9 - AHP Merkle GmbH

2.4 Hydraulic cylinders with special features
72
Double-lined cylinder
Double lined cylinders are hydraulic cylinders with a very special design. Structurally they are designed with two
cylinder tubes that are built one inside the other and sealed pressure-tight relative to each other. They can be
ordered even for long strokes. The distinguishing feature of double lined cylinders is their round construction
with a fl ange at one end. The fl ange is located either at the rod end or at the piston end. Attached to this
fl ange are both ports for the forwards and return stroke, and the cylinder is also mounted on it. The use of
double lined cylinders is always advisable when due to long strokes and installation in large molds one end of
the cylinder is hard to access, and thus both ports have to be located on one end.
Core pull unit
Core pull units are hydraulic cylinder designed with a guide that can apply high linear forces and very precise
motion. They are especially well suited for injection molding applications. In this arrangement of guide and
cylinder, the unit „pulls“ out the core of an injection molding tool with great force. Because here the hydraulic
cylinder „pushes“ with its entire piston surface – and not just with the ring surface, as is otherwise typical for
pulling motions. In this manner it applies 1.6 times the force with the same pressure conditions.
Core pull units also save space, and can absorb very strong side forces and torques. Both of these are important
requirements for building optimal tooling solutions in injection molding.