CN108313888A - A kind of electric single-beam bridge crane tool metal structure safety monitoring assembly and method - Google Patents

Abstract

The invention belongs to technical field of crane equipment.Purpose is to provide a kind of electric single-beam bridge crane tool metal structure safety monitoring assembly and method, the system can monitor overload operation situation, bolt state status and connection between girder and carriage position macroscopic cracking situation in the crane course of work on-line, have the function of to monitoring information security evaluation, warning function, reliable foundation can be provided for the safe operation of crane, avoid and reduce the generation of safety accident.Technical solution is：A kind of electric single-beam bridge crane tool metal structure safety monitoring assembly, including be suspended under suspension hook weight sensor, several girder strain transducers mounted on girder lower cover bottom surface centre position, the bolt clipping forcee sensor, several end carriage strain transducers on end carriage web and the total system host that collected data are handled that are mounted on one by one on the bolt that is connect with connecting plate and girder of end carriage web.

Description

An electric single-girder bridge crane metal structure safety monitoring device and method

technical field

The invention belongs to the technical field of hoisting equipment, and relates to a safety monitoring system for a metal structure of an electric single-girder bridge hoisting machine.

Background technique

Hoisting machinery is an important construction machinery in the fields of construction engineering, metallurgical industry, and electric power industry. Its own structure contains many risk factors and is one of the special equipment that is prone to safety accidents. Under normal circumstances, the service life of ordinary cranes is about 20 to 30 years. During the service process, they are affected by factors such as heavy loads, fatigue, and material aging. Heavy, overloaded use occurs from time to time, and the resulting damage to the metal structure inevitably accumulates. After the crane has been used for a certain number of years, its metal structure often suffers severe damage in places with large stress concentrations such as welding heat-affected zones and bolt connections. These structural damages have a significant impact on the bearing capacity of the structure, and cranes are generally huge in size and high in cost. Once an accident occurs, it will cause huge loss of life and property, and even lead to catastrophic accidents such as mass death and mass injury.

According to statistics, the number of hoisting machinery accidents ranks first in all kinds of special equipment accidents for five consecutive years, and the economic losses caused by shutdowns are also increasing. According to the structure, cranes are mainly divided into bridge cranes, gantry cranes and jib cranes, etc. Among them, electric single-girder bridge cranes are mainly composed of main girders, end girders, electric hoists, electrical equipment, etc. The end girder and the main girder pass through High-strength bolt connection. The main reasons for the failure of the metal structure caused by the electric single-girder bridge crane during operation are (1) Overload operation: the use of overloaded cranes will cause severe bending of the main girder of the steel structure of the crane, and the steel wire rope may be broken, and the main girder and Structural damage occurs at the connection position of the end beam. In severe cases, the connection position between the main beam and the end beam will be broken, and the main beam and hoisting weight will fall directly. (2) Bolt loosening: During the long-term load operation of the electric single-girder bridge crane, the bolts connecting the end beam and the main beam often loose due to vibration, overload, etc., resulting in instability of the structure and excessive local stress. At the same time, it may lead to the generation of fatigue cracks at the connection position and reduce the connection strength. (3) Cracks occur at the connection position between the end beam and the main beam: There is a large stress concentration at the bolt connection position of the end beam of the electric single-girder bridge crane. Under the long-term load and vibration, fatigue cracks are prone to occur and affect the structural strength. In severe cases Crack growth leads to fracture at the end beam connection location.

At present, the main guarantee methods for the safe operation of electric single-girder bridge cranes in my country are regular inspections and daily maintenance. Most of the technical means used are visual inspection, sensory judgment, shutdown measurement, and magnetic particle inspection. This type of safety assurance technology only detects part of the geometric and physical quantities of the crane in the non-working state, and cannot monitor the operating safety of the crane, and lacks a prevention mechanism for sudden accidents; Currently, daily maintenance is mainly detected through macroscopic methods such as nut mark recognition, lacking quantitative monitoring of bolt looseness, and inspections are required, and operators climb to the crane connection for inspections, which has a certain degree of danger. For the cracks at the connection position between the main girder and the end girder, due to the limitation of the structure of the connection position, the cracks are not easy to be observed intuitively; at the same time, due to the complexity of the operating conditions of the crane, the occurrence of cracks at the connection is random. It is difficult to detect the crack at this position by methods such as magnetic particle inspection.

Contents of the invention

The object of the present invention is to solve the above-mentioned problems and provide a safety monitoring device and method for the metal structure of the electric single-girder bridge crane. The macroscopic cracks at the connection position of the end beam have the function of monitoring information safety assessment and alarm function, which can provide a reliable basis for the safe operation of the crane and avoid and reduce the occurrence of safety accidents.

In order to solve the problems of the technologies described above, the technical solution provided by the invention is:

An electric single-girder bridge crane metal structure safety monitoring device, including a weight sensor suspended under the hook, several main girder strain sensors installed in the middle of the bottom surface of the main girder lower cover, each installed on the end girder The bolt fastening force sensor on the bolt connecting the web, the connecting plate and the main beam, several end beam strain sensors installed on the web of the end beam, and the host computer of the comprehensive processing system for processing the collected data.

The bolt fastening force sensor is installed on the web of the end beam, the bolts connecting the connecting plate and the main beam, arranged between the main beam and the gasket, and takes 2 as a group along the length direction of the end beam with respect to the connecting plate Symmetrical planes are mounted symmetrically.

Preferably, a total of 4 pieces of the end beam strain sensors are installed on the web of the end beam, and two pieces are installed symmetrically with respect to the symmetrical plane of the connecting plate along the length direction of the end beam.

The upper end beam strain sensor is installed at the same height as the lower bolt; the four end beam strain sensors are at the same distance from the symmetrical plane of the connecting plate.

The method of monitoring the metal structure safety monitoring device of the electric single-girder bridge crane, wherein the method of monitoring the state of the bolts is:

The pre-tightening force of two bolts in the same group is collected by the bolt fastening force sensor, and then the collected bolt pre-tightening force F _i is compared with the bolt pre-tightening force threshold F ₀ :

When F _i <F ₀ , it is determined that the bolt number i is in a loose state, i=1,2;

Bolt pretightening force threshold F ₀ ＝F _m /v

F _m is the rated pre-tightening force of the bolt

v is the bolt safety factor, take 1.1-1.2.

When F _i ≥ F ₀ , the method for judging the bolt state is:

(1) When 1/v<F ₁ /F ₂ <v, it is determined that bolts 1 and 2 are in normal condition;

(2) When F ₁ /F ₂ >v, it is determined that there is an abnormal condition of the No. 1 bolt;

(3) When F ₁ /F ₂ <(1/v), it is determined that the state of the No. 2 bolt is abnormal.

The monitoring and evaluation of macroscopic cracks at the connection position of the end beam web is carried out as follows:

(1) Make an initial judgment on the monitoring stress, if σ _ij ≥ [σ], the stress at the corresponding monitoring position exceeds the standard;

(2) If σ _ij <[σ],

1) If 1/n _i <k _i <n _i , the stress at the monitoring position is normal;

2) If 1/n ₂ <k ₂ <n ₂ , when k ₁ <1/n ₁ , and K>1.0, it means that there may be macro cracks near the monitoring position of end beam strain sensor 4-1; when k ₁ >n ₁ , and K<1.0, indicating that there may be macro cracks near the monitoring position of end beam strain sensor 4-2;

3) If 1/n ₁ <k ₁ <n ₁ , when k ₂ >n ₂ , and K>1.0, it means that there may be macro cracks near the monitoring position of end beam strain sensor 4-3; when k ₂ <1/n ₂ , and K<1.0, indicating that there may be macro cracks near the monitoring position of end beam strain sensor 4-4;

4) If k ₁ <1/n ₁ , k ₂ >n ₂ , K>1.0, it means there may be macro cracks in the monitoring area from end beam strain sensor 4-1 to 4-3;

5) If k ₁ >n ₁ , k ₂ <1/n ₂ , K<1.0, it means there may be macro cracks in the monitoring area from end beam strain sensor 4-2 to 4-4;

in:

Allowable stress [σ]

The first stress state coefficient k ₁ =σ ₁₁ /σ ₁₂

The second stress state coefficient k ₂ =σ ₂₁ /σ ₂₂

Relative stress state parameter K＝(σ ₂₁ -σ ₁₁ )/(σ ₂₂ -σ ₁₂ )

σ _ij (i=1,2; j=1,2) is the stress monitored by the four end beam strain sensors; the numbering rule is i from top to bottom, i=1,2; along the length of the end beam from left to right The position number of is j,j=1,2.

Where n ₁ and n ₂ are the first security assessment parameter and the second security assessment parameter, both of which are greater than 1.

Compared with prior art, the beneficial effect of the present invention:

1. The bolt fastening force sensor adopts a flat cylindrical sensor, which is installed in combination with gaskets and nuts, so that the structural connection of the end beam, main beam, and sensor is stable, and can quantitatively monitor the fastening force of the bolt connection of the electric single-girder bridge crane , so as to determine the connection status.

2. The macro crack evaluation module, the arrangement of end beam strain sensors is simple, and the evaluation method is reasonable, which can directly monitor the macro cracks at the connection position of end beam web.

Description of drawings

Fig. 1 is a schematic diagram of the system structure in the present invention.

Fig. 2 is a schematic diagram of the installation positions of the main girder strain sensor and the weight sensor in the present invention.

Fig. 3 is a schematic diagram of the installation position of the bolt fastening force sensor in the present invention (A-A sectional structure diagram in Fig. 2 ).

Fig. 4 is a cross-sectional structure diagram along B-B in Fig. 2 .

FIG. 5 is a cross-sectional structural diagram of C-C in FIG. 3 .

FIG. 6 is a schematic diagram of a preset crack of the stress calculation module in the present invention.

FIG. 7 is a schematic diagram of an enlarged structure of part D in FIG. 7 .

Fig. 8 is a schematic flow chart of the macro crack evaluation module in the present invention.

Detailed ways

The electric single-girder bridge crane metal structure safety monitoring device related to the present invention is as shown in Figure 1, comprises weight sensor 1, main girder strain sensor 2, bolt tightening force sensor 3, end beam strain sensor 4 (weight sensor 1 , the main beam strain sensor 2, the bolt fastening force sensor 3 and the end beam strain sensor 4 are all data acquisition devices), the comprehensive processing system host 6; the functional software modules include a system calibration module 7, an overload monitoring module 8, and a bolt state monitoring module 9. The stress calculation module 10 and the macro crack evaluation module 11, each module judges each monitoring situation in real time according to the corresponding evaluation method.

Taking an electric single-girder bridge crane with a span of 6800mm and a rated lifting capacity of 10t as an example, the specific implementation of the safety monitoring device and method for the mechanical metal structure of the crane will be described below.

Figure 2 shows the schematic diagram of the layout of the crane's weight sensor 1 and main girder strain sensor 2. The weight sensor 1 indirectly measures the current lifting capacity by detecting the tension of the steel wire rope. The system calibration module 7 evaluates the reliability of the monitoring data of the system by comparing the main girder strain sensor data 2 and the weight sensor 1 data collected by the data acquisition device when the lifting weight is at the mid-span position.

The overload monitoring module 8 compares the actual lifting weight of the weight sensor 1 collected in real time with the built-in lifting weight alarm threshold of the module. If the actual lifting weight exceeds the lifting weight alarm threshold, the comprehensive processing system host 6 displays the actual lifting weight and gives an alarm ;Set the lifting capacity alarm threshold to 95% of the rated lifting capacity.

The bolt fastening force sensor 3 is a flat cylindrical sensor, with two as a group (such as the left side bolt 3-1, the right side bolt 3-2) along the length direction of the end beam with respect to the symmetry plane 14-1 of the connecting plate 14 Perform symmetrical installation (see Figure 3; the length direction of the end beam is the left and right direction in Figure 3). The web plate 13 of the end beam 12, the connecting plate (14) and the main beam 15 are fixedly connected as a whole through bolts 16 and nuts 18, and the bolt fastening force sensor is threaded on the bolts and arranged between the main beam 15 and the gasket 17 Between (see Figure 5), bear the tightening force exerted by the bolts.

First, compare the pre-tightening force F _i collected by the bolt fastening force sensor with the system preset bolt pre-tightening force threshold F ₀ to confirm the fastening state of each bolt in real time. The specific monitoring can be performed by the bolt state monitoring module 9 . When the monitored bolt pretightening force is less than F ₀ (i.e. F _i <F ₀ ), it can be judged that the bolt is in a loose state, and the host computer 6 of the comprehensive processing system will alarm and display the loose bolt; The tightening force is the rated pre-tightening force of M20 high-strength bolts.

In the crane work project, the bolt state monitoring module 9 performs real-time judgment by comparing the pretightening force of two bolts in the same group; wherein F ₁ is the pretightening force of the left bolt, and F ₂ is the pretightening force of the right bolt;

When F _i ≥ F ₀ , the bolt state monitoring module in the host computer of the integrated processing system judges that the bolt state is abnormal; if (1/v)<F ₁ /F ₂ <v is satisfied, it is determined that the monitoring bolt state is normal; if F ₁ / If F ₂ >v, it is determined that there may be an abnormal state of the bolt at the monitoring position of bolt No. 1; if F ₁ /F ₂ <(1/v), it is determined that there may be an abnormal state of the bolt at the monitoring position of bolt No. 2.

Figure 3 shows a schematic diagram of the arrangement of four end beam strain sensors 4-1, 4-2, 4-3, and 4-4. The number of the two end beam strain sensors arranged from top to bottom is i, and they are arranged from left to right The number of the two end beam strain sensors is j, that is, the i numbers of the end beam strain sensors 4-1 and 4-3 are 1 and 2 respectively, and the j number is 1; similarly, the end beam strain sensors 4-2 and 4- The i numbers of 4 are 1 and 2 respectively, and the j number is 2; use σ _ij to represent the stress state of the four end beam strain sensors, and the end beam strain sensors 4-1, 4-2, 4-3, 4-4 The σ _ij of is sequentially σ ₁₁ , σ ₁₂ , σ ₂₁ , σ ₂₂ . Considering the structural form of the connection position between the end girder and the main girder of the electric single-girder bridge crane, and the change of the stress state at the monitoring position can effectively characterize the macroscopic cracks in the monitoring area, the end girder strain sensors are installed on the web 13 of the end girder at a distance of 10mm from the edge of the connecting plate , the height of the end beam strain sensors 4-1 and 4-2 is equal to the height of the lower bolts.

The monitoring and evaluation of the macro cracks at the connection position of the end beam web is that the macro crack evaluation module 11 first judges whether the stress state σ _ij of each monitoring position is within the allowable stress range. 6 shows that the stress at this position exceeds the standard alarm; when the stresses at the four monitoring positions are all within the allowable stress range, the macro crack evaluation module 11 proceeds to the next step to determine whether there are macro cracks in the monitoring local area of the end beam connection position of the crane according to the stress data of the four monitoring positions. Cracks, as shown in Figure 8, is a program schematic diagram of the macro crack evaluation module at the connection position of the end beam.

Firstly, if 1/n ₁ <k ₁ <n ₁ , 1/n ₂ <k ₂ <n ₂ is satisfied, it means that the stress state of the monitoring position is normal, and at this time, the integrated processing system host 6 displays the stress state of each position in real time;

If the above formula is not satisfied, proceed to the next step of judgment. If 1/n ₁ <k ₁ <n ₁ , when k ₂ >n ₂ , and K>1.0, it means that the stress state at the monitoring position of end beam strain sensor 4-3 is abnormal. There may be macroscopic cracks at this position, and at this time the integrated processing system host 6 displays an alarm at this position; when k ₂ <1/n ₂ , and K<1.0, it means that the stress state of the monitoring position of the end beam strain sensor 4-4 is abnormal, and this There may be macroscopic cracks in the position, and at this time, the host computer 6 of the comprehensive processing system displays an alarm for the position.

If 1/n ₂ <k ₂ <n ₂ , when k ₁ <1/n ₁ , and K>1.0, it means that the stress state at the monitoring position of the end beam strain sensor 4-1 is abnormal, and there may be macro cracks in this position , now the integrated processing system host 6 displays the position alarm. When k ₁ >n ₁ , and K<1.0, it means that the stress state of the position monitored by the end beam strain sensor 4-2 is abnormal, and there may be macroscopic cracks in this position. At this time, the comprehensive processing system host 6 displays an alarm at this position.

If k ₁ <1/n ₁ , k ₂ >n ₂ , K>1.0, it means that the stress distribution state in the monitoring area from end beam strain sensor 4-1 to 4-3 is abnormal, and there may be macro cracks in this area . If k ₁ >n ₁ , k ₂ <1/n ₂ , K<1.0, it means that the stress distribution from the end beam strain sensor 4-2 monitoring position to the 4-4 monitoring area is abnormal, and there may be macro cracks in this area .

Wherein the first safety evaluation parameter n ₁ and the second safety evaluation parameter n ₂ are calculated by the stress calculation module 10 . The stress calculation module 10 presets macroscopic cracks on the end beam 12 close to the lower bolt hole position on the crane model as shown in Figures 6 and 7, and defines the path AB as passing through the strain sensor 4-1 on the end beam web 13 and The straight line at position 4-3, the path CD and the path AB are symmetrical about the symmetry plane of the connecting plate 14, the starting point of the crack is the edge of the bolt hole, the end point is the intersection with the path AB, and the extension line of the crack passes through the center of the bolt hole. The lengths of cracks L ₁ and L ₂ are determined according to monitoring needs, and Where h is the height of the connecting plate 14, and _h0 is the height of the center of the bolt hole below from the bottom of the connecting plate 14. And between the cracks L ₁ and L _{2 ,} 5 groups of cracks La, Lb, Lc, Ld, and Le are uniformly prefabricated. The stress calculation module (10) first obtains the stresses at the monitoring positions of the four end beam strain sensors under the 7 groups of macro-crack conditions, and then calculates the 7 groups k ₁ according to the definition of the first stress state coefficient k ₁ and the second stress state coefficient k ₂ , k ₂ values, and take the maximum value of 1/k ₁ in the 7 sets of data as the first safety assessment parameter n ₁ , and take the minimum value of k ₂ as the second safety assessment parameter n ₂ ; n ₁ and n ₂ are both greater than 1 .

The first stress state coefficient k ₁ =σ ₁₁ /σ ₁₂ ; the second stress state coefficient k ₂ =σ ₂₁ /σ ₂₂ .

Based on the above analysis and judgment, the macro crack evaluation module 11 can monitor the macro cracks in the local area of the connection between the crane end girder and the main girder.

The weight sensor, strain sensor, bolt fastening force sensor, acquisition device, etc. of the present invention can be purchased directly; the system calibration module, overload monitoring module, bolt state monitoring module, stress calculation module and macro crack evaluation module are all It is a functional software module written by ordinary software technicians.

Finally, it should be noted that what is listed above is only a specific implementation case of the present invention, and does not limit the present invention in any form. Obviously, the present invention is not limited to the above embodiments, and many modifications are possible. All deformations that can be directly derived or associated by those skilled in the art from the content disclosed in the present invention should be considered as the protection scope of the present invention.

Claims (6)

1. An electric single-girder bridge crane metal structure safety monitoring device, comprising a weight sensor (1) suspended under the hook, several main beam strain sensors (2) installed in the middle of the bottom surface of the main beam lower cover plate ), also includes one by one installed on the end beam web (13) and the connecting plate (14) and the bolt fastening force sensor (3) on the main beam (15) connecting bolt (16), installed on the end beam web A plurality of end beam strain sensors (4) and a comprehensive processing system host (6) for processing the collected data. 2. The electric single girder bridge crane metal structure safety monitoring device according to claim 1, characterized in that: the bolt fastening force sensor is installed on the web of the end girder, the bolt connecting the connecting plate and the main girder , arranged between the main beam and the spacer, and installed symmetrically with respect to the symmetry plane (14-1) of the connecting plate in groups of 2 along the length direction of the end beam. 3. The safety monitoring device for the metal structure of the electric single-girder bridge crane according to claim 2, characterized in that: a total of 4 pieces of the end beam strain sensors are installed on the web of the end beam, respectively along the length direction of the end beam. Install symmetrically about the symmetrical plane of the connecting plate in groups of 2 pieces. 4. The safety monitoring device for metal structures of electric single-girder bridge cranes according to claim 3, characterized in that: the upper end beam strain sensors are installed at the same height as the lower bolts; the four end beam strain sensors are at the same distance from the connecting plate The planes of symmetry of have the same distance. 5. The method for monitoring by the electric single-girder bridge crane metal structure safety monitoring device as claimed in claim 1, wherein the method for monitoring the state of the bolts is: The pre-tightening force of two bolts in the same group is collected by the bolt fastening force sensor, and then the collected bolt pre-tightening force F _i is compared with the bolt pre-tightening force threshold F ₀ : When F _i <F ₀ , it is determined that the bolt number i is in a loose state, i=1,2; Bolt pretightening force threshold F ₀ ＝F _m /v F _m is the rated pre-tightening force of the bolt v is the bolt safety factor, take 1.1-1.2. When F _i ≥ F ₀ , the method for judging the bolt state is: (1) When 1/v<F ₁ /F ₂ <v, it is determined that bolts 1 and 2 are in normal state; (2) When F ₁ /F ₂ >v, it is determined that there is an abnormal condition of the No. 1 bolt; (3) When F ₁ /F ₂ <(1/v), it is determined that the state of the No. 2 bolt is abnormal. 6. The method for monitoring according to claim 5, characterized in that: the monitoring and evaluation of macroscopic cracks at the connection position of the end beam web is carried out according to the following steps: (1) Make an initial judgment on the monitoring stress, if σ _ij ≥ [σ], the stress at the corresponding monitoring position exceeds the standard; (2) If σ _ij <[σ], 1) If 1/n _i <k _i <n _i , the stress at the monitoring position is normal; 2) If 1/n ₂ <k ₂ <n ₂ , when k ₁ <1/n ₁ , and K>1.0, it means that there may be macro cracks near the monitoring position of end beam strain sensor 4-1; when k ₁ >n ₁ , and K<1.0, indicating that there may be macro cracks near the monitoring position of end beam strain sensor 4-2; 3) If 1/n ₁ <k ₁ <n ₁ , when k ₂ >n ₂ , and K>1.0, it means that there may be macro cracks near the monitoring position of end beam strain sensor 4-3; when k ₂ <1/n ₂ , and K<1.0, indicating that there may be macro cracks near the monitoring position of end beam strain sensor 4-4; 4) If k ₁ <1/n ₁ , k ₂ >n ₂ , K>1.0, it means there may be macro cracks in the monitoring area from end beam strain sensor 4-1 to 4-3; 5) If k ₁ >n ₁ , k ₂ <1/n ₂ , K<1.0, it means there may be macro cracks in the monitoring area from end beam strain sensor 4-2 to 4-4; in: Allowable stress [σ] The first stress state coefficient k ₁ =σ ₁₁ /σ ₁₂ The second stress state coefficient k ₂ =σ ₂₁ /σ ₂₂ Relative stress state parameter K＝(σ ₂₁ -σ ₁₁ )/(σ ₂₂ -σ ₁₂ ) σ _ij (i=1,2; j=1,2) is the stress monitored by the four end beam strain sensors; the numbering rule is i from top to bottom, i=1,2; along the length of the end beam from left to right The position number of is j,j=1,2; Where n ₁ and n ₂ are the first security assessment parameter and the second security assessment parameter, both of which are greater than 1.