Mold for making magnetic base

Abstract

There is disclosed a magnetic printing base for one or more printing plates, a method of making the magnetic base, and a mold in which moldable, non-magnetic adhesive material is molded about various parts of the magnetic base. The base is structured to permit magnetic circuit devices and end plates to be interconnected by the non-magnetic material into a unitary arrangement. Each magnetic circuit device includes a flat magnet disposed between and in contact with a pair of flat magnetizable plates. The permanent magnetsextend short of the final desired dimension of the base. The plates and the molded material initially extend beyond the final desired dimension of the base, but are trimmed off by a cutter to the final desired dimension after assembly of the base. To obviate the tendency of the printing plate to creep or drift, the spacing between the magnetic circuits is such that the strength, at surface of the base, of the magnetic flux field between next adjacent pole plates of adjacent magnetic circuit devices is equal to the strength, at the surface of the base, of the magnetic flux field between the pole plates of a magnetic circuit device itself. There is also disclosed a method of making a magnetic printing base by stages, as is desirable when molding a large base with a material that tends to set in a relatively short period of time, a mold therefor, and improved magnetic bases.

Dependencies are inferred from the claim text.