Boom-type roadheaders, also commonly known as cantilever roadheaders, are mechanical equipment used for tunneling operations in underground engineering projects such as tunnels and lanes.
Cantilever roadheaders must simultaneously realize the functions of stripping coal and rock, loading and transporting, walking and mobilizing the machine itself, and spray dust removal, integrating cutting, loading, transportation, and walking. It is mainly composed of cutting mechanism, loading mechanism, transportation mechanism, walking mechanism, frame and turntable, hydraulic system, electrical system, cooling dust suppression water supply system, and operation control system, among which the cutting arm, turntable, slag plate, conveyor, transfer machine, crawler, etc. are the main working mechanisms.
The main features of cantilever roadheaders include:
1. It can only cut part of the cross section of the lane. The full cross-section rock needs to be broken by moving the cutting head up and down and left and right continuously for many times. It can be used for tunnels of any cross-sectional shape.
2. The excavation speed is greatly affected by the utilization rate of the tunnel boring machine. Under optimal conditions, the utilization rate can reach about 60%. If the rock needs support or other auxiliary work cannot keep up, the utilization rate will be lower.
3. It has some of the same advantages as the full-face tunnel boring machine, such as continuous excavation, no blasting vibration, and can more freely determine the appropriate time to support the rock, which can reduce over-excavation and save the cost of rock support and lining.
4. Compared with the full-face tunnel boring machine, it is smaller and more flexible in the tunnel. It can be used for any type of support, and has the remarkable characteristics of low investment, short construction preparation time and high reusability. The working mechanism has a small size and all important parts are accessible, which is convenient for maintenance and support operations.
There are many ways to classify cantilever tunnel boring machines: according to weight, they can be divided into four types: extra-light, light, medium and heavy; according to the different ways in which the working mechanism cuts coal and rock, they can be divided into longitudinal and transverse axis tunnel boring machines.
In actual applications, different types of cantilevered tunnel boring machines have different technical parameters and applicable working conditions. For example, the EBZ230H cantilevered tunnel boring machine of Sany Heavy Industry has a total weight of 69 tons, a body length of 11.4 meters, a shovel width of 3.6/3.2/3.0 meters, a positioning cutting height of 3.2-4.9 meters, a positioning excavation width of 3.6-6.2 meters, a maximum/economical cutting rock unidirectional compressive strength of 95/75Mpa, a cutting motor power of 230kW, a cutting head speed of 37r/min, an oil pump motor power of 132kW, a ground pressure ratio of 0.15Mpa, a bottom depth of 190mm, a power supply voltage of 1140v, and a climbing ability of ±18°.
When selecting a boom-type tunnel boring machine, it is necessary to comprehensively consider factors such as specific engineering requirements, geological conditions, and cross-sectional dimensions to ensure that the equipment can complete the excavation task efficiently and safely. At the same time, operators need to undergo professional training and be familiar with the operation and maintenance methods of the equipment to ensure the normal operation and service life of the equipment.