Abstract: The blanks punched out from a film web and folded to form the jacket are then heated for a short time and cooled again in order to eliminate stresses in the jacket material which give rise to deformations and are also produced by the action of heat during processing of the material.

Abstract: In a protective jacket for disk-shaped recording media, for example magnetic films, fixed magnetic disks, grammophone disks or video disks, the fleece covering in the jacket is fastened close to the outer edges of the jacket and close to the contour lines of the openings by means of heat welded points a short distance apart and in the region inbetween at a distance apart which is several times as large. As a result of the cushions thus formed, a more advantageous cleaning effect is achieved.

Abstract: A protective jacket for recording media, in particular flexible recording media, is provided with a network or grid of conductor paths (6) to counteract electric charges, Advantageously, the jacket blank (1) is coated uniformly, in particular on both sides, with linear conductor paths (6). The protective jacket can be used for storing any recording media outside a recording/playback apparatus, or for operating any recording media inside such an apparatus. It is advantageous if, in the areas in which the blank (1) is welded to form a partially or completely closed jacket after folding, a conductor path grid or network is provided so that areas which are free of the conductive layer and are of prescribed dimensions are available between the conductor paths, such areas being necessary for welding.

Abstract: A protective jacket, in particular for recording media, preferably magnetic films, is provided with at least one stiffened region in the immediate vicinity of the read/write area, thus permitting more thorough cleaning of the recording medium and smoother running of the latter. Stiffened region(s) can be produced economically by printing on strips of ink.

Abstract: Before being coated with the magnetizable material, the substrate plates are machined on a precision turning lathe in such a way that the annular surface provided for the storage area is convexly arched on both sides of the plate. For this purpose, the substrate plate, during machining, is held on the chuck in a concave arch of the annular surface and machined flat with a purely radial free movement of the cutting tool, or held on a flat chuck and turned down under a feed movement of the tool, which feed movement corresponds to the required convex arching of the annular surface. In the first machining method, the elastically deformed substrate plate, after removal from the chuck, loses tension and forms a convexly arched annular surface.

Abstract: An apparatus for the production of a jacket for a recording disk from a foldable blank, comprising a stationary receiving surface for one half of the blank and a further surface, pivotable essentially through an angle of 180.degree., for bending over the other half of the blank; a sheet-like spacer member which can be positioned over the stationary receiving surface, and one of whose edges, serving as a folding blade, is allocated to the swing point of the two said surfaces; and means for heating the fold area of the blank.