Most of the factories in the manufacturing or recycling industry use a powerful hydraulic press for crushing, molding, and casting metal objects. The hydraulic presses will generate a large compressive force and apply it to a small area for creating the desired result. Compared with a mechanical press, hydraulic presses are compact in size and easy to operate. Full power stroke and built-in overload protection make hydraulic presses more flexible and safer. Full power stroke means the maximum pressing force can be generated anywhere in the stroke and this is one of the important benefits of the hydraulic press that offers the ability to control different job parameters. This blog describes the construction and working of hydraulic presses along with major hydraulic components used in the system.
Also Read: Uses of Hydraulic Press
What are the important hydraulic press components? Similar to other hydraulic systems, a hydraulic press consists of basic components like hydraulic cylinders, hydraulic pump, electric motor, control valves, reservoir, filter, hoses, pipes, and fittings. Proper installation of these hydraulic components will design an accurate and fully functioning hydraulic press. More details regarding these press components are noted below.
Hydraulic Cylinder: In every system, the most important component is a hydraulic cylinder and it will convert hydraulic energy to mechanical energy. The power of pressurized hydraulic fluid will push/pull the piston rod attached to the cylinder for applying the required compressive force on the workpiece. Each stroke will depend on the pressure of fluid entering and leaving the cylinder ports. Fixed mounting, dynamic mounting, and mounting to the piston rod are the different hydraulic cylinder mounting options available.
Hydraulic Pump: Hydraulic pump is the heart of every hydraulic system, it converts mechanical energy to hydraulic energy. A hydraulic press will normally use an external gear pump for this operation. This pump is ideal for medium pressure applications and it improves the volumetric efficiency. The external gear pump is cost-effective and simply constructed.
Electric Motor: The electric motor will drive the attached hydraulic pump by converting the electrical energy to mechanical energy. With this mechanical energy, the hydraulic pump will pressurize the fluid from the reservoir and transmit it to the hydraulic circuit. 3‐phase electric motors are suitable for hydraulic press applications due to its simple structure, high efficiency, reliable operation, less vibration, and more.
Control Valves: Control valves in the hydraulic system will direct and regulate the fluid flow through the circuit. Directional control valve, pressure control valves, and flow control valves are the different categories of valves commonly used. In hydraulic presses, every stroke of the ram depends on the fluid flow through the valves attached to it. Factors like fluid direction, pressure, and flow can be controlled with this valve.
Hydraulic Reservoir/Tank: The hydraulic tank in presses has different functions like storing the fluid, cooling the fluid, expanding of the fluid, and contaminant separation. The reservoir is constructed with a welded steel plate and its design can be varied considering the application requirements.
Filter: The quality of hydraulic oil has a key role in system performance. With different filters like return line filters, suction line filters, and pressurized line filters, it is possible to remove solid contaminants from the circulating oil. Also, the wear of hydraulic system components can also be minimized.
Hoses, Pipes, and Fittings: The hydraulic fluid will be transmitted to different parts of the system with connected hydraulic hoses and pipes. Fittings are used in the circuit to properly assemble the hoses/pipes with different system components.
How does a hydraulic press work? Similar to other hydraulic systems, the working of a hydraulic press is based on Pascal’s principle. Pascal’s law states that the external pressure applied to a confined incompressible fluid is distributed or transmitted evenly throughout the system in all directions. With a minimum applied force, it is possible to generate a larger output.
For a hydraulic press, it consists of two cylinders called a ram(larger cylinder) and a plunger(smaller cylinder). For hydraulic press working, a small force is applied to the plunger, and with force multiplication, the magnitude of this applied force will be increased and delivered at the ram. Depending on the working load, the hydraulic press can include multiple rams of small sizes and it can control the thrust forces.