CN219607897U - Screw tail measuring gauge capable of positioning - Google Patents

Abstract

The utility model discloses a positionable spiral tail measuring gauge, which comprises a measuring main body and a positioning structure; the measuring main body comprises a meter head and a meter frame, the meter head is arranged on the meter frame, a movable contact of the meter head penetrates through the meter frame, and a first fixed contact and a second fixed contact are also arranged on the meter frame on the side where the movable contact is positioned; the positioning structure comprises a ruler body and a positioning ruler, the meter frame is connected with the ruler body through a groove slideway, so that the ruler body can move back and forth for a certain distance compared with the meter frame, and the positioning ruler is arranged on the ruler body; the top ends of the movable contact, the first fixed contact and the second fixed contact are spherical structures, and the space between the first fixed contact and the second fixed contact isSpacing between the movable contact and the first fixed contactThe diameter of the movable contact is smaller than that of the fixed contact; the utility model avoids the defect of non-visual and inaccurate measuring position in the traditional mode.

Description

Screw tail measuring gauge capable of positioning

Technical Field

The utility model belongs to a measuring device for petroleum casing threads, and particularly relates to a screw tail measuring gauge for petroleum casing.

Background

The petroleum casing pipe is connected in the form of male and female threads, and when the threads are designed, the tool withdrawal position of the threads is determined through calculation, so that the threads are ensured to have enough connection strength, interference during screwing can be prevented, and therefore, the screw tail at the tool withdrawal position of the threads is required to be checked to ensure that the screw tail has enough length and is real.

The tool for checking whether the screw thread machining has the advance tool withdrawal is a screw tail measuring gauge, and the working principle is based on the theory that a straight line is determined by two points, namely, whether a movable contact (regarded as a third point) of a dial indicator is on the straight line determined by two fixed contacts.

The using method of the screw tail measuring gauge comprises the following steps: the three contacts are arranged at the tooth bottom of the thread, in particular to the method that two fixed contacts are arranged in a normal thread, a small-amplitude swing screw tail measuring gauge is determined, the minimum value is found, the screw tail measuring gauge is integrally rotated along the tooth bottom towards the large-diameter direction of the thread, when a movable contact enters an inspection area, whether the screw thread processing has the condition of retracting in advance can be judged through the reading of the screw tail measuring gauge, and if the reading of an indicator is not more than +0.005in (+ 0.13 mm), the screw tail is regarded as qualified. According to the requirements of API 5B, the dial indicator is required to be set to be zero before the screw tail measuring gauge is used. For buttress threads, the specification is not more than 13.375in, the complete thread bottoms are on the same straight line, and a plane is used as a correction reference; for the specification of not less than 16in, the complete thread roots are not on the same straight line but are stepped, the complete thread roots are used as correction references (before a gauge is corrected, whether the taper of the complete thread roots is proper or not is checked); for round threads, the method of use is not limited by specifications.

The method for determining the measuring position of the screw tail comprises the following steps: according to the API 5B, the initial measurement position of the screw thread gauge is the thread tooth bottom 1/4 of the circle before the screw thread retreats or 1/4 of the circle before the vertex of the triangle. The plane at a specific distance from the pipe end is perpendicular to the axis of the thread, and when the screw tail measuring gauge rotates due to the fact that the thread has a helix angle, the trace line of the movable contact can only have an intersection point with the plane, and the intersection point is the initial position of measurement;

inquiring about related application files of the screw tail measuring gauge, and patent applications of ' a device for measuring the screw tail of a trapezoid screw thread with a special pitch outside a pipe (application number 201220255934.6) ' a screw tail measuring instrument applied to a special threaded joint (application number 2202120864442.6) '; the main content of the two application documents is to improve the shape of the contact so as to adapt to different thread forms; the common problems in both application documents are: the designed measuring device cannot accurately position the initial position of the screw tail measurement. The width of a tooth socket of a screw thread of the petroleum casing is generally 1.5-4.5 mm, when finding the initial position of screw tail measurement, an observer visually determines the middle position of the top end of a flat head depth gauge at the bottom of a certain screw thread, and the position and the intersection point position have visual judgment errors, so that the error reaches +/-0.5 mm; taking an API buttress thread with 5 teeth per inch as an example, on a pipe with 7.0in specification, the thread lead angle is about 0.5 degrees, and the radial circumference angle corresponding to the axial + -0.5 mm is about 70 degrees, so that the accurate judgment of the measurement starting position is greatly interfered; the screw tail measuring gauge disclosed in the two applications has the problem that the measuring position cannot be accurately positioned.

Disclosure of Invention

The utility model aims to overcome the defects of the prior art and provides a positionable screw tail measuring gauge, the screw tail measuring gauge is matched with ball-head contacts with various diameter specifications to adapt to various thread forms, the positioning ruler can set the initial position for measurement, and the measuring gauge body and the gauge stand are elastically connected, so that the measuring position of a movable contact and threads in the measuring process is always kept relatively consistent.

The utility model solves the technical problems by adopting the following technical scheme:

a positionable screw tail measuring gauge comprises a measuring main body and a positioning structure; the measuring main body comprises a gauge outfit and a gauge stand, the gauge outfit is arranged on the gauge stand, a movable contact of the gauge outfit penetrates through the gauge stand, and a first fixed contact and a second fixed contact are also arranged on the gauge stand on one side where the movable contact is arranged; the positioning structure comprises a ruler body and a positioning ruler, the meter frame is connected with the ruler body through a groove slideway, so that the ruler body can move back and forth for a certain distance compared with the meter frame, and the positioning ruler is arranged on the ruler body;

the top ends of the movable contact, the first fixed contact and the second fixed contact are of spherical structures, and the interval between the first fixed contact and the second fixed contact isThe distance between the movable contact and the first fixed contact is +.>The diameter of the movable contact is smaller than that of the fixed contact, and the difference is not smaller than 0.20mm.

The ruler also comprises a spring, wherein the spring is positioned in the groove on the ruler body and sleeved on the guide post in the groove, one end of the ruler body is also sleeved on the guide post, and the spring is compressed when the ruler body moves along the guide post.

When the screw tail measuring gauge is used for measuring, the contact pressure between the positioning ruler and the workpiece is not more than 2N.

The measurement accuracy of the positioning ruler is 0.1mm.

The petroleum casing pipe screw thread is a conical screw thread, the included angle between the screw thread conical screw thread and the axis is alpha, when L is the fixed contact spacing A of the screw tail measuring gauge, the distance L of a certain length L in the screw thread axial direction on the screw thread conical screw thread is Ls, L=ls is cosalpha, the spacing between the first fixed contact and the second fixed contact is A, and when A is more than Ls, the second fixed contact is completely contacted with the screw thread tooth bottom and the screw thread bearing side during measurement; when A < Ls, the first fixed contact is in full contact with the thread root and the thread carrying side.

The movable contact is arranged on the meter head, the fixed contact is arranged on the meter frame, and when the positioning rule is locked, the distance between the contact and the positioning rule is controlled by the spring within a certain range; on the other hand, the positionable screw tail measuring gauge has the advantages that the top end of the contact is provided with a plurality of diameter specifications of a ball head type, and the measuring gauge can adapt to measurement of a plurality of thread forms; under the tensioning action of the spring, the first fixed contact or the second fixed contact is contacted with the tooth bottom and the tooth side of the thread at the same time, and in the measuring process, the movable contact and the thread always keep a relatively consistent measuring position.

The utility model has the advantages and positive effects that:

compared with the prior art, the positionable spiral tail measuring gauge provided by the utility model has the advantages that the top end of the contact is of a ball head type structure, during measurement, the fixed contact is contacted with the tooth bottom and the tooth side in a tangential mode at the same time, meanwhile, the diameter of the movable contact is smaller than that of the fixed contact, and the movable contact is contacted with the tooth bottom of the thread only; during measurement, the positioning ruler can accurately determine the starting point of measurement, and the spring mechanism realizes the measurement position of the movable contact and the screw thread which are consistent relatively all the time in the measurement process, so that the measurement precision can be effectively ensured.

Drawings

The technical solution of the present utility model will be described in further detail below with reference to the accompanying drawings and examples, but it should be understood that these drawings are designed for the purpose of illustration only and thus are not limiting the scope of the present utility model. Moreover, unless specifically indicated otherwise, the drawings are intended to conceptually illustrate the structural configurations described herein and are not necessarily drawn to scale.

FIG. 1 is a schematic front view of a positionable spiral tail measuring gauge structure of the present utility model;

FIG. 2 is a schematic view of the back of a positionable spiral tail measuring gauge according to the present utility model;

FIG. 3 is a schematic view of the inside of a positionable tail gauge stand according to the present utility model;

FIG. 4 is a schematic diagram of a positionable spiral tail measuring gauge positioning rule according to the present utility model;

FIG. 5 is a schematic view of the measuring external threads of a positionable tail gauge according to the present utility model;

FIG. 6 is a schematic view of the measuring internal threads of a positionable tail gauge according to the present utility model;

in the figure:

1-gauge outfit, 2-gauge stand, 3-ruler body, 4-positioning ruler, 5-spring, 6-guide post,

7-male threads, 8-female threads, 101-a movable contact, 201-a first fixed contact,

202-second fixed contact, 22-locking screw, 23-back cover screw, 24-back cover,

Detailed Description

The use of a positionable spiral tail measuring gauge of the present utility model will be described with reference to the accompanying drawings and specific measurement examples.

Example 1

As shown in fig. 1 and 2, the screw tail measuring gauge comprises a measuring main body and a positioning structure, wherein the measuring main body comprises accessories such as a gauge head 1, a gauge stand 2 and the like, and the positioning structure comprises a spring 5, a guide post 6, a ruler body 3 and a positioning ruler 4; the gauge outfit is fixedly arranged on the gauge stand through a locking screw 22, a movable contact 11 of the gauge outfit penetrates through the gauge stand, and a first fixed contact and a second fixed contact are also arranged on the gauge stand on the side where the movable contact is arranged; the gauge outfit 1 and the gauge stand 2 are fixed by a locking screw, the first fixed contact 201 and the second fixed contact 202 are arranged on the gauge stand 2, the gauge stand 2 and the ruler body 3 are connected through a groove slideway, in particular, the spring is positioned in a groove on the ruler body and sleeved on a guide post in the groove, one end of the ruler body is sleeved on the guide post, and the spring is compressed when the ruler body moves along the guide post; the spring 5in a compressed state is embedded in the grooves of the ruler body and the watch frame, and when the positioning ruler 4 is locked, the distance between the contact and the positioning ruler is controlled by the spring within a certain range; in order to facilitate the processing and assembly, the rear cover 24 is mounted on the watch frame by the rear cover screw 23, so that the installation of the components such as the spring and the guide post is facilitated.

The top end of the contact head of the screw tail measuring gauge is designed into a ball head structure, and the diameter isAnd the internal standard can adapt to measurement of various thread forms. When the screw tail measuring gauge is used, the positioning ruler 4 is adjusted according to the required measuring length and locked and fixed, the contact is arranged at the bottom of the screw thread, the screw tail measuring gauge is rotated along the direction of the large diameter of the screw thread at the bottom of the screw thread, and when the positioning ruler 4 contacts the starting position of the screw thread, the screw tail measuring gauge starts to enter a measuring state. In the measuring process, the movable contact 11 and the screw thread always keep a relatively consistent measuring position, and the screw tail of the screw thread can be accurately measured.

The number of threads per inch (25.40 mm) is an integer, typically 3, 4, 5, 6, 8, etc. In order to specifically illustrate the design details of the tail gauge, taking the requirement of 13.375in and below buttress threads on pitch as an example, for threads of other specifications or forms, only the corresponding tolerances need to be adjusted as such. The spacing between two fixed contacts is designed asThe distance between the movable contact and the first fixed contact is designed to be +.>The tolerance of +0.05mm and +0.10mm is derived from the tolerance of the pitch in API 5B, and only the upper tolerance is adopted, the screw threadThree contacts of the tail measuring gauge can be simultaneously arranged in the thread tooth groove.

Thread taper is defined as the axial distance between identical locations on a continuous thread. The screw thread has the tapering, and the contained angle of screw thread taper line and axis is alpha, and when L is the fixed contact interval A of screw tail measuring gauge, the distance of certain length L on screw thread taper line in screw thread axial direction is Ls, exists L=ls and cos alpha, and when L was two fixed contact interval A of screw tail measuring gauge, the difference of A and Ls under the different tapering is shown in table 1:

TABLE 1

The screw tail measuring gauge is measured on a thread taper line, and strictly speaking, the fixed contact pitch A of the screw tail measuring gauge is designed according to the distance Ls on the thread taper line, but considering the universality of the screw tail measuring gauge, namely, the screw tail measuring gauge can adapt to the thread measurement with different taper degrees, the pitch tolerance of the fixed contact of the screw tail measuring gauge is controlled according to +0.10mm, and the difference value in the table 1 can be covered to the greatest extent.

Therefore, when the fixed contact enters the thread tooth slot, the actual situation may occur that only one fixed contact is in full contact with the thread tooth bottom and the tooth side, for example, the distance a=50.90 mm between the fixed contacts on the surface frame, the distance ls=50.83 mm between the corresponding threads on the taper line, a > Ls, and only the second fixed contact is in full contact with the thread tooth bottom and the tooth side when measured; further, when A < Ls, the first fixed contact is in full contact with the tooth bottom and the tooth side.

When measuring the screw tail, the movable contact is required to be fully contacted with the thread tooth bottom, so that the interference of the tooth side to the movable contact is reduced to the greatest extent, namely the tooth side is prevented from contacting the movable contact, and particularly the inverted improved buttress thread is provided. Within the tolerance range, the condition that the movable contact is closest to the tooth side is A < Ls, B=25.40 mm, the thread pitch is positive tolerance +0.05mm, and at the moment, if the diameters of the movable contact and the fixed contact are the same, the tooth side of the thread is in forced contact with the movable contact to influenceAnd the movable contact is free. The common thread has a corresponding tooth slot width of 1.5-4.5 mm, and the ball head at the top end of the contact has a diameter ofIn various specifications, e.g.)> The diameter is preferably greater than half the width of the tooth slot when in use. On the other hand, the diameter of the movable contact is smaller than that of the fixed contact, and the difference value is not smaller than 0.20mm, so that the movable contact can be ensured to be in contact with the thread tooth bottom only, and the interference of the thread tooth side to the movable contact can be effectively avoided.

In addition, be elastic connection between table frame and the blade, spring control blade slides in the slide along the guide post, and under the natural state, blade T type top and table frame laminating. The positioning ruler can slide on the ruler body, and according to the precision design principle of the vernier caliper, the measuring precision of 0.1mm can be obtained by aligning 19mm on the ruler body with 10 scales on the positioning ruler, as shown in fig. 4.

According to the principle that the measured contact force does not exceed 2N, the design elastic coefficient of the spring takes a value of 50N/m, the pretightening force of the spring assembly is 1N, and the maximum contact force of the positioning ruler during measurement is 2N; the internal schematic diagram of the screw tail measuring gauge frame is shown in fig. 3, the gauge frame is elastically connected with the ruler body, the ruler body is controlled by the spring to slide in the slideway along the guide post, and in a natural state, the T-shaped top end of the ruler body is attached to the gauge frame and the pressing force 1N is maintained.

It should be noted that, due to the taper of the thread, the length of the thread measured along the thread taper line is longer than the corresponding thread by a certain length in the axial direction, but even when the thread taper is 1:10, the deviation of the length is only 1.2 per mill, so that the value has enough precision when the axial length of the thread is measured on the thread taper line.

By way of example, the screw tail gauge provided in this embodiment is used to detect premature tool withdrawal during the processing of petroleum casing threads, and the method is as follows:

measuring and judging whether the thread tail of a 9.625in special button male thread 7 is retracted according to the specified requirement, wherein the thread is of an improved buttress structure, according to the acceptance standard, the thread is 4 teeth/inch, the taper is 1:12, the required distance between the retracted position and the pipe end is not less than 119.59mm, and judging whether the advanced tool retraction phenomenon exists by using the thread tail measuring gauge; the measurement start positions thereof are determined as follows:

pitch = 25.4/4 = 6.35mm;

1/4 circumferential thread axial length = 6.35/4 = 1.59mm; (to the nearest 0.01 mm)

Selectively fixed contactSelect the movable contact +.>

The start position of the screw tail measurement is away from the pipe end= 119.59-1.59=118.0 mm;

the three contacts of the screw tail measuring gauge are zeroed on the plane, the positioning rule of the screw tail measuring gauge is adjusted and locked at 118.0mm, the positioning rule does not contact the pipe end, the three contacts are placed at the bottom of a screw thread tooth at a proper position, the screw tail measuring gauge is swung in a small amplitude, the minimum value (basically zero) is found, the screw tail measuring gauge is integrally rotated along the screw thread in the large diameter direction of the screw thread, when the positioning rule contacts the pipe end, the rule body gradually extends out, the movable contact enters the checking area, the screw tail is continuously rotated for 1/4 weeks, and if the reading of the indicating gauge is not more than +0.005in (+ 0.13 mm), the screw tail is qualified as shown in the figure 5.

Example 2

The method for checking tool withdrawal in the processing of the screw thread of the petroleum casing by using the screw tail measuring gauge provided in the embodiment 1 is as follows:

and (3) measuring and judging whether the thread tail of a 7.625in special female thread 8 is retracted according to the specified requirement, wherein the thread is a buttress thread, the thread is 5 threads/inch according to the acceptance standard, the taper is 1:16, the retraction position is required to be not less than 98.57mm away from the outer end of the female thread, and judging whether the advanced retraction phenomenon exists by using the thread tail measuring gauge. The measurement start positions thereof are determined as follows:

pitch = 25.4/5 = 5.08mm;

1/4 circumferential thread axial length = 5.08/4 = 1.27mm;

selectively fixed contactSelect the movable contact +.>

The initial position of the screw tail measurement is that the outer end of the female thread is= 98.57-1.27=97.3 mm;

the three contacts of the screw tail measuring gauge are zeroed on the plane, the positioning rule of the screw tail measuring gauge is adjusted and locked at 97.0mm, the positioning rule does not contact the outer end of the female screw thread, the three contacts are arranged at the bottom of the screw thread teeth at a proper position, the screw tail measuring gauge is swung in a small amplitude, the minimum value (basically zero) is found, the screw tail measuring gauge is integrally rotated along the spiral line, when the positioning rule contacts the outer end of the female screw thread, the movable contact enters the checking area, the screw tail is regarded as qualified when the positioning rule rotates for 1/4 weeks, and if the reading of the indicating gauge is not more than +0.005in (+0.13 mm), as shown in fig. 6.

Claims (6)

1. A spiral tail measuring gauge capable of being positioned is characterized in that: comprises a measuring main body and a positioning structure; the measuring main body comprises a gauge outfit and a gauge stand, the gauge outfit is arranged on the gauge stand, a movable contact of the gauge outfit penetrates through the gauge stand, and a first fixed contact and a second fixed contact are also arranged on the gauge stand on one side where the movable contact is arranged; the positioning structure comprises a ruler body and a positioning ruler, the meter frame is connected with the ruler body through a groove slideway, so that the ruler body can move back and forth for a certain distance compared with the meter frame, and the positioning ruler is arranged on the ruler body;

the top ends of the movable contact, the first fixed contact and the second fixed contact are of spherical structures, and the space between the first fixed contact and the second fixed contact isThe distance between the movable contact and the first fixed contact is +.>The diameter of the movable contact is smaller than that of the fixed contact, and the difference is not smaller than 0.20mm.

2. The positionable spiral tail gauge of claim 1, wherein: the ruler also comprises a spring, wherein the spring is positioned in the groove on the ruler body and sleeved on the guide post in the groove, one end of the ruler body is also sleeved on the guide post, and the spring is compressed when the ruler body moves along the guide post.

3. The positionable spiral tail gauge of claim 1, wherein: when the screw tail measuring gauge is used for measuring, the contact pressure between the positioning ruler and the workpiece is not more than 2N.

4. The positionable spiral tail gauge of claim 1, wherein: the measuring precision of the positioning ruler of the screw tail measuring gauge is 0.1mm.

5. The positionable spiral tail gauge of claim 1, wherein: when the petroleum casing pipe thread is a conical thread, the included angle between the conical thread and the axis is alpha, the distance of a certain length L in the axial direction of the thread on the conical thread is Ls, L=ls is cos alpha, the distance between the first fixed contact and the second fixed contact is A, and when A is more than Ls, the second fixed contact is completely contacted with the thread tooth bottom and the thread bearing side during measurement; when A < Ls, the first fixed contact is in full contact with the thread root and the thread carrying side.

6. The positionable spiral tail gauge of claim 1, wherein: in the measuring process, the movable contact and the screw thread always keep a relatively consistent measuring position.