CN1687854A - Spacing protector for numerically controlled machine tool and its method - Google Patents
Spacing protector for numerically controlled machine tool and its method Download PDFInfo
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- CN1687854A CN1687854A CN 200510020810 CN200510020810A CN1687854A CN 1687854 A CN1687854 A CN 1687854A CN 200510020810 CN200510020810 CN 200510020810 CN 200510020810 A CN200510020810 A CN 200510020810A CN 1687854 A CN1687854 A CN 1687854A
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Abstract
The invention discloses a spacing protecting device for digital controlled machine tool, solving the accident problem of the digital controlled machine tool caused by the PLC not outputting any accident processing signal as the supply terminals of the existing spacing protecting device does not contact well with or is cut off the input-end line of the PLC. And its character lies in that: the operating contact of a spacing travel switch is a normally closed contact and the PLC input port of the digital control system is set as a negative logic, and it has two setting methods of: 1. implementing by writing the PLC program; 2. implementing by setting the parameters of the digital controlled machine tool. It inputs a group of data into the PLC for setting the logic state of the input port, and adopts XOR logic operation to implement the conversion of '1' and '0'; sets some bit in the group of data to be '1' and makes the logic state of the PLC input terminal be negative logic by the XOR logic operation.
Description
Technical field
The present invention relates to the control system of numerically-controlled machine, especially its limiting and protecting device and method thereof.
Background technology
Each kinematic axis stroke of numerically-controlled machine need be controlled in the scope of design permission, and the excess of stroke promptly equipment or personal injury accident can take place.
The limiting and protecting device of existing numerically-controlled machine as shown in Figure 1; the normally opened contact SQ1 of limitation travel switch connects respectively+input end of 24V power supply terminal and PLC; the input port of PLC is the positive logic setting; when machine tool motion in allowed limits, the input end of PLC disconnects with+24V power supply, the photoelectric coupled device in the PLC does not have; light emitting diode is not luminous; the signal logic value is " 0 ", and PLC is judged as invalid, and PLC does not have the output of accident treatment signal.When the machine tool motion excess of stroke, depression stroke switch, its normally opened contact SQ1 closure, + 24V power supply is applied to the input end of PLC, and the photoelectric coupled device in the PLC gets electric, lumination of light emitting diode, the signal logic value is " 1 ", and PLC is judged as effectively, and PLC promptly exports the accident treatment signal.
Its shortcoming is: when the machine tool motion excess of stroke, during the depression stroke switch, if+24V power supply terminal is to the circuit loose contact or the open circuit of PLC input end, + 24V power supply can not be applied to the PLC input port effectively, the signal logic value is " 0 ", it is invalid to be judged as, and PLC can not export the accident treatment signal, will cause lathe major accident to occur.
Summary of the invention
The technical problem to be solved in the present invention provides a kind of no matter circuit loose contact or whether opens a way, and all can guarantee limiting and protecting device and method thereof that machine tool motion can the excess of stroke.
The technical solution used in the present invention is:
A kind of limiting and protecting device of numerically-controlled machine, comprise the terminal of the limitation travel switch of each kinematic axis of lathe, the machine tool numerical control system with programmable controller PLC, connection control power supply, a pair of make contact of described limitation travel switch connects the input port of control power supply terminal and PLC respectively; The make contact of described limitation travel switch adopts normally closed contact; Described PLC input port is the negative logic setting, connects the control power supply when the PLC input port, and when the logical value of input signal was " 1 ", PLC was judged as invalid, the output of accident free processing signals; When PLC input port and the disconnection of control power supply, when the logical value of input signal was " 0 ", PLC was judged as effectively, output accident treatment signal.
Described machine tool numerical control system adopts Siemens SINUMERIK802S system.
The PLC input port of above-mentioned numerically-controlled machine is set to negative logic two kinds of methods:
The first for the input terminal of needs employing negative logic, uses needs the place of the normally opened contact of this input terminal to substitute with normally closed contact in program, needs is used the place of normally closed contact substitute with normally opened contact, makes it to constitute the negative logic relation.
It two is, realizes by setting lathe parameter, imports one group of data to PLC, is used for the logic state of set input mouth, adopts the XOR computing to realize the conversion of " 1 " and " 0 "; A certain position in these group data is set at " 1 ", and making the logic state of corresponding PLC input terminal by the XOR computing is negative logic.
XOR also has two kinds of implementation methods:
(1). realize XOR with software, the CPU by PLC carries out XOR.
(2). realize XOR with hardware,, carry out XOR with this circuit at the preposition translation circuit that contains XOR of the input end of PLC.
As mentioned above, the make contact of limitation travel switch adopts normally closed contact, and the PLC input port is set to negative logic, when machine tool motion was in normal travel, the normally closed contact of travel switch was kept closed, and the logical value of input signal is " 1 ", PLC is judged as invalid, no signal output; When machine tool motion excess of stroke depression stroke switch, the normally closed contact of travel switch disconnects, and the logical value of input signal is " 0 ", and PLC is judged as effectively, output accident treatment signal; When power supply terminal occurring to the circuit loose contact of PLC input end or open circuit, the logical value of input signal also is " 0 ", PLC is judged as effectively, output accident treatment signal, lathe can not move, must be under the good situation of circuit contacts, lathe could normally move, and this has just guaranteed the safety of lathe.
Description of drawings
Fig. 1 is the circuit diagram of existing numerically-controlled machine limiting and protecting device.
Fig. 2 is the circuit diagram of this numerically-controlled machine limiting and protecting device.
Fig. 3-a is the stop portion PLC source program that adopts the positive logic input.
Fig. 3-b is the stop portion PLC source program that adopts the negative logic input.
Fig. 4 is the circuit diagram of hardware XOR.
Fig. 5 is a hardware XOR processing flow chart.
Fig. 6 is a software XOR processing flow chart.
Embodiment
In numerical control of machine tools transformation or Design of CNC System, when being input to digital control system, adopts the detection signal that relates to machine safety negative logic input technology, the reliability and the security that help improving numerically-controlled machine.If the circuit of lathe adopts elements such as traditional relay, contactor to realize logic function then should not adopt negative logic, because he can cause part relay, contactor to be in "on" position all the time.This can cause problems such as loss is big, element intensification, the lost of life, also can cause misoperation because of factors such as vibrations.Modern its steering logic of digital control system is realized by the logic electronics circuit, above problem can not occur.
Conceptual illustration
1. the positive logic of input terminal input
Certain input terminal and control power supply (be generally+this input terminal is imported effectively when 24V) constituting the loop, and logical value is " 1 ", and digital control system is made response according to logical relation.When the loop of this input terminal and external power supply disconnected, this input terminal input was invalid, and logical value is " 0 ", and digital control system does not have response to this input terminal.
2. the negative logic of input terminal input
Certain input terminal and control power supply (be generally+when 24V) constituting the loop this input terminal input invalid, logical value is " 0 ", digital control system does not have response to this input terminal.When the loop of this input terminal and external power supply disconnected, this input terminal input was effective, and logical value is " 1 ", and digital control system is made response according to logical relation.
Realize that the negative logic input needs software, hardware two aspects to cooperate.
Hardware connects, the input terminal of PLC has following two kinds of connected modes in the numerically-controlled machine, connected mode wherein shown in Figure 1 is the positive logic input, its principle is: depression stroke switch S Q1 when the machine tool motion excess of stroke, photoelectric coupled device in the closed PLC of SQ1 gets, PLC thinks that the logical value of this input terminal is " 1 ", and signal is effective, and PLC carries out associative operation.The shortcoming of this method be when from+24V terminal to the circuit loose contact the PLC input terminal or open circuit then can cause SQ1 invalid (closure) even SQ1 is depressed, and cause lathe major accident to occur.
Shown in Figure 2 is the connected mode of negative logic input, and the normally closed contact of travel switch is used in the signal input.Under normal circumstances SQ1 is closed, and the logical value of this input terminal is " 1 ", and the input terminal logical value is " 0 " when SQ1 is depressed disconnection.At this moment require this logical value " 1 " to be set at disarmed state, and logical value " 0 " is set at effective status by the parameter setting or the modification PLC program of digital control system.If from+when open circuit or loose contact appearred in the circuit of 24V terminal to the input terminal of PLC, this point was considered to effectively, and lathe can be reported to the police immediately, must connect normally operation of lathe under the good situation at circuit.This method has been got rid of the possibility that causes fault because of the limit circuit open circuit, and the security of lathe is improved.
Negative logic need change logical one into disarmed state and logical zero is an effective status, and the method that PLC is set to negative logic has two kinds:
One. when programming, realizes PLC by program
Under the situation that does not change the digital control system setting data, when perhaps employed digital control system does not possess by the input of setting data realization input terminal negative logic, can realize the negative logic input function of input terminal by the PLC program of lathe.Normally closed contact and normally opened contact exchange with input terminal in by positive logic input written program (that is: are changed to normally opened contact to the normally closed contact of the input terminal that adopts the negative logic input in program, normally opened contact changes normally closed contact into, and all the other contacts are constant) method realize the negative logic input of input terminal.
In PLC, a binary data bit in the image register of each input terminal input port, PLC when executive routine directly from image register sense data carry out logical operation.Certain state is exactly the state of corresponding input terminal normally opened contact in the data, and the state of its normally closed contact is the opposite state of normally opened contact.Its normally opened contact is not that logical zero, normally closed contact are logical one when input terminal constitutes the loop with the control power supply, and its normally opened contact is that logical one, normally closed contact are logical zero when input terminal constitutes the loop with the control power supply.
Fig. 3 is the PLC ladder diagram (a kind of method for expressing of PLC program) of X-axis stop portion in Siemens 802S digital control system, and Fig. 3-a, Fig. 3-b are respectively the PLC ladder diagrams that adopts positive logic input and negative logic input.In the PLC ladder diagram, I1.0, I1.1 are respectively the negative sense of lathe X-axis, the input terminal of forward hardware limit, I1.7 is the input terminal of excess of stroke alarm release switch, the output of Q0.7 spacing alarm, V16000000.1 is a User Alarms text display trigger bit, and V38011000.0 and V38011000.1 are the spacing information bits of negative sense, forward that PLC outputs to CNC.Because I1.7 just is used to remove the lock-out state after spacing, so adopt the positive logic input.
At Fig. 3-a is the PLC ladder diagram that adopts the positive logic input.When excess of stroke I1.0 or the pairing travel switch of the I1.1 closure that is depressed appears in lathe, the logical value of its normally closed contact changes " 1 " into from " 0 ", because the logical value of the normally closed contact of I1.7 is " 1 " at this moment, so Q0.7, V38011000.0 and V38011000.1 are effective, each stops lathe and sends warning, display alarm information.By making I1.7 invalid and make the axle of the excess of stroke get back to the normal position in conjunction with other operation.If travel switch and I1.0,11.1 and travel switch and power supply between line open circuit or loose contact all can make lathe be in tape jam work, and operating personnel can not discover.If the lathe excess of stroke, spacing also invalid even travel switch is depressed, major accident can appear in lathe.
Fig. 3-b is the PLC ladder diagram that adopts the negative logic input.Is the normally closed contact of travel switch in normal condition owing to what use, and input terminal constitutes the loop with the control power supply, and then its normally opened contact logical value is " 1 ", and the normally closed contact logical value is " 0 ", and spacing alarm is invalid, the lathe operate as normal.When the disconnection that is depressed of excess of stroke I1.0 or the pairing travel switch of I1.1 appears in lathe, the logical value of its normally closed contact changes " 1 " into from " 0 ", because the logical value of the normally closed contact of I1.7 is " 1 " at this moment, so Q0.7, V38011000.0 and V38011000.1 are effective, each stops lathe and sends warning, display alarm information.By making I1.7 invalid and make the axle of the excess of stroke get back to the normal position in conjunction with other operation.In this scheme, as long as there are open circuit or loose contact in spacing loop, spacing alarm is effective immediately, and only lathe could be worked after getting rid of line fault, has so just got rid of the possibility that causes the lathe accident because of spacing return lead fault.
Because the state of limit switch was set up when lathe energising back PLC read in the input terminal state for the first time, mistake can not occur so can guarantee the result of PLC program run.
Two. realize by setting lathe parameter
Can realize the conversion of input port logical value " 1 " and " 0 " by setup parameter, the PLC program of using the positive logic input mode to write realizes the function of negative logic.In digital control system, import one group of data, being used for the set input mouth is to adopt positive logic or negative logic.Set in these group data a certain position for " 1 " then corresponding input end just be set to the negative logic input, set in these group data a certain position for " 0 " then corresponding input end just be set to positive logic input.In Digital Logic, adopt XOR can realize the conversion of " 1 " and " 0 ", by following table its state negate behind binary data bit and " 1 " XOR as can be known, and with " 0 " XOR after keep initial value.
Table one XOR relation
| The input terminal logical value | Setting data | The result | Explanation |
| ????0 | ????0 | ????0 | Keep initial value |
| ????1 | ????0 | ????1 | Keep initial value |
| ????0 | ????1 | ????1 | Become " 1 " from " 0 " |
| ????1 | ????1 | ????0 | Become " 0 " from " 1 " |
Realize that by the method for setting lathe parameter the realization principle of negative logic is to realize from data of reading in and a setting data spare realization step-by-step XOR from the PLC input end.For example: to one 8 input port, if setting data is 46H (01000110B), then corresponding relation such as following table:
The corresponding relation of table two setting data and input terminal
| Input terminal number | ??7 | ??6 | ??5 | ??4 | ??3 | ??2 | ??1 | ??0 |
| Setting data | ??0 | ??1 | ??0 | ??0 | ??0 | ??1 | ??1 | ??0 |
| Logic state | Just | Negative | Just | Just | Just | Negative | Negative | Just |
Wherein 1,2, No. 6 input terminal adopts the negative logic input, and other terminals adopt the positive logic input.
The method that realizes XOR has two kinds of methods of hardware and software.
1. realize the method for XOR with hardware
Hardware realizes that the method for negative logic is at the preposition translation circuit that contains XOR of the input end of PLC, Fig. 4 is the circuit diagram of translation circuit, it is an example of this method, have only 8 input terminals, should determine input terminal quantity as required in actual applications, and employed components and parts can be selected flexibly also.U1 is 8 bit data latch 74LS73 among Fig. 4, and U2 is 8 input buffer 74LS244, and U3, U4 are or door to realize the sheet choosing and read and write logic that U5 is an XOR gate, realizes the XOR of setting data and input terminal logical value.Setting data is write in the control module of input port and latch, realize and the step-by-step XOR of input port that with this circuit this method can alleviate the burden of CPU among the PLC, improve travelling speed.Fig. 5 is the process flow diagram of this method, and when PLC energising and initialization, after CPU write data latches U1 (74LS273) to the data of setting, the state of these data and input port was realized the step-by-step XOR.If certain position is for " 1 " then the pairing input terminal in this position is a negative logic input in the data of setting.For example: the data that write latch be OFH then in Fig. 4 above 4 input terminals just be set at the positive logic input, below 4 input terminals just be set at the negative logic input.
2. realize the method for XOR with software
Software realizes that the method for XOR is that CPU by PLC carries out XOR.Because reading in the input port data all will carry out XOR, so this method can increase the CPU burden at every turn.Fig. 6 is the process flow diagram of this method.After digital control system PLC reads in the input port state,, just realized negative logic reading in data and setting data step-by-step XOR.
Realize the method for input terminal negative logic by setting lathe parameter, requiring digital control system to have can carry out the function of different set to the logical validity state of its PLC input, output port.The SINUMERIK 802S digital control system of Siemens has this function.
For the digital control system that input port adopts photoelectricity to isolate, adopt the method for negative logic input to make the light emitting diode of the photoelectrical coupler in the input circuit be in "on" position for a long time.But (have only several milliamperes because the working current of this light emitting diode is very little, input circuit only consumes tens milliwatts), therefore the increase of the power consumption of system can be ignored concerning the lathe of several kilowatts of power, and light emitting diode is a cold light source simultaneously, also can not cause system's heating.The mission life of photoelectrical coupler in every lathe continuous working every day 12 hours, can guarantee the lathe operate as normal more than 20 year greater than 100,000 hours, also can not impact life-span of lathe.
Claims (6)
1. the limiting and protecting device of a numerically-controlled machine; the terminal that comprises the limitation travel switch of each kinematic axis of lathe, machine tool numerical control system, connection control power supply with programmable controller PLC; the a pair of make contact of described limitation travel switch connects the input port of control power supply terminal and PLC respectively, it is characterized in that:
The make contact of described limitation travel switch adopts normally closed contact;
Described PLC input port is the negative logic setting, connects the control power supply when the PLC input port, and when the logical value of input signal was " 1 ", PLC was judged as invalid, the output of accident free processing signals; When PLC input terminal and the disconnection of control power supply, when the logical value of input signal was " 0 ", PLC was judged as effectively, output accident treatment signal.
2. numerically-controlled machine limiting and protecting device according to claim 1 is characterized in that: described machine tool numerical control system adopts Siemens SINUMERIK802S system.
3. the PLC input port of the described numerically-controlled machine of claim 1 is set to the method for negative logic, it is characterized in that: realize by the PLC program of writing lathe, PLC connects the input terminal of limitation travel switch, in program, use needs the place of the normally opened contact of this input terminal to substitute, needs are used the place of normally closed contact substitute with normally opened contact with normally closed contact.
4. the PLC input port of the described numerically-controlled machine of claim 1 is set to the method for negative logic, it is characterized in that: realize by setting lathe parameter, import one group of data to PLC, be used for the logic state of set input mouth, adopt the XOR computing to realize the conversion of " 1 " and " 0 "; A certain position in these group data is set at " 1 ", and making the logic state of corresponding PLC input port by the XOR computing is negative logic.
5. method according to claim 4 is characterized in that: described XOR computing is to realize with software, and the CPU by PLC carries out XOR.
6. method according to claim 4 is characterized in that: described XOR computing is to realize with hardware, at the preposition translation circuit that contains XOR of the input end of PLC, carries out XOR with this circuit.
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| CN 200510020810 CN1687854A (en) | 2005-04-29 | 2005-04-29 | Spacing protector for numerically controlled machine tool and its method |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101441460B (en) * | 2008-12-30 | 2011-01-26 | 奇瑞汽车股份有限公司 | Control method for controlling circuit for controlling device switch |
| CN102902211A (en) * | 2012-09-28 | 2013-01-30 | 烟台宝钢钢管有限责任公司 | Method for preventing malfunction of emergency stop and quick stop signals in control system |
| CN103278668A (en) * | 2013-05-13 | 2013-09-04 | 常熟理工学院 | Stepping current source |
| CN103279159A (en) * | 2013-05-13 | 2013-09-04 | 常熟理工学院 | Stepping current source device based on virtual instrument technology |
| CN104242235A (en) * | 2014-09-03 | 2014-12-24 | 天奇自动化工程股份有限公司 | Limit switch bypass in roundtripping equipment |
-
2005
- 2005-04-29 CN CN 200510020810 patent/CN1687854A/en active Pending
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101441460B (en) * | 2008-12-30 | 2011-01-26 | 奇瑞汽车股份有限公司 | Control method for controlling circuit for controlling device switch |
| CN102902211A (en) * | 2012-09-28 | 2013-01-30 | 烟台宝钢钢管有限责任公司 | Method for preventing malfunction of emergency stop and quick stop signals in control system |
| CN103278668A (en) * | 2013-05-13 | 2013-09-04 | 常熟理工学院 | Stepping current source |
| CN103279159A (en) * | 2013-05-13 | 2013-09-04 | 常熟理工学院 | Stepping current source device based on virtual instrument technology |
| CN104242235A (en) * | 2014-09-03 | 2014-12-24 | 天奇自动化工程股份有限公司 | Limit switch bypass in roundtripping equipment |
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