Durable and economical bearings for format adjustment in tray inserter

Profile

• What was needed: drylin R linear bearings, drylin SHT linear systems with liners made of iglidur J, drylin NEMA stepper motors with dryve D1 control system
• Requirements: Both for de-nesting and fleece cutting as well as for nesting, format adjustment is necessary for every tray. To achieve this, the machine manufacturer needs safe, durable and cost-effective automation solutions.
• Industry: Packaging industry
• Success for the customer: The drylin linear bearings are lubrication-free, highly wear-resistant and cost-effective. In our drylin SHT modular linear system, the customer can freely select from a large variety of different lead screws, materials and slides.

The absorbent pad insertion machine quickly fits out plastic trays with absorbent pads.

Problem

Plastic trays are the most common solution in supermarkets for the cost-effective storage of meat, fish, fruit and vegetables so that they remain fresh. In approximately 50% of plastic trays, there are so-called absorption pads that protect the product against pressure and absorb and bind any fruit juice that occurs (see Fig. 1 below).
In 2005, LAD GmbH developed an absorbent pad insertion machine which ensures that the pads are cut to the right size and placed in the packaging so that they cannot slide about; this machine is now sold worldwide. The system is fast and efficient, whereby one machine can make up 100,000 trays in eight hours.
The absorption pad insertion machine is designed for operation by one worker and is built in a U shape so that the working distances are short. But how is an absorbent pad placed in a tray in the shortest of times?
First, the employee must fill a rack with the trays. From there, the trays are transferred into the automated system, where they are "de-nested", i.e. separated, the fleece is cut to size, then inserted and welded or glued in place with the aid of a two-point ultrasonic technique. Afterwards, a quality check based on camera technology is carried out. If the tray passes the check, it is "nested" again, i.e. the trays are stacked inside each other, after which they are ejected. The employee can now remove and pack the stacked trays. In just one minute, 200 trays can be made up.
However, as there are many different packaging sizes on the market, it must be possible to easily reconfigure the machines at least once a day. Both for de-nesting and fleece cutting as well as for nesting, format adjustment is necessary for every tray. To achieve this, the machine manufacturer needs safe, durable and cost-effective automation solutions.

Solution

LAD GmbH can freely select from a large variety of different lead screws, materials and sliders from the modular drylin SHT linear systems kit. They can be individually configured online in the free drylin SHT designer. The SHT linear modules enable completely lubrication-free and maintenance-free movement with a high degree of precision.

Adjustment of the tray rack
At the beginning of the process, classical plain bearing technology comes into play in the system. To adapt the rack for the trays, drylin R bearings made of iglidur J are used. They provide lubrication-free bearing support on the stainless steel shaft.

De-nesting of the absorption pads
A drylin SHT linear system made of hard-anodized aluminium with a reverse lead screw is used for adjustment of the de-nester's format (Fig. 2). This is easy to adjust by means of a hand wheel. The carriages of the linear system move over liners made of iglidur J tribo-polymers, which are lubrication-free and highly wear-resistant.

Format adjustment of the absorption pads
We also offer cost-effective solutions for lighter tasks such as adjustment of the absorption pad width. A durable and attractively priced linear bearing is used: The drylin SHT module as a low-cost variant made of plastic (Fig. 3).

Nesting and ejection of the plastic trays
A special solution was needed for vertical stacking and automatic ejection of the stacked trays: Two SHT linear modules made of aluminium that are connected via a toothed belt are used for this today. The ejection pusher is driven by drylin NEMA stepper motors (Fig. 4), while the dryve D1 enables simple, cost-effective control (Fig. 5). The control system is suitable for all stepper, DC and EC/BLDC motors and can be operated without software and without an Internet connection via the web browser from a PC, smartphone or tablet without an Internet connection.

Fig. 1: The machine can fit out 100,000 plastic trays with the fleece within eight hours.

Fig. 2: drylin SHT linear modules running in opposite directions are used for adjustment of the formats of the absorption pad insertion machines.

Fig. 3: As a low-cost variant made of plastic, the linear system is also suitable for adjustment of the absorption pad fleece.

Fig. 4: Two synchronized drylin SHT linear modules enable vertical nesting and automatic ejection of the plastic trays. They are driven by NEMA stepper motors.

Fig. 5: For linear axis control of the de-nesting and ejection unit, the engineers rely on the intuitive and cost-effective dryve D1 control system.