Geometrical instruments – Gauge – Movable contact probe – per se
Reexamination Certificate
1999-08-04
2001-12-11
Gutierrez, Diego (Department: 2859)
Geometrical instruments
Gauge
Movable contact probe, per se
C033S559000, C033S558000
Reexamination Certificate
active
06327789
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a touch signal probe for measuring a configuration of a workpiece by a coordinate measuring machine and the like.
2. Description of Related Art
One-dimensional measuring machine, a height gauge for instance, a coordinate measuring machine and a profile measuring machine for measuring configuration of solid body are known as a measuring machine for measuring a configuration and a dimension of a workpiece. Various probes are attached to the measuring machine to detect relative position of a measuring machine body and the workpiece.
The probes are classified into non-contact type probes and contact-type probes, or into continuously measuring probe and touch trigger probe etc.
An ultrasonic touch signal probe disclosed in Japanese Patent Publication Laid-open No. Hei 6-221806 is known as an example of the above-mentioned contact type touch trigger probe for the coordinate measuring machine.
As shown in
FIG. 11
, a touch signal probe
100
includes a stylus holder
101
, a vibrator
102
and piezoelectric element
103
etc. The stylus holder
101
is attached to a movable shaft of a coordinate measuring machine etc (not shown). A contact to the workpiece is detected while the movable axis is moved and the coordinate when the probe touches the workpiece is read, thereby measuring the configuration etc. of the workpiece.
The stylus holder
101
is configured in a hollow cylindrical shape and has the vibrator
102
at a lower inner end (a direction in the figure, equally applied hereinafter) thereof supported by a pair of engage pin
104
disposed on a support point arranged at a substantially central portion in the axial direction of the vibrator
102
. A contact ball
102
A to be abutted to the workpiece during measurement is mounted on a lower end of the vibrator
102
and a counter balance
102
B having the same weight as the contact ball
102
A is attached on an upper end of the vibrator
102
, so that the support point to the stylus holder
101
is consistent with a centroid of the vibrator
102
.
A pair of groove portion
105
formed by cut-out is provided at an outer circumference of the vibrator
102
and the piezoelectric elements
103
are attached spanning over the respective groove portions
105
. The pair of groove portion
105
and the pair of the piezoelectric element
103
respectively have the same configuration. Both ends of the respective piezoelectric elements
103
are fixed at two points of the outer circumference of the vibrator
102
across the groove portion
105
by an adhesive etc.
The piezoelectric elements
103
are disposed substantially symmetrically at a center of the support point of the vibrator
102
along the axial direction of the vibrator
102
and are divided into a vibrating means
103
A for vibrating the vibrator
102
resonantly and a detecting means
103
B for detecting a change in the vibration of the vibrator
102
.
In the touch signal probe
100
, a node of vibration of the vibrator
102
coincide with the support point when the vibrator
102
is vibrated along the axial direction thereof by the vibrating means
103
A.
According to the touch signal probe
100
, since the centroid of the vibrator
102
is supported by the stylus holder
101
at a portion of the node of vibration, stability against disturbance vibration is improved to enhance measurement accuracy of the touch signal probe.
However, following problems occur in reducing an entire size of the probe in thus-structured conventional touch signal probe
100
.
When the size of the entire touch signal probe
100
is reduced, the size of the support point of the vibrator
102
is reduced in proportion to the entire dimension. In other words, in order to prevent the support point continuous with a non-vibrated stationary portion from restraining the vibration of the vibrator
102
, the support point is required to be positioned within a predetermined area adjacent to the node of vibration of the vibrator
102
and the size of the area is lessened when the size of the touch signal probe
100
is reduced, which result in difficulty in supporting the vibrator
102
on account of minute arrangement thereof.
Further, since the vibrating means
103
A and the detecting means
103
B mounted with the node of vibration therebetween are difficult to be disposed, highly accurate processing and assembly of the components with high accuracy can be difficult.
On the other hand, a vibrator shown in U.S. Pat. No. 5,524,354 is known as a vibrator for a touch trigger probe aiming at reduction in size.
As shown in
FIG. 12
, a vibrator
202
has a tuning-folk shaped vibrating portion
203
, a stick stylus
204
disposed at a pointed end of the tuning-folk shaped vibrating portion
203
, and a tip ball
205
disposed at a pointed end of the stylus
204
. The respective styluses
204
are arranged to cause flexural vibration in a direction orthogonal with an axial direction thereof in synchronization with the vibration of the tuning-folk shaped vibrating portion
203
. Base portion of the tuning-folk shaped vibrating portion
203
does not vibrate and support thereof is easy even when the size of the vibrator
202
is small, and a vibration property at a distal end can be enhanced to enable high sensitivity. Accordingly, the reduction of the size of the touch trigger probe can be easily attained while maintaining high sensitivity thereof.
In the touch trigger probe utilizing the vibrator
202
, however, since the stylus
204
causes flexural vibration in synchronization with the vibration of the tuning-folk shaped vibrating portion
203
, the sensitivity can be widely varied according to which part of the tip ball
205
contacts the workpiece (having direction dependence). Further, since the vibration range of the distal portion of the stylus
204
is generally set large, the accuracy cannot be obtained as compared to ordinary touch trigger probe.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a touch signal probe of which size can be easily reduced while maintaining high accuracy.
The present invention is a touch signal probe having a stylus holder, a vibrator supported by the stylus holder and having a contact portion to contact to a workpiece at a distal end thereof, a vibrating means for vibrating the vibrator in resonant condition in an axial direction of the vibrator, and a detecting means for detecting a contact of the vibrator with the workpiece by a change in the vibration of the vibrator caused when the vibrator contacts the workpiece, which is characterized in that the vibrator is supported by the stylus holder at two support points opposing with a node of vibration therebetween.
According to the present invention, since the vibrator is supported by the stylus holder at the two support points opposing with the node of vibration therebetween, the node of vibration can be formed at a portion between the two support points of the stylus by disposing the vibrating means and the detecting means spanning over the two support points. Therefore, since the support points are not limited to a small area, thereby simplifying a support structure and facilitating to attach the vibrating means and the detecting means, so that the size of the touch signal probe can be easily materialized.
Further, since the vibrator is supported at two points, the horizontal vibration in a direction orthogonal with the axial direction of the vibrator can be minimized to a negligible degree, thereby improving the detecting accuracy of the touch signal probe.
In the present invention, the node of vibration of the vibrator is preferably positioned at a center of the two support points and is preferably consistent with a centroid of the vibrator.
More specifically, as shown in schematic view of
FIG. 1
, the stick-shaped vibrator
12
is preferably supported by the two support points A and B and a point C of the node of vibration in an axial direction of the vibrator
12
is preferably the center of the two support p
Hidaka Kazuhiko
Nishimura Kunitoshi
Nishioki Nobuhisa
Gutierrez Diego
Lowe Hauptman & Gilman & Berner LLP
Mitutoyo Corp.
Smith R. Alexander
LandOfFree
Touch signal probe does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Touch signal probe, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Touch signal probe will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2574535