US2818713A - Knitting machine - Google Patents

Description

Jan. 7, 1958 A. w. H. PORTER KNITTI'NG MACHINE April' ze, 1954 Filed Inventor Azz/w h/uL/AM /m/ Faim? A ltornevs KNIT'HNG MACHINE Allan William Henry Porter, Burton-on-Trent, England,

assigner to F. N. F. Machinery Manufacturing Company Limited, Burton-on-Treut, England, a British company Application April 26, 1954, Serial No. 425,445

8 Claims. (Cl. titi-125) lIt is necessary in knitting fabrics to ensure that the stitches in the fabric remain of uniform size from course to course, both from the point of view of quality, appearance, and economy. The size of the stitches depends upon the tension under which the yarn is fed to the needles, and knitting machines are provided with various arrangements for ensuring that this remains constant throughout the knitting of a piece. It is desirable, however, to have some means of checking that the same length of yarn is being knitted into each course, and this is commonly done by marking one of the yarns at intervals as it moves towards the needles, and measuring how far the mark has moved towards the needles after a standard number of courses.

In at warp knitting machines, this is usually achieved by marking one of the outermost selvedge warp threads before it reaches the tension bar. Instead of passing over the tension bar directly to the warp guides, the marked thread is led through an eye at the end of the tension bar, along the length of the tension bar to a similar eye at the other end from where it passes to the warp guides to be knitted in to the selvedge on the opposite side of the piece to that on which it started.

The mark is made as the yarn passes through the first guide eye, after which the machine is restarted and after running a half rack, that is to say 240 knitting cycles, the machine is stopped again and the distance from the iirst guide eye to the mark is measured. Clearly this gives the amount of yarn consumed in 240 courses and subsequent checks carried out at later stages in the knitting of the same piece should yield the same result. To carry each check out involves stopping the machine twice with consequent loss of production and time. The fact of stopping the machine twice each time such a quality check is made increases the possibility of two additional faults in the fabric, and consequently lowers the grade of the fabric piece goods. This is caused by slight unbalance of the knitting mechanism due to changes of local accelerations and to backlash in pins of the mechanism as the machine slows down and starts up again. These marks are commonly called stopping and starting shades.

By means of the present invention, a constant check on the rate of consumption of yarn per course can be maintained automatically as the machine is running so that shade marks are avoided and no time is lost and the operator is easily appraised of any deviations and can make the ne-cessary adjustments all without stopping the machine.

The invention consists in marking the yarn automatically at intervals separated by predetermined numbers of courses or knitting cycles, and providing a graduation or index mark at the point which the yarn should have reached after a xed number of cycles, preferably after the same interval as the interval between the markings.

The index may consist of a short scale across which the marked thread is guided, marked with a zero at the center and graduated in eighths of an inch on either side of this mark, Preferably an arrangement is made to il- Patented Jan. 7, 1958 ice luminate the scale at the moment when a mark ought to be passing over the zero graduation so that the operators attention is drawn to the index at that moment and the necessary che-ck can be made.

The timing of the marking mechanism which may be mechanically or electrically operated, and the illumination of the scale, are taken preferably from a shaft of the knitting machine which revolves once every half rack.

The material produced by flat warp knitting machines is generally doubled and seamed edge to edge for dyeing and finishing in a tube. When the fabric is made up into a tube it can quite easily be distorted if the same points on opposite edges are not sewn accurately together. By use of two marking devices according to the invention operating on selvedge threads from both sides of the beam-travelling across to be knitted into the selvedge at the opposite edges, marks can be made simultaneously on the two threads so that these appear exactly opposite each other in the two selvedges, Iso that it is an easy matter when forming the fabric into a tube to ensure that these points come exactly together.

An example of an indicator according to the invention, fitted to a flat warp knitting machine, is shown in the accompanying drawings in which:

Figure 1 is a perspective View of the machine showing thefgeneral arrangements of the marking device;

Figure 2 is a plan view of the tension bar to which the device is fitted;

Figure 3 is a front elevation of the tension bar;

Figure 4 is a circuit diagram.

`ln Figure l a sheet of warp yarns 1 is drawn from a positively driven beam 2 and pass over a tension bar 3 to the knitting mechanism 4 from which the knitted fabric is wound on to a roller 5. A selvedge yarn 6 passes through a guide eye 7 mounted above the tension bar 3 and then traverses across the sheet of warps 1 to a guide eye 8, mounted above the tension bar, from which it passes over the tension bar 3 and down -to 4the knitting mechanism 4 where it is knitted into the selvedge at the edge of the cloth.

In Figures 2 and 3, the guide eye 7 is supported in a holder 9 carried on a horizontal transverse bar 10 supported at each end in brackets 11 on the tension bar 3. The guide eye 8 is similarly supported at the opposite end of the bar. A scale plate 12 is supported on the bar 1t) by brackets 13 having a shade 14 beneath which is a small tubular electric lamp 15. Guide eyes 16 are provided at each side of the scale plate 12 so as to ensure that the yarn passes immediately over the scale graduations 17. The brackets 13 can slide on the bar 10 and the scale plate can be yfixed in any particular position by a thumb screw 18. A bare wire 33a is stretched above the bar 10, and supplies current -to the lamp 15 through a sliding spring contact 34.

At the right hand end of the bar 10 is mounted the mechanism for marking the yarn. This comprises an anvil 20 having an absorbent surface 21 to which ink is supplied from a reservoir 22. The yarn is pressed against the absorbent surface 21 at intervals, by a pressure piece 23 formed on the forked end 24 of an armature 25 pivoted between lugs 26 by means of a pin 27, and attracted towards the anvil 20 by means of an electromagnet 28. The movement of the armature Z4 in each direction is limited by stops 29, 30. Y

The circuit of this electro-magnet 28 and the lamp 15 is shown in Figure 4, from which it will be seen that the lamp 15 and magnet 28 are connected in parallel to the secondary of a transformer 3l through a normally open micro-switch 32. The operating plate of this switch is arranged so as to be engaged by a tappet carried on a slowly rotating shaft geared to the knitting mechanism, a suitable shaft being that driving the take-up roller 5,

Thus, once in each revolution of this shaft, the microswitch 32 is closed, the lamp is illuminated, and the magnet is excited. The position of the scale plate 12 is set on the bar so that, for knitting a particular fabric, when knitting at the correct tension, the mark made by the armature 25 reaches the zero mark on the scale 17 by the time the micro-switch 32 isneXt closed.

When two selvedge threads, one from each of two beams, are to be marked and knitted into the cloth ,addi- : tional guide eyes 33, 34a are provided on the bar 1?, which also carries a `second scale plate 35 also provided with a lamp and spring contact 34. A second marking apparatus may be clamped `to the end 30u of the bar 10.

`I claim:

l. Apparatus for ascertaining at predetermined intervals variations in the average rate of feed of yarn per stitch in a flat warp knitting machine having a positively driven warp beam let-oi mechanism, comprising mechanism for marking a yarn at time intervals of a predetermined number of -courses of stitches, an adjustable indeX mark, means to lead the marked yarn past the `said mark and thence to the knitting point, and indicator means operable at intervals of the said number of courses.

2. Apparatus according to claim l, in which the indicator means and the marking mechanism are operated simultaneously.

3. Apparatus according to 1claim v1, in which the indicator means is a lamp illuminating the index mark.

4. Apparatus according to claim 1, in which the at warp knitting machine further comprises a tension bar and in which the means to lead the marked yarn cornprises guides at each end of said tension bar, and said index mark is adjustably mounted on said tension bar.

5. Apparatus according to claim 4, in which the index mark is part of a scale mounted adjustably on the tension bar.

6. Apparatus according to claim l, in'which the marking mechanismis operated electro-magnetically.

7. Apparatus according to claim 1, comprising a timing .device for operating the marking device and the indicator means and means to drive said timing device in step with the knitting elements of said machine.

8. Apparatus for ascertaining at predetermined intervals variations in the average yrate of feed of yarn per stitch in a ilat warp knitting machine having a positively driven beam let-off mechanism and a tension bar, over which the yarn is led from -the warp beam, comprising mechanism for marking la yarn, electro-magnetic means to operate said marking mechanism, a scale mounted for longitudinal adjustment along said tension bar, guide eyes at each end of said tension bar, a lamp arranged 4.to illuminate said scale, timing mechanism Yto illuminate said 4lamp and `operate said marking mechanism simultaneously at time intervals of a predetermined number of -courses and means to drive said `timing mechanism in step with the knitting elements of the machine.

References Cited in the le of this patent UNITED STATES PATENTS 2,083,333 Lawson June 8, 1937

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