Optics: measuring and testing – By alignment in lateral direction
Reexamination Certificate
1999-09-20
2001-07-24
Font, Frank G. (Department: 2877)
Optics: measuring and testing
By alignment in lateral direction
C033S293000
Reexamination Certificate
active
06266143
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to pipe section alignment systems that employ a coherent energy beam and a target positioned to receive the beam, and more particularly to apparatus for releasably and integrally mounting the target to the pipe section being aligned.
The laying of strings of piping sections installing water lines or sewer lines, typically requires coaxial alignment of successive pipe sections. This involves the individual alignment of each pipe section as it is added to the pipe string. A well known and effective system for pipe section alignment includes a laser generating a coherent energy beam, positioned so that the beam is either coincident with or parallel to a longitudinal central axis of the pipe string.
As a pipe section is added to the string, its proximal end is joined to the string, and a transparent target with alignment markings is mounted near its distal end. The laser intersects the target to provide a visual indication of pipe section alignment, to provide a guide for moving the pipe primarily at its distal end to adjust the pipe section toward parallelism with the laser beam.
A variety of these systems are found in the prior art. For example, U.S. Pat. No. 4,968,147 (Shoemaker) discloses a target system including an annular base, an anchoring unit having several extended arms and a square target unit within the annular base. The base has a tapered end that can fit within the bell end of a pipe section, and an opposite flat edge that can abut the spigot end of the pipe section, in which event arms are provided for frictionally engaging the pipe interior. The annular base has holes to receive the corners of the target. Levels on opposite sides of the target facilitate angular adjustment of the base to align vertical and horizontal markings on the target.
U.S. Pat. No. 3,898,743 (Myeress) shows a resilient frame with an upper loop and two lower loops supporting a target, to enable mounting and dismounting of the target within a pipe section, by flexing the frame. The frame flexes to fit different pipe section diameters, in a manner that tends to center the target within the pipe. If desired, laser targets can be set in different positions within pipe sections using adjustable arms or legs, for example as shown in U.S. Pat. No. 4,681,439 (Shoemaker), U.S. Pat. No. 5,095,629 (Klemer et al) and U.S. Pat. No. 3,634,941 (Roodvoets et al).
While the above systems are satisfactory in many respects, they are subject to several disadvantages. Targets with adjustable legs, while accommodating several pipe section sizes, require time and skill to ensure their proper alignment. Typically they are recessed within the piping section and are not conveniently visible, requiring the operator to bend over near the open end of the pipe section to perceive the degree of alignment. Many of the targets are supported merely by gravity, subject to displacement if the pipe section is inadvertently jostled or subject to shock. Thin legs or frames such as those shown in Shoemaker and Myeress are subject to movement from such jostling or impact.
Therefore, it is an object of the present invention to provide a laser alignment target that is quickly and conveniently attached to a pipe section, yet held firmly so that it is not displaced by shock or vibration experienced by the pipe section.
Another object is to provide a means for mounting a laser alignment target as an end cap of a pipe section rather than recessed within the pipe section, to facilitate ease of visually determining pipe section alignment.
A further object is to provide an alignment structure for mounting and maintaining a target with respect to a pipe section, in a manner that continually tends to center the target within the pipe section and functions as a shock absorber between the pipe section and the target.
Yet another object is to provide, in a single device, a laser alignment target and an end cap for providing a substantially fluid tight seal at one end of a piping section.
SUMMARY OF THE INVENTION
To achieve these and other objects, there is provided an apparatus for sealing and aligning piping. The apparatus includes a fluid impermeable pipe alignment target that has a light transmissive interior section bearing pipe alignment indicia. The alignment target further has a peripheral section surrounding and substantially concentric with the interior section and defining a target mounting surface. The target is adapted for mounting in a selected position at an open end of an elongate pipe section. The apparatus further includes a compressible and fluid impermeable seal member positionable against the mounting surface over the circumferential length of the mounting surface. A retaining means secures and maintains the seal member in a compressed state between the mounting surface and a selected surface region of the elongate pipe section near the open end. The seal member forms a substantially fluid tight seal between the target and the pipe section. In the compressed state, the seal member tends to maintain the target in the selected position and further tends to radially center the target with respect to the pipe section.
Typically the pipe section is a circular cylinder, in which case the seal member is torroidal, and the target mounting surface and selected surface region are annular. The target, preferably disk-shaped, also is preferably transparent to enable an individual on the opposite side of the target from the laser source to readily ascertain where the beam impinges upon the target disk.
The retaining means can include a retaining frame that has an annular retaining surface and means for releasably securing the retaining frame adjacent the target with the retaining and mounting surfaces proximate one another. These surfaces preferably are inclined in opposite directions relative to the longitudinal axis, to provide a generally V-shaped annular channel for retaining the seal member. A rotatable handle, threaded onto a bolt that extends through the retaining frame and target, draws the retaining frame axially toward the target so that the retaining and mounting surfaces engage and compress the annular seal member, forcing it against the selected surface region of the pipe section. Retained under compression within the triangular arrangement of these surfaces, the seal member firmly secures the target with respect to the pipe section, with a holding force that is substantially uniform throughout the circumferential extension of the seal member. The preferred axial member is an elastically compressible gasket.
Several advantages arise from the uniform distribution of force. First, there are no force concentrations, such as would arise at the corners of a square target supported within an annular frame, or at the points where target-supporting legs engage the piping section. The holding force can be of substantially greater magnitude because it is spread about the entire circumference. The elastic restoring force of the seal member is applied uniformly over the target circumference, thus tending to center the target. Yet another advantage is that the seal member, when constructed of a fluid impermeable material, provides a fluid tight seal between the target and the pipe section. Thus, the target and seal member function as an end cap that seals an open end of a pipe section, preventing the entry of water or debris.
Another aspect of the present invention is a pipe alignment apparatus including a target with a light transmissive interior section bearing pipe alignment indicia, and a peripheral section surrounding the interior section and defining a target mounting surface. The peripheral section further defines a planar reference surface adapted to abut a planar edge at an open end of an elongate pipe section, to determine a longitudinal position of the target relative to the pipe section. A compressible alignment member is positionable against the mounting surface. A retaining means secures and maintains the alignment member in a compressed state between the mounting sur
Jahnke Darren M.
McCluskey, II James M.
Peterson David L.
Thompson Leslie P.
Brink's Mfg. Co., Inc.
Font Frank G.
Larkin Hoffman Daly & Lindgren Ltd.
Niebuhr, Esq. Frederick W.
Stafira Michael P.
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