US3543808A

US3543808A - Process and apparatus for the laying of a pick into the shed of a loom

Info

Publication number: US3543808A
Application number: US705081A
Authority: US
Inventors: Albert E Moessinger
Original assignee: Individual
Current assignee: Individual
Priority date: 1968-02-13
Filing date: 1968-02-13
Publication date: 1970-12-01
Anticipated expiration: 1987-12-01

Description

United States Patent -Field of Search Albert E. Moessinger 1 Grand Place, Fribourg, Switzerland 705,081

Feb. 13, 1968 Dec. 1, 1970 Inventor Appl. No. Filed Patented PROCESS AND APPARATUS FOR THE LAYING OF -A PICK INTO THE SHED OF A LOOM 16 Claims, 25 Drawing Figs.

U.S. Cl 139/127 .....D03d47/l2 139/11, 116,122,123,l24,125,126,127,127(P) References Cited UNITED STATES PATENTS 5/1914 Brooks 3,050,088 8/1962 Schaffer 139/126 3,137,322 6/1964 TeStrake... 139/127(P) 3,140,633 7/1964 Vincent 139/127(P) FOREIGN PATENTS 326,127 3/1930 Great Britain 139/127 Primary Examiner-Henry S. .Iaudon Attorney-Sherman and Shalloway ABSTRACT: A process and apparatus for laying-in a pick of weft yarn utilizing a bobbin, first means to unwind a pick of weft yarn from said bobbin, second means for laying in the pick, said pick comprising a controlled limb, a loop, and a free limb and said second means comprising means to engage the controlled limb of the pick and means to move the loop, thereby causing the free limb to unwind within the shed of a loom.

Patented Dec. i970 3,543,808

Sheet 1 of9 INVENTOR ALBERT [MOESSINGER Patented Dec. 1, 1970 3,543,808

v NEXI Patented Dec. 1, 1970 Sheet 3 of9 INVENTOR ALBERT EMOESSINGER Patented Dec. 1, 1970 Sheet NOT . u m9 ROM mm? V0: NE A 8; mow E E fi INVENTOR ALBERTLMOESSINGER jfirma Y 5%.

I H AT'T rmrsv Sheetm H 5 2. m m x w BN N my 00m wmm mom MD Soc Patented 'Dec.1,1970 I 3,543,808

Sheet 7 of9 FIG.22

FIG 23 FIG. 24

FIG 25 INVENTORQ ALBERT [.MOESSINGER BY A ATTORNU Patented Dec.1,1970 3,543,808

Sheet 8 of9 I84 ALBERT EMOESSINGER ATTORNEY Patented Dec. 1, 1970 Sheet 9 of9 INVENTOR I ALBERTLMOESSINGER BY I Q 5) My 2 ATTORNEZ PROCESS AND APPARATUS FOR THE LAYING OF A PICK INTO THE SHED OF A LOOM SUMMARY OF THE INVENTION The present invention broadly relates to a process for introducing a weft yarn, i.e. laying-in a pick into the shed of a loom. More specifically, the invention relates to such a process which utilizes the kinetic energy accumulated in the yarn itself to assist in such laying-in.

Heretofore, it has been proposed to utilize this kinetic energy by processes wherein the yarn is ejected like a dart at high velocity into the shed. In order to avoid the development of a sinuous path, as a yarn is slowed down by air resistance and other resistances, the yarn is constantly tensioned by progressively slowing down its velocity during introduction into the shed. It is not possible, with these processes, to produce wide fabrics, because the yarn will stop before reaching the exit end of the shed.

It has also been heretofore proposed to lay the weft yarn in the shed in the form of a loop. The loop is projected by a jet of air into the shed. There are two reasons for this approach; first, to increase the propulsive action of the air by blowing transversely of the yarn, and second, to utilize a whip" action for unrolling the yarn. Whereas the first effect is generally achieved, the second is not since it merely unrolls a length of yarn without controlling the total length of the laid-in yarn in a constant manner. After unwinding a certain length, the fixed limb of the loop (i.e. the limb whose velocity is zero) is released and accelerates under the influence of the forces derived from the kinetic energy of the moving free limb. The free limb thus free, of course, can only be unwound when the other limb of the yarn is braked. In order to unwind or unroll the yarn it is therefore necessary to take energy from this other limb by slowing it down considerably or even bringing it to a halt by means of a brake arranged externally of the shed. thereby dissipating the energy imparted to this limb by the moving free limb. It will thus be clear that these processes exploit only an infinitely small part of the kinetic energy introduced into a yarn and merely dissipate said energy.

A modification of such processes used heretofore is urging a loop of yarn completely by forcing air across the yarn during its passage through the shed. In order to diminish the friction of the free strand situated externally of the shed. the free strand is housed in a tube and is pushed in the direction of its picking by a draught.

Some cloths utilize a double weft, and it has been proposed to introduce the doubled weft into a shed in the form ofa loop wherein one of the limbs is ejected by rollers rotating at the velocity ofejection. Since the yarn is not cut and unwinds constantly, it will not be possible, by these means, to produce singlc-weft fabrics. Furthermore, in such processes considerable difficulty is encountered where a rapid shed change IS required, since the weft is continually ejected. and it may pass from one shed to the other forming large loops protruding from the fabric, resulting in wastage.

In the past laying-in a pick has presented numerous operational problems. This invention solves many of those problems. To understand this invention and its novel charac tcristics. a general review of the process and terminology IS warranted. When a length of yarn is to be inserted in the shed of a loom. it is necessary to completely and accurately position the length within a given time interval. One method is to insert a cut length of yarn which is looped by gripping one end ofthe yarn and then passing the free portion over a roller so that the roller serves to define the loop. This roller may be moved forward and then stopped abruptly causing the free yarn to move forward until the loop disappears and a straight length of yarn is presented. wherein one end is still gripped. The action is analogous to that commonly observed with a whip (omitting the roller). This whip" action is utilized in the present invention. In the specification describing the invention. a free limb means that portion ofthe yarn length extending from its ungripped end to the portion of curvature (around the roller);

a "loop means that portion of curvature of the yarn; a controlled limb" means that portion which extends from the gripped end to the point of curvature, and the whip action occurring at the portion of curvature is unwinding." Thus, the

loop"joins the controlled limb with the free limb." During the w-hip" action the controlled limb can have zero velocity, the free limb has a given velocity and the loop has a given velocity.

This invention provides a process for the laying of a single pick in the shed of a loom, using the kinetic energy in said weft to aid introduction. The previously cut yarn is propelled along the axis of the shed, and it passes through the shed in the form of a loop with its free limb driven towards the exit of the shed at a velocity which is higher than that of the controlled limb. The yarn will advantageously be directed toward the axis of the shed before attaining its ejection acceleration at the shed entrance.

The mass of the free yarn, passing through the loop from the more rapid limb (free limb) to the slower limb (controlled limb), will present a difference in energy manifested as a force which will tend to tension the yarn and to overcome the frictional forces which might develop thereon.

The energy will be imparted to the yarn, in principle, before yarn entry into the shed, either by accelerating the yarn simultaneously over its entire length, or by accelerating locally it at the instant of its entry into the shed. In the first ease, the yarn will advantageously be rectilinear and will he directed in the direction of the shed at the instant of its acceleration, in the second case it may have any desired position. being for example still partially wound on the bobbin.

The location of the fixed end of the controlled limb is important since previous devices attempting to use the whip action used in the apparatus have failed. The reason for this is the yarn to be whipped is completely flexible and has no rigid part which facilitates the whip action. The fixed end should be located so that the rapid or free limb cannot rub against the slower or controlled limb. This is important since when the loop is propelled across the loom the yarn may more or less slightly adhere to the propelling means causing a reduction in kinetic energy. Since it is important that kinetic energy losses be kept to a minimum the fixed end of the loop must be so positioned so that there can be no reciprocal rubbing of the limbs as the loop passes across the loom.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates, diagrammatically, the unwinding action occurring when a pick of weft yarn is laid-in.

FIG. 2 illustrates a first embodiment of a device for laying-in a pick of weft yarn according to this invention.

FIG. 3 illustrates a second embodiment of a device for laying-in a pick of weft yarn according to this invention.

FIG 4 illustrates a third embodiment of a device for layingin a pick of weft yarn according to this invention.

FIG. 5 illustrates the embodiment of FIG. 4 having a yarnmeasuring device.

FIG. 6 illustrates a fourth embodiment of a device for laying-in a pick of weft yarn according to this invention, wherein the picking is commencing.

FIG. 7 shows the embodiment of FIG. 6, wherein the laying- In is proceeding.

FIG 8 shows the embodiment of FIG. 6, wherein the pick has been sheared and is unwinding.

FIG. 9 shows the embodiment of FIG. 6 wherein the pick is completely unwound within the shed.

FIG. I0 shows the embodiment of FIG. 6 wherein a new picking operation is beginning.

FIG. 11 is an end view of a loom suitable for applying the present invention.

FIG. 12 is a front view of the loom of FIG. I1.

FIG. 13 is a top view ofthe loom of FIG. 11.

FIG. 14 is an enlarged view of the batten of FIG. 11 illustrating suction means for controlling-the weft ends.

FIG. I5 is a view along lines II of FIG. 14.

FIG. 16 is an enlarged view of the batten of FIG. 11 illustrating means for moving the batten.

FIG. 17 is a top view of the moving means of FIG. 16.

FIG. 18 is a fragmentary part section illustrating the sliding of the picking axis and the driving in rotation of the picking wheel.

FIG. 19 is a side view of the portion illustrated in FIG. 18.

FIG. 20 is a graphical representation of the motions of components (moments) of FIGS. 1923 as a function of the rotation of the main shaft of the loom.

FIG. 21 is a schematic view showing a fifth embodiment of a device for laying-in a pick of weft yarn according to this invention wherein picking is commencing.

FIG. 22 is a schematic view wherein the pick has been introduced into the shed.

FIG. 23 is a schematic view wherein the pick is being unwound in the shed.

FIG. 24 is a schematic view wherein a subsequent pick is being accumulated.

FIG. 25 is a schematic view wherein picking has been completed and a subsequent pick is ready for laying-in.

DESCRIPTION OF THE PREFERRED EMBODIMENT movement, the loop 3 is displaced to 3 at velocity A differential element 5 of the said yarn, having a mass a'm moves along the free limb 4 through the loop 3 and arrives at 5, next to the fixed limb 2. The patch described is substantially the cycloid 6. During this passage from 5 to 5, the energy contained in the said element dm will pass from rim- (at s to am; (at

Velocity=V Velocity=0 This energy will be converted to a force T exerted in the direction of the movement of the free limb 4 moving with the loop 3. The said force T will act, from the loop 3 on, on the fixed limb 2 and free limb 4 of the yarn. Only the force T acting on the free limb 4, travelling at velocity V, will absorb the energy which is freed, the force T acting on the: fixed limb 2, which is immobile, will tension the yarn without dissipating energy. The work produced by the said force T will be equal to the kinetic energy contained in the yarn, i.e.:

V V m -2T1, and thus, L -m 1 m-g and wherein g is the gravitation constant.

From the foregoing, it will be clear that with this mode of laying-in it becomes possible to achieve considerable tension in the yarn. By way of example, a count 15/2 picked at a velocity of 50 m/sec will supply a force F E 9 grams.

Since the traction force on the yarn is proportional to the difference between the energy contained in the yarn at the instant at which it is introduced into the shed and that still contained in the yarn after its introduction. it is clear (and calculation demonstrates it) that when the controlled limb 2 travels ,at a velocity V2 within the shed (generally much smaller than V1 at its introduction) and in the same direction as V,, the

force T will be diminished. By way of information, we note that the general expression of the said force T is One embodiment of a mechanism for propelling (picking) the yarn is shown in FIG. 2 and comprises a lever 10 provided with a gripper 11 which secures one end of a yarn 12 to be propelled into the shed (not shown). From its position 1 to its position II, the lever is accelerated by known means (not shown), such as a spring, hydraulic pressure or pneumatic pressure, or by a cam actuated by the loom.

From II to III, the lever is braked by a means of any desired kind, such as is conventionally employed for this purpose.

The yarn 12, nipped by gripper 11, travels over a rounded guide 15 which is secured to lever 10. The yarn 12 is then passed through a rectilinear housing 13, which may be a tube, wherein an air flow (in the direction of arrow 14) exerts a suctional effect on the yarn l2 and maintains it in a rectilinear position. The direction of the said yarn is the direction in which the yarn is to be propelled. When the lever has reached the position II, it will have attained its maximum velocity, i.e. the propulsion velocity of the yarn which will then have been accelerated throughout its length to the said maximum velocity. From this point on, since the lever 10 slows down, the yarn 12 will continue its path until its entire length has unwound as shown in dotted lines in FIG. 2.

The propulsion mechanism shown in FIG. 3 differs from the preceding mechanism in that the velocity of propulsion of the yarn may be considerably increased. A yarn 12, secured at its end in a gripper 21 on lever 10 passes over a small wheel 23 rotating freely on a pivot 22 secured to the end of the propulsion (picking) lever. As in the example illustrated in FIG. 2, the velocity V, of the pivot 22 on the picking lever 10 will be at a maximum when the lever 10 reaches its position II. If the gripper 21 is fixed at that instant, the maximum velocity of the yarn will be 2V and the yarn will continue its movement at that velocity, as shown in dotted lines. Thus, it becomes possible to impart to the gripper 21 a clearly-defined movement in the one or the other direction during the movement of acceleration of the lever from position I to II, thus modifying the maximum velocity of the yarn, whereas after the yarn has left the wheel 23 of the picking lever 10, the movement of the gripper 21 will exert a traction force on the yarn, as previously explained.

FIG. 4 shows a further example of a mechanism for propelling the yarn into the shed.

The weft yarn 12 is drawn from a feed bobbin 31 and passes between an entrainment system comprising small wheels (or rollers) 32 and 33, the circumferential velocity of which is equal to the desired laying-in velocity. The yarn 12 passes between a first gripper 35 and the shears 36 (both of which are open) and then between the wheels (or rollers) 32 and 33, its end being retained by a second gripper 34. When the yarn is to be impelled into the shed 129, the

wheels

32 and 33 draw together in the direction indicated and press the yarn 10 between them as it is unwound from the bobbin 31. The mass of the yarn continues its travel under the influence of its kinetic energy which is converted, as each element passes from the free limb to the controlled limb, as described with reference to FIG. 1, to a force exerting a pull on the limbs of the loop. The first gripper 35 is open during the time necessary for allowing the passage of the desired length of the yarn. At that instant, the first gripper 35 is closed and the yarn is cut by the shears 36. The yarn thus freed continues its travel at the velocity imparted by

wheels

32 and 33 and unwinds within the shed 129.

In order to prevent braking of the yarn under the influence of the gripper 35 and the shears 36, it is possible to provide two yarn entrainment systems, as indicated in FIG. 5. The

entrainment system

32, 33 serves, as in the example according to FIG. 4, to propel a yarn into the shed 129, whereas the entrainment

system comprising wheels

37, 38 supplies a quantity of yarn such that, at the instant at which the yarn is to be nipped and severed by the

members

35 and 36, respectively, a yarn reserve (sucked, for example, into an accumulator pipe 39) will be available for feeding the

entrainment system

32, 33 during the time necessary for severing the yarn. An advantageous arrangement consists in driving the

entrainment system

37, 38 at a velocity such that, by continuous operation, it will supply exactly that quantity of yarn necessary for each cycle. Thus, the unwinding of the yarn from the bobbin 3] will be effected continuously and without jerky motion.

In all these examples, the unwinding velocity of the loop can be accelerated or slowed down during the passage thereof through the shed, depending on whether the frictional forces acting on the yarn are smaller or larger than the force T acting on the yarn. It could be said that. since the friction is proportional to the length of the yarn to be picked, the yarn will tend to accelerate towards the end of its travel (when little length remains), whereas it could very well be slowed down at the beginning ofits travel (when high length remains).

FIGS. 1 to 5 are FIGS. which have been simplified in order to facilitate understanding of the principle employed for the introduction of a pick into the shed of a loom in accordance with the novel process. These FIGS. do not show how a succession of yarns may be laid-in. In the case of FIGS. 4 and 5, for example, after the yarn has been cut by the shears 36, the first gripper could be displaced so as to carry the yarn through

rollers

32 and 33 and back around roller 32, through second gripper 34; then first gripper 35 is returned to its initial 1 position in order that the operation may recommence. A suitable device for such operations is described hereinafter.

FIGS. 6 to 10 show a chronological sequence of movements of a mechanism according to the invention in operation with other elements of a loom.

In FIG. 6 a yarn 12 is drawn from a bobbin 31 and passes into an unwinder comprising rolls 32, 33 and over a picking wheel 44, whereupon it is sucked into a reserve tube 13 in which a flow of air has been set up in the direction of the arrow l4. The unwind

rollers

32, 33 are connected to a speedvarying control 46, which is adapted to be adjusted by means of the handle 47, in such manner that the unwind

rollers

32, 33 supply exactly the desired length of weft between two picks. i.e. as a function of the width of the cloth.

The picking wheel is connected to a propulsion or picking lever 10 through a link 49, so as to permit the picking wheel 44 to be guided in a rectilinear guideway. The picking lever 10 rotates about a pivot and is actuated by a spring having the form of a torsion bar 51 secured at one of its ends to the picking lever 10 and at the other to a fixed portion 52 of the loom. The said lever 10 is provided with a knuckle or ball and socket joint 53, 54 fixed at 55 to the lever 10 and at 56 to a fixed portion of the loom. A

fork lever

57, 58, oscillating about a pivot 59 is actuated by a cam (not shown) rotating with the main shaft of the loom, and triggers the knuckle joint 53,54.

At the instant at which the knuckle joint 53, 54 is triggered by the fork lever arm 58, the picking lever 10 and the picking wheel 44 are accelerated by the action of the torque developed by the torsion bar 51. The energy contained in these mechanisms is dissipated at the end of the travel of lever 10 by an hydraulic brake 60 or equivalent braking means, connected at 61 to the picking lever 10.

A shed is formed by warp yarns 70, extending from the cloth face 71 to reed 72. Disposed behind the reed 72 are the shafts 73 actuating the healds 74 controlling the warp yarns 70 in such manner as to change a shed after the laying-in of each pick. In view of the considerable laying-in or picking velocities achievable with the novel process, the time available for beating up the pick in the cloth (by reed 72) and shed changing (by shaft 73) will be increased. These movements could be proportionally slower, optionally without a stopping position if desired. Any modification of existing loom mechanisms is thus easily accomplished.

At the instant of picking (FIG. 7) a given length of yarn has been sucked into the tube 13. This length of yarn will be accelerated by the movement of the picking wheel 44 to a velocity V equal to double the velocity Vr of the picking wheel 44 less the unwinding velocity of the entrainment or drive means V i.e. V 2Vr- V At the instant at which the picking lever 10 is braked, the free limb 4 of the yarn 12 will continue its travel (FIG. 7) into the shed. When an adequate length of yarn has been unwound by the unwinding roller 32, the gripper 62 closes, arresting the yarn 12 which is severed by the shears 36 (FIG. 8). This operation is advantageously effected when the free limb 4 of the yarn is entirely within the shed. While the free limb 4 of the yarn 12 continues its unwinding movement through the shed, the fixed limb whose end is gripped in the gripper 62, will be at velocity zero. The part 40' of the yarn 12 will be sucked into the reserve means (tube 13); since unwinding 32, 33 operate continuously, an additional air current in the direction of arrow 64 would facilitate this transfer (FIG. 8).

When the free limb 4 of the yarn 12 is completely unwound, its end is sucked in by the tube 65 (FIG. 9). A reed 72, travelling in the direction of the fabric face 71 will beat up the yarn laid-in against the fabric edge. During the movement of the reed 72, the tube 65 and also the gripper 62 may be displaced in the direction of the cloth, in order that the ends of the yarn may be constantly controlled during the displacement thereof towards the cloth 71 (FIG. 10) by reed 72. After beating up, the ends of the yarn projecting from the cloth may be cut by conventional means.

A weaving loom illustrating the application of this invention is shown in FIGS. l1, l2, and 13, while FIGS. 21 to 25 show chronologically the movement of a yarn from the takeoff device to the moment of its introduction into the shed.

The arrangement of the warp and fabric beams and the inclination of the shed has been selected for a better adaption of the new principle of this insertion. In addition, this arrangement substantially reduces the bulk and facilitates repair of broken yarns.

Referring to FIG. 11, the body of the loom is formed by two frames 101 and 102 (see FIG. 12), interconnected by a crosspiece 103 bent substantially at right angles to impart rigidity to

frames

101 and 102 and reinforced at its ends by U bends 104 and 105. In addition to crosspiece 103, the spacing of

frames

101 and 102 is maintained by tubes 12] and 122, as well as by a fixed shaft 123. On the said frames 101 and 102 there are fixed

rotary shafts

107 and 108 of warp beam 106 and fabric beam 109, the latter being disposed above the warp beam.

Between the two beams 106-and 109, only the mechanism for movement of frames 110 (described below) is mounted in order to limit the total height of the machine. Referring to FIG. 13, each frame 110 is ensured by a cable 111 fixed at one of its ends to frame 102 by means of a recall spring 112 and passing on four pulleys 113, I14, 115, and 116. Cable 111 is connected by grippers 117 to two rods 118 which communicate the motion of cable 111 to frames 110. The said rods 118 are guided in slides 119. The other end of cable 111 is fixed to the levers of a dobby which is indicated schematically by 120, controlling them independently in the usual way. Each frame 110 has identical controls as herein described.

Back to FIG. 11, warp yarns 70 unrolling from beam 106 pass over tensioning drum which is pivotally secured to the end of levers 126, which are'pivoted at their other end on fixed shaft 123. The said levers 126 are tensioned by adjustable springs I27, imparting the desired tension to the warp yarns 70. The said yarns 70 pass over a support 128 from which point they separate under the effect of frames 110 to form shed 129 limited by reed 72, and the yarns 70 meet again at the fell 13] of fabric 132. Fabric 132 isguided by fabric support 133 near fell 131 and then passes over tube 121 and emory roll 134, press 135 and crosspiece 103 to be rolled on fabric beam 109.

The succession of the warp-fabric passage is conventional and presents no novelty other than the inclination of the shed and the arrangement of the warp and fabric beams. The rotation of the emory roller ensures the advance of the fabric and is regulated in the usual manner to obtain the desired beating up of the picks. The advance of the fabric beam and the unrolling from the warp beam are also effected in a conventional way.

Weft yarn 12 drawn from a spool 31 passes over a takeoff device 138, 138' to be inserted into shed 129 by the process of the invention. Reed 72, fixed on the batten, which comprises substantially a tube 139 bearing pivot pins 209 (see FIGv 12) which turn in bearings located in plates 141 fixed on

frames

101 and 102. On said tube 139 there is riveted a thin sheet metal element 140 (see FIG. 16) in the form ofa V which extends over the whole length of the reed. The oscillating motion of the tube 139 is effected by main shaft 142 (see FIGS. 16 and 17) which also rotates in plates 141, with two eccentric parts 143 on which links 144 communicate the movement of the eccenter to tube 139 of the batten by means of levers 145 and pin 146. The main shaft 143 is furnished with a pulley 147 (see FIG. 12) driven by a belt and a conventional motor. which elements are not illustrated.

The picking of the yarn according to the invention is effected by means of picking wheel 150 connected by link 151 to pick lever 152, shown generally in FIG. 12. Said lever 152 is fixed on a hollow shaft 153 which pivots around its axis in bearings 154. The said hollow shaft 153 has an arm 156 at the end of which there is a ball and

socket joint

157, 158, part 158 of said joint being pivoted on a fixed shaft 159. On the extension of part 158 of the joint there is a spline 160 which can play in aperture 161 of piece 162. Said piece 162 also has a setscrew 163 and is driven in a vertical reciprocating motion produced by cam 164 which motion is transmitted by lever 165, shaft 165 oflever 165" and link 166.

Cam 164 is fixed on a shaft 167 driven by main shaft 142 by means of a pair of tapered gears 168. As seen in FIG. 1], ho]- low shaft 153 is rigidly connected to one end of a torsion bar 169. Said torsion bar 169 has at each end a square section, one of which ends is adapted into a corresponding seat of hollow shaft 153 and tightened by means of a slit ring 170. The other end of torsion bar 169 is similarly fixed in a piece 171 fixed on the fixed support 172 which is rigidly connected to frame 101. Said piece 171 can pivot on its support 172 and it is stopped in the desired position by a screw 173 which makes possible the adjustment of the force of the picking that is desired.

Returning to FIG. 12. when piece 162 moves upward, spline 160 is carried along and joint 157, 158 is brought into its rectilinear position. The first part of this return movement of piece 162 is effected without load until at the end of the stroke setscrew 163 pushes the extension of part 158 of the joint that bears spline 160 and bends the joint. When joint 157, 158 is in its rectilinear position, picking lever is carried into its throwing position and torsion bar 169 is stretched to its maximum. This position of picking lever 152 is maintained byjoint I57. 158 in its rectilinear position. At the moment at which setscrew 163 bends the joint. the position of picking lever 152 is released and the said element is accelerated by the moment of torsion exerted by torsion bar 169.

When picking lever 152 reaches the speed necessary for throwing the yarn, it is braked by suitable means. in the case illustrated in FIGS. 11 and 12. the braking is effected by a magnet 182 which develops a strong magnetic field between its poles 183. Lever 152 is of aluminum. which has good electrical conductivity. passes through the field, with production in the said aluminum of strong Foucault (eddy) currents which absorb its kinetic energy andslow its speed.

The remaining energy can then be absorbed by plate 180 which IS rigidly connected to lever 152 and which strikes against a shock absorbing block 181 fixed on fixed piece 155. The said shock absorbing block 181 can be rubber or equivalent materials The pick lever 152 drives the picking axis 175 (see FIGS. 18 and 19) ofthe picking wheel 150 via the link 151. the picking wheel 150 being secured to a small gear 176 meshing with a fixed rack 177, the picking axis 175 being mounted on a slide 178 displaceable in a slideway 179. That way, the picking wheel 150 will be rotatably driven by the movement of the pick lever 152 and the yarn will not suffer any friction during its acceleration.

In order not to conceal the essential elements of the machine, apparatus for guiding and placing the yarn are shown in FIGS. 21 to 25, which illustrate the position of the different elements and of the yarn in chronological order. For better comprehension. the motions of the different elements have been plotted as a function of the rotation of the main shaft 142 of the loom in a graph of FIG. 20 in which:

A is the motion of the batten;

B is the motion of the picker roll 44;

C is the motion of gripper C;

D is the motion of gripper D;

E is the motion of shears E;

F is the opening and closing of valve F; and

G is the opening and closing of valve G.

In this figure, the moments corresponding to FIGS. 21 to 25 have been plotted.

Weft yarn 12 drawn from spool 31 passes over takeoff 138, 138' which has been rotated down by in FIGS. 21 to 25 to make it clearer. From 138 yarn 12 passes into a yarn accumulator 39 in which suction is produced from passage 191 by means of valve G. Said valve G is actuated by lever 192 pivoting about fixed point 193 by means of a linkage 184 connected to a cam (not shown) that is driven by main shaft 142. The yarn then passes through gripper C. In the picker shaft of picker roll there extends, opposite the shed, an aspirating tube 13 in which the weft yarn is extended before the pick. At the end of suction tube 13 a passage 186 connects it to a pump (not shown) that can be the same as the pump that produces suction in accumulator 39. The said tube 13 is long enough sothat the whole length of yarn to be accelerated can be extended in it. A valve F is provided at a point along said whole length so that the extended yarn remains about 10 cm. downstream from the said valve F. Valve F is actuatedby lever 182' pivoting about fixed point 182' by means of a linkage 184' connected to a cam (not shown) which also actuates valve G.

A little ahead of the pick (FIG. 21), picker roll 150 is in front of tube 13. The weft yarn 12 has been locked by gripper C and it extends the whole length of tube 13. Valve F is opened so that between valve F and picker roll 150 the yarn 12 is exposed to only an insignificant flow of air. 0n the other hand, the last 10 cm of the said yarn are subjected to a How of air that extends the yarn to its whole length through suction in passage 186. Valve G is opened so that the yarn delivered by takeoff 138 can begin to collect in accumulator 39. At the moment of the pick, reed 72 is about in the middle of the shed. Yarn 12 is introduced into the shed by whip action of pick roll 150, and the tip of the loop passes above the reed (FIG. 22). The lower length of the loop (controlled limb) may touch reed 72 harmlessly because its velocity speed is zero; it may rest on the reed. Between FIGS. 21 and 22, yarn 12 will begin to col lect in accumulator 39 due to the continuous feed from 138, while picker roll 150 is at the back end of its stroke. It is to be noted that since accumulator 39 is in a slightly inclined plane (FIG. 13) weft yarn 12 in passing from takeoff 138 to accumulator 39 will not disturb either the passage of the loop of yarn 12 or of picker roll 150. It is also to be observed that gripper D is open. At about from the main shaft 142, the reed is in low position and the free limb of weft yarn 12 has entered the shed (FIG. 23). At this moment, gripper D closes, which allows the opening of gripper C without losing the controlled limb of the yarn. Gripper C opens and places the yarn in front of picker roll 150 and the mouth of suction tube 13 (FIG. 24). In the meantime, valves F and G have been closed, which has the effect of producing a suction of yarn 12 into tube 13 and cutting off the suction in accumulator 39. The yarn passes thus from accumulator 39 into tube 13. The loop of yarn in the shed has completely unwound across the shed and the end of yarn 12 has been engaged by the exit suction nozzle 200 and braked on the reed by nozzle 201 (FIGS. 14 and 15). We will return later to this apparatus. Reed 72 continues its ascending course, carrying the extended yarn against fell 131 of fabric 132 in which it is beaten up (FIG. 24). Gripper D opens and shears E cut the beaten up yarn at the fabric selvedge. The end of yarn 12 thus freed is sucked into tube 13 and theloop formed in this tube will be extended. During the last described operations, the takeoff 138 has continued to deliver yarn that has been sucked into tube 13'after the accumulator reserve. The amount of yarn furnished by takeoff 138 during one cycle of the machine is exactly the length necessary for weaving a pick, so that it can deliver yarn continuously. This may be achieved with conventional speed controls on 138. Since yarn 12 is extended completely in tube 13 (FIG. 25), the operations can begin again (FIG. 21).

FIGS. 14, 15 show retention of the yarn as it leaves the shed. This retention is' ensured by a retaining system comprising essentially two elements, a suction nozzle 200 comprising a tube 202 at the side of the reed where yarn 12 is shot and parallel to the axis of the shot; it is fiat and ends in a funnel 203. On the other side of the reed, downstream from funnel 203, there is a suction nozzle 201 sucking through the reed, the lower length of yarn which is extending without slip on the reed, and holding it. The two

nozzles

200 and 201 are connected to a suction pump (not shown) by a passage 204 which surrounds head 130' of reed 72 (H6. 14) in order to allow movement of the retaining system in response to a possible change of width of fabric to be manufactured.

Since the retaining system is movable with the reed, it is advantageous to connect passage 204 via a line 205 with metal element 140, which in turn is connected with tube 139 by an orifice 206, the communication with the fixed lines being effected via a hole 207 through shaft 193 and via tube 208 fixed on fixed plate 141 (FIG. 12-).

When the width of the fabric to be produced is changed, the length of the yarn delivered by takeoff 138 must be adjustable. A speed change device 210 controls takeoff 138 by means of sprocket wheel 211, chain 212, and a sprocket wheel 213, mounted on main shaft 142. Handle 214 of speed change device 210 allows regulation'of the length of the yarn issuing from the shed and reduction of yarn waste toa minimum.

It is to be understood that each and every detail ofa loom cannot be illustrated and the structure and operation of conventional details are obvious to those skilled in the art. This invention is adapted for use with all those conventional devices and the specific illustrationsof a loom and the components is not limiting in any manner. Havlng described the invention in compliance with the terms and spirit of the patent statutes:

1 claim: 1. Apparatus for laying a pick of weft yarn into a shed of a loom comprising:

first means to feed a supply of weft yarn; second means to grasp a leading end of said yarn; third means to loop said yarn outside of said shed and to impart to said looped yarn anaccumulated kinetic energy which causes said looped yarn to move toward and across said shed; fourth means to release said second means when the pick is positioned across said shed; and fifth means to shear the yarn. 2. Apparatus according to claim 1 wherein said third means comprises a picker lever which may move at the velocity of introduction of said yarn. I a

3. Apparatus according to claim 2 wherein said picker lever carries a picker roll around which said yarn is looped.

4. Apparatus according to claim 3 wherein said picker roll is rotatably driven by the movement of said picker lever.

5. Apparatus according to claim 1 wherein said third means comprises a pair of rollers rotating at the velocity of introduction ofthe yarn.

' 6. Apparatus according to claim 1 wherein said first means includes a reserve means to draw and retain a measured length of yarn in a rectilinear position prior to its introduction into the shed.

7. Apparatus according to claim 6 wherein said reserve means is rectilinearand directed toward the axis of the shed.

8. Apparatus according to claim 1 wherein said first means includes an accumulator means for storing at least a portion of a pick of weft yarn to be introduced into the shed.

9. Apparatus according to claim 1 wherein said fifth means comprises shears located adjacent the shed edge, said shears being actuated by actuating means to cut the controlled limb of a yarn after the free end of the yarn has been positioned across the shed.

10. A process of weaving in which successive wefts of yarn are inserted into successive sheds, said wefts of yarn pulled from a spool outside the shed in a measured amount and moving through the shed under the influence of the kinetic energy accumulated in their mass. including: pulling a weft of yarn from a spool to-a measured amount. picking the yam into the shed, said picking imparting the whole kinetic energy to the yarn before its entry into theshed, the weft yarn being converted by said picking into a loop with two substantially parallel limbs, one ,of said limbs being propelled into the shed by said kinetic energy and accelerated with respect to the other of said limbs, and cutting the previously inserted weft thread from the yarn to be prepared for the next insertion at the edge of the fabric.

'11. The process according to claim 10 wherein the linear speed of the other of said limbs corresponds to the speed of unwinding of the yarn from the spool.

12. The process according to claim 11 wherein the speed of the other of said limbs is zero during at least part of the laying of the pick.

13. Apparatus for weaving in which successive wefts are inserted into successive sheds by the sole action of kinetic energy accumulated in the yarn, which apparatus comprises:

a. measuring means pulling a yarn extending from .a fixed spool to the shed and measuring a predetermined length of weft yarn to be laid;

b. means catching the'yarn still connected to the previous inserted weft between the edge of the woven fabric and the measuring means when the length of weft yarn to be laid reaches the required predetermined value;

c. means cutting the weft yarn from the previous inserted weft near the edge of the woven fabric;

d. means guiding the freed yarn in a way opposite to that of the shed and means .bringing the thread into the guiding means; and

e. whipping means located outside the shed and pushing said weft into the form of a loop and toward said shed, said loop having two substantially parallel limbs, one of said lim-bs being in the axis of said guiding means and accelerated to a speed higher than the other of said limbs which is connected to the spool.

14. Apparatus according to claim 13 wherein means are provided such that the speed imparted to the other of said the yarn to form a loop.

16. Apparatus according to claim 15 wherein said guide roller is driven by gears deriving their motion from the movement of said lever.