Header for a heat exchanger, and method of making the same
A header for a heat exchanger includes a first and a second cylindrical portion. The first cylindrical portion has a first diameter, and extends over a first length portion of the header. The second cylindrical portion has a second diameter that is smaller than the first diameter, and extends over a second length portion of the header. Tube receiving slots are arranged along the first length portion. An end cap is received into an open end of the first cylindrical portion, and is joined thereto to seal a first end of the header. An open end of the second cylindrical portion is arranged at a second end of the header opposite the first end to allow for fluid flow into or out of the header. A circumferential bead is located between the first and second cylindrical portions, and extends radially outward of the first cylindrical portion.
1. A method of making a header for a heat exchanger, comprising:
forming a cylindrical tube from a sheet of aluminum material;
piercing a plurality of tube receiving slots through a wall of the cylindrical tube;
forming a circumferential bead into the cylindrical tube at a location between a first open end of the cylindrical tube and a nearest one of the plurality of tube receiving slots to the first open end, forming the circumferential bead comprising,
clamping a portion of the cylindrical tube within a die with a clamping force sufficient to resist axial displacement of the cylindrical tube during the forming operation, at least one of the tube receiving slots being located within said portion,
receiving protrusions extending from the die into the at least one of the tube receiving slots located within the clamped portion,
applying an axial force to the cylindrical tube at the first open end, and
displacing a portion of the tube wall into a recess provided within the die at a location immediately adjacent the clamped portion; and
reducing in diameter that portion of the cylindrical tube between the first open end and the circumferential bead.
2. The method of claim 1 , further comprising inserting an end cap into a second open end of the cylindrical tube opposite the first open end.
3. The method of claim 1 , further comprising forming a hose bead into the first open end of the cylindrical tube.
4. The method of claim 1 , wherein piercing a plurality of tube receiving slots comprises:
clamping an outer surface of the cylindrical tube within a die;
internally pressurizing the cylindrical tube using a fluid; and
displacing a plurality of punches in a radially inward direction of the cylindrical tube to pierce through the wall of the cylindrical tube.
5. The method of claim 4 , wherein displacing a plurality of punches in a radially inward direction of the cylindrical tube to pierce through the wall of the cylindrical tube forms inwardly directed flanges surrounding each of the plurality of tube receiving slots.
6. The method of claim 1 , wherein piercing the plurality of tube receiving slots occurs prior to forming the circumferential bead and prior to reducing in diameter that portion of the cylindrical tube between the first open end and the circumferential bead.
7. The method of claim 1 , wherein reducing in diameter that portion of the cylindrical tube between the first open end and the circumferential bead comprises:
placing the cylindrical tube within a die so that a surface of the circumferential bead located furthest from the first open end is disposed against a surface of the die;
moving a ram towards the die from the open end of the cylindrical tube, thereby displacing a portion of the cylindrical tube between the open end and the circumferential bead into an annular groove of the ram; and
applying a resistive force against said surface of the circumferential bead disposed against the die to prevent axial movement of the cylindrical tube while moving the ram.