Quels sont les principes et les principales utilisations des ventouses à vide ?

Quels sont les principes et les principales utilisations des ventouses à vide ?

Vacuum suction cups are generally used as a force point for manual or automatic transport applications. They can protect and help move a wide range of equipment - from bottles and bags to bricks and boards, as well as metal sheets, pipes, and windows. In essence, they are the interface between the vacuum system and the workpiece.  

         Typical vacuum handling systems are the backbone of many industries, including packaging, food, beverages, woodworking, metal cutting, vehicles, semiconductors and electronics. Pneumatic vacuum suction cups have many advantages in such applications, including that they are relatively simple, compact, lightweight, inexpensive and require little maintenance. They can hold parts tightly in fast-moving applications and can gently handle fragile parts.

Technically speaking, suction cups do not automatically absorb and hold the surface of the product. Instead, when the suction cup touches the surface of the workpiece, it activates a vacuum generator (such as a vacuum atomizing nozzle, fan or pump) and extracts air from the internal structure of the suction cup and creates a vacuum. Assuming the standard air pressure inside the structure is lower than the standard air pressure outside the suction cup, the atmospheric pressure presses the workpiece against the suction cup. The greater the difference between the ambient pressure and the vacuum pressure inside the vacuum suction cup, or the larger the effective area of ​​the suction cup acting on the workpiece, the greater the holding force that presses the suction cup against the workpiece.

Ideally, the suction cup should fit a smooth, non-porous surface. When a vacuum is created, the edges of the suction cup and the air are sealed, and the air inside the structure is quickly discharged, thereby firmly grasping the workpiece. However, the non-ideal condition is many times the normal condition because the material is often olefin-decomposed, rough, or uneven. In this case, the suction cup cannot be sealed, and the external air continues to enter the system, which is called a leaky system. Designers must compensate for the leaky system by using a high-flow vacuum generator or using a smaller suction cup to reduce the possibility of leakage.

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Vacuum cups range from simple ring cups to cups designed for applications such as handling sugar cubes, greasy metal sheets, or porous wood and cardboard. They come in two general shapes, flat and bellows. 

Flat cups are suitable for handling workpieces with flat or slightly deformed surfaces, such as metal and glass, plastic, and wood. Flat cups have a small internal volume, so they can be evacuated quickly and can also be moved quickly in a short time. With proper design, they have good reliability to handle high shear stresses and can also withstand the forces and speeds from fast automatic transport movements.

         Bellows cups, on the other hand, have one or more oscillating rotations. This allows them to compensate for different workpiece heights and handle parts with uneven surfaces. The bellows also cause a lifting motion when squeezed, which helps to gently grasp fragile parts such as electronic components or even chocolates.

Bellows versions are typically used to handle curved components such as body panels, pipes and tubes, injection molded plastic parts, and non-rigid packaged or shrink-wrapped goods.