Geometrical instruments – Gauge – Internal
Reexamination Certificate
1999-02-10
2001-06-12
Fulton, Christopher W. (Department: 2859)
Geometrical instruments
Gauge
Internal
C073S037900
Reexamination Certificate
active
06243962
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method and apparatus for machining the interior diameter of a cylindrical bore, and more particularly to such a method and apparatus utilizing a non-contact gage mounted on the boring shaft to measure the diameter of the bore.
BACKGROUND OF THE INVENTION
It is known to use non-contact gages to measure critical dimensions of precision workpieces after intermediate or final machining steps have been accomplished. Measuring the workpieces is desirable to monitor the quality of the workpieces being produced, and also can provide information that may be used to extend the service life of the machining tools being employed.
One type of non-contact gaging device comprises a small-diameter nozzle positioned in close proximity to the workpiece surface to be measured. Compressed air is supplied to the nozzle and the escape of pressure from the nozzle is throttled by the workpiece. By measuring the back-pressure at the nozzle it is possible to determine with a high degree of accuracy the distance between the workpiece surface and the nozzle. One of the advantages of such a pneumatic gage is that a continuous stream of measurements may be taken as the gage moves relative to the workpiece.
U.S. Pat. No. 5,152,166 discloses a pneumatic measuring device wherein the gage is mounted on a rotating shaft which is inserted into a bore after the forming tool has been withdrawn therefrom. The nozzle of the gage is directed radially outward so that it describes a spiral pattern over the inner surface of the bore as the rotating shaft is advanced into the bore. The pneumatic gage can not be inserted into the bore until after the tool which formed the bore has been withdrawn.
U.S. Pat. No. 3,059,381 discloses an apparatus for honing the interior surface of a machined bore and having a pneumatic gaging device for monitoring the diameter of the bore. The gaging device is mounted at the end of an arm which extends adjacent the outer surface of a rotating shaft to which honing stones are fixed. During operation of the machine, the rotating shaft is repeatedly inserted into and withdrawn from the bore, the honing stones gradually increasing the internal diameter of the bore with each stroke. The arm carrying the pneumatic gage is also inserted into the bore with each stroke of the shaft so that the gage is brought into close proximity to the inner surface of the bore at one point on its circumference and takes a measurement of the bore diameter at that point. When the gage senses the desired finished diameter, the machine automatically terminates the honing process.
SUMMARY OF THE INVENTION
It is an objective of this invention to provide a method and apparatus for forming and measuring a cylindrical bore with a single stroke of a rotating shaft.
This objective is achieved by a boring apparatus having a rotating shaft with one or more metal cutting tools and a non-contact measuring device attached thereto for rotation with the shaft. By locating the measuring device on the shaft along with the cutting tools, the measuring device is advanced into the bore formed by the tools so that it is positioned to measure the inner diameter of the bore as the rotating shaft is advanced into the bore during the cutting stroke. Accordingly, a single stroke of the boring apparatus serves both to form a desired internal diameter and to measure the diameter formed during the cutting stroke. This avoids the more time-consuming and complicated procedure known in the prior art which requires the boring shaft to withdrawn from the bore and subsequent insertion of a separate gaging device.
It is a further objective of this invention to provide a method and apparatus for forming a cylindrical bore in a workpiece, measuring the diameter of the bore, and adjusting the position of the cutting tool in response to the measured diameter.
This objective is achieved by a boring machine in which a non-contact measuring device is mounted on a rotating shaft along with one or more tools which are held in positioning means for moving the tools radially with respect to the shaft so that the diameter of the bore formed by the tools may be varied. The tools are held in a first position intended to produce a desired diameter during a first cutting stroke as they are advanced through the bore. The measuring device is inserted into the bore during or at the end of the stroke so that it may determine the diameter formed by the tools. If the measured diameter deviates from the desired diameter, the positioning means repositions the tools as necessary to achieve the desired bore diameter on a subsequent cutting stroke.
The tools may be repositioned radially outward prior to the shaft and tools being withdrawn through the bore, thereby executing a second cutting stroke which enlarges the bore to the desired diameter. In the alternative, the tools may be retracted so that they do not contact the interior of the bore as the shaft is withdrawn, the tools being repositioned to form the desired diameter on subsequent bores.
In a preferred embodiment of the invention, the measuring device is a pneumatic gage mounted in a housing which projects radially outward a short distance from the circumferential surface of the shaft. The gage is adjustable in a radial direction with respect to the shaft in order to vary the range of diameters that may be measured. Air pressure is supplied to the gage through a passage extending through the interior of the shaft. The movable tools are actuated by a pneumatic/hydraulic positioning system which is also supplied with air through the passage.
REFERENCES:
patent: 2355316 (1944-08-01), Mestas
patent: 2669864 (1954-02-01), Brewster
patent: 2797576 (1957-07-01), Haines
patent: 2821049 (1958-01-01), Harris, Jr.
patent: 2851783 (1958-09-01), Peras
patent: 3059381 (1962-10-01), Greening et al.
patent: 3494078 (1970-02-01), Miyamoto
patent: 3864054 (1975-02-01), Eysel
patent: 5152166 (1992-10-01), Brock et al.
Elastic Deformation Improves Micropositioning, Design News, Feb. 1, 1982.
Heller Machine Tools Ltd. Internet Advertisement (Date Unknown).
Fulton Christopher W.
Samsomatic, Ltd.
Young & Basile P.C.
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