Packaging
High speed pea counting
Friday 02. May 2008 - Rapid response valves in sorting systems
From rice and peas to plastic items: modern high-speed sorting systems sort items of all kinds by colour, shape or size. Faster than the human eye can perceive, rapid response valves type MHJ – also known as “Jet Valves” – blow bulk goods into various containers with perfect precision. Festo provides support for commissioning, as well as for function monitoring via the SBOC-M/SBOI-M intelligent compact vision system.
When sorting red and green plastic balls measuring 6 mm in diameter, the exemplary sorting system offers maximum performance. In real time, rapid response valves of type MHJ separate the mixed balls into different containers after they have been rolled down a chute. The SOEC colour sensor analyses the colours of the 12 grm. balls at the end of the chute. The strengths include a high switching frequency of 500 Hz and three independently teachable channels. A white LED light source renders the SOEC independent of external light sources and enables it to guarantee the recognition of objects in the entire working area, so that the sensor maintains an overview even at high speeds.
Rapid switching
The sensor sends a signal to the CPX-FEC control unit. This sets the rapid response valves in motion. Having a throughput of 50 l/min to 150 l/min as an individual valve or manifold sub-base valve and extremely short switching times of less than 1 ms, the MHJ valves are true professionals in the high-speed sector. The familiar types MH3 with 200 l/min and MH4 with 400 l/min are suitable for higher throughputs. These have switching times of less than 3 ms in the case of the MH3 and less than 4 ms in the case of the MH4. PLC standard 24 V DC/1A outputs enable simple and direct control of versions with integrated electronics – now with a very low powered triggering input. Alternatively, an external two-channel cable current regulator is available. This is particularly advantageous for applications in the processing industry. Thanks to a protection class of IP65, the MHJ10 compact, rapid response valves are not sensitive to dust and humidity and can be mounted directly on the application without protective measures. The MHJ9 valves have a plug connector of protection class IP40.
Everything is visible
At such extreme speeds it is almost impossible to detect the cause of a fault in a motion sequence. So-called high-speed cameras can provide the answer during commissioning and service, or even during operation, however these are generally very expensive. One economical alternative is the SBOC-M/SBOI-M intelligent vision system. This supports both diagnostics and commissioning, as well as function monitoring with an extremely high scanning rate of up to 2,000 images per second. The complete electronic system for recording and storing motion sequences is already integrated in the camera – it needs to be set up via a PC and then operates completely automatically. When played back in slow motion, the high speed compact vision system shows the sorting process on a monitor and thus enables the process to be diagnosed and corrected. This ensures process security – ultimately all parts are sorted with perfect results.
Much more than just pea counting
Quality assurance is the main concern when considering sorting systems for peas. Whether fresh, dried or frozen, thousands of peas are spread over the patented free-fall chute via a feed shaker. Lasers scan the peas for similar colour, shape and structure as they fall towards the inspection zone at a speed of 3 metres per second. Peas that are lighter, darker or bruised are hit via air guns a few milliseconds later and ejected from the falling mass. MHJ jet valves from Festo are packed tightly together on the free-fall chute, ensuring that imperfect produce is removed in a fraction of a second. Subsequently, only the best make it to the canning or bottling plant!