The hottest Siemens 840 channel control technology

Siemens 840 channel control technology and APC control

Abstract: Taking the automatic workbench exchange (APC) control of horizontal machining center as an example, this paper introduces the characteristics of Siemens 840 channel control technology

1 preface

the essence of the so-called channel control technology of CNC system is parallel processing. It enables the system to process multiple programs at the same time, improves the performance and reliability of the system, and reduces the cost. Using this advanced technology, the control problem of multi unit compound and multi axis machine tools can be better solved

Siemens has adopted channel control technology since 810 system, and this technology is more mature when it comes to 840 system. It not only increases the number of channels, but also introduces the concept of "op eratingmodegroup", so that the six channels can work simultaneously under six different operation modes, can perform all auxiliary functions (such as m, s, t, h, mortal D, etc.), and can control the spindle. Through the special "program and axis coordination" command (NC program command) of 840 system, the motion and control of each channel and axis can also be flexibly controlled and coordinated

the following takes the automatic workbench exchange control of tma-55opn6 horizontal machining center as an example to introduce the characteristics of Siemens 840 multi-channel control technology

2 machine tool control requirements

tma-55opn6 horizontal machining center is a fully functional horizontal machining center imported from Italy by our factory, which adopts Siemens 840 numerical control system. It has a rotary table library with 6 positions, 64 knives, and can carry out seven axis control. In addition to the five basic NC axes x, y, Z, B (rotary table) and C (spindle position control) of the ordinary horizontal machining center, in order to improve reliability and efficiency and simplify the hydraulic and mechanical transmission system, the rotation of the tool magazine and the rotation of the table magazine are controlled by the NC axis, in which the U axis is the rotary axis of the table magazine and the V axis is the rotary axis of the tool magazine. Because the tool preselection of the random tool magazine and the conveying of the worktable must be carried out at the same time when the machine tool is processed, which cannot be satisfied by the multi axis linkage function (because the seven axes are not in place at the same time). Therefore, TMA adopts Siemens 840 channel control technology

tma-55opn6 axis and channel allocation are shown in the table. Tma-55 opn6 axis and channel allocation table

axis number axis name channel operation mode group remarks 1x11 worktable left and right movement 2y11 worktable up and down movement 3z11 worktable longitudinal movement 4b11 worktable rotation 5v22 tool magazine rotation 6e33 worktable magazine rotation 7c11 spindle position control

the three channels are independently controlled by three different NC processing programs and run at the same time. The coordination between channels is controlled by PLC program, CNC R parameter CL800 special macro program instruction implementation. The control principle of channel Z and channel 3 is basically the same. Taking channel 3 as an example, this paper introduces the basic channel control method

the basic requirements of tma-55opn6 workbench exchange control are as follows:

1) the layout of workbench library is shown in the figure. The six positions are separated by 60 ° to form a 360 ° rotation axis e, where the position e=0 ° is the exchange position, and the position e=180 ° is the manual loading and unloading position. In consideration of the matching accuracy of the workbench, the workbench library adopts the fixed address installation method, and the 1 # position corresponds to e=60 °, and so on

1. Machine tool workbench 2 Exchange door 3 Workbench warehouse 4 Manual loading and unloading position 5 Loading and unloading door

schematic diagram of workbench switching device

2) during normal machining of the machine tool, it is required to automatically turn the workbench that has been processed on the workbench library to the manual loading and unloading position for loading and unloading. After the operation of the workbench library starts, first remove the workbench on the machine tool and install it into the original position, and then install the required workbench into the machine tool. The following two cases are errors: ① the worktable corresponding to the worktable on the machine tool has been installed on the worktable; ② The required workbench is machined or not installed

3) when the workbench exchange command is issued, the machine tool performs workbench exchange, and the action sequence is as follows:

① take down the workbench action: (I) channel 1 moves the X, y, Z, B axes to the specified coordinate points; Channel 3 turns the installation position corresponding to the workbench on the machine tool to the exchange position. The two channels act at the same time, and the five coordinate axes move together. (II) the conventional exchange action is controlled by the solenoid valve. (III) modify the workbench status data, set the workbench status on the exchange position to "processed", and set the workbench status on the machine tool to "no workbench", which is realized by M56 auxiliary function command through PLC program control

② the action of installing a new workbench is basically the same as that of removing it

3 control software design

in order to achieve the above actions, the machine tool uses the R parameter of 840 to represent various states. The definition is as follows:

· R800: indicates the number of workbench (1 ~ 6) installed on the machine tool now, "0" indicates that there is no workbench on the machine tool

· R801 ~ r806: indicates the status of the workbench at positions 1 ~ 6, "1" represents "unprocessed", "2" represents "processed", "4" represents that there is no workbench at this position

· r902: the workbench number (1 ~ 6) required to be transferred to the exchange position

· r903: status information of rotary axis (E) of workbench library, where: bit2=1 means that axis E has completed the action of returning to the reference point; Bit2=1 means that the e-axis has been positioned; Bit7=1 means that there is a workbench on the exchange bit now

the auxiliary action control of the automatic exchange of the workbench is realized by the following M functions:

· m53h**: write the H code into the parameter r902

· M56: use this command after the workbench on the machine tool is removed. Set R800 to "0", and now the workbench state on the exchange position is set to "2" (processed)

· M57: use this command after the machine tool is installed on the workbench. Set R800 to "the station number corresponding to the current exchange bit", and set the workbench state on the station corresponding to the current exchange bit to "4" (no workbench)

· M80 ~ M85: auxiliary function for exchange action

1) CNC program of channel 3, which is used to control the rotation of the workbench library. Its design idea is: after starting up, it can automatically complete the action of returning to the reference point; When the machine tool processes normally, send the processed workbench to the manual loading and unloading position; Complete the above actions after the automatic exchange starts

2) CNC program channel 1 of channel 1 is the main channel for normal processing. The exchange workbench command can be realized by calling subroutines to indicate that the elongation of some materials can be above 1000%. L9101 ~ l9106 respectively control the loading of worktables 1 ~ 6 into the machine tool. The principles of these six subroutines are the same

3) PLC program is responsible for the transmission of parameters and the execution of auxiliary functions. The details are as follows:

① use the data transmission function block fb62 of 840 to perform the following processing; Write the back reference point completion signal (db32d20.12), accurate position signal (db32d20.9) and workbench detection signal (switch signal) on the current exchange bit of axis e into the corresponding bit of r902; Execute the M53 instruction and write the H code after M53 into r902; Execute the M56 command, write 0 to R800, and set the workbench state on the exchange bit to "2" (processed); Execute the M57 command, write the workbench number on the exchange bit into R800, and set the workbench state on the exchange bit to "4" (no workbench)

② complete the opening/closing of the exchange door according to the M80 ~ M85 instructions and the switch state on the machine tool; Pull rod extends/retracts; Control of solenoid valves such as clamping/loosening of workbench magazine

③ it should be noted that since the rotation movement of axis e is only controlled by the parameter r902, as long as r902 is not 0, the workbench library will rotate. Therefore, when designing the PLC program, we must fully consider the starting conditions of the workbench library, and we must not easily transmit r902 in the program

④ in order to ensure that the M instruction dedicated to the workbench library is not started by wrong operation, it should be protected when designing the PLC program. For example, it is allowed to execute these m instructions only after the execution of special m and H codes, or it is started only under special conditions when the workbench library action is carried out. These are all issues that must be considered in PLC program design

4 coordination of channel control points and actions

in tma-55opn6, the action coordination between channels is undertaken by the PLC program. The key points are:

1) in order to meet the needs of adjustment and maintenance, channel 3 should have two operation modes, that is, it is always in "automatic mode" during normal operation; It is in "maintenance mode" during adjustment and maintenance. The conversion of the two operation modes can be controlled by special switches or special auxiliary functions, and the machine tool adopts the latter. For 840 system, the conversion of the two operation modes is realized by controlling db12/d5.8 ~ d5.11 signals

2) under the two operation modes, the PLC program should select different operation panel control signals. During normal operation, channel 3 only needs to process ncstart, reset and necessary channel feed stop, read start = inhibit signals> during adjustment and maintenance, all operation panel control signals must be transmitted to channel 3, so that axis e can be operated and controlled like x, y, Z and B. Channel selection is controlled by the "channel selection" key on the panel

3) even if channel 1 alarms, it is not necessary to stop the operation of channel 3 if it does not affect the normal operation of axis E. However, if channel 3 gives an alarm, channel 1 should enter the stop state immediately or wait for the end of processing, depending on the extent of the fault

in addition, relevant machine data should also be set on 840

3 conclusion

the multi-channel control function of CNC system is a new control technology developed in recent years. It can better solve the problem of multi unit and multi axis control, which is very beneficial to reduce manufacturing costs and improve system performance and reliability. (end)