With intelligent manufacturing entering the manufacturing field, automatic production has become an effective way for companies to improve their influence and expand product scale, and an effective means for companies to win the market.
Automatic workstation project, from conventional stacking, welding, handling to data collection, intelligent manufacturing, is developed step by step.
This post analyzes and explains the three aspects of the welding automation project, including the preliminary design, fixture description, site layout and beat.
Selection of welding robot
Robot automatic welding project must be familiar with the selected robot model and performance, especially whether there are special regulations and specific requirements for the product material information, incoming material status, process requirements and inspection requirements.
At the same time, we should also understand the equipment function, technical parameter information and application environment, and comprehensively give the planning scheme information.
The robot is usually a 6-axis robot (the fixture uses 7-axis or multi-axis, both of which are external axis, which is used for robot manufacturing)
According to the welding process requirements (MIG, MAG, TIG, sup, CO2, etc.), size parameters (arm span length, load capacity, etc.) and structural state, the equipment model is selected.
This time, the ABB 1410-5 / 1.44 robot is selected to weld the lower beam of the elevator with the MAG welding process.
See Table 1 for specific parameter information.
Table 1 welding product information (unit: mm)
|Product description||Product information||Weld length||Weld size|
It is necessary to select the robot model according to the specific parameter information and process information.
The maximum size of the product is 1400mm, and the robot model is abb1410-5 / 1.44, which can cover the product size range.
At the same time, whether the robot’s repeated positioning accuracy is within the control range is considered.
Because repeatability determines the consistency of the welding process.
The high repetitive positioning accuracy not only reflects the accuracy of the robot, but also avoids that the welding quality can not meet the requirements due to the poor repetitive positioning accuracy, which eventually leads to unqualified products and brings losses to the enterprise.
The trajectory diagram and parameter information of the robot are shown in Figure 1.
|Project description||Manipulator parameter information|
|Wrist holding weight||5kg|
|Maximum arm span radius||1440mm|
|Number of axes||6 axis|
|Repeat positioning accuracy||025mm (Comprehensive average value of multiple robots)|
|Robot version||Standard Edition|
|Axis||Motion range||Max speed|
|1||+170° ~ -170°||120°/s|
|2||+70° ~ -70°||120°/s|
|3||+170° ~ -65°||120°/s|
|4||+150° ~ -150°||280°/s|
|5||+115° ~ -115°||280°/s|
|6||+300° ~ -300°||280°/s|
|Power supply: 200 ~ 600V, 50/60hz|
Figure 1 parameter information of robot trajectory diagram
In the initial selection of the robot model, we need to consider that due to the limitations of layout and origin, we need to consult the function description table and trajectory diagram of the robot to ensure the accessibility of welding and avoid reducing the work efficiency.
At present, production simulation and simulation can be carried out through robot teaching software, and the welding range of robot, product space and position placement can be evaluated and confirmed in the early stage of the project, and the problems caused by robot production can be identified and improved in advance.
Description of external equipment
In the early stage of the simulation and simulation process, there is often a lack of evaluation of tooling, external axis and sliding table, resulting in a lot of energy on the transformation of tooling, external axis and sliding table, increasing the project cycle and enterprise losses.
Therefore, it is necessary to evaluate the external equipment such as tooling, external shaft and sliding table in advance.
Welding tooling plays an important role in the overall progress of the project.
Tooling design is a subject, which needs the accumulation of experience, mechanical and electrical knowledge and deep understanding of products.
We just want to provide a way to deal with the design of welding tooling.
Generally speaking, robots are suitable for standard and low repeatability products for large-scale manufacturing, so the consistency of welding tooling (meaning is equivalent to the consistency of robot’s repeated positioning accuracy), clamping sequence, positioning accuracy, stiffness and positioning requirements with the robot are the key factors in the design of welding tooling.
It is necessary to ensure the accuracy of the positioning position of the welding product in the tooling, and also to ensure that the welding stress and deformation can be controlled after the welding, so it needs to have appropriate stiffness.
Most of the welding tools are located by pneumatic structure, hydraulic, electric or manual support pneumatic structure.
At the same time, with the progress of technology, magnetic fixation can be considered.
But only for the special tooling without magnetic bias blowing, it needs to be selected according to the actual situation.
At the same time, in order to improve the heat dissipation and stiffness of products, red copper and alloy materials are often used to make special gaskets (Fig. 2 and Fig. 3).
Fig. 2 Special material module
Fig. 3 Copper material module
External shaft positioner
The positioner is used as the external axis of the robot.
Its positioning accuracy, turnover and rotation accuracy directly affect the repeated positioning accuracy and welding quality of the robot, and affect the final quality of the product.
The pre-design of positioner with welding tooling needs to consider the load, including tooling weight and product weight.
In order to avoid overweight, the reducer, gear and ring gear with small backlash and high rotation accuracy are selected, so as to reduce the rotation inertia of the positioner, make the acceleration and deceleration response fast, and improve the accuracy requirements.
The parameter information of the positioner is shown in Table 2.
Table 2 Parameter information of positioner
|Double seat single rotary positioner (set)|
|Outer axis||ABB external shaft MU200|
|Height of tooling loading table||850mm|
|Accuracy of positioner||The radius of rotation center is 500mm|
|Repeat positioning accuracy||±0.15mm|
Welding system configuration
According to the requirements of the welding project, the welding system should include: welding power supply, wire feeder, welding gun, cooling system (some integrated into the welding power supply), gun cleaning, wire cutting system and anti-collision system.
If there are special requirements, it can be considered to increase the laser position patrol, visual tracking, origin TCP calibration and other equipment auxiliary systems to improve the quality and efficiency of welding.
Analysis of the problems existing in the project
Any automation project will have problems and challenges. This post selects several common problems in the routine process to explain.
The welding tooling is manual
Welding tooling uses manual tooling, which is a common production mode in some enterprises.
But from the point of view of manufacturing, the flexibility of human is higher than that of robot, and the control of human brain is higher than that of robot.
Because the welder is observing the weld pool and welding torch trajectory in the welding process, it can adjust at any time.
Compared with the robot in the production process, it completes the welding according to the program, and has disadvantages in the adjustment and tracking, which is easy to cause simple copying of manual tooling.
Not only can not be consistent with the previous production efficiency, but also because the robot is mass production, resulting in a large number of bad and rework risk.
In the production of tooling, the idea can learn from manual tooling, but from the angle of strength and repeatability, it needs to meet the manufacturing needs of robot through the special process or changing tooling design.
Insufficient weld accessibility
As mentioned above, due to incomplete identification and lagging tooling design before project evaluation, it was found that some welds could not be completed during the welding process, or the welding position was not suitable (such as changing from ship type welding to vertical down welding), resulting in poor welding quality of products.
Therefore, the simulation before welding and the understanding of robot instructions are necessary.
Selection of robot welding process
The robot welding process (such as welding parameters, welding sequence, etc.) is different from manual welding.
The output parameters of the robot are relatively stable.
Manual welding parameters may not be copied to the robot. If the parameters and process are copied, the welding deformation may increase.
Therefore, in view of the particularity of robot manufacturing, it is necessary to reevaluate the welding process according to the project consideration.
Management of welding raw materials
The robot is very sensitive to the change of raw materials, so when using robot welding, we need to consider the control of welding raw materials
Therefore, enterprises and project managers’ understanding of robots can not only stay in the perspective of machine replacing manual production.
The robot is widely used, the welding robot is one of them.
It has been widely used in various industries, and it has its particularity compared with other types of robots.
From raw material management, equipment selection, process confirmation, personnel training and other aspects, we need to pay attention, so as to improve the efficiency and quality of the company’s products and reduce the labor intensity of employees through robot workstation.
However, from the perspective of enterprises, the preparation and manufacturing of automation solutions are not overnight, and its influence and significance is not only the replacement of human by machines, but also the overall upgrading of the industry, that is, to invest in technology and experience, and return it with quality and market.