US2752955A - Thread cutter for looms - Google Patents

Description

July 3 1956 P. c. CONSOLETTI 2,752,955

THREAD CUTTER FOR LOOMS Filed April 5, 1955 INVEN TOR. PAUL C. CoNsoLETTi A TTORNE Y Unite States Patent THREAD CUTTER FOR LUOMS Paul C. Consoletti, Milford, Mass., assignor to Draper Corporation, Hopedale, Mass, a corporation of Maine Application April 5, 1955, Serial No. 499,466

4 Claims. or. 139-263) This invention relates to thread cutters for looms, and more particularly, to such cutters in which blades are actuated by contact of certain follower means at a blade with a pivoted cam biased toward one extreme position by a resilient means.

It is an object of the invention to provide a practical, eifective and inexpensive means by which certain dcleterious action of these cutters may be avoided. More specifically, it is an object of the invention to .cut down flutter or rebound of the cam thereby to prevent unintended engagement of a follower with the point of the cam.

Cutter and clamp means of the Stafford type are used in fly shuttle looms .to sever and hold the filling as an exhausted bobbin is ejected at the filling replenishing cycle. In so doing, the cutter is very rapidly moved in to get the thread and similarly withdrawn quickly to cut and clamp the end. As shown and described in copending application Serial No. 420,821, filed April 5, 1954, now Patent No. 2,711,193, the movable blades are pivoted and actuated through contact of a projection or follower at one blade with a pivoted cam. This cam is inclined to the path of movement of the follower and is spring pressed in one direction against a stop. The action is one in which the follower alfected by one side of the cam is raised or lowered, as the case may be, to an elevation slightly past the pivot, the cam then springing to its stop position, under influence of the resilient means.

In the movement of the cutter to the front or back of the loom, there is especially at high speeds, a rebound or fluttering of the cam until it comes to rest against its stop. Movement to the front of the loom comes very quickly after that toward the rear so that this rebound action may be very disastrous in that the follower does sometimes strike the point of the com. If it strikes it rather squarely, the cam or follower must be seriously damaged and thus high speed action of such a mechanism is always open to the possibility of improper functioning of and damage to the cutter itself.

According to the invention, the simple mechanism so widely utilized is rendered safe or foolproof against the possibilities above noted by the incorporation into the combination of parts of a damping means which cuts down the possible fluttering or rebounding of the cam so that at any speeds at which these looms may be operated in practical usage there can be no destructive interference of the parts.

The invention will be described in detail in the following disclosure of one preferred embodiment thereof as illustrated in the accompanying figures of drawing, where- 1n:

Fig. l is a perspective view of a Stafford type cutter to which the invention has been applied.

Fig. 2 is a detail of part of the cutter showing the manner of operation of the cam.

Fig. 3 is a section at line 3-3, Fig. 2 showing certain details to an enlarged scale.

Now referring to Fig. 1, a cutter of the type described 2,752,955 Patented July 3, 1956 may include a bracket 10 within which is a guideway 11, a slide 12 movable in said guideway and extended laterally at 13 to terminate at 14 in a support means for the cutting and clamping instruments themselves. The bracket 10 is hung on an adjustable supporting structure generally indicated by numeral 15' in turn fixed on transferer stud 16. These parts are more or less conventional and need not be described in greater detail here.

The cutter and clamp parts include a stationary blade member 17 fixed in the support or holder 14. Pivoted at 18 are a movable cutter blade 19 at one side of fixed blade 17 and at its opposite side, a movable clamping blade 2tl, fiber blade 21 and a spring 22. The latter, in conjunction with a Belleville washer at the opposite end of the pivot, maintains the blades in operative engagement with the stationary blade.

The blade 20 continues to the other side of pivot 18 as arm 23 and that arm is laterally bent at its end to form a follower or projection 24 for engagement with a cam 25.

Cam 25 is set and locked in a slot in enlarged head 26 of a pivot or spindle 27, see also Figs. 2 and 3. This pivot is rotatable in a bearing in extension 28 at the rearmost end of bracket in and stop pinsgone of which is shown at 29, limit possible movement of the cam in each direction. A helical spring 3t has one end engaged about pin 29 and the other extended laterally over the top of the cam so that the latter is always biased toward the position of Fig. 1 where it is stopped against pin 29.

In operation the slide l2 is moved to the rear and then forwardly in timed relationship to the lay and motion of other parts at the transfer cycle. As it moves to the rear the follower 24 is moved downwardly below cam 25 thereby opening the cutter blades. As the follower passes below dead center of the pivot 27 it tilts cam 25 to nearly a horizontal position. As the lay moves forwardly slide 12 is retracted and follower 24 moves up cam 25 to close the blades thus severing the filling and clamping the end thereof which extends to the fabric.

Spring 30 is not particularly strong and. is designed to return the cam to the position of Fig. 1 immediately after the rearward motion of the parts. It cannot be strong enough to prevent the cam being tilted on its pivot and, of course, there is not too much resistance offered by the friction of blades 1? and 20 against the fixed blade.

In operation at higher speeds, it has been found that with a simple pivoted spring pressed earn, the follower has been bent or stripped from the arm at intervals. The cause of such destruction has been found to lie in the flutter or rebound of the cam. It actually bounces upwardly several times and if, as the parts move to the front, the follower 24 engages more or less squarely against the end of cam 25, the result is necessarily disastrous to some one or more of the parts.

It is not practical to increase the spring force since then, the cam would not be swung on its pivot as the friction at the blades would be insufi'icient to elfect that. To overcome the trouble, however, it has been found that a damping means at the cam pivot is most effective and makes possible the use of a relatively weak spring and consequently no excess pressure at the blades.

This damping means may take any one of several forms, but a preferred, simple and inexpensive form, as herein shown, is based upon friction. The extension 28 to the bracket is bored or recessed as at 31 for a spring 32 under compression when the parts are assembled and a retaining member, e. g., E-ring 33, locked in place. A nut and check nut may be used in which event the spring may be adjustable. Other resilient means may be used, and, if desired, the pivot may be longer and the spring positioned externally of the extension 28.

In effect the spring forces spindle 2'7 to the right, Fig.

3, so that the shoulder 34 at head 26 is pulled into frictional contact with the adjacent face of the extension 28. In some cases a fibre or other washer may be effectively utilized as a friction surface. The slight friction resistance to return of the parts after the cam has been moved to its extreme position virtually eliminates rebound and thus the cam immediately settles to its proper position before the return or forward movement of the slide.

The cutter is moved to the rear of the loom by certain well known means effective at transfer and acting upon or through stud 35, Fig. 1. The return to the front is under influence of the lay as it engages adjustable, abutment screw 36.

While one embodiment of the invention has been disclosed, it is to be understood that the inventive concept may be carried out in a number of ways. This invention is, therefore, not to be limited to the precise details described, but is intended to embrace all variations and modifications thereof falling within the spirit of the invention and the scope of the claims.

I claim:

1. In a Stafford type thread cutter for looms, a supporting bracket having therein a guideway, a slide movable in said guideway and a cutter and clamping means carried by said slide, said cutter and clamping means comprising stationary and movable blade members, means for actuating said movable blade members including a cam, pivot means in said bracket for said cam, resilient means for urging said cam to one extreme position, stop means for limiting movement of the cam as affected by said resilient means, and a follower on one of said blade members engageable with one side of the cam as the slide and cutter are moved in one direction and with the opposite side of the cam when said parts are reversely moved, said cam being swung about its pivot against the tension of the resilient means at each such movement of the slide and cutter and having a tendency to rebound as it strikes the stop means when returned by the spring, and damping means at said pivot for preventing such rebound of the cam.

2. In a Stafford type thread cutter for looms, a supporting bracket having therein a guideway, a slide movable in said guideway and a cutter and clamping means carried by said slide, said cutter and clamping means comprising stationary and movable blade members, means for actuating said movable blade members including a cam, pivot means in said bracket for said cam, resilient means for urging said cam to one extreme position, stop means for limiting movement of the cam as affected by said resilient means, and a follower on one of said blade members engageable with one side of the cam as the slide and cutter are moved in one direction and with the opposite side of the cam when said parts are reversely moved, said cam being swung about its 4 pivot against the tension of the resilient means at each such movement of the slide and cutter and having a tendency to rebound as it strikes the stop means when returned by the spring, and frictional damping means at said pivot for preventing such rebound of the cam.

3. in a Stafford type thread cutter for looms, a supporting bracket having therein a guideway, a slide movable in said guideway and a cutter and clamping means carried by said slide, said cutter and clamping means comprising stationary and movable blade members, means for actuating said movable blade members including a cam, pivot means in said bracket for said cam, resilient means for urging said cam to one extreme position, stop means for limiting movement of the cam as affected by said resilient means, and a follower on one of said blade members engageable with one side of the cam as the slide and cutter are moved in one direction and with the opposite side of the cam when said parts are reversely moved, said cam being swung about its pivot against the tension of the resilient means at each such movement of the slide and cutter and having a tendency to rebound as it strikes the stop means when returned by the spring, and damping means at said pivot which comprises a resilient means under compression and cooperating surfaces, one on said pivot and another on the bracket, held in frictional contact by said resilient means.

4. In a Stafford type thread cutter for looms, a supporting bracket having therein a guideway, a slide movable in said guideway and a cutter and clamping means carried by said slide, said cutter and clamping means comprising stationary and movable blade members, means for actuating said movable blade members including a cam, pivot means in said bracket for said cam, resilient means for urging said cam to one extreme position, stop means for limiting movement of the cam as affected by said resilient means, and a follower on one of said blade members engageable with one side of the cam as the slide and cutter are moved in one direction and with the opposite side of the cam when said parts are reversely moved, said cam being swung about its pivot against the tension of the resilient means at each such movement of the slide and cutter and having a tendency to rebound as it strikes the stop means when returned by the spring, and damping means at said pivot which comprises a shoulder on said pivot, a recess in said bracket, a spring in said recess and retaining means on said pivot opposed to said shoulder by which the spring is maintained under compression.

References Cited in the file of this patent UNITED STATES PATENTS 2,223,896 Nichols 'Dec. 3, 1940

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