Crawler crane ground contact pressure calculation method

Abstract

The application discloses a kind of crawler crane ground contact pressure calculation methods, including the equivalent transfer of the total vertical load of crawler crane to the center O point of two crawlers, according to static load type test, crawler crane should not occur overturning, obtain the total vertical load F of the allowable O point n And allowable total moment M n ; According to the change of only lifting weight when crawler crane is working, the total vertical load F and total moment M of the O point are obtained;Using total vertical load F and total moment M, the relationship curve of each point ground contact pressure σ of crawler and M rotation angle θ when jib 360 ° rotation is obtained.The application proposes a practical and effective calculation method for the ground contact pressure of crawler crane, compared with actual measurement data, the deviation rate of calculation result is smaller, the calculation result accuracy is higher, practical and convenient, can effectively improve the safety of crawler crane work.

Description

Technical Field

[0001] This invention relates to the field of crawler crane technology, and more specifically to a method for calculating the ground pressure of a crawler crane track. Background Technology

[0002] A crawler crane is a self-propelled crane that uses tracks for movement and a boom for lifting. Crawler cranes have a large ground contact area, good maneuverability, and can travel with a load, making them widely used in construction industries such as municipal engineering, power, bridges, petrochemicals, and water conservancy and hydropower.

[0003] Tracked cranes consist of a frame, chassis, two tracks, slewing mechanism, boom, counterweight, etc. Their instruction manuals typically only provide parameters such as track dimensions and center distance, average ground pressure, self-weight of the main boom and auxiliary boom, counterweight, and lifting performance, but do not provide the mass and center of gravity of each component. This makes accurately calculating the ground pressure during lifting extremely difficult. Current methods for calculating ground pressure rely on empirical formulas, resulting in significant deviations, sometimes even differing by a factor of two. These formulas are either overly conservative or unsafe. Therefore, a universal and accurate method for calculating ground pressure is urgently needed. Summary of the Invention

[0004] To address the problems existing in the prior art, a method for calculating the ground pressure of a tracked crane track is provided.

[0005] The technical solution adopted by this invention to solve its technical problem is:

[0006] This invention proposes a method for calculating the ground pressure ratio of a tracked crane track, including:

[0007] A crawler crane consists of a body, chassis, two tracks, slewing mechanism, boom, and counterweight. The center of the two tracks is point O.

[0008] S1: The entire vertical load of the crawler crane is equivalently transferred to point O, the center of the two tracks. Based on the static load type test, the crawler crane should not overturn. The allowable total vertical load F at point O is obtained. n And allowable total torque M n ;

[0009] S2: Based on the fact that only the lifting capacity changes during the operation of the crawler crane, the total vertical load F and total moment M about point O are obtained;

[0010] S3: Using the total vertical load F and the total moment M, the relationship curve between the ground pressure σ at each point of the track and the rotation angle θ of M is obtained when the boom rotates 360°.

[0011] Preferably, the design self-weight m0 of the crawler crane is calculated according to the following formula based on the average ground pressure σ0:

[0012] m0=2σ0ca / g (1)

[0013] In the formula, σ0 represents the average ground pressure of the crawler crane, a represents the grounding length of one side of the track, c represents the width of one side of the track, and g represents the acceleration due to gravity.

[0014] Preferably, in step S1, after equivalently transferring all the vertical loads of the crawler crane during the static load type test to point O, the allowable total vertical load F acting on point O is obtained. n :

[0015] F n = (m0-m1+m2+m3+m4)g+1.25Q n g (2)

[0016] In the formula, m0 represents the design self-weight of the crawler crane, m1 represents the basic boom mass, m2 represents the main boom mass, m3 represents the auxiliary boom mass, m4 represents the super-lift counterweight mass, and Q... n This indicates the rated lifting capacity, and g represents the acceleration due to gravity.

[0017] Based on the anti-overturning requirements, the allowable total torque M acting at point O is obtained. n :

[0018] M n =k×min{F n a / 2,F n b / 2} (3)

[0019] In the formula, k represents the ratio coefficient of overturning moment to stabilizing moment, k is taken as 0.9, a represents the single-sided track ground contact length, and b represents the track center distance;

[0020] M n Divided into torque M related to lifting capacity 1n Torque M independent of lifting capacity 2n Two parts:

[0021]

[0022]

[0023] In the formula, R represents the working radius, L represents the boom length, φ is the dynamic load coefficient, φ is taken as 1.15, and α II α is the maximum sway angle of the lifting wire rope. II Take 5°.

[0024] Preferably, in step S2, when the crawler crane is operating, only the lifting capacity changes, and the dynamic load factor should be considered. The remaining parameters are the same as during the type test. The total vertical load F and total moment M at point O are calculated according to the following formulas:

[0025] F=(m0-m1+m2+m3+m4)g+φ(Q1+Q2)g (6)

[0026] M = M1 + M 2n (7)

[0027]

[0028] In the formula, M1 represents the torque related to the lifting capacity, Q1 represents the hook mass, and Q2 represents the sling and the maximum lifting mass. When M > 0, it is the forward tilting moment, and when M < 0, it is the backward tilting moment.

[0029] Preferably, in S3, the total torque M is expressed using the right-hand rule, the boom direction is perpendicular to the M direction, and the rotation angle of M is assumed to be θ. When M is in the same direction as the x-axis, θ = 0°, and counterclockwise is positive. The two tracks are respectively called track I and track II.

[0030] Torque M of track I I Axial pressure P I Calculate using the following formula:

[0031]

[0032]

[0033] Torque M of Track II II Axial pressure P II Calculate using the following formula:

[0034]

[0035]

[0036] In the formula, F represents the total vertical load, M represents the total torque, θ represents the rotation angle of the total torque, a represents the single-side track ground contact length, and b represents the track center distance.

[0037] Preferably, the front and rear ends of track I and track II are denoted as D1 and D4, and D2 and D3, respectively, and the ground pressure at the corresponding points are denoted as σ1 and σ4, and σ2 and σ3, respectively. When points D1, D2, D3, and D4 are not off the ground, σ1, σ2, σ3, and σ4 are calculated according to the following formulas:

[0038]

[0039]

[0040]

[0041]

[0042] In the formula, F represents the total vertical load, M represents the total torque, θ represents the rotation angle of the total torque, a represents the single-side track ground contact length, b represents the track center distance, and c represents the single-side track width.

[0043] Preferably, when M is located in the first quadrant, σ2 is the smallest and σ4 is the largest. The condition for the occurrence of extreme values ​​is θ = arctan(a / 3b), which is the most unfavorable rotation angle of M in the first quadrant. The values ​​of σ1, σ2, σ3, and σ4 can be obtained using the most unfavorable rotation angle.

[0044] If σ2≥0 at the most unfavorable turning angle, it means that points D1, D2, D3, and D4 have not left the ground. Then, formulas (13) to (16) are used to calculate the grounding specific pressure.

[0045] If σ2 < 0 at the most unfavorable turning angle, it means that point D2 of track II has left the ground and is no longer under pressure. The pressure of track II is redistributed, and at this time σ2 = 0. σ3 is calculated according to the following formula:

[0046]

[0047]

[0048]

[0049] If σ1 < 0 at the most unfavorable turning angle, it means that point D1 of track I has also left the ground and is no longer under pressure, and the pressure on track I is redistributed. At this time, σ1 = 0, and σ4 is calculated according to the following formula:

[0050]

[0051]

[0052]

[0053] In the formula, l II e represents the actual ground contact length of track II after point D2 leaves the ground. II Indicates the eccentricity of track II, l I This indicates the actual ground contact length of track I after point D1 leaves the ground; e I Indicates the eccentricity of track I;

[0054] Since the two tracks are symmetrically distributed, the load acts on the center point O of the two tracks. This can be deduced similarly when M is located in other quadrants.

[0055] Compared with the prior art, the beneficial effects of the present invention are:

[0056] Based on the actual working conditions of crawler cranes and combined with the design requirements of cranes, this invention proposes a method for calculating the grounding specific voltage of crawler cranes. The method has been tested and compared. Compared with the 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 effectively improves the safety of crawler crane operation. Attached Figure Description

[0057] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0058] Figure 1 This is a diagram showing the planar dimensions and track numbering of the crawler crane in this invention;

[0059] Figure 2 This is the equivalent load diagram during the static load type test in this invention;

[0060] Figure 3 This is the equivalent load diagram during lifting operations in this invention;

[0061] Figure 4 This is a diagram showing the direction of the total torque and its rotation angle in this invention;

[0062] Figure 5 This is a schematic diagram of the force analysis of track I in this invention;

[0063] Figure 6 This is a schematic diagram of the force analysis of track II in this invention;

[0064] Figure 7 This is a schematic diagram of the ground pressure distribution of track II in this invention;

[0065] Figure 8 This is a schematic diagram of the ground pressure distribution of track I in this invention;

[0066] Figure 9 This is a graph showing the relationship between grounding specific voltage and total torque rotation angle when considering the first set of parameters in this invention.

[0067] Figure 10 This is a graph showing the relationship between grounding specific voltage and total torque rotation angle when using the second set of parameters in this invention. Detailed Implementation

[0068] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0069] Reference Appendix Figure 1-10This embodiment proposes a method for calculating the ground pressure ratio of a tracked crane track, including:

[0070] A crawler crane includes a body, chassis, two tracks, slewing mechanism, boom, counterweight, etc., with the center of the two tracks being point O.

[0071] S1: The entire vertical load of the crawler crane is equivalently transferred to point O, the center of the two tracks. Based on the static load type test, the crawler crane should not overturn. The allowable total vertical load F at point O is obtained. n And allowable total torque M n ;

[0072] S2: Based on the fact that only the lifting capacity changes during the operation of the crawler crane, the total vertical load F and total moment M about point O are obtained;

[0073] S3: Using the total vertical load F and the total moment M, the relationship curve between the ground pressure σ at each point of the track and the rotation angle θ of M is obtained when the boom rotates 360°.

[0074] The SANY SCC800A crawler crane uses two sets of lifting parameters, as shown in Table 1.

[0075] Table 1: Two sets of lifting parameters for the Sany Heavy Industry SCC800A crawler crane

[0076]

[0077] Note: The main boom mass m2 includes the basic boom mass m1; without a superlift device, m3 = m4 = 0.

[0078] The plan dimensions and track numbers of the crawler crane are as follows: Figure 1 As shown, point O is the geometric center of the two tracks. The ground contact points at the front and rear ends of track I are designated as D1 and D4, respectively, and the ground contact points at the front and rear ends of track II are designated as D2 and D3, respectively.

[0079] The design weight m0 of the crawler crane can be calculated based on the average ground pressure σ0 using the following formula:

[0080] m0=2σ0ca / g (1)

[0081] In the formula, σ0 represents the average ground pressure of the crawler crane, a represents the grounding length of one side of the track, c represents the width of one side of the track, and g represents the acceleration due to gravity.

[0082] The equivalent load at point O during the static load type test of the crawler crane is:

[0083] In S1, according to the design requirements of crawler cranes, the crawler crane should not overturn around any overturning line (the rectangular side line composed of D1, D2, D3, and D4) during the static load test. After equivalently transferring all the vertical load of the crawler crane to point O, if... Figure 2 As shown, the allowable total vertical load F acting at point O is obtained. n :

[0084] F n = (m0-m1+m2+m3+m4)g+1.25Q n g (2)

[0085] In the formula, m0 represents the design self-weight of the crawler crane, m1 represents the basic boom mass, m2 represents the main boom mass, m3 represents the auxiliary boom mass, m4 represents the super-lift counterweight mass, and Q... n This indicates the rated lifting capacity, and g represents the acceleration due to gravity.

[0086] Based on the anti-overturning requirements, the allowable total torque M acting at point O is obtained. n :

[0087] M n =k×min{F n a / 2,F n b / 2} (3)

[0088] In the formula, k represents the ratio coefficient of overturning moment to stabilizing moment, k is taken as 0.9, a represents the single-side track ground contact length, and b represents the track center distance.

[0089] M n Divided into torque M related to lifting capacity 1n Torque M independent of lifting capacity 2n Two parts:

[0090]

[0091] M 2n =M n -M 1n (5)

[0092] In the formula, R represents the working radius, L represents the boom length, φ is the dynamic load coefficient, φ is taken as 1.15, and α II α is the maximum sway angle of the lifting wire rope. II Take 5°.

[0093] During the static load type test of the crawler crane, the parameters in Table 1 are substituted into formulas (1) to (5) to obtain the equivalent load on point O as shown in Table 2.

[0094] Table 2: Equivalent load on point O during static load type test of crawler crane

[0095]

[0096] The equivalent load on point O during crawler crane operation:

[0097] In S2, when the crawler 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:

[0098] F=(m0-m1+m2+m3+m4)g+φ(Q1+Q2)g (6)

[0099] M = M1 + M 2n (7)

[0100]

[0101] In the formula, M1 represents the torque related to the lifting capacity, Q1 represents the hook mass, and Q2 represents the sling and the maximum lifting mass. When M > 0, it is the forward tilting moment, and when M < 0, it is the backward tilting moment.

[0102] When the crawler crane is in operation, the equivalent load on point O can be obtained by substituting the parameters in Table 1 and Table 2 into formulas (6) to (8), as shown in Table 3.

[0103] Table 3: Equivalent load on point O during crawler crane operation

[0104]

[0105] Grounding specific voltage of crawler cranes:

[0106] In S3, the total torque M is expressed using the right-hand rule, with the boom direction perpendicular to the M direction, such as... Figure 4 As shown, assume the rotation angle of M is θ. When M is in the same direction as the x-axis, θ = 0°, and counterclockwise is positive.

[0107] Torque M of track I I Axial pressure P I Calculate using the following formula:

[0108]

[0109]

[0110] Torque M of Track II II Axial pressure P II Calculate using the following formula:

[0111]

[0112]

[0113] In the formula, F represents the total vertical load, M represents the total torque, θ represents the rotation angle of the total torque, a represents the single-side track ground contact length, and b represents the track center distance.

[0114] When none of the points on the two tracks have left the ground, the ground contact specific pressures σ1, σ2, σ3, and σ4 at points D1, D2, D3, and D4 are calculated using the following formulas:

[0115]

[0116]

[0117]

[0118]

[0119] In the formula, F represents the total vertical load, M represents the total torque, θ represents the rotation angle of the total torque, a represents the single-side track ground contact length, b represents the track center distance, and c represents the single-side track width.

[0120] When M is in the first quadrant, σ2 is the smallest and σ4 is the largest. The condition for σ2 and σ4 to have extreme values ​​is θ = arctan(a / 3b). Substituting a and b from Table 1 into the equation, we can get θ = 23.6°, which is the most unfavorable turning angle. Substituting θ, a, b and F and M from Table 3 into formulas (13) to (16), we can get the values ​​of σ1, σ2, σ3 and σ4 at the most unfavorable turning angle, as shown in Table 4.

[0121] Table 4: σ1, σ2, σ3, σ4 at the most unfavorable turning angle

[0122]

[0123] Under both sets of parameters, σ² at the most unfavorable turning angle is not less than 0, indicating that neither track has left the ground. Figure 5 , Figure 6 As shown.

[0124] When the boom rotates 360°, substituting the relevant parameters from Tables 1 and 3 into formulas (13) to (16) yields the relationship curves between the ground pressure at points D1, D2, D3, and D4 and the total torque rotation angle, as shown below. Figure 9 , Figure 10 As shown.

[0125] Foundation bearing capacity verification:

[0126] According to the engineering geological survey report, the corrected characteristic value of the foundation bearing capacity f a=200kPa. Under axial load, the bearing capacity of the foundation should meet the following requirement:

[0127] σ max ≤f a (17)

[0128] In the formula, σ max This indicates the maximum grounding specific voltage.

[0129] The maximum grounding specific voltage under both sets of parameters in Table 4 is less than f. a The bearing capacity of the foundation meets the requirements.

[0130] The track grounding specific voltage was tested on-site using a grounding specific voltage tester under the two sets of parameters in Table 1. For the first set, the rotation angle θ of M was 50°, and for the second set, the rotation angle θ of M was 130°. The measured and calculated grounding specific voltage values ​​are shown in Table 5. It can be seen that the maximum deviation of the calculated value from the measured value is less than 10%, indicating high accuracy.

[0131] Table 5: Measured and Calculated Values ​​of Grounding Specific Voltage

[0132]

[0133] Based on the actual working conditions of crawler cranes and combined with the design requirements of cranes, this invention proposes a method for calculating the grounding specific voltage of crawler cranes. The method has been tested and compared. Compared with the 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 effectively improves the safety of crawler crane operation.

[0134] 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 grounding specific voltage of a tracked crane track, characterized in that, include: A crawler crane consists of a body, chassis, two tracks, slewing mechanism, boom, and counterweight. The center of the two tracks is point O. S1: The entire vertical load of the crawler crane is equivalently transferred to the center point O of the two tracks. Based on the static load type test, the crawler 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 crawler crane, the total vertical load F and total moment M about point O are obtained; S3: Using the total vertical load F and the total moment M, the relationship curve between the ground pressure σ at each point of the track and the rotation angle θ of M when the boom rotates 360° is obtained; 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 two tracks are respectively called track I and track II; Torque M of track I I Axial pressure P I Calculate using the following formula: （9） （10） Torque M of Track II II Axial pressure P II Calculate using the following formula: （11） （12） In the formula, F represents the total vertical load, M represents the total torque, θ represents the rotation angle of the total torque, a represents the single-side track ground contact length, and b represents the track center distance. The front and rear endpoints of track I and track II are denoted as D1 and D4, and D2 and D3, respectively. The ground pressure at the corresponding points is denoted as σ1 and σ4, and σ2 and σ3, respectively. When points D1, D2, D3, and D4 are not off the ground, σ1, σ2, σ3, and σ4 are calculated according to the following formulas: （13） （14） （15） （16） 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 single-side track ground contact length, b represents the track center distance, and c represents the single-side track width. When M is in the first quadrant Minimum, The conditions for the maximum and the occurrence of extreme values ​​are all That is, the most unfavorable rotation angle of M in the first quadrant. The values ​​of σ1, σ2, σ3, and σ4 can be obtained using the most unfavorable rotation angle. If the most unfavorable turning angle is If D1, D2, D3, and D4 are not off the ground, then formulas (13) to (16) are used to calculate the grounding specific voltage. If the most unfavorable turning angle is This indicates that point D2 of track II has detached from the ground and is no longer under pressure, and the pressure on track II is redistributed. , Calculate using the following formula: （17） （18） （19） If the most unfavorable turning angle is This indicates that point D1 of track I has also left the ground and is no longer under pressure, and the pressure on track I has been redistributed. , Calculate using the following formula: （20） （21） （22） In the formula, l II e represents the actual ground contact length of track II after point D2 leaves the ground. II Indicates the eccentricity of track II, l I This indicates the actual ground contact length of track I after point D1 leaves the ground; e I Indicates the eccentricity of track I; Since the two tracks are symmetrically distributed, the load acts on the center point O of the two tracks. This can be deduced similarly when M is located in other quadrants.

2. The method for calculating the grounding specific voltage of a tracked crane track according to claim 1, characterized in that, The design weight m0 of the crawler crane is calculated according to the average ground pressure σ0 using the following formula: （1） In the formula, σ0 represents the average ground pressure of the crawler crane, a represents the grounding length of one side of the track, c represents the width of one side of the track, and g represents the acceleration due to gravity.

3. The method for calculating the ground pressure ratio of a tracked crane track according to claim 1, characterized in that, In step S1, after equivalently transferring all the vertical loads of the crawler crane during the static load type test to point O, the allowable total vertical load F acting on point O is obtained. n : （2） In the formula, m0 represents the design self-weight of the crawler crane, m1 represents the basic boom mass, m2 represents the main boom mass, m3 represents the auxiliary boom mass, m4 represents the super-lift counterweight mass, 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 : （3） In the formula, k represents the ratio coefficient of overturning moment to stabilizing moment, k is taken as 0.9, a represents the single-sided track ground contact length, and b represents the track center distance; M n Divided into torque M related to lifting capacity 1n Torque M independent of lifting capacity 2n Two parts: （4） （5） In the formula, R represents the working radius, L represents the boom length, ϕ is the dynamic load coefficient (ϕ is taken as 1.15), and α... II α is the maximum sway angle of the lifting wire rope. II Take 5°.

4. The method for calculating the grounding specific voltage of a tracked crane track according to claim 3, characterized in that, In S2, when the crawler 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: （6） （7） （8） 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.

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