Geometrical instruments – Gauge – With support for gauged article
Reexamination Certificate
2000-12-21
2002-07-23
Gutierrez, Diego (Department: 2859)
Geometrical instruments
Gauge
With support for gauged article
C033S551000
Reexamination Certificate
active
06421929
ABSTRACT:
FIELD OF THE INVENTION
This invention is an improvement in measuring male and female tapered or conical parts. More particularly, this invention is an apparatus and method for measuring such parts that use non-contact linear measurement technology and that can accurately and repeatably measure tapered or conical parts. The inventive apparatus and method are particularly suited to measuring tapered parts that exhibit large deviations from their desired measurements.
BACKGROUND OF THE INVENTION
The 25th Edition of Machinery's Handbook, Industrial Press Inc., New York, 1996, at pp. 689-693, describes measurement of a tapered or conical part. This handbook describes suitable methods for determining measurements of an exteriorly tapered or conical (male) part and for determining measurements of an interiorly tapered or conical (female) part.
A method for determining the measurement of an exteriorly tapered or conical (male) part is as follows. The axis of a vee-block aligns with the sides of a sine-bar, as in
FIGS. 1A-C
. The male tapered part
10
to be measured positions in the vee-block
12
. The male tapered part
10
aligns perpendicularly to the transverse axis of the sine-bar
14
. The sine-bar
14
offsets to the proper height to define a flat plane for the top surface
16
of the male tapered part
10
, as shown in FIG.
1
C. The sine-bar
14
is set to the angle B=(C+A/2), where A/2 is one-half the included exterior angle of the male tapered part
10
, as shown in FIG.
1
C. Where D is the included angle of the precision vee-block
12
, as shown in
FIG. 1B
, the angle C, shown in
FIG. 1C
, is calculated from the formula:
Sin
C
=
Sin
A
/
2
Sin
D
/
2
This determines the total included angle of the male tapered part
10
. If all points along the top surface
16
of the tapered part
10
are co-linear and co-planar, as in
FIG. 1C
, this confirms the planarity (absence of concavity/convexity) of the exterior surface of the male tapered part
10
along that line. By continuing such replicate measurements along the surface of the male tapered part
10
, the concavity/convexity for the entire part
10
is determined.
Machinery's Handbook also describes measurement of an interiorly tapered or conical (female) part
18
, with reference to FIG.
2
. The method uses individual balls B, B
1
of two or more different sizes that each has a given fit diameter within the interior of the female tapered part
18
. The principle of the ball method of taper measurement is described with reference to the gauge
20
in FIG.
2
. When two balls B, B
1
of unequal diameters are either in contact or a known distance apart, lines tangent to both their circumferences will represent an angle or taper. The degree of the angle or taper depends upon the diameters of the two balls B, B
1
and the distance C between their centers. The gauge
24
in
FIG. 2
consists of two adjustable straight edges A, A
1
, in contact with balls B, B
1
. The angle &agr;, or the taper between the straight edges A, A
1
, depends upon the diameters of the balls B, B
1
and the center distance C between the balls. By measuring these three dimensions accurately, the gauge
20
can be set to a given angle.
The first ball B inserts into the taper defined between A and A
1
and the height of B from the base of the taper is measured. Then a second, larger ball B
1
inserts into the taper and the difference in heights between B and B
1
from the base of the taper is measured. The difference between the larger and smaller diameters of the female tapered part
18
(i. e., diameters of the balls B and B
1
) and the length of the longitudinal axis of the female tapered part
18
(i. e., center distance C) define the planarity (absence of concavity/convexity) of the interior surface of the female tapered part
18
.
All state-of-the-art-measuring devices utilize some variation on the principles of measurement of the interior (female) or exterior (male) conical or tapered part as described above. For example, current commercially available gauges using air jet nozzles employ the following method for measuring exterior (male) tapers.
A typical conventional gauge uses a funnel-shaped receptacle, known as a “pot.” The interior pot surface has orifices for small air jet nozzles that direct airflow at the interior of the pot and at an exteriorly tapered part supported within the pot. The air jet nozzles arrange in horizontally aligned pairs, and the nozzles of each pair position 180° apart from each other. The gauge generally has three pairs of air jet nozzles arranged at three different horizontal levels, respectively, within the pot. A first set of nozzles positions to measure a larger diameter of the taper. A second set of nozzles positions at about the middle of the taper height to measure an intermediate diameter of the taper. A third set of nozzles positions to measure a smaller diameter of the taper.
The interior taper of the pot provides contact support for the male tapered part to be measured. The air pressure exerted by each aligned pair of air jet nozzles within the pot is measured with the exteriorly tapered part in place and with an exteriorly tapered mastering part in place. When the mastering part is in place, a minimal air gap exists between the mastering part and the pot. With the mastering part in place, an initial pressure is measured to calibrate the gauge. The air gap between the mastering part and the pot is determined at each set of air jet nozzles. Then, the mastering part is removed and replaced with a male tapered part to be measured.
There is a difference between the pressure measurement with the male tapered part to be measured in the pot and the pressure measurement with the male tapered mastering part in place. The difference in air pressures determined by each pair of air jet nozzles is used to calculate the difference between the diameter of the mastering part and the diameter of the tapered part horizontal to that pair of air jet nozzles. The air gap between the male tapered part being measured and the pot is determined and compared to the air gap determined between the mastering part and the pot at each set of air jet nozzles. Diameters are thus measured at three different locations along the height of the tapered part. The distance between any two diameters along a vertical axis of the tapered part is known. Lines tangent to the circumferences of both of the circles defined by these diameters will form the angle of the tapered part. This calculation may be made by hand or by the computer measuring the pressure differences.
The top and bottom diameters, measured by the top and bottom air jet nozzles, establish a diameter difference (similar to that determined by the “ball drop” described in Machinery's Handbook). The third diameter, measured by the third set of air jet nozzles, determines the straightness of the taper (its concavity/convexity), by indicating whether the three points are co-linear. Points are co-planar by the construction of the pot.
The diameters are measured with the tapered part resting in contact with the pot in a “gravity seat;” that is, the part rests there under its own weight. The tapered part positions in the pot relative to the air jet nozzles. If the tapered part should fit off-center and over on one side of the pot, one of the air jet nozzles will be plugged and restricted. The restricted air jet nozzle will register an incorrect higher-than-average pressure, while the corresponding horizontally opposite air jet nozzle will register an incorrect lower-than-average pressure. The pair of air jet nozzles operatively connects, so that the corresponding gaps between the tapered part and each air jet nozzle are averaged and the diameter of the tapered part at that point can be measured.
The currently available system of measuring tapered parts is limited, because the air jet nozzles must position close to the surface of the tapered part (i.e., with only a small gap between the tapered part to be measured a
Command Tooling Systems
Gutenkauf Robert W.
Jaisle Cecilia M.
Linn, Jr. Eric H
Reid Malcolm D.
LandOfFree
Apparatus and method to measure tapered or conical parts does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Apparatus and method to measure tapered or conical parts, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Apparatus and method to measure tapered or conical parts will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2861209