Advantages of deep hole drilling high pressure cooling system

Release time:

2022-06-02

Deep hole refers to the hole with the ratio of hole depth to hole diameter L/d≥ 5, which is a difficult problem in machining. The high-pressure cooling system for deep hole drilling is in the processing of deep holes with large depth-to-diameter ratio. There are difficulties such as slender tools, low rigidity, low strength, and easy tool deflection. In addition, it is difficult to dissipate heat, chips are not easy to discharge, and diameters become larger. Taper, hole deflection and other phenomena often occur, which cannot meet the quality requirements. Then, let's learn about the design and analysis of the high-pressure cooling system for deep hole drilling!

Deep hole refers to the hole with the ratio of hole depth to hole diameter L/d≥ 5, which is a difficult problem in machining.High pressure cooling system for deep hole drillingIn the processing of deep holes with large depth-to-diameter ratio, there are difficulties such as slender tools, low rigidity, low strength, and easy to cause tool deflection. In addition, heat dissipation is difficult, chips are not easy to discharge, diameters become larger, and taper and holes often occur. Deflection and other phenomena cannot meet the quality requirements. Then, let's learn about the design and analysis of the high-pressure cooling system for deep hole drilling!

Process Design and Analysis of High Pressure Cooling System for Deep Hole Drill

The high-pressure cooling system of deep hole drill adopts regular drilling method, which requires lengthened twist drill. Moreover, due to chip processing, not only the processing accuracy is low and the surface roughness is poor, but also the processing efficiency is low, the labor intensity of workers is high, and the quality is difficult to guarantee. It is also easy to cause chip and chip equipment selection. Considering that our factory has many product types, deep hole processing product structures are very different and production batches are small, it is impossible to purchase special machine tools, in order to better ensure the deep hole accuracy requirements, combined with the actual factory, select the appropriate processing equipment to meet the technical requirements of deep hole processing.

1. Tool selection

　　High pressure cooling system for deep hole drillingTools are gun drill, jet drill, drill, hard alloy indexable deep hole drill, cutting chip deep hole drill, sub-dry deep hole processing system and other types.

After the comparison of the above several deep hole processing tools and the actual situation of our company, the study decided to use the gun body drill bit composed of the front end of the carbide drill bit, the drill pipe and the handle for the deep hole processing. The front end of the gun body bit is provided with an oil hole to strengthen the cooling and lubrication of the bit and make the chips discharged smoothly. In addition, choosing cemented carbide with excellent toughness and vibration resistance as the substrate and coating the surface with TiC or TiN can improve the hardness and wear resistance of the drill bit. The drill pipe generally uses 40Cr seamless steel pipe. The principle is that high-pressure oil is injected from the hole at the rear of the drill, and after reaching the cutting area through the waist-shaped hole, it discharges chips from the space between the V-shaped groove and the wall of the workpiece hole together with the cutting fluid, so it is called external chips. For manufacturing, the rake angle of such a deep hole drill is usually 0. There is no chisel, the drill tip deviates from the axis, the drill tip forms a small cone, and the chips are cut into two sections at the drill tip for easy discharge.

2. Equipment

The gun drill is used to drill the hole in the center of the rotating workpiece. When processing, the workpiece usually rotates and the drill bit is fed linearly. Suitable for lathes and vertical machine tools with machining centers and high-pressure cooling systems, tool and workpiece rotation. Comprehensive gun drilling processing applications and the company's existing equipment, in the processing of the parts, the author chose the milling compound machining center. The equipment can not only realize the rotation of parts, but also equipped with high-pressure internal cooling system, which can meet the application of gun drilling. Drilling can be carried out.

3. Gun Drill Guide Hole Machining

The gun body bit is an unbalanced bit, and the unbalanced groove shape means that the cutting force is unbalanced. In order to reduce the radial cutting force around the drill bit, it needs to be shared by the guide or the guide hole. A typical gun machine tool is equipped with a gun body guide sleeve. The milling machining center selected in this example is not a gun body machine tool. There is no guide sleeve or fixture, and the guide sleeve cannot be designed. To this end, the author considers the use of drilling to balance the gun body cutting force. A large number of experimental data show that the depth of the guide hole of the gun body bit is 1~2 times of the diameter of the gun body bit, and the diameter should be larger than the diameter of the gun body bit by 0.004~0.012mm.

4. Process Test and Analysis of High Pressure Cooling System for Deep Hole Drilling

The deep hole drilling high-pressure cooling system uses soft three-jaw clamping, positioning, and clamping, and performs deep hole processing of parts in the order of the deep holes of the guide holes on the end of the car. When drilling, drill bits from different manufacturers are used to test and process with different cutting parameters. When digging deep holes, we choose watermelon gun body drill bits, and use different processing methods and different cutting parameters to test multiple holes.

1) Guide hole processing

Under the premise of meeting the guiding role of the gun body drill bit when drilling, the author also considers the cost of the tool, and selects the imported watermelon hollow inner cold alloy drill bit and the domestic siping alloy drill bit for trial cutting.

2) Deep hole processing

The deep hole processing adopts two processing schemes for experimental processing. One is to process the deep hole with a rotation speed and feed speed less than that of the drill when entering the guide hole and exiting the deep hole. The other is to reverse the rotation speed and feed speed into the guide hole with a lower rotation speed and G0. The experimental processing results show that the processing efficiency is low, the surface quality of the parts is poor, while the second processing method has high processing efficiency and good quality.

The above introduction isHigh pressure cooling system for deep hole drillingFor more information, please feel free to contact us!