The invention concerns a cleaning lip for a rotating roll of a textile machine in a rolling mill for processing fibrous materials wherein the cleaning lip is comprised of a carrying means integrated with a lip, the length of the lip being limited by a wiping edge and wherein the lip is composed of plastic.
"Textile machine" in its concept encompasses drawing frames, such as carding and stretching machines, as well as spinning machines common to a rolling mill. These textile machines process fiber material, textile in nature. This fiber material includes cotton or its mixtures with artificial fibers. The fiber material can be available as fiber fleece or fiber in band form.
In the rolling mill, pairs of rolls are arranged. A pair is formed by an upper and lower roll, between which the fiber material is guided.
Besides fiber of desired length, on the band being rolled are found short fibers, and contaminating material. Regarded as contamination in cotton are solid dirt particles, pod husk particles, dust, foreign material and, possibly, finishing compounds.
These impurities, as well as fibers, collect upon the outside surface of the roll. There, they disadvantageously interfere in the gap between the pairs of rolls, thus fostering wrapping on the rolls. The formation of wrap-around finally leads to a blockage of the fiber material at the roll pair. In order to avoid this undesirable condition, a cleaning lip is installed in contact with the outer surface of the rotating roll.
Rieter Ingolstadt Spinnereimaschinenbau AG shows in its Operation Manual, Roll Mill RSB 851 (4135), SB 851 (4131), pg. 27, Item 4.4.2.8 and pg. 28, FIG. 5, the installation of cleaning lips (P2) on the rolls of a 3 over 3 rolling mill. The cleaning lip is made by combining a carrying means and a lip. The cleaning lip is disposed at such an angle to the roll, that the wiping edge of the lip runs parallel to the longitudinal axis of the roll. Further, the cleaning lip under bending stress assumes a curved position on the roll. Upon the rotation of the roll, the cleaning lip removes the accumulating impurities from the outer surface of the roll and aids in cleanliness of operation.
As the said operational manual illustrates, the impurities fall away from the cleaning lip and are picked up by a pneumatically operating suction system of the rolling mill for disposal.
Illustration 5 in the manual shows that the lip has a relatively extended length which calls for a contact position at the roll dependent upon the direction of rotation. Upon a reverse of rotation for a short interval, (which an operator does to correct wrapping on the roll) the approach position of the wiping edge of the cleaning lip changes itself in such a way that upon the subsequent return to forward rotational motion by the roll, the wiping edge of the cleaning lip does not resume its previous approach position. In such a case, the function of the cleaning lip is substantially limited. The approach position of the wiping edge must then be additionally monitored and corrected.
When in operation, the cleaning lip is exposed to powerful mechanical and thermal demands. A mechanical stress arises from heavy contamination of the roll or from wrapping formation. The friction between the lip and the outer surface of the roll leads to high thermal conditions. This leads to the situation, that in a very short period, the wiping edge of the lip no longer forms a constant, uniform, contact line on the outer surface of the roll. Evidence exists that the wiping edge corrugates or wears away and no longer lies on the outer roll surface with the entire edge. Then a varied rate of heat expansion exists between the carrier means and the lip.
Under these circumstances, the function of the cleaning and contamination removal of the surface of the roll deteriorates. This requires a replacement of the cleaning lip. At present, the durability of the cleaning lip is relatively short.
In the state of the technology, there have been further attempts to improve the cleaning lip. CH 681 459 A5 exhibits the purpose of assuring a good exchangeability of the rubber element (corresponds to the lip) and to increase the wiping effect. From the standpoint of the technical construction, the said rubber element is expensive.
DE 34 22 139 presents the purpose of creating a wiper (i.e. cleaning lip) which functions reliably and the manufacture of which is economical. In this case, simultaneously, the disadvantages arising from a stiffening of the wiping lip are to be avoided. The stiffening is achieved principally through a structural arm of the holding bar. By this means, the flexibility of the lip is limited, which is not desirable where wrapping is the problem. A corrugated structural member on the back side of the lip requires an increased cost of manufacture. Since the longitudinal grooves and ribs (corrugated structural member) run to the wiping edge, one must consider increased local abrasion in the area of the grooves at the border of the wiping edge. As FIG. 1 of DE 34 22 139 C2 shows, the wiping edge of the cleaning lip therein is disposed at a small gap from the cylinder. The cleaning action is thereby limited disadvantageously where wrapping is concerned. The DE 34 22 139 C2 claims a weakening of the wiping lip in both the longitudinal and cross direction. In spite of the costly form of the wiping lip, it amounts to a corrugation of the wiping edge.
EP 45 725 shows a lip with a stiffening (ribs) on the free end of the lip. The expectation is that a longer durability will be achieved in this manner. On the grounds of the relatively great stiffness or rigidity, there still arises the increased danger of fissure formation at the lip, which does not lead to any increase in durability.