Bridge crane safety evaluation method based on fuzzy hierarchical comprehensive analysis method

Abstract

The invention discloses a bridge crane safety evaluation method based on a fuzzy hierarchical comprehensive analysis method. The method comprises the following steps: firstly, establishing a bridge crane safety evaluation index system based on a bridge crane inspection procedure in combination with field inspection of inspection workers and considering residual life influence factors; secondly, a nine-scale method is adopted to construct a judgment matrix, then the weight value of the evaluation index is determined, and the accuracy and reliability of the constructed judgment matrix are ensured through consistency check; and finally, integrating the scores of the evaluation indexes according to the corresponding weights to obtain the evaluation score of the whole crane. According to the method, whether the safety performance of the bridge crane meets the requirement or not is determined in the evaluation process, meanwhile, potential danger identification and rectification measure proposing in the evaluation process are considered, verification is carried out through engineering examples, and the method has important practical significance and popularization value.

Description

Technical Field

[0001] The invention belongs to the technical field of lifting machinery, and in particular relates to a safety evaluation of a bridge crane, and is also applicable to the safety evaluation of other cranes. Technical Background

[0002] Bridge crane is a kind of lifting equipment with a wide range of uses, playing an important role in production and life. Once a safety accident occurs, it will cause great economic losses and serious consequences. Therefore, scientific and reasonable safety evaluation is particularly important.

[0003] At present, special equipment inspectors inspect the safety status of cranes according to relevant national inspection regulations at all levels, and finally give a "qualified" or "unqualified" conclusion, which determines whether the crane inspection result is qualified from an administrative perspective. In fact, due to technical means, judgment standards and other factors, the inspection results of the special inspection department cannot fully reflect the actual safety status of the crane. Summary of the invention

[0004] In view of the above problems, the present invention studies the safety evaluation system of cranes in more depth on the basis of studying the current inspection procedures, and provides a theoretical and practical basis for the relevant national special inspection agencies to conduct more scientific and reasonable safety evaluation and risk control. Research on the safety evaluation method of bridge cranes based on fuzzy hierarchical comprehensive analysis. The fuzzy hierarchical comprehensive analysis method is adopted, combined with the on-site inspection situation of the inspectors, based on the existing inspection process, and considering the remaining life of the structure, a comprehensive safety evaluation method for bridge cranes is established.

[0007] The technical solution of the present invention is: a bridge crane safety evaluation method based on fuzzy hierarchical comprehensive analysis method, which specifically includes the following steps:

[0008] 1) Select safety evaluation indicators and divide the safety indicator system into A layer, B layer and C layer. Among them, A layer is the whole bridge crane. B layer includes technical data B1, metal structure B2, parts B3, safety protection device B4, electrical system B5, performance test B6 and remaining life B7, a total of seven indicators. The C layer is further subdivided according to the B layer indicators, with a total of 29 indicator layers, such as Figure 1 As shown;

[0009] 2) Judge each evaluation index and use the nine-scale method to construct the judgment matrix U = (u ij ) n×n The meaning of each scale value of the nine-scale method is shown in Table 1. Table 1 Meaning of scale values ​​of the nine-scale method Scale value meaning 1 The relative importance between the two indicators is the same 3 One metric is slightly more important than the other 5 One indicator is significantly more important than another 7 One indicator is more important than another 9 One indicator is definitely more important than another 2，4，6，8 The middle value between two adjacent judgments reciprocal <![CDATA[The comparison of index i and index j gives u ij , and the comparison of j and i gives u ji = 1 / u ij >

[0010] 3) Determine the weight value of the evaluation index, formula is the calculation formula of the weight value. After calculation, the weight result W of the indicator is obtained.

[0011] 4) Use a one-time test to determine whether the results are consistent. The formula for a one-time test is: Where, CR is the consistency ratio. If CR < 0.1, it means that the judgment matrix meets the one-time test standard; CI is the random one-time index; λ max is the maximum characteristic root of the matrix; n is the number of pairs of comparison indicators; RI is the evaluation consistency index, and the value of the one-time index RI is selected according to Table 2; Table 2 Consistency Index RI n 1 2 3 4 5 6 7 8 9 10 11 RI 0 0 0.52 0.89 1.12 1.26 1.36 1.41 1.49 1.49 1.52 n 12 13 14 15 RI 1.54 1.56 1.58 1.59

[0012] 5) By constructing a judgment matrix, calculating and passing a consistency test, the weight value of each indicator is finally obtained;

[0013] 6) With reference to the safety technical specifications related to cranes, establish the evaluation set of C-level indicators. The scoring criteria of C-level indicators are shown in Table 3; Table 3 C-level indicator scoring criteria Evaluation content Evaluation score qualified 4 Basic Qualification 3 Defective and repairable 2 Failed and cannot be repaired 1

[0014] 7) The scores of the evaluation indicators are integrated according to the corresponding weights to finally obtain the evaluation score of the entire crane. The safety level of the crane is now divided into four levels: excellent, good, medium, and poor, and the score range is divided as shown in Table 4. Table 4 Quantitative classification standards for complete cranes BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is the safety evaluation index system for bridge cranes;

[0016] Figure 2 A diagram for the abstract; DETAILED DESCRIPTION

[0017] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0018] A 20 / 5t-21.5m general-purpose bridge crane of a company was inspected and safety evaluated. The crane has been in continuous operation for 15 years. Its basic parameters are shown in Table 5. This parameter Parameter name data Parameter name data Rated lifting capacity 20t Job Level A6 span 21.5m Lifting speed 6m / min Lifting height 10m Cart running speed 75m / min Car running speed 45m / min

[0019] According to the standard inspection items and inspection methods, the crane shall be inspected item by item and the inspection record form shall be filled in;

[0026] After completing the inspection, score each evaluation indicator according to the safety evaluation system in this chapter. The scoring process for each indicator is as follows:

[0027] 1) Maintenance and inspection records. After reviewing the data, the maintenance records, self-inspection records, regular inspection records and other materials of the bridge crane are complete and properly kept, but some self-inspection records are missing. This inspection is basically qualified and the evaluation score is 3 points.

[0028] 2) Usage records. After reviewing the data, the operation records of the bridge crane are complete and archived, but the records of working data are mostly subjective and not very reliable. This inspection is basically qualified and the evaluation score is 3 points.

[0029] 3) After data review, the product technical documents of the bridge crane are complete and meet the requirements of relevant standards. The inspection is passed and the evaluation score is 4 points.

[0030] 4) Main beam: After the appearance inspection of the main beam, no obvious cracks and corrosion were found, and no deformation occurred. The overall structure was stable. This inspection passed and the evaluation score was 4 points.

[0031] 5) End beams. After visual inspection of the end beams, no obvious cracks or corrosion were found, and no deformation occurred. The overall structure was stable. This inspection was passed and the evaluation score was 4 points.

[0032] 6) Walkway. After the appearance inspection, the walkway surface has not been deformed, the railings are firm, and the relevant dimensions meet the standard requirements. This inspection is passed and the evaluation score is 4 points.

[0033] 7) Tracks. After the appearance inspection, the trolley and car tracks have no cracks, no welding defects, no obvious looseness and no rail gnawing. The car track is worn but does not affect safety. This inspection is basically qualified and the evaluation score is 3 points.

[0034] 8) Connection of metal structures. After visual inspection, the connection bolts and connecting pins between the metal structures are intact and not damaged, and there is no obvious looseness. This inspection is qualified and the evaluation score is 4 points.

[0035] 9) Lifting equipment. After the appearance inspection, the crane hook is firmly and reliably suspended, with no missing parts or damage, and no welding repairs. The anti-unhooking device meets the requirements of relevant standards. This inspection is qualified and the evaluation score is 4 points.

[0036] 10) Wire rope. After visual inspection and measurement with a caliper, the wire rope is not damaged or broken, and the diameter meets the requirements; the rope segment of the wire rope is firmly fixed, and there are more than 2 safety circles reserved on the drum. This inspection is qualified and the evaluation score is 4 points.

[0037] 11) Pulley. After the appearance inspection, the pulley has no defects or deformation, no jamming during operation, and slight wear but no safety impact. This inspection is basically qualified and the evaluation score is 3 points.

[0038] 12) Wheels. After the appearance inspection, the crane's trolley wheels and small trolley wheels have no defects, deformation, or obvious wear, and there is no rail gnawing during operation. This inspection is qualified and the evaluation score is 4 points.

[0039] 13) Roll. After the appearance inspection, the roll has no defects, deformation, wear, and surface cracks. This inspection is qualified and the evaluation score is 4 points.

[0040] 14) Brake. After visual inspection, the brake arm and brake wheel of the brake have no cracks or plastic deformation, the friction plate wear is small, the wear does not reach 50% of the original thickness, and the brake wheel and friction plate have no debris or oil stains. After the no-load test, there is no abnormal friction sound between the brake wheel and the friction plate, and the brake is reliable when working. This inspection is qualified and the evaluation score is 4 points.

[0041] 15) Lifting height limiter. The crane is tested with no load. The crane hook is slowly raised. When the hook hits the lifting height limiter, the hook automatically stops running, the power source in the rising direction is cut off, and the lifting movement cannot be performed, but the lowering movement can be performed. If this test is passed, the evaluation score is 4 points.

[0042] 16) Travel limiter. After visual inspection, the crane's trolley and carriage travel mechanisms are equipped with travel limiters in each direction of operation, and the limiter structure is intact and without missing parts. After no-load test, all limiters can work normally. When the trolley and carriage run to their limit positions, they can automatically cut off the power source and stop their movement in the corresponding direction. This inspection is passed and the evaluation score is 4 points.

[0043] 17) Lifting weight limiter. After visual inspection, the crane is equipped with a lifting weight limiter, and it is not short-circuited. Perform a static load test, keep the load at 100mm to 200mm above the ground, and continue to load without impact. When the load reaches 1.05 times the rated lifting weight, the upward movement of the mechanism is cut off, but the downward movement is possible. This test is qualified and the evaluation score is 4 points.

[0044] 18) Buffers and stoppers. After visual inspection, the crane's trolley and carriage are equipped with buffers, and there are stoppers at the ends of the tracks. After no-load tests, the buffers on both the trolley and carriage can contact the stoppers at the ends of the tracks at the same time, and the stoppers are firm and reliable. This item is qualified and the evaluation score is 4 points.

[0045] 19) Electrical operation status. After the appearance inspection, the crane control cabinet, resistors, feeding devices and other electrical equipment are firmly fixed and not damaged. After the no-load test, the crane can accurately complete all operating instructions, and all functions of the electrical equipment operate normally. This inspection is passed and the evaluation score is 4 points.

[0046] 20) Grounding protection. After visual inspection, the crane's electrical equipment and metal structure are equipped with grounding connection wires. The grounding resistance is measured with a grounding resistance meter, and its resistance value meets the requirements of relevant standards. This inspection is passed and the evaluation score is 4 points.

[0047] 21) Insulation protection. Disconnect the power supply and use a 500V megohmmeter to measure the resistance between the electrical circuit and the ground. If the resistance is greater than 1.0MΩ, the test is qualified and the evaluation score is 4 points.

[0048] 22) Line protection. After visual inspection, all external lines of the bridge crane have short-circuit protection or overcurrent protection function. This inspection is qualified and the evaluation score is 4 points.

[0049] 23) Phase error and missing protection. During the power-on test, disconnect any one phase line of the power supply, and the main power contactor will automatically disconnect; swap any two phase lines of the power supply, and the main power contactor will automatically disconnect. If this test is passed, the evaluation score is 4 points.

[0050] 24) Zero position protection. During the action test, disconnect the main power supply, move the controller handle of the crane away from the zero position, and then turn on the power supply again. The motor cannot start. The motor can only start after the controller handle is placed in the zero position. This test is passed and the evaluation score is 4 points.

[0051] 25) Undervoltage protection. During the action test, disconnect the power supply and the main power contactor will automatically disconnect. After the power supply is connected, the main power contactor cannot connect automatically and must be connected manually. If this test is passed, the evaluation score is 4 points.

[0052] 26) No-load test. The bridge crane was tested for motion of the hook, trolley and carriage in succession when it was no-load. During the test, all mechanisms operated normally, the brakes were reliable, the electrical system functioned normally, there was no gnawing of the track, and various safety protection devices worked reliably and effectively. This test was passed and the evaluation score was 4 points.

[0053] 27) Rated load test. Under the rated load condition, the bridge crane operates normally in all mechanisms, the main load-bearing structural parts have no obvious cracks, the connections are not loose, and the components are not damaged. The vertical static deflection of the main beam is measured by a level and is lower than S / 800, which meets the requirements of relevant standards. The inspection is qualified and the evaluation score is 4 points.

[0054] After statistics, the scores of each test item are shown in Table 6. Table 6 Inspection items and inspection scores

[0055] According to the weight of each evaluation index, the scores of each inspection item are combined. After calculation, the comprehensive score of this general bridge crane is: 3.9.

[0056] According to the quantitative classification standards for complete cranes in Table 4, the safety level of this general-purpose crane is Level I, which means that the safety condition of the crane is very good.

[0057] Although the general bridge crane has been in continuous operation for 15 years, its overall safety status is very good, which is related to the active maintenance of the crane. In addition, the crane works in an indoor non-dust workshop and is less polluted by the environment. The above evaluation results are consistent with the actual situation of the crane and can reflect the comprehensive safety status of the crane. However, it should also be noted that some evaluation indicators may have safety hazards, which should be repaired.

[0058] The description of the above embodiments is to facilitate those skilled in the art to understand the present invention. Those skilled in the art in the field to which the present invention belongs can still modify or replace the specific embodiments of the present invention with equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A safety evaluation method for bridge crane based on fuzzy hierarchical comprehensive analysis method, characterized in that The following steps are involved: Step 1: Selection of safety evaluation indicators; Step 2: Determine the weight set of safety evaluation indicators; Step 3: Determine the evaluation set of each evaluation indicator; Step 4: Quantitative grading standards for complete cranes.

2. The safety evaluation method for bridge crane based on fuzzy hierarchical comprehensive analysis method according to claim 1 is characterized by: The selection of safety evaluation indicators in the step 1 refers to establishing a safety evaluation indicator system for bridge cranes based on the inspection procedures for bridge cranes, combined with on-site inspections by inspection staff, and taking into account factors affecting the remaining life.

3. The safety evaluation method for bridge crane based on fuzzy hierarchical comprehensive analysis method according to claim 1 is characterized by: In the step 2, when determining the weights of the evaluation indicators, the nine-scale method is used, which can more accurately reflect the relationship between indicators of the same level.

4. The safety evaluation method for bridge crane based on fuzzy hierarchical comprehensive analysis method according to claim 1 is characterized by: The accuracy and reliability of the judgment matrix constructed by determining the weight values ​​in step 2 need to pass a consistency test.

5. The method for safety evaluation of a bridge crane based on fuzzy hierarchical comprehensive analysis method according to claim 4 is characterized in that: The consistency test calculation formula is:

6. The safety evaluation method for bridge crane based on fuzzy hierarchical comprehensive analysis method according to claim 1 is characterized by: In step three, the crane inspector only needs to select the corresponding evaluation score according to the evaluation content.

7. The safety evaluation method for bridge crane based on fuzzy hierarchical comprehensive analysis method according to claim 1 is characterized by: In the step 4, the safety level of the crane is divided into four levels according to excellent, good, medium and poor, and the scoring interval is divided.

8. The safety evaluation method for bridge crane based on fuzzy hierarchical comprehensive analysis method according to claim 7 is characterized by: The scoring range is divided as follows: Evaluation level I, score range (3.5, 4]: indicates that the crane is in excellent safety condition, all inspection items basically meet the requirements, there may be individual inspection items that fail, and it can continue to be used after repair or replacement. Evaluation level II, score range (3, 3.5]: indicates that the crane is in good safety condition, a small number of inspection items do not meet the safety requirements, and it can continue to be used after repair or replacement. Evaluation level III, score range (2.5, 3]: Indicates that the crane is in general safety condition, there are unqualified items in the inspection items, and it needs to be shut down for repair and re-evaluation before continuing to use. Evaluation level IV, score range [1,2.5]: Indicates that the crane is in poor safety condition, the crane has major safety hazards, and it is difficult to meet the standards through repair and adjustment. The whole machine needs to be shut down for overhaul or scrapped.

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