When designing molds with sliding cores, the mold designer is often faced with the challenge of fitting all traditional components in as small a mold base as possible. There are different methods of actuating a sliding core. The most common of these use horn or angle pins.
To move the slide when the mold opens or closes. Heel blocks (wedges) are normally used behind the sliding core to withstand injection pressure acting on the sliding core. Unfortunately, these components both use up precious mold space and are tied to the movement of the platen. Some molded parts also require that the sliding core be moved prior to opening a mold. While it is possible to use standard cylinders to actuate the sliding core or heel block, typical designs require additional mold design and machining, and waste mold space.
Then a third solution could be to use a standard Block Hydraulic Cylinder with a check valve to stop the oil flow. Check Valve should only be used in load holding or position holding applications where they work very well because of their typically near-zero leakage.
Here is the Vega Catalogue for Check Valves:
An alternative is to use a hydraulic locking core pull cylinder that replaces traditional slides and heel blocks. The cylinder enables independent movement of the sliding core and completely eliminates the need for wedges. It uses a segmented ring that presses into an internal groove within the cylinder assembly while in locking position. As a result, the injection pressure from the part cavity acts against the cross-section of the segmented ring, locking the slide without needing a heel block. Eliminating separate heel blocks or additional cylinders can result in a smaller mold base size—simplifying mold designs, reducing material costs and increasing overall cost savings.
A hydraulic locking core pull cylinder has a compact design, further enabling smaller mold bases. The modular design also enables easy modifications, and if the tool needs to be removed or exchanged, it’s easy to re-install it to the same specifications.
Here is a video explaining how Vega Hydraulic Locking Core Pull Cylinder V260CF works:
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