Geometrical instruments – Gauge – Circular size
Reexamination Certificate
2000-04-04
2001-09-11
Gibson, Randy W. (Department: 2859)
Geometrical instruments
Gauge
Circular size
C033S555300
Reexamination Certificate
active
06286223
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an apparatus for measuring the outer diameter of a worked portion at the end of a pipe end, and a method thereof. The pipe, for example, is an oil well pipe. A thread for coupling is formed at an end portion of the oil well pipe. The apparatus and the method of the present invention are suitable for measuring the outer diameter dimension after a thread working is applied.
BACKGROUND ART
FIG. 5
is a sectional view showing a typical example of a method for joining oil well pipes. FIG.
5
(
a
) shows one type in which two pipes P
1
and P
2
are jointed to each other by use of a coupler C. In this type, a thread portion S, having a mail thread, is provided around each outer peripheral surface of the ends of the two pipes P
1
and P
2
. The two pipes are joined together by screwing the male thread into the mating female thread provided around an inner peripheral surface of the coupler C. In the type shown in
FIG.5
(
b
), a female thread is provided around an inner peripheral surface of one pipe P
2
, which is joined to another pipe P
1
by screwing the female thread into the mating male thread provided around an outer peripheral surface of the another pipe P
1
.
In the types shown in
FIG. 5
, some pipes have a portion M (referred as a metal seal portion) corresponding to an end portion of the pipe to which no thread working is applied. There also exists a type, which has no such metal seal portion, but it is not shown in the drawing.
As described above, a thread working is applied to at least one of the outer peripheral surface of the end portions of the oil well pipes. Such a thread requires durability against repeated use, and a portion which is joined by the thread, also requires high air tightness. Thus, in an oil well pipe which has the thread worked portion with or without the metal seal portion, it is highly important to verify whether the worked portion of a pipe edge, including these portions, is ranged within a particular standardized dimension.
To cite an example for verification of the oil well pipe edge portion worked as shown in
FIG. 5
, there is one measurement method, in which the outer diameter, at a position of 2 mm from the pipe edge (the metal seal portion), is measured and the outer diameter, at one particular portion in the range of from 30 to 80 mm from the same pipe edge (the thread portion), is measured. The position in the latter measurement is varied according to a size of an oil well pipe. In the conventional method, when the outer diameter is measured at such plural designated positions, stand off ring gauges, which have respectively different diameters corresponding to each prescribed outer diameter at the plural designated positions, have been prepared for each the pipe size. However, this conventional method has the following enumerated drawbacks.
(1) A number of gauges need to be prepared for each pipe size and also for each measuring position. Therefore, the expenditure for their fabrication would run up and this also takes a lot of trouble due to the checking operation for quality control of the gauges.
(2) Since it needs to perform the measurement with fitting the gauge onto the measuring position from the outside, this occasionally causes to make some defects on the peripheral of the pipe.
(3) In a case that the thread worked portion is out of the complete round, the measurement error would be increased.
There also exists a method for directly measuring the outer diameter dimension of the designated portion besides the aforementioned method. However, such a method has the following drawbacks.
(4) Since the maximum size of the outer diameter is measured by making a reference portion of the gauge contact at the pipe end, it needs to turn the gauge around with making the reference portion serve as a fulcrum. Accordingly, the measurement attitude could become unstable, and this tends to cause measurement error.
(5) Since the outer diameter of the designated portion is measured at several points and these sizes are visually read, a continuous and rapid measurement cannot be carried out.
(6) Since plural designated portions need to be measured with respective particular gauges, the designated portions cannot simultaneously be measured.
As described above, any conventional measuring methods are inefficiently performed by manual procedures, and it is also difficult to measure with high accuracy.
DISCLOSURE OF INVENTION
One object of the present invention is to provide an apparatus for measuring an outer diameter of the worked portion at the end of a pipe, which has all of the following functions:
(a) Enabling to measure an outer diameter of various pipes having different sizes.
(b) Enabling to simultaneously measure both of the outer diameters of two circumferential portions of the end portion of the pipe.
(c) Enabling to pick up the measurement result in the form of an electric signal and process the signal by an arithmetic unit to automatically calculate the outer diameters.
(d) Enabling to continuously measure with high accuracy at plural circumferential positions of the pipe.
A second object of the present invention is to provide a method for rapidly and accurately measuring an outer diameter of the worked portion at the end of a pipe by use of the aforementioned apparatus.
The apparatus of the present invention is an apparatus for measuring an outer diameter of a worked portion at the end of a pipe, as illustratively showed in
FIG. 1
to FIG.
4
. Major members of this apparatus are a main arm
1
, a lower gauge head support arm
2
, a bearing roller arm
3
, an upper gauge head support arm
4
, a presser roller arm
5
, a position-fixing bracket
6
, lower gauge heads
14
a
and
14
b
, and upper gauge heads
15
a
and
15
b.
The lower gauge head support arm
2
and the bearing roller arm
3
are locked to the lower end of the main arm
1
while projecting at a right angle, i.e. toward a horizontal direction, with respect to the main arm
1
. In the same way, the upper gauge head support arm
4
and the presser roller arm
5
are disposed to project at a right angle with respect to the main arm
1
. Hereat, the arm
4
and
5
can vertically slide along the main arm
1
.
The upper gauge head support arm
4
is locked in a predetermined position (predetermined height) of the main arm
1
through clamping down with screws
16
a
and
16
b
. In the same way, the position-fixing bracket
6
is locked in a predetermined position or predetermined height of the main arm
1
through clamping down with screws
17
a
and
17
b
.This position-fixing bracket
6
makes a junction with the presser roller arm
5
through pins
18
a
and
18
b
and coil springs
19
a
and
19
b.
The lower gauge head
14
b
and the upper gauge head
15
b
are inserted respectively into the groove
2
b
of the arm
2
and the groove
4
b
of the arm
4
, and each gauge head is movable toward the main arm
1
along the respective grooves. The gauge heads
14
a
and
15
a
may be secured at a predetermined position not able to move in a horizontal direction, and may otherwise be moveable toward the main arm
1
, along a groove
2
b
and a groove
4
b
respectively, as well as the gauge heads
14
b
and
15
b
. All of these gauge heads can be vertically moved, i.e., can be moved toward a peripheral surface of a measured object, and it is adapted so that such movement distance can be detected in the form of an electric signal.
The bearing roller arm
3
is formed in a U-shape as shown in figures, and rollers
10
a
and
10
b
are rotatably attached to both sides
3
b
of the bearing roller arm. The presser roller arm
5
has a similar structure in which rollers
11
a
and
11
b
are provided. A pipe, as the measured object, is supported with being clipped between these rollers. Thus the outer diameter can be measured at two portions of the pipe in its axial direction (longitudinal direction), by the aforementioned gauge heads.
Further details about the apparatus and the measuring method will be described hereinafter.
BRIEF DESCR
Burns Doane , Swecker, Mathis LLP
Gibson Randy W.
Sumitomo Metal Industries Ltd.
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