Application of industrial robot in automatic transformation of compressor pump production line

Abstract

With the rapid development of industrial automation, the traditional manual operation is no longer suitable for the development of modern enterprises, because the industrial robot control system dynamic response is fast, high position accuracy, strong overload capacity, so it is very suitable for the production of mechanical parts and processing line automation transformation. In this paper, an air conditioning compressor company to the pump body production line for the theme of automation, the application of industrial robots instead of artificial automation production. Aiming at the transformation of the L2 series pump body assembly line in the assembly plant of the company, the industrial robot was used to transform the production line, and the program debugging was carried out on the site. The robot was able to run stably and work as required. At last, the actual working beat of the robot is calculated to be 13.7 seconds, which is 2.3 seconds less than 16 seconds in manual operation. Experimental results show that the actual working tempo of the robot can meet the requirements, and can improve the assembly efficiency and save manpower.

Keywords

Compressor automation mechanical

1. Introduction

At present, China’s manufacturing level is still in the industrial 2.0 and 3.0, from the use of electricity driven mechanical system to the application of electronic information technology to improve the level of automation of production direction. Germany 4.0 takes intelligent factory as the core, establishes a set of large-scale and customized product design, production and service mode, and truly realizes the transformation and upgrading process from manufacturing to “intelligent manufacturing” [1]. Whether from the level of production management or product technology level, China has a huge substantial gap with Germany and other developed countries. Industry 4.0 is the inevitable direction for the future development of China’s manufacturing industry. China must take the road of industry 4.0 to realize the ideal of manufacturing power [2]. On March 5, 2015, Li keqiang first proposed the grand plan of “made in China 2025” when he delivered the government work report at the national two sessions. “Made in China 2025” is a major strategic plan made by the Chinese government to comprehensively improve the quality and level of China’s manufacturing industry under the new international and domestic environment and based on the general trend of international industrial transformation.

Its fundamental goal is to change the “big but not strong” situation of China’s manufacturing industry. Through 10 years of efforts, China will become a manufacturing power, laying a solid foundation for building China into a manufacturing power with global leadership and influence by 2045 [3]. “Made in China 2025” clearly indicates that the integration innovation and engineering application of new generation information technology and manufacturing equipment will be carried out closely centering on key links in key manufacturing fields. We will support government-industry-university-research-application joint efforts to tackle key problems, develop intelligent products and autonomously controllable intelligent devices, and realize industrialization. Relying on advantageous enterprises, we will build intelligent factories/digital workshops in key fields by closely following key process intelligence, robot replacement of key positions, intelligent optimization control of production process and supply chain optimization [4].

2. Literature review

Abroad have formed a group of strong, Wicher detection Technology research and development and production base, advanced industrial robot robot of the famous manufacturers abroad mainly Japan FANUC Yaskawa company, Sweden ABB Robotics companies, German KUKA Roboter company, America’s Adept Technology company, etc., the company has become the area of the industrial robot pillar [5]. At present, industrial robot automatic production line has been widely used in foreign automobile manufacturing industry, electronic and electrical industry, construction machinery and other fields. Due to the investment of industrial robots, the production quality of products is guaranteed to a greater extent, the production efficiency of products is improved, and a large number of safety accidents caused by industrial injuries are avoided. At home, China, as the world’s factory, has witnessed the rise of industrial robot industry in developed provinces and cities in China in recent years, and even has penetrated into some underdeveloped provinces and cities. In order to reduce manufacturing costs and solve the serious shortage of employees in factories, it is particularly important for Samokhin to invest in industrial robots for automatic transformation [6]. According to data from China’s national bureau of statistics, China accounts for about 1/8 of the world’s industrial robots every year, making it one of the countries with the most industrial robots in use. Japan and South Korea are the countries with the most industrial robots in use. Four new types of industrial robots were successfully developed in Harbin, China, in 2018. In recent years, Deng pointed out that the major domestic robot manufacturers include eft intelligent equipment co., LTD., China xintong machine automation co., LTD., and shougang motoman robot co., LTD. [7].

The innovation of this paper is that through the powerful 3D design function of Pro/E software, 3D design modeling is carried out for each functional unit of the mechanical claw. Then, each functional part is assembled according to the actual assembly relationship to obtain the three-dimensional model of the virtual prototype of the mechanical claw. Finally, the machine is processed through the CAD two-dimensional engineering drawing. The control system of the robot is designed and analyzed again, and the I/O control module of the robot is designed. The designed production line is simulated and analyzed based on FANUC Robotics software [8].

3. Experimental methods

3.1 Transformation tasks

(1)
Investigate the production situation, production environment and work content of the pump body production line, and design the renovation plan.
(2)
The overall layout of the production line includes the layout of the production line, concentric assembly machine, robot, robot control cabinet, pump body tray, safety fence and robot control cabinet [9].
(3)
Select the type of robot to be used in the transformation process, including the manufacturer and the robot model. Understand and introduce the structure of the robot, which is mainly divided into the robot body, the control cabinet and the function of the teaching device.
(4)
As the actuator at the end of the robot, the mechanical claw should be designed reasonably and optimized. The function of each component of the mechanical claw was introduced, pro/E 3d model and 2d engineering drawing were established, and the mechanical claw was finally assembled.
(5)
Computer control module is the core module of robot controller. 1. I/O pin definition, the robot through I/O module to achieve communication with each device and external signals. 2. Automated simulation of the production line is carried out by using ROBOGUIDE software, and the motion path and running track of the robot are optimized through the simulation process. 3. After the simulation, the robot is installed on the actual production line, and then the field program is written so that the robot can work reasonably according to the required operation steps and trajectory. Finally, the robot program is debugged to observe the running state of the robot. 4. After the robot is put into operation, calculate the actual production beat and observe whether the actual product production time meets the requirements [10].
(6)
After the robot is put into use, special technicians are dispatched to conduct technical management on the site, observe and record the actual operation situation and problems of the automatic production line, so as to make improvements.

3.2 Robot selection

Er50-c20 eft robot is now selected. Its control system adopts industrial technology and is based on the operating system. It has a friendly man-machine interface and is quite convenient for programming, operation and maintenance [11]. And through the installation of software, can directly control the external equipment, make the automatic control more effective, no need to increase the external control hardware, reduce the failure, reduce the cost, make the system programming, maintenance easier. Each pair of joints and bars of the robot constitutes one degree of freedom. Now start from the base and make the rod base into 0 rod, the first motion rigid body into 1 rod, the connection point between 0 rod and 1 rod is 1 joint, and so on. D-H parameters of six-dof joint robot is shown in Table 1. For ease of description robot adjacent connecting rod, the relative position and relative motion relationship between the consolidation of a coordinate system, respectively, on each connecting rod rigid body or system of differential movement including differential movement vector d and $\delta$ differential rotation vector, the former is composed of the differential movement along the three axes, the latter is made around the three differential rotation of the coordinate system, namely:

$\displaystyle{d}=\left[{d_{x},d_{y},d_{z},}\right]^{T}$ $\displaystyle\delta=\left[{\delta_{x},\delta_{y},\delta_{z}}\right]^{T}$

3.3 Robot system simulation

Robots into the production line prior to installation to the simulation analysis for the performance of the robot, to prevent the equipment after the robot installation due to the site installation errors or other device to interference of robots, as well as to test the robot program, in order to avoid interference occur program itself, finally get the best operation mode of the robot and track [12].

3.4 Robot I/O control module

The robot’s signal has the input signal and the output signal two parts. The standard input signals are: hand pressure switch, pause, resume operation; Standard output signals are: alarm, robot pause, operation signal. These signals are already defined and do not need to be defined. In practice, when the signal is needed, the signal only needs to be connected to the corresponding other pins. The er50-c20 industrial robot control cabinet has three input modules and two output modules. Each IO module USES a 24V power supply. IO module is the relay station and connection unit between external signal and robot.

3.5 Teaching programming

Programming instruction plays an important role in the application of robot. CNC program is the soul of robot reproduction. According to the instruction grammar, the programming which can make the robot run efficiently, safely and stably is the basis of robot control.

4. Experimental results

Table 1
D-H parameters of six-dof joint robot

Connecting rod	$\theta$ i	di	ai	$\alpha$
i $=$ 1	$\Theta 1$	0	0	$-$ 90 ${}^{\circ}$
i $=$ 2	$\Theta 2$	D2	A2	0
i $=$ 3	$\Theta 3$	0	as	90 ${}^{\circ}$
i $=$ 4	$\Theta 4$	D4	0	$-$ 90 ${}^{\circ}$
i $=$ 5	$\Theta 5$	0	0	$-$ 90 ${}^{\circ}$
i $=$ 6	$\Theta 6$	D6	0	0

4.1 Program debugging

Ensure that there is no workpiece in the equipment and no workpiece on the two jaw before continuous operation; The robot’s global speed is adjusted between 5% and 10%. After finishing 1–2 workpieces at a speed of 10%, observe whether the workpiece can meet the requirements and observe whether there will be interference in the robot’s movement. If the robot can run smoothly and the workpiece is well machined. The overall speed was improved by 15%–20%, and the same two workpieces were processed for observation. If all is well, the robot will eventually run at a steady speed of 85 to 95 percent. Special attention is in the claw grasp and move out of the workpiece, can not adjust the global speed, so as to avoid collision.

4.2 Calculation of robot working time

The production beat is the main standard to measure the production efficiency. The working rhythm of the robot is related to the path of the robot, the speed of the robot, the machining speed of the tongge and the flow speed of the assembly line. Taking the motion path of the robot as an example, it is considered that both the assembly line and the tongscheming machine can work normally and keep up with the time set by the robot without any delay. In a working cycle, the industrial robot has to complete the feeding and unloading work on the assembly line, as well as the feeding and unloading work in the same machine, plus the safe position waiting time set due to safety considerations. The industrial robot circulates from t1–t6 working process and motion path in Table 2. Therefore, the actual time required by the robot in each stage of a work cycle can be obtained, and the time required for the robot to complete a work cycle can be obtained as follows:

$\displaystyle\text{t}=\text{t}1+\text{t}2+\text{t}3+\text{t}4+\text{t}5+\text{% t}6+\text{t}7=13.7\text{ s}$ $\displaystyle\textit{WorkBeat}=\frac{60\text{ s}}{\text{t}}\approx 4\left({% \textit{Pcs/Min}}\right)$

Table 2
Robot operation beat

Time serial	Working process	Time/s
number
t0	Robot arrives directly above the production line from the standby safety point and waits	1
t1	Robot descends no. 1 jaw, closes, grabs the workpiece, and rises back to the top of the production line	1.7
t2	Robot chassis rotated 90 ${}^{\circ}$ , and then down to no. 2 of the jaw is processed workpiece placed on the tray, and rise to the line above	2.5
t3	Robot moves from above the assembly line to the safety point outside the concentric machine and waits	1.9
t4	Robot moves up and inside the machine	0.9
t5	Robot descends to grab the processed claw 2	1.7
t6	Robot chassis rotated 180 ${}^{\circ}$ , and then down to 1 jaw raw workpiece inside with centrifuge, and rose to the upper part	2.8
t7	Robot leaves the tongge to reach the safety point outside the concentric machine and moves to the upper part of the assembly line to wait for the pallet	2.4

The simulation space is established by using the software ROBOGUIDE before the robot is put into the concentric assembly station. The actual work content of the robot is simulated by simulation, and the motion trajectory of the robot is obtained. Then the robot is wired and the function of the robot I/O port is defined. According to the work content of the robot to teach the robot programming, and in the field of the program debugging, the robot can stable operation, and can work according to the requirements. At last, the actual working time of the robot is calculated to be 13.7 seconds, which is 2.3 seconds less than 16 seconds in the manual time. In order to improve the production efficiency and solve the problem of the pump body concentric assembly machine position beat backward, the reconstruction requirements and reconstruction plan for the production line are put forward. After observing the working mode and measuring the working space of the production line, it is decided to use the industrial robot to carry out automatic transformation to meet the production requirements. At the same time, a concrete transformation plan was drawn up, and robots were added to replace the working mode of workers. The spatial layout of all the equipment in the reconstruction is carried out to prevent the position interference in practical application. Finally, according to the working mode of the robot, the motion steps of the robot are preliminarily drawn up. The robot is used as an automatic equipment to carry the pump body in the reconstruction process. According to relevant experience, work requirements and site conditions, and through the relevant understanding of industrial robots, the model er50-c20 evert robot was selected. At the same time, the composition of the robot includes robot body, robot control system and teaching device, as well as the performance parameters and application mode of the robot. The running situation of the robot is analyzed by TP programming. After the robot is put into the production line, a program is written with a demonstrator, and the actual on-site robot is used to control and plan the robot’s motion trajectory, so that the robot can run in accordance with the work requirements and carry out debugging and operation. Finally, the actual working beat of the robot can meet the requirements.

5. Conclusion

The level of automation in a factory is the main measure of a company’s advanced level. The application of industrial robots in the electrical manufacturing and processing industry is the inevitable trend of the future electrical processing to the direction of numerical control, high speed, high efficiency, high precision, function compound, green environmental protection, intelligent and so on.At present, air conditioning compressor assembly is still labor-intensive industry, a lot of assembly work is done by hand, not only slow efficiency, but also labor intensity of workers. Through the intelligent transformation of the air conditioning compressor assembly line, intelligent components, such as robots, servo transmission, servo cylinder and other intelligent equipment are used instead of manual work for handling, assembly, automatic loading and unloading and welding inspection, so as to improve the assembly efficiency and save manpower. This paper studies the application of robots in the automatic transformation of production lines, which can not only realize the automation of the whole factory for the company, but also provide technical support to the industry and other industries, and have a comprehensive understanding of the robot and automatic transformation of production lines.

References

Navarrolópez

E.M.

and O’Toole

M.D.

, Automated generation of hybrid automata for multi-rigid-body mechanical systems and its application to the falsification of safety properties, Mathematical & Computer Modelling of Dynamical Systems24(1) (2018), 44–75.

Schädler

Miestinger

and Becher

et al., Automated control of mechanical ventilation during general anaesthesia: study protocol of a bicentric observational study (avas), Bmj Open7(5) (2017), e014742.

Ichiro

Koichi

and Atsuo

, Automatic breast cancer palpation robot, Advanced Robotics3(4) (1989), 251–261.

Everett

L.J.

and Ives

T.W.

, Automatic maintenance of robot programs, IEEE Transactions on Robotics and Automation11(4) (1995), 603–606.

Ahmed

T.T.

and Zhang

Y.J.

, A practical approach for automated polishing system of free-form surface path generation based on industrial arm robot, International Journal of Advanced Manufacturing Technology93(9-12) (2017), 3921–3934.

Samokhin

Hyytiä

Kai

et al., Adaptive boost pressure control for four-stroke diesel engine marine application in the presence of dynamic uncertainties, IEEE Transactions on Control Systems Technology PP(99) (2017), 1–13.

Pritschow

Koch

and Bauder

, Automatic generating of inverse coordinate transformations for industrial robots by application of an optimized iterative solution method, Robotersysteme5(1) (1989), 3–8.

Liu

Cong

and Liu

et al., Trajectory planning for porcine abdomen cutting based on an improved genetic algorithm and machine vision for industrial robot, Jiqiren/Robot39(3) (2017), 377–384.

Chen

H.P.

and Sheng

W.H.

, Transformative CAD based industrial robot program generation, Robotics and Computer-Integrated Manufacturing27(5) (2011), 942–948.

10.

Shi

Tian

X.C.

and Zhang

C.H.

, Automatic programming for industrial robot to weld intersecting pipes, International Journal of Advanced Manufacturing Technology81(9-12) (2015), 2099–2107.

11.

Damir

and Bojan

, Measuring knee movement using an industrial robot – Gravity compensation for the automatic gripper, Strojniski Vestnik/Journal of Mechanical Engineering48(2) (2002), 87–97.

12.

Liu