Nozzle hydraulic needle

Support elements and device drives in customary standard machine versions may be employed for the installation of a silicone cylinder module. A drive for a hydraulic needle sealing nozzle must also be provided. With the use of cold runner nozzles with needle sealing or with a cold runner head, the needle sealing nozzle on the machine can be omitted. Figure 7.9 depicts a LSR cylinder equipment kit. 

The simple cold runner nozzle with hydraulic needle sealing system, as shown in Figure 7.11 makes possible either direct or indirect injection of silicone parts. Advantages in the application of this system are good thermal separation between the cold nozzle and the heated mould and the flat gate location on the moulded part. 

This can be carried out in two ways. The gas can be introduced either through the sprue or directly into the moulded part. The hydraulic needle shut-ofF nozzle is open. The mould material is completely injected. No material cushion remains behind. This stage of the process is shown in Figure 10.19. 

Hesse was actively involved in the development of the turbine proposed by Lester A. Pelton (1829-1909) by providing the original sketch of a split bucket. As stated by Rouse it is of note that whereas Pelton experimented first in this field of hydromachinery, with buckets improvised from oyster cans, a model made from patterns supplied by Pelton had been tested in 1883 by Hesse in his hydraulic laboratory . Pelton took out a second patent of his turbine in 1889 on small details, and this was followed by others on improvements of the bucket shape and in 1900 on the first needle nozzle. Hesse s laboratory appears to have been the first in the USA. Unfortunately, all that is known about it is found only in a printed report published in 1883, supplemented by a colleague of Hesse relating to the efficiency of a Pelton imit. 

Shutoff nozzles are used to prevent nozzles from leaking into empty molds or when the nozzle is retracted from the sprue bushings. Valves of all kinds —i.e., spring-loaded ball check valves, hydraulically and mechanically operated needle valves, and rotary valves —have been incorporated into nozzles. 

Hydraulically actuated needle-type shut-off nozzle with cooling jacket... 

Cold runner systems that are ready to use are offered as standard in the marketplace. These fimction especially well with needle sealing nozzles that are controlled hydraulically or pneumatically. In order to allow integration with the process sequence of the injection moulding machine, interfaces were developed for control of this type of cold runner. The machine control unit also monitors the position of the needles. 

Simple and sturdy construction of the exchangeable needles and nozzles Optimal thermal separation between hot and cold modules Uniform force application to all nozzles through the central hydraulic cylinder Reduced mould costs, since installation with different moulds is possible Easy matching of new moulds to the same cold runner head Cycle-time savings... 

Finally the hydraulic GIT needle shut-off nozzle is opened and the material cushion is injected for sealing as shown in Figure 10.18c. 

---