What are the differences between three-axis manipulator and five-axis servo manipulator in installation and debugging?

Although the three-axis injection manipulator and the five-axis servo manipulator belong to the matching automation equipment of injection molding machine, there are essential differences in the driving mode, structural form and freedom of movement of their moving axes, and there are obvious differences in the previous installation conditions, on-site construction, debugging process, personnel capacity, trial production verification and other links, and the requirements for workshops and construction personnel are different.

In terms of basic installation conditions, the three-axis manipulator is mostly a side-hanging structure, and the main body is mounted on the body of the injection molding machine, which only relies on the body of the injection molding machine as a support. There is basically no additional requirement for the bearing capacity of the steel structure and beam at the top of the factory building, just make sure that the body of the injection molding machine is stable. The installation space is concentrated in front of the injection molding machine, so the equipment has light weight, simple hoisting, short time-consuming for a single equipment to enter the site, and no complicated top load-bearing checking calculation is needed. However, most of the five-axis servo tauren manipulators adopt the overhead tauren beam structure, and the beam is erected above the injection molding machine. Before installation, it is necessary to check the bearing capacity of the steel beam at the top of the factory building and the frame of the injection molding machine to confirm the strength of the hoisting point. Some old workshops also need to strengthen the steel structure to prevent vibration and deformation caused by long-term operation. The overall weight of the five-axis manipulator is larger, and the lifting operation requires higher requirements. When the manipulator enters the site, the installation tolerance control of levelness and beam parallelism is much stricter than that of the three-axis manipulator, and it also requires higher site space layout. It is necessary to reserve enough space for overturning and rotating actions to avoid interference between fixtures, products and surrounding molds and auxiliary machines.

In the stage of mechanical assembly and positioning debugging, the three-axis manipulator only has three linear motion axes, namely X, Y and Z, which are responsible for moving back and forth, up and down, left and right, respectively, without rotating and turning joints. Mechanical positioning only needs to calibrate the three-axis origin limit switch and hard limit switch, and adjust the level and travel limit. The assembly focuses on the parallelism of the guide rail and the tightness of the belt or rack, with few mechanical positioning parameters and simple calibration items. Debuggers only need to ensure the accuracy of the picking position and feeding position of the manipulator, and after the mechanical calibration is completed, there will be basically no attitude deviation problem. In addition to the X, Y and Z linear axes, the five-axis servo manipulator is additionally provided with the A-axis rotating and B-axis overturning servo axes. During mechanical assembly, not only the three-axis linear guide rail should be calibrated, but also the concentricity of the rotating joint, the clearance of the reducer and the verticality of fixture installation should be finely adjusted. The mechanical clearance of the rotating shaft will directly affect the turnover accuracy of the product, so it is necessary to eliminate the back clearance during assembly and debugging to avoid the jitter and angle deviation when the parts are turned over. The number and accuracy requirements of calibration items in mechanical assembly are significantly higher than those of the three-axis manipulator.

In terms of electrical wiring and hardware configuration debugging, the three-axis manipulator is mostly driven by single servo with cylinder, and only the main upper and lower shafts adopt servo, and the rest shafts rely on cylinder action, so there are few electrical lines. The solenoid valve and gas pipe line are the key points of wiring, and the air source pressure and cylinder throttle valve adjustment are the core. Electrical debugging mainly confirms the interaction of limit signal, safety door signal and mold opening signal of injection molding machine. The number of IO points is small, the communication logic is simple, and the wiring and power-on debugging speed is fast. All five axes of the five-axis full servo manipulator are driven by servo motors. There are a large number of servo drivers in the electrical cabinet, and the layout requirements of encoder cables, power cables and shielded wires are strict. It is necessary to do anti-interference treatment to prevent the workshop inverter and injection molding machine from generating electromagnetic interference and losing pulses. When wiring, it is necessary to distinguish the encoder circuit of each servo shaft, and to configure multi-axis synchronous signals, so that there are more communication and interaction points with the injection molding machine. In addition to the basic mold opening signal, it is also necessary to support multi-segment signal linkage to meet the complex actions such as embedded parts, gate cutting and visual linkage. During power-on debugging, it is necessary to do origin regression, electronic gear and servo gain adjustment one by one, and adjust the speed and acceleration parameters of each axis to suppress start-stop impact and jitter. The workload of electrical debugging is much larger than that of three-axis models.

The gap between programming and on-site teaching and debugging is the most prominent. Three-axis manipulator only needs to teach a few key points: standby position, picking position and material level. The motion trajectory is simple and straight, the program logic is simple, and the action sequence is fixed. It can only complete basic operations such as picking, translating and placing. The teaching program can be written in a few minutes, and ordinary technicians can start debugging after short-term training. When changing products, only a few point coordinates need to be fine-tuned. In addition to the basic points, the five-axis servo manipulator also needs to teach the rotation and overturning posture, which can adjust the product angle in real time during the movement. The trajectory supports curve movement and multi-axis synchronous linkage, and can complete the processes such as turning over, lateral placement and embedded parts placement after taking the parts. When teaching, it is necessary to take into account the attitude angle, the timing of fixture opening and closing, the interference avoidance between product attitude and peripheral equipment. The program contains multi-branch logic, can set multiple sets of mold changing formulas, and supports the linkage of vision, gate shearing, conveyor belt and other peripherals. Program debugging requires debugging personnel to have knowledge of multi-axis motion control, master servo gain and optimization of acceleration and deceleration curves, eliminate vibration during high-speed flipping, and the debugging period is longer, which requires higher technical level of debugging engineers.

In the safety debugging and trial production verification, the safety logic of the three-axis manipulator is simple, and the hard limit and safety door interlock are the core verification items. In the trial production stage, it is important to check whether the parts are dropped or hit the mold, with fewer consecutive empty runs and short trial production verification period. Due to the addition of the rotating shaft, the safety verification items of the five-axis manipulator are greatly increased. In addition to the conventional limit, it is necessary to set the soft limit and attitude interference area of the rotating shaft to prevent the product from hitting the mold, conveyor belt and peripheral auxiliary machines during the overturning process. In the trial production stage, it is necessary not only to verify the stability of picking, but also to repeatedly verify the flip attitude and product placement accuracy, and to check whether there is jitter and positioning deviation under high-speed movement. It takes a long time to continuously run empty and trial production with materials, and gradually optimize the servo parameters to ensure the stability of mass production.

Finally, from the perspective of later debugging and maintenance, the three-axis manipulator is simple in structure, easy to troubleshoot, and fast in later mold changing and debugging, which is suitable for the scene of single product and simple picking. There are many parameters of the five-axis servo manipulator, and the servo gain, origin offset and reducer clearance will all affect the finished product effect. Although the later modification debugging is flexible, it needs professional engineers to check the abnormal posture and jitter problems, which puts higher demands on the technical ability of workshop maintenance personnel.

By comprehensive comparison, the three-axis manipulator has low installation and debugging threshold, short cycle and simple personnel requirements, and is only suitable for basic injection molding automation that only takes and puts products. Five-axis servo manipulator needs load-bearing checking calculation in the early stage of installation, with many mechanical, electrical, teaching and debugging items, high technical threshold and longer debugging period, but it can realize complex posture movements and adapt to precision injection molding production with post-mold process.