Hydraulic Piston Rock Splitting-Intros

        

  Hydraulic Rock Splitting

---   A New Method for Breaking Rock without Vibration. —

How tool works

A piston rock splitter machine is composed of a power pack and one or more number of splitting cylinders connected with hoses.  Each power pack is driven by electric motor supplied by  380(400)VAC 3 phase or 220(240)VAC single phase power source. Splitting cylinders are  connected to the powerpack through  hoses of low pressured and high pressured .Splitting cylinders are  sized to fit the pre-drilled holes of 90mm diameter or larger ( 95,100,105 mm diameter holes)



                      

The splitting cylinders are inserted into the pre-drilled holes. Then the pistons expand as the hydraulic pressure force is activated. When the expanded pistons crack the rock ,the rock is fractured  to be crushed.

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 Pic-5

 pic-6

 As we see on above pic 1~6, pistons are rising or falling by hydraulic pressures. When high pressure is activated, the pistons rise while low pressure is activated, pistons fall down. The cylinders in the drilled holes  are smaller than the drilled holes by 10~15mm  in diameter. When the holes are drilled  90mm diameter, the piston cylinders have 80mm diameters. Usual stroke of each piston has 25~35mm depending on the cylinder rod diameter.

Drilling is done by a separate rock drill . Crushing  ( or mucking) the rock is done by a breaker or  an excavator.

 Then crushed rocks are removed from the site.

  The holes are made vertically  or horizontally with some angles or straight. Usually horizontal drilling is made for large volume work. Vertical drilling is made in an inevitable case  such as shaft digging, trench work or quarrying sites.

Hydraulic Power Pack

Hrd-tech has been offering  a  very sturdy and reliable power pack among  its kind. The hydraulic power pack is driven by electricity of AC power ( either 380V3phase or 220V single phase,50/60HZ). A power pack supplies the hydraulics to the pistons of cylinders. This power pack must be a proven one. Its failure means non-operation of the machine.  The power pack should  be from the renowned supplier, because it is not like the ordinary power pack used for lifting jakki .

Hrd-tech.com has been manufacturing custom made power packs since late 1990’s. The power pack has been improved and improved  for  its reliability.  It is producing hydraulic power upto 2,500kgf/cm2. But it s  use  is l recommended to limit  of  1,200kgf/cm2  pressure for the safety sake.. AC mains power supply required  is  either 220~240V AC or 380 VAC  3phase. with frequency of 50/60HZ.

The power pack is accommodated inside the case. A power cord is connected to the power pack socket. When the green push button is  pushed , the electricity is on. Then the motor begins to run. As the motor runs, hydraulics is loaded. When the lever is directed to left, the high pressure is loaded. When the  lever is turned to right, low pressure is loaded. The medium position of the lever means the hydraulics is NOT  loaded. Hydraulic oil is returned to the tank without producing any pressure. Each  cylinder  in the hole produces expanding pressure of  150MT or more. When multiple cylinders are activated, very high pressing power is produced  . Each cycling of high to low pressing fluid takes time of 2~3 monutes. It is a safe machine.  It needs very little maintenance  of only with  regular cleaning outside.  Oil and filters are recommended to replace  every 6 months.

     

               (  Hydraulic pressure cracks the holes of the rock,)

Splitting Cylinders with Pistons--- Splitters

In the early stage of rock demolition, wedge type splitting tools were used. As a German company DARDA named it as Darda, it has been known as Darda splitter. Darda has been very effective for concrete works. Some people used Darda for rock demolition but it took quite a long time   because the spacing for rock hole was so near, lots of small holes had to be made.

Piston Cylinders began to be  used  in late 1990 mostly in Korea.  Korean government restricted to use any explosives for rock removal in residential area or building site.
 Usually the holes are drilled  with spacing of between 30cm to 60cm . In special hard rock the space is made more closely like 30cm .  Soft rocks need  more distant like 60cm spacing between holes. In the beginning, holes were made  in 95mm or 105mm . The  cylinders are made in 85mm or 95mm diameter steel rods.  The length of the steel rod has to be limited in its length or weight. THose cylinders were mostly handled by human hands. The weight was set between 30~40 kgs.  
( see below size table).

Division			unit	Manual   type						Mechanical Type
				SR80-10	SR85-10	SR85-11	SR95-06	SR150-2	SR185-1	SR95-10	SR150-08
Cylinder  Diameter			mm	80	85	85	95	150	185	95	150
Length of Cylinder Excluding. handle			mm	650	745	810	525	300	195	705	1000
Weight of Cylinder Including. handle			kg	27	30.8	32.5	29	36	35	39.3	125
Number of Pistons			#	10	10	11	6	2	1	10	8
Diameter of Pistons		D1	mm	38	40	40	45	58	90	45	58
Force	piston		ton	18.2	20.8	20.8	28.5	58.8	114	28.5	58.8
	cylinder		ton	182	208	229	171	117.6	114	285	470
Required Hole diameter			mm	90	95	95	105	165	200	105	165
Applying force			Kgf/cm2	1,200	1,200	1,200	1,200	1,200	1,200	1,200	1,200

Splitting cylinders are made with special steel. The steel needs special machining unlike normal machine. The structure must  stand with  the ultra hard impact during its repeated stressing activity.  It needs special heat treatment  to get temper and tensile flexibility.It should be light and sturdy enough for mannuvoering and protecting its function under high pressure.

Manual type is used with workers’ hands. Manual type weighs around 30kgs including its handle.Mechanical type is assisted by a winch or an excavator with some grippers.

Most popular cylinders are SR85-10 or SR85-10 for medium hard rock splitting. They are  rather light but producing very heavy  cracking power. SR95-06 or SR95-07( not listed) is used for  very hard rock splitting. Tunnel job requires SR95 types because of hard rock . From above table, you can see that SR185-1 produces the strongest force among all other sizes. Though the total cylinder force is not big,SR185 has the most powerful cracking force. Mechanical type is used by limited contractors who need more productive constant work. There is no limit in weight or length.   Sizes are built by customer specifications.

Pre-requisite: Rock drilling work.
 Every hydraulic rock splitting, whether it is wedge type or piston type, preparation of rock hole is required. From our experience, rock drilling takes 2~3 times of splitting time. So every rock demolition specialist must study the rock drill job carefully.
here follows several hints for a new entrepreneur.

Drilling Holes for Splitting

Rock drilling has been done with many rock drills. Some of the following methods have been used for hydraulic piston rock splitting.

Crawler rock drill

A crawler rock drill has been used for drilling holes in the rock. It is speedy in deep drilling upto 3 meter deep. The rod is extendable. Drills are built for certain range of drill bit sizes. The drill bit of 90~105mm is to be used for the manual cylinders.

Core drill mounted on excavator.

Very hard rocks are drilled with core drills. Usually large size holes of over 120mm are made by core drills.

Following photo shows core drilling work. The core drill is mounted on an excavator. The cylinder diameter is smaller than the drill size by 15mm .In case of 200mm drill hole, 185mm cylinder is used. For the 165mm diameter holes, 150mm cylinder is used. As the drilling takes lots of time, one or two cylinder is enough for splitting job  Drilling pace decides the rock splitting. Drilling pace is determined by several factors: 1. Spacing between holes:   2. Depth of the holes: 3. Splitter's expanding power. 4. Rock's characteristics. For a guide purpose, we recommend to set a spacing of 50cm with manual splitter. For the mechanical splitter, 60cm spacing is recommended.  Then based on your experience of some splittings, you can adjust the spacing  wider or narrower.