Tetrahedron calibration tool for inertial navigation system and processing technology thereof

Abstract

The present application relates to inertial navigation system calibration tooling technical field, specifically relates to a kind of tetrahedron calibration tooling for inertial navigation system and its processing technology;Tetrahedron calibration tooling includes body skeleton, body skeleton has upper and lower surface, front and back side, outside is equipped with through recess left and right side, eight first non-hole boss, twelve second non-hole boss, twelve hole bosses and internal cavity;The outside of two front and back sides is equipped with non-through recess, the inside of two front and back sides is equipped with circular arc slide, processing technology includes the following steps: rough machining, stability treatment, semi-finishing, finishing, inspection, through the installation mode of hole boss on each side and cavity inside and steel wire nipple fixing connector, and optimization is carried out to processing technology, meet the high-precision requirement between the surface of calibration tooling and each boss on vertical single-side milling machine can be processed.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of calibration tooling for inertial navigation systems, and in particular to a tetrahedron calibration tooling for inertial navigation systems and a processing technology thereof. BACKGROUND

[0002] An inertial navigation system is a self-contained navigation system, which does not rely on information outside the system and does not radiate energy to the outside of the system, and has the advantages of good concealment and working conditions not affected by environmental changes and human interference. Its working principle is based on Newton's law of mechanics, which measures the acceleration of the carrier in the inertial reference frame, and integrates the time, and then transforms it into the navigation coordinate system, so as to obtain the velocity, yaw angle, position and other related information of the carrier in the navigation coordinate system. Inertial navigation technology plays a very important role in national defense equipment technology. For medium and long range using inertial guidance, 70% of the hit accuracy depends on the accuracy of the guidance system. For nuclear submarines, the inertial navigation system is currently the only navigation device suitable for it.

[0003] The inertial navigation system is installed inside the calibration tooling through screws for calibration testing. In order to ensure the accuracy of the inertial navigation test, high requirements are put forward for the flatness, parallelism, perpendicularity and roughness of the four surfaces and the bosses of the calibration tooling. If the machining error of the four surfaces of the calibration tooling is too large, it will cause the deviation of the measurement data, thereby affecting the accuracy of the inertial navigation system. In addition, since the inertial navigation system is mass-produced, higher requirements are put forward for the calibration tooling, that is, the calibration tooling needs to be used for a long time to follow the system for various tests, causing wear of the four calibration planes, so that the surface measurement accuracy does not meet the product technical requirements.

[0004] The existing calibration tooling adopts a single structure and material, and its disadvantage is that after being used for a period of time, the tooling size will exceed the allowable error range due to the wear of the surface, thereby affecting the measurement accuracy of the fiber-optic inertial unit. Therefore, the calibration tooling needs to be repaired frequently, which not only increases the cost, but also prolongs the maintenance period and affects the progress of the product. SUMMARY

[0005] The present application aims to provide a tetrahedron calibration tooling for inertial navigation systems and a processing technology thereof, in order to solve the problem of long tooling repair period and easy damage in the prior art.

[0006] To achieve the above-mentioned purpose, the present application provides a tetrahedron calibration tooling for inertial navigation systems, which is used to fix the inertial navigation system,

[0007] The body skeleton has upper and lower surfaces with a quadrilateral outer contour, two front and back sides with the same structure, two left and right sides with the same structure and a through groove on the outer side, eight first non-hole bosses distributed on the four corners of the upper and lower surfaces, twelve second non-hole bosses on the front and back sides, twelve hole bosses on the left and right sides, and an internal cavity.

[0008] The outer side of the two front and back sides is provided with a non-through groove, and the inner side of the two front and back sides is provided with a circular arc slide. Each hole boss is used to connect an inertial navigation system and an external connecting piece. The internal cavity is provided with left and right bosses on the front and back side walls, and the internal cavity is symmetric about the center of the front and back sides.

[0009] The parallelism, perpendicularity and roughness of the surfaces of the eight first non-hole bosses distributed on the four corners of the upper and lower surfaces, the surfaces of the twelve second non-hole bosses on the front and back sides, and the surfaces of the twelve hole bosses on the left and right sides should meet the preset requirements. The depth of the non-through groove on the front and back sides is 5mm, and the distance between adjacent non-through grooves is 30mm. The distance between adjacent through grooves on the left and right sides is 20mm. The diameter error of the circular arc slide in the internal cavity is required to be between 0-0.3mm to ensure smooth installation of the inertial navigation system.

[0010] The six surfaces of the calibration tool are perpendicular and parallel to each other. The perpendicularity and parallelism between the two front and back sides, the two upper and lower surfaces, and the two left and right sides are not high, but the perpendicularity and parallelism between the boss surfaces of the body skeleton have strict precision requirements. The flatness of the boss surface of the body skeleton is not more than 0.012mm. The perpendicularity between the non-hole bosses on the upper and lower surfaces and the hole bosses on the left and right sides, the non-hole bosses on the front and back sides is not more than 0.02mm. The parallelism between the bosses 31 on the left and right sides is not more than 0.02mm. The perpendicularity between the hole bosses on the left and right sides and the second non-hole bosses on the front and back sides is not more than 0.02mm. The perpendicularity between the stepped surface of the left boss of the internal cavity and the surface of the second non-hole boss on the front and back sides is not more than 0.015mm.

[0011] The surface roughness of the first non-hole boss on the upper and lower surfaces, the second non-hole boss on the front and rear sides, the hole boss on the left and right sides, and the left boss inside the left side of the internal cavity and the right boss inside the right side of the internal cavity is not more than 1.6um. The surface roughness of the remaining planes of the body skeleton is not more than 3.2um. In addition, the center position error of the calibration hole in the same plane is not more than 0.1mm, the surface roughness of the first non-hole boss on the upper and lower surfaces of the body skeleton, the second non-hole boss on the front and rear sides, the hole boss on the left and right sides, and the left boss inside the left side of the internal cavity and the right boss inside the right side of the internal cavity is not more than 1.6um, the surface roughness of the remaining planes of the body skeleton is not more than 3.2um. In addition, the center position error of the calibration hole in the same plane is not more than 0.1mm, the tetrahedral calibration tool of the application has the advantages of simple overall structure, light weight, high wear resistance, easy replacement, outstanding comprehensive cost performance, and the method of replacing each surface with a surface boss to contact the inertial navigation system greatly reduces the processing difficulty.

[0012] The left boss is provided with a stepped platform.

[0013] The twelve hole bosses on the left and right sides are connected to the external connecting piece one by one, and the four bosses in the internal cavity are used to connect the inertial navigation system and the body skeleton.

[0014] The body skeleton and the external connecting piece are connected by a steel wire sleeve.

[0015] The calibration tool of the application uses a steel wire sleeve inlaying method to connect with the external connecting piece, so that the calibration tool can be disassembled and repaired more frequently, thereby ensuring the accuracy of the tool for a longer period of time.

[0016] The body skeleton is made of 2A12-T4 aluminum alloy material.

[0017] The body skeleton material aluminum alloy 2A12-T4 is subjected to sealing treatment after anodic oxidation treatment to improve the corrosion resistance and insulation of the oxidation film.

[0018] The tetrahedral calibration tool processing technology for the inertial navigation system is applied to the tetrahedral calibration tool as claimed in the preceding claims.

[0019] The tetrahedral calibration tool processing technology comprises the following steps:

[0020] S1: rough machining, rough milling of each outer surface and inner cavity surface of the calibration tool, leaving an appropriate amount of allowance;

[0021] S2: stability treatment, stability treatment, release processing stress;

[0022] S3: semi-finishing, milling out the calibration tooling outer wall and the inner cavity on each boss, further reducing the processing allowance;

[0023] S4: finishing, finishing each surface to the processing requirements, and processing the grooves and holes on each side and boss;

[0024] S5: inspection, deburring, drilling threaded holes, and implanting steel wire bushings.

[0025] In step S1, when rough machining the blank, use M50 flat knife to roughly mill the profile of the internal cavity, and keep 3mm processing allowance on each surface, and pay attention to the position of each boss inside the cavity;

[0026] Use M50 flat knife to trim the outer surface profile of the blank, also keep 3mm processing allowance.

[0027] In step S3, to ensure overall machining accuracy and reduce the influence of milling machine error on finishing, use M20 flat knife to gradually mill out the basic shape of the outer wall and cavity of the body framework, including the bosses on each surface, through multiple semi-finishing of the body framework.

[0028] In step S4, based on the above steps, inspect the remaining processing allowance of the body framework, and use M10 flat knife to further eliminate the processing allowance until the drawing requirements are met.

[0029] Step S4 also includes:

[0030] Use M16 flat knife to process the through grooves on the left and right sides, and pay attention to the spacing between the grooves during processing to ensure the parallelism of the groove surface. Process the non-through grooves on the front and rear sides, and pay attention to the parallelism of the non-through groove bottom surface and the side surface, as well as the perpendicularity of the groove bottom surface and the side surface.

[0031] Step S4 also includes:

[0032] Use M3 drill bit to drill holes on the bosses on the left and right sides and inside the cavity, and pay attention to the position accuracy of the holes to ensure the connection between the body framework and the external connecting parts and inertial navigation.

[0033] In step S5, quality inspection is performed on the finished body framework, including deburring, drilling threaded holes, and installing matching steel wire bushings.

[0034] The releasing processing stress includes the following steps:

[0035] The machining residual stress of the skeleton is eliminated by using a positive and negative temperature cycle process, the temperature range is-60 DEG C~120 DEG C, each temperature point is required to be kept for 2h~3h, and the total cycle is 3 times.

[0036] The tetrahedron calibration tool for the inertial navigation system and the machining process thereof provided by the application solve the problems of long calibration tool repair cycle and easy damage of threads by installing the fixing connector through the hole boss on each side and the cavity and the steel wire screw sleeve, optimize the machining process, meet the high-precision requirement between each surface of the calibration tool and each boss machined on the vertical single-face milling machine, and greatly improve the batch production efficiency of the calibration tool. BRIEF DESCRIPTION OF DRAWINGS

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description only some embodiments of the application, and for those skilled in the art, other drawings can also be obtained without creative labor.

[0038] Fig. 1 It is the axial structure schematic diagram of the tetrahedron calibration tool for the inertial navigation system provided by the application.

[0039] Fig. 2 It is the cross-sectional structure schematic diagram of the tetrahedron calibration tool for the inertial navigation system provided by the application.

[0040] Fig. 3 It is the step schematic diagram of the machining process of the tetrahedron calibration tool for the inertial navigation system provided by the application.

[0041] 1-front and back sides, 11-second non-hole boss, 12-non-through groove, 13-circular arc slide, 2-upper and lower surfaces, 21-first non-hole boss, 3-left and right sides, 31-hole boss, 32-through groove, 33-first calibration hole, 4-internal cavity, 41-second calibration hole, 42-step mesa, 43-left boss, 44-right boss. DETAILED DESCRIPTION

[0042] The embodiments of the application are described in detail below, and examples of the embodiments are shown in the drawings, wherein the same or similar notations represent the same or similar elements or elements with the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and are intended to explain the application, and cannot be understood as a limitation of the application.

[0043] In the description of the present application, it should be understood that the terms "length", "width", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, in the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise explicitly and specifically limited.

[0044] Please refer to Figs. 1-2 The present application provides a tetrahedral calibration tool for an inertial navigation system, which is used to fix the inertial navigation system,

[0045] The body framework has upper and lower surfaces 2 with a quadrilateral outer contour, front and rear side surfaces 1 which are structurally identical, left and right side surfaces 3 which are structurally identical and have through grooves 32 on the outer sides, eight first non-hole bosses 21 distributed on the four corners of the upper and lower surfaces 2, twelve second non-hole bosses 11 provided on the front and rear side surfaces 1, twelve hole bosses 31 provided on the left and right side surfaces 3, and an internal cavity 4.

[0046] The outer sides of the two front and rear side surfaces 1 are provided with non-through grooves 12, and the inner sides of the two front and rear side surfaces 1 are provided with circular arc slides 13. The aforementioned hole bosses 31 are used to connect the inertial navigation system and external connecting parts. The internal cavity 4 is provided with left and right bosses 43 and 44 on the front and rear side walls, and the internal cavity 4 is symmetric about the center plane of the front and rear side surfaces 1.

[0047] The parallelism, perpendicularity and roughness of the surfaces of the eight first non-hole bosses 21 distributed on the four corners of the upper and lower surfaces 2, the surfaces of the twelve second non-hole bosses 11 provided on the front and rear side surfaces 1, and the surfaces of the twelve hole bosses 31 provided on the left and right side surfaces 3 should meet the preset requirements. The depth of the non-through groove 12 on the front and rear side surfaces 1 is 5mm, and the distance between adjacent non-through grooves 12 is 30mm, which is used for the fixed installation of the body framework and external parts. The distance between adjacent through grooves 32 on the left and right side surfaces 3 is 20mm, and the diameter error of the circular arc slide 13 in the internal cavity 4 is required to be between 0-0.3mm, so as to ensure the smooth installation of the inertial navigation system.

[0048] The six surfaces of the calibration tool are perpendicular and parallel to each other, respectively, wherein the perpendicularity and parallelism between two of the front and rear sides 1, two of the upper and lower surfaces 2, and two of the left and right sides 3 are not high, but the perpendicularity and parallelism between the boss surfaces of the body frame are strictly required to have high precision, the body frame requires that the flatness of the boss surfaces is not more than 0.012 mm, the body frame requires that the perpendicularity between the non-hole boss 31 on the upper and lower surface 2 and the hole boss 31 on the left and right side 3 and the non-hole boss 31 on the front and rear side 1 is not more than 0.02 mm, and the body frame requires that the parallelism between the bosses 31 on the left and right side 3 is not more than 0.02 mm. The body frame requires that the perpendicularity between the hole boss 31 on the left and right side 3 and the second non-hole boss 11 on the front and rear side 1 is not more than 0.02 mm. The body frame requires that the perpendicularity between the stepped surface 42 of the left boss 43 of the inner cavity 4 and the surface of the left boss 43 of the left side wall in the inner cavity 4 and the second non-hole boss 11 on the front and rear side 1 is not more than 0.015 mm.

[0049] The body frame requires that the surface roughness of the first non-hole boss 21 on the upper and lower surface 2, the second non-hole boss 11 on the front and rear side 1, the hole boss 31 on the left and right side 3, and the left boss 43 on the left side of the inner cavity 4 and the right boss 44 on the right side of the inner cavity 4 is not more than 1.6 um. The body frame requires that the surface roughness of the remaining planes is not more than 3.2 um. The hole boss 31 is provided with a first calibration hole 33, and the center position error of the first calibration hole 33 at adjacent positions in the same plane is not more than 0.1 mm. The tetrahedral calibration tool of the present application has the advantages of simple overall structure, light weight, high wear resistance, easy replacement, outstanding comprehensive cost performance, and the method of replacing each surface with a boss surface to contact the inertial navigation system greatly reduces the processing difficulty.

[0050] The left boss 43 is provided with a stepped surface 42.

[0051] The twelve hole bosses 31 provided on the left and right sides 3 are connected one by one with the external connecting members, and the four bosses in the inner cavity 4 are used to connect the inertial navigation system with the body frame.

[0052] The body frame and the external connecting members are connected by a steel wire screw.

[0053] The calibration tool of the present application uses the method of inlaying a steel wire screw to connect with the external connecting members, so that the calibration tool can be disassembled and repaired more frequently, thereby ensuring the precision of the tool for a longer period of time.

[0054] The body skeleton is made of 2A12-T4 aluminum alloy material.

[0055] The body skeleton material 2A12-T4 is subjected to sealing treatment after anodic oxidation treatment, so as to improve the corrosion resistance and insulation of the oxidation film.

[0056] Please refer to Fig. 3 The application also provides a tetrahedron calibration tool machining process for an inertial navigation system, which is applied to the tetrahedron calibration tool as claimed in the preceding claims.

[0057] The tetrahedron calibration tool machining process comprises the following steps:

[0058] S1: rough machining, rough milling of each outer surface and inner cavity surface of the calibration tool, and retaining an appropriate amount of allowance;

[0059] Among them,

[0060] S1 specifically comprises the following steps: when the rough machining is performed on the blank, a M50 flat knife is used on a common single-face horizontal milling machine to roughly mill the profile of the inner cavity 4, and each surface is kept with a machining allowance of 3 mm, and the positions of the bosses in the cavity are noted; then, a M50 flat knife is used to trim the profile of the outer surface of the blank, and a machining allowance of 3 mm is also kept.

[0061] S2: stability treatment, stability treatment is performed to release machining stress;

[0062] The positive and negative temperature cycle process is used to eliminate the residual stress of the skeleton after rough machining, and the temperature range is specifically required to be controlled at-60 DEG C to 120 DEG C, the temperature is kept for 2 h to 3 h at each temperature point, and the cycle is performed for 3 times in total.

[0063] S3: semi-finishing, milling each boss on the outer wall and inner cavity of the calibration tool, and further reducing the machining allowance;

[0064] In order to ensure the overall machining accuracy and reduce the influence of the milling machine itself error on the finishing, the body skeleton is subjected to repeated semi-finishing operation, that is, a M20 flat knife is used to gradually mill away the machining allowance of the body skeleton retained in the step S1, and the machining is stopped in the last semi-finishing to complete the semi-finishing process.

[0065] S4: finishing, finishing each surface to the machining requirement, and performing groove digging and hole punching on each side surface and boss;

[0066] S4: Inspect, remove burrs, drill threads, and implant steel wire bushings.

[0067] S5: Inspect, remove burrs, drill threads, and implant steel wire bushings.

[0068] After the final machining of the body frame, quality inspection is performed. After checking the requirements between each surface and each boss, deburring is performed on the frame to ensure the smoothness between the assembly surface and the contact surface. Then, the first calibration hole 33 in step S4 is drilled into a threaded hole to fit the steel wire bushing ST5x0.8-15K.

[0069] In step S1, when the rough machining of the blank is performed, the M50 flat knife is used to roughly mill the profile of the internal cavity 4, leaving a machining allowance of 3mm on each surface, and the positions of the bosses inside the cavity are noted;

[0070] The M50 flat knife is used to trim the outer surface profile of the blank, also leaving a machining allowance of 3mm.

[0071] In step S3, to ensure overall machining accuracy and reduce the influence of milling machine errors on precision machining, the body frame is subjected to multiple semi-precision machining. The M20 flat knife is used to gradually mill the basic shape of the outer wall of the body frame and the cavity, including the bosses on each surface.

[0072] In step S4, based on the above steps, the remaining machining allowance of the body frame is inspected, and the M10 flat knife is used to further eliminate the machining allowance until the requirements of the drawing are met.

[0073] Step S4 also includes:

[0074] The through groove 32 of the left and right side surfaces 3 is machined by using a flat knife of M16, and the distance between the grooves needs to be paid attention to during machining to ensure the parallelism of the groove surface. The non-through groove 12 of the front and rear side surfaces 1 is machined before and after, and the parallelism of the non-through groove 12 bottom surface and the side surface and the perpendicularity of the groove bottom surface and the side surface need to be paid attention to during machining.

[0075] The step S4 further comprises:

[0076] The holes are punched on the bosses of the left and right side surfaces 3 and the cavity inside by using a drill bit of M3, and the position accuracy of the holes needs to be paid attention to to ensure the connection of the body framework with the external connecting piece and the inertial navigation system.

[0077] In step S5, the quality inspection of the body framework after finishing machining is carried out, including burr treatment, drilling threaded holes, installing matched steel wire sleeves and the like.

[0078] The releasing machining stress comprises the following steps:

[0079] The machining residual stress of the framework is eliminated by using positive and negative temperature cycle process, the temperature range is-60 DEG C~120 DEG C, and it is required to keep 2h-3h at each temperature point, and a total of 3 cycles.

[0080] The tetrahedron calibration tool for the inertial navigation system and the machining process thereof have the advantages of supporting more frequent disassembly and maintenance, thereby ensuring the precision of the tool for a longer time, the calibration tool has simple overall structure, light weight, high wear resistance, easy replacement, outstanding comprehensive cost performance, the method of using each surface boss instead of the contact of each surface with the inertial navigation system greatly reduces the machining difficulty, in addition, the machining process of the tetrahedron calibration tool ensures the overall size of the tool and the position precision requirements such as the flatness, parallelism and perpendicularity between the multiple bosses, completes the precise forming of the tool shape and the precise machining of the internal cavity 4, the machining quality is stable, the tool can be machined on an ordinary single-face horizontal milling machine, the machining efficiency is greatly improved, and the tool is suitable for mass processing.

[0081] The above only discloses a preferred embodiment of the present application, and of course cannot limit the scope of the present application, and those skilled in the art can understand that all or part of the above-mentioned embodiments are implemented, and equivalent changes made according to the claims of the present application still belong to the scope covered by the present application.

Claims

1. A tetrahedral calibration tool for an inertial navigation system, for fixing the inertial navigation system, characterized in that, the body framework has upper and lower surfaces with a quadrilateral outer contour, front and rear sides with the same structure, left and right sides with the same structure and provided with through grooves on the outer side, eight first non-hole bosses distributed at the four corners of the upper and lower surfaces, twelve second non-hole bosses provided on the front and rear sides, twelve hole bosses provided on the left and right sides, and an internal cavity; the outer side of the front and rear sides is provided with a non-through groove, and the inner side of the front and rear sides is provided with a circular arc slide, each hole boss is used to connect the inertial navigation system and the external connecting piece, the internal cavity is provided with left and right bosses on the front and rear side walls, and the internal cavity is symmetric about the center of the front and rear side walls; the twelve hole bosses provided on the left and right sides are connected one by one with the external connecting piece, and four bosses in the internal cavity are used to connect the inertial navigation system and the body framework.

2. The tetrahedral calibration tool for the inertial navigation system according to claim 1, characterized in that, the left boss is provided with a stepped platform.

3. The tetrahedral calibration tool for the inertial navigation system according to claim 1, characterized in that, the body framework and the external connecting piece are connected by a steel wire sleeve.

4. The tetrahedral calibration tool for the inertial navigation system according to claim 1, characterized in that, the body framework is made of 2A12-T4 aluminum alloy material.

5. A tetrahedral calibration tool processing technology for an inertial navigation system, applied to the tetrahedral calibration tool according to claim 1, characterized in that, the tetrahedral calibration tool processing technology comprises the following steps: rough machining, rough milling of the outer surfaces and internal cavity surfaces of the calibration tool, leaving an appropriate amount of allowance; stability treatment, stability treatment is performed to release the machining stress; semi-finish machining, milling out the bosses on the outer wall and internal cavity of the calibration tool, further reducing the machining allowance; finish machining, fine milling of each surface to the machining requirement, and groove digging and hole punching treatment on each side and boss; inspection, removing burrs, drilling threads in the holes, and implanting a steel wire sleeve.

6. The tetrahedral calibration tool processing technology for the inertial navigation system according to claim 5, characterized in that, the release of machining stress comprises the following steps: eliminate the machining residual stress of the framework by using positive and negative temperature cycle process, the temperature range is-60℃~120℃, and it is required to keep each temperature point for 2h~3h, a total of 3 times.

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