Pistons are a product requiring mass production, and the entire production process involves surface treatment, turning, boring, and milling. Between these processes, pistons need to be transported from one machine tool to another for processing, finished parts need to be transported for surface treatment, and qualified products need to be packed and shipped. The workload of piston transfer between these processes is very large. Some processes, even with automated loading and unloading, only take 8 seconds, but the labor intensity is high, and manual loading is inefficient and prone to quality problems (improper piston assembly). Manual unloading can sometimes damage the piston surface. Therefore, some piston manufacturers use palletizing robots manufactured by the German company Pegra to complete these tasks, which not only improves work efficiency and output but also enhances product quality and economic benefits. As an example, this article introduces the Pegra MS600 standard palletizing robot used by FederalMogul in Nuremberg, Germany.
I. Composition of MS600
The MS600 mainly consists of a feeding mechanism, a unloading mechanism, a pallet handling mechanism, and a two-dimensional handling robot. The MS600 palletizing robot completes a part loading and unloading process every 8 seconds and a pallet exchange every 7 seconds, demonstrating its high efficiency. Its main components are described below.
1. Material supply organization
The feeding mechanism consists of a manual trolley and a pallet lifting unit. The trolley holds 12 steel mesh baskets filled with pistons, which are stably positioned on the trolley by working in a coordinated manner. The baskets are stable and secure during manual transport. Each basket measures 545 × 310 × 95 mm (length × width × height) and has 15 compartments, each holding a piston weighing approximately 350 grams. A trolley holds a total of 180 pistons, with a total weight of approximately 63 kg. During operation, the operator pushes the trolley into the MS600's feeding track, positioning it against a specific position sensor. Once all pistons on the feeding trolley have been processed, the pistons and 12 steel mesh baskets are transported to the unloading mechanism. The empty trolley is then manually pushed out, and a trolley filled with pistons is pushed into the feeding track.
2. Feeding mechanism
The unloading mechanism is exactly the same as the loading mechanism, but when manually pushed into the MS600's feeding track, it is empty, without pushers or pistons. After all the pistons on a pallet of the feeding mechanism have been processed and returned to their original positions, the pallet is placed on the unloading trolley. After all the pistons in the 12 pallets have been processed and placed on the unloading trolley, it must be manually pushed out and sent away, and then an empty trolley is pushed into the unloading track.
3-pallet handling mechanism
The pallet handling mechanism consists of two pallet lifting shafts and a pallet horizontal transport shaft. The pallet lifting shafts are vertical motion shafts composed of two PAS42BB motors connected in parallel, driving the lifting and lowering of 12 pallets. The pallet horizontal transport shaft is a horizontal motion shaft composed of two PAS42BB motors connected in parallel. All three motion shafts are controlled by servo motors.
4 Two-dimensional transport robot
Because FederalMogul uses vertical CNC lathes, BioGla employed a 2D XZ robot. The X-axis uses a PAS42BB, and the Z-axis uses an LM-A101. To facilitate gripping the piston, BioGla designed a four-fingered gripper with auxiliary positioning. The XZ robot has an X-axis travel of 1.2m and a Z-axis travel of 0.4m, with a maximum X-axis speed of 2m/s and a maximum Z-axis speed of 1m/s.
II. MS600 Working Process
The feeding and unloading mechanisms share the same pallet lifting mechanism. After the feeding trolley is pushed into the track, the pallet lifting mechanism pulls up all the pallets starting from the bottom, lifting the entire stack of pallets by one pallet thickness each time, ensuring that the top pallet can be supported and moved horizontally by the pallet horizontal movement mechanism. During operation, the pallet lifting mechanism raises the top pallet to a certain height above the horizontal movement axis and then stops. The pallet horizontal movement mechanism then moves towards the first pallet, positioning its accompanying pallet below it. The lifting mechanism then lowers, placing the first pallet on the horizontal movement mechanism's pallet. The lifting mechanism then raises it 10mm, and the horizontal movement mechanism moves back, bringing the pallet to the XZ 2D robot arm. The XZ 2D robot arm first handles the first row of parts one by one, processing them before returning them to their original position. After one row of parts has been processed, the horizontal movement axis moves forward, placing the second row of parts in a position that the robot arm can grasp. This process continues until all parts on the last row have been processed. After the last row of parts has been processed, the horizontal motion axis returns the pallet to the lifting mechanism of the unloading mechanism. The lifting mechanism then lowers by the height of one pallet, awaiting the next pallet. At this point, the feeding mechanism rises, and the horizontal motion mechanism removes the next pallet. This is the pallet exchange process. After the pallet exchange is complete, the parts on the next pallet are processed, and so on, until all parts on the last pallet have been processed.
III. Control System Section
The entire robot control system adopts the TLCCCAN bus control system from BioGlare, controlling the movement of each axis via CANbus. Each axis is driven by a TLC534 servo motor drive system with CANbus control functionality. The TLCC acts as the master station, controlling dozens of slave stations (TLC534) via the CAN bus, with a control cycle of 10ms. Each axis is equipped with a PLE series precision planetary gearbox from Neugart, Germany. The entire system uses five PLE series precision planetary gearboxes and five programmable intelligent servo drive systems (TLC534) with motion control functions.
IV. Outlook
This article introduces the application of palletizing robot systems in piston production lines. Pegra also provides similar feeding and unloading robot systems for machining equipment such as turning, milling, grinding, and boring machines for many types of parts. These palletizing robot systems mainly consist of Cartesian coordinate robots. Their main characteristics are simplicity, ease of understanding, ease of control, practicality, low cost, and high efficiency. They are widely used in the production of cosmetics, food, mobile phones, sensors, toys, and instruments in Europe and America. We hope this introduction to one type of palletizing robot structure will help users understand and adopt them. We also have more than 10 other structures of feeding, unloading, and palletizing robot systems. Pegra has produced thousands of similar robots over the past twenty years.
