A method for calculating the pressure of a truck crane outrigger

Abstract

The application discloses a kind of automobile crane outrigger pressure calculation methods, including the equivalent transfer of the total vertical load of automobile crane to the center O point of four outriggers, according to static load type test, automobile crane should not overturn, obtain the allowable total vertical load F n And allowable total moment M n ; According to the change of only lifting weight when automobile crane is working, obtain the total vertical load F and total moment M of O point;Using total vertical load F and total moment M, obtain the pressure curve of four outriggers when jib 360 ° rotates.The application proposes a practical and effective calculation method for the outrigger pressure of automobile crane, compared with actual measurement data, the deviation rate of calculation result is smaller, the accuracy of calculation result is higher, practical and convenient, effectively improve the safety of automobile crane work.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of automobile crane, in particular to a kind of automobile crane outrigger pressure calculation method. BACKGROUND

[0002] The automobile crane is a kind of boom crane installed on ordinary automobile chassis or special automobile chassis, and the whole machine load is transmitted to the foundation through four outriggers during operation. In order to prevent the automobile crane from overturning due to insufficient foundation bearing capacity, the outrigger pressure is needed to calculate the foundation bearing capacity.

[0003] The automobile crane is complex in composition, and only parameters such as running weight, rated lifting capacity, working amplitude and counterweight are provided in the instruction manual, without the mass and center of mass of each component of the automobile crane, which brings great difficulty to accurately calculate the outrigger pressure. The current method for calculating the outrigger pressure is an empirical formula, and the calculation result has a large deviation, sometimes even a difference of one time, or too conservative, or unsafe, and a general and accurate outrigger pressure calculation method is urgently needed. SUMMARY

[0004] In order to solve the problems existing in the prior art, an automobile crane outrigger pressure calculation method is provided.

[0005] The technical solution adopted by the present application to solve its technical problems is:

[0006] The present application provides an automobile crane outrigger pressure calculation method, comprising:

[0007] The automobile crane comprises a chassis, four outriggers, a slewing mechanism, a counterweight, a rotatable and variable amplitude boom, and the boom is used for lifting work, and the center of the four outriggers is O point;

[0008] S1: equivalent transfer all vertical loads of the automobile crane to the center O point of the four outriggers, and according to the static load type test, the automobile crane should not overturn, to obtain the allowable total vertical load F n and the allowable total moment M n of O point;

[0009] S2: according to the change of only lifting weight during operation of the automobile crane, the total vertical load F and the total moment M of O point are obtained;

[0010] S3: using the total vertical load F and the total moment M, the pressure curve of the four outriggers during 360° rotation of the boom is obtained.

[0011] Preferably, in S1, after equivalent transfer all vertical loads of the automobile crane to O point during static load type test, the allowable total vertical load F n of O point is obtained:

[0012] (1) ;

[0013] wherein m1 represents the self weight of the truck crane, m2 represents the detachable counterweight mass, m3 represents the auxiliary boom mass, Q n represents the rated load, and g represents the gravitational acceleration;

[0014] According to the anti-overturning requirement, the allowable total moment M n at the O point is obtained:

[0015] (2) ;

[0016] wherein k represents the overturning moment to stabilizing moment proportionality coefficient, k is taken as 0.9, a represents the longitudinal span of the outrigger, and b represents the lateral span of the outrigger;

[0017] M n is divided into the load-related moment M 1n and the load-unrelated moment M 2n :

[0018] (3) ;

[0019] (4) ;

[0020] wherein R represents the working amplitude, L represents the length of the hoist boom, φ is the dynamic load coefficient, φ is taken as 1.15, and a II is the maximum deflection angle of the hoist wire rope, a II is taken as 5°.

[0021] Preferably, in the S2, when the truck crane is working, only the load is changed, and the dynamic load coefficient should be considered, and the rest of the parameters are the same as in the type test, the total vertical load F at the O point and the total moment M are calculated according to the following formula:

[0022] (5) ;

[0023] (6) ;

[0024] (7) ;

[0025] wherein M1 represents the load-related moment, Q1 represents the hook mass, Q2 represents the mass of the sling and the maximum hoisted object, M1 is the front tilting moment when , and M1 is the back tilting moment when .

[0026] Preferably, in the S3, the total moment M is expressed by the right-hand rule, the boom direction is perpendicular to the M direction, assuming that the rotation angle of M is theta, M is in the same direction as the x axis , counterclockwise is positive, and the pressures of the four legs are N1, N2, N3 and N4 respectively:

[0027] (8);

[0028] (9);

[0029] (10);

[0030] (11);

[0031] In the formula, F represents the total vertical load, M represents the total moment, theta represents the rotation angle of the total moment, a represents the longitudinal span of the leg, and b represents the transverse span of the leg.

[0032] Preferably, in the S3, when M is in the first quadrant, N2 is minimum and N4 is maximum, and the extreme value conditions are , if , it indicates that all four legs are under compression, and if , it indicates that the leg corresponding to N2 has been separated from the ground, and the pressure is redistributed, and the calculation formulas of N1, N3 and N4 are:

[0033] (12);

[0034] (13);

[0035] (14);

[0036] Since the four legs are symmetrically distributed, the load acts on the center O point of the four legs, and the situation is the same when M is in other quadrants.

[0037] Compared with the prior art, the beneficial effects of the present application are:

[0038] The present application is based on the actual working condition of the truck crane, combined with the design requirements of the crane, and proposes a leg pressure calculation method of the truck crane, and the test comparison is carried out, compared with the actual measurement data, the deviation rate of the calculation result is smaller, the calculation result is more accurate, practical and convenient, and the safety of the truck crane work is effectively improved. BRIEF DESCRIPTION OF DRAWINGS

[0039] The above and / or additional aspects and advantages of the present application will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the following drawings of which:

[0040] Figure 1 is the plan size and the number of outriggers of the truck crane in the present application;

[0041] Figure 2 is the equivalent load diagram when the static load type test in the present application;

[0042] Figure 3 is the equivalent load diagram when the lifting operation in the present application;

[0043] Figure 4 is the outrigger force analysis schematic diagram in the present application;

[0044] Figure 5 is the four outrigger force analysis schematic diagram in the present application;

[0045] Figure 6 is the three outrigger force analysis schematic diagram in the present application;

[0046] Figure 7 is the relationship curve diagram of each outrigger pressure and the slewing angle when the first group of parameters in the present application;

[0047] Figure 8 is the relationship curve diagram of each outrigger pressure and the slewing angle when the second group of parameters in the present application. DETAILED DESCRIPTION

[0048] The embodiments of the present application are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar notations represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary, only for explaining the present application, and cannot be understood as a limitation of the present application.

[0049] Referring to the accompanying drawings, Figures 1-8 the present embodiment proposes a truck crane outrigger pressure calculation method, comprising:

[0050] The truck crane includes a chassis, four outriggers, a slewing mechanism, a counterweight, a rotatable and luffing arm frame, the arm frame is used for lifting work of articles, and the center point O of the four outriggers;

[0051] S1: The total vertical load of the truck crane is equivalent to the center O of the four outriggers, according to the static load type test, the truck crane should not overturn, and the allowable total vertical load F n and the allowable total moment M n of O are obtained;

[0052] S2: According to the truck crane operation, only the lifting weight changes, the total vertical load F and the total moment M of O are obtained;

[0053] S3: Using the total vertical load F and the total moment M, the pressure curve of the four outriggers during 360° rotation of the boom is obtained.

[0054] The XCA130L8C truck crane of Xugong adopts two groups of lifting parameters, as shown in Table 1.

[0055] Table 1: Two groups of lifting parameters of the XCA130L8C truck crane of Xugong

[0056] .

[0057] The planar size and outrigger number of the truck crane are shown in Figure 1 , and O point is the geometric center of the four outriggers, and ZT1, ZT2, ZT3 and ZT4 are the numbers of the four outriggers, respectively.

[0058] When the static load type test of the truck crane is performed, the equivalent load on O point is:

[0059] In S1, according to the design requirements of the crane, the truck crane should not overturn around any overturning line (the edge line of the rectangle formed by the four outriggers) during the static load type test, and after the total vertical load of the truck crane is equivalent to O point, as shown in Figure 2 , the allowable total vertical load F n on O point is obtained.

[0060] (1);

[0061] In the formula, m1 represents the truck self weight, m2 represents the detachable counterweight mass, m3 represents the auxiliary boom mass, Q n represents the rated lifting capacity, and g represents the acceleration of gravity;

[0062] According to the anti-overturning requirement, the allowable total moment M n on O point is obtained:

[0063] (2);

[0064] In the formula, k represents the overturning moment to stabilizing moment proportionality coefficient, k is 0.9, a represents the outrigger longitudinal span, and b represents the outrigger transverse span;

[0065] M n is divided into two parts, the moment M 1n related to the lifting capacity and the moment M 2n unrelated to the lifting capacity:

[0066] (3);

[0067] (4);

[0068] In the formula, R represents the working radius, and L represents the boom length. φ This is the dynamic load factor. φ Take 1.15, α II α is the maximum sway angle of the lifting wire rope. II Take 5°.

[0069] During the static load type test of the truck crane, the parameters in Table 1 are substituted into formulas (1) to (4) to obtain the equivalent load on point O as shown in Table 2.

[0070] Table 2: Equivalent load at point O during static load type test of truck crane

[0071] .

[0072] The equivalent load on point O during truck crane operation:

[0073] In S2, when the truck crane is in operation, only the lifting capacity changes, and the dynamic load factor should be considered. The remaining parameters are the same as in the type test. For the total vertical load F and total moment M at point O, as follows... Figure 3 As shown, calculate using the following formula:

[0074] (5);

[0075] (6);

[0076] (7);

[0077] In the formula, M1 represents the torque related to the lifting capacity, Q1 represents the hook mass, and Q2 represents the mass of the slings and the maximum lifted load. When the forward tilting moment is reached, The moment is the backward tilting moment.

[0078] When the truck crane is in operation, substitute the parameters in Table 1 and Table 2 into formulas (5) to (7) to obtain the equivalent load on point O as shown in Table 3.

[0079] Table 3: Equivalent load on point O during truck crane operation

[0080] .

[0081] Outrigger pressure of truck crane:

[0082] In S3, the total torque Using the right-hand rule, the boom direction is... Direction perpendicular, such as Figure 4 As shown, assuming The rotation angle is , When in the same direction as the x-axis Counterclockwise is positive, and the pressures of the four outriggers are N1, N2, N3, and N4 respectively:

[0083] (8);

[0084] (9);

[0085] (10);

[0086] (11);

[0087] In the formula, F represents the total vertical load, M represents the total moment, θ represents the rotation angle of the total moment, a represents the longitudinal span of the outrigger, and b represents the lateral span of the outrigger.

[0088] Since the four outriggers are symmetrically distributed and the load acts on the center point O of the outriggers, we can analyze only the case when M is in the first quadrant. When M is in the first quadrant, N2 is minimum and N4 is maximum, and the conditions for the extreme values ​​are as follows: ,if This indicates that all four outriggers are under pressure, such as Figure 5 As shown; if This indicates that the outrigger corresponding to N2 has lifted off the ground, such as... Figure 6 As shown, the formulas for calculating N1, N3, and N4 for pressure redistribution are:

[0089] (12);

[0090] (13);

[0091] (14);

[0092] When M is in the first quadrant, substitute a and b from Table 1 into... , can be obtained When N2 and N4 reach extreme values, substitute F and M from Table 3 into formulas (9) and (11) to obtain the extreme values ​​of N2 and N4 as shown in Table 4.

[0093] Table 4: Extreme values ​​of N2 and N4 when M is located in the first quadrant

[0094] .

[0095] Under both sets of parameters, the minimum value of N2 is greater than 0, indicating that all four outriggers are under pressure. When the boom rotates 360°, substituting F and M from Table 3 into formulas (8) to (11), the relationship curves between the pressure N of each outrigger and the rotation angle θ are as follows:Figure 7 , Figure 8 As shown.

[0096] Foundation bearing capacity verification:

[0097] To reduce the ground pressure under the outriggers, a 6m² area (A) is laid under each of the four outriggers. 2 The roadbed box has legs located at its center, and the box's self-weight (m) is 0.6t. According to the engineering geological survey report, the characteristic value of the foundation bearing capacity (f) is... ak The bearing capacity is 120 kPa. Since the roadbed box is located on the ground surface and its width is not large, the corrected characteristic value of the foundation bearing capacity can be used. .

[0098] In S3, the outrigger pressure is a standard value. The formula for calculating the foundation pressure p caused by the maximum outrigger pressure and the self-weight of the roadbed box is:

[0099] (15);

[0100] In the formula, N max The maximum value of the outrigger pressure is represented by m, the mass of the roadbed box under a single outrigger is represented by g, and A is represented by the area of ​​the roadbed box under a single outrigger. The ground pressure obtained from the maximum value of N4 in Table 4 is shown in Table 5.

[0101] Table 5: Calculation Results of Foundation Pressure

[0102] .

[0103] The formula for verifying the bearing capacity of the foundation under the maximum outrigger pressure is as follows:

[0104] (16);

[0105] In the formula, p represents the foundation pressure, and f a This represents the corrected characteristic value of the foundation bearing capacity. In Table 5, p is always less than f. a This indicates that the bearing capacity of the foundation meets the requirements.

[0106] Based on the actual working conditions of truck cranes and combined with crane design requirements, this invention proposes a method for calculating the outrigger pressure of truck cranes. Compared with actual measurement data, the deviation rate of the calculation results is small, the accuracy of the calculation results is high, it is practical and convenient, and it effectively improves the safety of truck crane operation.

[0107] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A method for calculating the outrigger pressure of a truck crane, characterized in that, include: A truck crane includes a chassis, four outriggers, a slewing mechanism, a counterweight, and a rotatable and luffing boom. The boom is used for lifting items, and the center of the four outriggers is point O. S1: The entire vertical load of the truck crane is equivalently transferred to point O, the center of the four outriggers. Based on the static load type test, the truck crane should not overturn. The allowable total vertical load F at point O is obtained. n And allowable total torque M n ; S2: Based on the fact that only the lifting capacity changes during the operation of the truck crane, the total vertical load F and total moment M at point O are obtained; S3: Using the total vertical load F and the total moment M, obtain the pressure curves of the four outriggers when the boom rotates 360°; In step S1, after equivalently transferring all the vertical loads of the truck crane during the static load type test to point O, the allowable total vertical load F acting on point O is obtained. n : （1）； In the formula, m1 represents the tare weight of the truck crane, m2 represents the detachable counterweight mass, m3 represents the mass of the jib, and Q... n This indicates the rated lifting capacity, and g represents the acceleration due to gravity. Based on the anti-overturning requirements, the allowable total torque M acting at point O is obtained. n : （2）； In the formula, k represents the ratio coefficient of overturning moment to stabilizing moment, k is taken as 0.9, a represents the longitudinal span of the outrigger, and b represents the lateral span of the outrigger. M n Divided into torque M related to lifting capacity 1n Torque M independent of lifting capacity 2n Two parts: （3）； （4）； In the formula, R represents the working radius, and L represents the boom length. φ This is the dynamic load factor. φ Take 1.15, α II α is the maximum sway angle of the lifting wire rope. II Take 5°.

2. The method for calculating the outrigger pressure of a truck crane according to claim 1, characterized in that, In S2, when the truck crane is in operation, only the lifting capacity changes, and the dynamic load factor should be considered. The remaining parameters are the same as in the type test. The total vertical load F and total moment M at point O are calculated according to the following formulas: （5）； （6）； （7）； In the formula, M1 represents the torque related to the lifting capacity, Q1 represents the hook mass, and Q2 represents the mass of the slings and the maximum lifted load. When the forward tilting moment is reached, The moment is the backward tilting moment.

3. The method for calculating the outrigger pressure of a truck crane according to claim 2, characterized in that, In S3, the total torque M is expressed using the right-hand rule, with the boom direction perpendicular to the M direction. Assuming the slewing angle of M is θ, and M is in the same direction as the x-axis... Counterclockwise is positive, and the pressures of the four outriggers are N1, N2, N3, and N4 respectively: （8）； （9）； （10）； （11）； In the formula, F represents the total vertical load, M represents the total moment, θ represents the slewing angle of the total moment, a represents the longitudinal span of the outrigger, and b represents the lateral span of the outrigger.

4. The method for calculating the outrigger pressure of a truck crane according to claim 2, characterized in that, When M is in the first quadrant, N2 is at its minimum and N4 is at its maximum. The conditions for the occurrence of extreme values ​​are as follows: ,if This indicates that all four outriggers are under pressure. This indicates that the outrigger corresponding to N2 has lifted off the ground, resulting in pressure redistribution. The formulas for calculating N1, N3, and N4 are as follows: （12）； （13）； （14）； Because the four outriggers are symmetrically distributed, the load acts on the center point O of the four outriggers. The same applies when M is located in other quadrants.

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