Manufacturing and testing method for combined large-size and high-precision strip workpieces

Abstract

The present application relates to the technical field of mechanical processing technology. The present application discloses a method for manufacturing and testing a combined large-scale high-precision strip workpiece, which is characterized in that the workpiece is cut according to the size of each segment; each segment is manufactured by cutting; including rough machining, semi-finishing, and finishing processes; each process adopts layered cutting, the number of layers is an even number, and adjacent layers are cut in opposite directions; natural aging is performed after each process is completed, and after the last natural aging is completed, the segments are assembled and fixed into a workpiece; the workpiece is inspected as a whole. The technical solution of the present application effectively overcomes the various disadvantages of adopting the overall machining and then segmentation process. The technical solution of the present application greatly improves the effective utilization rate of the raw material plate material and reduces the input of raw material cost.

Description

Technical Field

[0001] The present application relates to the field of mechanical processing technology, and in particular to high-precision workpiece manufacturing and detection technology, and specifically to a method for manufacturing and detecting combined large-scale high-precision strip workpieces. Background Art

[0002] Strip workpieces usually refer to workpieces with a width-to-length ratio of ≤1 / 50 and / or a thickness-to-length ratio of ≤1 / 100, including straight workpieces and arc-shaped workpieces. For combined large-scale, high-precision strip workpieces, in order to ensure processing accuracy, it is generally required to adopt the manufacturing method of overall processing and overall testing. After the workpiece is processed, it is segmented to obtain individual components.

[0003] The main disadvantages of this traditional processing method are:

[0004] 1. The traditional process of processing the overall shape of the product and then segmenting it usually requires large-scale equipment such as large-scale gantry CNC machining centers to process large-sized workpieces, resulting in a serious waste of processing equipment resources; and the inherent larger equipment accuracy error of large-scale gantry CNC machining center equipment is difficult to overcome and avoid, and as the product specifications become larger, the cumulative accuracy error of the equipment will also be larger, which will ultimately make it difficult to guarantee product accuracy.

[0005] 2. If the arc-shaped bar workpiece is processed as a whole, its shape characteristics will result in a large amount of scraps in the raw material arrangement process even if comprehensive arrangement is adopted. The effective utilization rate of the raw material plate is very low, resulting in a huge waste of raw material resources.

[0006] 3. During the overall processing, the residual stress of machining has a great influence on the accuracy of the workpiece, causing the positions of the holes and grooves of the workpiece naturally placed after the processing to change significantly with the stress deformation of the product. The dimensional accuracy cannot be effectively guaranteed, and it is even difficult to meet the high-precision requirements of the design drawings for the positions of the holes and grooves.

[0007] 4. The process method of testing the workpiece as a whole before segmenting it will make it difficult to use a three-coordinate measuring machine to test the product's overall dimensions, the position dimensions of a large number of holes and slots, and the form and position tolerances of the segmented products. It is even more difficult to test the position accuracy of the adjacent parts of each segment. Moreover, it is difficult to determine the conformity of the product quality after the segmented parts are combined without effective testing. Summary of the invention

[0008] The main purpose of the present application is to provide a method for manufacturing and detecting a combined large-size high-precision strip workpiece, so as to solve the problems of machining accuracy and measurement accuracy of this type of combined large-size high-precision strip workpiece in the prior art.

[0009] In order to achieve the above-mentioned purpose, according to one aspect of the specific implementation method of the present application, a method for manufacturing and inspecting a combined large-size high-precision strip workpiece is provided, which is characterized in that the workpiece is cut according to the size of each segment; each segment is manufactured by cutting; including rough machining, semi-finishing, and finishing processes; layered cutting is adopted in each process, the number of layers is an even number, and adjacent layers are cut in opposite directions; natural aging is carried out after each process is completed, and after the last natural aging is completed, the segments are assembled and fixed into a workpiece; and the workpiece is inspected as a whole.

[0010] In some embodiments, the workpiece has holes and / or slots therein.

[0011] In some embodiments, the workpiece has a width-to-length ratio of ≤1 / 50 and / or a thickness-to-length ratio of ≤1 / 100.

[0012] In some embodiments, the workpiece is a curved workpiece.

[0013] In some embodiments, the arc-shaped workpiece is composed of two arcs.

[0014] In some embodiments, the precision level is increased according to the precision requirements of each segment for processing and manufacturing.

[0015] In some embodiments, the workpiece manufacturing process includes the following specific steps:

[0016] Cutting of each section; first natural aging; rough milling of the shape; second natural aging; semi-finishing milling of the shape and rough machining of holes / slots; third natural aging; finishing milling of the shape and finishing boring of holes / slots; final natural aging; assembly and fixation; overall inspection.

[0017] In certain embodiments, water cutting is used in each segment cutting step.

[0018] In some embodiments, all processing steps after cutting are performed using CNC equipment.

[0019] According to the technical solution of the present application and the further improved technical solution in certain exemplary embodiments thereof, the present application has the following beneficial effects:

[0020] The technical solution of the present application effectively overcomes the various drawbacks of the overall processing and then segmentation process. It avoids the waste of equipment resources that originally required the use of a large gantry machining center for production, and uses an ordinary vertical machining center to achieve effective processing and manufacturing of each segmented product. It also avoids the drawback of large cumulative errors in the overall processing of large equipment. It avoids the difficulty of overall inspection under natural placement conditions caused by the stress deformation of such slender parts in the original overall processing method.

[0021] The process method of segmented manufacturing and then combined testing in this application can effectively meet the needs of combined testing and acceptance of segmented products and product dimensional accuracy reproduction, and realize the detection of combined product external dimensions, hole system slot system position accuracy and processing accuracy.

[0022] The technical solution of the present application greatly improves the effective utilization rate of raw material plates and reduces the investment in raw material costs.

[0023] The present application is further described below in conjunction with the accompanying drawings and specific embodiments. Additional aspects and advantages of the present application will be partially given in the following description, partially become apparent from the following description, or be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The drawings constituting a part of this application are used to provide further understanding of this application. The specific implementation manner, illustrative embodiments and descriptions of this application are used to explain this application and do not constitute improper limitations on this application.

[0025] In the attached picture:

[0026] Figure 1 This is a schematic diagram of the structure of a combined large-size high-precision arc strip workpiece according to an exemplary embodiment of the present application;

[0027] Figure 2 for Figure 1 The enlarged schematic diagram of sections 12 and 13;

[0028] Figure 3 This is a schematic diagram of the combined test;

[0029] Figure 4 for Figure 3 Schematic diagram of the VV section.

[0030] in:

[0031] 01~13 are the numbers of the 13 segments respectively; 100 is the workpiece; 101 is the narrow groove; 102 is the installation positioning hole; 200 is the inspection tool plate; 120 is the pin; 121 is the threaded hole for pin removal; OP is the symmetry axis of the workpiece (the perpendicular bisector of the line segment O1O2); O1 is the center of the arc AP; O2 is the center of the arc BP; Y1Y2 are the segment positions of segments 12 and 13. DETAILED DESCRIPTION

[0032] It should be noted that, in the absence of conflict, the specific implementation modes, exemplary embodiments and features thereof in this application can be combined with each other. The present application will now be described in detail with reference to the accompanying drawings and in combination with the following content.

[0033] In order to enable those skilled in the art to better understand the scheme of the present application, the following will be combined with the drawings in the specific implementation methods and exemplary embodiments of the present application to clearly and completely describe the technical solutions in the specific implementation methods and exemplary embodiments of the present application. Obviously, the described exemplary embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the specific implementation methods and exemplary embodiments in the present application, all other implementation methods and embodiments obtained by ordinary technicians in this field without making creative work should fall within the scope of protection of this application.

[0034] As an exemplary embodiment of the present application, the technical solution of the present application is described below based on the manufacturing and inspection process of the hoop bar workpiece of the steam generator of the domestically produced third-generation nuclear power technology "Hualong One".

[0035] See also Figure 1 to Figure 4 The workpiece 100 is an alloy steel hoop bar for low-temperature containers, which is used to support and fix the J-shaped clips for the U-shaped heat exchange tubes of the evaporator of the pressurized water reactor of the "Hualong One" nuclear power plant. The eccentrically symmetrical semicircular arc bar has 158 Y-direction through narrow grooves 101 with a width of 3.11mm (0, +0.15) and a depth of 22.7mm distributed symmetrically along the X direction of the drawing. The distance tolerance between the center plane of all narrow grooves 101 and the left and right symmetrical center plane of the part is ±0.05mm. The whole hoop bar is divided into 13 left-right symmetrical sub-parts of different lengths according to design requirements, such as Figure 1 The segments numbered 01 to 13. The segmented positions also need to ensure the narrow groove width tolerance of 3.11mm (0, +0.15) and the distance tolerance between the narrow groove center plane and the symmetrical center plane after the segmented parts are assembled. At the same time, the position accuracy requirements of the 59 installation positioning holes 102 unevenly distributed on the entire product are extremely high (position accuracy: Φ0.1mm, distributed on the semicircular arc radius R1715mm; the workpiece arc length is about 4560mm, width 25mm, thickness 32mm). The compliance of the size and position tolerances of each hole and narrow groove on the hoop bar workpiece is an important guarantee for the successful assembly of the steam generator and its normal operation during its service life.

[0036] The material of the workpiece 100 is ASME grade alloy steel SA-516GR.70 for low-temperature containers (this material has the characteristics of low tensile strength (about 450-585MPA) and yield strength (≥230MPA)). The general method for processing such parts is usually to use a large gantry CNC machine tool for overall processing and inspection, and then split and process them into 13 sub-parts required by the design; however, if only a gantry CNC machine tool is used for conventional processing, although the dimensional accuracy and position accuracy of a single hole or slot in the hoop strip can be guaranteed during the fixed processing process. However, based on this narrow width, thin thickness and long arc hole and slot parts (the width-to-length ratio reaches about 1 / 180, and the thickness-to-length ratio reaches about 1 / 450 when the remaining thickness of the groove bottom is about 9mm), the processing stress and material internal stress generated during the machining process, and the slender workpiece is easy to bend and deform after the processing is completed, resulting in the position accuracy of the arc-arranged holes and the center surface of each narrow slot difficult to meet the design requirements.

[0037] In order to solve the problems of machining accuracy and measurement accuracy of this type of combined large-size high-precision bar workpieces, the workpiece manufacturing and testing methods in this example are as follows:

[0038] Firstly, according to the requirement of final inspection and acceptance of the products, each segmented product shall be inspected and accepted in the assembled state. Then, an inspection tooling plate for assembled installation and positioning of each segmented product is designed and manufactured. The position accuracy of the installation positioning holes of each segmented product from Φ0.1mm is tightened to Φ0.03mm, and the size tolerance of the through hole of Φ13.5 (0, +0.1) is tightened to Φ13.55±0.01, and the processing is carried out according to more stringent precision requirements.

[0039] In view of the determination of the above-mentioned final acceptance plan, and in order to avoid the processing deformation caused by cutting heat and the easily deformed structure of the workpiece during the overall mechanical processing of the hoop bar product, which leads to the problem that the outer dimensions, hole and groove positions of the hoop bar after processing of the workpiece cannot meet the design requirements, this exemplary embodiment manufactures the 13 segments that are combined into the whole hoop bar product in sections, and then uses the inspection tooling plate to position and combine them into an overall process plan for three-coordinate inspection of the whole product.

[0040] After many trials and processing, the following main processing procedures were gradually summarized in terms of machining process parameters, tool path methods, anti-deformation stress relief and testing:

[0041] ① Water cutting for cutting—② Natural aging for 24h—③ Rough milling of shape, holes and slots—④ Natural aging for 24h—⑤ Semi-finishing milling of shape and slots—⑥ Natural aging for 24h—⑦ Finishing milling of shape and slots and finishing boring—⑧ Natural aging for 8h—⑨ Assemble and fix each segment into a complete base and then use three-coordinate measuring machine for inspection.

[0042] The workpiece material in this example is SA-516GR.70 medium-low temperature container steel (which has alloy components such as carbon ≤0.24%, phosphorus ≤0.035, sulfur ≤0.01, silicon (0.13~0.45), and manganese (0.79~1.30)). This material has the characteristics of low strength and high plasticity.

[0043] The product is in the shape of an arc-shaped slender strip, such as the hoop strip with an outer specification of R1727.5×25×32, and has 59 unevenly distributed through holes (position accuracy Φ0.1mm) and 158 narrow grooves of 3.11mm wide × 22.7mm deep (position accuracy ±0.05mm) inside.

[0044] First, computer nesting is used according to the appearance of each segmented product in order to maximize the use of this type of nuclear-grade raw materials; at the same time, CNC water jet cutting is used to cut the plates used for the hoop bar workpiece, leaving a uniform processing allowance along the theoretical shape of the product; and conventional cutting processing using flame cutting or plasma cutting methods during the cutting process to avoid thermal deformation and thermal stress accumulation of the workpiece.

[0045] The workpieces after water jet cutting are laid flat for 24 hours for natural aging treatment to fully release the processing stress generated during water jet cutting.

[0046] The workpieces that have been processed in the previous stage are processed in layers using a CNC milling machine.

[0047] First, leave a margin on both sides of the CNC rough machining segmented products as a clamping reference, and at the same time, rough machining the installation positioning holes 102 of the segmented products (usually there are 2 to 5 installation positioning holes 102 on each segmented product);

[0048] Then CNC rough-processes the product shape in layers, and the cutting parameters are as follows: linear speed: 100m / minute; cutting depth of each layer: 0.5mm / layer; cutting amount: 1000mm / minute; and the total number of CNC layered processing is planned as an even-numbered layer, and the odd-numbered layers are processed by reverse milling and the even-numbered layers are processed by forward milling. This method can eliminate some processing stress in time during the processing process.

[0049] Finally, a Φ2.7mm diameter straight shank end mill was used to machine a narrow groove 101 with a width of 3.11mm and a depth of 22.7mm in layers. The cutting parameters were linear speed: 60m / min, depth of each layer: 0.2mm / layer; feed speed: 600mm / min. In view of the narrow width and deep depth of the groove, when the Φ2.7mm diameter tool was used for machining, the diameter-to-depth ratio would reach about 1:8, so it was necessary to ensure that the cutting allowance on both sides of the cutting direction was as uniform as possible to avoid deflection or damage caused by unilateral cutting of the tool.

[0050] At the same time, during the cutting process, pay attention to maintaining the sharpness of the tool and timely and sufficient cooling to reduce the generation of cutting heat. Evenly leave allowances for the parts that need to be processed later, and perform rough processing on the through holes to remove most of the processing allowances before semi-finishing and fully release the processing stress.

[0051] After the CNC rough milling process is completed, it will be laid flat for natural aging treatment for 24 hours to fully release the processing stress generated during the rough milling process.

[0052] After the previous process is completed, the product shape is processed by CNC semi-finishing milling with reserved layers.

[0053] First, two planes of the thickness of the CNC semi-finished segmented product are reserved as the clamping reference to eliminate the influence of the plastic deformation of the previous process on the processing accuracy of the subsequent process, and at the same time, the installation positioning hole 102 of the semi-finished segmented product is semi-finished;

[0054] Then, the installation positioning holes of each segmented product are used as the positioning and locking reference, and the CNC layered semi-finishing of the product shape is performed. The cutting parameters are: linear speed: 100m / min; cutting depth per layer: 0.5mm / layer; cutting amount: 1000mm / min. The total number of CNC layered processing is planned to be an even number of layers. At the same time, the odd number layers are processed by reverse milling, and the even number layers are processed by down milling. Part of the processing stress is eliminated in time during the processing process.

[0055] Finally, a Φ3.0mm diameter straight shank end mill was used to machine a narrow groove with a width of 3.11mm and a depth of 22.7mm in layers with reciprocating allowances; the cutting parameters were linear speed: 60m / min, depth of cut per layer: 0.2mm / layer; feed speed: 600mm / min. The ratio of tool diameter to cutting depth in this process reached about 1:8, so it was necessary to ensure that the cutting allowances on both sides of the cutting direction were as uniform as possible and contacted the machining allowances on both sides of the wall at the same time to avoid position deviation or damage caused by single-sided cutting of the tool.

[0056] At the same time, during the cutting process, attention should be paid to maintaining the sharpness of the tool and timely and sufficient cooling to reduce the generation of cutting heat. Evenly leave allowances for the parts that need to be processed later, and perform semi-finishing of the through holes to remove most of the machining allowances before finishing to fully release the machining stress.

[0057] After the CNC semi-finishing milling process is completed, it will be laid flat for natural aging treatment for 24 hours in time to fully release the processing stress generated during the semi-finishing milling process.

[0058] After the previous process is completed, the product shape is processed by layered CNC precision milling and low-stress boring is used for the installation positioning holes of the segmented products.

[0059] First, CNC finish-machines the two major planes of the segmented product thickness as the clamping reference to eliminate the influence of the plane plastic deformation after the previous process on the processing accuracy of the subsequent process. At the same time, the size of each installation positioning hole of the segmented product is Φ13.5±0.01 by boring.

[0060] Then, the positioning holes of each segmented product are used as the positioning and locking reference, and the CNC layered finishing of the product shape is performed. The cutting parameters are: linear speed: 150m / min; cutting depth per layer: about 0.3mm / layer; cutting amount: 2000mm / min. The total number of CNC layered processing is planned to be an even number of layers. At the same time, the odd number layers are processed by reverse milling, and the even number layers are processed by down milling. Part of the processing stress is eliminated in time during the processing process.

[0061] Finally, a custom straight shank end mill with a diameter of Φ3.18mm was used to reciprocate in layers to process a narrow groove with a width of 3.11(0, +0.15)mm and a depth of 22.7mm; the cutting parameters were linear speed: 60m / min, cutting depth per layer: 0.1mm / layer; feed speed: 600mm / min. The ratio of tool diameter to cutting depth in this process reached about 1:7, so it was necessary to ensure that the cutting allowances on both sides of the cutting direction were as uniform as possible and contacted the machining allowances on both sides of the wall at the same time to avoid position deviation or damage caused by single-sided cutting of the tool.

[0062] At the same time, during the cutting process, pay attention to maintaining the sharpness of the tool and timely and sufficient cooling to reduce the generation of cutting heat.

[0063] After the CNC milling process is completed, the complete set of segmented products are placed on the inspection tooling plate 200, and the positioning holes at both ends of each segmented product (each segment has 2 to 5 positioning holes) are aligned with the qualified combined inspection installation positioning holes on the inspection tooling plate. At the same time, the pin 120 is used for positioning and fixing (the matching size tolerance of the pin 120 is Φ13.54 (0, -0.005) mm). Figure 4 shown.

[0064] After the natural aging, the whole product is tested by three-coordinate measurement in the state of segmented pin fixation. The whole assembly product can be tested at the same testing position, including the detection of the overall dimensions, hole / slot dimensions, the detection of the position accuracy of Φ0.1mm of 59 installation positioning holes 102, and the detection of the size of ±0.05mm from the center plane of 158 3.11mm narrow slots 101 to the symmetrical center plane of the whole assembly product.

[0065] The segmented manufacturing process method of this embodiment effectively overcomes the various drawbacks of adopting the overall processing and then segmented process. It avoids the waste of equipment resources that originally required the use of a gantry processing center of more than 4 meters to produce, and adopts the commonly used 850 vertical processing center to realize the effective processing and manufacturing of each segmented product. At the same time, it also avoids the drawback of large cumulative errors in the overall processing of large equipment.

[0066] The segmented processing and manufacturing process of this embodiment increases the effective utilization rate of nuclear-grade raw material plates from about 10% to about 90%, greatly reducing the input of raw material costs.

[0067] The segmented processing and manufacturing process method of this embodiment avoids the difficulty in the original overall processing method that such slender arc-shaped parts are difficult to detect as qualified under natural placement conditions due to processing stress deformation.

[0068] The process method of segmented manufacturing and then combined testing in this embodiment can effectively meet the needs of combined testing and acceptance of each segmented product and the reproduction of product dimensional accuracy. It can realize the detection of the outer dimensions of the combined product, the detection of the position accuracy of Φ0.1mm of 59 installation positioning holes, the detection of the position dimension of ±0.05mm from the center plane of 158 3.11mm grooves to the symmetric center plane of the whole combined product, and the detection of the 3.11mm groove width dimension formed by the combination of each segmented product.

[0069] The technical solution of the present invention can greatly improve the overall work efficiency of such arc-shaped strip workpieces, save processing costs and raw material costs, and obtain accurate three-coordinate measurement and detection data, while effectively ensuring product quality. The technical solution of the present invention has been successfully applied to the batch manufacturing of such thin and long combined large-size high-precision hoop strip products. The evaporators for the "Hualong One" nuclear reactors "Fangchenggang 4# Pile" and "Fangchenggang 3# Pile" with independent intellectual property rights produced by this method have achieved grid-connected power generation and safe operation of nuclear reactors.

Claims

1. A method for manufacturing and testing a combined large-scale high-precision strip workpiece, characterized in that: The workpiece has a positioning hole and a narrow groove; the manufacturing and testing method comprises the steps of: Cut the workpieces according to their segment sizes, and carry out natural aging treatment after cutting. Each segment is manufactured by cutting, and the cutting process includes rough milling, second natural aging, semi-finishing milling and rough hole / slot machining, third natural aging, finishing milling and finishing boring holes / slots, and the last natural aging. Each process adopts layered cutting, the number of layers is an even number, and adjacent layers are cut in opposite directions. The precision level is improved according to the precision requirements of each segment for processing and manufacturing. After the last natural aging treatment is completed, each segment is fixed on the inspection tooling plate through the cooperation of the latch and the positioning hole, so as to be assembled and fixed into a workpiece; Conduct overall inspection on the workpiece; The rough milling process specifically includes: firstly, leaving allowance for CNC rough machining of the two sides of the segment thickness as a clamping reference, and rough machining of the segment installation positioning hole (102); then, CNC rough machining of the segment shape in layers; and finally, using a straight shank end mill with a diameter of 2.7 mm to reciprocate in layers to machine the narrow groove (101); The semi-finishing milling and roughing of holes / grooves are specifically as follows: first, two planes of the segment thickness are semi-finished by CNC with allowance as the clamping reference, and the segment installation positioning holes (102) are semi-finished at the same time; then, the segment installation positioning holes (102) are used as the positioning and locking reference, and the segment shape is semi-finished by CNC in layers; finally, a straight shank end mill with a diameter of 3 mm is used to reciprocate in layers to allowance for the narrow groove (101); The precision milling of the outer shape and precision boring of the holes / grooves are specifically as follows: first, two planes of the segment thickness are precision machined by CNC as the clamping reference, and at the same time, each installation positioning hole (102) of the segment is precision machined by boring; then, the segment installation positioning hole (102) is used as the positioning and locking reference, and the segment outer shape is precision machined by CNC in layers; finally, a straight shank end mill with a diameter of 3.18 mm is used to reciprocate in layers to machine the narrow groove (101); The workpiece has a width-to-length ratio of ≤1 / 50 and a thickness-to-length ratio of ≤1 / 100, and is made of ASME grade alloy steel for low-temperature containers. The narrow grooves (101) are symmetrically distributed along the X direction on the eccentrically symmetrical semicircular arc strip of the workpiece and are through-connected in the Y direction. The distance tolerance between the center plane of all the narrow grooves (101) and the left-right symmetrical center plane of the workpiece is ±0.05 mm.

2. The manufacturing and testing method of combined large-scale high-precision strip workpiece according to claim 1 is characterized in that: The workpiece is an arc-shaped workpiece.

3. The manufacturing and testing method of combined large-scale high-precision strip workpiece according to claim 2 is characterized in that: The arc-shaped workpiece is composed of two circular arcs.

4. The manufacturing and testing method of combined large-scale high-precision strip workpiece according to claim 1 is characterized in that: After cutting, all processing steps are carried out using CNC equipment.

5. The manufacturing and testing method of combined large-scale high-precision strip workpiece according to claim 1 is characterized in that: Water cutting is used in each segment cutting step.

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