Three-axis servo manipulator: structural difference and selection guide between single-arm and double-arm

In the field of injection molding automation production, the three-axis servo manipulator has become the mainstream automatic equipment for picking parts by virtue of its advantages of stable operation, accurate positioning and wide adaptability. Many enterprises often confuse single-arm manipulator with double-arm manipulator when selecting equipment. There are obvious differences between the two models in structural design, operational performance, applicable scenarios and production costs. Improper selection will not only affect the production rhythm, but also cause space waste, equipment redundancy or insufficient production capacity. In order to help major production enterprises accurately select and adapt to workshop production conditions, the core differences, performance characteristics and applicable scenarios of three-axis servo manipulator with single arm and double arms are analyzed in detail.

Firstly, the single-joint arm and the double-joint arm are distinguished from the telescopic structure, which is the core factor to determine the stroke and height adaptability of the manipulator. Single-arm manipulator adopts integrated whole arm structure, without subsection nesting design, with simple and solid overall structure, few parts and components, extremely strong equipment rigidity, small jitter during operation, high positioning accuracy, and outstanding equipment stability. However, the short board of this structure is obvious, and the arm can not be contracted in sections. After the equipment is fully retracted, the overall height is higher, and there are strict requirements for the headroom of the workshop, which is only suitable for the production workshop with sufficient floors. At the same time, the movement stroke of single arm is fixed, the cycle movement rhythm is relatively gentle, and it is more suitable for injection production with conventional rhythm, and the later maintenance is simple, the failure rate is low, and the procurement cost is lower. It is a classic adaptation model for small and medium tonnage injection molding machines.

Double-arm manipulator adopts two-stage nested expansion and double-speed belt transmission structure, which is an optimized model developed for low-rise factory buildings and high-speed production scenes. Relying on the principle of double-speed expansion and contraction, the double-arm can realize short-distance retraction and large effective working stroke, and the overall height of the equipment is greatly reduced in the standby retraction state, which perfectly solves the installation problem of insufficient height of the workshop, and is suitable for most standard workshops and low-rise workshops. In terms of operational performance, the double-jointed arm has faster action response, which can effectively shorten the action time of picking and returning, greatly reduce the product molding cycle, and is especially suitable for mass production of thin-walled, high-speed and precise small parts. Compared with the single-arm structure, the double-arm structure has more parts, wearing parts such as double-speed belts, and its rigidity is slightly weakened. In the later period, it is necessary to regularly check the belt tension and the wear of the guide rail. The maintenance frequency is slightly higher, and the equipment procurement cost is relatively higher, which can meet the needs of large-tonnage and long-stroke injection production.

Secondly, from the number of arms, the single-arm and dual-arm models are distinguished, and the core difference is reflected in the working efficiency and functional adaptability. The single-arm manipulator is equipped with a single set of arms and fixtures, which has simple structure, small occupied space and convenient debugging. The equipment can only complete a single grabbing action in a single in-mold operation, and it is impossible to pick up the finished product and the material head at the same time. If it is faced with the production of three-plate mold, it is necessary to enter and leave the mold twice to complete the picking, which will directly extend the production rhythm. This model has high performance-to-price ratio and low failure rate. It is suitable for the conventional production scene with two-plate molds and simple structure, and only needs to take the finished product or material head separately. It is a universal basic automation equipment.

Dual-arm manipulator is equipped with independent main and auxiliary double arms, which can realize synchronous linkage operation and is also the preferred model for three-plate mold production. The equipment can grab the finished product by one arm and pick up the material head by the other arm in one in-and-out action in the mold, so as to realize synchronous separation and classified placement of the finished product and the material head of the nozzle, save the secondary part taking process and greatly improve the production efficiency. At the same time, the dual-arm model can be compatible with auxiliary processes such as insert placement and simple post-processing, and has stronger functionality, and is suitable for high-end production scenes with multiple cavities, precision injection molding and mass production. Its disadvantages are greater self-weight of equipment, more complicated structure, debugging difficulty and slightly higher procurement and maintenance costs than single-arm models.

Based on the structural combination, the four mainstream models on the market have their own precise adaptation scenarios. The single-section single-arm manipulator has stable structure and high cost performance, which is suitable for the conventional production of two-plate molds with medium and small tonnage in workshops with sufficient floors. Single-section dual-arm manipulator has strong rigidity and high efficiency, which is suitable for the production of high-rise factory buildings and three-plate die precision products; Two-section single-arm manipulator adapts to low-rise factory building, focusing on high-speed and efficient production; Two-section dual-arm manipulator has the best comprehensive performance, taking into account space adaptability, running speed and working efficiency. It is the first choice for low-rise workshops, three-plate molds and mass precision production.

In the actual selection, enterprises should give priority to the comprehensive judgment of workshop clearance height, injection molding machine tonnage, mold structure, product technology and production rhythm. When the storey height is sufficient, the rigidity of equipment can be guaranteed by single-section arm first, and double-section arm is preferred when the workshop is limited. Single arm can meet the demand for two-plate mold in simple working condition, and double-arm model is recommended for three-plate mold and high-efficiency mass production scene. Reasonable selection can maximize the performance of equipment, improve the level of production automation and reduce the cost of production and operation and maintenance.