Geometrical instruments – Gauge – Movable contact probe – per se
Reexamination Certificate
1999-06-17
2001-06-05
Hirshfeld, Andrew H. (Department: 2859)
Geometrical instruments
Gauge
Movable contact probe, per se
C033S503000, C033S572000
Reexamination Certificate
active
06240651
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates in general to a coordinate measuring machine. More specifically, this invention relates to a coordinate measuring machine having an image processor and a probe detectable by the image processor.
Conventional coordinate measuring machines used in measuring an object typically include a sensing probe mounted to a moveable spindle. The sensing probe includes a shaft interconnecting a sensor and a contact tip. In making a measurement, the spindle positions the probe to where the contact tip contacts the object, which causes the sensor to deflect. The sensor may be a measuring type sensor or a switching type sensor. The measuring type sensor measures displacement as a function of the deflection of the sensor, whereas the switching type sensor generates a switching signal upon the sensor deflecting a predetermined amount. The shaft of either sensing type probe must be sufficiently rigid to transmit the loading force on the contact tip to the sensor. However, this rigidity requirement places a limit on how small the shaft and contact tip can be, which in turn restricts how small of a measurement can be taken.
Various coordinate measuring machines having non-contact sensors, such as image processors and/or lasers, have been proposed that are capable of taking smaller measurements than a typical sensing probe. However, the non-contact sensors are not as well suited as a probe for making certain type measurements, such as measuring the internal surface of a cylinder.
Still other coordinate measuring machines having an image processor and a flexible non-sensing probe have been proposed. The image processor and non-sensing probe are arranged on a single spindle in a manner such that the non-sensing probe is detectable by the image processor. In making a measurement, the image processor detects the position of the non-sensing probe when the non-sensing probe is placed in contact with the intended measurement object. The non-sensing probe includes a shaft and contact tip integrally formed from a fiber-optic material. Because the shaft of the non-sensing probe need not exhibit load transfer capabilities, the size of non-sensing probe can be relatively small as compared to a typical sensing probe. Consequently, a coordinate measurement machine utilizing an image processor and non-sensing probe combination is capable of making smaller contact measurements than can a coordinate measurement machine utilizing a typical sensing probe. However, due to the brittle nature of the non-sensing probe, the shaft of the non-sensing probe is susceptible to breaking under normal use conditions. Consequently, the non-sensing probe may have to be replaced a number of times during the normal course of a measurement process. In replacing the non-sensing probe, the contact tip portion of the non-sensing probe must be positioned in the focus plane of the camera. The replacement of probe typically requires at least some form of manual support. Consequently, these types of machines generally cannot operate for lengthy periods of time without the need for operator assistance.
Another concern associated with the non-sensing probe is the build up of static forces between the contact tip portion of the non-sensing probe and the measurement object, which cause the contact tip to cling to the measurement object. This clinging phenomenon may cause the contact tip to break from the probe when attempting to separate the probe from the object.
Additionally, dust or other particles may stick to the contact tip, which may cause inaccuracies in the measurements taken.
Furthermore, because the non-sensing probe and image processor are mounted to a common spindle in a “fixed” relationship relative to one and other, it is difficult to hold the contact tip portion in focus when placing the contact tip in contact with the object. Also, it may be desirable to operate the image processor independent of the non-sensing probe when in making certain measurements. However, in order for the image processor to directly make a measurement of an object, the non-sensing probe must be removed from the spindle. The removal and the subsequent replacement of the non-sensing probe from and to the spindle add to the time and cost of the measurement operation.
One objective of this invention is to provide means for automatically repairing the non-sensing probe. Another objective of this invention is to provide means for cleaning the non-sensing probe. Additionally, it is an objective of this invention to provide means for dislodging the non-sensing probe from a measurement object. Furthermore, it is an objective of this invention to provide means for moving the non-sensing probe and image processor relative to one and other. Still further, it is an objective of this invention to reduce the likelihood of damage to the non-sensing probe while maintaining detection of the non-sensing probe by the image processor.
SUMMARY OF THE INVENTION
This invention concerns a coordinate measuring machine for measuring an object. The machine comprises a support platform for supporting the object. A non-contact scanner and a probe detectable by the non-contact scanner are supported by the support platform. The probe includes a shaft having a contact end portion. The contact end portion includes a tip for contacting the object. The tip may include at least one stylus for contacting the object
The machine may further comprise heating means proximate the support platform for forming the tip by heat transferred from the heating means to the contact end portion.
Additionally, the machine may comprise cleaning means proximate the support platform for cleaning the tip.
Also, the machine may comprise dislodging means proximate the tip for dislodging the tip from the object.
Furthermore, the machine may comprise drive means connected to at least one of the non-contact scanner and the probe for moving the non-contact scanner and the probe relative to one and other.
The machine may also comprise a fiber-optic ring adapted for receiving light from a light source and proximate the probe for illuminating the tip, which better enables the non-contact scanner to detect the tip.
Preferably the probe is formed of a fiber-optic material. Alternatively, the probe may be formed of a suitable non-fiber-optic material.
Various objects and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiments, when read in light of the accompanying drawings.
REFERENCES:
patent: Re. 33774 (1991-12-01), Gurny
patent: 4642897 (1987-02-01), Kirsch
patent: 5517124 (1996-05-01), Rhoades et al.
patent: 5628922 (1997-05-01), Chen
Brossette Frank
Hombach Stefan
Schroeder Mario
Hirshfeld Andrew H.
MacMillan Sobanski & Todd LLC
Mycrona GmbH
Smith R A
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