Design of a High Pressure System to Aid Horizontal Directional Drill Bit Steering
Dustin Holden, Curtis Johnson, Brandon Kimbrell, Kristin Stephens
Horizontal Directional Drilling (HDD) is a technique that provides a means of installing underground utilities without cutting a trench in the soil (i.e. trenchless). Several equipment manufacturers have been successful in designing, manufacturing, and marketing units for this task. HDD equipment typically performs well unless the soil is very hard. A senior design team, The West Central Pump Works, Inc., under the direction of Dr. Paul Weckler, was challenged with this problem by one of the equipment manufacturers and was asked to develop a creative solution.
Ditch Witch has come to the team, looking for creative solutions to their design problem. Ditch Witch JT520 units are used for compact horizontal directional drilling (HDD) tasks. They are ideal for shallow product installations and are commonly used in residential areas. Relative to larger Jet Trac units, the JT520 is a comparatively low powered unit. The problem presented to the team involves complications the unit encounters when steering the drill head through compacted soils. Current operation of the unit involves a rotating bit (beacon) that is continually lubricated with drilling fluid. When steering of the beacon is required, rotational motion is stopped and the bit is forced (pushed or thrust) through the soil. When it reaches the desired position, rotational motion is resumed. A problem arises when the soil is too solid for the beacon to push through during the steering process.
Scope of Work
Ditch Witch is requesting a design that solves the challenges of injecting a high pressure fluid through the drill string for a short period of time to aid in steering the beacon in hard, dry soil conditions. Ultimately, the team will be concerned with producing high pressure down the drill pipe to achieve a high velocity stream of fluid to erode material in the drill path. Consultation with the sponsor after the fall semester led the team to the development of a dual hydraulic cylinder system solution to the design problem. The system will be designed so that Ditch Witch will be able to implement it into future unit models. While the ultimate design factor controlling the problem solution is a high pressure, high velocity jet of water, other factors play a key role in the design process.