Here are some examples:

* Bale dryerPulp mill or plate for journalists
* Plywood Press
* Feed compactor

Picture1. Clamping Function

* Filter-press residue
Press * Aluminum extrusion profile
* Press Box
* Trash compactor

Decompression

At the end of the cycle the press ram material pressed, the fluid in the RAM is still under pressure. Properly control the speed of decompression than pull the ram is a serious problem that is common to most hydraulic presses. If you’ve ever heard, and believed that the hydraulic oil is not compressible, you must open your mind to some new learning. It is true that the hydraulic oil is not very compressible in comparison with gas such as air (used in plant air compressors), but this is not the end of history.

Picture2. controlling the rate of decompression

Without compression, so the available 400 Volume girl is filled with 400 gallons of hydraulic fluid.

Most heating oil hydraulic compression of about half of one percent per 1000 PSI hydraulic pressure. This means that at 1000 PSI, you can customize 502.5 gallons to 500 gallons ram. 5000 PSI, you can customize 512.5 gallons to 500 gallons of the same ram.
prefill3

The pressure, 512.5 gal were crammed into an area of 500 gal.

Typical work as an industrial printing press extruding aluminum and packaging pulp has a very large cylinder (or RAM) can have several gallons (10 liters) or more of the liquid completely compressed to the maximum pressure when fully deployed. This is a huge amount of potential energy.

Trap and pressure (5000 psi) The volume of 512.5 gallons of liquid in the RAM 500 gallons will print very quickly when the valve port opens to expose liquid to atmospheric pressure.

Under compression have been crammed into the 500 gal space.

Compress hydraulic fluids have been carried out gradually and controlled as the ram was moved against the load (feature extraction). The output of this compressed fluid must be carefully controlled. Decompression is usually treated by opening the valve a very small hole. Once atmospheric pressure has fallen to a level, the valve is opened for the cycle to withdraw quickly and efficiently.
prefill4

Decompression is begun with the opening doll relief, which allows controlled release of hydraulic fluid booster.

If the fluid is released at a pace not controlled as it is through the large port valve, which was immediately transferred to the highest position, the liquid moves at very high speeds. This outburst of energy cons wall tubes, which are essentially sub-during this period may cause pressure buildup in May of the same fracture line. Hose back in May diametrically boule sudden decompression of ram, and thus may contract length and separate installation or detachment of the wall surrounding the tank online.
hosedamage

Small diameter of the cylinder press, as used in trash compactors, food May appears decompression control. Those bottles with smaller volumes and lower pressures may be only a small amount of compressed fluid in the end of the race. Hydraulic components generally inexpensive to include only bang-bang style directional valve that releases fluid from the totally blind end port at the end of the cylinder stroke. The effects of uncontrolled decompression, it is still often heard and felt the shock wave is amplified by a metal cover the whole machine. Even these low volume shocks can have a devastating effect over time.

In the next issue of newsletter to learn, we will examine some specific decompression valve to control the vertical and horizontal presses.

Why do hydraulic systems overheat?

Heating of hydraulic fluid in operation is due to inefficiency. The inefficiency of the loss of input power, which is converted into heat. A hydraulic system load thermal energy is equal to the sum of all power lost (PL) by inefficiency and can be expressed as follows:

PLtotal = PLpump + PLvalves + PLplumbing + PLactuators

If the total amount of heat lost power is greater than the heat, the hydraulic system to overheat more. Installed cooling capacity ranges usually between 25 and 40 per cent of electricity consumption, according to the nature of hydraulics.

Temperature of hydraulic fluid
What temperature is too hot? Hydraulic fluid temperatures above 180 ° C (82 ° C) damage to sealants and accelerate oil degradation. During operation of the hydraulic system at temperatures above 180 ° C should be avoided, fluid temperature too high when viscosity is less than the optimum value for the hydraulic system components. This can occur even below 180 ° C as the viscosity of the liquid class.

Maintain stable temperature of fluid
To achieve a stable temperature environment, the ability of a hydraulic system to dissipate heat, must exceed the heat load. For example, a system needs input power of 100 kilowatts continuous and can disperse an efficiency of 80 percent to a heat load of 20 kilowatts. Assuming that the system is designed cooling capacity of 25 kilowatts, all growing, underlining the heat above 25 kilowatts or reduced cooling capacity below 25 kW, the system will lead to overheating.

Consider an example. I was recently asked to investigate and solve an overheating problem in a mobile application. The hydraulic system consists of a motor unit diesel-hydraulic, which is currently used to power a pipe cutting saw. The saw was designed for the under-utilization of the sea and was connected to the hydraulic unit on the surface of a 710-foot cord. The conditions for the operation of the saw were 24 GPM at 3000 PSI.

The hydropower plant has a continuous power of 37 kW and was fitted with a heat exchanger air furnaces. The interchange has been dispersed to 10 kilowatts of heat at room temperature or 27 percent of the available input power (10/37 x 100 = 27) Can. The performance of all components of the cooling system were monitored and their activity within the design.

In this passage, it was clear that the overheating problem was caused by the heat load is excessive. Concerned about the length of the umbilical cord, so I thought the pressure drop. The theoretical pressure drop over 710 feet of pipe ¾ inch pressure is 800 psi at 24 L / min. The pressure drop over the same length of 1-inch return pipe is 200 PSI. The theoretical heat load produced by the pressure drop through the umbilical cord is 1000 PSI (800 + 200 = 1000) was 10.35 kilowatts. This meant that heat stress is the navel of 0.35 kilowatts more than the capacity of heat dissipation of the heat exchanger of the hydraulic system. That’s when they load with the normal heat system (inefficiency caused) in connection with the hydraulic system to overheat.

Beat the Heat

Besides improving chip control and tool life, directing a jet with accuracy at high speed cooling may increase the overall productivity. One of the potential beneficiaries of this approach to liquid cooling is the multitasking turning center. Most of these machines offer the supply of liquid cooling option with a pressure between 70 and 100 bar. In fact, Sandvik Coromant has developed accessories for high pressure coolant specifically for use with such machines, the amount of pressure.

For multitasking machines in particular, inefficient chip removal hinder the ability to make changes effective tools. Sandvik CoroTurn HP system reacts to this riddle. In this system, each tool carrier fitted with two or three nozzles replaceable stainless steel from which coolant is circulated at high pressure. Sandvik said spray heads are mounted near the edge of the temperature in the heat-affected zone (HAZ) below. They are correctly positioned and oriented at an angle, depending on the type of tools and application.

Getting the positioning right is just one of the keys to the effectiveness of this cooling technology delivery. The system pushes the chip and provides localized cooling of the insert point without thermal shock. It does this by producing a precise laminar flow – that is to flow with the energy flows is based on work instead of drawn by turbulence.