New revolutionized space-saving grading-technology enables automated carton-filling of fixed weight cartons.

Prototype of an IES system: Pneumatic elements for intermediate storage of products

In the beginning of 2004 “Liebel Weighing and Grading Technologies” registered a patent for a new and revolutionary grading mechanism. With the help of this new and extremely space-saving technology it is possible to equalize products of different weights (through a process of combination weighing) to a carton which has a fixed standard weight. Because of the requirements of modern automated packaging machines the equalizing process is carried out in one continuous line, without the need of depositing each weight-batch in a different channel. The first prototype was delivered to one of our clients in the middle of 2004. In the meantime Liebel works intensively to increase the throughput performance with the ultimate goal to eventually arrive at 120 to 140 n/min. This is the current level reached by automated price labelling machines which are commonly installed previous to an IES system.

Classical Equalizing Systems

Equalizing (to create uniformity) or combination weighing (to find the optimum weight combinations) are words used in reference to the packing of sliced products like sliced cold meats, cheese etc. Equalizing describes the process of creating fixed-weight batches using products with different individual weights. These products are commonly cut by a slicing machine and price-labelled individually according to their exact weight. After the labelling process they need to be packed into cartons which have a uniform fixed weight.

A classical Liebel Universal-Equalizing-System (UES) is usually connected per data-link to a previous prize labelling machine. It does not require a separate weighing unit with load cell, because this is already included in the price-labelling mechanics of the price-labeller. All product weights are being transmitted from the price labelling machine to the UES machine and computed within the operating system of the UES. The decision into which channel the product should be located is instant (real time). Usually one channel is being filled to the level of reaching an arithmetically critical value. The rest of the products are only sorted into the first channel, if their weight corresponds to the weight needed in order to arrive at the appropriate target weight of the channel. If this is not the case, the next channel (channel 2) will be filled (up to its arithmetically critical value). If cartons are being packed manually, a signal notifies the operator “when a channel has reached its target weight”. Only after verifying that the channel has been emptied, can the channel start to be filled again.
A UES machine consists of an operating unit with a belt-bridge which leads over from the price-labelling machine to the sorting system with 4, 6, 8 or 12 channels with pushers or flaps depending on the type of products to be equalized. Products are being sorted into appropriate channels. These can vary from a packing table with simple containers to bag-filling devices or roller-conveyers for sensitive products. Most grading machines on the market use a very similar build-up to the above described system, whereby mathematical algorithms may vary.

IES – Integrated Equalizing System - a description of its concept
The difference between the IES and classical systems can briefly be described by the following points:

• Products are being delivered lengthwise
• Products for one equalized carton (with fixed weight) are being delivered in one whole string (sequence)
• An automatic storage of products which cannot be used – for later usage
• A new type of mathematical algorithm which combines the classical calculation (which uses the “mathematically critical value”) with a new form of “combination approach calculation”.
• Extremely compact measurements

In order to construct the IES a new conveyer- and ejection-system, as well as new software were used.