Turning – Portable lathe for pipe turning
Reexamination Certificate
1999-05-27
2001-03-20
Tsai, Henry (Department: 3722)
Turning
Portable lathe for pipe turning
C082S128000, C082S130000, C082S131000
Reexamination Certificate
active
06202522
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a portable machine tool for preparing pipe workpiece ends for welding, in particular for beveling pipe ends.
BACKGROUND OF THE INVENTION
Portable machine tools for machining tubular workpieces such as pipes typically include a rotary cutting head on which there is mounted one or more cutter elements or bits that are advanced into engagement with the workpiece by advancing the cutting head along a central mandrel that supports the cutting head for rotation about and axial movement along the mandrel. The mandrel is secured to the workpiece by expandable or otherwise moveable workpiece engaging or locking elements that can be actuated by a tool operator to immobilize the tool relative to a tubular workpiece. Typically, in the case of pipe workpieces, the workpiece engaging elements are radially moveable blades or pins that frictionally engage the interior or exterior of a workpiece to lock the workpiece and tool together so that the cutting head can be precisely located relative to the end of the workpiece and manipulated to perform a machining operation, such as beveling or otherwise shaping the end of the workpiece in preparation for a subsequent welding procedure involving the workpiece.
In prior art devices of this kind, the drive motor is usually integrated with or connected to the tool such that the motor may drive the cutting head in rotation while the reaction torque between the cutting head and the motor is reacted back into the mandrel that is affixed to the workpiece. Various torque reacting schemes are described in the prior art to avoid reaction torque between a driving motor and a cutting head causing relative rotation between the motor (or the tool drive train) and the cutting head.
More recently, the use of single modular drive motor units, each including a driving head for engaging and driving various machine tools, including pipe end preparation tools, interchangeably with each other has become significant. In such arrangements, the driving head of the drive motor unit contains rotatable torque transmitting elements that are intended to engage rotary drive transmitting members on the various machine tools which enables the tools to be interchangeably used with a singular modular drive motor unit. This presents a problem, however, in reacting driving torque between a rotary cutting head of a portable machine tool driven by such a drive motor unit and the drive motor unit itself. Since the drive motor unit is a separate module that is quickly connectable and separable from the machine tool body, typical torque reacting schemes are not appropriate to restrain relative rotation between the drive motor unit and the mandrel shaft that is secured relative to the tubular workpiece.
The present invention is intended to solve this problem and to provide a portable machine tool for preparing pipe ends for welding that is compact, convenient to use, and can be utilized with a modular drive motor unit of the type described while restraining torque reaction movement of the drive motor unit relative to the mandrel shaft during operation of the tool.
BRIEF SUMMARY OF THE INVENTION
A portable machine tool for preparing pipe workpiece ends for welding in accordance with the invention includes a cutting head including one or more cutter element seat(s) on a forward side thereof and mounted on a mandrel shaft extending axially therethrough so that the cutting head can be both rotated about the mandrel shaft and moved axially along the mandrel shaft in a controlled manner. One or more cutter bit(s) is (are) provided on the cutter seat(s), each cutter preferably made in accordance with the cutter described herein.
Workpiece engaging elements are carried by the mandrel shaft for locking the mandrel shaft and cutting head relative to a pipe or tubular workpiece and a feed mechanism carried by the mandrel shaft cooperates with the shaft and the cutting head to advance and retract the cutting head in axially forward and rearward directions along the mandrel shaft when actuated. A rotary drive coupling carried by the cutting head is connectable with the drive head of a modular drive motor unit for transmitting driving torque between the driving head of the motor and the cutting head. In the preferred embodiment of the invention, the drive coupling is annular and the tool drive head also is annular. In use the tool drive head annulus fits over the drive coupling annular element.
In accordance with the invention, a torque reaction bar is secured to the mandrel shaft against relative rotation and includes a drive motor engaging member adapted to engage the drive motor to secure the drive motor against rotation relative to the mandrel shaft when the motor is connected to the drive coupling of the cutting head.
The feed mechanism is conveniently located for manipulation by the tool operator and may include an actuator element having handles for manipulation by the tool operator.
The torque reaction bar is quickly separable axially from the mandrel shaft by quick disconnect connectors to facilitate rapid assembly and disassembly of the drive motor unit from the cutting head. In the case of an annular drive head, the maximum diameter of the tool rearwardly of the drive coupling area engaged by the annular drive head of the drive motor unit does not exceed the inside diameter of the annular drive head so that the drive motor unit may be quickly assembled axially over the rearward side of the tool without interference when the torque reaction bar is removed from the mandrel shaft.
The forward side of the rotary cutting head is configured to provide one or more cutter bit or element seats radially extending along the forward face of the cutting head. The cutter bits may be located at various radial positions on the cutter seats to machine the end surfaces of various diameter pipes or tubular workpieces, and the seats may be inclined forwardly from the vertical to machine bevel surfaces on workpiece ends such as pipes and fittings.
Preferably, a cutter bit element used with the cutting head is configured so that it can be mounted at a single position on the cutter seat in any one of four orientations, each of which presents a sharpened cutting edge to the workpiece at the same cutting position during rotation of the cutting head. This is accomplished by forming the cutter so that it has four cutting edges symmetrically located with respect to fastener mounting apertures provided in the cutter. Thus, the cutter may be mounted on a respective seat by the fasteners in four different orientations, each of which presents a sharpened cutting edge at an identical position for performing a machining operation on a workpiece.
REFERENCES:
patent: 3051059 (1962-08-01), Davey
patent: 3421196 (1969-01-01), Reich
patent: 3813747 (1974-06-01), Hertel
patent: 3982451 (1976-09-01), Gilmore
patent: 4437366 (1984-03-01), Astle
patent: 5531550 (1996-07-01), Moruzzi
patent: 5810522 (1998-09-01), Parker
patent: 5941145 (1999-08-01), Marshall et al.
Bacon & Thomas PLLC
Tri Tool Inc.
Tsai Henry
LandOfFree
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