Press Band Arrangement for Double-Band Presses

The invention relates to a press band arrangement for double-band presses for applying surface pressure on plate-shaped workpieces or on material webs continuously guided through such presses.

The bands which are usually made of suitable metals, particularly steel, singly or in several layers, closely adjacent, pushed into one another, are to transfer the pressure, which is generated by means of fluid pressure media or mechanically over an area to the material to be pressed, i.e. with or without forming a negative image of the press band surface on the material to be pressed, depending on the treatment purpose and the material to be pressed.

It is generally known to weld together such bands and band units of several longitudinally extending band strips according to the operating width of the machine if the band material is not available in the operating width of the machine. The longitudinal welding of steel bands is technically no problem, the removal of the tensile stresses which result in the welded seam due to shrinkage and which are added to the bending stresses and tensile stresses during normal operation and are therefore dangerous, requires an additional, difficult processing effort and is hardly possible to accomplish free of residual tension. An additional, expensive disadvantage, particularly in wide bands, consists in that a band or band unit which is damaged by a hard foreign body which entered the machine must be completely replaced.

It is the task of the invention to eliminate the above-described disadvantages and to suggest a method to decisively reduce the expenditure connected therewith.

The solution of this task is imparted by constructing the press bands as single or multiple layers with the layers made up of separate unconnected closely adjacent longitudinal strips extending over a pair of drums. Border disks on the drums hold the strips in place. In multiple layer press bands the edges of the strips in adjacent layers are offset.

FIG. 1 is a perspective schematic view of a single layer press band embodying the present invention; and

FIG. 2 is a view similar to FIG. 1 but illustrating a multiple layer press band.

As the drawing shows, the press bands 1 consist of individual, closely adjacent longitudinal strips which are not welded in the longitudinal direction, or of individual bands 2 of the same length which are arranged in a single layer (FIG. 1) or in several layers (FIG. 2) next to one another and are held by means of border disks 4 which are arranged at the sides of the band drums 3. Particularly in roller supported machines in which tightness with respect to a fluid pressure medium is not necessary, the arrangement according to the invention can be applied successfully. In multi-layered press band units as in FIG. 2, the units are pushed into one another in such a way that the longitudinal joints or edges of the individual band strips 2 are arranged offset with respect to one another in the transverse direction of the press band 1.

If, in the case of press band units, the operation or the use of the machine requires bands which are free of longitudinal gaps, i.e. which are, if necessary, longitudinally welded, then the remaining layers of the band unit may still be arranged unwelded if multi-layered press bands are required.

The advantages achieved with the invention are considerable because longitudinal welding and treatment of the longitudinally welded seam are omitted; when there are damages due to foreign bodies, replacements can be limited to the damaged parts or strips of a band layer; for the stock maintenance for replacement needs, it is sufficient to provide one individual band for each band layer and one longitudinal strip 2 for each band length.