Research on Tool Information Management of Intelligent Machine Tool Based on RFID

CNC machine tools have become the mainstream equipment in the machining workshop. Generally, the number of tools in the small CNC machining workshop is as high as 1,000. Together with its supporting components, the total number is tens of thousands and hundreds of varieties. As the number and types of tools increase dramatically, standard and non-standard tools of various types and specifications in the production shop coexist, and a large number of tools frequently flow and exchange between the tool warehouse and machine tools and machine tools. At present, domestic processing workshops rely on manual methods and paper barcode management tools. Paper barcodes are easily stained in oily environments, and tool life can only be judged by experience. Due to the lack of tools, many machining processes are stopped, and the machine operator takes a lot of time to find the tool. With the increase in the types of CNC machine tools and the variety of new products, existing tool management solutions have been unable to meet the demand, so the introduction of radio frequency technology (RFID).

RFID is a non-contact automatic identification technology developed in the 1990s. It has fast scanning, small size, anti-pollution ability and durability, reusable, penetrating and barrier-free reading, and large data memory capacity. It has strong characteristics, so it has great application potential in production data collection, monitoring and data transmission. Based on the radio frequency technology, this paper installs the RFID chip on the tool holder to realize the collection and management of tool information and reduce the overall production cost.

1 Tool management industry status and needs

Experts engaged in tool management research at home and abroad have developed a lot of tool management software, but can not meet all the requirements of tool management. The existing tool management has the following problems:

1 It is impossible to analyze the record and data of the entire life cycle of the tool, only to collect and monitor the tool information at the time point, and the data at the time of no processing can not be obtained;

2 Traditional tool management lacks M2M (Machine to Machine) information interaction, and cannot achieve integrated management;

3 Existing tool management solutions are designed to meet production needs without considering the cost of the tool throughout its life cycle.

In order to solve the above problems and achieve the goal of more intelligent automation in the manufacturing industry, it is urgent to introduce new technical means to manage tool information. In the precision machining process of mobile phone components, Jinsheng Precision Components Co., Ltd. intelligently manages the use of tools in the machine tool, passes the tool parameters to the machine tool, and adds the tools to the machine tool magazine for the machining program to call. When the tool is finished, the tool production time is written into the RFID of the tool to realize real-time tool information acquisition and tool status tracking.

2 Tool information management system parameter collection and setting

The tool information management system refers to the communication between the machine equipment (such as CNC machine tools, tool setting instruments, etc.) and the RFID reader in the manufacturing unit. The wireless communication technology, CNC and RFID readers adopt serial communication technology. Achieve information monitoring and storage management of the tool during its life cycle. The entire life cycle of a tool generally includes planning, purchasing, marking, warehousing, lending, assembly, use, return, re-grinding, scrapping, and so on. This article uses the tool designed by Sigu Digital Technology Co., Ltd. (sygole). The tool holder is equipped with an RFID tag. The handle is shown in Figure 1. The RFID read/write tag takes 500ms.

Figure 1 Tool holder with RFID tag and RFID tag

The prerequisite for machine tool management is that the tool has been set up and the tool is aligned by the tool setter. In order to achieve the corresponding function of the tool, the machine needs to initialize the tool magazine and write the tool machining time into the tool holder RFID. Since the reading and writing distance of the high-frequency RFID is relatively short, when the RFID of the tool holder is read and written, the antenna is brought close to the RFID tag through the pneumatic device.

(1) Machine tool magazine initialization

To realize the intelligent transmission of CNC tool information, we must first rely on CNC machine tools. In order to ensure that the tool magazine is automatically loaded into the machine tool and the tool parameters are read from the RFID tag into the machine tool magazine, the machine tool library needs to be initialized. The specific process is as follows:

1 When the machine tool has a tool change, the machine tool needs to control the cutter head to rotate one turn (see Figure 2), and reinitialize all the tools to the machine tool magazine;

2 For each knife, the following operations are required: the CNC drives the cylinder to raise the RFID read head by command. After the cylinder is in place, the CNC acquires the state of the sensor switch and starts the operation of the RFID reader; the cylinder state is maintained for 500ms, and the CNC drives the RFID reader through the serial port communication. The writer performs a reading operation on the handle RFID chip; the cylinder is retracted, and after the CNC detects that the magnetic induction switch of the cylinder is in place, the cutter continues to operate;

3 Functions to be controlled: Add a button to the CNC operation interface. Each time the button is pressed, the cutter head automatically rotates for one week, ensuring that each tool change can be rotated for one week, and the machine tool magazine is initialized; the knife that does not directly install the knife to the machine tool is not allowed. Library handle.

Figure 2 turret cutter

(2) Tool production time record

When the tool is unloaded, the tool throughput (machining time) is written to the tool management system. The flow of writing machine machining time into the RFID of the tool holder is as follows:

1 Before the machine is unloaded or after the group of tools, the machine records the used tools, rotates the cutters, and writes the tool processing time one by one;

2 cylinder state is maintained for 500ms, CNC drives RFID reader through serial communication and writes to the handle RFID chip;

3Retract the cylinder. After the CNC detects that the cylinder magnetic induction switch is in place, the cutter head continues to rotate.

To ensure the smooth operation of the above scheme, a button must be added to the CNC operation interface. Before the knife is unloaded or after the knife is set, press the button once to rotate the machine for one week, and write the tool usage time to finally complete the tool life control. Pay attention to the operating specifications when performing the program flow operation. The program flow is shown in Figure 3.

Figure 3 program flow

(3) Tool data storage in RFID chip

Tool coding is an important piece of information that determines the uniqueness of a tool's identity, writes it to RFID, and manages each tool through tool coding. When writing the corresponding program, the nominal diameter, nominal length and corresponding program of the tool can be determined according to the specification and model of the tool, and then the corresponding diameter compensation and length compensation can be given according to the actual situation. Since the same tool can be installed on different machine tools, the same machine can also process different products. When the product is processed, abnormal conditions may occur. Therefore, the above processing information needs to be displayed during processing. Through program control, the report dynamically displays the tool code, processed product, product quantity, abnormal information, etc., as well as the tool code, tool life, tool used time and other information in the RFID record.

3 hardware system composition and software development

The hardware consists of electronic tags (RFID), antennas, readers and related data interfaces (see Figure 4). The RFID tag is a data carrier consisting of a chip and a coupling component, each RFID tag having a unique electronic code; the RFID tag antenna is a transponder antenna of the RFID tag, and the wireless RF between the tag and the controller is transmitted through communication induction. Signal, reader is a device used to read or write RFID tag information.

Figure 4 RFID composition

The system is a distributed application system, and adopting the C/S mode is more conducive to the operation of the system. The system development platform is Microsoft Visual Studio2010.Netf ramework3.5 and above, developed by C#, and the database is ORACLE.

The RFID code block used in the system is the EEPROM storage type. Since the general machine tool numerical control system is equipped with a COM serial communication interface, the RS232 communication protocol is adopted. The tool life needs to be updated in real time. In order to ensure the real-time performance of the stored data, the tool information in the chip is updated in time when the tool is changed, and the life data in the NCK variable of the numerical control system is written into the RFID chip.

summary

By installing an RFID tag on the tool for life recognition and information reading and writing of the tool life cycle, the reader is installed on the host of the CNC machine tool, as an information interaction interface between the RFID tag and the main control system , using the RFID tag as the The information carrier realizes the information interaction between the tool and the host and the host and the host to realize the prediction of the tool life. The new solution enables tool life management, reducing tool inventory by 20%, reducing tool costs by 10%, reducing preparation time by 15%, improving equipment efficiency by 10%, shortening delivery time by 10%, and reducing overall cost by more than 15%.