In ancient China, the fable of the Foolish Old Man Moving the Mountains illustrates the indomitable spirit of perseverance through slow and steady effort.

When humanity entered the 18th century, the First Industrial Revolution brought about not just a technological transformation but also a profound social change, ushering in an era where machines began to replace manual labor. Since then, the rock drilling and excavation industry has rapidly advanced towards faster, more durable, and efficient methods. During this process, various thread forms for drill rod connections, including API standard threads and wave-shaped trapezoidal threads, were developed.

The operational principles of these threads differ, leading to different requirements. A senior technical expert in the drilling industry has publicly discussed the threads of roller-cone drill rods and top hammer drill rods. The insights offered are so valuable that they are said to be worth more than a decade of study.

Petroleum roller-cone bits operate by rotating and crushing rock, with drill rods using API standard threads. These threads only bear axial thrust, torsional forces, and some impact forces, without transmitting impact energy to the rod body. The API standard threads are designed primarily for connection, fastening, and sealing, resulting in minimal energy consumption and negligible overheating.

In contrast, top hammer drill rods typically use R-shaped or T-shaped threads. The energy from the hydraulic rock drill is transmitted through the rod to the drill bit, leading to significant energy loss as heat at the thread connections, with temperatures potentially exceeding 400°C. If API standard threads were used for top hammer rods, not only would they be inefficient at energy transmission, but they could also suffer from erosion, making the drill rods difficult to disassemble and severely affecting construction efficiency and increasing costs.

In the 1970s and 80s, extensive research was conducted by foreign experts on the threads used in top hammer drill rods, considering wave-shaped, composite, reverse serrated, FL, and trapezoidal threads. It was concluded that wave-shaped threads are suitable for rods with diameters under 38 mm, while trapezoidal threads are more appropriate for rods with diameters between 38 mm and 51 mm.

In the 21st century, with the increasing diameter of top hammer bits and considerations of thread root strength, various drilling tool companies have introduced new thread types such as SR, ST, and GT through continuous research and development.

In summary, during the rock drilling process, the thread connections on top hammer drill rods are one of the primary areas of energy consumption and a major factor in early drill rod failures.

As Buddhism teaches, "dependent origination is empty, and one should not cling to any single method." With the ongoing advancements in science and technology, it is worth pondering whether the currently used thread forms are the best and final solution for connections in the hydraulic drilling industry.