US2817879A - Rubbing aprons - Google Patents

Description

L. CHIOVATO ET AL Dec. 31, 1957 RUBBING APRONS Filed July 6, 1955 IN VENT 0R5 United States Patent 2,817,879 RUBBING APRONS Luigi Chiovato and Gianfranco Leguani, Milan, Italy, assignors to Pirelli, Societa per Azioni, Milan, Italy Application July 6, 1955, Serial No. 520,311 Claims priority, application Italy July 16, 1954 3 Claims. (Cl. 19-153) This invention relates to rubbing aprons for carding machines, and, more particularly, to such aprons having rubber outer layers provided with slits therein to improve their condensing action.

A rubbing apron is used to condense a card web prior to a spinning operation and therefore receives a series of parallel rovings from the card, and, by relative trans verse motion between a pair of such aprons having the rovings passing in frictional engagement between their adjacent surfaces, condenses the formerly loose, relatively wide, rovings, to compact, narrow rovings.

In order to improve the efiiciency of the condensing action of such an apron, it has been proposed to provide each cooperating apron with grooves cut inward from its outer surface and extending generally in the direction of movement of the rovings. These grooves extend spirally around the body of the apron and have been cut therein by removal of material, usually leather, from the body of the apron. Such grooves are usually about 3 to 5 mm. spaced, about 1.8 mm. deep, and about 1.5 mm. wide. The grooves in the aprons operate on the rovings passing by them, which are usually spaced from 40 to 50 mm. apart, to prevent the individual rovings from being coupled together during the condensing operation.

In use of aprons provided with grooves as above described, however, it has been found that after a period of use, the apron surface wears down to smooth off the grooves and decrease the frictional adhesion between the rovings and the apron. This results in a decrease in the efficiency of the rubbing operation of the rubber, thus resulting in increasing failure to form round, uniform rovings.

By the use of our invention, however, it has been found that the rubbing efficiency of the apron may be maintained constant over a very long period of time.

Our invention comprises a rubbing apron constructed with a rubber outer surface, and, rather than having grooves formed by removal of material from the card rubber, having scores or slits cut into the rubber surface and extending very deeply therein.

The invention will now be more fully described in conjunction with the accompanying drawing, in which:

Fig. 1 is a perspective view of a rubbing apron, constructed in accordance with the invention;

Fig. 2 is a plan view of the device of Fig. 1; and

Fig. 3 is a partial sectional view, taken along line 3-3 of Fig. 2.

In the drawing, a rubbing apron is indicated generally at A. This apron is of conventional form and is adapted to operate in conjunction with an oppositely disposed similar apron, on a pair of rollers (not shown) which are conventionally rotated and reciprocated in an axial direction, to give the rovings of the web passing between the adjacent parallel surfaces of the two aprons a rubbing action. Since apparatus which will cooperate with apron A to perform this purpose is conventional and well known to those skilled in this art, such apparatus is not here shown or described.

This invention relates to a peculiar and novel construction of the body of the apron, and will now be described in conjunction with Fig. 3.

As shown in Fig. 3, the apron A consists of a base layer of rubber, two layers of rubberized fabric 2 superimposed and fixed on the base layer, and of a rubber covering 3 fixed to the outer side of the outer fabric layer. This particular combination of layers forming the apron is designed for long wear and precise operation, but it is not particularly important to this invention. What is important is that the outer layer 3 of the apron be of rubber, and that it have the novel characteristics now to be described.

In order to provide for an efficient rubbing action in operation of the apron, a number of slits 3a are cut into the surface of the outer rubber layer of the apron substantially perpendicularly to its outer surface, these slits extending through the major portion of the depth of the layer. The slits are preferably continuous around the surface of the apron in such form as to form a continuous helical groove therein.

The slits 3a are preferably spaced apart a distance of between 0.5 and 2 mm. and each have a depth of up to W of the depth of the rubber layer 3. The slits thereby divide the outer rubber layer of the apron into a multiplicity of relatively thin rubber plates 4, attached to the base of the outer rubber layer only at their inner sides.

During the rubbing action of the apron, the rubber plates 4 of the apron bend like the hair of a brush, as shown at 5 in Fig. 3.

Tests of aprons constructed as detailed above have shown that a constant, high level, rubbing action is obtained therewith, and that the life of the apron is quite long, terminating only when the rubber plates 4 have worn down to the uncut portion of rubber layer 3.

It is, of course, not essential that the slits 3a in the outer rubber layer be continuous to form a helical groove, but rather this invention includes any arrangement of such slits as long as they penetrate the major portion of the depth of the outer rubber layer, up to W of said depth, and as long as the slits are made without removal of material from the apron and are spaced close together, preferably between 0.5 and 2 mm. apart. It will be understood that the term slit, as used in this description and the appended claims, refers to knife-cuts in the surface of the rubber layer, and does not cover grooves in the surface formed by removal of material therefrom.

We claim:

1. A rubbing apron for a card condenser having an outer layer of rubber extending over its operative surface and adapted to be reciprocated substantially perpendicularly to the direction of travel of the web with which the apron is to be used, said rubber layer having a multiplicity of slits therein extending generally in the direction of travel of the web and around the periphery of the apron, said slits extending substantially perpendicularly to the outer surface of the rubber layer through the major portion of the depth thereof, and said slits being spaced closely to define a multiplicity of narrow rubber blocks in the surface of the apron which bend oppositely to the direction of travel of the apron during its reciprocating motion to assist the condensing action.

2. The apparatus defined in claim 1 in which said slit are spaced apart between 0.5 and 2 min. and extend through up to of the depth of the rubber layer.

3. The apparatus of claim 2 in which said slits form a continuous substantially helical path around the surface of the rubber layer.

References Cited in the file of this patent UNITED STATES PATENTS 489,281 Barker Jan. 3, 1893 1,442,767 Hunter et al. Jan. 16, 1923 2,434,820 Tifi't Jan. 20, 1948

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