Risk assessment method for key parts of tower crane based on risk inspection technology

Abstract

The invention discloses a risk assessment method for key parts of a tower crane based on a risk inspection technology, and relates to the technical field of crane management. According to the risk assessment method for the key parts of the tower crane based on the risk inspection technology, historical fault time sequence data of equipment is taken as input, and fault failure Weibull distribution scale parameters of the key parts are estimated based on a least square method; an ADV comprehensive weight calculation method is formed by fusing an analytic hierarchy process (AHP), a decision laboratory method (DEMATEL) and a variable weight theory (VWT), and a correction calculation model of the actual failure probability of the key parts of the tower crane is constructed; and quantitative economic evaluation is carried out on failure consequences of the parts, and quantitative risk evaluation on key parts of the tower crane is completed in combination with the risk matrix, so that quantitative evaluation on the failure consequences and the failure probability of the mechanical parts of the tower crane can be realized, and theoretical support is provided for accurate risk evaluation and hierarchical management and control of the tower crane.

Description

Technical Field

[0001] The present invention relates to the technical field of crane management, and specifically to a risk assessment method for key components of tower cranes based on risk inspection technology. Background Art

[0002] With the rapid development of China's economy, the construction of construction projects and infrastructure has been continuously strengthened, and the usage of tower cranes has also been increasing year by year. At present, the main safety guarantee method for lifting machinery in China is to combine regular maintenance and annual inspection. According to the regulations, cranes need to be inspected routinely before daily work, and maintenance work needs to be carried out every month. However, due to the special working environment of tower cranes, many problems are faced in their maintenance work, such as: dangerous maintenance environment, huge maintenance workload, incomplete maintenance, etc. These problems have led to the failure to complete the maintenance work of tower cranes in a timely and in-place manner, and thus led to the occurrence of accidents.

[0003] As a typical mechatronic device, the reliability of the key components of tower cranes plays a decisive role in the safety of the whole machine. As the equipment is used for a longer time, the components of the equipment will inevitably age, greatly increasing the risk of accidents. The current maintenance method has certain limitations, it is difficult to fully cover potential risks, and it cannot comprehensively consider the differences in equipment management levels of each user unit and the diversity of the individual states of the equipment itself. In addition, due to the relatively fixed inspection items and inspection cycles, it is easy to cause over-inspection of general components in actual operation, while the inspection of key components faces problems such as untimely inspection and insufficient inspection resources. At the same time, due to the lack of in-depth analysis of the quantitative failure probability and failure consequences of the key components of tower cranes, the reference value provided in the accident prevention and maintenance strategy formulation of tower cranes is quite limited. Summary of the Invention

[0004] (I) Technical Problems to be Solved In view of the deficiencies of the prior art, the present invention provides a risk assessment method for key components of tower cranes based on risk inspection technology, and solves the problem of xxxx.

[0005] (II) Technical Solutions To achieve the above objectives, the present invention is realized through the following technical solutions: A risk assessment method for key components of tower cranes based on risk inspection technology. The key components in the present invention include 8 types of components: tower body, boom, brake, wire rope, motor, hook, pulley block, and driver's cab.

[0006] The risk assessment method for key components of tower cranes based on risk-based inspection (RBI) technology provided by the present invention adopts a two-parameter Weibull distribution combined with least squares estimation and ADV weight calculation, establishes a corrected calculation model for the actual failure probability of key components of tower cranes, and combines the quantitative economic evaluation of component failure consequences to complete the quantitative risk assessment of tower crane components through a risk matrix. Generally, it is mainly divided into three parts: (1) Calculation of the actual failure probability of key components. Based on the component failure records within a specific period, the scale parameter and shape parameter of the Weibull distribution are calculated by the least squares method to obtain the general failure probability distribution function of the component L u ( t i ); referring to "Risk-Based Inspection" (API 581), a corrected hierarchical structure model for tower crane components is constructed, the weights of each level of indicators are determined by ADV weight calculation, and the correction coefficient of tower crane components is calculated by grey comprehensive evaluation N E ; by converting the management system evaluation score into the management system evaluation coefficient value, dividing the five-level evaluation criteria, and selecting the management evaluation coefficient according to the actual situation of the equipment N M . Through the product of the above three, the actual failure probability of the component is obtained L a .

[0007] (2) Calculation of the failure consequences of key components. By statistically calculating the total price of the tower crane, the cost of personnel casualties, the daily economic loss, the unit area cleaning cost, and the component replacement and repair cost, the failure consequences of the component are calculated according to the formula.

[0008] (3) Quantitative risk assessment of key components. Based on the component failure consequences and actual failure probability obtained in the previous steps, the component risk level is judged according to the risk matrix.

[0009] More specifically, the calculation of the actual failure probability L a of the key component includes the following steps: (1-1) Calculation of the general failure probability L u of the component.

[0010] (1-1-1) Collect the historical failure time series of tower crane components during use, . t i represents the failure time, n is the total number of component failures within the statistically counted failure cycle.

[0011] Calculate the median rank F ( t i )。

[0012] ; (1 - 1 - 2) Estimate the shape parameter and the scale parameter by least - squares parameter estimation and the scale parameter 。

[0013] Process the data: ; ; ; ; Calculate the obtained shape parameter and the scale parameter ; (1 - 1 - 3)Calculate the regression sum of squares SSR and the total sum of squared deviations SST 。

[0014] ; ; (1 - 1 - 4)Calculate the goodness of fit R 。

[0015] ; R The closer it is to 1, the better the fitting effect. When , it indicates a good fitting effect.

[0016] (1 - 1 - 5)Obtain the general failure probability function of the component: ; Obtain the general failure probability of the component at this moment according to the actual working duration of the component L u 。When L u reaches the value 1 for the first time, the corresponding running time is defined as the limit life of the component t d 。

[0017] The revised hierarchical structure model of the key components of the tower crane described in the present invention includes a total of 4 secondary indicators, namely technical module, general module, mechanical module, and process module. Among them, the secondary indicators can be further divided into 11 tertiary indicators, namely failure rate, inspection effectiveness, factory conditions, weather conditions, crane complexity, crane working level, specification status, life cycle, difference between static and dynamic equipment, process stability, and safety protection.

[0018] The technical module (A1) includes the failure rate (A 11 ) and the inspection effectiveness (A 12 ).

[0019] The general module (A2) includes the factory conditions (A 21 ) and the weather conditions (A 22 ).

[0020] The mechanical module (A3) includes the crane complexity (A 31 ), the crane working level (A 32 ), the specification status (A 33 ), and the life cycle (A 34 ).

[0021] The process module (A4) includes the difference between static and dynamic equipment (A 41 ), the process stability (A 42 ), and the safety protection (A 43 ).

[0022] (1-2) The calculation of the correction coefficient of the key components of the tower crane N E includes the following steps: (1-2-1) ADV weight calculation.

[0023] By analyzing the internal relationship of indicators through DEMATEL, combining AHP and VWT to correct the indicator weights according to the indicator status values, and considering the indicator correlation and indicator status values for weight calculation, we respectively obtain , , ; AHP weight calculation: ; Among them, is the AHP weight, and is the maximum eigenvalue of the judgment matrix.

[0024] Calculate the consistency index CI : ; Calculate the consistency ratio: , when CR <0.1, it is considered that the judgment matrix meets the consistency requirement. Otherwise, adjust the judgment matrix until CR <0.1, and finally obtain the ranking vectors of each level of indicators.

[0025] Among them, RI is the random consistency index, and its value is related to the order of the judgment matrix.

[0026] AD weight calculation: Establish a direct influence matrix , and use the 5-level scaling method to obtain the direct influence matrix. Among them, is the degree of influence of the former on the latter when the i-th element is compared with the j-th element, .

[0027] Calculate the direct influence matrix N : ; Calculate the comprehensive influence matrix T : ; Calculate the independence degree I i : ; Among them, C i is the degree of being influenced,

[0028] Calculate the AD weight: ; ADV weight calculation: ; Among them, is the index status vector, is the status variable weight vector.

[0029] ; Do not ignore the role of an index in triggering other changes in the system, and select the average cause degree R as the index status vector, Select the average cause degree.

[0030] Calculate the average cause degree R : ; (1 - 2 - 2) Obtain the operation data of a tower crane on a certain day, combine the inspection situation of the inspection personnel, and according to the established three-level evaluation index corresponding evaluation criteria, obtain the sample matrix , then the sample matrix can be expressed as: ; where d ijk is the third-level index A ij of the k th test result, p is the number of tests.

[0031] (1 - 2 - 3) Calculate the correction coefficient of tower crane components according to the grey comprehensive evaluation. Set 5 evaluation grey classes, namely "very low", "low", "medium", "high", and "very high". Through the selected whitenization weight function, calculate the whitenization value, weight vector, and weight matrix of each level of index. For a third-level index A ij , its e th evaluation grey class whitenization value X ije can be expressed as: ; In the formula, d ijk is the element of the evaluation matrix D ; f e is the selected whitenization weight function, then A ij 's weight vector r ij is: ; The grey weight matrix of the secondary index R i is composed of the weight vectors of the tertiary indexes and is expressed as: ; According to the grey weight matrix of the secondary index, calculate the weight vector r i of the correction coefficient of tower crane components.

[0032] ; where is the weight vector of the tertiary indexes included in the i th secondary index, .

[0033] Obtain the correction coefficient weight matrix R of tower crane components according to the weight vector of the correction coefficient of tower crane components: ; Finally, the correction factor of tower crane components is calculated according to the weight vector of secondary indicators and the weight matrix of correction factors of tower crane components. N E 。

[0034] ; Among them, V represents the 5-level grey class and its corresponding score, V =[9, 7, 5, 3, 1] T , is the weight vector of secondary indicators.

[0035] (1 - 3) The management evaluation coefficient corrects the general failure probability according to the equipment management level of the tower crane user unit. Compare the equipment management level of the tower crane user unit with the industry average management level. Its calculation is as follows: ; Among them, x is the ratio of the equipment management level to the industry average management level.

[0036] By converting the management system evaluation score into the management system evaluation coefficient value, taking x = 0.5 as the industry average management level score value of the crane industry, and dividing the 5-level evaluation standard. In actual application, generally take 1, as shown in Table 1. It means that the tower crane management level of this user unit reaches the industry average management level.

[0037] Table 1 Values of management evaluation coefficient

[0038] (1 - 4) The calculation of the actual failure probability of key components is as follows: ; Among them, L a is the actual failure probability; L u is the general failure probability; N E is the correction factor; N M is the management evaluation coefficient; The failure of key components of tower cranes often leads to tower crane accidents, resulting in more serious consequences. The assessment of the failure consequences of key components of tower cranes mainly considers three aspects: casualties, economy, and environment. The losses in these three aspects are all converted into economic indicators for calculation, and finally the total economic loss cost is calculated and compared with the cost of the entire crane equipment. The failure consequence level is divided according to the proportion. The specific steps for calculating the failure consequences of key components are as follows: (2-1) Calculation of casualty costs R i Tower crane accidents may result in casualties. The casualty costs are calculated as follows: ; R HD The casualties caused by tower crane accidents are converted into economic losses, 10,000 yuan / person; is the population density of the production plant, person / m 2 ; is the area affected by the accident, m 2 .

[0039] (2-2) Calculation of economic loss costs R E The economic loss costs of tower cranes include three aspects: equipment downtime loss costs R s , Repair and replacement costs R RM , other expenses R m .

[0040] Equipment downtime loss costs R s It means that during the period of handling a crane accident at a production and operation site, the enterprise is unable to maintain normal production activities, resulting in economic losses.

[0041] ; in, R L The economic loss caused by the company's shutdown for each day is RMB 10,000; t The length of the shutdown is days.

[0042] Repair and replacement costs R RM When a component of a tower crane fails, it needs to be replaced or repaired, which will incur certain costs.

[0043] Other expenses R m The losses caused by the accident to the equipment and facilities around the lifting machinery.

[0044] ; in, is the property value of the accident-hazardous area, 10,000 yuan / m 2 ; is the area of ​​equipment and facilities damaged by the accident, m 2 .

[0045] ; (2 - 3) Environmental pollution cost R p ; Among them, is the economic cost of environmental loss, in ten thousand yuan; is the unit opportunity cost of the environment, in ten thousand yuan; is the pollution amount of the environment; (2 - 4) Failure consequence R t Calculate ; Among them, R E is the economic loss cost, in ten thousand yuan; R i is the cost of casualties, in ten thousand yuan; R p is the environmental pollution cost, in ten thousand yuan; Quantitative assessment can determine the risk level of tower crane components through a 5 - level risk matrix. Among them, the failure probability level is divided according to the actual failure probability of the component to be calculated, and the failure consequence level is divided according to the ratio of the failure consequence to the price of the whole tower crane. The risk matrix is shown in Table 2.

[0046] Table 2 Risk matrix table

[0047] (III) Beneficial effects The present invention provides a risk assessment method for key components of tower cranes based on risk inspection technology. Compared with the prior art, it has the following beneficial effects: This risk assessment method for key components of tower cranes based on risk inspection technology provides a new calculation method for the quantitative calculation of the failure probability of tower crane components. Aiming at the diversity, uncertainty and complexity in the process of risk assessment of tower crane components, a complete quantitative assessment process for the risk level of tower crane components is established, realizing the quantitative assessment of the failure consequence and failure probability of crane components. The proposed method has the characteristics of being easy to understand, easy to master and easy to extend. Brief description of the drawings

[0048] Figure 1 is a schematic diagram of the modified hierarchical structure model of the key components of the tower crane of the present invention; Figure 2 is a schematic diagram for calculating the weight of ADV index of the present invention. Detailed implementation manners

[0049] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0050] Please refer to Figure 1-2 , the embodiments of the present invention provide a technical solution: a risk assessment method for key components of tower cranes based on risk inspection technology, including the following steps: (1) Calculate the actual failure probability of the component L a (1-1) Calculate the general failure probability L u Obtain the historical failure time series of a certain component of the tower crane during its use period, and calculate according to the least squares parameter estimation steps to obtain the shape parameter = 2.09, scale parameter = 426.83, goodness of fit R = 0.9576. Then its general failure probability distribution function is .

[0051] The actual use time of this component is 191 days, then the general failure probability L u (191) is 0.1683.

[0052] (1-2) Calculate the correction coefficient N E According to the calculation of the ADV weight, calculate the weights of each secondary index and tertiary index. Through the consistency test, the weights of each level of evaluation index finally obtained are shown in Table 3.

[0053] Table 3 Weights of Each Level of Evaluation Index

[0054] The sorting vectors of each level of index are obtained as: ; (1-2-2) Combine the detection data of a certain day of this tower crane with the detection situation of the detection personnel, and according to the corresponding evaluation criteria of the tertiary index, obtain a set of sample matrices D of the evaluation values of each level of index. The evaluation criteria of the tertiary index are shown in Table 4, and the evaluation values of each level of index of the sample matrix D are shown in Table 5.

[0055] Table 4 Three-level Index Evaluation Criteria

[0056] Among them, , J is the failure rate assessment level; T J is the time when the failure mechanism causes the failure to occur; T i is the time that the component has been in service; T SL is the remaining life , K is the life cycle assessment level; T i is the time that the component has been in service; T SL is the remaining life Table 5 Sample Matrix D Evaluation value

[0057] (1 - 2 - 3) The whitening weight function established according to the multi-level grey comprehensive evaluation method is as follows: Table 6 Whitening Weight Functions Corresponding to Each Grey Class

[0058] According to the weight vector of the correction coefficient of tower crane components, the correction coefficient weight matrix of tower crane components is obtained R , that is: ; Finally, according to the weight vector of the secondary index the correction coefficient weight matrix of tower crane components R the correction coefficient of tower crane components is calculated N E is 1.9683.

[0059] (1 - 3) The management level of the tower crane of this user unit reaches the industry average management level, and the management evaluation coefficient N M takes 1.

[0060] (1 - 4) The actual failure probability of this component .

[0061] (2) Calculate the failure consequences of key components R t According to the collected statistics, the usage site of this tower crane is a non-production and non-operational site, the overall price of the machine is 400,000 yuan, the accident impact area is 20 m 2 , the personnel density is 0.0084 people / m 2 , the accident-caused casualties cost of the tower crane is 300,000 yuan per person, the cost of component replacement and repair is 0.2 ten thousand yuan, the shutdown duration is 0.4 days, the enterprise incurs an economic loss of 10,000 yuan per day during shutdown, and the property value in the accident danger area is 0.2 ten thousand yuan. Calculate its economic loss cost: ; ; ; ; (3) Quantitative risk assessment of components The consequences of the failure of this component , and the actual failure probability is 0.3313.

[0062] From the risk matrix, it is judged that the risk level of this component is low, and there is no need to take corresponding measures to reduce the operating risk of the component.

[0063] In summary, the present invention provides a new calculation method for the quantitative calculation of the failure probability of tower crane components. In view of the diversity, uncertainty and complexity in the process of tower crane component risk assessment, a complete set of quantitative assessment processes for the risk level of tower crane components is established, realizing the quantitative assessment of the failure consequences and failure probability of crane components. The proposed method has the characteristics of being easy to understand, easy to master and easy to extend.

[0064] At the same time, the content not described in detail in this specification belongs to the prior art well-known to those skilled in the art.

[0065] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device.

[0066] Although embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A risk assessment method for key components of tower cranes based on risk inspection technology, characterized by: The specific steps include: S1. Calculate the actual failure probability of key components; ； in, L a is the actual failure probability, L u is the universal failure probability, N E is the correction factor, N M is the management evaluation coefficient; S2. Calculate the consequences of failure of key components: ； in, R As a consequence of failure, Ri Cost of casualties, RE For economic loss expenses, RP Costs for environmental pollution; S3. Conduct quantitative risk assessment on key components based on the quantitative risk assessment matrix.

2. The tower crane key component risk assessment method based on risk inspection technology according to claim 1 is characterized in that: The key components include tower body, crane arm, brake, wire rope, electric motor, hook, pulley block and driver's cab.

3. The tower crane key component risk assessment method based on risk inspection technology according to claim 1 is characterized by: The general failure probability in step S1 L u The process of obtaining is: Collect the historical failure records of the selected key components and estimate the scale parameter of the Weibull distribution by the least squares method With shape parameters , according to the goodness of fit R To judge the fitting effect, The fitting effect is better when and , obtain the universal failure probability function of key components, and then obtain the universal failure probability of the component according to the actual service time of the component L u , the general failure probability function of the key components is: ； in, α is the shape parameter, β is the scale parameter, t It is the actual service time of the parts.

4. The risk assessment method for key components of a tower crane based on risk inspection technology according to claim 1 is characterized in that: The correction coefficient in step S1 N E The process of obtaining is: T1. Analyze the internal connection of indicators through DEMATEL, combine AHP and VWT to modify the indicator weight according to the indicator status value, consider the indicator correlation and indicator status value to calculate the weight, and obtain , , ; T2, obtain the operation data of the tower crane on a certain day, and obtain the sample matrix according to the corresponding evaluation criteria of the constructed three-level evaluation indicators; T3, tower crane parts correction coefficient weight matrix calculated based on ADV weight and secondary index weight vector to calculate tower crane parts correction coefficient N E : in, N E is the correction factor of tower crane components, R is the grey weight matrix of tower crane component correction coefficients, V Indicates 5 levels of gray and their corresponding scores, V =[9,7,5,3,1] T , W is the weight vector of the secondary indicators.

5. The tower crane key component risk assessment method based on risk inspection technology according to claim 1 is characterized in that: The modified hierarchical structure model of key components of tower crane includes 4 secondary evaluation indicators and 11 tertiary evaluation indicators. The secondary evaluation indicators are technical module, general module, mechanical module and process module. The tertiary evaluation indicators are failure rate, inspection effectiveness, factory conditions, weather conditions, crane complexity, crane working level, standard conditions, life cycle, distinction between dynamic and static equipment, process stability and safety protection.

6. The tower crane key component risk assessment method based on risk inspection technology according to claim 1 is characterized by: In step S1, the evaluation coefficient is managed N M The process of obtaining is: Compare the equipment management level of the tower crane user with the industry average management level and calculate the management evaluation coefficient N M : ,in, x It is the ratio of the equipment management level to the industry average management level.

7. The tower crane key component risk assessment method based on risk inspection technology according to claim 1 is characterized by: The casualty expenses in step S2 R i The calculation formula is: ； in, R HD The accident caused death or serious injury to people, which turned into economic losses. is the personnel density of the production plant, The area affected by the accident.

8. The tower crane key component risk assessment method based on risk inspection technology according to claim 1 is characterized by: The economic loss cost in step S2 R E The calculation formula is; ； in, R E For economic loss expenses, is the property value of the accident-hazardous area, S p The area of ​​equipment and facilities damaged by the accident. R L The economic losses caused by the daily shutdown of enterprises, t The number of days of downtime, R RM Cost of parts replacement and repair.

9. The tower crane key component risk assessment method based on risk inspection technology according to claim 1 is characterized by: The environmental pollution fee in step S2 R p The calculation formula is; ； in, The economic cost of environmental damage, is the unit opportunity cost of the environment, The area of ​​environmental pollution.

10. The tower crane key component risk assessment method based on risk inspection technology according to claim 1 is characterized by: In the step S3, the vertical axis of the quantitative risk assessment matrix is ​​the actual failure probability value, and the horizontal axis is the ratio of the failure consequence to the price of the entire crane.

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