Patent GB-1381468-A (GB)
Title: Magnetic cylinder construction and method of making same
IPC: B23Q3/154
Filed: 1973-05-24
Abstract: 1381468 Permanent magnets; magnetic holding devices DAYCO CORP 24 May 1973 [12 June 1972] 24863/73 Heading H1P A permanent magnetized cylinder assembly 10 (Fig. 1), e.g. for retaining a pad printing blanket or like unit, containing magnetic materials comprises plural sector shaped magnetic units 11 detachably fixed in parallel disposition about the periphery of an elongated core 12 (Fig. 2), and parallel to the longitudinal axis thereof. The surfaces externally define a smooth right cylinder. Core 12 comprises central member 14 threaded at opposite ends 15 surrounded by a concentric tubular sleeve 16 with nuts 17 retaining end plates 20 bolted thereto at 23; the end assemblies having shafts 22 rotatably supporting the cylinder. Each assembly 11 (Fig. 3), comprises an elongated non-magnetic support strip 30 and interacting non-magnetic supports 31 with cavities 32 enclosing plural permanent mganets 33 therein. Plural magnetic polepieces 34 are fixed alternately with supports 31 and magnets 33 against strip 30 with like poles adjacent to define polepieces of alternating polarity along strip 30. Plural threaded fastening bolts 35 engaging registering holes of supports 31, magnets 33, and sleeve 16 retains each assembly 11 therein. Polepieces 34 are disposed in planes common to the polepieces of the remaining assemblies 11 and perpendicular to the axis, while the permanent magnets are disposed (Fig. 4, not shown), on opposite sides of the polepieces to derive an optimum strength field about the exterior of cylinder 10. Strip 30 is of U-shaped cross-section comprising side arms 41 with locking means comprising longitudinal interior lugs 43 along the side arms engaging cut-outs 42 of the polepieces and supports. External longitudinal rib 45 and groove 47 of assembly 11 engage corresponding ribs and grooves of adjacent identical assemblies (Fig. 5), and the side arms are of wedge-shaped crosssection. The polepieces and supports 31 have trapezoidal cross-sections normal to the axis, and inclined surfaces 51 are coplanar with the outside surfaces of the strip 30, so that each assembly of polepieces and supports defines a segmental annular magnetic ring with rectilinear lines dividing the pairs of adjacent polepieces. The lower edges of the polepieces and magnets engage the bight of the U-shaped strips whose arcuate bottom surfaces engage the outer surface of the core structure, and the assembly is retained as a unit by layers of epoxy resin 60. In assembly, strip 30 is cut to desired lengths defined by the inside distance between nuts 17, placed on a work-table, and polepieces 34, supports 31 and magnets 33 are assembled in sequence; all surfaces being coated with epoxy resin adhesive with like magnet poles adjacent each polepiece. The complete assembly is clamped until the epoxy resin is cured. The core structure may be magnetic or non-magnetic, and the outer surface may be machined or ground down to the required cylindrical dimensions. Strip 30 and supports 31 may be of, e.g. plastic aluminium alloy or stainless steel formed by extrusion, casting or stamping, while bolts 35 may be of aluminium and polepieces 34 of low carbon steel.