Belt conveyor concave arc section curvature half calculation steps and examples

The biggest headache for newbie geeks when they first get into conveyor design is.Why does the equipment always spill material in the turns? Why does the conveyor belt float when starting with no load?In fact, the core of the problem is often hidden in the design of the concave arc section - the radius of curvature is calculated wrong! Today we use the most vernacular way to disassemble the calculation steps, combined with real cases, hand in hand to teach you to avoid those pits.

I. What exactly is the radius of curvature of a concave arc segment?

Imagine you take a rubber band taut and lift it upwards, the centre will naturally sag into an arc. The concave curved section of the conveyor is this principle.The concave curve formed when the conveyor belt shifts from horizontal to climbing.(Figure 1). The radius of curvature (R) is the value that describes how much this arc bends - theThe smaller the radius, the sharper the bend; the larger the radius, the smoother the bend.

Why is it important to count on it? Come see two rollover sites:

• ​The radius is too small.: The edge of the conveyor belt is not taut, and the material spills out (insufficient tension on the edge);
• ​the radius is too large: The conveyor belt floats directly away from the rollers during no-load start-up and flies like a kite (fluttering belt accident).

II. Core formula dismantling: 4 parameters determine life and death

Let's start by dumping the industry's common formula (don't panic, it's explained step-by-step later):

​R₂ ≥ Fx / (qB × g) × 1.5​
(1.5 times the safety factor)

Where does this formula come from? Let's take it apart and crumble it up:

1. ​Fx (concave arc starting point tension in Newton N)​
   ​Initial force of belt tensionThe more strength you put into a tug of war, the less likely the rope is to come undone. Just like in a tug of war the harder you make it, the less likely the rope is to come undone. Get the way:

   • Check the design manual for tension calculations (e.g., graph ↓)
   • or deduced by the point-by-point tension method
     Chestnut: a DTII coal conveyor Fx = 16,790N

   tension point	Operating conditions Fx(N)	Start-up condition Fx(N)
   concave arc origin	16,790	19,940

2. ​qB (mass per unit of conveyor belt in kg/m)​
   ​How much does each metre of conveyor belt weigh?The tape is made from a variety of materials, such as aluminium, aluminium and aluminium. Directly check the tape parameter table, common NN-100 type canvas tape is about 13-24kg/m.
   Note: Lightweight straps are more likely to float!

3. ​g (acceleration due to gravity, constant 9.8 m/s²)​
   Earth's gravitational value, fixed.

4. ​1.5 (safety factor)​
   Bumper!At no load qB is minimum and R demand is maximum(The smaller the denominator in the formula, the larger the result). No coefficient? Wait for the no-load flutterbelt!

Hands-on practice: coal conveyor concave arc design calculation

​contexts::

• Belt width 1200mm, belt speed 2.5m/s
• Conveying capacity 1200t/h, inclination angle 7°.
• Tape model NN-100, qB=13.36kg/m
• Tension calculated Fx = 16,790N (operating condition)

​Substituting the formula::

R₂ ≥16,790/ (13.36×9.8) ×1.5​
= 16,790 / 130.93 × 1.5
=192.3 metres​

​Key findings::
​The radius of curvature of the concave section of the conveyor must be ≥ 192.3 metres.. What if the roadway height on site is insufficient (e.g. only 3.5 metres)? Engineer's remedial programme:

1. Addition of a pressure pulley to force down the conveyor belt (but it will wear the tape)
2. Change to a segmented transfer design (two conveyors lapped to avoid large arcs)

Fourth, novice high-frequency stepping on the pit point (blood and tears experience!)

1. ​Why is R₂ calculated on a full load and still drifting with no load?​
   →You're ignoring the safety factor!At no load qB gets small (no material), equation denominator is smallest, R demand is largest. Not adding 1.5 times? Wait to fix the equipment!

2. ​It's no use forgetting the formula, there's simply not enough room on site!​
   → Look at the real case: a mine tunnel height limit of 3.5m, according to the formula needs to be lifted 7.8m. engineers of the tawdry operation:

   • ​Option A: Pressure pulley set (low cost but hurts the belt)
   • ​Option B:: Dual machine reproduction (expensive but once and for all)
     I stand by Option B - the savings on repairs paid for themselves long ago!

3. ​How do you break the edge scattering?​
   The radius of curvature is just the basis!Slot angle λ≥35°+Deep groove double rows of quadruple rollersIt is the king of anti-spill combination. It's like adding a "stopping bowl" to the conveyor belt, so the material won't spill no matter how it's turned upside down.

V. Comparison of R₂ under different working conditions (table in seconds)

Note: Data based on a yard tailing case

Engaging in conveyor design is like walking a tightrope.The radius is too small for sprinklers, too big for flaps, and you have to rack your brain to change the plan when you run out of room.. But grabbing the two core parameters, Fx and qB, and latching on to the 1.5x safety factor will avoid at least an 80% accident. Next time you encounter a concave arc section - pull out the formula to calm the field, then slap the table and yell at the construction team, "Do it my R₂!" .