US2592039A - Apparatus for examining threads visually for defects - Google Patents

Description

April 1952 y JEAN-PAUL LAETSCH ETAL 2,592,039

APPARATUS F OR EXAMINING THREADS VISUALLY FOR DEFECTS Filed Sept. 4, 1947 r 2 SI-IEETfi-SI-IEET 1 INVENTORS. fi e ha Lae'fse/l BY pal/l Lhfy I A QWZM JEAN-PAUL LAETSCH ET AL- 2,592,039

April 8, 1952 APPARATUS FOR EXAMINING THREADS VISUALLY FOR DEFECTS 2 SHEETSSHEET 2 Filed Sept. 4, 1947 INVENTOR. deamPau/ Laelirc z -BY Paul LiT/j mm MW Patented Apr. 8, 1952 OFFICE APPARATUS FOR EXAMINING THREADS VISUALLY FOR DEFECTS Jean Paul Laetsch, Zurich, Switzerland, and Paul Litty, Guebwiller, France Application September 4, 1947, Serial N o. 77 2,190 In France September 9, 1946 9 Claims This invention relates to the visual examination or checking of threads and aims to provide an improved apparatus whereby threads can be examined visually in a continuous manner in order to reveal irregularities, the shaggy state, impurities or other defects.

One object of the invention is to provide means whereby the visual examination of threads may be carried out in a more efiicacious and convenient manner than hitherto.

Further objects and features of the invention will appear in the following specification and be pointed out in the claims, whilst others may be obvious to those versed in the art.

. For the visual examination of threads it has been a common practice to wind the thread in parallel spirals on plates or cartons. A carton, serving as a screen, was chosen of such a colour that it contrasted with the thread which was wound thereon in such a way as to facilitate checking, by synoptic comparison of consecutive spirals disposed at an appropriate distance from one another.

Extremely influenced I by changing lighting conditions of the surroundings, this method only allowed an incomplete examination of threads whatever might be the orientation that could be brought to be given to the wound carton with respect to the light. Moreover, the side of the threads applied against the winding carton always remained invisible to the eye. Besides, the examination was limited to the part of thread wound on the screen.

The present invention aims to overcome the diificulties, and is based in part upon a clear appreciation of the desiderata, and on the ways of achieving the latter hereinafter set forth.

To obtain an efficacious checking of the thread, it has now been found .necessary for it to be possible to examine it in optimum conditions of lighting, independent of all outside influence, over an unlimited length and on all its surfaces. It has further been ascertained that to examine a thread in the room, arranged before a screen at a certain distance from this latter, the site of the source of light has a great influence. Thus to reveal irregularities such as cuts, bulky threads .or others, it has been found advantageous to light the thread by rays striking it transversely, whilst lighting in the longitudinal direction allows of recognising the existence of impurities such as husks, knobs and the like in a manner more practical to the eye of the observer. By giving the thread a translatory movement, limitless-lengths thereof can be examined and the examination can be carried-out in a more complete manner than if the thread remains immobile. This translatory movement is preferably such that two consecutive parallel helices move in opposite directions.

The practical realisation, either separately, or in combination one with another, of the different conditions for a proper examination of the threads is the subject of the present invention.

This contemplates apparatus according to which the thread to be examined is animated by the aforesaid movements, by means of the suitable arrangement of guiding and drawing parts in a casing artificially lighted and preferably arranged in a darkened locality.

The annexed diagrammatic drawing, comprising three figures, shows by way of example, a form of execution of an apparatus by means of which it is possible to obtain a visual check of the thread with all the desired precision and under the most imprdved convenient conditions.

Fig. 1 shows this apparatus in elevation,

Fig. 2 is a side sectional View, and

Fig. 3 is a plan view.

The various members are housed in a casing I, provided at the front with window-shutters 2 (Fig. 3) pivoting about an axis 3. These window-shutters, when closed, leave a free space or viewing opening 4 in front of the screen 5 which is interchangeably mounted, for example in guides 6. The thread to beexamined proceeding from a spool 1, arranged on a spindle 8, is led over a thread brake or tensioner 9 and a guide Ill on to roller H and thence across two pairs of combs l2 and 13 on to and around a second roller M, then back and again around the roller l I, thence forwardly and again around the roller l4, etc., until there exists in front of the screen 5 a plurality of parallel rows of threads. The roller I4 is driven from a driving shaft l5 by means of intermeshing gears I6 and H. The outgoing thread is passed across the thread-guide I8 and is coiled on a spool IQ of which the rotation is ensured simply by pressure on cylinder 20 of the driving shaft [5. The spool I9 is mounted for reciprocating movement in the direction of its axis for which purpose said spool is carried by a rod 23 which is provided with two fingers 22 between which is received a pin or spur 2| carried by a rotary disk 24, the latter having worm teeth which mesh with a worm 25 on the driving shaft 15.

The driving of the shaft l5 can be effected, either by hand by means of a crank not shown in the drawing, or by an electric motor connected for example by a belt to the pulley 26. The drive may be continuous or intermittent. The speed of passage of the thread in front of the screen can be regulated in known conditions, by means of a rheostat for example.

Between the pairs of combs l2 and I3, the thread bears on smooth bars 21 preferably of glass. The teeth of the comb l3 are staggered in relation to those of the comb l2 to compel the thread to bear always on the same side of the teeth and thus ensure a perfect parallelism of the various rows of thread between them.

Between the combs I3 the rows of thread are freely suspended, the screen being the background. It results from this arrangement that the thread, under the influence of its own torsion, turns more or less about its axis, thus exhibiting its various surfaces to the observer.

The combs l2 and I3 ensuring parallelism of the various rows of threads between them, as well as the bars 21, or the rollers l l and I4, could be replaced, either by channelled rollers or rollers with ribs or swellings, or by guide pulleys or in any other useful manner. It is preferable to give the adjacent rows of thread a translatory movement in opposite directions and for this purpose the thread, after leaving the guide It, is led through the two sets of combs l2, l3 and then around the roller l4 and back through the two sets of combs and around the roller H, and thence again through the two sets of combs and around the roller I4, etc. With this manner of threading up the device, each stretch or length of thread between the two pairs of combs and which is situated in front of the screen 5, is travelling in a direction opposite to that of the adjacent thread.

Another Way of threading up the device would be to lead the thread around the roller 14 and then back of the screen 5 and around the roller 1 I, and then pass the thread through the combs l2 and I3 and around the roller I 4 again and then lead the thread to the roller ll back of the screen, etc. With this manner of threading up the device all of the thread sections in front of the screen will be travelling in the same direction.

To facilitate threading of the device the combs 13 are shown as being pivotally mounted in their supports so that they can be turned into the position shown by dotted lines l3 in Fig. 3. Furthermore, the support 40 for the guiding system ll, I2, l3, I4, 21, is pivotally mounted on supporting brackets 4| as shown at 29, thereby permitting the assembly to be turned in the direction of the arrow C from its operative vertical position shown in full lines Fig. 2 into an inclined position shown in dotted lines.

When a spool is exhausted or is replaced by another, the work of threading can be dispensed with, if care has been taken to attach the thread from one spool to another.

The turning down of the comb l3 can be effected by acting on the knob 30 in such a manner as to disengage a retaining cog urged by a spring 3|, which also serves to keep the comb I3 in a staggered position with respect to the comb [2.

The lighting of the thread passing before the screen 5 is ensured by two sources of illumination 32, arranged on either side of the field of examination and rendered invisible to the observer by means of the window-shutters 2.

A clapper or shield 34, controlled from a distance and pivoting about an axis 33 of a fixed wall 35, allows of illuminating the thread to be examined, either directly in the longitudinal direction, or indirectly in an inclined transverse direction. In the first case, supposing the clapper 34 is in the full line position Fig. 3, the light rays R emanating from the source 32, sweep the threads in the direction of their axes or length as indicated by the arrows R. In the case the clapper is in the dotted line position 34 the light rays R are directed towards the interior surface of the window shutter 2 and reflected in the direction R" onto the surface of the field of examination at an angle to the axes or longitudinal direction of the threads.

It is noted that, in the two cases, the background screen 5 forms a contrast with the thread bathed in light. In the case of the direct illumination the rays R do not reach the screen, this latter remaining dark, owing to the walls 36 which prevent their passage.

According to whether it be desired to obtain more or less marked contrasts, use can be made of screens of various colours.

The installation above described presents a single field of examination. It is possible, in the same casing, to superpose several fields of examination in such a manner as to be able to control simultaneously the thread from several spools. Mere duplication or multiplication of parts for dealing with several threads instead of a single one, is not excluded by the claims referring more especially to the simpler form illustrated by way of example.

It will be obvious to those versed in the art that the invention is susceptible of various changes in the shape, construction and means of support of its various elements wtihout departing from the scope and spirit of the appended claims.

We claim:

1. Visual thread examining apparatus comrising the combination of a casing with a viewing opening at the front, a screen mounted in said casing, thread feeding, supporting and guidirig means within said casing leading said thread in a continuous manner in parallel rows in front of said screen, sources of light mounted within and at each side of said casing, moveable clappers operable at will into two positions, said clappers in one position allowing direct light rays from said sources in the longitudinal direction of the parallel rows of thread to illuminate them directly endwise, whilst intercepting rays which in the other position of said clappers give frontal illumination of the thread by reflection from interior front surfaces in the casing.

2. Visual thread examining apparatus comprising the combination of a casing, windowshutters forming the front of said casing and leaving a viewing opening, a screen interchangeably mounted in said casing, thread feeding, supporting and guiding means within said casing leading said thread in a continuous manner in parallel rows in front of said screen, sources of light disposed in said casing and means controlling the light rays emanating therefrom to cause illumination of the rows of thread in the field of examination selectively at will either in the direction of their axes or in a direction at an angle thereto, the thread in parallel rows before the screen having controllable translator-y movement and being so associated with appropriate guiding members of the thread feeding system that the various parallel rows are so propelled that two consecutive rows move in opposite directions.

3. Visual thread 'e'xamining apparatus comprising th combination of a casing, windowshutters forming the front of said casing and leaving a viewing opening, a screen interchangeably mounted in said casing, thread feeding, supporting and guiding means within said casing leading said thread in a continuous manner in parallel rows in front of said screen, sources of light disposed in "said casing and means controlling the light rays-emanating therefrom to cause illumination of the rows of thread in the field of examination selectively at will either in the direction of their axes or in a direction at an angle thereto, the thread in parallel rows before the screen having controllable translatory movement and being so associated with appropriate guiding members of the thread feeding system that the various parallel rows are so propelled that each row is displaced in an opposite direction to that in which an adjacent row is displaced.

4. Visual thread examining apparatus comprising the combination of a casing, windowshutters forming the front of said casin nd leaving a viewing opening, a screen interchangeably mounted in said casing, thread feeding, supporting and guiding means within said casing leading said thread in a continuous manner in parallel rows in front of said screen, Sources of light disposed in said casing and means controlling the light rays emanating therefrom to illuminate the rows of thread in the field of examination before said screen selectively at will either in the direction of their axes or at an angle thereto, the rows of thread being maintained rigorously parallel by said guiding means comprising guides in the form of two groups of combs disposed respectively at the entrance and exit of the observation field, the combs in each of these groups being staggered with respect to one another constraining the thread to bear constantly on the same side of the comb teeth.

5. Visual thread examining apparatus as in claim 4, wherein one of the combs of each group is mounted to be lowerable from the net of the rows of thread thereby facilitating threading the latter.

6. In visual thread examining apparatus, the combination with a casing having a viewing opening, of a screen mounted in said casing in position to be viewed through said opening, thread feeding, supporting and guiding means having provision for holding a continuous length of thread in parallel rows between said screen and opening and for feeding said thread forwardly, a source of light mounted within the casing and positioned to direct light on to the rows of threads in the direction of their length, a reflector positioned to reflect light from said source of light frontally on to the rows of threads, a shield movable at the will of the operator into either one of two positions, in one of which positions it cuts off from the reflector the light from the source of light while permitting light from said source to illuminate the rows of threads in the direction of their length, and in the-other of which positions it intercepts the light projected from the source of light in the direction of the length of the threads while permitting projection of light from the source of light on to the reflector which reflects the light on to said rows of threads from the front, whereby the thread may be examined through the viewing opening under optimum lighting conditions and without any exterior illumination.

of thread in parallel rows between said screen and said opening and with the section of thread forming each row supported at its ends only and being. freely suspended between said ends, said means feeding the thread in the direction of its length, a source of light within the casing at each side of said opening and positioned to project light on to the rows of thread in the direction of their length, a reflector at each side of said opening to reflect light from the corresponding light source frontally on to the rows of threads, a shield at each side of the opening movable at the will of the operator into either one of two positions, in one of which positions it cuts off from the corresponding reflector the light from the corresponding source of light while permitting light from said source to illuminate the rows of threads in the direction of their length and in the other of which positions it intercepts the light projected from the corresponding light source in the direction of the length of the rows of threads while permitting projection of light from said source on to the corresponding reflector which reflects the light on to the rows of threads from the front, whereby the thread may be examined throu h the viewing opening under optimum lighting conditions and without any exterior illumination.

8. Visual thread examining apparatus comprising a casing, two window-shutters forming the front of the casing and spaced apart to form between them a viewing opening, a screen within the casing in position to be seen through the viewing opening, thread feeding, supporting and guiding means having provision for holding a continuous length of thread in parallel rows between said screen and said opening and for feeding said thread forwardly, a source of light within the casing at each side of said opening and positioned to project light on to the rows of thread in the direction of their length, the inner face of each window-shutter constituting a reflector to reflect light from the corresponding source of light on to the rows of threads from the front, a shield at each side of the viewing opening movable at the will of the operator into either one of two positions, in one of which positions it cuts off from the reflecting surface of the correspondin window-shutter the light from the corresponding source of light While permitting light from said source to illuminate the rows of threads in the direction of their length, and in the other of which positions it intercepts the light projected from the corresponding light source in the direction of the length of the rows of threads while permitting projection of light from said source on to the reflecting surface of the corresponding window-shutter, which surface reflects the light on to the rows of thread from the front.

9. Visual thread examining apparatus of the character described comprisin a casing having a viewing opening, a screen within said casing in position to be viewed through said viewing opening, thread guiding and supporting members for supporting the thread in front of the screen in horizontal parallel rows arranged in a vertical plane, supporting brackets within the casing above the thread guiding and supporting members, and means for pivotally suspending the thread guiding and supporting members Irom UNITED STATES PATENTS said brackets, whereby said thread guiding and supporting members can be swung forwardly Number Name Date about their pivotal support to facilitate the J H h: 1924 threading operation, 5 1,721 8 lhzham uly 23, 9 JEAN PAUL LAETSCH; 1,930,077 Bentley Oct. 10, 1933 PAUL LITTY 2,105,715 Birch Jan. 18, 1938 2,376,773 May 22, 1945 REFERENCES CITED 2,412,381 Dec. 10, 1946 The following references are 0! record in the W file of this patent:

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