Control equipment spins a good yarn

An advanced mobile Carding Aid machine is being developed with the aid of a PLC from IMO

When Jim Kelly’s ControlAbility and textile consultant Malcolm McMath were developing their KelMac mobile Carding Aid machine, they turned to IMO for control equipment.

IMO supplied equipment crucial to the machines’ operation, including a G6 programmable logic controller (PLC), an intelligent human machine interface (HMI) and three VXM inverter drives. On board the G6 PLC is a CNET communication card which allows the PLC to communicate with any other device.

In this instance, the PLC communicates with a load cell digitiser (LCD). When introducing effect fibres to the machine, it is essential that the amount is strictly controlled. This is acieved by weight checking, which needs to be done frequently and quickly. On the KelMac machine, the LCD checks the effect fibre weight some 250 times per second. Although the process does not require 250 samples per second, IMO technology allows this to be averaged out precisely, says the company.

Once connected to a main production machine, effect fibres are loaded into the hopper of the KelMac Carding Aid. From here they go to a wire feed roller then to a stripping roller which strips the effect fibres off the feed roller. IMO VXM inverter drives, even without feedback control, overcome the limitations of normal AC drives which can become unstable at low speeds. Although the stripping roller has less work to do, it still has to operate at low speed and not stall.

A feed (or weighing) conveyor delivers the effect fibres to the pneumatic delivery fan. To enable this it is suspended on load cells which calculate average weights. The feed conveyor is some 900mm long and is broken down into 20 blocks of 45mm length. Each block can be slowed or accelerated individually to ensure a precise delivery rate. If the delivery rate is too high, the wire feed roller automatically slows down to reduce the delivery rate or increases in speed if the delivery rate is too low.

The technology of the G6 PLC enables users to write their own functions. These are automatically stored in an array which outputs a stable instruction to the drives.

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