Method for restoring embedded handle after breakage of rear handle of round broach

Abstract

The invention provides a method for restoring and embedding a broken rear handle of a round broach. The method comprises the following steps: measuring and determining the breakage position and size of the original rear handle, turning a rear guide part of the broach, machining a step structure and an annular groove, heating a new rear handle for hot assembly, and fixing by adopting a three-point positioning thread. According to the method, reliable repair of the broken handle is achieved in the mode that hot assembly and mechanical locking are combined, and the method has the advantages of being simple in machining process, low in repair cost and high in connection reliability.

Description

Technical Field

[0001] The present application relates to the field of mechanical processing technology, and in particular to a method for restoring and embedding a circular broach handle after the rear handle is broken. Background Art

[0002] The broach is an important precision machining tool. The main function of the rear handle is to serve as the rear support for broaches larger than 60 mm and heavier, to prevent the broach from tilting during operation. The structure of the broach usually includes the handle, neck, transition cone, leading part, cutting teeth, calibration teeth, rear guide and rear handle, among which the integrity of the rear handle has an important influence on the performance of the broach.

[0003] At present, in the process of broach manufacturing and use, the common methods of fixing the broach handle mainly include integral processing and mechanical connection. The integral processing has the advantages of simple structure and high connection strength, but the cost is relatively high; the mechanical connection method is easy to assemble, but it is prone to looseness and loss of precision.

[0004] In actual production, the rear handle of the broach may break due to material defects, overload use, fatigue damage, improper heat treatment, etc. In the prior art, broaches with broken rear handles are usually directly scrapped, which not only causes a large amount of resource waste, but also increases production costs.

[0005] The existing technology has the following main problems: in the conventional production, processing and use process, there is no effective repair method after the rear handle of the broach is broken, and it can only be scrapped, which leads to huge economic losses. In addition, the existing few repair solutions have technical defects such as poor connection reliability and difficulty in ensuring accuracy. Summary of the invention

[0006] In view of this, the present application provides a method for restoring the broken rear handle of a circular broach, which solves the problem in the prior art that the broken rear handle of the broach lacks an effective repair method and can only be scrapped, resulting in economic losses.

[0007] The present application provides a method for restoring a circular broach handle after the rear handle is broken, comprising the following steps:

[0008] Measure and determine the fracture position and size of the original rear handle, use a three-coordinate measuring machine or precision measuring tools to measure the outer diameter, roundness and coaxiality of the rear guide part, and establish the basic benchmark data;

[0009] Carry out broaching back guide turning, including:

[0010] Use carbide tools for the first rough turning, with feed rate f≤0.15mm / r, cutting depth ap≤1mm, cutting speed 80-100m / min, to remove the surface oxide layer;

[0011] Use ceramic tools for the second finishing, with feed rate f≤0.08mm / r, cutting depth ap≤0.2mm, cutting speed 120-150m / min, to machine the step structure, leaving a finishing allowance of 0.02-0.05mm;

[0012] Process annular grooves on the step structure, with a groove depth of 0.5-1mm, surface roughness Ra≤1.6μm, and cylindricality error controlled within 0.01mm;

[0013] Design and process the first rear handle according to the step structure size, and arrange three through-threaded holes at intervals of 120° along the circumference of the circular broach rear guide portion, each threaded hole having a 90° or 120° countersunk hole structure;

[0014] Put the first rear handle into a medium temperature tempering furnace and heat it to 350°C, keep it warm for 15-20 minutes, and control the temperature uniformity within the range of ±5°C. The first rear handle is a re-customized rear handle;

[0015] A special centering fixture is used for heat-fit assembly. The leveling error of the fixture base is controlled within 0.02mm / 1000mm, and the centering accuracy is ≤0.01mm.

[0016] After natural cooling, apply medium-strength thread locking agent on the threaded connection surface, screw the three screws through the threaded holes respectively, so that the ends of the screws extend into the annular groove for limit fixation, and tighten in steps with a torque wrench to control the screw tightening torque error within ±5%.

[0017] The cooperation between the first rear handle and the step structure adopts the following parameters:

[0018] diameter The following uses H7 / u6 fit, with interference 0.015-0.025mm;

[0019] diameter Adopt H7 / u7 fit, interference 0.020-0.032mm;

[0020] diameter The above adopts H7 / u8 fit, with interference 0.025-0.040mm;

[0021] The mating surfaces are inspected with blue light, and the contact area ratio is ≥85%, with evenly distributed contact points.

[0022] The screw selection and installation includes:

[0023] Use screws with strength grade 12.9;

[0024] For diameter For screws, use a tightening torque of 25-30 N·m;

[0025] For diameter For screws, use a tightening torque of 45-50 N·m;

[0026] For diameter For screws, use a tightening torque of 70-80 N·m;

[0027] The thread clearance is 6g / 6H.

[0028] Measure and determine the fracture position and size of the original rear handle, use a three-coordinate measuring machine or precision measuring tools to measure the outer diameter, roundness and coaxiality of the rear guide part, and establish the basic benchmark data;

[0029] Carry out broaching back guide turning, including:

[0030] Use carbide tools for the first rough turning, with feed rate f≤0.15mm / r, cutting depth ap≤1mm, cutting speed 80-100m / min, to remove the surface oxide layer;

[0031] Use ceramic tools for the second finishing, feed rate f≤0.08mm / r, cutting depth ap≤0.2mm, cutting speed 120-150m / min, process the step structure, and reserve 0.02-0.05mm finishing allowance;

[0032] Using micron-level stereolithography technology, epoxy acrylate photosensitive resin material is used to print the transition connection layer on the fracture surface, wherein the laser power is controlled at 80-100mW and the scanning speed is 200-300mm / s;

[0033] Among them, printing the transition connection layer on the fracture surface includes: printing a honeycomb basic grid with a unit size of 50-100 microns, and the structure density distribution is gradient, gradually decreasing from the inside to the outside; setting a micro-barb structure with a height of 15-25 microns;

[0034] The 42CrMo alloy sheets are stacked layer by layer using the layered solid manufacturing technology, wherein the thickness of the alloy sheets starts from 0.1 mm and increases to 0.2 mm layer by layer;

[0035] The interlayers are bonded with modified epoxy resin structural adhesive, with the amount of adhesive applied per layer being 0.15-0.20g / cm 2 ;

[0036] The pressing pressure is 3-5MPa, and the pressing force increases by 10% layer by layer;

[0037] The inter-layer alignment accuracy is ≤0.02mm, and the vacuum degree during stacking is ≤10Pa;

[0038] Perform stress release heat treatment at 200-250°C for 2-3 hours and cool with the furnace;

[0039] After cooling, three through threaded holes are arranged at intervals of 120° along the circumference, each threaded hole has a 90° or 120° countersunk hole structure, and three screws are screwed in through the threaded holes respectively.

[0040] The modified epoxy resin structural adhesive adopts a gradient formula:

[0041] The bottom layer uses a high-toughness formula with a shear strength of ≥25MPa;

[0042] The middle layer uses a standard formula with a temperature resistance of -40°C to 150°C;

[0043] The surface layer uses a high-strength formula with a curing time of 120 minutes (120°C);

[0044] The bonding strength shall not be less than 85% of the parent material strength.

[0045] The method further comprises: performing the following tests after forming:

[0046] Ultrasonic flaw detection is carried out every 5 layers;

[0047] After final molding, X-ray inspection is carried out to ensure that there are no internal defects;

[0048] Test the surface hardness, which is required to reach more than 90% of the raw material;

[0049] Perform dynamic balance test and the dynamic balance level reaches G2.5.

[0050] Measure and determine the fracture position and size of the original rear handle, use a three-coordinate measuring machine or precision measuring tools to measure the outer diameter, roundness and coaxiality of the rear guide part, and establish the basic benchmark data;

[0051] Carry out broaching back guide turning, including:

[0052] Use carbide tools for the first rough turning, with feed rate f≤0.15mm / r, cutting depth ap≤1mm, cutting speed 80-100m / min, to remove the surface oxide layer;

[0053] Use ceramic tools for the second finishing, feed rate f≤0.08mm / r, cutting depth ap≤0.2mm, cutting speed 120-150m / min, process the step structure, and reserve 0.02-0.05mm finishing allowance;

[0054] Put the first rear handle into a medium temperature tempering furnace and heat it to 350°C, keep it warm for 15-20 minutes, and control the temperature uniformity within the range of ±5°C. The first rear handle is a re-customized rear handle;

[0055] Three through threaded holes are arranged at intervals of 120° along the circumference, each threaded hole has a 90° or 120° countersunk hole structure, and three screws are screwed in through the threaded holes for fixing;

[0056] An elastic compensation structure is designed between the first rear handle and the original rear guide, including:

[0057] It uses three elastic diaphragms evenly spaced at 120°, made of 42CrMo alloy steel with a hardness of HRC32-36;

[0058] The thickness of the diaphragm is precisely controlled at 1.5-2mm, and the thickness ratio between the inner and outer ends is 1.2:1;

[0059] The effective working length is 0.4-0.5 times the diameter of the rear handle;

[0060] A bearing support system is provided, comprising:

[0061] Use double-row angular contact ball bearings with P4 grade precision;

[0062] The bearing preload is adjusted by precision nuts and controlled between 5% and 8% of the dynamic load.

[0063] The bearing seat adopts 40Cr quenched and tempered steel integral design;

[0064] The radial clearance is controlled at 0.01-0.015mm;

[0065] Carry out assembly, including:

[0066] Using a special positioning tool to install the elastic diaphragm, the position of the elastic diaphragm and the position of the threaded hole are arranged alternately;

[0067] Control the circumferential distribution error of the three diaphragms to be ≤0.5°;

[0068] The verticality between the diaphragm and the connection surface is ≤0.02mm;

[0069] The installation torque is controlled at 20-25N·m;

[0070] Set up the bearing system, including:

[0071] The bearing seat aperture accuracy requirement is H6;

[0072] The interference of the outer ring of the bearing is 0.01-0.02mm;

[0073] The verticality between the bearing end face and the seat is ≤0.005mm;

[0074] The preload force is controlled by a special torque wrench.

[0075] The performance parameters of the elastic diaphragm include:

[0076] Material elastic modulus: 210GPa;

[0077] Yield strength: ≥835MPa;

[0078] Fatigue strength: ≥400MPa;

[0079] Elastic deformation: 0.2-0.3mm;

[0080] Bearing preload: 2000-3000N.

[0081] The restored inlay handle meets the following criteria:

[0082] Static detection:

[0083] Radial runout ≤ 0.01mm;

[0084] Axial runout ≤ 0.015mm;

[0085] Coaxiality ≤ 0.02mm;

[0086] Angle swing ≤ 0.1°;

[0087] Dynamic Detection:

[0088] Vibration value at working speed ≤0.8mm / s;

[0089] Temperature rise ≤15℃;

[0090] Noise value ≤75dB.

[0091] The assembly environment requirements include:

[0092] Constant temperature workshop temperature 20±2℃;

[0093] Relative humidity is controlled at 45%-65%;

[0094] The illumination level shall not be less than 500 lux;

[0095] Working table flatness ≤ 0.05mm / m 2 ;

[0096] Regularly check the machine tool accuracy to ensure processing stability.

[0097] This application has the following technical effects:

[0098] It can well realize the repair and interchangeable replacement of broken handles, avoiding the economic loss caused by scrapping of broaches;

[0099] The combination of thermal assembly and mechanical locking has high connection reliability and stability in use;

[0100] Low repair cost, high efficiency and strong reliability;

[0101] The processing conditions are easy to meet the requirements and are convenient for production and manufacturing. BRIEF DESCRIPTION OF THE DRAWINGS

[0102] In order to more clearly illustrate the technical solution of the embodiment of the present invention, the following briefly introduces the drawings required for use in the embodiment:

[0103] Figure 1 A schematic diagram of a rear handle fracture provided in an embodiment of the present application;

[0104] Figure 2 A schematic diagram of the turning and embedding shape of the rear guide portion provided in the embodiment of the present application;

[0105] Figure 3 A schematic diagram of the first rear handle structure provided in an embodiment of the present application;

[0106] Figure 4 A schematic diagram of repairing a broken handle provided in an embodiment of the present application;

[0107] Figure 5 A schematic diagram of screw clamping provided in an embodiment of the present application. DETAILED DESCRIPTION

[0108] The present application provides a method for restoring a circular broach handle after the rear handle is broken, comprising:

[0109] First embodiment:

[0110] S1: Measure and determine the fracture position and size of the original rear handle, use a three-coordinate measuring instrument or precision measuring tools to measure the outer diameter, roundness and coaxiality of the rear guide part, and establish the basic reference data;

[0111] Before repairing the broken handle of the broach, it is necessary to check the broken part (such as Figure 1 ) to ensure the dimensional accuracy and assembly accuracy after repair. Specifically, by using a three-coordinate measuring machine or other precision measuring tools (such as inside and outside diameter micrometers, roundness gauges, etc.), the rear guide part at the fracture position is measured in detail.

[0112] During the measurement process, the following aspects are focused on: first, the outer diameter size of the rear guide part, which requires multi-point measurement at different positions to determine whether there is ellipticity or taper error; second, the roundness measurement, which obtains the roundness error data of the rear guide part by measuring at different sections; finally, the coaxiality measurement, which requires the undamaged part as a reference to measure the coaxiality relationship between the rear guide part and other key parts (such as the leading part, cutting teeth, etc.).

[0113] In addition, it is important to note that the effect of ambient temperature on the measurement results should be considered during the measurement process. The ambient temperature should be kept within the range of 20±2℃, and the workpiece should be ensured to be in thermal equilibrium with the ambient temperature before measurement. For parts with high dimensional accuracy requirements, it is recommended to take the average value of multiple measurements to reduce the impact of random errors.

[0114] The purpose of obtaining these benchmark data is: on the one hand, to provide accurate dimensional basis for subsequent processing technology to ensure that the newly made rear handle can accurately match the original rear guide; on the other hand, it also provides basic data for quality control, and the repair effect can be evaluated by comparing the data before and after the repair. All measurement data should be recorded in detail, and the corresponding measurement record table should be drawn to provide reference for the subsequent process.

[0115] It should be noted that during the measurement process, if other damage (such as cracks, deformation, etc.) is found at the fracture site, it should also be recorded. This information has important reference value for the selection of subsequent repair processes and parameter determination. At the same time, it is recommended to observe and record the morphological characteristics of the fracture surface, which will help analyze the cause of the fracture and provide a basis for preventing similar failures.

[0116] S2: Turning of the guide part after broaching.

[0117] After completing the measurement data collection, the next step is to turn the back guide of the broach. This process is divided into two stages: roughing and finishing, each of which has its own specific process parameters and technical requirements.

[0118] S2 includes:

[0119] S2.1: Use carbide tools for the first rough turning, with feed rate f≤0.15mm / r, cutting depth ap≤1mm, cutting speed 80-100m / min, to remove the surface oxide layer;

[0120] The main purpose of the rough machining stage is to remove the surface oxide layer and uneven parts of the fractured part, so as to create a good foundation for the subsequent fine machining. In this stage, carbide tools are used for machining. It is recommended to use P10-P20 grade carbide inserts, the tool rake angle is 6°-8°, and the back angle is 8°-10°. The machining parameters are controlled within the following range: the feed rate does not exceed 0.15mm / r, the cutting depth is controlled within 1mm, and the cutting speed is maintained at 80-100m / min. The selection of these parameters takes into account both machining efficiency and tool life and machining quality.

[0121] During the rough machining process, special attention should be paid to the following points: First, ensure that the cutting fluid is sufficient and the flow is stable. It is recommended to use a cutting fluid with a concentration of 4%-6% and a flow rate of not less than 20L / min; secondly, intermittent feeding should be adopted, and feeding should be paused every 3-5mm of cutting. This can effectively control the accumulation of cutting heat; finally, the shape and color of the chips should be observed in time. If any abnormality is found, the cutting parameters should be adjusted immediately.

[0122] S2.2: Use ceramic tools for the second finishing, feed rate f≤0.08mm / r, cutting depth ap≤0.2mm, cutting speed 120-150m / min, process the step structure, and reserve 0.02-0.05mm finishing allowance;

[0123] The main task of the finishing stage is to produce a step structure that meets the requirements. Ceramic tools are used in this stage to obtain better machining accuracy and surface quality. It is recommended to use Al2O3-based nitride ceramic blades for ceramic tools, and the radius of the tool tip arc is 0.4mm. The finishing parameters must be strictly controlled: the feed rate does not exceed 0.08mm / r, the cutting depth is controlled within 0.2mm, and the cutting speed is increased to 120-150m / min. Pay special attention to reserving a finishing allowance of 0.02-0.05mm, which is very important for subsequent precision matching.

[0124] During the finishing process, the following aspects need to be focused on: First, the accuracy of the machine tool should be checked before processing, especially the spindle runout error should be controlled within 0.005mm; second, the workpiece should be clamped using a three-jaw chuck with a tail support to ensure stability during the processing; third, the tool wear should be checked regularly, and if the tool is found to be obviously worn, it should be replaced in time to ensure processing accuracy.

[0125] In order to ensure the processing quality, it is recommended to conduct online inspection during the processing. You can use a micrometer to check the runout of the workpiece. At the same time, pay attention to controlling the temperature of the cutting area. It is recommended to conduct a dimensional inspection after each key dimension is processed. If accuracy deviation is found, adjust the processing parameters or replace the tool in time.

[0126] The entire turning process should be carried out in a constant temperature environment, with the workshop temperature maintained at 20±2℃ and the relative humidity controlled between 45%-65%. This can minimize the impact of thermal deformation on machining accuracy. At the same time, it is recommended to record the key parameters of the machining process, including cutting force, spindle current, vibration value, etc. These data are of great reference value for process optimization and quality control.

[0127] S2.3: Process an annular groove on the step structure, with a groove depth of 0.5-1mm, a surface roughness Ra≤1.6μm, and a cylindrical error controlled within 0.01mm;

[0128] like Figure 2 As shown, S2.1-S2.2 respectively perform turning processing on the fractured part, and S2.3 further processes the annular groove (embedded shape) to facilitate the installation of the newly designed first rear handle.

[0129] S3: design and process the first rear handle according to the step structure size, and arrange three through-threaded holes at intervals of 120° along the circumference of the circular broach rear guide portion, each threaded hole having a 90° or 120° countersunk hole structure;

[0130] After the step structure of the rear guide is processed, it is necessary to design and process the first rear handle (such as Figure 3 ), and design and process the threaded fixing structure. This step requires high precision and directly affects the reliability of the final assembly.

[0131] The first step is to design the first rear handle. According to the previously measured step structure size, the matching part of the first rear handle is designed. The design of the matching surface needs to take into account the requirements of thermal fit, the surface roughness requirement is Ra0.8, and the coaxiality error is controlled within 0.01mm. The material of the rear handle is 42CrMo, and the hardness after heat treatment is required to be HRC28-32 after quenching and tempering to ensure sufficient strength and good toughness.

[0132] When machining the first rear handle, a CNC lathe is used for rough machining and fine machining. The rough machining allowance is controlled at 0.3-0.5mm, and the fine machining is carried out twice, with the first fine machining allowance being 0.1mm and the second fine machining allowance being 0.02-0.03mm. The cylindrical error of the mating surface is required to be controlled within 0.005mm, and the surface hardness uniformity deviation is not more than ±2HRC.

[0133] The arrangement of threaded holes is another key point in this step. There are three threaded holes arranged every 120° in the circumferential direction. This uniform arrangement can ensure the uniform distribution of the fixing force. The following points should be paid special attention to in the processing of threaded holes: the verticality error between the drilling centerline and the axis should be controlled within 0.02mm; the position accuracy error of the threaded holes should be controlled within ±0.05mm; the angle distribution error of the three threaded holes should not exceed ±0.5°.

[0134] Each threaded hole is designed with a countersunk hole structure, and the countersunk angle can be selected at 90° or 120°. The specific angle selection should take into account the type and force of the screw used. The processing of the countersunk hole requires the use of a special countersunk drill. The countersunk depth must ensure that the screw head is completely buried, but it cannot be too deep to affect the strength. The surface roughness of the countersunk hole is required to be Ra1.6 to ensure a good fit with the screw head.

[0135] The processing steps of threaded holes are: first use the center drill to locate, then use the drill to drill through the hole, then use the reamer to finely ream, and finally process the thread and countersunk. The thread processing uses an extrusion tap to obtain better thread surface quality. The thread accuracy grade requires 6H, and the effective thread engagement length is not less than 1.5 times the thread diameter.

[0136] During the processing, the following points need to be noted: low speed and large feed should be used when drilling to prevent drilling deviation; sufficient cutting fluid lubrication should be ensured during the tapping process, and chip breaking should be used; the processing dimensions of all holes must be strictly in accordance with the requirements of the drawings, and inspection records must be kept.

[0137] Finally, the threaded holes are fully inspected, including: using a thread gauge to check the thread accuracy, using a universal tool microscope to check the countersunk angle, and using a three-coordinate measuring machine to check the position and verticality of the hole. At the same time, it is recommended to perform a thread torque test on each threaded hole to ensure that the expected tightening effect can be achieved during assembly.

[0138] S4: placing the first rear handle into a medium temperature tempering furnace and heating it to 350° C., keeping the temperature for 15-20 minutes, and controlling the temperature uniformity within the range of ±5° C., wherein the first rear handle is a re-customized rear handle;

[0139] After the first rear handle is processed, the next step is the heat assembly and fixing process. This process includes three main steps: heat treatment, heat fit assembly and thread fixing, and each step requires strict control of process parameters.

[0140] The first is the heat treatment process. Put the processed first back handle into the medium temperature tempering furnace for heating. The tempering furnace needs to be preheated in advance to ensure temperature uniformity. During the heating process, the temperature rise rate is controlled at 100℃ / hour to avoid stress concentration caused by rapid temperature rise. When the temperature reaches 350℃, keep it warm for 15-20 minutes. During this period, the furnace temperature fluctuation must be controlled within the range of ±5℃. In order to monitor the uniformity of temperature, it is recommended to install temperature sensors at different positions of the workpiece to record temperature data in real time.

[0141] The control of heat treatment environment is also very important. The furnace should maintain good hot air circulation, and forced convection can be used to ensure that all parts of the workpiece are heated evenly. At the same time, to prevent the surface of the workpiece from oxidation, protective gas (such as nitrogen or argon) can be introduced, and the gas purity should not be less than 99.99%.

[0142] S5: Use a special centering fixture for heat-fit assembly, the leveling error of the fixture base is controlled within 0.02mm / 1000mm, and the centering accuracy is ≤0.01mm;

[0143] In the hot-fit assembly process, a special centering fixture is used for operation. The design of the fixture needs to take into account the factors of thermal expansion and contraction, and the material is a special alloy steel with a small thermal expansion coefficient. The leveling of the fixture base is the key, and a precision level is used for adjustment to ensure that the leveling error is controlled within 0.02mm / 1000mm. The centering device adopts the three-point positioning principle and cooperates with the photoelectric sensor to achieve a centering accuracy of ≤0.01mm.

[0144] The assembly process needs to be fast and accurate. When the first rear handle reaches the specified temperature, it is quickly removed from the tempering furnace and transferred to the assembly station using a special heat-insulating fixture. Before assembly, the cleanliness of the two mating surfaces must be confirmed again to ensure that there are no impurities such as oil, dust, etc. During assembly, force must be applied evenly to avoid eccentricity or tilting. The entire hot assembly process is recommended to be completed within 3 minutes to fully utilize the thermal expansion difference.

[0145] Figure 4 This is a schematic diagram after repair.

[0146] S6: After natural cooling, apply medium-strength thread locking agent on the threaded connection surface, screw the three screws through the threaded holes respectively, and make the ends of the screws extend into the annular groove for limit fixation. Use a torque wrench to tighten in steps, and control the screw tightening torque error within ±5%.

[0147] After the workpiece cools down to room temperature naturally (usually takes 4-6 hours), proceed to the thread fixing step. First, check the state of the threaded hole to ensure that there is no deformation or damage. Apply medium-strength thread locker evenly on the threaded connection surface. It is recommended to use anaerobic thread locker with a temperature resistance of not less than 150°C. The amount of application should be moderate to avoid excessive or insufficient application.

[0148] The screw installation adopts a step-by-step tightening method. In the first step, screw in the three screws separately, but do not tighten them completely, so that the ends of the screws just extend into the annular groove. In the second step, use a calibrated torque wrench to pre-tighten in a diagonal cross order, and control the torque to 60% of the final tightening torque. In the third step, perform the final tightening again in the same order to reach the specified tightening torque value. During the entire tightening process, the torque error must be controlled within ±5%. Figure 5 The figure is a schematic diagram of the assembly of the screws, wherein the first rear handle is marked as 1, the screw is marked as 2, and the rear guide of the broach is marked as 3.

[0149] To ensure the quality of fastening, it is recommended to use the torque-angle composite control method during the fastening process, and record the fastening torque and rotation angle data of each screw. After fastening, the screws should be marked for subsequent inspection. It is also recommended to wait for the thread locker to fully cure (usually 24 hours at room temperature) before proceeding with subsequent operations.

[0150] Finally, the assembled parts are fully inspected, including the measurement and recording of coaxiality, runout, screw tightening torque and other parameters. It is recommended to conduct a re-inspection 24 hours after the first assembly to confirm the stability of various performance indicators. All test data must be recorded in detail as a basis for quality traceability.

[0151] The cooperation between the first rear handle and the step structure adopts the following parameters:

[0152] diameter The following uses H7 / u6 fit, with interference 0.015-0.025mm;

[0153] diameter Adopt H7 / u7 fit, interference 0.020-0.032mm;

[0154] diameter The above adopts H7 / u8 fit, with interference 0.025-0.040mm;

[0155] The mating surfaces are inspected with blue light, and the contact area ratio is ≥85%, with evenly distributed contact points.

[0156] The screw selection and installation includes:

[0157] Use screws with strength grade 12.9;

[0158] For diameter For screws, use a tightening torque of 25-30 N·m;

[0159] For diameter For screws, use a tightening torque of 45-50 N·m;

[0160] For diameter For screws, use a tightening torque of 70-80 N·m;

[0161] The thread clearance is 6g / 6H.

[0162] Second embodiment:

[0163] S1: Measure and determine the fracture position and size of the original rear handle, use a three-coordinate measuring instrument or precision measuring tools to measure the outer diameter, roundness and coaxiality of the rear guide part, and establish the basic reference data;

[0164] S2: Turning of the guide part after the broach, including:

[0165] S2.1: Use carbide tools for the first rough turning, with feed rate f≤0.15mm / r, cutting depth ap≤1mm, cutting speed 80-100m / min, to remove the surface oxide layer;

[0166] S2.2: Use ceramic tools for the second finishing, feed rate f≤0.08mm / r, cutting depth ap≤0.2mm, cutting speed 120-150m / min, process the step structure, and reserve 0.02-0.05mm finishing allowance;

[0167] The description of S1-S2 is the same as that of the first embodiment and will not be repeated here.

[0168] S3: Using micron-level stereolithography technology, a transition connection layer is printed on the fracture surface using epoxy acrylate photosensitive resin material, wherein the laser power is controlled at 80-100 mW and the scanning speed is 200-300 mm / s;

[0169] Among them, printing the transition connection layer on the fracture surface includes: printing a honeycomb basic grid with a unit size of 50-100 microns, and the structure density distribution is gradient, gradually decreasing from the inside to the outside; setting a micro-barb structure with a height of 15-25 microns;

[0170] After the turning of the rear guide is completed, the next key step is to establish the transition layer on the fracture surface (after turning, the fracture surface is relatively smooth and it is easy to set the transition layer). This step uses micron-level stereolithography technology, which is a high-precision additive manufacturing process that can achieve precise structural control at the micro scale.

[0171] First, before photolithography, the fracture surface needs to be specially treated. This includes surface cleaning, plasma activation, and coating of bottom treatment agent. The cleaning process requires ultrasonic cleaning, combined with a specific cleaning agent to remove surface oil and oxides; plasma activation is to increase surface energy and enhance the adhesion of subsequent materials; the selection of the bottom treatment agent should take into account the compatibility with the photosensitive resin.

[0172] In terms of material selection, epoxy acrylate photosensitive resin is used, which has good mechanical properties and processing properties. The selection criteria of the resin include: viscosity between 200-300mPa·s, curing shrinkage less than 3%, and elongation at break greater than 15%. In order to improve the performance of the material, nano-scale reinforcing agents such as nano-silicon oxide or carbon nanotubes can be added to the resin, and the addition ratio is controlled between 0.5-1%.

[0173] In the photolithography process, the control of laser power is crucial, and the power needs to be strictly controlled within the range of 80-100mW. Too high power will cause excessive cross-linking or local overheating of the material, while too low power cannot ensure sufficient curing. The scanning speed is set at 200-300mm / s. This speed range can ensure good forming quality and maintain high processing efficiency.

[0174] When printing the honeycomb base grid, a special scanning strategy is used. First, the contour scan, then the internal filling, and finally the compensation scan. The unit size is controlled between 50-100 microns. This size range can ensure both the strength of the structure and good flexibility. The gradient change design of the structure density is very critical. The density distribution that gradually decreases from the inside to the outside can better meet the stress transfer requirements.

[0175] The design and production of the micro-barb structure is the most delicate part of the whole process. The height of the barb is controlled at 15-25 microns, the angle is designed to be 60°-75°, and the spacing is evenly distributed. These barbs not only increase the mechanical bite force, but also produce microscopic deformation when subjected to force, providing additional stress buffering.

[0176] During the printing process, the following parameters need to be strictly controlled: the ambient temperature is maintained at 23±1℃, the relative humidity is controlled at 40%-60%, and the dustproof level is required to reach Class 1000. The printing process should be carried out under yellow light to avoid the influence of ambient light on the photosensitive resin. At the same time, the entire work surface should be kept level and the vibration should be controlled below 0.1μm.

[0177] In terms of quality control, each completed layer of the structure must be inspected in real time, including using a microscope to observe the integrity of the structure and using a profilometer to measure the surface roughness. If defects are found, the process parameters must be adjusted immediately or the layer must be reprinted. It is recommended to calibrate the key parameters of the lithography system at regular intervals, including laser power, spot size, scanning accuracy, etc.

[0178] Finally, post-processing after printing is also very important, including the removal of residual monomers and UV post-curing. The post-curing process should be carried out in a nitrogen-protected environment, with the temperature controlled at 60-80°C for 2-4 hours. This ensures that the material achieves the best mechanical properties. Key parameters should be recorded throughout the process to provide a basis for quality traceability.

[0179] It should be noted that the original fracture surface is usually irregular, and there may be oxide layers, burrs, etc. on the surface. Therefore, S2 turning can: remove the surface oxide layer, provide a clean base surface, and provide a regular machined surface for subsequent precise processing. Then in S3, photolithography and printing are performed on the processed regular surface, which can: improve the accuracy and controllability of the photolithography process and ensure the uniformity of the honeycomb base grid.

[0180] S4: stacking 42CrMo alloy sheets layer by layer using a layered physical manufacturing technology, wherein the thickness of the alloy sheets starts from 0.1 mm and increases layer by layer to 0.2 mm;

[0181] In the process of manufacturing the first rear handle, the use of layered solid manufacturing technology is an innovative method. This technology builds the part by stacking 42CrMo alloy sheets layer by layer, which can achieve good mechanical properties and microstructure control.

[0182] The first step is the preparation of alloy flakes. 42CrMo alloy flakes need to be produced through precision rolling process, which requires strict control of chemical composition: carbon content 0.38-0.45%, chromium content 0.9-1.2%, molybdenum content 0.15-0.25%. The temperature needs to be strictly controlled during the rolling process, maintained between 850-900℃, and the pass thinning rate is controlled at 15-20% to ensure the uniformity of the sheet's structure and mechanical properties.

[0183] The thickness of the sheet is controlled by a progressive design, starting with a 0.1mm thick sheet at the bottom layer, and then increasing layer by layer in increments of 0.01mm until it reaches 0.2mm. This progressive design can achieve a uniform transition of stress while ensuring structural strength. The surface roughness of each layer of sheet is required to be Ra0.4, and the flatness error is controlled within 0.005mm.

[0184] The interface treatment during the stacking process is crucial. Each layer of thin film needs to be surface activated before stacking, including two steps: plasma cleaning and chemical activation. The plasma cleaning parameters are: power 300-400W, processing time 30-40 seconds; chemical activation uses a special activation liquid, and the immersion time is controlled at 20-30 seconds. This ensures that the interlayer bonding strength reaches more than 90% of the parent material strength.

[0185] During the lamination process, a precision positioning system is used for alignment. The positioning system includes a laser guide device and a mechanical positioning device, and the positioning accuracy is required to be ≤0.01mm. After each layer of thin film is placed, a pressure sensor is used to detect the uniformity of pressure distribution, and the pressure is controlled within the range of 5-7MPa. At the same time, the entire lamination process is carried out in a vacuum environment, and the vacuum degree is maintained above 10^-3Pa.

[0186] The interlayer bonding adopts diffusion welding process, and the welding parameters are: temperature 1050-1100℃, pressure 8-10MPa, and insulation time 30-40 minutes. In order to prevent oxidation, the entire welding process is carried out under the protection atmosphere of high-purity hydrogen (purity ≥99.999%). After each layer of welding is completed, the bonding quality should be tested with an ultrasonic flaw detector to ensure that there are no defects such as inclusions and pores.

[0187] The following parameters need to be strictly controlled during the stacking process: ambient temperature 23±1℃, relative humidity 40-60%, work surface levelness error ≤0.02mm / 1000mm. An intermediate inspection should be carried out every 3-5 layers, including dimension measurement, flatness detection and ultrasonic flaw detection. If any problems are found, the process parameters should be adjusted in time.

[0188] In terms of quality control, a complete process parameter recording system should be established, including the batch number of each layer of thin film, surface treatment parameters, welding parameters, etc. At the same time, it is recommended to reserve sampling positions during the stacking process for subsequent mechanical property testing and metallographic analysis. After each key part is completed, X-ray flaw detection should be carried out to ensure internal quality.

[0189] Finally, the overall heat treatment after superposition is also very important. The heat treatment process includes: normalizing (880-900℃) + quenching (840-860℃, oil cooling) + tempering (550-580℃) to obtain the ideal organizational structure and mechanical properties. The hardness after heat treatment is required to be HRC28-32, the tensile strength is ≥900MPa, and the section shrinkage is ≥45%.

[0190] Figure 4 This is a schematic diagram of repairing a broken handle.

[0191] S5: Modified epoxy resin structural adhesive is used to bond the layers, with the amount of adhesive applied per layer being 0.15-0.20g / cm 2 ;

[0192] The pressing pressure is 3-5MPa, and the pressing force increases by 10% layer by layer;

[0193] The inter-layer alignment accuracy is ≤0.02mm, and the vacuum degree during stacking is ≤10Pa;

[0194] In the process of layering and stacking 42CrMo alloy sheets, interlayer bonding is the key link to ensure the overall performance. This process uses modified epoxy resin structural adhesive for bonding, which requires strict control of process parameters and environmental conditions.

[0195] The first is the selection and preparation of structural adhesive. Two-component modified epoxy resin structural adhesive is used, and the ratio of the main agent to the curing agent is required to be precisely controlled at 100:30 (weight ratio). The performance index requirements of the structural adhesive are: viscosity (25℃) 8000-12000mPa·s, usable time (25℃) 40-60 minutes, shear strength ≥25MPa, and temperature resistance not less than 120℃. In order to improve the toughness of the structural adhesive, nano-scale toughening agent can be added, and the addition ratio is controlled at 2-3%.

[0196] The glue application process requires special attention to the amount control. The glue application amount for each layer is strictly controlled at 0.15-0.20g / cm 2 This range can ensure sufficient bonding strength while avoiding excessive adhesive layer thickness accumulation. Gluing is applied using precise quantitative coating equipment, and the coating uniformity deviation is controlled within ±5%. When applying glue, be careful to avoid positioning holes and key functional surfaces, and partial shielding can be used for protection.

[0197] The lamination process adopts a progressive pressurization method. The initial pressure is set at 3MPa. As the number of layers increases, the pressure increases by 10% layer by layer, but does not exceed the upper limit of 5MPa. This progressive pressurization can effectively discharge the excess adhesive layer while ensuring that the bottom layer will not be deformed due to overpressure. The pressure is applied using a multi-point synchronous pressurization system, and the pressure uniformity deviation is controlled within ±3%.

[0198] To ensure that the inter-layer alignment accuracy is ≤0.02mm, a dual-path laser alignment system and mechanical positioning are combined. The resolution of the laser alignment system reaches 0.001mm, and the deviation is monitored in real time through CCD images. Mechanical positioning uses precision positioning pins, the cylindrical error of the positioning pins is controlled within 0.002mm, and the matching clearance is 0.005-0.008mm.

[0199] The control of vacuum degree is an important factor to ensure the quality of bonding. The entire stacking process is carried out in a vacuum chamber, and the vacuum degree is required to be ≤10Pa. The vacuuming process is divided into two stages: the first stage is to quickly vacuum to 100Pa, and the second stage is to slowly vacuum to the target value to avoid sudden vacuuming and causing bubbles. At the same time, a desiccant is set in the vacuum chamber to control the environmental humidity.

[0200] The temperature control system adopts zone heating, and the working temperature is maintained at 23±2℃. In order to prevent temperature fluctuations from affecting the bonding quality, a water circulation constant temperature device is installed on the outer wall of the vacuum chamber. At the same time, the temperature of each area is monitored in real time through thermocouples, and adjustments are made in time when abnormalities are found.

[0201] After stacking, it needs to be cured naturally for 24 hours, and the curing environment temperature is controlled at 23±2℃ and the relative humidity is 45-65%. After curing, the final size inspection and mechanical property test are carried out to ensure that the product quality meets the design requirements.

[0202] S6: Perform stress release heat treatment at a temperature of 200-250° C. for 2-3 hours, and cool with the furnace;

[0203] S7: After cooling, three through threaded holes are arranged at intervals of 120° along the circumference, each threaded hole has a 90° or 120° countersunk hole structure, and three screws are screwed in through the threaded holes respectively.

[0204] The modified epoxy resin structural adhesive adopts a gradient formula:

[0205] The bottom layer uses a high-toughness formula with a shear strength of ≥25MPa;

[0206] The middle layer uses a standard formula with a temperature resistance of -40°C to 150°C;

[0207] The surface layer uses a high-strength formula with a curing time of 120 minutes (120°C);

[0208] The bonding strength shall not be less than 85% of the parent material strength.

[0209] After molding, the following tests are performed:

[0210] Ultrasonic flaw detection is carried out every 5 layers;

[0211] After final molding, X-ray inspection is carried out to ensure that there are no internal defects;

[0212] Test the surface hardness, which is required to reach more than 90% of the raw material;

[0213] Perform dynamic balance test and the dynamic balance level reaches G2.5.

[0214] Third embodiment:

[0215] S1: Measure and determine the fracture position and size of the original rear handle, use a three-coordinate measuring instrument or precision measuring tools to measure the outer diameter, roundness and coaxiality of the rear guide part, and establish the basic reference data;

[0216] S2: Turning of the guide part after the broach, including:

[0217] S2.1: Use carbide tools for the first rough turning, with feed rate f≤0.15mm / r, cutting depth ap≤1mm, cutting speed 80-100m / min, to remove the surface oxide layer;

[0218] S2.2: Use ceramic tools for the second finishing, feed rate f≤0.08mm / r, cutting depth ap≤0.2mm, cutting speed 120-150m / min, process the step structure, and reserve 0.02-0.05mm finishing allowance;

[0219] S3: placing the first rear handle into a medium temperature tempering furnace and heating it to 350° C., keeping the temperature for 15-20 minutes, and controlling the temperature uniformity within the range of ±5° C., wherein the first rear handle is a re-customized rear handle;

[0220] S4: three through threaded holes are arranged at intervals of 120° along the circumference, each threaded hole has a 90° or 120° countersunk hole structure, and three screws are respectively screwed in through the threaded holes for fixing;

[0221] The specific description of S1-S4 is detailed in Example 1 and will not be repeated here.

[0222] S5: Designing an elastic compensation structure between the first rear handle and the original rear guide, including:

[0223] It uses three elastic diaphragms evenly spaced at 120°, made of 42CrMo alloy steel with a hardness of HRC32-36;

[0224] The thickness of the diaphragm is precisely controlled at 1.5-2mm, and the thickness ratio between the inner and outer ends is 1.2:1;

[0225] The effective working length is 0.4-0.5 times the diameter of the rear handle;

[0226] The elastic compensation structure design between the first rear handle and the original rear guide is the key to ensure the overall performance. This elastic compensation structure adopts a specially designed diaphragm system, which can effectively alleviate the stress concentration during the working process and improve the overall reliability.

[0227] The first is the material selection and heat treatment of the elastic diaphragm. 42CrMo alloy steel is selected as the diaphragm material, and its chemical composition is strictly controlled: carbon content 0.40-0.45%, chromium content 0.9-1.2%, molybdenum content 0.15-0.25%. The heat treatment process includes: tempering treatment (quenching temperature 840-860℃, tempering temperature 520-540℃) and aging treatment (200℃×2h), and finally obtains HRC32-36 hardness. The organizational requirements after heat treatment: tempered troostite + dispersed carbide, grain size level 8-9.

[0228] The structural design of the diaphragm adopts a 120° uniform distribution to ensure uniform stress. The circumferential positioning of the three diaphragms adopts precision positioning grooves, and the positioning accuracy is controlled within 0.01mm. Each diaphragm is precision machined, with a dimensional tolerance grade of IT6 and a form and position tolerance band of 0.01mm. The geometric shape of the diaphragm adopts a gradual curve design to obtain the best stress distribution.

[0229] The control of diaphragm thickness is the key to ensure performance. The overall thickness is controlled within the range of 1.5-2mm, and the inner and outer ends are designed with a thickness ratio of 1.2:1. This gradual design can make the stress distribution more reasonable and improve fatigue life. High-precision CNC milling machines are used for processing, and special fixtures are used to control the thickness tolerance within ±0.01mm. The surface roughness requirement is Ra0.4, and the surface treatment adopts nitriding + polishing process.

[0230] The design of the effective working length is closely related to the rear shank diameter, which is controlled at 0.4-0.5 times the rear shank diameter. This ratio is the optimal value determined by finite element analysis and experimental verification, which can provide appropriate elastic deformation while ensuring sufficient rigidity. The working length is processed by a profile grinder, and the profile error is controlled within 0.005mm.

[0231] It is important to accurately control the installation position of the diaphragm. The coaxiality of the installation surface is required to be 0.01mm, and the verticality is required to be 0.02mm. Special tooling is used during installation to ensure that the three diaphragms are evenly stressed and the preload deviation does not exceed 5%. After installation, the flatness of the diaphragm in the free state should be tested to ensure that there is no initial deformation.

[0232] Quality control of the manufacturing process includes the following aspects:

[0233] Material inspection upon entry: composition analysis, metallographic inspection, mechanical properties test;

[0234] Process control: 100% detection of key dimensions and online measurement of geometric and positional tolerances;

[0235] Heat treatment process control: temperature uniformity ±5℃, hardness distribution detection;

[0236] Assembly process control: preload force measurement, coaxiality measurement;

[0237] Each diaphragm is subjected to the following performance tests:

[0238] Static stiffness test: linearity deviation of loading displacement curve ≤3%;

[0239] Dynamic fatigue test: no cracks or permanent deformation after 106 cycles;

[0240] Frequency response test: The natural frequency must meet the design requirements;

[0241] To ensure assembly quality, establish detailed assembly process procedures:

[0242] Clean all contact surfaces to ensure they are free of oil and impurities;

[0243] Check the geometric accuracy of the mounting surface;

[0244] Install the diaphragms in the order marked;

[0245] Use a torque wrench for even tightening;

[0246] Measure key assembly parameters;

[0247] Conduct functional testing;

[0248] Finally, the overall performance of the assembled elastic compensation structure is verified, including:

[0249] Static displacement test;

[0250] Dynamic response testing;

[0251] Temperature effect test;

[0252] Reliability assessment;

[0253] All manufacturing and testing data must be fully recorded and product files must be established to ensure traceability. At the same time, detailed assembly and maintenance procedures must be formulated to ensure the standardization of subsequent use and maintenance.

[0254] Among them, S1-S4 is used to measure and establish benchmark data, and obtain regular step structures and prefabricated screw connection structures through turning. Finally, the first rear handle is heat treated.

[0255] S5 introduces an elastic compensation structure: an elastic diaphragm is arranged between the first rear handle and the original rear guide.

[0256] S1-S4 complete the basic processing and connection preparation, and S5 adds an elastic compensation mechanism on this basis to provide dynamic compensation capability. Therefore, the screw connection provides basic fixation, while the elastic compensation structure provides dynamic adjustment capability, and the bearing system provides motion support.

[0257] S6: Setting a bearing support system, including:

[0258] Use double-row angular contact ball bearings with P4 grade precision;

[0259] The bearing preload is adjusted by precision nuts and controlled between 5% and 8% of the dynamic load.

[0260] The bearing seat adopts 40Cr quenched and tempered steel integral design;

[0261] The radial clearance is controlled at 0.01-0.015mm;

[0262] The design and installation of the bearing support system is a precise link in the entire device, which directly affects the running accuracy and service life. This system needs to comprehensively consider multiple factors such as load characteristics, temperature effects and assembly process.

[0263] The first step is the selection of bearings. Double-row angular contact ball bearings with P4 precision are selected, and the contact angle is 25°. This design can withstand both radial loads and axial loads. The bearing steel material is GCr15SiMn, with specific requirements: carbon content 0.95-1.05%, chromium content 1.40-1.65%, hardness HRC62-64. The purity of the bearing steel is required to be ≤-II level, and the carbide uniformity is ≤3 level to ensure the reliability of high-speed operation.

[0264] The control of bearing preload is a key process parameter. The preload is adjusted by precision nuts to keep it between 5% and 8% of the dynamic load. The preload is measured by combining the strain gauge method and the torque method. The strain gauge accuracy level is 0.1. The adjustment process is divided into two stages: coarse adjustment and fine adjustment:

[0265] Rough adjustment: Use a special torque wrench to make preliminary adjustments according to the calculated theoretical torque value.

[0266] Fine-tuning: Fine-tune the preload to the optimal state through bearing temperature rise and vibration tests

[0267] The bearing seat is designed with a 40Cr quenched and tempered steel monolithic structure. The heat treatment process of the material is: quenching and tempering (quenching temperature 850℃, tempering temperature 580℃), to obtain a hardness of HRC28-32. The main dimensional tolerance grade of the monolithic design is IT6, and the geometric tolerance zone is 0.01mm. The structural features of the bearing seat include:

[0268] The cylindricality error of the bearing mounting surface is ≤0.005mm;

[0269] End face verticality error ≤ 0.008mm;

[0270] The surface roughness of the mating surface is Ra0.4;

[0271] Design effective lubrication channels and sealing structures;

[0272] The radial clearance is controlled by precise matching, and the clearance is controlled within the range of 0.01-0.015mm. This range is the optimal value after considering factors such as temperature changes and load deformation. The following method is used to measure the clearance:

[0273] Use a micrometer to measure static clearance at room temperature;

[0274] Use eddy current sensors to monitor dynamic clearance during operation;

[0275] Measure the clearance variation at different temperatures;

[0276] The control of assembly process is also very important:

[0277] Clean and inspect all parts;

[0278] Geometric accuracy detection of bearing seat mounting surface;

[0279] Pre-assembly and clearance inspection of bearings;

[0280] Cleanliness inspection of lubrication oil system;

[0281] Installation of seals;

[0282] Adjustment and inspection of preload force;

[0283] Commissioning and performance testing;

[0284] The design of the lubrication system takes into account the following factors:

[0285] Using ISO VG32 high-speed bearing oil;

[0286] The oil circuit design ensures sufficient lubrication;

[0287] Set up an oil level observation window;

[0288] Equipped with temperature monitoring device

[0289] The monitoring system configuration includes:

[0290] Temperature sensor: accuracy ±0.1℃;

[0291] Vibration sensor: frequency range 0.1-10kHz;

[0292] Displacement sensor: resolution 0.1μm;

[0293] Online monitoring system;

[0294] Quality control measures include:

[0295] Bearing arrival inspection: size, accuracy, surface quality;

[0296] Bearing seat machining process control;

[0297] Recording of key parameters of the assembly process;

[0298] Operation test data collection and analysis;

[0299] Special Notes:

[0300] The assembly environment temperature is controlled at 20±2℃;

[0301] Relative humidity is controlled at 45-65%;

[0302] Dustproof level reaches Class 1000;

[0303] Assembly tools must be calibrated;

[0304] Maintenance recommendations:

[0305] Check the lubricant quality regularly;

[0306] Monitor bearing temperature rise and vibration;

[0307] Record operating parameters;

[0308] Develop a preventive maintenance plan;

[0309] All assembly processes and debugging data must be recorded in detail to establish a complete technical file. At the same time, an emergency plan must be formulated to deal with possible abnormal situations.

[0310] S7: Perform assembly, including:

[0311] Using a special positioning tool to install the elastic diaphragm, the position of the elastic diaphragm and the position of the threaded hole are arranged alternately;

[0312] Control the circumferential distribution error of the three diaphragms to be ≤0.5°;

[0313] The verticality between the diaphragm and the connection surface is ≤0.02mm;

[0314] The installation torque is controlled at 20-25N·m;

[0315] The installation of the elastic diaphragm is a key link in the entire assembly process, which requires precise control of positioning, torque and geometric parameters to ensure the stability and reliability of the system.

[0316] The first step is the design and calibration of a special positioning fixture. The positioning fixture is made of high-strength aluminum alloy (7075-T6) and anodized to improve surface hardness and wear resistance. The main features of the fixture include:

[0317] The flatness error of the reference surface is ≤0.005mm;

[0318] The cylindricality error of the positioning pin hole is ≤0.003mm;

[0319] Angle indexing plate accuracy 0.1°;

[0320] Integrated torque monitoring system;

[0321] The preparation work before installation is very important:

[0322] Clean all contact surfaces with a dust-free cloth dipped in isopropyl alcohol;

[0323] Check the surface condition of the elastic diaphragm to ensure there are no scratches or deformation;

[0324] Verify the accuracy of positioning tooling;

[0325] Prepare a calibrated torque wrench;

[0326] Check the specifications and condition of all fasteners;

[0327] The installation of the elastic diaphragm adopts the principle of staggered arrangement, staggered 120° with the threaded hole. This arrangement can optimize stress distribution and improve overall rigidity. Specific installation steps:

[0328] Adjust the positioning tool to a horizontal position with an error of ≤0.02mm / 1000mm;

[0329] Install the first diaphragm as a reference;

[0330] Use the angle indexing device to determine the position of the second and third diaphragms;

[0331] Install piece by piece while monitoring the circumferential distribution error;

[0332] The control of circumferential uniform error is very important, and the requirement is ≤0.5°. The following methods are used to ensure installation accuracy:

[0333] Use high-precision photoelectric angle sensor for real-time monitoring;

[0334] Use a three-coordinate measuring machine for position verification;

[0335] A position compensation mechanism is provided to enable fine adjustment;

[0336] Real-time data logging for each installation step;

[0337] The verticality between the diaphragm and the connection surface is controlled within 0.02mm, and the following measures are adopted:

[0338] Use precision level for real-time monitoring;

[0339] Install a special support frame to provide stable support;

[0340] Verify verticality using multi-point measurement;

[0341] Use shims to make fine adjustments if necessary;

[0342] The control range of the installation torque is 20-25N·m. This process requires special attention:

[0343] Use a digital torque wrench with an accuracy level of ±2%;

[0344] Adopt step-by-step fastening method:

[0345] Step 1: reach 40% of the target torque;

[0346] Step 2: reach 70% of the target torque;

[0347] Step 3: reaching the final torque value;

[0348] The torque error of each fastening point is controlled within ±1N·m;

[0349] Quality control measures during installation:

[0350] Create a detailed installation checklist;

[0351] Record the installation parameters of each diaphragm;

[0352] Real-time monitoring of key geometric parameters;

[0353] Take photos and archive each assembly step;

[0354] Inspection items after installation:

[0355] Diaphragm circumferential position measurement;

[0356] Full-circle verticality detection;

[0357] Torque value review;

[0358] Diaphragm prestress state inspection;

[0359] Overall coaxiality measurement;

[0360] Special considerations:

[0361] The installation environment temperature is maintained at 20±2℃;

[0362] Avoid direct sunlight that may cause uneven temperatures;

[0363] Prevent contamination from dust and impurities;

[0364] Operators must undergo special training;

[0365] Assembly record requirements:

[0366] Record the serial number of each diaphragm;

[0367] Record installation torque and angle data;

[0368] Record the model and accuracy of the testing instrument;

[0369] Record operator and inspector information;

[0370] Create complete assembly files;

[0371] After the installation is complete, a functional test is required:

[0372] Static displacement test;

[0373] Vibration characteristics test;

[0374] Stiffness testing;

[0375] Verification of prestress state;

[0376] All test data must be fully recorded and compared with the design requirements to ensure that they meet the technical specifications. At the same time, a detailed maintenance plan should be formulated to ensure the long-term stable operation of the system.

[0377] S8: Setting up the bearing system, including:

[0378] The bearing seat aperture accuracy requirement is H6;

[0379] The interference of the outer ring of the bearing is 0.01-0.02mm;

[0380] The verticality between the bearing end face and the seat is ≤0.005mm;

[0381] The preload force is controlled by a special torque wrench.

[0382] The assembly process of the bearing system is a precision work that requires strict control of the matching accuracy, assembly process and preload force to ensure the operating performance and service life of the bearing system.

[0383] The first is the processing requirements of the bearing seat. The bearing seat aperture adopts H6 grade precision, and the specific processing technology is as follows:

[0384] Rough machining allowance 0.3-0.5mm;

[0385] Processing procedures of fine milling → fine boring → grinding;

[0386] The final size tolerance band width is between 10-14μm;

[0387] Cylindricity error is controlled within 0.004mm;

[0388] Aperture surface roughness Ra0.4;

[0389] The interference fit between the bearing outer ring and the bearing seat is controlled at 0.01-0.02mm, which requires precise dimensional measurement and temperature control:

[0390] Use a three-point inside micrometer to measure the bearing housing bore diameter;

[0391] Use an outside micrometer to measure the outer ring diameter of the bearing;

[0392] The measurement environment temperature is controlled at 20±0.5℃;

[0393] The cleanliness level of the mating surface shall not be lower than NAS6;

[0394] The verticality requirement between the bearing end face and the seat is ≤0.005mm, which requires the following measures:

[0395] Process control:

[0396] The reference surface can be processed by clamping in one step;

[0397] Use a precision vertical milling machine;

[0398] Use precision measuring instruments for online measurement;

[0399] Detection method:

[0400] Use a high-precision dial indicator;

[0401] Measured by roundness meter;

[0402] Multi-point sampling verification;

[0403] The preload force is controlled by a special torque wrench, with specific requirements:

[0404] The torque wrench accuracy level is 0.5;

[0405] Minimum graduation value 0.1N·m;

[0406] With overload protection function;

[0407] Equipped with digital display of torque value;

[0408] Control of assembly process:

[0409] Cleaning and inspection of bearing seats;

[0410] Use a dust-free cloth to clean;

[0411] Check surface condition;

[0412] Measure critical dimensions;

[0413] Bearing installation preparation;

[0414] Preheat the bearing temperature to 30-35℃;

[0415] Check the bearing rotation flexibility;

[0416] Prepare special installation tools;

[0417] Bearing installation process;

[0418] Hydraulic assembly method is adopted;

[0419] Control assembly speed ≤5mm / min;

[0420] Monitor changes in assembly forces;

[0421] Preload adjustment;

[0422] Step-by-step loading method;

[0423] Real-time monitoring of bearing temperature rise;

[0424] Record adjustment process data;

[0425] The performance parameters of the elastic diaphragm include:

[0426] Material elastic modulus: 210GPa;

[0427] Yield strength: ≥835MPa;

[0428] Fatigue strength: ≥400MPa;

[0429] Elastic deformation: 0.2-0.3mm;

[0430] Bearing preload: 2000-3000N.

[0431] The restored inlay handle meets the following criteria:

[0432] Static detection:

[0433] Radial runout ≤ 0.01mm;

[0434] Axial runout ≤ 0.015mm;

[0435] Coaxiality ≤ 0.02mm;

[0436] Angle swing ≤ 0.1°;

[0437] Dynamic Detection:

[0438] Vibration value at working speed ≤0.8mm / s;

[0439] Temperature rise ≤15℃;

[0440] Noise value ≤75dB.

[0441] The assembly environment requirements include:

[0442] Constant temperature workshop temperature 20±2℃;

[0443] Relative humidity is controlled at 45%-65%;

[0444] The illumination level shall not be less than 500 lux;

[0445] Working table flatness ≤ 0.05mm / m 2 ;

[0446] Regularly check the machine tool accuracy to ensure processing stability.

Claims

1. A method for restoring a circular broach handle after it is broken, characterized in that: The following steps are involved: Measure and determine the fracture position and size of the original rear handle, use a three-coordinate measuring machine or precision measuring tools to measure the outer diameter, roundness and coaxiality of the rear guide part, and establish the basic benchmark data; Carry out broaching back guide turning, including: Use carbide tools for the first rough turning, with feed rate f≤0.15mm / r, cutting depth ap≤1mm, cutting speed 80-100m / min, to remove the surface oxide layer; Use ceramic tools for the second finishing, with feed rate f≤0.08mm / r, cutting depth ap≤0.2mm, cutting speed 120-150m / min, to machine the step structure, leaving a finishing allowance of 0.02-0.05mm; Process annular grooves on the step structure, with a groove depth of 0.5-1mm, surface roughness Ra≤1.6μm, and cylindricality error controlled within 0.01mm; Design and process the first rear handle according to the step structure size, and arrange three through-threaded holes at intervals of 120° along the circumference of the circular broach rear guide portion, each threaded hole having a 90° or 120° countersunk hole structure; Put the first rear handle into a medium temperature tempering furnace and heat it to 350°C, keep it warm for 15-20 minutes, and control the temperature uniformity within the range of ±5°C. The first rear handle is a re-customized rear handle; A special centering fixture is used for heat-fit assembly. The leveling error of the fixture base is controlled within 0.02mm / 1000mm, and the centering accuracy is ≤0.01mm. After natural cooling, apply medium-strength thread locking agent on the threaded connection surface, screw the three screws through the threaded holes respectively, so that the ends of the screws extend into the annular groove for limit fixation, and tighten in steps with a torque wrench to control the screw tightening torque error within ±5%.

2. The method according to claim 1, characterized in that The method further comprises: The cooperation between the first rear handle and the step structure adopts the following parameters: diameter The following uses H7 / u6 fit, with interference 0.015-0.025mm; diameter Adopt H7 / u7 fit, interference 0.020-0.032mm; diameter The above adopts H7 / u8 fit, with interference 0.025-0.040mm; The mating surfaces are inspected with blue light, and the contact area ratio is ≥85%, with evenly distributed contact points.

3. The method according to claim 1, characterized in that The screw selection and installation includes: Use screws with strength grade 12.9; For diameter For screws, use a tightening torque of 25-30 N·m; For diameter For screws, use a tightening torque of 45-50 N·m; For diameter For screws, use a tightening torque of 70-80 N·m; The thread clearance is 6g / 6H.

4. A method for restoring a circular broach handle after it is broken, characterized in that: The following steps are involved: Measure and determine the fracture position and size of the original rear handle, use a three-coordinate measuring machine or precision measuring tools to measure the outer diameter, roundness and coaxiality of the rear guide part, and establish the basic benchmark data; Carry out broaching back guide turning, including: Use carbide tools for the first rough turning, with feed rate f≤0.15mm / r, cutting depth ap≤1mm, cutting speed 80-100m / min, to remove the surface oxide layer; Use ceramic tools for the second finishing, with feed rate f≤0.08mm / r, cutting depth ap≤0.2mm, cutting speed 120-150m / min, to machine the step structure, leaving a finishing allowance of 0.02-0.05mm; Using micron-level stereolithography technology, epoxy acrylate photosensitive resin material is used to print the transition connection layer on the fracture surface, wherein the laser power is controlled at 80-100mW and the scanning speed is 200-300mm / s; Among them, printing the transition connection layer on the fracture surface includes: printing a honeycomb basic grid with a unit size of 50-100 microns, and the structure density distribution is gradient, gradually decreasing from the inside to the outside; setting a micro-barb structure with a height of 15-25 microns; The 42CrMo alloy sheets are stacked layer by layer using the layered solid manufacturing technology, wherein the thickness of the alloy sheets starts from 0.1 mm and increases to 0.2 mm layer by layer; The interlayers are bonded with modified epoxy resin structural adhesive, with the amount of adhesive applied per layer being 0.15-0.20g / cm 2 ; The pressing pressure is 3-5MPa, and the pressing force increases by 10% layer by layer; The inter-layer alignment accuracy is ≤0.02mm, and the vacuum degree during stacking is ≤10Pa; Perform stress release heat treatment at 200-250°C for 2-3 hours and cool with the furnace; After cooling, three through threaded holes are arranged at intervals of 120° along the circumference, each threaded hole has a 90° or 120° countersunk hole structure, and three screws are screwed in through the threaded holes respectively.

5. The method according to claim 4, characterized in that The modified epoxy resin structural adhesive adopts a gradient formula: The bottom layer uses a high-toughness formula with a shear strength of ≥25MPa; The middle layer uses a standard formula with a temperature resistance of -40°C to 150°C; The surface layer uses a high-strength formula with a curing time of 120 minutes (120°C); The bonding strength shall not be less than 85% of the parent material strength.

6. The method according to claim 4, characterized in that The method further comprises: performing the following tests after forming: Ultrasonic flaw detection is carried out every 5 layers; After final molding, X-ray inspection is carried out to ensure that there are no internal defects; Test the surface hardness, which is required to reach more than 90% of the raw material; Perform dynamic balance test and the dynamic balance level reaches G2.

5.

7. A method for restoring a circular broach handle after it is broken, characterized in that: The following steps are involved: Measure and determine the fracture position and size of the original rear handle, use a three-coordinate measuring machine or precision measuring tools to measure the outer diameter, roundness and coaxiality of the rear guide part, and establish the basic benchmark data; Carry out broaching back guide turning, including: Use carbide tools for the first rough turning, with feed rate f≤0.15mm / r, cutting depth ap≤1mm, cutting speed 80-100m / min, to remove the surface oxide layer; Use ceramic tools for the second finishing, with feed rate f≤0.08mm / r, cutting depth ap≤0.2mm, cutting speed 120-150m / min, to machine the step structure, leaving a finishing allowance of 0.02-0.05mm; Put the first rear handle into a medium temperature tempering furnace and heat it to 350°C, keep it warm for 15-20 minutes, and control the temperature uniformity within the range of ±5°C. The first rear handle is a re-customized rear handle; Three through threaded holes are arranged at intervals of 120° along the circumference, each threaded hole has a 90° or 120° countersunk hole structure, and three screws are screwed in through the threaded holes for fixing; An elastic compensation structure is designed between the first rear handle and the original rear guide, including: It uses three elastic diaphragms evenly spaced at 120°, made of 42CrMo alloy steel with a hardness of HRC32-36; The thickness of the diaphragm is precisely controlled at 1.5-2mm, and the thickness ratio between the inner and outer ends is 1.2:1; The effective working length is 0.4-0.5 times the diameter of the rear handle; A bearing support system is provided, comprising: Use double-row angular contact ball bearings with P4 grade precision; The bearing preload is adjusted by precision nuts and controlled between 5% and 8% of the dynamic load. The bearing seat adopts 40Cr quenched and tempered steel integral design; The radial clearance is controlled at 0.01-0.015mm; Carry out assembly, including: Use a special positioning tool to install the elastic diaphragm, the position of the elastic diaphragm and the position of the threaded hole are arranged alternately; control the circumferential distribution error of the three diaphragms to be ≤0.5°; The verticality between the diaphragm and the connection surface is ≤0.02mm; The installation torque is controlled at 20-25N·m; Set up the bearing system, including: The bearing seat aperture accuracy requirement is H6; The interference of the outer ring of the bearing is 0.01-0.02mm; The verticality between the bearing end face and the seat is ≤0.005mm; The preload force is controlled by a special torque wrench.

8. The method according to claim 7, characterized in that The performance parameters of the elastic diaphragm include: Material elastic modulus: 210GPa; Yield strength: ≥835MPa; Fatigue strength: ≥400MPa; Elastic deformation: 0.2-0.3mm; Bearing preload: 2000-3000N.

9. The method according to claim 7, characterized in that: The restored inset handle meets the following criteria: Static detection: Radial runout ≤ 0.01mm; Axial runout ≤ 0.015mm; Coaxiality ≤ 0.02mm; Angle swing ≤ 0.1°; Dynamic Detection: Vibration value at working speed ≤0.8mm / s; Temperature rise ≤15℃; Noise value ≤75dB.

10. The method according to claim 7, characterized in that The assembly environment requirements include: Constant temperature workshop temperature 20±2℃; Relative humidity is controlled at 45%-65%; The illumination level shall not be less than 500 lux; Working table flatness ≤ 0.05mm / m 2 ; Regularly check the machine tool accuracy to ensure processing stability.

Images