Geometrical instruments – Gauge – With support for gauged article
Reexamination Certificate
2001-04-27
2003-04-08
Gutierrez, Diego (Department: 2859)
Geometrical instruments
Gauge
With support for gauged article
C033S503000, C033SDIG001
Reexamination Certificate
active
06543150
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a form measuring sensor and a form measuring instrument. More specifically, it relates to a form measuring sensor and a form measuring instrument for measuring a form of a workpiece by touching a stylus on a surface of a thread.
2. Description of Related Art
There are various shapes of workpiece to be measured. Among the workpiece, a thread of a threaded workpiece (threaded hole=internal thread, threaded shaft=external thread) has parameters (characteristic value) for defining characteristic thereof. Such parameters include thread pitch a, effective thread portion length b, incomplete thread portion c, threaded hole depth d etc. as shown in threaded hole
100
of
FIG. 7. A
coordinates measuring machine is used for measuring respective parameters a to d of the threaded hole
100
.
In order to measure the thread by the coordinates measuring machine, a touch signal probe or a scanning probe can be used.
When a touch signal probe is used, the contact portion of the touch signal probe is brought into contact with the surface of the thread and the coordinates value at the time is read. The thread form is measured by obtaining coordinates value at a desired plurality of points by repeating the above operation.
On the other hand, when the scanning probe is used, the scanning probe and the thread are relatively moved while a contact portion of the scanning probe keeps in contact with the thread surface with a constant measurement force. The thread form is measured by continuously collecting the coordinates value of the contact portion.
However, following disadvantages occur in measuring the thread form using the above-described coordinates measuring machine.
When the touch signal probe is used to measure the workpiece, the touch signal probe has to touch the thread surface at respective points. Accordingly, for measuring the respective parameters of, for instance, the threaded hole
100
, the data have to be continuously collected by multi-point measurement, so that considerable time is required for measurement.
On the other hand, when the scanning probe is used to measure the workpiece, since contact and separation are not required between the probe and the thread surface for respective points unlike the measurement using the touch signal probe, the data can be continuously collected within a short period of time. However, the scanning probe having a mechanism for continuously detecting the coordinates value of the contact portion while keeping the contact portion in contact with the thread surface is expensive in itself.
An object of the present invention is to provide a form measuring sensor and a form measuring instrument capable of continuously collecting workpiece surface form data within a short time and capable of being inexpensively constructed.
SUMMARY OF THE INVENTION
A form measuring sensor according to an aspect of the present invention includes: a stylus having a contact portion to be in contact with a workpiece surface at a first end; and a body for holding the stylus through an adaptor, the adaptor including a stylus attachment for a second end of the stylus to be attached, a body attachment to be attached to the body and an elastically deformable connector for connecting the stylus attachment and the body attachment, where the connector elastically deforms to allow a displacement of the stylus and the stylus attachment relative to the body attachment in accordance with a configuration of the surface of the workpiece, and where a deformation sensor for detecting the elastic deformation of the connector is provided.
In the present invention, the form measuring sensor is relatively moved in surface direction of the workpiece while the contact portion of the stylus keeps in contact with the surface of the workpiece. Then, the contact portion of the stylus scans the inner circumference of the workpiece and displaces in a direction approximately orthogonal with the relative movement, so that the stylus attachment of the adaptor attached with the stylus displaces in the same direction. On the other hand, since the body attachment of the adaptor is attached to the body relatively moving in the surface direction of the workpiece, the displacement direction becomes solely the relative movement direction. In other words, since the stylus attachment of the adaptor displaces approximately orthogonal with the relative movement direction and the body attachment does not displace relative to the body, the connector connecting the stylus attachment and the body attachment elastically deforms. Accordingly, the displacement of the stylus attachment, i.e. the displacement of the contact portion of the stylus can be represented by the elastic deformation of the connector. Continuous inner circumference form data of the workpiece can be collected within a short time by continuously detecting the elastic deformation of the connector with the deformation sensor.
The surface form of the workpiece is measured by detecting the elastic deformation of the connector which allows the displacement of the stylus by elastic deformation thereof, i.e. brings the stylus into contact with the workpiece with a constant measuring force. In other words, since the contact portion is brought into contact with the workpiece surface with a constant force and the displacement of the contact portion is continuously detected by the connector, the mechanism can be arranged simpler and more inexpensive than a scanning probe.
In the above arrangement, the stylus may preferably be formed in approximate L-shape and include a first arm extending along the surface of the workpiece with an end attached to the stylus attachment, and a second arm extending substantially orthogonal with the other end of the first arm and having the contact portion at an end thereof.
According to the above arrangement, since the stylus includes the first arm attached to the stylus attachment and extending along the surface of the workpiece, and the second arm extending approximately orthogonal with the first arm and having the contact portion, the stylus can be easily inserted into the threaded hole, and the contact portion can be securely brought into contact with the thread bottom of the threaded hole.
In the form measuring sensor according to the above arrangement of the present invention, the body may preferably be relatively moved along the surface of the workpiece while the contact portion of the stylus keeps in contact with the surface of the workpiece, and the contact portion of the stylus may preferably be disposed on a center line of the connector approximately parallel to the relative movement direction.
When the contact portion of the stylus scans the surface of the workpiece, some friction force is ordinarily generated between the contact portion and the workpiece surface. The friction force fluctuates according to measurement force applied to the contact portion and surface roughness of the workpiece etc. Specifically, when FIG.
6
(A) is taken as an example, the stylus
110
is moved in a direction indicated by outlined arrow in the figure while an end of an approximately L-shaped stylus
110
, i.e. a contact portion
111
keeps in contact with the surface of a workpiece W. At this time, measurement force Fv and friction force Ff are applied on the contact portion
111
. When the length of the first arm
112
is L1 and the length of the second arm
113
is L2, a moment M1 applied to the other end
114
of the stylus
110
can be represented as follows:
M
1=
Fv*L
1+
Ff*L
2
When the connector of the adaptor is located on the other end
114
of the stylus
110
, the moment M1 is applied on the connector to cause elastic deformation of the connector. The elastic deformation of the connector varies in accordance with surface form of the workpiece W. Accordingly, the surface configuration of the workpiece W can be detected by detecting and continuously recording the variation of the elastic deformation. In other words, t
Matsumiya Sadayuki
Yoshioka Susumu
Guadalupe Yaritza
Gutierrez Diego
Mitutoyo Corporation
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