In previous articles we’ve covered many industry sectors, including power generation, petrochemicals, wind power, oil and gas. This time we focus on construction and mining and explain how on-site machines can be used to fix problems with heavy plant equipment.
1. Worn back hoe and loader pin bores on excavators
When you consider the conditions and demands that excavation equipment are exposed to, it comes as no surprise that the joints of front loaders and back hoe buckets are subject to wear and tear. Many internal bores wear out, becoming oversize or even oval shaped.
So what can be done to repair these components?
Replacing the full component may seem the obvious choice, but in most cases this is not required, as the bores can be refurbished easily using a suitable line boring machine. These machines can be set up to ensure accurate alignment, for example, between 2 hinge pins, with the line boring operation being followed by either welding or shrink fitting new sleeves into the bores.
2. Ball kiln trunnion repair
Above left: Machining a worn trunnion on a ball mill using the Mirage SRB3000-H. Above centre: Illustration of a ball mil (courtesy of Wikipedia Commons). Above right: Image showing the Mirage SRB300-H with counterweight assembly removed to show the facing arm.
Ball mills are used in the mining industry for grinding aggregates such as cement into smaller particles. A ball mill consists of a hollow cylindrical shell rotating about its axis. The axis of the shell may be either horizontal or at a small angle to the horizontal. It is partially filled with steel, ceramic or rubber balls which act as the grinding media.
The When a mining site developed running problems with a ball mill, worn journal diameters were diagnosed as the cause. Mirage developed the SRB3000-H to re-machine the journals, allowing new bearing liners to be fitted in-situ and removing the need to dismantle the trunnions.
3. Crane pedestal bearing faces
When constructing or maintaining crane assemblies, such as those used on oil rigs, one of the components that can require on-site machining is the face for mounting the large bearings (used for rotating the crane arm). These surfaces must be smooth and perfectly level. Projects of this type can be performed using an orbital milling machine or a modified flange facing machine (as shown above right) with a milling head attachment.
4. Rotary kiln roller repair
Source: By HandaKiln (Own work) [CC BY-SA 4.0 (http://creativecommons.org/licenses/by-sa/4.0)], via Wikimedia Commons
A rotary kiln is used to process materials such as Cement, Lime, Titanium dioxide and other materials.
The kiln is a cylindrical vessel on a slight incline which is supported on rollers and is rotated slowly about its axis. The material to be processed is fed into the upper end of the cylinder.
Above: The Mirage BLG1000-H Belt Grinding Machine
Mirage has developed a belt grinding machine (BLG1000) which has been designed to grind the surface of kiln rollers, giving them a new lease of life. The machine is mounted onto a linear rail and is capable of both heavy metal removal and fine polishing.
5. Dragline repair
As with the oil rig crane pedestal faces, the same operation can be carried out on Dragline plant equipment using a large orbital milling machine similar to the OM6000 shown above.
6. Construction vehicle spot facing
A spot facing machine is used during the manufacturing of construction vehicle assemblies and is particularly useful for facing external surfaces of components that rotate or swivel. The machine is mounted into the bore and capable of facing from 2.5 – 10.2” (63 – 260mm).
7. Shaft keyway repair
Many types of heavy plant equipment use keyways are commonly used in rotating plant equipment. When a keyed joint fails this can be repaired by machining the key seat and key way using the Mirage Mini-Mill 3 Axis Key Way Milling Machine which has an X Axis Stroke of up to 8.0", a Y Axis stroke up to 2.0" and a Z axis stroke up to 2.0".
Discover more about on-site machining projects by download one of our case study packs.
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