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Standard and special deep drilling machines – Gundrills
Advantages of deep hole-drilling
- Optimal work regimes
- Good quality of boreholes, considering the tolerance of diameter, quality of surfaces and geometric accuracy of shapes
- Good conditions for cooling and lubricating
- High accuracy of run-out
- It replaces more steps of the work procedure, for example pre-drilling, redrilling etc. with one single procedure of “deep hole drilling”
- Processing of materials that are difficult to process
- Large drilling depths in one cycle of drilling (up to 250mm diameter)
- Continuous and not complicated removal of chips
Positive characteristics demand
- Stable implementation of machines
- Adequate devices for cooling and filtration
- Use of modern machine elements
- Steering technique with functions of tool supervision
Drilling Systems
Drilling with system ELB (Single Lip Drill)
As a basis in all three systems we need a drilling bush, which at the beginning of drilling leads the drill as long as it needs for the drilling head to completely penetrate the material which is being processed. The cooling medium, which can be cutting oil or emulsion under high pressure, enters from the back side of the driving mechanism and passes thru the spindle and through the drill onto the cutting part of the drilling head. Cuttings exit together with the cooling medium through the lateral groove of the drill and fall thru the holder of drilling bush into the drain tap of chips.
Drilling with system BTA or STS (single tube system)
The characteristic of this system is that it is intended for drilling holes of bigger dimensions from 20 mm and up. The tool is composed of a tube that is fitted into the driving spindle, and crown drilling head that has hard-metal cutting plates that are brazed or screwed. The way of the cooling medium is reverse as at the ELB system. The cooling medium enters under pressure next to the tube onto the drilling head and onto the cutting plates, there it cools off the cuttings and then together with them passes through the tube, driving spindle and exits on the back side of the driving spindle and continues to the drain tap of chips.
Drilling with system EJECTOR
This system is intended mostly for the construction of deep hole-drilling onto different processing centers that have hollow driving spindles. It is composed of a crown drilling head, two tubes which are inserted one in another and of an injector that serves as an inlet for the cooling medium. The cooling medium passes between the tubes onto the drilling head, where it takes over the cuttings, and returns through the inner tube and through the driving spindle into the drain tap of chips.
