Metal working – Method of mechanical manufacture – Electrical device making
Patent
1994-02-25
1995-11-14
Briggs, William
Metal working
Method of mechanical manufacture
Electrical device making
36447406, 409200, 451 5, B23Q 1526, B23C 306, B24B 4900
Patent
active
054654742
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an apparatus, such as a crankshaft miller, for machining a work into a product having a cylindrical circumference, and more particularly to a cylindrically machining apparatus capable of improving roundness in the circumference of a machined product.
BACKGROUND ART
A crankshaft miller of a type in which a milling cutter with the inner teeth being contacted with the outer surface of a work rotates at a high speed, thereby machining the journal of a crankshaft to have a cylindrical circumference, is known. A motion of the milling cutter is shown in FIGS. 14(a) to 14(d) in which the center c of the milling cutter 1 moves in the direction of an arrow d along a path (circle) b located at a predetermined distance r from the center a of a work WK. A plurality of tips 1a formed on the inner side of the milling cutter 1 rotates about the center c, thereby cutting the outer surface of the work.
The milling cutter 1 is moved under the control of a program prepared by an NC machine. In the NC program, the motion of the milling cutter is defined by a single command given by, for example,
In the command, "G02" indicates "arc interpolation designation", "X90. Y75." indicates "X and Y coordinates at the start point S and the end point E (same as the start point S) of the center c of the milling cutter 1" and "I0. J35." indicates "X and Y coordinates of the rotational center a relative to the start point S".
In machining the outer surface of the work WK such as a crankshaft, rigidity of the work varies with the position of the rotation. Accordingly, roundness of the circumference of the machined work WK varies as indicated by a contour C' in FIG. 15, which is deformed from a circle C, causing an error. To make the contour C' of the work WK coincident with the circle C by displacing inward or outward the segments e, f, g, and h of the contour C', the path through which the center of the milling cutter 1 moves must be corrected into a path b' having segments e', f', g', and h' as shown in FIG. 16 according to the deformation of the segments e, f, g, and h.
As mentioned above, commands used in an NC machine are such a command that "move along a circle of a fixed radius". The correction that is carried out by the command is limited to a correction of the milling cutter motion over the entire circle. It is impossible to correct each segment of the contour indicated by the path b'. With such a command, it is impossible to improve roundness of the contour of a machined work.
The present invention has been made in view of the above background and its object is to provide a machining apparatus in which a path of its cutting tool is corrected according to the commands different for each segment of the circumference of a work, thereby remarkably improving roundness of the resultant product.
DISCLOSURE OF INVENTION
To achieve the above object, there is provided a cylindrically machining apparatus for machining a work by turning a tool along a circumference of the work so that the circumference has a target radius, comprising detection means for dividing the circumference of the work into predetermined intervals and for detecting a difference between radius of the work after machined and a target radius thereof for each of the intervals; calculating means for correcting the position of the tool every predetermined rotation angle based on the radius difference detected by the detecting means, and for interpolation-computing a path of the tool based on the corrected position of each rotation angle; and control means for turning the tool along the path calculated by the calculating means.
With such a construction of the invention, the circumference of a work is divided into predetermined intervals and difference between the radius of a work after machined and the target radius for each of the intervals is detected. The position of the tool is corrected at every predetermined rotation angle according to the detected radius difference. A path of the tool is interpolation-computed accor
REFERENCES:
patent: 4294045 (1981-10-01), Enomoto et al.
patent: 4375670 (1983-03-01), Kralowetz et al.
patent: 4384333 (1983-05-01), Maecker
patent: 5238337 (1993-08-01), Nussbaumer et al.
Ikoma Akira
Kimura Tomohisa
Briggs William
Kabushiki Kaisha Komatsu Seisakusho
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