Choosing an electrohydraulic press

Choosing an electro-hydraulic press will not be so difficult if you carefully study all the nuances of this technique. You will also need to familiarize yourself with an overview of electrical models for 25 and 30, 50 and 75, 100 tons and 150 tons in order to understand what exactly is needed.

The electrohydraulic press is an electrically driven hydraulic squeezing mechanism. It should be noted right away that the electric drive has almost completely replaced air and steam systems. It turned out to be much more economical, and therefore even some of the local advantages of pneumatic and steam schemes have lost all significance. Now such systems have survived only in outdated equipment, and then in single copies. Therefore, the comparison will go between purely electric and electro-hydraulic devices (fully pneumatic ones can be taken out of the brackets).

Hydraulically based systems are particularly robust and reliable. With their help, it is possible to provide a multi-ton pressing force. Such equipment is often recommended for hydroforming. With a particularly slow motion, it is possible to give the accumulation of metal a sufficiently precise configuration. Other advantages are also noted:

• it is quite simple to adjust and control the force;
• it is easy to influence the speed of the output link;
• due to the transfer of kinematic fluid through pipes, including flexible pipes, it is possible to apply force even to remote or moving parts of the structure.

But this does not mean that hydraulics are woven from some advantages. Its characteristic weaknesses are:

• the need for a special fluid;
• the complexity of the hydraulic fluid control system;
• relatively low efficiency;
• high cost of parts and their maintenance;
• the likelihood of working oil seepage into the pressed area.

The movable crossbeams of hydraulic presses make so-called double strokes. They are divided (excluding technological breaks) into idle, working and reverse stages. On straight idling, initial preparation for action is performed. The work attachment approaches the workpiece. At this point, the working fluid is not supplied to the cylinders and no useful work is performed.

With a direct working movement, the workpiece is mechanically deformed. Just at this moment, she receives the required configuration. It is then that the device expends a large amount of mechanical force. Therefore, he needs a certain amount of energy. It is supplied by an electric motor connected to a hydraulic circuit.

Additionally, there are:

• working cylinders;
• fluid return cylinders;
• connecting pipelines;
• hydraulic fittings;
• filling tanks for low pressure liquids;
• accumulators;
• flywheels;
• multipliers.

The drives can be of group and individual design. In the first case, the total installed capacity is reduced. A pumping-accumulator station is installed in a separate room. The route for pipes connecting this station and the working part of the press is mainly calculated individually.

But it can also be used on conventional powerful systems, when the hydraulic drive cannot be installed on the press itself or near it. The manual hydraulic press is much less powerful, but the very essence of its work just takes such a technique out of the scope of the topic under discussion.

The table press will take a certain place on the workbench. The floor-standing one is set almost arbitrarily and can have more power, but it will cost significantly more. A network device is predictably more powerful and more stable than a battery device, and it also has a longer continuous operation time, but these advantages usually have to be paid for by the stationarity or low mobility of the system.

The most popular options are now electro-hydraulic presses:

• Oprema 40I;
• "Parity-PRO" (models "PG20", "PR10", "R342M2");
• test products of the "PI" series from "Metrotest";
• OMA 665;
• K 100 E Mega.

The most important indicator is the effort being developed. You don't need to be an engineer to understand that devices for 25, 30 and 100, 150 tons are completely different categories with different capabilities and areas of application. A ten-ton indicator is enough for an ordinary automotive or household appliance repair service. 40 or 50 tons will be enough for a large car service. And the equipment for 75 tons is suitable for straightening heat-treated parts and other engineering tasks.

However, there are a number of other subtleties. So, the distance from the stem to the working platform plays an important role. It is determined by the largest workpiece size. The presence of a pressure gauge is also significant. The more precisely the working pressure is regulated, the better. It is also worth paying attention to:

• price;
• functionality (so that there are all the necessary options and not a single one that is not required);
• ease of maintenance (it is ridiculous and ruinous if a master from the service is called to the household device every time for cleaning);
• availability of spare parts;
• design reviews.