Horizontal directional drilling, commonly referred to as HDD, is a process used in a number of applications such as installing utilities underground. The HDD process, regardless of the application, includes a pilot hole-boring step. In this step a bore hole is created that extends underground—generally horizontal or parallel to the surface of the earth—starting at a launch point and ending at a termination point.
The bore hole is created by positioning a boring machine to rotate and push a drill string through the ground. A drill bit is attached to the leading end of the drill string. The drill string is created by connecting individual drill rods together end-to-end from a supply of drill rods stored on the boring machine. The connection between the rods is made up, and subsequently broken in a later step, by the boring machine. A typical boring machine includes a gearbox that connects to the drill string, a drill rod storage magazine, and a rod loading mechanism. The rod loading mechanism moves the individual drill rods from the storage magazine into alignment with the drill string and the gearbox where the individual drill rod is connected to and made a part of the drill string.
Rod loading mechanisms typically include a rod transfer mechanism that moves the rod from the storage magazine and positions the rod with one end in alignment with the drill string and the other end in alignment with the gearbox. Typically, when the drill rod is not being used as part of the drill string, it is stored in a plurality of columns within the storage magazine. In many of these systems, the drill rod is removed sequentially from the first column of the storage magazine proximal to the drill string. After the first, proximal column is emptied, then drill rod is taken from the next adjacent column. Depending on the number of drill rods required for the application, the drill rod is removed column by column until the most distal column is emptied. When the drill string is later broken down, the reverse procedure is utilized, whereby the most distal column is filled first, with next closer adjacent column filled next, and continuing until the proximal column is filled.
The above method is especially used with rod transfer mechanisms that employ a single rod blocking member, with a rod receiving pocket, or grip, located proximal the drill string. The rod receiving pocket may be located physically adjacent the rod blocking member or may be part of the same structure. In either event, however, if the rod receiving pocket is indexed past a column that is not yet emptied, then the drill rod from that column is unintentionally released into the drill string area. Since the drill rod is generally both long and heavy, drilling must cease until the drill rod is untangled and removed from the drill string area. This creates an inefficient and aggravating situation.
In order to insure that the rod transfer mechanism is properly indexed to the appropriate column, mechanical stops have been employed in the past. However, to set the stops to the correct index position, the operator needed to stop drilling, leave the operator position, move to the magazine area, and then manually set the stop. Alternatively, a second person needed to set the position. In either instance the process was inefficient. Therefore, there is a need in the art for a method and apparatus for efficiently and correctly setting the index position for the appropriate column of a drill rod magazine of an HDD machine from the operator position. The present invention overcomes the shortcomings of the prior art and addresses these needs in the art.