A kind of determination method of petroleum casing pipe round thread tooth form angle
Technical field
The invention belongs to oil and gas industry petroleum casing screw parameter detecting fields, and in particular to a kind of petroleum casing pipe
The determination method of round thread tooth form angle.
Background technique
Petroleum casing pipe is important equipment used in exploitation of oil-gas field, and the quality of quality directly affects oil gas field production safety
And production efficiency.Currently, the tubing and casing majority that each elephant uses executes API relevant criterion, such as API SPEC 5CT and API
SPEC 5B etc., wherein API Round threaded casing has been made due to its high in machining efficiency, function admirable in each elephant extensively
With.In relevant criterion the thread parameter etc. of CASING CONNECTION WITH ROUND PROFILE THREAD clearly requires, the concrete regulation mesh of performance parameter
Scale value and the margin of tolerance.Manufactory requires processing tubing and casing according to product standard, and parameters meet the requirements of the standard, are determined as
Qualified products are delivered for use.
It is found in manufactory's production testing and oil field practical application, some thread parameters of petroleum sleeve joint are difficult to standard
Really measurement and judgement.For example, requiring casing round thread in API SPEC 5B standard for the tooth form angular dimensions of Round threaded casing
Tooth form angle is 60 °, and tooth form angle tolerance is ± 1.5 °, although API SPEC 5B standard is clear to tooth form angle tolerance,
But not clear how to measure.Due to unpractical measuring tool, current most of factories are not using tooth form angle as life
The normal inspection project examined is produced, only just uses laboratory method when there are larger quality problems at product approval initial stage or product
A small amount of measurement is carried out, detection efficiency is low, and testing cost is high.Not detecting tooth form angle has quality for petroleum sleeve joint screw thread
Hidden danger, it is therefore desirable to a kind of method for proposing detection petroleum casing pipe tooth form angle that can be effectively practical, to determine the petroleum of production
Whether casing joint form of thread angle parameter meets the requirements of the standard.
Summary of the invention
Present invention aim to address existing petroleum casing screw tooth form angles to be difficult to the problem of accurately determining, proposes one kind
Convenient for measuring, reflecting accurate and energy practical application petroleum casing screw tooth form angle determination method, the method is by producing
Measurement of the manufacture scene to petroleum casing screw thread height, to determine whether the petroleum casing screw tooth form angular values accord with
It closes and requires.
Technical proposal that the invention solves the above-mentioned problems is:
A kind of determination method of petroleum casing pipe round thread tooth form angle, comprising the following steps:
1) casing threads after processing is completed, measures the thread height deviation h of screw thread;
2) decision condition:
Wherein, H is round thread theory thread depth, SsFor screw thread abatement value as defined in standard, p is thread pitch, and A is mark
Form of thread angle upper limit value as defined in standard, K are processing correction factor;
3) when the form of thread height tolerance h of measurement meets decision condition, determine that form of thread angle is qualified, otherwise for
It is unqualified.
Further, thread height rule measurement thread height deviation h is used in step 1).
Further, processing adjusted coefficient K determines in the following manner, using the casing processed under same process conditions, often
It is spaced 10 and takes out 1, take out 3 branch casings altogether, the thread height deviation h of screw thread is detected using thread height rule1、h2、h3, and
3 branch casing form of thread angle As are detected using laboratory method1、A2、A3, bring formula into
Calculate adjusted coefficient K1、K2、K3, it is averaged i.e. as processing adjusted coefficient K=avg (K under the processing conditions1,K2,
K3)。
Further, same process conditions are identical casing grade, identical process tool and processing method.
Further, laboratory method is optical contrast microscope, profile measurer or injection molding.
The invention has the benefit that
1. judgement range is calculated by mathematical model in determination method proposed by the present invention, by measured value and model is determined
It encloses comparison to be determined, visual result is clear, and detection efficiency is high.
2. method proposed by the present invention utilizes existing thread parameter detection instrument, easy to operate, quasi- convenient for measurement, reflection
Really, and energy practical application is in casing manufactory and Oil Field.
3. manufacturing reality to the determining fitting for processing coefficient in mathematical model in the present invention, the processing conditions is enhanced
The lower validity for determining range.
Detailed description of the invention
Fig. 1 is petroleum casing pipe round thread tooth form schematic diagram.
Appended drawing reference: the normal tooth form profile of 1-, 2- thread form angle become larger form of thread profile.
Specific embodiment
The contents of the present invention are described in further detail below in conjunction with specific embodiment:
A kind of determination method of petroleum casing pipe round thread tooth form angle, comprising the following steps:
1) casing threads after processing is completed, the thread height deviation h of measurement screw thread is advised using thread height;
2) decision condition:
Wherein, H is round thread theory thread depth;
SsFor screw thread abatement value as defined in standard;
P is thread pitch;
A is form of thread angle upper limit value as defined in standard, and K is processing correction factor;
3) when the form of thread height tolerance h of measurement meets decision condition, determine that form of thread angle is qualified, otherwise for
It is unqualified.
Above-mentioned processing adjusted coefficient K determines in the following manner: using the casing processed under same process conditions, at interval of
10 are taken out 1, take out 3 branch casings altogether, and the thread height deviation h of screw thread is detected using thread height rule1、h2、h3, and use
Laboratory method detects the 3 branch casing form of thread angle A1、A2、A3, bring formula into
Calculate adjusted coefficient K1、K2、K3, it is averaged i.e. as processing adjusted coefficient K=avg (K under the processing conditions1,K2,
K3)。
Above-mentioned same process conditions are identical casing grade, identical process tool and processing method.
Above-mentioned laboratory method is optical contrast microscope, profile measurer or injection molding.
Because tooth form angle and thread height deviation h have the geometrical relationship of above-mentioned formula, decision condition is released, is passed through
To the judgement of h can indirect judgement tooth form angle it is whether qualified.
Tooth form for certain machine tooling is the survey of progress form of thread angle for the casing of 8 tooth round thread of API standard
Amount and judgement.
1) according to API SPEC 5B standard queries it is found that 8 tooth round thread theory thread depth H=2.749mm, screw thread spiral shell
Away from p=3.175mm, screw thread abatement value Ss=0.508mm, A=61.5 ° of upper limit value of form of thread angle;
2) processing adjusted coefficient K is determined;
30 branch casings are processed under the same processing conditions, are taken out 1 at interval of 10, are taken out 3 branch casings altogether, use tooth form height
Metric detects the thread height deviation h of screw thread1、h2、h3, and the 3 branch casing form of thread is detected using laboratory method
Angle A1、A2、A3, bring formula intoExtrapolation goes out adjusted coefficient K1、K2、K3, it is averaged
Number is as processing adjusted coefficient K=avg (K under the processing conditions1,K2,K3);
3) parameter for obtaining step 1) and step 2) brings tooth form angle into and determines formula
Show that tooth form angle determines range;
4) it is done using the judgement range that the thread height deviation h that thread height rule detect screw thread to be detected is obtained with step 3)
Compare, that is, can determine that whether the form of thread angle meets the requirements of the standard.
The drill rod boring tool form of thread angle that method of the invention can also be used for similar structures determines.