Xu Zheng
(Shanghai Jiu Duan Precision Electromechanical Technology Co., Ltd., Shanghai)
Abstract: This article introduces some features and advantages of Siemens SIMATIC T-CPU in implementing multi-axis complex motion control by introducing the electrical control system of the high-speed heat-dissipation belt forming machine, and introduces some experiences in the development process.
Keywords: SIMATIC T-CPU, DP(DRIVE), SINAMICS S120, Servo Drives, Cooling Belt Molding Machines, Synchronous Control, Motion Control, Metal Forming Machines
Abstract:This paper introduces that electrical control system for High speed radiator metal-forming machine, present advantages of SIMATIC T-CPU in multi-axis motion control application, some realization of SIMATIC T-CPU application.
Key Words: SIMATIC T-CPU, DP(Drive), SINAMICS S120, Servo motor, Servo Drive, metal-forming, motion control, coupling motion control, synchronizing axis,
I. Project Overview
The cooling belt is one of the most important and most used components in the air conditioning industry. It plays a very important role in the temperature control effect of the radiator and condenser. Due to the process complexity of the heat sink molding technology and the large demand of the air conditioning industry, its manufacturing process is often difficult to achieve with simple mechanical equipment. Traditional manufacturing methods are: mechanical gear transmission, plus simple servo control. The technical weaknesses of traditional process manufacturing are: difficulty in modifying process parameters and poor control accuracy.
This time, we developed this set of cooling belt molding machine equipment, the electrical control part of the Siemens SIMATIC CPU315T-2DP to the system's various drive shafts for accurate motion control, not only can effectively improve the drive shaft positioning accuracy, but also in the The process parameters are modified in real time during the entire system operation, which overcomes the technical weaknesses in traditional equipment.
Second, the control system composition
Figure 1
The heat sink molding machine is a typical motion control system. Its raw material is a radiating belt that is rolled into a disk shape (see Figure 1), and its finished product is a sawtooth type with the same length and a certain height. Heat sink (see Figure 2).
Figure II
This machine consists of a total of six axes (see Figure 3). The various operating and process parameters for the axes are set by Siemens Human Machine Interface (HMI). The first axis of the system is the speed axis. Speed ​​control is realized through the inverter. Its role is to quickly release the heat-dissipation belt of the machine tool, which is in the form of a disk, according to the operating speed set by the system. The second axis of the system is connected to the gear box and the forming tool. Although it is also controlled by the frequency converter, it is the spindle of the machine because an incremental encoder is installed on its shaft end as the active axis of the entire system. The third shaft is a driven shaft and its position is between the first shaft and the second shaft acting as a damping and buffering effect. In a conventional process, this shaft is replaced by a magnetic powder brake, but since the magnetic powder of the magnetic powder brake is magnetized over time, the quality of the product is not sufficiently guaranteed. Now we will carry out the relative synchronous control of the electronic gear ratio between this axis and the spindle, so that it forms a slight speed difference with the spindle to generate a certain tension. This not only overcomes the shortcomings of the magnetic powder brake, but also eliminates the raw material irregularities. Manufacturing errors caused by other factors.
After the heat sink has been shaped by a forming tool, it forms a loose zigzag shape. However, the sawtooth shape of the finished heat dissipating belt is very tight, and the heat dissipating belt is indented and has strong elasticity, and it is not easy to form the final shape. Therefore, the fourth, fifth, and sixth axes require multi-level shaping adjustment of the entire heat-dissipating tape. Due to the rapid movement of the heat sink during the operation of the machine tool, it is necessary to reach three meters per second. Therefore, one of the difficulties in system control is that the shafts must be properly matched with each other, and cumulative errors cannot be generated. Here we use the absolute electronic gear ratio provided by the SIMATIC T-CPU as the precise synchronization function, which allows the encoders of the fourth, fifth and sixth axes and the end of the spindle to achieve positional synchronization, which is a good solution to this problem. problem.
Another difficulty in system control is the cutting of uniform lengths of tape in the rapid movement of the heat sink. In the control of the sixth axis of the machine tool, we used the OUTPUT CAM function in the electronic gear ratio synchronization of the SIMATIC T-CPU so that after the sixth axis reaches the specified position, it can promptly send a signal and trigger the cutter to cut the tape.
The six axes of the entire machine tool are connected through the isochronous communication mode of the PROFIBUS-DP(DRIVER) communication port, which greatly improves the consistency, stability and rapidity of the system.
Figure 3
Third, the control system to complete the function
At the heart of the entire control system, we chose Siemens' SIMATIC CPU315T-2DP. It is a new generation of S7-300 PLC automatic control products in Siemens family that integrates Siemens SIMOTION motion controller and SIMATIC logic controller. The communication between these two well-known Siemens controller cores is ensured by the internal hardware of the SIMATIC T-CPU. It does not require the user to additionally compile communication programs and realizes a complex logic controller and advanced motion controller. Seamless connection saves the user's development costs and greatly reduces the system's programming and debugging time.
In the system, the two communication ports of the CPU315T-2DP are configured with a communication rate of 12M bits/sec. The standard MPI/DP port is used to connect the man-machine interface and the inverter, and another Profibus DP (DRIVE) port is used to connect the servo control. And external encoders. The six axes of the entire system are controlled by the SIMATIC T-CPU via the PROFIBUS bus and are linked in ISOCHRONE MODE mode, which greatly improves the control accuracy of the system. The hardware configuration is shown in Figure 4.
Figure 4
The servo controller adopts the latest SINAMICS S120 CU320 from Siemens (see Figure 5). The motor module uses a book-type dual-axis module with DRIVE-CLIQ interface. The motor uses 1FK7 series servo motor with DRIVE-CLIQ interface. During the hardware configuration, the S7T Config debugging software integrated in the software S7 Technology is used to use the "drive parameter automatic configuration mode" to all the servo system data at one time (including: servo drive parameter configuration, servo motor parameters, and servo motor code Read), eliminating the need for cumbersome servo drive and motor parameter configuration.
Figure five
IV. Implementation and Operation of the Project
The development software of the SIMATIC T-CPU performs hardware configuration, driver commissioning, process parameter setting, and programming by means of the technology package S7 Technology integrated in the STEP 7 environment.
For the programming of the SIMATIC T-CPU, the programming software STEP 7 with the SIMATIC S7-300 PLC is exactly the same. This is also the most attractive place for engineers and technicians, as long as you have the technical basis of PLC programming, you can independently complete the development of very complex motion control systems on the SIMATIC T-CPU platform. Since the SIMATIC T-CPU is a new generation of SIMATIC S7-300 PLC automation products that integrates Siemens SIMOTION motion controllers and SIMATIC logic controllers, you can not only easily get outstanding Siemens SIMATIC S7-300 PLCs. Many technical advantages of the controller (for example, logic control, industrial network communication, HMI communication, remote diagnosis, etc.), and the advantages of many motion control technologies of the excellent SIMOTION motion controller from Siemens.
The SIMATIC T-CPU is mainly used in a variety of applications that require multi-axis motion control. The application of this multi-axis motion control system often has certain difficulties for the realization of the electrical control system. If you use the SIMATIC T-CPU, you can find the corresponding commands in the STEP 7 programming library as long as the STEP 7 software and the S7-Technology software package are installed in the computer. There is no difference between function blocks, calling them and using the usual SIMATIC S7-300 software function blocks. You can use PLC structured programming, and it is very easy to implement motion control programming and debugging. In this way, the users of Siemens SIMATIC T-CPU have a low knowledge of the background of the engineer's motion control and are very human.
Process axis parameters such as speed, displacement, etc., and various status and error information of the axis are contained in the DB block assigned to the axis. When programming, the value of the corresponding address in the DB block of each axis can be read. The state of movement of the axis is clear at a glance. Moreover, faults can be judged and dealt with in a timely manner through error alarm information in the DB block. Figure 6 shows the DB blocks generated after the four servo axes of the machine have been configured.
Figure 6
Fifth, application experience
After the machine is put into operation, it works normally and its performance is stable. In particular, the device can achieve molding speed of 3 meters per second, and it can dynamically modify the technical characteristics of the process parameters, has been praised by users.
Recalling the development process of the machine tool control system, it is fortunate that in the selection phase of the project plan, it made a wise decision - choose Siemens SIMATIC T-CPU as the core component of the control system, so as to ensure that they can be in just a few months time, Successfully carried out the research and development of the entire complex electrical control system and provided a strong technical guarantee.
During the development of the system, we got a good service from the Siemens technical support team and we sincerely thank you for this.