Detection Device and Detection Method for Pitch Diameter of Internal Thread

Abstract

The present disclosure provides a detection device and a detection method for the pitch diameter of an internal thread, belonging to the technical field of measurement. The detection device includes an adjustment structure and a detection structure; the adjustment structure includes a fixed sleeve, a sliding rod, a locking assembly and a base. The first end of the sliding rod is coaxially and movably inserted into the first end of the fixed sleeve, and the locking assembly is sleeved outside the fixed sleeve and the sliding rod for locking the sliding rod in the fixed sleeve. The base is connected to the second end of the fixed sleeve, and the base is used to fit with the cylindrical surface of the minor diameter of the internal thread to be detected; the detection structure includes a detection head and a micrometer. The detection head is connected to the micrometer, and the micrometer is connected to the second end of the sliding rod. The detection head is used to fit with the tooth profile groove of the internal thread, and the straight line where the detection head and the fixed sleeve are located is perpendicular to the axis of the internal thread. Through the detection device, the present disclosure can detect the pitch diameter of internal threads with different tooth profiles, pitches and thread specifications.

Description

Technical Field

[0001] The present disclosure belongs to the technical field of measurement, and particularly relates to a detection device and a detection method for the pitch diameter of an internal thread. Background Art

[0002] The pitch diameter of a thread is the diameter of an imaginary cylinder, and the generatrix of the imaginary cylinder passes through the groove (tooth profile groove) and the convex width on the tooth profile in the axial section of the thread being equal. The pitch diameter of a thread is a very important value and has an important impact on the assembly quality of a workpiece.

[0003] In the related art, for an internal thread, the detection and measurement device for the pitch diameter of the internal thread includes an internal thread micrometer and two measurement contacts connected to the internal thread micrometer. Among them, one measurement contact is in the shape of a cone, and one measurement contact has a V-shaped groove. During actual measurement, first, corresponding measurement contacts and an internal thread micrometer need to be selected according to the different tooth profile grooves and pitches of the internal thread. Then, the two selected measurement contacts are connected to both ends of the internal thread micrometer, and one of the two selected measurement contacts (the measurement contact with a V-shaped groove) is clamped in the tooth profile groove of the internal thread, and the other (the measurement contact in the shape of a cone) is sleeved on the conical surface opposite to the tooth profile groove. The corresponding reading of the internal thread micrometer is the actual size of the pitch diameter of the internal thread.

[0004] Since there are a very large number of combinations of tooth profiles and pitches for internal threads, to meet the product requirements, a very large number of measurement contacts and internal thread micrometers of different specifications need to be configured. Moreover, the common measurement contacts on the market are all for metric ordinary threads (such as triangular threads, etc.), and there are very few measurement contacts suitable for special tooth profile threads, such as sawtooth threads and trapezoidal threads, resulting in limited use of the above devices and inability to be widely used. Summary of the Invention

[0005] Embodiments of the present disclosure provide a detection device and a detection method for the pitch diameter of an internal thread, which can detect the pitch diameter of internal threads with different tooth profiles, pitches, and thread specifications. The technical solution is as follows:

[0006] An embodiment of the present disclosure provides a detection device for the pitch diameter of an internal thread. The detection device includes an adjustment structure and a detection structure. The adjustment structure includes a fixed sleeve, a sliding rod, a locking assembly, and a base. The first end of the sliding rod is coaxially and movably inserted into the first end of the fixed sleeve, and the locking assembly is sleeved outside the fixed sleeve and the sliding rod for locking the sliding rod in the fixed sleeve. The base is connected to the second end of the fixed sleeve, and the base is used to fit against the cylindrical surface of the minor diameter of the internal thread to be detected. The detection structure includes a detection head and a micrometer. The detection head is connected to the micrometer, and the micrometer is connected to the second end of the sliding rod. The detection head is used to fit against the tooth profile groove of the internal thread, and the straight line where the detection head and the fixed sleeve are located is perpendicular to the axis of the internal thread.

[0007] In another implementation manner of the present disclosure, the base includes a wedge block and a screw sleeve. The wedge block is a triangular block structure. One end of the screw sleeve is connected to the bottom surface of the wedge block. The triangular wedge top edge of the wedge block is used to fit against the cylindrical surface of the minor diameter of the internal thread. The triangular wedge top edge of the wedge block is coplanar and perpendicular to the axis of the screw sleeve, and the bottom surface of the wedge block is arranged opposite to the triangular wedge top edge of the wedge block. The other end of the screw sleeve is connected to the fixed sleeve.

[0008] In another implementation manner of the present disclosure, the locking assembly includes a fixed collar, a sliding collar, and an elastic member. The first end of the fixed collar is connected to the first end of the fixed sleeve. The fixed collar is sleeved outside the sliding rod and is in contact with the outer wall of the sliding rod. The outer diameter of the fixed collar gradually decreases along the direction from the second end of the fixed collar to the middle of the fixed collar, and a plurality of strip-shaped grooves are provided between the second end and the middle of the fixed collar. One end of the strip-shaped groove is an opening and is located at the second end of the fixed collar. The sliding collar is slidably sleeved outside the second end of the fixed collar. An accommodation cavity is formed between the sliding collar and the fixed collar. The elastic member is located in the accommodation cavity and is arranged along the axis direction of the sliding rod. Both ends of the elastic member are respectively abutted against the outer wall of the fixed collar and the inner wall of the sliding collar.

[0009] In yet another implementation manner of the present disclosure, the fixed collar includes a first ring body and a second ring body. The first end of the first ring body is sleeved outside the first end of the second ring body. The sliding collar is slidably sleeved outside the first ring body and the second ring body. The outer wall of the second ring body from the middle to the second end is a conical surface. The second end of the first ring body is connected to the fixed sleeve. The elastic member is sleeved outside the second ring body. A receiving cavity is formed among the first end face of the first ring body, the inner wall of the sliding collar, and the outer wall of the second ring body. The strip-shaped groove is located on the outer wall of the second ring body, and the opening is located at the second end of the second ring body.

[0010] In yet another implementation manner of the present disclosure, the inner wall of the sliding collar has a first limiting inner flange, and a limiting hook is provided at the outer wall of the second end of the second ring body and is matched with the first limiting inner flange.

[0011] In yet another implementation manner of the present disclosure, the inner wall of the sliding collar has a second limiting inner flange. The second limiting inner flange and the first limiting inner flange are arranged at intervals, and the second limiting inner flange is located between the first limiting inner flange and the first ring body. The second end of the elastic member abuts against the second limiting inner flange.

[0012] In yet another implementation manner of the present disclosure, the detection head includes a connecting rod and a hemispherical head. One end of the connecting rod is connected to the hemispherical head, and the other end of the connecting rod is connected to the micrometer.

[0013] In yet another implementation manner of the present disclosure, the middle part of the connecting rod has an outer flange, and the outer flange abuts against the end of the micrometer.

[0014] In yet another implementation manner of the present disclosure, a method for detecting the pitch diameter of an internal thread is further provided. The detection method is based on the above-mentioned detection device. The detection method includes: zeroing the micrometer in the detection device; adjusting the position of the slide bar in the detection device relative to the fixed sleeve so that the total length of the detection device is less than the minor diameter of the internal thread, and recording the current total length L of the detection device 1 ; placing the detection device in the internal thread, fitting one side of the base to the cylindrical surface of the minor diameter of the internal thread, adjusting the micrometer in the detection device so that the detection head extends into the tooth profile groove of the internal thread and the detection head fits with both sides of the tooth profile groove, and reading the maximum reading of the micrometer as L 2 ; according to the L 1 、L 2 and the diameter of the detection head and the parameters of the internal thread, obtaining the pitch diameter of the internal thread.

[0015] In yet another implementation manner of the present disclosure, according to the L 1 , L 2 and the diameter of the detection head and the parameters of the internal thread, obtaining the pitch diameter of the internal thread includes:

[0016] The pitch diameter of the internal thread satisfies the following formula:

[0017] D 2 = 2(L 1 + L 2 ) - D 1 - K 1 d 0 - K 2 p;

[0018] Wherein, D 2 is the pitch diameter of the internal thread; D 1 is the minor diameter of the internal thread; d 0 is the outer diameter of the detection head; p is the pitch of the internal thread; K 1 and K 2 are coefficients.

[0019] The beneficial effects brought by the technical solution provided by the embodiments of the present disclosure are:

[0020] When detecting the pitch diameter of the internal thread by the detection device for the pitch diameter of the internal thread provided by the embodiments of the present disclosure, the length of the adjustment structure can be adjusted by moving the sliding rod relative to the fixed sleeve, and at the same time, the sliding rod can be locked on the fixed sleeve through the locking component to fix the length of the adjustment structure.

[0021] Moreover, since the detection device further includes a detection head and a micrometer, the detection head can be attached to the tooth profile groove of the internal thread and the base can be attached to the minor diameter cylindrical surface of the internal thread during detection, and then the pitch diameter of the internal thread can be calculated by reading the value of the micrometer and combining the length of the detection device. When detecting various types of internal threads, the detection device only needs the detection head to cooperate with the tooth profile groove of the internal thread and the base to be attached to the minor diameter cylindrical surface of the internal thread, avoiding the need to set multiple measurement contacts of different types and specifications due to different types of internal threads, and greatly improving the applicability of the detection device. Description of the Drawings

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present disclosure. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0023] Figure 1It is a schematic diagram of the basic parameters of the internal thread provided by the embodiments of the present disclosure;

[0024] Figure 2 It is a schematic diagram of several common internal threads provided by the embodiments of the present disclosure;

[0025] Figure 3 It is a schematic diagram of the structure of the detection device provided by the embodiments of the present disclosure;

[0026] Figure 4 It is a schematic diagram of the structure of the base provided by the embodiments of the present disclosure;

[0027] Figure 5 It is a schematic diagram of the structure of the locking structure provided by the embodiments of the present disclosure;

[0028] Figure 6 It is a schematic diagram of the structure of the detection head provided by the embodiments of the present disclosure;

[0029] Figure 7 It is a flowchart of the method for detecting the pitch diameter of the internal thread provided by the embodiments of the present disclosure;

[0030] Figure 8 It is a usage state diagram of the detection device provided by the embodiments of the present disclosure.

[0031] The meanings of the symbols in the figure are as follows:

[0032] 1. Adjustment structure; 11. Fixed sleeve; 12. Slide bar; 13. Locking assembly; 131. Fixed collar; 1311. First ring body; 1312. Second ring body; 1313. Limit hook; 132. Sliding collar; 1321. First limit inner flange; 1322. Second limit inner flange; 134. Elastic member; 130. Accommodation cavity; 1310. Strip-shaped groove; 14. Base; 141. Wedge block; 142. Threaded sleeve;

[0033] 2. Detection structure; 21. Detection head; 211. Connecting rod; 2111. Outer flange; 212. Hemispherical head; 22. Micrometer. Detailed implementation manners

[0034] To make the objectives, technical solutions and advantages of the present disclosure clearer, the following will further describe the embodiments of the present disclosure in detail with reference to the accompanying drawings.

[0035] To clearly illustrate the detection device for the pitch diameter of the internal thread provided by the embodiments of the present disclosure, the relevant parameters of the internal thread are introduced first here.

[0036] Major diameter (root diameter) of the internal thread: The diameter of the imaginary cylinder that coincides with the root of the internal thread. Generally, the nominal diameter of the thread is the major diameter, such as Figure 1 the D in 4 .

[0037] Minor diameter (crest diameter) of internal thread: The diameter of the imaginary cylinder that coincides with the crest of the internal thread, such as Figure 1 D in 1 .

[0038] Pitch diameter of internal thread: The diameter of the imaginary cylinder whose generatrix passes through the equal widths of the protrusion and groove on the thread profile, such as Figure 1 D in 2 .

[0039] Pitch of internal thread: The axial distance between two corresponding points on the pitch diameter line of adjacent teeth, such as Figure 1 p in

[0040] Thread angle of internal thread: The angle α between two adjacent flank sides on the thread profile groove, and the half thread angle is α / 2 (see Figure 2 Figures a and c in

[0041] Flank angle of internal thread: The angle between the flank of the thread profile groove and the perpendicular line to the thread axis, such as α 1 , α 2 , and the thread angle is (α 1 +α 2 ).

[0042] In addition, internal threads can be classified into triangular threads (ordinary threads), rectangular threads, trapezoidal threads, serrated threads, and other special-shaped threads according to their cross-sectional shapes (thread profile grooves), see Figure 2 Figures a, b, c, and d in

[0043] An embodiment of the present disclosure provides a device for detecting the pitch diameter of an internal thread, as shown in Figure 3 . The detection device includes an adjustment structure 1 and a detection structure 2. The adjustment structure 1 includes a fixed sleeve 11, a slide rod 12, a locking assembly 13, and a base 14. The first end of the slide rod 12 is coaxially and movably inserted into the first end of the fixed sleeve 11, and the locking assembly 13 is sleeved outside the fixed sleeve 11 and the slide rod 12 for locking the slide rod 12 in the fixed sleeve 11. The base 14 is connected to the second end of the fixed sleeve 11, and the base 14 is used to fit with the cylindrical surface of the minor diameter of the internal thread to be detected. The detection structure 2 includes a detection head 21 and a micrometer 22. The detection head 21 is connected to the micrometer 22, and the micrometer 22 is connected to the second end of the slide rod 12. The detection head 21 is used to fit with the thread profile groove of the internal thread, and the straight line where the detection head 21 and the fixed sleeve 11 are located is perpendicular to the axis of the internal thread.

[0044] When the detection device for the pitch diameter of the internal thread provided by the embodiments of the present disclosure detects the pitch diameter of the internal thread, the length of the adjustment structure 1 can be adjusted by moving the sliding rod 12 relative to the fixed sleeve 11, and at the same time, the sliding rod 12 can be locked on the fixed sleeve 11 through the locking assembly 13 to fix the length of the adjustment structure 1.

[0045] Moreover, since the detection device further includes a detection head 21 and a micrometer 22, during detection, the detection head 21 can be fitted with the tooth profile groove of the internal thread, and the base 14 can be fitted with the small diameter cylindrical surface of the internal thread. Then, by reading the value of the micrometer 22 and combining the length of the detection device, the pitch diameter of the internal thread can be calculated. When detecting various types of internal threads, the detection device only needs the detection head 21 to cooperate with the tooth profile groove of the internal thread and the base 14 to be fitted with the small diameter cylindrical surface of the internal thread, avoiding the need to set multiple measuring contacts of different types and specifications due to different types of internal threads, greatly improving the applicability of the detection device.

[0046] Figure 4 Schematic diagram of the structure of the base provided by the embodiments of the present disclosure, combined with Figure 4 For example, the base 14 includes a wedge block 141 and a screw sleeve 142. The wedge block 141 is a triangular block structure.

[0047] One end of the screw sleeve 142 is connected to the bottom surface of the wedge block 141. The triangular wedge top edge of the wedge block 141 is used to fit with the small diameter cylindrical surface of the internal thread. The triangular wedge top edge of the wedge block 141 is coplanar and perpendicular to the axis of the screw sleeve 142, and the bottom surface of the wedge block 141 is arranged opposite to the triangular wedge top edge of the wedge block 141. The other end of the screw sleeve 142 is connected to the fixed sleeve 11.

[0048] In the above implementation, the base 14 is set as the wedge block 141 and the screw sleeve 142, which can be connected to the fixed sleeve 11 through the screw sleeve 142, and at the same time, the wedge block 141 is fitted with the small diameter cylindrical surface of the internal thread.

[0049] In addition, since the small diameter cylindrical surface of the internal thread is an arc-shaped surface, in order to enable the wedge block 141 to achieve good fitting with the small diameter cylindrical surface of the internal thread, the wedge block 141 is set as a triangular block structure, so that the triangular wedge top edge of the wedge block 141 is tangent to the small diameter cylindrical surface of the internal thread, thereby improving the fitting between the two.

[0050] For example, the screw sleeve 142 is threadedly sleeved on the fixed sleeve 11, which can facilitate the detachable connection between the two.

[0051] Figure 5 Schematic diagram of the structure of the locking structure provided by the embodiments of the present disclosure, combined with Figure 5, optionally, the locking assembly 13 includes a fixed collar 131, a sliding collar 132, and an elastic member 134. The first end of the fixed collar 131 is connected to the first end of the fixed sleeve 11. The fixed collar 131 is sleeved outside the sliding rod 12 and is in contact with the outer wall of the sliding rod 12. The outer diameter of the fixed collar 131 gradually decreases along the direction from the second end of the fixed collar 131 to the middle of the fixed collar 131. A plurality of strip-shaped grooves 1310 are provided between the second end and the middle of the fixed collar 131. One end of each strip-shaped groove 1310 is open and located at the second end of the fixed collar 131

[0052] The sliding collar 132 is slidably sleeved outside the second end of the fixed collar 131. An accommodation cavity 130 is formed between the sliding collar 132 and the fixed collar 131. The elastic member 134 is located in the accommodation cavity 130 and is arranged along the axial direction of the sliding rod 12. Two ends of the elastic member 134 respectively abut against the outer wall of the fixed collar 131 and the inner wall of the sliding collar 132.

[0053] In the above implementation, the locking assembly 13 is set as the fixed collar 131, the sliding collar 132, and the elastic member 134. In this way, the locking assembly 13 can be connected to the fixed sleeve 11 through the fixed collar 131. At the same time, the elastic member 134 enables the sliding collar 132 to be as far away from the first end of the fixed collar 131 as possible when no external force is applied, that is, the sliding collar 132 is sleeved outside the second end of the fixed collar 131 as much as possible. Moreover, since the outer diameter of the fixed collar 131 is gradually changing and there are a plurality of strip-shaped grooves 1310, the fixed collar 131 can be expanded and contracted in the radial direction under the clamping of the sliding collar 132, thereby restricting the inner diameter of the second end of the fixed collar 131 and realizing the clamping between the fixed collar 131 and the sliding rod 12.

[0054] The reason why the sliding collar 132 can move is that it is convenient to flexibly adjust the position of the sliding collar 132 on the fixed collar 131 to unlock the locking between the fixed collar 131 and the sliding rod 12.

[0055] That is to say, when no external force is applied, due to the action of the elastic member 134, the sliding collar 132 is stably sleeved at the second end of the fixed collar 131 to clamp the second end of the fixed collar 131 and limit the slide bar 12 within the second end of the fixed collar 131, thereby realizing the connection and fixation between the slide bar 12 and the fixed sleeve 11. When it is necessary to adjust the position of the slide bar 12 relative to the fixed sleeve 11, the sliding collar 132 can be toggled by hand to move the sliding collar 132 towards the first end of the fixed collar 131, thereby unlocking the connection between the slide bar 12 and the fixed sleeve 11, adjusting the position of the slide bar 12, and then releasing the sliding collar 132 so that the sliding collar 132 clamps the second end of the fixed collar 131 again under the action of the elastic member 134, thereby realizing the clamping between the fixed collar 131 and the slide bar 12 again.

[0056] Continue to refer to Figure 5 , optionally, the fixed collar 131 includes a first ring body 1311 and a second ring body 1312. The first end of the first ring body 1311 is sleeved outside the first end of the second ring body 1312. The sliding collar 132 is slidably sleeved outside the first ring body 1311 and the second ring body 1312. The outer wall of the second ring body 1312 from the middle to the second end is a conical surface.

[0057] The second end of the first ring body 1311 is connected to the fixed sleeve 11. The elastic member 134 is sleeved outside the second ring body 1312. An accommodation cavity 130 is formed between the first end face of the first ring body 1311, the inner wall of the sliding collar 132, and the outer wall of the second ring body 1312. The strip-shaped groove 1310 is located on the outer wall of the second ring body 1312, and the opening is located at the second end of the second ring body 1312.

[0058] In the above implementation manner, the fixed collar 131 is set as the first ring body 1311 and the second ring body 1312, which can facilitate the formation of the accommodation cavity 130 to provide an installation basis for the elastic member 134. At the same time, it is also convenient for the connection between the fixed sleeve 11 and the slide bar 12.

[0059] Exemplarily, the first ring body 1311 is threadedly sleeved outside the second ring body 1312. By adjusting the screwing length of the thread, the size of the accommodation cavity 130 can be changed, thereby adjusting the pre-tightening force of the elastic member 134.

[0060] Optionally, the inner wall of the sliding collar 132 has a first limiting inner flange 1321, and a limiting hook 1313 is provided at the outer wall of the second end of the second ring body 1312 to cooperate with the first limiting inner flange 1321.

[0061] In the above implementation manner, the first limiting inner flange 1321 and the limiting hook 1313 are arranged such that the sliding collar 132 can be stably clamped outside the second ring body 1312 under the action of the elastic member 134, and the second ring body 1312 is tightly sleeved outside the sliding rod 12.

[0062] Exemplarily, the cooperation between the first limiting inner flange 1321 and the limiting hook 1313 mentioned above means that when the sliding rod 12 is separated from the fixed sleeve 11 and the locking assembly 13, under the action of the elastic member 134, the first limiting inner flange 1321 and the limiting hook 1313 are always in contact with each other and will not separate from the second ring body 1312.

[0063] Optionally, the inner wall of the sliding collar 132 has a second limiting inner flange 1322. The second limiting inner flange 1322 and the first limiting inner flange 1321 are arranged at intervals, and the second limiting inner flange 1322 is located between the first limiting inner flange 1321 and the first ring body 1311. The second end of the elastic member 134 abuts against the second limiting inner flange 1322.

[0064] In the above implementation manner, the arrangement of the second limiting inner flange 1322 can conveniently clamp the elastic member 134 in the accommodating cavity 130.

[0065] Figure 6 The following is a schematic structural diagram of the detection head provided by an embodiment of the present disclosure. In combination with Figure 6 , optionally, the detection head 21 includes a connecting rod 211 and a hemispherical head 212. One end of the connecting rod 211 is connected to the hemispherical head 212, and the other end of the connecting rod 211 is connected to the micrometer 22.

[0066] In the above implementation manner, the detection head 21 is arranged as the connecting rod 211 and the hemispherical head 212. In this way, the hemispherical head 212 can be connected to the micrometer 22 through the connecting rod 211, and at the same time, the hemispherical head 212 can be stably located in the tooth profile groove of the internal thread to be detected for convenient detection.

[0067] Of course, the detection head 21 is arranged as the hemispherical head 212 to facilitate the calculation of the coefficient K 1 and K 2 (which will be introduced later).

[0068] Exemplarily, the connecting rod 211 is threadedly connected to the micrometer 22. This facilitates the detachable connection between the two. The hemispherical head 212 and the connecting rod 211 can be an integrally formed structural member, which is convenient for processing and manufacturing.

[0069] Exemplarily, the middle part of the connecting rod 211 has an outer flange 2111. The outer flange 2111 abuts against the end of the micrometer 22.

[0070] In this way, the connecting rod 211 can be positioned at one end of the micrometer screw 22 by the outer flange.

[0071] On the other hand, the present disclosure is an embodiment that further provides a method for detecting the middle diameter of an internal thread, such as Figure 7 As shown, the detection method is based on the above-mentioned detection device, and the detection method includes:

[0072] S701: Return the micrometer screw in the detection device to zero.

[0073] S702: Adjust the position of the slide bar in the detection device relative to the fixed sleeve so that the total length of the detection device is smaller than the minor diameter of the internal thread, and record the current total length L of the detection device. 1 .

[0074] Exemplarily, the position of the slide rod relative to the fixed sleeve can be adjusted by adjusting the locking assembly in the detection device so that the total length of the detection device is slightly smaller than the minor diameter of the internal thread, and a caliper or other instrument is used to measure and record the current total length of the detection device.

[0075] The total length of the above-mentioned detection device is slightly smaller than the minor diameter of the internal thread, and the difference between the total length of the detection device and the minor diameter of the internal thread can be 1 to 10 mm.

[0076] S703: Place the detection device in the inner hole of the internal thread, fit one side of the base with the cylindrical surface of the internal thread minor diameter, adjust the screw micrometer in the detection device so that the detection head penetrates into the tooth groove of the internal thread and fits with both sides of the tooth groove. The maximum reading of the screw micrometer is L 2 .

[0077] In the above step S703, when one side of the base is fitted with the cylindrical surface of the internal thread minor diameter, the triangular wedge-shaped top edge of the base is actually fitted with the cylindrical surface of the internal thread minor diameter. At the same time, by adjusting the micrometer in the detection device, the spherical surface of the hemispherical head of the detection head is made to penetrate into the tooth groove of the internal thread and the spherical surface is fitted with both sides of the tooth groove, and then the maximum reading of the micrometer is read.

[0078] By adjusting the screw micrometer as described above, the total length of the detection device can be further adjusted so that the detection head can fully fit the groove surface of the tooth groove.

[0079] S704: According to L 1 , L 2 The diameter of the detection head and the parameters of the internal thread can be used to obtain the median diameter of the internal thread.

[0080] The above method has the same beneficial effects as the aforementioned detection device, and will not be described in detail here.

[0081] In this embodiment, before step 701, it is necessary to select a suitable detection head according to the relevant parameters of the internal thread so that the detection head can be located in the tooth profile groove of the internal thread to be detected.

[0082] Exemplarily, according to the tooth profile angle and pitch of the internal thread to be measured, the optimal outer diameter d of the required detection head is calculated by a formula 最佳 , and the detection head actually used is selected. The outer diameter of this detection head should be as close as possible to the calculated value of the optimal outer diameter d 最佳 .

[0083] Among them, the formula for calculating the optimal outer diameter d of the detection head 最佳 can refer to the calculation formulas corresponding to different types of internal threads in the industry, which will not be elaborated here.

[0084] After selecting the detection head, then connect the corresponding detection head to the detection device for detecting the pitch diameter of the internal thread.

[0085] The above method has the same beneficial effects as the aforementioned detection device, which will not be elaborated here.

[0086] Optionally, step S704 can be implemented in the following manner:

[0087] Exemplarily, the pitch diameter of the internal thread satisfies the following formula:

[0088] D 2 = 2(L 1 + L 2 ) - D 1 - K 1 d 0 - K 2 p; (1)

[0089] Among them, D 2 is the pitch diameter of the internal thread; D 1 is the minor diameter of the internal thread; d 0 is the outer diameter of the detection head; p is the pitch of the internal thread; K 1 and K 2 are coefficients.

[0090] The above formula (1) can be derived from the following formula (2).

[0091] 2M = 2×(L 1 + L 2 ) = D 2 + D 1 + K 1 × d 0 + K 2 × p; (2)

[0092] Among them, M can be seen in Figure 8As shown, it is the total length of the detection device corresponding to when it fits with the internal thread; D 2 is the pitch diameter of the internal thread; D 1 is the minor diameter of the internal thread; d 0 is the outer diameter of the detection head; p is the pitch of the internal thread; K 1 and K 2 are coefficients.

[0093] In addition, combining Figure 8 , it can be known that:

[0094]

[0095] where x can be Figure 8 as shown in, representing the distance from the spherical vertex of the detection head to the pitch diameter of the internal thread. In order to make formula (3) more general, x can be related to d 0 and the pitch p of the internal thread, and thus formula (1) can be obtained.

[0096] In addition, due to different types of internal threads, the calculation methods of K 1 and K 2 in the above formula (1) or (2) will be different.

[0097] Generally speaking, when the tooth profile groove of the internal thread section is an asymmetric figure, the following formulas (4) and (5) can be used to calculate K 1 and K 2 respectively. When the tooth profile groove of the internal thread section is a symmetric figure, the following formulas (6) and (7) can be used to calculate K 1 and K 2 respectively.

[0098]

[0099]

[0100] where, α 1 , α 2 are the flank angles of the tooth profile groove of the internal thread.

[0101]

[0102]

[0103] where, α is the tooth profile angle of the tooth profile groove of the internal thread.

[0104] The above calculation formulas (4)-(7) can all be derived from relevant mathematical formulas and will not be elaborated here.

[0105] The following combines specific examples and the appendix Figure 8To further illustrate the above detection method:

[0106] For example, taking the internal thread of a zigzag thread (3°, 30°) as an example, when detecting the pitch diameter of the internal thread, it can be achieved through the following steps:

[0107] First, according to the thread angle and pitch of the internal thread to be measured, calculate the optimal outer diameter of the required detection head through the formula, and select the actually used detection head according to the optimal outer diameter, so that the outer diameter of the detection head satisfies the following formula:

[0108]

[0109] Among them, d 0 is the outer diameter of the actually selected detection head; d 最佳 is the optimal outer diameter of the detection head; α 1 , α 2 are the flank angles of the internal thread; p is the pitch of the internal thread.

[0110] Then, zero the micrometer, turn the sliding collar 132, and adjust the extension length of the slide rod 12 so that the total length of the detection device is slightly less than the minor diameter D 1 of the internal thread to be measured. At this time, record the total length of the current detection device as L 1 .

[0111] Next, press the triangular wedge top edge of the base of the detection device against the minor diameter cylindrical surface of the internal thread, and keep the triangular wedge top edge parallel to the axis of the minor diameter of the internal thread. Slowly adjust the micrometer, insert the detection head into the thread groove of the internal thread until the spherical surface of the detection head contacts both side walls of the thread groove of the internal thread, and when the reading of the micrometer is the largest (indicating that the extension distance of the micrometer is the largest at this time), record the reading L 2 of the micrometer.

[0112] S4. Calculate the pitch diameter of the internal thread according to the foregoing formula (1).

[0113] Among them, K 1 and K 2 can be obtained according to formulas (4) and (5).

[0114] For another example, taking a common internal thread (60° triangular internal thread) as an example, when detecting the pitch diameter of the internal thread, it can be achieved through the following steps:

[0115] The difference from the above example is that the calculation formula of d 最佳 is different, and the following formula is adopted:

[0116]

[0117] Among them, d 0is the outer diameter of the actually selected detection head; d 最佳 is the optimal outer diameter of the detection head; α / 2 is the half angle of the thread profile of the internal thread; p is the pitch of the internal thread.

[0118] And K 1 and K 2 can be obtained according to formulas (6) and (7).

[0119] The above are only optional embodiments of the present disclosure and are not intended to limit the present disclosure. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present disclosure shall be included within the protection scope of the present disclosure.

Claims

1. A detecting device for the pitch diameter of an internal thread, characterized in that, the detecting device comprises an adjusting structure (1) and a detecting structure (2); the adjusting structure (1) comprises a fixed sleeve (11), a sliding rod (12), a locking assembly (13) and a base (14). The first end of the sliding rod (12) is coaxially and movably inserted into the first end of the fixed sleeve (11), and the locking assembly (13) is sleeved outside the fixed sleeve (11) and the sliding rod (12) for locking the sliding rod (12) in the fixed sleeve (11). The locking assembly (13) comprises a fixed collar (131), a sliding collar (132) and an elastic member (134). The first end of the fixed collar (131) is connected to the first end of the fixed sleeve (11). The fixed collar (131) is sleeved outside the sliding rod (12) and is in contact with the outer wall of the sliding rod (12). The outer diameter of the fixed collar (131) gradually decreases along the direction from the second end of the fixed collar (131) to the middle of the fixed collar (131), and a plurality of strip-shaped grooves (1310) are provided between the second end and the middle of the fixed collar (131). One end of the strip-shaped groove (1310) is open and located at the second end of the fixed collar (131). The sliding collar (132) is slidably sleeved outside the second end of the fixed collar (131). A receiving cavity (130) is formed between the sliding collar (132) and the fixed collar (131). The elastic member (134) is located in the receiving cavity (130) and is arranged along the axial direction of the sliding rod (12). Two ends of the elastic member (134) are respectively abutted against the outer wall of the fixed collar (131) and the inner wall of the sliding collar (132). The fixed collar (131) comprises a first ring body (1311) and a second ring body (1312). The first end of the first ring body (1311) is sleeved outside the first end of the second ring body (1312). The sliding collar (132) is slidably sleeved outside the first ring body (1311) and the second ring body (1312). The outer wall of the second ring body (1312) from the middle to the second end is a conical surface. The second end of the first ring body (1311) is connected to the fixed sleeve (11). The elastic member (134) is sleeved outside the second ring body (1312), and a receiving cavity (130) is formed between the first end face of the first ring body (1311), the inner wall of the sliding collar (132) and the outer wall of the second ring body (1312). The strip-shaped grooves (1310) are located on the outer wall of the second ring body (1312), and the opening is located at the second end of the second ring body (1312); The base (14) is connected to the second end of the fixed sleeve (11). The base (14) is used to fit against the cylindrical surface of the minor diameter of the internal thread to be detected. The base (14) includes a wedge block (141) and a screw sleeve (142). The wedge block (141) is of a triangular block structure. One end of the screw sleeve (142) is connected to the bottom surface of the wedge block (141). The triangular wedge top edge of the wedge block (141) is used to fit against the cylindrical surface of the minor diameter of the internal thread. The triangular wedge top edge of the wedge block (141) is coplanar and perpendicular to the axis of the screw sleeve (142), and the bottom surface of the wedge block (141) is arranged opposite to the triangular wedge top edge of the wedge block (141). The other end of the screw sleeve (142) is connected to the fixed sleeve (11); The detection structure (2) includes a detection head (21) and a micrometer (22). The detection head (21) is connected to the micrometer (22), and the micrometer (22) is connected to the second end of the slide bar (12). The detection head (21) is used to fit against the tooth profile groove of the internal thread, and the straight line where the detection head (21) and the fixed sleeve (11) are located is perpendicular to the axis of the internal thread.

2. The detection device according to claim 1, characterized in that, The inner wall of the sliding collar (132) has a first limiting inner flange (1321), and a limiting hook (1313) matching with the first limiting inner flange (1321) is arranged at the outer wall of the second end of the second ring body (1312).

3. The detection device according to claim 2, characterized in that, The inner wall of the sliding collar (132) has a second limiting inner flange (1322). The second limiting inner flange (1322) is arranged at an interval from the first limiting inner flange (1321), and the second limiting inner flange (1322) is located between the first limiting inner flange (1321) and the first ring body (1311). The second end of the elastic member (134) abuts against the second limiting inner flange (1322).

4. The detection device according to any one of claims 1-3, characterized in that, The detection head (21) includes a connecting rod (211) and a hemispherical head (212). One end of the connecting rod (211) is connected to the hemispherical head (212), and the other end of the connecting rod (211) is connected to the micrometer (22).

5. The detection device according to claim 4, characterized in that, The middle part of the connecting rod (211) has an outer flange (2111), and the outer flange (2111) abuts against the end of the micrometer (22).

6. A method for detecting the pitch diameter of an internal thread, characterized in that, The detection method is based on the detection device according to any one of claims 1-5. The detection method includes: Zeroing the micrometer in the detection device; Adjust the position of the slide bar relative to the fixed sleeve in the detection device so that the total length of the detection device is less than the minor diameter of the internal thread, and record the current total length L of the detection device 1 ; Place the detection device inside the internal thread, make one side of the base fit with the cylindrical surface of the minor diameter of the internal thread, adjust the micrometer in the detection device so that the detection head extends into the tooth profile groove of the internal thread and makes the detection head fit with both sides of the tooth profile groove, and read the maximum reading of the micrometer as L 2 ; According to the L 1 , L 2 , and the diameter of the detection head and the parameters of the internal thread, the pitch diameter of the internal thread is obtained.

7. The detection method according to claim 6, characterized in that, Said according to the said L 1 、L 2 and the diameter of the said detection head and the parameters of the said internal thread, obtaining the pitch diameter of the said internal thread, including: The pitch diameter of the internal thread satisfies the following formula: ； Among them, D 2 is the pitch diameter of the internal thread; D 1 is the minor diameter of the internal thread; d 0 is the outer diameter of the detection head; p is the pitch of the internal thread; K 1 and K 2 are coefficients.

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