Device for measuring inner diameter of pipeline

Abstract

The utility model provides a device for measuring the inner diameter of a pipeline, which belongs to the technical field of inner diameter measurement, and comprises a first clamp body, a second clamp body and a pin shaft, the second clamp body is arranged close to the first clamp body, the pin shaft passes through the middle parts of the first clamp body and the second clamp body, and the second clamp body and the first clamp body can relatively rotate around the pin shaft in the circumferential direction; the upper half portion and the lower half portion of the first clamp body and the upper half portion and the lower half portion of the second clamp body are arranged around the pin shaft in an annular array mode. Wherein the same end of the first clamp body and the same end of the second clamp body are inserted into a part hole and abut against the inner wall of the hole at the same time, and the inner diameter size of the part hole is obtained by measuring the distance between the other end of the first clamp body and the other end of the second clamp body. The device for measuring the inner diameter of the pipeline provided by the utility model has the technical effects that the size can be directly measured without taking out the device from a part, the measurement result is accurate, the error is reduced, and the operation is time-saving and labor-saving.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the technical field of internal diameter measurement, more specifically, relates to a device for measuring the internal diameter of a pipe. BACKGROUND

[0002] An internal calliper is a kind of metal tool calliper used for measuring internal diameter and groove, and belongs to a kind of calliper. Another corresponding one is an external calliper, which is used for measuring the external diameter of a cylinder or the length of an object. The internal calliper and the external calliper do not have the function of directly reading the measurement result, but the length size (internal diameter also belongs to the length size) is measured by using a steel ruler or a vernier caliper to read the result, or the required size is taken off a steel ruler to check whether the diameter of a part is consistent. The internal calliper is usually used in combination with an external diameter percentage ruler to measure the internal hole size. This internal diameter measurement method is called "internal calliper percentage ruler", which uses the internal calliper to read the accurate size on the external diameter percentage ruler, and then measures the internal diameter of a part. Or the internal calliper adjusts the tightness of contact with the hole, and then reads the specific size on the external diameter percentage ruler. This measurement method is not only a good method for measuring the internal diameter when there is a lack of precise internal diameter measuring tools, but also solves the problem of measuring the internal diameter of a part when there is a shaft in the hole, which makes it difficult to use a precise internal diameter measuring tool.

[0003] However, when the internal calliper is used in combination with the external diameter percentage ruler to measure the internal diameter of a part, the internal calliper needs to be taken out of the part and then the external diameter percentage ruler is used to measure the size. If the internal calliper is loose during the removal process, it will cause size measurement error and length measurement deviation. Moreover, when multiple holes with different diameters or stepped holes in a part need to be measured, the internal calliper needs to be used multiple times, the external diameter percentage ruler needs to be used multiple times to read the size and record the size, and the multiple measurements of the internal calliper will result in inaccurate measurement of holes with different diameters, which is troublesome and causes waste of time and energy. TECHNICAL SOLUTION

[0004] The utility model aims at providing a device for measuring the internal diameter of a pipe, which aims to solve the technical problem that the internal calliper needs to be taken out of a part hole and then an external diameter percentage ruler is used to measure the size when the internal calliper is used in combination with the external diameter percentage ruler to measure the internal diameter of a part hole in the prior art.

[0005] To achieve the above-mentioned purpose, the utility model adopts the technical scheme of providing a device for measuring the internal diameter of a pipe, which comprises:

[0006] The first calliper body has protruding structures at both ends and is in the shape of a Z letter.

[0007] The second calliper body is arranged close to the first calliper body and has protruding structures at both ends and is in the shape of an inverted Z letter.

[0008] a pin shaft is arranged through the middle of the first jaw body and the second jaw body, the first jaw body and the second jaw body can rotate around the pin shaft circumferentially relative to each other; when the first jaw body and the second jaw body are arranged vertically, the structure located at the upper part of the pin shaft is defined as the upper half, and the structure located at the lower part of the pin shaft is defined as the lower half, the upper half and the lower half of the first jaw body, the upper half and the lower half of the second jaw body are arranged in an annular array around the pin shaft;

[0009] wherein the same end of the first jaw body and the second jaw body is inserted into the inside of the part hole and abuts against the inner wall of the hole at the same time, and the distance between the other end of the first jaw body and the other end of the second jaw body is measured to obtain the inner diameter size of the part hole.

[0010] In a possible implementation, the device for measuring the inner diameter of the pipeline further comprises:

[0011] a third jaw body is arranged close to the second jaw body, both ends of which are provided with protruding structures, and the third jaw body is arranged in a Z-shaped manner;

[0012] a fourth jaw body is arranged close to the third jaw body, both ends of which are provided with protruding structures, and the fourth jaw body is arranged in an inverted Z-shaped manner;

[0013] wherein the middle part of the third jaw body and the middle part of the fourth jaw body are rotationally connected with the pin shaft, the third jaw body and the fourth jaw body can rotate around the pin shaft circumferentially relative to each other, and the upper half and the lower half of the third jaw body and the upper half and the lower half of the fourth jaw body are arranged in an annular array around the pin shaft; the same end of the third jaw body and the fourth jaw body is inserted into the inside of the part hole and abuts against the inner wall of the hole at the same time, and the distance between the other end of the third jaw body and the other end of the fourth jaw body is measured to obtain the inner diameter size of the part hole.

[0014] In a possible implementation, the length of the third jaw body or the fourth jaw body is smaller than the length of the first jaw body or the second jaw body.

[0015] In a possible implementation, the third jaw body and the fourth jaw body each comprise:

[0016] a fixed rod, the middle part of which is rotationally connected with the pin shaft, and both ends of which are provided with first insertion holes extending into the inside thereof;

[0017] two extension rods, each of which is provided with a second insertion hole extending into the inside thereof at one end, and the protruding structure is located at the end of the extension rod away from the second insertion hole;

[0018] Two telescopic rods, one end of each of which is respectively inserted into two first insertion holes, and the other end of each of which is respectively inserted into two second insertion holes, both ends of the telescopic rods have the freedom of sliding insertion into the first insertion holes and the second insertion holes, and the length of the third jaw body or the fourth jaw body is adjusted by adjusting the insertion depth of the telescopic rods.

[0019] In a possible implementation, the fixed rod is provided with locking holes near the two end positions and the two end positions of the two extension rods away from the protruding structure, a jackscrew is installed in the locking hole, and the jackscrew is screwed to abut and lock the telescopic rod.

[0020] In a possible implementation, the telescopic rod comprises a plurality of rod bodies which are detachably connected to each other in a head-to-tail manner, and the rod bodies at both ends of the telescopic rod are respectively used for sliding insertion into the first insertion hole and the second insertion hole.

[0021] In a possible implementation, the protruding structure of the second jaw body and / or the fourth jaw body is hinged with a rotating block, one end of the rotating block is fixedly connected with one end of a measuring scale, the end of the measuring scale close to the protruding structure is flush with the end of the protruding structure, the protruding structure of the first jaw body and / or the third jaw body is hinged with an indicating block, and the indicating block is used for indicating the scale on the measuring scale after the measuring scale abuts against the indicating block.

[0022] In a possible implementation, the end of the indicating block in contact with the measuring scale is pointed.

[0023] In a possible implementation, the protruding structure of the second jaw body and / or the fourth jaw body is connected with a lock, and the lock is used for locking the position of the rotating block after rotation.

[0024] In a possible implementation, the middle part of the first jaw body and the second jaw body is wider than the two ends, and the end of the protruding structure in contact with the part is arc-shaped.

[0025] The beneficial effects of the device for measuring the inner diameter of a pipe provided by this utility model are as follows: Compared with the prior art, the device for measuring the inner diameter of a pipe according to this utility model includes a first clamp body, a second clamp body, and a pin. The first clamp body has protruding structures at both ends and is Z-shaped. The second clamp body is positioned close to the first clamp body and also has protruding structures at both ends, forming an inverted Z-shape. The pin passes through the middle of the first and second clamp bodies, allowing the second and first clamp bodies to rotate relative to each other circumferentially around the pin. When the first and second clamp bodies are vertically positioned, the structure located above the pin is defined as the upper half, and the structure located below the pin is defined as the lower half. The upper and lower halves of the first clamp body and the upper and lower halves of the second clamp body are arranged in a circular array around the pin shaft. The same end of the first clamp body and the second clamp body are inserted into the hole of the part and simultaneously abut against the inner wall of the hole. The inner diameter of the part hole is obtained by measuring the distance between the other ends of the first clamp body and the other ends of the second clamp body. This solves the technical problem in the prior art that when using an internal caliper with an external micrometer to measure the inner diameter of a part hole, it is necessary to remove the internal caliper from the part hole and then use the external micrometer to measure the size, which is a relatively troublesome operation. It has the technical effect of directly measuring the size without removing it from the part, with more accurate measurement results, reduced errors, and time-saving and labor-saving operation. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 A schematic diagram of a device for measuring the inner diameter of a pipe provided in an embodiment of this utility model;

[0028] Figure 2 A schematic diagram of a device for measuring the inner diameter of a pipe provided in this embodiment of the present invention, in the state of measuring the inner diameter of a part (the cylindrical structure at the lower end represents the part whose inner diameter is to be measured).

[0029] Figure 3 A front view schematic diagram of a device for measuring the inner diameter of a pipe, provided for another embodiment of this utility model;

[0030] Figure 4 for Figure 3 The diagram shows a device for measuring the inner diameter of a pipe in a state where it is measuring the inner diameter of a part (the cylindrical structure at the lower end represents the part whose inner diameter is to be measured).

[0031] Figure 5A kind of main view structural schematic diagram of the device for measuring the inner diameter of pipeline provided in another embodiment of the utility model;

[0032] Figure 6 A kind of main view structural schematic diagram of the device for measuring the inner diameter of pipeline provided in another embodiment of the utility model;

[0033] Figure 7 For Figure 6 Upper structure schematic diagram in it;

[0034] Figure 8 For Figure 7 The state schematic diagram after the rotation of measuring scale in it;

[0035] Figure 9 For Figure 6 Or Figure 7 The plan view of measuring scale in it.

[0036] Mark explanation:

[0037] 1, first jaw body;2, second jaw body;3, pin shaft;4, convex structure;5, third jaw body;51, fixed rod;52, extension rod;53, telescopic rod;531, rod body;54, first jack;55, second jack;56, locking hole;6, fourth jaw body;7, rotating block;8, measuring scale;9, indicating block;10, lock. Specific embodiments

[0038] In order to make the technical problems, technical scheme and beneficial effects to be solved by the utility model more clear and obvious, the utility model is further described in detail in the following with the aid of drawings and embodiments.It should be understood that the specific embodiments described herein are only used to explain the utility model, and are not used to limit the utility model.

[0039] Please see Figures 1 to 9The utility model provides a kind of device for measuring pipe inner diameter, and the device is described as follows.The device for measuring pipe inner diameter includes first jaw body 1, second jaw body 2 and pin shaft 3, first jaw body 1 is provided with protruding structure 4 at both ends, and first jaw body 1 is in Z shape.Second jaw body 2 is arranged close to first jaw body 1, and is also provided with protruding structure 4 at both ends, and second jaw body 2 is in reverse Z shape.Pin shaft 3 is arranged through the middle of first jaw body 1 and second jaw body 2, and second jaw body 2 and first jaw body 1 can rotate circumferentially around pin shaft 3.When first jaw body 1 and second jaw body 2 are arranged vertically, the structure above pin shaft 3 is defined as upper half, and the structure below pin shaft 3 is defined as lower half, and first jaw body 1, second jaw body 2, first jaw body 1 upper half and lower half, second jaw body 2 upper half and lower half are arranged in annular array around pin shaft 3.Wherein, the same end of first jaw body 1 and second jaw body 2 is inserted into the inside of part hole, and abuts against the inner wall of hole at the same time, and the distance between the other end of first jaw body 1 and the other end of second jaw body 2 is measured to obtain the inner diameter size of part hole.

[0040] Compared with the prior art, the device for measuring pipe inner diameter provided by the utility model is provided with first jaw body 1 and second jaw body 2 connected with each other in rotation, one end of which is placed in the inner hole of a part, and the other end can be used to measure the inner diameter by using a tool, so that the measuring method is simple, and the technical problem that in the prior art, when the inner calliper is used to measure the inner diameter of a part hole together with an outer diameter vernier, the inner calliper needs to be taken out from the part hole and then an outer diameter vernier is used to measure the size, which is relatively troublesome, is solved, and the device has the technical effects that the size can be directly measured without taking out the part, the measurement result is more accurate, errors are reduced, and the operation is time-saving and labor-saving.

[0041] In the embodiment, first jaw body 1 and second jaw body 2 are arranged in a stacked manner, which is similar to the arrangement of scissors.Pin shaft 3 penetrates first jaw body 1 and second jaw body 2 and can rotate.The length and material of first jaw body 1 and second jaw body 2 are not limited.First jaw body 1 and second jaw body 2 can be regarded as having the same structure, except that they are arranged in opposite directions.

[0042] When it is necessary to measure multiple holes or stepped holes with different diameters in a part, in some embodiments, please refer to Figures 3 to 4, the device for measuring the inner diameter of a pipeline further comprises a third jaw body 5 and a fourth jaw body 6, the third jaw body 5 is arranged close to the second jaw body 2, both ends of the third jaw body 5 are provided with protruding structures 4, and the third jaw body 5 is arranged in a Z shape; the fourth jaw body 6 is arranged close to the third jaw body 5, both ends of the fourth jaw body 6 are provided with protruding structures 4, and the fourth jaw body 6 is arranged in an inverse Z shape; wherein the middle part of the third jaw body 5 and the middle part of the fourth jaw body 6 are rotationally connected with the pin shaft 3, the third jaw body 5 and the fourth jaw body 6 can rotate circumferentially relative to the pin shaft 3, and the upper half and the lower half of the third jaw body 5 and the upper half and the lower half of the fourth jaw body 6 are arranged in an annular array around the pin shaft 3; the same end of the third jaw body 5 and the fourth jaw body 6 is inserted into the inside of the hole of the part, and simultaneously abuts against the inner wall of the hole, and the distance between the other end of the third jaw body 5 and the other end of the fourth jaw body 6 is measured to obtain the inner diameter size of the hole of the part. The first jaw body 1 and the second jaw body 2 are arranged at a relatively deep position in the hole of the part, while the third jaw body 5 and the fourth jaw body 6 are arranged at a relatively shallow position in the part, so that two holes with different diameters can be measured at the same time, the measurement efficiency is improved, and the result can be obtained by measuring once without multiple measurements. It should be noted that the vernier is used to measure the size twice, i.e. the distance between the first jaw body 1 and the second jaw body 2 and the distance between the third jaw body 5 and the fourth jaw body 6. The plurality of protruding structures 4 are the same in structure. The middle part of the first jaw body 1, the second jaw body 2, the third jaw body 5 and the fourth jaw body 6 is provided with a mounting hole, the pin shaft 3 passes through the mounting hole, and the first jaw body 1, the second jaw body 2, the third jaw body 5 and the fourth jaw body 6 can rotate around the pin shaft 3 or can be stacked together in a stacked manner.

[0043] The first jaw body 1, the second jaw body 2, the third jaw body 5 and the fourth jaw body 6 are sequentially arranged in the axial direction of the pin shaft 3.

[0044] In some embodiments, referring to Figures 3 to 4 The length of the third jaw body 5 or the fourth jaw body 6 is less than the length of the first jaw body 1 or the second jaw body 2. The third jaw body 5 or the fourth jaw body 6 is used for measuring the inner diameter of a hole with a relatively shallow depth in a part hole, so the length thereof is set to be relatively short.

[0045] In some embodiments, referring to Figures 5 to 6, the third jaw body 5 and the fourth jaw body 6 each include a fixed rod 51, two extension rods 52 and two telescopic rods 53, the middle part of the fixed rod 51 is rotationally connected with the pin shaft 3, and both ends are provided with a first insertion hole 54 extending to the inside thereof; one end of each of the two extension rods 52 is provided with a second insertion hole 55 extending to the inside thereof, and the protruding structure 4 is located at the end of the extension rod 52 away from the second insertion hole 55; one end of each of the two telescopic rods 53 is respectively inserted into the two first insertion holes 54, and the other end is respectively inserted into the two second insertion holes 55, both ends of the telescopic rod 53 have the freedom of insertion and sliding in the first insertion hole 54 and the second insertion hole 55, and the length of the third jaw body 5 or the fourth jaw body 6 is adjusted by adjusting the insertion depth of the telescopic rod 53. The middle part of the fixed rod 51 is rotationally connected with the pin shaft 3, the mounting hole is arranged in the middle part of the fixed rod 51, the fixed rod 51 can rotate around the pin shaft 3 in the circumferential direction, and the position of the extension rod 52 can be adjusted by means of the telescopic rod 53 to measure the inner diameter of the hole in the part at different positions. The position of the extension rod 52 can be adjusted by adjusting the length of the telescopic rod 53. It should be noted that the plurality of telescopic rods 53 are adjusted at the same time, and the length of the third jaw body 5 and the fourth jaw body 6 is kept consistent, and the structural size is the same.

[0046] As a preferred, when the telescopic rod 53 is in the longest state, the length of the third jaw body 5 or the fourth jaw body 6 is also less than the length of the first jaw body 1 or the second jaw body 2.

[0047] To achieve the locking or fixing of the telescopic rod 53, in some embodiments, please refer to Figures 5 to 8 , the fixed rod 51 is provided with a locking hole 56 near the two end positions and the end positions of the two extension rods 52 away from the protruding structure 4, a jack screw is installed in the locking hole 56, and the jack screw is used to abut against the telescopic rod 53. When it is necessary to fix the telescopic rod 53, that is, to fix the length of the third jaw body 5 or the fourth jaw body 6, the inner end of the jack screw abuts against the telescopic rod 53 by screwing the jack screw, and the telescopic rod 53 is fixed at this time. Conversely, by screwing the jack screw in the opposite direction, the locking or fixing of the telescopic rod 53 can be released, and at this time the insertion depth of the telescopic rod 53 can be flexibly adjusted, that is, the length of the third jaw body 5 or the fourth jaw body 6 can be adjusted.

[0048] Specifically, the jack screw is a screw, which can abut against or be inserted into the telescopic rod 53 to achieve the effect of fixing.

[0049] To achieve the adjustment of the length of the telescopic rod 53 itself, in some embodiments, please refer to Figures 5 to 8The telescopic rod 53 comprises a plurality of rod bodies 531 which are detachably connected to each other in a head-to-tail manner, and the rod bodies 531 at both ends of the telescopic rod 53 are respectively used for being slidingly inserted into the first insertion hole 54 and the second insertion hole 55. By using different numbers of rod bodies 531, the length adjustment of the telescopic rod 53 can be achieved after combination. The rod bodies 531 are detachably connected to each other by fasteners, and according to actual conditions, a reasonable number of rod bodies 531 can be selected to realize the measurement of the inner diameter of the hole at different depths in the part.

[0050] In order to reduce the use of the vernier, integrate the size measurement and reading, and facilitate the direct measurement of the size and reading, in some embodiments, please refer to Figures 7 to 9 The convex structure 4 of the second jaw body 2 and / or the fourth jaw body 6 is hinged with a rotating block 7, one end of the rotating block 7 is fixedly connected with one end of a measuring scale 8, and the end of the measuring scale 8 close to the convex structure 4 is arranged flush with the end of the convex structure 4. The convex structure 4 of the first jaw body 1 and / or the third jaw body 5 is hinged with an indicating block 9. After the measuring scale 8 abuts against the indicating block 9, the indicating block 9 is used to indicate the scale on the measuring scale 8. During measurement, the rotating block 7 can be appropriately rotated, and when the first jaw body 1 and the second jaw body 2 are fixed, or the third jaw body 5 and the fourth jaw body 6 are fixed, the measuring scale 8 can be rotated and abutted against the indicating block 9 at this time. Through the corresponding scale indicated by the indicating block 9, the hole inner diameter size information can be obtained at the first time, and the vernier measurement can not be used at this time. Figure 7 and Figure 8 In the above two embodiments, the right end of the measuring scale 8 is arranged in alignment with the right end of the convex structure 4, and the left end of the indicating block 9 is arranged in alignment with the left end of the convex structure 4. At this time, through the scale indicated by the indicating block 9, the size of the hole inner diameter can be obtained without addition and subtraction calculation. The indicating block 9 is horn-shaped, and can be rotated relative to the convex structure 4. The position after rotation can be fixed.

[0051] The measuring scale 8 has a scale line. Please refer to Figure 9 The measuring scale 8 is located between the first jaw body 1 and the second jaw body 2, and is located between the third jaw body 5 and the fourth jaw body 6, which does not affect the measurement.

[0052] In some embodiments, please refer to Figures 7 to 9 The end of the indicating block 9 in contact with the measuring scale 8 is sharp-shaped, which aims to point to the scale more accurately and facilitate reading.

[0053] In some embodiments, please refer to Figures 7 to 8The convex structure 4 of the first jaw 1 and / or the second jaw 2 is connected with a lock 10, which is used to lock the position of the rotating block 7 after rotation. During measurement, the measuring scale 8 can be appropriately rotated, which is convenient for operation. When reading is needed, the measuring scale 8 is close to the indicating block 9. In order to lock the rotating block 7 and fix the measuring scale 8, the lock 10 is used to fix the rotating block 7. The lock 10 is a component in the prior art (such as a clamping piece, a screw, etc.), which can lock the position of the rotating block 7 with the freedom of circumferential rotation, and can also release the lock of the rotating block 7.

[0054] In order to connect the first jaw 1 or the second jaw 2 with the pin shaft 3, in some embodiments, please refer to Figures 1 to 8 The middle width of the first jaw 1 and the second jaw 2 is greater than the width of the two ends, and the width gradually decreases from the middle to the end. The end of the convex structure 4 in contact with the part is arc-shaped, which is convenient for abutting to the hole wall of the part and forming contact with the hole wall, and convenient for measurement. As a preferred, the middle width of the third jaw 5 and the fourth jaw 6 is greater than the width of the two ends, and the width gradually decreases from the middle to the end.

[0055] The above only describes the preferred embodiments of the present application, and is not used to limit the present application. Any modification, equivalent replacement and improvement within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A device for measuring the internal diameter of a pipe, characterized in that, The utility model relates to a kind of gauge pin, including: First jaw, both ends have protruding structure, the first jaw is Z-shaped; Second jaw, close to the first jaw is arranged, both ends have protruding structure, the second jaw is anti-Z-shaped; Pin shaft, middle part is arranged in the first jaw and the second jaw, the second jaw and the first jaw can be rotated around the pin shaft circumferentially;When the first jaw and the second jaw are vertically arranged, the structure defined in the upper part of the pin shaft is upper half, the structure defined in the lower part of the pin shaft is lower half, the first jaw upper half and lower half, the second jaw upper half and lower half are arranged in annular array around the pin shaft; Wherein, the same end of the first jaw and the second jaw is inserted into the hole of part, and simultaneously abuts the hole inner wall, the distance between the other end of the first jaw and the other end of the second jaw is measured to obtain the inner diameter size of the hole of part; Further including: third jaw, close to the second jaw is arranged, both ends have protruding structure, the third jaw is Z-shaped arrangement; Fourth jaw, close to the third jaw is arranged, both ends have protruding structure, the fourth jaw is anti-Z-shaped arrangement; Wherein, the middle part of the third jaw and the middle part of the fourth jaw are rotatably connected with the pin shaft, the third jaw and the fourth jaw can be rotated around the pin shaft circumferentially, the third jaw upper half and lower half, the fourth jaw upper half and lower half are arranged in annular array around the pin shaft;The same end of the third jaw and the fourth jaw is inserted into the hole of part, and simultaneously abuts the hole inner wall, the distance between the other end of the third jaw and the other end of the fourth jaw is measured to obtain the inner diameter size of the hole of part;The length of the third jaw and the fourth jaw can be adjusted.

2. A device for measuring the internal diameter of a pipe according to claim 1, characterized in that The length of the third jaw or the fourth jaw is less than the length of the first jaw or the second jaw.

3. A device for measuring the internal diameter of a pipe according to claim 1, characterized in that, The third jaw or the fourth jaw includes: Fixed rod, middle part is rotatably connected with the pin shaft, both ends are provided with first insertion hole extending to its interior; Two extension rods, one end is provided with second insertion hole extending to its interior, the protruding structure is located at the end of the extension rod away from the second insertion hole; Two telescopic rods, one end is respectively inserted into two first insertion holes, the other end is respectively inserted into two second insertion holes, both ends of the telescopic rod have the freedom of sliding insertion into the first insertion hole and the second insertion hole, the length of the third jaw or the fourth jaw is adjusted by adjusting the insertion depth of the telescopic rod.

4. A device for measuring the internal diameter of a pipe according to claim 3, characterized in that Locking hole is arranged at the position close to both ends of the fixed rod and the position close to the end of the two extension rods away from the protruding structure, a jackscrew is installed in the locking hole, and the jackscrew is screwed to abut and lock the telescopic rod.

5. A device for measuring the internal diameter of a pipe according to claim 3, characterized in that The telescopic rod includes a plurality of rod bodies that are detachably connected to each other, and the rod bodies at both ends of the telescopic rod are respectively used for sliding insertion into the first insertion hole and the second insertion hole.

6. A device for measuring the internal diameter of a pipe according to claim 1, characterized in that, The convex structure of the second forceps body and / or the fourth forceps body is hinged with a rotating block, one end of the rotating block is fixedly connected with one end of a measuring scale, the end of the measuring scale close to the convex structure is flush with the end of the convex structure, the convex structure of the first forceps body and / or the third forceps body is hinged with an indicating block, after the measuring scale and the indicating block abut, the indicating block is used for indicating the scale on the measuring scale.

7. A device for measuring the internal diameter of a pipe according to claim 6, characterized in that The end of the indicating block in contact with the measuring scale is pointed.

8. A device for measuring the internal diameter of a pipe according to claim 6, characterized in that The convex structure of the second forceps body and / or the fourth forceps body is connected with a lock, the lock is used for locking the position of the rotating block after rotation.

9. A device for measuring the internal diameter of a pipe according to claim 1, characterized in that, The middle width of the first forceps body and the second forceps body is greater than the width of both ends, and the end of the convex structure in contact with the part is arc-shaped.

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