Boiler tube bank repair
OwnerMark W. Hillestadinventor
Life of this patent
Estimating the term…
Abstract
A method and apparatus for repairing boiler tube walls by cutting out and replacing a worn or damaged section thereof involves the use of a power tool having a rotary milling head specially adapted to remove membrane material from between tube ends which are exposed when the damaged section is removed and optionally to simultaneously bevel the end of a tube as membrane material is being removed. The method and apparatus of the invention allows for the rapid and precise removal of membrane material from between the exposed tube ends to facilitate subsequent beveling and welding operations or for concurrent beveling and membrane removal, while substantially reducing the risk of weakening or damaging the tube wall by avoiding excess removal of material therefrom.
Claims30
A motor-driven tool for removing membrane material from between tube ends of a tube wall, comprising:
- a motor operatively connected to an output shaft and a rotary milling head mounted to said output shaft;
- said rotary cutting head including a cylindrical body, said rotary milling head further including a pilot rod adapted to be inserted into a tube end of the tube wall to position and stabilize said milling head during milling of the membrane material, and an annular recess radially located between said pilot rod and said cylindrical body,
- said rotary milling head having a plurality of cutting blades disposed circumferentially around the rotational axis thereof;
- said cutting blades each including a cutting edge collectively defining an annular cutting sweep having an inner radius which is about equal to the outer radius of a tube of the tube wall and an outer radius which is about equal to the sum of the outer radius of said tube wall plus from about 50 to 100 percent of the width of the membrane material between adjacent tubes of said tube wall;
- and
- one or more cutting blades disposed within said recess for bevelling said tube end.
A motor-driven tool for removing membrane material from between tubes of a tube wall and for beveling the end of a tube, comprising:
- a motor operatively connected to an output shaft and a rotary milling head mounted to said output shaft;
- said rotary milling head having a generally cylindrical body with a plurality of membrane cutting blades disposed circumferentially around the rotational axis at one axial end thereof, and
- mount means for removable attachment of said milling head to said shaft at the other axial end thereof;
- the cutting edge of said membrane cutting blades collectively defining an annular cutting sweep having an inner radius which is about equal to the outer radius of a tube of said tube wall and an outer radius which is about equal to the sum of said outer radius of said tube plus from about 50 to 100 percent of the width of the membrane between adjacent tubes of said tube wall;
- said milling head having a recess with generally cylindrical walls, said cylindrical recess having an axis coincident with the rotational axis of said milling head and a diameter and depth sufficient to receive said tube of said tube wall to allow removal of said membrane material;
- and
- one or more bevel cutting blades disposed within said recess for beveling said tube end.
A milling head for a motor-driven tool for removing membrane material from between tubes of a tube wall and for beveling the end of a tube, comprising:
- a rotary milling head having a substantially cylindrical body containing a plurality of cutting blades disposed circumferentially around the rotational axis thereof;
- said blades each including a cutting edge which collectively define an annular cutting sweep,
- said rotary milling head further including an attached pilot rod adapted to be inserted into a tube end of said boiler tube wall to position and stabilize said milling head during the milling operation, and an annular recess radially located between said pilot rod and said cutting-blades, said recess having a depth sufficient to allow removal of said membrane material between adjacent tubes of the tube wall to a depth which is at least equal to the depth of a bevel which is to be milled at said tube end, said pilot rod having a cylindrical axis coincident with the rotational axis of said milling head, and
- one or more bevel cutting blades disposed within said annual recess for beveling said tube end.
A milling head for removing membrane material from between tubes of a tube wall and for beveling the end of a tube of the tube wall, comprising:
- a substantially cylindrical body with a plurality of membrane cutting blades disposed circumferentially around the rotational axis of one axial end thereof;
- the cutting edge of said membrane cutting blades collectively defining an annular cutting sweep having an inner radius which is about equal to the outer radius of a tube of said tube wall and an outer radius which is about equal to the sum of said outer radius of said tube plus from about 50 to 100 percent of the width of the membrane between adjacent tubes of said tube wall;
- said milling head having a recess with generally cylindrical walls, said cylindrical recess having an axis coincident with the rotational axis of said milling head and a diameter and depth sufficient to receive said tube of said tube wall to allow removal of said membrane material;
- and one or more bevel cutting blades disposed within said recess for forming a bevel on said tube end.
A method for removing membrane material from between tubes of a tube wall and for beveling the end of a tube, comprising:
- removing membrane material from the areas immediately adjacent opposite sides of an exposed tube end using a motor-driven tool having a rotary milling head, and beveling said exposed tube end using said rotary milling head, whereby the membrane removal and beveling is achieved using a single tool.
Dependencies are inferred from the claim text.