This disclosure relates to methods and apparatuses for punching workpieces. A punching tool is configured to move during a punching stroke along a stroke axis towards a workpiece to be punched. The punching tool is configured to move away from the punched workpiece during a return stroke. The punching tool includes first and second components configured to be coupled hydraulically for concurrent movement along the stroke axis. The punching tool includes a punching drive for moving the first component along the stroke axis. The punching apparatus is configured to move the second component relative to the first component at a first transmission ratio during the punching stroke. The punching apparatus is configured to move the second component relative to the first component at a second transmission ratio in response to a reaction force of the workpiece exceeding a threshold value of the punching drive during the punching stroke.

The invention relates to a hydraulic drive (1) comprising a working cylinder (2) and a travel cylinder (3) which is mechanically connected to the working cylinder (2). The working cylinder (2) and the travel cylinder (3) each comprise an upper and a lower cylinder chamber (21, 22, 31, 32), and all four cylinder chambers (21, 22, 31, 32) of the working and travel cylinder (2, 3) are connected to one another in a suitable manner in a closed pressure circuit (4) which is filled and prestressed with a hydraulic fluid (F). A rotational speed-variable hydraulic machine (5) with a first and second pressure connection (51, 52) is arranged in the pressure circuit (4) in order to conduct the hydraulic fluid (F) between the individual cylinder chambers (21, 22, 31, 32) of the working and travel cylinder (2, 3) during the operation (B) of the hydraulic drive (1). At least one first and second distributing valve (6, 7) are arranged in the pressure circuit (4) such that the respective valve switch positions (61, 62, 71, 72, 73) which are suitable for the different operating phases of the hydraulic drive (1) together with the suitably driven hydraulic machine (5) allow a common movement of the work and travel cylinder (2, 3) in one or the other piston movement direction (R1, R2). For this purpose, preferably only the first and the second distributing valve (6, 7) are arranged in the pressure circuit (4). The hydraulic drive (1) requires a minimum number of components, maintains a low installation complexity, improves the energy efficiency, can be constructed in a compact manner, and can be operated in a sufficiently variable manner.

An arrangement for receiving a multi-part casting mold, in particular an at least two-part blow mold. A drive unit for displacing locking elements has a main cylinder with a main piston and a travel cylinder with a travel piston, wherein the travel cylinder is connected with the main piston of the main cylinder and is movable therewith. The travel piston has a piston rod, which is connected with the locking element and is mounted concentrically displaceably in the main piston. In the operating condition of the molding process, the travel piston abuts on the main piston, wherein the main cylinder provides the locking force to keep the mold closed during the molding process.

The invention relates to a precision blanking press comprising a top, a base and tie rods and columns that connect the top and the base non-positively.

The object of the invention is to provide a precision blanking press characterized by a press frame with a high stiffness, low mass and simple design, the press allowing the transfer of higher cutting forces during fine blanking while safely eliminating the axial play between the adjustment elements and at the same time improving the operational safety.

This object is achieved by providing that the knife-edged ring cylinder (32) is designed as a one-piece core member (16), a separate stripping/pushing cylinder (31) with stripping/pushing piston (35) in line with the stroke axis (HU) being disposed on the core member, and that an ejector piston (76) is associated with the counterstay piston (75) in the main piston (2), wherein the stripping/pushing piston (35) and the ejector piston (76) each have associated working chambers (36a, 36b; 79) that are independent of one another and are mutually connected hydraulically, and at least two diametrically opposite pre-loading pistons (59) and piston rods (60) disposed at the top (4) are associated with the stripping/pushing cylinder/core member (31/16), each of said pre-loading pistons being guided in a pre-loading cylinder chamber (58a, 58b) in the top (4) perpendicular to, and in line with, an adjusting nut (25), the cylinder being pressurized with fluid from the hydraulic system (39), wherein the piston rods (60) are connected together by way of an adjusting cross member (62) such that an adjustment motion of the pre-loading piston and the piston rods (59, 60) applies an external vertical adjusting force (F) to the stripping/pushing cylinder/core member (31/16), locking or releasing the internal threading (24) of the adjusting nut (25) at the external threading (23) of the core member (16) axially, and the main piston (2) comprises protruding discus-shaped working surfaces (68a, 68b) that subdivide working chambers (69a, 69b) disposed one atop the other vertically with minimal travel (H) in the cylinder chamber (65) of the base (5).