Device and method for measuring effective length of internal thread lifting hole

Abstract

The invention provides a device and a method for measuring the effective length of an internal thread lifting hole. The invention discloses a device for measuring the effective length of an internal thread lifting hole. The device comprises an internal thread sleeve, a left and right thread rotating shaft assembly, a guide shaft, a left L-shaped measuring plate and a right L-shaped measuring plate, an internal thread is arranged on the internal thread sleeve; the guide shaft is mounted on the internal thread sleeve and penetrates through the left L-shaped measuring plate and the right L-shaped measuring plate; the left L-shaped measuring plate and the right L-shaped measuring plate can move along the length direction of the guide shaft; the left and right threaded rotating shaft combination body is mounted on the inner threaded sleeve and is parallel to the guide shaft; the left and right threaded rotating shaft assembly passes through the left L-shaped measuring plate and the right L-shaped measuring plate, and the left L-shaped measuring plate and the right L-shaped measuring plate can move along the length direction of the guide shaft. According to the measuring device, the influence of the size of the tool withdrawal groove on measurement can be eliminated, errors are reduced, the measuring result is more accurate, and therefore the credibility of paper strength checking is improved.

Description

Technical Field

[0001] The present invention relates to a measuring device, in particular to a measuring device for the effective length of an internal threaded lifting hole of a gas generator for aircraft catapult, and in particular to a measuring device and method for the effective length of an internal threaded lifting hole. Background Art

[0002] At present, after the geometric dimensions of the gas generator for aircraft catapult are processed and formed in the industry, there is no effective measurement method for the length of the internal thread lifting hole because there is a back-cutting groove hole inside. Since reliable visual inspection is impossible, the only way to measure it is to use a tape measure or a thin rod of a vernier caliper to extend it. Because this method with large errors is used for measurement, the credibility of the theoretical strength verification of the internal thread is reduced, which poses a hidden danger to the subsequent strong vibration and high overload catapult tests. Summary of the invention

[0003] In view of the defects in the prior art, the object of the present invention is to provide a device and method for measuring the effective length of an internal thread lifting hole.

[0004] According to the present invention, a device for measuring the effective length of an internal threaded lifting hole comprises an internal threaded sleeve, a left and right threaded rotating shaft assembly, a guide shaft, a left L-shaped measuring plate and a right L-shaped measuring plate;

[0005] The internal thread sleeve is provided with an internal thread; the guide shaft is mounted on the internal thread sleeve, and the guide shaft passes through the left L-shaped measuring plate and the right L-shaped measuring plate; the left L-shaped measuring plate and the right L-shaped measuring plate can both move along the length direction of the guide shaft;

[0006] The left and right threaded rotating shaft assembly is installed on the internal threaded sleeve and is arranged parallel to the guide shaft; the left and right threaded rotating shaft assembly passes through the left L-shaped measuring plate and the right L-shaped measuring plate, and the left L-shaped measuring plate and the right L-shaped measuring plate can both move along the length direction of the guide shaft.

[0007] Preferably, the device for measuring the effective length of the internal thread lifting hole is used to measure the effective length of the internal thread lifting hole of the gas generator for aircraft catapult.

[0008] Preferably, the left and right threaded rotating shaft assembly comprises a left square plate, a right square plate, a left shaft shoulder, a right shaft shoulder, a left threaded rod, a right threaded rod and a positioning round table;

[0009] The left square plate, left shoulder, left threaded rod, positioning round table, right threaded rod, right threaded rod, right shoulder and right square plate are detachably connected in sequence;

[0010] The left plate and the right plate are completely identical in shape and size and are symmetrically distributed along the center line, and the left shoulder and the right shoulder are completely identical in shape and size and are symmetrically distributed along the center line;

[0011] The right threaded rod and the left threaded rod are respectively threadedly connected with the right L-shaped measuring plate and the left L-shaped measuring plate; when the left threaded rod rotates, the left L-shaped measuring plate can move along the length direction of the left threaded rod; when the right threaded rod rotates, the right L-shaped measuring plate can move along the length direction of the right threaded rod;

[0012] The internally threaded sleeve is provided with a first positioning hole and a second positioning hole; the left shoulder is located at the first positioning hole, and the left square disk is located outside the internally threaded sleeve; the right shoulder is located at the second positioning hole, and the right square disk is located outside the internally threaded sleeve.

[0013] Preferably, the left L-shaped measuring plate comprises a first guide hole, a first right-hand threaded hole, a first long arc surface and a first short arc surface;

[0014] The diameter of the first guide hole of the left L-shaped measuring plate matches the diameter of the guide shaft;

[0015] The first right-hand threaded hole of the left L-shaped measuring plate matches the right-hand thread on the left threaded rod of the left and right threaded rotating shaft assembly.

[0016] Preferably, the right L-shaped measuring plate comprises a second guide hole, a second left-hand threaded hole, a second long arc surface and a second short arc surface;

[0017] The diameter of the second guide hole of the right L-shaped measuring plate matches the diameter of the guide shaft;

[0018] The second left-hand threaded hole of the right L-shaped measuring plate matches the left-hand thread on the right threaded rod of the left-right threaded rotating shaft assembly.

[0019] Preferably, it also includes two positioning rings, which are respectively mounted on the left shoulder and the right shoulder.

[0020] Preferably, it also includes a connecting piece, and the positioning ring is connected to the left and right threaded rotating shaft combination body through the connecting piece.

[0021] Preferably, the distance that the top surface of the first short arc surface extends from the top surface of the first long arc surface is twice the measured pitch of the threaded hole.

[0022] Preferably, the thickness of the first short arc surface and the second short arc surface is 1 mm smaller than the minimum length of the measured internal thread backing groove specified in GB / T3-1997.

[0023] According to a method for measuring the effective length of an internal thread lifting hole provided by the present invention, the effective length measuring device of the internal thread lifting hole is used, and the method comprises the following steps:

[0024] S1. Install the measuring device for the effective length of the internal thread lifting hole into the internal thread lifting hole of the gas generator, and rotate the internal thread sleeve to make the two screwed together;

[0025] S2, rotating the left plate and the right plate, so that the top surface of the first short arc of the left L-shaped measuring plate and the top surface of the second short arc of the right L-shaped measuring plate are respectively fitted with the inner wall of the internal thread lifting hole;

[0026] S3, continue to rotate the internal thread sleeve until the left and right disks are rotated so that the first short arc surface of the left L-shaped measuring plate and the short arc surface of the right L-shaped measuring plate enter the cutter groove of the internal thread lifting hole of the gas generator and contact the inner wall surface, then reversely rotate the internal thread sleeve until it contacts the internal thread end surface of the lifting hole, and stop reverse rotation;

[0027] S4. Use a vernier caliper to accurately measure the distance L3 from the upper end surface of the internal thread sleeve to the upper end surface of the internal thread lifting hole of the gas generator, and obtain the effective length L1 of the internal thread lifting hole of the gas generator = L2-L3;

[0028] Wherein L2 is the distance from the upper end surface of the internal threaded sleeve to the measuring reference surface of the left L-shaped measuring plate.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] 1. The measuring device of the present invention can eliminate the influence of the undercut groove size on the measurement, reduce the error, make the measurement result more accurate, and thus improve the credibility of the paper strength verification.

[0031] 2. The left and right threaded rotating shaft assembly of the present invention is provided with a left square plate and a right square plate, so that the operator only needs to use a wrench to hold the square plate and rotate it to operate the left threaded rod and the right threaded rod to rotate, thereby driving the left L-shaped measuring plate and the right L-shaped measuring plate to move, without the need for special tools, and the operation is simple and easy to use. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0033] Figure 1 It is a schematic diagram of the structure of an internal threaded sleeve;

[0034] Figure 2 It is a schematic diagram of the structure of the left and right threaded rotating shaft assembly;

[0035] Figure 3 It is a schematic diagram of the structure of the left L-shaped measuring plate;

[0036] Figure 4 It is a schematic diagram of the top view of the left L-shaped measuring plate;

[0037] Figure 5 It is a schematic diagram of the structure of the right L-shaped measuring plate;

[0038] Figure 6 It is a schematic diagram of the top view of the right L-shaped measuring plate;

[0039] Figure 7 It is a schematic diagram of the structure of the present invention;

[0040] Figure 8 The present invention is installed on the gas generator for aircraft catapult.

[0041] Fig. 9 The present invention is a structural diagram of the operation process of a gas generator for aircraft catapult;

[0042] Fig.10 This is a structural diagram of the present invention in operation on a gas generator for aircraft catapult;

[0043] Fig.11 This is a structural diagram of the gas generator used for aircraft catapult.

[0044] The figure shows:

[0045] DETAILED DESCRIPTION

[0046] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several changes and improvements can also be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0047] The invention provides a device for measuring the effective length of an internal thread lifting hole, which solves the problem of accurately measuring the effective length of the internal thread lifting hole of a gas generator for aircraft catapult.

[0048] The present invention provides a device for measuring the effective length of an internal thread lifting hole, such as Figure 1-Figure 7 As shown, it includes an internal thread sleeve 20, a left and right threaded rotating shaft assembly 30, a guide shaft 40, a left L-shaped measuring plate 60 and a right L-shaped measuring plate 50;

[0049] The internal thread sleeve 20 is provided with an internal thread 21;

[0050] The guide shaft 40 is installed on the internal threaded sleeve 20, and the guide shaft 40 passes through the left L-shaped measuring plate 60 and the right L-shaped measuring plate 50; the left L-shaped measuring plate 60 and the right L-shaped measuring plate 50 can move freely along the length direction of the guide shaft 40; specifically, the threaded sleeve 20 is provided with a guide hole 23, the diameter of the guide hole 23 matches the diameter of the guide shaft 40, and can position the guide shaft 40;

[0051] The left and right threaded rotating shaft assembly 30 is installed on the internal threaded sleeve 20 and arranged in parallel with the guide shaft 40; the left and right threaded rotating shaft assembly 30 passes through the left L-shaped measuring plate 60 and the right L-shaped measuring plate 50, and the left L-shaped measuring plate 60 and the right L-shaped measuring plate 50 can move along the length direction of the guide shaft 40;

[0052] The measuring device for the effective length of the internal thread lifting hole is used to measure the effective length of the internal thread lifting hole of the aircraft catapult gas generator. Specifically, the internal thread 21 on the internal thread sleeve 20 matches the diameter, length and accuracy of the external thread 12 of the aircraft catapult gas generator 10. Fig.11 This is a structural diagram of a gas generator for aircraft catapult use, with emphasis on the internal threaded lifting hole of the gas generator for aircraft catapult use.

[0053] The left and right threaded rotating shaft assembly 30 includes a left disk 37, a right disk 31, a left shoulder 36, a right shoulder 32, a left threaded rod 35, a right threaded rod 33 and a positioning round table 34; the left disk 37, the left shoulder 36, the left threaded rod 35, the positioning round table 34, the right threaded rod 33, the right threaded rod 33, the right shoulder 32 and the right disk 31 are detachably connected in sequence; the left disk 37 and the right disk 31 are completely identical in shape and size and are symmetrically distributed along the center line 38, the left shoulder 36 and the right shoulder 32 are completely identical in shape and size and are symmetrically distributed along the center line 38; the right threaded rod 3 ... The rod 35 is threadedly connected to the right L-shaped measuring plate 50 and the left L-shaped measuring plate 60 respectively; when the left threaded rod 35 rotates, the left L-shaped measuring plate 60 can move along the length direction of the left threaded rod 35; when the right threaded rod 33 rotates, the right L-shaped measuring plate 50 can move along the length direction of the right threaded rod 33; specifically, the right threaded rod 33 is provided with left-handed threads, and the left threaded rod 35 is provided with right-handed threads, and the spiral diameters, pitches and lengths of the two threaded rods are equal and completely the same, only the rotation directions are different and they are symmetrically distributed along the center line 38, and the positioning truncated cones 34 are symmetrically distributed along the center line 38;

[0054] The internal threaded sleeve 20 is provided with a first positioning hole 221 and a second positioning hole 222; the left shoulder 36 is located at the first positioning hole 221, and the left disk 37 is located outside the internal threaded sleeve 20; the right shoulder 32 is located at the second positioning hole 222, and the right disk 31 is located outside the internal threaded sleeve 20. Specifically, the diameter of the first positioning hole 221 on the threaded sleeve 20 matches the diameter of the left shoulder 36 on the left and right threaded rotating shaft assembly 30; the diameter of the second positioning hole 222 matches the diameter of the right shoulder 32, and the left and right threaded rotating shaft assembly 30 can flexibly rotate along its own axis;

[0055] The left L-shaped measuring plate 60 includes a first guide hole 62, a first right-handed threaded hole 61, a first long arc surface 63 and a first short arc surface 64; the diameter of the first guide hole 62 of the left L-shaped measuring plate 60 matches the diameter of the guide shaft 40; the first right-handed threaded hole 61 of the left L-shaped measuring plate 60 matches the right-handed thread on the left threaded rod 35 of the left and right threaded rotating shaft assembly 30;

[0056] The right L-shaped measuring plate comprises a second guide hole 52, a second left-handed threaded hole 51, a second long arc surface 53 and a second short arc surface 54; the diameter of the second guide hole 52 of the right L-shaped measuring plate 50 matches the diameter of the guide shaft 40; the second left-handed threaded hole 51 of the right L-shaped measuring plate 50 matches the left-handed thread on the right threaded rod 33 of the left-right threaded rotating shaft assembly 30; the right L-shaped measuring plate is identical to the left L-shaped measuring plate 60 except that the left-handed threaded hole 51 of the right L-shaped measuring plate has a different rotation direction from the right-handed threaded hole 61 on the left L-shaped measuring plate;

[0057] The distance between the guide hole 23 and the positioning hole on the internal threaded sleeve 20, the distance between the guide hole 62 and the right-handed threaded hole 61 of the left L-shaped measuring plate 60, and the distance between the guide hole 52 and the left-handed threaded hole 51 of the right L-shaped measuring plate 50 are completely equal; the distance that the top surface of the first short circular arc surface 64 protrudes from the top surface of the first long circular arc surface 63 is twice the pitch of the measured threaded hole. The thickness of the first short circular arc surface 64 and the second short circular arc surface 54 is 1mm less than the minimum length of the measured internal thread undercut groove specified in GB / T3-1997.

[0058] The measuring device for the effective length of the internal thread lifting hole also includes a positioning ring 3, and the number of the positioning rings 3 is 2, which are respectively mounted on the left shoulder 36 and the right shoulder 32. Specifically, the inner hole diameter of the positioning ring 3 matches the diameter of the left shoulder 36 and the right shoulder 32 of the left and right threaded rotating shaft assembly 30. And it can slide freely. The measuring device for the effective length of the internal thread lifting hole also includes a connecting piece, and the positioning ring 3 is connected to the left and right threaded rotating shaft assembly 30 through the connecting piece. In a preferred example, the connecting piece is a pin.

[0059] refer to Figure 1-Figure 7 Before assembling the left and right threaded shaft assembly 30, the left shoulder 36 and the right shoulder 32 are respectively installed into the positioning holes on the internal threaded sleeve 20, and then the left L-shaped measuring plate 60 is screwed into the right-handed thread on the left threaded rod 35 of the left and right threaded shaft assembly 30 through the right-handed threaded hole 61, and the right L-shaped measuring plate 50 is screwed into the left-handed thread on the right threaded rod 33 of the left and right threaded shaft assembly 30 through the left-handed threaded hole 51, and then the left and right threaded shaft assembly 30 is assembled into one body, and fits with the left and right end surfaces of the positioning truncated table 34, and after ensuring that the left and right threaded shaft assembly 30 is centered along the center line 4, the positioning ring 3 is inserted into the left shoulder 36 and the right shoulder 32 of the left and right threaded shaft assembly 30, and fits with the outer cylindrical surface of the internal threaded sleeve 20. Then, the pin hole is configured by the first taper pin 1, so that the left and right threaded shaft assembly 30 and the positioning ring 3 are integrated. The guide shaft 40 freely passes through the guide hole 23 on the internal threaded sleeve, the guide hole 62 of the left L-shaped measuring plate, and the guide hole 52 of the right L-shaped measuring plate, and after being centered along the center line 4, the second cone pin 2 is used to configure the pin hole so that the guide shaft 40 and the internal threaded sleeve 20 are integrated, and the distance L2 from the upper end surface of the internal threaded sleeve 20 to the first measuring reference surface 65 of the left L-shaped measuring plate 60 (also the second measuring reference surface 55 of the right L-shaped measuring plate 50) is accurately measured with a vernier caliper; the first measuring reference surface 65 is Figure 5 The upper end surface of the first short arc surface 64 is shown in the figure; the second measurement reference surface 55 is Figure 3 The upper end surface of the second short arc surface 54 is shown in the figure.

[0060] The present invention also provides a method for measuring the effective length of an internal thread lifting hole, comprising the following steps:

[0061] S1, such as Figure 8 As shown, the measuring device for the effective length of the internal thread lifting hole is installed into the internal thread lifting hole 13 of the gas generator 10, and the internal thread sleeve 20 is rotated for about one circle to make the two screwed into one;

[0062] S2, such as Fig. 9 As shown, the left disk 37 and the right disk 31 are rotated with a wrench so that the top surface of the first short arc 64 of the left L-shaped measuring plate 60 and the top surface of the second short arc 54 of the right L-shaped measuring plate 50 are respectively fitted with the inner wall of the internal thread lifting hole 13; in a preferred example, when one of the left disk 37 or the right disk 31 is rotated, the left and right threaded rotating shaft assemblies 30 will rotate as a whole, that is, when one of the left disk 37 or the right disk 31 is rotated, the left L-shaped measuring plate 60 and the right L-shaped measuring plate 50 will move due to the action of the thread.

[0063] S3, such as Fig.10As shown, the internal thread sleeve 20 is continuously rotated until the square plate 37 and the right square plate 31 are slightly rotated, so that the first short arc surface 64 of the left L-shaped measuring plate 60 and the second short arc surface 54 of the right L-shaped measuring plate 50 enter the undercut groove 11 of the internal thread lifting hole 13 of the gas generator and contact the inner wall surface, and then the internal thread sleeve 20 is reversely rotated until it contacts the internal thread end surface of the lifting hole 13, and the reverse rotation is stopped;

[0064] 4 Use a vernier caliper to accurately measure the distance L3 from the upper end surface of the internal thread sleeve 20 to the upper end surface of the internal thread lifting hole 13 of the gas generator 10. Knowing the size of L2, the effective length L1 of the internal thread lifting hole 13 of the gas generator 10 is obtained to be L2-L3;

[0065] Wherein L2 is the distance from the upper end surface of the internal threaded sleeve 20 to the first measurement reference surface 65 of the left L-shaped measuring plate 60, and is also the distance from the upper end surface of the internal threaded sleeve 20 to the second measurement reference surface 55 of the right L-shaped measuring plate 50; the first measurement reference surface 65 is Figure 5 The upper end surface of the first short arc surface 64 is shown in the figure; the second measurement reference surface 55 is Figure 3 The upper end surface of the second short arc surface 54 is shown in the figure.

[0066] In the description of the present application, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0067] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essence of the present invention. In the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

1. A device for measuring the effective length of an internal threaded lifting hole, characterized in that: It comprises an internal thread sleeve (20), a left and right threaded rotating shaft assembly (30), a guide shaft (40), a left L-shaped measuring plate (60) and a right L-shaped measuring plate (50); The internal thread sleeve (20) is provided with an internal thread (21); the guide shaft (40) is mounted on the internal thread sleeve (20), and the guide shaft (40) passes through the left L-shaped measuring plate (60) and the right L-shaped measuring plate (50); the left L-shaped measuring plate (60) and the right L-shaped measuring plate (50) can both move along the length direction of the guide shaft (40); The left and right threaded rotating shaft assembly (30) is mounted on the internal threaded sleeve (20) and arranged in parallel with the guide shaft (40); the left and right threaded rotating shaft assembly (30) passes through the left L-shaped measuring plate (60) and the right L-shaped measuring plate (50), and both the left L-shaped measuring plate (60) and the right L-shaped measuring plate (50) can move along the length direction of the guide shaft (40).

2. The measuring device for the effective length of the internal thread lifting hole according to claim 1, characterized in that: The measuring device of the effective length of the internal thread lifting hole is used for measuring the effective length of the internal thread lifting hole of the gas generator for aircraft catapult.

3. The measuring device for the effective length of the internal thread lifting hole according to claim 1, characterized in that: The left and right threaded rotating shaft assembly (30) comprises a left square plate (37), a right square plate (31), a left shaft shoulder (36), a right shaft shoulder (32), a left threaded rod (35), a right threaded rod (33) and a positioning round table (34); The left square plate (37), the left shoulder (36), the left threaded rod (35), the positioning round table (34), the right threaded rod (33), the right threaded rod (33), the right shoulder (32), and the right square plate (31) are sequentially detachably connected; The left plate (37) and the right plate (31) are completely identical in shape and size and are symmetrically distributed about the center line (38); the left shoulder (36) and the right shoulder (32) are completely identical in shape and size and are symmetrically distributed about the center line (38); The right threaded rod (33) and the left threaded rod (35) are respectively threadedly connected to the right L-shaped measuring plate (50) and the left L-shaped measuring plate (60); when the left threaded rod (35) rotates, the left L-shaped measuring plate (60) can move along the length direction of the left threaded rod (35); when the right threaded rod (33) rotates, the right L-shaped measuring plate (50) can move along the length direction of the right threaded rod (33); The internally threaded sleeve (20) is provided with a first positioning hole (221) and a second positioning hole (222); the left shaft shoulder (36) is located at the first positioning hole (221), and the left square plate (37) is located at the outside of the internally threaded sleeve (20); the right shaft shoulder (32) is located at the second positioning hole (222), and the right square plate (31) is located at the outside of the internally threaded sleeve (20).

4. The measuring device for the effective length of the internal thread lifting hole according to claim 1, characterized in that: The left L-shaped measuring plate (60) comprises a first guide hole (62), a first right-hand threaded hole (61), a first long arc surface (63) and a first short arc surface (64); The diameter of the first guide hole (62) of the left L-shaped measuring plate (60) matches the diameter of the guide shaft (40); The first right-hand threaded hole (61) of the left L-shaped measuring plate (60) matches the right-hand thread on the left threaded rod (35) of the left and right threaded rotating shaft assembly (30).

5. The measuring device for the effective length of the internal thread lifting hole according to claim 1, characterized in that: The right L-shaped measuring plate comprises a second guide hole (52), a second left-hand threaded hole (51), a second long arc surface (53) and a second short arc surface (54); The diameter of the second guide hole (52) of the right L-shaped measuring plate (50) matches the diameter of the guide shaft (40); The second left-hand threaded hole (51) of the right L-shaped measuring plate (50) matches the left-hand thread on the right threaded rod (33) of the left-right threaded rotating shaft assembly (30).

6. The measuring device for the effective length of the internal thread lifting hole according to claim 3, characterized in that: It also includes a positioning ring (3), wherein the number of the positioning rings (3) is two and they are respectively mounted on the left shaft shoulder (36) and the right shaft shoulder (32).

7. The device for measuring the effective length of an internal threaded lifting hole according to claim 6, characterized in that: It also comprises a connecting piece, through which the positioning ring (3) is connected to the left and right threaded rotating shaft assembly (30) into one body.

8. The device for measuring the effective length of an internal threaded lifting hole according to claim 2, characterized in that: The distance that the top surface of the first short arc surface (64) extends from the top surface of the first long arc surface (63) is twice the measured thread pitch of the threaded hole.

9. The device for measuring the effective length of an internal threaded lifting hole according to claim 2, characterized in that: The thickness of the first short arc surface (64) and the second short arc surface (54) is 1 mm smaller than the minimum length of the internal thread backing groove measured in accordance with GB / T3-1997.

10. A method for measuring the effective length of an internal thread lifting hole, characterized in that: The device for measuring the effective length of the internal thread lifting hole according to claim 2 comprises the following steps: S1, installing the measuring device for the effective length of the internal thread lifting hole into the internal thread lifting hole (13) of the gas generator (10), and rotating the internal thread sleeve (20) so that the two are screwed into one; S2, rotating the left disk (37) and the right disk (31) so that the top surface of the first short arc (64) of the left L-shaped measuring plate (60) and the top surface of the second short arc (54) of the right L-shaped measuring plate (50) are respectively fitted with the inner wall of the internal thread lifting hole (13); S3, continue to rotate the internally threaded sleeve (20) until the left disk (37) and the right disk (31) are rotated so that the first short arc surface (64) of the left L-shaped measuring plate (60) and the short arc surface (54) of the right L-shaped measuring plate (50) enter the back-cut groove (11) of the internally threaded lifting hole (13) of the gas generator and contact the inner wall surface, then reversely rotate the internally threaded sleeve (20) until it contacts the internally threaded end surface of the lifting hole (13), and stop the reverse rotation; S4. Use a vernier caliper to accurately measure the distance L3 from the upper end surface of the internally threaded sleeve (20) to the upper end surface of the internally threaded lifting hole (13) of the gas generator (10), and obtain the effective length L1 = L2-L3 of the internally threaded lifting hole (13) of the gas generator (10); Wherein L2 is the distance from the upper end surface of the internal thread sleeve (20) to the measuring reference surface (65) of the left L-shaped measuring plate (60).

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