US2492737A

US2492737A - Photoelectric weft straightener

Info

Publication number: US2492737A
Application number: US19677A
Authority: US
Inventors: George B Dunn
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1948-04-08
Filing date: 1948-04-08
Publication date: 1949-12-27
Anticipated expiration: 1966-12-27

Description

2 Sheets-Sheet 1 J7 sa Hafel'ff MER G. B. DUNN Fligl.

Dec. 27, 1949 PHOTOELECTRIC WEFT STRA'IGHTENER Filed April s, 1948 Inventor George B. Dunn, bg wa Md.

His Attor'nag.

Dec. 27, 1949 G, B, DUNN PBo'roELEcTRIc wEFT STRAIGHTENER Filed April 8, 1948 WEFT THREADS WEI-'T' THREADS WEFT THREADS Inventor'. George B. Dunn,

bg FA is Attorneg.

Patented Dec. 27, 1949 George B. Dunn,

General Electric Company,

New York Schenectady, N. Y., assignor to a corporation of Application April s, 194s, serial No. 19,677

(ci. afs-52) c claims. l

This invention relates to apparatus utilized in the manufacture of woven'material, more particularly to apparatus for straightening the weft of woven fabrics, i.' e., producing rectilinearity of the weft threads and a perpendicular relationship between the weft threads and the warp threads, and an object of this invention is the provision of a simple, reliable, inexpensive and improved device of this character.

A further object of the invention is the provision in apparatus of the character described of a very simple, inexpensive and compact scanning device for detecting conditions of bow, skew and non-rectilinearity of weft threads in woven material.

In carrying the invention into effect in one form thereof, means are provided for projecting two beams of parallel light rays on a length of Woven fabric so that the beams are directed toward opposite edges of the fabric. The direction of each beam is such that it makes an acute angle with its own Orthographie or perpendicular projection on the plane of the fabric. Each of these perpendicular projections in turn makes an acute angle with a line in the plane of the fabric perpendicular to the warp. On the opposite side of the fabric from the light sources are mounted two photoelectric cells. Each is mounted in a position to receive light from a corresponding beam transmitted through the fabric. The cells are connected in corresponding arms of a bridge circuit. When the weft threads are straight and are perpendicular to the Warp threads, the bridge is balanced and its output voltage is zero. If any skew or bow is present, the cells receive unequal amounts of light, and a voltage appears at-the output terminals. control a suitable device to position the weft threads with respect to the warp threads to correct the bow or skew.

For a better and more completel understanding of the invention reference should now be had to the following specification and to the accompanying drawing of which Fig. 1 is a simple diagrammatic sketch of an embodiment of the invention used to remove skew from a wovenfabric; Fig. 2 is a sketch of a photoelectric scanning device; Figs. 3-8, inclusive, are diagrammatic sketches of different conditions of skew of the woven material which facilitate an under standing of the operation of the invention; Fig. 9 is a diagrammatic sketch of an embodiment of the invention which is useful in removing bow from This voltage is utilized to a woven fabric; and Fig. 10 is a chart of diagram- 55 i on the material.

rected toward one edge of the material and the matic sketches which illustrate the mechanical operation of the bow correcting device.

Referring now to the drawings, a length of woven material I is passed between a pair of mangle rolls 2, under an idler roll 3, over a canting roll 4, under an idler roll 5 and thence into a tenter having endless chains 6 and 1. These chains pass around end pulleys 8 and 8 which are driven by suitable driving means such as an electric motor I0 to which they are mechanically connected. The tenter chains are thus driven at equal speeds.

The canting roll 4 is journaled for rotation in bearing blocks II and II'. These bearing blocks are connected through links I2 and I3 with nuts I4 and I5 which are threaded on the screw shaft I6 which may be rotated in either direction by means of an electric motor I'I to which it is connected through gearing I8. If the material approaching the tenter is skewed, the skew can be corrected by rotation of motor II in the proper direction toelevate one end of the canting roll and to lower the opposite end.

The energization and direction of rotation of the correcting motor I'I is controlled by skew detecting means which is illustrated as comprising a pair of light sources I9 and 20 and a pair of photoelectric cells 2| and 22. Each source is provided with a suitable optical system for projecting a beam of substantially parallel rays ol light. The source I9 is mounted above one edge of the material and the source 20 is mounted above the opposite edge. The sources are so positioned that they project oppositely directed beams As shown, the beam 23 is dibeam 24 is directed toward the opposite edge.

The beam 23 makes an acute angle 25 with its own orthographic projection 23a on the plane of the material, and the beam 24 makes an acute angle 26 with its orthographic projection 24a on the plane of the material. These angular relationships are illustrated in Fig. 2. The angles 25 and'26 are substantially equal. The magnitude of the angle is determined by the material. There is an optimum angle for each material. For some materials the angle may be as small as twenty degrees and for others it may be as large as sixty degrees and for still other materials it may be some angle between twenty and sixty degrees.

J Similarly, these projections 23a and 24a make acute angles 21 and 28 with a line 29 in the plane of the material which is perpendicular to the warp threads. The angles 21 and 28 are also substantially Aequal and their magnitude depends upon the material. There is an optimum angle for each material. For most materials the value of this optimum angle is between twentyve degrees and sixty degrees.

The photoelectrie cell 2| is positioned on the axis of the beam 24 so that it receives the light rays of this beam which are transmitted through the material. Similarly the photoelectric cell 22 is positioned on the axis of the beam 23 so that it receives the light rays of beam 23 which are transmitted through the material.

The diameter of the beam will depend upon the dimensions of the photoelectric cell. For most types of photoelectric cells Vcurrently available, a beam of 2-3" diameter may be employed. The beam will produce an illuminated spot on the fabric which is elliptical in shape.

Each of the photoelectric cells 2| and 22 is connected in a corresponding arm of a bridge Ill of which the third and fourth arms are represented by the resistors 3| and 32. A direct voltage of substantially constant value is supplied to the input terminals 30a and 30h of the bridge from a source of regulated voltage which is represented by the two

supply conductors

33 and 34. The

output terminals

30c and 30d of the bridge are connected to the input control terminals 35a and 35h of a balanced electric valve amplifier 35. Direct voltage is supplied to the power input terminals 35e and 35d of the amplifier from a suitable source such as the

supply conductors

33 and 34. The output terminals 35e. 35i, 35g and 35h of the amplifier are connected to the control input terminals 36a, 36h, 36e and 36d of a balanced power amplier 36. Alternating voltage is supplied tc the power input terminals 36e and 36j from a suitable source such as the two supply conductors 31 and 38. The power output terminals 36g and 36h are connected to the armature of the skew correction motor I'I.

When the bridge is balancedyi. e. when the photoelectric cells 2| and 22 receive substantially equal amounts of light, the voltage across the

output terminals

30c and 30d of the bridge is zero. Consequently the voltage at the output terminal 35e and 35f of the ampliiier is equal to the voltage at the terminals 35g and 35h. As a result both paths of the power amplifier are equally energized. The current in each path is rectiiied half wave, and these currents are supplied to the motor armature in opposite directions so that the net energization of the motor I1 is zero and the motor is at standstill. The magnitudes o! the balanced output voltages of amplifier 35 are relatively low and the opposing circulating currents in the motor armature are correspondingly low.

When the bridge becomes unbalanced in one direction, i. e. when photoelectric cell 2| receives more light than photoelectric cell 22 receives, the current in one path of the power amplier is increased and the current in the second path is reduced to zero, with the result that the motor rotates in a corresponding direction. Ii* the bridge becomes unbalanced in the reverse direction, the current in the second path is increased and the current in the rst path is reduced to zero and the motor rotates in the reverse direction.

The appearance of the warp and weft threads when the material has no skew is illustrated in Fig. 3. If the light spot upon which the beam falls is viewed from the position of light source I9. i. e. along the'axis of the beam 23, the appearance of the warp and weft threads in the area within the spot illuminated by the beam is as illustrated in the enlarged view shown in Fig. 4. Invother words, Fig. 4 illustrates the "appearance of the warp and weft threads to the beam 24 when the material has no skew. It is clear that there are substantial spaces between the threads through which light is transmitted to the photoelectric cell 2|. The appearance to the beam 23 is similar. The spaces through which light is transmitted are equal for both beams and consequently both cells 2| and 22 receive equal amounts of light with the result that the bridge is balanced and the correction motor I1 is at standstill.

If there is positive skew in the material, as illustrated in Fig. 5, the appearance of the warp and weft threads to the beam 24 is as illustrated in the enlargement of Fig. 6. The spaces through which light is transmitted are much reduced in size and correspondingly less light is transmitted4 through the material to the photoelectric cell 2|.

0n the other hand, if the material has negative skew, as illustrated in Fig. '7, the appearance of the warp and weft threads to the beam 24 is as illustrated in Fig. 8. The spaces between the threads through which light rays of beam 24 are transmitted to photoelectric cell 2| are larger than the spaces in the no skew condition illustrated in Fig. 4. Consequently more light is transmitted to the photoelectric cell 2| than is transmitted during the condition of no skew.

To the beam 23 the appearance of the weft and warp threads during conditions of positive and negative skew is the reverse of their appearance to the beam 24. In other words, when the material has positive skew, as in Fig. 5, the appearance of the threads to the beam 23 is as illustrated in Fig. 8 and when the material has negative skew the appearance of the threads to the beam 23 is as illustrated in Fig. 6.

Thus, when the material has positive skew, the light received by the photoelectric cell 22 is increased and the light received by the photoelectric cell V2| is decreased. As a result the bridge 30 is unbalanced and the correction motor is energized for rotation in a direction to elevate the left-hand end of the canting roll 4, as viewed from the position of the mangle rolls 2, and to lower its right-hand end. This movement of the canting roll retards thev left-hand selvage of the material and permits the right-hand selvage to advance. By left-hand selvage is meant the selvage which is on the left of an observer looking in the direction of travel of the fabric. This correcting operation continues until the skew is removed from' the material and the amounts of light received by photoelectric cells 2| and 22 are equal so that the bridge 30 is rebalanced and the correction motor is stopped. Similarly when the material has negative skew, the bridge becomes unbalanced in the opposite direction electrically, and the correction motor |`l is energized for rotation in a direction to elevate the righthand end of the canting roll and to lower the leithand end to retard the right-hand selvage and advance the left-hand selvage. The operation continues until skew is removed so that the bridge 30 is again balanced and the correction motor is stopped. It is not essential that the beams be directed on diierent areas, as illustrated in Figs. 1 and 2. They may be directed on the same area. This has the advantage that errors are eliminated which might arise if one beam falls on an area having a given design or color and the other beam falls on an area having a different design or color.

terial passes over an idling roll 53, beneath the bowed roll 39, over the bowed roll 39a and beneath an idling roll 54, as illustrated in Figs. 9 and 10.

The dotted line la in diagrams, a, b and c of Fig. 10 represents the warp at the selvages and the full line Ib represents the warp at the center of the material. When the bowed rolls are in the positions illustrated in Fig. 10a, the selvages travel the distance a between the bowed rolls, and the center travels the shorter distance b. Since the selvages must travel the longer distance in passing through the corrector, they become advanced with respect to the center, and forward bow in the material is corrected.

In Fig. 10b the distances a and b are equal. Therefore the selvages and the center travel equal distances in passing through the corrector and no correction results This is the neutral position.

When the bowed rolls occupy the positions illustrated in Fig. 10c, the distance b which the center of the material must travel is greater than the distance a which the selvages travel. Consequently the center becomes advanced with respect to the selvages and rearward bow is corrected. Any other suitable bow eliminating device may be utilized in place of the device 39. For example, the bow eliminator illustrated in Fig. 1 of U. S. Patent 2,106,611, La Pierre, may be utilized if desired.

As shown in Fig. 9, the motor 42 is supplied from a power amplifier 44 which is controlled by an amplifier 45. The amplier 45 in turn is controlled by a bridge 46. A photoelectric cell 41 is connected in one arm of the bridge and a photoelectric cell 48 is connected in another arm.

These photoelectric cells 41 and 48 together with light sources 49 and 50 are mounted with respect to the fabric in the manner illustrated in Fig. 9. -The source 49 projects a beam 5i which is transmitted through the fabric to the photoelectric cell 41. Similarly the light source 50 projects a light beam 52 which is transmitted through the fabric to the photoelectric cell 48. It will be noted that the beams 5| and 52 lie in substantially parallel planes whichare perpendicular to the plane of the fabric as contrasted to the skew detecting device in which the projected beams lie in intersecting vertical planes.

When there is no bow in the fabric the appearance of the threads in the areas illuminated by the beams, as viewed from the positions of the light sources, is as illustrated in Fig. 4. Consequently equal amounts of light from both beams are transmitted through the fabric to the photoelectric cells 41 and 48. The bridge is balanced and the correction motor 42 is at standstill. If forward bow is present in the fabric, as illustrated in Fig. 9, the appearance of the threads in the area illuminated by beam 5|, as viewed from the location of the light source 49, is as illus- .trated in Fig. 6. In other Words, the threads present a closed-up appearance to the beam, and the amount of light transmitted through the fabric to the photoelectric cell 41 is correspondingly reduced. On the other hand, the appearance of the threads in the area illuminated by the beam 52, as viewed from the position of light source 50, is as shown in Fig. 8. That is to say.

the threads present an open appearance to the beam and a correspondingly increased amount of light from the beam is transmitted through the fabric to photoelectric cell 48.

As a result of the increased amount of. light received by photoelectric cell 48 and the decreased amount of light falling on photoelectric cell 41, the bridge is unbalanced and the correction motor 42 is energized to rotate the bowed rolls 39 and 39a toward the positions illustrated in F'ig. 10a to eliminate the forward bow from thevweft threads of the fabric. When the bowed lrolls '39 and 39a have been rotated a suillcient amount to eliminate the forward bow the amounts of light received by both photoelectric cells are equal and the bridge is rebalanced. As a result, the correction motor is deenergized and stopped.

Although in accordance with the provisions of the patent statutes this invention is described as embodied in concrete form and the principle thereof has been explained together with the best mode in which it is now contemplated applying that principle, it will be understood that the elements shown and described are merely illustrative and that the invention is not limited thereto since alterations and modications will readily suggest themselves to persons skilled in the art without departing from the true spirit of this invention or from the scope of the annexed claims.

What I claim as new and desire to secure by Letters Patent of the United States is:

l. In a weft straightener for a length of material having warp threads and weft threads, means for projecting on the fabric two beams of light directed toward opposite edges of the fabric, each of said beams making an acute angle with its own perpendicular projection on the plane of the fabric and each of said projections making an acute angle with a line in the plane of the fabric perpendicular to the warp, photoelectric means responsive to the difference in the amounts of said beams transmitted through said fabric, and means controlled by said photoelectric means for moving said weft threads with respect to said warp threads.

2. In a weft straightener for a length of material having warp threads and weft threads.

means on one side of the plane of the fabric for projecting on the fabric two beams of light directed toward opposite edges of the fabric, each of said beams making an acute angle with its own perpendicular projection on the plane of the fabric and each of said projections making an acute angle with a line in the plane of the fabric perpendicular to the warp, a pair of photoelectric devices mounted on the opposite side of the plane of the fabric each in a position to receive light from a corresponding one of said beams transmitted through said fabric, and means controlled by said photoelectric devices for positioning the weft threads perpendicular to said warp threads. 3. In a weft straightener for a length of material having warp threads and weft threads, means for projecting on the fabric two beams of light directed toward opposite edges of the fabric, each of said beams making an angle of between twenty and sixty degrees with its own perpendicular projection on the plane of the fabric and each of said encara? projections making an angle of between twentyve and sixty degrees with a line in the plane of the fabric perpendicular to the warp, photoelectric means responsive to the difference in the amounts of said beams transmitted through said fabric, and means controlled by said photoelectric means for varying the position of said weft threads with respect to said warp threads.

4. In a weft straightener for a length of material having warp threads and weft threads, means for projecting onthe fabric two beams of light directed toward opposite edges of the fabric, each of said beams making an angle of between twenty and sixty degrees with itsA own perpendicular projection on the plane of the fabric and each of said projections making an angle of between twenty-tive and sixty degrees with a line in the plane of the fabric perpendicular to the warp, photoelectric means for measuring the amount of each of said beams transmitted through the fabric, and means controlled by said photoelectric means for varying the position of said weft threads with respect to warp threads in response to the dierence of said amounts of said beams transmitted through the fabric.

5. In a weft straightener for a length of material having warp threads and weft threads, means for projecting on the fabric two beams of light directed toward opposite edges of the fabric, each of said beams making an angle of between twenty and sixty degrees with its own perpendicular projection on the plane of the fabric and each of said projections making an angle of between twentyfive and sixty degrees with a line in the plane of the fabric perpendicular to the warp, photoelectric means responsive to the difference in the amounts of said beams transmitted through the fabric, and means controlled by said photoelectric means for positioning said weft threads perpendicular to said warp threads.

6. In a weft straightener for a length of material having warp threads and weft threads, means on one side of the plane of the fabric for projecting on the fabric two beams of light directed toward opposite edges of the fabric, each of said beams making an angle of between twenty and sixty degrees with its own perpendicular projection on the plane of the fabric and each of said projections making an angle or' between twentyve and sixty degrees with a line perpendicular to the warp, a pair of photoelectric devices mounted on the opposite side of the plane ofthe fabric each in a position to receive light from a corresponding one of said beams transmitted through said fabric, and means controlled by said photoelectric cells in response to the diierence in. the amounts of light received by said photoelectric cells for positioning said weft threads perpendicular to said Warp threads.

GEORGE B. DUNN.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 2,106,611 La Pierre Jan. 25, 1938 2,208,447 Berry July 16, 1940 2,219,213 Swain' Oct. 22, 1940 2,311,406 Manseld et al Feb.'16, 1943 2,427,753 Vose et al. Sept. 23, 1947