A precise pouring and forming method for fabricated prefabricated components

Abstract

The application discloses a kind of precision pouring and forming method of fabricated precast component, comprising the following steps S1 precast preparation: according to the design drawing of fabricated precast component, complete component deepening design, clear component size, reinforcement arrangement, embedded part position and pouring parameter, prepare mould, reinforcement, concrete raw material, vibrating equipment, curing equipment and detection equipment, and all equipment is debugged calibration, raw material is detected on approach;S2 mould precision positioning: using modular steel mould, mould is decomposed into bottom mould, side mould, end mould and positioning assembly, and the precise butt joint of each component of mould is realized by double-stage positioning pin+wedge locking mechanism.The application is suitable for industrialized batch production of various types of fabricated concrete precast component, especially suitable for high-rise fabricated building, public building and other projects with high requirements for component precision and forming quality.

Description

Technical Field

[0001] This invention relates to the field of prefabricated component technology, and in particular to a method for precise casting and molding of prefabricated components. Background Technology

[0002] With the rapid modernization of my country's construction industry, prefabricated buildings, due to their outstanding advantages such as high industrialization level, less wet work on construction sites, significant energy-saving and emission-reduction effects, high construction efficiency, and strong quality control, have become an important direction for the transformation and upgrading of the construction industry. They are widely used in various projects such as civil buildings and public buildings, expanding from traditional multi-story residential buildings to high-rise residential buildings, public buildings, and other building types, and related technologies are constantly innovating and breaking through. The core of prefabricated buildings is precast components. The casting and forming quality of precast components directly determines the structural safety, assembly efficiency, and performance of prefabricated buildings. Therefore, improving the precision of casting and forming of precast components is the key to promoting the high-quality development of prefabricated buildings.

[0003] Currently, existing methods for casting and molding prefabricated components still face numerous technical bottlenecks, making it difficult to meet the high precision and quality requirements of modern prefabricated buildings. The main problems are as follows: First, the positioning accuracy of the molds is insufficient. Traditional precast component molds mostly adopt a single welded structure, relying on manual on-site adjustment. The flatness, perpendicularity, and dimensional accuracy of the molds are difficult to guarantee. After repeated use, problems such as weld cracking and datum plane misalignment are prone to occur, resulting in large mold positioning errors. This leads to excessive dimensional deviations in precast components, affecting the assembly compatibility of the components. At the same time, the molds are cumbersome to assemble and disassemble, have poor versatility, and the same set of molds cannot adapt to the production needs of different specifications of components. Frequent mold changes result in low production efficiency and low equipment utilization.

[0004] Second, the accuracy of the reinforcement and embedded parts layout is low. During the reinforcement binding process, there is a lack of effective positioning and fixing measures, and the reinforcement cage is prone to deformation and displacement, resulting in excessive deviations in reinforcement spacing and protective layer thickness. When installing embedded parts, manual positioning is often used, which has poor positioning accuracy and large deviations in the center of the embedded parts. This can easily lead to problems such as embedded parts shifting or tilting, affecting the reliability of subsequent component connections and even requiring later repairs, thus increasing production costs.

[0005] Third, the concrete pouring and vibration processes are unreasonable. Concrete mix proportions rely heavily on manual experience, resulting in insufficient measurement accuracy and unstable workability and strength properties. Traditional pouring methods are used, leading to uneven pouring speeds and issues such as concrete accumulation and segregation. This is especially problematic during layered pouring, where weak interlayer bonding creates gaps. Improper control of vibration frequency and time during vibration results in either over-vibration causing aggregate settling and surface sanding, or under-vibration leading to defects such as honeycomb and voids within the concrete, severely impacting the structural strength and durability of the components.

[0006] Fourth, the curing process is crude and inefficient. Current curing methods mostly employ traditional steam curing or natural curing. During steam curing, temperature and humidity control are imprecise, and the rapid heating and cooling rates can easily lead to cracks on the component surface. Natural curing has a long cycle, is greatly affected by environmental factors, and results in unstable curing quality. This not only prolongs the production cycle but also affects the strength development and molding quality of the components. Furthermore, traditional curing methods are energy-intensive, which is inconsistent with the development concept of green building.

[0007] Fifth, the overall quality control is inadequate. The existing production process lacks a systematic traceability mechanism for raw material testing, production process parameter recording, and finished product testing. Once a component quality problem occurs, it is difficult to trace the root cause, hindering the optimization of production processes and quality improvement. Furthermore, during finished product handling and stacking, surface damage and deformation under pressure can easily occur, affecting the final quality of the components.

[0008] Therefore, it is necessary to design a method for precise casting and molding of prefabricated components to solve the above problems. Summary of the Invention

[0009] The purpose of this invention is to address the shortcomings of existing technologies by proposing a method for precise casting and molding of prefabricated components. This invention is applicable to the industrial mass production of various types of prefabricated concrete components, and is particularly suitable for high-rise prefabricated buildings, public buildings, and other projects with high requirements for component precision and molding quality.

[0010] To achieve the above objectives, the present invention adopts the following technical solution: A method for precise casting and molding of prefabricated components includes the following steps: S1 Prefabrication Preparation: Based on the design drawings of prefabricated components, complete the detailed design of the components, clarify the component dimensions, reinforcement layout, embedded part positions and pouring parameters, prepare molds, reinforcement, concrete raw materials, vibration equipment, curing equipment and testing equipment, and debug and calibrate all equipment, and conduct incoming inspection of raw materials. S2 Mold Precision Positioning: Modular steel molds are used, which are decomposed into bottom molds, side molds, end molds and positioning components. The precise docking of each part of the mold is achieved through double-stage positioning pins and wedge locking mechanism. The flatness, perpendicularity and dimensional accuracy of the mold are tested and calibrated using a three-coordinate measuring machine platform to ensure that the mold positioning error is ≤0.3mm. After calibration, the mold is fixed and a special release agent is applied. S3 Reinforcing Steel and Embedded Parts Precise Layout: According to the detailed design drawings, the processed and qualified reinforcing steel is tied into shape, and the reinforcing steel skeleton is fixed with positioning clamps to ensure that the spacing deviation of the reinforcing steel is ≤±2mm and the thickness deviation of the protective layer is ≤±1mm; the embedded parts are fixed in the mold with positioning seats, the position of the embedded parts is adjusted to ensure that the center deviation of the embedded parts is ≤0.5mm, and a second inspection is carried out after fixing. S4 concrete precision preparation and pouring: According to the strength grade requirements of the components, the concrete raw materials are precisely proportioned, with the measurement error of cement, sand, gravel, water and admixtures ≤±1%. The mixing time is controlled at 90-120s to ensure that the workability of the concrete meets the standards (slump 120±20mm, spread ≥500mm). A quantitative concrete placing machine is used for layered pouring, with the pouring speed controlled at 0.5-0.8m³ / h, and the thickness of each layer controlled at 200-300mm. The pouring volume and pouring speed are monitored in real time during the pouring process. S5 Layered Vibration: An immersion vibrator and an attached vibrating table are used for combined vibration. The immersion vibrator is operated at a frequency of 50-60Hz, with an amplitude of 0.5-1mm and an insertion depth of 50-100mm below the surface of the lower concrete layer. The vibration time is 20-30s per layer until the concrete surface is free of air bubbles and smooth with a layer of cement paste, avoiding over-vibration or under-vibration. The attached vibrating table operates synchronously at a frequency of 40-50Hz to help eliminate voids within the concrete. S6 Precision Curing: After pouring, first perform 2-4 hours of static curing at room temperature, then enter the steam curing stage. The heating rate is controlled at ≤15℃ / h, the constant temperature stage temperature is controlled at 50-60℃, the constant temperature time is 12-20 hours, the cooling rate is controlled at ≤10℃ / h, and after cooling to room temperature, perform natural curing for ≥7 days. During the curing period, monitor the ambient temperature and humidity in real time to ensure the stability of curing parameters. S7 Demolding Inspection: When the concrete strength reaches more than 70% of the design strength, demolding is carried out. Demolding is done slowly using special tools to avoid damaging the components by prying. After demolding, the dimensions, surface flatness, appearance quality and the position of embedded parts of the components are fully inspected. Unqualified components are reworked, and qualified components proceed to the next process. S8 Finished Product Processing: Clean the surface of qualified precast components, repair defects, mark the component number, production date and strength grade on the surface of the components, use special packaging for protection, stack them in categories, and do a good job of finished product identification and traceability management.

[0011] Preferably, in S1, the detailed design of the component is carried out based on the BIM model, integrating the data of the entire process of component design, production and installation, completing collision detection in advance, optimizing the layout of steel bars and embedded parts, and issuing detailed component processing drawings and production operation instructions; the raw material inspection upon arrival includes cement strength, mud content of sand and gravel, mechanical properties of steel bars and compatibility of admixtures, and can only be put into use after passing the inspection.

[0012] Preferably, in S2, the modular steel mold is made of Q345B steel, the surface is nitrided, the mold thickness is ≥6mm, and the rigidity meets the requirements of not deforming or leaking grout under the vibration condition of C50 and above high-strength concrete; the special release agent is a water-based release agent, and the coating thickness is controlled at 0.1-0.2mm, thin and uniform, without missed coating or accumulation.

[0013] Preferably, in S3, the processing accuracy requirements for the reinforcing bars are: the cutting length deviation of the reinforcing bars ≤ ±5mm, the bending angle deviation ≤ ±2°, and the inner diameter of the bend meets the specifications; the positioning clamp adopts an adjustable stainless steel clamp with a clamp spacing ≤ 200mm to ensure that there is no deformation or displacement after the reinforcing bar skeleton is formed; the embedded parts are made of Q235B material, with a galvanized surface treatment and a galvanized layer thickness ≥ 80μm.

[0014] Preferably, in S4, the concrete raw materials include ordinary Portland cement, medium sand, 5-25mm continuously graded crushed stone, high-efficiency water-reducing agent, and drinking water; the quantitative concrete placing machine is equipped with a flow sensor to provide real-time feedback on the pouring flow rate, and to prevent the concrete from directly impacting the reinforcing steel frame and embedded parts during the pouring process.

[0015] Preferably, in S5, the immersion vibrator is a variable frequency vibrator, which can adjust the vibration frequency in real time according to the thickness of the concrete pouring; during vibration, the vibrator adopts the "fast insertion and slow withdrawal" method, the insertion points are arranged in a quincunx pattern, the spacing is controlled at 3-4 times the diameter of the vibrator, and the adjacent insertion points overlap by 100-150mm; after vibration, the residual concrete on the surface of the vibrator is cleaned in time.

[0016] Preferably, in S6, the steam curing adopts a closed-loop steam curing kiln equipped with a waste heat recovery device, and the waste heat utilization rate is ≥40%; during the curing period, temperature and humidity data are recorded every 2 hours to form a curing record table; during the natural curing stage, geotextile or plastic film is used to cover the surface of the component to keep the surface moist, water is sprayed every 2 hours in hot weather, and heat preservation measures are taken in cold weather.

[0017] Preferably, in S7, the inspection adopts a combination of laser scanner and manual inspection. The size inspection includes the length, width, height and diagonal length of the component, with the length deviation ≤ ±5mm and the width / height deviation ≤ ±3mm. The surface flatness is inspected with a 2m straightedge, with an error ≤ 2mm / m. The appearance quality requirements are no exposed reinforcement, honeycomb, pitting and cracks.

[0018] Preferably, in S8, the surface cleaning is carried out by high-pressure airflow to remove floating dust and residual release agent from the surface of the component; the defect repair is carried out by repair mortar with the same strength grade as the component, and the surface flatness after repair is consistent with the surrounding area; the packaging is wrapped with pearl cotton and waterproof cloth, and the stacking is supported by wooden blocks with a spacing of ≤1.5m to avoid deformation of the component under pressure.

[0019] Preferably, it also includes a full-process quality traceability system, in which an RFID chip is embedded in each component to record raw material testing data, production parameters, maintenance records and test results, so as to achieve full life-cycle traceability of the component; the method is applicable to the production of various prefabricated components of assembled monolithic frame structures and assembled monolithic shear wall structures.

[0020] The present invention has the following beneficial effects: 1. High positioning accuracy and good component adaptability. This invention adopts a modular steel mold combined with a double-stage positioning pin and wedge locking mechanism, and uses a three-coordinate measuring platform for precise calibration. The mold positioning error is ≤0.3mm. The reinforcing bars and embedded parts are fixed by positioning clamps and positioning seats. The spacing deviation of the reinforcing bars is ≤±2mm, and the center deviation of the embedded parts is ≤0.5mm. This effectively solves the problem of large positioning deviation in the prior art, ensures the accurate size of the prefabricated components, and the surface flatness error is ≤2mm / m. This improves the assembly adaptability of the components, reduces the amount of on-site assembly adjustment work, and improves assembly efficiency.

[0021] 2. Excellent molding quality and high structural strength. This invention ensures stable workability and strength of concrete by precisely controlling the concrete mix proportion with a measurement error of ≤±1%. The use of layered pouring and coordinated vibration processes avoids problems such as concrete segregation, under-vibration, and over-vibration, ensuring high concrete density and eliminating defects such as honeycomb and voids. Precise curing processes effectively control the strength development of the concrete, preventing surface cracks and improving the structural strength and durability of the components. The component qualification rate is ≥99%, and the strength compliance rate is 100%.

[0022] 3. High production efficiency and low energy consumption. This invention adopts modular molds, which can be quickly assembled and disassembled to adapt to the production needs of different specifications of components. A single set of molds can cover more than 80,000 square meters of prefabricated building area within its life cycle, and the mold reuse rate is high. The processes of pouring, vibration and curing are optimized, shortening the production cycle by 15%-20%. The production cycle of conventional components can be controlled within 7-10 days per batch. The steam curing kiln is equipped with a waste heat recovery device, with a waste heat utilization rate of ≥40%, reducing energy consumption by 10%-15%, which is in line with the development concept of green building.

[0023] 4. Robust quality control and strong traceability. This invention establishes a full-process quality traceability system, recording component lifecycle data through RFID chips. This enables full traceability of raw material testing, production processes, maintenance records, and finished product testing. In the event of a quality problem, the root cause can be quickly traced, facilitating production process optimization and quality improvement. Simultaneously, each process includes testing steps to ensure component quality meets requirements.

[0024] 5. High versatility and wide applicability. This invention is applicable to the industrial mass production of various precast concrete components (precast beams, precast columns, precast wall panels, precast floor slabs, precast stairs, etc.) such as precast monolithic frame structures and precast monolithic shear wall structures. The process parameters can be flexibly adjusted according to the design requirements of different components to meet the needs of different projects, and it has broad engineering application prospects. Attached Figure Description

[0025] Figure 1 This is a flowchart of the overall process flow of a method for precise casting and molding of prefabricated components proposed in this invention. Figure 2 Flowchart for prefabrication preparation and precise mold positioning; Figure 3 A flowchart of the process for laying out pre-embedded steel bars and vibrating concrete during pouring. Figure 4 A flowchart for precise maintenance process; Figure 5 This is a flowchart of the demolding inspection, finished product processing and traceability process. Detailed Implementation

[0026] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0027] Reference Figures 1-5 A method for precise casting and molding of prefabricated components includes the following steps: S1. Prefabrication preparation Based on the design drawings of prefabricated components, we carry out detailed design of components based on BIM model, integrate data from the entire process of component design, production and installation, complete collision detection in advance, optimize the layout of steel bars and embedded parts, and issue detailed component processing drawings and production operation instructions, clarifying component dimensions, steel bar layout, embedded part positions and various process parameters such as pouring, vibration and curing.

[0028] Prepare all kinds of equipment and raw materials required for production. The equipment includes modular steel molds, steel bar processing equipment, concrete mixing equipment, quantitative placing machine, immersion vibrator, attached vibrating table, steam curing kiln, laser scanner, three-coordinate measuring machine platform, RFID chip reading and writing equipment, etc. The raw materials include cement, sand, gravel, water, admixtures, steel bars, embedded parts, release agent, repair mortar, etc.

[0029] All equipment underwent comprehensive commissioning and calibration: the batching scale of the concrete mixing equipment was calibrated with an error of ≤±1% to ensure accurate measurement of raw materials; the vibration equipment was commissioned to the preset frequency and amplitude to ensure stable vibration effect; the testing equipment (laser scanner, coordinate measuring machine platform) was calibrated to the required accuracy to ensure accurate test data; and the curing equipment was commissioned to the preset temperature and humidity parameters to ensure a stable curing environment.

[0030] Incoming raw materials are inspected as follows: Cement is PO 42.5 grade ordinary Portland cement, with its 3-day and 28-day strength and stability tested to ensure compliance with the requirements of the "Code for Acceptance of Construction Quality of Concrete Structures" (GB 50204); Sand is medium sand with a fineness modulus controlled between 2.3 and 3.0 and a mud content ≤3%; Aggregate is 5-25mm continuously graded crushed stone with a mud content ≤1%, and the particle size distribution meets the design requirements; Reinforcing steel is HRB400E threaded steel and HPB300 plain round steel, with its tensile strength, yield strength, and surface quality tested to ensure no rust or cracks; Admixtures are high-efficiency water-reducing agents with a water reduction rate ≥20%, and compatibility tests with cement are conducted to ensure no stratification or sedimentation; Embedded parts are made of Q235B material, with dimensional deviations ≤1mm and a zinc coating thickness ≥80μm; Release agents are water-based, ensuring no irritating odor and good release effect. Only after all raw materials have passed inspection and been recorded in the raw material arrival and acceptance log can they be put into use. Unqualified raw materials must be removed from the site immediately and are strictly prohibited from being used in production.

[0031] S2, Precise mold positioning Modular steel molds are adopted, dividing the mold into five functional units: bottom mold, side mold, end mold, and positioning components. The molds are made of Q345B steel with nitriding treatment. The mold thickness is ≥6mm, and the rigidity meets the requirements of not deforming, leaking grout, or shifting under vibration conditions for high-strength concrete of C50 and above. Each mold undergoes three rounds of simulated pouring pressure tests (maximum load up to 18MPa) before leaving the factory to ensure stable mold performance.

[0032] Install the bottom mold on a special base and adjust its level. Use a level to check that the levelness error is ≤0.2mm / m. Then, use a double-stage positioning pin and a wedge locking mechanism to precisely align the side mold, end mold and bottom mold. The positioning pin is made of high-strength alloy material with a positioning accuracy of ≤0.1mm. The wedge locking mechanism ensures that all parts of the mold are tightly connected without looseness or gaps.

[0033] A coordinate measuring machine (CMM) platform was used to comprehensively inspect and calibrate the flatness, perpendicularity, and dimensional accuracy of the mold. The spacing between inspection points was ≤500mm to ensure that the mold positioning error was ≤0.3mm, and that the deviation between the component design dimensions and the actual mold dimensions was controlled within the allowable range. After calibration, the mold was fixed to the base with bolts to prevent displacement during the casting process.

[0034] Apply a dedicated water-based release agent evenly to the inner surface of the mold, controlling the coating thickness to 0.1-0.2mm. Use a brush or sprayer to ensure a thin and even application, without any missed spots or accumulation. After application, allow it to stand for 10-15 minutes to allow the release agent to dry before proceeding to the next step. Applying the release agent effectively prevents concrete from sticking to the mold, ensuring a smooth and flat surface for the component and reducing damage during demolding.

[0035] S3. Precise placement of reinforcing bars and embedded parts According to the detailed design drawings and production operation instructions of the components, the steel bars are processed: steel bar cutting machines and steel bar bending machines are used to cut and bend the steel bars. The cutting length deviation is ≤ ±5mm, the bending angle deviation is ≤ ±2°, and the inner diameter of the bend meets the specifications. The processed steel bars are stacked according to specifications and models, and labeled with the component number, steel bar specifications, and quantity to avoid mixing.

[0036] The processed steel bars are transported to the mold and bound into shape within the mold. Adjustable stainless steel positioning clamps are used to fix the steel bar skeleton, with a clamp spacing of ≤200mm and arranged in a quincunx pattern to ensure that the steel bar skeleton does not deform or shift after forming. During the binding process, the spacing of the steel bars is strictly controlled, with a deviation of ≤±2mm, and is monitored in real time using a steel bar spacing ruler. The thickness of the protective layer of the steel bars is controlled using high-strength spacers, with the spacer strength ≥ the strength grade of the concrete of the component, and the spacer spacing ≤500mm, ensuring that the deviation of the protective layer thickness is ≤±1mm.

[0037] According to design requirements, embedded parts (such as connecting sleeves, reserved bolts, lifting rings, etc.) are fixed in the mold using positioning seats. The positioning seats have an adjustable structure, which can accurately adjust the position and elevation of the embedded parts. After adjustment, the positioning seats are fixed to the mold with bolts to ensure that the embedded parts are not loose or displaced. Then, a laser scanner is used to detect the center position of the embedded parts, ensuring that the center deviation of the embedded parts is ≤0.5mm. When connecting the embedded parts to the reinforcing steel cage, welding is used, with a weld length ≥10d (d is the diameter of the reinforcing steel). The weld quality meets the specifications, avoiding incomplete welds and missed welds.

[0038] After the reinforcement bars and embedded parts are laid out, the quality inspectors will conduct a second inspection. The inspection includes the specifications of the reinforcement bars, spacing, thickness of the protective layer, position, elevation and fixing of the embedded parts. If the inspection is qualified, the inspection record of the concealed works of the reinforcement bars will be filled out before proceeding to the next process. If the inspection is unqualified, adjustments and repairs will be made in a timely manner until it is qualified.

[0039] S4. Precision preparation and pouring of concrete Based on the strength grade requirements of precast components, concrete raw materials are precisely proportioned. The concrete mix design follows the "Specification for Concrete Mix Proportion Design" (JGJ 55). For example, the mix proportion (by mass) for C30 concrete is: cement:sand:aggregate:water:admixture = 320:650:1200:180:8. The specific mix proportion may be adjusted based on the performance of raw materials and the strength requirements of the components. The measurement error of cement, sand, aggregate, water, and admixtures is ≤±1%, and electronic metering equipment is used to ensure accurate proportioning.

[0040] The measured raw materials are added to the concrete mixing equipment in the following order: first, sand, gravel, and cement are added and mixed for 30 seconds to ensure uniform mixing; then water and admixtures are added and mixing continues for 90-120 seconds to ensure uniform mixing and that the workability meets the standards. Concrete workability is tested using slump and spread tests. The slump is controlled at 120±20mm, and the spread is ≥500mm. If the workability does not meet the standards, the admixture dosage can be adjusted appropriately until the requirements are met. After each batch of mixing is completed, three sets of concrete test blocks (150mm×150mm×150mm) are prepared. One set is used for 7-day strength testing, and two sets are used for 28-day strength evaluation. The test blocks are prepared according to specifications and cured under the same conditions as the structural components.

[0041] After the concrete is prepared, a quantitative placing boom is used for layered pouring. The placing boom is equipped with a flow sensor to provide real-time feedback on the pouring flow rate, facilitating control of the pouring speed. The pouring speed is controlled at 0.5-0.8 m³ / h to avoid excessively fast pouring, which could lead to concrete segregation and accumulation, or excessively slow pouring, which could result in poor interlayer bonding. Each layer of concrete is poured to a thickness of 200-300 mm. During pouring, the distance between the placing boom's outlet and the mold surface is controlled at 300-500 mm to prevent direct impact of concrete on the reinforcing steel frame and embedded parts, thus preventing steel displacement and embedded part misalignment.

[0042] During the pouring process, designated personnel monitor the pouring volume and speed in real time, observing the flow state of the concrete. If segregation or accumulation occurs, the pouring speed and placement position are adjusted promptly. Simultaneously, the sealing of the molds is checked regularly; any leakage is promptly sealed to prevent affecting the quality of the formed component. When pouring to the design elevation of the component, a 5-10mm allowance is made for vibration shrinkage to ensure that the component elevation meets design requirements after vibration.

[0043] S5, Layered Vibration The method of using immersion vibrators and attached vibrating tables in tandem ensures the concrete is compacted, eliminates internal voids, and improves the structural strength of the components. The immersion vibrators are variable frequency vibrators, allowing for real-time adjustment of the vibration frequency according to the concrete pouring thickness. The vibration frequency is controlled at 50-60Hz, with an amplitude of 0.5-1mm. The diameter of the vibrator is selected based on the pouring thickness, generally 50-70mm.

[0044] During vibration, the vibrator should be inserted quickly and withdrawn slowly, reaching a depth of 50-100mm below the surface of the next layer of concrete. This ensures a tight bond between layers and prevents gaps. Vibration time should be controlled at 20-30 seconds per layer, continuing until the concrete surface is free of air bubbles, smooth with a layer of cement paste, and no longer settles. Over-vibration or under-vibration should be avoided. Over-vibration will cause concrete aggregates to settle and cement paste to rise, resulting in surface defects such as sandiness and cracks. Under-vibration will lead to internal defects such as honeycomb and voids in the concrete, affecting the structural strength of the component.

[0045] The insertion points of the immersion vibrator are arranged in a quincunx pattern, with the spacing controlled at 3-4 times the diameter of the vibrator. Adjacent insertion points overlap by 100-150mm to ensure that the vibration covers the entire pouring area without any blind spots. During vibration, the vibrator must not touch the reinforcing steel cage, embedded parts, or the inner wall of the mold to avoid displacement of the reinforcing steel, misalignment of embedded parts, or damage to the mold.

[0046] While the immersion vibrator is being used for compaction, an attached vibrating table is activated. The attached vibrating table is fixed to the bottom of the mold, and its vibration frequency is controlled at 40-50Hz. This helps eliminate small voids inside the concrete and improves its density. The running time of the attached vibrating table is synchronized with the vibration time of the immersion vibrator to ensure coordinated compaction.

[0047] After vibration, promptly clean any residual concrete from the vibrator to prevent it from setting and affecting future use. Simultaneously, use a scraper to level the surface of the component, then use a trowel to compact and smooth it, ensuring the surface flatness error is ≤2mm / m and that there are no defects such as unevenness, air bubbles, or cracks.

[0048] S6, Precision Maintenance After the concrete is poured and vibrated, curing should be carried out immediately. Curing is divided into three stages: static curing, steam curing and natural curing, to ensure that the concrete strength develops rapidly and stably and to avoid cracks on the surface of the component.

[0049] Phase 1: Static Curing. After pouring, allow the concrete to settle completely for 2-4 hours at room temperature (≥15℃) to prevent premature heating and surface cracking. During static curing, cover the surface of the component with geotextile to prevent rapid evaporation of surface moisture.

[0050] The second stage: Steam curing. After static curing, the components, along with the mold, are sent into a closed-loop steam curing kiln for steam curing. The steam curing kiln is equipped with a waste heat recovery device, with a waste heat utilization rate of ≥40%, reducing energy consumption. Steam curing is divided into three stages: heating period, constant temperature period, and cooling period. 1. Heating period: The heating rate should be controlled at ≤15℃ / h, and the temperature should be increased slowly to avoid excessive temperature difference that may cause cracks on the surface of the component. The heating time should be controlled at 3-5 hours until the curing temperature reaches 50-60℃. 2. Constant temperature period: Maintain a stable curing temperature of 50-60℃, relative humidity ≥90%, and control the constant temperature time to 12-20 hours to ensure rapid strength growth of concrete, reaching more than 70% of the design strength; 3. Cooling period: The cooling rate should be controlled at ≤10℃ / h. Cool down slowly to avoid sudden temperature drops that could cause thermal stress in the components and lead to cracks. The cooling time should be controlled at 3-5 hours until the curing temperature drops to room temperature (the temperature difference with the ambient temperature is ≤5℃).

[0051] During steam curing, temperature and humidity sensors are used to monitor the temperature and humidity inside the curing kiln in real time, recording the data every 2 hours to create a component curing record sheet, ensuring that the curing parameters meet the requirements. If there are deviations in temperature or humidity, the steam supply and ventilation volume are adjusted promptly to ensure a stable curing environment.

[0052] Phase 3: Natural Curing. After steam curing, the components are removed from the curing kiln and subjected to natural curing for ≥7 days. During natural curing, the component surface is covered with geotextile or plastic film to keep it moist. In hot weather (≥35℃), water is sprayed every 2 hours. In cold weather (≤5℃), insulation measures are taken (such as covering with insulating blankets) to prevent the components from freezing or cracking due to rapid evaporation of surface moisture. During natural curing, the surface temperature and ambient humidity of the components are continuously monitored to ensure curing quality.

[0053] S7, Demolding Inspection Demolding can only be carried out when the concrete strength reaches more than 70% of the design strength. The concrete strength is determined by the strength test results of test blocks cured under the same conditions. Before demolding, first remove the fixing bolts of the mold, and use special demolding tools (such as demolding pry bar or jack) to slowly remove the mold. During the demolding process, the movements should be gentle to avoid hard prying or hammering, so as to prevent damage to the corners and edges of the component and scratches on the surface.

[0054] The demolding sequence is as follows: first remove the end molds, then the side molds, and finally the bottom mold. During the demolding process, a dedicated person should monitor the process to prevent the molds from falling or the components from tipping over, ensuring construction safety. After demolding, promptly clean any residual concrete and release agent from the mold surface, and inspect, repair, and maintain the molds to ensure their accuracy and performance for future use.

[0055] After demolding, the precast components undergo comprehensive quality inspection using a combination of laser scanners and manual inspection. The inspection includes: 1. Dimensional Inspection: Inspect the length, width, height, diagonal length of the components, as well as the position dimensions of reserved holes and embedded parts. The length deviation is ≤ ±5mm, the width / height deviation is ≤ ±3mm, the position deviation of reserved holes is ≤ ±2mm, and the center deviation of embedded parts is ≤ 0.5mm. 2. Surface flatness inspection: A 2m straightedge is used for inspection. The surface flatness error is ≤2mm / m, and there are no unevenness, warping or other phenomena. 3. Appearance quality inspection: Check whether there are defects such as exposed reinforcement, honeycomb, pitting, cracks, missing edges and corners on the surface of the component. The area of ​​honeycomb and pitting should be ≤0.02% of the component surface area, the crack width should be ≤0.2mm, and there should be no serious defects such as exposed reinforcement, missing edges and corners. 4. Strength testing: The rebound method is used to test the concrete strength of the components to ensure that the strength meets the design requirements. If the strength does not meet the standard, special testing and treatment will be carried out.

[0056] After the inspection is completed, fill in the precast component appearance quality acceptance record and dimensional inspection report. Qualified components enter the next process; unqualified components are marked, a special repair plan is formulated, and repair is carried out. After repair, they are re-inspected until they are qualified; components that cannot be repaired are scrapped and are strictly prohibited from being put into use.

[0057] S8. Finished Product Processing For precast components that have passed inspection, surface cleaning is performed. High-pressure airflow is used to remove floating dust, residual release agent, and debris from the component surface to ensure that the component surface is clean and tidy. If there are minor defects such as small honeycombs or pitting on the component surface, repair mortar of the same strength grade as the component is used for repair. After repair, a trowel is used to compact and smooth the surface to ensure that the surface flatness of the repaired area is consistent with the surrounding area and there are no obvious repair marks.

[0058] The component surface is marked with information such as component number, production date, strength grade, and inspection qualification mark. The marking location is selected on non-stressed parts of the component, and the font is clear and standardized to facilitate subsequent identification and traceability. At the same time, an RFID chip is embedded in each component. Through RFID chip reading and writing equipment, information such as raw material testing data, production parameters, maintenance records, and test results are recorded to achieve full life cycle traceability of the component.

[0059] Precast components are protected using specialized packaging, which consists of pearl cotton and waterproof cloth. Special attention is paid to protecting the edges, surfaces, and embedded parts of the components to prevent damage during transportation and storage. After packaging, the components are categorized and stacked on a flat, firm surface supported by wooden blocks with a spacing of ≤1.5m. Soft materials are used to insulate the contact points between the blocks and the components to prevent deformation under pressure. The stacking height is determined based on the type and strength of the components, generally not exceeding three layers, and overloading is strictly prohibited.

[0060] After the finished components are stacked, they should be properly labeled and managed. A finished product ledger should be established to record information such as component number, specifications, quantity, production date, test results, and stacking location, so as to facilitate subsequent warehousing, transportation and installation.

[0061] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for precise casting and molding of prefabricated components, characterized in that, Includes the following steps: S1 Prefabrication Preparation: Based on the design drawings of prefabricated components, complete the detailed design of the components, clarify the component dimensions, reinforcement layout, embedded part positions and pouring parameters, prepare molds, reinforcement, concrete raw materials, vibration equipment, curing equipment and testing equipment, and debug and calibrate all equipment, and conduct incoming inspection of raw materials. S2 Mold Precision Positioning: Modular steel molds are used, which are decomposed into bottom molds, side molds, end molds and positioning components. The precise docking of each part of the mold is achieved through double-stage positioning pins and wedge locking mechanism. The flatness, perpendicularity and dimensional accuracy of the mold are tested and calibrated using a three-coordinate measuring machine platform to ensure that the mold positioning error is ≤0.3mm. After calibration, the mold is fixed and a special release agent is applied. S3 Reinforcing Steel and Embedded Parts Precise Layout: According to the detailed design drawings, the processed and qualified reinforcing steel is tied into shape, and the reinforcing steel skeleton is fixed with positioning clamps to ensure that the spacing deviation of the reinforcing steel is ≤±2mm and the thickness deviation of the protective layer is ≤±1mm; the embedded parts are fixed in the mold with positioning seats, the position of the embedded parts is adjusted to ensure that the center deviation of the embedded parts is ≤0.5mm, and a second inspection is carried out after fixing. S4 concrete precision preparation and pouring: According to the strength grade requirements of the components, the concrete raw materials are precisely proportioned, with the measurement error of cement, sand, gravel, water and admixtures ≤ ±1%. The mixing time is controlled at 90-120s to ensure that the workability of the concrete meets the standards. A quantitative concrete placing machine is used for layered pouring, with the pouring speed controlled at 0.5-0.8m³ / h and the thickness of each layer controlled at 200-300mm. The pouring volume and pouring speed are monitored in real time during the pouring process. S5 Layered Vibration: An immersion vibrator and an attached vibrating table are used for combined vibration. The immersion vibrator is operated at a frequency of 50-60Hz, with an amplitude of 0.5-1mm and an insertion depth of 50-100mm below the surface of the lower concrete layer. The vibration time is 20-30s per layer until the concrete surface is free of air bubbles and smooth with a layer of cement paste, avoiding over-vibration or under-vibration. The attached vibrating table operates synchronously at a frequency of 40-50Hz to help eliminate voids within the concrete. S6 Precision Curing: After pouring, first perform 2-4 hours of static curing at room temperature, then enter the steam curing stage. The heating rate is controlled at ≤15℃ / h, the constant temperature stage temperature is controlled at 50-60℃, the constant temperature time is 12-20 hours, the cooling rate is controlled at ≤10℃ / h, and after cooling to room temperature, perform natural curing for ≥7 days. During the curing period, monitor the ambient temperature and humidity in real time to ensure the stability of curing parameters. S7 Demolding Inspection: When the concrete strength reaches more than 70% of the design strength, demolding is carried out. Demolding is done slowly using special tools to avoid damaging the components by prying. After demolding, the dimensions, surface flatness, appearance quality and the position of embedded parts of the components are fully inspected. Unqualified components are reworked, and qualified components proceed to the next process. S8 Finished Product Processing: Clean the surface of qualified precast components, repair defects, mark the component number, production date and strength grade on the surface of the components, use special packaging for protection, stack them in categories, and do a good job of finished product identification and traceability management.

2. The method for precise casting and molding of prefabricated components according to claim 1, characterized in that: In S1, the detailed design of the components is carried out based on the BIM model, integrating data from the entire process of component design, production, and installation, completing collision detection in advance, optimizing the arrangement of steel bars and embedded parts, and generating detailed component processing drawings and production operation instructions; the incoming raw material testing includes cement strength, sand and gravel mud content, steel bar mechanical properties, and admixture compatibility testing, and the raw materials can only be put into use after passing the tests.

3. The method for precise casting and molding of prefabricated components according to claim 1, characterized in that: In S2, the modular steel mold is made of Q345B steel, and the surface is nitrided. The mold thickness is ≥6mm, and the rigidity meets the requirements of not deforming or leaking grout under the vibration condition of C50 and above high-strength concrete. The special release agent is a water-based release agent, and the coating thickness is controlled at 0.1-0.2mm, which is thin and uniform, without any missed coating or accumulation.

4. The method for precise casting and molding of prefabricated components according to claim 1, characterized in that: In S3, the required precision of the steel bar processing is as follows: the steel bar cutting length deviation is ≤ ±5mm, the bending angle deviation is ≤ ±2°, and the inner diameter of the bend meets the specifications; the positioning clamp adopts an adjustable stainless steel clamp with a clamp spacing of ≤200mm to ensure that there is no deformation or displacement after the steel bar skeleton is formed; the embedded parts are made of Q235B material with galvanized surface treatment and a galvanized layer thickness of ≥80μm.

5. The method for precise casting and molding of prefabricated components according to claim 1, characterized in that: In S4, the concrete raw materials include ordinary Portland cement, medium sand, 5-25mm continuously graded crushed stone, high-efficiency water-reducing agent and drinking water; the quantitative placing machine is equipped with a flow sensor to provide real-time feedback on the pouring flow rate, and avoids direct impact of concrete on the steel reinforcement cage and embedded parts during the pouring process.

6. The method for precise casting and molding of prefabricated components according to claim 1, characterized in that: In S5, the immersion vibrator is a variable frequency vibrator, which can adjust the vibration frequency in real time according to the thickness of the concrete pouring; during vibration, the vibrator adopts the "fast insertion and slow withdrawal" method, the insertion points are arranged in a quincunx pattern, the spacing is controlled at 3-4 times the diameter of the vibrator, and the adjacent insertion points overlap by 100-150mm; after vibration, the residual concrete on the surface of the vibrator is cleaned in time.

7. The method for precise casting and molding of prefabricated components according to claim 1, characterized in that: In S6, the steam curing adopts a closed-loop steam curing kiln equipped with a waste heat recovery device, and the waste heat utilization rate is ≥40%. During the curing period, temperature and humidity data are recorded every 2 hours to form a curing record table. During the natural curing stage, geotextile or plastic film is used to cover the surface of the component to keep the surface moist. In hot weather, water is sprayed every 2 hours, and in cold weather, heat preservation measures are taken.

8. The method for precise casting and molding of prefabricated components according to claim 1, characterized in that: In S7, the inspection adopts a combination of laser scanner and manual inspection. The size inspection includes the length, width, height and diagonal length of the component. The length deviation is ≤ ±5mm and the width / height deviation is ≤ ±3mm. The surface flatness is inspected with a 2m straightedge and the error is ≤ 2mm / m. The appearance quality requirements are no exposed reinforcement, honeycomb, pitting and cracks.

9. The method for precise casting and molding of prefabricated components according to claim 1, characterized in that: In S8, the surface cleaning uses high-pressure airflow to remove floating dust and residual release agent from the component surface; the defect repair uses repair mortar of the same strength grade as the component, and the surface flatness after repair is consistent with the surrounding area; the packaging uses pearl cotton + waterproof cloth to wrap, and wooden blocks are used for support when stacking, with a spacing of ≤1.5m between the wooden blocks to avoid deformation of the component under pressure.

10. The method for precise casting and molding of prefabricated components according to claim 1, characterized in that: It also includes a full-process quality traceability system, which embeds an RFID chip in each component and records raw material testing data, production parameters, maintenance records and test results to achieve full life-cycle traceability of the components; the method is applicable to the production of various prefabricated components for assembled monolithic frame structures and assembled monolithic shear wall structures.

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