US2638942A - Weft detector and stop motion for weaving looms - Google Patents

Description

May 19, 1953 Filed Sept. 21, 1950 T. HINDLE WEFT DETECTOR AND STOP MOTION FOR WEAVING LOOMS 3 Sheets-Sheet 1 Z gi 6 I I A m U i m Inventor 95 M By (9H4? Attorneys y 9, 1953 T. HINDLE 2,638,942

WEFT DETECTOR AND STOP MOTION FOR WEAVING LOOMS 7 Filed Sept. 21, 1950 3 Sheets-Sheet 2 May 19, 1953 HINDLE 2,638,942

WEFT DETECTOR A ND STOP MOTION FOR WEAVING LOOMS Filed 21, 1950 3 Sheets-Sheet 3 I nvenior Afiorneys Patented May 19, 1953 WEFT DETECTOR AND STOP MOTION 'FOIt WEAVING LOOMS Thomas Hindle, Blackburn, England Application September 21, 1950, Serial No. 185,990 I In Great Britain September 25, 1949 Claims. (Cl. 139-370) This invention relates to looms for weavin and more particularly to improvements in weft detectors and loom stop-motions.

The object of the invention is to provide an improved weft detector which is sensitive to the tension of the weft as this. is laid in the warp shed by the moving shuttle.

According to the invention, when the shuttle enters the shed, the weft is caused to loop round a sensitive detector pin temporarily positioned closely adjacent to or actually amongst the selvage warp threads near the fell of the cloth, the pull exerted by the weft on the said pin being utilised to close the contactsof an electric switch against the pressure of a light spring acting to open them.

The invention is illustrated in and will be described with reference to the accompanying drawings. In these drawings- Fig. 1 is a front elevation, partlyin section, of the improved weft detector, which is shown in the detecting position in relation to -the salvage of the cloth being woven;

Fig. 2 is a partial cross-section through a loom showingone suitable form of -mechanism for actuating the arms which support the weft detectors;

Fig. 3 is an electric circuit cliagram'illustrating the action of the detector switches; and I Fig. 4 is a timing diagram'based ononerevolution of the loom crankshaft Referring to Fig. 1, which illustrates the weft detector and the manner in which it functions, an approximately verticaldetector-pin i, tapered or pointed at its lowerend is suitably clamped by screws 2 in a holder 2, which is pivoted at -Z on the inner end of a horizontal holder-bar 3, fixed stops t and 4 being provided-to restrict-the rocking movementof the holder 2 and the detector-pin l to a small angle.

An electric switcht is mounted on the outer end of the holder-bar 3, preferably a djustably, \as' for instance bi, means or the collar 5*, which forms part of theswitch casing, and the-screw 5 The switch iwhichmay beofany suitable typeprovide'd with a light spring acting to-separate'the switch contactsis actuated by'the cletector-pin through a push-rodfi, the inner end of which'bears on the detectorspim or as shown on its holder 2 a short distance above the-pivot 2, and the outer end of which bears on the-plunger'ii of the switch-'5. Thez-push-rodfi slides in bushes '3 inserted in a central passage-3 in the holder bar 3. 7

When the weft pull is absent on the detector- :2 pin I the contacts ofthe-switch 5 are openedlby the switch-spring, and the detector-pin,.b-y reason of its unbalanced weight in relation to,- pivot 2, assumesits natural position, as shown by the centre-line a-b, in which the lower end of the holderZ rests against the stop 4*.

The pull of'the weft W looped roundthe detector-pinat the picking end .of the loom displaces the bottom end of .the pinin the-direction of the moving shuttle (indicated by arrows in Fig. 1.) with theresult that the pin then rocks to the position shown in Fig.1, corresponding to centre-line c-d. Such-displacement is transmitted on a reduced scale by the push-rod 6 .to the plunger 5 of the switch 5.50 .as to close the switch contacts, which then remain closed provided that-the weft continues to exert the necessary pull on the detector-pin l throughout the remainder of the shuttles flight.

When the weft'haspulled the detectorpin I to position cd, so that the holder-2 bears firmlyagainst stop '4, the pin in such position isrigid- 1y supported and is well adapted to withstand without further displacement any snatch or abnormal pull exerted by .the weft.

The improved weft-detector possesses, therefore, the incidental advantage of.preventing, in well-known manner, the cloth selvage being pulled in unevenly by irregular wefttension.

In Fig. 1, the woven cloth-is indicated in crosssection at G, E being one selvage. W represents' the warp threads forming the shed, through which the weft W is being laid bytheshuttle travelling in-the direction indicatedby the arrows.

In Fig. 2, the weftW is shown extending between the cloth-fell F and the shuttle S passing through the shed formed-bythe warp threads W. The weft W loops. round the detector-pin l. The slay is shown insolid lines at L in its fully back position, in dotted lines at L inits fully" forward position.

The horizontal holder-bar 3, is clamped by.a screw! approximately-midwayin its length-at the end of an arm or lever 'Lsecured so as to rock with a rocking shaft 8, which is parallel-to and is supported in bearings-8 fixed on the front-rest R of the loo-m. g

A mechanism constructed andarranged asso far described is provided ateach selvage side of the loom and both arms 1 are given a suitable rocking movement in ,synchronism with the-for wardand backward movements'of theslay. .The rocking shaft "8 may i be 'actuated through any suitable mechanismconnectedto thes'lay or its swords, or by a cam or cams revolving at crankshaft speed. In the case of very wide looms, the rocking shaft 8 may be in two parts, each actuated independently, but in unison.

Referring to Fig. 2, as the slay retires from its forward position L in anticipation of the next picking operation, the arms 1 swing down to carry thedetector-pins into their detecting position, that is, as shown in Fig. l and in full lines in Fig. 2, closely adjacent to or actually amongst the selvage warp threads near the fell F of the cloth, with the bottom-or pointed end projecting slightly below the plane of the bottom shed.-

The detector-pin l remains in this position until at a suitable time as the slay is again advancing towards its front position, shown by dotted lines at L, the arms 1 swing up, first withdrawing the engaged detector-pin in an upward direction from the weft loop, and then swinging both arms and detectors upward and forward outof the way of the slay which is then advancing to beat up the weft. The time at which the detector-pin l is withdrawnfrom the weft loom does not occur until after the shuttle has arrived in the opposite box, so. that the detector issensitive to the tension of the weft during the major and final portion of the shuttles passage across the slay. V H

One suitable arrangement of actuating the rockingshaft 8 and hence the arms l'iixed thereon is shown in Fig. 2. In this arrangement the loom crankshaft 9 is provided with a negative cam'or cams I0, co-acting with roller li on a follower-lever l l, pivoted at II on the loom framing. The displacement of the lever ll by the cam I0 is transmitted by a link l2 to a two- 'arm lever 13 which is pivoted at I3 on the loom framing. A spring l6 anchored at one end to the frame of the loom and at the other end to one arm of the lever l3 acts on the latter to maintain the roller I l carried by the follower-lever l I in contact with the cam ill. I

The upper arm of the lever 43 is connected by link I4 to, lever it which is fixed to the rockingshaft8, on which the arms I are secured.

Insteadof employing a negative cam 10 for actuating the'follower-lever I' l a positive cam may be employed in which case the spring [6 is not required. i t As applied to' a wide loom in which the slay movement includes appreciable dwell in or near the back position to allow of the shuttles passage throughthe shed, the profile ofthe cam J0 is preferably such that thearms I remain "up for about one-quarter of the crankshafts revolution and remain down forabout one-half, the remaining two-eighths sufficing for the upand down movements.

The arms 1 supporting theweft-detectors are adjustable along, their shaft or shafts-8 to suit the exact width of cloth being woven. A flexible cable 5 connects each swinging switch to a terminal box orplug 5? mounted'iinderneaththe front-rest'R.

The details of the mounting 'and' actuation of each switch may be varied if desired. For example the switches may be mounted 'ori'or below the front-rest and be actuated throughmechanical linkagefrom the detector-pins I. v

The weft-detector mechanism herei nbefore described canbe used either to close an electric circuit-or, as'isdpreferred, to maintain anIelectrio. circuit whichw'o uld otherwise he broken, as anl,indication ,that" he weftfi's intact from the tle. It may be employed to indicate whether the weft is intact right across the looms reeded width at or just before the time when the shuttle completes its passage, or at any desired earlier stage in the shuttles flight after the weft should normally have looped round and actuated the detector-pin at the picking end. Such indication may be adapted to control any form or loop stop motion so as to cause the loom to be stopped in the event of weft failure.

The weft detector switches 5 act by controlling the circuit of an electro-magnet, the basic principlebeing thatsuch electro-magnet must be energised, or continue to be energised at the crucial moment if the loom is to continue running. Thus if the weft fails to make or to maintain the circuit of the electro-magnet, the loom stops- The loom also stops should the electric supply for the detector circuit fail for any reason.

' The aforesaid electro-magnet may be controlled by a pair of weftdetector switches, operating in combination with a cam-actuated weft try-switch, such cam revolving at slay crankshaft speed. Alternatively, the weft try-switch may be actuated by a cam or cams mounted on any other shaft, or by an oscillating cam or equivalent linkage connected to the slay or slay swords, the essential requirement being that the weft try-switch shall open and close at the desired times in each successive revolution of the loom crankshaft. The two weft detector switches and the weft try-switch are all three connected in parallel with the electro-magnet and a. suitable source of electric current. Fig. 3 shows such a circuit arrangement in diagrammatic form, the weft-actuated detector switches 5 being connected in parallel with the cam-actuated weft try-switch l1, and then in series with the electro-magnet I8. The cam-actuated weft try-switch ll maintains the circuit for part of the crankshafts revolution, but opens the'circuit at any desired point during the period the shuttle is normally passing through the shed, during which period one or the other of the detector switches 5 normally should be closed due to'the pull of the weft exerted on the corresponding detector-pin I.

In Fig. 4 which shows a timing diagram typical for a wide loom, I represents the crank position at beat-up when the slay is fully forward and V represents the crank position when the slay is fully back. The arms 1 remain up out of the path of the read from VIII to II. From II to III the arms are lowered to carry the detector-pins into their detecting position, where they remain until VII. From VII to VIII, the arms are liftautomatically.

ing. The picking impulse normally commences at III and the shuttle passage takes place from IV to VI. The weft try-switch opens at about V and remains open until about VI, after which it re-closes and remains closed for the remainder of the cycle.

If the weftruns out or breaks so that the appropriate detector switch 5' is not closed when the weft try-switch l1 opens the circuit'at about V, then the electro-magnet is promptly de-ene'rgised and'the loom thereby caused to be stopped automatically. Similarly, if the weft is intact when the weft try-switch opens at about V, but subsequently fails before it re-closes at about VI, then the appropriate detector-switch 5 opens with'the resultthat the electro-magnet is de-energised'and the loom thereby caused to be stopped I claim:

1. A weft detector motion for controlling the stop motion of a loom comprising the combination with an electric switch of a Sensitive detector-pin; means for temporarily positioning said pin in close relationship to the selvage warp threads near the fell of the cloth during the passage of the shuttle across the slay, and a member between said pin and switch for controlling the switch, the movement of the shuttle causing the weft to loop around the detector pin and exert a pull thereon to move it into a position to operate said member to close the switch and maintain the switch closed so long as the pin remains in close relationship to the selvage warp threads and the weft continues to exert a pull on the pin.

2. In a weft detector motion as in claim 1, the combination with the sensitive detector-pin of a pivot on which it is mounted in a slightly unbalanced condition, and wherein said member comprises a push rod adapted to be engaged by the detector-pin when it is moved out of its neutral position by the pull of the weft, and said electric switch has spring controlled contacts which are closed by the movement imparted to the push rod by the detector-pin due to the pull of the weft, and including an electric circuit containing the switch and controlling the stop motion of the loom.

3. In a weft detector motion as in claim 2, the combination with the sensitive detector-pin, of a holder rotatably mounted on said pivot and in which the detector-pin is adjustably mounted, a holder-bar in which the push rod is slidably mounted, the holder being pivotally mounted at the end of the holder bar so that the holder and the pin are out of balance, and a housing for the switch at the opposite end of the holder bar to that at which the holder for the pin is pivotally mounted.

4. In a weft-detector motion as in claim 3, the combination with the detector-pin, the holder therefor, and the holder bar of a rocking arm in which the holder bar, is carried, and a cam making one revolution for each revolution of the crank shaft of the loom, said cam controlling the rocking arm to lower the detector-pin into the detecting position in close relationship to the salvage warp threads and to raise it therefrom at the appropriate points in the weaving cycle of the loom.

5. In a weft detector motion as in claim 4, the combination with the detector-pin, the holder therefor, the holder bar, the rocking arm and the actuating cam of a pivoted follower-lever which is actuated by the cam, a rotatably mounted shaft on which the rocking arm is aflixed and a lever and link mechanism connecting the follower-lever to the shaft.

THOMAS HINDLE.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,169,756 Buell et al. Aug. 15, 1939 FOREIGN PATENTS Number Country Date 347,965 Great Britain May 7, 1931 505,855 Germany Aug. 28, 1930

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