A ROLLER FOR STRETCHING OR IMPARTING SHRINKAGE TO SHEETING

Abstract: A roller (R1) comprises a surfacial layer (2a) whose dia­ meter progressively diminishes from its middle portion to­ ward the opposite ends, and an arched shaft (1a) supporting the roller (R1) rotatively. Sheeting passed over the roller (R1) can be subjected to stretching or shrinking without causing a permanent set therein.

Description: The invention relates to a roller for stretching or imparting shrinkage to sheeting. To stretch or impart shrinkages to metal or cloth sheeting, a previously proposed method has been to use a barrel-shaped roller supported by a straight shaft. The barrel-shape roller has a cross-section of symmetrically arched profiles like a beer barrel. Such barrel-shaped rollers are useful for carrying a thin sheet thereon without the possibility of slipping. When a sheet runs on the arched surfaces of the roller the contact therebetween is minimized so as not to produce a permanent set on the sheet. It has also been proposed to use two barrel-shaped rollers together in a pair as a pinch roller unit. When tapes of different thicknesses are passed side by side therethrough with thin tapes inside and thick tapes outside, they are fed out at a constant rate irrespective of the differences in thickness. This requires that a number of winders equal to the number of tapes and rotating at different speeds are used. A roller unit has also been proposed comprising an arched roller having a constant cross-sectional area throughout its length and carried on an arched shaft (see GB-A-1346196). When sheet material is passed over this roller a force acts on the sheet crosswise, that is to say in a direction axially of the shaft. When the sheet runs toward the peripheral edges of the roller it is subjected to an outward force, whereas when the sheet runs toward the centre it is subjected to an inward force. In the former case the sheet is outwardly extended, and in the latter case it is shrunk. This can be effective to remove shrinkage from, i . e . to stretch, or to impart shrinkage to a metal sheet. However, the previously proposed arched roller must be provided with means for keeping the sheet material on the roller, otherwise it would slip off. A barrel-shaped roller is thus required in the unit to retain the sheet material on the arched roller. Patent Specification DE-A 2 937 610 discloses a roller formed by an outer flexible sleeve, end discs, a central rod and a pair of tubular members slidable on the ends of the central rod and having collars at their inner ends coupled by fixed length linkages to projections from the inner face of the flexible sleeve at the mid length position thereof. By moving the tubular members selectively axially inwardly and outwardly the collars and linkages, in a parallelogram relation, increase or decrease the diameter of the roller at positions intermediate the ends of the roller compared with the diameter at the ends of the roller set by the discs. Patent Specification FR-A-892 194 discloses a roller with a bent axle and, on each side of the bend in the axle, a plurality of discs which increase in diameter in directions away from the bend and support an outer sleeve of rubber with a helical reinforcement. According to the invention there is provided a roller for stretching or imparting shrinkage to sheeting and having an arched shaft characterised by a surfacial layer rotatably supported on the arched shaft and having an outer diameter which progressively reduces from its middle portion toward its opposite ends. Such a roller can be capable of allowing sheet material to run at a constant speed thereon with stability and without being liable to a permanent set. The invention is diagrammatically illustrated by way of example in the accompanying drawings, in which:- Figures 1A and 1B are a side view and a cross-sectional view respectively showing one embodiment of a roller according to the invention; Figures 2A and 2B are a side view and a front view respectively showing a second embodiment of a roller according to the invention; Figure 3 is a side view showing a third embodiment of a roller according to the invention; Figures 4A and 4B are a perspective view and an end view showing embodiments of a shaft of a roller according to the invention; Figures 4C and 4D are perspective views showing further embodiments of a core of a roller according to the invention; Figure 5 is a diagrammatic side view showing a pair of rollers according to another embodiment of the invention; Figures 6A and 6B are perspective views showing a roller according to the invention used for stretching or shrinking sheeting; and Figures 7A to 7F are schematic views exemplifying various phases in which paired rollers according to the invention are applied to a sheeting passing therebetween. Referring to the drawings and firstly to Figures 1A and 1B, a roller R1 includes an arched shaft 1 a and a surfacial layer in the form of a rubber lining 2 a . The rubber lining 2 a is rotatable with respect to the arched shaft 1 a by means of a plurality of bearings 3 with casings 4 housing the bearings 3. The casings 4 and the rubber lining 2 a are fastened to each other in known manner. The casings 4 are separated by ring-shaped partitions 5 having equal thickness. The rubber lining 2 a is of crown form, that is to say convex whereby the diameter of the rubber lining 2 a progressively increases toward its middle portion. When the arched shaft 1 a is supported in such a manner as to cause it to arch downward as shown in Figure 1B, the upper surface 21 of the rubber lining 2 a becomes straight or horizontal. When the rubber lining 2 a is rotated with respect to the shaft 1 a a tensile force is exerted on the convex side thereof whereas a compressive force is exerted on the straight side thereof. The degree of expansion and shrinkage depend on the radius of curvature of the shaft 1 a . A sleeve 6 is provided as a spacer between the shaft 1 a and the bearings 3, and an end flange 7 is engaged in the end portion of the rubber lining 2 a , the end flange 7 being fixed thereto by means of a stop flange 8. A set sleeve 9 projects into the stop flange 8. Referring to Figure 2A, a roller R2 includes a lining 2 b which is arched as a whole, that is to say it has a concave upper surface 22, unlike the roller R1 of Figures 1A and 1B which has the straight upper surface 21. The upper surface 22 is concave by a distance d with respect to the straight surface 21 of the roller R1, the straight surface being shown by a chain dotted line in Figure 2A. In this way the lining 2 b has a shallowly arched upper surface 22 and a deeply arched lower surface 24 with straight lateral sides 23 extending therebetween as shown in Figure 2B. Herein "deeply" and "shallowly" are relative with respect to each other. Figure 3 shows a further modified roller R3 including a lining 2 c which has an upwardly arched upper surface 25 although the degree of arching is smaller than that of the lower arched surface. The rollers R2 and R3 have the same internal structure as that of the roller R1. These rollers are made in the following manner:- A roller is prepared which has an initially thick surfacial layer made of soft material, such as rubber, plastics, ceramic or mild metal. The roller is carried on an arched shaft, when necessary, through a core 30 or 40 shown in Figures 4C or 4D or any other means which enables the roller to rotate thereon. The arched shaft 1 a is fixed with its arched portion downward. Then a cutting blade is applied to the surfacial layer as the roller is rotated so as to shape the desired profile of the roller, that is with a top surface which is horizontal, arched, or convex. In common with all the profiles the roller is cut so that the diameter thereof diminishes progressively from the middle toward the end portions. In this way the profile of the roller is shaped as shown in Figure 2A, 1A or 3 as desired. The important thing is that the arched roller is fixed, with its arched portion downward in a vertical plane in which the shaft lies. The shaft is only arched to an extent which allows the roller to rotate thereon. In general the curvature is 9 mm to 400 m, preferably 18 mm to 200 m, more preferably 36 mm to 100 m. There is no limitation on the length and diameter of the shaft. In general the length can be 8 mm to 20 m, preferably 12 mm to 10 m, more preferably 15 mm to 6 m, and the diameter can be 1 mm to 5 m, preferably 2 mm to 2 m, more preferably 5 mm to 1 m. The cross-sectional shape and dimension of the shaft can vary widely i . e . with radial projections (Figure 4A) or other forms. The shaft shown in Figure 4A comprises several plates 11 radially extending from a bar 1 b , and the shaft shown in Figure 4B comprises the bar 1 b and plates 11 with a surrounding cylinder 12. To reduce weight, increase strength or secure rapid cooling, various shapes of the shaft can be appropriately selected. The progressively diminishing diameter of the roller toward its opposite ends, enables sheeting to run in face-to-face contact with the roller. The peripheral surfaces of the roller take one of the above-mentioned three profiles as shown in Figures 1A to 3, that is, one state in which one surface of the roller has a larger radius of curvature than that of the opposite peripheral surface (Figure 2A), another state in which one surface of the roller is straight (Figure 1A), and a third state in which one surface of the roller is concave in the middle whereas the opposite surface is convex (Figure 2A). In this specification the terms convex, concave arched or arching and straight mean that the shapes of the shaft and roller appear in the respective forms in a vertical plane on which they are projected from the side. As a result of such profiles sheeting passing over the roller is subjected to extension in length at one side and reduction at the opposite side. To multiply the effects of the roller two rollers can be used as a pair as shown in Figure 5. The surfacial layer of each roller is made of soft elastic material, such as rubber, Ni-Ti alloy, Cu-Zn-Al alloy, ceramic. A rubber surfacial layer is effective to prevent sheeting from slipping thereon, and a metal or ceramic surfacial layer is advantageous for heatproof qualities and for avoiding dust adhering to the sheeting. The roller can be provided with grooves or ridges on its surface to allow water to drain from the roller surface, or to prevent sheeting from slipping on the roller. The size of the roller is chosen to suit the sheeting which is to be processed. In Figure 2A the distance d is preferably 0.1 mm to 10 cm. In the embodiment shown in Figure 1A the shaft 1 a is made of steel (55C), measuring 1620 mm in length, 45 mm in diameter, and having a radius of curvature of 25717.7 mm. The roller 2 a is 1200 mm in length, 154 mm in diameter at its middle portion, and 120 mm in diameter at its end portions, the surfacial layer being 8 to 15 mm in thickness. For example the hardness of the lining rubber can be 35 (shore) for use with cloth sheeting, and 80 for use with iron sheeting. In the arrangement shown in Figures 2A and 3 using the same roller as that mentioned above d is about 0.5 mm. The bearings 3 are those commercially available. A bellows-type cylinder 30 is shown in Figure 4C whereas a cylinder 40 shown in Figure 4D is provided with spiral grooves 41 and 42, the groove 41 progressing in a clockwise direction but the groove 42 progressing in a counter-clockwise direction so that the force equally diverses in the opposite directions along the length of the cylindrical body, thereby enabling the roller to withstand a large load. This spirally grooved roller can be effectively used when the roller is rotated at a high speed or when heavy sheeting is passed thereon. A plurality of the rollers, especially of the rollers R2 shown in Figure 2A, can be used when the sheet materials are to be temporarily stopped thereon, or when a large load is applied to the sheeting so as to form a corrugated surface. One advantage can be to prevent the sheeting from undergoing a one-sided force thereby avoiding a permanent set in the sheeting. It is easy to adjust the contact between the roller and the sheeting passing thereon. The roller shown in Figure 1A ("straight type") is especially suitable for a pinch roller unit shown in Figure 5, which is used when a rolled metal plate is cut to a desired length. Two of the rollers R1 are arranged side by side with their straight sides 21 abutting. Under this arrangement the pressure of the rollers upon the sheeting is equally distributed along the length of the roller even when sheeting of various thicknesses is passed between the two rollers. The roller dispatches the sheeting at various rates in accordance with the circumference of each part of the rollers. The sheeting is wound on a reel under a constant tension. Sheetings of various thicknesses can be neatly wound on reels even when the reels are driven at the same speed from the same source of electricity. Figure 5 shows gears 50 which impart the same torque equally to the two rollers R1. Gears 51 can be used to amplify the torques acting on the rollers. The gears 51 are provided at both end portions of either of the rollers R1. The shafts 1 a are supported on supports 60 the internal structure of which is shown in Figure 1B. The gears 50 and 51 are fixed to the stop flange 8. The shafts 1 a are mounted on the supports 60 through angular adjusting devices 62 each of which includes a ball 63 fixed to the shaft 1 a , a casing 64 rotatably accommodating the ball 63, a screw 65 adjusting the ball 63 and a hosuing 66. The rollers are used as a tenter i . e . for stretching sheeting, or as a device for imparting shrinkages to sheeting, such as cloth, metal foil or paper. Figure 6A shows a relationship between a roller R and sheeting S when the roller R is used as a tenter. The roller R is mounted on its shaft in such a manner that the sheeting passes from the concave side of the roller to the convex side as indicated by the arrow thereon. The sheeting running thereon in the direction A is subjected to an extending force along its width. Figure 6B shows the relationship therebetween when the roller R is used as a shrinking device. The roller R is mounted on its shaft in such a manner that the sheeting passes from the convex side to the concave side. Under this arrangement the sheeting is subjected to an inward force as it passes over the roller R in the direction B. As will be apparent from the examples of Figures 6A and 6B, it can be important for the sheeting to be placed on the straight surface of the roller situated between the convex side and the concave side, otherwise a permanent set could be left in the sheeting. This also secures a safe high-speed passage of the sheeting on the roller. When two rollers are used in a pair as a pinch roller unit, it is more effective to prevent the sheeting from slipping on the rollers, and causes stronger forces to act widthwise on the sheeting. When two rollers are used in pair, the types used can be selected from those mentioned above. Figure 7A shows a state in which two rollers are slightly spaced, whereas Figure 7B shows a state in which flat portions of each roller meet at position RP. The latter case is advantageous in regulating the widths of sheeting to be passed through the rollers, thereby eliminating the need to use an extra roller or any other means for regulating the widths of the sheeting. Figure 7C shows an advantageous example for stretching sheeting. The rollers are arranged in such a manner that the two rollers flatly meet near an entrance position. Under this arrangement the sheeting is subjected to equally diverged and amplified forces as shown in Figure 7D. Figure 7E shows a state in which the sheeting is subjected to inward forces, thereby causing the sheeting to shrink as shown in Figure 7F. Advantageously the intensified inward forces are applied to the sheeting. If desired the roller or rollers can be covered with a soft material, such as cloth or sponge.

Claims: A roller (R, R1, R2, R3) for stretching or imparting shrinkage to sheeting (S) and having an arched shaft (1 a , 1 b , 1 c ) characterised by a surfacial layer (2 a , 2 b , 2 c ) rotatably supported on the arched shaft (1 a , 1 b , 1 c ) and having an outer diameter which progressively reduces from its middle portion toward its opposite ends. A roller according to claim 1, wherein the roller has a straight peripheral surface side (21) and a convex peripheral side surface (24) facing in opposite directions with respect to the axis thereof. A roller according to claim 1, wherein the roller has a concave peripheral side surface (22) and a convex peripheral side surface (24) facing in opposite directions with respect to the axis thereof. A roller according to claim 1, wherein the roller has a convex peripheral side surface (25) and a convex peripheral side surface (24) facing in opposite directions with respect to the axis thereof. A roller according to any one of claims 1 to 4, wherein the surfacial layer (2 a , 2 b , 2 c ) is made of a soft, elastic material such as rubber. A roller according to any one of claims 1 to 4, wherein the surfacial layer is formed of metal. A roller according to any one of claims 1 to 4, wherein the surfacial layer is formed of ceramic. A roller according to any one of claims 1 to 7, wherein the roller includes a cylinder (40) having grooves (41, 42) therein.

Inventors: YANO, AKECHI
Applicants: YANO, AKECHI
Application year: 1986
Main classification: D06C3
IPC codes: D06C3