Roman Jablonski Prof. Ph.D.Eng.

Piotr Kulinowski Ph.D.Eng.

University of Mining and Metallurgy, Cracow, Poland

Department of Mining Machines and Waste Utilization Equipment

*Belt conveyors, tension systems, simulation tests*

The mathematical, discrete model of the belt conveyor is used for analysis of this system. In the analysis, the belt is substituted by the rheological model describing dynamic properties and the Rayleigh model as a multi-mass discrete representation of the belt continuity.

The system of differential equations describing the belt conveyor model is given as a multivariate computer program.

The calculation results gave the following information: about the tension variations in the belt, acceleration, velocity of chosen points of the belt and displacements of stretching cars. Starting and stopping of the belt conveyor have been considered.

Simulation tests have been experimentally verified on the real object. It was the underground coal-mine belt conveyor (length: 910 m, power 2x150 kW). Authors used the TV-camera to register a displacement of the stretching car during starting of the conveyor. Results of simulations and experiments were compared and show the satisfactory similarity.

Designers use the standard methods for calculations operating parameters of the belt conveyors, but these analyses gives the unsatisfying results during starting and stopping of conveyors. In mining belt conveyors are used modern types of drives: "soft-start", intermediate belt drives (T-T systems), new construction of belt cord, new types of tension systems and horizontal curves. Therefore designers should to dispose of calculating methods in order to identify technical effects of usage specific drive type, tension system and conveyor belt with specific viscoelastic properties.

Discrete belt conveyor models have been used for analysis of dynamic phenomena during starting and stopping since the 70’s and were described in [1, 5, 6, 8, 10, 12, 14].

The tested conveyor may have optional layout and can be loaded at any point along the conveying route. Also it can be equipped with many kinds of drive types and tension systems.

In simulation tests of drives were taken into consideration: motors, hydraulic and flexible couplings, brakes, reducers and possibility the belt slip on the drive pulley.

For calculating the frictional resistance of belt conveyor was used the computer program QNK supported by the DIN22101.

The discrete model of the belt conveyor makes possible to model all known tension systems: fixed, gravity take-up, winch operated, pneumatic take-up, hydraulic take-up and mechanical follow-up device.

- Max. capacity - 1000 t/h
- Conveying length - 910 m
- Belt width - 1000 mm
- Belt type GTP 1000 (textile cord) - FTT Wolbrom Poland
- Belt speed - 1.62, 3.24 m/s
- Installed power - 2 x 75/150 kW (2 speed motor)

The principle of **MFBT** operation shows the scheme on Fig.3. The
task of this tension system is to keep forces T_{1} and T_{2}
in constant proportion (T_{1}/T_{2} = constant = b/a) and
to eliminate the belt slip on the drive pulley.

In belt conveyor drums are located on trolleys linked with rope. Its transmission ratio depends on the type of drive (friction factor between belt and the drum pulley surface, angle of wrap). The first trolley "A" is located in the area of belt running on the drive drum (red color on figures), the second one "B" in the area of belt running off the drive drum (green color on figures). (Fig.4, Fig.5)

The analysis of courses of forces variations in the belt, velocities and trolleys movements permits to find relations between the velocity of stress front in the belt and the movement of trolley stretching the belt in the starting conveyor. Those relations as results of simulation tests are presented on fig.7, fig.8, and fig.9 (red line).

The tension device described above will to exactly follow-up system
if both trolleys have possibility to move. If the trolley "A" will lean
against the buffer (extreme right position) then this device will be "fixed"
- T_{1}/T_{2} is not constant.

For the verification of simulation tests authors used the TV-camera
to register a movement of the stretching trolley "A"
during starting of the empty conveyor (Fig.6). The result of measurement
is shown on fig.9 (green line).

The results of simulation tests are presented by using the computer
program DynaBelt.

Download
the compressed computer program dynabelt.zip (292 K).

- New transport tasks for belt conveyors and new constructional solutions force designers to improve the calculations methods, because the standards methods of calculation of belt conveyor do not take in consideration the dynamic phenomena in belt conveyor during starting and stopping.
- Simulation tests of the dynamic belt conveyor model permit multivariate analysis of various constructional solutions of conveyors and determine running parameters, which are essential for designers and users.
- The comparison of simulation tests and measurement results of selected parameters of operation of mechanical follow-up tension system verified the modeling method of tension systems analysis. Results of simulations and experiments were compared and show the satisfactory similarity.

- 1. Funke H.: Über die dynamische Beanspruchung von
Förderbandanlagen beim Anfahren und Stillsetzen. Braunkohle, Heft 3, p.
64-73 März 1974.

2. Funke H., Könneker F.R.: *Experimental Investigations
and Theory for the Design of a Long-Distance Belt Conveyor System. *Bulk
Solids Handling, Vol.8, No. 5, p. 567-579. October 1988.

3. Jabłoński R. Zieba
G.: *Automatic Mechanical Follow-up Conveyor Belt Tension System.
*5th International Conference on Bulk Materials Storage, Handling and
Transportation. Newcastle 10-12 July 1995.

4. Jabłoński R., Kulinowski
P.: *The Comparison of Simulation Tests and Measurement Results
of Selected Parameters of Automatic Follow-Up Device Stretching the Belt
in The Belt Conveyor.* Prace Naukowe Instytutu
Górnictwa Pol. Wrocł. , p. 111-121. Szklarska Poręba 1996. (in Polish)

5. Karolewski B.: *An Investigation of Various Conveyor
Belt Drive Systems Using a Mathematical Model. *Bulk Solids Handling,
Vol.6, No. 2, p. 61-65. April 1986.

6. Kulinowski P., Jabłoński
R.: *Simulation Test of a Belt Conveyor Model. *International
Computer Science Conference **microCAD'94.**. Miskolc, Hungary 3.03.94.
(in German)

7. Kulinowski P., Jabłoński
R.: *Computer - Aided Analysis of the Belt Conveyor Dynamics.*
Prace Naukowe Instytutu Górnictwa Pol. Wrocł. 78, p. 47-54. Szklarska Poręba
1995. (in Polish)

8. Nordell L.K., Ciozda Z.P.: *Transient Belt Stresses
During Starting and Stopping: Elastic Response Simulated by Finite Element
Methods. *Bulk Solids Handling, Vol.4, No. 1, p. 99-104. March 1984.

9. Otrebski M.: *Influence of Motor Starting Sequence
on Conveyor Start-Up. *Bulk Solids Handling, Vol.15, No. 2, p. 253-256.
April/June 1995.

10. Schulz G.: *Analysis of Belt Dynamics in Horizontal
Curves of Long Belt Conveyors. *Bulk Solids Handling, Vol.15, No. 1,
p. 25-30. January/March 1995.

11. Schulz G.: *Calculation of the Dynamics of Long
Belt Conveyors. *Internet-http://ourworld.compuserve.com/homepages/Conveyor_Dynamics/
1996.

12. Schulz G.: *Comparison of Drives for Long Belt
Conveyors. *Bulk Solids Handling, Vol.15, No. 2, p. 247-251. April/June
1995.

13. Schulz G.: *Further Results in the Analysis
of Dynamic Characteristics of Belt Conveyors *Bulk Solids Handling,
Vol.13, No. 4, p. 705-710. November 1993.

14. Żur T.: *Vicoelastic
Properties of Conveyor Belts. *Bulk Solids Handling, Vol.6, No. 3, p.
85-92. June 1986.

Piotr Kulinowski Ph.D.Eng.

University of Mining and Metallurgy, Cracow, Poland

Department of Mining Machines and Waste Utilization Equipment

Al. Mickiewicza 30, B-2, pok.6

tel. +48 12 173074

fax +48 12 335162

e-mail kulipi@uci.agh.edu.pl