What Is a Hydraulic Press Machine?
A hydraulic press machine is a device that uses hydraulic oil and a hydraulic pump to operate a mechanism to shape a material to be processed into a specified shape using a press die.
Press dies are installed on the upper and lower beds of the machine, and when the upper bed is lowered by hydraulic pressure with the material placed on the lower die, the material is clamped between the upper and lower dies to form the desired shape.
Uses of Hydraulic Press Machines
Hydraulic press machines are available in various sizes depending on the applied pressure. 1,000-ton class hydraulic press machines are often used in the automotive industry to process the exterior panels and chassis frames of passenger cars and truck buses. Presses are also used for die castings, forgings, power generation turbines made of CFRP, and other large products that require molding processing power and time.
For deep-drawing shapes such as sinks and stainless steel containers, mechanical presses using a link drive may cause drawing wrinkles and cracks, resulting in quality defects. On the other hand, hydraulic press machines can improve the quality of deep-drawing shapes because the processing speed can be adjusted.
Principle of Hydraulic Press Machines
Hydraulic pressure is a system that uses fluid to transfer energy and is based on Pascal’s principle. Hydraulic press machines use an electric motor to operate a hydraulic pump, which generates hydraulic pressure. That pressurized hydraulic fluid is then sent to the hydraulic cylinder, which moves the upper side of the bed up and down within a range set by the machine.
To achieve relatively high torque, engines, and electric equipment must be combined with an appropriate transmission. In contrast, hydraulic equipment does not require a transmission because the machine is controlled by changing the amount of hydraulic fluid supplied to the cylinder.
Other Information on Hydraulic Press Machines
1. Features of Hydraulic Press Machines
Comparison of Press Force
The cylinder is moved up and down by the hydraulic oil pressure discharged from the hydraulic pump and the flow control valve. Since a large output can be obtained with a small amount of power, the maximum press force of a mechanical press machine is 80,000 kN, while that of hydraulic press machines is 200,000 kN. Compared to the drive motor used in a mechanical press machine, the drive motor used in hydraulic press machines has about 10 times greater output per mass. Therefore, hydraulic machines have the advantage of being lighter and smaller.
Comparison of Machines
Hydraulic press machines have longer operating strokes than mechanical press machines. They can generate high compressive forces and adjust speed and are easy to handle because the relief valve, which is the mechanism of the hydraulic system, prevents overload. These machines also require more maintenance and processing time is slower.
Comparison During Production
Mechanical presses are used for mass production. Mechanical press machines do not require hydraulic oil or hydraulic pumps, are quiet and unaffected by temperatures, do not require the installation of a hydraulic unit, and have the advantage of high processing speeds. Especially in shearing, bending, drawing, and punching processes, presses are suitable for mass production because processing time is short.
2. Points to Note About Hydraulic Press Machines
Because hydraulic press machines generate extremely high pressure, accidents involving serious injury or death are common. Daily maintenance safety and health education are essential. Insufficient machine management due to hydraulic oil leaks, contamination, etc., can lead to malfunctions, and a machine that has stopped may suddenly start moving.
Operators and supervisors need to provide on-site workers with thorough safety and health education, such as by placing safety bars above and below the bed of the press at the end of each operation.