In the planning and design of the automobile painting production line, the spraying robot is directly related to the interlocking with other equipment (conveying system, paint mixing system, etc.), coordination with the chamber body (painting booth), work interface division and other designs. , control requirements, etc., and to meet the paint characteristics used in planning and design and the quality requirements for compressed air. Before the selection and design of the robot, the basic data of the production line design (production product, rhythm, pitch, maximum model size, maximum spray area, etc.), process requirements and humanized design must be comprehensively considered, so that the robot and its supporting system Optimization and rationalization of planning and design work.
Taking the DURR spraying robot as an example, this paper briefly introduces the relationship between the robot system and other equipment during planning and design, and explains the division of labor, interfaces and requirements of its working interface.
1 Interlocking between robots and related systems
Interlocking can be divided into mechanical and electrical interlocking. The interlocking between robots and related systems is electrical interlocking. Electrical interlocking includes hard wiring and soft wiring interlocking. The hard wiring method is the traditional wiring method, which is realized by the auxiliary contacts of the components and the wire connection. Hardwired systems have visible wiring, terminal blocks, and test points. Compared with hard-wired control, the use of advanced programmable controllers, soft-connected programming control of computers, etc. is soft-wiring. The interlocking signals adopted by the robot mainly include: operation signal, normal signal and emergency stop signal related to the conveying system; supply and discharge signal related to the air supply and exhaust system of the spray booth; normal fire control signal of the spray booth related to the fire protection system. of them
There are not only hard-wired interlocks, but also soft-wired interlocks. Involving safety interlock signals, usually hard-wired interlocks are used.
2 The relationship between the robot and the conveying system
2.1 Electrical and communication
In addition to the normal safety interlock signals between the robot and the conveying system, there are also ordinary signal exchange and communication, including the encoder signal installed on the conveying chain, the relative position of the body (or spray) on the conveying chain, the product ( body or paint) model and color (paint code), etc.
1) Product and color information identification system: The system is required to have two working modes, automatic and manual. When the product data is invalid or lost, it can be selected manually by the upper computer of the robot system; when a problem occurs, the input of products and colors can be realized through the man-machine interface on the operating table. The spraying system can recognize the empty skid code sent by the conveying system and automatically adjust to the non-spraying state.
2) Color verification: If the robot system receives a color code that does not match the definition, the system will report an error and remind the staff to deal with it.
3) Product information: The model and color information of the product are transmitted to the robot system in a timely manner by the conveying system, and the robot system is responsible for receiving and identifying the signals transmitted by the conveying system. The interlocking and communication signals between the robot and the conveying system are controlled by the robot itself. When the conveying device stops, the robot will stop moving;
When the feeding device runs again, the robot will resume work at the place where it stopped last time, the software system will not generate a restart fault alarm, and can continue to perform the profiling and motion programs from the stop point.
2.2 Conveying system
It is required that the position of the car body on the skid/conveyor system must remain unchanged; the conveyor system must not shake when working to ensure perfect painting; the total tolerance is composed of the conveyor system, the car body, the skid and the foundation, usually the allowable tolerance of the system is ≤±± 10.0 mm, otherwise it will directly affect the film thickness and spray quality.
2.3 Work interface division of labor
1) The robot system installs an encoder, an encoder shield, and a mounting bracket on the extension part of the conveyor chain drive shaft to detect the interlocking motion of the conveyor chain and the robot. The robot system is responsible for the interlocking device with the conveying system, and receives the conveying system signals by itself (including the workpiece conveying system operation, emergency stop, ready and other signals).
2) The robot system needs to specify the installation requirements of the tracking encoder (installation position, etc.), and the conveyor system needs to provide the rotation speed, related drawings and dimensions of the drive shaft of the conveyor chain. At the same time, it is required that the extension shaft of the conveyor chain drive motor has a central positioning hole to facilitate the installation of the tracking encoder.
3) For electrical interlocking and communication signal exchange, if the communication protocol is inconsistent, it is necessary to provide converters, wiring and signal interlocking. Whether the robot system is responsible or the conveying system is responsible can be specified according to the actual situation (the following robots and spray booths supply and exhaust air). System, fire protection system, paint transfer system and other work interface division of labor is the same), usually adopt the principle of "who uses who takes and who releases" and so on.
2.4 The relationship between the robot and the paint mixing system
The temperature of the coating system must be kept constant, and its temperature control range is (22 ± 2) °C. At the same time, the emphasis is different for different coatings, such as the viscosity of water-based coatings and the resistivity of solvent-based coatings. The types of coatings can be divided into water-based paints, solvent-based paints, and high-viscosity paints. Different paints require different pressures to be delivered to the paint booth wall (connected with the robot paint pipeline), and at the same time, the paint pressure is required to be stable and without pulsation. The paint should meet the maximum consumption of each atomizer at the same time, including the maximum consumption of the atomizer during spraying and preloading. The paint circulation speed must be adjusted to better meet the needs of actual production on site.
2) Cleaning agent
The pressure required for the cleaning agent (ie deionized water, solvent) to be delivered to the wall of the spray booth should meet the actual needs, and at the same time, the pressure of the cleaning agent should be stable, without pulsation, and meet the maximum consumption of each atomizer. In order to achieve efficient cleaning results, it must ensure that the paint used
The cleaning agent has a sufficient solution to dissolve all coating materials and is applied to the entire coating system. After that, the paint can be divided into corresponding cleaning procedures, with different cleaning procedures and cleaning times.
3) Clarify the number of paint colors and reduce the waste of cleaning agents and solvents. The spraying stations are usually divided into primer (middle coating) stations, color paint stations and varnish stations. Circulation system, three-line circulation system, etc.), the quantity of paint (color), the quantity of cleaning agent, and the waste solvent return line, etc. It is necessary to meet the design and use requirements while avoiding waste.
2.5 Work interface division of labor
1) The paint and cleaning agent used by the robot (including the cleaning agent used by the atomizer automatic cleaning device) are connected to the ball valve interface at the wall panel of the paint spraying chamber by the paint transfer system, and the robot is responsible for connecting to the robot pipeline and components provision and installation.
2) In order to better meet the flexible production of the coating production line, the planned spraying color cannot meet the actual needs. Usually, the robot system is required to reserve and install a set of cleaning agents, coatings, compressed air quick connectors and corresponding equipment for each robot. The pipeline is used to spray the paint supplied by the small system to better meet the needs of actual production.
3) If the waste solvent recovery function is required, the robot system needs to propose the location and interface size of the waste solvent collection box and the atomizer automatic cleaning device, so that the waste solvent recovery equipment can be installed and recovered.
3 Robot's requirements for spray booth and resistance to ground
3.1 Requirements for spray booth
The spray booth has the conditions for normal spraying, that is, the relative humidity, temperature and wind speed in the spray booth must meet the design requirements. The relative humidity needs to be specific to specific coatings, such as solvent-based coatings, water-based coatings, etc. The relative humidity requirements are different.
3.2 Resistance to ground
Usually includes resistance between body and earth; resistance between two parts (plastic or metal part); resistance between body-in-white (to be painted) and earth; resistance between 2 separate parts (plastic or metal) part); resistance between skid (to be painted) and earth; resistance to earth at each point of the spray booth and conveying system. It must be noted that all components must be electrically conductive when sprayed on the body or skid.
3.3 Signal chaining
The robot system is interlocked with the air supply and exhaust system of the spray booth: when the air supply and exhaust system of the spray booth is not in normal operation, the robot system must have corresponding alarms and corresponding actions. The robot system is interlocked with the fire protection system: when the fire protection system sends out a fire alarm signal, the robot system should stop the corresponding action, cut off the high-voltage power supply, the power supply of the motion axis, close the paint, solvent, and compressed air pipelines, and issue an alarm indication.
3.4 Work interface division of labor
3.4.1 Robot Basics
In the detailed design of the robot system, the robot needs to provide detailed information such as dynamic and static load requirements and specific installation positions to the paint spray booth designer, so as to design the chamber body. The process of being responsible for the design, manufacture, processing and installation of the spray booth includes the foundation of the robot, and at the same time, it is required to comply with the load, installation position, size and height provided by the robot.
3.4.2 Personal safety and danger prevention
An emergency stop safety switch is set on the exit door of each robot station room, which is interlocked with the automatic spraying system to ensure that personnel are outside the room. The entrance and exit of the robot area are equipped with grating muting switches, and each safety switch must be connected to each automatic system controller. Activating any safety line in any chamber stops the operation of indoor equipment and interrupts the spraying process. Restarting the system where it stopped does not affect the quality of the spray (except in the event of an emergency stop).
Part of the supporting equipment of the robot system needs to be installed on the spray booth body, which requires the robot system to provide detailed information such as the safety switches installed on the spray booth body, the installation position and size of the supporting equipment to the spray booth designer, so that It is used to design and reserve the chamber body to ensure that the equipment installed on the spray booth by the robot system meets the requirements for use.
4 Robot's requirements for compressed air
1) Compressed air pressure, position, consumption The robot system needs to clarify the dynamic pressure (usually 0.6 MPa) of the air supply for all robots and supporting equipment, as well as the volume of compressed air consumption per hour (Nm3/h) and the total volume (Nm3/h).
2) Compressed air quality
Because the compressed air output by the air compressor is not clean, in addition to water (including water vapor, condensed water) and suspended matter, it also contains oil (including oil mist and oil vapor). These pollutants are detrimental to improving production efficiency, reducing operating costs, and improving product quality. Therefore, a series of drying and purification treatments are required before the compressed air is supplied to the robot and ancillary equipment. Among them, the compressed air quality grade standard ISO 8573.1 divides the pollutants in the compressed air into solid impurities, water and oil. The specific requirements for the spray air quality required by the robot are as follows:
①Pressure dew point (i.e. dry and wet degree) ≤- 20 ℃, which can be achieved by dryer; ②Residual dust content (i.e. dust particle size and concentration) ≤ 0.1mg/m3 (corresponding to particle size of 0.1 μm), which can be achieved by Filter to achieve; ③ residual oil content (that is, how much oil content per unit volume of compressed air) ≤ 0.01 mg/m3, through the filter to achieve. Because the quality of compressed air directly affects the level of investment and production costs, excessive quality requirements should be avoided. It is more economical and practical to use dry and corresponding dust-free and oil-free compressed air, which can avoid various failures of the robot body and components caused by oil, water or ice and dust, and can avoid the occurrence of waste products and production stoppages.
3) Compressed air pipeline interfaces required for access to robots, ionization stations, etc. are usually subject to the thread standard conforming to the DIN/ISO 228 standard.
4) Work interface division of labor and public power will provide 0.6 MPa compressed air that meets the requirements of the robot system (pressure, flow, quality, etc.) If the robot system needs compressed air higher than 0.6 MPa, the compressed air booster device will be provided by the robot and can meet the needs of use. In addition, the pneumatic cabinet of the robot is required to be equipped with filters, pressure regulators and pressure gauges, etc., to further confirm whether the compressed air meets the actual use requirements.
5 Other design and control requirements
5.1 Power Requirements
The robot system puts forward specific power supply requirements according to the number of robots (including the consumption and connection of each robot station) and supporting equipment, so as to meet the normal operation of the field equipment.
Work interface division of labor: Usually, the public power provides a 380 V three-phase five-wire power supply that meets the requirements to the main electric control cabinet of the robot system (the specific work interface division of labor depends on the situation), and the internal power supply of the robot system is self-distributed or connected to this point. Take power and be responsible for supplying and connecting all circuits after this point.
5.2 Central control room information
All spraying robot stations are required to have information exchange with the central control room, that is, the upper computer of these devices should be connected to the equipment control Ethernet, allowing relevant personnel to monitor the running status and alarm information of the specific robots of the spraying robot station in the central control room or other monitoring stations.
The robot system is responsible for providing an RJ45 Ethernet interface in the control cabinet of the robot station, and prepares the data blocks of the robot station status information and basic fault information in the PLC program, which is read by the central control itself, and the central control room is responsible for the rest.
5.3 Model Identification Error-Proof System
In order to ensure that the information of the car body is accurate, the robot system should be equipped with a product identification system at the entrance of the primer (middle coating) line and the topcoat line. Compare the product model of the robot, if they are the same, the robot will correctly call the painting copying and painting parameters; otherwise, the system will report an error and remind the staff to deal with it.
By understanding and mastering the relationship between the painting and spraying robot system and other equipment and chambers, it plays a key role in the planning and design of the robot system in the automobile painting production line, which directly affects and restricts the quality of production products and investment costs. According to the basic data of production line planning and design, process requirements and the close cooperation between the robot system and related equipment and chambers, the interlock, working interface, interface and required division of labor between them are defined. The robot system design can be improved only when the problems of related equipment in the design are solved and improved in a timely and effective manner, with a reasonable division of labor and mutual cooperation.