In the production process of many products, the use of robots to complete some of the production process, not only can improve production efficiency, reduce costs, but also improve product quality. For example, in the ESTEE LAUDER lipstick production process, to lipstick and shell from the tray out, and then the lipstick neatly and accurately loaded into the shell, and cover the lid and tighten, and finally put the finished lipstick into another tray. There are also in many cell phone production process, in a tray neatly placed on a number of cell phone shells, printed circuit boards, packaged in plastic bags display parts. The robot claws grab them one by one onto a conveyor belt for the next step in the process, and at the end move the already empty pallets onto an empty pallet stack. This type of palletizing robots are widely used in many industries such as pharmaceuticals, packaging, instrument assembly, relay production, etc. Since their structures and working principles are very similar and they are all based on Cartesian Coordinate Robots, this paper first introduces Cartesian Coordinate Robots and then Standard Palletizing Robots and an application case.

First, Cartesian Coordinate Robot

A Cartesian Coordinate Robot consists of several linear axes, usually corresponding to the X-axis, Y-axis and Z-axis in the Cartesian Coordinate System. In most cases, the angle between the linear axes of a Cartesian Coordinate Robot is a right angle, usually the X-axis and Y-axis are the horizontal axis of motion, and the Z-axis is the up and down axis of motion. The core component of a Cartesian Coordinate Robot is the linear motion axis, which is composed of refined aluminum profiles, toothed belts, linear motion guides and servo motors. The standard maximum stroke of single motion axis is 5600mm, load 1~200kg, positioning accuracy 0.05mm, and the highest motion speed 8m/sec. According to the specific application of positioning accuracy, effective stroke, running speed and load size, movement mode, etc. to select the appropriate guide, and combined into the corresponding form of multi-dimensional robot to complete a specific task. According to its structure, there are more than 30 kinds of two-dimensional and three-dimensional robots, but also in the Z-axis plus one or two rotary axis, constituting four-dimensional and five-dimensional robots. Multiple Cartesian Coordinate robots are constructed in specific combinations to synchronize specific tasks. Palletizing robots are the most common combination, and there are many standard forms of palletizing robots for different applications.

Two palletizing robots structure The German company BAGRA has formed some standardized series of palletizing robots in 20 years of application. These robots are mainly used for handling, processing and transferring large quantities of workpieces in automated production processes. Each palletizing robot has two or three stacks of pallets, the number and size of pallets in each stack varying according to the application. The following is an example of a WMS-type robot, which is analyzed and described below.

In Figure 1, the top pallet in stack A is lifted and moved to a horizontal position, where the loading or unloading positions of the pallets and components can be freely programmed, and the workpieces in one pallet are returned to their original position after handling, or of course to another position. The schematic working process is described below. First, a stack of pallets is brought to position A by means of a conveyor belt or a cart, which holds the workpieces to be processed. Through the workpiece to make the A stack of pallets precise positioning, the hand claw (Gripper) in the guide rail Y axis driven down to the top of the towing tray position, the hand claw together to grasp the towing tray, and then raised to a fixed height and then stop. At this time, another 2-dimensional XZ-axis robot handles the workpieces in the pallet. Usually, the workpiece is taken out to another working position for further processing, and then put back to the original position in the pallet after processing. After the entire pallet has been processed, the X-axis of the guideway moves to send the processed pallet to the B-stack pallet position, drops down, releases the top of the B-stack pallet, and then returns to grab the next pallet to be processed from the A-stack pallet. From the first tray is processed, and then sent to the B, return, and then to the A to grab the second tray to be processed, up to the position of its processing can be done, this process is the towing tray exchange process, time to be less than 10 seconds. The whole process can be set on the guide rail X-axis, Y-axis running speed, acceleration, reduce the guide rail X-axis, Y-axis running time, in order to improve efficiency, while also installing the conveyor belt along the guide rail X-direction, composed of the assembly line mode, thereby greatly improving production efficiency. The two-dimensional robot supporting Figure 1 consists of an X-axis and a Z-axis, referred to as the XZ robot. In the work of XZ robot, the X-axis of the palletizing robot has to cooperate with its work. the XZ robot can only grasp one or several rows of workpieces, and every time it finishes grasping one or several rows of workpieces, the X-axis of the palletizing robot has to be moved, so that the XZ robot can only grasp another row or several rows of workpieces. This is repeated until the entire pallet is gripped.