Self centering pipe axis laser guide

DETAILED DESCRIPTION The self centering laser guide of this invention is a mechanical device based on the principle that when three planar surfaces spaced 120 degrees apart intercept the walls of a cylinder the axis of the cylinder will be automatically determined.
The saddle of this invention is a device based on the principle that a series of rectangular members tangent to a cylinder throughout their length are parallel to the cylinder axis.
The self centering pipe axis laser guide assembly comprises three expanding link mechanisms spaced 120 degrees apart having a common base whose center line represents the central longitudinal axis.
The links are made up of parallel, radial, lever and axis links.
A laser module attached to the base has its output aligned with this base axis.
A lead screw is included in the base and is the drive mechanism for a spider lever and the lever links which rotate the radial links and offset the parallel link from the axis link.
The relative position of the spider lever is used as an indication of pipe diameter against scales calibrated for both inside and outside diameters.
A knob assembly possessing adjustable torque characteristics is connected to the lead screw and is rotated clockwise to expand the links or counterclockwise to retract the links.
In either case rotation is continued until excessive torque disengages the lead screw.
The pipe axis laser guide has the capability of locating the central axis in a variety of pipe diameters, although it is primarily used for diameters of two to seven inches.
Generally the pipe axis laser guide is inserted into the front end of a pipe in the retracted position and expanded until the parallel link edges contact the inside diameter of the pipe.
Slight pressure from the parallel links retain the unit in place with the centerline of the base in alignment with the axis of the pipe.
Unlike most current laser systems that position the laser beam to specific grade and then manually position the pipe axis to the beam, the laser guide of this device inherently positions the laser beam to the pipe axis and then the pipe is positioned to a specific grade if required with the aid of the saddle and inclination gauge