Invited by Shanghai Turbine Generator Co., Ltd. in l997, the author demonstrated the transformation of the machining center of the large turbo generator base of the company and performed software maintenance on the C-axis positioning oscillation problem. As a result, useful explorations have been conducted on the repair and reconstruction of large-scale used equipment, gaining considerable experience.
The base machining center is a used equipment imported from Westinghouse Company in the United States in 1992 and manufactured by American Freer. It is composed of three parts: boring machine, boring machine and turntable. The cantilever extends 7,5m, diameter is 1.5m, rotary table is 12m long, 4.2m wide, and carries 140t. It can be used to process 30o, 6o0 and 9o0MW turbine generators. Block, is a special large-scale equipment in China's turbine generator manufacturing industry. The control system of the machining center is two A-B7320 CNC systems, control side boring machine and side boring machine respectively. The control software is developed by A-B company and includes PAL. (ie PLC software). Because of the peculiarities of large CNC equipment, its PAL software and NC software are developed together. Therefore, the PAL interface software is not readable and writable, and can only be operated. This brings great difficulties to the transformation of CNC equipment. In order to thoroughly understand the PAL interface software, we conducted deciphering and analysis, identified some special problems in the design of large-scale PAL interface software, and mastered a large number of machine parameters.
I. Special problems of large CNC equipment
1. The spindles of large and medium-sized CNC machine tools generally adopt a transmission mode with gear shifting. This is to ensure that large torques can be transmitted at low speeds and that the transmission range of the constant power zone can be expanded. Since there is a gear shift, there is a “gearing†problem. Hydraulic shifters are often used on large machine tools. To prevent the phenomenon of “top gearâ€, the main motor is used to perform instant jog movements. This brings with it the following problems: 1 Large inertia The delay caused by the use of time relay detection, over a certain period of time, shows that the gear fails; 2 for the sake of reliability, the end of the file should be notified by the file limit switch hanging file file success or not; 3 Asking the jog needs to output the short-time motion command to the interface, which is difficult to implement smoothly in the PLC, because the general PAL system can not deal with the motor movement problem: 4 In order to make up for the lack of automatic gear, the manual gear is retained on the panel. The problems with the push button switch are well handled in the PAL software of the machining center.
2. Clamping and relaxing problems are more prominent in large CNC machine tools. In order to position accurately under large inertia, the axes must be clamped immediately when they reach the target position and then relaxed when they are in motion. Some axes are also divided into low clamps and high clamps to prevent jitter during clamping. These functional requirements increase the difficulty of writing interface software.
3. There is a problem with the coupling of normal NC programs and PLC programs. For example, the aforementioned C-axis high clamp and low clamp problems, the formula used to determine the high entrainment band and low entrainment band is: the end position is the current position + following error. These system parameters are not available in the PLC data area. NC and PLC (PAL) were originally developed in the original control program. There is no such problem. For the general retrofit users, there are some difficulties in extracting these system parameters.
4. The unidirectional approach is particularly important for the accurate positioning of large-scale machine tools. Many CNC systems now have this type of function and are extremely convenient in retrofitting.
5. The choice of some parameters. We found that the computer software gain KC of large CNC machine tools is very low (system position loop gain KV=KC·KD·KM·KA, see the author's monograph “Machine Tool CNCâ€), generally between 0.002 and 0.005. Since the KC value is set low, the system position loop gain KV is much lower than 1. This kind of low-gain system is easy to be stable, easy to adjust, suitable for large-scale machine tools, and the disadvantage is that the following error is slightly larger.
Second, the C axis oscillation software maintenance
The C-axis of the machining center end boring machine is a rotary shaft, which is used to process more than 100 holes on the machine frame end face. After the positioning and clamping, the Z-axis direction is used to drill the holes. Since the end of 1997, the C-axis positioning has been oscillating, unable to find the exact positioning position, and swaying, which seriously affected the processing progress. Our analysis is due to the wear of mechanical parts, resulting in the in place band can no longer meet the requirements, need to expand. This is very simple for the new CNC system, as long as the modifications are in place with parameters, but it is not an easy task for the Taiwan used equipment in the late 1970s. A—B7320 CNC machine parameters are not open to the user. Once commissioned, the machine parameters are stored in the machine parameter area (occurs as an absolute address). There are about 10 NC parameters in the machine tool parameters, including the in-position belt and the clamping belt. Only by properly expanding it, the C-axis oscillation problem can be solved. Of course, such software maintenance is temporary, and a thorough solution is to repair mechanical wear.
Third, the selection of numerical control system
This transformation is to replace the original A-B7320 CNC system with two A-B9/260CNC. At the same time there are nine coordinate DC servos that are replaced, and DC motors are temporarily not replaced. The A-B7300 series and the 9 series CNC CNC systems were born in the 1970s and 1990s, respectively, with a span of 20 years. During this period, microelectronics, computer technology, control technology, and software technology all developed at a rapid rate. Therefore, the 9 series is much better than the 7300 series in the overall level, but the 9 series system software was born entirely from the 7300 series software. This point is of great significance for successful numerical control transformation.
Both 1.7300 series and 9 series software use front and back control structures. The front-end program of 7300 series is a 10ms interrupt service program, and the important functions of CNC machine tools such as interpolation, position control, PAL (PLC), and monitoring are all included. The 9-series front-end program is still a real-time interrupt service routine, but the sampling (processing) cycle becomes 6-30ms, one step every 2ms, which provides users with great flexibility. Another difference is that the 9 series can divide the PAL program into two parts, foreground and background, to adapt to the situation of large-scale I/O point control, and to reduce foreground load before the background control is a classic real-time control method. The multilevel interrupt control method can be regarded as the variation of the front-background control, that is, the lowest level interrupt can be regarded as a background program, and the rest of the interrupt can be regarded as a foreground program.
The 730 series PAL (PLC) manual provides four 730o tape mode variables, namely the request variable, the mode indicator variable, the pre-zero after omitted variable, and the tray request variable, which is a 73o0 part-processing tape in the 9 series environment. Used to set up. This tape compatibility largely protects the user's interests and enables some proven parts processing programs to be used intact in the 9 series. From another perspective, the 9 series and 7300 series of system software have a lot of similarities and inheritance.
There are great similarities between the PAL variables provided by the 3.7300 CNC and the 9 series CNCs. For the transformation of numerically-controlled machine tools, the PAL variable is a prerequisite for writing PAL programs. The PAL variable provided by the system reflects the structure and function of the system program. The richer the PAL variable, the more flexible the development of its software, but the more difficult it is to develop the CNC system program. The 7300 series offers about 120 variables for the team. There are 281 in the 9 series. On the whole, the 9 series PAL function is much better than the 7300 series. The PAL variables used in the 7300 system can be found in the 9 series of PAL variables, which provides a lot of convenience for the numerical control transformation.
The base machining center is a used equipment imported from Westinghouse Company in the United States in 1992 and manufactured by American Freer. It is composed of three parts: boring machine, boring machine and turntable. The cantilever extends 7,5m, diameter is 1.5m, rotary table is 12m long, 4.2m wide, and carries 140t. It can be used to process 30o, 6o0 and 9o0MW turbine generators. Block, is a special large-scale equipment in China's turbine generator manufacturing industry. The control system of the machining center is two A-B7320 CNC systems, control side boring machine and side boring machine respectively. The control software is developed by A-B company and includes PAL. (ie PLC software). Because of the peculiarities of large CNC equipment, its PAL software and NC software are developed together. Therefore, the PAL interface software is not readable and writable, and can only be operated. This brings great difficulties to the transformation of CNC equipment. In order to thoroughly understand the PAL interface software, we conducted deciphering and analysis, identified some special problems in the design of large-scale PAL interface software, and mastered a large number of machine parameters.
I. Special problems of large CNC equipment
1. The spindles of large and medium-sized CNC machine tools generally adopt a transmission mode with gear shifting. This is to ensure that large torques can be transmitted at low speeds and that the transmission range of the constant power zone can be expanded. Since there is a gear shift, there is a “gearing†problem. Hydraulic shifters are often used on large machine tools. To prevent the phenomenon of “top gearâ€, the main motor is used to perform instant jog movements. This brings with it the following problems: 1 Large inertia The delay caused by the use of time relay detection, over a certain period of time, shows that the gear fails; 2 for the sake of reliability, the end of the file should be notified by the file limit switch hanging file file success or not; 3 Asking the jog needs to output the short-time motion command to the interface, which is difficult to implement smoothly in the PLC, because the general PAL system can not deal with the motor movement problem: 4 In order to make up for the lack of automatic gear, the manual gear is retained on the panel. The problems with the push button switch are well handled in the PAL software of the machining center.
2. Clamping and relaxing problems are more prominent in large CNC machine tools. In order to position accurately under large inertia, the axes must be clamped immediately when they reach the target position and then relaxed when they are in motion. Some axes are also divided into low clamps and high clamps to prevent jitter during clamping. These functional requirements increase the difficulty of writing interface software.
3. There is a problem with the coupling of normal NC programs and PLC programs. For example, the aforementioned C-axis high clamp and low clamp problems, the formula used to determine the high entrainment band and low entrainment band is: the end position is the current position + following error. These system parameters are not available in the PLC data area. NC and PLC (PAL) were originally developed in the original control program. There is no such problem. For the general retrofit users, there are some difficulties in extracting these system parameters.
4. The unidirectional approach is particularly important for the accurate positioning of large-scale machine tools. Many CNC systems now have this type of function and are extremely convenient in retrofitting.
5. The choice of some parameters. We found that the computer software gain KC of large CNC machine tools is very low (system position loop gain KV=KC·KD·KM·KA, see the author's monograph “Machine Tool CNCâ€), generally between 0.002 and 0.005. Since the KC value is set low, the system position loop gain KV is much lower than 1. This kind of low-gain system is easy to be stable, easy to adjust, suitable for large-scale machine tools, and the disadvantage is that the following error is slightly larger.
Second, the C axis oscillation software maintenance
The C-axis of the machining center end boring machine is a rotary shaft, which is used to process more than 100 holes on the machine frame end face. After the positioning and clamping, the Z-axis direction is used to drill the holes. Since the end of 1997, the C-axis positioning has been oscillating, unable to find the exact positioning position, and swaying, which seriously affected the processing progress. Our analysis is due to the wear of mechanical parts, resulting in the in place band can no longer meet the requirements, need to expand. This is very simple for the new CNC system, as long as the modifications are in place with parameters, but it is not an easy task for the Taiwan used equipment in the late 1970s. A—B7320 CNC machine parameters are not open to the user. Once commissioned, the machine parameters are stored in the machine parameter area (occurs as an absolute address). There are about 10 NC parameters in the machine tool parameters, including the in-position belt and the clamping belt. Only by properly expanding it, the C-axis oscillation problem can be solved. Of course, such software maintenance is temporary, and a thorough solution is to repair mechanical wear.
Third, the selection of numerical control system
This transformation is to replace the original A-B7320 CNC system with two A-B9/260CNC. At the same time there are nine coordinate DC servos that are replaced, and DC motors are temporarily not replaced. The A-B7300 series and the 9 series CNC CNC systems were born in the 1970s and 1990s, respectively, with a span of 20 years. During this period, microelectronics, computer technology, control technology, and software technology all developed at a rapid rate. Therefore, the 9 series is much better than the 7300 series in the overall level, but the 9 series system software was born entirely from the 7300 series software. This point is of great significance for successful numerical control transformation.
Both 1.7300 series and 9 series software use front and back control structures. The front-end program of 7300 series is a 10ms interrupt service program, and the important functions of CNC machine tools such as interpolation, position control, PAL (PLC), and monitoring are all included. The 9-series front-end program is still a real-time interrupt service routine, but the sampling (processing) cycle becomes 6-30ms, one step every 2ms, which provides users with great flexibility. Another difference is that the 9 series can divide the PAL program into two parts, foreground and background, to adapt to the situation of large-scale I/O point control, and to reduce foreground load before the background control is a classic real-time control method. The multilevel interrupt control method can be regarded as the variation of the front-background control, that is, the lowest level interrupt can be regarded as a background program, and the rest of the interrupt can be regarded as a foreground program.
The 730 series PAL (PLC) manual provides four 730o tape mode variables, namely the request variable, the mode indicator variable, the pre-zero after omitted variable, and the tray request variable, which is a 73o0 part-processing tape in the 9 series environment. Used to set up. This tape compatibility largely protects the user's interests and enables some proven parts processing programs to be used intact in the 9 series. From another perspective, the 9 series and 7300 series of system software have a lot of similarities and inheritance.
There are great similarities between the PAL variables provided by the 3.7300 CNC and the 9 series CNCs. For the transformation of numerically-controlled machine tools, the PAL variable is a prerequisite for writing PAL programs. The PAL variable provided by the system reflects the structure and function of the system program. The richer the PAL variable, the more flexible the development of its software, but the more difficult it is to develop the CNC system program. The 7300 series offers about 120 variables for the team. There are 281 in the 9 series. On the whole, the 9 series PAL function is much better than the 7300 series. The PAL variables used in the 7300 system can be found in the 9 series of PAL variables, which provides a lot of convenience for the numerical control transformation.
Cop Cars,Police Van,Motorbike For Cruiser,Motocross Road Bike
Jinan Maxview Industrial Co.,Ltd. , https://www.maxviewmoto.com