Jacket for printing cylinder

Abstract

To provide a jacket for a printing cylinder that enables prevention of enlargement of the margin width on the gripping side of sheet paper while avoiding an increase in apparatus size.SOLUTION: A jacket 50 attached to a printing cylinder 10 of a sheet-fed printing machine, the jacket 50 comprising: a resin sheet 60; and a gripping-side mouthpiece 70 formed of a flat metal thin plate and joined so as to overlap one surface at a gripping-side end portion of the resin sheet 60, the gripping-side mouthpiece 70 being formed of spring steel.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a jacket for a printing cylinder. [Background technology]

[0002] In a sheet-fed printing press, a design is printed on the front side of a sheet being transported by a printing cylinder. A jacket may be attached to the outer peripheral surface of the printing cylinder, with which the back side of the sheet comes into contact, for example, as a stain-proofing measure. The jacket is typically configured with a stain-proof layer formed on the surface of a base plate made of a thin metal plate. For example, a thin aluminum plate is used as the base plate. The stain-proof layer is formed, for example, by baking a fluorine-based resin (see Patent Document 1 below).

[0003] Because jackets require replacement, they can be attached and detached from the printing cylinder on the press. When attaching a jacket to a printing cylinder, the leading edge, which is one circumferential end of the jacket, is held by a leading edge holder installed in a notch in the printing cylinder, and the printing cylinder is rotated while being wrapped around the outer circumferential surface of the printing cylinder. Then, the trailing edge, which is the other circumferential end of the jacket, is held by a trailing edge holder installed in the notch in the printing cylinder. In Patent Document 2 listed below, the bent end, which is the leading edge end of the jacket (plate), is inserted from the radial outside through a gap (gap) formed between the claw base (claw base bar) and the wall surface of the notch into the leading edge holding area, and is held by being sandwiched between the rod-shaped cam and claw base bar, which are the leading edge holders.

[0004] In addition to the above-mentioned jacket having a configuration in which an antifouling layer is formed on the surface of a base plate made of a thin metal plate, a thin resin sheet itself that is made of a material having antifouling properties or that has been treated with a surface treatment to exhibit antifouling properties may be used as a jacket. In this case, since the resin sheet is easily bent and has low strength, mouthpieces are attached to the circumferential ends of the resin sheet as reinforcing materials. In the jacket of Patent Document 3 (see Figure 3) listed below, the mouthpiece (first mouthpiece) at the leading end is made of a metal plate and is attached by bending (so-called hemming) the leading end of the resin sheet (non-metallic sheet) so as to sandwich it from both sides. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-166677 [Patent Document 2] Publication number 04-044364 [Patent Document 3] Patent No. 6738648 Summary of the Invention [Problem to be solved by the invention]

[0006] In the configuration of the nozzle in Patent Document 3, the thickness of the leading edge of the jacket is the sum of the thickness of the resin sheet and the thickness of the two metal plates that form the nozzle. Furthermore, because a space is formed inside the bent portion of the metal plate during processing, the thickness is even greater than this sum. In a configuration in which the leading edge of such a jacket is inserted into the holding area on the leading edge from the radial outside through the gap between the jaw base (jaw base bar) and the notch wall surface, as in Patent Document 2, it is necessary to increase the width (circumferential length) of the gap.

[0007] However, if the gap width is increased, the circumferential distance from the leading edge of the sheet held between the claws and the claw base to the print start position on the outer periphery of the printing cylinder increases, which increases the circumferential length (margin width) of the margin on the leading edge side of the sheet, potentially making it impossible to print efficiently for the size of the sheet.

[0008] In addition, in Patent Document 3, the leading edge holding area is also open to the outside from the axial end of the printing cylinder (the side of the printing cylinder), and the leading edge is inserted from this open area into the leading edge holding area by axial movement of the jacket, so there is no need to increase the width of the gap.However, with this configuration, it is necessary to secure space axially outside the side of the printing cylinder for axial movement of the jacket, which could result in the device becoming larger.

[0009] The present invention has been made in consideration of the existence of the above-mentioned problems, and its purpose is to provide a jacket for a printing cylinder that can prevent the circumferential length (margin width) of the margin on the leading edge of the sheet from increasing without increasing the size of the device. [Means for solving the problem]

[0010] The printing cylinder jacket according to the present invention is characterized by comprising a resin sheet and a die made of a flat metal thin plate superimposed on and joined to one surface of the leading edge of the resin sheet.

[0011] In the jacket for a printing cylinder according to the present invention, the mouthpiece can be made of spring steel.

[0012] In the printing cylinder jacket according to the present invention, the resin sheet may be made of a thermoplastic resin and may be joined to the die by welding at the interface with the die. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide a jacket for a printing cylinder that can prevent the circumferential length (margin width) of the margin on the leading edge of a sheet from increasing without increasing the size of the device. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a cross-sectional view of a printing cylinder to which a printing cylinder jacket according to one embodiment of the present invention is attached. [Figure 2] FIG. 2 is an enlarged view of the cutout portion of FIG. [Figure 3] FIG. 3 is an enlarged view of the leading edge side of FIG. 2. [Figure 4] FIG. 4 is a view corresponding to FIG. 3 and illustrates the attachment of the leading end of the jacket. [Figure 5] FIG. 1 is a front view showing a jacket for a printing cylinder according to one embodiment of the present invention. [Figure 6] 6A and 6B are diagrams illustrating a mouthpiece at the leading end of the jacket, with FIG. 6A being an enlarged view of part A in FIG. 5 and FIG. 6B being a cross-sectional view taken along line CC in FIG. 6A. [Figure 7] 6A and 6B are diagrams illustrating a nozzle at the tail end of the jacket, with FIG. 6A being an enlarged view of part B in FIG. 5, and FIG. 6B being a cross-sectional view taken along the line DD of FIG. 6A. DETAILED DESCRIPTION OF THE INVENTION

[0015] Preferred embodiments for carrying out the present invention will be described below with reference to the drawings. Note that the following embodiments do not limit the inventions according to the claims, and not all of the combinations of features described in the embodiments are necessarily essential to the solution of the invention.

[0016] First, with reference to FIGS. 1 to 3, a printing cylinder to which a printing cylinder jacket according to one embodiment of the present invention is attached will be described.

[0017] The printing cylinder 10 is a transport cylinder that transports sheets. The printing cylinder 10 is cylindrical and has an outer peripheral surface 11 and two notches 12 recessed in the outer peripheral surface 11 along the circumference. The notches 12 are groove-shaped and extend in the axial direction of the printing cylinder 10. The printing cylinder 10 is a so-called double cylinder. As shown in FIG. 2, the notch 12 has a leading edge side wall surface 13 to which a gripper support bar 24 (described later) is attached, a bottom surface 14, and a trailing edge side wall surface 15 opposite the leading edge side wall surface 13. The leading edge side wall surface 13, the bottom surface 14, and the trailing edge side wall surface 15 extend in the axial direction. A rounded chamfer 16 is formed at the connection between the outer peripheral surface 11 and the leading edge side wall surface 13 and extends in the axial direction (see FIGS. 3 and 4). Arranged inside the notch 12 are a plurality of claws 21 arranged in the axial direction, a claw shaft 22 supporting the claws 21, and a claw base bar 24 having a claw base 23 integrally formed therewith and projecting radially outward at an axial position corresponding to the claws 21. A sheet is clamped between the claws 21 and the claw base 23. In Figure 3, the clamped sheet is indicated by the symbol P. Note that the claw base 23 and the claw base bar 24 may be configured as separate members.

[0018] As shown in FIG. 3, the claw base bar 24 has a generally rectangular cross section. A lower surface 25 on the side of the claw base bar 24 facing the leading side wall surface 13 is in contact with the leading side wall surface 13 and is fixed to the leading side wall surface 13 with bolts (not shown). An upper surface 26, located above the lower surface 25 in the drawing, is positioned a predetermined distance away from the leading side wall surface 13 relative to the lower surface 25. The upper surface 26 is parallel to the lower surface 25 and also parallel to the leading side wall surface 13. The side of the claw base 23 facing the leading side wall surface 13 and the upper surface 26 are formed in the same plane. A gap indicated by the symbol T in FIG. 3 is formed between the upper surface 26 and the leading side wall surface 13. Similarly, a gap T is formed between the side of the claw base 23 facing the leading side wall surface 13 and the leading side wall surface 13 (the symbol T is also shown in FIG. 4). The gap T is formed to extend in the axial direction. A groove 27 extending in the axial direction is recessed in the upper surface 26 of the claw base bar 24. A presser bar 31, which will be described later, is disposed in this groove 27. Six operation holes 28 are formed in the bottom surface of the groove 27, lined up in the axial direction, and penetrate the side surface of the claw base bar 24 on the opposite gripping side wall surface 13 side. The operation holes 28 are formed as circular holes.

[0019] A pressure bar 31 is disposed in the groove 27. The pressure bar 31 has a rectangular cross section and extends in the axial direction. The pressure bar 31 has bolt insertion holes 32 formed at positions corresponding to the six operation holes 28. The screw shaft of a fixing bolt 33 is inserted into each bolt insertion hole 32 from the side opposite the leading edge wall surface 13. The screw shaft of the fixing bolt 33 is threaded into an internal thread formed in the leading edge wall surface 13. The fixing bolt 33 is a hexagon socket head bolt with a hexagonal hole formed in its head. When the fixing bolt 33 is screwed in, the pressure bar 31 approaches the leading edge wall surface 13. A side surface 34 of the pressure bar 31 facing the leading edge wall surface 13 is parallel to the leading edge wall surface 13. The pressure bar 31 has a chamfer 35 at the upper corner of the side surface 34. The chamfer 35 extends in the axial direction and is inclined at 15 degrees relative to the leading edge wall surface 13. A leading edge end 51 of a jacket 50 (described later) is clamped and held between the leading edge wall surface 13 and a side surface 34 of the pressure bar 31. The leading edge wall surface 13, the pressure bar 31, and the fixing bolt 33 constitute a leading edge holder 30 for holding the leading edge end 51 of the jacket 50.

[0020] As shown in Figure 2, a trailing edge holder 40 for holding a trailing edge 52 of a jacket 50 (described later) is installed near the trailing edge wall surface 15 inside the notch 12. The trailing edge holder 40 is equipped with a clamping means 41 that clamps the trailing edge 52 of the jacket 50. The clamping means 41 extends in the axial direction. The clamping means 41 is fixed to the tip of an arm 43 that has a base supported by a support shaft 42 arranged radially inward and is swingable around the axis of the support shaft 42. The axis of the support shaft 42 is parallel to the axis of the printing cylinder 10. A compression coil spring 44 is arranged between the swing arm 43 and the trailing edge wall surface 15.

[0021] The jacket 50, which is wound around the outer circumferential surface of the printing cylinder 10 with its leading edge 51 held by the leading edge holder 30 and its trailing edge 52 held by the trailing edge holder 40, is brought into close contact with the outer circumferential surface 11 of the printing cylinder 10 by the tension applied by the spring force of the compression coil spring 44.

[0022] Next, a jacket for a printing cylinder according to one embodiment of the present invention will be described with reference to FIGS. 5 to 7 as reference drawings.

[0023] The printing cylinder jacket 50 according to this embodiment comprises a rectangular resin sheet 60 as the main portion, and a leading edge nozzle 70 and a trailing edge nozzle 80 as reinforcing members respectively joined to two opposing sides of the resin sheet 60. The leading edge nozzle 70 and the trailing edge nozzle 80 extend over the entire length of the two sides. The leading edge nozzle 70 is located at the leading edge end 51 of the jacket 50, and the trailing edge nozzle 80 is located at the trailing edge end 52 of the jacket 50. In other words, the leading edge nozzle 70 is provided at the leading edge end of the resin sheet 60, and the trailing edge nozzle 80 is provided at the trailing edge of the resin sheet 60.

[0024] The material of the resin sheet 60 is a stain-resistant thermoplastic resin, and in this embodiment, PFA (perfluoro(alkyl vinyl ether)-tetrafluoroethylene plastic) is used. The thickness of the resin sheet 60 is 0.25 mm.

[0025] The leading edge nozzle 70 and the trailing edge nozzle 80 are made of flat metal thin plate, and in this embodiment, spring steel with a thickness of 0.5 mm is used. More specifically, a spring stainless steel strip with a thickness of 0.5 mm is used. By using spring steel that does not easily undergo plastic deformation, the thickness can be made thinner compared to when using general steel material with low spring properties. Furthermore, using stainless steel as the material prevents rust.

[0026] The leading edge nozzle 70 is bonded to the upper surface 61 of the resin sheet 60, which will be the front side (outside) when the jacket 50 is attached to the printing cylinder 10. Bonding is achieved by welding the resin sheet 60 to the leading edge nozzle 70 at the interface 71 between the overlapping resin sheet 60 and the leading edge nozzle 70. The welded portion is indicated by the symbol E in FIG. 6. Bonding by welding prevents the welded portion E from becoming thick, so the thickness of the leading edge 51 is approximately the same as the total thickness of the resin sheet 60 and the leading edge nozzle 70, which is 0.75 mm. Note that in the welding process, the leading edge nozzle 70 is heated from the opposite side of the resin sheet 60, and the heat transferred to the resin sheet 60 through the leading edge nozzle 70 melts the resin sheet 60 and bonds it to the leading edge nozzle 70. The welded portion E extends across the entire width of the resin sheet 60 along the longitudinal direction of the leading edge nozzle 70. U-cuts 53 are formed in six locations on the leading edge 51 for passing the screw shafts of the fixing bolts 33. Reference numeral 54 denotes positioning through holes for aligning the resin sheet 60 and the leading edge nozzle 70.

[0027] The rear end cap 80 is bonded to the underside 62 of the resin sheet 60, which will be the back side (inside) when the jacket 50 is attached to the printing cylinder 10. Bonding is achieved by welding the resin sheet 60 to the rear end cap 80 at the interface 81 between the overlapping resin sheet 60 and the rear end cap 80. The welded portion is indicated by the symbol F in Figure 7. Bonding by welding prevents the bonded portion from becoming thick, so the thickness of the rear end portion 52 is approximately the same as the combined thickness of the resin sheet 60 and the rear end cap 80, which is 0.75 mm. In the welding process, the rear end cap 80 is heated from the opposite side of the resin sheet 60, and the heat transferred to the resin sheet 60 through the rear end cap 80 melts the resin sheet 60 and bonds it to the rear end cap 80. The welded portion F extends across the entire width of the resin sheet 60 along the longitudinal direction of the rear end cap 80. Reference numeral 55 denotes a positioning through-hole for aligning the positions of the resin sheet 60 and the rear-side mouthpiece 80 .

[0028] The joining can also be performed by bonding at the boundary surfaces 71, 81 between the resin sheet 60 and the leading-side nozzle 70 or the trailing-side nozzle 80. In this case, an adhesive layer is formed at the boundary surfaces 71, 81, so the thickness of the leading-side end portion 51 and the trailing-side end portion 52 becomes slightly (about 0.05 mm) larger than the total thickness of the resin sheet 60 and the leading-side nozzle 70 or the trailing-side nozzle 80, which is 0.75 mm.

[0029] 4, the procedure for attaching the jacket 50 to the printing cylinder 10 will be described. Note that the symbol H in FIG.

[0030] First, all six fixing bolts 33 are rotated to screw them out a predetermined amount. Then, the leading edge 51 of the jacket 50 is inserted into the gap T from the radially outer side (the upper side of the paper in FIG. 4). The insertion direction is indicated by an arrow in FIG. 4. At this time, the axial position of the jacket 50 relative to the printing cylinder 10 is determined by aligning the position of the U-cut 53 with the position of the screw shaft of the fixing bolt 33. The width of the gap T is set to be a predetermined amount larger than the thickness of the leading edge 51 of the jacket 50. In this embodiment, the width of the gap T is set to 1.0 mm, with the thickness of the leading edge 51 being 0.75 mm. This allows for ample insertion. Furthermore, even if the pressure bar 31 is in the insertion direction of the gripping side end 51 when inserting, the tip (lower end) of the gripping side end 51 presses the chamfer 35 of the pressure bar 31, causing the pressure bar 31 to move in a direction away from the gripping side wall surface 13, and the gripping side end 51 can be inserted to the position shown in Figure 3.

[0031] 3, all six fixing bolts 33 are turned and screwed in and tightened, whereby the leading end 51 is held by being clamped between the leading wall surface 13 and the side surface 34 of the pressure bar 31. When clamped, the resin sheet 60 comes into contact with the leading wall surface 13, and the leading mouth piece 70 comes into contact with the pressure bar 31. Because the resin sheet 60 does not come into contact with the pressure bar 31, the resin sheet 60 will not be damaged by the pressure of the pressure bar 31.

[0032] Thereafter, the printing cylinder 10 is rotated to wrap the jacket 50 (resin sheet 60) around the outer peripheral surface 11, and the trailing edge 52 of the jacket 50 is held by the clamping means 41 of the trailing edge holder 40, and tension is applied to the jacket 50 (resin sheet 60) by the spring force of the compression coil spring 44. This causes the jacket 50 (resin sheet 60) to adhere closely to the outer peripheral surface 11 of the printing cylinder 10. Note that, because the printing cylinder 10 of this embodiment is configured as a double cylinder, the jacket 50 is attached to the outer peripheral surface 11 at two locations.

[0033] Next, referring again to FIG. 3, the printable start position of the printing cylinder 10 and the circumferential length of the margin on the leading edge side of the paper sheet P (margin width) will be described.

[0034] In FIG. 3, the printable start position of the printing cylinder 10 is indicated by the symbol S. The position on the surface of the jacket 50 corresponding to the connection between the outer peripheral surface 11 and the R chamfer 16 of the printing cylinder 10 is the printable start position S. The surface of the jacket 50 has an outer diameter suitable for printing from the printable start position S. The circumferential length (margin width) of the margin on the leading edge side of the sheet P, indicated by the symbol L in the figure, is the distance from the leading edge P1 of the sheet P to the printable start position S. If the gap T increases, the printable start position S moves in a direction away from the gripper base 23, and the margin width L increases. In this embodiment, the jacket 50 has a thin leading edge 51, which reduces the gap T and thereby prevents the margin width L from increasing. This enables efficient printing for the size of the sheet.

[0035] Although the embodiments of the present invention have been described above, the technical scope of the present invention is not limited to the scope described in the above embodiments. Various modifications and improvements can be made to the above embodiments.

[0036] For example, in the above-described embodiment, the printing cylinder 10 is a double cylinder, but is not limited to a double cylinder. For example, it may be a single cylinder or a triple cylinder.

[0037] Furthermore, for example, in the above-described embodiment, the material of the resin sheet 60 is PFA (perfluoro(alkyl vinyl ether)-tetrafluoroethylene plastic), but this is not limited to this. For example, it may be PTFE (polytetrafluoroethylene), silicone resin, or PET (polyethylene terephthalate). In the case of PET (polyethylene terephthalate), it is desirable to treat the surface of the sheet to exhibit antifouling properties.

[0038] Furthermore, for example, in the above-described embodiment, the thickness of the resin sheet 60 is 0.25 mm, but is not limited to this and may be, for example, 0.2 mm or 0.5 mm.

[0039] Furthermore, for example, in the above embodiment, the thickness of the leading edge mouthpiece 70 is 0.5 mm, but it is not limited to this and can be selected appropriately from the range of 0.2 mm to 1.0 mm.

[0040] Furthermore, for example, in the above-described embodiment, the width of the gap T is 1.0 mm, but is not limited to this. It may be set appropriately depending on the thickness of the resin sheet 60 and the leading-side nozzle 70.

[0041] Furthermore, for example, in the sheet-fed printing press of the above-described embodiment, the printing object is a paper sheet P, but the printing object is not limited to paper. For example, the printing object may be a resin film.

[0042] Furthermore, for example, in the above-described embodiment, the jacket 50 is provided with the leading edge side cap 70 and the trailing edge side cap 80, but it may be configured to be provided with only the leading edge side cap 70. [Explanation of symbols]

[0043] 10: Printing cylinder 11:Outer surface 12: Notch 13: Grip side wall 14: Bottom 15: Rear wall 16: R chamfer 21: Nails 22: Claw shaft 23: Nail stand 24: Nail stand bar 25: Lower side 26:Top side 27: Groove 28: Operation hole 30: Gripper side holder 31: Presser bar 32: Bolt insertion hole 33: Fixing bolt 34: Side 35: Chamfering 40: Buttocks support 41: Holding means 42: Support shaft 43: Arm 44: Compression coil spring 50: Jacket 51: Grip end 52: Butt end 53: U-cut 54:Through hole 55:Through hole 60: Resin sheet 61:Top surface 62: Bottom surface 70: Mouth side nozzle 71: Boundary 80: Bottom end cap 81: Boundary E: Welded part F: Welded part H:Tool L: Margin width P: Sheet paper P1: Leading edge (lead edge of sheet) S: Printable start position T: Gap

Claims

1. A jacket for a printing cylinder comprising a resin sheet and a die made of a flat metal thin plate superimposed on and bonded to one surface of the leading edge of the resin sheet.

2. 2. The printing cylinder jacket according to claim 1, wherein the nozzle is made of spring steel.

3. 3. A printing cylinder jacket according to claim 1, wherein the resin sheet is made of a thermoplastic resin and is joined to the die by welding at the interface with the die.

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