Introduction to HYG series Rock Drilling Machine from Hong Yuan Hydraulic Machinery Co. Ltd

? This article introduces Hong Yuan HYG series hydraulic rock drill, analyzes the application advantages of HYG rock drill, compares it with Epiroc Cop1838, and evaluates the prospect of double-sided oil-return technical method.

?1.???Overview of HYG hydraulic rock drill

? Hong Yuan Hydraulic released HYKD series hydraulic rock drill for iron and steel industry in 2000. After years of technical and experience accumulation, HYG series hydraulic rock drill for mining industry was released in 2010 and was well-recognized by the market since then. The new technology adopted by the rock drill improves the economic benefit of the drill pipe and prolongs the service time of the drill pipe. HYG series rock drill is mainly used in mining, tunneling and construction industry. The maximum impact power is 24Kw. The drilling hole diameter range is 33 ~ 102mm, and the best hole diameter is 45mm. It is the most commonly used hole diameter in Chinese market.

▲FIG 1. HYG550 hydraulic rock drill

?２. Advantages of HYG rock drill

2.1 Drilling efficiency and cost advantage

? At the mine of AMD, the largest iron ore producer in China, workers successfully upgraded the 1838 rock drill to HYG550. The upgraded rock drill brings customers better production efficiency and lower cost. Due to the excellent performance of HYG series rock drills, the customer immediately added 2 equipment orders, and plans to gradually upgrade all of the 1838 rock drills in the mine in the future.

HYG 550 rock drill increases the max. maintenance interval to 800-1000 impact hours, and greatly reduces the consumption of spare parts, especially in terms of total cost and performance. Compared with 1838 rock drill, the advantages of HYG rock drill are shown in Table 1.

? Table 1 comparative advantages of HYG550 and 1838 rock drills

2.2 Comparison of working and performance HYG550 and 1838 rock drills

Compared with 1838 series rock drill, under the same impact flow and slightly lower impact pressure, HYG550 rock drill provides higher impact frequency and higher impact power, and the energy efficiency is 13.5% higher than 1838 rock drill. HYG550 rock drill, through reducing single impact energy, produces increased impact frequency and higher impact power. HYG550 improves the drilling speed and service life of the drill pipes.

?If the rock is particularly hard, or the hole diameter is large and the hole is deep, such as the application of flint, medium deep hole, extension drilling, the impact energy needs to be greater than 250J. Under these situations, the 1838 rock drill may be better than HYG550 because of its large single impact energy. However, at present, the impact pressure of 18-series rock drills is mostly less than the maximum impact pressure. Therefore, the application of reducing single impact energy and increasing impact frequency will give HYG550 more advantageous in most applications.

Table 2 Comparison of technical parameters between HYG550 and 1838 rock drill

2.3 Seamless upgrade

? All drilling jumbos that use Epiroc Cop1838 rock drill and match BMH series propulsion beam can be upgraded to HYG550 rock drill without replacing the propulsion beam.

3.??Structural characteristics of HYG rock drill

?3.1 Reducing the number of shell-parts

1838 rock drill has 6 shell－parts in total, and HYG series has only 3 shell-parts. See Figure 3. The gearbox cover is removed, and the intermediate and gearbox are integrated into one shell, reducing the risk of deflection.

? ▲ Fig.3 Shell-parts of HYG rock drill

3.2 Bushing advantages

? The sliding contact between the impact piston and the valve is of bushing structure, as shown in Figure 4. The cylinder block has no contact with moving parts, which greatly prolongs the service life of the cylinder block. In fact, this is also the structure long adopted by Sandvik rock drill.

▲ Figure 4 HYG rock drill bushing structure

3.3 Four shorter bolts

Comparing with the long-bolt of 1838 rock drill, four shorter double headed bolts are used for the connection between the shells. The purpose is to avoid the problem of tensile elongation of the long bolts, and therefore to reduce the risk of shell deflection.

?3.4 Front end structure

The drill guide sleeve adopts the front-rear double guide sleeve structure similar to Sandvik, which plays a better role in supporting and guiding the drill and prolongs the service life of the guide sleeve, water seal and drill rod. The front end structure can provide better protection on the water seal, four edge sleeve and rotating bushing.

3.5 Return oil accumulator

1838 series rock drill oil return accumulator is installed on the oil return pipeline. The structure of HYG550 rock drill oil return accumulator is the same as that of the high-pressure accumulator, which greatly increases the reliability and reduces one maintenance point.

?4. Structural characteristics of impact system

?4.1 Technical route of single side oil return

? The double-sided oil return of impact piston has always been the main feature and exclusive feature of Epiroc rock drill. The impact system of HYG550 rock drill changes the technical route of double-sided oil return system, and adopts the technical route of stable pressure in the front chamber and variable pressure in the rear chamber as Sandvik rock drill, as shown in Figure 5. This change greatly reduces the difficulty of design and manufacturing of rock drill, and avoids many problems caused by the asynchronous commutation of two cavities.

A-?valve transformer chamber

B-??valve constant high pressure chamber

C-??rear chamber (high and low pressure)

D-?signal feedback chamber

E-??front chamber (constant high pressure)

? ▲ Fig. 5 Schematic diagram of impact hydraulic system of HYG rock drill

See Table 3 for the technical parameters of HYG550 rock drill

?

4.2 Oil circuit for signal

The front chamber E of the piston is of constant high pressure. The middle chamber D of the piston is of constant low pressure. The low-pressure oil is obtained from the middle chamber D of the piston and reaches the chamber A of the distribution valve through the internal hole. See Fig. 5. This structure is probably the simplest and best structure.

4.3 valve drive

???? ?The distribution valve is still a core valve structure, but the driving method is changed to constant high pressure in chamber B and variable pressure in chamber A, as shown in Figure 5. Chamber B acts on the inner hole of the valve core. The design is very ingenious. It can reduce the processing cost of the valve and shell, lower the weight of the valve body and improve the response speed. However, the guidance function of the valve core is somehow lowered. Therefore, other structures are added to the valve core to make up for it.

4.4 Valve structure

????? The oil distribution structure of the distribution valve does not adopt the mainstream three-way valve design, but adopts the design of the original double-sided oil return structure. In addition to the reasons for technical inheritance, this design can ensure that the overflow area is doubled when the valve core diameter and stroke are small, as shown in Figure 5.

4.5 Piston flange

???? ?When the rock drill works, empty strike is a common phenomenon and inevitable. HYG550 rock drill has added anti-impact brake flange on the impact piston structure. The brake flange makes the rock drill more resistant to empty strike and prolongs the service life of the rock drill. Sandvik rock drills have long adopted the brake flange structure.

?5. Structural features of buffer system

?5.1 Two-stage buffer

?????HYG550 uses the external oil supply two-stage buffer. The buffer accumulator and buffer check valve are cancelled. Therefore, the number of parts is reduced, and the structural complexity and processing and manufacturing cost are greatly reduced.

?5.2 Position of drill rod stop-sleeve

?????The drill stop-sleeve is placed in the buffer piston and the rear guide sleeve. It not only is easy to process and manufacture, but also avoids the damage of the stop sleeve caused by the deformation of the rear guide sleeve brass sleeve.

6 Sealing and lubrication

?6.1 Seals

????? All hydraulic static seals adopt polyurethane square rings.

?6.2 Buffer seals

?????The buffer seal adopts the seal design and material combination specially customized by Hong Yuan engineers. The seal can bear the rebound force of drilling tools and better bear the rotation speed of 300 ~ 400 rpm.

?6.3 Seals manufacturer

?????The inner seals of HYG550 rock drill are all products of German Merkel Freudenberg and Trelleborg products.

?6.4 Face seals for the shell

?????Sealing rings are added to the end face connecting parts of all shells (including accumulator) of HYG550 rock drill, which reduces end face cavitation and prolongs the service life of underground rock drill shell. After the sealing ring is added to the connecting end face, the lubricating oil consumption of HYG550 rock drill is also greatly reduced compared with 1838 rock drill.

6.5 Gear lubrication

????? The gearbox is lubricated by hydraulic oil, and there is no need to grease regularly.

?7. pipeline and pipe joint layout

????? The oil inlet and return port of the rotary motor is located on the installation surface, and finally leads to the bottom-end of the rock drill through the hole between the gearbox and the shell. In this way, all hydraulic oil pipe and lubricating oil pipe interfaces are arranged at the end of the rock drill, and there are left and right symmetrical interfaces. When the rock drill is installed on the left and right booms of the twin-boom drilling jumbo, the pipeline can be installed symmetrically, making the installation of the rock drill pipeline more convenient and tidy. Each oil pipe has an independent slot on the drum, so the pipeline is not easy to wear.

▲ Figure 6 oil pipe drainage structure of MD20 rock drill

9. Conclusions

(1) HYG550 rock drill not only adopts the design ideas of COP 1838 series and Sandvik drilling machines, but also has its own advantages.

(2) There is no optimal technology for rock drill, only relatively optimal technical solutions. As long as it is applicable and meets the current market demand, it is a good technology. HYG550 rock drill products give us great surprise and shock.

HYG series has been on the market for twelve years, and HYG550 is much better than its before under development. In fact, Chinese rock drill have made great progress over a few years ago. At this stage, although the gap between the performance and reliability of domestic hydraulic rock drill and the international brand is smaller and smaller, Chinese engineers still need to make more efforts.