Geometrical instruments – Gauge – Movable contact probe – per se
Reexamination Certificate
2000-01-05
2001-01-16
Bennett, G. Bradley (Department: 2859)
Geometrical instruments
Gauge
Movable contact probe, per se
Reexamination Certificate
active
06173504
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a measuring instrument and a measuring method, in which inner and outer dimension or a diameter of an object is measured by the distance between a pair of probes when the pair of the probes is abutted to the object to be measured while moving relatively; and to a probe for a measuring instrument that is most suitable for the inner dimension measurement.
2. Description of the Related Art
An inner and outer dimension measuring instrument, in which inner and outer dimension of an object is measured by the distance between a pair of probes when the probes are abutted to a surface of the object while moving relatively, is used.
According to the inner and outer dimension measuring instrument, the inner and outer dimension of the object is measured by the distance between the pair of the probes, so that it is possible to measure various sizes of objects, such as the diameters of a ring-shaped object, a diameter of a hole or the width of a groove which is formed on an object, and a thickness of an object.
Conventionally, for example, an inner and outer dimension measuring instrument
110
, shown in
FIG. 20
, is known as an inner and outer dimension measuring instrument.
The inner and outer dimension measuring instrument
110
is composed of: a body
111
; a table
112
mounted on the body
111
so that an object to be measured W is put thereon; and a pair of probes P
1
and P
2
extending upward from the surface of the table
112
on which the object W is put, and the probes respectively moved in respectively opposite directions A and B to abut to and separate from surfaces of the object W.
The body
111
is provided therein with a rail
115
extending along a moving direction of the probes P
1
, P
2
, and the pair of sliders
55
movably supported with respect to the rail
115
and respectively supporting the bottom ends of a pair of probes P
1
and. P
2
. The table
112
is provided on the upper face of the body
111
and has an X-Y table
113
to adjust the horizontal position of the object W, and a tilt adjusting table
114
to adjust a tilt of the object W against the probes P
1
and P
2
.
For example, in the measurement of the inner dimension of the object W, after the probes P
1
and P
2
approach each other, the object W is put on the table
112
. After that, the probes P
1
and P
2
are respectively moved in the directions A opposite to each other. While the probes P
1
and P
2
are abutted to the inner side of the object W, each position of the sliders
116
is read from a displacement detector (not shown), thus measuring the inner diameter of the object W as the distance between the pair of the probes P
1
and P
2
. Note that, in the measurement, force acting in a direction toward the object W is applied to the probes P
1
and P
2
through the sliders
116
, so that the contacting force is maintained between the object W and the probes P
1
and P
2
. As a result, the probes P
1
and P
2
can be surely abutted to the inner circumferential face of the object W.
Another inner and outer dimension measuring instrument
120
, shown in
FIG. 21
, is known.
The inner and outer dimension measuring instrument
120
is composed of: a body
121
, a table
122
mounted on the body
121
, a pair of rails
125
provided on the body
121
on both sides of the table
122
, a slider
126
provided on each of a pair of the rails
125
, an arm
127
attached to each slider
126
, and a pair of probes P
1
and P
2
respectively provided to the ends of the arms
127
. Similarly to the aforementioned table
112
, the table
122
has an X-Y table
123
and a tilt adjusting table
124
.
Similarly to the aforementioned inner and outer dimension measuring instrument
110
, for example, in the measurement of the inner dimension of the object W, after the probes P
1
and P
2
are moved in the directions A to separate from each other, each position of the sliders
126
is read from a displacement detector (not shown) when the probes P
1
and P
2
are abutted to the inner side-face of the object W, thus measuring the inner diameter of the object W as a distance between the probes P
1
and P
2
.
The following disadvantages, however, can be listed when the objects W having various sizes are measured with high accuracy by the aforementioned inner and outer dimension measuring instruments
110
or
120
.
Disadvantage 1
In the inner and outer dimension measuring instrument
110
, the table
112
has a multilayer structure composed of the X-Y table
113
and the tilt adjusting table
114
, so that each of the probes P
1
and P
2
should have a sufficient length to project above the table
112
from the slider
116
located under the table
112
. In consequence, when the probes P
1
and P
2
are abutted to the inner side-face of the object W at the predetermined contacting force, a difference may be occurred between the actual distance between the probes P
1
and P
2
and a measured value indicated on the displacement detector.
On the inner and outer dimension measuring instrument
120
, although the length of the probes P
1
and P
2
is shorter, the length of the arm
127
needs to be longer in order to measure any object W having various sizes. According to the extent of the length of the arm
127
, the arm
127
is flexed by the dead weight thereof and the contacting force of the probes P
1
and P
2
to the object W, thereby also producing a difference between the actual distance between the pair of the probes P
1
and P
2
and a measured value indicated on the displacement detector.
To resolve the aforementioned measuring errors, in the inner and outer dimension measuring instruments
110
and
120
, the measurement of the object W is carried out with a relative measurement in which a measured value is corrected with pre-measured standard sample.
For the reason that the flexure of the probes P
1
and P
2
or the arm
127
exerts an influence upon the measurement in these conventional inner and outer dimension measuring instruments
110
and
120
, the relative measurement is always needed irrespective of the required accuracy of the measurement of the object W, resulting in complicated processes for measuring the object W.
In the measurement using the longer probes P
1
and P
2
and the longer arm
127
, the absolute amount of the flexure is larger, so that the dispersion in the contacting force of the probes P
1
and P
2
exerts an influence upon the dispersion in the measured values, resulting in difficulties in the measurement with high accuracy.
Disadvantage 2
To properly measure the inner or the outer diameter of the object W by any one of the aforementioned inner and outer dimension measuring instruments
110
and
120
, after the object W is put on the inner and outer dimension measuring instrument, it is needed to perform two adjustments, that is, adjustment for aligning a measurement axis (an axis line on which the probe is moved) of the measuring instrument with a diametral position of the object W (a measuring position adjustment), and adjustment for correcting a tilt of the axis of the inner or outer diameter of the object W relative to an axis line perpendicular to the measurement axis (a tilt adjustment). In other words, the axis of the inner or outer diameter of the object W should be adjusted to intersect at right angles to the measurement axis.
For example, in the measurement of the inner diameter, as shown in
FIG. 22
, when the diametral position of the object W differs from the measurement axis of the measuring instrument, a space d between the pair of the probes P
1
and P
2
is smaller than a diameter D of the object W, so that the accurate measurement is impossible. As shown in
FIG. 23
, in order to properly measure the inner diameter (or the outer diameter) of the object W, the diametral position of the object W is needed to be aligned with the measurement axis of the measuring instrument.
As shown in
FIG. 24
, when the axis of the inner diameter (or the outer diameter) of the object W has a tilt with
Moriya Yoshio
Ohtsuka Yukiharu
Saruki Yoshio
Bennett G. Bradley
Mitutoyo Corporation
Webb Ziesenheim & Logsdon Orkin & Hanson, P.C.
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