How to choose the right vacuum pump for vacuum adsorption?

What vacuum pumps should be used for vacuum adsorption and suckers?

First, let’s take a look at the vacuum principle of the vacuum sucker. The vacuum principle adopted by the vacuum sucker is to “absorb” the workpiece by vacuum negative pressure to achieve the purpose of clamping the workpiece. As shown in FIG. 1, the vent is connected to the vacuum generator. When the vacuum generator is started, the vent is ventilated, and the air inside the sucker is pumped out, forming a vacuum with pressure P2. At this point, the air pressure inside the sucker is lower than the atmospheric pressure outside the sucker P1, namely P2 < P1, and the workpiece is sucked up under the action of external pressure. The higher the vacuum inside the sucker, the tighter the attachment between the sucker and the workpiece.

So how to achieve efficient vacuum adsorption? Let’s look again at what vacuum adsorption involves.

In order to achieve vacuum adsorption, the following four conditions are required: vacuum generating device, suction cup for vacuum adsorption, adsorbed object, connecting pipe and control equipment. Understanding these conditions, how to achieve high efficiency vacuum adsorption, is the mutual work of these conditions.

The first is the vacuum generating device, people’s consciousness, often is the higher the vacuum, the better the effect of adsorption. This is true, but let’s look at another data: experiments have shown that if the vacuum is increased from -0.6bar to -0.9bar, the adsorption force can be increased by 1.5 times, but the air suction time and energy consumption required are increased by 3 times! The creation of a high vacuum is not proportional to the high input energy. So, in the vacuum adsorption equipment, too much pursuit of high vacuum degree is often not practical, for the long-term operation of the equipment, more is not economic.

Next important is the vacuum chuck, its size and form, plays a decisive role in vacuum adsorption. The larger the area of the sucker, the stronger the adsorption force, which also depends on the surface of the object to be adsorbed. In general, in order to achieve the purpose of long-term energy saving operation, the design of the sucker is relatively large and the number is relatively large. In order to achieve high-efficiency adsorption, apart from selecting high-flow high-pressure fan as the vacuum generator, the suction cup is also designed to be smaller to reduce the extraction time of air. The vacuum buffer tank is sometimes installed by vacuum equipment manufacturers to improve this performance.

Next is the adsorbed object (hereinafter referred to as the workpiece), which mainly depends on the shape of the workpiece and allow the possible fixed way, comprehensive operation convenience, practicality to consider, there is no general principle. It should be noted here that the multi-point adsorption or large plane adsorption of the workpiece is often much better than the single point, small area adsorption, especially in soft materials, breathable materials, irregular workpiece, the difference is very big.

As for the control equipment, it is better to use the valve with stepless changes, to avoid sudden changes of vacuum in the process of adsorption and clamping as far as possible, so as to prevent accidents.

How does the cost-effective vacuum adsorption equipment achieve efficient vacuum adsorption? In the use of imported dry rotary vane vacuum pump as a vacuum generating device, it is mainly focused on the negative pressure above -60kpa, because of its small flow, generally will increase the vacuum buffer tank in the middle, and use a single point, small area sucker to adsorb, reduce air extraction time, improve work efficiency; At the same time, this kind of vacuum pump has strict requirements for clean air, which limits the further application of vacuum adsorption equipment. Price is extremely expensive, and because it is only applicable to high class customers, strict in another kind of request is not high end customers, using the single period of high pressure swirl air pump as a vacuum generator, the double period of high pressure fan to cater to the mid-market, using vortex pump (similar to high-pressure blower structure, but the pressure is much higher than the same power of high pressure air blower, and rotary vane vacuum pumps, traffic is rotary-vane vacuum pump are 1.5 ~ 2 times) to replace the dry rotary-vane vacuum pump are quickly occupied the high-end market.

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