Over a certain work piece volume or if the operation of the work requires so, machine-driven material moving systems serve the operation more efficiently. There are several opportunities for machine-driven material moving available depending on the needs, manufacturing processes and the given designs of the equipment in place. Machine-driven conveyors and elevator cranes can be of lower or upper line types. Within that range, a machine-driven conveyor can be of single line or of double (P&F) system. There exist auxiliary machine systems of individual design (auxiliary chains) which can provide the machine-operation of certain sections (e.g. powder blast cabinets) of manual systems. Machine-driven conveyors, similarly to manual ones can be suspended on the equipment or steel separately standing support legs. It can also be provided, if the conditions of the building allow it, to load the conveyors on the supporting structure of the building itself. For that however, the involvement of a static engineer is essential.
The certain machine-driven systems are described in the following:
The single line (monorail) conveyors are service units of automatic systems. The conveyor consists of an endless track of rail, in which the conveyor chain of preset speed runs. The chain can be of several designs and layout which are always selected according to the subject work task and loading data. The conveyor line is also designed in accordance with the given loading data. The work pieces or the beams holding the work pieces are directly suspended on the chain (with tabs or bores created accordingly). The line can be implemented with any tracks thanks to the straight and horizontal-vertical eaves. The monorail line cannot be detached but only one track can be in place, therefore, the subject equipment need to be “beaded” one by one on the line. For the parallel service of several work stations with the same conveyor, a Power and Free (P&F) conveyor is needed. The machine-driven monorail conveyor provides the cheapest service for automatic systems.
A normal single line conveyor may consist of the following main and auxiliary units:
- Straight conveyor line element
- Horizontal, vertical eaves
- Load bearing roller type of chain structure in various designs and layout
- Conveyor drive with motor
- Oiling unit
- Conveyor chain tensioner section
- Frequency converter for speed adjustment
- Control cabinet and control system
- Support steel structure
- Work piece support beam
Power&Free conveyor system
The P&F material moving system is a special branch of material handling. It is a solution mainly used for connecting parallel running work stations and for complicated material handling tasks. With the P&F system, even two separate conveyors can be connected if they need to be running through some common equipment necessary for both of them. In the same method, the system can connect even a manual and a machine-driven system. In such case, the conveyor is of double line. The chain continuously runs on the upper line with the load bearing elements, while on the lower line, the support beam of the work pieces is placed. The design of the beam is such that it engages the chain above and gets to any position along the line. Stop sections can be installed at several points along the line. At those points, the work pieces gets disengaged from the chain and does not move forward as long as it waits I the stop section. The work pieces arriving behind it in a sequence will also get disengaged from the chain and accumulate. Since the conveyor chain runs the line continuously and with high speed, the time for moving the work pieces between the units significantly drops. The stop sections also allow the work pieces to be processed and treated etc. at their standstill position. P&F systems are therefore highly needed if the idea is to provide machine-driven material handling to stations of manual processing and treatment or if it is to connect separate automatic systems. The system is PLC--controlled. The line is equipped with sensors at various positions which help forward the work pieces support beams to the appropriate direction, making them stop, letting the move on etc. The beams can be designed so that certain beams are only allowed to move in one, while other types are only allowed in another direction by the PLC upon reaching the relevant switch points.
A P&F machine-driven conveyor system may consist of the following main and auxiliary units:
- Straight conveyor line elements (chain and load track separated)
- Horizontal, vertical eaves (chain and load track separated)
- Load taking type of roller chain in various designs and layout
- Conveyor drive mechanism with motor
- Oiling device
- Conveyor chain tensioner section
- Frequency converter for speed adjustment
- Control cabinet and PLC control and sensors
- Supporting steel structure
- P&F work piece support beam
- Line section switches
- Stop points
Elevator cranes, chain elevators
Elevator cranes are automatic service units of tub type pre-treatment equipment and tub type of KTL painting equipment. The cranes place the baskets and racks in the appropriate tubs based on a pre-written program. Based on the prescribed technology process and technology times a way-time diagram can be defined, based on which it can be calculated if the given task is feasible with only one crane or more. The more cranes work at a tub type of system the more the section time can be decreased, that is the number of racks to be supplied from the line. Obviously, there is still an ideal number, over which it is not work running since not any further decrease can be reached. In such case, further decrease can be reached by increasing the number of the individual points of treatment. Moving of the cranes is provided by elevator and run type motors which are brake-equipped and their cycle can be modified by a frequency converter in place. That way, the crane can run, or the racks can be lowered and lifted at the adjustable speed as prescribed by the program. Each crane can be of both lower and upper line type. In case of long-rack racks and baskets (or at high work load), it is recommended to install a lower line system. In that case the crane is not suspended but is seated and runs on a lower line.
In smaller tub type of systems chain elevators are applied which vary from the completely manual version (manual progress and lowering/lifting movement) to the fully mechanical versions. The installation of such system is mainly recommended with smaller volumes, lower work load and simpler technology lines to be supplied.
An elevator crane main consist of the following main and auxiliary units:
- Crane structure, steel structure
- Lift and progress motors
- Crane runway
- Crane and crane runway support steel structure
- Crane climbing cable conduit elements
- PLC control, crane programs, manual mode
- Work piece holder baskets, racks
In case of manual material handling systems, it is possible to install auxiliary chain operated handling equipment for the supply of certain phases of the work. Auxiliary chain can be applied e.g. at powder spraying cabinets for automatic spraying or in the furnace and at pre-treatment cabinets for drawing in and discharge of the work pieces. The auxiliary chain commences and stops by pressing a button but obviously, it can be automated wherever such function is needed. The auxiliary chain forwards the work piece holder carriages or beams with the help of an endless claw chain. The racks are pushed to the auxiliary chain manually which gets engaged with the claws of the chain. At the end of the process where the chain returns, the claw simply pushes the work piece holder carriages or beams out of the auxiliary chain. The auxiliary chain is equipped with a small drive and a framework structure (with chain guides) as well as a frequency converter, by which the chain speed can be adjusted. The control of the auxiliary chain is generally integrated n that control board where the auxiliary chain was installed.
An auxiliary-chain elevator unit may consist of the following main and auxiliary units:
- Chain control
- Claw chain
- Auxiliary chain framework
- Chain wheels
- Drive and its holder
- Tensioner section
- Frequency regulator (for seed adjustment)