US1455370A - Circular-knitting machine - Google Patents

Description

May 15', 1923. 1,455,370

R. W. WALTON CIRCULAR KNITTING MACHINE Filed Sept. 17. 1921 M/VE/VTOR Patented wit- 15, was.

ROBERT W. WALTON, 0F PHILADELPHIA, PENNSYLVANIA.

CIRCULAR-KNITTING MACHINE.

Application filed September 17, 1921. Serial No. 501,316.

T 0 all whom it may concern:

Be it known that I, ROBERT V. lVAL'roN, a citizen of the United States, residing at Philadelphia, county of Philadelphia, and State of Pennsylvania, have invented a new and useful Improvement in Circular-Knitting Machines, of which the following is a full, clear, and exact description, reference being had to the accompanying drawings, which form a part of this specification.

My invention relates to circular knitting machines, more especially those knitting continuous tubular fabric in the manufacture of hosiery. This tubular fabric is afterwards cut into lengths, upon which foot portions are knitted, and it is common practice to knit what is termed a loose course near the end of each of said lengths for the following reason.

After being cut into lengths, as described, each piece is mounted by hand on a transfer ring. This ring comprises a circle of points equal in number to the needles in the circular knitting head and one end of each piece is pressed onto this ring so that one of the points projects through each individual loop in one of the courses of the tubular fabric near the end of the piece. This is called the topping operation. The ring is then inverted over the knitting head of a machine for knitting the foot portion and the loops are transferred from the points to the needles of the machine whereby everything is in readiness for the operation of knitting the foot onto the length of tubular fabric.

Therefore, after a certain length of regular tubular fabric has been knitted, the machine is set to automatically knit a course of elongated stitches wherein the yarn is pulled out to a greater length by the needles for the pur ose of facilitating the topping operation. owever. it is found in practice that the knitting of this loose course is very apt to produce drop stitches, necessitating a mending operation before the piece is ready for topping, adding appreciably to the time and cost of production. It is to obviate this difficulty that my invention is designed.

It is customary to knit the stocking fabric with two threads of yarn. In the process of knitting, one of these threads is bound to be in greater tension than the other, with i the result that in the'loose course the tighter needles below their regular knitting depth and at the same point a cam is introduced beneath the dial needles for raising them up, thus lengthening the distance between the heads of both sets of needles just at the point where the yarn is fed in and therefore drawing longer loops.

, Drawing the longer loops tends to pull up on the cylinder needles with the result that directly their butts have passed thelowest point of the depressed knitting cam, they are at once raised up to the guard cam. This immediate raising of thecylinder needles, together with the lowering of the dial needles to their regular level directly they have passed the cam at the knitting point, produces such a slack in the fabric between the needles that many stitches are dropped.

In my invention I provide means for lowering the guard cam just following the lowering of the main stitch cam with the result that when the cylinder needles pass the lowest point of the stitch cam they are not allowed to be drawn up as heretofore, but their butts, striking this lower guard cam, are deflected gradually to their normal level, and the loops on the needles are not allowed to become so slack as to fly off and form drop stitches.

Having now described in general terms the object of my invention, the necessity for and value of which will be readily understood and appreciated by those skilled in the art, I will proceed with a detailed description of mechanism employed in lowering the guard cam as described in connection with the accompanying drawings, in which,

Fig. 1 is a diagrammatic showing of a section of fabric showing a loose course.

Fig. 1 is a similar view showing dropped stitches.

Fig. 2 is a cross-section through one side of the knitting head of the machine, showing the dial and circular needles at the knittin point.

ig. 3 is a plan view of a portion of the cam ring embodying my invention.

Fig. 4 is a developed front view of the mechanism shown in Fig. 3.

Fig. 5 is a rear or outside view of the mechanism shown in Fig. 3.

The cylinder stitch cam' a is secured to post I) which is vertically slidable through the top 0 of the cam ring, and normally pressed upward by a spring not shown, as is old and well known in the art. Post 6 carries a head d, in the form of a cam plate, which is adapted to be actuated by set screws 6 in an arm f secured to a pivot post 9 mounted in the cam ring. An adjusting screw t, which overhangs the edge of plate d, limits the upward movement of the knitting cam. A clamp h is mounted on the set .screws and carries a cam 71 for acting on the dial needles j. Pivot post 9 carries an arm which projects beyond the cam ring and is actuable by well known means to turn the pivot post'and with it arm f.

I have mounted the guard cam m on a post 7, vertically slidable through top 0 of the cam ring and normally held up by spring 0 so the cam is against under side of top 0, as indicated in broken lines in Fig. 4. For depressing the guard cam, I provide a twopiece block 1) clamped to set screws 9 screwed into arm 7 in such a position that a beveled portion 1 of the block will act upon the similarly beveled top of post n, in the inward turning of arm 7, to depress said post. By loosening the clamp of block p and screwing set screws 9, the block may be adjusted to give post n and guard cam m the downward movement required.

Normally arm f is turned outwardly so its set screws 6 are out of action with regard to cam plate d. When a loose course is to be knit, as hereinbefore described, arm is is actuated to turn arm 7 inwardly until set screws e contact with and override plate d, pressing it downward and with it the knitting cam a to lower the cylinder needles 8. At the same time cam '5 acts to raise the dial needles 9' and lengthen the pull of the yarn between the two sets of needles. While the knitting cam a is being depressed by set screws 0 moving on the cam face of plate (2, the beveled corner 1 of block 17 contacts with post 71 and starts to depress it and with it the guard cam m. When arm 7 completes its inward turn, both cams a and marrive at their lower position and remain so until the loose course is completed when arm f is withdrawn and they again rise to their normal knitting osition.

This metho of action, whereby the stitch cam leads in the downward movement and is followed by the guard cam, is newssary in order not to put an extra'strain on the loops formed just before the cam was lowered, which would be stretched and broken if the two cams acted simultaneously.

In the knitted fabric indicated in the diagrams, Figs 1 and 1 the two strands of yarn should always act together as if they were a single thread. A perfect loop in the loose course is thus indicated at m, and 3 indicates drop stitches of one of the strands, the tighter thread being held on the needles and knitted, as previously described. It will be understood that when knitting with a single strand, the thread is liable to be thrown off the needles on the loose course in a similar manner, so that my invention applies equally for use in knitting with single or double threads.

The advantages of my invention result from the provision of means for maintaining the cylinder needles depressed for a. short distance beyond the low point of the stitch cam for the circular needles and thereby maintain the newly formed loops under tension, which will prevent the dropping of stitches. By maintaining the I c linder needles depressed for a short time a ter the loops have been formed, I am not only enabled to form a loose course without danger of dropping stitches, but am enabled to form a very much looser course than heretofore, which is very desirable to facilitate transferring, and at the same time I am enabled to make a loose course having very long stitches without lowering the stitch cam a great extent. This I am enabled to do as the needles, as they pass under the stitch cam, draw the yarn from the yarn supply only and not from the yarn supply and the newly formed loops on the needles, which have just passed under the stitch cam.

By depressing the guard cam a short time after depressing the stitch cam, I avoid all danger of straining the short s formed on the cylinder needles just prior to the lowering of the stitch cam.

The two cams are arranged to reach their lowest position and act upon the needles at substantially the same relative time-relative as regards the needles. That is, by the time the first needles passing under the lowered stitch cam reach the guard cam, it alllso is in lowered position, then and not till t en.

The lag of the ard cam is equivalent to the time it takes t e needles to pass from the low point of one cam to the lowpoint of the other. This allows the needles to be thrown off, and does not unduly strain the last preceding short loops as the guard cam curves off from this point allowin the needles to rise, and also those last few 5 ort loops draw some thread from th first long ones.

Similarly, at the end of the loose course, the stitch cam leads in the rising movement by just the time it takes the last long 100 needle to reach the low point of the guar cam. Then and. not till then does the guard cam rise, which serves to keep suflicient tensidn on the last long loop to prevent itsbeing thrown off and yet does not unduly stretch the first short loops for the same reasons given in the other case.

Havin now fully described my invention what I c aim and desire to protect by Letters Patent is: a

1. In a circular knitting machine, in combination, cylinder needles and dial needles, a knitting cam and a guard cam for the cylinder needles, loose course cams for both cylinder and dial needles, a shift cam for depressing the guard cam, and means for actuating theiloose course and shift cams, said means being arranged to cause the shift cam to operate directly after the operation of the loose course cams.

needles after their depressing means hasacted, whereby drop stitches are prevented.

3. A circular kmtting machine comprising needles, a stitch cam and a guard cam, means to depress the stitch cam to cause the needles to raw longer loops, and means to depress the guard cam to prevent the needles rising toohigh after the first named means has acted, whereby said loops are maintained taut enough to prevent their being thrown ofi to form drop stitch 4. In a circular knitting machine, dial needles and cylinder. needles and a guard ,cam for the cyl a stitchcam md ne e means for produclnga loose course 'compnis ing a cam for depressing the stitch. am,

arm for actuating said depressing cam a cam mounted on said arm for ralsmg the dial needles, another cam on said arm for the stitch and then similarly shifting the guard cam, while knitting, sufiiciently 'to prevent the too sudden-shortening o f the stitch.

6. A cam cylinder for knittin -g machines having .a stitch cam, a nerd cam, and a lever for lowering the stitch cam a certain distance and then lowering the guard cam a less distance.

7. In a circular knitting machine, mean's for knitting a loose course comprising a movable stitch cam and an arm for depressing said stitch cam, a movable guard cam, and a cam on said arm for depressing the guard cam when the stitch cam is depressed.

In testimonyof which invention I have hereunto set my hand, at Philadelphia, Pa., on this 14th day of September, 1921.

ROBERT W. -WA-LTON.

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