Magnetic print cylinder

[57] ABSTRACT

A magnetic print cylinder for use with flexible, magnetizable printing plates, the cylinder having a plurality of axially extending, magnetic assemblies mounted in a side-by-side relation on the surface thereof, each of the assemblies including a channel member of magnetic flux insulating material, a plurality of permanent magnetic parts aligned in a spaced relation in the channel member, and a magnetizable pole piece positioned between each pair of magnets, the outer surface of the magnetic assemblies forming the plate mounting surface for the printing plates.

Claims, 6 Drawing Figures

<img file="US3721189A_D0001.tif" />

/2

PATENTEDMAR20 1973

3,721,189

<img file="US3721189A_D0002.tif" />

INVENTOR.

BY

Zzzzzevzy

3,721,189

MAGNETIC PRINT CYLINDER

BACKGROUND OF THE INVENTION

The increased use of magnetizable type flexible printing plates has produced a need for a magnetic plate cylinder. A number of such cylinders are described in U.S. Pats. No. 3,039,390 issued June 19, 1962 and No. 3,097,598 issued July 16, 1965 entitled “Printing Cylinders” and U.S. Pat. No. 3,496,866 issued Feb. 24, 1970 entitled “Magnetic Plate Cylinder.” These three patents generally show the three types of cylinders which have been used for this purpose. The first two patents disclose plate cylinders which are provided with annular magnetic poles on the outer surface of the cylinder. The plate cylinders in both of these patents are complicated and require considerable time to assemble. The plate cylinder in U.S. Pat. No. 3,496,866 shows axially extending pole pieces which are used to hold down only the ends of the printing plate. Mounting of the printing plate on this type of printing cylinder is limited to the location of the magnetic pole pieces.

SUMMARY OF THE INVENTION

The magnetic plate cylinder of the present invention overcomes the above problems by providing a magnetic field in the entire outer surface of a cylinder using preformed magnetic assemblies. Each of the magnetic assemblies has a plurality of permanent magnets positioned in a spaced relation within a channel member. Nonferrous spacers are used to hold the magnets in the channel member and magnetizable pole pieces are positioned between the spacers and the magnets. A simple and unique mounting arrangement is provided ³³for locking the spacers and pole pieces in the channel members. The permanent magnets may be formed individually or as integral parts of the spacers to simplify the procedure for assembling the channel members. The channel members can be readily adapted to fit on any diameter cylinder without any necessity for changing the pole pieces, magnets and spacers. A printing cylinder of this type increases the flexibility of its use to a variety of printing plate sizes and arrangements.

Other objects and advantages will become apparent when read in connection with the accompanying drawings.

THE DRAWINGS

FIG. 1 is a perspective view of the magnetic plate cylinder according to the present invention;

FIG. 2 is a top view of a portion of one of the magnetic assemblies;

FIG. 3 is a section view taken on line 3—3 of FIG. 2 55 showing the magnetic flux field between adjacent pole pieces;

FIG. 4 is a section view taken on line 4—4 of FIG. 3 showing one of the pole pieces;

FIG. 5 is a section view taken on line 5—5 of FIG. 3 ⁶⁰showing one form of magnetic component; and

FIG. 6 is a view similar to FIG. 5 showing an alternate form of magnetic component.

DESCRIPTION OF THE INVENTION

Referring to FIG. 1 of the drawings, the magnetic plate cylinder 10 of the present invention generally in2 eludes a cylinder 12 having journals 14 at each end. The entire outer surface of the cylinder 12 is provided with a magnetic field by means of a plurality of magnetic assemblies 16 mounted thereon. Each of the mag5 netic assemblies 16 includes a plurality of permanent magnetic components or parts 18 and magnetizable pole pieces 20 which are alternately arranged within a channel member 22. The preassembled magnetic assemblies 16 are mounted on the cylinder 12 and the outer surface of the magnetic assemblies machined to the desired diameter (circumference).

MAGNETIC ASSEMBLIES

In accordance with the invention, a magnetic field is provided on the entire periphery of the cylinder 12 for holding magnetizable printing plates thereon by means of the magnetic assemblies 16. Each of the magnetic assemblies 16 includes a parent or channel member 22, a 20 plurality of permanent magnetic and spacer parts 18, and a plurality of magnetizable pole pieces 20. Referring to FIGS. 2 and 3, a portion of one of the magnetic assemblies 16 is shown with the magnetic and spacer parts 18 and pole pieces 20 alternately arranged in the 25 channel member 22. The magnetic and spacer parts 18 and pole pieces 20 are locked in the member 22 by means of a filler block 30 provided at each end of the member 22. The permanent magnetic and spacer parts 18 are arranged with like magnetic poles adjacent common pole pieces 20 as more particularly described below.

The channel members 22 are formed from a magnetic flux insulating material such as a non-ferrous metal, i.e. aluminum or brass, or stainless steel. Means are provided within the members 22 for locking the magnetic and spacer parts 18 and pole pieces 20 in the channel members 22. Such means, as seen in FIGS. 4,5 and 6, is in the form of a mechanically interlocking element 32 shown as a pair of flanges 32 located on the inside surfaces 34 of said walls 36 of channel members 22. Although flanges 32 are shown any other suitable means such as a dovetail or truncated configuration could be used. The surface 38 on the bottom wall 40 of the member 22 is shaped to matingly engage the outer surface of the cylinder 12 and can be arcuate as shown, or flat.

The magnetic and spacer parts 18 can be made as shown in either FIG. 5 or FIG. 6. In this regard, the 50 component 18 shown in FIG. 5 includes a permanent magnet 42 which is positioned in the bottom of the channel member 22. The magnet 42 is retained therein by means of a spacer 44 which has axially extending slots 46 along each side for engagement with flanges 32 provided in the channel member 22. In the alternate arrangement shown in FIG. 6, a permanent magnet 42 is formed as an integral part of a spacer 48. The spacer 48 has the same general outer configuration as the inner shape of the channel member 22. Slots 50 are provided along the sides of the spacer 48 to engage the flanges 32. The spacer (44 and 48) in both FIG. 5 and FIG. 6 is also formed of a magnetic flux insulating material such as a metal or a plastic.

The magnetic pole pieces 20 and the filler block 30 also have the same general outer configuration as the interior channel member 22. Slots 52 are provided along the sides of the pole piece 20 and filler block 30

3,721,189 which also correspond to the flanges 32 on the channel member 22. The outer edge 54 of the pole piece 20 should conform to the contemplated radius for the cylinder 10.

The magnetic assemblies 16 are assembled by alternately sliding a magnetic and spacer part 18 and a magnetic pole piece 20 into the channel member 22. It should be noted, as seen in FIG. 5, that the components 42 (or FIG. 6 components 48) are alternately turned to provide the south poles of adjacent magnets on both side of a magnetizable pole piece 20 and the north poles of the next adjacent magnets on each side of the next pole piece 20.

The filler blocks 30 are secured in the ends of each of the channel members 22 by means of pins 60 which are inserted through openings 62 provided in the channel member 22 into recesses 64 provided in the filler blocks 30.

The assemblies 16 are mounted on the cylinder 12 by means of a bolt 66 which extends through opening 68 provided in the filler block 30 and are threadedly received in threaded openings 70 provided in the cylinder 12. The pole piece 20 and magnetic and spacer parts 18 can be adhesively secured in the channel member 22 by any suitable means such as an epoxy resin.

It should be noted that the dimensions of the magnetic and spacer part 18 and pole pieces 20 are standardized for ease of assembly in the channel member 22. The channel members 22 can be adjusted to different radius cylinder 12 by machining the radial angle of the outside surface of the side walls 36 of the member 22 when mounted on the cylinder 12 to provide abutting contact with adjacent magnetic assemblies 16. This is accomplished by initially forming the member 22 with a radially extending side wall at an angle corresponding to the largest diameter cylinder contemplated for a particular set of channel members 22. The channel member can then be adapted for use with smaller cylinders by merely machining the angle of the side walls to the radial angle of the new cylinder.