US3760608A

US3760608A - Thread cutting and retaining device for circular knitting machines

Info

Publication number: US3760608A
Application number: US00147981A
Authority: US
Inventors: F Lonati
Original assignee: Individual
Current assignee: Individual
Priority date: 1970-06-16
Filing date: 1971-05-28
Publication date: 1973-09-25
Anticipated expiration: 1990-09-25

Abstract

A thread cutting and retaining device for circular knitting machines for the manufacture of stockings and the like, suitable for employing stretch, elastic and normal type yarns, comprising at least one thread suction nozzle on a fixed structure above the dial of the circular knitting machine, at least one cutting element near said nozzle and at least one feed. The device further comprises a mechanical thread retaining unit on the periphery of said fixed structure formed from a clamp-like element with fluid control means for said clamp-like element in the open position and clamp-like element return means in the closed position.

Description

United States Patent 1 [111 3,760,608 Lonati Sept. 25, 1973 THREAD CUTTING AND RETAINING 3,097,512 7/1963 Moyer 66/140 5 DEVICE FOR CIRCULAR KNITTING 3,367,146 2/1968 A1lred..... 66/140 S UX MACHINES 3,379,036 4/1968 Farmer 66/145 R [75] Inventor: Francesco Lonati, Brescia, Italy FOREGN PATENTS OR APPLICATIONS 7 2 7 B [73] Assignee: Construzioni Meccaniche Lonati di Loy/'22 H96 Great mam S Lona" Francesco Brecla Italy Primary ExaminerRobert R. Mackey [22] Filed: May 28, 1971 Attorney-Guido Modiano and Albert Josif 21 Appl. No.: 147,981

, [57] ABSTRACT [30] Foreign li i p i Data A thread cutting and retaining device for circular knit- June 16 1970 Ital 26041 N ting machines for the manufacture of stockings and the y like, suitable for employing stretch, elastic and normal 52 U.S. Cl 66 s 66 5 type Yams mPr1smg at least thread Int Cl D04b/15/61 zle on a fixed structure above the dial of the circular [58] Fieid S 145 s knitting machine, at least one cutting element near said 6/l45 nozzle and at least one feed. The device further com- I prises a mechanical thread retaining unit on the periph- References Cited ery of said fixed structure formed from a clamp-like e1- ement with fluid control means for said clamp-like ele- UNITED STATES PATENTS ment in the open position and clamp-like element re- R25,584 5/1964 Stack et a1 66/140 S tum means i h l d position 2,908,154 10/1959 Butler 66/145 S UX 3,077,097 2/1963 Butler 66/140 8 3 Claims, 5 Drawing Figures PATENIEUSEPZSISH 3.760.608

sum 1 or 2 I NVE NTOR FRANCESCO LONATI M NH PATENTED8EP25I973 V a 760 608 sumaorz l THREAD CUTTING AND RETAINING DEVICE FOR CIRCULAR KNITTING MACHINES BACKGROUND OF THE INVENTION This invention relates to a thread cutting and retaining device for circular knitting machines with several feeds for the manufacture of stockings and the like.

At the present state of the art, in circular knitting machines for the manufacture of stockings and the like, pneumatic suction nozzles are provided to retain the thread after it has been cut, or when it is not subjected to processing in such a way so as to then allow an easy recovery of the thread when it must again be used for the knitting .of the tubular manufactured article.

In these machines, to the above mentioned suction nozzles, cutting devices are associated, arranged in a position close to the trajectory of the needles, in a way that the cutting occurs near the last stitch carried out by the needles on the thread to be cut. The cutting means are arranged downstream from the nozzles, considering the rotational direction of the needle cylinder, and somewhat close to the nozzles.

Said thread cutting and retaining means have however various disadvantages, when the machine has four or more feeds. In particular, such disadvantages are made more evident as the number of feeds increases, a higher number of feeds being increasingly in request in the present art for a more rapid manufacture of the stockings or socks.

In fact, in a machine with many feeds, these feeds must be arranged very close along the periphery of the needle cylinder, so that some of them are necessarily very near to the cutting devices. In this way the feeding thread, or yarn cut by the cutting elements, has very short free end, so that it becomes very difficult, if not impossible, to make its retention secure by the suction of the relative nozzle. This fact involves still more serious problems in that the thread is'tensioned during the cutting operation and once the cutting has been carried out, it is abruptly released. This releasing can result in unthreading of the yarn off the thread guide, such an effect being increased by the braking action which is exercised on the thread upstream of the thread guide.

In other words, with the multifeed machines, it is difficult to possibly guarantee, for all the feeds, a secure retaining of the thread by means of the suction-nozzles and, thus a secure manufacturing, without spoiled work and machine stops.

The non-retained thread cannot then be hooked by the needles for subsequent processing thereof.

The problem mentioned above is then still more serious when the so-called stretch thread is used for the manufacture of stockings, having a particular elasticity. With the machines having more than four feeds at present in use, manufacturing with such a type of thread is practically impossible.

SUMMARY OF THE INVENTION One object of the present invention is that of eliminating the above mentioned disadvantages by providing a thread cutting and retaining device to be applied to circular knitting machines with several feeds for the manufacture of stockings and the like, which allows in every case the retaining of each thread, from any feed, and which also allows in a satisfying way the processing of the so-called stretch yarns.

Another object of the present invention is that of conceiving a device of the above mentioned type which may be easily installed, even on multifeed circular machines already in use.

A further object of the invention is that of providing a thread cutting and retaining device of secure operation and economic production.

According to the invention, there is provided a thread cutting and retaining device for circular multifeed knitting machines for the manufacture of stockings and the like, particularly those having four and more feeds, comprising at least one thread suction nozzle arranged on a fixed structure mounted above the hook carrying dial of the circular knitting machine, at least one cutting element arranged near said at least one nozzle donwstream thereof relative to the rotational direction of the needle cylinder, as well as at least one feed corresponding to said at least one suction nozzle, the device having a mechanical thread retaining unit cooperating with said at least one suction nozzle arranged on the periphery of said fixed structure at a feed upstream from said cutting element, and formed from a substantially clamp-like element for the reception of the thread not in use. Preferably fluid operated control means of said clamp-like element in the open position is provided as well as return means for said clamp-like elements to the closed position.

BRIEF DESCRIPTION OF THE DRAWING The invention will better appear from the description of a preferred but not exclusive embodiment of the invention, illustrated by way of an indicative and not limitative example in the accompanying drawings in which:

FIG. 1 is a side view of the unit carrying the cutting and retaining device according to the invention, arranged above the dial,

FIG. 2 is a view from below the device, according to the invention, the dial being removed,

FIG. 3 is aplan view of the device showing the relationship between the elements of the device and the feeds of the thread, and

FIGS. 4 and 5 show at a larger scale and in a perspective view a detail of the retaining means in closed and in open positions, respectively.

DESCRIPTION OF THE PREFERRED EMBODIMENT With reference to the above mentioned figures, the present device comprises a thread retaining unit including a multiarm lever or clamp element la rotatable about a pin 2 and having one end 3 loaded by a spring 4. This spring is fixed to a plate element 4a, in turn mounted on a fixed structure 7 at 4b, at which point a resilient tang 40 also terminates, which acts on the lever element or plate-like element 1a. The other two ends of said plate-like element are shown at 5 and 6, respectively. On the structure 7, there are two plate-like elements of the above mentioned type, symmetrically arranged with respect to the axis of the structure 7 carrying the unit. On the base 7a, there are'further provided two inclined notches 7b, one at each of the plate-like elements la, in such a way so as to be freely accessible to the thread when these plate-like elements are in the open position, corresponding to that shown by broken lines in FIG. 1. On the base 7a there are also provided holes 8 from which two

suction nozzles

9 and 10 lead,

within which end spouts 9a and 10a of two

canals

9b and 10b open.

For the operation of the retaining devices 1, pneumatic devices 11 are provided (in FIG. 1 only one has been shown), one for each retaining unit 1, terminating with a projecting end 12 in contact with the end 5 of the plate-like element la.

The device according to the invention further comprises a cutting element visible in FIG. 1 and generally indicated at 13, arranged a little after the retaining device l, in the rotational direction of the needle cylinder. Said cutting element is formed from a cutting blade 14, rigid with a rod 15, movable in a vertical direction and guided in a hole provided in a structural frame a. A spring 150 wound around the rod 15 at the upper part thereof, pushes a cutting blade 14 towards the bottom having locations from one part on the structure 15a and from the other on a block element 15b, rigid to the rod 15.

On the dial there is fixed a so-called milling cutter 22, cooperating with the cutting element 13, in the direction in which the blade 14 slides'on the flat upper surface of the milling cutter and cuts off the thread which is hooked and dragged into the teeth of the milling cutter when it is withdrawn from active feeding position.

Rigid to the base 7a is also a retaining unit of the socalled elastic type shown at 16 and comprises a rod 17 ending with a square end 18 housed in nonoperative condition, in a suitable slot or seat 19 provided in the base 70. The rod 17 is vertically guided in the structure 7. A spring 21 winds around a portion of said rod 17, tending to maintain it in a raised position shown in FIG. 1, that is with the end 18 housed in the seat 19.

The operation of the thread retaining and cutting device according to the invention is illustrated in the following, by making reference firstly to the case of knit ting thread of normal and of so-called .stretch" type, and then to the case of knitting thread of the so-called elastic type, this latter being used for the manufacture, for instance, of the elastic upper zone of the stockings.

The sequence of the cutting and retaining operations in the case concerning normal yarn and in the case concerning stretch yarn, if withdrawal of the yarn from active feeding position is desired is the following: first of all the thread guide is raised and a simultaneous action of the element 11 on the plate-like element 1a takes place in the direction to bring it into the open or first position shown by broken lines in FIG. 1, in which the notch 7b remains freely accessible to the thread. Following the rotation of the needle cylinder and the raising of the thread guide, the thread is drawn by the teeth of the milling cutter 22 and contacts the blade 14 which cuts it off. At this point the free end of the thread begins to feel the effects of the suction nozzle, which tends to bring it towards the center of the device, making it be introduced into the notch 7b, as shown in FIG. 5. A command from unit 11 frees the plate-like element 1a which, under the action of the spring 4, is carried into a second position shown by the continuous line in FIG. 1, clamping the thread in the notch 7b, as shown in FIG. 4. In this way the thread is securely held and is impeded from any possible detaching from said notch by the thread guide. In particular, this advantageously occurs when the thread from the feed which is the nearest to the retaining device 1, is cut. In fact, the cut thread, whose end is very short (it should be remembered that on the periphery of the structure 7 there are arranged, for example, eight feeds as shown in FIG. 3), might not sufiiciently feel the effects of the return action of the nozzle and could, both for its elasticity and for the restraining exercised on it upstream from the thread guide, escape from the thread guide which supports it.

When the thread must be changed, for example, from one type of thread to another type, or in general, always when a thread must be introduced into the process, there is lowered first the relative thread guide, in a way to knit the thread, and then the retaining device 1 with a command from the pneumatic device 11 is opened so that the end of the thread in question is freed.

It is understood, that in the same notch 7b, several threads may be held simultaneously from the same feeding unit.

The resilient tang 40 serves to press the plate-like element 1a against the structure 7, in such a way to assure the secure retaining of the threads.

During the sucking phase of the thread supported by the thread guide nearest to the retaining device 1, for a thread which has already been cut, the sucking action is increased by blowing air through the

spouts

9a or 10a, in a way to improve the sucking effect on the thread. The sucking in the

canals

9 and 10 is continuous.

If it is desired now to carry out the same operation for the elastic thread, which is introduced into the manufacturing for certain particular parts of the socks or stockings, the procedure is partly as for the normal thread or the stretch-thread, only that the retaining device 1 is no longer made use of, but the device 17 is used instead. In fact, for the insertion of the elastic thread, the relative thread guide is lowered and, when the thread has been knitted, the rod 17 is lowered which frees the thread held in it.

For the exclusion of the elastic thread, first of all the thread guide is lifted and the lowering of the rod 17 is operated, while the thread is hooked in it. At this point, the return of the hook, in the position in which the appendix 18 is placed in its seat 19, is operated, with which the retaining of the elastic thread is obtained, and the cutting of the thread in the way already said for the normal thread is provided.

As can be seen, the device according to the invention allows secure retaining for each type of thread and for all the threads of all the feeds. In particular, the threads of the feeds farthest from the cutting device can be held by the single sucking effect of one of the two nozzles, as occurs in conventional machines having a small number of feeds, because the free end of the cut thread is sufficiently long to be able to be held without difficulty.

The cutting and retaining device thus described is susceptible to numerous modifications and changes, all falling within the scope of the invention. Thus the number of retaining and cutting units may be different from two, as has been assumed in the example described.

The materials used, as well as the dimensions and the shapes of the various elements forming the invention, may be any according to the requirements.

I claim:

I. In a circular knitting machine for the manufacture of stockings and the like, including a needle cylinder, at least one feed for a thread to be knitted, a hook carrying dial and support structure arranged above said dial, a thread cutting and retaining device including means arranged to cut said thread and to retain the cut end portion of said thread, respectively, said cutting means comprising a circular toothed blade coaxial to said dial and a cutting blade arranged on said support structure for cooperation with said circular toothed blade for cutting the thread, and said retaining means comprising at least a suction nozzle for holding the end portion of said thread cut by said cutting means, a clamp element pivoted on said support structure and a substantially inclined notch provided on said support structure adjacent said clamp element for receiving said end portion cut by said cutting means and sucked by said suction nozzle, said clamp element having an operative portion movable from a first position in which said portion leaves said notch accessible to said end portion of the thread to a second position in which said portion closes said notch clamping said end portion of the thread arranged therein, means being provided for actuating said clamp element to move from said first position to said second position and from said second position to said first position.

2. A device as claimed in claim 1, wherein said clamp element comprises a plate-like element having three arm portions extending in three different directions, said plate-like element being povoted on said support structure substantially tangentially to said dial, the first of said arms being provided with said operative portion laterally covering said notch in said second thread retaining position, and wherein said means for actuating said clamp element comprise resilient means acting on a second of said arms and fluid operated means acting on a third of said arms against the action of said resilient means.

3. A device as claimed in claim 1, wherein said retaining means further comprise a resilient tang anchored to said support structure and having a free end in contact with said operative portion of said clamp element, said tang urging said element towards said support structure for increasing the clamping action on said thread.

Claims

1. In a circular knitting machine for the manufacture of stockings and the like, including a needle cylinder, at least one feed for a thread to be knitted, a hook carrying dial and support structure arranged above said dial, a thread cutting and retaining device including means arranged to cut said thread and to retain the cut end portion of said thread, respectively, said cutting means comprising a circular toothed blade coaxial to said dial and a cutting blade arranged on said support structure for cooperation with said circular toothed blade for cutting the thread, and said retaining means comprising at least a suction nozzle for holding the end portion of said thread cut by said cutting means, a clamp element pivoted on said support structure and a substantially inclined notch provided on said support structure adjacent said clamp element for receiving said end portion cut by said cutting means and sucked by said suction nozzle, said clamp element having an operative portion movable from a first position in which said portion leaves said notch accessible to said end portion of the thread to a second position in which said portion closes said notch clamping said end portion of the thread arranged therein, means being provided for actuating said Clamp element to move from said first position to said second position and from said second position to said first position.