A expansion mandrel, radial calibration device and radial calibration method for precision measurement

Abstract

The present invention belongs to the technical field of precision positioning fixtures, and in particular, relates to an expansion mandrel, a radial calibration device and a radial calibration method for precision measurement. The expansion mandrel comprises: a mandrel pull rod and an internal expansion sleeve sleeved on the outside of the mandrel pull rod, the internal expansion sleeve is provided with a sleeve adjustment structure corresponding to the pull rod adjustment structure, and a hollow petal structure is provided corresponding to the expansion adjustment structure. The sleeve adjustment structure is connected to the pull rod adjustment structure through an axial adjustment component. The radial calibration device comprises: a fixed ring coincident with the central axis of a thin-walled cylinder and a straight-in type micrometer head installed on the fixed ring through a supporting structure, the measuring rod of the straight-in type micrometer head is connected to the expansion mandrel through a special chuck, and the inner wall of the thin-walled cylinder is expanded and tightened through the expansion mandrel. The expansion mandrel can adjust its own volume, eliminate assembly gaps, and can adapt to changes in the length of workpieces to improve test accuracy; the device can improve test accuracy, efficiency and ease of operation.

Description

Technical Field

[0001] The invention belongs to the technical field of precision positioning fixtures, and in particular relates to an expansion-type core shaft, a radial calibration device and a radial calibration method for precision measurement. Background Art

[0002] A large number of thin-walled cylindrical workpieces on the inspection line need to be placed on a special inspection table one by one, and the radial runout at a certain point is measured non-contactly. The radial runout value at that point is used as the standard for judging whether the workpiece is qualified. The sensor used for online measurement of the radial runout of the workpiece on the special inspection table is a non-contact eddy current sensor. Before the workpiece is measured, the sensor needs to be calibrated.

[0003] During calibration, the lower end of the special mandrel needs to be inserted into the open part of the workpiece. The displacement measuring mechanism pushes the upper end of the special mandrel to drive the workpiece to move in a straight line. By adjusting the distance between the workpiece and the eddy current sensor, the mathematical correspondence between the output of its electrical parameters and the displacement value is determined.

[0004] At present, the following main problems exist when the existing calibration device performs calibration operations on sensors:

[0005] Problem 1: At present, the special mandrel in the calibration device is a stepped shaft structure, and there is a gap between the mandrel and the inner diameter of the workpiece, causing random errors;

[0006] Problem 2: The center height of the displacement measuring rod is fixed and cannot adapt to the length change of the workpiece (within the tolerance range specified in the drawing), and it is easy to get stuck during operation;

[0007] Question 3: The motion trajectory of the linear micrometer head does not coincide with the axis of the sensor being measured, and there is randomness in each installation, resulting in systematic errors and random errors.

[0008] Obviously, the special spindle in the calibration device currently used cannot eliminate the gap and cannot adapt to the change of workpiece length; the calibration device currently used has obvious accuracy errors and is inconvenient to operate, which can easily cause misjudgment of the workpiece, affecting the test accuracy and efficiency, and can no longer meet the requirements of online workpiece detection. Summary of the invention

[0009] In order to solve the problems existing in the above-mentioned prior art, the present invention designs an expansion mandrel for precision measurement and a device for on-site calibration of a radial vibration sensor for a thin-walled cylinder. The expansion mandrel can adjust its own volume, eliminate assembly gaps, and can adapt to changes in workpiece length to improve test accuracy; the device can improve test accuracy, efficiency and operational convenience.

[0010] The technical solution adopted by the present invention to solve this problem is:

[0011] An expansion mandrel for precision measurement, comprising:

[0012] The mandrel pull rod comprises a pull rod connection structure, a pull rod adjustment structure, a pull rod connection structure and a tension adjustment structure which are connected in sequence;

[0013] The internal expansion sleeve is sleeved on the outside of the core shaft pull rod. The internal expansion sleeve is provided with a sleeve adjustment structure at the position corresponding to the pull rod adjustment structure, and a hollow petal structure is provided at the position corresponding to the expansion adjustment structure. The sleeve adjustment structure is connected to the pull rod adjustment structure through an axial adjustment component. When the core shaft pull rod is adjusted to slide axially relative to the internal expansion sleeve through the axial adjustment component, the hollow petal structure is converted between a free state and an expansion state.

[0014] Preferably, it further comprises a sleeve assembly connected to the pull rod connection structure, the sleeve assembly is provided with an insertion side hole for assembling the displacement measuring mechanism, the pull rod connection structure is inserted into the sleeve assembly and can slide up and down along the sleeve assembly.

[0015] Further preferably, the sliding sleeve assembly includes a pressure cover structure and a guide sleeve structure that are interference-fitted together, and both the pressure cover structure and the guide sleeve structure are provided with insertion side holes for assembling the displacement measuring mechanism, and the pressure cover structure is provided with a knurled screw for locking and fixing the displacement measuring mechanism, and the pull rod connecting structure is inserted in the guide sleeve structure and can slide up and down along the guide sleeve structure.

[0016] Further preferably, the pull rod connection structure is further provided with an annular groove, an elastic retaining ring is sleeved on the annular groove, the pull rod adjustment structure is provided with a threaded adjustment section, and the expansion adjustment structure is a conical structure.

[0017] Further preferably, the ferrule adjustment structure is arranged at one side end of the internal expansion ferrule, and the ferrule adjustment structure includes at least one circle of annular hook ring opened on the outer wall of the end of the internal expansion ferrule.

[0018] Further preferably, the axial adjustment assembly comprises:

[0019] A lock nut structure, which is threadedly connected to the threaded adjustment section;

[0020] A hanging ring structure, which is hooked on the annular hook ring, and the hanging ring structure includes two half-ring structures with openings facing each other;

[0021] Further preferably, the two half-ring structures relatively press the outer end surface of the lock nut structure and fix the two half-ring structures to the lock nut structure by screws, thereby clamping the lock nut structure and the internal expansion sleeve together.

[0022] Further preferably, the hollow petal structure is arranged at the other side end of the internal expansion sleeve, and the hollow petal structure includes a tightening body, which is a hollow cylindrical structure with a certain elasticity and a diameter larger than the internal expansion sleeve. The tightening body is divided into a plurality of petal bodies by radially arranged petal seams, and a hollow expansion cone surface is formed in the inner hole of the expansion body. When the core shaft pull rod slides upward axially relative to the internal expansion sleeve, the conical structure slides upward axially relative to the hollow expansion cone surface, and each petal body expands outward.

[0023] The second invention object of the present invention is to provide a radial calibration device for a thin-walled cylinder, comprising:

[0024] A fixing ring, which coincides with the central axis of the thin-walled cylinder, and the fixing ring is provided with a radial vibration sensor for calibration, and an eddy current sensor is preferably selected;

[0025] The displacement measuring mechanism comprises a straight-in differential head, which is mounted on a fixed ring via a supporting structure; a measuring rod of the straight-in differential head is connected to an expansion mandrel via a special chuck; the inner wall of a thin-walled cylinder is expanded via the expansion mandrel; the motion trajectory of the thin-walled cylinder driven by the straight-in differential head coincides with the central axis of a radial vibration sensor.

[0026] Further preferably, the support structure comprises:

[0027] A base, which is fixed on the fixing ring by fixing screws, and the base is provided with a plurality of mounting holes;

[0028] The support seat has a positioning hole at the upper end for assembling the straight-in type micrometer head, and a support rod at the lower end for fitting and inserting in the installation hole.

[0029] Further preferably, the base is an arc-shaped block structure having the same diameter as the fixing ring.

[0030] The third invention object of the present invention is to provide a radial calibration method for a thin-walled cylinder, comprising the following steps:

[0031] S101: Assembling the expansion mandrel

[0032] First, put the inner expansion sleeve on the outside of the mandrel pull rod, then clamp the lock nut structure and the inner expansion sleeve together through the axial adjustment component, then insert the pull rod connection structure of the mandrel pull rod into the guide sleeve structure of the sliding sleeve assembly, and finally insert the lower end of the expansion mandrel into the opening of the thin-walled cylinder to expand the inner wall of the thin-walled cylinder;

[0033] S102: Assembling the displacement measurement mechanism

[0034] First, install the base on the fixing ring with the fixing screws, then insert the support seat into the mounting hole of the base, then insert the straight-in micrometer head into the positioning hole of the support seat and fix it with screws, and finally insert the measuring rod of the straight-in micrometer head into the center hole of the special chuck and lock it with a nut;

[0035] S103: Assembly between displacement measuring mechanism and expansion mandrel

[0036] Insert the special chuck into the insertion side hole of the sliding sleeve assembly at the upper end of the expansion mandrel, and lock it with a knurled screw to ensure that the central axis of the thin-walled cylinder coincides with the central axis of the fixed ring, and the motion trajectory of the thin-walled cylinder driven by the linear differential head coincides with the central axis of the sensor;

[0037] S104: Calibration work

[0038] After all the parts are assembled, the measuring rod of the linear micrometer head is moved to push the expansion mandrel to move the thin-walled cylinder, adjust the distance between the thin-walled cylinder and the radial vibration sensor, and perform calibration.

[0039] The advantages and positive effects of the present invention are:

[0040] 1. In the present invention, the expansion function of the core shaft and the inner wall of the workpiece is realized by the relative movement between the core shaft pull rod and the internal expansion sleeve, thereby eliminating the gap between the core shaft and the inner wall of the workpiece. The radial calibration device utilizes the hollow petal structure at the lower end of the expansion core shaft to expand from the inside of the workpiece, thereby eliminating the gap between the core shaft and the inner diameter of the workpiece, which can effectively avoid random errors caused by the existence of the gap and improve the test accuracy.

[0041] 2. In the present invention, there is space in the guide sleeve structure for the expansion mandrel to move axially, and the center height of the measuring rod can adapt to the length change of the workpiece. The radial calibration device uses the movable sleeve assembly at the upper end of the expansion mandrel to automatically adjust the height between the linear micrometer head and the workpiece, adapt to the length change of the workpiece, prevent jamming, and improve the test accuracy.

[0042] 3. In the present invention, an arc-shaped base is used to arrange the straight-in type micrometer head on a concentric circle coaxial with the workpiece, and the straight-in type micrometer head can swing freely left and right, and the position of the straight-in type micrometer head can be automatically adjusted to ensure that the movement trajectory of its measuring rod coincides with the axis of the sensor being measured, which can improve the test accuracy, efficiency and operational convenience. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The technical solution of the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments, but it should be understood that these drawings are designed only for explanation purposes and are not intended to limit the scope of the present invention. In addition, unless otherwise specified, these drawings are intended only to conceptually illustrate the structural configurations described herein and are not necessarily drawn to scale.

[0044] Figure 1 is a schematic structural diagram of a radial calibration device for a thin-walled cylinder provided in Example 2;

[0045] Figure 2 is a schematic diagram of a top view of a radial calibration device for a thin-walled cylinder provided in Example 3;

[0046] Figure 3 is a schematic structural diagram of the base in Example 2;

[0047] Figure 4 is a schematic structural diagram of the support seat in Example 2;

[0048] Figure 5 is a schematic diagram of the structure of the straight-in type micrometer head in Example 2;

[0049] Figure 6 is a schematic structural diagram of an expansion type mandrel for precision measurement provided in Example 1;

[0050] Figure 7 yes Figure 6 Side view of

[0051] Figure 8 is a schematic structural diagram of the gland structure in Example 1;

[0052] Fig. 9 is a structural schematic diagram of the guide sleeve structure in Example 1;

[0053] Fig.10 is a structural schematic diagram of the lock nut structure in Example 1;

[0054] Fig.11 is a schematic structural diagram of the hanging ring structure in Example 1;

[0055] Fig.12 is a schematic structural diagram of the mandrel pull rod in Example 1;

[0056] Fig.13 It is a schematic diagram of the structure of the internal expansion sleeve in Example 1.

[0057] In the figure: 1- straight-in type micrometer head; 2- support seat; 3- special chuck; 4- expansion type mandrel; 401- gland structure; 402- guide sleeve structure; 403- mandrel pull rod; 4031- pull rod connection structure; 4032- pull rod adjustment structure; 4033- pull rod connection structure; 4034- expansion adjustment structure; 404- lock nut structure; 405- semi-ring structure; 406- internal expansion sleeve; 4061- ring shaped hook ring; 4062-petal body; 4063-inner hole; 407-knurled screw; 408-elastic retaining ring; 409-screw hole; 4010-side hole A; 4011-guide sleeve hole; 4012-side hole B; 5-eddy current sensor; 6-thin-walled cylinder; 7-fixing ring; 8-base; 9-positioning screw; 10-mounting hole; 11-clamping hole; 12-support rod; 13-measuring rod; 14-positioning hole. DETAILED DESCRIPTION

[0058] First of all, it should be noted that the specific structure, features and advantages of the present invention will be specifically described below by way of example, but all descriptions are only for illustration and should not be understood as limiting the present invention in any way. In addition, any single technical feature described or implied in the embodiments mentioned herein, or any single technical feature displayed or implied in the drawings, can still be combined or deleted between these technical features (or their equivalents) to obtain more other embodiments of the present invention that may not be directly mentioned in this document. In addition, in order to simplify the drawings, the same or similar technical features may be marked only in one place in the same drawing.

[0059] In the present invention, unless otherwise clearly specified and limited, the terms "installation", "setting", "connection", "fixation", "screwing" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined, for ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances. The present invention is described in detail below with reference to the accompanying drawings.

[0060] Embodiment 1:

[0061] A tightening mandrel for precision measurement, comprising: a mandrel rod 403, which comprises a rod connection structure 4031, a rod adjustment structure 4032, a rod connection structure 4033 and an expansion adjustment structure 4034 connected in sequence; an internal expansion sleeve 406, which is sleeved on the outside of the mandrel rod 403, the internal expansion sleeve 406 is provided with a sleeve adjustment structure at a position corresponding to the rod adjustment structure, and a hollow petal structure at a position corresponding to the expansion adjustment structure, the sleeve adjustment structure is connected to the rod adjustment structure 4032 through an axial adjustment component, and when the mandrel rod 403 is adjusted by the axial adjustment component to produce axial sliding relative to the internal expansion sleeve 406, the hollow petal structure switches between a free state and an expansion state.

[0062] In this embodiment, when the expansion mandrel is assembled, the internal expansion sleeve 306 is sleeved on the outside of the mandrel rod 304. The relative movement between the mandrel rod 403 and the internal expansion sleeve 406 can be adjusted by operating the axial adjustment component. The relative movement between the mandrel rod 403 and the internal expansion sleeve 406 can realize the conversion of the hollow petal structure between the free state and the expansion state. When the lower end of the expansion mandrel 4 is inserted into the open part of the workpiece (such as the thin-walled cylinder 6), the volume of the hollow petal structure can be adjusted by operating the axial adjustment component to realize the expansion function of the expansion mandrel and the inner wall of the workpiece, thereby eliminating the gap between the mandrel and the inner wall of the workpiece, which can effectively avoid the random error caused by the existence of the gap.

[0063] Furthermore, it can also be considered in the present embodiment that the expansion core shaft also includes a sliding sleeve assembly connected to the pull rod connecting structure 4031, and the sliding sleeve assembly includes a pressure cover structure 401 and a guide sleeve structure 402 that are interference-fitted together, and the pressure cover structure 401 and the guide sleeve structure 402 are both provided with insertion side holes for assembling the displacement measuring mechanism. Specifically: the insertion side hole includes a side hole A and a side hole B respectively opened on the pressure cover structure 401 and the guide sleeve structure 402, and the pressure cover structure 401 is provided with a screw hole 409, and the screw hole 409 is screwed with a knurled screw 407 for locking and fixing the displacement measuring mechanism.

[0064] Furthermore, in the present embodiment, it can also be considered that the pull rod connecting structure 4031 is inserted into the guide sleeve structure 402 and can slide up and down along the guide sleeve structure 402, and there is a free movement space along the axial direction at the connection between the guide sleeve structure 402 and the pull rod connecting structure 4031. The length of the pull rod connecting structure 4031 inserted in the guide sleeve structure 402 can be appropriately adjusted according to the length of the workpiece. The length of the expansion core shaft can adapt to the change in the length of the workpiece.

[0065] Furthermore, in this embodiment, it can also be considered that Figure 6As shown, the core shaft pull rod 403 includes a pull rod connection structure 4031, a pull rod adjustment structure 4032, a pull rod connection structure 4033 and a tension adjustment structure 4034 which are connected in sequence. The pull rod connection structure 4031, the pull rod adjustment structure 4032 and the pull rod connection structure 4033 are preferably round rod structures. In order to achieve relative movement between the core shaft pull rod 403 and the internal expansion sleeve 406, the pull rod adjustment structure 4032 is provided with a threaded adjustment section.

[0066] Furthermore, in this embodiment, it can also be considered that an annular groove is further provided on the pull rod connection structure 4031, and an elastic retaining ring 408 is sleeved on the annular groove, and the elastic retaining ring 408 serves as a mechanical limit to prevent the component from being disengaged.

[0067] Furthermore, in the present embodiment, it can also be considered that the expansion adjustment structure 4034 is a conical structure, and when relative movement occurs between the core shaft pull rod 403 and the internal expansion sleeve 406, the expansion adjustment structure 4034 can adjust the hollow petal structure corresponding to its position to expand outward or retract.

[0068] Furthermore, in the present embodiment, it can also be considered that the ferrule adjustment structure is arranged at one side end of the internal expansion ferrule 406 , and the ferrule adjustment structure includes at least one circle of annular hook ring 4061 opened on the end outer wall of the internal expansion ferrule 406 .

[0069] Furthermore, in this embodiment, it can also be considered that the axial adjustment assembly includes: a lock nut structure 404, which is threadedly connected to the threaded adjustment section; a hanging ring structure, which is hooked on the annular hook ring 4061, and the hanging ring structure includes two half-ring structures 405 with openings facing each other; the two half-ring structures 405 relatively press the outer end surface of the lock nut structure 404 and fix the two half-ring structures 405 on the lock nut structure 404 by screws, so as to clamp the lock nut structure 404 and the internal expansion sleeve 406 together. The two half-ring structures 405 are two semi-circular ring structures cut from a full circle, and the lock nut structure and the internal expansion sleeve are fixed from the outside, avoiding structural interference caused by the installation of the full circle.

[0070] Furthermore, in the present embodiment, it can be considered that the hollow petal structure is arranged at the other end of the inner expansion sleeve 406, and the inner expansion sleeve 406 is a hollow cylindrical structure with an inner hole 4063 in the middle. The hollow petal structure includes a tightening body, which is a hollow cylindrical structure with a certain elasticity and a diameter larger than the inner expansion sleeve 406. The tightening body is divided into a plurality of petal bodies 4062 by radially provided petal seams, and a hollow expansion cone is formed in the center hole of the tightening body, such as Figure 6As shown, when the core shaft pull rod 3 slides upward axially relative to the internal expansion sleeve 406, the conical structure slides upward axially relative to the hollow expansion cone surface, and each petal body expands outward under the condition of internal force.

[0071] Working principle of embodiment 1: The expansion type mandrel mainly includes a gland structure 401, a guide sleeve structure 402, a mandrel pull rod 403, a lock nut structure 404, two half-ring structures 405, an internal expansion sleeve 406, a knurled screw 407, and an elastic retaining ring 408 for the shaft. Wherein: the gland structure 401 and the guide sleeve structure 402 are interference fit together, the knurled screw 7 is pre-installed on the gland structure 401, the lock nut structure 404 is installed on the threaded adjustment section of the core shaft pull rod 403, the core shaft pull rod 403 is inserted into the inner hole 4063 of the internal expansion sleeve 406, and one end of the two semi-ring structures 405 is hooked on the annular hook ring 4061 at the upper end of the internal expansion sleeve 6, and the other end is fixed to the lock nut structure 404 with screws, so that the lock nut structure 404 and the internal expansion sleeve 406 are clamped together; the shaft elastic retaining ring 408 is installed in the annular groove of the core shaft pull rod 403 as a mechanical limit to prevent the component from being disengaged, and the pull rod connecting structure 4031 at the upper end of the core shaft pull rod 3 is inserted into the guide sleeve hole 4011 of the guide sleeve structure 402, and the expansion core shaft is assembled. When working, the mandrel rod 403 is driven to move axially along the internal expansion sleeve 406 by rotating the lock nut structure 404. When the mandrel rod 403 moves upward, the petals 4062 at the lower end of the internal expansion sleeve 406 change from a free state to a tightened state. When the mandrel rod 403 moves downward, the petals 4062 at the lower end of the internal expansion sleeve 406 return to a free state, thereby realizing the internal tightening function of the mandrel on the thin-walled cylindrical workpiece. In addition, during use, the measuring end of the displacement measuring mechanism is simultaneously inserted into the side hole A4010 of the gland structure 401 and the side hole B4012 of the guide sleeve structure 402, and fixed with a knurled screw 407. Since the guide sleeve structure 402 is mounted on the mandrel rod 403 and has a free moving space, the expansion mandrel with a sliding sleeve assembly can adapt to the length change of the workpiece.

[0072] The expansion mandrel realizes the expansion function between the mandrel and the inner wall of the workpiece through the relative movement between the mandrel pull rod and the inner expansion sleeve, eliminating the gap between the mandrel and the inner wall of the workpiece. At the same time, the guide sleeve structure has space for axial movement, and the center height of the displacement measuring mechanism can adapt to the length change of the workpiece.

[0073] Embodiment 2:

[0074] A radial calibration device for a thin-walled cylinder comprises: a fixed ring 7, which coincides with the central axis of the thin-walled cylinder 6, and the fixed ring 7 is provided with a radial vibration sensor for calibration, and an eddy current sensor 5 is preferably selected; a displacement measuring mechanism, which comprises a straight-in differential head 1, and the straight-in differential head 1 is installed on the fixed ring 7 through a supporting structure, and the measuring rod 13 of the straight-in differential head 1 is connected to the expansion type mandrel 4 through a special chuck 3, and the inner wall of the thin-walled cylinder 6 is expanded by the expansion type mandrel 4 described in Example 1, and the motion trajectory of the thin-walled cylinder 6 driven by the straight-in differential head 1 coincides with the central axis of the eddy current sensor 5.

[0075] In this embodiment, Figure 1-2 As shown, when the device is assembled, the straight-in type micrometer head 1 is installed on the fixed ring 7 through the supporting structure, the measuring rod 13 of the straight-in type micrometer head 1 is connected to the expansion type mandrel 4 through the special chuck 3, the inner wall of the thin-walled cylinder 6 is expanded by the expansion type mandrel 4, and the central axis of the thin-walled cylinder 6 and the fixed ring 7 are made to coincide by adjusting the supporting structure, and the central axis of the straight-in type micrometer head 1, the central axis of the thin-walled cylinder 6, the central axis of the fixed ring 7 and the central axis of the eddy current sensor 5 are located on the same vertical plane. During calibration, the measuring rod 13 of the moving straight-in differential head 1 pushes the expansion core shaft 4 to drive the thin-walled cylinder 6, adjusts the distance between the thin-walled cylinder 6 and the eddy current sensor 5, and performs calibration. In this device, the hollow petal structure at the lower end of the expansion core shaft is used to expand and tighten from the inside of the thin-walled cylinder to eliminate the gap between the core shaft and the thin-walled cylinder; the movable sliding sleeve structure at the upper end of the expansion core shaft is used to automatically adjust the height between the straight-in differential head and the thin-walled cylinder to adapt to the length change of the thin-walled cylinder; the motion trajectory of the thin-walled cylinder 6 driven by the straight-in differential head 1 coincides with the central axis of the eddy current sensor 5, which can improve the test accuracy, efficiency and ease of operation.

[0076] Furthermore, in this embodiment, it can also be considered that the supporting structure includes: a base 8, which is an arc-shaped block structure with the same diameter as the fixing ring 7, and the base 8 is fixed to the fixing ring 7 by fixing screws 9, and a plurality of mounting holes 10 are opened on the base 8; a supporting seat 2, the upper end of which is provided with a positioning hole 14 for assembling the straight-in type micrometer head 1, and a clamping hole 11 for clamping the positioning hole 14, and the lower end of the supporting seat 2 is provided with a supporting rod 12 for adapting and being inserted into the mounting hole 10. In this embodiment, the base 8 is fixed to the fixing ring 7 by fixing screws 9, and a plurality of mounting holes 10 are vertically opened on the base 8 along its arc direction. Taking this embodiment as an example, two mounting holes 10 are opened on the base 8, and the angle between the two mounting holes is α°. The supporting rod 12 at the lower end of the supporting seat 2 can be adapted to be inserted into the mounting hole 10, and the position of the subsequent thin-walled cylinder can be fine-tuned by rotating and adjusting the supporting rod 12 in the mounting hole 10. This supporting structure utilizes an arc-shaped base to arrange the straight-in differential head on a concentric circle coaxial with the thin-walled cylinder, and the straight-in differential head 1 can swing freely left and right, and the position of the straight-in differential head 1 is automatically adjusted to ensure that the motion trajectory of its measuring rod coincides with the axis of the sensor being measured. After the support seat 2 is installed, first insert the straight-in differential head 1 into the positioning hole 14, and then screw the screw into the clamping hole 11 to clamp the positioning hole 14 to fix the position of the straight-in differential head 1. Then, the measuring rod 13 of the straight-in differential head 1 is connected to the expansion mandrel 4 through the special chuck 3, and then the inner wall of the thin-walled cylinder 6 is expanded by the expansion mandrel 4. The support rod is fine-tuned to make the center axis of the thin-walled cylinder 6 coincide with the center axis of the fixing ring 7. At this time, the center axis of the straight-in differential head 1, the center axis of the thin-walled cylinder 6, the center axis of the fixing ring 7 and the center axis of the eddy current sensor 5 are located on the same vertical plane.

[0077] Furthermore, in the present embodiment, it can also be considered that the connection method between the straight-in type micrometer head 1 and the expansion type core shaft 4 is: the measuring rod 13 of the straight-in type micrometer head 1 is inserted into the center hole of the special chuck 3 and locked by the locking nut, and then the special chuck 3 is inserted into the insertion side hole at the upper end of the expansion type core 4 and locked by the knurled screw 407.

[0078] Working principle of embodiment 2: The radial calibration device includes a straight-in differential head 1, a support seat 2, a special chuck 3, an expansion mandrel 4, an eddy current sensor 5, a fixing ring 7, a base 8 and a fixing screw 9. During assembly, the base 8 is mounted on the fixing ring 7 coaxial with the thin-walled cylinder 6 and fixed with the fixing screw 9. The lower end of the expansion mandrel 4 is inserted into the opening of the thin-walled cylinder 6 to expand the inner wall of the thin-walled cylinder 6. The support seat 2 is inserted into the mounting hole 10 of the base 8, the special chuck 3 is inserted into the insertion side hole of the sliding sleeve structure at the upper end of the expansion mandrel 4, the straight-in differential head 1 is inserted into the positioning hole 14 of the support seat 2 and fixed with screws, and the center hole of the special chuck 3 and the locking nut are inserted at the same time. The sliding sleeve structure can slide up and down on the expansion mandrel 4, and the relative position between the straight-in differential head 1 and the thin-walled cylinder 6 is adjusted according to the length change of the thin-walled cylinder 6 to prevent jamming. After all the components are installed, the measuring rod 13 of the linear micrometer head 1 is moved to push the expansion core shaft 4 to drive the thin-walled cylinder 6, and the distance between the thin-walled cylinder 6 and the eddy current sensor 5 is adjusted to perform calibration.

[0079] Embodiment 3:

[0080] Embodiment 3 of the present invention is further improved on the basis of embodiment 2 so as to give full play to the technical advantages of the present invention, and this is explained by way of example below. For example: at least two groups of eddy current sensors 5 are installed on the fixing ring 7 through the sensor mounting structure. Taking this embodiment as an example, two groups of eddy current sensors 5 are installed on the fixing ring 7 through the sensor mounting structure, and the angle α between the two groups of eddy current sensors 5 is α. The straight-in differential head 1 is installed at position A and position B at the same time. The position angle α between position A and position B can be fine-tuned according to the angle α between the two groups of eddy current sensors 5, so as to realize the calibration of the two groups of eddy current sensors 5 on the same basis. This radial calibration device eliminates the gap between the core shaft and the workpiece, can adapt to the length change of the workpiece, and the straight-in differential head 1 drives the workpiece movement trajectory to coincide with the sensor center axis, thereby improving the test accuracy and efficiency.

[0081] Embodiment 4:

[0082] A radial calibration method for a thin-walled cylinder comprises the following steps:

[0083] S101: Assemble the expansion mandrel 4

[0084] First, the inner expansion sleeve 406 is placed on the outside of the mandrel pull rod 403;

[0085] Then, the lock nut structure 404 and the inner expansion sleeve 406 are clamped together through the axial adjustment component. At this time, the two half-ring structures 405 are located outside the pull rod adjustment structure 4032, and the hollow petal structure is located outside the expansion adjustment structure 4034;

[0086] Afterwards, the rod connection structure 4031 of the mandrel rod 403 is inserted into the guide sleeve structure 402 of the sliding sleeve assembly;

[0087] Finally, the lower end of the expansion mandrel 4 is inserted into the opening of the thin-walled cylinder 6, and the inner wall of the thin-walled cylinder 6 is expanded by rotating the lock nut structure 404;

[0088] S102: Assembling the displacement measurement mechanism

[0089] First, install the base 8 on the fixing ring 7 by fixing screws 9;

[0090] Then, the support rod 12 of the support seat 2 is inserted into the mounting hole 10 of the base 8. The mounting hole 10 and the sensor 5 are located on the same radial direction of the fixing ring 7.

[0091] Afterwards, insert the direct-acting micrometer head 1 into the positioning hole 14 of the support seat 2 and fix it with screws;

[0092] Finally, insert the measuring rod 13 of the straight-through micrometer head 1 into the center hole of the special chuck 3 and lock it with a nut;

[0093] S103: Assembly between displacement measuring mechanism and expansion mandrel

[0094] Insert the special chuck 3 into the insertion side hole of the upper end sliding sleeve assembly of the expansion mandrel 4, and lock it with the knurled screw 407 to ensure that the central axis of the thin-walled cylinder 6 coincides with the central axis of the fixing ring 7, and ensure that the motion trajectory of the thin-walled cylinder 6 driven by the linear micrometer head 1 coincides with the central axis of the sensor 5;

[0095] S104: Calibration work

[0096] After all the components are assembled, the measuring rod 13 of the linear micrometer head 1 is moved to push the expansion core shaft 4 to drive the thin-walled cylinder 6 to move, and the distance between the thin-walled cylinder 6 and the eddy current sensor 5 is adjusted to perform calibration.

[0097] The above embodiments describe the present invention in detail, but the contents are only preferred embodiments of the present invention and cannot be considered to limit the scope of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the present invention.

Claims

1. An expansion mandrel for precision measurement, Features: include: A mandrel pull rod (403), comprising a first pull rod connection structure (4031), a pull rod adjustment structure (4032), a second pull rod connection structure (4033) and an expansion adjustment structure (4034) which are connected in sequence; The internal expansion sleeve (406) is sleeved on the outside of the core shaft pull rod (403). The internal expansion sleeve (406) is provided with a sleeve adjustment structure at the position corresponding to the pull rod adjustment structure, and is provided with a hollow petal structure at the position corresponding to the expansion adjustment structure. The sleeve adjustment structure is connected to the pull rod adjustment structure (4032) through an axial adjustment component. When the core shaft pull rod (403) is adjusted by the axial adjustment component to produce axial sliding relative to the internal expansion sleeve (406), the hollow petal structure is converted between a free state and an expansion state.

2. The expansion mandrel for precision measurement according to claim 1, Features: It also includes a sleeve assembly connected to the first pull rod connection structure (4031), the sleeve assembly is provided with an insertion side hole for assembling the displacement measuring mechanism, and the first pull rod connection structure (4031) is inserted into the sleeve assembly and can slide up and down along the sleeve assembly.

3. The expansion mandrel for precision measurement according to claim 2, Features: The pull rod adjustment structure (4032) is provided with a threaded adjustment section, and the expansion adjustment structure (4034) is a conical structure.

4. The expansion mandrel for precision measurement according to claim 3, Features: The ferrule adjustment structure is arranged at one end of the inner expansion ferrule (406), and the ferrule adjustment structure comprises at least one annular hook ring (4061) opened on the outer wall of the end of the inner expansion ferrule (406).

5. The expansion mandrel for precision measurement according to claim 4, Features: The axial adjustment assembly comprises: A lock nut structure (404) is threadedly connected to the threaded adjustment section; A hanging ring structure, which is hooked on the annular hook ring (4061), and the hanging ring structure includes two half-ring structures (405) with openings facing each other; The two semi-ring structures (405) relatively press the outer end surface of the lock nut structure (404) and fix the two semi-ring structures (405) on the lock nut structure (404) by screws.

6. The expansion mandrel for precision measurement according to claim 4, Features: The hollow petal structure is arranged at the other end of the inner expansion sleeve (406), and the hollow petal structure includes an expansion body, which is divided into a plurality of petal bodies (4062) by radially arranged petal seams, and a hollow expansion cone surface is formed in the inner hole of the expansion body.

7. A radial calibration device for thin-walled cylinders, Features: include: A fixing ring (7) which coincides with the central axis of the thin-walled cylinder (6), and a radial vibration sensor for calibration is provided on the fixing ring (7); A displacement measuring mechanism, comprising a straight-in type differential head (1), the straight-in type differential head (1) being mounted on a fixed ring (7) via a supporting structure, the measuring rod (13) of the straight-in type differential head (1) being connected to an expansion mandrel (4) via a special chuck (3), the inner wall of a thin-walled cylinder (6) being expanded by the expansion mandrel (4) as described in any one of claims 2 to 6, the motion trajectory of the thin-walled cylinder (6) driven by the straight-in type differential head (1) coinciding with the central axis of a radial vibration sensor.

8. A radial calibration device for a thin-walled cylinder according to claim 7, Features: The support structure comprises: A base (8) is fixed on the fixing ring (7) by means of fixing screws (9), and a plurality of mounting holes (10) are provided on the base (8); The support seat (2) has a positioning hole (14) at its upper end for assembling the straight-in type micrometer head (1), and a support rod (12) at its lower end for fitting and inserting into the mounting hole (10).

9. A radial calibration device for a thin-walled cylinder according to claim 8, Features: The base (8) is an arc-shaped block structure having the same diameter as the fixing ring (7).

10. A radial calibration method for thin-walled cylinders, Features: The following steps are involved: S101: Assembling the expansion mandrel First, the internal expansion sleeve (406) is sleeved on the outside of the core shaft pull rod (403), and then the lock nut structure (404) and the internal expansion sleeve (406) are clamped together through the axial adjustment component, and then the pull rod connection structure of the core shaft pull rod (403) is inserted into the sliding sleeve component, and finally the lower end of the expansion core shaft (4) is inserted into the opening of the thin-walled cylinder (6) to expand the inner wall of the thin-walled cylinder (6); S102: Assembling the displacement measuring mechanism First, the base (8) is mounted on the fixing ring (7) by means of fixing screws (9), and then the support seat (2) is inserted into the mounting hole (10) of the base (8), and then the direct-type micrometer head (1) is inserted into the positioning hole (14) of the support seat (2) and fixed with screws, and finally the measuring rod (13) of the direct-type micrometer head (1) is inserted into the center hole of the special chuck (3) and locked with a nut; S103: Assembly between displacement measuring mechanism and expansion mandrel Insert the special chuck (3) into the insertion side hole of the upper end sliding sleeve assembly of the expansion core shaft (4), and lock it with a knurled screw (407) to ensure that the central axes of the thin-walled cylinder (6) and the fixed ring (7) coincide with each other, and the motion trajectory of the thin-walled cylinder (6) driven by the linear micrometer head (1) coincides with the central axis of the sensor (5); S104: Calibration work After all the components are assembled, the measuring rod (13) of the linear micrometer head (1) is moved to push the expansion core shaft (4) to drive the thin-walled cylinder (6) to move, and the distance between the thin-walled cylinder (6) and the radial vibration sensor is adjusted to perform calibration.

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