Organic compounds -- part of the class 532-570 series – Organic compounds – Sulfonate esters
Reexamination Certificate
2000-01-05
2001-10-23
Fulton, Christopher W. (Department: 2859)
Organic compounds -- part of the class 532-570 series
Organic compounds
Sulfonate esters
C033S561000, C033S503000
Reexamination Certificate
active
06307084
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a touch signal probe for measuring a surface position of a workpiece by contact, especially a vibrating touch signal probe for detecting vibration change caused when a contact portion of a stylus touches the workpiece. More specifically, it relates to a contact portion detecting mechanism of a vibrating touch signal probe for detecting a contact location of the contact portion against the workpiece.
2. Description of the Related Art
A height gauge (linear measuring machine), a coordinate measuring machine and a profile measuring machine are known as a measuring machine for measuring the configuration and dimensions of a workpiece. Various probes are used in the measuring machine for detecting the positional relationship of a measuring machine body and the workpiece. The probes can be grouped into a non-contact probe and a contact probe, or alternatively, a continuous measuring probe and a touch trigger probe.
An ultrasonic touch trigger probe disclosed in Japanese Patent Laid-Open Publication No. Hei 6-221806 is known as a contact touch trigger probe for the above coordinates measuring machine. As shown in
FIG. 10
, the touch signal probe
100
includes a stylus holder
101
, a stylus
102
and a piezoelectric element
103
. The stylus holder
101
is mounted to a stylus support moving in a three-dimensional space at a predetermined velocity vector in accordance with an external command (not shown). The stylus moves along with the stylus support and detects the contact against the workpiece, so that an edge position of the workpiece is detected by reading the coordinate in contact.
The stylus holder
101
is shaped into a tubular cylinder, and the stylus
102
is supported at the inner lower end thereof by a pair of engage pins
104
provided on a support point at an approximate axial center of the stylus
102
. A contact portion
102
A having a spherical surface to be abutted to the workpiece in measurement is attached to a lower end of the stylus
102
and a counter balance
102
B having the same weight as the contact portion
102
A is mounted to an upper end of the stylus
102
, so that the support point of the stylus holder
101
is consistent with a centroid of the stylus
102
.
A pair of grooves
105
as a attachment portion of the piezoelectric element
103
are cut on an outer circumference of the stylus
102
and two piezoelectric elements
103
having the same configuration are attached to the grooves
105
by an adhesive or the like with both ends being firmly adhered.
The piezoelectric elements
103
are disposed approximately symmetrically along an axial direction of the stylus
102
with the support point of the stylus
102
at the center thereof, the piezoelectric elements being divided into a vibrator
103
A for resonantly vibrating the stylus
102
and a detector
103
B for detecting a change in vibration of the stylus
102
.
The touch signal probe
100
vibrates the stylus
102
along an axial direction thereof by the vibrator
103
A. When the ball-shaped contact portion
102
A touches the workpiece, vibration of the stylus
102
is restricted by a contact force to change vibration status. Accordingly, edge position etc. can be detected by detecting the change in the vibration status by the detector
103
B.
However, since the change in the vibration status of the stylus
102
differs according to a difference in contact location (the part of the surface of the ball-shaped contact portion
102
A actually touching the workpiece) of the contact portion
102
A against the workpiece and deflection by the contact force of the contact portion
102
A, the touch signal probe
100
having the above-described arrangement is not suitable for a probe for conducting profiling measurement and continuous measurement where various parts of the contact portion
102
A touches the workpiece.
Specifically, as shown in FIG.
11
(A), when the contact portion
102
A touches the workpiece W in a direction orthogonal with the axial direction (vibrating direction) of the stylus
102
, the vibration status along the axial direction of the stylus
102
does not largely change even when the deflection against the workpiece W by a contact force F
1
of the contact portion
102
A increases.
On the contrary, as shown in FIG.
11
(B), when the contact portion
102
A touches the workpiece W along the axial direction of the stylus
102
, the vibration status of the stylus
102
largely changes even when the deflection toward the workpiece W by contact force F
2
of the contact portion
102
A changes only slightly. The status is shown in
FIG. 12
, where a detection signal V showing vibration status change of the stylus
102
changes gently relative to a change in deflection L as shown in graph G
10
. On the other hand, the detection signal V largely changes even against a small change of the deflection L.
Accordingly, when the touch signal probe
100
is moved together with the stylus support in a three-dimensional direction to conduct profiling measurement for measuring the configuration of the workpiece W, since the change in vibration status of the stylus
102
largely differs according to the contact location of the contact portion
102
A, non-ambiguous determination of the edge of the workpiece W is difficult according to magnitude of the vibration status change of the stylus
102
. Therefore, such ultrasonic touch signal probe
100
is not suitable as a probe for profiling measurement and continuous measurement of the workpiece W. Further, when the size of the probe is reduced, the rigidity of the stylus is reduced. Accordingly, axial resonance of the stylus cannot be maintained in the continuous measurement, thus resulting in decrease in sensitivity, i.e. deterioration in accuracy.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a contact location detecting mechanism for the above ultrasonic touch signal probe to be used for profiling measurement and continuous measurement for measuring configuration of the workpiece, which is capable of measuring a configuration of the workpiece with high accuracy.
A contact location detecting mechanism according to the present invention is for a touch signal probe having a stylus support for moving in a three-dimensional space by a predetermined velocity vector according to an external command, a stylus holder mechanically connected to the stylus support, a stylus supported by the stylus holder and including a contact portion to be touched to a workpiece at a pointed end thereof, a vibrator provided to a part of the stylus holder for resonantly vibrating the stylus in an axial direction thereof, and a detector provided to a part of the stylus holder for detecting a change in vibration by the vibrator, the touch signal probe detecting the change in vibration by the detector when the contact portion touches the workpiece, the contact detecting mechanism of a touch signal probe detecting the contact location on the contact portion to the workpiece. The contact detecting mechanism includes: a rotary motion generator for making a scanning rotary motion of the stylus on a plane orthogonal with an axis of the stylus by a predetermined radius and a predetermined angular velocity; a phase value detector for detecting phase value indicating a rotation position of the scanning rotary motion by the rotary motion generator; and a contact location detector for detecting the contact location of the contact portion to the workpiece based on a detection signal value detected by the detector and the phase value detected by the phase value detector while the contact portion touches the workpiece.
The rotary motion generator may include a driving mechanism for moving the stylus on a plane orthogonal with an axis of the stylus in X-axis and Y-axis direction orthogonal with each other, and a rotation controller for giving a control signal of X=R cos &thgr; and Y=R sin &thgr; relative to a locus of the rotary motion having a radius R and a rotary a
Hidaka Kazuhiko
Matsuki Kaoru
Okamoto Kiyokazu
Fulton Christopher W.
Mitutoyo Corporation
Webb Ziesenheim & Logsdon Orkin & Hanson, P.C.
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