EP0290897A2

EP0290897A2 - Device for controlling the selectors in a four-feed circular knitting machine for socks and stockings

Info

Publication number: EP0290897A2
Application number: EP88106992A
Authority: EP
Inventors: Francesco Lonati
Original assignee: Lonati SpA
Current assignee: Lonati SpA
Priority date: 1987-05-13
Filing date: 1988-05-01
Publication date: 1988-11-17
Also published as: JPS63288256A; IT8720505A0; IT1207078B; EP0290897A3

Abstract

The device comprises a ring cam (2) arranged around the needle cylinder at the lower ends of the selectors (4) and having an upper profile with rises (8) defining an ascending section (9) upstream of each machine feed and a descending section (10) downstream of each feed, according to the rotational direction of the needle cylinder with respect to the ring cam (2). Located upstream of each ascending section (9) is an extraction cam (12), which acts on the selectors (4) to extract their heels (4a) from the grooves of the needle cylinder so as to be selected by the selection levers (14). The extraction cam (12) is positioned so as to cause commencement of the exit of the heels (4a) from the relative grooves before the end of the descending section (10) of the ring cam (2) which has a recess (16) on its inner side to permit commencement of the extraction of the heels (4a).

Description

The present invention relates to a device for controlling the selectors in a four-feed circular knitting machine for socks and stockings with high operating speed.
As is known, devices for controlling the selectors in circular machines for the manufacture of socks and stockings comprise a ring cam which is placed around the needle cylinder proximate to its lower end and has an upper shaped profile intended to engage with the heels of the selectors which protrude from the grooves of the needle cylinder.
The upper profile of the ring cam has a rising section, upstream of each feed or drop of the machine, considering the direction of rotation of the needle cylinder relatively to the ring cam, and a descending section after each feed. The selectors, engaging with the rising section of the ring cam, push the needle, which is accommodated in the same groove of the needle cylinder above the selector, to take up the thread supplied to the feed being considered or to engage with its heel with needle cams which are located around the needle cylinder above the ring cam and determine the movement of the needle for the forming of the loops of knitting.
Devices for controlling the selectors furthermore comprise extraction means, which act on the selectors so as to cause the exit of their heel from the grooves of the needle cylinder to produce their engagement on the upper profile of the ring cam, and sinking means which act on the selectors to push them with their heel internally to the needle cylinder so as to avoid their engagement with the ring cam.
The extraction means, if the selector is of the "oscillating type", that is with such a configuration as to oscillate about an intermediate point of its length in a radial plane of the needle cylinder, resting with said point on the bottom of the related groove of the needle cylinder, are constituted by an extraction cam which makes contact with one of the ends of the selector to cause said oscillation. In some types of machine, the extraction cam is placed on the outer side of the needle cylinder with a profile which approaches the axis of the needle cylinder and acts on the upper end of the selectors in the direction of the axis of the needle cylinder so as to cause the exit, from the grooves, of its lower end on which there extends the heel intended to engage with the ring cam. In other types of machine the extraction cam is placed below the needle cylinder with a profile which moves away from the axis of the needle cylinder and acts on the lower end of the selectors from the inside towards the outside of the needle cylinder, moving the heels of the selectors out of the grooves of the needle cylinder.
The sinking means are, generally, constituted by selection levers which are arranged facing externally to the needle cylinder and act on the selectors in the direction of the axis of the needle cylinder. The selection levers are mutually superimposed in a direction parallel to the axis of the needle cylinder and the selectors, besides the heel intended to engage with the ring cam, have along their length other heels intended to be contacted by the selection levers. The selection levers are arranged downstream of the extraction cam and are generally controllably movable from an operative position, in which they do not interfere with the heels of the selectors, moved in extraction position by means of the extraction cam, so that the lower heel of the selectors engages with the upper profile of the ring cam, to an operative position, in which they interfere with the heels of the selectors, sinking them in the related grooves so that the lower heel of the selectors passes on the inner side of the ring cam and therefore does not engage with its upper profile.
By arranging the heels of the selectors intended to be contacted by the selection levers at mutually different levels and by acting on the selection levers, the selectors which must engage with the upper profile of the ring cam are determined, and the needles which must take up the thread at a preset feed are also therefore determined.
In current circular machines for the manufacture of socks and stockings, the extraction cam and the selection levers are arranged in sequence between the end of a descending section and the beginning of the successive rising section.
With the continuous increase of the rotation speeds of the needle cylinder relatively to the cam to continuously improve the productivity of these machines, the problems of the wear of the heels of the selectors, due to the sliding against the cams, have become increasingly relevant.
To solve these problems, the rising and descending sections of the ring cam have been modified, reducing their inclination with respect to a plane perpendicular to the axis of the needle cylinder and the maximum height of the rising sections has been reduced as much as possible.
This solution has yielded good results in circular machines with two feeds, that is to say with ring cams provided with two diametrally mutually opposite rises, which determine a rising section and a descending section at each feed, allowing an increase of the speed of rotation of the needle cylinder and therefore an increase of the productivity of these machines.
In four-feed circular machines, this solution is very difficult since the ring cam has four rises which are mutually angularly offset and an extraction cam and the selection levers must be arranged in sequence between two successive rises. In these machines a reduction of the inclination of the rising sections and of the descending sections of the ring cam entails a reduction of the space available between two successive rises of the ring cam to position thereat the extraction cam and the selection levers. In this space, to obtain the extraction of the heels of the selectors and the successive sinking of the heels of the selectors which must not operate at the feed being considered, the extraction cam would have to have a profile with relatively large angles with respect to a line tangent, in the various points of the profile, to the circumference described by the selectors upon the rotation of the needle cylinder and the same would be true for the profiles of the selection levers which must contact the selectors.
A profile of this type would prevent the achievement of high speeds of rotation of the needle cylinder due to problems of wear of the selectors and would therefore render useless the reduction of the inclination of the rising and descending sections performed on the ring cam.
The aim of the present invention is to solve the above described technical problems by providing a device for controlling the selectors in a four-feed circular knitting machine for socks and stockings which allows the achievement of high operating speeds and which therefore allows to increase the productivity of the machine.
Within this aim, an object of the invention is to provide a device simple in execution, which does not entail problems of arrangement for the extraction cams and for the selection levers which act on the selectors.
This aim, as well as this and other objects which will become apparent hereinafter, are achieved by a device for controlling the selectors in a four-feed circular knitting machine for socks and stockings, comprising: a ring cam placed around the needle cylinder at the level of the lower end of the selectors accommodated in the grooves of the needle cylinder and having an upper profile with rises defining a rising section upstream of each feed of the machine and a descending section downstream of each feed of the machine, according to the direction of rotation of the needle cylinder relatively to said ring cam, said selectors being movable in planes radial to the needle cylinder from a sunk position, in which a heel thereof, located proximate to their lower end, is sunk in the related groove of the needle cylinder and passes on the inner side of the rises of said ring cam, to an extraction position, in which said heel protrudes from the related groove of the needle cylinder to engage with said upper profile of said ring cam, and an extraction cam placed upstream of said rising section and rigidly associated with said ring cam, said extraction cam having a profile with a portion extending towards or away from the axis of the needle cylinder and engageable with said selectors for their passage from said sunk position to said extraction position, selection means being provided arranged between said extraction cam and said rising section and engageable with at least part of said selectors for their passage from said extraction position to said sunk position, characterized in that the beginning of said portion of the profile of said extraction cam is located upstream of the final part of said descending section of the rise of said ring cam and in that the inner side of said rise has, at said portion of the profile of the extraction cam, a recess at least at the level of the heel of the selectors engaged with said extraction cam to allow the beginning of the passage of the selectors in sunk position from said sunk position to said extraction position before the end of said descending section.
Further characteristics and advantages of the invention will become apparent from the description of a preferred but not exclusive embodiment of the device according to the invention, illustrated only by way of non-limitative example in the accompanying drawings, wherein:

figure 1 is a top plan view of the ring cam with two extraction cams and with part of the needle cylinder shown in phantom lines;
figure 2 is an enlarged view of a detail of figure 1, with some selectors illustrated schematically in cross section along a plane perpendicular to the needle cylinder and with the selection means indicated;
figure 3 is a perspective view of a portion of the ring cam with some selectors engaged therewith;
figure 4 is a sectional view of figure 2 taken along the axis IV-IV;
figure 5 is a sectional view of figure 2 taken along the axis V-V;
figure 6 is a sectional view of figure 2 taken along the axis VI-VI; and
figure 7 is a sectional view of figure 2 taken along the axis VII-VII.

With reference to the above described figures, the device according to the invention, generally indicated by the reference numeral 1, comprises a ring cam 2 which is fixed to the supporting structure of a circular knitting machine for socks and sockings and is placed around the needle cylinder 3 at the level of the lower end of the selectors 4, that is proximate to the lower end of said needle cylinder 3.
More particularly, the ring cam 2 has a substantially planar portion 5 which extends perpendicular to the axis 6 of the needle cylinder and which is located below the needle cylinder and a cylindrical portion 7 which extends starting from this planar portion 5 and extends around the needle cylinder.
The cylindrical portion 7 has an upper profile with four rises 8 which define a rising section 9 upstream of each feed of the machine and a descending section 10 downstream of each feed, considering the direction of rotation of the needle cylinder 3 relatively to the ring cam 2.
The selectors 4 are slideably accommodated internally to the grooves 11 of the needle cylinder 3 which extend on the lateral surface of the needle cylinder parallel to the axis 6. Furthermore, the selectors 4 are of the "oscillating" type, that is they have such a configuration as to be able to oscillate about an intermediate point of their length in a radial plane of the needle cylinder, resting with said point on the bottom of the related groove. By means of this oscillation each selector can be moved from a sunk position, in which its lower heel 4a is sunk in the related groove and passes on the inner side of the ring cam, to an extraction position, in which their lower heel 4a protrudes from the related groove to engage with the upper profile of the ring cam.
To cause the passage of the selector from the sunk position to the extraction position, an extraction cam 12 is provided which is placed upstream of at least one rising section 9 of the ring cam and has a profile 13 with at least one portion which extends away from the axis 6 of the needle cylinder 3. Said extraction cam 12 is fixed to the planar portion 5 of the ring cam and is arranged proximate to the lower end of the needle cylinder. The portion of the profile 13 which moves progressively away from the axis 6 of the needle cylinder 3 protrudes from the bottom of the grooves 11 of the needle cylinder so as to act from the inside towards the outside on the lower end of the selectors which are in a sunk position.
Obviously the selection cam may also be arranged on the outer side of the needle cylinder 3 at the level of the upper end of the selectors 4 and have a profile which gradually approaches the axis 6 of the needle cylinder and which acts on the upper end of the selectors from the outside towards the inside so as to cause the same oscillation of the selectors.
The device according to the invention furthermore comprises selection means which are constituted by a plurality of selection levers 14 mutually superimposed parallel to the axis 6 of the needle cylinder 3. The selection levers 14 are arranged facing with one of their ends 14a laterally to the needle cylinder and are controllably movable, in a known manner, for example towards or away from the axis 6 of the needle cylinder, to interfere or not interfere with other heels 15 of the selectors which are arranged above the lower heel 4a. The selection levers 14 are located between the extraction cam 12 and the rising section of the ring cam and the interference of one of these levers 14 with one of the heels 15 causes the passage of the related selector from the extraction position to the sunk position, while the non-interference allows the selectors to remain in the extraction position and therefore to engage with the rising section 9.
According to the invention, the beginning of the portion of the profile 13 of the extraction cam which moves progressively away from the axis 6 of the needle cylinder is placed ahead of the final part of the descending section 10 of the ring cam and the inner side of the ring cam has a recess 16 located at least at the level of the lower heel 4a of the selectors engaged with the extraction cam so as to allow the beginning of the passage of the selectors 4 from the sunk position to the extraction position before the end of the descending section 10 instead of after the end of the descending section as occurred in known devices.
Advantageously, the recess 16, which can be obtained by means of a milling which affects the entire height of the rise 8 starting from the level of the lower heels 4a in sunk position, connects to the remaining part of the inner side of the ring cam proximate to the selection levers 14.
In this manner the portion of the profile 13 of the extraction cam 12 which extends away from the axis of the needle cylinder may extend for a center angle α, referred to the axis 6 of the needle cylinder 3, which is comprised between 50° and 60° and can therefore have lines, tangent in the various points, which have a small inclination with respect to the lines tangent to the circumference defined by the selectors in the rotary motion of the needle cylinder; in this manner the angle of impact of the extraction cam 12 with the selectors 4 is very small and therefore it is possible to achieve high speeds of rotation of the needle cylinder.
Furthermore, since the lower heels 4a of the selectors 4 are extracted from the grooves proximate to the end of the descending section 10 of the rise 8, it is possible to reduce the inclination of the rising and descending sections of the rise 8 though keeping considerable space available for the selection levers 14 which can have a greater width with respect to known selection levers and therefore an inclination of their end directed towards the needle cylinder very small with respect to a line tangent to the circumference described by the selectors in the rotary motion of the needle cylinder, allowing also in this case high rotation speeds.
For the sake of descriptive completeness, it should be noted that on the upper profile of the ring cam, towards the inner side in the region of connection of the recess 16, a depression 18 is provided, due to the milling operation for the obtainment of the recess 16, which is not contacted by the heels 4a of the selectors 4 since it is placed at a lower level.
The operation of the device according to the invention is as follows.
The selectors 4 which are in extraction position engage with their lower heel 4a with the upper profile of the ring cam 2 and follow in a known manner the rising sections 9 and the descending sections 10 of the rise 8 until they are moved to the sunk position by one of the selection levers 14.
The selectors 4 which are in sunk position rest, in a known manner, on the planar portion 5 with their lower end. When these selectors 4 engage with the profile of the extraction cam 12, they are pushed to exit with their lower heel 4a from the related groove 11 of the needle cylinder 3. The beginning of the exit occurs, in the device according to the invention, before the end of the descending section 10 of the rise 8 and is completed at the end of this descending section. At this point both the selectors which were in the sunk position and those which already were in the extraction position are selected by the selection levers 14 which, according to the knitting requirements, keep preset selectors in extraction position and move the others to the sunk position.
In practice it has been observed that the device according to the invention fully achieves the intended aim since, by virtue of the modifications of the profile of the extraction cam, of the ring cam and of the selection levers, made possible by virtue of the recess on the inner side of the rises of the ring cam, allows the achievement of much high operating speeds in a four-feed circular knitting machine for socks and stockings with respect to known machines and therefore considerably increases the productivity of this type of machine.
The device thus conceived is susceptible to numerous modifications and variations, all of which are within the scope of the inventive concept; moreover, all the details may be replaced with technically equivalent elements.
In practice, the materials employed, as well as the shapes and dimensions, may be any according to the requirements and the state of the art.
Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly, such reference signs do not have any limiting effect on the scope of each element identified by way of example by such reference signs.

Claims

1. Device for controlling the selectors in a four-feed circular knitting machine for socks and stockings, comprising: a ring cam (2) placed around the needle cylinder (3) at the level of the lower end of the selectors (4) accommodated in the grooves (11) of the needle cylinder (3) and having an upper profile with rises (8) defining a rising section (9) upstream of each feed of the machine and a descending section (10) downstream of each feed of the machine, according to the direction of rotation of the needle cylinder (3) relatively to said ring cam (2), said selectors (4) being movable in planes radial to the needle cylinder (3) from a sunk position, in which a heel (4a) thereof, located proximate to their lower end, is sunk in the related groove (11) of the needle cylinder (3) and passes on the inner side of the rises (8) of said ring cam (2), to an extraction position, in which said heel (4a) protrudes from the related groove (11) of the needle cylinder (3) to engage with said upper profile of said ring cam (2), and an extraction cam (12) placed upstream of said rising section (9) and rigidly associated with said ring cam (2), said extraction cam (12) having a profile with a portion extending towards or away from the axis (6) of the needle cylinder (3) and engageable with said selectors (4) for their passage from said sunk position to said extraction position, selection means (14) being provided arranged between said extraction cam (12) and said rising section (9) and engageable with at least part of said selectors (4) for their passage from said extraction position to said sunk position, characterized in that the beginning of said portion of the profile of said extraction cam (12) is located upstream of the final part of said descending section (10) of the rise (8) of said ring cam (2) and in that the inner side of said rise (8) has, at said portion of the profile of said extraction cam (12), a recess (16) at least at the level of the heel (4a) of the selectors (4) engaged with said extraction cam (12) to allow the beginning of the passage of the selectors (4) in sunk position from said sunk position to said extraction position before the end of said descending portion (10).

2. Device, according to claim 1, characterized in that said recess (16) is radiused to the remaining part of the inner side of said ring cam (2) proximate to the region affected by said selection levers (14).

3. Device, according to claim 1, characterized in that said recess (16) substantially affects the entire height of said rise (8) starting from the level of the heels (4a) of the selectors (4) in said sunk position.

4. Device, according to claim 1, characterized in that said extraction cam (12) is rigidly associated with said ring cam (2) and is located proximate to the lower end of the needle cylinder (3), said portion of the profile of said extraction cam (12) extending away from the axis (6) of the needle cylinder (3) and protruding from the bottom of the grooves (11) of the needle cylinder (3) in the direction of the inner side of said ring cam (2), said extraction cam (12) acting from the inside towards the outside of the needle cylinder (3) on the lower end of said selectors (4) in sunk position.

5. Device, according to one or more of the preceding claims, characterized in that said portion of the profile of said extraction cam (12) extends for a center angle (α), referred to the axis (6) of the needle cylinder (3), substantially comprised between 50° and 60°.