| 摘要 |
In a punching apparatus for cutting portions out of a web of material, the punching tool assembly has a movable top punching tool and a bottom punching tool carried by a plate arrangement which includes a base, a first plate supported on the base and a second plate which is supported on the first plate and which carries the bottom tool. One of the plates is reciprocal transversely to the web of material while the other is pivotable about a substantially vertical axis. Movements of the plates relative to each other and relative to the base permit the punching tool assembly to be aligned with the portion to be punched out of the material web, prior to the punching operation. To reduce friction between the base and the relatively movable plates the apparatus has friction-reducing means which are reciprocal between an inoperative position in which the base and the plates are in contact with each other and an operative position in which the friction-reducing means provide for rolling friction between the relatively movable components. The friction-reducing means may be in the form of ball rolling units actuable between their inoperative and operative positions by piston actuators.
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