Patent Application
20240352635
A large variety of knitting systems and loop-forming needles has been known for many years. In knitting machines, it is customary to use needle-guiding means comprising grooves in which loop-forming needles are guided and can be moved translatorially in the longitudinal direction of the grooves, which point in the working direction. In circular knitting machines, these needle-guiding means are typically knitting cylinders whose basic shape is cylindrical and whose cylinder axis points in the working direction. The grooves are then arranged on a cylindrical base surface of the knitting cylinder. In flat knitting machines, these needle-guiding means are typically needle beds having an essentially rectangular shape. The grooves in such needle beds are arranged on a planar base surface of the needle bed, said planar base surface pointing in an elevational direction. The elevational direction is at right angles to the working direction. Needle beds for flat knitting machines and knitting cylinders for circular knitting machines both constitute needle-guiding means. At their front end, the needles mostly have a loop-forming element—in most cases shaped as a hook—with which loops can be formed during the knitting process. The needle-guiding means has a plurality of grooves arranged side by side at a defined distance apart, said distance corresponding to the pitch, along a peripheral direction of the needle-guiding means. The peripheral direction in this context is at right angles to the working direction and to the elevational direction and extends along the base area of the needle-guiding means. In the case of a knitting cylinder, therefore, the peripheral direction always runs tangentially along the cylindrical base area of the knitting cylinder. Each needle comprises at least one drive butt via which it can be moved translatorially. For this purpose, the drive butts of the needles engage with a cam which has a curved profile in the peripheral direction of the needle-guiding means. Relative motion in peripheral direction between cam and needle-guiding means initiates translatory motion in working direction in the drive butts of the needles.
WO2012055591A1 shows a knitting machine having needles which, in a rearward shank portion, are guided in slide or guiding grooves and, in a forward working portion, are guided in loop-forming or verge grooves. The guiding grooves and verge grooves are arranged on a knitting cylinder, wherein associated guiding and verge grooves are mutually offset in the peripheral direction of the knitting cylinder. Loop-forming needles, each of which is guided in its own guiding groove and its own verge groove, are able to compensate this offset by means of elastic bending. In this way, an originally straight needle can be guided both in a guiding groove and in a verge groove which is offset, in peripheral direction, relative to said guiding groove. However, known loop-forming needles with high needle pitches—i.e. needles with a large shank width—are not designed for such loads. They therefore have a shorter service life and consume more power than is usual for loop-forming needles.
Based on the prior art, the aim of the invention is therefore to devise a knitting system and a needle which show greater stability, are less prone to wear and require less power than previously known knitting systems and needles.
The objective is achieved by means of the claims 1 and 11. A knitting system features a needle-guiding means with a base surface pointing in an elevational direction, as well as at least one guiding groove which is arranged on the base surface of the needle-guiding means and extends substantially in working direction, wherein the working direction is at right angles to the elevational direction. At least one verge groove is arranged on the base surface of the needle-guiding means and is offset relative to the at least one guiding groove in peripheral direction and in working direction, said peripheral direction extending on the base surface of the needle-guiding means at right angles to the working direction and the elevational direction. At least one needle has, at its first end, which points in the positive working direction, a working portion incorporating a loop-forming element, and, at its second end, which points in the negative working direction, a shank portion, wherein, between said shank portion and said working portion, a bending portion is interposed in which the at least one needle has a bend with directional components in peripheral direction and in working direction. The working portion of the at least one needle is accommodated in a loop-forming groove and the shank portion of the at least one needle is accommodated in a guiding groove. It is advantageous if, in the bending portion of the at least one needle, at least one recess is arranged at at least one of its lateral surfaces pointing in peripheral or in elevational direction and/or the bending portion of the at least one needle is plastically formed in such a manner as to effect, in peripheral direction, a plastic shank offset between the working portion and the shank portion. The lateral surfaces here are the surfaces bounding the needle in peripheral direction and elevational direction. It is particularly advantageous if, in the bending portion of the at least one needle, at least two recesses are defined on at least one of its lateral surfaces pointing in peripheral direction or in elevational direction. For example, a plurality of recesses may be defined on the same lateral surface or one recess in each case on two lateral surfaces. It is just as possible for at least one recess to be defined on a lateral surface pointing in peripheral direction and at least one recess on a lateral surface pointing in elevational direction. The offset in peripheral direction, which exists between the verge groove and the guiding groove, is compensated by the needle by means of an elastic or plastic bend in its bending portion. Only in this way is it possible for the shank portion of a needle to be accommodated in a guiding groove and its working portion in a verge groove which is offset in peripheral direction relative to the guiding groove. The shank and working portions of a needle which has a recess in the bending portion can be configured with greater stability without necessitating higher bending forces for the bend in the bending portion. The needle height, for example, can be increased. On account of a prying effect, increased needle height in the shank portion enables driving forces, in particular, which are transmitted from the cam to the needle's drive butt, to be supported better in the guiding channel with lower supporting forces. Consequently, a needle of this kind not only shows greater stability but is also less prone to wear and requires less power. The guiding and verge grooves may be manufactured in different ways: for example, they may be introduced into the needle-guiding means by means of a machining method. It is also possible for the grooves—both guiding grooves and verge grooves—to be formed by walls inserted in the base surface, which project above the base surface and form grooves with neighbouring walls. The knitting system according to the invention may comprise guiding and verge grooves made by all production and construction methods previously known for this purpose. For the recess of the at least one needle, the following applies: it is advantageous to produce the recess by means of machining processes, such as grinding or milling, and/or forming processes, such as rolling, and/or parting processes, such as punching. A ground recess is particularly advantageous. Recesses produced by machining and forming methods, in particular ground recesses, can be made inexpensively and accurately. In the area of recesses, the needle's cross section is less than in surrounding areas.
Further advantages are obtained if at least one recess at a lateral surface pointing in peripheral direction has a recess depth of 10 μm to 100 μm, advantageously 30 μm to 70 μm, and/or at least one recess at a lateral surface pointing in elevational direction has a recess depth of 150 μm to 500 μm, advantageously 200 μm to 400 μm. The recess depth here is the depth to which the recess surface is sunk below the lateral surface on which the recess is defined. Accordingly, in the case of a recess on a lateral surface pointing in peripheral direction, the recess surface also points in peripheral direction, and in the case of a recess on a lateral surface pointing in elevational direction, the recess surface also points in the elevational direction. If the recess were too deep, the needle would be weakened too much in the bending portion. This would then prevent exploitation of the advantages resulting, particularly in the shank portion, from the improved support of the needle on on account of the driving forces. If, on the other hand, the recess is not deep enough, the stability of the needle in the shank portion and working portion cannot be sufficiently improved. The above-mentioned selection ranges have proved advantageous with customary needle widths of less than 0.6 mm and needle heights of less than 4 mm.
It is advantageous if the at least one recess extends, in an elevational direction which is at right angles to the working direction and the peripheral direction, over the entire needle height. A recess which extends over the entire needle height requires less complex production methods than a recess which only extends over part of the needle height. However, a recess which extends over a maximum of 90%, preferably a maximum of 80%, of the needle height is also advantageous. The bending properties of the needle can also be optimized with a recess which does not extend over the entire needle height.
It is advantageous if the at least one recess extends, in working direction, over the entire bending portion of the needle. The length of the bending portion in working direction is therefore the same as a recess length corresponding to the extension of the recess in working direction. Additional advantages are obtained if the at least one recess extends in working direction over a maximum of 80%, preferably a maximum of 50%, of the bending portion. The recess length is thus less than the length of the bending portion in working direction. In particular, the needle may also be bent at places where there is no recess. It is particularly advantageous if at least two recesses are defined on one of the needle's lateral surfaces pointing in the peripheral direction. A plurality of recesses is thus defined on the same lateral surface. It is also possible to define more than one recess in each case on a plurality of lateral surfaces. It is advantageous if the at least two recesses provided on a lateral surface are spaced from one another in working direction and/or elevational direction.
Of particular advantage is a knitting system in the case of which the at least one recess of the at least one needle, in an extended state and/or a retracted state, is completely outside the at least one verge groove and/or the at least one guiding groove. As already mentioned, the needles are translatorially movable in working direction in the verge and guiding grooves. The extended state of the needle in this case is the state in which the needle's loop-forming element projects furthest out of the verge groove in working direction. The retracted state of the needle is the state in which the loop-forming element projects the shortest distance out of the verge groove in working direction. Also in the extended and the retracted state, the working portion is accommodated in a verge groove and the shank portion in a guiding groove. The knitting system is configured in such a manner that a recess in the needle's bending portion does not engage either a verge groove or a guiding groove when the needle is in the extended or retracted state, thereby preventing the introduction of large amounts of dirt produced during knitting—for example fluff, abraded metal or dust—through the recess into the guiding and verge grooves. This reduces friction and is advantageous with regard to wear on the knitting system and to its power consumption.
It is furthermore advantageous if the at least one recess of the at least one needle in the retracted state is outside of the at least one guiding groove to an extent of at least 60%, preferably, however, 80% of the recess length, which corresponds to the extension of the recess in working direction, and/or if the at least one recess of the at least one needle in the extended state is outside of the at least one verge groove to an extent of at least 60%, preferably, however, 80% of the recess length. Depending on the requirements made on the knitting system and the knit goods to be produced, it may not be possible to configure the knitting system in such a way that the recess is also completely outside of the guiding groove in the retracted state and/or outside of the verge groove in the extended state. It is advantageous in this case if the recess is outside of the guiding and/or verge groove to an extent of at least 60% of the recess length, which corresponds to the extension of the recess in working direction. The amount of dirt introduced into the guiding groove and/or verge groove will not be enough in this case to prevent the described advantages of the knitting system according to the invention from being exploited.
Also to advantage is a knitting system comprising at least one drive butt, which is arranged in the shank portion of the at least one needle and projects above the surrounding shank portion in elevational direction, and a bending-portion clearance, which corresponds to the distance in working direction between the at least one drive butt and the bending portion, wherein the bending-portion clearance is at least as large as an extension length corresponding to the path of the needle in working direction between the retracted and extended states. In this way, the drive-butt area of the needle is always accommodated in a guiding groove and the driving forces acting on the drive butt are better supported. The area of the needle which borders directly on the drive butt is nevertheless exposed to high mechanical loads. The needle's bending portion is likewise an area which has to withstand high mechanical loads on account of the constant-during knitting also alternating-elastic bending. To avoid overlapping of these high loads in a transition area, it is accordingly advantageous if the drive butt is spaced sufficiently far away from the bending portion.
Further advantages are obtained if the working portion and the shank portion of the at least one needle extend substantially parallel to one another in working direction. If the working portion and the guiding portion run parallel to one another in working direction and the needle moves translatorially, the loop-forming element performs linear motion in working direction. If there were angular offset between the shank portion and the drive portion, this could lead to additional movement of the loop-forming element in peripheral direction. This would lead to knitting flaws and a non-uniform loop structure. Furthermore, the forces developing between the working portion of the needle and the verge groove would be greater, resulting in increased wear and power consumption. Mutual parallelism of the two portions is, in this context, an ideal. Manufacturing tolerances and play between the needle and the respective guiding and verge grooves almost always result in a small angular offset between the working portion and the shank portion. The expression “substantially parallel” means in this case that the working portion and the shank portion are parallel to the extent possible within the technical tolerance limits of routinely used manufacturing methods.
Also to advantage is a knitting system according to the invention, which has at least one guiding wall, which limits the at least one guiding groove in peripheral direction, and at least one additional bar, which adjoins the at least one guiding wall in working direction and is arranged on the base surface of the needle-guiding means, wherein for the width ratio (V) of the guiding-wall width (bFS) to the additional-bar width (bHS), V=bFS/bHS, the following applies: 2.0≤V≤2.5, preferably 2.1≤V≤2.4. The use of additional bars to support a sinker holder—in connection with a circular knitting machine cylinder this is also known as a sinker ring—in which sinker grooves for additional knitting tools involved in the knitting process, for example sinkers, are arranged, has been known for many years.
However, hitherto known additional bars generally have the same width in peripheral direction as the adjoining guiding wall. In the case of the knitting system according to the invention, the additional bars and the bending portion of the needles are located at the same height in working direction. In order to prevent collisions and friction between the bending portion of the needles and the additional bars, it is therefore advantageous to configure the additional bars to be narrower than the guiding walls—in particular bearing in mind the above-mentioned size ratios. In consequence of the concomitant avoidance of contact points, the power consumption of the whole knitting system decreases and there is less wear. It is not necessary for every guiding wall to have an adjoining additional bar in order to guarantee correct functioning. On the contrary, the number of additional bars may be fewer than the number of guiding walls.
Additional advantages are obtained if, between a working-portion centerline extending in the middle of the working portion along the tool's longitudinal direction and a shank-portion centerline extending in the middle of the shank portion along the tool's longitudinal direction, a shank offset S in peripheral direction exists, which is composed of a plastic shank offset SPL and an elastic shank offset SEL resulting from an elastic deformation—i.e. S=SPL+SEL, wherein, for the shank offset, as a function of a pitch t and the shank width dS, the relation S=(t−dS)/2 applies. In addition to a purely elastic bend and a purely plastic bend in order to compensate the shank offset between guiding groove and verge groove, it is advantageous to superimpose a plastic and an elastic bend in the bending portion.
On account of the plastic component of the bend, the proportion of the shank offset that has to be compensated with an elastic bend decreases and so, consequently, does the bending force and the component loading due to elastic deformation. This is advantageous particularly in the case of large pitches—i.e. large shank offsets.
It is advantageous if the shank portions of at least two needles are accommodated in one and the same guiding groove. Walls are required for the formation of guiding grooves. The transverse forces acting on the needle's drive butt are discharged onto these walls. If two or more needles are accommodated in the same guiding groove, the number of guiding grooves and consequently also guiding walls required for a given number of needles decreases—the installation space is accordingly better utilized. Consequently it is possible, without changing the size of a needle-guiding means in peripheral direction—e.g. in the case of a knitting cylinder, without increasing the circumference or the diameter of the cylinder—to operate a larger number of needles and obtain a finer pitch.
Also to advantage is a needle with the following features:
It is advantageous if at least one recess at a lateral surface pointing in peripheral direction has a recess depth of 10 μm to 100 μm, advantageously 30 μm to 70 μm, and/or at least one recess at a lateral surface pointing in elevational direction has a recess depth of 150 μm to 500 μm, advantageously 200 μm to 400 μm. If the recess were too deep, the needle would be weakened too much in the bending portion. If, on the other hand, the recess is not deep enough, the stability of the needle in the shank portion and working portion cannot be sufficiently improved. The above-mentioned selection range has proved advantageous with customary needle widths of less than 0.6 mm because a positive effect is obtained with regard to stability and wear resistance in the shank and working portions but, at the same time, the needle is not weakened too much in the bending portion.
Further advantages are obtained if the at least one recess extends, in an elevational direction which is at right angles to the working direction and the width direction, over the entire needle height. A recess which extends over the entire needle height requires less complex production methods than a recess which only extends over part of the needle height.
However, a recess which extends in elevational direction over a maximum of 90%, preferably a maximum of 80%, of the needle height is also advantageous. It is particularly advantageous if the height of the recess in elevational direction—i.e. the recess height—is a maximum of 90%, preferably, however, a maximum of 80% of the needle height. The bending properties of the needle can also be specifically adapted to the knitting system with a recess which does not extend over the entire needle height. The extension of the recess in elevational direction relative to the needle height thus influences the rigidity and strength of the needle in the bending portion.
It is also advantageous if the working portion and the shank portion extend substantially parallel to one another in working direction. During the knitting process, knitting-machine needles generally perform purely translatory motion in the needles' working direction. It is advantageous for a precise knitting movement if the working portion and the shank portion are mutually parallel.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2020 128 660.0 | Oct 2020 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2021/079909 | 10/28/2021 | WO |
