Method for manufacturing a furnace heat exchanger and plate assembly

A method of securing a heat exchanger unit for a furnace to a plate member, comprising the steps of:

• providing said heat exchanger unit as a relatively thin walled sheet metal structure defining a chamber for the flow of fluid to be in heat exchange relationship with the walls of said heat exchanger unit and at least one opening into said chamber through a wall of said heat exchanger unit;
• providing a plate member including an opening corresponding to said opening in said heat exchanger unit and defined by a curved perimeter flange projecting from a plane of said plate member;
• providing first apparatus comprising a set of radially movable jaw members, said jaw members including surface means engageable with said flange;
• inserting said flange through said opening in said heat exchanger unit;
• inserting a portion of said first apparatus including said jaw members through said opening in said plate member;
• actuating said jaw members to move radially outwardly into engagement with said flange;
• bending first portions of said flange with said jaw members into engagement with said heat exchanger unit at the periphery of said opening in said heat exchanger unit to form a joint between said heat exchanger unit and said plate member;
• actuating said jaw members to retract radially inwardly;
• withdrawing said first apparatus from said opening in said plate member;
• providing a second apparatus having a set of radially movable jaw members with surface means engageable with said flange at zones on said flange not forcibly bent by direct engagement of said jaw members of said first apparatus;
• inserting a portion of said second apparatus including said jaw members of said second apparatus through said opening in said plate member;
• actuating said jaw members of said second apparatus to move radially outwardly into engagement with flange;
• bending second portions of said flange interposed between said first portions with said jaw members of said second apparatus into engagement with said heat exchanger unit at the periphery of said opening in said heat exchanger unit to form a joint between said heat exchanger unit and said plate member;
• actuating said jaw members of said second apparatus to retract radially inwardly;
• and
• withdrawing said second apparatus from said opening in said plate member.

A method of securing a heat exchanger unit for a furnace to a plate member, comprising the steps of:

• providing said heat exchanger unit as a relatively thin walled sheet metal structure defining a chamber for the flow of fluid to be in heat exchange relationship with the walls of said heat exchanger unit, said heat exchanger unit having at least one opening into said chamber through a wall of said heat exchanger unit and a shoulder formed around the periphery of said opening in said heat exchanger unit;
• providing a plate member including an opening corresponding to said opening in said heat exhchanger unit and defined by a seamless perimeter flange projecting from the plane of said plate member;
• inserting said flange into said chamber through said opening in said heat exchanger unit;
• and
• bending said flange radially outwardly with respect to a central axis of said opening and axially with respect to said axis into engagement with an inner wall surface of said shoulder to form a substantially rigid leakproof joint between said heat exchanger unit and said plate member.

A method of securing a heat exchanger unit for a furnace to a plate member, comprising the steps of:

• providing said heat exchanger unit as a relatively thin walled sheet metal structure defining a chamber for the flow of fluid to be in heat exchange relationship with the walls of said heat exchanger unit and, at least one opening into said chamber through a wall of said heat exchanger unit delimited by a peripheral rim;
• providing a plate member including an opening corresponding to said opening in said heat exchanger unit and defined by a seamless perimeter flange projecting from the plane of said plate member, said flange defining a peripheral channel portion between the plane of said plate member and a distal end of said flange;
• inserting said flange into said chamber through said opening in said heat exchanger unit with said rim disposed in said channel portion and
• bending said distal end of said flange radially outwardly with respect to said channel portion and axially with respect to a central axis of said opening in said heat exchange unit into engagement with an inner wall surface of said heat exchanger unit at the periphery of said opening substantially without displacement of said rim to form a substantially rigid leakproof joint between said heat exchanger unit and said plate member.