For a long while, strap hinge conveyors have been indispensable in chipping, not to mention punching and shaping technology. They transport wet and dry chips as well as bulk material and small parts – usually efficiently and economically. Yet the smallest parts from thin sheet metal pieces and fine, hard chips or hot applications such as laser cutting test the design-related limits of the strap hinge conveyors.
This is why KNOLL Maschinenbau of Bad Saulgau, one of the leading suppliers of systems for conveying and filtering chips and cooling lubricants in the metal machining industry, has developed a new conveyor belt that is especially robust and easy to service and suitable for a significantly broader field of applications.
The new KNOLL slat belt conveyor distinguishes itself from classic strap hinge conveyors through various design features. The most important: the profiled plates have no closed joint that connects them to one another. They touch only due to line contact, which keeps joint friction to a minimum. For this, the chain – a hollow pin chain as for the strap hinge – fulfills the function of the plate joint in addition to performing its task as traction mechanism.
For consoles are joined with the chain, which on the one hand form the side rims and on the other hand serve as support for the plate elements with which they are connected form- and force-fit. In comparison to the previous KNOLL strap hinge conveyors, the side rims are higher and they are arranged standing in a row. A labyrinth seal and if necessary brush bars arranged above and below protect the chain against soiling.
The plate elements feature a continuous profile produced using a roll forming method. On the one hand, the contour created this way has great bending stiffness. Thus, the slat belt absorbs a 100 kg load on a 1 m wide section of belt and can be walked on without any supports. On the other hand, the contour of the plates prevents any gap formation against the running direction.
And another effect: the profile with pronounced plate cavities combined with the side rims standing in a row allows the controlled transport of small parts. They always lie in the cavities, they cannot get jammed and block the drive.
For the development of the slat belt conveyor, KNOLL paid great attention to ease of service. The detachable screw fixture of the belt plates makes an important contribution to this, They are connected to the consoles via thermal screws. These shape their own thread and, due to their minimally non-round shape, offer an extremely tight screw connection, which is quite important for the operation of the slat belt that is subjected to a high vibrational load.
In case of any damage to individual plates, they can be replaced easily and quickly without any additional reconstruction measures. If no thermal screw is available, a "normal" screw with M6 thread can be used.
The KNOLL slat belt conveyor has a modular design. Even other elements can be replaced without any issues. It is even possible to retrofit existing KNOLL strap hinge conveyors to the plate system, however without the new side rim and labyrinth seals.
With its sophisticated design details, the new KNOLL slat belt conveyor can be used in many application cases for which the strap hinge conveyor would not be suitable or not ideal. In chipping, for example, machines with greater and greater capacity are being used; these perform turning and milling tasks and therefore produce different-sized chips. While previously a strap hinge conveyor was used for long chips and a scraper belt conveyor for short ones, the slat belt conveyor can handle both tasks. For even fine, hard chips are no problem for it. The new side rims ensure this; they are protected with labyrinth covers, etc. to guarantee protection of the traction mechanism. The fact that there are no slits and due to the line movement no closed joints that can become soiled or blocked also make it suitable for this use. Perforated plates can be used for wet processing so that the belt functions as a of pre-filter and (only) lets the cooling lubricant pass through.
These properties are also welcome in sheet metal processing. Thus even small parts that are punched, nibbled or cut out of 0.5 mm thin sheet metal can be conveyed without problems and without a fear of jamming.
The KNOLL slat belt conveyor even presents significant advantages for hot applications. For the overall system is not sensitive to heat input since the plates can expand and contract independent of one another without having the belt tense up. Due to the new joint construction with just one line movement of the plates, the system is not sensitive even to tough soiling (e.g. slag).
Many different experiments with punch-nibbling, laser, turning and milling machines have already proven that these advantages apply not just in theory but in practice. KNOLL has placed numerous slat belt conveyors in service in the course of the last three years – at customers and in its own production, where, for example, in cast processing, short, abrasive chips must be disposed of. Here the side rim is combined with brushes and even after several weeks of running time, no wear could be determined on the side rims.
KNOLL is putting the new slat belt conveyors on the market in sizes P40 and P63. The description corresponds to the division of the chain. The customer can choose the width of the conveyor, that is, the plate length, at will.