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Therefore, it is necessary to select a micro vacuum pump in the true sense, such as PK, PC, VCH, etc., but not a gas sampling pump, such as SA, SB, PM series (see "Micro Vacuum Pump, Air Pump Classification" for details).
(ie F≈0.01×maximum negative pressure of the pump×sucker area)
In the above formula, F: theoretical adsorption force, unit: Kgf (kg force)
P absolute pressure: the absolute vacuum of the micro vacuum pump, the unit is: KPa (kPa)
S suction cup area: the effective area of ​​the suction cup, the unit takes: cm 2 (cm 2 )
(usually calculated according to local atmospheric pressure = 100kPa)
(assuming the suction cup area is 1 square centimeter)
1. Under the same negative pressure, the micro-vacuum pump with large flow rate is stronger than the actual suction force with small flow rate (because the replenishment is fast, the ability to maintain this negative pressure is strong for the system). For example, the peak flow rate of VCA5038 is 38L/MIN. Compared with the 15L/MIN of PCF5015, although the negative pressure is the same, the actual adsorption force is stronger than PCF5015N.
2. The above adsorption weight refers to the case of vertical upward adsorption (ie, the suction force of the pump is upward, against the downward gravity of the object); while the vertical downward adsorption and the side adsorption are much more complicated, because the friction coefficient of the contact surface is involved. Different factors such as different stress conditions, and even problems such as moving after adsorption, cannot be simply selected according to the above table.
Micro vacuum pumps, miniature vacuum pumps, vacuum pump, often used for object adsorption, there are several issues to note:
1. The meaning of vacuum adsorption:
It refers to connecting the vacuum pump suction port to the object to be adsorbed through suction cups, tubes and other components. At this time, the suction cup is similar to the closed container, and the suction cup is vacuumed, causing the internal air pressure to change from normal pressure to negative pressure, using the external atmospheric pressure and the negative pressure. The pressure difference acts to achieve the purpose of absorbing the object.
2. Calculate the theoretical formula of the adsorption force:
F≈0.01 (101-P absolute pressure) S suction cup area
It can be seen from the above equation that the magnitude of the adsorption force is theoretically independent of the flow rate of the pump, but is related to the flow parameter in actual use. The reason is as follows: Because the pneumatic system is impossible to achieve theoretical sealing, there is always a certain leakage. In this case, the larger the flow rate of the micro vacuum pump, the smaller the proportion of the leakage amount, and the more favorable the pump maintains a higher vacuum degree, thereby obtaining a larger adsorption force. For example, there are two pumps with the same ultimate vacuum. The flow rate of the A pump is 1L/min, and the flow rate of the B pump is 20L/min. Also in the case of 0.1L/min leakage, the vacuum of the A pump will be much lower, because 0.1 The L/min leak is too big for it. However, the 0.1L/min leak is nothing for the B pump and still maintains a high vacuum. Therefore, although the vacuum is the same, in practice, the B pump produces a greater adsorption force.
Therefore, when selecting the pump, it is necessary to consider both the vacuum degree and the flow rate. It is impractical to only pay attention to the vacuum degree index.
For the question of the speed of adsorption time, please refer to the curve and calculation tool of the vacuum degree in the container with the pumping time when pumping the closed container.
The release problem after the object is sucked. When it is necessary to release the object being sucked, the pump must first be stopped and no further vacuuming is required. After the pump is stopped, the object does not necessarily fall off immediately, because the pump has a certain pressure holding capacity, and the vacuum will continue to be maintained for a while. In order to release immediately, the pneumatic system should add another branch, connect a switch valve, stop the pump and open the valve at the same time, and immediately eliminate the vacuum of the pneumatic system, so as to reliably release the object.
3. The maximum suction force (adsorption force) that can be provided by the common micro vacuum pump + the weight of the object to be sucked (blue represents the most frequently used model)
series
model
Maximum negative pressure (kPa)
Maximum adsorption force (Kgf kg force)
The maximum weight (grams) of the object that can be lifted from the bottom up (in theory)
VM
VM8001
-20
0.2
200
VM7002
-30
0.3
300
VM6503
-35
0.35
350
VM6005
-40
0.4
400
VAA
VAA6005
-40
0.4
400
VAA5008
-50
0.5
500
PK
PK5008
-50
0.5
500
PK4512
-55
0.55
550
PC
PC4020N
-60
0.6
600
PC3025N
-70
0.7
700
VCH
VCH1028
-90
0.9
900
VCA
VCA5038
-50
0.5
500
FAA
FAA4002
-30
0.3
300
FAA6003
-40
0.4
400
FAA8006
-50
0.5
500
PCF
PCF5015N
-50
0.5
500
note: