New Benchmarks in fluid technology

New Benchmarks in fluid technology
Slimline Hydrotek

Thursday, August 21, 2014

Using Scanwill oil to oil pressure intensifier instead of separate high pressure power packs / pump motors

It is observed in lot of applications especially in special purpose metal cutting machines that the main hydraulic system works at very low pressure mainly the indexing and machining slides. However in most of these systems the job is clamped with Clampets which are very compact cylinders. These are used mainly to accommodate them in a very small space available on the machine. Since these are compact cylinders, the piston area is also small.

Normally it is observed that the bore sizes available for these clampets is not more than 50 mm. To achieve a force of say 3T one needs this cylinder to operate at 200 bar !  Invariably there is separate clamping power pack or else there is a separate pump motor assembly may be with a radial piston or some other high pressure pump installed on the same low pressure power pack. So you have an additional electric motor, bell housing assembly, suction strainer, separate relief valve etc. To get rid of the hassles one should think of using an Oil to Oil pressure intensifier. The typically most of the valves used in the metal cutting SPMs are CETOP 3 ( NG 06 ) mounting.

There are oil to oil intensifiers available with CETOP 3 stackable mounting !  This is available in the ‘ A’ line of CETOP stack like depicted below. The main advantage is that all the valves used in the circuit work at low pressure which is the main pressure setting of the system relief valve hence less stressed valves and other pipe lines. The only line which works at high pressure is the A line coming out from the intensifier and going to the clamping cylinder .  There is no need to use high pressure series tube fittings before the intensifier since the complete power unit works at a low pressure and ONLY the  portion from intensifier to cylinder works at high pressure. This also results in the space as well as cost saving during the assembly.  Another big advantage is that these intensifiers are available in various ratios like, 1.4 , 2.0, 3.4, 5.0, 7.0, 9.0 . With these available ratios , the maximum pressure the designer can go up to is 500 bar !. Hence the designer has a freedom to choose the ratio based on the maximum available working pressure on the main power pack. These intensifiers have a very simple construction, work on the principal of area ratio and are easy to repair / replace.In addition to these stackable models, line mounted models are also available. The maximum pressure output is as high as 4000 Bar!

The new design of Scanwill intensifiers are also available to be used with rotary joints.
Some of the applications of these compact intensifiers are as follows:
  • High static pressure testing equipments
  • Fork Lift attachments for drum handlers etc.
  • Rock splitters
  • Rescue Tools
  • Chucking
  • Demolition Tools
  • Torquing Tools
  • Rail Road equipments
These intensifiers are manufactured by Scanwill Fluid Power ApS, Denmark www.scanwill.com  and are available in India through Slimline Hydrotek, Pune. www.slimlinehydrotek.com

Article Written By Mr. Prasanna Umarani 

To Know More Please Visit: http://slimlinehydrotek.com

Wednesday, June 18, 2014

Conversion of conventional hydraulic surface grinder

As everyone is aware , the surface grinder uses hydraulic system for reciprocation . Apparently it seems a very  simple system only with one double piston rod cylinder with reciprocating action and working at a very low pressure . However only the designers and the maintenance team know how complicated the system is ! Whenever there is break down it becomes really tough job for maintenance team since there are no standard valves used in the circuit except may be a relief valve. All other valves like the direction control valve, flow control valve, deceleration valve etc. are specially manufactured and fitted in a single  manifold block by the machine manufacturers . Unless the maintenance person has a thorough knowledge of hydraulics it becomes very difficult to even recognize the components and trace the circuit. Most of the flow control, DC valves are fine tuned by the manufacturer so as to avoid any vibrations or jerks during the reversal. Jerk free movement is very crucial to the operation of surface grinder.  Hence trouble shooting of this type a circuit becomes a tough task. It’s not only tough but it consumes too much of time. The spare valves are never readily available as these are specially made for the application by the machine manufacturer and the user has no choice but to contact the machine manufacturer.

Avoid this ! Go for a proportional valve system. The pump, motor and accessories remain the same. A standard NG06 or NG10 size simple open loop proportional valve works like a combination of direction control, flow control and deceleration / acceleration control valves. This becomes the most simplified system. A small change in control panel is needed which can generate a signal of +/- 10V. Reversal signal can be generated by a simple limit or proximity switch. This eliminates the need of complicated cams, dogs, throttle valves etc. All the parameters like maximum speed, acceleration / deceleration values can be controlled on a control panel with potentiometer and a small PLC . In addition, if one uses a low pressure variable volume vane pump then there can be a substantial reduction in the power consumed and heat generation.

Conclusion – conversion to proportional valve system 01. Reduces down time 02. Circuit can be understood easily 03. Ready availability of spares since all valves used are manufactured by standard hydraulic companies 04. Results in lower inventory carrying costs
Go for it !


Article Written By Mr. Prasanna Umarani 

To Know More Please Visit: http://slimlinehydrotek.com