Printing – Flexible-sheet-securing devices
Reexamination Certificate
2001-02-06
2002-11-19
Evanisko, Leslie J. (Department: 2854)
Printing
Flexible-sheet-securing devices
C101S378000
Reexamination Certificate
active
06481348
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an apparatus for attaching an object; i.e., a printing plate or a blanket, to a printing cylinder of a printing press (hereinafter referred to as an “object attachment apparatus of a printing cylinder”), and to a printing plate and a blanket which can be attached to the printing cylinder by use of the apparatus.
2. Description of the Related Art
Japanese Patent No. 2956026 discloses a conventional apparatus for winding a printing plate or blanket around the outer circumferential surface of a cylinder of a rotary press to thereby attach the plate or blanket to the cylinder under tension.
The attachment apparatus disclosed in Japanese Patent No. 2956026 will be described. A printing plate or blanket (hereinafter generally referred to as a “plate”) to be attached to the cylinder has opposite end portions which are bent at respective angles corresponding to an angle formed between a slit for receiving the opposite end portions and the outer circumferential surface of the cylinder. That is, a first end portion of the plate is bent at an angle substantially equal to an acute angle formed between the slit and the outer circumferential surface of the cylinder, and a second end portion of the plate is bent at an angle substantially equal to an obtuse angle formed between the slit and the outer circumferential surface of the cylinder. Further, a large number of square openings are formed in a leg portion of the second bent end portion.
The apparatus for attaching the plate under tension disclosed in Japanese Patent No. 2956026 has the following structure. An axial-extending slit is formed in the cylinder of the rotary press such that the slit opens at the outer circumferential surface of the cylinder and extends radially inward; an axially-extending hole is formed in the cylinder such that the hole continues from the bottom portion of the slit; and an axially-extending tension spindle is rotatably inserted into the hole.
The plate is attached to the cylinder as follows. The first bent end portion of the plate is inserted into the slit to be located on the acute-angle side of the slit. Subsequently, the plate is wound around the outer circumferential surface of the cylinder, and the second bent end portion of the plate is inserted into the slit and attached to the tension spindle. Upon rotation of the tension spindle, the plate is pulled into the slit from the second end portion side, whereby the plate is attached to the outer circumferential surface of the cylinder under tension.
The means for attaching the second bent end portion to the tension spindle is a strip having a large number of elastic rectangular tongues aligned along the strip, such as a comb-shaped plate spring. The strip is disposed in a groove which is formed in the tension spindle and has a V-shaped cross section. The elastic rectangular tongues enter the large number of square openings of the leg portion of the second bent end portion, and their inwardly-facing surfaces come into engagement with the inner edge portions of the openings. More specifically, the base portion of the strip is fixed to the bottom portion of the groove such that the tip ends of the rectangular tongues project from the outer circumferential surface of the tension spindle and such that the tip ends can bend.
After the tip ends of the tongues have entered the openings at the second bent end portion of the plate upon rotation of the tension spindle, the inwardly-facing surfaces of the tongues come into engagement with the inner edge portions of the openings and move angularly, while bending, upon further rotation of the tension spindle. Thus, the tongues pull the plate into the slit by means of their elasticity, whereby the plate is attached to the outer circumferential surface of the cylinder in a state in which a proper elastic force is applied from the tongues to the second bent end portion of the plate.
When the plate is to be removed from the cylinder, the tension spindle is further rotated in the plate-attaching direction. As a result, the tongues bend such that their dimensions measured in the radial direction decrease, and the tongues disengage from the openings formed at the second bent end portion of the plate, so that the tip end portions of the tongues are released toward the deeper side of the slit. Thus, the tongues recover their original, straight shape.
When the tension spindle is rotated in the reverse direction in this state, the outwardly-facing surfaces of the tongues come into contact with the tip end of the second bent end portion of the plate and push the second bent end portion, so that the second bent end portion of the plate is pushed out of the slit. Thus, a portion of the plate located in the vicinity of the opening of the slit separates from the outer circumferential surface of the cylinder, so that a clearance is formed between that portion and the outer circumferential surface of the cylinder. The thus-formed clearance enables a worker to remove the plate from the cylinder.
The conventional apparatus for attaching a printing plate or blanket to a printing cylinder as disclosed in Japanese Patent No. 2956026 has the following drawbacks.
1. As described above, after the plate to be attached to the cylinder is inserted into the slit formed in the cylinder, the tension spindle is rotated in order to cause the tip ends of the elastic tongues to enter the openings formed in the second bent end portion of the plate. However, if the plate is inserted into the slit with a slight shifting, the tongues fail to enter the openings, because the openings and the tip ends of the tongues each have a square shape, and the relative position between each opening and a corresponding tongue is determined through engagement between opposite side edges of the opening and the opposite side edges of the tongue. In such a case, since the plate cannot be attached, the work of inserting the plate into the slit of the cylinder must be performed again. When the width of the openings formed in the second bent end portion of the plate is increased in order to overcome the above-mentioned problem, the attachment position of the plate varies greatly, which also requires re-performance of the work of inserting the plate into the slit of the cylinder. In either case, the burden imposed on a worker increases.
2. The slit formed in the cylinder is located outside of the tension-spindle insertion hole also formed in the cylinder; one of the side wall surfaces is tangent to the wall surface of the tension-spindle insertion hole; and cutaways extending in the circumferential direction are formed between the slit and the tension-spindle insertion hole at appropriate positions in order to connect the slit and the hole.
The second bent end portion of the plate inserted into the slit is located on the outside of the outer circumference of the tension spindle inserted into the tension-spindle insertion hole.
Subsequently, the plate is pulled toward the deeper side of the slit through use of elastic deformation of the tongues projecting from the outer circumferential surface of the tension spindle. Further, when the tension spindle is rotated further for removal of the plate, the tongues are disengaged from the plate and released toward the deeper side of the slit. Subsequently, the tension spindle is rotated in reverse in order to push the plate out of the slit by means of the tongues.
However, when the tongues attached to the tension spindle bend or deform permanently due to repeated plate attachment/removal operations, there is a possibility that the plate cannot be attached to the cylinder while receiving a constant tension from each of the tongues, due to variation in deformation amounts among the tongues. Further, there is a possibility that the tip ends of some tongues, having deformed greatly, do not come into contact with the plate and become unable to pull the plate into the slit and push the plate out of the slit.
Further, deformation and breakage of the tongues occu
Kitai Mitsuo
Yoneta Mutsuhito
Yoshizawa Kohji
Armstrong Westerman & Hattori, LLP
Evanisko Leslie J.
Tokyo Kikai Seisakusho Ltd.
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