1. Technical principle and working mode
The tractor-driven lime-soil mixer (abbreviated as road mixer) is a soil improvement equipment based on the road mixing method. The tractor power output shaft (PTO) drives the cutter shaft to rotate, realizing on-site crushing, turning and homogenization mixing of soil and stabilizers (such as lime and cement). Its core technologies include:
Power transmission system: The tractor rear-mounted three-point suspension connection is adopted, and the power is transmitted to the cutter shaft through the universal joint drive shaft and gearbox. The double-row or three-row chain drive design (such as SAAO-1600 model) can withstand greater torque and ensure the continuous operation stability of high-viscosity soil.
Forward and reverse cutter shaft technology: Adjust the rotation direction according to different soil types. The forward mode (cutting from top to bottom with the cutter head) is suitable for soft soil layers, and the reverse mode (crushing from bottom to top with the cutter head) is used for hard road surface or asphalt milling, and the cutting depth can reach 400mm.
Cold mixing process: No pre-drying is required, and the wet soil and stabilizer are mixed instantly through the high-speed shearing and throwing of the cutter head, and the uniformity of a single operation reaches more than 90%.
2. Core structure design
Transmission module:
Gearbox and sprocket group: The bevel gear split transmission (such as double transmission structure) is adopted to evenly distribute the power to the double-side chain to reduce the load on one side. The gearbox is equipped with a flange and a thrust bearing, supports an input speed of 540-800r/min, and is suitable for tractors with 60-200 horsepower.
Knife shaft and tool configuration: The thickness of the knife shaft tube is up to 60mm, and it is equipped with L-type, chisel-type or alloy bullet-type tools. The alloy bullet adopts tungsten carbide coating, and its service life is increased by 3 times compared with traditional blades. It is suitable for complex working conditions containing gravel or construction waste.
Depth and width adjustment system: The landing gear is controlled by a hydraulic cylinder to achieve 0-420mm mixing depth adjustment. The widened model (such as the 2000 model) has a mixing width of 2 meters and a daily processing area of more than 7,500 square meters. Equipped with a beam scraper, it can synchronously level the mixed ash soil layer and reduce the secondary paving process.
Protection and durability design: The outer shell adopts an 8mm thickened steel plate cover to prevent debris splashing and reduce noise. The three-row chain transmission system is equipped with a double protector to avoid overload damage. The modular design supports the rapid replacement of the blade or chain, and the maintenance time is shortened by 40%.
3. Application advantages and scene adaptation
Efficient construction capability: The workload of a single road mixer is equivalent to that of 100 people working at the same time. It is especially suitable for large-scale road base treatment (such as highway roadbed and airport runway expansion). The unconfined compressive strength of the mixed ash soil can reach 2-4MPa.
Case: In the foundation treatment of the Yellow River flooding area, the Lei Chuang 1800 mixer is combined with a silicate curing agent to replace the traditional three-in-one soil process, reducing the dredging cost by 30%.
Material adaptability: It can process various formulations such as fly ash soil, cement stabilized sand, and oily sludge. By adjusting the cutter head spacing and speed, the particle size control (0.5-5mm) can be achieved to meet different compaction requirements. Special models (such as crushing type) can process recycled mixtures containing bricks and old asphalt pavement, and the crushing particle size is ≤50mm.
Economic analysis: Compared with the factory mixing method, the road mixing method reduces material transportation and site costs, and the comprehensive construction cost is reduced by 25%-40%.
4. Technological innovation and development trend
Hydraulic mechanical continuously variable transmission (HMCVT) integration:
The new 200-horsepower tractor is equipped with hydraulic power diversion technology to achieve automatic matching of mixer speed and travel speed, and improve fuel efficiency by 15%-30%, which is suitable for plateau or low temperature environments.
Intelligent control upgrade: Integrated moisture content sensor and GPS positioning system to monitor mixing uniformity in real time and generate electronic construction logs. AI algorithm can optimize the cutter head speed and travel path to reduce manual intervention.
Modular and environmentally friendly design: The detachable blade shaft module supports fast switching of mixing/milling functions, expanding the application scenarios of the equipment (such as farmland soil improvement). The closed mixing chamber and exhaust gas purification system reduce dust and VOCs emissions, which meets the environmental protection requirements of the "Soil Pollution Prevention and Control Law".
Industry Outlook:
With the advancement of the domestic "dual carbon" goals, the combination of electric tractors and biomass fuel power systems will become a key direction for the green upgrade of road mixers. At the same time, the penetration of high-precision navigation and 5G remote control technology will promote the development of road mixing operations towards unmanned and intelligent.
