Patent GB-197665-A (GB)
Title: Improvements in circular rib knitting machines
IPC: D04B35/02
Filed: 1923-04-25
Abstract: 197,665. Scott, R. W. May 9, 1922, [Convention date]. Circular machines.-Relates to a machine for the production of articles such as stockings with partly ribbed and partly plain knitted areas by a. continuous automatic operation of two sets of needles which knit, without transferring loops, a ribbed fabric part of one circumferential segment of the article being produced before beginning to knit the ribbed fabric part of another segment. This result is attained chiefly by the provision of devices operating in a new way for maintaining upon the fabric and in respect of the instruments used a sufficient tension, without recourse to fabric take-up devices, and in provisions for severally operating different segments of the knitting and tensioning - instruments at different times. Preferably the dial needles are of the kind shown in Fig. 3 and prior to the formation of ribbed fabric they are operated to produce an eyelet-hole closing course which forms a line of demarcation between the ribbed and plain areas. Preferably the knitting of a stocking &c. is started at the toe end by forming a selvage s, Fig. 21, on bare needles and by making rounds r of plain fabric followed by a fashioned pouch t. Previous to the entry of dial needles for the, ribbed instep, courses r<5>, r<6>, Fig. 23, of tuck loops are made, the tuck loops occurring in one or other of the wales flanking that containing an initial rib loop z so that a leg of a loop r<7> always extends across the eyelet-hole which would otherwise be formed. Tucking is effected by moving the lower centre cam 9, Fig. 5, which is pivoted at 7, to the position shown in full lines, whereby the needles depressed by the cam 4 are enabled to take fresh yarn without clearing the loopsalready on their hooks. The cam 4 may be positioned so as to act on long-butted needles only, or if the latter are first taken by a cam 25, the cam 4 will act on the short and mediumbutted needles only. The instep section of partly-ribbed fabric p which may be as much less than half the circumference of the tube as is desired, is obtained without placing the whole web under undue tension, by operating the webholders in segments corresponding to and variable with the number of active dial needles, rib-knitting tension being thus maintained on the instep segment and a normal web-holder action on the sole segment. The web-holders are of two kinds, w<1>, w<2>, the web-holders w<2> being distrbuted at the flanks of the rib wales and being provided with tensioning serrations w<13> which co-operate with partitions or fins d<5>, Fig. 11 on the underside, of the dial D. The instep web holders may have longer butts than the rest. The plain web holders w<1> are operated by a fixed cam 304, Fig. 14, and adjustable cams 306, 307. The length of the web holder from the hooks w<10> to the inward faces of the butts is constant so that the inward limit of throw is the same for all, but the length from the hooks w<10> to their outer ends is less in the web holders w<2> than in the web holders w<1>, and the web holders w<2> are capable of being withdrawn outwardly, without contact with the cams for the web holders w<1>, to an abnormal extent for the purpose of engaging the points w'3 with the fabric.. The fabric is tensioned at any particular point by reinserting an abnormally withdrawn web-holder at that point. This is effected by cams such as 312 pivoted at 313 in a slot above the level of the cam 307 and acted on by an adjustable spring plunger 315 to hold an adjustable eccentric limit stop 314 on the cam 312 against the cam-cap wall. When plain fabric is being made, the cam 312 merely advances the web-holders on which it acts to their normal inward limit and provison for withdrawing this cam when not required to function is unnecessary. The tensioning effect of any of the web holders w<2> being dependent on whether it has been abnormally withdrawn before reaching the cam 312, means are provided for acting on all or some only of the web-holders w<2> to predetermine abnormal withdrawal of selected web-holders only, or of all of the series. This is effected by a pattern-controlled withdrawing cam 325 which can be placed in several positions for differential action on the butts w<17>, w<18> of the webholders w<2>, which are shown as provided with two different lengths of butts, but further differentiation may be employed. The cam 325 is attached to an arcuate segment of spring metal and is placed in the required position by the action of a lug on a pattern-controlled' thrust bar. Provision is made for adjusting the dial vertically, under control of the pattern-mechanism, and in coordination with similar movements of the cylinder. Dial cams for operating the two-part dial needles and yarn-feeding, cutting and clamping-means are also described. The cam 25, Fig. 5, the switch cam 415 and the widening picker 680 are operated in common by a single thrust rod controlled from a pattern chain. A cam 8 depresses the cylinder needles after both set of needles have knitted, during rotary knitting and is removed during the reciprocating knitting. The welt W and a concluding section of ribbed fabric W<1> may be sewed on the lines w<3> and/or w<2>.