Abstract: The invention relates to a filter device for extruders and injection-molding machines, the screen elements being formed by a candle filter and, if required, by a plurality of candle filters, which are arranged in the circumferential direction on the screen plunger, extending parallel to the longitudinal axis of the screen plunger, and are flowed through from the outside inward for filtering purposes and from the inside outward for backwashing purposes.

Abstract: Apparatus for filtering plasticized material between two discrete inlets and a main outlet of a housing has two passages each of which connects one of the inlets with the main outlet. Each passage receives a reciprocable cylindrical filter carrier which can establish or interrupt a path for the flow of plasticized material from the respective inlet to the main outlet, depending on the selected axial position of the carrier. In order to expel contaminants which gather at the upstream side of the filter in a carrier, the carrier which is to be relieved of contaminants is moved to an axial position in which the respective inlet is sealed and the space at the downstream side of the filter receives filtered plasticized material substantially centrally of the filter. Contaminants are expelled from the space at the upstream side of the filter by way of a second outlet which is provided in the housing and communicates with the filter chamber of the carrier which is in the process of being relieved of contaminants.

Abstract: A filter changing apparatus for use with an extruder for plasticized synthetic plastic material has a housing with one or more bores for reciprocable cylindrical carriers of tubular filters. Each carrier is movable between at least one first position in which a stream of plastic material can flow from an inlet of the housing, axially into one end of the filter, radially outwardly from the filter and into an outlet of the housing, and at least one second position in which the carrier seals the inlet from the outlet or permits expulsion of contaminants and plastic material from the filter in a direction toward the inlet or into a second outlet of the housing.

Abstract: Apparatus for filtering plasticized material between the inlet and the outlet of a housing has two parallel passages for reciprocable filter carriers each of which is movable between a first position and a second position. When in their first positions, the carriers permit plasticized material to flow from the inlet, through filters in their filter chambers and then into the outlet of the housing.

Abstract: An extruder wherein the housing which defines a passage for the flow of foamed plastic material at elevated pressure and temperature to the shaping station contains a reciprocable carrier of one or more filters. The carrier has a filter compartment and is movable relative to the housing between a first position wherein the plastic material must flow from the inlet of the passage, through the compartment and the filter therein, and on to the outlet of the passage, and a second position in which the compartment is sealed from the passage. An expansion chamber in the housing and/or in the carrier communicates or can be caused to communicate with the compartment in the second position of the carrier so as to allow for a controlled reduction of pressure of plastic material before the compartment is made accessible for removal of inspection of the filter in the compartment. The compartment is thereupon rendered accessible, either in the second position of the carrier or by moving the carrier to a further position.

Abstract: Apparatus for filtering a stream of plasticized synthetic plastic material in an extruder has a housing with four or more channels connecting a material-admitting inlet with a material-discharging outlet. The housing is formed with parallel bores each of which receives a single reciprocable cylindrical carrier of two or more filters or two independently reciprocable cylindrical carriers of discrete filters. Each carrier can be moved between a first position in which its filter or filters register with discrete channels of the housing and at least one additional position in which its filter or one of its filters is accessible. At least 75 percent of filtering capacity remains available when a filter is being inspected, cleaned or replaced. The carriers seal those channels which are not in line with filters while the carriers are out of their first positions.