Abstract: A tool assembly (1) in which a tool closing force (CF) is applied to a forming tool (2) by means of closing force actuators (40). In a tool closing position each closing force actuator engages a lower tool section (4) and an upper tool section (3) through tool clamps (31A, 31B). The clamps take up the major portion of the tool separating force generated by the internal pressure of the forming tool. Only a small portion of the tool separating force has to be counteracted by the closing force actuators, the size of which can be substantially reduced. The elasticity of the clamp material results in a widening of the clamp under the influence of the tool separating force, and this clamp widening is compensated by the readjustment of the clamp through the application of the closing force.