Tiebar withdrawal device

Device for moving the tiebar in a pressure die casting machine.

In order to clamp large or bulky die casting molds (e.g. for core pulls which extend out a long way), the top two tiebars can be withdrawn in most machines.

Figure 1 shows an example of the withdrawal of the tiebars. To do so, the tiebar nut on the fixed fixing plate is removed and the flange on the mold height adjustment is loosened. In the next step, the tiebar on the movable fixing plate is clamped tightly again. By doing so, when the movable fixing plate is moved back, the tiebar is taken back with it and pulled out of the mold area.

In automatic tiebar withdrawal devices, the tiebar nuts on the fixed fixing plate are split (see Figure 2). First, the split tiebar nuts are opened with a hydraulic actuating cylinder. Then the tiebar nuts are unlocked from the movable fixing plate. The freed tiebars are then pulled back by a hydraulic lifting cylinder on the end of the locking part until the die casting mold can be clamped without difficulty. To ensure the process runs smoothly, all movements are locked electronically and their end positions are monitored by a control limit switch.

The diagram and the process flow of an automatic tiebar withdrawal device are shown in Figure 3; Figure 4 and Figure 5 show example designs on cold chamber die casting machines.

  • Fig. 1: Withdrawal of the upper tiebars to clamp larger molds
  • Fig. 2: Split tiebar nut with hydraulic actuating cylinder on the fixed fixing plate, source: Bühler
  • Fig. 3: Principle of automatic tiebar withdrawal in a cold chamber die casting machine, source: Bühler AG
  • Figure 4:·Automatic tiebar withdrawal device on a cold chamber die casting machine, Bühler  AG
  • Figure 5:·Automatic tiebar withdrawal device on both upper tiebars of a cold chamber die casting machine, Oskar Frech GmbH
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