Applicator beam in a size press

Abstract: The invention concerns an applicator beam in a size press comprising a nip (N) formed by press rolls (12, 14), through which nip the paper or board web (W) is passed. The press rolls (12,14) are provided with coating devices (23) for the spreading of films of coating agent onto the faces of said rolls. The coating devices (23) are mounted on applicator beams (20) placed in the transverse direction of the machine, which applicator beams are linked pivotally on the frame (11) of the size press or on the loading arms (16) of the displaceable roll (14) by means of a pivot shaft (21) transverse to the machine direction and which applicator beams are provided with pivot cylinders (22), by whose means the applicator beams (20) can be pivoted between a closed position, i.e. the operating position, and an opened position, i.e. the service position. According to the invention, in its cross section taken in a vertical plane in the longitudinal direction of the machine, the applicator beam (20) is shaped so that at least the wall (26) of the applicator beam (20) that is facing away from the corresponding press roll (14) is curved. Moreover, the pivot shaft (21) of the applicator beam (20) is arranged so that, when the applicator beam (20) is pivoted around its pivot shaft (21), the distance (a) from the curved outer face (26) of the applicator beam to the other constructions of the machine placed close to the applicator beam (20), such as the tending bridge (30), remains substantially unchanged.

Description: The invention concerns a size press comprising a nip formed by press rolls, through which nip the paper or board web is passed and in which size press the first press roll is mounted by means of bearings permanently on the frame of the size press, whereas the other press roll is mounted on the frame of the size press by means of its bearings as displaceable by the intermediate of loading arms or equivalent, and in which size press the press rolls are provided with coating devices for the spreading of films of coating agent onto the faces of said rolls, said coating devices being mounted on applicator beams placed in the longitudinal direction of the rolls, which applicator beams are linked pivotally on the frame of the size press or on the loading arms of the displaceable roll by means of a pivot shaft longitudinal to the beam and which applicator beams are provided with pivot cylinders, by whose means the applicator beams can be pivoted between a closed position, i.e. the operating position, and an opened position, i.e. the service position. The construction of a prior-art size press is illustrated in Fig. A1. In Fig. A1, the size press is denoted generally with the reference numeral 100. The press rolls 112,114 in the size press 100 form a nip N with each other, the paper or board web W being passed through said nip. The web W is guided into the nip N over the guide roll 119. The bearing 113 of the first press roll 112 is mounted on the frame 111 of the size press permanently, and, correspondingly, the bearing 115 of the second press roll 114 is mounted on the loading arm 116, which is fitted pivotally, by means of the articulated joint 118, on the frame 111 of the size press. Between the frame 111 and the loading arm 116, loading cylinders 117 are fitted, by whose means the nip N can be opened and closed and by whose means the loading pressure between the rolls 112,114, i.e. the nip pressure, can be adjusted to the desired level. Each roll 112,114 in the size press 100 is provided with a coating device 123,123a of its own, by whose means a film of coating agent is applied onto the face of the respective roll 112,114, said film being transferred onto the web W in the roll nip N. The coating devices 123,123a are, each of them, mounted on an applicator beam 120,120a transverse to the machine direction. In the prior-art solution shown in Fig. A1, the applicator beam 120a of the first press roll 112 is mounted pivotally, by means of the articulated joint 121a, on the frame 111 of the size press, and further, between said applicator beam 120a and the frame 111 of the size press, pivot cylinders 122a are fitted, by whose means the applicator beam 120a can be opened and closed in relation to the roll 112. In a corresponding way, the coating device 123 of the second press roll 114 is mounted on an applicator beam 120 transverse to the machine direction, which beam is mounted pivotally, by means of the articulated joint 121, on the loading arm 116. Between the applicator beam 120 and the loading arm 116, pivot cylinders 122 are fitted, by whose means the applicator beam 120 can be opened and closed in relation to the second press roll 114. In the prior-art size press 100 described above, one of the major drawbacks has been the space required by the applicator beam 120 during pivoting of the beam between the operating position and the service position, i.e. the opened position. In Fig. A1, the applicator beam of the second press roll 114 is illustrated in the service position by means of dashed lines and as denoted with the reference numeral 120'. For servicing of the applicator beam 120, a tending bridge 130 is provided on the machine, from which bridge the service operator 132 standing on the bridge can carry out the operations necessary on the applicator beam 120. As can be seen from Fig. A1, when the applicator beam 120 is in the operating position, there is a considerably long distance between the tending bridge 130 and the applicator beam 120, for which reason the tending bridge 130 is provided with a handrail 131 in order that the service operator 132 could not even accidentally fall into the space between the tending bridge 130 and the applicator beam 120. It has been necessary to allow said space between the applicator beam 120 and the tending bridge 130 to remain so large, because, when the applicator beam 120 is pivoted to the service position 120' around the articulated joint 121, the applicator beam 120 is shifted a great deal closer to the tending bridge 130. This is why, and since, during pivoting, the applicator beam 120 and the tending bridge 130 form a "closing nip", on account of working safety in relation to the applicator beam 120, also when in the service position, and in relation to the tending bridge 130, a safety clearance b must be allowed, which is, at the minimum, of an order of 120 mm. By means of said safety clearance b, the objective has been to avoid the risk of squeezing when the applicator beam 120 is being opened. This is why it has been necessary to dimension the distance between the applicator beam 120 and the tending bridge 130 excessively large in view of the user, i.e. the service operator 132. From the tending bridge 130, access to the actuating members of the applicator beam 120 is not easy enough. The object of the present invention is to provide a solution by whose means the drawbacks described above and related to the prior art are avoided. In view of achieving this, the invention is characterized in that, in its cross section taken in a vertical plane in the transverse direction of the the applicator beam this beam is shaped so that at least its wall that is facing away from the corresponding press roll is curved, the distance from the curved outer face of the applicator beam to the pivot shaft being substantially equally large at every point, such that, when the applicator beam is pivoted around its pivot shaft, the distance from the curved outer face of the applicator beam to the other constructions of the press or constructions related thereto and placed close to the applicator beam, such as the tending bridge, remains substantially unchanged. By means of the invention, a number of remarkable advantages are obtained over the prior art, in particular in consideration of the maintenance of the applicator beam. First, the outer face of the applicator beam has been shaped, and the pivot point of the applicator beam has been chosen, so that, when the beam is pivoted between the operating position and the service position, the distance between the applicator beam and the structures outside the machine, such as the tending bridge, is substantially not changed. Preferably, the cross-sectional shape of the applicator beam is shaped as an arc of a circle, and the pivot shaft is fitted substantially in the area of the centre point of the arc of a circle, in which case, when the applicator beam is pivoted, for example between the tending bridge and the applicator beam, no "closing nip" is formed, which is the case in prior-art solutions. This is why the tending bridge can be placed considerably closer to the applicator beam than in prior art. This, of course, improves the servicing possibilities of the applicator beam substantially. Since, in the solution of the invention, the space between the applicator beam and the tending bridge can be dimensioned very little, the tending bridge does not have to be provided with handrails. This also facilitates the maintenance of the applicator beam. A further advantage of the solution in accordance with the invention is provided therein that the centre of gravity of the applicator beam is placed very close to the pivot shaft of the beam, in which case the own weight of the applicator beam has no substantial effect on the size of the pivot cylinder. The further advantages and characteristic features of the invention come out from the following detailed description of the invention. In the following, the invention will be described by way of example with reference to the figures in the accompanying drawing. Figure 1 is a fully schematic partial side view of a size press in which an applicator beam in accordance with the invention is fitted. Figure 2 is a schematic illustration of an embodiment alternative to the applicator beam illustrated in Fig. 1. In Fig. 1, the size press is denoted generally with the reference numeral 10. The press rolls 12,14 of the size press 10 form a nip N with each other, the paper or board web W being passed through said nip. The bearing 13 of the first press roll 12 is mounted on the frame 11 of the size press permanently, and, in a corresponding way, the bearing 15 of the second press roll 14 is mounted on a loading arm 16, which is fitted on the frame 11 of the size press pivotally by means of an articulated joint 18. Between the frame 11 and the loading arm 16, loading cylinders 17 are fitted, by whose means the nip N can be opened and closed and by whose means the loading pressure between the rolls 12,13, i.e. the nip pressure, can be adjusted to the desired level. Each roll 12,14 in the size press 10 is provided with a coating device of its own, but in Fig. 1, only the coating device 23 of one of the rolls 14 in the size press is shown. By means of said coating devices 23, films of coating agent are applied to the faces of the rolls 12,14, which films are transferred to the web W in the roll nip N. The coating device 23 is mounted on an applicator beam 20 transverse to the machine direction. In the solution shown in Fig. 1, holders 24 have been mounted on the loading arm 16, on which holders the applicator beam 20 is mounted pivotally by means of the articulated joint 21. Underneath the applicator beam 20, a collecting trough 25 separate from the applicator beam has been arranged for the coating agent, which trough communicates with the recirculation of the coating agent. The applicator beam 20 in accordance with the invention is shaped as of curved cross-sectional shape as shown in Fig. 1, preferably shaped as an arc of a circle. In Fig. 1, the curved outer face of the applicator beam 20 is denoted with the reference numeral 26, and the radius of the curve with the reference R. The pivot shaft 21 is fitted in the area of the centre point of the arc of a circle, preferably exactly at the centre point, as a result of which the distance a between the applicator beam 20 and the tending bridge 30 does not change when the applicator beam 20 is pivoted. In such a case, the tending bridge 30 can be placed very close to the applicator beam 20, because there is no risk of squeezing between the applicator beam 20 and the tending bridge 30. As is shown in Fig. 1, the handrail of the tending bridge, which is used in connection with conventional solutions, can be omitted, and the service operator 32 has easy access to the actuating members of the applicator beam 20. Owing to the cross-sectional shape in accordance with the invention of the applicator beam 20, the centre of gravity of the applicator beam 20 is placed very close to the pivot shaft 21, in which case the own weight of the applicator beam 20 does not affect the dimensioning of the pivot cylinders 22. Further, in a solution in accordance with the invention, the construction and installation of the tending bridge 30 can be fixed, unlike the prior-art solutions, which often require a displaceable tending bridge. Fig. 2 shows a solution alternative to the construction shown in Fig. 1. The illustration in Fig. 2 has been simplified from Fig. 1 further so that all parts not included in the scope of the invention have been omitted in the illustration in Fig. 2. In Fig. 2, the size press is denoted generally with the reference numeral 40. The press roll 44, which corresponds to the second press roll 14 in the illustration in Fig. 1, is mounted by means of bearings 45 on the loading arm 46. On the loading arm 46, holders 54 have been fitted, on which the applicator beam 50 is mounted by means of a pivot shaft 51. In Fig. 2, the coating device is denoted fully schematically with the reference numeral 53, the coating-agent collecting trough with the reference numeral 55, and the pivot cylinders of the applicator beam 50 with the reference numeral 52. The embodiment shown in Fig. 2 differs from the construction shown in Fig. 1 in the respect that, in the embodiment of Fig. 2, the applicator beam 50 has been formed as of substantially fully circular cross-sectional shape. This provides the additional advantage that the pivot shaft 51, which is, in a way corresponding to Fig. 1, placed substantially at the centre point of the surface of revolution of the applicator beam 50, is placed as close to the centre of gravity of the applicator beam 50 as possible. In such a case, the pivot cylinders 52 intended for pivoting of the applicator beam 50 can be dimensioned as of quite a small size. Above, the invention has been described by way of example with reference to the figures in the accompanying drawing. The invention is, however, not confined to the embodiments illustrated in the figures alone, but different alternatives of the invention may show variation within the scope of the inventive idea defined in the accompanying patent claims.

Claims: Size press comprising a nip (N) formed by press rolls (12,14;44), through which nip the paper or board web (W) is passed and in which size press the first press roll (12) is mounted by means of bearings (13) permanently on the frame (11) of the size press, whereas the other press roll (14;44) is mounted on the frame (11) of the size press by means of its bearings (15;45) as displaceable by the intermediate of loading arms (16;46), and in which size press the press rolls (12,14;44) are provided with coating devices (23,53) for the spreading of films of coating agent onto the faces of said rolls, said coating devices (23;53) being mounted on applicator beams (20;50) placed in the longitudinal direction of the rolls, which applicator beams are linked pivotally on the frame (11) of the size press or on the loading arms (16) of the displaceable roll (14) by means of a pivot shaft (21;51) longitudinal to the beam and which applicator beams are provided with pivot cylinders (22;52), by whose means the applicator beams (20;50) can be pivoted between a closed position, i.e. the operating position, and an opened position, i.e. the service position, characterized in that, in its cross section taken in a vertical plane in the transverse direction of the applicator beam (20;50) this beam is shaped so that at least its wall (26) that is facing away from the corresponding press roll (14;44) is curved, the distance from the curved outer face (26) of the applicator beam (20;50) to the pivot shaft (21;51) being substantially equally large at every point, such that, when the applicator beam (20;50) is pivoted around its pivot shaft (21,51), the distance (a) from the curved outer face (26) of the applicator beam to the other constructions of the press and constructions related thereto and placed close to the applicator beam (20;50), such as the tending bridge (30), remains substantially unchanged. Applicator beam as claimed in claim 1, characterized in that the pivot shaft (21;51) of the applicator beam is placed in the area of the centre of curvature of the curved outer face (26). Applicator beam as claimed in any of the preceding claims, characterized in that the curved outer face (26) of the applicator beam forms apart of an arc of a circle. Applicator beam as claimed in any of the preceding claims, characterized in that the pivot shaft (21;51) is placed substantially at the centre of gravity of the cross-section of the applicator beam (20;50) or in direct proximity of said centre of gravity.

Inventors: ROUSU ARI, RUUSKA PAAVO, SALO MARKKU, ROUSU, ARI, RUUSKA, PAAVO, SALO, MARKKU
Applicants: VALMET PAPER MACHINERY INC, VALMET PAPER MACHINERY INC.
Application year: 1993
Main classification: D21H23
IPC codes: D21H23