Apparatus and method for manufacturing monolithic cross flow particulate traps

An apparatus for manufacturing a monolithic cross flow particulate trap of porous ceramic material having a plurality of tubes having porous walls of lengths equal to that desired for the finished trap comprising:

• a loom-like machine;
• a hopper connected to the loom-like machine for receiving and then feeding individual tubes into a trough;
• a ram for advancing the tubes along the trough;
• guide tubes which are moved up and down and in concert with the ram, and wherein the guide tubes wrap a first wire around a first semi-periphery of the tubes near the ends of each tube and a second wire around the remaining semi-periphery of each tube;
• a mandrel for rolling the tubes into a mat and for firmly holding the tubes in place while adding a rope of pliable plasticized cordierite at each end of the tubes to build a continuous end wall that is sealed about each tube;
• wherein the mandrel continues rolling the mat to a desired length of tubes forming a diameter of the monolithic cross flow particulate trap;
• means for cutting the mat at the desired length of tubes;
• means for sintering the cut mat to obtain a porous monolithic module;
• and
• means for finish machining the mat.

An apparatus for manufacturing porous ceramic tubes having a slightly enlarged outside diameter at each end of the tubes and wherein the tubes have an internal passage, comprising:

• an internal die member having a first diameter substantially equivalent to the desired diameter of the tubes at a first position;
• a second diameter of the internal die member larger than the first diameter for producing an enlarged diameter in the tubes at the second position;
• a lip seal located near the second diameter for hermetically sealing a cavity formed by the second diameter;
• a valve controlled passage connected to the cavity;
• a hollow cylindrical mandrel located within the internal die member having a clearance between the hollow cylindrical mandrel and the first diameter, wherein a radial clearance is equal to the desired wall thickness of the tubes;
• and
• means for controlling the valve in the first position to provide pressure in the cavity formed by the second diameter to assure the internal die member is vented thereby permitting the tubes to emerge and remain at the diameter of the first diameter;
• and
• means for controlling the valve in the second position to create a high vacuum with the cavity formed by the second diameter forcing the emerging tube to expand until restrained by the wall of a second diameter.

An apparatus for manufacturing porous ceramic tubes having a slightly enlarged outside diameter at each end of the tubes, comprising:

• a die having a first fixed internal diameter having substantially the dimensions of the outside diameter used for the bulk of the tube length wherein filtration thought the porous walls occurs;
• a second diameter of the internal die member larger than the first diameter for producing enlarged diameters of the tubes at certain locations;
• a mandrel used to define the internal diameter having an axially slideable small tubular member having an integral head that has substantially the same diameter as desired for the internal diameter used for the bulk of the tube length;
• a short length of elastomer of similar diameter as the actuator head and positioned between said head of said actuator member and the body of the hollow mandrel;
• wherein said actuator member having a first axial position wherein the elastomer is under no axial load and has a first diameter that is substantially the same as the desired internal diameter of the extruded tube for the bulk of its length;
• wherein said actuator having a second axial position wherein the elastomer section is axially compressed to increase its diameter to a second dimension that will cause the extruding tube outside diameter to be enlarged by the amount required to force the plasticized material being extruded through the annulus defined by the inside diameter of the second diameter and the outside diameter of the expanded elastomer;
• means for pinching off the tubes to cut into the desired lengths and to pinch closed the ends of the tubes;
• and
• means for sensing the position of the extruded tube to control the internal actuator member and the pinch-off device.

A method of manufacturing monolithic cross flow porous particulate traps of plasticized material such as a mixture of fine cordierite ceramic powder or the like and a powdered plastic, comprising the steps of:

• extruding the plasticized material between a projecting die member having an enlarged head, and an axially movable honeycomb die member and/or honeycomb walls to define a wall thickness for passages wherein the enlarged heads of the projecting die members are evenly aligned with the honeycomb walls and axially movable honeycomb die members to form honeycomb sections;
• guiding said extruded honeycomb sections to maintain a substantially equal clearance gap between the passages in the honeycomb section;
• sensing when the end walls should commence;
• moving the axially movable honeycomb die member and honeycomb walls from a first position to a second position when extrusion of the clearance gap should terminate thereby terminating the clearance gap and commencing end walls;
• and
• processing the extruded material to obtain porous refractory honeycomb sections.

A method for manufacturing a monolithic cross flow particulate trap module of porous ceramic material in a loom-like machine, comprising the steps of:

• placing a plurality of sintered tubes having porous walls of lengths equal to that desired for the finished trap module into a hopper of the loom-like machine;
• moving the tubes individually and laterally from the hopper into a guideway of the loom-like machine;
• feeding the tubes individually along the guideway;
• wrapping a first wire around the semi-periphery of the tube and a second wire around the remaining semi-periphery of the tube at each end of said tube;
• forming the wrapped tubes into a mat with the loom-like machine, wherein the tubes are held firmly in place while spaced apart by the diameter of the wires;
• rolling the mat around a small mandrel while adding and squeezing lengths of pliable plasticized material between each turn at the vicinity of the first and second wires at each end of the tubes to build a continuous end wall that is sealed about each tube;
• parting the mat when the desired number of tubes are in place;
• sintering the rolled assembly to obtain a porous monolithic module;
• and
• machining the module to final dimensions.

A method for manufacturing a monolithic cross flow particulate trap of porous material comprising the following steps of:

• obtaining individual porous ceramic tubes having a slightly enlarged outside diameter near each end of the tubes and wherein the internal passages of each tube are blocked at each end;
• assembling a plurality of the tubes into a tight bundle, and wherein the slightly enlarged outside diameters at each end of the tubes provide a small clearance between the outside surfaces of each tube throughout the bulk of their length;
• placing said bundle of tubes into a fixture;
• pressing suitably shaped discs of pliable plasticized ceramic over each end such that the pliable ceramic is densely fitted over the tubes;
• sintering the discs and tubes to form the monolithic trap module;
• and
• machining the trap to achieve finish dimensions and to open the blocked ends of each tube.

A method for manufacturing porous ceramic tubes having a slightly enlarged outside diameter at each end of the tubes and wherein the tubes have an internal passage, comprising the steps of:

• manufacturing the tubes by extruding plasticized ceramic material;
• forming the internal and external diameters of the tubes with a die orifice and mandrel;
• and
• enlarging both ends of the tube by creating a vacuum wherein the tube ends are forced outwardly enlarging said ends.

A method for manufacturing porous ceramic tubes having a slightly enlarged outside diameter at each end of the tubes and wherein the tubes have an internal passage, comprising the steps of:

• manufacturing the tubes by extruding plasticized ceramic material;
• forming the internal and external diameters of the tubes with a first die orifice and elastomer mandrel for the bulk of the length of the tube;
• and
• enlarging both ends of the tube by axially compressing the elastomer mandrel via a second die orifice to a larger diameter and wherein the tube ends are enlarged outwardly.