Printing – Intaglio – Wipers
Patent
1983-04-18
1985-03-12
Fisher, J. Reed
Printing
Intaglio
Wipers
101365, B41F 910
Patent
active
045037701
DESCRIPTION:
BRIEF SUMMARY
This invention relates to the art of doctor blades for use in printing machines.
In a common form of gravure printing machine, the cylinder having a very large number of ink-holding recesses is wiped, as it rotates, by a doctor blade which is pressed substantially rigidly against the surface of the cylinder.
The object of the present invention is to provide an improved form of doctor blade assembly, and an improved form of doctor blade which:
(i) increase the running life of the doctor blade,
(ii) maintain an even pressure between the face of the doctor blade and the cylinder,
(iii) prevent foreign bodies becoming trapped between the doctor blades and the cylinder,
(iv) counteract, so far as concerns the effect on the doctor blade, the bouncing of the cylinder due to, for example, worn bearings, bent mandrel ends, floating bowl, and rollers,
(v) prevent damage to the cylinder, by the doctor blade, as a result of backlash of the cylinder due to general play in the drive gearing of the cylinder,
(vi) lower high-pressure build-up of ink buffering against the doctor blade at high speeds,
(vii) reduce colour variation between changes of doctor blade.
According to the present invention a doctor blade assembly, for inclusion in a printing machine having a frame structure and a printing cylinder rotatable therein, comprises a mounting for supporting on the frame structure of the machine, a plane doctor blade supported by the mounting so as, when in use, to have its plane radial or at a small angle to radial to the printing cylinder, the doctor blade being movable substantially parallel to its own plane relative to the mounting, and loading means acting between the mounting and the blade in the direction to urge the blade against the printing cylinder.
The mounting may include a hollow housing with the doctor blade extending through an opening in the lower part of said housing to abut against the printing cylinder. In one form to provide for close but movable fitting of the blade, the housing includes elongated support elements between which the doctor blade is sandwiched but relatively slidable, at least one of said supports being resiliently urged towards the other. For example, one of said supports may be a fixed wall of the housing, and the other support may be a pad.
The loading means is preferably resilient loading means, and in a first form the loading means includes spring means acting between the mounting and that edge of the doctor blade which is remote from the printing cylinder. The loading means may thus be a plurality of compression springs disposed at intervals along the length of the doctor blade. A buffer strip may be positioned between such compression springs and the edge of the doctor blade. The doctor blade may conveniently be supported also by suspension means acting between it and the buffer strip. The buffer strip may form a sliding seal with the internal face of the housing such that the portion of the doctor blade which is situated within the housing is within a substantially sealed enclosure which receives any ink which is forced up the upstream surface of the doctor blade during rotation of the printing cylinder. A suction conduit, e.g. a hose protruding into the ink chamber, may serve to remove excess ink.
In another form, the resilient loading means is a bag containing resiliently compressible fluid and having a portion thereof acting on the doctor blade. The bag may, for instance, be disposed within a chamber having elongated legs bounding an opening in which the doctor blade is slidable. In a preferred arrangement, the doctor blade has, on its edge remote from the printing cylinder, a backing member which is abutted by the bag. Said backing member may form a sliding seal with the legs of the chamber.
Conduit means may be provided on the mounting to terminate adjacent the upstream face of the doctor blade for ejection of solvent onto that face, to keep the blade free of hardened ink when a temporary stoppage occurs.
The doctor blade assembly may further comprise sliding joint means by
REFERENCES:
patent: 1981912 (1934-11-01), Fankboner
patent: 2329277 (1943-09-01), Lodding
patent: 2692554 (1954-10-01), Bamford
patent: 2987748 (1961-06-01), Scott
patent: 3292201 (1966-12-01), Bedard
patent: 3778861 (1973-12-01), Goodnow
patent: 4192231 (1980-03-01), Kawakami
patent: 4241691 (1980-12-01), Hopfe
LandOfFree
Printing machine doctor blades does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Printing machine doctor blades, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Printing machine doctor blades will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-702235