A device for measuring the distance of small holes in the inner wall of a hole

Abstract

This invention relates to a small hole measuring device for inner bore walls. The small hole locator includes a plugging slider, a piston hole, a piston body, and a spring plunger. The plugging slider, used to match the inner bore, is connected to a longitudinal measuring scale. The piston body is disposed within the piston hole, with a threaded hole on its protruding side. The external thread on the spring plunger connects to the threaded hole. A floating positioning pin on the spring plunger matches the small hole. The plugging slider has a channel for the floating positioning pin to enter and exit, which communicates with the piston hole. The plugging slider also has an air passage. The retraction side of the piston body is the air chamber of the piston hole, which communicates with the air passage. An air inlet pipe is also provided outside the plugging slider, connected to the air passage. The piston body is also equipped with a return spring, which is mounted on the plugging slider. This cylinder-type small hole measuring device can accurately locate and position the small hole when inserted, ensuring accurate subsequent distance measurement and minimizing damage to the inner bore wall.

Description

Technical Field

[0001] This invention relates to a distance measuring device. Background Technology

[0002] Small holes are additionally machined on the side walls of the cylinder bores (usually circular inner holes) of various cylinders such as brake pumps and clutch pumps. These holes are often created by punching outwards from the inside using a punching die (e.g., oil inlet holes). Additionally, there are oil inlet holes on the outside of the cylinder. Due to process requirements, it is necessary to obtain the distance between the small holes and the ports of the cylinder bore (i.e., the inner hole). For example, CN113983939A describes a device and method for measuring the spacing between through holes on the inner wall of a brake pump cylinder bore, which can relatively well measure the relative position of small holes (such as through holes) on the inner wall. During measurement, although the approximate position and orientation of the small hole on the inner wall of the cylinder bore (i.e., the inner hole) are known, and a measuring tool can be inserted into the inner hole, it is still impossible to accurately locate the small hole, leading to measurement difficulties and inaccuracies. Accurate measurement of the position of these small holes on the inner wall of the cylinder bore is necessary to ensure the accurate relative positioning of other components when installed in the cylinder bore. Summary of the Invention

[0003] In view of the technical problems existing in the background art, the present invention aims to provide a different, alternative, inner hole ranging device capable of accurately locating a small hole. It can be used to accurately measure the distance between the small hole and the inner hole port.

[0004] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: a small hole measuring device for inner wall, comprising a longitudinal measuring scale, characterized in that: a small hole locator is provided on the longitudinal measuring scale, the small hole locator comprising a plugging slider, a piston hole, a piston body and a spring plunger, the plugging slider is connected to the longitudinal measuring scale, the plugging slider is used to match the inner hole, the piston hole is laterally arranged on the plugging slider, the piston body is disposed in the piston hole, the piston body is provided with a threaded hole, the threaded hole is located on the protruding side of the piston body, the external thread on the spring plunger is connected to the threaded hole, the floating positioning pin on the spring plunger matches the small hole, the plugging slider is provided with a channel for the floating positioning pin to enter and exit, the channel is laterally arranged, the channel is connected to the piston hole, the plugging slider is also provided with an air channel, the retraction side of the piston body is the air chamber of the piston hole, the air chamber is connected to the air channel, the plugging slider is also provided with an air inlet pipe, the air inlet pipe is connected to the air channel, the piston body is also equipped with a retraction spring, the retraction spring is installed on the plugging slider.

[0005] The following optimizations or supplementary explanations can be made to the above technical solutions.

[0006] A sealing ring is provided between the piston body and the piston hole, and an annular groove is provided on the outer ring of the piston body, with the sealing ring placed in the annular groove; a sliding caliper guide is also provided on the longitudinal measuring scale.

[0007] For example, the plug slider has a horizontally arranged stepped hole. One end of the stepped hole is a channel opening, and the other end of the stepped hole is equipped with a plug. The piston hole is between the plug and the channel opening. The air passage is set as a connecting hole on the side of the piston hole. The piston body has a narrowed part that protrudes towards the retraction side. The narrowed part is fitted with the plug by a limiting fit. The connection between the air passage and the piston hole is located on the retraction side of the piston body. The narrowed part is set as a narrowed cylindrical structure.

[0008] In addition, the air inlet pipe is built into the longitudinal measuring scale, the small hole locator is located at one end of the longitudinal measuring scale, and the other end of the longitudinal measuring scale is provided with an air inlet for connecting an external air source device. The air inlet is connected to the air inlet pipe.

[0009] For example, the return spring is a compression spring, which is sleeved outside the spring plunger, and the return spring is connected to the extended side of the piston body, and the return spring is located in the piston bore.

[0010] In addition, the circumferential sidewall of the plug slider matches the circular inner hole; the piston hole is a radial hole, and the longitudinal measuring scale is an axial scale.

[0011] In addition, the plugging slider also includes a detachable diameter-changing opening sleeve, which allows the plugging slider to match inner holes of different diameter specifications.

[0012] For example, the plugging hole slider has a main body, and the main body is also provided with a changing sleeve groove. The changing sleeve groove is located on both sides of the main body. The changing diameter opening sleeve is provided with a changing sleeve slider part. The changing sleeve slider part matches the changing sleeve groove. The changing sleeve groove is arranged longitudinally. The changing sleeve slider part is located in the inner ring of the changing diameter opening sleeve. The changing diameter opening sleeve has an opening area for avoiding the passage. The changing sleeve slider part is located on the left and right sides of the opening area.

[0013] Specifically, the outer ring of the diameter-changing open sleeve is combined with the longitudinal region where the channel opening of the main body of the plugging slider is located to match the inner hole size to be measured, or the outer ring of the diameter-changing open sleeve has a semi-circular mating outer wall to match the inner hole size to be measured.

[0014] In addition, a connecting fastener is provided between the diameter changing sleeve and the plugging slider body; or, the plugging slider body is provided with a ball screw, and the inner ring of the diameter changing sleeve is provided with a recessed hole that mates with the ball screw.

[0015] The beneficial effects of the present invention are that the small hole measuring device for the inner hole wall can find and insert into the small hole, accurately locate the position of the small hole, ensure the accuracy of subsequent measurement and distance measurement, and is not easy to damage or scratch the inner hole wall. Attached Figure Description

[0016] The following description, in conjunction with the accompanying drawings, details the embodiments and working principles of the present invention.

[0017] Figure 1 This is a schematic diagram of the structure of the small hole located on the inner bore of the cylinder body according to the present invention.

[0018] Figure 2 This is a schematic diagram of a structure according to an embodiment of the present invention.

[0019] Figure 3 for Figure 2 A schematic diagram of the structure of a small-to-medium hole positioner.

[0020] Figure 4 This is a cross-sectional view of another embodiment of the present invention.

[0021] Figure 5 In this invention and Figure 4 A cross-sectional view of the diameter-changing opening sleeve with matching structure.

[0022] Figure 6 for Figure 4 and Figure 5 A schematic diagram of the structural combination is shown below. Figure 7 Sectional view of AA.

[0023] Figure 7 This is a schematic diagram of a small hole measuring device for an inner hole wall with an added diameter-changing opening sleeve.

[0024] Figure 8 This is a schematic diagram illustrating the state used in this invention.

[0025] In the picture:

[0026] 1. Longitudinal measuring tape; 11. Sliding caliper guide; 12. Air inlet;

[0027] 2. Small hole locator;

[0028] 3. Plug hole slider; 30. Main body; 31. Channel opening; 32. Air passage; 33. Stepped hole; 34. Plug; 35. Diameter change open sleeve; 36. Change sleeve groove; 37. Change sleeve slider part; 38. Opening area; 39. Ball screw; 351. Concave hole;

[0029] 4. Piston bore; 41. Gas chamber;

[0030] 5. Piston body; 51. Threaded hole; 52. Sealing ring; 53. Annular groove; 54. Narrowing section;

[0031] 6. Spring plunger; 61. External thread; 62. Floating locating pin; 63. Small spring;

[0032] 7. Return spring;

[0033] 8. Inner hole; 80. Small hole. Detailed Implementation

[0034] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the implementation of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0035] Referring to the accompanying drawings, an inner wall small hole measuring device in this embodiment includes a longitudinal measuring scale 1, which can be a depth gauge structure. A small hole locator 2 is provided on the longitudinal measuring scale 1. The small hole locator 2 extends into the inner hole 8 (i.e., cylinder bore) of the cylinder to be measured (such as a brake pump, clutch pump, etc.) along with the longitudinal measuring scale 1 to cooperate with the positioning small hole 80 for accurate measurement.

[0036] The small hole positioner 2 includes a plugging slider 3, a piston hole 4, a piston body 5, and a spring plunger 6.

[0037] The plugging slider 3 is connected to the longitudinal measuring scale 1. The plugging slider 3 is used to match the inner hole 8. When the plugging slider 3 is inserted into the inner hole 8 of the cylinder, the plugging slider 3 matches the inner hole 8, and the relative position is more stable, avoiding shaking that affects the measurement. Usually, the shape and size of the plugging slider 3 match the inner hole 8. The plugging slider 3 slides stably in the inner hole 8. During the process of inserting (placing) the longitudinal measuring scale 1 into the inner hole 8, the plugging slider 3 helps to stabilize the position and cooperate to make accurate measurements.

[0038] The longitudinal measuring scale 1 measures the length in the longitudinal direction. The piston hole 4 is set laterally on the plugging slider 3. The piston hole 4 and the longitudinal measuring scale 1 form a relatively orthogonal relationship. After the longitudinal measuring scale 1 and the plugging slider 3 (inserted) are inserted into the inner hole 8, the lateral direction of the piston hole 4 on the plugging slider 3 is consistent with the radial direction of the inner hole 8, and the measuring length direction of the longitudinal measuring scale 1 is consistent with the axial direction of the inner hole 8.

[0039] The piston body 5 is disposed in the piston bore 4, and the piston body 5 can perform piston action within the piston bore 4, namely, lateral (i.e. radial) extension and return action.

[0040] A threaded hole 51 is provided on the piston body 5. The threaded hole 51 is located on the protruding side of the piston body 5, and the threaded hole 51 is provided on the end face of the protruding side of the piston body 5.

[0041] The spring plunger 6 is a mature technology. The spring plunger 6 (body) has an external thread 61. The spring plunger 6 has a compression spring (small spring 63) inside to provide elastic force to push the plunger core (i.e. floating positioning pin 62) of the spring plunger 6 out to the initial state, so that the floating positioning pin 62 can extend and float on the spring plunger 6 (body). In this invention, the plunger shaft is used as the positioning hole 80 of the floating positioning pin 62 for measurement. The floating positioning pin 62 on the spring plunger 6 matches the hole 80, and the head of the floating positioning pin 62 is located at the outer end of the spring plunger 6.

[0042] The external thread 61 on the spring plunger 6 is connected to the threaded hole 51 (of the piston body 5). The threaded connection facilitates the assembly of the spring plunger 6 onto the piston body 5 and the adjustment of the relative position of the spring plunger 6 on the piston body 5. The extension distance of the end (outer end) of the spring plunger 6 relative to the piston body 5 can be adjusted to adjust the initial relative position of the floating positioning pin 62 on the spring plunger 6. Through adjustment, it is ensured that it can operate smoothly and cooperate with the positioning hole 80 for measurement, and also avoids the spring plunger 6 from scratching the inner wall of the inner hole 8 (i.e., the inner wall).

[0043] The plug slider 3 is provided with a channel 31 for the floating positioning pin 62 to enter and exit. The channel 31 is arranged horizontally. The horizontally arranged channel 31 is connected to the horizontally arranged piston hole 4. They are arranged in the same direction (both are horizontal) and are connected. When the spring plunger 6 moves back and forth in the piston hole 4 with the piston body 5, the floating positioning pin 62 of the spring plunger 6 can extend and retract from the channel 31.

[0044] The plugging slider 3 is also equipped with an air passage 32. The retraction side of the piston body 5 is the air chamber 41 of the piston hole 4, which is connected to the air passage 32. The plugging slider 3 is also equipped with an air inlet pipe (not shown in the figure), which is connected to the air passage 32 to form an air passage structure, so that the air source can be connected to the air chamber 41 through the air inlet pipe and the air passage 32 to realize the gas input and gas discharge. In addition, the piston body 5 is also equipped with a return spring 7, which is installed on the plugging slider 3. When gas is input into the air chamber 41, the air pressure increases and overcomes the elastic force of the return spring 7, thus driving the piston body 5 to extend. When gas is discharged from the air chamber 41, the elastic force of the return spring 7 drives the piston body 5 to return to its original position. When gas is supplied or discharged into the air chamber 41, combined with the return spring 7, the piston body 5 is driven to move within the piston hole 4, thus controlling the extension and return movements of the piston body 5 within the piston hole 4.

[0045] When measuring the distance to the position of the small hole 80 on the inner wall of the cylinder bore 8 (i.e., cylinder bore) of a cylinder block (brake pump, clutch pump, etc.), insert the longitudinal measuring gauge 1 with the small hole locator 2 into the inner bore 8. The plug slider 3 of the small hole locator 2 slides and inserts into the inner bore 8, and the longitudinal measuring gauge 1 can be stably inserted. The air inlet pipe is used to connect to an external air source device (such as a vacuum pump, etc.). Positive pressure gas is input into the air chamber 41 of the piston bore 4 to help extend and move the piston body 5 (laterally). The spring plunger 6 on the piston body 5 will also extend and move (laterally) together. The floating positioning pin 62 of the spring plunger 6 will push against the side wall of the inner bore 8. The floating positioning pin 62 of the spring plunger 6 (with the help of the small spring 63 to provide elastic force) (Used below) The floating positioning pin 62, with its spring-loaded floating function, will not scratch the side wall of the inner hole 8 when the piston body 5 is extended, will contact and abut against the side wall of the inner hole 8. Knowing the approximate position and orientation of the small hole 80 on the inner wall of the cylinder bore (i.e., the inner hole 8), by inserting the small hole locator 2 to the approximate position and orientation of the small hole 80, and operating the longitudinal measuring scale 1 to move back and forth and rotate longitudinally, the floating positioning pin 62 can automatically insert into the small hole 80, thereby achieving accurate positioning of the small hole 80 for distance measurement, such as measuring the distance between the small hole 80 and the port of the inner hole 8. Accurate positioning of the small hole 80 ensures accurate subsequent distance measurement. After the measurement is completed, the gas in the air chamber 41 is discharged, and the elastic force of the return spring 7 drives the piston body 5 to return to its original position. The floating positioning pin 62 on the spring plunger 6 returns to its original position along with the piston body 5, retracting back into the channel opening 31. Among them, the small hole 80 usually has a flared opening at the upper edge of the inner hole 8 wall to facilitate the smooth insertion of the floating positioning pin 62.

[0046] The small hole ranging device in the inner wall of the cylinder can accurately locate the small hole 80 position by inserting it into the small hole, ensuring accurate subsequent measurement and ranging, and is less likely to damage or scratch the inner wall of the hole.

[0047] Based on the above embodiments, the following optimizations or further explanations can be made.

[0048] For example, a sealing ring 52 is provided between the piston body 5 and the piston bore 4 to prevent gas in the gas chamber 41 from leaking to the protruding side of the piston body 5 (i.e., the mounting side of the spring plunger 6). For instance, an annular groove 53 is provided on the outer ring of the piston body 5, and the sealing ring 52 is placed in the annular groove 53, which facilitates the assembly of the sealing ring 52 and makes the sealing ring 52 relatively stable during operation.

[0049] The plug slider 3 has a stepped hole 33, which is horizontally positioned (i.e., its axis is horizontal). One end of the stepped hole 33 is a channel opening 31, and the other end is fitted with a plug 34 to seal the opening. Between the plug 34 and the channel opening 31 is a piston hole 4 for machining and assembly. This structure can be directly machined by drilling to form the piston hole 4. The air passage 32 is set as a connecting hole on the side of the piston hole 4, which can also be easily machined and connected by drilling. Furthermore, the piston body 5 has a narrowed portion 54 protruding towards the retraction side. The narrowed portion 54 is fitted with the plug 34 by a limiting mechanism. Under the action of the return spring 7, the piston body 5 returns to its original position, and the plug 34 holds the piston body 5 in place. The connection between the air passage 32 and the piston hole 4 is located on the retraction side of the piston body 5, resulting in a relatively compact structure. This allows the air passage 32 to smoothly supply gas into the piston hole 4 when the piston body 5 is in its original position (pressed onto the plug 34 by the return spring 7), preventing the air passage 32 from being blocked by the piston body 5 and affecting operation. For example, the narrowed portion 54 can be designed as a narrowed cylindrical structure for easier processing. An annular space is formed on the outer ring of the narrowed portion 54 to ensure uniform gas distribution and smoother piston body 5 operation.

[0050] Further optimization involves embedding the air inlet pipe within the longitudinal measuring scale 1. The small hole locator 2 is located at one end of the longitudinal measuring scale 1, while the other end of the longitudinal measuring scale 1 is equipped with an air inlet 12 for connecting to an external air source device. The air inlet 12 is connected to the air inlet pipe, resulting in a relatively compact structure that facilitates insertion into and removal from the cylinder body's inner hole 8, as well as easy connection and operation of the air source circuit. A valve or similar structure can also be installed between the external air source device and the air inlet 12 to control the input and output of gas into the air chamber 41.

[0051] The longitudinal measuring scale 1 is also equipped with a sliding caliper guide 11, which is a conventional technology, such as a depth gauge. The sliding caliper guide 11 is used to measure the depth by being placed against the port of the inner hole 8 of the cylinder.

[0052] For example, the return spring 7 is a compression spring, which is sleeved on the outside of the spring plunger 6. The return spring 7 is connected to the extended side of the piston body 5 and is located in the piston hole 4. The structure is reasonable and the operation is stable.

[0053] The inner bore 8 of the cylinder is typically circular, and the circumferential sidewall of the plug slider 3 matches the circular inner bore 8, ensuring stability when the plug slider 3 is inserted into the inner bore 8. The piston bore 4 is a radial bore, and the longitudinal measuring scale 1 is an axial scale.

[0054] The plugging slider 3 also includes a detachable diameter-changing sleeve 35. The diameter-changing sleeve 35 can be disassembled and installed, and the outer diameter of the plugging slider 3 can be changed after the diameter-changing sleeve 35 is installed, so that the plugging slider 3 can also match other inner holes 8 of different diameter specifications. Usually, the inner holes 8 of cylinders produced by manufacturers (such as brake pumps, clutch pumps, etc.) have several diameter specifications. By replacing and assembling different diameter-changing sleeves 35, the plugging slider 3 as a whole can match different cylinder inner holes 8. This inner hole wall small hole distance measuring device can be used for distance measurement of small holes 80 on the inner hole wall of cylinders of various specifications, which is more practical and has low operating cost.

[0055] The plugging slider 3 has a main body 30, and the main body 30 is also provided with a replacement sleeve groove 36, which is distributed on both sides of the main body 30.

[0056] The diameter-changing open sleeve 35 is provided with a diameter-changing slider part 37, which matches the diameter-changing groove 36. The corresponding diameter-changing slider part 37 will also be located on the left and right sides of the diameter-changing open sleeve 35. The diameter-changing groove 36 is arranged longitudinally, and the diameter-changing slider part 37 can be set as a longitudinal slide bar, which makes the sliding more stable and the structure more stable after assembly. During disassembly and assembly, the diameter-changing slider part 37 slides into the assembly and slides out of the groove 36 for disassembly and assembly, which is convenient. The diameter-changing open sleeve 35 can be axially slid on the main body 30 (of the plugging hole slider 3) to form a plugging hole slider 3 that is adapted to different cylinder inner bores 8. In addition, the diameter-changing slider part 37 is located on the inner ring of the diameter-changing open sleeve 35. The diameter-changing open sleeve 35 has an opening area 38 that avoids the passage 31. The diameter-changing open sleeve 35 does not affect the passage 31 (and the floating positioning pin 62 enters and exits from the passage 31) during disassembly and assembly. The diameter-changing slider part 37 is located on the left and right sides of the opening area 38, and the structure is relatively stable after assembly.

[0057] For example, the outer ring of the diameter-changing open sleeve 35 and the longitudinal region where the channel opening 31 of the main body 30 of the plugging slider 3 is located are combined to match the size of the inner hole 8 to be measured, which can stably match the inner hole 8 of the cylinder. Alternatively, for example, the outer ring of the diameter-changing open sleeve 35 has a semi-circular mating outer wall, which is used to adapt to the size of the inner hole 8 to be measured, which can also stably match the inner hole 8 of the cylinder.

[0058] Furthermore, to ensure a stable assembly between the diameter-changing sleeve 35 and the plugging slider 3 body 30, and to facilitate disassembly and assembly, a connecting fastener (such as a fastening screw) is provided between the diameter-changing sleeve 35 and the plugging slider 3 body 30; alternatively, the plugging slider 3 body 30 is provided with a ball screw 39 (such as an internal hexagonal screw with a spring ball, spring set screw, etc.), and the inner ring of the diameter-changing sleeve 35 is provided with a recessed hole 351 that mates with the ball screw 39, facilitating the disassembly and assembly of the diameter-changing sleeve 35.

Claims

1. A device for measuring the distance of a small hole in the inner wall of a borehole, comprising a longitudinal measuring scale (1), characterized in that: A small hole locator (2) is provided on the longitudinal measuring scale (1). The small hole positioner (2) includes a plugging slider (3), a piston hole (4), a piston body (5), and a spring plunger (6). The plugging slider (3) is connected to the longitudinal measuring scale (1), and the plugging slider (3) is used to match the inner hole (8). The piston hole (4) is horizontally positioned on the plug hole slider (3). The piston body (5) is disposed within the piston bore (4). A threaded hole (51) is provided on the piston body (5), and the threaded hole (51) is located on the protruding side of the piston body (5). The external thread (61) on the spring plunger (6) is connected to the threaded hole (51). The floating positioning pin (62) on the spring plunger (6) matches the small hole (80). The plugging slider (3) is provided with a channel (31) for the floating positioning pin (62) to enter and exit. The channel (31) is arranged horizontally and is connected to the piston hole (4). The plug slider (3) is also provided with an air passage (32), and the retraction side of the piston body (5) is the air chamber (41) of the piston hole (4), which is connected to the air passage (32). The plugging slider (3) is also equipped with an air inlet pipe, which is connected to the air passage (32). The piston body (5) is also equipped with a return spring (7), which is mounted on the plug hole slider (3); The plugging slider (3) also includes a detachable diameter-changing opening sleeve (35), which allows the plugging slider (3) to match inner holes (8) of different diameter specifications. The plugging slider (3) has a main body (30), and the main body (30) is also provided with a sleeve changing groove (36). The sleeve changing groove (36) is located on both sides of the main body (30). The diameter-changing open sleeve (35) is provided with a sleeve-changing slider (37), which matches the sleeve-changing groove (36). The sleeve-changing groove (36) is arranged longitudinally. The changing sleeve slider (37) is located on the inner ring of the changing diameter opening sleeve (35). The changing diameter opening sleeve (35) has an opening area for the clearance passage (31). The changing sleeve slider (37) is located on the left and right sides of the opening area respectively. The outer ring of the diameter-changing open sleeve (35) and the longitudinal region where the channel opening (31) of the main body (30) of the plugging slider (3) is located are combined to match the size of the inner hole (8) to be measured, or the outer ring of the diameter-changing open sleeve (35) has a semi-circular mating outer wall to match the size of the inner hole (8) to be measured. A connecting fastener is provided between the diameter changing sleeve (35) and the main body (30) of the plugging slider (3); or, a ball screw (39) is provided on the main body (30) of the plugging slider (3), and the inner ring of the diameter changing sleeve (35) is provided with a recessed hole (351) that is positioned and matched with the ball screw (39).

2. The internal hole ranging device as described in claim 1, characterized in that: A sealing ring (52) is provided between the piston body (5) and the piston hole (4), and an annular groove (53) is provided on the outer ring of the piston body (5), with the sealing ring (52) located in the annular groove (53); The longitudinal measuring scale (1) is also equipped with a sliding caliper guide (11).

3. The internal hole ranging device as described in claim 1, characterized in that: The plug slider (3) has a horizontally arranged stepped hole (33). One end of the stepped hole (33) is a channel opening (31), and the other end of the stepped hole (33) is provided with a plug (34). The piston hole (4) is between the plug (34) and the channel opening (31). The air passage (32) is configured as a connecting hole on the side of the piston hole (4); The piston body (5) has a narrowed portion (54) that protrudes towards the retraction side, and the narrowed portion (54) is in a limiting fit with the plug (34). The connection between the air passage (32) and the piston bore (4) is located on the retraction side of the piston body (5). The narrowing section (54) is designed as a narrowing cylindrical structure.

4. The internal hole ranging device as described in claim 1, characterized in that: The gas connection line is built into the longitudinal measuring scale (1). The small hole locator (2) is located at one end of the longitudinal measuring scale (1). The other end of the longitudinal measuring scale (1) is provided with an air inlet (12) for connecting an external air source device, and the air inlet (12) is connected to the air inlet pipeline.

5. The internal hole ranging device as described in claim 1, characterized in that: The return spring (7) is a compression spring, which is sleeved outside the spring plunger (6). The return spring (7) is connected to the extended side of the piston body (5) and is located in the piston hole (4).

6. The internal hole ranging device as described in claim 1, characterized in that: The circumferential sidewall of the plug slider (3) matches the circular inner hole; the piston hole (4) is a radial hole, and the longitudinal measuring scale (1) is an axial scale.

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