The present invention relates generally to rotary joints for establishing fluid connections between stationary piping and a rotating drum. More particularly, the present invention relates to a rotary joint of such type having a heat exchange chamber system for relieving any heat exchange effects from the fluid supply.
Rotary joints of the above-described types have widely varying uses throughout industry. For example, in a traditional paper manufacturing process, a paper web once formed is directed in peripheral contact about one or more heated rotating drums to effectively dry or calendar the paper web. The drum characteristically is hollow with a smooth outer peripheral surface for carrying the paper web, the drum being interiorly heated to transfer drying or calendaring heat to the traveling paper web. Conventionally, a rotary joint is affixed sealably to one axial end of the drum to establish a supply connection and, if desired, a return connection for flow of a heated fluid between external piping and the drum interior. Such rotary joints basically include a main shaft assembly for connection with stationary external fluid supply piping and a housing member rotatably journaled annularly about the shaft assembly, with one of the shaft assembly and housing member being affixed to the drum for rotation therewith while the other is mounted to remain stationary. The shaft assembly may be further adapted to receive internally one end of an exhaust tube to establish appropriate communication with stationary external fluid return piping, as desired.
With increasing efforts in recent years to improve the efficiency and economy in paper making operations, it has been common to increase the speed of operation of calendar and dryer drums while at the same time utilizing heating fluids such as heat transfer oils or steam at increasing temperatures. Unfortunately, such increases in drum speed and operating temperature place a substantial strain on the journal components of the rotary joint and, over time, deleteriously affect their anti-friction operation and may ultimately cause their failure.