Part surface precision measurement method based on force-position cooperation in general assembly state

Abstract

The application discloses a kind of total assembly state based on force-position collaborative part profile precision measurement method, comprising the following steps: according to the actual size of assembly jig drill hole and part locking hole, manufacturing force measurement adaptive mould;Force measurement adaptive mould is installed to the drill hole in assembly jig and is fixed;The part to be measured is aligned with force measurement adaptive mould by its locking hole, utilizes constant force spring pin to pass through part locking hole and acts on force measurement adaptive mould, to apply known and constant pre-tightening force to part, complete part in assembly jig on constant force clamping;In the constant pre-tightening force state of part, using measuring equipment to collect data on part profile, the accurate control of force and the high-precision measurement of position are combined, can provide known, uniform distribution and constant standard clamping force in the whole measurement process for part, eliminate the dispersion problem of measurement data caused by clamping force fluctuation from the source, greatly improve the accuracy of measurement result.

Description

Technical Field

[0001] This invention belongs to the field of aerospace component measurement technology, specifically relating to a method for measuring the surface accuracy of parts based on force-position coordination in the final assembly state. Background Technology

[0002] In the research and development and production of modern aircraft (such as large passenger aircraft, military aircraft, and space launch vehicles), the skeletal structure (such as the frame and bulkhead of the fuselage, and the beams and ribs of the wings) is the core load-bearing component that bears and transmits the main loads. The surface accuracy of the skeletal structure directly determines the assembly coordination of the overall structure, the integrity of the load transmission path, and the structural safety and service reliability of the final product. Therefore, high-precision and high-reliability measurement and evaluation of the skeletal structure of these key load-bearing skeletal components during the final assembly stage is a crucial link in ensuring the structural quality of the aircraft.

[0003] The current conventional method for measuring the surface profile of skeleton parts is as follows: after the part is installed on the assembly jig, the fit clearance between the part and the tooling is checked, or equipment such as a laser tracker is used to position and inspect the part's surface profile. The basic operation process of this method is: first, the part is installed on the assembly jig using a traditional fixture, and then a clearance gauge is used to measure the clearance between the detection block or detection plate and the workpiece surface profile, thereby evaluating the surface accuracy of the workpiece. However, this method has a technical flaw: it does not effectively control the clamping state of the part.

[0004] Specifically, the traditional screw clamps widely used on assembly jigs provide clamping forces that are uneven, difficult to quantify, and cannot be kept constant during measurement. The clamping forces vary significantly between different operators and different clamping points. Even the same operator cannot guarantee the consistency of clamping forces in multiple operations. This uncertainty in clamping force introduced by human factors and tool characteristics directly leads to poor repeatability and low reliability of measurement results, making it impossible for process engineers to accurately distinguish the following three types of errors: manufacturing errors of the parts themselves, elastic or plastic deformation caused by assembly stress, and errors introduced by the measurement method itself.

[0005] Furthermore, when the workpiece is large and the surface to be inspected is far from the operating table, the operator's reading position deviates significantly from the position of the inspection tool when using traditional methods to inspect the surface accuracy, which further reduces the measurement accuracy. For assemblies with multiple connections and over-positioning constraints, if the preload of each clamping point is inconsistent, the parts will generate additional bending moments or twisting, which seriously affects the assembly coordination accuracy. Therefore, we propose a part surface accuracy measurement method based on force-position coordination in the final assembly state. Summary of the Invention

[0006] The purpose of this invention is to provide a method for measuring the surface accuracy of parts based on force-position coordination in the final assembly state, so as to solve the problems mentioned in the background art.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a method for measuring the surface accuracy of parts in the final assembly state based on force-position coordination, comprising the following steps:

[0008] Step 1: Preparation of force measuring adapter mold: Based on the actual dimensions of the drilling holes of the assembly frame and the locking holes of the parts, manufacture the force measuring adapter mold;

[0009] Step 2, Mold Installation and Adaptation: Install the force measuring adapter mold into the drill hole of the assembly frame and fix it in place;

[0010] Step 3, constant force clamping: Align the part to be tested with the force measuring adapter mold through its locking hole, and use a constant force spring pin to pass through the locking hole of the part and act on the force measuring adapter mold to apply a known and constant preload force to the part, thus completing the constant force clamping of the part on the assembly frame;

[0011] Step 4: Profile Measurement: With the part under the constant preload state, use measuring equipment to collect data on the profile of the part.

[0012] Preferably, the force measuring adapter mold has a stepped shaft structure, with a top plate at one end for axial positioning with the assembly frame reference surface and for bearing clamping reaction force.

[0013] The force measuring adapter mold has a blind hole machined along the axial direction at its center, which is used to guide the insertion and locking of the constant force spring pin.

[0014] The force measuring adapter mold has a slot at its tail end, which provides a tooling point for the installation and disassembly of the force measuring adapter mold.

[0015] Preferably, step one further includes a mold compensation process: applying a compensation material to the outer diameter of the force measuring adapter mold to compensate for the loss, and the compensation value is determined based on the measured gap between the outer diameter of the force measuring adapter mold and the inner diameter of the drilling hole of the assembly frame.

[0016] After curing, the compensation material forms a uniform coating, which is used to eliminate the fit gap between the outer circle of the force measuring adapter mold and the inner wall of the drill hole.

[0017] Preferably, the compensation material is APF paint, which is applied and left to cure at room temperature for 30 minutes after application.

[0018] Preferably, in step two, after the force measuring adapter mold is installed into the drilling hole of the assembly frame, it is further fixed by attaching pressure-sensitive adhesive tape to the edge of the force measuring adapter mold.

[0019] Preferably, the force measuring adapter mold is provided with a detachable adjustment shim at the contact surface between the top plate and the assembly frame, which is used to adjust the step height of the force measuring adapter mold in real time to adapt to parts or frames of different thicknesses.

[0020] Preferably, the force measuring adapter mold has an integrated knob-type fine-tuning mechanism inside, which is linked to the top plate and used to adjust the step height of the force measuring adapter mold.

[0021] Preferably, the measuring device is a laser tracker.

[0022] Preferably, the material of the force measuring adapter mold is 45 steel. After machining, it is heat-treated to relieve stress. The heat treatment process is as follows: heat treatment is carried out in a heating furnace at 150°C to 250°C for 1.5 to 6 hours, and then it is taken out and naturally cooled to room temperature.

[0023] Preferably, the method is applicable to the surface accuracy measurement of large thin-walled weakly rigid structural components, composite material skin panels, sheet metal forming parts, and complex curved surface parts that are prone to elastic rebound in the final assembly state.

[0024] Compared with the prior art, the beneficial effects of the present invention are:

[0025] 1. This invention replaces the traditional screw clamp that relies on manual experience and has unstable force values ​​by using a force-measuring adapter mold and a constant-force spring pin in synergy. It combines precise force control with high-precision position measurement, and reproduces the constant preload specified in the process during the measurement stage. This allows the measurement data to truly reflect the actual shape of the part under assembly stress, providing a reliable data basis for subsequent assembly coordination and error analysis. It can provide the part with a standard clamping force that is known in size, evenly distributed, and remains constant throughout the measurement process, eliminating the problem of measurement data dispersion caused by clamping force fluctuations from the source and greatly improving the accuracy of measurement results.

[0026] 2. The force measuring adapter mold of the present invention has an adjustable step height device and can be compensated for its outer diameter by coating, so that it can flexibly adapt to the hole diameter tolerance and position deviation between the assembly frame drill hole and the part locking hole, which greatly improves the tooling's versatility and adaptability to actual production conditions.

[0027] 3. The slotted structure at the tail of the mold in this invention facilitates installation and disassembly; the use of pressure-sensitive tape for auxiliary fixing is simple, efficient, and pollution-free, ensuring the convenience and stability of the operation process and improving on-site measurement efficiency. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the force measuring adapter mold structure of the present invention.

[0029] In the diagram: 1. Blind hole; 2. Groove; 3. Compensating material; 4. Top plate. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] This embodiment uses a typical connection part of the fuselage frame of a certain aircraft model as an example to illustrate the specific implementation process of the present invention in detail:

[0032] Step 1: Fabrication of the force measuring adapter mold:

[0033] Use CAD and other drawing software to complete the structural design of the force measuring and adapting mold, and then issue the machining operation;

[0034] like Figure 1 As shown, the specific structural parameters of the force measuring adapter mold in this embodiment are as follows:

[0035] The mold has a stepped shaft structure, with a top plate 4 at the top, which is 5mm thick. It is used to fit and limit the assembly frame reference surface and bear the clamping reaction force.

[0036] The center of the mold has a blind hole 1 with a diameter of 3.5 mm and a depth of 8 mm machined along the axial direction to accommodate the insertion end of the constant force spring pin and provide locking guidance;

[0037] A slot 2 with a width of 1.5mm and a depth of 6mm is opened at the tail of the mold (i.e. the opposite side of the top plate). The slot extends to the bottom of the blind hole, which makes it easy to use a flat tool to insert and rotate the mold for disassembly. At the same time, it serves as a stress relief groove to prevent the mold from getting stuck due to interference fit.

[0038] The outer diameter of the mold body is machined to 9.5mm.

[0039] In this embodiment, the actual diameter of the drilling hole in the assembly frame is 10mm, the actual diameter of the locking hole in the part is 3.26mm, and the total thickness of the tooling is 10mm.

[0040] The material of the force measuring adapter mold is 45 steel. In order to eliminate machining stress, heat treatment is performed after machining: heat treatment is carried out in a heating furnace (such as an oil bath furnace or an air circulation furnace) in the range of 150℃ to 250℃ for 1.5 to 6 hours, and then it is taken out and naturally cooled to room temperature in the air.

[0041] Force measurement and mold compensation:

[0042] The outer diameter of the force measuring adapter mold is compensated by using a coating. The outer diameter of the force measuring adapter mold is 9.5mm, and there is a gap of 0.25mm on one side and a total of 0.5mm between it and the 10mm assembly frame drill hole.

[0043] APF aviation anti-corrosion paint is used as compensation material 3. It is evenly applied to the outer diameter surface of the force measuring adapter mold for compensation. The compensation thickness is just enough to eliminate the gap and allow for smooth insertion. After compensation, it is left to stand at room temperature for 30 minutes until the APF paint layer is completely cured to achieve the required mating dimensions.

[0044] Step 2: Force Measurement Adaptor Mold Adaptation:

[0045] After the force measuring adapter mold is compensated and cured, it is installed into the drilled hole of the assembly frame according to the corresponding position. After installation, pressure-sensitive tape (such as polyimide tape) is used to stick the force measuring adapter mold tightly to the frame base for auxiliary fixation, so as to ensure that the force measuring adapter mold will not fall off or shift due to its own weight in subsequent operations.

[0046] Step 3: Clamp with constant force:

[0047] Align the locking hole of the part to be tested with the installed force measuring adapter mold, select a constant force spring pin of the specified specification, insert it into the locking hole of the part in sequence and insert it into the blind hole 1 of the force measuring adapter mold, and use the constant tension of the constant force spring pin to apply a known and constant preload force to the part to complete the constant force clamping of the part on the assembly frame.

[0048] Step 4: Surface Measurement

[0049] After the part is fixed, the laser tracker is started and data is collected on the part surface under the constant preload according to the preset measurement path.

[0050] In this embodiment, the force measuring adapter mold is provided with a detachable adjustment shim at the contact surface between the top plate 4 and the assembly frame. When the thickness of the part to be measured changes or there is a machining error on the reference surface of the frame, the step height of the force measuring adapter mold can be adjusted in real time by increasing or decreasing the number of adjustment shims or replacing shims of different thicknesses, so that the mold can adapt to parts or frames of different thicknesses and ensure that the clamping force direction of the constant force spring pin is perpendicular to the surface of the part.

[0051] In this embodiment, the force measuring adapter mold has an integrated knob-type fine adjustment mechanism. This knob-type fine adjustment mechanism is linked with the top plate 4. The operator can rotate the knob to drive the top plate to generate axial displacement relative to the mold body, thereby continuously and precisely adjusting the step height of the force measuring adapter mold. This method does not require the replacement of any parts, and the adjustment process is more convenient and faster, especially suitable for production scenarios that require frequent switching of different part models.

[0052] In this embodiment, the method is applied to the assembly surface accuracy measurement of a large thin-walled weak rigidity structural component: a composite material wing panel of a certain type of aircraft. This wing panel has low stiffness in a free state, is easily affected by its own weight and produces non-real deformation, and has multiple connection relationships with the wing spars, ribs and other skeleton structures.

[0053] This invention replaces the traditional screw clamp, which relies on manual experience and has unstable force values, by using a force-measuring adapter mold and a constant-force spring pin in synergy. It combines precise force control with high-precision position measurement, and reproduces the constant preload specified in the process during the measurement stage. This allows the measurement data to truly reflect the actual shape of the part under assembly stress, providing a reliable data foundation for subsequent assembly coordination and error analysis. It can provide the part with a standard clamping force that is known in size, evenly distributed, and remains constant throughout the measurement process, eliminating the problem of measurement data dispersion caused by clamping force fluctuations from the source and greatly improving the accuracy of the measurement results.

[0054] The force-measuring adapter mold of the present invention uses a device that can adjust the step height (such as a detachable shim or an integrated knob) and can compensate for the outer diameter with paint, so that it can flexibly adapt to the hole diameter tolerance and position deviation between the assembly jig hole and the locking hole of the part, greatly improving the versatility of the tooling and its adaptability to actual production conditions.

[0055] The slotted structure at the tail of the mold in this invention facilitates installation and disassembly; the use of pressure-sensitive tape for auxiliary fixing is simple, efficient, and pollution-free, ensuring the convenience and stability of the operation process and improving on-site measurement efficiency.

[0056] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for measuring the surface accuracy of a part in its final assembly state based on force-position coordination, characterized in that, Includes the following steps: Step 1: Preparation of force measuring adapter mold: Based on the actual dimensions of the drilling holes of the assembly frame and the locking holes of the parts, manufacture the force measuring adapter mold; Step 2, Mold Installation and Adaptation: Install the force measuring adapter mold into the drill hole of the assembly frame and fix it in place; Step 3, constant force clamping: Align the part to be tested with the force measuring adapter mold through its locking hole, and use a constant force spring pin to pass through the locking hole of the part and act on the force measuring adapter mold to apply a known and constant preload force to the part, thus completing the constant force clamping of the part on the assembly frame; Step 4: Profile Measurement: With the part under the constant preload state, use measuring equipment to collect data on the profile of the part.

2. The method for measuring the surface accuracy of a part in its final assembly state based on force-position coordination, as described in claim 1, is characterized in that: The force measuring adapter mold has a stepped shaft structure, with a top plate at one end for axial positioning with the assembly frame reference surface and for bearing clamping reaction force. The force measuring adapter mold has a blind hole machined along the axial direction at its center, which is used to guide the insertion and locking of the constant force spring pin. The force measuring adapter mold has a slot at its tail end, which provides a tooling point for the installation and disassembly of the force measuring adapter mold.

3. The method for measuring the surface accuracy of a part in its final assembly state based on force-position coordination, as described in claim 1, is characterized in that: Step one also includes a mold compensation process: the outer diameter of the force measuring adapter mold is coated with compensation material, and the compensation value is determined based on the measured gap between the outer diameter of the force measuring adapter mold and the inner diameter of the drilling hole of the assembly frame. After curing, the compensation material forms a uniform coating, which is used to eliminate the fit gap between the outer circle of the force measuring adapter mold and the inner wall of the drill hole.

4. The method for measuring the surface accuracy of a part in its final assembly state based on force-position coordination, as described in claim 3, is characterized in that: The compensation material is APF paint, which is applied and left to cure at room temperature for 30 minutes after application.

5. The method for measuring the surface accuracy of a part in its final assembly state based on force-position coordination, as described in claim 1, is characterized in that: In step two, after the force measuring adapter mold is installed into the drilling hole of the assembly frame, it is further fixed by attaching pressure-sensitive adhesive tape to the edge of the force measuring adapter mold.

6. The method for measuring the surface accuracy of a part in its final assembly state based on force-position coordination, as described in claim 1, is characterized in that: The force measuring adapter mold is equipped with a detachable adjustment shim at the contact surface between the top plate and the assembly frame, which is used to adjust the step height of the force measuring adapter mold in real time to adapt to parts or frames of different thicknesses.

7. The method for measuring the surface accuracy of a part in its final assembly state based on force-position coordination, as described in claim 1, is characterized in that: The force measuring adapter mold has an integrated knob-type fine-tuning mechanism inside, which is linked to the top plate and is used to adjust the step height of the force measuring adapter mold.

8. The method for measuring the surface accuracy of a part in its final assembly state based on force-position coordination, as described in claim 1, is characterized in that: The measuring device is a laser tracker.

9. The method for measuring the surface accuracy of a part in its final assembly state based on force-position coordination, as described in claim 1, is characterized in that: The force measuring adapter mold is made of 45 steel. After machining, it is heat-treated to relieve stress. The heat treatment process is as follows: heat treatment is carried out in a heating furnace at 150°C to 250°C for 1.5 to 6 hours, and then it is taken out and naturally cooled to room temperature.

10. A method for measuring the surface accuracy of a part in its final assembly state based on force-position coordination, as described in claim 1, characterized in that: The method is applicable to the surface accuracy measurement of large thin-walled weakly rigid structural components, composite material skin panels, sheet metal forming parts, and complex curved surface parts that are prone to elastic rebound in the final assembly state.

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