HTS drill bit - extraordinary results of efficient machining
2018-09-25 17:01:25
Improving processing efficiency has always been the dream of many manufacturers. Because of the increase in processing efficiency, it not only means a shortened production cycle and a reduction in financial costs, but also often means a significant reduction in manufacturing costs. The Harbin Steam Turbine Works ("Haqi"), located in the industrial base of Northeast China, has greatly improved its processing efficiency when its products are in short supply, and has achieved extraordinary results.
When Haqi was processing and manufacturing the first 600,000 kW supercritical steam turbine in China, large-diameter deep hole machining became a problem that caused it a very headache. The coupling hole of the facet in the outer cylinder of the steam turbine unit has a maximum diameter of 140 mm and a depth of 600 mm. Initially they used the traditional method commonly used in China - drilling with high-speed steel twist drills and then gradually reaming. The diameter of the hole is 60mm, and then the hole is not more than 15mm at a time. With such a processing method, it takes about 6.5 hours to drill one hole, and the processing cycle of all 200 holes exceeds 40 days.
Mr. Luo Yang is the director of the tool room of the Haqi Third Branch. He chose to use Kennametal's HTS drill bit. HTS is a modular indexable drill bit. Due to the use of indexable inserts, it can be adapted to different machining tasks by selecting different materials, different coatings and different grooved inserts. Both internal and external knives, ranging from four to 12 blades and four sized blades, cover a wide range of diameters from 45mm to 270mm. This design allows the entire hole to be drilled at one time without the need for multiple reamings, and the cutting speed is greatly improved. Moreover, due to the reasonable groove shape of the blade, the vibration generated on the machine tool is very small, and the influence on the machine tool is small. When using high-speed steel drill bits, they had an accident of machine tool overload damage, and the cutting became very smooth after using the HTS drill bit.
The centering of large-sized indexable drill bits has always been a problem. Since the inserts of the indexable drill bit are distributed over different diameter segments to complete the entire cutting task, the cutting force is always difficult to achieve equilibrium. Therefore, the drill bit will produce some offset under the action of this combined force of cutting. The greater the diameter of the drill bit, the more pronounced the tendency of this offset. Harbin's original process plan requires multiple reaming, which also includes the role of correcting the offset of the previous step. The centering drill in the middle of the HTS drill bit is placed to contain this offset. Therefore, when using HTS drilling, Harbin does not need to ream several times, but can complete the entire machining task in one drilling.
The drive ring is also an important part of the HTS drill bit. It will ensure that both the drilling head and the machine tool will not be damaged by the shear fracture of the male key during the drilling torque overload.
The HTS bit must be used with the cutting fluid, where the cutting fluid plays a major role in chip removal. Drilling is a closed environment where all chips must be removed from the gap between the drill pipe and the hole. Due to the high processing efficiency, the amount of chips generated per minute is large, and the high drilling torque makes the diameter of the drill pipe too small, which makes the chip removal efficiency very important. In many cases, the efficiency of drilling is limited by the efficiency of chip removal and it is difficult to perform better. The cutting fluid of the HTS drill bit is fed from the center of the tool to the drilling head, which in turn flushes the chips from the gap between the drill pipe and the hole. Therefore, the greater the pressure and flow rate of the cutting fluid, the better the effect will be. Through the transformation of the machine tool, Haqi realized the conversion from external cooling to internal cooling, which increased the cooling pressure, thus preparing the necessary conditions for the rational use of the HTS drill bit. This series of designs provides a revolutionary solution for large diameter deep hole machining. Taking Haqi as an example, using this drill bit, its multiple steps are combined into one, and the cutting speed is increased by about 8 times. The original hole machining requires 6 tools and 6.7 man-hours. Now only one tool and only one tool is needed. 0.5 working hours, reducing processing time by 93%.
Haqi is very satisfied with this result. They have extended this kind of drill bit and some of their experience from the three-point factory to other branch factories. Nowadays, the steam turbines of Haqi are basically processed with such drill bits, which is very efficient. In Luo Yang’s words, the most direct feeling of front-line operators is “savingâ€.
When Haqi was processing and manufacturing the first 600,000 kW supercritical steam turbine in China, large-diameter deep hole machining became a problem that caused it a very headache. The coupling hole of the facet in the outer cylinder of the steam turbine unit has a maximum diameter of 140 mm and a depth of 600 mm. Initially they used the traditional method commonly used in China - drilling with high-speed steel twist drills and then gradually reaming. The diameter of the hole is 60mm, and then the hole is not more than 15mm at a time. With such a processing method, it takes about 6.5 hours to drill one hole, and the processing cycle of all 200 holes exceeds 40 days.
Mr. Luo Yang is the director of the tool room of the Haqi Third Branch. He chose to use Kennametal's HTS drill bit. HTS is a modular indexable drill bit. Due to the use of indexable inserts, it can be adapted to different machining tasks by selecting different materials, different coatings and different grooved inserts. Both internal and external knives, ranging from four to 12 blades and four sized blades, cover a wide range of diameters from 45mm to 270mm. This design allows the entire hole to be drilled at one time without the need for multiple reamings, and the cutting speed is greatly improved. Moreover, due to the reasonable groove shape of the blade, the vibration generated on the machine tool is very small, and the influence on the machine tool is small. When using high-speed steel drill bits, they had an accident of machine tool overload damage, and the cutting became very smooth after using the HTS drill bit.
The centering of large-sized indexable drill bits has always been a problem. Since the inserts of the indexable drill bit are distributed over different diameter segments to complete the entire cutting task, the cutting force is always difficult to achieve equilibrium. Therefore, the drill bit will produce some offset under the action of this combined force of cutting. The greater the diameter of the drill bit, the more pronounced the tendency of this offset. Harbin's original process plan requires multiple reaming, which also includes the role of correcting the offset of the previous step. The centering drill in the middle of the HTS drill bit is placed to contain this offset. Therefore, when using HTS drilling, Harbin does not need to ream several times, but can complete the entire machining task in one drilling.
The drive ring is also an important part of the HTS drill bit. It will ensure that both the drilling head and the machine tool will not be damaged by the shear fracture of the male key during the drilling torque overload.
The HTS bit must be used with the cutting fluid, where the cutting fluid plays a major role in chip removal. Drilling is a closed environment where all chips must be removed from the gap between the drill pipe and the hole. Due to the high processing efficiency, the amount of chips generated per minute is large, and the high drilling torque makes the diameter of the drill pipe too small, which makes the chip removal efficiency very important. In many cases, the efficiency of drilling is limited by the efficiency of chip removal and it is difficult to perform better. The cutting fluid of the HTS drill bit is fed from the center of the tool to the drilling head, which in turn flushes the chips from the gap between the drill pipe and the hole. Therefore, the greater the pressure and flow rate of the cutting fluid, the better the effect will be. Through the transformation of the machine tool, Haqi realized the conversion from external cooling to internal cooling, which increased the cooling pressure, thus preparing the necessary conditions for the rational use of the HTS drill bit. This series of designs provides a revolutionary solution for large diameter deep hole machining. Taking Haqi as an example, using this drill bit, its multiple steps are combined into one, and the cutting speed is increased by about 8 times. The original hole machining requires 6 tools and 6.7 man-hours. Now only one tool and only one tool is needed. 0.5 working hours, reducing processing time by 93%.
Haqi is very satisfied with this result. They have extended this kind of drill bit and some of their experience from the three-point factory to other branch factories. Nowadays, the steam turbines of Haqi are basically processed with such drill bits, which is very efficient. In Luo Yang’s words, the most direct feeling of front-line operators is “savingâ€.
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