ejercicios lab 022311

8/22/2019 Ejercicios Lab 022311

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Festo Didactic GmbH & Co. FP1110 A-23

To learn about the switching characteristics of an inductive proximity sensor.

Study the exercise. You will find hints and explanations in the textbook ProximitySensors.

Before the practical construction of the exercise, read through the data sheets ofthe components required.

Assemble the components. You can carry out the exercise in accordance with the description in paragraph

"Practical assembly".

Make a note of everything you consider of particular interest.

Warning

The electrical power supply must be switched on only after all connections have

been established and checked. After completion of the exercise, the voltage supply

must be switched off before the components are dismantled.

Exercise 3

Switching distance of an inductive proximity sensor

Training aim

Exercise definition


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Exercise 3

A-24 Festo Didactic GmbH & Co. FP1110

On an assembly station the presence of magazine shafts is monitored usinginductive sensors. Measure the switching distance of various inductive sensors in

order to determine the switching distance between a metal object and the sensor.

2

1

Inductive proximity switch (1), Magazine shaft (2)

Problem description

Positional sketch


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Exercise 3


Inductive sensors contain an oscillator circuit, which consists of a parallel resonancecircuit with inductance and capacitance as well as an amplifier. By means of a ferrite

shell core of the inductance (coil), the electromagnetic field is directed towards the

outside.

If an electrically conductive material is introduced into the electromagnetic stray

field then, according to the laws of inductance, eddy currents are created, which

attenuate oscillation. Depending on the conductivity, the dimensions and the

distance of the approaching object, the oscillator can be attenuated to such an

extent that oscillation stops. Attenuation of the oscillator is evaluated via

subsequent electronic devices, and an output signal generated.

6

Oscillator (1), Demodulator (2), Triggering stage (3), Switching status

indicator (LED) (4), Output stage with protective circuit (5), External voltage (6),

Internal stabilised voltage (7), Active switching zone (coil) (8),

Switching output (9)

Function description


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Exercise 3


1

3

4

2

1020304050 100 20 30 50 60 70 80 90 100

Item no. Qty. Designation

1 1 Distribution unit, D:ER-VERT-SENSOR-...

2 1 Positioning slide, D:ER-VS-FP1110-...

1 Vernier caliper, D:AS-MS

3 1 Inductive sensor unit 1, D:ER-SIEH-M18B-...


1 Set of test objects, mild steel S 235 JR, part 3

Layout

Components list


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Exercise 3


1

BN(1)

BU(3)

BK(4)

2




or

Inductive sensor unit 2, D:ER-SIEH-M12B-...

BN(1)

BU(3)

BK(4)

+24 V DC

0 V

Electrical connections

Electrical circuit diagram


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Exercise 3


Mount the distribution unit, the positioning slide and the inductive sensor unit 1onto the profile plate. The inductive sensor is mounted centrally in front of the

middle of the positioning slide (see fig. "Layout"). Connect the 24V electrical power

supply and the inductive sensor to the distribution unit (see fig. "Electrical

connections").

Attach the vernier caliper to the positioning slide.

Now take the calibrating plate in mild steel (S 235 JR, part 3) from the set of test

objects and fit it into the material fixture of the positioning slide.

Measure the switching distance of the sensor. Make a note of the point, at which the

signal change occurs when the plate approaches the sensor, and also the point at

which the signal change occurs when you move the plate away from the sensor. The

difference between these two points is the hysteresis of the sensor.

Hysteresis (mm) = Switch-off point (mm) Switch-on point (mm)

Carry out the same measurements with the inductive sensor unit 2.

Repeat the measurements several times in order to check the reproducability of theswitching distance.

Mounting the vernier caliper

When mounting the vernier caliper, the slide unit of the positioning slide is set at

"0". The two measuring pointers are moved apart by approximately 10 mm. The

vernier caliper is placed parallel to the base plate, flush with the edge, so that the

front pointer is adjacent to the stop for the vernier caliper. The body of the caliper is

attached to the base plate of the positioning slide by means of the two retaining

magnets.

Practical assembly 1

Practical assembly 2


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Exercise 3


Inductive sensor unit 1 (D:ER-SIEH-M18B-...)

Switch-on point:

Switch-off point:

Hysteresis:

Inductive sensor unit 2 (D:ER-SIEH-M12B-...)

Switch-on point:

Switch-off point:

Hysteresis:

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Evaluation

Conclusions


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Exercise 3



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To learn that the switching distance of inductive proximity sensors is dependent onmaterials when sensing different metals.






Warning




Exercise 4

Sensing of different metals with inductive proximity sensors

Training aim

Exercise definition


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Exercise 4


On a conveyor, metal containers are used for the transport of assembly parts. Theposition of the containers on the individual station is defined by means of an

inductive sensor. A selection of containers in different materials is available. The

effect of the different materials on the switching distance is to be examined.

Problem description

Positional sketch


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Exercise 4


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3

2

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The components list is continued on the following page.

Layout

Components list


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Exercise 4



1 Set of test objects, mild steel S 235 JR, part 3

1 Set of test objects, stainless steel, part 4

1 Set of test objects, aluminium, part 5

1 Set of test objects, brass, part 6

1 Set of test objects, copper, part 7

Components list(continued)


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Exercise 4


1

BN(1)

BU(3)

BK(4)

2




BN(1)

BU(3)

BK(4)

+24 V DC

0 V




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Exercise 4


Mount the distribution unit, the positioning slide and the inductive sensor unit 1 onthe profile plate. The inductive sensor is to be mounted centrally in front of the

positioning slide (see fig. "Layout"). Connect the 24V electrical power supply and

the inductive sensor to the distribution unit (see fig. "Electrical connections").


Measure the switching distance of the sensor for the different materials from the set

of test objects. Make a note of the point at which the change-over occurs, when the

plate approaches the sensor, as well as of the point of change-over when you move

the plate away from the sensor.

Take the mild steel plate (S 235 JR, part 3) from the set of test objects and fit it into

the material fixture of the positioning slide.

Take the various metal plates (stainless steel, aluminium, brass and copper) from

the set of test objects and carry out the measurements.

Determine the reduction factor of the switching distance for the different materials.

The reduction factor for mild steel (S 235 JR) is 1. With the other items, you can

obtain their respective value by dividing the determined switching distance by the

value of the switching distance for mild steel.







magnets.

Practical assembly


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Exercise 4


Material Switch-on point

[mm]

Switc-off point

[mm]

Hysteresis

[mm]

Reduction factor

Mild steel

S 235 JR,

part 3

1

Stainless steel,

part 4

Aluminium,

part 5

Brass,

part 6

Copper,

part 7

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Evaluation

Conclusions


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Exercise 4



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To learn about the influence of objects of different size on the switching distance ofan inductive proximity sensor.






Warning




Exercise 5

Influence of the object surface on the switching distance

Training aim

Exercise definition


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Exercise 5


Metallic objects of different size must be detected on a rotary indexing table by aninductive sensor. Only parts made from mild steel (S 235 JR) are to be detected.

Investigate the influence of the object size on the switching distance of the sensor.

Problem description

Positional sketch


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Exercise 5


1

3

2

1020304050 100 20 30 50 60 70 80 90 100






The components list is continued on the following page.

Layout

Components list


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Exercise 5



1 Set of test objects, mild steel S 235 JR, 30 mm x 30 mm, part 11






Components list(continued)


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Exercise 5


1

BN(1)

BU(3)

BK(4)

2




BN(1)

BU(3)

BK(4)

+24 V DC

0 V




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Exercise 5


Mount the distribution unit, the positioning slide, and the inductive sensor unit 1 onthe profile plate. The inductive sensor should be mounted offset by 5 cm against the

centre of the positioning slide (see fig. "Layout"). Connect the 24V electrical power

supply and the inductive sensor to the distribution unit (see fig. "Electrical

connections").


Take the mild steel plates of different length (parts 11 - 16) from the set of test

objects and carry out the measurements. Measure the switching distance of the

proximity sensor for each of the plates. Make a note of the measurements at which a

signal change occurs when the plates approach the sensor.







magnets.

Note

The object of this exercise is to determine the relation between the switching

distance and the size of the object. Standard EN 50 010 specifies a standard

calibrating plate for defining the nominal switching distance. The standard

calibrating plate for an inductive sensor is 1 mm thick and has an edge length either

of the diameter of the inscribed circle of the active surface of the sensor or three

times the length of the nominal switching distance of the sensor, whichever value is

the larger.

For the sensor used, the nominal switching distance is 7 mm and the diameter of the

active surface 16 mm. The standard calibrating plate sides must thus have a length

of 21 mm.

Practical assembly


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Exercise 5


Length of sides Switching gap [mm]

Mild steelS 235 JR,

part 11: 30 mm

Mild steel S 235 JR,

part 12: 25 mm


part 13: 20 mm


part 14: 15 mm

Mild steel S 235 JR,part 15: 10 mm


part 16: 5 mm

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Evaluation

Conclusions


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Exercise 5

ejercicios lab 022311

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