| 摘要 |
A clamping device for the clamping jaws (5, 6) of a sheet-metal stretcher has, for each pair of clamping jaws, a push rod (15) which slides in guides (14) in the clamping head (1) in the stretching plane and on which are pivoted two articulated rods which, in turn, are connected in articulated fashion to the clamping jaws (5, 6) and move these clamping jaws synchronously in two guides (3, 4) arranged in a wedge shape relative to one another, backwards to effect closure and forwards to effect opening. Because of the risk to the articulated rods and the clamping device in the event of a tear in the sheet during the stretching operation or the differential straining of the sheet (13) by the upper and lower clamping jaws (5, 6) due to the occurrence of very large and different forces on the two articulated rods, the articulated rods are connected to the clamping jaws (5, 6) in a manner which allows them to be decoupled. In this arrangement, the articulated rods are pivoted as bell-crank levers (23, 24) on the hydraulically movable push rod (15), with a fulcrum (22). The short arm is pivotably mounted via hydraulic pivoting cylinders (20, 21) arranged on the push rod (15), and the long arm can be coupled to drive stubs (31, 32) of the clamping jaws (5, 6) via mouth-shaped openings (29, 30) and decoupled from the clamping jaws by pivoting. <IMAGE>
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