A new version of the program which has full Dynamic
Analysis capabilities has been available in Helix delta-T since 2003.
This version calculates the transient belt Tensions and Velocities during
starting and stopping of a conveyor. It can model the conveyor belt transient
behaviour during Starting Fully Loaded, Starting Empty, Stopping Fully Loaded
and Stopping Empty.
This new version of the program which has full Dynamic Analysis
capabilities is essential for designing high powered conveyors and long overland
conveyors. The Dynamic analysis version includes the Standard and Professional
versions of the software.
The program allows the user to input any number of
Drives or Brakes and allows for input of Drive Torque / Speed curves, Delay
times, Braking Torques, Flywheels and inertia effects. After the Dynamic
Calculations have been performed, the user can view and Print two dimensional
and surface plot three dimensional graphs for Belt Tensions, Belt Velocities,
Strain rates and Takeup movement versus time step for all points along the
conveyor.
The Dynamic calculation process uses sophisticated Variable Step Runge Kutta
method integrators for solving the complex differential equations. All the
numerical analysis is compiled into the program and it does not require any
other software to perform the calculations or display graphs etc. It also allows
flexible, easy to use boundary condition specification by the user.
Helix delta-T uses a Finite Element model of the
conveyor to perform the dynamic analysis. The conveyor is broken up into
segments, and for each segment, we use a Kelvin solid model, which is a spring
in parallel with a viscoelastic element, as shown below:
Kelvin Solid Model
Conveyor Model Diagram
The conveyor model created and captured in the normal
delta-T program is automatically broken up into segments in the Dynamic
Calculation process. The program already knows the geometry of each section of
conveyor, as well as the idler spacing, rotating masses, resistances, inertias,
drive power and location, takeup mass and the equivalent mass of each element in
the conveyor. The Dynamic calculation breaks the standard conveyor sections into
smaller segments. The designer can specify the maximum segment length to be
used.
Delta-T uses the Finite Element method of dynamic analysis.
Once the conveyor is segmented, the moving mass, length etc. of each segment is
known. The Tension force acting on segment i at time t is given by the sum of
the spring and viscoelastic Tension forces, Ts and Tv respectively. At each time
step of say 0.1 seconds, the rate of change of velocity, combined with the
strain on each conveyor segment is calculated. The peripheral force at the drive
pulleys is the motivating force. The main conveyor resistances, represented by
the Coulomb friction factor f, which is a function of instantaneous belt tension
and belt sag at the segment under consideration, are taken into account. All
idler roller rotating masses and pulley, drive and brake inertias are included
in the acceleration and tension calculations. The Drive Torque or Velocity is
input graphically, and the resulting Belt Tensions, strains and belt Velocities
are output for each time step and for each point along the conveyor. These
values are presented graphically for ease of interpretation.
Graphs of the dynamic analysis can be viewed and
printed for the following:
| |
Conveyor Loading
|
|
Graph of |
2 Dimension Graphs
|
3 Dimension Graphs
|
|
Starting |
Fully Loaded |
Empty |
Fully Loaded |
Empty |
|
Braking |
Fully Loaded |
Empty |
Fully Loaded |
Empty |
|
Coasting |
Fully Loaded |
Empty |
Fully Loaded |
Empty |
|
Takeup Travel |
Fully Loaded |
Empty |
Fully Loaded |
Empty |
The Dynamic Calculations are easy use to use and
Engineers who have static conveyor design experience can perform these complex
dynamic simulations using this very powerful software.
-
Easily model the belt transient tensions and
velocities during Starting and Stopping of conveyors.
-
Add Torque Control or Speed Control on drive
acceleration.
-
Add Delay times for multiple drives for Dynamic Tuning
-
Add Flywheels to pulleys to optimise starting and
stopping
-
Add Brakes to pulleys as required.
-
Calculate Dynamic Runback forces and size holdbacks
for dynamic loads
-
View the movement of the Takeup pulley during Starting
and Stopping
-
Predict the maximum Transient Belt Tensions at any
point along the conveyor as well as the timing of these transients.
-
Compare the Dynamic Calculations results with the
rigid body static calculations in the delta-T5.
-
Predict the magnitude of transient loads on conveyor
structures.
-
Calculate the torque loadings on gearboxes, holbacks
and couplings during starting and stopping. Eliminate conditions which may cause
costly equipment failures.
-
Perform Dynamic Tuning by changing the start delay
times on different drives
- Helix delta-T allows the designer to control the
starting of a conveyor by means of
- Torque Speed Control - Starting
- Speed Time Control - Starting
- Constant Torque Brake - Stopping
- Speed Time Curve Control - Stopping
Sample of Belt Velocity Graph for conveyor starting
Sample Belt Tension Graphs for conveyor starting full
Takeup Travel Graph
Example of Dynamic Analysis - conveyor stopping loaded
Belt Velocities
Belt Tensions
Note Tension rise as conveyor comes to rest and holdback locks up.
The program
will automatically calculate the belt tensions in the system, select a suitable
belt from the database, calculate the pulley and shaft sizes required, select a
suitable electric motor, fluid coupling and gearbox from the databases,
calculate the idler shaft deflections and bearing life and then present the full
conveyor design in reports which can be viewed, printed or exported to Word for
Windows, Excel, PDF files and other applications.
Belt tensions can be viewed
graphically, and the Calc section provides useful procedures for calculating
discharge trajectories, hoper pull-out forces, vertical curve radii, horizontal
curve banking angles and belt drift, trough transitions distances and other
frequently performed routines. Context sensitive on screen Help will guide you
through the operating procedures and provide the formulae used in the
calculations.
You can also create and view a 3D model of the conveyor. The
program also allows you to dynamically calculate vertical and Horizontal curve
geometry for the conveyor. In addition, delta-T provides an in-depth analysis of
conveyor belt tensions under different operating conditions such as running
fully loaded, running empty, starting fully loaded, starting empty, braking
fully loaded, braking empty and coasting. A new sketch facility allows users to
sketch the conveyor profile and enter data in tabular format.