Abstract:
A seal unit for sealing a clearance between relatively movable first and second machine components includes a low-friction, wear-resistant sealing element having a sealing face for sealingly engaging a surface of the first machine component; a spring having a soft spring characteristic and being at least indirectly in engagement with the second machine component and a reverse face of the sealing element for resiliently urging the sealing face of the sealing element against the surface of the first machine component.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to a device for sealing a clearance between two relatively moving surfaces, particularly a radial end face of a roll in a fiber processing machine and an adjoining stationary wall face forming part of the machine (such as a card, a roller card unit, a card feeder or a cleaner). 
     It is generally difficult to seal relatively movable surfaces against one another. Such is the case when a seal has to be provided between a radial end face of a rotary roll or cylinder and an adjoining wall surface. It is known, for example, to use squeegee-like devices which, however, have not proven to be satisfactory. The principal difficulty in fiber processing machines resides in the fact that air circulations in the clearance lead to undesired fiber movements. Thus, very small fiber fragments gain access to the clearance in which they may accumulate which, in the long run, leads to clogging or significant braking of the roll. For preventing fiber particles from entering into the clearance, bristle seals have been used. These, however, have also not proven successful because they were either too stiff or too loose and thus have led either to a braking of the roll accompanied by significant frictional heating or have not provided an acceptable seal at all. It is a also a disadvantage of known sealing constructions that in case of a periodic engagement of the seal, a &#34;breathing motion&#34; between the space to be sealed and the external environment occurs. 
     SUMMARY OF THE INVENTION 
     It is an object of the invention to provide an improved device of the above-outlined type from which the discussed disadvantages are eliminated and which, in particular, ensures a secure and operationally safe sealing of the rotating roll against the adjoining stationary lateral surfaces. 
     This object and others to become apparent as the specification progresses, are accomplished by the invention, according to which, briefly stated, the seal proper is a low-friction, wear-resistant material which, on its reverse side, is engaged by a soft spring element urging the sealing face of the seal towards the component to be sealed. 
     By pressing the low-friction and wear-resistant sealing member by a soft spring or springs against a counterface, there is advantageously achieved an operationally safe, gapless seal. The spring force urges the sealing member, for example, a sealing ring, sealingly against the counterface and the use of a soft spring element simultaneously avoids disturbing effects such as wear, frictional heat-up, braking, and the like. 
     Advantageously, the seal is made of a felt material It is difficult, circumstantial and thus economically not feasible to narrow and control the tolerances in machine construction in such a manner that, on the one hand, no braking occurs and, on the other hand, no air gap appears. Felt material is viewed as the ideal sealing substance from the point of view of frictional and wear behavior. Felt material is, however, rigid to a high degree if in a compressed state, and a large force is needed even if a 0.1 mm further compression is to be obtained. Since during such a compression the force increases very substantially, there will also rapidly appear a large friction force which is not desirable. Temperature-caused expansions of machine components also lead to changes of dimensions, including the sealing clearance. Such changes are advantageously absorbed by the felt material. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     FIG. 1 is a schematic side elevational view of a carding machine incorporating the invention. 
     FIG. 2 is a sectional elevational view of a preferred embodiment of the invention. 
     FIG. 2a is an exploded detail, on an enlarged scale, of the embodiment illustrated in FIG. 2. 
     FIG. 3 is a sectional elevational view of another preferred embodiment of the invention. 
     FIG. 4 is an elevational view of yet a further embodiment of the invention. 
     FIGS. 5, 6 and 7 are perspective sectional views of three further preferred embodiments of the invention. 
     FIG. 8 is a perspective view illustrating the embodiment of FIG. 7 for a use different from that shown in FIG. 7. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In FIG. 1 there is shown a carding machine which may be an EXACTACARD DK 740 model, manufactured by Trutzschler GmbH &amp; Co. KG, Monchengladbach, Germany. The carding machine has a feed roll 1, a feed table 2, a licker-in 3, a main carding cylinder 4, a doffer 5, a stripping roll 6, crushing rolls 7, 8, a web guide element 9, a sliver trumpet 10, calender rolls 11 and 12 as well as travelling flats 13 cooperating with the main carding cylinder 4. The direction of rotation of the respective rotary components is designated by an arcuate arrow. The reference numeral 14 designates the fiber lap which is introduced into the carding machine at the feed roll 1 whereas reference numeral 15 designates the fiber sliver withdrawn from the trumpet 10 by the calender rolls 11, 12. 
     Also referring to FIG. 2, there is shown therein one end portion of the licker-in 3 which has a cylindrical body shell 3b terminating in an annular edge face 3a which is at a narrow clearance a from the inwardly oriented surface 17a of a lateral stationary wall 17. The cylindrical shell 3b is closed by a radial bottom 3d which is recessed inwardly and is at a distance b from the stationary wall 17. A seal assembly 16 is supported on the outer face 3c of the bottom 3d. The sealing ring 18 is situated at an outer diametral zone of the base 3c. It is feasible to position the sealing ring 18 on the edge face 3a, that is, at an outer diametral zone of the licker-in 3. 
     The seal assembly 16 is formed of a sealing ring 18 made, for example, of felt and a spring ring 19 made, for example, of foam plastic. The inner radial surface 18b of the sealing ring 18 and the outer radial surface 19a of the spring ring 19 are firmly bonded (for example, glued) to one another. The outer radial surface 18a of the sealing ring 18 is in a sliding contact with the inner surface 17a of the side wall 17, whereas the outer radial surface 19b of the spring ring 19 is stationarily affixed to the outer radial surface 3c of the base 3d. It is also feasible, in the alternative, to attach the spring 19 to the wall 17, in which case the surface 18a of the sealing ring 18 contacts the surface 3c of the radial base 3d. 
     The embodiment illustrated in FIG. 3 includes a cross-sectionally U-shaped annular housing 20, receiving the two-part seal assembly 16. The sealing ring 18 and the spring ring 19 are supported together in the unilaterally open annular housing 20 by a glue connection between the outer radial surface 19b of the spring 19 and the inner bottom face 20a of the housing 20. The outer radial face 20b of the housing 20 is secured to a radial end face of the roll, such as the outer face 3c of the bottom 3d shown in FIG. 2. It is feasible, as an alternative, to secure the face 20b to the side wall 17. Between the aligned inner circumferential surfaces 18c of the sealing ring 18 and 19c of the spring ring 19 on the one hand and the adjoining inner circumferential surface 20c of the housing 20 a clearance e is provided, whereas between the aligned outer circumferential surfaces 18d of the sealing ring 18 and 19d of the spring ring 19 and the adjoining inner circumferential surface 20d of the housing 20 a clearance f is provided so that the seal assembly 16 is free to move in the direction of the arrows A and B. One part of the sealing ring 18 is displaceable along a length c (for example, 5 mm) between the inner wall faces 20c and 20d. Thus, the sealing ring 18 is, along length c situated inside the housing 20 whereas the other part thereof (along length a) projects beyond the housing 20. In this manner, the glue bond between the surfaces 18b and 19a is protected within the housing 20 against rupture by transverse forces, and the sealing ring 18 is reliably guided within the housing 20. 
     Turning to the embodiment illustrated in FIG. 4, the linear sealing element 18&#39;, on its face opposite from the sealing face, is covered by a flat intermediate component 22 which is engaged by a plurality of leaf springs 21 which have soft spring characteristics and whose respective opposite ends are secured to a stationary surface 23. 
     FIG. 5 shows an embodiment which is similar in structure to the FIG. 3 embodiment except that the sealing element 18&#34; and the housing 20&#39; are of linear design, and the spring force is supplied by a series of spaced coil springs 24 (only one shown) situated between a backing strip 22 attached to a rear face of the sealing member 18&#34; and the bottom face 20b&#39; of the housing 20&#39;. 
     A variant of the embodiment of FIG. 5 is illustrated in FIG. 6, wherein the spring element is a hollow rubber spring 25 of rectangular cross section, whose one surface contacts the rear face 18b&#34; of the sealing member 18&#34; and whose opposite face contacts the bottom face 20b&#39; of the housing 20&#39;. The rubber spring 25 is filled with air and is compressible. As an alternative, it is feasible to use a solid rubber spring. 
     It will be understood that the linear constructions of FIGS. 4, 5 and 6 may be of annular design, similarly to the embodiment shown in FIG. 3. 
     The embodiment shown in FIG. 7 is a linear variant of the annular structure of FIG. 3. The spring element is a bar-like foam rubber element 19&#39;. The surface 18a&#34; of the sealing element 18&#34; sealingly contacts a planar surface of a planar component 26 movable in the direction of arrows C and D. 
     In FIG. 8, there is shown the embodiment structured according to FIG. 7 cooperating with a cylindrical surface 27a of a joint 27 rotatable in the direction of arrows E and F. 
     While the invention was described for use with a licker-in 3 of a carding machine, it is to be understood that the seal assembly may also find application in any relatively movable components such as rotary members of fiber cleaning machines, fiber feeders or other fiber processing apparatus. 
     It will be understood that the above description of the present invention is susceptible to various modifications, changes and adaptations, and the same are intended to be comprehended within the meaning and range of equivalents of the appended claims.