Finding an installation guide of Self-Drilling Anchor is easy.
Choosing the right model from a specification sheet is easy.
But if you want to get a deep understanding:
Why are Ischebeck IBO hollow bars more expensive?
Will Chinese-Made be reliable enough for my drilling/reinforcing works?
Similar rolling machines and materials are used, why onton anchor bars still outperform?
The article is just about the secrets you want to know about the manufacturing of IBO Drill Hollow Bars.
As we know, hollow bar anchors are mainly used as micropiles, soil nails, and rock bolts.
The corresponding standards are EN 14199 and EN 14490.
And the material properties are according to DIN EN 10204.
A typical product specification and load-bearing capacities are as follow.
If you’ve run an SDA anchor rod producing line, you know that it is not easy to boost strength and elongation together.
Of course, you can use the steel material with high elongation composition.
That’s why you see the variety of materials in the market (within the specified range of standards).
Unfortunately, in fact, raw material plays only a limited function in the performance.
Briefly speaking, no matter what materials you use, only a proper process can yield a performance boost.
Interesting in the production process of SDA drill anchors?
Just keep reading.
Hollow grouting threaded anchor rolling mill is the main part of SDA production lines.
The rolling mill is assembled with three or five rolls. Power is transferred to gear reducer by motor transmission belt. Then the thread is formed by the rotating rolls.
Specifications of typical rolling mills:
|Spiral pitch (mm)||10-12.7||10-12.7||10-12.7||10-12.7|
|Max. rolling capacity (kN)||700||800||1200||1700|
|Main power (kW)||7.5||7.5||10||15|
|Hydraulic power (kW)||5.5||5.5||7.7||9.9|
The critical technologies for mass production are material properties and the control of broken rate.
Thread rolling seems easy but takes the most advantages of the metals will be a puzzle for some naïve manufacturers.
For example, knockoff knife is Swiss Army knife lookalike, but it would bring unexpected troubles if underperformed.
One more step, expect the cold rolling,
The hot-roll Forging process to produce hollow bars for use as Self-Drilling Rock Bolts is introduced.
It combines on-line rolling and remained heat treatment technique, reduces wasting and brings stronger hollow drill rods.
According to the production practice, there are couples of advantages for the hot-rolled IBO hollow bars:
Since the complexity of heat treatment process, the time and energy consumptions of producing SDA hollow bars are relatively high.
But it has been proved that well hot-rolled SDA rock bolts perform much better than the anchor bolts made in traditional methods.
The first Chinese made self-drilling anchor was made by Onton in 1992. It was just an imitation of the famous Atlas Copco SDA.
In the next decade, cold rolling was applied but the products are not so balanced in the mechanical properties.
Since the standards raised, as the high-speed railways building, the high elongation is required to improve the quality of tunnel projects.
The third innovation in Self-drilling anchor manufacturing technique was complete around 2006. And it is the basis for the methods as mentioned previously.
Below you can click to see the complete timeline of the history of self-drilling anchor manufacturing.
Evolution line of self-drilling anchor production technology
The packing of marine cargoes is always important, especially for full thread rebars. We pride ourselves on providing only the best packing solution for all our anchor bolts to ensure safe shipping and flawless deliveries.
Click to see how we package IBO hollow bars to protect them from corrosion, mechanical damages, and dirt accumulation until assembled on the construction site.
The default packaging material is waterproof fabric, protected against splashing water.
What’s more, it’s free. Onton doesn’t charge for fundamental wrapping.
Though self-drilling anchor rock bolts are anti-rust oil coasted, sometimes composite packaging is required to prevent from a harsh environment.
Take another look at the above illustration and you will find the IBO anchor bolts have been wrapped under the waterproof fabric covered.
In fact, there are additional three layers for this kind of packaging.
This way of packing is specially designed to improve the waterproof effect.
The rust of the steel influences the entire service life of self-drilling anchor.
The range of IBO hollow bars is wide.
ONTON’s range covers various steel grades from 200 to 1800kN in ultimate load, and rope thread diameters from R25 to R51, T thread diameters from T30 to T76.
In order to have enough assortment of products ready to be shipped, to reduce the lead time, a separate storehouse is established.
For tunneling projects, small diameters SDA rock bolts (R25, R32) are mostly used in the method of NATM.
And in this range, ONTON’s abundant supply inventories can meet customer demand promptly.
First please note our factory is located inland, away from the eastern coast.
There are two ways for the transportation:
When time is not a big issue, you can choose the second solution to save costs, especially for big quantity.
This item is totally customizable: no matter shipping marks or special logo marked onto Self-drilling anchors.
Identification marks on reinforcing bars are now requested by most international standards.
ONTON has the technology of rolling marks onto SDA hollow bar anchors.
Sometime this would be very useful, especially for significant projects since it brings:
WT is short for the Chinese name of ONTON
During the packaging, we paste shipping marks on the surface of each package.
The marks will be appointed by customers. It normally consists of the consignee, product models, package numbers, origin, etc.
Thus, you can easily distinguish the models of Self-drilling anchor without unwrapping the waterproof fabrics.
Based on an in-house production control and a long-term rolling experience (almost 26 years, specializing in self-drilling anchor bolts), Onton brings stable anchor products with high quality.
Here are some key data on our anchor bolts manufacturing:
The thread dimensions of ALL anchor hollow bars are continuously monitored with thread gauges.
The thread geometry is according to ISO 10208, Rock drilling equipment: Left-hand rope threads.
For other types like T thread, onton implements internal standards.
Worry about mismatching?
It is possible to happen. But don’t have to be too worried.
T thread self-drilling anchors are not quite the same as famous Ischebeck Titan anchor bars or Dywidag T Thread drill rods. But it is available for those companies’ drill equipment.
There are still other SDA systems around the world. Those types can be produced specialty.
TWO specimens are taken from each batch after the thread rolling, we call it as “first testing”.
It is a tensile test which includes examining 0.2% yield strength, ultimate strength, and elongation at maximum load (Agt). Exact technical indicators are set up to guarantee the performance.
About strength and elongation, this article may help:
2 Tips for choosing a qualified Self-Drilling Anchor IBO
Randomly sampling at least THREE finished SDA bolts from a single batch (100-200 PCS).
The tensile test qualification rate should be 100%.
We call it as “finished bar examines”.
We know self-drilling anchor bolts are used in the fields of mining, tunneling and reinforcing works. Safety is a big issue for those projects.
That’s why onton insists on the quality. Unstable raw materials are rejected. Good quality is guaranteed from the original steel tubes carried to our SDA factory.
About production, quality control
Now do you get the answers to the questions at the beginning of this article?
Producing Self-drilling anchor is not just to roll a thread onto a steel tube.
We need to improve the properties, decrease breakage rate, keep stable for EACH METER.
If you want more information about self-drilling anchor rock bolts, let me know.