Keyway symmetry degree detection measuring tool

Abstract

The utility model provides a keyway symmetry degree detection measuring tool, comprising a seat body provided with an accommodating cavity; a positioning hole cavity and a measuring hole cavity are formed in the peripheral side of the base body, both the positioning hole cavity and the measuring hole cavity are communicated with the containing cavity, and the positioning hole cavity and the measuring hole cavity are arranged at an interval of 90 degrees in the circumferential direction; the positioning structure is arranged in the positioning hole cavity, moves in the axial direction of the positioning hole cavity and is used for determining the position of the workpiece in the containing cavity; the measuring structure is arranged in the measuring hole cavity, moves in the axial direction of the measuring hole cavity and is used for measuring the distance between the surface of the workpiece and a preset point. According to the invention, the workpiece is placed in the accommodating cavity, then the positioning structure is inserted into the key groove to determine the position of the workpiece in the accommodating cavity, and finally the distance between the surface of the workpiece and the preset point is measured and calculated through the movement of the measuring structure in the measuring hole cavity in the axial direction of the measuring hole cavity. And obtaining the symmetry degree deviation of the double keyways relative to the cylindrical reference axis.

Description

Technical Field

[0001] The utility model belongs to the technical field of detection measuring tools, and particularly relates to a keyway symmetry detection measuring tool. Background Art

[0002] At present, for the symmetry detection of a double keyway shaft in the market, coordinate measuring or a combination of conventional measuring tools is used for detection. Among them, the coordinate measuring instrument is expensive and not suitable for enterprises with relatively weak strength; while the detection method of the conventional measuring tool combination, as Figure 1 shown, requires a height gauge, a V-block and a flat plate as Figure 1 shown. First, place the workpiece in the V-groove of the V-block, adjust the keyway to a horizontally symmetric position. During this period, use the height gauge to measure the heights between the left and right keyway side walls and the flat plate respectively, measure the height data a between the keyway side wall 1 and the flat plate with the height gauge, and measure the height data b between the keyway side wall 2 and the flat plate after the workpiece is rotated 180 degrees and perform calculations to obtain the symmetry deviation of the double keyway relative to the cylindrical reference axis.

[0003] However, this method of measurement requires a height gauge or a dial indicator, a V-block with relatively high precision, and a flat plate with relatively high flatness. It has relatively high requirements for the measurer, and there are deviations in the data due to the technical differences of the measurer. Therefore, it is not suitable for scenarios with a large number of workpieces, and the work efficiency is low, and it cannot meet the needs of the current rapid development. Content of the Utility Model

[0004] In order to overcome the above technical defects, the utility model provides a keyway symmetry detection measuring tool, which can solve the technical problem of how to measure the symmetry of the keyway of a workpiece in the prior art.

[0005] The utility model is realized according to the following technical scheme:

[0006] The utility model provides a keyway symmetry detection measuring tool, which includes:

[0007] A seat body, which is provided with a receiving cavity; a positioning hole cavity and a measuring hole cavity are provided on the circumferential side of the seat body, both the positioning hole cavity and the measuring hole cavity are communicated with the receiving cavity, and the positioning hole cavity and the measuring hole cavity are circumferentially spaced by 90°;

[0008] A positioning structure, which is arranged in the positioning hole cavity and moves along the axial direction of the positioning hole cavity, and is used to determine the position of the workpiece in the receiving cavity;

[0009] A measuring structure, which is arranged in the measuring hole cavity and moves along the axial direction of the measuring hole cavity, and is used to measure the distance between the workpiece surface and a preset point.

[0010] The present application abandons the conventional measuring tool combination detection method in the prior art and innovatively proposes a keyway symmetry detection measuring tool with a new structure. It only requires the workpiece to be placed in the accommodating cavity, and then the positioning structure is inserted into the keyway to determine the position of the workpiece in the accommodating cavity. Finally, the distance between the workpiece surface and the preset point is measured and calculated by moving the measuring structure in the measuring cavity and along the axial direction of the measuring cavity to obtain the symmetry deviation of the double keyway relative to the cylindrical reference axis.

[0011] In one embodiment, the number of the positioning holes is two, and the two positioning holes are arranged circumferentially at an interval of 180°; the number of the positioning structures is correspondingly two;

[0012] The number of the measuring cavities is two, and the two measuring cavities are arranged circumferentially at an interval of 180°; the number of the measuring structures is correspondingly two.

[0013] In one embodiment, the number of the positioning holes is two, and the two positioning holes are arranged circumferentially at an interval of 180°; the number of the positioning structures is correspondingly two;

[0014] The number of the measuring cavity is one; the number of the measuring structure is correspondingly one.

[0015] In one embodiment, the positioning structure has an extended position and a retracted position relative to the positioning hole;

[0016] When the positioning structure is in the extended position, the positioning end of the positioning structure extends into the keyway of the workpiece in the accommodating cavity;

[0017] When the positioning structure is in the retracted position, the positioning end of the positioning structure retracts into the positioning hole.

[0018] In one embodiment, the positioning structure includes a positioning rod, the positioning rod is provided with the positioning end and a holding end, and the holding end is located outside the positioning hole.

[0019] In one embodiment, a first limiting portion extending inwardly is provided in the positioning hole cavity;

[0020] The positioning rod is provided with a second limiting portion extending outward;

[0021] The positioning structure further includes a spring member sleeved on the positioning rod, and two ends of the spring member are respectively in contact with the first limiting portion and the second limiting portion.

[0022] In one embodiment, an abutment portion is provided at one end of the positioning hole away from the accommodating cavity;

[0023] The positioning rod is provided with a limit pin extending outward;

[0024] When the positioning structure is in the retracted position, the limiting pin abuts against the abutting portion under the self-rotation of the positioning rod.

[0025] In one embodiment, a through hole is provided on the positioning rod, and the limiting pin is inserted into the through hole.

[0026] In one embodiment, the seat body includes a positioning seat and a measuring seat, and the positioning seat is detachably connected to the measuring seat;

[0027] The measuring seat is provided with a part of the accommodating cavity, the measuring hole cavity and the positioning hole cavity;

[0028] The positioning seat is provided with the other part of the positioning hole cavity, and a first limiting portion is provided in the positioning seat.

[0029] In one embodiment, the measuring structure includes a micrometer screw, a fixed sleeve and a differential cylinder. Among them, one end of the micrometer screw is movably arranged in the measuring hole cavity;

[0030] The fixed sleeve is fixed on the peripheral side of the seat body and sleeved on the periphery of the other end of the micrometer screw, and a fixed scale is provided on the fixed sleeve;

[0031] The differential cylinder is sleeved on the periphery of the fixed sleeve and is threadedly connected to the other end of the micrometer screw, and a movable scale is provided on the differential cylinder. Description of the Drawings

[0032] The following further describes in detail the specific embodiments of the present invention with reference to the drawings, wherein:

[0033] Figure 1 It is a schematic diagram of a conventional measuring tool combination of the prior art;

[0034] Figure 2 It is a schematic diagram of the keyway symmetry detection measuring tool of the present invention; (the positioning structure is in the retracted position)

[0035] Figure 3 It is a measuring schematic diagram of the keyway symmetry detection measuring tool of the present invention;

[0036] Figure 4 It is a measuring schematic diagram of the keyway symmetry detection measuring tool of the present invention;

[0037] Figure 5 It is a position schematic diagram of the limiting pin and the abutting portion of the present invention;

[0038] Figure 6 It is a position schematic diagram of the limiting pin and the abutting portion of the present invention.

[0039] Description of the reference numerals in the drawings:

[0040] 10 body, 101 positioning seat, 102 measuring seat, 110 accommodating cavity, 120 positioning hole cavity, 121 first limiting portion, 122 abutting portion, 130 measuring hole cavity, 20 positioning structure, 210 positioning rod, 211 positioning end, 212 holding end, 213 second limiting portion, 220 spring member, 230 limiting pin, 30 measuring structure, 310 micrometer screw, 320 fixed sleeve, 330 thimble, 40 workpiece, 410 keyway. Detailed implementation manners

[0041] The preferred embodiments of the present utility model will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are only for the purpose of illustrating and explaining the present utility model, and are not used to limit the present utility model.

[0042] In order to better elaborate the present utility model, the present utility model will be further described in detail below with reference to the accompanying drawings.

[0043] It should be clear that the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope protected by the embodiments of the present application.

[0044] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the embodiments of the present application. The singular forms "a", "the" and "said" used in the embodiments of the present application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0045] When the following description refers to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all the embodiments consistent with the present application. On the contrary, they are only examples of devices and methods consistent with some aspects of the present application as detailed in the appended claims. In the description of the present application, it should be understood that the terms "first", "second", "third", etc. are only used to distinguish similar objects, and do not have to be used to describe a specific order or sequence, nor can they be understood as indicating or implying relative importance. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0046] In addition, in the description of the present application, unless otherwise specified, "a plurality of" means two or more. "And / or" describes the association relationship of associated objects and indicates that there can be three relationships. For example, A and / or B can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone. The character " / " generally represents an "or" relationship between the front and rear associated objects.

[0047] In the conventional measuring tool combination detection method in the prior art, it is necessary to use a height gauge, a V-block, and a flat plate as shown in Figure 1 First, place the workpiece in the V-groove of the V-block, adjust the keyway to a horizontally symmetric position. During this period, continuously use the height gauge to measure the heights between the left keyway sidewall 1, the right keyway sidewall 1 and the flat plate respectively, and make the distances between them and the flat plate equal, that is, ensure that the left keyway sidewall 1 and the right keyway sidewall 1 are parallel to the flat plate, and repeat the leveling of the keyway sidewalls.

[0048] After the leveling is completed, use the height gauge to measure the heights from the left keyway sidewall 1 and the right keyway sidewall 1 to the flat plate, and record the height data a; rotate the workpiece 180° on the V-block to make the other side of the two keyways flip to the position of the current sidewall 1, and make the left keyway sidewall 2 and the right keyway sidewall 2 coplanar and parallel to the flat plate. During adjustment, repeat the above actions to ensure that the distances between the sidewalls 2 of the left and right keyways and the flat plate are equal. After the sidewall 2 is parallel to the flat plate, use the height gauge to measure the heights from the left keyway sidewall 2 and the right keyway sidewall 2 to the flat plate, and record the height data b. At this time, half of the absolute value of the difference between a and b is the symmetry deviation of the double keyway relative to the cylindrical reference axis.

[0049] Embodiment 1

[0050] Combined with Figures 2 to 5 As shown in

[0051] As Figure 2As shown, the present application abandons the conventional measuring tool combination detection method in the prior art and innovatively proposes a keyway symmetry detection measuring tool with a new structure. Only need to place the workpiece 40 into the accommodation cavity 110, then use the positioning structure 20 to insert into the keyway 410 to determine the position of the workpiece 40 in the accommodation cavity 110. Finally, the measuring structure 30 moves along the axial direction of the measuring hole cavity 130 in the measuring hole cavity 130 to measure the distance between the surface of the workpiece 40 and a preset point and perform calculations to obtain the symmetry deviation of the double keyway 410 relative to the cylindrical reference axis.

[0052] In this embodiment, the number of the positioning hole cavities 120 is two, and the two positioning hole cavities 120 are circumferentially spaced 180°; the number of the positioning structures 20 is correspondingly two; the number of the measuring hole cavities 130 is two, and the two measuring hole cavities 130 are circumferentially spaced 180°; the number of the measuring structures 30 is correspondingly two.

[0053] As Figure 3 and Figure 4 shown, the two positioning structures 20 make a stretching movement into the accommodation cavity 110 along the axial direction of the positioning hole cavity 120 in the positioning hole cavity 120, and use the positioning structure 20 to stretch into the keyway 410 of the workpiece 40 for positioning to determine the position of the workpiece 40 in the accommodation cavity 110;

[0054] Subsequently, as Figure 3 shown, first use one of the two measuring structures 30 (for example, the upper measuring structure 30) to make a stretching movement into the accommodation cavity 110 along the axial direction of the measuring hole cavity 130 (upper measuring hole cavity 130) in the measuring hole cavity 130 until the measuring structure 30 contacts and abuts against the surface of the workpiece 40; wherein, when the measuring structure 30 makes a stretching movement and contacts the workpiece 40, the workpiece 40 will move downward under the pushing action of the measuring structure 30. While moving downward, one end of the positioning structure 20 that stretches into the keyway 410 will abut against the upper side surface of the keyway 410. At this time, the measuring structure 30 can no longer stretch in, measure the distance between the end of the current measuring structure 30 in contact with the workpiece 40 and the preset point and record it, and record the height data a;

[0055] Then as Figure 5As shown, the upper measuring structure 30 retracts into the measuring hole cavity 130, and the lower measuring structure 30 moves axially into the accommodating cavity 110 in the measuring hole cavity 130 (lower measuring hole cavity 130) until the measuring structure 30 contacts and abuts against the surface of the workpiece 40. Among them, when the measuring structure 30 moves in and contacts the workpiece 40, the workpiece 40 will move upward under the pushing action of the measuring structure 30. While moving upward, one end of the positioning structure 20 extending into the keyway 410 will abut against the lower side surface of the keyway 410. At this time, the measuring structure 30 can no longer extend in. Measure the distance between the end of the current measuring structure 30 in contact with the workpiece 40 and the preset point and record it, and record the height data b. Finally, calculate the symmetry deviation of the double keyway 410 relative to the cylindrical reference axis.

[0056] It should be noted that generally, the end of the measuring structure 30 close to the accommodating cavity 110 will not extend into the accommodating cavity 110 to avoid interference and collision with the workpiece 40. In addition, for the convenience of data recording, the preset point mentioned above is the zero point.

[0057] Furthermore, the positioning structure 20 has an extended position and a retracted position relative to the positioning hole cavity 120; as Figure 3 shown, when the positioning structure 20 is in the extended position, the positioning end 211 of the positioning structure 20 extends into the keyway 410 of the workpiece 40 in the accommodating cavity 110; as Figure 2 shown, when the positioning structure 20 is in the retracted position, the positioning end 211 of the positioning structure 20 retracts into the positioning hole cavity 120. Through the above method in this embodiment, the positioning end 211 of the positioning structure 20 can retract into the positioning hole cavity 120 to avoid collision and interference with the positioning structure 20 when the workpiece 40 is placed into the accommodating cavity 110.

[0058] Furthermore, the positioning structure 20 includes a positioning rod 210. The positioning rod 210 is provided with the positioning end 211 and a holding end 212. The holding end 212 is located outside the positioning hole cavity 120 so that when an operator operates, he can control the positioning rod 210 to move axially in the measuring hole cavity 130 by grasping the holding end 212, so as to switch the positioning structure 20 between the extended position and the retracted position.

[0059] Further, a first limiting portion 121 extending inward is provided in the positioning hole cavity 120; a second limiting portion 213 extending outward is provided on the positioning rod 210; the positioning structure 20 further includes a spring member 220 sleeved on the positioning rod 210, and two ends of the spring member 220 respectively abut against the first limiting portion 121 and the second limiting portion 213. In this embodiment, due to the elastic acting force of the spring member 220, when the positioning structure 20 is in the retracted position, the positioning end 211 of the positioning structure 20 retracts into the positioning hole cavity 120, and the spring member 220 is in a compressed state, accumulating elastic potential energy; and when the positioning structure 20 switches to the inserted position, the spring member 220 will drive the positioning end 211 of the positioning structure 20 to extend into the keyway 410 of the workpiece 40 in the receiving cavity 110, omitting the action of the operator to push, and the elastic acting force of the spring member 220 can press the positioning end 211 against the keyway 410 to determine the position of the workpiece 40 in the receiving cavity 110.

[0060] Combined Figures 2 to 6 As shown, in order to facilitate the operator to place the workpiece 40 into the receiving cavity 110, further, a top abutting portion 122 is provided at one end of the positioning hole cavity 120 away from the receiving cavity 110; the positioning rod 210 is provided with a limiting pin 230 extending outward; when the positioning structure 20 is in the retracted position, the limiting pin 230 abuts against the top abutting portion 122 under the self-rotation action of the positioning rod 210. The operator pulls the positioning structure 20 to the retracted position, pulls the limiting pin 230 out of the positioning hole cavity 120, rotates the positioning rod 210 to make the limiting pin 230 abut against the top abutting portion 122, and is clamped on the outer edge of the seat body 10. The two positioning structures 20 are operated in the above manner so that the operator can free both hands to place the workpiece 40 into the receiving cavity 110.

[0061] Further, a through hole is provided on the positioning rod 210, and the limiting pin 230 is inserted into the through hole, which is convenient for assembling the limiting pin 230 onto the positioning rod 210.

[0062] In order to facilitate the machining and manufacturing of the seat body 10 and the assembly of the seat body 10 and the positioning structure 20, further, the seat body 10 includes a positioning seat 101 and a measuring seat 102, and the positioning seat 101 is detachably connected to the measuring seat 102; the measuring seat 102 is provided with a part of the accommodating cavity 110, the measuring hole cavity 130, and the positioning hole cavity 120; the positioning seat 101 is provided with the other part of the positioning hole cavity 120, and a first limiting portion 121 is arranged in the positioning seat 101. The operator can first place the positioning rod 210 into the positioning seat 101, abut the two ends of the spring member 220 against the first limiting portion 121 and the second limiting portion 213 respectively, and then connect and fix the positioning seat 101 and the measuring seat 102. Through the above assembly operation, the positioning rod 210 can be prevented from being inserted into the positioning hole cavity 120 from the accommodating cavity 110, which is convenient for assembly; in addition, the positioning hole cavity 120 is processed in two sections, with a part located in the measuring seat 102 and the other part located in the positioning seat 101, so as to process the first limiting portion 121 in the positioning seat 101.

[0063] Preferably, the positioning seat 101 and the measuring seat 102 are connected and fixed by bolts.

[0064] Further, the measuring structure 30 includes a micrometer screw 310, a fixed sleeve 320, and a thimble 330. Among them, one end of the micrometer screw 310 is movably arranged in the measuring hole cavity 130; the fixed sleeve 320 is fixed on the peripheral side of the seat body 10 and sleeved on the periphery of the other end of the micrometer screw 310, and a fixed scale is arranged on the fixed sleeve 320; the thimble 330 is sleeved on the periphery of the fixed sleeve 320 and is threadedly connected to the other end of the micrometer screw 310, and a movable scale is arranged on the thimble 330. In this embodiment, by rotating the thimble 330, the micrometer screw 310 is driven to rotate, so that the micrometer screw 310 moves in the measuring hole cavity 130 and along the axial direction of the measuring hole cavity 130. During the movement of the micrometer screw 310, the fixed scale and the movable scale both change accordingly. When the micrometer screw 310 contacts the workpiece 40 and can no longer move, the corresponding fixed scale and movable scale are the distance between the current surface of the workpiece 40 and the preset point.

[0065] It should be noted that the working principle of the above measuring structure 30 can refer to the working principle of a micrometer.

[0066] Regarding the structural configuration of the measurement structure 30, in other embodiments, the measurement structure 30 includes a telescopic rod and a fixed tube. Among them, one end of the telescopic rod is movably disposed in the measurement hole cavity 130, and a scale is provided on the telescopic rod; the fixed tube is fixed on the peripheral side of the base body 10 and sleeved around the other end of the telescopic rod. In this embodiment, by performing telescopic operations on the telescopic rod, the telescopic rod can move in the measurement hole cavity 130 and along the axial direction of the measurement hole cavity 130. During the movement of the telescopic rod, the scale changes accordingly. When the telescopic rod contacts the workpiece 40 and can no longer move, the corresponding scale is the distance between the current surface of the workpiece 40 and the preset point.

[0067] The usage process of a keyway symmetry detection measuring tool according to an embodiment is as follows:

[0068] 1. As Figure 2 shown, hold the gripping ends 212 of the two positioning rods 210 and pull out the positioning rods 210, so that the limit pins 230 are pulled out of the positioning seat 101;

[0069] 2. Rotate the positioning rods 210 so that the limit pins 230 abut against the abutting portion 122 and are clamped on the outer edge of the base body 10. The two positioning structures 20 are operated in the above manner, so that the operator can free both hands to put the workpiece 40 into the receiving cavity 110; meanwhile, the positioning ends 211 of the positioning rods 210 are located in the positioning hole cavity 120 to avoid interfering with the workpiece 40 to be placed in the receiving cavity 110;

[0070] 3. Put the workpiece 40 within the measurement range into the receiving cavity 110, and align the keyway 410 with the two positioning hole cavities 120;

[0071] 4. Rotate the positioning rods 210 in the reverse direction, so that the two positioning rods 210 on both sides are pressed into the keyway 410 of the workpiece 40 to be measured under the elastic force of the spring members 220;

[0072] 5. As Figure 3 shown, perform a rotation operation on the differential cylinder 330 of the upper measurement structure 30, so that the micrometer screw 310 presses against the outer cylindrical surface of the workpiece 40 to be measured, and the positioning end 211 of the positioning rod 210 abuts tightly against one side of the keyway 410 of the workpiece 40 to be measured; read the reading a of the upper measurement structure 30 as the height data a;

[0073] 6. Perform a reverse rotation operation on the differential cylinder 330, so that the micrometer screw 310 retracts into the measurement hole cavity 130;

[0074] 7. As Figure 4Perform a rotation operation on the thimble 330 of the lower measuring structure 30 as shown, so that the micrometer screw 310 presses against the outer cylindrical surface of the workpiece 40 to be measured, and the positioning end 211 of the positioning rod 210 closely adheres to the other side of the keyway 410 of the workpiece 40 to be measured; read the reading b of the lower measuring structure 30 as the height data b.

[0075] 8. Calculate half of the absolute value of the difference between a and b, which is the symmetry deviation of the double keyway 410 relative to the cylindrical reference axis.

[0076] In this embodiment, the workpiece 40 is detected by the keyway symmetry detection tool with the above structure, eliminating detection components such as height gauges or dial indicators, gauge blocks, V-shaped irons, and flat plates. It also eliminates the repeated leveling of the side walls of the keyway 410 during measurement and the process of flipping 180° for measurement, improving the detection efficiency and accuracy. After testing, the keyway symmetry detection tool can quickly and accurately measure the symmetry of the double keyway 410.

[0077] Embodiment 2

[0078] This embodiment is basically the same as Embodiment 1, except that in this embodiment, the number of the positioning hole cavities 120 is two, and the two positioning hole cavities 120 are circumferentially spaced 180° apart; the number of the positioning structures 20 is correspondingly two; the number of the measuring hole cavities 130 is one; the number of the measuring structures 30 is correspondingly one. After the measurement of the height data a is completed in this embodiment, the workpiece 40 needs to be taken out and rotated 180°, and then the height data b is measured.

[0079] According to the disclosure and teaching of the above specification, those skilled in the art of the present invention can also make changes and modifications to the above embodiments. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some modifications and changes to the present invention should also fall within the protection scope of the claims of the present invention. In addition, although some specific terms are used in this specification, these terms are only for convenience of description and do not constitute any limitation to the present invention.

Claims

1. A keyway symmetry detection measuring tool, characterized in that include: A seat body is provided with a receiving cavity; a positioning hole cavity and a measuring hole cavity are provided on the circumferential side of the seat body, the positioning hole cavity and the measuring hole cavity are both connected to the receiving cavity, and the positioning hole cavity and the measuring hole cavity are arranged at a 90° interval in the circumferential direction; A positioning structure, which is disposed in the positioning hole and moves along the axial direction of the positioning hole, and is used to determine the position of the workpiece in the accommodating cavity; The measuring structure is arranged in the measuring cavity and moves along the axial direction of the measuring cavity, and is used for measuring the distance between the workpiece surface and a preset point.

2. The keyway symmetry measuring tool according to claim 1, characterized in that: The number of the positioning holes is two, and the two positioning holes are arranged 180° apart in the circumferential direction; the number of the positioning structures is correspondingly two; The number of the measuring cavities is two, and the two measuring cavities are arranged circumferentially at an interval of 180°; the number of the measuring structures is correspondingly two.

3. The keyway symmetry detection tool according to claim 1, characterized in that: The number of the positioning holes is two, and the two positioning holes are arranged 180° apart in the circumferential direction; the number of the positioning structures is correspondingly two; The number of the measuring cavities is one; the number of the measuring structures is correspondingly one.

4. The keyway symmetry measuring tool according to any one of claims 1 to 3, characterized in that: The positioning structure has an extended position and a retracted position relative to the positioning hole; When the positioning structure is in the extended position, the positioning end of the positioning structure extends into the keyway of the workpiece in the accommodating cavity; When the positioning structure is in the retracted position, the positioning end of the positioning structure retracts into the positioning hole.

5. The keyway symmetry detection tool according to claim 4, characterized in that: The positioning structure comprises a positioning rod, the positioning rod is provided with the positioning end and a holding end, and the holding end is located outside the positioning hole.

6. The keyway symmetry measuring tool according to claim 5, characterized in that: A first limiting portion extending inward is provided in the positioning hole cavity; The positioning rod is provided with a second limiting portion extending outward; The positioning structure further includes a spring member sleeved on the positioning rod, and two ends of the spring member are respectively in contact with the first limiting portion and the second limiting portion.

7. The keyway symmetry measuring tool according to claim 6, characterized in that: An abutment portion is provided at one end of the positioning hole away from the accommodating cavity; The positioning rod is provided with a limit pin extending outward; When the positioning structure is in the retracted position, the limiting pin abuts against the abutting portion under the rotation of the positioning rod.

8. The keyway symmetry measuring tool according to claim 7, characterized in that: The positioning rod is provided with a through hole, and the limiting pin is inserted in the through hole.

9. The keyway symmetry measuring tool according to claim 6, characterized in that: The seat body comprises a positioning seat and a measuring seat, and the positioning seat is detachably connected to the measuring seat; The measuring seat is provided with the accommodating cavity, the measuring hole cavity and a part of the positioning hole cavity; The positioning seat is provided with the other part of the positioning hole cavity, and the first limiting part is arranged in the positioning seat.

10. The keyway symmetry detection measuring tool according to any one of claims 1 to 3, characterized in that: The measuring structure includes a micrometer screw, a fixed sleeve, and a differential cylinder, wherein, One end of the micrometer screw is movably arranged in the measuring hole cavity; The fixed sleeve is fixed on the peripheral side of the seat body and sleeved on the periphery of the other end of the micrometer screw, and a fixed scale is arranged on the fixed sleeve; The differential cylinder is sleeved on the periphery of the fixed sleeve and is in threaded connection with the other end of the micrometer screw, and a movable scale is arranged on the differential cylinder.

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