Metal deforming – By use of tool acting during relative rotation between tool... – During rotation of work
Patent
1989-05-19
1991-06-04
Spruill, Robert L.
Metal deforming
By use of tool acting during relative rotation between tool...
During rotation of work
72102, 72703, B21B 2706
Patent
active
050203525
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to means for the screening of ink transfer rollers and to tool support means for use in such apparatus
BACKGROUND ART
In the process of flexographic printing, or flexography, ink is transferred by an ink transfer roller from an ink source to a flexible printing plate or roller. The ink transfer roller is provided on its cylindrical surface with an array of small depressions or indentations called cells. The array of cells on the surface of the ink transfer roller is known as a screen. The screen receives and holds ink from a supply source, a scraper blade or a rubber roller removes excess ink from the surface of the roller, and the ink from the screen is then transferred, directly or indirectly to the flexographic printing plate or roller.
The ink transfer rollers are produced by forming a roller with a smooth cylindrical surface of a suitable material, usually a metal such as copper, and then forming a screen thereon. The screen is normally formed by rotating the ink transfer roller, bringing a rotatable screen forming tool into contact with the surface of the roller such that it rotates about an axis substantially parallel to the axis of the transfer roller and moving the rotating tool along the roller such that a helical path of cells is formed with adjacent turns of the helix in register.
The present invention provides an alternative to the conventional apparatus for the screening of ink transfer rollers i.e. forming a screen of cells on the cylindrical surface of the ink transfer roller.
DISCLOSURE OF INVENTION
In one broad form the present invention provides a tool support assembly comprising: having a notional axis of rotation about which an ink transfer roller may be rotated; be transverse of and above the axis of rotation when attached thereto; normal to the arm and substantially parallel to the rotating axis; therealong; axis substantially parallel to the pivot axis; and opposite end to the support attachment.
In a further form the invention provides a screening apparatus including a horizontal longitudinal bed, a rotating means adapted to hold an ink transfer roller for rotation about a substantially horizontal axis of rotation positioned above, and aligned with, the longitudinal axis of the bed and the above described support assembly secured to the bed for controlled longitudinal movement therealong. Conveniently the apparatus is a conventional lathe with the support assembly attached to a carriage of the lathe bed.
The vibration damping means preferably comprises a strut or bar disposed between the lathe and the arm and inclined away from the roller. The strut being held in place by a resilient connection member, such as a shock cord, extending between the strut and a point on the arm closer to its first point than is its engagement with the strut. This arrangement serves to dampen any "chatter" of the tool. Any upward moment of the tool will cause the arm to rise and the tension in the resilient connection member will pull the upper end of the strut along the underside of the arm slightly towards the tool holder. As the tool drops under gravity the upper end of the strut will slide back along the underside of the arm. This arrangement preferably includes a stop member on the arm which will be engaged by the upper end of the strut if the tool were to drop more than a predetermined amount. The stop member is preferably so set that if the tool were to run off the end of a roller the tool would not drop so far that the tool holder would engage with the roller and mar its surface.
Alternatively, the vibration damping means comprises a telescopic fluid damper, such as a proprietary shock absorber, extending between a portion of the arm distal of the pivot and the support attachment. The inner telescopic member includes a clamp slidable therealong and lockable in any position. The clamp is positioned so that the tool can only drop to a limited position should it run off the end of a roller while the screen rolling operation is being undertaken. The position is se
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patent: 482947 (1892-09-01), Hope
patent: 878071 (1908-02-01), Laing
patent: 1414574 (1922-05-01), Laing
patent: 1982209 (1934-11-01), Gary
patent: 3292403 (1966-12-01), Lewis
M. J. Vine Enterprises Pty. Ltd.
Spruill Robert L.
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