|Title of Invention||
A FLEXIBLE BEND FOR A REVOLVING FLAT CARDING MACHINE
|Abstract||A flexible bend for a revolving flat carding machine, wherein the height profile along the circumference of the flexible bend is formed in such a way in the direction of the center of the radius (12) that during a displacement of the adjustment points the upper edge of the flexible bend is raised or lowered uniformly with a constant shape over the entire carding range.|
The present invention relates to a flexible bend for a revolving flat carding machine.
Together with the cylinder, the flat region forms the main carding zone and has as its function the loosening of the flocks to form individual fibers, the separation of contaminants and dust, the elimination of very short fibers, the opening of neps and the parallelization of the fibers. Since the flats become blocked by dirt and fibers, it is necessary to clean them. The revolving flat was therefore developed, the flats being held together by means of a chain or a belt and being combined into an endless, circulating belt. Some are in direct use opposite the cylinder clothing. The remainder are transported onward via deflection rolls in a reverse attitude and can be cleaned and possibly ground.
Between the clothing of flats and cylinder there forms a narrow gap, which is called the carding gap. It results because the revolving flats, guided by arcuate strips - called flexible bends, regulating bends, flex-bends, flexible curves or sliding bends - are guided along in the circumferential direction of the cylinder at a specific, not necessarily constant, carding distance. The size of the carding gap in a revolving flat carding machine is between 0.10 ... 0.30 mm for cotton or up to 0.40 mm for chemical fibers. Therefore, the ability to adjust the flexible bend precisely is of central importance.
In the working position, the flats slide on the flexible bends when the clothing of cylinders and flats are arranged opposite one another. These flexible bends are approximately concentric with respect to the cylinder axis of rotation, on each side of the cylinder. They are fixed to the side pieces or cylinder plates of the carding machine, specifically in such a way that they can be readjusted easily and safely. Since the carding gap changes continuously with the grinding and the wearing of the clothing, the bends must be flexible in order to be able to permit readjustment and thus correction of the carding gap to the intended dimension. For this purpose, the flexible bends are normally cast from a special alloy which has elastic properties. Thus, the flexible bends
can be brought into the necessary shape with relatively little expenditure of force and with little stress.
For the adjustment of the flats or of the carding gap, various flat regulating systems have been developed over the course of time. The oldest design is three-point regulation, as described in Johannsen, Handbuch der Baumwollspinnerei [Cotton spinning handbook] (Vol. II, 1963, page 50 et seq.). In this case, the flexible bend is supported at three points by loadbearing supports. By means of the adjustment toward the cylinder axis of rotation or away from the latter, the radius of the flexible bend upper edge can be changed. However, producing a displacement without undesired material stresses in the circumferential direction presupposes that the ends of the bend have to be pushed forward on their supporting points. For this purpose, at these supporting points the bend has slots, through which the adjusting means pass. If the flexible bend is set closer, the radius decreases and the end of the bend at the outer supporting points is displaced to the side, since the length of the bend remains unchanged in relation to the initial state. At the conclusion, the position of the adjusting means in the slot is fixed. This principle has been developed further in five-point regulation systems, primarily in order that the weight on the flats can be distributed better over the supporting points and the deflection of the bends can be prevented. This regulation system operates with a vertex which can be changed only in the direction of the radius but is fixed with respect to the side. The end and intermediate points can be displaced in both directions. One example of a newer five-point regulation system is described, inter alia, in EP 787 841. Although many improvement proposals for the adjusting devices and regulation system have been proposed, in practice there are still problems with undesired deformation of the flexible bends. One main problem resides in the fact that "hills" and/or "valleys" are produced between the adjustment points and are reflected directly in a carding gap which does not run uniformly. These deformations can effect locally radial deviations of some hundredths of a mm and, as compared with the typical size of a carding gap mentioned at the beginning, are therefore sufficiently large to have a noticeable effect on the carding behavior. This is in turn reflected negatively in the quality of the sliver, the end product of the carding machine.
The invention of the present application is based on the object of providing a device of the type described at the beginning which avoids the aforementioned disadvantages and, in particular, prevents possible undesired deformations of the device between the adjustment points.
According to the invention, this object is achieved by a device having the features of the independent patent claim 1. In particular by constructing the flexible bend in such a way that, during a displacement of the adjustment points, the upper edge of the flexible bend is raised or lowered uniformly with a constant shape over the entire carding range. For instance, the intention is to avoid a flexible bend with an initially circular upper edge being shaped elliptically after the displacement
In the following text, the invention will be explained in more detail by using examples.
Figure 1 shows a schematic illustration of the carding machine Figure 2 shows a schematic illustration of the flexible bend according to the
Figure 1 shows a revolving flat carding machine, for example the Rieter Karde C60 with a working width of 1.5 meters. Fiber flocks are transported through the various cleaning process stages through transport ducts (not shown) and finally supplied to the cleaner shaft (16) of the carding machine. Instead of a cleaner shaft, a normal filling shaft can also be provided. The latter than passes on the fiber flocks to the carding machine as wadding. The feed device feeds the fiber flocks to the lickers-in (3). The lickers-in open the fiber flocks and remove some of the dirt particles. The last licker-in roll transfers the fibers to the card cylinder (1). The card cylinder interacts with the flats (7) and in this case parallelizes the fibers still further. The flats are cleaned by a flat cleaning system (14) and possibly re-ground by means of a grinding device. After the fibers have to some extent carried out a plurality of revolutions on the card cylinder, they are taken off the card cylinder by the doffer roll (4), supplied to the doffing region (5) and finally deposited as a card sliver in a can holder in a can (not shown).
The flats belong to a system of revolving flats (2); where by, flats are moved onward over the cylinder surface by means of a drive with the aid of an endless belt or chain via deflection rollers (6), normally counter to the direction of rotation of the cylinder. The underside of the flat is provided with a clothing, for example with a sawtooth clothing or flexible clothing in the form of little hooks. The cylinder also has a clothing which interacts with the flat. A revolving flat set comprises around 80 ... 120 flats, of which only part are in the working position. The number of flats in the working position depends, inter alia, on the diameter of the cylinder and the revolving flat arrangement. On average, these are 20 ... 46 flats. Between the cylinder clothing and the flat clothing there is a gap, which is called the carding gap. Furthermore, the flexible bend has means (13) for adjusting the bend, arranged in such a way that accurate adjustment of the carding gap can be performed. This carding gap is normally adjusted with a constant distance from the cylinder over virtually the whole of the carding zone. However, the gap can also be adjusted to open - the carding gap becomes greater - or to close - the carding gap becomes smaller. For the monitoring of the adjustment, slots can be made in the side of the bends, through which the distance between the clothing can be measured with gauges.
Figure 2 describes a flexible bend (8) according to the invention in more detail. The upper edge (9) of the bend is used directly or indirectly as a sliding surface for the flats (7). These have special end pieces for this purpose.
In the following text, in order to explain the flexible bend shape according to the invention, a circular flexible bend upper edge will be assumed. However, this is not an imperative condition, as will be proved later.
Therefore, assume that the flexible bend has an upper edge with a constant curvature, which is used as a sliding surface for the flats and is arranged circularly-concentrically in relation to the cylinder axis of rotation. This leads to a constant carding gap over the entire carding zone. The inventive flexible bend is now characterized by a characteristic profile course h(g>),
which is formed along the circumference (or the upper edge (9)) in the direction of the
center (12). This profile course can be derived from the polar moment of inertia, which is:
where I is the polar moment of inertia; I0 is I at the central adjustment point; øis the
angle originating from the central adjustment point; ø0 is the angle between the central and outer adjustment point.
The theoretical principles for deriving this formula will be found, inter alia, in Dubbel} Taschenbuch fur den Maschinenbau [Mechanical Engineering Handbook], 18th edition, para. 2.4, Bending, p. 186ff.
The inventive geometry of the flexible bend is therefore independent of the contour of the upper edge. The necessary and sufficient condition for the flexible bend is that the polar moment of inertia decreases linearly over the circumference, from / = i0 (at ø =
0) to / = 0 (at ø = 90).
If the profile of a flexible bend is fabricated in accordance with this law, a uniform deformation of the upper edge is given. On the basis of the assumption made at the beginning that the flexible bend has a circular upper edge, this means that: If the adjustment points are all displaced toward the center of the circle or away from the latter by a specific amount, the flexible bend thereafter always still has a circular shape, defined by a radius which is smaller or greater by this amount than the initial radius.
The profile shape of the flexible bend, calculated from the given polar moment of inertia curve, depends in particular on the cross section of the flexible bend. In principle, a rectangular cross section is used but a cross section in trapezoidal form or a rounded variant can also be employed. Likewise, any desired cross sections are conceivable, which do not have to be the same over the entire flexible bend. Specifically, it is true for a rectangular cross section that:
Here, b is the width of the cross section and h is the height of the cross section.
The course of the profile height h(ø) of the flexible bend in the interval 0
The inventive geometry of the flexible bend is thus independent of the choice of materials or their properties. By means of the suitable calculation of the profile shape from the polar moment of inertia, it is also possible for holes, necessary in the flexible bend if, for example, it is wished to inspect the adjusted carding gap with a gauge - to be taken into account. The flexible bend can also comprise a plurality of parts which together in turn form a subassembly, for example two wedge-shaped bend parts, as described in DE 196 51 894.
1. A flexible bend for a revolving fiat carding machine, characterized in that the
height profile along the circumference of the flexible bend in the direction of the
center of the radius (12) is formed in such a way that during a displacement of
the adjustment points the upper edge of the flexible bend is raised or lowered
uniformly with a constant shape over the entire carding range.
2. The flexible bend as claimed in claim 1, characterized in that the height profile is
derived from the polar moment of inertia where / is the polar
moment of inertia; /0 is / at the central adjustment point; ø is the angle
originating from the central adjustment point; ø0 is the angle between the central and outer adjustment point.
3. The flexible bend as claimed in claim 1 or 2, characterized in that the flexible
bend has a rectangular cross section and the height profile therefore
corresponds to the formula where b is the width of the cross
section and h is the height of the cross section.
4. The flexible bend as claimed in one of the preceding claims, characterized in that
the upper edge (9) is circular.
5. The flexible bend as claimed in one of the preceding claims, characterized in that
additional constructional elements, e.g. holes, are taken into account.
6. The flexible bend as claimed in one of the preceding claims, characterized in that
the bend is assembled from a plurality of parts.
7. A carding machine having at least one flexible bend as claimed in claims-to 6. a
|Indian Patent Application Number||3924/CHENP/2006|
|PG Journal Number||13/2014|
|Date of Filing||26-Oct-2006|
|Name of Patentee||MASCHINENFABRIK RIETER AG|
|Applicant Address||KLOSTERSTRASSE 20, CH-8406 WINTERTHUR, SWITZERLAND|
|PCT International Classification Number||D01G 15/30|
|PCT International Application Number||PCT/CH05/00206|
|PCT International Filing date||2005-04-12|