A Brief Introduction to Research and Development of Large-scale Parts NC Machining Production Line

implementation plan.

DNC network technology application. Develop communication interface for practical management software.

Reliability numerical control test and improvement. In accordance with the requirements of reliability growth, tests, records, and analyses are carried out to provide sufficient and reliable data support for the improvement of domestic CNC machine tools and CNC systems.

The large-scale CNC machining production line has 2 large horizontal CNC milling machines, 1 vertical CNC milling machine, 1 horizontal machining center, 1 gantry machining center, and 2 vertical-horizontal conversion machining centers. Among the equipped CNC systems, domestic CNC systems account for more than 50%. The DNC network transmits the NC machining program generated by CAD/CAM; it has the function of production scheduling management. Information distribution uses multiplexers.

This production line realizes the automation, intelligence, network and real-time performance of the DNC production method through network connection. The networking project includes a Windows98 PC, a taemc320T serial communicator from Taiwan M0XA company, the cable uses GAT5 shielded twisted pair, and the two ends are installed with FC232 long-line drivers to solve the problem of long-distance transmission reliability. It uses 232 ports and 7 CNCs. The equipment realizes half-duplex communication. The network can transmit the NC code generated by the CAM software to the numerical control equipment, and at the same time, it can also return the program used by the numerical control equipment to the PC for backup or use in another equipment; the hard disk of the PC is provided for each Folder, save the NC programs used by the machine tool and the NC programs to be used in their respective directories, so that they can be transferred and called at any time. The PC, C32T communication serial port and long-term driver are centrally placed in the central control room. In order to avoid electromagnetic interference, the cables are routed through galvanized pipes. The longest transmission distance can reach 12km. The transmission software uses the built-in CAM communication software and Each system comes with its own transmission software, and the software network block diagram is as shown.

Equipment Equipment Equipment Equipment Equipment During the operation of the production line, we have conducted reliability tests on a total of 6 sets of four equipment using different numerical control systems, and filled out the reliability test report in detail. In the reliability test, a total of 12 general failures occurred, and a total of 2 major failures. The mean time between failures was MTBF>500h. In addition to detailed records of the failures, we reported them to relevant departments and analyzed the reasons in time. , The formulation of improvement measures has greatly improved the company’s large-scale CNC machine tool manufacturing level and shortened the machine tool assembly cycle.

When our company puts the DNC production line into operation, first determine the processing technology of the workpiece to be processed, and process it according to the process route. Complete the optimization analysis of the process of the processing object system, combined with the application of CAD/CAM technology, optimize the analysis of the workpiece according to the group technology, determine the process plan and implementation countermeasures, so that the processing technology is scientific and reasonable, the processing accuracy, quality is stable, and the processing efficiency Significantly increase and reduce production costs.

The application of DNC network technology has realized the network, automation and flexibility of CNC machine tool processing, control and management. The development of this production line successfully solved the key technology of our company’s machine tool production and filled the blank of the large-part CNC machining production line in the machine tool industry, and passed the national acceptance in December 2000.

3. Existing problems and prospects Our company started from the self-catering Huawu Kangxi Huajiyu bookmark 0□ Zhang Wenyi Zhang Lei bookmark1 under the conditions of market changes, product structure adjustments, and shortage of funds.

Cummins engine PT fuel system testing usually uses special testing equipment, which often causes: ①High equipment costs; ②Removing the PT system from the engine for testing not only affects production, but also brings new failures due to disassembly and assembly; ③The abnormal working of the diesel engine is not only the failure of the fuel system, but often the fault judgment causes unnecessary losses. Under this premise, we have designed a portable Cummins engine tester.

1. It can measure the actual power, speed and temperature of the engine; 2. The measurement of engine PT system parameters and the test of intake pressure fluctuation; 3. Use the starting voltage drop to measure the cylinder compression pressure.

itself has a coupling (because the photoelectric encoder shaft cannot bear radial force and axial force), the front end of the coupling is designed with a fork shaft to connect with the engine counter to obtain the engine speed signal.

type) pressure, PT pump outlet pressure, oil pressure, etc. The sensor is equipped with an amplifier, and the output voltage signal is DC 1-5V. The output linearity is very good. It is directly connected to the outlet of the PT pump, the intake manifold (with damping), etc.

*High speed 5000r/min output voltage 0.4-5.0V drive voltage 4.75-13.2V output pulse rise and fall time 1.0/1S speed sensor pressure sensor amplifier pressure sensor voltage sensor amplifier isolation voltage divider serial communication terminal computer-printer meter 2KYB- The main parameters of Type 4 pressure transducer: output voltage signal 1-5V accuracy 5% power supply 12 ~ 15V pressure overload 150% structure block diagram We use 51 single-chip microcomputer (CPU 8031) for development, A/D conversion interface (0809) for analog signal processing , Used to measure voltage, pressure (PT pump pressure, ambient pressure, intake pipe pressure, etc.), temperature (environment, part surface, exhaust temperature, etc.), digital quantity is directly sent to 8031; measurement, storage and display under program control , And then send the measurement result to the printer from the serial communication port, or send it to the computer for data storage and curve drawing. For the convenience of use, the equipment power supply adopts AC 220V or DC 12V and the development needs of the body industry have researched and developed a large-scale CNC machining production line for machine tools, and completed the national key scientific and technological research project. The system status collection is supplemented and perfected, the transmission software is unified, the computer production management system needs to be improved, and the DNC network needs to be further expanded.

We will further strengthen the construction of digital network engineering supporting the production line; based on the establishment of a CNC special-shaped box parts production line and a CNC workshop for small and medium-sized shaft sleeves, the four parts of modeling, processing, measurement, and robot operation will be integrated, namely 4M system, to achieve rapid manufacturing, rapid measurement, rapid modeling and operation; continue to improve the processing production line and DNC network technology to solve existing problems; explore the development direction of CIMS.

1. Use the starting voltage drop to measure the cylinder pressure. Since the starter current is proportional to the cylinder pressure, and the starter starting current is proportional to the voltage drop of the battery when starting, a large battery voltage drop means that the pressure of the cylinder is high at the end of compression; conversely 2. The engine power is measured using no Load acceleration dynamometer method, the inherent coefficient A of the BPA engine-under no load, when the throttle is fully opened, the time required for the engine to rise from n, (generally 100Or/min) to the rated speed (time unit is 8) ) When determining the inherent coefficient, first select a new engine, and use the rated power shown on the nameplate (as the P value of formula ①) to measure A, and then the A value of the model can be obtained.

For example, the NH-220-CI diesel engine used in the D-80 bulldozer has a rated power of 132kW. Under no load, the time required for the engine speed to rise from lr/min to the rated speed of 1850r/min is measured as Ae=0554s, Then /1 = 73.1. Set the value of 4 in the test program, when the At is measured for the same type of engine, the actual power of the engine can be measured by the tester.