Rakelmesser

Abstract

A plate-shaped doctor blade used for peeling paper from a surface of a roller provided in a papermaking apparatus, the doctor blade comprising: a rectangular body with a longitudinal direction extending in an axial direction of the roller, and comprising a front end that is to be brought into contact with the surface, a rear end opposite the front end and side ends, both of which are in the longitudinal direction, where both ends are chamfered in an arc shape in the longitudinal direction of the front end.

Description

Technical field

[0001] The present invention relates to a doctor blade used for peeling paper from a surface of a roller provided in a papermaking apparatus, such as a paper machine. State of the art

[0002] Typically, in the drying section of a papermaking machine, a damp paper web is continuously fed onto the surface of a roller, such as a Yankee dryer, which is heated to a high temperature. After the damp paper web has dried as it passes over the rotating roller, the dried paper is peeled from the surface of the roller and sent to the next step.

[0003] At this stage, a doctor blade is used to peel the paper from the surface of the roller. For example, PTLs 1 and 2 disclose a plate-shaped doctor blade used in a papermaking device, such as a paper machine. The doctor blades described in these documents can peel paper or paper dust that has dried and adhered to the surface of the roller when their tip is pressed against the surface of the rotating roller. List of citations from patent literature PTL 1: Japanese unexamined patent application publication no. 2002-173887 PTL 2: Japanese unexamined utility model registration application publication no. 62-180098 Summary of the invention: Technical problem

[0004] However, as described in PTL 1, if the doctor blade is made of metal, sparks can be generated when the blade tip comes into contact with the surface of the rotating roller, and the risk of fire caused by these sparks has been highlighted. Specifically, because there is a large quantity of paper formed in a web or a large amount of paper dust around the papermaking apparatus, there is concern that the paper or paper dust could be ignited by the sparks. Thus, PTLs 1 and 2 propose doctor blades that use a non-metallic material, such as epoxy resin, ceramic, carbon fiber, or the like, which does not generate sparks. However, from the standpoint of rigidity and durability, there is a high demand for metal doctor blades, and metal doctor blades that are less likely to generate sparks are needed.

[0005] One object of the present invention is to provide a doctor blade that is less likely to generate sparks when the doctor blade is brought into contact with the surface of a roller. Solution to the problem

[0006] A doctor blade of the present invention is a plate-shaped doctor blade used for peeling paper from the surface of a roller provided in a papermaking apparatus. The doctor blade comprises a rectangular body with a longitudinal direction extending in an axial direction of the roller, a front end that is to be brought into contact with the surface of the roller, a rear end opposite the front end, and side ends that are longitudinal ends. Both longitudinal ends of the front end are chamfered in an arc.

[0007] In the doctor blade according to the present invention, both ends of the rear end located in the longitudinal direction are chamfered in an arc shape. Advantageous effects of the invention

[0008] In the doctor blade of the present invention, both ends of the leading edge are chamfered in an arcuate shape along the longitudinal direction. For example, if the leading edge is not chamfered in an arcuate shape, corners are formed at both ends of the leading edge, and these corners act as resistance when the leading edge is brought into contact with the surface of the roller, causing sparks. However, in the doctor blade of the present invention, the leading edge is chamfered in an arcuate shape, so that there are no corners that can cause the generation of sparks. Thus, the resistance when the doctor blade is brought into contact with the surface of the roller is reduced, and therefore the generation of sparks can be suppressed.

[0009] In the doctor blade of the present invention, both ends of the rear end are chamfered in the longitudinal direction. In this case, for example, if the front end is damaged, e.g., deformed or chipped, and difficult to use, the rear end can be used by bringing it into contact with the roller surface instead of the front end. Furthermore, because both ends of the rear end are chamfered in the arc, eliminating sharp corners that could cause sparking, the resistance encountered when the rear end comes into contact with the roller surface is reduced, thus suppressing sparking. Brief description of the drawings Fig. is a schematic perspective view showing a state in which a doctor blade according to an embodiment of the present invention is installed such that it is pressed against a surface of a roller provided in a papermaking apparatus. Fig. is a top view and a partially enlarged view of the doctor blade according to the embodiment of the present invention. Description of the embodiments

[0010] Below, a doctor blade 1 according to an embodiment of the present invention is described with reference to Fig. described. In the following description, the axial direction of a Fig. shown roller 2 and the longitudinal direction of the in Fig. The direction of the doctor blade 1 shown is designated as the left-right direction X, and the transverse direction of the doctor blade 1 is designated as the front-back direction Y.

[0011] Fig. Figure 1 is a schematic perspective view showing a state in which the doctor blade 1 is installed such that a front end 1a of it is pressed against a surface 2a of the metal roller 2, such as a Yankee dryer, which is provided in a dryer section of a papermaking device, such as a paper machine (not shown). The doctor blade 1 is made of a metal, such as iron or stainless steel, and is formed into a plate. The doctor blade 1 is as shown in Figure 1. Fig. shown installed in relation to roller 2 and is used to peel paper from the surface 2a of roller 2.

[0012] The doctor blade 1 has a body 1b. The longitudinal direction of the body 1b extends in the left-right direction X, which is the direction of the axial direction of the roller 2. The body 1b is formed in a rectangular shape in plan view and comprises a front end 1a, which is to be brought into contact with the surface 2a of the roller 2 when installed, a rear end 1a' opposite the front end 1a, and side ends 1c and 1c', both of which are in the left-right direction X. Fig. The front end 1a is a front edge of the body 1b and comes into contact with the surface 2a of the roller 2 when the doctor blade 1 is as shown. Fig. The side ends 1c and 1c' are the left and right edges of the body 1b and are continuous with the front end 1a and the rear end 1a'.

[0013] Although not shown, the front end 1a is preferably formed as an edge having a smaller thickness than the central area of ​​the body 1b, and various edges, such as a parallel edge, a slanted edge, a rounded edge and a square edge, can be used.

[0014] Both ends in the longitudinal direction (the left-right direction X) of the front end 1a are chamfered in an arc shape ( Fig. ).

[0015] Specifically, with reference to the right end of the doctor blade 1 in the partially enlarged view in Fig. A first connecting area 1d, which is connected to the side end 1c, is formed at the right end of the front end 1a. Because the first connecting area 1d is chamfered in an arc up to the side end 1c, the linear front end 1a and the linear side end 1c of the doctor blade 1 are smoothly connected without forming a corner. The doctor blade 1 is symmetrically formed and therefore also has a first connecting area 1d at the left end, which is the same as the one at the right end. Because the first connecting area 1d at the left end has the same configuration as the one at the right end, its description is omitted.

[0016] The rear end 1a' is the rear edge of the body 1b and can be brought into contact with the surface 2a of the roller 2 instead of the front end 1a if, for example, the front end 1a is damaged, e.g., deformed or chipped, and difficult to use as is. It is preferred that the rear end 1a' be formed as an edge, like the front end 1a.

[0017] Furthermore, both ends of the rear end 1a' of the doctor blade 1 are also chamfered in an arc shape in the longitudinal direction (the left-right direction X). Fig. Specifically, with reference to the right end of the doctor blade 1 in the partially enlarged view in Fig.A second connecting area 1e, which is connected to the side end 1c, is formed at the right end of the rear end 1a'. Because the second connecting area 1e is chamfered in an arc up to the side end 1c, the linear rear end 1a' and the linear side end 1c of the doctor blade 1 are smoothly connected without forming a corner. The doctor blade 1 is symmetrical and therefore also has a second connecting area 1e at the left end, which is the same as the one at the right end. Because the second connecting area 1e at the left end has the same configuration as the one at the right end, its description is omitted.

[0018] Next, the beneficial effects of the doctor blade 1 will be described.

[0019] In the doctor blade 1, both left and right ends of the front end 1a are chamfered in an arc. Because there are no corners that could cause sparks to be generated at the first connection areas 1d and 1d, which are the ends of the front end 1a, the resistance that occurs when the front end 1a is brought into contact with the surface 2a of the roller 2 is reduced, and thus the generation of sparks can be suppressed.

[0020] The doctor blade 1 has a rear end 1a' which can be brought into contact with the surface 2a of the roller 2 in place of the front end 1a, and both left and right ends of the rear end 1a' are chamfered in an arc. In this case, for example, if the front end 1a is damaged, e.g., deformed or chipped, and difficult to use as is, the rear end 1a' can be used by bringing it into contact with the surface 2a of the roller 2 in place of the front end 1a. Furthermore, when the rear end 1a' is brought into contact with the surface 2a of the roller 2, because there are no corners that can cause the generation of sparks in the second connection areas 1e and 1e, which are the ends of the rear end 1a', the resistance that occurs when the rear end 1a' is brought into contact with the surface 2a of the roller 2 is reduced, and thus the generation of sparks can be suppressed.The doctor blade 1 with the rear end 1a' can be used for a longer time than other doctor blades and requires less frequent replacement. This makes it possible to reduce the maintenance costs of the papermaking equipment.

[0021] The embodiment of the present invention has been described in detail above, but the present invention is not limited to the embodiment described above. Various design modifications can be made to the present invention, as long as such modifications do not deviate from the scope of the claims.

[0022] For example, the doctor blade 1 according to the present embodiment is configured to have the rear end 1a', but it need not have the rear end 1a'. An example of the doctor blade 1 according to the present embodiment has been described in which the first connecting regions 1d and 1d, which are both ends of the front end 1a, and the second connecting regions 1e and 1e, which are both ends of the rear end 1a', are chamfered in an arc extending to the side ends 1c and 1c. However, the first connecting regions 1d and 1d and the second connecting regions 1e and 1e need not be continuous with the side ends 1c and 1c in an arc. It is only necessary that both ends of the front end 1a and both ends of the rear end 1a' are chamfered in an arc so that no corners are formed at either end of the front end 1a or either end of the rear end 1a'. Reference symbol list 1 squeegee 1a Front end 1a' Rear end 1b Body 1c End of page 1d first connection area 1e second connection area 2 rollers 2a Surface X Left-right direction Y Front-Back direction QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 2002-173887

[0003] JP 62-180098

[0003]

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