Method and apparatus for making a hydrocyclone separation chamber

A method of forming a frusto-conical tubular member with a seamless, smooth frusto-conical interior wall surface, said frusto-conical tubular member being incrementally formed from an elongated tube member of metal material of known ductility and yield strength with a cylindrically shaped wall of specific thickness by the sequential expansion of contiguous length segments of said cylindrical tube member and wherein said tube member is uniformly configured about a central longitudinal axis, said method comprising the steps of:

• (a) disposing one end of said tube member into a female die member where the female die member defines an interior frusto-conical wall surface configured about a cone axis and having a cone angle of 10.degree. or less so that the central longitudinal axis of the tube member is in coaxial alignment with the cone axis of the interior frusto-conical wall surface of said die member;
• (b) applying hydraulic pressure to the interior of said tube member while said tube member is disposed in said female die member at a level of hydraulic pressure which is greater than the yield strength of said metal material of the tube member to radially expand the wall of the tube member;
• (c) limiting the radial expansion of said tube member to a predetermined length where the wall of the tube member is brought into a conforming relationship with the interior wall surface of said female die member and thereby form a frusto-conical first length segment of tubular member;
• said predetermined length being selected with respect to the ductility and wall thickness of said tube member of metal material and the cone angle of said frusto-conical wall surface so that the tensile strength of the tube member is not exceeded during the expansion of said first length segment;
• (d) annealing said tube member after said radial expansion;
• (e) disposing said tube member into a female die member where a second length segment adjacent to the first length segment is unrestricted relative to said interior wall surface of said last mentioned female die member and said first length segment is restricted by the frusto-conical wall surface of said first mentioned female die member;
• (f) re-applying hydraulic pressure to the interior of said tube member and limiting the radial expansion of said annealed tube member to said second length segment so as to allow the radial expansion of the cylindrical portion of said tube member along said second length segment into conforming engagement with the interior wall surface of said last mentioned die member to form a second frusto-conical length segment which is contiguous and continuous with said first frusto-conical length segment with said first and second length segments in combination defining a tubular member with a single continuous smooth frusto-conical interior wall surface.

A method of forming a frusto-conical tubular member with a seamless smooth frusto-conical interior wall surface, said frusto-conical tubular member being incrementally formed from a metal tube member of ductile material with a cylindrically shaped wall by the process of:

• forming said tube member in a first female die member which has a pair of ends and a die cavity extending to said ends and defined by an interior frusto-conical wall surface along a first wall segment configured about a cone axis with a cone angle of 10.degree. or less and having a divergent end portion at one end of the die member and a convergent end portion at the other end of said die member and an interior wall surface along a second wall segment, and where the tube member has a length of tubing which is unconfined in one of said wall segments,
• in a first step applying hydraulic pressure to the interior of the tube member to provide sufficient force to expand said tube member along the unconfined length of tubing while restricting the expansion of said tube member along the other of said wall segments to prevent rupture of the wall of said tube member;
• in a second step, annealing said tube member in its first expanded condition to restore its metallurgical properties;
• in a third step, placing said tube member, in its first expanded condition after annealing, in a second female die member which has a second pair of ends and an interior frusto-conical second wall surface extending from one of said second pair of ends to the other end of said second pair of ends and which is provided with a greater length than said first wall segment and arranged so that in said first expanded condition, the tube member has an unconfined second length segment along said second wall surface and where such forming is achieved by applying hydraulic pressure to the interior of the tube member to provide sufficient force to further expand said tube member from its first expanded condition along the unconfined second length segment while restricting expansion of said tube member in said first expanded condition along the unconfined length to prevent rupture of the wall of the tube member in the second expanded condition;
• and
• in a fourth step, annealing said tube member.

A method of forming frusto-conical tubular member to obtain a seamless, smooth frusto-conical interior wall surface, said tubular member being formed from an elongated tube member of ductile metal material configured uniformly about a central longitudinal axis and having a pair of ends and a cylindrical tubular wall, said method including the steps of:

• disposing one end of said elongated tube member into a female die member having an interior frusto-conical first wall surface configured about a cone axis with a taper angle relative to the cone axis of the die member over a first length segment of the die member and having a second wall surface with a cylindrical shape over a second length segment of the die member contiguous to said first length segment, and where the central axis of the elongated tube member is in substantially coaxial alignment with the cone axis of the interior frusto-conical wall surface of said female die member, and where the cylindrical tubular wall of the tube member is spaced from the wall surfaces of said first and second length segments;
• applying hydraulic pressure to the interior of said tube member while said tube member is disposed in said female die member at a level of hydraulic pressure which is greater than the yield strength of the tube member to obtain an outward radial expansion of the wall of the tube member to conform to the wall surfaces of said first and second length segments in the die member;
• during the step of applying hydraulic pressure, restricting the radial expansion of the wall of said tube member along the first and second length segments of said interior wall surface in the die member to allow limited radial expansion of the wall of said tube member into conforming engagement with said first and second wall surfaces over said first and second length segments without bursting said wall and thereby to form an expanded frusto-conical length segment and a contiguous expanded cylindrical length segment of said tube member;
• said first and second length segments being selected with respect to the angle of taper of said frusto-conical wall surface, the diameter of the female die member, the ductility and the wall thickness of said tube member such that the tensile or burst strength of the tube member is not exceeded during the radial expansion and wherein the taper angle of said frusto-conical interior wall surface of the die member is less than 5.degree. relative to said cone axis and thereafter annealing said tube member.