When a local Original Equipment Manufacturer (OEM) of concrete brick, block, and paving machinery had the unique opportunity to build a greenfield plant for a longstanding customer in the East London area, it turned to SEW-Eurodrive for its easily configurable HandlingKinematics pick-and-place solution.
The HandlingKinematics application module allows for machine control at a higher level by means of a lower level Configurable Control Unit (CCU) for carrying out precision path movements. During startup, all the end-user is required to do is enter the relevant mechanical data for the initial configuration of the motion parameters.
During production, the trajectory positions necessary for commencing movement are simply transferred to the CCU, which coordinates the path movement in real time. It even allows for ‘wait’ points to be defined in the trajectory. The system is so flexible that, during palletising and stacking, the target position can be adapted immediately during the runtime by the CCU, without higher level controller intervention.
Even greater flexibility can be allowed for by incorporating the freely-programmable MOVI-PLC in the HandlingKinematics application module. This provides for exactly the same functionality and completely repeatable configuration. While the hardware is the same, the only extra element needed is a different memory card for the programmable MultiMotion software, which ensures unlimited consistency.
MAXOLUTION engineer, Dylan Enslin explains that the pick-and-place solution from SEW-Eurodrive is essential for bricks or concrete blocks to be palletised in cube-sized packages for easy transport. Bricks or blocks are manufactured, compacted on a vibrating screen, placed on steel or wooden boards, and stacked in a curing chamber for three days, during which time a high humidity is maintained to crystallise the cement.
Thereafter a destacker feeds the boards onto a conveyor belt, which is where the pick-and-place application comes into play. Shaving even a single second from this process can translate into a massive increase in the daily production rate. The actual pick-and-place machine itself is robotic, which is not supplied by SEW-Eurodrive as an off-the-shelf unit. Instead, it supplies a retrofit kit that includes geared motors, cables, inverter, variable speed drives and the software.
Pick-and-place robotics is based on kinematics, a mathematical model used to control and coordinate multiple axes. The machine developed by the OEM is essentially an automated gantry system, with an upper level controller to send the relevant coordinate data. The distance involved during the pick-and-place process is about 4 m, with a 2 m to 3 m lift. The rotation and clamping of the gripper is controlled by a combination of pneumatics and servo motors.
SEW-Eurodrive has been working intensively with the OEM for about two years to refine its latest upgraded equipment. A specific recommendation, for example, was to use a combination of high-flex and standard cabling, as the cabling is subjected to a lot of bending. This saves on costs, as well as increasing the durability of the system. Other factors that had to be taken into account were the motor mountings, as the oil levels had to be correct and all the necessary oil seals in place.
“From the initial designs, we actually ended up with a unit smaller than envisaged initially, due to us refining the calculations provided by the client. The smaller the unit, the more cost-effective it is,” Enslin explains. Such has been the close working relationship established with the OEM that SEW-Eurodrive has already collaborated on an improved vibrating screen.
“There are global companies manufacturing similar equipment, but it wanted to design and build its own unique version compatible with local operating conditions and requirements. A standout feature of the OEM’s equipment is the application of servo technology. The fact that we have been able to supply it with the latest advances in this field positions us firmly as a complete solutions provider for our customers in a range of industries,” Enslin concludes.
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