US2875790A - Adjustable unwinding means for the warp beam in weaving looms - Google Patents

Description

March 3, 1959 WARP BEAM IN WEAVING LOOMS 5 Sheets-Sheet 1 Filed NOV. 1, 1956 w E m M N 7 n x m m W M o I N3 0 m 3 3 Q L P m. o M- o I l\ l P .wwt \Q Q Q A 9 J Q m QM o A o h a o N Filed Nov. 1, 1956 March 3, 1959 J. PICANOL 2,875,790

ADJUSTABLE UNWINDING MEANS FOR THE WARP BEAM IN WEAVING LOOMS 3 Sheets-Sheet 2 J. PLcanol/A/VE/WU/P new d w x A 7 TOPNEYJ March 3, 1959 2,875,790

' J. PICANOL" V ADJUSTABLE 'UNWINDING MEANS FOR THE WARP BEAM IN WEAVING LOOMS Filed Nov. 1, 1956 5 Sheets-Sheet s J.P(.canol, Ill/EH70]? .p pmduli United States Patent ADJUSTABLE UNWINDING MEANS FOR THE WARP BEAM IN WEAVING LOOMS Jaime Picanol, Zillebeke-lez-Ypres, Belgium Application November 1, 1956, Serial No. 619,791

Claims priority, application Belgium, December 17, 1955 4 Claims. (Cl. 139--108) In weaving looms it is, as is well known, indispensable to ensure, that the tension of the warp threads be maintained at a constant value, as well at the beginning as at the end of the unwinding of the warp beam, i. e., in fact at any slope of the threads between the warp beam and the back rest. It is also of paramount importance to keep said warp tension at a rigorously constant value, irrespective of whatever kind of weft is used for the fabric to be produced on the loom. All unwinding mechanisms hitherto known and applied in weaving looms aim at maintaining the warp tension at a constant value, and this aim is generally arrived at by means of critical and laborious adjustments of the various elements, which constitutes a difficult and time consuming task for the weaver foreman, particularly when a change of weft is to be executed.

A first object of the invention is concerned with a control mechanism for the unwinding of the warp beam, which enables to efiectuate a change of the weft by means of one single very simple operation involving only one easily accessible manual control element. This mechanism according to the invention is essentially characterised in that the spring to be controlled in order to adjust the warp tension in accordance with the weft to be applied, is connected between an element by which the back rest is positionally controlled, and a pivotable crank member, the connection between said spring and said pivotable member being shiftable on said member, so as to enable the positioning of the application point at various distances from the pivot point of said member, said pivotable crank member preferably carrying marks opposite each of the various points to which said connection may be shifted so as to permit practically instantaneous setting of said shiftable connection at the correct position in accordance with the weft to be executed.

A second object of the invention is concerned with means to be employed in order to ensure constant feed lengths of warp thread in spite of the progressively decreasing diameter of the warp beam, which constitutes another necessary condition for maintaining the warp tension at a constant value. For this purpose the aforementioned pivotable crank member is connected with the sensing member through the intermediary of a specially arranged mechanism forming part of the invention. Said mechanism is such as to transform the law of senser motion into another motional law of said crank member in such a way, that at any time the rate of angular displacement of the warp beam is changed in accordance with the progressively diminishing diameter of said warp beam, this arrangement being such as to maintain a constant warp feed up to the complete unwinding of the warp beam.

In this manner it is not only possible, with the aid of a previous adjustment, to comply with the requirements of various kinds of weft, but also the changes of the tension due to the progressive decrease of the warp beam diameter are automatically taken into account.

According to the invention said motion transforming mechanism may be of great simplicity, and may for instance consist of a crank secured to the sensing member of the warp beam, said crank being permanently held in operative engagement with a concave, preferably cylindrical surface of a bell crank lever, in which case the cooperating surfaces are very easy to machine. By a judicious choice of the relative positions of the pivot axes of the sensing member and of said concave surface respectively, and of the relation between the radius of curvature of said concave surface and the path of the crank part bearing against said curved surface, it is easy to achieve a. mathematically accurate transformation of the law of motion of the sensing member into such a movement of the mechanism controlling the un winding of the warp beam, that at any time the warp length fed from the latter is practically maintained at a constant value.

In fact, the concave surface acts, with respect to the crank secured to the sensing member, as a cam controlling the unwinding mechanism of the warp beam in accordance with the angular position of said sensing member.

Thus by means of the arrangement according to the invention a virtually perfect warp beam unwinding control means is achieved, in which any change of weft as well as the change of warp beam diameter are equally taken into account, in order to ensure practically perfect constancy of the tension in the warp threads.

The operating conditions, as defined above, characterising the unwinding mechanism, may be put into effect in many ways and by different means, differing particularly with respect to the way in which has been realised the rocking pivotable member and the shiftable coupling of the spring which controls the position of the back rest, and the shape and operation of the mechanism for transforming the senser motion as set forth.

In order to further illustrate the various characteristics of the invention, without limiting the scope of the invention thereto, an embodiment will be described hereinafter, with reference to the annexed drawings, wherein:

Figure 1 shows the main elements of the control mechanism controlling the unwinding of the warp beam, with their respective positions corresponding to the maximum diameter of the warp beam, and to a given kind of weft;

Figure 2 is similar to Figure 1, however with the mechanism in a position corresponding to minimum warp beam diameter, the weft being of the same nature as in the previous figure;

Figures 3 and 4 represent succinctly and in schematic form the members driving the unwinding mechanism in two characteristic positions both corresponding to a large warp beam diameter;

Figures 5 and 6 are similar to Figures 3 and 4 respectively, positions being shown as correspond to a smaller warp beam diameter;

Figure 7 represents the essential elements of the motion transforming mechanism.

In the embodiment shown, the mechanism for presenting the unwinding means in accordance with the Weft to be applied, comprises the back rest 1 journalled at both sides in the end portions of bell crank levers 2 pivotally mounted as at 3. The other crank of said bell crank lever 2 is coupled with a rocking lever 4 by means of a connecting rod 5. Said rocking lever 4 is at one end connected, through the intermediary of a spring 7, with a pull rod 6 carrying at its other end a head member 8, which may be made to bear on different points of a crank member 9, the latter being mounted on a pivot 10 so as to be able to perform a pivoting motion on said pivot 10. I By positioning said coupling head member 8 at various distances from the pivot point 10 of said pivotable crank member the pretension of the spring 7 may be varied in order to adjust the influence exerted by said spring via the rocking lever 4, the coupling rod and the pivotable bell crank 2, on the back rest. This adjustment is made in accordance with the weft of the fabric to be produced.

The mechanism controlling the back rest 1 in accord ance with the changing diameter of the warp beam comprises, in addition to the mechanism just described, a crank '11 secured to the warp beam sensing member 13 through the intermediary of the pivot 12. Said crank carries a projecting stud 14 in permanent operative contact with the concave surface of one arm of a bell crank lever 16 pivotally mounted as at 17, the other arm of said bell crank lever being connected to the aforementioned pivotable crank member 9 by means of arod 18. Said concave surface 15, with a radius of curvature =R, has its centre of curvature at a place which does not coincide with the pivot on which the crank 11 swings together with the warp beam sensing member 13. The distance and the relative position between said centre of curvature of the arched surface 15 and the pivot 12, as well as the distance and the relative position between the pivots 12 and 17 are such that the movement of the sensing element as the beam diameter progressively decreases, is transformed into a progressive motion of the back rest 1 in a Way as to ensure nearly'constant tension of the warp threads. In fact any angular displacement of the sensing member 13 causes an equal pivoting movement of the crank 11 and a proportional rotation of the stud 14 projecting from said crank, around the pivot 12. The path through which said stud moves being different from the curvature of the arched surface 15 of the bell crank lever 16, and said arched surface, due to the influence exerted by the spring 7 via the rod '6, pivotable crank member 9 and rod 18 on said bell crank lever 16, being positively urged against the stud projecting from said crank 11, it follows, that the bell crank lever 16 rotates on pivot 17, as the sensing member progresses along its arched path.

As any angular movement of said bell crank lever 16 is translated into a longitudinal movement of rod 18, said movement is transmitted to the pivotable crank member 9 and via the latter and the shiftable coupling head member 8 to the rod 6 and the rocking member 4. Now, the latter controls the warp beam driving mechanism. In fact, said rocking member 4 is permanently held in contact with a cam fixedly mounted on a rod 20 having a second cam 21 fixed thereon; a return spring 23 interconnects the latter with a fixed part 22 of the loom. Between both said cams 19 and 21 is disposed the free end 24 of a reciprocating rod 25 which is driven by a crank 26 engaged in an oscillating angular movement of constant amplitude around a fixed centre of rotation 27. Inasmuch as the oscillating angular movement of the crank has constant amplitude, it follows, that the reciprocating movement of the rod 25, as well as the limits of the rectilinear movement of the free end 24 of said rod 25, are likewise constant. During its backward stroke the rod 2425 will engage the cam 21, "and will move the same during the last part of said backward stroke, said cam 21, in turn, driving rod 20 and the unwinding mechanism of the warp beam. Said mechanism has schematically been indicated at 28, whilst th'e beam and its axis are shown at 29 and 30 respectively.

g, Consequently, as will appear from Figures 3 and 4, if the initial position of cam '21, as determined by the position of the sensingelenie11t 13, is as shown in Figure 3, the rod 24-25 will travel freely through a distance a, during the first part of its backward stroke.

thereafter will engage cam 21 and will move same through the remaining part of the stroke; it thus follows, that in this case the active part of the stroke is given by ii. The beam driving mechanism 28 will thus be acmated only during said part ('1' of theaters of rod Said . 4 24-25. Considering next the case indicated in Figures 5 and 6, it will be seen, that due to senser 13 being 'in a different position, cam 21 has been set to a position more to the left with respect to the initial setting, as corresponds with a displacement to the left of the rocking member 4 caused by an angular displacement of the pivotable crank member 9, bell crank lever 16 and crank 12, the latter being secured to the sensing member 13. The distance separating said cam 21 from the free end 24 of rod 25 has decreased, consequently the ineffective part 0! of the stroke of rod 2425 will also be smaller. The effective stroke d will be correspondingly greater, consequently the driving mechanism 28 will be actuated during a longer time interval than in the case corresponding with Figures 3 and 4. Thus by a suitable design of the mechanism for the transformation of the angular movement of the senser 13, it is possible to obtain a mathematically accurate control of the movement of the beam unwinding mechanism, and thus to regulate the feed movement in the wanted manner.

It Will be understood, that the various mechanisms described may be realised in many other ways, and that various changes as to the shape, size and the relative positions of the different elements may be resorted to, Without departing from the spirit of the invention or the scope of the subjoined claimsv What I claim is:

1. Adjustable warp beam unwinding mechanism for weavers loom, said loom comprising a back rest, said mechanism comprising means for driving said warp beam, a sensing element riding on the periphery of said warp beam and means for controlling the motion of said warp beam driving means in accordance with the instantaneous position of said sensing element and for simultaneously controlling the position of the back rest of the loom, means for transforming the motion of said sensing element into an adequate motion of said control means, a pivotable crank member controlled by said senser motion transforming means, a rocking member effectively connected with said back rest and adapted to control the setting of said warp beam drive control means, spring tensioned means connecting said rocking member with said pivotable crank member, said spring tensi'oned connecting means comprising a rod bearing with one end against a surface of said pivotable crank member.

2. Adjustable warp beam unwinding mechanism as claimed in claim 1, in which said pivotable crank member has, along one of its edges, suitably shaped bearing positions at various distances from its fulcrum, said bearing positions being adapted to receive, and to cooperate with, said end of said rod of said spring tensioned connecting means, said bearing positions being each associated with suitable markings on said crank member, whereby the setting of the application point of said spring tensioned connecting means at various distances from said fulcrum is facilitated.

3. Warp beam unwinding mechanism for weavers looms, comprising means for driving said warp beam, a sensing element controlled in accordance with the instantaneous diameter of the warp beam, a pivotable crank member, means for controlling the position of said pivotable crank member in accordance with the instantaneous position of said sensing element, a rocking member, spring tensioned means connecting said rocking member with said pivotable crank member, said spring tension'ed connecting means comprising a rod and said pivotable crank member being adapted to receive the end of said rod at various positions on one of its edge surfaces, at pivoted bell crank lever supporting the back rest of the loom, and means comprising a rod interconnecting said pivoted bell crank lever with said rocking member.

4. Warp beam unwinding mechanism for weavers loom, said loom comprising a back rest, said mechanism comprising means for driving said warp beam, a sensing element riding on the periphery of said warp beam, a crank secured to said sensing element and having a projecting element thereon, a pivotable bell crank lever having two arms and having its pivot at the junction of said arms, one or both said arms having a concave cylindrical surface thereon, said concave surface being kept in operative contact with said projecting element on said crank, a pivotable crank member, a rod connecting the other of said arms, of said bell crank lever with said pivotable crank member, a rocking member connected to the back rest of the loom, spring tensioned connecting means interconnecting said rocking member with said pivotable crank member, means for setting the point of application of said spring tensioned connecting means 15 on said pivotable crank member at various distances from the fulcrum of said pivotable crank member, a

driving mechanism oscillating with constant amplitude and comprising a reciprocating element, a rod controlling the warp beam driving means, said latter rod having two catch elements secured thereon, one of said catch elements being permanently kept in engagement with said rocking member, and the other catch. element being disposed in the path of said reciprocating element of said constant amplitude drive mechanism.

References Cited in the file of this patent UNITED STATES PATENTS 647,815 Draper et al. Apr. 17, 1900 1,758,738 Draper May 13, 1930 2,350,954 Brown June 6, 1944 2,369,889 Geddings Feb. 20, 1945

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