Merits of HRD Piston Rock Splitters

Why a Piston Splitter ?

A wedge splitter has been around for many decades. Why do we need another type of rock splitter ?  Any merit with the piston rock splitter over the wedge splitter?

1. A piston rock splitter performs much more rock splitting than a darda.

 A piston rock splitter  has been developed and improved  mainly in Korea since early 1990. Until this piston type rock splitter was available, wedge type splitter called,Darda splitter had been used for removing concrete structures and rocks. As Korean government enforced law of vibration free rock removal in early 1990's to avoid environmental conflicts between the construction company and residents, many construction companies had to find more efficient methods of rock removal.

Non-vibration or vibration free rock removal was absolutely demanded by many construction companies.  However Darda splitters could not meet too many demands.
Some people  tried other rock removal methods such as PCF( penetrating cone fracture) or NONEX or CARDOX.  Some people tried rubber tube expander in pre-drilled holes.
In some places, a larger size wedge splitter was tried . But the resulting performance was as low as disappointed level.

Spatial distance between holes is the decisive factor in performance.

A mechanical rock splitting needs predrilled holes before splitting. The depth and number of hole decides the  total performance of rock drilling jobs. The number of holes is decided by the splitters' breaking force.
In other words, if the splitter's breaking force is weak, the hole distance must be short enough so that the holes should broken.

When a wdge type splitter is used, this hole distance is 20~35cm  while the piston rock splitter has hole distance of 40~50cm. The number of hole is 3~5 time difference.
The depth of hole is also short with wedge type. As a result, the performance of wedge splitter is very low.

   

Comparison of Manual wedge splitter vs piston splitter

Various sizes of piston splitter were introduced for special applications.

Piston rock splitters have been made mainly for manual operation . That does not mean that mechanized sizes are not possible.  Mechanizing was tried various ways. The splitter had to be maneuverable freely. Mechanized splitters were not so easy in operation.Only a  small number of people are using excavator mounted splitters..  Most of the handling has been manual one. So the weight , the length or thickness of the cylinders are limited within manual range.
For an ordinary Korean worker, recommended weight is less than 35kg per each splitter.
HRD-tech builds ordinary size as under 30kgs in weight . The heavier one is hard for any ordinary worker to handle.

Longer cylinder performs more splitting. However the weight, hole diameter limits the size. Design or building must reflect the sturdy durability under harsh pressed condition.
            
Following photo shows one piston cylinder weighing 38kg each.  It is not easy or comfortable to move one piston cylinder around the rock sites..

Cylinders of 185mm diameter

           Following photo shows the popular cylinder size of 95mm diameter with  9 pistons. Each cylinder weighs 36kg.  This size is favored by contractors who wants to remove hard rocks in tunnel work.  It is rather heavy  for ordinary person to handle manually.  Only experienced  strong  workers can handle them .

Cylinder of 95mm diameter with 9 pistons

Model 9509 ( 95mm diameter 9 pistons) , 9507( 95mm diameter 7 pistons) are built with the same size piston rods and cylinder diameters.  Only the number of piston and the length of cylinder differs. The drilled holes for 95mm dismater splitter is 105mm.

Following photo shows the more popular cylinder size of 85mm diameter with 11 pistons ( Model 8511) or 10 pistons( model 8510). 

6  x  8511 splitters connected to a Power pack in a Case

Each piston of 85mm diameter cylinder weighs less than 30kgs. This weight is good for a strong worker. The drill hole size for the 85mm splitter is 95mm.

HRD-tech.com produces 80mm diameter cylinders  too..  Each piston produces expanding stress of  19.9tons(19,900kp/cm2).  Favored sizes are 10pistons ( Model  8010 ). A splitter has expanding forces of 199tons against the wall inside the rock hole of 89~90mm diameter.

Another size manual splitter is 90mm diameter cylinder. Usually it has 8 pistons in a cylinder. 90mm diameter produces splitting force of  24.5tons each.

Understanding Splitting Principles of Splitters.

A wedge splitter makes fracture of holes by use of expanding force of the feathers/shims. A piston splitter makes fracture of holes by use of expanding force of the pistons. By appearance both tools seem to work in same manner.  Each mechanical force pushes the wall of rock in its pre-drilled holes.

If you look at the fracturing manner carefully, you will be able to find that splitting direction is not straight but perpendicular.to the hole direction. See the below photos.

A wedge splitter's force is working perpendicular to hole's direction. 

 When you see the direction of piston splitter's force, you will see that piston's expanding direction is also perpendicular to the hole direction. See below diagram.

A wedge or a piston forces the wall perpendicular to the hole's direction.

Why Piston Splitters Break More Rocks with  Less Expanding Force?

As you see on pictures 3 & 4, a wedge splitter pushes the rock wall with the continuous feather's surface. On the contrary to this ,a piston splitter pushes the rock wall with tops of pistons.  Both tools push the rock wall. But the concinuity and discontinuity makes a big difference in producing the expanding forces.

A continuous force works on the rock wall as a shearing stress or a compressive strength.   A discontinuous piston particularly the bottom piston works on the rock wall as a " tensional force".( See pic.4 )

The bottom piston splits the rock with tensional force as well as compressional force.
Actual pistons' expanding forces compress f.e . with 90% of compression and 10% tensioning!

Darda also supplies a mechanized wedge splitter of 1500tons and 1800tons.  Their recommended spacing is not known. But we  assume that their spacing must be shorter than Yamamoto's device.

With the piston rock splitter, recommended spacing for the manual piston spliter is 40~60cm. For the ultra hard granite rock ,35~40cm  spacing is  experienced . With machine mounted piston splitter can break the same hard rock with far distance of 1000~1200mm .

Depth of  hole is optional. The splitting depth varies depending on splitter's kind and size. With the wedge splitter only shallow holes are broken leaving the bottom or deep part  not broken always.  Piston splitters break the holes almost to  the  deep bottom . A wedge splitter cannot break to the bottom of the hole. It must leave some vacant bottom which is 30~40% of total depth.

In Korea, wedge splitters are used limitedly in very narrow space only.

For the rock demolition, piston splitters are used on any rock fracturing sites.

It is evident that different performance between the wedge splitters and piston splitters changes the demand for the kind of splitters.  We recommend our customers who are serious to remove the rocks either from tunnel work or ground preparation site to use piston splitters .
.
HRD Piston Rock Splitter

Hwacheon eng co ltd has been specialized in manufacturing piston rock splitters  a few dacades since 1990.

The most important quality is from the sturdy power pack.  it has been modified and modified to suit the rough construction environment.
HRD-tech splitters are not copiable by any compay in the world.  Many tried to copy them to fail. Its machining, heat treating  has special knowhow.

We are happy to hear from our customers their compliments. We started export to USA in 2007. This customer has informed us recently that they have been keeping  a couple of machines more than 10 years in leasing business. They could  sell  a few machines through this lease  experience.

Another customer in New York has been promoting our machines  in their  web site
togetherwith darda and piston splitters for different applications.

Now we have customers around the globe.  Russia, India, China, Chile ,Phillippines, Kenya, keeps our splitters.

Send your inquiry any time to my email: cs@hrd-tech.com