Many industrial applications require a counter, or a length measurement to determine the final product requirements for processing and packaging. Where lengths are fixed these can be designed into the machine, whereas other industries have varying production counts or lengths and require continuous measurement to ensure counts or cut lengths are correct.
Count Measurement can use a counter such as the Lumel N30O receiving pulses from either:
- Proximity sensor detecting bolt heads, metal tags similar
- Photo-electric Sensor detecting cut-outs in a roller or holes in a wheel, or products directly
- Encoder providing X number of pulses per revolution connected to a shaft or a fixed circumference measuring wheel
Whether counting 1 pulse = 1 product, or 1000 pulses = 1 metre, the function of the counter varies considerably using the same electronic product with the determining factor of speed or accuracy coming from the sensor. ie:
- Count 24 cans by Photo-Electric sensor and provide output (24 per carton)
- Count 64 bolt heads with Inductive sensor (4 bolts per rotation) = 8 rotations and output (stop)
- Count pulses from encoder (360 pulses = 1 revolution) and stop at 1200 revolutions.
Counters all have pre-set functions for triggering relay outputs to operate other equipment and can also include secondary counters for counting batch quantities ie: 150 cartons and stop.
Length Measurement or Cut-to-length
The use of the counter to count pulses from an encoder attached to a measuring wheel to accurately count length can be simply achieved with high accuracy also with UP/Down count for product moving forward and backwards. Wheel sizes are available from 200mm to 500mm and with an encoder of at least 1 pulse output per mm circumference of the wheel will provide approximately 1mm accuracy. A higher resolution from the encoder will provide a higher accuracy. The value division between wheel circumference and pulses is entered into the counter for accuracy such as 500mm (Wheel) / 1200 pulses (Encoder) = 500/1200=0.4166666 scaling will be entered into the counter so the counter accurately measures every mm.
For cut to length applications, a counter ideally has 2 setpoints and 2 relay outputs. These can be used to slow machine prior to cut, to stop the machine, to cut, a grab jaw, to mark position of cut. Outputs could also provide distance marks or provide a batch output stop.
A setpoint for the cut length is configured and if required additional outputs for other functions so when the pulses count up to the setpoint, a relay will turn on. If the machine is required to slow prior to the setpoint, an additional setpoint can be used.
Setpoints can simply be changed via the front panel, or utilising the inbuilt RS485 communications, A PC or HMI can be used as a central point for communicating with the on machine counter that provides high visibility to the operator.
More automation such as an IDEC PLC can be incorporated into the process to replace the counter and provide a more sophisticated factory control centre with HMI touch screen. The end result is the same with the added advantage of higher communications software processing the time, quantities and logging of material from the production process for Invoicing and despatch systems.
Manufacturers: Balluff, Kubler, Lumel, IDEC