Turning – Portable lathe for pipe turning
Reexamination Certificate
2000-02-02
2001-07-10
Tsai, Henry (Department: 3722)
Turning
Portable lathe for pipe turning
C082S053100, C082S131000, C083S631000
Reexamination Certificate
active
06257110
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to tube cutters having a clamping means and wherein the saw rotates around the tube while cutting it.
2. Description of the Related Art
In the past tube cutters have had motors with saw blades in rotatable housings which rotate the saw around the outside diameter of the tube to be cut. However, little attention was paid to making precision cuts such that the tube has a square cut with no burrs, finishing marks, or other imperfections. Making precision cuts is particularly a problem with smaller diameter tubes since they bend and vibrate easily.
Clamping devices hold the tubing in place during the cutting procedure. However, in the past these clamping devices did not hold the tubes straight enough or firmly enough to keep the tubes perpendicular to the saw to ensure a square cut with no burrs, finishing marks or other imperfections. Further the clamping devices did not sufficiently dampen vibrations in the tubing to prevent vibrational movements from reducing the quality of the cut.
In the past the rotatable housing of the saws did not rotate around the tube with precision. There was not sufficient stiffness of the bearings of the rotatable housings to hold the saw blade in a plane. Further the stiffness was not sufficient to dampen vibrations in the housing, which would then transfer to the saw blade. Both of these conditions lead to a cut, which is not square, leaves finishing marks, burrs and other imperfections in the cut.
In the past centering the tube axis to the left or right with respect to the center of rotation of the blade in the rotatable housing was accomplished by moving the clamping device left or right relative the housing, but the clamping device was not sufficiently secured to the housing to hold it solidly in place and prevent movement or vibrations from detracting form the quality of the cut.
Further, in the past, the tube saws were rotated on the housing by hand thus applying uneven pressures of the saw blades on the tubes. The uneven force of the blade on the tubing promotes causes different cut rates in different portions of the tube. The uneven force on the blade promotes different vibration patterns in the tubing and in the saw blade and forces the tubing out of alignment at different amounts such that it is no longer square with respect to the blade. The differences in pressures on the blade result in different cut qualities around the circumference of the tubing. It is desired to have a uniform precision cut around the circumference of the tubing.
SUMMARY OF THE INVENTION
The invention relates to a tube saw for precision cuts of tubing wherein the tube saw produces a square cut with no burrs, finishing marks or other defects.
The tube saw comprises a clamp with a plurality of alternately sloped triangular clamping elements having opposing complementary facing hypotenuse surfaces for gripping a tube along its length in a plurality of positions for aligning the tubes held therein perpendicular to a saw while damping vibrations in the tubing. The tubing center is adjusted by a centering shaft to compensate for the clamps not being aligned exactly with the center of the housings axis of rotation. The clamping means is then fixed in position relative the housing with T-nuts to ensure a square cut and to limit vibrations.
A rotating circular saw blade driven by a motor is mounted on a housing and radially adjusted to a depth for cutting into the tube such that the saw blade cuts though to the tube inner wall. Then the housing is rotated 360 degrees around the tubing allowing the saw to cut the tubing around its circumference. The rotating housing has bearings providing axial and radial stiffness such that the saw is held firmly in position as it rotates around the tube and the vibrations of the saw are dampened by the bearing stiffness.
A servo motor having a gear housing provides an evenly applied force to the gear teeth on the rotating portion of the housing to rotate the saw around the tube. The evenly applied force of the servo motor moves the saw at an even rate around the tube for application of a uniform cutting pressure of the saw blade on the tube producing a high quality cut around the entire tube.
OBJECTS OF THE INVENTION
It is an object of the invention to make square cuts on tubing.
It is an object of the invention to eliminate burrs on the cut tubing.
It is an object of the invention to eliminate finishing marks on the cut tubing.
It is an object of the invention to hold the tubing with a clamp to reduce vibrations in the tubing while it is being cut resulting in a better cut.
It is an object of the invention to hold the tubing with a clamp so that the tube axis is perpendicular with respect to the saw blade plane for a square cut.
It is an object of the invention to center the tubing with respect to the axis of rotation of the saw blade rotation, to lock the tubing in that location, and to dampen vibrations in the housing assembly such that the tubing will receive a square cut.
It is an object of the invention to position the saw blade close to the clamp to reduce, bending a vibration in the tubing for a better cut.
It is an object of the invention to rotate the saw around the tubing without movement of the saw away from the plane of the cut and to dampen vibration of the saw blade as it rotates around the tube for a better cut.
It is an object of the invention to provide even force on the saw as it rotates around the tube for less vibration in the tubing and an even cut of the tubing.
It is an object of the invention to dampen vibration in the housing during rotation of the saw blade around the tubing.
It is an object of the invention to provide stiff bearings in the housing.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawing.
REFERENCES:
patent: 4791842 (1988-12-01), Olson
patent: 4813314 (1989-03-01), Kwech
patent: 4939964 (1990-07-01), Ricci
patent: 5189933 (1993-03-01), Ricci
patent: 5349751 (1994-09-01), Fahr
patent: 5549024 (1996-08-01), Ricci
patent: 5609081 (1997-03-01), Lin
patent: 5685996 (1997-11-01), Ricci
patent: 5993963 (1999-08-01), Pierce
Gardzinski Martin A.
Ricci Donato L.
Nikolai Mersereau & Dietz, P.A.
Ricci Donato L.
Tsai Henry
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