METHOD AND DEVICE FOR ROTATING ROLLS

Abstract: The invention relates to a method and device for rotating rotational bodies (1), such as rolls, along their longitudinal axis (X) by means of motion of a trough-like surface (2) guiding and supporting said body (1). In the invention, the axis of rotation of the body (1) moving on said surface is guided by means of the profile (2a, 7a, 7b) of the surface (2) to a new position to eliminate the swinging of the body (1). In an embodiment, said profile (2a, 7a, 7b) comprises a straight section (2a) and a section (7a, 7b) which is arranged at least on the other side of the same, and which comprises a surface that rises outwards. The diagonal surface can be arranged as a separately attachable part. By means of the invention, the swinging of the conical roll (1) is prevented during rotation.

Description: Method and device for rotating rolls The invention relates to a method according to the preamble of claim 1 for rotating rolls. The invention also relates to a device according to the preamble of claim 5 for rotating rolls. Furthermore, the invention relates to an arrangement for a rotating device according to the preamble of claim 8. As is well known, for wrapping of cylindrical pieces, such as paper rolls, wrapping devices known as such are used, which devices perform the wrapping by means of a wrapping film, typically a transparent stretch film or a thin plastic film. One known wrapping device is disclosed in the patent publication US 5,086,610. The wrap is guided around the mantle of the piece and at the same time the piece is rotated around its central line i.e. its longitudinal axis. At the final stage of the wrapping, the film is cut, and the end of the film is welded on the other films by means of hot sealing. As to the techniques involved in cutting, sealing and feeding of the film, reference is made e.g. to the patent publication US 5,092,109. During the wrapping the wrapping film is stretched in a controlled manner as presented for example in the patent publication US 5,054,263. The wrap can be guided around the mantle and the ends of the piece in such a way that the piece is rotated both around the longitudinal axis and a typically vertical axis which is transverse to the longitudinal axis. An example of such a device is disclosed in the patent publication US 5,487,255. Alternatively, the carriage feeding the wrap can rotate around an axis vertical with respect to the piece, wherein the piece is typically only rotated around its horizontal central line. When rolls are manipulated, for example packed in a wrap or transferred to a new working station, they have to be rotated around their longitudinal axis. Although the rolls, such as paper rolls, are nominally cylindrical, the softness of the material in the roll, the directional errors in the wrapping, variations in humidity and other factors effect the actual shape to be conical. The conical shape results in that the presently used rotating devices deflect the direction of the longitudinal axis of the roll during the rotation. This, in turn, causes errors in other work stages, such as packing effected by means of wrapping. The problem occurs especially in devices according to the patent publication US 5,487,255, in which conical rolls are rotated in a recess formed in a continuous track. The track is formed around two reels which are rotated, and the aim is to rotate the roll around its longitudinal axis substantially in its position by means of the moving track. Heretofore, attempts have been made to solve said problem with separate blocking rolls and wheels. These, however, cause dents on the roll which impair the quality of the roll, and they are also expensive and cumbersome. It is an aim of the invention to eliminate this drawback and to attain a method and a device, in which, without impairing the quality of the roll, the axle of the roll does not tend to swing during rotation even though the roll has the shape of a cone. This eliminates the errors caused by the swinging in the manipulation of the rolls. Said problem occurs especially in soft rolls. The best soloution for rotating these rolls is a slat chain trough in which the roll is rotating. According to the invention, the act of rotating the roll so that the roll does not swing can be attained by shaping the surface of the trough in such a way that the slope angle of the profile of the surface changes in the direction of the axis of the roll. The roll is positioned in such a location during the rotation that the axle of the roll is parallel to the axis of rotation, and thus, the roll does not tend to swing. More precicely, the method according to the invention is characterized in what will be presented in the characterizing part of claim 1. The device according to the invention is characterized in what will be presented in the characterizing part of claim 5. The arrangement for a rotating device according to the invention is characterized in what will be presented in the characterizing part of claim 8. In the following, the invention will be described in more detail by means of a preferred embodiment and with reference to the appended drawings, in which Fig. 1 shows a side view of a prior art solution for rotating a roll, Fig. 2 shows a roll according to Fig. 1 seen from the direction of the smaller end, Fig. 3 shows a side-view of a preferred embodiment of the invention, and Fig. 4 shows the roll according to Fig. 3 at the location of the smaller end, seen in the direction of said end. For the sake of clarity, Fig. 1 only shows a cross-section of the shape of the profile on the upper surface of a track 2 at the point where the roll 1 rests. Similarly, for the sake of clarity, Fig. 3 shows only a cross-section of the profile shape of the upper surface of the track 2 at the point where the roll rests. In Figs. 1 and 2, the roll 1 to be rotated is located on top of the track 2. The track 2 is moving when the reels 3a and 3b are rotated. When the track moves, the roll 1 rotates in a trough 4 formed by the track. Even though the roll 1 is nominally a cylinder, it actually has the shape of a cone. The larger end is marked with the reference numeral 5 and the smaller end with the reference numeral 6. Because the roll 1 consists of one piece, the rotational angles of the ends 5 and 6 are equal in size during the rotation, and since the diameter of the end 5 is larger than the diameter of the end 6, the peripheral speed of the perimeter of the end 5 is higher than the peripheral speed of the end 6. The propagation speed of the track 2 is, however, the same at both ends. Therefore both ends 5 and 6 cannot follow the track 2 in accordance with the travel direction of the track 2. The peripheral speed of the larger end 5 is higher than the speed of the track 2, and thus, the end 5 moves against the travel direction of the track. The speed of the smaller end 6 is not sufficient, and the track 2 carries it along. Therefore, the longitudinal axis of the roll 1 swings in the trough 4, and the roll 1 is set in a diagonal position in the trough 4 at such a point that the slipping of the roll 1 finally prevents it from swinging further. With reference to Fig. 1 , the longitudinal axis of the conical roll 1 is marked with a straight line X which at the same time conjoins the central line of the roll 1. It can be seen that when the roll 1 is positioned on the track 2, the central line X is positioned in a diagonal position with respect to the surface of the track 2 supporting the roll 1. With reference to Fig. 2, the reels 3a and 3b are rotated clockwise, wherein the upper surface of the continuous track 2 moves substantially to the right at the same time causing the rotation of the roll 1 counterclockwise. Because of the differences in speed, when the roll 1 rotates, the end 6 tends to follow the track to the right, and the end 5 tends to move to the left. Thus, the central line X also tends to turn. Correspondingly, when the rolls 3a and 3b are rotated counterclockwise, directions of motion of the track 2 and the roll 1 are opposite to the directions marked in Fig. 2. In the rotation of reels 3a and 3b it is possible to apply devices, such as motors known per se, which can be applied in a manner known as such by anyone skilled in the art. The reels 3a and 3b and their tracks 2 can be arranged in a supporting frame known as such, which can also comprise actuator means known per se, such as a pressurized medium operated cylinder for tilting the track 2 to transfer and receive the roll 1. Figs. 3 and 4 show an embodiment according to the invention in which the prior art swinging of the roll 1 is eliminated. The roll 1 to be rotated, the track 2 and the reels 3a and 3b are similar to those shown in Figs. 1 and 2. The profile of the track 2 in the direction of the longitudinal axis X of the roll 1 is, however, changed by means of diagonal surfaces 7a and 7b located at the edges of the track 2, which surfaces can be formed of wedge parts attached on the surface of the track 2. The surfaces 7a and 7b function in a manner described hereinbelow. When the track 2 starts to move, and the roll 1 starts to rotate, it swings in a similar manner as described in connection with Figs. 1 and 2. Because of the swinging, the roll 1 also moves in the direction of its longitudinal axis X, wherein the smaller end 6 climbs on top of the surface 7b. The roll 1 climbs so far on top of the surface 7b that the longitudinal axis X of the roll 1 is parallel to the trough 4 again, and the swinging is eliminated. Thereafter the roll 1 rotates in such a manner that its longitudinal axis X is parallel to the trough 4, wherein the necessary work stages, such as the wrapping of the roll into a packing film during the rotation, proceed without problems with a good output. With reference to Fig. 4, the reels 3a and 3b are rotated clockwise, wherein the upper surface of the continuous track 2 moves substantially to the right, at the same time causing the rotation of the roll 1 counterclockwise. Correspondingly, when the reels 3a and 3b are rotated counterclockwise, the directions of motion of the track 2 and the roll 1 are opposite to the directions marked in Fig. 2. In different situations, the roll 1 , however, moves in the direction of its longitudinal axis X and climbs on the surface 7b, which is on the side of the smaller end 6. Thus, the central line X conjoins the axis of rotation of the roll 1 , and the swinging is prevented. The method functions in a corresponding manner in a situation where the end 5 has a larger diameter than the end 6. A corresponding situation occurs when the roll 1 is positioned in such a way in the situation of Fig. 3 that the end 6 is closer to the surface 7a on the right side. Thus, when the roll 1 is rotated, it climbs on the surface 7a. It is obvious that if the roll 1 is always positioned in such a way on the track that the smaller end 6 is on the left, only the surface 7b is necessary. However, the tapering direction of the rolls 1 always varies as a result of the presented problems, and thus the track 2 is advantageously provided with both surfaces 7a and 7b for manipulation of different rolls 1. The shape of the side line of the roll 1 , i.e. the nominal profile of the mantle 1a does not have to be straight. Thus, the general shape of the rotating profile i.e. the shape of the supporting surface 2a of the track 2 in the longitudinal direction X of the roll, corresponds to the nominal profile of the roll 1 , but deviates from the same in a manner described hereinbelow. When the actual profile of the roll 1 deviates from the nominal profile, the roll 1 is transferred in the direction of its londitudinal axis X. The rotating profile is selected in such a manner that in this transferred position, the axis of rotation of the roll 1 is again positioned in the direction of the longitudinal axis X of the roll 1 , wherein the swinging is ceased. In the embodiment of Fig. 3, the profile of the surface of the track 2 guiding and supporting the rotating piece 1 is straight in its central section, and both of its ends are provided with a diagonal surface 7a and 7b which rises outwards. Thus, the nominal shape of the piece 1 is a cylinder. According to a preferred embodiment of the invention the guiding and supporting surface 2 is a chain conveyor. According to another preferred embodiment, the invention is applied in a device in which the roll 1 is wrapped in a package during the rotation. When the cylindrical straight roll is positioned on the track 2 partly on top of the surface 7a or 7b, it moves in the direction of its longitudinal axis when rotated and is centered into a new position on top of the section 2a. Thus, according to the invention, the longitudinal axis of the roll is positioned in parallel with the trough 4 and the swinging is eliminated, and thus, the invention is also suitable for manipulation of other rolls. The invention is not restricted solely to the above-presented preferred embodiment of the invention, but it can vary within the scope of the presented claims. In addition to the presented wrapping devices, the invention is suitable for other devices and methods in processing of rolls, in which they have to be rotated around their longitudinal axis, as was stated hereinabove. The invention can be applied in connection with the present trough-like rotating devices by providing them with diagonal surfaces, as was presented above.

Claims: Claims: 1. Method for rotating rotational bodies (1), such as rolls, along their longitudinal axis (X) by means of motion of a trough-like surface (2) guiding and supporting said body (1), characterized in that the axis of rotation of the body (1) moving on said surface is guided by means of the profile (2a, 7a, 7b) of the surface (2) to a new position to eliminate the swinging of the body (1). 2. Method according to claim 1 , characterized in that the body (1) is guided by means of the profile (2a, 7a, 7b) which comprises a straight section (2a) and a diagonal surface (7a, 7b) that rises outwards. 3. Method according to claim 1 or 2, characterized in that during the rotation, the end (6) which has a smaller diameter in the conical body (1), moving in the direction of its longitudinal axis (X), is guided on the rising diagonal surface (7a, 7b). 4. Method according to any of the claims 1 to 3, characterized in that the longitudinal axis (X) of said body (1) is guided in parallel with the trough (4) of said surface (2). 5. Device for rotating rotational bodies (1), such as rolls, around their longitudinal axis (X) by means of motion of a trough-like surface (2) guiding and supporting said body (1), characterized in that the profile (2a, 7a, 7b) of said surface (2) is arranged to guide the axis of rotation of the body (1) moving on the surface (2) to a new position to eliminate the swinging of the body (1). 6. Device according to claim 5, characterized in that said profile (2a, 7a, 7b) comprises a straight section (2a) and a diagonal surface (7a, 7b) which is arranged at least on the other side of the same and which rises upwards. 7. Device according to claim 5 or 6, characterized in that said troughlike surface (2) is a slat conveyor which hangs between the reels (3a, 3b) and forms a trough (4). 8. Arrangement for a rotating device, which device is intended for rotating rotational bodies (1), such as rolls, around their longitudinal axis (X) by means of motion of a trough-like surface (2) guiding and supporting said body (1 ), characterized in that the arrangement comprises a profile part (7a, 7b) to be arranged on said surface (2), to guide the axis of rotation of the body (1) moving on the surface (2) into a new position to eliminate the swinging of the body (1). 9. Arrangement according to claim 8, characterized in that said profile part (7a, 7b) has a conical shape. 10. Arrangement according to claim 8 or 9, characterized in that said profile part (7a, 7b) is arranged for changing the straight profile of said surface (2) into a diagonal surface which rises outwards from its other end.

Inventors: MAEKI-RAHKOLA JARI, METSAENRANTA JOUKO, MAEKI-RAHKOLA, JARI, METSAENRANTA, JOUKO
Applicants: MAEKI RAHKOLA JARI, METSAENRANTA JOUKO, PESMEL OY, MAEKI-RAHKOLA, JARI, METSAENRANTA, JOUKO
Application year: 1999
Main classification: B65H54
IPC codes: B65B25