Characteristics and Processing Methods of Self – drilling anchor bolt’s Thread

self drilling anchor bolt‘s thread

Sinorock self-drilling anchor system is an advanced anchoring system that can directly perform drilling and grouting in loose soil and fractured rock formations, which include continuous full-thread hollow anchor bolts and other accessories. Self-drilling anchor system can be used as micro-piles and soil nails, which is a fast and efficient rock and soil anchoring solution.
The thread of self drilling hollow anchor rod is very similar to that of the ribbed rebars. The pitch is large and depth of the teeth is deep. The connected surface threads can not only bind to the cement, but also provide good adhesion and friction.At the same time,it can Increase the length at any time.

The processing of external thread of the self drilling anchor bolt needs the three axis thread rolling mill . Because the raw material is hollow steel tube the rolling of the two-axis rolling mill is prone to elliptical, flattening and even cracking of the hollow anchor bolt, so the thread of hollow anchor bolt by using the three axis thread rolling mill for processing is form well and high ,which can meet the needs of drilling construction.
There are two kinds of threads on the surface of the hollow anchor bolt, one is in line with ISO10208 standard R-type thread, one is to provide greater support standard T-type thread,the T-type teeth is deepened so that it can reach more area of concrete ,usually the T-type thread friction force is more than 2 times than R-type adhesive force,T-type self drilling anchor bolts are usually used in the use of micro-piles occasions.

There are two methods for processing of self drilling anchor bolt, cold rolling and controlled rolling, cold rolling change the grain structure by cold rolling and improve the yield strength, controlled rolling can be used according to the different needs of the scene to change the mechanical properties of the hollow anchor bolt, controlled rolling is more effective for ensuring the metal structure of the hollow anchor bolt, the grain is more small, which is more suitable for high elongation requirements of the occasion to meet more customer needs.

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