A new mechanical valve gate actuation system makes it possible to have an accurate and reproducible opening and closing of the injection gate. Heitec Heisskanaltechnik of Burgwald Germany available in North America through Technoject Machinery is introducing a brand new valve gate system actuation.
The principle is simple: Two mould components interlink diagonally and implement the needle movement. The actuating bar moves the needle unit. This needle unit consists of an actuating bar, which if firmly connected with the valve gate needle. Each needle can be adjusted individually in length. In addition, one drive unit can actuate several needles. If necessary very small cavity distances can be realized with this modular design.
Normally, the drive, the actuating bar and the needle are aligned in a row, but offset or at 90° to each other is possible as well. Also, the actuating bars can be positioned at almost any arbitrary angle to each other. This could allow the needle to be placed on an angle also. It is even possible with multi-cavity tools to arrange the needles at different angles.
The new diagonal drive can be operated with both a hydraulic or a pneumatic cylinder, or with an electric motor. As a standard the cylinder is mounted on one of the sides, but if requested can also be positioned at the top or bottom of the mould. If the drive is operated with a stepper motor, the needle movement can be actuated in such a way that a soft, final closing into the sealing area is made possible.
Unlike conventional systems, the drive cylinder is located outside the tool and heat transfer from the tool is eliminated to a large extent. Therefore, no more costly, heat-resistant components are needed. The mould construction results in a smaller stack height and a high stability, since the mould is not weakened by pockets. The installation of supports is therefore redundant. Often the height of the drive unit plus ejector package is reduced by 50% compared with the usual height requirements.
The drive mounted outside operates all needles in a system at the same time. This ensures that all valve gate needles open and close at the same time. A fine adjustment of the needle position is possible at any time on the machine by limiting the stroke of the drive component. A special kind of monitoring the needle movement and position is done with the visual position marker at the side of the drive system similar to a screw position indicator on an injection moulding machine. For quick and easy maintenance central lubrication fittings for the drive components are accessible from the outside and the lubrication channels are integrated in the intermediate plate. This complete drive system is simply mounted behind being the hot half and takes up all the supporting forces of a hot runner system (solid mould).
For more information call Technoject at 905-951-7144.