초록 ▼

A first continuously operating extruder for an extrudable material is fed with filtered such material from a second extruder through a filter and a storage tank having means for applying pressure to the material in the tank. During replacement of a filter, the second extruder is stopped, and the flo

A first continuously operating extruder for an extrudable material is fed with filtered such material from a second extruder through a filter and a storage tank having means for applying pressure to the material in the tank. During replacement of a filter, the second extruder is stopped, and the flow of material out of the continuously operating extruder is maintained constant by blocking the passageway between the second extruder and the tank and by applying suitable pressure to the material in the tank until the filter is removed and replaced by a new filter. The blocking device may be separate from a holder for a pair of filters, both the blocking device and the holder being movable by a fluid operable piston and cylinder. Alternatively, a separate blocking device may be omitted, and the filter holder may carry a single filter and have an impermeable portion which provides the blocking function.

대표청구항 ▼

A method for operating a material extrusion system for extruding filtered insulating material around a wire, said system comprising a first extruder having an inlet and an outlet, an extrusion head connected to the outlet of said first extruder for receiving filtered material therefrom and for apply

A method for operating a material extrusion system for extruding filtered insulating material around a wire, said system comprising a first extruder having an inlet and an outlet, an extrusion head connected to the outlet of said first extruder for receiving filtered material therefrom and for applying said filtered material around said wire as it is fed through said head; a second extruder having an inlet and an outlet; a material storage tank having an inlet connected to said inlet of said first extruder for material flow therebetween, a pressure applying means for applying pressure to the material therein, and means for preventing and alternately permitting material flow between said inlet of the tank and said inlet of said first extruder; a material conveying tube interconnecting said outlet of said second extruder to said inlet of said first extruder for material flow therebetween; filtering means insertable into said tube for filtering material flowing therethrough; and blocking means for blocking the flow of material through said tube and said filter, said method comprising: inserting the filtering means in said tube and unblocking said tube by operating said blocking means; supplying unfiltered said material to said inlet of said second extruder and operating said extruder to cause it to supply said last-mentioned material to said tube where it is filtered and then passes to said inlet of said first extruder; while preventing flow of said material into said storage tank, operating said first extruder continuously to extrude material out of said outlet of said first extruder into said extrusion head, said second extruder being normally operated at a rate such that filtered material is supplied to the inlet of said first extruder at a rate which is sufficient to cause said material to flow continuously out of the outlet of said first extruder; when it is desired to change said filter, permitting said material to flow into said storage tank; when said storage tank is filled with said material in an amount sufficient to replace the material extruded by said first extruder during the time required to change said filter, stopping said second extruder, blocking said tube with said blocking means and removing said filtering means from said tube; while said blocking means is blocking said tube, applying pressure by said pressure applying means to the material in said tank in an amount sufficient to cause material in said tank to be supplied to said inlet of said first extruder at a rate which will maintain a continuous flow of the filtered material out of said outlet of said first extruder; inserting a new filtering means in said tube and unblocking said tube by operating said blocking means; resuming the operation of said second extruder.