CN113800412A - Tower crane mechanism overspeed protection system and method based on PLC - Google Patents
Tower crane mechanism overspeed protection system and method based on PLC Download PDFInfo
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- CN113800412A CN113800412A CN202111135485.1A CN202111135485A CN113800412A CN 113800412 A CN113800412 A CN 113800412A CN 202111135485 A CN202111135485 A CN 202111135485A CN 113800412 A CN113800412 A CN 113800412A
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- 238000000034 method Methods 0.000 title claims abstract description 23
- 238000001514 detection method Methods 0.000 claims abstract description 34
- 238000005259 measurement Methods 0.000 claims abstract description 22
- 230000008569 process Effects 0.000 claims abstract description 9
- 238000004804 winding Methods 0.000 claims description 24
- 238000004891 communication Methods 0.000 claims description 5
- 230000000007 visual effect Effects 0.000 claims description 4
- 238000004364 calculation method Methods 0.000 claims 1
- 238000010586 diagram Methods 0.000 description 5
- 238000005516 engineering process Methods 0.000 description 4
- 238000007689 inspection Methods 0.000 description 4
- 229910000831 Steel Inorganic materials 0.000 description 3
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- 238000006243 chemical reaction Methods 0.000 description 2
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B66—HOISTING; LIFTING; HAULING
- B66C—CRANES; LOAD-ENGAGING ELEMENTS OR DEVICES FOR CRANES, CAPSTANS, WINCHES, OR TACKLES
- B66C23/00—Cranes comprising essentially a beam, boom, or triangular structure acting as a cantilever and mounted for translatory of swinging movements in vertical or horizontal planes or a combination of such movements, e.g. jib-cranes, derricks, tower cranes
- B66C23/88—Safety gear
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B66—HOISTING; LIFTING; HAULING
- B66C—CRANES; LOAD-ENGAGING ELEMENTS OR DEVICES FOR CRANES, CAPSTANS, WINCHES, OR TACKLES
- B66C13/00—Other constructional features or details
- B66C13/18—Control systems or devices
- B66C13/48—Automatic control of crane drives for producing a single or repeated working cycle; Programme control
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B66—HOISTING; LIFTING; HAULING
- B66C—CRANES; LOAD-ENGAGING ELEMENTS OR DEVICES FOR CRANES, CAPSTANS, WINCHES, OR TACKLES
- B66C15/00—Safety gear
- B66C15/06—Arrangements or use of warning devices
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
- G01P3/00—Measuring linear or angular speed; Measuring differences of linear or angular speeds
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Automation & Control Theory (AREA)
- Jib Cranes (AREA)
- Control And Safety Of Cranes (AREA)
Abstract
The invention relates to the field of safety control of tower cranes, in particular to a tower crane mechanism overspeed protection system and method based on a PLC (programmable logic controller), which greatly improve the safety protection on tower crane mechanism overspeed and reduce the cost. According to the tower crane mechanism overspeed protection system based on the PLC, a plurality of detection holes are uniformly distributed on the surface of a drum side plate of the tower crane mechanism, a proximity switch is arranged on a mounting bracket of the tower crane mechanism, and the proximity switch is connected with a control module of the tower crane mechanism; the proximity switch is used for measuring the time that the adjacent detection holes pass through the proximity switch in the rotation process of the drum side plate under the current gear of the tower crane mechanism and sending the measurement time to the control module; the control module is used for recording the measurement time, comparing the measurement time with the threshold time correspondingly set for the current gear of the tower crane mechanism, judging the overspeed if the measurement time is less than the threshold time, and cutting off the output of a frequency converter of the tower crane mechanism and the power supply of a brake of the tower crane mechanism if the overspeed is exceeded. The invention is suitable for overspeed protection of the tower crane.
Description
Technical Field
The invention relates to the field of safety control of tower cranes, in particular to a tower crane mechanism overspeed protection system and method based on a PLC.
Background
With the development of dragging technology, power electronic technology and automatic control technology, the cost performance of the control system is higher and higher. A lifting (movable arm amplitude variation) control system in the field of tower cranes gradually adopts a PLC (programmable logic controller) and frequency conversion control mode to eliminate the original relay and traditional control (note: the traditional control refers to the resistance speed regulation, pole-changing speed regulation and the like of a wound-rotor motor). The functions of counting, timing, logical operation, communication and the like of the PLC are combined with the perfect self-checking function of the frequency converter, the control of the mechanism is not limited to dragging and speed regulation, and advanced sensing technologies can be utilized, so that early warning and protection of motor overheating and control logic faults are easily realized.
However, the tower crane lifting (movable arm luffing) mechanism is easy to stall, that is, the speed is out of control and exceeds a set safety value, for example, a heavy object runs at a speed higher than a rated speed or falls freely, which causes a serious accident. The main stalling reasons of the tower crane lifting (movable arm amplitude variation) mechanism are as follows: the connection failure of the winding drum and the speed reducer, insufficient output of the motor in the running process and the like.
In the prior art, in order to realize stall protection, a special stall protector product is usually adopted for speed detection and relevant signals are fed back; however, the speed measuring device has the advantages of high price, high investment, single measuring means and low safety.
Disclosure of Invention
The invention aims to provide a system and a method for overspeed protection of a tower crane mechanism based on a PLC (programmable logic controller), which greatly improve the safety protection of overspeed of the tower crane mechanism and reduce the cost.
The invention adopts the following technical scheme to realize the purpose, and the tower crane mechanism overspeed protection system based on the PLC is characterized in that a plurality of detection holes are uniformly distributed on the surface of a drum side plate of the tower crane mechanism, a proximity switch is arranged on a mounting bracket of the tower crane mechanism, and the proximity switch is connected with a control module of the tower crane mechanism;
the proximity switch is used for measuring the time that the adjacent detection holes pass through the proximity switch in the rotation process of the drum side plate under the current gear of the tower crane mechanism and sending the measurement time to the control module;
the control module is used for recording the measurement time, comparing the measurement time with the threshold time correspondingly set for the current gear of the tower crane mechanism, judging the overspeed if the measurement time is less than the threshold time, and performing sound-light alarm through the tower crane mechanism linkage table if the overspeed is exceeded, and simultaneously cutting off the output of a frequency converter of the tower crane mechanism and the power supply of a brake of the tower crane mechanism.
Further, the stroke limiter of the tower crane mechanism is provided with an encoder.
Further, the encoder is connected with the control module in an RS485 communication mode;
the encoder is used for detecting the rotation speed data of the drum side plate under the current gear of the tower crane mechanism and transmitting the rotation speed data to the control module; and the control module compares the rotating speed of the current drum side plate with a threshold speed correspondingly set for the current gear of the tower crane mechanism, if the rotating speed is higher than the threshold speed, the overspeed is judged, if the overspeed is higher than the threshold speed, the audible and visual alarm is carried out through a tower crane mechanism linkage table, and the output of a tower crane mechanism frequency converter and the power supply of a tower crane mechanism brake are cut off.
The tower crane mechanism overspeed protection method based on the PLC is applied to the tower crane mechanism overspeed protection system based on the PLC, and comprises the following steps:
step 2, sending the measured time and the rotation speed of the side plate of the winding drum to a control module;
and 4, if the tower crane mechanism is judged to be overspeed, performing sound-light alarm through the tower crane mechanism linkage table, and simultaneously cutting off the output of a tower crane mechanism frequency converter and the power supply of a tower crane mechanism brake.
Further, in step 1, the method for calculating the time for the adjacent detection holes on the side plate of the winding drum to pass through the proximity switch comprises the following steps:
the rotating speed of the side plate of the winding drum is set to be vr/m, namely the revolution per minute is v, n detection holes are uniformly distributed on the surface of the side plate of the winding drum, and the time of the adjacent detection holes passing through the proximity switch
And s represents seconds.
Further, in step 3, the obtaining manner of the threshold speed includes: and multiplying the rotating speed corresponding to the current gear of the tower crane mechanism by the set percentage to be used as a threshold speed.
Further, in step 3, the obtaining manner of the threshold time includes:
and multiplying the rotating speed corresponding to the current gear of the tower crane mechanism by the set percentage to be used as a threshold speed, and calculating the corresponding threshold time through the threshold speed.
The proximity switch is arranged on the mounting bracket of the tower crane mechanism, the time that the adjacent detection hole passes through the proximity switch is measured through the proximity switch, the proximity switch is low in cost, high in stability, fast in response and strong in anti-interference capability compared with a special stall protector, an encoder is arranged in a stroke limiter of the tower crane mechanism, the rotating speed of a side plate of a winding drum is detected through the encoder, and overspeed protection is performed when the rotating speed exceeds a set threshold value; the two schemes of the proximity switch detection time and the encoder detection speed are mutually redundant, and the safety of the tower crane mechanism is guaranteed, so that the safety protection on the overspeed of the tower crane mechanism is greatly improved, and the cost is reduced.
Drawings
Fig. 1 is a schematic structural diagram of a tower crane mechanism of the invention.
Fig. 2 is a diagram of the system component connections of the present invention.
Fig. 3 is a schematic view of the roll side panel profile 12 inspection holes of the present invention.
In the attached drawing, 1 is tower machine mechanism chassis, 2 is tower machine mechanism installing support, 3 is the reel curb plate, 4 is the inspection hole, 5 is the reel bearing, 6 is proximity switch, 7 is the stroke limiter of configuration encoder, 7-1 is the encoder, 8 is the converter, 9 is the motor, 10 is the operation panel, D is adjacent inspection hole distance, D is the inspection hole diameter.
Detailed Description
According to the tower crane mechanism overspeed protection system based on the PLC, a plurality of detection holes are uniformly distributed on the surface of a drum side plate of the tower crane mechanism, a proximity switch is arranged on a mounting bracket of the tower crane mechanism, and the proximity switch is connected with a control module of the tower crane mechanism;
the proximity switch is used for measuring the time that the adjacent detection holes pass through the proximity switch in the rotation process of the drum side plate under the current gear of the tower crane mechanism and sending the measurement time to the control module;
the control module is used for recording the measurement time, comparing the measurement time with the threshold time correspondingly set for the current gear of the tower crane mechanism, judging the overspeed if the measurement time is less than the threshold time, and performing sound-light alarm through the tower crane mechanism linkage table if the overspeed is exceeded, and simultaneously cutting off the output of a frequency converter of the tower crane mechanism and the power supply of a brake of the tower crane mechanism.
The stroke limiter of the tower crane mechanism is provided with an encoder, and the encoder is connected with the control module in an RS485 communication mode;
the encoder is used for detecting the rotation speed data of the drum side plate under the current gear of the tower crane mechanism and transmitting the rotation speed data to the control module; and the control module compares the rotating speed of the current drum side plate with a threshold speed correspondingly set for the current gear of the tower crane mechanism, if the rotating speed is higher than the threshold speed, the overspeed is judged, if the overspeed is higher than the threshold speed, the audible and visual alarm is carried out through a tower crane mechanism linkage table, and the output of a tower crane mechanism frequency converter and the power supply of a tower crane mechanism brake are cut off.
The tower crane mechanism overspeed protection method based on the PLC is applied to the tower crane mechanism overspeed protection system based on the PLC, and comprises the following steps:
step 2, sending the measured time and the rotation speed of the side plate of the winding drum to a control module;
and 4, if the tower crane mechanism is judged to be overspeed, performing sound-light alarm through the tower crane mechanism linkage table, and simultaneously cutting off the output of a tower crane mechanism frequency converter and the power supply of a tower crane mechanism brake.
In the step 1, the method for calculating the time for the adjacent detection holes on the side plate of the winding drum to pass through the proximity switch comprises the following steps:
the rotating speed of the side plate of the winding drum is set to be vr/m, namely the revolution per minute is v, n detection holes are uniformly distributed on the surface of the side plate of the winding drum, and the time of the adjacent detection holes passing through the proximity switch
And s represents seconds.
In step 3, the obtaining mode of the threshold speed comprises: and multiplying the rotating speed corresponding to the current gear of the tower crane mechanism by the set percentage to be used as a threshold speed.
In step 3, the obtaining mode of the threshold time comprises:
and multiplying the rotating speed corresponding to the current gear of the tower crane mechanism by the set percentage to be used as a threshold speed, and calculating the corresponding threshold time through the threshold speed.
The structural schematic diagram of the tower crane mechanism is shown in fig. 1, a plurality of uniformly distributed detection holes 4 are formed in a drum side plate 3, a bearing 5 of the drum side plate 3 is connected with a tower crane mechanism mounting bracket 2, a stroke limiter 7 configured with an encoder is arranged on the drum bearing 5, the tower crane mechanism mounting bracket 2 is arranged on an underframe 1 of the tower crane mechanism, and the tower crane mechanism mounting bracket 2 is provided with a proximity switch 6 and a proximity switch 6.
The connection diagram of the system elements of the invention is shown in figure 2, a proximity switch is connected with a control module PLC, a frequency converter 8 is respectively connected with the control module PLC and a motor 9, and an encoder 7-1 and a console 10 are connected with the control module PLC.
In the embodiment of the invention, the schematic diagram of 12 detection holes distributed on the side plate of the winding drum is shown in fig. 3, and the tower crane mechanism works at 6-gear frequency (speed) from small to large and respectively corresponds to the rotating speed V1、V2、V3、V4、V5、V6(unit: RPM, an abbreviation for RevolationPerMinute, i.e. revolutions per minute, representing the number of revolutions per minute of the device), at a maximum speed V6(its value can be checked by mechanism design book, sample, etc.) calculating d distance correspondent required time t6(i.e., the time for adjacent detection wells to pass the proximity switch) the formula is as follows:
V6(rev/min) ═ V6*2πrad/60s，＝V62 π/60rad/s, where rad/s denotes how many arcs are turned per second. And the proximity switch selected in this embodiment is of a flush magnetic field interference resistant type in order that the detection signal is not interfered. Meanwhile, the diameter of the proximity switch is far smaller than the aperture D, and the pulse frequency emitted by the proximity switch is far larger than t6Output frequency of corresponding frequency converter
In the scheme, D is 30mm, the diameter of the selected proximity switch is 18mm, the frequency is 1000Hz, and the detection distance is 5 mm.
The data processing time of the PLC is selected to be far longer than the frequency of the proximity switch switching value signal. Taking VIPA-300 as an example, the processing time of each type of data is less than 1 μ S. The CPU is provided with an RS485 interface
Calculating the time t as described above6The method (1) takes a speed higher than 20% of each gear as a tolerance speed (threshold speed), and tolerance time (namely, threshold time) of the passing distance d is calculated according to the tolerance speed to be t1 ', t 2', t3 ', t 4', t5 'and t 6'. For example, the allowable differential velocity v6'＝1.2v6，
After the proximity switch outputs a switching value signal to be connected into the PLC, in the running process of the mechanism, the time of the adjacent detection holes passing through the proximity switch is continuously detected through the PLC timer, and the tolerance time and the detection time are compared by using the comparator; meanwhile, the encoder detects the speed of the side plate of the winding drum, the binary system data output by the encoder is transmitted to the PLC through RS485 communication, and the data is converted into the speed by the PLC and is compared with the tolerance speed;
and once the detected time is less than the current gear tolerance time or the detected speed exceeds the tolerance speed, the sound and light alarm is immediately carried out through the linkage table, and the output of the frequency converter and the power supply of the brake are cut off to brake forcibly. The tolerance time and the tolerance speed can be calculated by setting the proportion according to actual needs.
If the running signal of the linkage table is not sent, the winding drum automatically rotates (the brake fails) due to other reasons such as line faults and the like, the protection system can send out audible and visual alarm through the PLC, and can carry out human intervention (for example, a driver immediately operates and descends to lower the load to the ground) to eliminate the faults. The hovering function of the frequency converter can be utilized, the frequency converter can automatically output torque, and the load is stopped from sliding downwards.
The invention can process the stalling accident at the sprouting stage from the low speed, and has very small impact on the brake, thereby greatly reducing the impact on the tower crane structural member and ensuring the safety of equipment personnel.
In actual work, due to the fact that the layers of the winding drum accommodating steel wire ropes are different, when stall faults occur in different layers, the linear speeds of the steel wire ropes are different, and the braking force requirements of the tower crane mechanism brake are different. Therefore, in order to ensure that the stall protection is effective in the operation process of the outermost ring of the steel wire rope, the moment of the brake needs to be checked and selected according to the rated load of the outermost layer.
When the tower crane mechanism normally parks, the PLC monitors and compares a control signal, a proximity switch signal and an encoder signal, and once abnormal signal changes of the two detection devices occur, the fault of the detection device is judged, and at the moment, another alarm signal is sent to the cab, so that the self-detection of the detection device is completed.
In conclusion, the invention greatly improves the safety protection on the overspeed of the tower crane mechanism and reduces the system cost.
Claims (7)
1. The tower crane mechanism overspeed protection system based on the PLC is characterized in that a proximity switch is arranged on a mounting bracket of the tower crane mechanism and is connected with a control module of the tower crane mechanism;
the proximity switch is used for measuring the time that the adjacent detection holes pass through the proximity switch in the rotation process of the drum side plate under the current gear of the tower crane mechanism and sending the measurement time to the control module;
the control module is used for recording the measurement time, comparing the measurement time with the threshold time correspondingly set for the current gear of the tower crane mechanism, judging the overspeed if the measurement time is less than the threshold time, and performing sound-light alarm through the tower crane mechanism linkage table if the overspeed is exceeded, and simultaneously cutting off the output of a frequency converter of the tower crane mechanism and the power supply of a brake of the tower crane mechanism.
2. The PLC-based tower crane mechanism overspeed protection system according to claim 1, characterized in that the travel limiter of the tower crane mechanism is configured with an encoder.
3. The PLC-based tower crane mechanism overspeed protection system as claimed in claim 2, wherein the encoder is connected with the control module in an RS485 communication manner;
the encoder is used for detecting the rotating speed of the drum side plate under the current gear of the tower crane mechanism and transmitting the rotating speed to the control module; and the control module compares the rotating speed of the current drum side plate with a threshold speed correspondingly set for the current gear of the tower crane mechanism, if the rotating speed is higher than the threshold speed, the overspeed is judged, if the overspeed is higher than the threshold speed, the audible and visual alarm is carried out through a tower crane mechanism linkage table, and the output of a tower crane mechanism frequency converter and the power supply of a tower crane mechanism brake are cut off.
4. The tower crane mechanism overspeed protection method based on the PLC is applied to the tower crane mechanism overspeed protection system based on the PLC in claim 3, and is characterized by comprising the following steps:
step 1, measuring the rotating speed of a side plate of a winding drum and the time of an adjacent detection hole on the side plate of the winding drum passing through a proximity switch under the current gear of a tower crane mechanism;
step 2, sending the measured time and the rotation speed of the side plate of the winding drum to a control module;
step 3, the control module compares the measurement time with a threshold time correspondingly set by the current tower crane mechanism gear or compares the rotating speed of the current reel side plate with a threshold speed correspondingly set by the current tower crane mechanism gear, and if the measurement time is less than the threshold time or the rotating speed of the reel side plate is greater than the threshold speed, the overspeed is judged;
and 4, if the tower crane mechanism is judged to be overspeed, performing sound-light alarm through the tower crane mechanism linkage table, and simultaneously cutting off the output of a tower crane mechanism frequency converter and the power supply of a tower crane mechanism brake.
5. The PLC-based tower crane mechanism overspeed protection method according to claim 4, wherein in the step 1, the calculation method of the time for the adjacent detection holes on the side plate of the winding drum to pass through the proximity switch comprises the following steps:
the rotating speed of the side plate of the winding drum is set to be vr/m, namely the revolution per minute is v, n detection holes are uniformly distributed on the surface of the side plate of the winding drum, and the time of the adjacent detection holes passing through the proximity switch
And s represents seconds.
6. The PLC-based tower crane mechanism overspeed protection method according to claim 4, wherein in step 3, the threshold speed obtaining manner comprises: and multiplying the rotating speed corresponding to the current gear of the tower crane mechanism by the set percentage to be used as a threshold speed.
7. The PLC-based tower crane mechanism overspeed protection method according to claim 6, wherein in step 3, the threshold time obtaining manner comprises:
and multiplying the rotating speed corresponding to the current gear of the tower crane mechanism by the set percentage to be used as a threshold speed, and calculating the corresponding threshold time through the threshold speed.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111135485.1A CN113800412A (en) | 2021-09-27 | 2021-09-27 | Tower crane mechanism overspeed protection system and method based on PLC |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202111135485.1A CN113800412A (en) | 2021-09-27 | 2021-09-27 | Tower crane mechanism overspeed protection system and method based on PLC |
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| CN214192364U (en) * | 2020-05-28 | 2021-09-14 | 北京萨达智能技术有限公司 | Tower crane area protection control device based on field operation setting |
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- 2021-09-27 CN CN202111135485.1A patent/CN113800412A/en active Pending
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20100237306A1 (en) * | 2009-03-17 | 2010-09-23 | J. R. Clancy, Inc. | Hoist with Overspeed Protection |
| CN101665220A (en) * | 2009-09-25 | 2010-03-10 | 四川建设机械（集团）股份有限公司 | Variable-frequency speed-regulating control system of crane |
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