This is the 14806th article published by Metalworking (mw1950PUB).
Editor's Note
Old machine tools can only be retired? No，No，No！ Today, we take a look at a new idea - "brain change" and "change of heart", the original electrical control system will be transformed, replaced by a more cost-effective CNC system, so that the old equipment can be put back into use.
preface
At present, the domestic equipment manufacturing industry is in the ascendant, but the basis of equipment manufacturing, such as the research and development and use of numerical control systems, the manufacture and application of machine tool mechanical components, etc., is still a big gap with the world's advanced level. In recent years, our company from the cost and machine tool utilization, transformation of the cost performance and other aspects of the investigation, the purchase of a number of imported second-hand CNC milling machine, the batch of equipment electrical system aging, but its mechanical components have been many years of natural aging, precision casting, traditional process quenching of the basic workpiece for a long time, the better its stress and precision stability, the workpiece fatigue resistance, the stronger the deformation resistance, the higher the application value. But also because its electrical system, especially the digital control system has been eliminated products, limited to the recoverability of electrical components, the availability and reserve of spare parts and the lack of knowledge and understanding of the system in the company, the electrical system of second-hand equipment can not be used, it is necessary to "change the brain" and "change the heart", the original electrical control system will be transformed, replaced by a more cost-effective NUMERICAL control system, so that the old equipment can be put back into use.
The purpose, status quo and main content of the transformation
(1) The purpose of the implementation of the transformation of the second-hand equipment for electrical automation transformation, so that the original elimination of scrapped equipment to play its residual value, and restore the processing capacity, processing accuracy, is the main purpose of this transformation.
(2) Cnc machine tool transformation status Quo Although cnc machine tools in mainland China have developed rapidly in recent years, there is still a certain gap with the international advanced level in terms of reliability, appearance quality, product development cycle, strain capacity and equipment rigidity. In order to narrow the gap, relevant experts suggest that machine tool companies should focus on the following 6 aspects.
1) Increase efforts to implement quality engineering and improve the failure-free rate of CNC machine tools.
2) Track the international level, so that CNC machine tools to efficient, high-precision direction of development.
3) Seek a breakthrough in the ability to develop complete sets of designs.
4) Give full play to service advantages and expand market share.
5) Multi-variety manufacturing to meet the needs of users at different levels.
6) Modular design, shorten the development cycle, quickly respond to the market.
(3) The main content of the transformation of our company has a 1996 factory of a German brand CNC crankshaft milling machine, is the company's early purchase of second-hand imported milling machine, the machine tool originally used Uni-pro NC90 system, but the system and drive part of the failure rate is relatively high, the system control board and drive board are eliminated products, after damage repair difficulties, long repair cycle, and no corresponding spare parts replacement, resulting in long equipment downtime. With the development of automation technology, this machine tool has been unable to meet the automation requirements, the need for this machine tool system transformation, with FANUC αi series (the company's original reserve spare parts) servo unit and servo motor to replace the original machine tool control unit and stepper motor, can achieve multi-axis CNC linkage.
Technical requirements for electrical modification of CNC crankshaft milling machines
According to the structure and function of the original machine tool, the configuration of the numerical control system is determined, and the technical requirements for the transformation are as follows.
1) Replace the CNC system of the original machine tool with the ultra-small, ultra-thin and high-precision and efficient FANUC 0i-TD CNC system with FANUC network function. And the fanuc 0i-TD dual-path control function is selected, which can realize the simultaneous machining of two tool holders, or the independent processing of two tool holders.
2) FanUC αi series (spare parts of the company's reserve) with high speed, high precision and high energy efficiency AC digital servo unit and servo motor replace the original machine tool X1 axis, Z1 axis, A1 axis, X2 axis, Z2 axis and A2 axis servo unit and servo motor. At the same time, the X1 axis is the tool holder 1 radial movement, the Z1 axis is the tool holder 1 axis, the A1 axis is the tool holder 1 eccentric axis rotation, the X2 axis is the knife holder 2 radial movement, the Z2 axis is the knife holder 2 axis movement, and the A2 axis is the tool holder 2 eccentric axis rotation.
3) Retain the semi-closed loop feedback control of X1 axis, A1 axis, X2 axis and A2 axis of the original machine tool. The Z1 axis and Z2 axis of the original machine tool are changed from semi-closed-loop control to full closed-loop control, and the grating ruler is added. After the completion of the machine tool transformation, the positioning accuracy and repeat positioning accuracy of the X1 axis, Z1 axis, X2 axis and Z2 axis are detected and compensated with laser interferometer, and the positioning accuracy of each coordinate axis of the machine tool is improved.
4) Replace the I/O connection unit of the original machine tool with the I/O connection unit of FANUC 0i-TD, and use the built-in PLC of the FANUC 0i-TD system to logically control all the actions outside the machine tool.
5) Redesign and manufacture of machine tool operation station and machine tool operation panel (all the buttons and indicators on the operation panel are selected from Schneider products), FANUC 10.4in (lin=0.0254m) LCD color LCD display and Japan's original external hand crank pulse operation box.
6) Replace the feedback cable of the original machine tool X1 axis, Z1 axis, A1 axis, X2 axis, Z2 axis and A2 axis with the original fanuc original servo motor feedback cable, and replace the original machine tool X1 axis, Z1 axis, A1 axis, X2 axis, Z2 axis, A2 axis and the power cable of the two spindles with the power cable of the German cable spectrum.
7) Retain the original machine tool electrical cabinet, redesign and make a strong electric control panel. All high-power components are made from Siemens or Schneider brands.
8) Retain the control mode and spindle motor of the two spindle motors of the original machine tool, reconfigure the soft starter, rewir the wiring, make it connected with the new 0i-TD system, and control it through the internal PLC program of the system.
9) The X-axis and Z axis of the original machine tool are controlled by one motor to be driven by two motors separately, and the gear reducer of the original machine tool is removed. Four gearboxes were redesigned (the last gear transmission was retained), and four servo reducers were added at the same time to replace the original gears and clutches to eliminate the gap between the gear transmissions.
10) According to the structure and action requirements of the original machine tool, the electrical design of the machine tool and the PLC control program design are re-carried out.
Cnc crankshaft milling machine after the transformation of the composition and key action design
(1) The transformed machine tool after the transformation of the machine tool electrical control part is shown in Figure 1. Its electrical control part is composed of machine tool electrical cabinet, CRT/MDI operation panel and machine tool operation panel.
Figure 1 The transformed machine
1) The machine tool electrical cabinet cabinet is equipped with Japanese FANUC A series servo units, including X1 axis, Z1 axis, A1 axis, X2 axis, Z2 axis and A2 axis, FANUC 0i -TD cnc system, I/O interface circuit, and grating ruler interface board.
2) CRT/MDI operation panel CRT/MDI operation panel is installed above the operation station, and the function of each button can be consulted in the user manual [1].
3) The machine operation panel Of the machine tool operation panel is shown in Figure 2, and the function of each button is described accordingly in the key action design and the control of the main moving parts.
Figure 2 Machine tool operation panel
(2) Key action design The key action design for dual-channel control, machine tool axis control and interlock signal is as follows.
1) Dual channel control. The retrofit uses the FANUC 0i-TD control system, which is dual-channel, each channel is equivalent to a separate system that can control the corresponding axis movements separately. When performing machine control in MDI and automatic mode, it is necessary to distinguish the current channel and display it in the lower right corner of the display screen: path 1 (i.e. channel 1) or path 2 (i.e. channel 2). For the same instruction, for example: GO G91 X100; if this is channel 1, the X1 axis moves; if it is channel 2, the X2 axis moves. Channel switching is via the switch button on the operator panel [2].
2) Control of each axis of the machine tool. In this CNC milling machine, there are 6 CNC axes, of which Channel 1 controls 3 CNC axes, which are X1 axis, Z1 axis and A1 axis; Channel 2 controls 3 CNC axes, which are X2 axis, Z2 axis and A2 axis, of which the front and back movement of the machine tool is along the X axis, the lateral movement of the machine tool is along the Z axis, and the rotational movement of the cutterhead is along the A axis.
3) Interlock signal of each axis. When moving, the X1 axis hydraulic locking pressure detection must be disconnected and opened automatically. The Z1 axis position must be within the set range, that is, out of the chuck area, allowing the X1 axis to move, when the "dual channel run" button and the adjacent left blank key are pressed at the same time, in the handwheel mode, the X axis can be moved. This design is intended for use in the center of the cutterhead so that the X axis is not affected by the conditions set by the position of the Z axis. The Z1 axis hydraulic locking pressure detection must be disconnected when moving, and it is automatically disconnected, the center frame is released, the left chuck is clamped, and the left guard is opened.
Control of major moving parts
(1) Cutterhead rotation control The spindle of this machine tool is controlled by an ordinary three-phase motor, and the starting adopts Siemens soft starter control for smooth acceleration. The spindle speed is about 80r/min. A speed detection switch is installed on the side of the spindle drive gear, and when there is a mechanical problem during the rotation, the machine is alarmed in time and the machine tool is stopped [4].
(2) Cutterhead rotation start and stop precautions When the "unload left cutterhead" button is pressed, the corresponding left cutterhead will not be able to rotate, and when the "unload right cutterhead" button is pressed, the corresponding right cutterhead will not be rotated. When there is an emergency stop alarm after the cutterhead starts, it will cause the cutterhead to stop, and the soft starter alarm, the soft starter in the electrical cabinet is red, and the soft starter needs to be reset to eliminate the alarm [5].
(3) The disassembly action of the cutterhead When the cutterhead of the machine tool needs to be removed, the cutterhead needs to be stopped. If you remove the left cutterhead, open the Z1 axis to the right to a suitable safe position, long press the "Remove Left Cutterhead" button, about 1s can be, remove the left cutterhead light will flash. If you remove the right cutterhead, open the Z2 axis to the left to a suitable safe position, long press the "Remove Right Cutterhead" button, about 1s can be, remove the right cutterhead light will flash. When the light flashes, the cutterhead will not rotate. Then remove the shroud from the center frame and manually move the corresponding X-axis out of the center frame range. After changing the tool, first move the X axis back to the center of the cutterhead, then press and hold the corresponding "Unload Cutterhead" button for about 1s, and then move the Z axis back to the machining position after the light goes out.
It should be noted that if the cutterhead is opened, the "unload left cutterhead" and "remove right cutterhead" indicators must be lit until the X axis of the machine tool is restored to its original position, and then press the button to cancel the action, otherwise there will be serious consequences. Because the X axis of the machine tool has a hydraulic locking, so when the X axis is opened, the locking hydraulic will have nowhere to seal, resulting in a large amount of oil leakage, and even the sealing ring is broken; when the unloading cutterhead function takes effect, the corresponding X axis of the machine tool will not be locked and will not leak oil.
(4) Chuck and top control in the manual state, press the "left chuck clamping" button, the left chuck will be clamped, the indicator light is on; press the "left chuck release" button, "left chuck will be released" release light. Other manual buttons such as "Left Stop Forward", "Right Top Forward", "Right Chuck Release", "Center Rack Release" and "Center Rack Clamp" are similar.
In the automatic state, press the "Clamp" button, and the action sequence is the right top forward stop, the left chuck clamps the right chuck clamps and the light turns on after the clamping is complete.
Press the "Release" button, the action sequence so far so that the mouth release the right chuck release the left chuck to release the right top back after the completion of the light.
It should be noted that when compiling a manual control PLC program, it is necessary to first top the right tip, and then let the right chuck clamp, otherwise it is easy to damage the machinery.
(5) The movement of the tailstock is in the manual state, the Z2 axis is opened out of the chuck area to reach a safe position; at the same time, the two tailstock movement keys are held for about 1s, and the two indicator lights flash at the same time; release the left and right screws that fix the tailstock, and manually pull the hydraulic valve 5S25 handle above the tailstock before and after to move the tailstock.
Conclusion
Through electrical transformation, solve the problems of the original machine tool control system and position feedback system, so that the machine tool has high precision and accurate position compensation function, so that the old equipment is revitalized.
CNC machine tools are used more and more widely, and the market capacity is also larger, but competition will also intensify. Machine tool use enterprises can not fundamentally solve the current problems in the domestic equipment manufacturing industry, although a large number of domestic equipment, but high precision, high speed and high strength requirements of the equipment still need to be imported from abroad. The way to independently transform second-hand equipment can shorten the gap with advanced equipment manufacturing technology, absorb foreign advanced machine tool technology, and also save a lot of costs for enterprises. The price of domestic equipment at the same level is more than 3 million yuan, the price of imported new equipment is 7 million to 9 million yuan, and the price of purchasing second-hand imported equipment is 800,000 yuan, plus the transformation cost is about 900,000 yuan, which can save more than 7 million yuan in costs compared with the purchase of imported new equipment, and the economic benefits are significant.
bibliography:
Beijing Fanuc Electromechanical Co., Ltd. FANUC Series 0i-MODEL D/ FANUC Series 0i Mate-MODEL D Lathe System/Machining Center System General User Manual[Z]. 2012.
Beijing Fanuc Electromechanical Co., Ltd. FANUC Series 0i-MODEL D/ FANUC Series 0i Mate-MODEL D Parameter Specification[Z]. 2012.
Beijing Fanuc Electromechanical Co., Ltd. FANUC Series 0i-MODEL D/ FANUC Series 0i Mate-MODEL D Maintenance Manual[Z]. 2012.
Xu Kaitao. Research on Problems and Countermeasures in Installation and Commissioning of Electrical Equipment[J]. China Equipment Engineering, 2020(6):87-88.
[5] Zorrian. Research on problems existing in the installation and commissioning of electrical equipment and countermeasures to solve them[J]. Engineering Technology Research, 2019(5): 109-110.
This article was published in Metal Processing (Cold Working), No. 4, 2022, pages 83-86, by Tianrun Industrial Technology Co., Ltd. Chu Zhongzhi, Wang Jiyu, Yu Zhuqing. Original title: "Imported Second-hand CNC Crankshaft Milling Machine Electrical Automation Transformation and Application".
Recommend Video
Pay attention to the metalworking video number, pay attention to the industrial media with attitude
-End-