Tube making machine with diameter control and method
A spiral pipe forming system which includes automatic diameter or dimension sensing and control.
This application claims the benefit of U.S. Provisional Application No. 61/011677, titled “Tube Making Machine with Diameter Control and Method,” filed Jan. 18, 2008, inventor William J. Kephart, which application is hereby incorporated by reference.
I. BACKGROUND OF THE INVENTIONA. Field of the Invention
The present invention relates to machines and methods for making spiral pipe from strips of sheet metal and, in particular, to machines and methods for accurately monitoring and controlling the diameter of such pipe. As used here, “pipe,” tube” and “conduit” are used interchangeably.
B. Description of the Related Art
Commonly assigned U.S. Pat. No. 3,940,962 describes a three-roll conduit forming mill and diameter control of Pacific Roller Die Company, Inc. The '962 patent is incorporated by reference in its entirety. As described in the '962 patent, the adjacent spiral edges of a strip which forms a spiral conduit are joined by interlocked edge flanges which are pinched or crimped tightly together by upper and lower lock-up rolls. The radial positioning of this pair of rolls relative to the conduit axis controls the diameter of the conduit. Thus, when the rolls are simultaneously raised, i.e., moved radially inward relative to the axis of the conduit, the diameter of the conduit increases When the rolls are simultaneously lowered, i.e., moved radially outward relative to the conduit axis, the diameter of the conduit decreases. The position of the lock-up rolls is changed by control screws which are manually turned using wrenches. The '962 patent indicates the diameter changes effected by such movement are minor and occur gradually. For instance, in a machine for making 1 to 36 inch conduit, such adjustments may be used to effect diameter changes of approximately ±¼ (one-fourth) inch.
The '962 patent also discloses the feasibility of making the adjustment automatic, by including means for monitoring the diameter, such as a belt or loop detector, which, when it senses a given diameter deviation would activate a servomechanism which in turn lowered or raised the lock rolls to correct the deviation.
II. SUMMARY OF THE INVENTIONIn one aspect, the present invention is embodied in a mill for forming a spiral pipe, comprising: apparatus for forming a spirally wound sheet, the apparatus including inner and outer pressure rolls engaging and crimping together adjacent edges of the spirally wound sheet; a sensing system for monitoring changes in the diameter of the spirally wound sheet as it is formed and responsively generating signals including information regarding changes in diameter; and a system responsive to the output signals for moving the inner and outer pressure rolls in unison radially inward or outward relative to the axis of the pipe to offset change in diameter.
In another aspect, the present invention is embodied in a method of forming a spiral pipe with diameter control, comprising: forming a spirally wound sheet having adjacent edges; crimping adjacent edges of the sheet together; monitoring the diameter of the spirally wound sheet for changes therein; responsive to change in the diameter, generating signals including information regarding changes in diameter; and responsive to the signals, moving the adjacent edges of the spirally wound sheet together radially inward or outward relative to the axis of the spirally wound sheet to offset the change in diameter.
As is well known and as described more fully in U.S. Pat. No. 3,940,962, the roll former 12 comprises a carriage 22 which is supported by casters 24 so that the oblique angle formed between the roll former and the three roll system can be varied. The carriage 22 is an elongated frame which mounts a plurality of corrugating rolls 10, arranged in a plurality of stands of matched pairs of upper and lower rolls. The rolls are horizontally aligned so that a strip 1 which is input to the roll former 12 passes through the upper and lower rolls of each stand and is deformed thereby into a corrugated profile, then exits the roll former and enters the three roll system 14.
The operation of the three roll system 14 is also well known and thus is described in conjunction with the construction and operation of the diameter (or dimension) sensing and control unit 16 and the diameter or dimension sensor or monitor 15 of system 16. Referring to
The diameter or dimension control system 16 for the pipe forming mill 10 is depicted in
The external pressure roll 62 is mounted to shaft or piston 76 of hydraulic jack 78. Bidirectional movement of the jack piston 76, as indicated by arrow 82, moves the external pressure roll 62 radially inward (up) or outward (down). Synchronized inward or outward movement of the external pressure roll 62 and the internal pressure roll 54 shifts the position of the crimped edges of the pipe inward and outward relative to the pipe axis.
Referring further to
When the size of the pipe 3 changes, downward or counterclockwise pivoting of the pivot arm 36 is associated with decreases in pipe size, whereas upward or clockwise pivoting of the pivot arm is associated with increases in pipe size. The output from ultrasonic sensor 46 causes control box 84 to operate the internal and external pressure roll positioning devices in unison, and simultaneously move the internal pressure roll 54 and the external pressure roll 62 inward or outward relative to the pipe axis and thereby respectively increase or decrease the diameter of the pipe.
The present invention has been described in terms of preferred and other embodiments. The invention, however, is not limited to the embodiments described and depicted. Adaptation to other embodiments will be readily done by those of usual skill in the art, limited only by the claims appended hereto.
Claims
1. Apparatus for forming a spiral pipe, comprising: apparatus for forming a spirally wound sheet, the apparatus including inner and outer pressure rolls engaging and crimping together adjacent edges of the spirally wound sheet; a sensing system for monitoring changes in the diameter of the spirally wound sheet as it is formed and responsively generating signals including information regarding changes; and a system responsive to the output signals for moving the inner and outer pressure rolls in unison radially inward or outward relative to the axis of the pipe to offset change in diameter.
2. A method of forming a spiral pipe having controlled diameter, comprising: forming a spirally wound sheet having adjacent edges; crimping adjacent edges of the sheet together; monitoring the diameter of the spirally wound sheet for changes therein; responsive to change in the diameter, generating signals including information regarding the change; and responsive to the signals, moving the adjacent edges of the spirally wound sheet together radially inward or outward relative to the axis of the spirally wound sheet to offset the change in diameter.
Type: Application
Filed: Jan 16, 2009
Publication Date: Nov 5, 2009
Inventor: William James Kephart (Brentwood, CA)
Application Number: 12/321,370
International Classification: B21C 37/12 (20060101);