US3083553A - Cutting assembly for circular knitting machines - Google Patents

Description

April 2, 1963 J. DE Moss ETAL CUTTING ASSEMBLY FOR CIRCULAR KNITTING MACHINES Filed July 20, 1961 FIGI.

FIJG. 2.

INVENTORSI J OHN DeMOSS ROBERT PE E L ATTYS.

United States Patent 3,083,553 CUTTING ASSEIVIBLY FOR CERCULAR KNITTING MACHKNES John De Moss, Somerdale, N1, and Robert Peel, Phiiadeiphia, Pa., assignors to Singer-Fidelity, Inc, Philadelphia, Pa, a corporation of Delaware Filed July 20, 1961, Ser. No. 125,585 3 Claims. (Ci. 6614t3) This invention relates to cutting devices used on circular knitting machines, particularly ladies fine gauge seamless hose machines, where the ends caused by the yarn changes are cut short as knitting proceeds.

One type of such device is shown in U.S, Patent 2,824,- 383. These devices consist of a serrated ring Where the teeth are in close proximity to the back of the needles and rotate in synchronization therewith. The teeth are on the edge of what can be called a substantially flat ring. The flat surface of this ring engages a blade or similar cutter having a cutting edge. In some cases the cutting edge is raised out of action when not needed and in other cases is left in permanent contact with the rotating flat surface. The teeth of the flat serrated ring cooperate with the cutter or knife edge so that when a thread is entrapped in any tooth on the ring it is severed as it passes the point of engagement with the cutter. In practice this combination of mechanism sufiers from certain disadvantages associated with wear on both the ring and the knife or cutter, failure to cut due to foreign substances raising the cutter from the surface of the ring and the like. In practice, most of the known combinations of mechanism made in accordance with the above inventions have also required considerable skill in the initial setting to insure that they operate satisfactorily,

A primary object of the present invention is to obviate some of these difficulties and to completely remove the necessity for skilled adjustment in the initial setting.

Another object of the present invention is to provide an improved cutter assembly of simple manufacture which is self-aligning, self-cleaning, and self-sharpening.

More specifically, the present invention contemplates a serrated ring substmtially as shown in the above patents, and a cooperating cutter having a flat annular face with a sharp edge and placed on the fiat edge of the serrated ring with part of its circumference slightly overlapping the edge of the teeth with means to exert pressure forcing the annular face into fiat and intimate contact with the flat surface of the serrated ring.

All of the objects of the various features and details of the construction and operation thereof are more fully set forth hereinafter with reference to the accompanying drawing wherein:

FIG. 1 is a fragmentary plan view of the dial of a circular knitting machine embodying a cutting assembly in accordance with the present invention;

FiG. 2 is a side elevational view of the assembly as seen from the line 22 in FIG. 1;

FIG. 3 is a sectional view taken on the line 3--3 of FIG. 2; and

FIG. 4 is a perspective view of the cutting assembly.

Referring to the drawing, the knitting machine comprises a conventional rotary needle cylinder having a circle of needles 11 mounted therein. A dial 12 rotates with the needle cylinder and is covered by a stationary dial cap 13. A latch ring 15 surrounds the needle circle and comprises a part of the stationary frame of the machine. The latch ring mounts one or more feed stations (not shown) which operate in the usual manner to insert yarns into and withdraw yarns out of action,

In accordance with the invention, a cuttter mechanism is provided, preferably one for each feed station, for example as shown at 21. The cutter assembly 21 cooperates with a serrated or toothed annular ring 23 mounted on and for rotation with the dial 12. The upper face of the ring 23 is provided with a flat surface 2-5 projecting from the dial, and the teeth 24 of the ring 23 meet the flat portion 25 of the ring in cutting edges 25. The cutting assembly 21 cooperates with the cutting edges 26 to sever the yarns engaged by the teeth 24.

As shown in the drawing, the preferred embodiment of the cutter assembly comprises a cutter element 30 in the form of a short cylinder with conical indentations 31 on the two end surfaces thereof. Each of the end surfaces is lapped or ground to form a flat annular face 32 having a sharp edge 34 at the junction with the cylindrical surface 33. The lower annular face 32 of the cylinder is engaged with the flat surface 25 of the ring 23 with a part of its circumference overlapping the outer periph cry of the surface 25.

#Means is provided on the stationary dial cap 13 to accurately position the cylinder 30 and bias the annular face 32 thereof into fiat and intimate contact with the flat face 25 of the annular ring 23. In the illustrated embodiment of the invention, the positioning means comprises a spring finger 40 mounted on the dial cap 13 as indicated at 41 and having a resilient arm 42 disposed generally circumferentially of the annular ring 23. The free end of the arm 42 is provided with a depending toe 43 which terminates at its lower extremity in a point 44 which engages in the conical indentation 31 on the upper surface of the cutter element. The point contact of the leg with the cutter element permits the cutter to be self-aligning, so as to insure flush engagement between the annular face 32 and the upper surface 25 of the serrated ring. This automatic self-alignment of the cutter with the serrated ring eliminates the necessity for skillful installation and adjustment of the cutter and eliminates the necessity for the extremely close tolerances which were required in the prior cutter elements.

Because of the overlapping of the cutter with the outer periphery of the teeth 24 and the point contact between the leg 43 and the indentation 31, the frictional contact between the face 32 and the surface 25 during normal rotation of the serrated ring 23 causes the cutter to rotate about the leg point 44. As the cutter rotates, the rotation causes the entire annular face 32 of the cutting element to pass over the surface 25 and thereby maintains the annular face 32 and the edge 34 sharp and free of ridges or other indentations. The rotation of the cutter also operates to discharge any foreign matter which may lodge between the cutter and the serrated ring In this manner, the cutter assembly is both self-sharpening and self-cleanmg.

It is apparent that the cutter of the present invention is of extremely simple manufacture and can be readily produced in a variety of very hard steels or special alloys, such as tungsten carbide. Both the upper and lower surfaces 32 of the cutter may be lapped or ground to create two cutting edges 34, whereby the cutter may be reversed if one edge should become damaged or otherwise inefiective in use.

It is preferred to form the cutter element 30 as a cylinder with conical indentations in the upper and lower surfaces, but it is entirely possible to form the element as a cone, either truncated or pointed at the top. In this case, the cutter is held doum by a resilient flexible member having an aperture adapted to receive the upper end of the cutter. In such a case, the base of the conical member would be provided with a suitable indentation or ofiset to provide an annular face similar to the face 32. In this way, it is not necessary to provide the extreme flatness which would be otherwise required to insure proper cutting action.

After the cutter assembly has been assembled and put into operation, it is desirable to retain the cylindrical or other cutter in position while the assembly is partially dismantled, for example when lifting the dial cap from the dial. One method of accomplishing this is by using a magnetized element for the arm 40. Thus, when the serrated ring is removed from engagement with the cutter element, the magnetized arm retains the cutter element while adjustments were made in the knitting machine.

While a particular embodiment of the present invention has been herein illustrated and described, it is not intended to limit the invention to such disclosure, but changes and modifications may be made therein and thereto within the scope of the following claims.

we claim:

1. In a circular knitting machine having a rotary cylinder mounting a circle of needles, a toothed ring mounted for rotation with said cylinder adjacent to and within said needle circle, said toothed ring having an upper flat surface cooperable with said teeth to form a plurality of cutting edges, and a stationary dial cap superimposed on said ring; a cutter for 'yarn engaged in the teeth of said ring comprising a cutterelement having an annular face engaged flush against the fiat surface 'of said toothed ring, said annular face cooperating with said cutting edges to sever the yarn engaged in the teeth of said toothed ring,

4 said cutter element being mounted for self-alignment with said flat surface and being rotatable by said ring about the axis of said annular face.

2. Apparatus according to claim 1 wherein said annular face of the cutting clement projects beyond the outer periphery of said fiat surface whereby the frictional engagement of said annular face on the fiat surface of said toothed ring elfects rotation of said cutter element.

3. Apparatus according to claim 1 wherein said cutter element is generally cylindrical in form and is provided with a generally conical indentation on its upper surface coaxial with said annular face, and including a mount ing arm secured to said dial cap and having a point projecting into the conical indentation on said upper surface, said arm being resiliently fiexible'to thereby bias said cutter into flush engagement with said surface of the toothed ring, the point and said indentation cooperating to provide for self-alignment of said cutter.

References Cited in the file of this patent UNITED STATES PATENTS 2,592,019 Farnett Apr. 8, 1952 2,824,436 Stack et a1 Feb. 25, '1958 2,970,460 Mahler et al. Feb. 7, 1961

Claims (1)

1. IN A CIRCULAR KNITTING MACHINE HAVING A ROTARY CYLINDER MOUNTING A CIRCLE OF NEEDLES, A TOOTHED RING MOUNTED FOR ROTATION WITH SAID CYLINDER ADJACENT TO AND WITHIN SAID NEEDLE CIRCLE, SAID TOOTHED RING HAVING AN UPPER FLAT SURFACE COOPERABLE WITH SAID TEETH TO FORM A PLURALITY OF CUTTING EDGES, AND A STATIONARY DIAL CAP SUPERIMPOSED ON SAID RING; A CUTTER FOR YARN ENGAGED IN THE TEETH OF SAID RING COMPRISING A CUTTER ELEMENT HAVING AN ANNULAR FACE ENGAGED FLUSH AGAINST THE FLAT SURFACE OF SAID TOOTHED RING, SAID ANNULAR FACE COOPERATING WITH SAID CUTTING EDGES TO SEVER THE YARN ENGAGED IN THE TEETH OF SAID TOOTHED RING, SAID CUTTER ELEMENT BEING MOUNTED FOR SELF-ALIGNMENT WITH SAID FLAT SURFACE AND BEING ROTATABLE BY SAID RING ABOUT THE AXIS OF SAID ANNULAR FACE.

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