the lamp 28 so that a beam of light is directed transversely of the fabric I through the interstices between the strands at the areas at the edges 26 and 27 thereof. On the other side of the fabric opposite the lamps 28, means are provided to pick up the transmitted light and project images of the warp and weft threads and direct two pairs of images thus produced so that they are visible to the eye of an observer in closely juxtaposed position. This means may comprise a telescopic apparatus indicated generally as 36. This comprises a tube 31 with projecting lens means indicated generally as 38 at each of the two ends thereof. As shown in Fig. 2, those ends may be continuations of the tube 37, the axes of said ends being transverse to the axis of the tube 37, the axis of which, as specifically shown in Fig. 2, is perpendicular to the longitudinal axis of the fabric I and substantially parallel to the plane of said fabric. Intermediate the ends of the tube 37 the tube 39 projects therefrom at right angles, at one end of which there is provided a viewing screen 40. The tube 39 may have a wall or diaphragm 41 extending longitudinally thereof and dividing it into substantially two passageways. Reflectors 43 direct the light emitted by the lamps 28 and transmitted through the interstices of the fabric I and through the projection lens means 38 on the screen 40 so that images of the weft and warp strands at the edges 26 and 27 are grouped on said screen in closely juxtaposed position readily visible to the eye of the observer. Any suitable magnification of the strands may be effected by means of the lens system in a manner which will be clear. At 45, there is diagrammatically shown a telescopic construction to permit focusing adjustment and at 46, a similar construction to provide lateral adjustment of the tube 36 for focusing purposes and to accommodate different widths of fabric.

In the operation of the device, the operator, knowing the speed of travel of the fabric as it leaves the tenter frame 17 on its way to take-up roll 23, adjusts the frequency of the light flashes emitted by the lamps 28 so that the images of the warp and weft threads passed upon the viewing screen 40 either appear stationary or moving at such a low rate of speed as to be clearly visible as a series of lines, as indicated in Figs. 3 and 4. As above mentioned, distortion of the weft threads is indicated by the fact that the lines of the image of the weft threads of the edge 27 are offset in relation to the lines of the image of the weft threads of the edge 26. When such distortion is detected then steps may be immediately taken by known means to adjust the operation of the tenter frames to cure this condition.

It is to be understood that the eribodiment of the invention-specifically hereinabove described may be modified by those skilled in the art without departing from the principles of the invention as defined in the appended claims. For example, instead of employing light transmitted through the interstices of the fabric, the lamps 28 could be arranged on the same side of the fabric as that in which the telescopic apparatus 36 is positioned, in which case reflected light would be employed to produce images of the strands. It is preferred, however, to employ transmitted light.

I claim: 1. In conjunction with apparatus for finishing woven fabrics including a tenter frame and means to continuously pass the fabric in sheet form from the tenter frame to a place of disposal at a predetermined linear speed, a pair of stroboscopic lamps arranged on one side of said cloth, each of said lamps being adjacent an edge of said fabric; means to vary the frequency of the light flashes from said lamp in accordance with the speed of movement of said fabric, said lamps being 20. adapted to direct a series of light flashes of controllable frequency transversely of said fabric and through the interstices of the strands thereof; a tube having an axis substantially parallel to the plane of said fabric and positioned on the other side of said fabric and in adjacent spaced relation thereto; said tube having projection lens means at each end thereof opposite said lamps, image viewing means intermediate the ends and means to direct the projected pair of images of the warp and weft strands of the opposite edge portions of said fabric and to group said pair of images so that they are visible to the eye of an observer in closely juxtaposed position at the viewing means.

2. In conjunction with apparatus for finishing woven fabrics including a tenter frame and means to continuously pass the fabric in sheet form from the tenter frame to a place of disposal at a predetermined linear speed, a pair of stroboscopic lamps arranged on one side of said cloth and to project their beams through limited areas of the fabric spaced apart widthwise thereof; means to vary the frequency of the lightflashes from said lamp in accordance with the speed of movement Sof said fabric; a housing positioned on the other side of the fabric from said lamps and in adjacent spaced relation thereto; said housing having projection lens means at each end thereof opposite said lamps, image viewing means Intermediate the 5o ends and means to direct the projected pair of images of the warp and weft strands of said spaced apart areas and to group said pair of images so that they are visible to the eye of an observer in closely juxtaposed position at the viewing means.

3. In conjunction with apparatus for finishing woven fabrics including a tenter frame and means to continuously pass the fabric in sheet form from the tenter frame to a place of disposal at a predetermined linear speed, a pair of stroboscopic 0lamps arranged on one side of said cloth and to project their beams through limited areas of the fabric spaced apart widthwise thereof; means to vary the frequency of the light flashes from said lamp in accordance with the speed of movement of said fabric; means located on the other side of the fabric from said lamps to direct the light from the illuminated areas and to create images of the warp and weft threads of said areas; and means to group said images so as to be visible in closely juxtaposed position.

WILLIAM C. OBERKIRK.