Extract from Sai Journal - Issue 2, 2010
It is said that the first drilling rig was built many hundreds of years ago in the Chinese city of Zigong where the people have been drilling for brine, from which they extract salt, since before the Han Dynasty (76-88 A.D.).
Today our life wouldn’t be possible without drilling and drilling equipment. Our homes are standing on piling systems made by using drilling machines. Much of the water we drink comes from the ground through holes that have been bored using drilling equipment. Also, since we need more water every day, it becomes even more necessary to find it at deeper levels in the ground.
For the same reason of higher demand – fossil fuel is searched for at deeper and deeper levels everyday challenging the limits of drilling operations on a daily basis. Even in catastrophic events like the collapse of a portion of the San Jose copper-gold mine in Copiapo Chile, the men trapped underground have been rescued making great use of essential drilling technology.
Moreover, drilling is now becoming strategic for the transformation of our urban life into a “greener” one. In the not too distant future, our household heating systems are likely to be based on hot water coming from the ground.
Last but not least, many people living in arid regions will have water taken from very deep holes drilled in the ground and life in such places will be much easier and more enjoyable. However, despite being something that mankind has done for hundreds and hundreds of years, there is still a lot that can be done in order to enhance the potential of drilling operations.
SAI has recently developed a new range of motors and drive units that can offer a great deal of new possibilities when used in drilling machines. The higher power and displacement density make these drives unachievable by any other solution on the market.
The core element is the SAI motor with its well known method of operation based on an eccentric crankshaft and swivelling cylinders. This has been the subject of further development by the introduction of the innovative variable eccentricity crankshaft. The crankshaft can now be produced to provide a variation of its eccentricity, in a continuous way, from maximum to zero.
Consequently, the displacement of the motor can vary likewise adapting the torque and speed output of the drive to the operational requirements of the machines.
This shift can be achieved extremely quickly or very slowly depending on the needs of the application. The shape of the ramp and the response of this variation can be adjusted electronically and mechanically, and fine tuning can be achieved very easily directly on the machine during the initial running and validation of the application.
The long-established high volumetric efficiency of SAI motors lends itself to very accurate controllability of rotational speed even at times of vastly varying load/pressure. The high starting efficiency offered in every displacement within the range permits the overcoming of obstacles found during the drilling operation whether these be at start up or during low speed running. These characteristics make SAI motors very flexible and easy to use when drilling any ground condition.
A multiple motor set up offers enhanced variation possibilities giving way to an extremely wide operational range of the machine. Variable motors can be controlled separately or with a single input signal and the "addition" or "elimination" of motors can be done automatically without stopping the drilling operation. The increased power density of the T Series motors, that can now work continuously at 350 bar, and that can reach peak pressure in the range of 500 bar, allow the drilling machine to make efficient use of the installed power. This, together with the high speed characteristics of the SAI motors, allows them to make profitable use of the maximum oil flow installed on the machine therefore reducing drilling time.
Multiple smaller motors offer an advantage of a single motor by providing high turn down ratios between maximum and minimum speed of up to 12:1. The power level is available from 70 Kw through to over 300 Kw.
The high resistance to cavitation, typical of SAI motors, reduces the complexity of valving systems and consequently the size of the drive and its accompanying costs. The latest range of SAI motors have been designed to achieve an extremely long lifetime. Hence, they can be used in harsh environments or for continuously long periods leading to reduced maintenance and operational costs.
All of the above results in increased machine productivity and consequently higher operational profitability.
Custom Fluidpower is the authorised Australian supply, service and repair centre for the complete range of SAI Hydraulic motors.
Custom Fluidpower is a wholly Australian owned company offering hydraulic, pneumatic, filtration and lubrication product sales along with complete system design, installation and commissioning, and service and repairs. Custom Fluidpower services the agricultural, aerospace, exploration, industrial, marine, mobile, mining and material handling industries Australia wide. For further information visit www.custom.com.au.