| 摘要 |
The heating of heating torpedoes for tools and machines processing plastic is preferably performed by means of heating cartridges in which there is arranged a helical heating conductor embedded in highly compressed metal oxide. The very narrow tolerances in the operating temperature which apply in the processing of plastics require special controllers or temperature limiters, which of course represent additional expenditure. In addition, the construction of the torpedo must be designed such that all the parts which are in direct contact with the plastics composition are of the same temperature as far as possible. It is the object of the present invention to provide a heating torpedo which manages without any special complex control devices and in which exceeding of the permissible maximum temperature is reliably avoided with at the same time uniform heat distribution. This object is achieved according to the present invention by one or more PTC elements being mounted within an inner casing of highly heat-conductive metal in compressed metal oxide, which casing bears with its entire surface directly against the inner wall of the outer casing of the torpedo. |
