Beltweigher
Encyclopedia
A beltweigher or belt weigher is a piece of industrial control equipment
used to gauge the mass or flow rate of material travelling over a troughed (cupped) conveyor belt of any length which is able to adequately contain the material being weighed. These are also known as belt scales, dynamic scales, conveyor scales, and in-motion weighers. Many such check weigher
s or feed weighers are an active part of the process flow control of the conveyor line.
A belt weigher replaces a short section of the support mechanism of the belt, which might be one or more sets of idler
rollers, or a short section of channel or plate. This weighed support is mounted on load cell
s, either pivoted, counterbalanced or not, or fully suspended. The mass measured by the load cells is integrated
with the belt speed to compute the mass of material moving on the belt, after allowing for the mass of the belt itself. Belt weighers generally include the necessary electronics to perform this calculation, often in the form of a small industrialized microprocessor
system.
A belt weigher is normally mounted in a well supported straight section of belt, with no vertical or sideways curvature, and as close to level as is practicable. The weighed support must be aligned vertically and horizontally with the adjacent supports to avoid tensile forces in the belt skewing the measurement.
Due the belt tension variation, frequent check calibration must be done.
Outputs from belt weighers are typically:
In addition, some belt weigher controllers will offer features such as driving an output to stop the belt when a predefined mass of material has been measured, or a range of alarms to indicate nil flow, belt slippage and belt stoppage.
Uses include mineral and aggregate extraction, continuous mixing processes, control of variable rate feeder
s, port handling and ship loading processes.
Control system
A control system is a device, or set of devices to manage, command, direct or regulate the behavior of other devices or system.There are two common classes of control systems, with many variations and combinations: logic or sequential controls, and feedback or linear controls...
used to gauge the mass or flow rate of material travelling over a troughed (cupped) conveyor belt of any length which is able to adequately contain the material being weighed. These are also known as belt scales, dynamic scales, conveyor scales, and in-motion weighers. Many such check weigher
Check weigher
A checkweigher is an automatic machine for checking the weight of packaged commodities.It is normally found at the offgoing end of a production process and is used to ensure that the weight of a pack of the commodity is within specified limits...
s or feed weighers are an active part of the process flow control of the conveyor line.
A belt weigher replaces a short section of the support mechanism of the belt, which might be one or more sets of idler
Idler
An idler is a mechanical device such as an idler pulley or idler wheel that is secondary to the main transfer of power in a mechanical system. They are support rollers on which conveyor belts move...
rollers, or a short section of channel or plate. This weighed support is mounted on load cell
Load cell
A load cell is a transducer that is used to convert a force into electrical signal. This conversion is indirect and happens in two stages. Through a mechanical arrangement, the force being sensed deforms a strain gauge. The strain gauge measures the deformation as an electrical signal, because the...
s, either pivoted, counterbalanced or not, or fully suspended. The mass measured by the load cells is integrated
Integral
Integration is an important concept in mathematics and, together with its inverse, differentiation, is one of the two main operations in calculus...
with the belt speed to compute the mass of material moving on the belt, after allowing for the mass of the belt itself. Belt weighers generally include the necessary electronics to perform this calculation, often in the form of a small industrialized microprocessor
Microprocessor
A microprocessor incorporates the functions of a computer's central processing unit on a single integrated circuit, or at most a few integrated circuits. It is a multipurpose, programmable device that accepts digital data as input, processes it according to instructions stored in its memory, and...
system.
A belt weigher is normally mounted in a well supported straight section of belt, with no vertical or sideways curvature, and as close to level as is practicable. The weighed support must be aligned vertically and horizontally with the adjacent supports to avoid tensile forces in the belt skewing the measurement.
Due the belt tension variation, frequent check calibration must be done.
Outputs from belt weighers are typically:
- pulses at predefined increments of mass
- an analogueAnalog signalAn analog or analogue signal is any continuous signal for which the time varying feature of the signal is a representation of some other time varying quantity, i.e., analogous to another time varying signal. It differs from a digital signal in terms of small fluctuations in the signal which are...
signal proportional to the flow rate
In addition, some belt weigher controllers will offer features such as driving an output to stop the belt when a predefined mass of material has been measured, or a range of alarms to indicate nil flow, belt slippage and belt stoppage.
Uses include mineral and aggregate extraction, continuous mixing processes, control of variable rate feeder
Variable rate feeder
A variable rate feeder is a piece of industrial control equipment used to deliver solid material at a known rate into some process.A number of different techniques and transport mechanisms are used, but these broadly split into these categories, in descending order of accuracy:* closed-loop...
s, port handling and ship loading processes.