Turning – Process of turning
Patent
1996-06-11
1998-07-14
Howell, Daniel W.
Turning
Process of turning
82 12, 408 2, B23B 4112
Patent
active
057787441
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a method and a device for position-exact and dimension-exact chamfering of a clamped pipe end with respect to the outer or inner diameter of the pipe, especially for producing a welding chamfer, which must be applied, in general, with great precision with respect to the inner surface of the pipe, in order to be able to produce a welding connection between abutting pipe ends with respect to all specifications. The manufacture of such a welding chamfer is problematic because a considerable deviation from roundness as well as wall thickness variations due to radial displacement of the inner diameter relative to the outer diameter may occur in seamless pipes. Even though welded pipes have no great wall thickness variation, these pipes may have a greatly oval contour and, in the area of the welding seam, may exhibit bulges at the interior and/or exterior. Furthermore, for seamless and welded pipes a diameter deviation is generally acceptable which, however, does not ensure an exact welding seam preparation without taking into consideration the actual inner or outer diameter of the pipe.
The deviation from roundness of the pipe can be compensated according to U.S. Pat. No. 3,724,303, in which a device for combined cutting and chamfering of pipe ends is disclosed, by arranging the chamfering tool on a workpiece holder which is elastically supported via a roller or a ball on the outer surface of the pipe. In this manner, an outer chamfer as well as an inner chamfer can be applied position-exact and dimension-exact relative to the outer circumference of the pipe. When it is desired to apply an outer and/or inner chamfer position-exact and dimension-exact relative to the inner surface of the pipe, the tool holder must be supported in a similar manner at the inner surface of the pipe. This known device thus operates according to the tracing method with a mechanical sensing device which is directly operatively coupled with the chamfering device.
This known device is disadvantageous because the machining process of chamfering is not dividable into a fast rough-machining, process and a slower finish-machining process so that the advance for the entire machining process must be based on the required surface quality to be produced with the finish-machining process. Accordingly, the machining time is unnecessarily long, because only a small cutting output is achievable. Furthermore, an irregular surface of the chamfer will result when the tracing device runs across cuttings or a welding seam bulge which negatively affects the quality of the chamfer to be produced.
It is an object of the invention to provide a method and device with which a pipe end can be chamfered position-exact and dimension-exact with respect to the outer or inner diameter of the pipe and with which the chamfer remains unaffected by a deviation from roundness, by wall thickness deviations, cuttings or welding seam bulges.
SUMMARY OF THE INVENTION
Based on this object, a method is suggested which inventively is performed such that first in a fast rough-machining process with great advance rate the chamfer is produced with a machining allowance for a subsequent finish-machining process, whereby a machining tool is first adjusted to the nominal or actual inner or outer diameter of the pipe and subsequently the chamfer is procuded position-exact and dimension-exact in a short finish machining process with low advance rate with the same or another chamfering tool as a function of the course of the outer or inner diameter along the circumference of the pipe determined with a sensing device.
The method for machining a chamfer at a pipe end, clamped in a radial clamping device, to exact positional and dimensional tolerances as a function of a measured course of an inner and an outer diameter of the pipe, according to the present invention comprises the steps of: end clamped in the radial clamping device; controlled manner a machining tool to the pipe end; inner diameter of the pipe and the actual outer di
REFERENCES:
patent: 3256754 (1966-06-01), Rivierre et al.
patent: 3724303 (1973-04-01), Rinaldo
patent: 4324049 (1982-04-01), Blose
patent: 4774753 (1988-10-01), Holy
patent: 5197361 (1993-03-01), Carreir
Braun Hans-Jorg
Mohn Gerhard
Howell Daniel W.
Maschinenfabrik Reika-Werk GmbH
Williams Mark
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