GB2177125A - Improved knocking-over sinker for circular knitting machines - Google Patents

Abstract

An improved knocking-over sinker for circular knitting machines is proposed, with a head provided with a hook and with at least one knocking-over plane, and with a drive butt, as well as with at least one notch 23 provided in its lower edge in correspondence of the sinker stem, said sinker being characterized in that it is provided with at least one further notch 24, provided in such a position as to confer a certain elasticity to the sinker in its longitudinal direction. The further notch may be in the upper edge of the stem as shown and another notch may also be formed in the underside of the neck joining the head 11 to the stem 14. The sinker may be-braked in its slot by bowing it laterally or bending it in a Z shape or by having slightly offset guiding slots in the guide ring and crown. <IMAGE>

Description

SPECIFICATION Improved knocking-over sinker for circular knitting machines The present invention relates to an improved knocking-over sinker for circular knitting machines.

It is known that the knocking-over sinkers of circular knitting machines, sliding inside radial slots ofthe sinkers ring and of sinkers crown, undergo a considerable wear, due to friction, ofthe side walls and of the lower edge ofthe same sinkers in contact with the surfaces ofthe slots.

Furthermore, they undergo considerable stresses due to the continuous reversing of their running direction under the action ofthe drive cams.

These problems are heavier in caseof machines operating at high rate, and with rather highly inclined cams because of lesser peripheral room available for the thread feeds.

In order to reduce the friction and consequently the wear, in the prior art knocking-over sinkers have already been proposed, which are provided on their lower edge with one or more lightening notches. Such notches, by reducing the surface of the sidewalls, reduce also the amplitude ofthesurface actually in friction contact with the bottom and with the side walls ofthe slots. They moreover lighten the sinkers, thus favouring their reciprocating motion.

The notches provided in the stem of the sinkers between the drive butt and the largerfront head, having the hook and the knocking-over plane, allow also the stem to be made slightly thinner and hence provided with a certain elasticity, advatangeousto the purpose of reducing the impact strengthens arising during the reciprocating motion ofthe sinkers.

The notches as mentioned show howeverthe disadvantage of collecting dirt, the advantages ofthe lower friction going thus lost with time, because such dirt accumulation causes a braking resistance against the sinker motion.

Thus, cleaning the sinkers notches from time to time is necessary, which requiresthestopping ofthe production, and is not easy, because the same sinkers must be extracted, one by one, from their related slots.

Furthermore, it has been possible to observe that, notwithstanding the presence ofthese notches inthe stem of the sinkers, the same stem undergoes strong vibrations and impacts, which still cause a consider ablewear. On one hand,thesevibrationsaredueto the factthatthe head ofthe sinker, in which the most of the mass ofall the sinker is concentrated, is connected to the stem by a substantially stiff connecting section, so that the accelerations and decelerationsthe head massundergoes during the reciprocating motion are directly transmitted to the sinker stem.On the other hand, it has been observed that strong vibrations and rebounds of the sinkers are also caused by the accelerations and decelerationsappliedtothesinkers by the drive cams during their reciprocating motion insidethe radial slots ofthe sinkers ring and ofthe sinkers crown, inside which slots the sinkers are by nature housed with minimum friction.

The purpose ofthe present invention is to provide an improved knocking-over sinker, of the type provided with notches in its lower edge, but so shaped as to reduce the wear and make it more resistantto stresses, soto increase its life.

Another purpose isto provide a sinker which does not show problems of dirt deposition and which does not require frequent cleaning operations, and the stem ofwhich undergoes lower vibrations during its reciprocating notion inside its related slot in the sinkersring,thus reducing theweardueto such vibrations.

In order to achieve these purposes, according to the invention a knocking-over sinker for circular knitting machines is proposed, with a head provided with a hook and at least one knocking-over plane, and with a drive butt, as well as with at least one notch in its lower edge in correspondence of the sinker stem, said sinker being characterized in that it is provided with at least one further notch, provided in such a position as to confer acertain elasticity to the sinker in its longitudin- al direction.

Advantageously, the sinker can be provided with two notches spaced from each other, on its lower edge, and with a notch, interposed between the said notches, on the upper edge ofthe sinker, such notches conferring to the sinkerstem a meander configuration.

The sinker can also be divided with a notch in its connecting section connecting the head to the stem, said notch beginning from the front edge of said connecting section approximately atthe level of the bottom of the groove formed in the sinker head by the hook and the knocking-over plane, and being inclined backwards relatively to the axis ofthe stem.

Thanks to the presence of these notches, not only a lightening of the sinker and a reduction of its mass are obtained, but above all a certain long rtudi nal flexibility is conferred to the sinker, so that the dynamic forces are damped, with the result that the sinker undergoes lower vibrations during its reciprocating motion.

To the purpose of reducing alsothe vibrations caused bythe strong accelerations and decelerations ofthesinker during its motion underthe action of the drive cams, it is furthermore proposed thatthe sinkers be submitted to a limited braking action insidethe related slots of the sinkers ring and slots ofthe sinker crown which house them.

Such a braking action can be achieved by means of a limited cambering or bending to a Z-shape of the sinker stem, or by slightly staggering the slots ofthe sinkers ring relatively to the corresponding slots ofthe sinkers crown. Surprisingly, it has been possibleto observethat,thanks to this slight braking action to which the sinker stem is submitted during its reciprocating motion, the vibrations of the stem are decreased, and the wear of its edges is consequently reduced.

Advantageously,the longitudinal extensionofthe notches provided in the stem can be shorterthatthe sinker stroke, so that inside the notch dirt is no longer accumulating, because the reciprocating motion of the sinker, the stroke ofwhich is longer than the length ofthe mouth ofthe notches, does not leave free room forthe accumulation of dirt inside the sinker notches.

As a consequence, a sinker having the shape according to the invention, shows a lower wear panda longer life,furthermore it being not any longer necessary to carry out operations ofcleaning ofthe slots and ofthe sinkers notches, thanks to the fact that in those areas dirt is no longer accumulating.

Further details and advantages of the invention shall result more clearfrom the following disclosure, referred to two preferred forms of practical embodi ment of a sinker according to the invention, as illustrated in the attached drawings, wherein: Fig 1 is an elevation view on enlarged scaleof a knocking-over sinker according to the invention, Fig. 2 shows on a lowerscalethesinkerofFig. on a circular knitting machine, of which only a small portion of radial section is visible, Fig. 3 is an elevation view of a sinkerwith two hooks and two knocking-over planes according to the invention, Fig. 4 shows a plan view ofthe sinker of Fig.3, and Fig. 5 shows the same sinker, on a smallerscale, on a circular knitting machine, of which only a small portion ofthe radial section is visible.

Referring first to Figs. 1 and 2, a sinker 10 has, in a known way, a front head 11 with a hook 12 and knocking-over plane 13, anda stem 14 with drive 15 at its rea rend.

The sinker 10 is slidingly housed, in a knowrrway, with its stem 14 inside a respective radial slot 16 of the sinkers ring 17, affixed to the cylinder 18 of machine needles. The head 11 is sliding inside a respective radial slot 19 of the sinkers crown 20, affixed to the cylinder 18. The reciprocating motion ofthe various sinkers 10 is obtained in a known way bythe action of drive cams 21, acting on the butts 15 and on the flanks 26 ofthe sinkers 10, and supported by a structure having a relative motion.as referred to the ring 17.

Inorderto reduce the sliding friction, in the lower edge 14a ofthe stem l49fthe sinker 10, when the sinker is manufactured by shearing from a steel sheet in a per se known way, at least a notch 23 is provided.

Preferably,two of such notches 23, of preferably trapezoidal shape are provided, spaced from each other-lengthwise to the sinker 10.

The longitudinal extension the mouth of thenotch or of the notches 23is shorterthan the stroke ofthe sinker 10, which can be deducted from thetwo positions ofthe sinker as shown in Fig. 2, respectively by continuous line and, partly,by broken line.

In this way, the accumulation of dirt, such as pieces of thread, lint, and other matter, mixedwith lubricat- ing oil, is prevented, because the stroke ofthe sinker, by resulting longerthatthe mouth ofthe notches 23, does not allow the foreign matter mentioned to find free room to stably settle inside the notches 23.

Thesinker 10 is also preferably provided with an notch 24 in its upper edge, interposed, in a lenghtwise direction along the sinker 10, betweenthe lower notches23,andittoo having a mouth shorter in length than the stroke of the sinker 10. The upper notch 24 has preferably it too a trapezoidal shape, and confers to the stem ofthe sinker 10, together with the notches 23, a meander configuration, which considerably in creases the elasticity ofthe sinker in the longitudinal direction, and moreover makes it much lighter, with consequent better motion performance thereof.

The upper notch 24 allows also an easier penetration of the lubricating oil into the areas defined between the side walls ofthe sinker 10, and the side wallsofthe respective slot 16,thus improvingthe lubrication ofthe surfaces under mutual sliding contact and thus increasing thefluency ofthe sinker As it can be seen in particular at Fig. 1,the depth of the notches 23,24 is slightly lower than half height of the stem 14 ofthe sinker 10.

Theloweredgeofthehead 11 ofthesinkerl0is preferably extendedto an upperelevation thanthe lower edge of the stem 14 of the sinker 10.

As it results from Fig. 2, the slots 19 of the sinkers crown 20 are advantageously defined between protru sions 25 ofthe crown 20, having a radial size shorter than the stroke ofthe sinkers 10. In this way, the friction isreduGed also in correspondence of the head 11 of the sinkers, and deposits of dirt are not even formed in thiszone, tofutl advantage of the fitlency of the sinkers 10.

Advantageously, the upper notch 24 can be used to the purpose of checkingthe possible butt breakage, by inserting a check pin through the structure 22 in a suitable position to verify the presence or less of the notch in this position.

Of course, also two upper notches 24 canbe provided, associated, e.g., to three lower notches 23, or other combinabons of upper and lower notches can be provided.

The knocking-over sinker 110 shown in Figs. 3-5 comprises, in aknown way, a head 111, a stem 112 and a head-stemconnecting section 113. The headIl 1 has two hooks 114,115 and two knocking-over planes 116, 117tthe hoole 114 and the plane 116forming a first groove118,andthehook115andtheplane117 forming a second groove 119. The stem 112 ofthe sinker 110 has a drive butt 120. The connecting section 1 T3formswith the stem 112 a flank 121.

In the lower edge 122 of the stem 112two notches 1 23 spaced relativelyto each other are provided, and in the upper edge 124 of the stem 112 1 further notch 125 is provided in an intermediate position between thefirsttwo notches, so as to confer to the stem 11 a meander configuration, with the advantages which have been already evidenced for the sinker of Figs. 1 and2.

The connecting section 1-13 between the head 111 arrd th e stem 112 ofthe sinker 110 is providedwitha further notch 126, which begins from the front edge 127 of said connecting section 113 approximately at the level ofthe bottom ofthe grooves118,119 and which is inclined downwards relatively to the axis of the stem 11 2.The depth of the notch 126 is such that the residual width ofthe connection section 11 3may confer a sufficiently high mechanical strength to said connecting section.

Thanks to the presence of the notch 126 inthe connecting section 113, this letterobtainsa certain flexibility, so that during the reciprocating motion of the sinker the dynamic forces of the head 111 are transmitted in a dampedfashiontothestem 112, and the vibrations ofthe same are hence considerably reduced. Moreover, this notch 126 causes a further lightening of the sinker 110, besides the reduction in weight obtained by means ofthe notches 123 and 125, by reducing the mass thereof.

The profile of the notch 126 is determined substan tially by the requirement that the head 111 ofthe sinkerll0mustdrivethelatch oftheneedleofthe machine during its opening and closing motion, and that it must be avoided that this latch may collide againstthe edge of the notch during such a movement.

As it can be seen at Fig. 4, the sinker 110 has a certain bending with a camber fwhich is a function ofthe rotary speed ofthe machine, and ofthe mass ofthe sinker. In this way, the reciprocating motion of the sinker inside the respective slots ofthe sinkers ring and ofthe sinkers crown underthe action exerted by the drive cams results slightly braked, and consequently the vibrations of the sinker stem, caused by the very sharp accelerations and decelerationsit undergoes, are reduced, andthe occurring of the wear due to such vibrations is prevented.

Asimilar braking action could be obtained also by bending the sinker stem to a Z-shape, or bystaggering the slots ofthe sinkers ring relatively to those ofthe sinkers crown.

Fig. 5 shows the sinker 110 mounted on the machine. In a known way, the sinker 110 isslidingly housed with its stem 112 insidea respective slot 127 of the sinkers ring 128, affixed to the cylinder 129 bearing the machine needles. The head 111 is sliding inside a respective slot 130 defined between protrusions 131 of the sinkers crown 132, affixed to the cylinder 129.

The radial motion ofthevarioussinkersl 10 is obtained in a known way under the action applied by the drive cams 133, acting on the butts 120 and on the flanks 121 ofthe sinkers 110, and supported buy a structure 134 in relative motion as referred to the ring 128.

Fromtheforegoing disclosure is results clear how a sinker according to the invention has, summarizing, a longer life than the equivalent sinkers ofthe prior art.

The notch between the head and the stern of the sinker 110 hasbeen ilustrated with reference to a sinker with two hooks andtwo knocking-over planes, but it is clear that it can be applied as well to sinkers with one hood and one knocking-over plane only, af the type as illustrated in Fig. and 2.

Claims (15)

1. Improved knocking-over sin kerfor circular knit- ting machines, with ahead provided with a hook and withat least one knocking-over plane, and with a drive butt, as well aswith at least a notch in its lower edge in correspondence ofthe sinker stem, said sinker being characterized in that it is provided with at least one further notch, provided in such a position as to confer a certain elasticity to the sinker in its longitudinal direction.

2. Sinker according to claim 1, characterized inthat said at least one further notch is provided in the upper edge of the sinker stem.

3. Sinker according to claim 1, characterized in that it is provided with two notches, spaced from each other, in the lower edge ofthe sinker stem, and with a notch in the upper edge, interposed between the said two lower notches, said notches conferring to the stem a meander shape.

4. Sinker according to one of preceding claims, characterized in that said notches have a depth slightly lowerthan half of the height of the sinker stem.

5. Sinker according to one of preceding claims, characterized in that said notches have a substantially trapezoidal shape.

6. Sinkeraccording to one of preceding claims, characterized inthatthe longitudinal extension ofthe mouth of said notches is shorterthanthe length of the sinker stroke.

7. Sinker according to claim 1 characterized in that said at least further notch is positioned between the head and the stem ofthe sinker, and beginsfromthe frontedgeoftheconnectingsectionwhich connects the head andthe stem of the sinker, approximately at the level ofthe bottom of the slot formed in the sinker head bythe hook and the knocking-over plane, said furthernotch being inclined backwards relatively to the axis of the sinker stem.

8. . Sinker according to one of preceding claims, characterized in that means are provided for braking the sliding ofthe same sinker inside the radial slots of the sinkers ring and ofthe sinkers crown.

9. Sinker according to claim 8, characterized in that said-braking means are constituted by a cambering of the sinker.

10. Sinker according to claim 8, characterized in that saidbraking means are constituted by a bending ofthesinkerbodyto aZ-shape.

11. Sinker according to claim 8, characterized in thatsaid braking means are constituted by a staggering of the radial slot of the sinkers ring relatively to the corresponding slot ofthe sinkers crown, which respectivelyhousethe stem and the head of the sinker

12. Sinkeraccording to one of preceding claims, characterized inthatthe lower edge in correspondenee of the sinker head is positioned to a ttigher elevationthan the lower edge in correspondence of thasinkerstem.

13. Sinkeraccordingto one of preceding claims, characterized in that the head ofthe sinker is suitable to slide inside a respective slot of the sinkers crown, defined between protrusions having a radial dimension shorterthanthe sinkerstroke length.

14. A knocking over sinker for a circular knitting machine substantially as herein before described with reference to and as illustrated in the accompanying drawings.

15. Knitting machineincludingasinkeraccord ingto any preceding claim.