Metal deforming – Process – Tube making or reshaping
Reexamination Certificate
1999-09-21
2001-07-03
Tolan, Ed (Department: 3725)
Metal deforming
Process
Tube making or reshaping
C072S031050, C072S702000
Reexamination Certificate
active
06253595
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention relates in general to pipe bending apparatus, and more particularly to equipment for forming bends in large-diameter pipes such as the type utilized with pipelines carrying petrochemicals, and the like.
BACKGROUND OF THE INVENTION
There exists a network of pipelines throughout much of the United States for carrying both liquid and gaseous types of fuel. The pipelines generally constitute large 40-foot, 22-36 inch diameter sections that are welded together and buried underground. Of course, the pipelines follow the general contour of the earth. The path of the pipeline can also be detoured or otherwise routed around obstacles.
A major challenge to the pipeline industry is to join the ends of the individual pipes with a high-quality weld to ensure the strength integrity of the joined pipes, as well as to prevent voids or weak spots in the joint that could thereafter leak. Thus, rather than forming welded joints in the pipes to form angles, the pipes themselves are bent so as to follow the contour of the earth and circumvent any obstacle in the path of the pipeline. By bending the pipes instead of forming joints welded at an angle, the number of welds are minimized and the reliability of the pipelines is enhanced.
Because of the size of the pipes being bent, the pipe bending equipment is generally massive in nature and operated hydraulically. The movement of the pipe into the pipe bending equipment, as well as the apparatus for gripping the pipe and forming a bend therein, is all hydraulically operated under the control of an operator. Such pipe bending machines and corresponding apparatus are disclosed in U.S. Pat. No. 5,092,150 by Cunningham; U.S. Pat. Nos. 3,834,210 and 3,851,519, the disclosures of which are incorporated herein by reference. As is customary with large diameter pipes, a bend in each pipe is accomplished by making numerous small bends, each spaced from each other. With such pipe bending systems, the operator is in full control of the number of incremental bends to be made, the spacing between the incremental bends, as well as the extent of each incremental bend in the pipe. Experienced operators can efficiently control the pipe bending systems to form accurate bends in the pipes and minimize damaged or over bent pipes which result in a waste of time and the pipes themselves. When a baseline of pipe bending information is obtained by the operator, based on the particular type of pipe being operated upon, the operator can manipulate the manual controls in an attempt to repeat a number of incremental bends so that each bend is identical. While the repeatability of the formation of a number of bends is possible to a certain extent, errors and differences often occur due to the skill of the operator, fatigue, environmental conditions, etc.
It can be seen from the foregoing that a need exists for an automated pipe bending system that is controlled by a programmed processor to form incremental bends with a high degree of repeatability and accuracy. A further need exists for a programmed processor and associated equipment that is easily retrofit to an existing system to thereby automate the operation thereof Another need exists for a low-cost programmed system that enhances the repeatability and quality of pipe bends.
SUMMARY OF THE INVENTION
In accordance with the principles and concepts of the invention, there is disclosed pipeline bending apparatus and a method of operation thereof, which overcome the disadvantages and shortcomings of the corresponding prior art systems. In accordance with the preferred embodiment of the invention, a pipe bending system is disclosed, which is controlled by a programmed processor so that the quality and repeatability of the bends in a pipe are facilitated.
According to one form of the invention, a pin-up hydraulic cylinder and a stiffback hydraulic cylinder are controlled by a programmed processor. A sensor which senses the extent of the bend in the pipe provides information to the programmed processor. Other data stored in the memory of the processor includes the angle of each bend, including the amount of springback, the number of bends to be formed in the pipe, and the distance between each incremental bend. Hence, when the operator initiates a bend cycle, the processor automatically activates the stiffback hydraulic cylinder to move and thus position the pipe in a level position. The pin-up hydraulic cylinder is activated to clamp one end of the pipe into position. Next, the processor again activates the stiffback hydraulic cylinder to move and thus bend the pipe to a predefined angle, as measured by the angle sensing sensors. When the appropriate angle is reached, the processor allows the hydraulic pressure in the stiffback cylinder to be released, thus lowering the stiffback to its full down position. Also, the pin-up clamp is moved so as to release its grip on the pipe. Next, the processor controls drive rollers to grip the pipe and move it axially a certain distance in the pipe bending system, as measured by an encoder which transmits digital signals to the processor. When moved a predefined distance, the drive rollers are stopped, whereupon the processor commences to control the apparatus to form another incremental bend in the pipe. The number of incremental bends formed in the pipe are preprogrammed and thus the processor proceeds through each incremental bending operation until completed.
Because of the utilization of various sensors and feedback data, the programmed processor can control the pipe bending system so as to form highly accurate bends on a repeatable basis.
REFERENCES:
patent: 4080814 (1978-03-01), Eaton
patent: 4649726 (1987-03-01), Trammell et al.
patent: 5092150 (1992-03-01), Cunningham
patent: 5259224 (1993-11-01), Schwarze
patent: 5275031 (1994-01-01), Whiteside et al.
patent: 5305223 (1994-04-01), Saegusa
patent: 5481891 (1996-01-01), Sabine
patent: 5651638 (1997-07-01), Heggerud
patent: 5682781 (1997-11-01), Schwarze
patent: 5697240 (1997-12-01), Parker
Celesco Transducer Products, Inc., “Cable-Extension Position Transducer, PT8510” 1 sheet, dated Aug. 7, 1998.
CRC-Evans Pipeline International, Inc.
Sidley & Austin
Tolan Ed
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