SAPELEM - Guides - Guide accessoires

The good working of a gripping component quite often depends on the good realization of the vacuum circuit

The main rules to be respected are the following ones :

		All the hoses at the same level have the same length Section of hose B = 4 times the section of hose A Section of hose C = 2 times the section of hose B

SAPELEM offers you a wide range of accessories able to optimize the working of your gripping.

They allow to compensate the height dispersions of the gripper regard to the product to be handled.

In case of vertical handling, it is advisable to take into account that the axle is working in flexion/bending and thus to oversize the spring system.

Needle dial allows to display vacuum level inside the circuit. The vacuumeter does not send out any signal, it’s only a visual control, the red and green zones determine the danger zones during the handling of tight products.

There are three families of flappers :

Nonreturn valve :

Function: To keep vacuum in the circuit in case of vacuum generator supply failure.
Safety instructions: Only on tight product, mount a vacuum filter; provide a valve to bleed off a vacuum circuit to air in order to release the part.

Pilot controlled valve: « Safety Valve »

Functions: To keep vacuum in the circuit in case of vacuum generator supply failure and pilot the release of the parts by counter-blow.
Safety instructions: Only on tight product; length of vacuum circuits has to be perfectly balanced.

Leak limiter flappers :

Function: To disconnect the unused suction cups in case of gripping of products with variable sizes or with variable quantities.
Safety instructions: Only on tight product

IWe have to distinguish vacuum filters intended to prevent intrusive solid particles in the vacuum circuit from condensate separators intended to stop the liquids.

Because of the slight difference of pressure in a vacuum circuit, it is advisable to proportion accurately the connectors and the hoses in order to optimize the gripping times

Hose too large = volume useless to empty

Hose too small = important drops of loads

The more and more frequent use of self-regulated vacuum generators imposes more and more tight vacuum circuits. Snap-connectors with cover are thus the most appropriated to this kind of circuit.

Sensor of vacuum level sends out a signal when the preset control threshold is reached. We distinguish 3 technologies of vacuum switch according to the signal they send out.

Pneumatic signal :

Pneumatic with positive function:
It sends out a pneumatic signal when the threshold is reached.
Pneumatic with negative function:
It cuts off the pneumatic signal when the threshold is reached.

Advantage :

No need of electricity

Electric signal :

Electromechanical engineering: a switch moves when the vacuum threshold is reached, according to the kind of used dry contact, it can be:
- NC : the power is on as long as vacuum is not reached
- NO : the power is on when vacuum is reached
- Reverser: it has a NO and a NC contact

Advantages :

The dry contact vacuum switches accept a wide mains voltage’s range: both constant and alternating voltage.

Electronic : three types of outlets :
- NPN : Sending of 24 VDC to the load
- PNP : It earths the load
- Analog: It sends out a signal proportional to the vacuum level. The signal can be “Voltage” (1-5 Volts or 1-10 Volts) or “Current” (4-20 mA)

Advantages :

Measurement and setting accuracy
Possibility to have a digital display of the measured value
Possibility to have additional functions (adjustable counter-blow sequence, adjustable hysteresis)

NPN or PNP outlets can be Normally Opened (NO) or Normally Closed (NC)

Distributors :

Functions: Hold – Safety gripping in case of supply failure – Release.
Type: bistable direct acting; air pressure no required to pilot the slide valves

3-way slide bushes :

Functions: Hold – Release, it puts the suction cup in direct relation with the vacuum circuit or atmosphere.
Safety instructions: protect the valve against involuntary operations to avoid untimely releases.

1/4 turn ball valves :

Functions: Open – Close the vacuum way (suction cup’s selection for example)
Safety instructions: The type 2/2 valve doesn’t allow to bleed off the suction cups to atmosphere; when the valve is closed there is a risk of self-priming of the suction cups.

Anti-self - priming :

Function: Bleeds off big suction cups or circuits with valves easier to atmosphere. Thus it makes the release of the products easier as well as the involuntary gripping by simple touch of the suction cups to the product.
Safety instructions: protect the valve against involuntary operations to avoid untimely releases.

Function: Automatic selection of the suction cups outside the gripping area for products with variable size.

Safety instructions: The suction cups which have to be in contact with the part to be handled have to be totally on the part; those which have to be closed have to be totally outside the part.

Vacuum circuits technical guide

Spring systems

Vacuumeters

Flappers

Vacuum filters

Connectors

Vacuum switches

Valves

Feelers

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