A road header, also known as a boom-type road header, road header machine, or header machine, is a piece of heavy excavation equipment that utilizes a special cutterhead mounted on the end of a boom that can swing up or down, left or right.[1] The machine is typically mounted on crawler tracks that enable it to move forward in to the rock face. In addition, road headers deploy a loading device such as a conveyor for the removal of muck sliced from the rock face to the rear of the machine for loading.
Road headers are widely used in the excavation of soft to medium rock in both underground mining and tunneling, and have become a viable alternative to full-face tunnel boring machines to create openings in various configurations and sizes without disturbing the surrounding rock face.[2]
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[edit] History
The first road headers appeared in the early 1950s and were developed primarily for the mechanical excavation of coal.[3]
By the 1960s, road headers were being widely used in tunneling and gradually gained worldwide acceptance by the end of the 1970s.[4]
A number of improvements made over the last 50 years have expanded their initial use in coal mining. The machines have steadily increased in weight, size, and cutterhead power. Developments have also been made in the design of the boom and muck pick-up and loading systems. Today’s modern road headers also come equipped with electrically- or hydraulically-controlled systems that are connect to microprocessor-based guidance and profile control systems.[5]
[edit] Features/How it Works
An increase in the use of road headers in soft rock excavation has been precipitated by a move away from the conventional drill-and-blast method.[6]
The advantage of a road header is that it is more flexible and versatile in soft to medium rock excavation because it has the capacity to excavate and clear muck from the tunnel simultaneously. This is accomplished with additional ground support in the form of rock bolting, shotcrete, steel supports, or a combination thereof.[7]
As a mechanical excavation tool, a road header can also cut a range of cross-sections, change diameter and direction quickly, and move towards and away from the face under its own power.
Though typically mounted on some sort of crawler track, more and more of the machines are being rigged to other types of machines such as hydraulic breakers, trucks, and traveling gentries or even inside shields.[8]
Road headers are available with built-in safety features such as a water-jet spray in the drum that achieves pick cooling and releases a high-pressure spray of water from the pick front head that dissipates dust generated from cutting.[9]
The heaviest road header weighs as much as 120 tons with the maximum power generated from the cutterhead topping off at 500kW.[10]
One drawback of the machine is that the cutterhead blade is not yet durable enough to excavate in hard rock despite extensive field-testing and structural changes made in the machine’s weight, framing, and cutterhead power.[11]
[edit] Common Manufacturers
- Anshan Powerful Heavy Industry
- Dosco Overseas Engineering
- Eickhoff Bergbautechnik GmbH
- Fairchild International
- Industriemaschinen Bergbau Service GmbH
- Joy Mining Machine
- Mitsui Miike
- Sandvik
- Technicore Underground Corp.
- Voestalpine
- WIRTH Group
- Yasinovatskiy Machine Building Plant
[edit] References
- ↑ Roadheaders. Infomine. 2008-09-08.
- ↑ Tatiya, Ratan Raj. Surface and Underground Excavations. A.A. Balkema: 2005
- ↑ Roadheader Application in Mining. 2008-09-08.
- ↑ Roadheader Application in Mining. 2008-09-08.
- ↑ Tatiya, Ratan Raj. Surface and Underground Excavations. A.A. Balkema: 2005.
- ↑ Roadheader Application in Mining. 2008-09-08.
- ↑ Road Header. Construction Machinery. 2008-09-08.
- ↑ Tatiya, Ratan Raj. Surface and Underground Excavations. A.A. Balkema: 2005.
- ↑ Mitsui's Excavation Machine. 2008-09-08.
- ↑ Roadheader. Application in Mining. 2008-09-08.
- ↑ Roadheader. Application in Mining. 2008-09-08.
