Cutter blade

Abstract: A guillotine-type cutter blade (10) cuts sheets (18) such as papers, metallic plates, etc. The cutter blade (10) is provided at the back face (12) with a flank (13) which is inclined at an angle of 1 o to 7 o with respect to the moving direction of the cutter so as not to be in contact with the cut surface of the sheets (18a), thereby preventing formation of a built-up edge.

Description: The present invention relates to a cutting machine of the type as defined in the preamble of claim 1. A cutter blade for a cutting machine of this type is described in US-A-532 021. The known cutting knife has first and second sides and a cutting edge. The cutting edge is formed by the intersection of two inclined surfaces. The inclined surface of the second side extends at an angle of about 22° with respect to the flat second side. The inclined surface of the first side is arranged at a protrusion over the first side, and extends at an angle in the order of O°10' to 0°25', preferably about 0°15' with respect to the flat first surface. The knife is described to be able to minimise friction between the knife and the materials during the cutting operation, and to be able to retain the desirable characteristics after repeated sharpening. US-A-4 271 740 describes a cutting machine wherein an object is cut in such a manner that a cutting blade is rotated relatively to the object. The cutting blade is constructed as a straight blade and is arranged in the cutting machine essentially horizontal, but with an angle of preferably 1° to 5° between the back surface of the blade and a horizontal line. The cutting machine is not described to be able to cut a number of piled sheets. Further cutting machines are used to cut a large number of thin sheets or strips such as papers, plastics, aluminum plates, etc. into a predetermined small size sheet. The cutting machines are of a guillotine type in which a single-edged cutter blade is moved vertically to cut the sheets. The cutter blade has a cutting face and a vertically flat face or a back face intersecting the cutting face to form a cutting edge. In cutting the sheets, the cutting face pushes cut sheets away from the sheets while the flat face is made to face the cut surface of the sheets. Such a cutter blade is liable to have cutting dusts stuck thereto only at several cuttings, depending on materials of sheets and the number of sheets for a cutting. The dusts cause scratches of the cut surface of the sheets. Conventionally, various countermeasures are taken to prevent this problem. For example, in the case of cutting a number of aluminum sheets, a paper laminated with a polyethylene is interposed as a interleaf between each of the alminum sheets, or the cutter blade is applied with a lubricant as described in Japanese Patent Laid-Open Publication No. 2-109699. However, when cutting such metallic sheets with papers interposed, the cutting edge of the cutter blade is damaged at only 10 cuts, which causes the cut surface of the metallic sheets to be scratched linearly by cutting dusts. The dusts are stuck to the back face of the cutter blade because of heat generated in cutting to cause a built-up edge which is a newly formed portion of the cutting edge. There are known cutter blades having a flank in their back face in order to prevent formation of a built-up edge. However, the inclinations of the flanks with respect to the moving direction of the cutter blades are approximately only 0.02°, so that a built-up edge is formed also only at 10 cuts. Therefore, it is necessitated to change the cutter every 10 cuts, resulting in degradation of efficiency of cutting operation. It is therefore an object of the present invention to provide a cutter blade whose lifetime is long. It is another object of the present invention to provide a cutter blade by which cutting operations can be performed efficiently. In order to achieve the above and other objects of the present invention, the cutter blade of the cutting machine as claimed in claim 1 is provided at the back with a flank having an inclination of 1° to 7° with respect to the moving direction of the cutter blade such that the flank will not contact the cut surface of stacked sheets. The flank may be formed by a flat surface or a curved surface. Also, the flank may be formed by inclining a cutter blade with a spacer attached to the back surface of cutter blade. According to the present invention, the lifetime of the cutter blade can be lengthened, contributing to improvement of efficiency of cutting operation. The above objects and advantages of the present invention will become more apparent from the following detailed description of preferred embodiments of the invention when read in connection with the accompanying drawings, in which: Fig. 1 is a cross section illustrating a cutting condition by use with a cutter blade in a cutting machine according to the present invention; Fig. 2 is a cross section illustrating a stack of aluminum sheets, which are piled alternately with interleaves and sandwiched by cardboard sheets; Fig. 3 illustrates a portion of the cutter blade of Fig. 1; and Figs. 4 to 6 illustrate another examples of cutter blades use in cutting machines according to the present invention. In Fig. 1 illustrating a cutting machine 9, a cutter blade 10 has a cutting face 11 and a vertically flat face or a back face 12. The back face 12 is provided with a flank 13. The width of the cutter blade 10 is 1.8 m. The cutter blade 10 is attached to the base plate of a drive unit (not illustrated) by screws and driven in a direction indicated by an arrow perpendicular to a cutting stage or table 25. A clamp 16 presses and fixes stacked sheets 18 placed on the cutting table 25. As illustrated in Fig. 2, in cutting a number of aluminum sheets, a number of aluminum sheets 20 and a number of interleaves 21 are first piled alternately, all of which are sandwiched by cardboard sheets 22 from upper and lower sides to form a set. Several sets thereof are piled one over another to constitute the stacked sheets 18 disposed on the cutting table 25. In this embodiment, the cutting machine 9 cuts presensitized plates having aluminum supports but can cut papers or plastic sheets, etc. A cut surface 18a of the stacked sheets 18 is formed by means of the cutter blade 10, and is parallel to a moving direction of the cutter blade 10. A wood pad 24 held by a pad holder 23 is fitted in a recess 26 of the cutting stage 25. When the cutter blade 10 is let down, the cutting edge of the cutter blade 10 cuts into the wood pad 24 finally so as to cut the stacked sheets 18 completely. As illustrated in Fig. 3, the flank 13 is inclined at an angle  with respect to the moving direction of the cutter blade 10 so as not to be in contact with the cut surface 18a. The angle  is preferably set to be in a range of 1° to 7°. If the angle  is less than 1°, a built-up edge is soon formed to cause scratches of the cut surface 18a. If the angle  is more than 7°, the strength of the cutter blade is small to cause the cutter blade to be broken. The operation of the above embodiment will be described now. After the stacked sheets 18 are fixed by the clamp 16, the cutter blade 10 is let down from an initial position by the drive unit. Then, the cutting edge of the cutter blade 10 cuts into the stacked sheets 18. The cut stacked sheets 19 are pushed by the cutting face 11 into a direction X as indicated in Fig. 1. Thereafter, the cutter blade 10 is raised to retreat to the initial position. After the clamp is set to be in a released condition, the stacked sheets 18 are moved by a predetermined length into the direction X and pressed and fixed again by the clamp 16. As soon as the cut stacked sheets 19 are removed from the cutting table 25, the cutter blade 10 in the initial position is let down again. This operation is repeated to cut the stacked sheets 18 sequentially. The number of times which the cutter blade 10 can perform sequential cuttings is varied in accordance with the kind of stacked sheet material, the number of piled sheets, and the angle  of the flank provided in the cutter blade. Therefore, the angle  of the flank 13 of the cutter blade 10 was variously changed to test how many times the cutter blade 10 can cut the stacked sheets 18. 50 alminum sheets of 0.3 mm thickness and 50 interleaves were alternately piled, all of which were sandwiched by the two cardboard sheets 22 to form one set. Three sets thereof were piled one over another to constitute the stacked sheets 18. The stacked sheets 18 were cut by 550 mm. The cutter blade 10 was formed of high-speed steel. The results of the test is written in the following table 1. Angle () 0.02° 0.5° 1.0° 3.0° 5.0° 7.0° 9.0° or more Maximum times of successive Cuts 10 50 250 500 700 1000 incapable Cutter strength up ↔ down As is apparent in the Table 1, when the angle  of the flank 13 was in a range from 1° to 7°, 250 to 1,000 sequential cuttings were possible until a built-up edge was formed on the cutter blade 10. However, when the angle  of the flank 13 was 9° or more, the strength of the cutter blade 10 was too small to use it. In Fig. 4 illustrating another embodiment, a cutter blade 30 has a curved flank 31. In Fig. 5, a cutter blade 40 has a flank 41 with a recessed portion 42. Further, as illustrated in Fig. 6, when attaching a cutter blade 50 with a flat back face 52 to a base plate 54 of the drive unit, a spacer 51 may be inserted to incline the cutter blade 50. Thereby, the inclined back face 52 serves to be a flank. While the present invention had been described in detail above with reference to preferred embodiments shown in the drawings, it will be apparent to those skilled in the art that various changes and modifications of the present invention are possible within the scope of the following claims.

Claims: A cutting machine (9) having a cutter blade (10,30,40,50) for cutting a number of piled sheets (18), said cutter blade (10,30,40,50) having a cutting face (11,32,53) and a back face (12,52) intersecting said cutting face (11,32,53) to form a cutting edge, said back face (12,52) facing a cut surface (18a) of said piled sheets (18) at the time of cutting and comprising an inclined flank (13,21,41,52) provided on the side of said back face (12,52) near said cutting edge, characterized in that said cutting machine (9) is of a guillotine type and comprises a cutting table (25) for supporting the piled sheets (18) on both sides of the plane of the cutter blade (10,30,40,50) and means for moving the cutter blade (10,30,40,50) in a direction perpendicular to the surface of said cutting table (25), and said flank (13,21,41,52) is inclined at an angle of 1° to 7° with respect to the moving direction of said cutter blade (10,30,40,50) so as not to contact said cut surface (18a). The cutting machine of claim 1, wherein said flank (13,41) is formed by a flat surface of a recess in said back face (12) interacting said cutting surface to form said cutting edge. The cutting machine of claim 2, wherein a further recess (42) is provided in said flat surface distant to said cutting edge. The cutting machine of claim 1, wherein said flank (31) is formed by a curved surface of a recess in said back face (12) intersecting said cutting surface to form said cutting edge. The cutting machine of claim 1 wherein the inclined flank (52) of said cutter blade (50) is provided by mounting said cutter blade (50) in an inclined position with respect to the moving direction of said cutter blade (50). The cutting machine of claim 5 including a wedge-like space (51) arranged between said cutter blade (50) and a base plate (54) for attaching said cutter blade (50) to said base plate (54).

Inventors: ISHIBASHI TERUHIKO, ISHIBASHI, TERUHIKO, ISHIBASHI, TERUHIKO C/O FUJI PHOTO FILM CO LTD
Applicants: FUJI PHOTO FILM CO LTD, FUJI PHOTO FILM CO., LTD.
Application year: 1993
Main classification: B26D1
IPC codes: B26D3, B26D1, B26D7