A method of aligning a marine propulsion shafting and a system therefor

Abstract

The application relates to a ship propulsion shafting alignment method and system, which comprises the following steps: establishing a first propulsion shafting alignment calculation model of a rear bearing of a stern shaft, defining a dimensionless proportion; obtaining an average specific pressure parameter based on the first propulsion shafting alignment calculation model; obtaining an equivalent support point axial distance proportion of the rear bearing of the stern shaft based on the average specific pressure of each support point and the dimensionless proportion; obtaining a second propulsion shafting alignment calculation model of single-point support of the rear bearing of the stern shaft based on the first propulsion shafting alignment calculation model and the equivalent support point axial distance proportion of the rear bearing of the stern shaft; fitting a distribution relationship formula of the wear of the rear bearing of the stern shaft along the axial direction based on the average specific pressure of each support point, the dimensionless proportion and the second propulsion shafting alignment calculation model, and calculating the equivalent wear of the rear bearing of the stern shaft; and adjusting the alignment state of the shafting to meet the specification requirements based on the equivalent wear of the rear bearing of the stern shaft and the wear of the front bearing of the stern shaft calculated according to the simultaneous equations of the front and rear bearings.

Description

Technical Field

[0001] This application relates to the field of ship propulsion shafting, and in particular to a method and system for aligning ship propulsion shafting. Background Technology

[0002] Traditional shaft alignment does not take into account the wear changes of the stern water-lubricated bearings, thus presenting the following problems in practical applications:

[0003] First, according to the requirements of ship propulsion shaft repair specifications, the maximum allowable wear of water-lubricated bearings can be 2.7mm to 8.1mm depending on the shaft diameter and material. Bearing wear will have a significant impact on its elevation, and thus a significant impact on the load of each bearing.

[0004] Secondly, the wear state of the stern bearing in the propulsion shafting system is nonlinear under the cantilever load of the propeller. In addition, the two bearings in the water-lubricated stern section, namely the forward stern bearing and the aft stern bearing, have different loads and shaft diameters, and their wear amounts are also different. Therefore, it is not possible to directly use the maximum wear amount required by the standard to calculate the change in the elevation of the water-lubricated stern bearing to analyze the shafting alignment status.

[0005] Therefore, proper alignment carried out using traditional methods can ensure that the system maintains a good condition during the initial installation and operation phases. However, as the operating time increases, the nonlinear wear of the bearings will cause significant changes in the alignment of the shaft system, resulting in poor bearing condition during actual operation and posing a risk to the safe operation of the system. Summary of the Invention

[0006] This application provides a method and system for aligning a ship propulsion shaft system, which can solve the problem that in related technologies, reasonable alignment carried out by traditional methods will result in poor bearing condition during actual operation as the operating time increases, posing a risk to the safe operation of the system.

[0007] In a first aspect, embodiments of this application provide a method for aligning a ship's propulsion shafting, comprising:

[0008] A calculation model for centering the first propulsion shaft system with multi-point support of the rear bearing is established, and a dimensionless proportion is defined.

[0009] Based on the first propulsion shaft alignment calculation model, the average specific pressure parameter is obtained, which includes the average specific pressure of each support point of the stern shaft aft bearing;

[0010] Based on the average specific pressure and dimensionless proportion of each support point, the axial distance proportion of the equivalent support point of the stern shaft rear bearing is obtained;

[0011] Based on the first propulsion shaft alignment calculation model and the axial distance ratio of the equivalent support point of the stern shaft bearing, the second propulsion shaft alignment calculation model with single-point support of the stern shaft bearing is obtained;

[0012] Based on the average specific pressure at each support point, the dimensionless proportion, and the second propulsion shaft alignment calculation model, the distribution relationship of the wear amount of the stern shaft rear bearing along the axial direction is fitted, and the equivalent wear amount of the stern shaft rear bearing is calculated.

[0013] Based on the equivalent wear of the aft bearing and the wear of the fore stern bearing calculated using the simultaneous equations relating the wear of the fore and aft bearings, the alignment of the shaft system is adjusted to meet the specifications.

[0014] In conjunction with the first aspect, in one implementation method, a dimensionless proportion is defined, specifically including:

[0015] Determine the measured length of the bearing bush and the number of support points;

[0016] Based on the measured value of the bearing length and the number of support points, the actual distance of each support point from the stern end of the stern shaft bearing is obtained;

[0017] The actual distance of each support point from the stern end of the stern bearing is dimensionless and converted into a percentage of the bearing length to define a dimensionless percentage.

[0018] In conjunction with the first aspect, in one implementation, based on the first propulsion shaft alignment calculation model and the axial distance ratio of the equivalent support point of the stern shaft bearing, a second propulsion shaft alignment calculation model with single-point support of the stern shaft bearing is obtained, specifically including:

[0019] The position of the single-point support is determined based on the axial distance ratio of the equivalent support point of the stern shaft bearing, and the multi-point support of the stern shaft bearing in the first propulsion shaft alignment calculation model is replaced with a single-point support to obtain the second propulsion shaft alignment calculation model with the single-point support of the stern shaft bearing.

[0020] In conjunction with the first aspect, in one implementation, based on the average specific pressure at each support point, the dimensionless proportion, and the second propulsion shaft alignment calculation model, the axial distribution relationship of the stern shaft aft bearing wear is fitted, and the equivalent wear of the stern shaft aft bearing is calculated, specifically including:

[0021] Based on the average specific pressure at each support point, the dimensionless proportion, and the second propulsion shaft alignment calculation model, the distribution relationship of the wear amount of the stern shaft rear bearing along the axial direction is obtained;

[0022] Based on the distribution relationship and the proportion of the axial distance of the equivalent fulcrum of the stern shaft aft bearing, the equivalent wear amount of the stern shaft aft bearing is obtained.

[0023] In conjunction with the first aspect, in one implementation, based on the average specific pressure at each support point, the dimensionless proportion, and the second propulsion shaft alignment calculation model, the axial distribution relationship of the stern shaft aft bearing wear is obtained, specifically including:

[0024] A fifth-order polynomial fitting of the specific pressure distribution was performed in the calculation model for the alignment of the second propulsion shaft system to obtain the fitting results;

[0025] Based on the average specific pressure, dimensionless proportion, and fitting results of each support point, the distribution relationship of the wear amount of the stern shaft rear bearing along the axial direction is obtained.

[0026] In conjunction with the first aspect, in one implementation method, based on the average specific pressure at each support point, the dimensionless proportion, and the fitting results, the axial distribution relationship of the stern shaft aft bearing wear is obtained, specifically including:

[0027] Based on the average specific pressure, dimensionless proportion, and fitting results of each support point, the initial distribution relationship is obtained.

[0028] Based on the preset maximum wear amount, the proportional coefficient in the initial distribution formula is determined to obtain the axial distribution formula of the wear amount of the stern shaft rear bearing.

[0029] In conjunction with the first aspect, in one implementation, the alignment of the shaft system is adjusted to meet specification requirements based on the equivalent wear of the aft bearing and the wear of the fore stern bearing calculated according to the simultaneous equations relating the wear of the fore and aft bearings. Specifically, this includes:

[0030] The wear amount of the front stern shaft bearing is obtained based on the simultaneous equations relating the wear amounts of the front and rear bearings to the front stern shaft bearing and the equivalent wear amount of the rear stern shaft bearing.

[0031] Based on the equivalent wear of the aft bearing and the wear of the fore bearing, the alignment of the shaft system is adjusted to meet the specifications.

[0032] In conjunction with the first aspect, in one embodiment, the average specific pressure parameter further includes the average specific pressure of the forward stern shaft bearing and the overall average specific pressure of the aft stern shaft bearing.

[0033] In conjunction with the first aspect, in one embodiment, before obtaining the wear amount of the stern shaft front bearing based on the simultaneous equations relating the wear amounts of the front and rear bearings and the equivalent wear amount of the stern shaft rear bearing, the method further includes:

[0034] The steps to obtain the simultaneous equations for the wear of the front and rear bearings of the stern shaft bearing based on the average specific pressure of the front bearing and the overall average specific pressure of the rear bearing.

[0035] Secondly, embodiments of this application provide a ship propulsion shaft alignment system, comprising: a first module, a second module, a third module, a fourth module, a fifth module, and a sixth module. The first module is used to establish a first propulsion shaft alignment calculation model with multi-point support for the aft bearing and to define a dimensionless proportion. The second module is used to obtain an average specific pressure parameter based on the first propulsion shaft alignment calculation model, the average specific pressure parameter including the average specific pressure of each support point of the aft bearing. The third module is used to obtain the axial distance proportion of the equivalent support points of the aft bearing based on the average specific pressure of each support point and the dimensionless proportion. The fourth module is used to obtain the second propulsion shaft alignment calculation model with single-point support of the stern shaft bearing based on the first propulsion shaft alignment calculation model and the axial distance ratio of the equivalent support point of the stern shaft bearing. The fifth module is used to fit the axial distribution relationship of the stern shaft bearing wear based on the average specific pressure of each support point, the dimensionless ratio, and the second propulsion shaft alignment calculation model, and to calculate the equivalent wear of the stern shaft bearing. The sixth module is used to adjust the alignment state of the shaft system to meet the specification requirements based on the wear of the stern shaft bearing calculated by the simultaneous equations of the equivalent wear of the stern shaft bearing and the wear of the front and rear bearings of the stern shaft bearing.

[0036] The beneficial effects of the technical solutions provided in this application include:

[0037] This application provides a method and system for aligning a ship's propulsion shafting. By establishing a calculation model for aligning the first propulsion shafting with multi-point support of the aft bearing and the axial distance ratio of the equivalent support points of the aft bearing, the accuracy of wear prediction is improved. Furthermore, by establishing a simultaneous equation for the wear of the fore and aft bearings regarding the wear of the fore and aft bearings, the wear of the fore and aft bearings is ensured to meet the specifications simultaneously. This achieves dynamic inclusion of wear effects and can effectively guarantee that the alignment state of the ship's propulsion shafting meets the design requirements throughout the entire service life of the bearings, thus ensuring the safety of system operation. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 A flowchart of a ship propulsion shaft alignment method provided in this application embodiment;

[0040] Figure 2 This is a schematic diagram of the overall short-span shaft system provided in the embodiments of this application;

[0041] Figure 3The curves showing the distribution of average specific pressure at various points of the stern shaft bearing as a function of axial position are provided in the embodiments of this application.

[0042] In the diagram: 1. First flexible coupling; 2. First intermediate bearing; 3. First intermediate shaft; 4. Second intermediate shaft; 5. Second intermediate bearing; 6. Second flexible coupling; 7. Third intermediate shaft; 8. Thrust bearing; 9. Water-lubricated stern shaft front bearing; 10. Stern shaft; 11. Water-lubricated stern shaft rear bearing; 12. Propeller. Detailed Implementation

[0043] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.

[0044] This application provides a method and system for aligning a ship propulsion shafting system, which can solve the problem that in related technologies, reasonable alignment carried out by traditional methods will result in poor bearing condition during actual operation as the operating time increases, posing a risk to the safe operation of the system.

[0045] In a first aspect, embodiments of this application provide a method for aligning a ship's propulsion shafting, comprising:

[0046] 101: Establish a calculation model for centering the first propulsion shaft system with multi-point support of the stern shaft bearing, and define the dimensionless proportion;

[0047] 102: Based on the first propulsion shaft alignment calculation model, obtain the average specific pressure parameter, which includes the average specific pressure of each support point of the stern shaft aft bearing;

[0048] 103: Based on the average specific pressure and dimensionless proportion of each support point, obtain the axial distance proportion of the equivalent support point of the stern shaft rear bearing;

[0049] 104: Based on the first propulsion shaft alignment calculation model and the axial distance ratio of the equivalent support point of the stern shaft aft bearing, obtain the second propulsion shaft alignment calculation model with single-point support of the stern shaft aft bearing;

[0050] 105: Based on the average specific pressure of each support point, the dimensionless proportion, and the second propulsion shaft alignment calculation model, fit the distribution relationship of the wear amount of the stern shaft rear bearing along the axial direction, and calculate the equivalent wear amount of the stern shaft rear bearing.

[0051] 106: Based on the equivalent wear of the aft bearing and the wear of the fore stern bearing calculated according to the simultaneous equations of the wear of the fore and aft bearings, adjust the alignment of the shaft system to meet the specifications.

[0052] In this application, by establishing a calculation model for the alignment of the first propulsion shafting with multi-point support of the aft bearing and the axial distance ratio of the equivalent support points of the aft bearing, the accuracy of wear prediction is improved. Furthermore, by establishing a simultaneous equation for the wear of the front and rear bearings of the stern bearing, the wear of the front and rear bearings is ensured to meet the specifications simultaneously. This achieves dynamic inclusion of wear effects and can effectively guarantee that the alignment of the ship's propulsion shafting meets the design requirements throughout the entire service life of the bearings, thus ensuring the safety of system operation.

[0053] See Figure 2 As shown, the short-span shaft system of this embodiment includes a first flexible coupling 1, a first intermediate bearing 2, a first intermediate shaft 3, a second intermediate shaft 4, a second intermediate bearing 5, a second flexible coupling 6, a third intermediate shaft 7, a thrust bearing 8, a water-lubricated stern shaft front bearing 9, a stern shaft 10, a water-lubricated stern shaft rear bearing 11, and a propeller 12.

[0054] In step 101, the first propulsion shaft alignment calculation model with multi-point support of the stern shaft bearing is established. The shaft alignment calculation model is established in accordance with the requirements of CB / Z338-2005 "Ship Shaft Alignment". The measured value L of the bearing shell of the stern shaft bearing is obtained through actual measurement or design drawings.

[0055] When defining the dimensionless proportion, the specific steps include steps 1011 to 1013:

[0056] Step 1011: Determine the measured length of the bearing bush and the number of support points;

[0057] Step 1012: Based on the measured value of the bearing length and the number of support points, obtain the actual distance of each support point from the stern end of the stern bearing;

[0058] Step 1013: Dimensionlessly convert the actual distance of each support point from the stern end of the stern shaft bearing into a proportion of the bearing length to define a dimensionless proportion.

[0059] Specifically, determine the measured length L of the bearing bush and the number of support points n. The stern shaft aft bearing establishes n support points within its bearing bush length L. The number of n is determined according to the bearing length and the required calculation accuracy. Generally, n≥8 to ensure calculation accuracy.

[0060] Therefore, the actual distance from the i-th fulcrum to the stern end of the aft bearing is:

[0061]

[0062] For ease of subsequent calculations, the dimensionless ratio of the distance from the i-th fulcrum to the stern end of the aft bearing relative to the bearing length is defined as:

[0063]

[0064] In this embodiment, the support modeling of the stern shaft aft bearing needs to be based on the elastic support characteristics. It is assumed that its total stiffness is K, and n support points (n≥8) are evenly distributed within the bearing length L. The stiffness of each support point is equally distributed, which is K / n, so as to more accurately reflect the non-uniformity of load distribution within the bearing length. The stern shaft front bearing, thrust bearing 8, second intermediate bearing 5 and first intermediate bearing 2 are set as single support points according to the CB / Z338-2005 standard. The support point positions are all located at 0.5 times the bearing length of the corresponding bearing (geometric center). Other bearings (such as other intermediate bearings) can flexibly choose elastic support (considering the actual stiffness characteristics) or rigid support (simplifying the model) according to the calculation accuracy requirements, so as to balance the alignment accuracy and calculation efficiency while meeting the specification requirements, and ensure the reliability and safety of the shaft system in long-term operation.

[0065] Based on the above embodiments, in this embodiment, in step 102, the first propulsion shaft alignment calculation model performs shaft alignment analysis and calculates the average specific pressure Ri (i=1~10) of each support point of the stern shaft aft bearing and the average specific pressure Q of the stern shaft forward bearing. Simultaneously, the Ri value is used according to the formula:

[0066]

[0067] Calculate the overall average specific pressure R of the stern shaft rear bearing. h The number of support points n≥8 ensures the discretization accuracy of the load distribution within the bearing length, while the combination of elastic support modeling (stiffness K) and dimensionless axial distance ratio enables the specific pressure parameter to accurately reflect the mechanical characteristics of the shaft system under alignment, providing key data support for subsequent wear analysis and alignment error correction.

[0068] Based on the above embodiments, in this embodiment, in step 103, the average specific pressure Ri of each support point of the stern shaft bearing is combined with the corresponding dimensionless axial distance ratio Xi, and the axial distance ratio Xd of the equivalent support point of the stern shaft bearing is calculated using a weighted average formula, which is:

[0069]

[0070] Where Ri is the specific pressure data of each support point obtained in step 102, and Xi is the dimensionless proportion defined in 101. The force concentration area is located by the specific pressure weight, which provides key parameter support for the subsequent establishment of single-point support model and wear distribution analysis.

[0071] Based on the above embodiments, in this embodiment, a second propulsion shaft alignment calculation model with single-point support of the stern shaft bearing is obtained based on the first propulsion shaft alignment calculation model and the axial distance ratio of the equivalent support point of the stern shaft bearing. Specifically, this includes:

[0072] The position of the single-point support is determined based on the axial distance ratio of the equivalent support point of the stern shaft bearing, and the multi-point support of the stern shaft bearing in the first propulsion shaft alignment calculation model is replaced with a single-point support to obtain the second propulsion shaft alignment calculation model with the single-point support of the stern shaft bearing.

[0073] Specifically, in this step, the multi-point support structure of the stern shaft bearing is replaced with a single-point support by using the first propulsion shaft alignment calculation model based on the multi-point support of the stern shaft bearing established in step 101 and the axial distance ratio Xd of the equivalent support point of the stern shaft bearing calculated in step 103, so as to obtain the second propulsion shaft alignment calculation model with single-point support of the stern shaft bearing.

[0074] Specifically, this includes: using the axial distance ratio Xd of the equivalent support point of the stern shaft bearing as the position benchmark for single-point support, substituting it into the first propulsion shaft alignment calculation model, simplifying the original bearing length within n≥8 elastic support points (stiffness K / n) into a single support point (stiffness K or rigid support), thus forming the second propulsion shaft alignment calculation model. This model meets the requirements of the CB / Z338-2005 "Ship Shaft Alignment" specification, while ensuring the rationality of the alignment state through mechanical equivalence and significantly reducing the computational complexity, making it suitable for shaft design and maintenance scenarios with different precision requirements.

[0075] Based on the above embodiments, in this embodiment, based on the average specific pressure of each support point, the dimensionless proportion, and the second propulsion shaft alignment calculation model, the axial distribution relationship of the stern shaft aft bearing wear is fitted, and the equivalent wear of the stern shaft aft bearing is calculated, specifically including steps 1051 to 1052:

[0076] Step 1051: Based on the average specific pressure of each support point, the dimensionless proportion, and the second propulsion shaft alignment calculation model, obtain the distribution relationship of the wear amount of the stern shaft rear bearing along the axial direction.

[0077] First, a fifth-order polynomial fitting of the specific pressure distribution is performed in the calculation model for the alignment of the second propulsion shaft system to obtain the fitting results. Then, based on the average specific pressure at each support point, the dimensionless proportion, and the fitting results, the distribution relationship of the stern shaft aft bearing wear along the axial direction is obtained.

[0078] Specifically, based on the average specific pressure, dimensionless proportion, and fitting results of each support point, the distribution relationship of the wear amount of the stern shaft rear bearing along the axial direction is obtained. This includes: obtaining the initial distribution relationship based on the average specific pressure, dimensionless proportion, and fitting results of each support point; and determining the proportional coefficient in the initial distribution relationship based on the preset maximum wear amount to obtain the distribution relationship of the wear amount of the stern shaft rear bearing along the axial direction.

[0079] Specifically, in the second propulsion shaft alignment calculation model, based on the average specific pressure (R1, R2, ..., R) of each support point of the stern shaft aft bearing obtained in step 102, 10 The ratio of the dimensionless axial distance (X1, X2, ..., X...) to the dimensionless axial distance defined in step 101 10 A fifth-order polynomial fitting of the specific pressure distribution is performed to construct a continuous distribution function R(X) of the specific pressure along the axial position. Subsequently, combining the logic that the wear of the bearing is proportional to the specific pressure, the distribution relationship of the wear of the stern shaft bearing along the axial position is as follows: ;

[0080] The fitted R(X) is correlated with the preset maximum wear amount M allowed by the specification. Since the maximum wear amount is located at the stern end of the aft bearing, and is calculated based on the polynomial of the axial load distribution of the aft bearing, the value of K can be obtained from:

[0081] The calculations yielded the final formula for the distribution of wear along the axial position: Y(X)=k·R(X). This formula transforms the specific pressure distribution into the wear distribution through the mapping of the dimensionless proportion X, providing a quantitative basis for subsequent calculation of equivalent wear and adjustment of the alignment state. At the same time, it ensures that the model meets the specifications' requirements for shaft alignment error and bearing life.

[0082] Step 1052: Based on the distribution relationship and the axial distance ratio of the equivalent pivot point of the stern shaft bearing, obtain the equivalent wear amount of the stern shaft bearing.

[0083] Specifically, step 1052 involves X, calculated in step 103, representing the axial distance ratio of the equivalent pivot point of the stern shaft bearing. d Substituting the wear distribution relationship Y(X)=k·R(X) derived in step 1051 (where k=M / R(0), M is the maximum allowable wear amount according to the specification, and R(0) is the stern end specific pressure value), the equivalent wear amount Y of the stern shaft rear bearing can be directly calculated. h That is, Y h =Y(X d )=k·R(X d ).

[0084] This process incorporates the equivalent position X d The weighted effect on load distribution within the bearing length makes Y hIt can represent the typical wear characteristics of the aft bearing under single-point support, providing key parameters for subsequent alignment and adjustment, ensuring that the shaft alignment error and bearing wear both meet the technical requirements of CB / Z338-2005 "Ship Shaft Alignment", and at the same time, by considering the correlation between equivalent wear and actual wear distribution, it balances calculation efficiency and engineering accuracy.

[0085] Based on the above embodiments, in this embodiment, the alignment of the shaft system is adjusted to meet the specifications based on the equivalent wear of the aft bearing and the wear of the front bearing of the stern shaft calculated according to the simultaneous equations of the wear of the front and rear bearings. Specifically, this includes steps 1061 to 1062:

[0086] Step 1061: Based on the simultaneous equations of the front and rear bearing wear of the stern shaft front bearing and the equivalent wear of the stern shaft rear bearing, obtain the wear of the stern shaft front bearing;

[0087] Step 1062: Based on the equivalent wear of the aft bearing and the wear of the fore bearing, adjust the alignment of the shaft system to meet the specifications.

[0088] The average specific pressure parameter further includes the average specific pressure of the forward stern shaft bearing and the overall average specific pressure of the aft stern shaft bearing. Before obtaining the wear amount of the forward stern shaft bearing based on the simultaneous equations relating the wear amounts of the forward and aft bearings and the equivalent wear amount of the aft stern shaft bearing, the method further includes:

[0089] The steps to obtain the simultaneous equations for the wear of the front and rear bearings of the stern shaft bearing based on the average specific pressure of the front bearing and the overall average specific pressure of the rear bearing.

[0090] Specifically, steps 1061 to 1062 adjust the shaft system state by combining the front and rear bearing wear formulas with the alignment parameters, including:

[0091] In a ship's propulsion shafting system, the water-lubricated stern shaft's fore and aft bearings are made of the same material, and their wear coefficients are also identical. Since their operating conditions are completely the same, based on the definition of bearing material wear coefficients, the wear amount of the fore and aft stern shaft bearings after operation, the average specific pressure Q of the fore stern shaft bearing, and the overall average specific pressure R of the aft bearing are all considered. h The diameter of the stern shaft aft bearing journal Dh, the diameter of the stern shaft forward bearing journal Dq, the rotational speed n, and the running time t are calculated using the following formula:

[0092]

[0093]

[0094] Combining the above two equations, we can obtain:

[0095]

[0096] The equivalent wear amount Y of the rear aft bearing of the stern shaft h =Y(X d )=k·R(X d Substitute this formula to calculate the wear amount Yq of the forward bearing of the stern shaft, thereby dynamically linking the wear amount of the forward bearing with the equivalent wear amount of the aft bearing, ensuring that the wear amounts of both simultaneously meet the allowable range of CB / Z338-2005 "Ship Shaft Alignment";

[0097] Finally, in the second propulsion shaft alignment model established in step 104, Yh and Yq are used as inputs for the elevation reduction of the stern shaft aft bearing and the fore bearing. Combined with the elevation data of the remaining bearings, the shaft alignment calculation is carried out again to obtain the load of each bearing, the rotation angle of the stern shaft aft bearing and the stress of the shaft section, and to check whether it meets the specifications. By iteratively adjusting the bearing displacement value, the global optimization of the alignment state is achieved, taking into account the consistency of material wear coefficient and the matching of operating conditions, so as to ensure the safety of the shaft system in long-term operation.

[0098] The specific implementation process is as follows:

[0099] A calculation model for the alignment of the first propulsion shafting with multi-point support for the aft bearing is established, and a dimensionless proportion is defined: The calculation model for the alignment of the first propulsion shafting is established according to the requirements of CB / Z 338-2005 "Ship Shaft Alignment". The aft bearing has 10 support points (n=10) within its bearing length L=960mm. The axial position of the i-th support point is calculated using the following formula (with the aft end of the aft bearing as the origin):

[0100]

[0101] Specifically, x1=0.05L, x2=0.15L, x3=0.25L, x4=0.35L, x5=0.45L, x6=0.55L, x7=0.65L, x8=0.75L, x9=0.85L, and x10=0.95L;

[0102] For ease of subsequent calculations, the dimensionless ratio of the distance from the i-th fulcrum to the stern end of the aft bearing relative to the bearing length is defined as:

[0103]

[0104] Therefore, X1=0.05, X2=0.15, X3=0.25, X4=0.35, X5=0.45, X6=0.55, X7=0.65, X8=0.75, X9=0.85, and X10=0.95.

[0105] The aft bearing of the stern shaft needs to be considered as an elastic support. The stiffness K of the aft bearing of the stern shaft is measured to be 5×108 N / m. Therefore, the stiffness of each support point of the aft bearing of the stern shaft is 5×107 N / m. The support points of the forward bearing of the stern shaft, the thrust bearing 8, the second intermediate bearing 5, and the first intermediate bearing 2 are all set as single support points in accordance with the requirements of CB / Z 338-2005 "Ship Shaft Alignment". The support point positions are all at 0.5 times the bearing shell length of the corresponding bearing. The remaining bearings are treated as rigid supports.

[0106] Then, shaft alignment calculations were performed: Based on the bearing load range and other parameters specified in the design requirements, a reasonable alignment state was determined. Analysis determined that the second intermediate bearing 5 should be raised by 0.8mm, while the elevations of the remaining bearings remained unchanged as the reasonable alignment state for the shaft system. The average specific pressure at each support point of the aft bearing was calculated as follows: R1=0.59MPa, R2=0.537MPa, R3=0.486MPa, R4=0.438MPa, R5=0.392MPa, R6=0.349MPa, R7=0.309MPa, R8=0.270MPa, R9=0.235MPa, R10=0.201MPa. The specific pressure of the forward bearing was Q=0.272MPa. The specific pressure of the aft bearing was calculated as follows:

[0107]

[0108] The calculated Rh = 0.381 MPa;

[0109] Then, calculate the equivalent support point position of the aft bearing: Based on the calculated specific pressure Ri and dimensionless axial distance ratio Xi of each support point of the aft bearing, calculate the axial distance ratio X of the equivalent support point of the aft bearing using the following formula. d :

[0110]

[0111] After calculation, X d =0.41, meaning the equivalent pivot point of the stern shaft bearing is located 0.41L (~402mm) from the stern.

[0112] Next, a calculation model for the alignment of the second propulsion shaft system with a single-point support for the aft bearing was established: In the multi-point elastic support alignment model of the aft bearing, the equivalent support point of the aft bearing was set at a single-point support 0.41L (~402mm) from the stern, forming a calculation model for the alignment of the shaft system with a single-point support for the aft bearing. The single-point support for the aft bearing was set as an elastic support with a stiffness of 5×10⁻⁶. 8 N / m.

[0113] Then, the wear distribution relationship of the stern shaft rear bearing was obtained: the distribution curve of the average specific pressure of each support point of the stern shaft rear bearing as a function of axial position (represented by the dimensionless axial distance percentage X) was plotted.

[0114] The average specific pressure distribution curve of each support point of the stern shaft bearing as a function of axial direction was fitted using a fifth-power polynomial, and determined through numerical simulation:

[0115] ;

[0116] Since the wear of a bearing is directly proportional to the specific pressure, the axial distribution of the wear of the bearing aft of the stern shaft is as follows: Based on repair standards or design requirements, the maximum wear amount M of the aft bearing is determined to be 5mm. Since the maximum wear amount is located at the aftmost end of the aft bearing, and the load distribution polynomial of the aft bearing along the axial direction is calculated to be 0.6167MPa, the K value is determined as follows:

[0117] The calculated value is 8.11, thus yielding the axial distribution of wear on the stern shaft aft bearing as follows: ;

[0118] Then calculate the equivalent wear of the aft bearing: based on the calculated equivalent pivot point position X of the aft bearing. d =0.41, calculate the wear at the equivalent fulcrum position, i.e., the equivalent wear Y of the stern shaft aft bearing. h =Y(X) d =3.328mm;

[0119] Calculating the wear of the stern shaft forward bearing: In a ship's propulsion shafting system, the water-lubricated stern shaft forward and aft bearings are made of the same material, and their wear coefficients are also the same. Since their operating conditions are completely identical, the wear of the stern shaft forward and aft bearings after operation is calculated using the following formula, based on the definition of the bearing material wear coefficient:

[0120]

[0121]

[0122] In the above formula, Yh is the equivalent wear of the aft bearing, Yq is the wear of the fore bearing, Rh is the overall average specific pressure of the aft bearing, Q is the average specific pressure of the fore bearing, Dh and Dq are the journal diameters of the aft and fore bearings respectively (360mm and 376mm), the rotational speed n, and the running time t. Combining the above two formulas yields:

[0123]

[0124] The wear amount of the stern shaft front bearing is calculated to be Yq = 2.659 mm using the above formula;

[0125] Finally, the shaft alignment calculation taking bearing wear into account is performed: In the shaft alignment model with a single-point support bearing aft of the stern shaft, the calculated values ​​Yq=2.659mm and Yh=3.328mm are used as the reduction in the elevation of the front and rear bearings of the stern shaft, i.e., the elevation of the front bearing is -2.659mm and the elevation of the rear bearing is -3.328mm. The remaining bearings are aligned according to the calculated elevation positions of the shaft alignment, i.e., the elevation of the #2 intermediate bearing is +0.8mm, and the elevations of the thrust bearing 8 and the first intermediate bearing 2 are both 0mm. These are used as inputs to perform shaft alignment calculations, obtaining the load of each bearing, the rotation angle of the rear bearing of the stern shaft, and the stress of the shaft segment, as shown in Tables 1 to 3.

[0126] Table 1 Comparison of bearing load and specific pressure before and after bearing wear

[0127]

[0128] Table 2 Comparison of bending stress in each shaft segment before and after bearing wear

[0129]

[0130] Table 3 Comparison of stern shaft rear bearing rotation angle before and after considering bearing wear

[0131]

[0132] According to the relevant requirements of CB / Z338-2005 "Ship Shaft Alignment" and the allowable load requirements of each bearing, the wear of the forward stern shaft bearing, thrust bearing 8, second intermediate bearing 5, first intermediate bearing 2, and the bending stress of the thrust shaft and second intermediate shaft 4 changed significantly. The stern shaft bearing was in better condition after the angular wear. Overall, the shaft alignment condition after wear met the relevant requirements.

[0133] It should be noted that: the ship propulsion shafting of this application generally includes two water-lubricated stern bearings for wear calculation, but this can be extended to three stern bearings. The calculation method is similar, all of which calculate the equivalent wear at the bearing support position based on the maximum wear of the stern bearing. Then, based on the different specific pressures of the stern bearings, the wear of other bearings is extrapolated to obtain the elevation status of each stern bearing. The shaft alignment is then evaluated based on this status. At the same time, if the shaft alignment check does not meet the standard specifications or bearing design requirements after bearing wear, the shaft alignment status should be adjusted appropriately, the bearing positions should be adjusted, the load should be reasonably distributed, or other types of bearings can be replaced to solve the problem.

[0134] This application proposes a method for calculating the wear state of the stern water-lubricated bearings in a ship's propulsion shafting under propeller cantilever loads. It also provides a reasonable alignment analysis method for the shafting that takes into account the wear of the stern water-lubricated bearings. This method can effectively ensure that the alignment state of the ship's propulsion shafting meets the design requirements throughout the entire service life of the bearings, thus ensuring the safety of the system operation.

[0135] Secondly, embodiments of this application provide a ship propulsion shaft alignment system, comprising: a first module, a second module, a third module, a fourth module, a fifth module, and a sixth module. The first module is used to establish a first propulsion shaft alignment calculation model with multi-point support for the aft bearing and to define a dimensionless proportion. The second module is used to obtain an average specific pressure parameter based on the first propulsion shaft alignment calculation model, the average specific pressure parameter including the average specific pressure of each support point of the aft bearing. The third module is used to obtain the axial distance proportion of the equivalent support points of the aft bearing based on the average specific pressure of each support point and the dimensionless proportion. The fourth module is used to obtain the second propulsion shaft alignment calculation model with single-point support of the stern shaft bearing based on the first propulsion shaft alignment calculation model and the axial distance ratio of the equivalent support point of the stern shaft bearing. The fifth module is used to fit the axial distribution relationship of the stern shaft bearing wear based on the average specific pressure of each support point, the dimensionless ratio, and the second propulsion shaft alignment calculation model, and to calculate the equivalent wear of the stern shaft bearing. The sixth module is used to adjust the alignment state of the shaft system to meet the specification requirements based on the wear of the stern shaft bearing calculated by the simultaneous equations of the equivalent wear of the stern shaft bearing and the wear of the front and rear bearings of the stern shaft bearing.

[0136] In this application, by establishing a calculation model for the alignment of the first propulsion shafting with multi-point support of the aft bearing and the axial distance ratio of the equivalent support points of the aft bearing, the accuracy of wear prediction is improved. Furthermore, by establishing a simultaneous equation for the wear of the front and rear bearings of the stern bearing, the wear of the front and rear bearings is ensured to meet the specifications simultaneously. This achieves dynamic inclusion of wear effects and can effectively guarantee that the alignment of the ship's propulsion shafting meets the design requirements throughout the entire service life of the bearings, thus ensuring the safety of system operation.

[0137] In the description of this application, it should be noted that the terms "upper," "lower," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two elements. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0138] It should be noted that in this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0139] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for aligning a ship's propulsion shafting, characterized in that, It includes: A calculation model for centering the first propulsion shaft system with multi-point support of the rear bearing is established, and a dimensionless proportion is defined. Based on the first propulsion shaft alignment calculation model, the average specific pressure parameter is obtained, which includes the average specific pressure of each support point of the stern shaft aft bearing; Based on the average specific pressure and dimensionless proportion of each support point, the axial distance proportion of the equivalent support point of the stern shaft rear bearing is obtained; Based on the first propulsion shaft alignment calculation model and the axial distance ratio of the equivalent support point of the stern shaft bearing, the second propulsion shaft alignment calculation model with single-point support of the stern shaft bearing is obtained; Based on the average specific pressure at each support point, the dimensionless proportion, and the second propulsion shaft alignment calculation model, the distribution relationship of the wear amount of the stern shaft rear bearing along the axial direction is fitted, and the equivalent wear amount of the stern shaft rear bearing is calculated. Based on the equivalent wear of the aft bearing and the wear of the fore stern bearing calculated from the simultaneous equations of the wear of the fore and aft bearings, the alignment of the shaft system is adjusted to meet the specifications. Define dimensionless proportions, specifically including: Determine the measured length of the bearing bush and the number of support points; Based on the measured value of the bearing length and the number of support points, the actual distance of each support point from the stern end of the stern shaft bearing is obtained; The actual distance of each support point from the stern end of the rear bearing is dimensionless and converted into a proportion of the bearing length to define a dimensionless proportion. Based on the first propulsion shaft alignment calculation model and the axial distance ratio of the equivalent support point of the stern shaft aft bearing, the second propulsion shaft alignment calculation model with single-point support of the stern shaft aft bearing is obtained, specifically including: The position of the single-point support is determined based on the axial distance ratio of the equivalent support point of the stern shaft bearing, and the multi-point support of the stern shaft bearing in the first propulsion shaft alignment calculation model is replaced with a single-point support to obtain the second propulsion shaft alignment calculation model with a single-point support of the stern shaft bearing. Based on the average specific pressure at each support point, the dimensionless proportion, and the second propulsion shaft alignment calculation model, the axial distribution relationship of the stern shaft aft bearing wear is fitted, and the equivalent wear of the stern shaft aft bearing is calculated, specifically including: Based on the average specific pressure at each support point, the dimensionless proportion, and the second propulsion shaft alignment calculation model, the distribution relationship of the wear amount of the stern shaft rear bearing along the axial direction is obtained; Based on the distribution relationship and the proportion of the axial distance of the equivalent fulcrum of the stern shaft aft bearing, the equivalent wear amount of the stern shaft aft bearing is obtained.

2. The ship propulsion shaft alignment method as described in claim 1, characterized in that, Based on the average specific pressure at each support point, the dimensionless proportion, and the second propulsion shaft alignment calculation model, the axial distribution relationship of the stern shaft aft bearing wear is obtained, specifically including: A fifth-order polynomial fitting of the specific pressure distribution was performed in the calculation model for the alignment of the second propulsion shaft system to obtain the fitting results; Based on the average specific pressure, dimensionless proportion, and fitting results of each support point, the distribution relationship of the wear amount of the stern shaft rear bearing along the axial direction is obtained.

3. The ship propulsion shaft alignment method as described in claim 2, characterized in that, Based on the average specific pressure, dimensionless proportion, and fitting results at each support point, the axial distribution relationship of the stern shaft aft bearing wear is obtained, specifically including: Based on the average specific pressure, dimensionless proportion, and fitting results of each support point, the initial distribution relationship is obtained. Based on the preset maximum wear amount, the proportional coefficient in the initial distribution formula is determined to obtain the axial distribution formula of the wear amount of the stern shaft rear bearing.

4. The ship propulsion shaft alignment method as described in claim 1, characterized in that: Based on the equivalent wear of the aft bearing and the wear of the fore stern bearing calculated using the simultaneous equations relating the wear of the fore and aft bearings, the alignment of the shaft system is adjusted to meet the specifications. Specifically, this includes: The wear amount of the front stern shaft bearing is obtained based on the simultaneous equations relating the wear amounts of the front and rear bearings to the front stern shaft bearing and the equivalent wear amount of the rear stern shaft bearing. Based on the equivalent wear of the aft bearing and the wear of the fore bearing, the alignment of the shaft system is adjusted to meet the specifications.

5. The ship propulsion shaft alignment method as described in claim 4, characterized in that: The average specific pressure parameter also includes the average specific pressure of the forward bearing of the stern shaft and the overall average specific pressure of the aft bearing of the stern shaft.

6. The ship propulsion shaft alignment method as described in claim 5, characterized in that, Before obtaining the wear amount of the front stern shaft bearing based on the simultaneous equations relating the wear amounts of the front and rear bearings and the equivalent wear amount of the rear stern shaft bearing, the method further includes: The steps to obtain the simultaneous equations for the wear of the front and rear bearings of the stern shaft bearing based on the average specific pressure of the front bearing and the overall average specific pressure of the rear bearing.

7. A ship propulsion shaft alignment system, characterized in that, It includes: The first module is used to establish a calculation model for centering the first propulsion shaft system with multi-point support of the stern shaft bearing and to define the dimensionless proportion. The second module is used to obtain the average specific pressure parameter based on the first propulsion shaft alignment calculation model. The average specific pressure parameter includes the average specific pressure of each support point of the stern shaft aft bearing. The third module is used to obtain the axial distance ratio of the equivalent support point of the stern shaft bearing based on the average specific pressure and dimensionless ratio of each support point. The fourth module is used to obtain the second propulsion shaft alignment calculation model with single-point support of the stern shaft bearing based on the first propulsion shaft alignment calculation model and the axial distance ratio of the equivalent support point of the stern shaft bearing. The fifth module is used to fit the axial distribution relationship of the stern shaft aft bearing wear based on the average specific pressure of each support point, the dimensionless proportion, and the second propulsion shaft alignment calculation model, and to calculate the equivalent wear of the stern shaft aft bearing. Module 6: It is used to calculate the wear of the front stern bearing based on the equivalent wear of the aft bearing and the simultaneous equations of the front stern bearing with respect to the wear of the front and rear bearings, and to adjust the alignment of the shaft system to meet the specifications. The first module is also used to: determine the measured value of the bearing length and the number of support points; based on the measured value of the bearing length and the number of support points, obtain the actual distance of each support point from the stern end of the stern bearing of the stern shaft; and convert the dimensionless actual distance of each support point from the stern end of the stern bearing of the stern shaft into a proportion of the bearing length, so as to define the dimensionless proportion. The fourth module is also used to: determine the position of a single-point support based on the axial distance ratio of the equivalent pivot point of the stern shaft bearing, and replace the multi-point support of the stern shaft bearing in the first propulsion shaft alignment calculation model with a single-point support, so as to obtain the second propulsion shaft alignment calculation model with a single-point support of the stern shaft bearing; The fifth module is also used to: obtain the axial distribution relationship of the wear amount of the stern shaft rear bearing based on the average specific pressure of each support point, the dimensionless proportion, and the second propulsion shaft alignment calculation model; and obtain the equivalent wear amount of the stern shaft rear bearing based on the distribution relationship and the axial distance proportion of the equivalent support point of the stern shaft rear bearing.

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