What is a Hydraulic Cushion

What is a Hydraulic Cushion

The hydraulic cushion counteracts the force of the main cylinder, slowing down its descent and thus allowing the metal sheet to be stretched to form the workpiece. It is particularly suitable for deep drawing processes, i.e., cold working on a flat sheet of metal, transforming it into a more or less complex concave shape.

The hydraulic cushion is placed under the press’s fixed table. It consists of the main cylinder, a fixed flange, a mobile table sliding along four self-lubricating guides, and a valve stem passing through the hole of the lower fixed table.

deep drawing press with die cushion

Working principle of hydraulic cushion of press

The hydraulic cushion is one of the key components of a press, and its working principle is mainly divided into two parts: the hydraulic working principle and the pad working principle.

Hydraulic working principle:

The hydraulic pad uses the characteristics of liquid transmission in a closed pipe to work, and its working process is as follows:
1. Hydraulic oil is stored in the hydraulic pad, and the hydraulic oil is transported to the cavity of the pad through the hydraulic pump
2. When the hydraulic pump supplies pressure to the pad’s cavity, the hydraulic oil begins to compress the gas in the pad.
3. The hydraulic oil generates high pressure on the surface of the pad through the action of compressed gas, thereby achieving the pressing of the workpiece.

Working principle of pad:

The pad is an important component of the hydraulic cushion, and its working principle is as follows:
1. The pad is composed of multiple layers of thin sheets. The upper and lower layers of the pad contact the hydraulic pump and the workpiece, respectively.
2. When the hydraulic pump gives pressure, the hydraulic oil begins to exert force on the pad, causing each layer of thin sheets to unfold gradually.
3. During the pad’s unfolding process, a closed space is formed between the upper and lower layers of thin sheets, thereby achieving uniform pressing of the workpiece.
4. When the hydraulic pump stops supplying pressure, the hydraulic oil in the gasket will flow back, and the sheet will gradually shrink and return to its initial state.

 hydraulic press drawings-1

In summary, the hydraulic pad of the press machine realizes uniform pressing of the workpiece through the interaction of hydraulic work and pad work. The hydraulic work uses the transmission characteristics of the liquid to compress the gas in the pad through hydraulic oil to generate high pressure. The pad work forms a closed space through the expansion and contraction of the sheet to achieve uniform pressing.

The main functions of the lower hydraulic cushion:

Buffering and reducing impact. The lower hydraulic cushion can buffer and reduce impact. By controlling the speed and pressure of the lower pad, the workpiece is subjected to a stable force when pressed down, and the deformation or damage of the workpiece due to impact is avoided.
• Increasing the pressure of the hydraulic press. The lower hydraulic cushion can increase the pressure of the punch press so that when the workpiece is punched, the pressure applied upward by the lower pad can be increased, thereby increasing the strength and hardness of the workpiece.
• Stabilizing the position of the workpiece. The lower hydraulic cushion can stabilize the position of the workpiece and prevent the workpiece from moving or deforming during punching, thereby ensuring the accuracy and quality of the punching.
• Adjusting the height of the hydraulic press. The lower hydraulic cushion can also be used to adjust the height of the punch press. The height of the lower pad can be adjusted as needed to keep the workpiece in the best position during the punching process.

hydraulic press drawings-2

In short, the lower hydraulic cushion is a very important hydraulic accessory. It can improve the hydraulic press‘s impact performance, stabilize the workpiece’s position, improve the quality of punching, protect the hydraulic system and equipment, and extend the equipment’s life.

Zhengxi is a professional hydraulic press factory in China and can provide high-quality hydraulic press machines with cushions. Contact us to know more!


Post time: Oct-29-2024