Title of Invention

AN IMPROVED DRAFTING DEVICE FOR A SPINNING MACHINE

Abstract

The invention relates to an improved drafting device a spinning machine comprising an input roller pair (2); an output roller pair (3); an intermediate roller pair (4); an upper belt (5); a lower belt (6); a roller (7); and a part (8,9) constituting of a reversing rail (8) and a tensioning stirrup (9) over which said upper and lower belt (5,6) slide. A fluropolymer covering is directly applied to one of the metal surfaces of said part (8,9) over which the belts (5,6) slide and a rust-proof sprayed on hard metal alloy being applied on the parts (8,9) over which the belts (5,6) slide.

Full Text

The invention relates to a drafting mechanism for a spinning machine with a lower belt which is guided about a roller and a reversing rail or via a tensioning stirrup or over both. The state of the art includes, for drafting mechanisms of spinning machines in textile machinery like, for example, ring spinning machines or roving spinning frames, a construction in which a lower belt is guided at least over one lower belt roller and a reversing rail. The lower belt roller serves here to drive the lower belt. In many cases the lower belt, which engages the lower belt roller and the reversing rail, is also guided over a tensioning stirrup which is spring loaded. In this manner, the lower belt can be maintained at an approximately constant tension. The tension of the lower belt is adjustable in that the tensioning stirrup rod carrying the tensioning stirrup, which extends into bores in the machine support stampings, can be rotated. In other cases (German Patent Document 4 401 880 Al) a short lower belt runs about a roller and a reversing rail. The stretch of the short lower belt running from the reversing rail composed of sheet metal, is provided with a guide. It is also known to provide a belt table for a stretching frame (German Patent Document 41 22 881 Al) in which the table plate is formed with a projection which is provided on opposite sides with counter surfaces guided in a form fitting manner in a recess like a slide - 1A- guide during the swinging movement of the table plate. The table plate and the projection are comprised of a synthetic resin material. A tensioning mechanism is known for a belt which, on the one hand is provided with a free end and on the other provides a guide wall which prevents the lateral shifting of the belt over the free end. Both the surface of the conventional reversing rail and the surface of the tensioning stirrup can be coated, for example, by zinc plating, chromium plating or with epoxy resin lacquers, to reduce the surface wear. It is the object of the present invention to provide a spinning machine drafting mechanism of the aforedescribed type which is so formed in a new way that a reduction of the wear and an increase in the useful life is achieved. This object is attained in accordance with the invention by a fluoropolymer which is applied either directly to the metal surfaces of the reversing rail and/or the tensioning stirrup or upon a stainless hard metal coating sprayed onto the surface, especially a chromium-nickel steel alloy or a chromium- molybdenum steel alloy. With such a coating, it is possible to achieve in a simple way a significant increase in the useful life of the reversing rails and/or the tensioning stirrups of the device. It is already known in the art indeed to provide a process for the coating of a substrate with a fluoropolymer layer in which the surface of the substrate is thermally sprayed with a stainless steel alloy (EP 0 365 602 B1). From this art, however, there is no suggestion of a process for coating metal surfaces of reversing rails and/or tensioning stirrups in drafting mechanisms of spinning machines. - 2 - According to a further feature of the invention, only the surfaces contacted by the lower belt of the reversing rail are coated. When the reversing rail is, in cross section, an L-shaped member with an upper shank and a forward shank, the upper shank along its upper side and the front side of the forward shank are thus coated. When the reversing rail is T-shaped in cross section with a horizontal shank and a vertical shank then the upper side of the horizontal shank and at least an end portion thereof is provided with the coating. According to a further feature of the invention, only the surfaces of the tensioning stirrup which are contacted by a lower belt are coated. The chromium-nickel steel alloy or the chromium- molybdenum steel alloy can contain 20 to 40% by weight chromium and 6 to 20% by weight of nickel or molybdenum or a mixture of the two. The invention is further described below in conjunction with an example illustrated in the accompanying drawing: FIG. 1 is a section through a spinning machine drafting mechanism with reversing rail and tensioning stirrup; FIG. 2 is a section through the reverse rail which is T-shaped in cross section; and FIG. 3 is a section through a tensioning stirrup. In FIG. 1 a drafting mechanism 1 of a spinning machine has been shown in a schematic side view. This drafting mechanism 1 comprises an input roller pair 2, an output roller pair 3 and an intermediate roller pair 4 with - 3 - an upper belt 5 and a lower belt 6. The lower belt 6 is guided around a driven lower roller 7, a reversing rail 8 which is a T-shaped in cross section, and a tensioning stirrup 9. The tensioning stirrup 9 is part of a tensioning device 10 known per se. According to the invention, the metal surfaces of the reversing rail 8 and/or of the tensioning stirrup 9 are provided with a coating 11 which in its lower layer is comprised of a sprayed-on layer of a stainless [rust-free] hard metal alloy, especially a chromium-nickel steel alloy or chromium-molybdenum steel alloy. This rough very hard layer is covered by a fluoropolymer layer whose antiadhesion, sliding and chemical characteristics determine the characteristics of the surface contacted by the belt. Because of the roughness of the lower layer, the fluoropolymer layer adheres very firmly, the peaks of the hard lower layer protecting the fluoropolymer layer from damage and wear. In the embodiment illustrated in FIGS. 1 and 2, the reversing rail 8 has a T-shaped cross section. It is comprised of a horizontal shank 15 and a vertical shank 16. From FIG. 2 it will be apparent that the upper side of the horizontal shank 15 and at least one of the ends thereof is provided with the coating 11. In a manner not further illustrated, it is also possible to use a reversing rail which is L-shaped in cross section with an upper shank and a forward shank. In this embodiment, the upper side of the upper shank and the front side of the forward shank can be provided with the coating 11. From FIGS. 1 and 3 it will be apparent that in the construction shown in the drawing, the lower belt not only is guided over the reversing - 4 - rail 8 but also around the tensioning stirrup 9 of a tensioning device 10. From FIG. 3, only the surfaces contacted by the lower belt 6 of the stirrup 9 are shown to be equipped with the coating 11. The chromium nickel steel alloy can comprise 20 to 40% by weight chromium and 6 to 20% by weight nickel. The nickel can be wholly or partly replaced by molybdenum. Other stainless [rust-free] hard metal alloys can also be used, e.g. alloys with vanadium. By the use of such alloys with fluoropolymer jackets as the coating 11 of the metal surfaces of the reversing rail 8 and/or the tensioning stirrup 9, it is possible in a simple manner to reduce the wear of the surfaces contacted by the lower belt 6 and of the stretching mechanism 1 of the spinning machine and also of the belt 6 so that there useful lives are increased. - 5 - WE CLAIM: 1. An improved drafting device for a spinning machine, the device comprising an input roller pair (2): an output roller pair (3): an intermediate roller pair (4); an upper belt (5) ; a lower belt (6); a roller (7); and a part (8,9) constituting of a reversing rail (8) and a tensioning stirrup (9) over which said upper and lower belt (5,6) slide, characterized in that a fluropolymer covering is directly applied to one of the metal surfaces of said part (8,9) over which said belts (5,6) slide and a rust-proof sprayed on hard metal alloy being applied on the parts (8,9) over which said belts (5,6) slide. 2. The drafting device as claimed in claim 1, wherein said rust-proof sprayed on hard metal alloy comprises an allay selected from a group comprising a chromium nickel stainless alloy and a chromium molybdenum steel alloy. 3. The drafting device as claimed in claim 1 wherein the surfaces of the reversing rail (8) contacted by the lower belt (6) are coated, 4. The drafting device as claimed in claim 1, wherein said reversing rail (8) having a L-shaped cross section with an upper shank and forward shank, and wherein the upper surface of the upper shank and the front side of the forward shank are coated. 6. 5. The drafting device as claimed in claim 1. wherein said reversing rail (8) has a T-shaped crass section with a horizontal shank (15) and a vertical shank (16), and wherein the upper side of the horizontal shank (15) and at least one of its ends are coated. 6. The drafting device as claimed in claim 1, wherein only the surface of the tensioning stirrup (9) contacted by the lower belt (6) are coated. 7. The drafting device as claimed in any of the preceding claims, wherein said chromium nickel steel alloy comprises a 20 to 40% chromium by weight and & to 20% by weight nickel molybdenum as the hard metal alloy. Dated this 9th day of September 1997 OF L.S.DAVAR & CO APPLICANTS' AGENT 7. The invention relates to an improved drafting device a spinning machine comprising an input roller pair (2); an output roller pair (3); an intermediate roller pair (4); an upper belt (5); a lower belt (6); a roller (7); and a part (8,9) constituting of a reversing rail (8) and a tensioning stirrup (9) over which said upper and lower belt (5,6) slide. A fluropolymer covering is directly applied to one of the metal surfaces of said part (8,9) over which the belts (5,6) slide and a rust-proof sprayed on hard metal alloy being applied on the parts (8,9) over which the belts (5,6) slide.

Documents:

01661-cal-1997-abstract.pdf

01661-cal-1997-claims.pdf

01661-cal-1997-correspondence.pdf

01661-cal-1997-description(complete).pdf

01661-cal-1997-drawings.pdf

01661-cal-1997-form-1.pdf

01661-cal-1997-form-2.pdf

01661-cal-1997-form-3.pdf

01661-cal-1997-form-5.pdf

01661-cal-1997-p.a.pdf

01661-cal-1997-priority document others.pdf

01661-cal-1997-priority document.pdf

1661-cal-1997-granted-abstract.pdf

1661-cal-1997-granted-claims.pdf

1661-cal-1997-granted-correspondence.pdf

1661-cal-1997-granted-description (complete).pdf

1661-cal-1997-granted-drawings.pdf

1661-cal-1997-granted-form 1.pdf

1661-cal-1997-granted-form 2.pdf

1661-cal-1997-granted-form 3.pdf

1661-cal-1997-granted-form 5.pdf

1661-cal-1997-granted-letter patent.pdf

1661-cal-1997-granted-pa.pdf

1661-cal-1997-granted-priority document.pdf

1661-cal-1997-granted-reply to examination report.pdf

1661-cal-1997-granted-specification.pdf

1661-cal-1997-granted-translated copy of priority document.pdf