CN111551097A - Arc radius measuring tool - Google Patents

Abstract

The invention relates to an arc radius measuring tool for measuring the radius of a bent pipe after the bent pipe of a metal pipeline is machined in the industries of chemical engineering, boilers and the like, and the arc radius measuring tool comprises a measuring tool body, wherein two sides of the upper part of the measuring tool body are provided with fixed measuring claws which are tightly attached to the arc surface of the inner arc of the bent pipe of a workpiece during working, and the distance between the two fixed measuring claws is the chord length of a measured arc line; a slide way is arranged in the middle of the measuring body, a measuring rod which can freely slide and stretch along the slide way and can stretch out and draw back after the measuring rod extends out is arranged in the slide way, the upper end measuring head of the measuring rod abuts against the middle point of the measured arc line, the chord height of the measured arc line is measured through the measuring rod, a measuring cam which can freely rotate around a pin shaft is arranged in a U-shaped groove at the lower part of the measuring body, and the contour line of the measuring cam is contacted with the lower; the dial disc is fixed on the measuring cam by a rivet and is integrated with the measuring cam, when the dial disc is stirred, the dial disc rotates together with the measuring cam to push the measuring rod to slide and extend out for measuring the arc, and the measuring device has the advantage of being capable of quickly, conveniently and accurately measuring the pipe behind the bent pipe.

Description

A circular arc radius measuring tool

technical field

The invention relates to a circular arc radius measuring tool which is used for measuring the radius of the elbow after the metal pipe elbow is processed in the chemical industry, boiler and other industries.

Background technique

In heat exchange equipment, a large number of heat exchange tubes are often used for medium heat exchange. In order to reduce the number of joints and reduce the probability of welding defects, it is necessary to bend the heat exchange tube. On some compact equipment, stricter requirements are put forward for the bend radius of the heat exchange tube. Therefore, it is necessary to measure the bending radius of the pipe after bending the pipe quickly, conveniently and accurately. Generally, the elbow angle of the heat exchange tube is less than 180°, and because the arc chord length and radius are not linear, it is difficult to directly measure the arc bending radius. Therefore, the existing measuring tools cannot directly measure the R arc radius. . However, it is possible to use the mathematical principle of three points to determine the arc size, analyze the functional relationship between the arc length and the radius, and convert the nonlinear relationship between the arc chord height and radius into an angle (or length) and a There is a linear relationship between the measured arc radii, and then a measuring tool is designed according to this linear relationship to achieve the purpose of directly measuring the arc radius.

SUMMARY OF THE INVENTION

The purpose of the present invention is to overcome the deficiencies in the prior art and provide an arc radius measuring tool that can quickly, conveniently and accurately measure the bending radius of the pipe after bending.

The purpose of the present invention is to achieve this: a circular arc radius measuring tool, including a measuring device, and two fixed measuring claws on the arc surface of the inner arc of the curved pipe of the workpiece during operation are provided on both sides of the upper part of the measuring device. The distance between the claws is the chord length of the arc to be measured; a slideway is set in the middle of the measuring concrete, in which is installed a measuring head that can slide freely along the slideway and stretch out, and the upper end of the measuring head is on the measured arc. The measuring rod at the middle point is used to measure the chord height of the measured arc through the measuring rod. In the U-shaped groove at the lower part of the measuring body, a measuring cam that can rotate freely around the pin shaft is installed through the pin shaft to measure the contour of the cam and the measurement The lower ends of the rods are in contact; the measuring cam is fixed with a dial integrated with it by rivets. When the dial is toggled, the dial rotates together with the measuring cam, and pushes the measuring rod to slide out for arc measurement.

The upper and lower ends of the measuring rod are designed with sharp corners with small R arcs.

A stop pin is fixedly installed on the measuring rod at a lateral position along its telescopic direction, a sliding groove is correspondingly provided on the measuring rod, and the head of the stop pin protrudes through the sliding groove.

A fan-shaped window for reading the measurement data exposing the dial is opened on the concrete of the measurement. The fan-shaped window has a tapered surface, and the tapered surface of the fan-shaped window is engraved with an auxiliary ruler scale line, and the auxiliary ruler scale line is equal to the circumference. Wire.

The material of each part is selected from tool steel and is subjected to quenching treatment.

A circle scale line is arranged on the circumference of the dial, and the circle scale line corresponds to the different contour radii of the measuring cam, and the corresponding arc radius value is marked on the scale line.

The outer edge of the dial protrudes to a specific lower end.

The profile of the measuring cam is made in this way:

The relationship between the radius R of the inner arc circle of the workpiece elbow to be measured, the half chord length A, and the chord height H are as follows:

R ² =A ² +B ² R=H+B

After mathematical derivation, the relationship between the radius R of the inner arc circle, the half chord length A, and the chord height H is:

R=1/2*(A ² /H+H)

Set the chord length 2A as a fixed value, then the radius R of the circle has a unique corresponding relationship with the chord height H. Divide the working part of the measuring cam into equal parts according to the circumference, and then determine each level of the measuring cam according to the relationship between the above formula R and H. The radius H of the part is made, and the contour line of the measuring cam is made according to this method.

There are grooves on both sides of the measuring body, which are convenient for holding by hand when measuring.

The present invention has following positive effect:

1. The present invention has the advantage of being able to quickly, conveniently and accurately measure the pipe after bending.

2. The measuring principle of the present invention refers to the working principle of the vernier caliper and the universal angle ruler, which improves the accuracy of measurement in the circumferential direction, and converts the angle measurement function of the universal angle ruler into measuring the extension length through the cam.

3. The working principle of the vernier caliper is as follows: take a vernier caliper with an accuracy of 0.05 mm as an example, there are 20 equal division scales on the vernier, and the total length is 19 mm. When measuring, if the 11th scale line on the vernier is aligned with the main ruler, the reading of the fractional part is 11/20 mm = 0.55 mm; if the 12th scale line is aligned with the main ruler, the reading of the fractional part is 12/20 mm = 0.60mm. Generally speaking, there are n equal division scales on the vernier, and their total length is equal to the total length of the (n-1) equal division scales on the ruler. If the minimum scale length on the vernier is x, the minimum scale length on the main ruler is y then nx=(n-1)y, x=y-(y/n) The difference between the main scale and the minimum scale of the vernier is Δx=y-x=y/ny/n is called the precision of the vernier caliper, which determines the reading result number of digits. It can be seen from the formula that improving the measurement accuracy of the vernier caliper lies in increasing the number of scales on the vernier or reducing the minimum scale value on the main scale. In general, y is 1 mm, and n is 10, 20, and 50, and the corresponding precisions are 0.1, 0.05 mm, and 0.02 mm.

The reading mechanism of the universal angle ruler is made according to the vernier principle. Each division of the main ruler is 1°. The reticle of the vernier is divided into 30 grids by taking 29° of the main ruler, so the angle grid of the vernier reticle is 29°/30, that is, the difference between the main ruler and the vernier grid is 2', that is to say, the reading of the universal angle ruler is 2'. Accuracy is 2'. In addition, there are 5' and 10' precision. The reading method is exactly the same as that of a vernier caliper.

4. The dial and the cam of the present invention are fixed together, and the scale lines on the circumference of the dial correspond to different cam radii. The scale of the dial is equivalent to the main scale line of the universal angle ruler, and each division is 1°. The scale of the specific fan-shaped window is equivalent to the vernier scale. The scale of the vernier can be divided into 30 grids equal to 29° of the main ruler, so the angle grid of the vernier scale is 29°/30, that is, the main scale and the vernier are one grid. The difference is 2', which means that the reading accuracy of the universal angle ruler is 2'. If the requirements for measurement accuracy are lower, the scale of the specific window can be divided into 6 grids equal to 5° of the main ruler, so the angle grid of the vernier scale is 5°/6, that is, the difference between the main scale and the vernier is one grid. 10', which means that the reading accuracy of the universal angle ruler is 10'.

Description of drawings

FIG. 1 is a schematic diagram of the structure of the R arc radius measuring tool of the present invention.

FIG. 2 is a schematic measurement diagram of the R arc radius measuring tool of the present invention.

FIG. 3 is a front view of the quantity concrete 4 of the present invention.

FIG. 4 is a left sectional view of the quantity concrete 4 of the present invention.

FIG. 5 is a front view of the riveted combination of the measuring cam 5 and the dial 7 of the present invention.

FIG. 6 is a cross-sectional view of the riveted combination of the measuring cam 5 and the dial 7 of the present invention.

FIG. 7 is an assembly view of the measuring rod 3 and the stopper pin 8 of the present invention.

8 is a graph showing the relationship between the radius R of the circle, the half chord length A, and the chord height H according to the present invention.

In the figure 1. Inner arc of elbow, 2. R arc radius measuring tool, 3. Measuring rod, 4. Measuring specific, 5. Measuring cam, 6. Pin shaft, 7. Dial, 8. Stop pin.

Detailed ways

As shown in Figures 1 and 2, a circular arc radius measuring tool includes a measuring body 4. On both sides of the upper part of the measuring body 4, there are fixed measuring claws which are close to the arc surface of the inner arc 1 of the workpiece elbow during operation. Two The distance between the fixed measuring claws is the chord length of the measured arc; a slideway is arranged in the middle of the measuring body 4, and in the slideway is installed a measuring head that can slide freely along the slideway and stretch out, and the upper end of the measuring head is placed on the surface of the measured body. The measuring rod 3 at the middle point of the measuring arc is used to measure the chord height of the measured arc through the measuring rod 3. The measuring cam 5 is installed in the U-shaped groove of the lower part of the measuring body 4 through the pin shaft 6, and the measuring cam 5 can go around the pin shaft 6. Free rotation, the contour line of the measuring cam 5 is in contact with the lower end of the measuring rod 3; the measuring cam 5 is fixed with a dial 7 integrated with it by rivets, and the dial 7 rotates together with the measuring cam 5 when the dial 7 is toggled , push the measuring rod 3 to slide out the specific amount 4 and carry out the arc measurement. Both the upper and lower ends of the measuring rod 3 are designed with sharp corners, and the sharp corners have a small R arc.

A stopper pin 8 is fixedly installed on the measuring rod 3 at a lateral position along its telescopic direction, and a sliding groove is formed on the measuring rod 4 correspondingly.

FIG. 1 is a schematic structural diagram of the present invention (invention). The two sides of the upper part of the measuring concrete 4 are fixed measuring claws, which are close to the arc surface of the inner arc 1 of the workpiece elbow when working, which is equivalent to determining the chord length of the arc to be measured. The two ends of the measuring rod 3 are designed with sharp angles (to reduce friction, wear and improve service life, with a small R arc) installed on the slideway in the middle of the measuring rod 4, which can freely slide and expand along the slideway, and its upper end extends out. (probe) can be placed on the middle point of the arc under test, which is equivalent to measuring the chord height of the arc under test.

The measuring cam 5 is installed in the U-shaped groove in the lower part of the measuring body 4 through the pin 6 and can rotate freely around the pin 6 . The contour line of the measuring cam 5 is in contact with the sharp corner of the lower end of the measuring rod 3 . When the measuring cam 5 rotates, the measuring rod 3 is pushed to extend along the slideway.

As shown in FIG. 5 and FIG. 6 , the dial 7 and the measuring cam 5 are fixed as a whole by rivets, and the circumference scale lines on the circumference of the dial 7 correspond to the different contour radii of the measuring cam 5 . And mark the corresponding arc radius value on the scale line.

A fan-shaped window for reading the measurement data of the scale plate 7 is opened on the top of the measuring unit 4. The fan-shaped window has a tapered surface, and the tapered surface of the fan-shaped window is engraved with an auxiliary ruler scale line, and the auxiliary ruler scale line is a circle. Equal lines.

Circumferential scale lines are arranged on the circumference of the dial 7, and the circumferential scale lines correspond to different contour radii of the measuring cam 5, and the corresponding arc radius values are marked on the scale lines. The outer edge of the dial 7 protrudes to the lower end of the specific 4 . The two sides of the measuring body 4 are provided with grooves which are convenient for holding by hand during measurement.

Figure 8 is a diagram showing the relationship between the radius R of the circle, the half chord length A, and the chord height H. The relationship between the parameters in the figure is:

R ² =A ² +B ²

R=H+B

After mathematical derivation, the relationship between the radius R of the circle, the half chord length A, and the chord height H is:

R=1/2*(A ² /H+H)

If the chord length 2A is set as a fixed value, the radius R of the circle has a unique corresponding relationship with the chord height H. Divide the working part of the measuring cam 5 into equal parts according to the circumference, and then determine the radius (H) of each equal part of the measuring cam 5 according to the relationship between the above formulas R and H, and make the contour line of the measuring cam 5 according to this method. Then the rotation angle of the measuring cam 5 made by the above method has a corresponding linear relationship with the radius R of the arc to be measured.

Figure 2 is a schematic diagram of the measurement of the R arc radius measuring tool. Figures 3 and 4 are structural diagrams of the quantity concrete 4. A fan-shaped window is opened on the top of the measurement unit 4, so that the measurement data can be read. In order to improve the measurement and display accuracy, referring to the scale value display principle of the vernier caliper, according to the measurement accuracy requirements, engraved on the conical surface of the fan-shaped window a circular bisector line---the secondary ruler scale line, the fan-shaped arc bisector line (the secondary ruler scale). The bisector angle value of the line) can be 0.5, 0.8, 0.9 times of the bisector line on the dial 7---the angle value of the scale line of the main ruler, and the measurement and display accuracy of the main ruler can be increased by 2 times, 5 times, 10 times, respectively. times.

The dial 7 also functions as a manual dial. As can be seen from FIG. 2 , the outer edge of the dial 7 protrudes by the lower end portion of the specific 4 . The outer edge of the dial 7 is moved by hand, the dial 7 rotates together with the measuring cam 5, and the measuring rod 3 is pushed to slide out to perform the arc measurement.

A stop pin 8 is installed on the measuring rod 3 . The stop pin 8 can prevent the measuring rod 3 from slipping out of the slideway of the measuring body 4, and can also be moved by hand to help the measuring rod 3 retract.

The grooves on both sides of the measuring unit are designed for easy gripping by hand during measurement.

The two sides of the upper part of the measuring concrete 4 are fixed measuring claws, which are close to the arc surface of the inner arc 1 of the workpiece elbow when working. The measuring rod 3 is installed on the slideway in the middle of the measuring body 4, and can freely slide and extend along the slideway. The measuring cam 5 is installed in the U-shaped groove at the lower part of the measuring body 4 through the pin 6 and can rotate freely around the pin 6 . When the measuring cam 5 rotates, the measuring rod 3 is pushed to extend along the slideway. The dial 7 and the measuring cam 5 are integrally fixed by rivets. The dial 7 also functions as a manual dial. When the outer edge of the dial 7 is moved by hand, the dial 7 rotates together with the measuring cam 5, and pushes the measuring rod 3 to slide out for arc measurement. The measuring rod 3 is provided with a stop pin 8, which can prevent the measuring rod 3 from slipping out of the slideway of the measuring concrete 4, and can also be moved by hand to help the measuring rod 3 retract.

In order to improve the service life of the measuring tool, tool steel is selected as the material of each part and quenched. After the measuring tool is assembled, the measuring rod 3 slides, and the riveted part between the measuring cam 5 and the dial 7 rotates flexibly.

Before using the measuring tool, turn the dial 7 and move the stop pin 8 to retract the measuring rod 3 to the lowest position in the measuring device 4 .

As shown in Figure 1 and Figure 2, when using, hold the grooves on both sides of the measuring unit 4 by hand, and place the measuring tool on the inner arc of the measured arc, so that the fixed measuring claws on both sides of the measuring unit 4 are close to the arc surface of the workpiece . Turn the dial 7, the dial 7 drives the measuring cam 5 to rotate, and the lower end of the measuring rod 3 is in contact with the outer contour of the measuring cam 5. Under the push of the measuring cam 5, the measuring rod 3 extends out along the chute, and the upper end of the measuring rod 3 is to be measured. When the (probe) touches the arc surface of the workpiece to be measured, stop rotating the dial 7. Read the R arc radius size displayed by the scale of the specific 4 sector window, and complete the measurement of the R arc radius size.

The display principle of the measuring tool is to convert the linear scale display principle of the vernier caliper into a circular scale display. When reading the value, first read the number of the main scale line before the 0 line of the sub-scale scale line, for example, 62, and then read the number of the sub-scale scale line aligned with the main scale line, such as 8, then all The measured arc radius is 62.8mm.

When measuring, first of all, it should be ensured that the fixed measuring claws on both sides of the specific 4 are close to the arc surface of the workpiece and cannot be attached to the straight line segment, otherwise the real data of the arc radius cannot be measured; secondly, in order to improve the measurement accuracy, moderate force should be used to ensure The workpiece and the measuring claw and the measuring head of the measuring tool are reliably fitted.

The dial 7 and the cam 5 of the present invention are fixed together, and the circumferential scale lines of the dial 7 correspond to different cam radii. The scale of the dial 7 is equivalent to the main scale line of the universal angle ruler, and each division is 1°. The scale of the 4-sector window is equivalent to the vernier scale. The scale of the vernier can be divided into 30 grids by taking 29° of the main ruler, so the angle grid of the vernier scale is 29°/30, that is, the main scale and the vernier are one grid. The difference is 2', which means that the reading accuracy of the universal angle ruler is 2'. If the measurement accuracy is required to be lower, the scale of the specific 4 windows can be divided into 6 grids by taking 5° of the main ruler, so the angle grid of the vernier scale line is 5°/6, that is, the difference between the main scale and the vernier grid. is 10', which means that the reading accuracy of the universal angle ruler is 10'.

Claims (9)

1. A circular arc radius measuring tool, comprising a measuring device (4), characterized in that: a fixed amount on the camber surface of the inner arc (1) of a workpiece elbow is provided on both sides of the upper part of the measuring device (4) during work. Claws, the distance between the two fixed measuring claws is the chord length of the measured arc; a slideway is arranged in the middle of the measuring body (4), and a slideway is installed in the slideway that can freely slide and extend along the slideway and stretch out. The measuring rod (3) whose upper end probe is placed at the middle point of the measured arc, measures the chord height of the measured arc through the measuring rod (3), and passes the pin shaft (6) in the lower U-shaped groove of the measuring concrete (4). A measuring cam (5) is installed, the measuring cam (5) rotates freely around the pin shaft (6), and the contour line of the measuring cam (5) is in contact with the lower end of the measuring rod (3). A dial (7) integrated with it is fixed. When the dial (7) is toggled, the dial (7) rotates together with the measuring cam (5), push the measuring rod (3) to slide the specific extension (4) and carry out Arc measurement. 2. A circular arc radius measuring tool according to claim 1, characterized in that: both the upper end probe and the lower end of the measuring rod (3) are designed into sharp corners, and the sharp corners have small R arcs. 3. A circular arc radius measuring tool according to claim 1, characterized in that: a stop pin (8) is fixedly installed on the measuring rod (3) along the lateral position of its telescopic direction, corresponding to the measuring rod (4) The upper part is provided with a sliding groove, and the head of the blocking pin (8) protrudes through the sliding groove by a specific amount (4). 4. A kind of circular arc radius measuring tool according to claim 1 is characterized in that: a fan-shaped window for reading measurement data exposing the dial (7) is provided on the top of the measuring body (4), and the fan-shaped window has a There is a tapered surface, and a secondary ruler scale line is engraved on the cone surface of the fan-shaped window, and the secondary ruler scale line is a circle bisector. 5 . The arc radius measuring tool according to claim 1 , wherein the material of each part is selected from tool steel and quenched. 6 . 6. a kind of circular arc radius measuring tool according to claim 1, is characterized in that: on the circumference of dial (7), be provided with circumference scale line, and circumference scale mark is corresponding with the different contour radii of measuring cam (5), And mark the corresponding arc radius value on the scale line. 7 . The arc radius measuring tool according to claim 1 , wherein the outer edge of the dial ( 7 ) protrudes from the lower end of the specific ( 4 ). 8 . 8. a kind of circular arc radius measuring tool according to claim 1, is characterized in that: the outline of described measuring cam (5) is made according to this method: The relationship between the radius R of the inner arc circle of the workpiece elbow to be measured, the half chord length A, and the chord height H are as follows: R ² =A ² +B ² R=H+B After mathematical derivation, the relationship between the radius R of the inner arc circle, the half chord length A, and the chord height H is: R=1/2*(A ² /H+H) Set the chord length 2A as a fixed value, then the radius R of the circle has a unique corresponding relationship with the chord height H. Divide the working part of the measuring cam (5) into equal parts according to the circumference, and then determine the measuring cam according to the relationship between R and H above. (5) The radius H of each equal part, and make the contour line of the measuring cam (5) according to this method. 9 . A circular arc radius measuring tool according to claim 1 , characterized in that grooves are provided on both sides of the measuring body ( 4 ), which are convenient to be clamped by hand during measurement. 10 .

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