Method and system for centering ship propulsion shafting

Abstract

The invention relates to a ship propulsion shafting alignment method and system, and the method comprises the steps: building a first propulsion shafting alignment calculation model of multi-point support of a tail shaft rear bearing, and defining a dimensionless proportion; based on the first propulsion shafting alignment calculation model, an average specific pressure parameter is obtained; based on the average specific pressure and the dimensionless proportion of all the supporting points, the axial distance proportion of the equivalent supporting points of the tail shaft rear bearing is obtained; on the basis of the first propulsion shafting centering calculation model and the ratio of the axial distance of the equivalent supporting point of the tail shaft rear bearing, a second propulsion shafting centering calculation model of tail shaft rear bearing single-point supporting is obtained; on the basis of the average specific pressure of each supporting point, the dimensionless proportion and a second propulsion shafting alignment calculation model, fitting a distribution relational expression of the tail shaft rear bearing abrasion loss in the axial direction, and calculating the tail shaft rear bearing equivalent abrasion loss; based on the equivalent abrasion loss of the tail shaft rear bearing and the abrasion loss of the tail shaft front bearing calculated according to a simultaneous equation of the tail shaft front bearing about the abrasion loss of the front bearing and the rear bearing, the centering state of the shaft system is adjusted to meet the standard requirement.

Description

Technical Field

[0001] The present application relates to the field of ship propulsion shafting, and in particular to a ship propulsion shafting alignment method and system. Background Art

[0002] Traditional shafting calibration does not take into account the wear state changes of the stern water-lubricated bearings. Therefore, the following problems exist in practical applications: First, according to the requirements of ship propulsion shaft repair regulations, the maximum allowable wear of water-lubricated bearings can reach 2.7mm~8.1mm depending on the shaft diameter and material. Bearing wear will have a greater impact on its elevation, and thus have a greater impact on the load of each bearing; Secondly, the wear state of the rear stern shaft bearing at the stern of the ship's propulsion shaft system is in a nonlinear state under the action of the propeller cantilever load, and the two bearings of the stern water-lubricated setting, namely the front stern shaft and the rear stern shaft bearing, have different loads and shaft diameters, and the wear amounts of the two are also not nearly the same. It is impossible to directly include the maximum wear amount required by the standard into the elevation change of the water-lubricated stern bearing to analyze the alignment state of the shaft system.

[0003] Therefore, reasonable alignment carried out according to traditional methods can ensure that the system remains in good condition during the initial installation and operation stages. However, as the operating time increases, the alignment state of the shafting will change significantly after nonlinear wear of the bearings, resulting in poor bearing condition during actual operation and a risk to the safe operation of the system. Summary of the Invention

[0004] The present application provides a method and system for aligning a ship propulsion shaft system, which can solve the problem in related technologies that reasonable alignment performed according to traditional methods will lead to poor bearing status during actual operation as the operating time increases, posing a risk to the safe operation of the system.

[0005] In a first aspect, an embodiment of the present application provides a method for aligning a ship propulsion shafting system, comprising: Establish a calculation model for the alignment of the first propulsion shaft system with multiple support points on the rear bearing of the stern shaft, and define the dimensionless proportion; Based on the first propulsion shafting alignment calculation model, an average specific pressure parameter is obtained, wherein the average specific pressure parameter includes the average specific pressure of each support point of the stern shaft rear 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 rear bearing, the second propulsion shaft alignment calculation model with single-point support of the stern shaft rear bearing is obtained; 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 rear bearing wear is fitted, and the equivalent wear of the stern shaft rear bearing is calculated. Based on the equivalent wear of the stern shaft rear bearing and the wear of the stern shaft front bearing calculated according to the simultaneous equations of the wear of the front and rear bearings, the alignment status of the shafting is adjusted to meet the requirements of the specification.

[0006] In conjunction with the first aspect, in one embodiment, defining a dimensionless proportion specifically includes: Determine the measured value of bearing shell length and the number of support points; Based on the measured value of the bearing shell length and the number of support points, the actual distance between each support point and the stern end of the rear bearing of the stern shaft is obtained; The actual distance between each support point and the stern end of the rear bearing of the stern shaft is converted into a ratio of the bearing shell length to define the dimensionless ratio.

[0007] In conjunction with the first aspect, in one embodiment, based on the first propulsion shafting alignment calculation model and the axial distance ratio of the equivalent support point of the stern shaft rear bearing, a second propulsion shafting alignment calculation model with single-point support of the stern shaft rear 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 rear bearing, and the multi-point support of the stern shaft rear bearing in the first propulsion shaft system alignment calculation model is replaced with a single-point support to obtain the second propulsion shaft system alignment calculation model with a single-point support of the stern shaft rear bearing.

[0008] In combination with the first aspect, in one embodiment, based on the average specific pressure of each support point, the dimensionless proportion, and the second propulsion shaft alignment calculation model, a distribution relationship of the stern shaft rear bearing wear along the axial direction is fitted, and the equivalent wear of the stern shaft rear bearing is calculated, specifically including: 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 rear bearing wear is obtained. Based on the distribution relationship and the axial distance ratio of the equivalent support point of the stern shaft rear bearing, the equivalent wear amount of the stern shaft rear bearing is obtained.

[0009] In combination with the first aspect, in one embodiment, based on the average specific pressure of each support point, the dimensionless proportion, and the second propulsion shaft alignment calculation model, a distribution relationship of the stern shaft rear bearing wear along the axial direction is obtained, specifically including: A fifth-order polynomial fitting of the specific pressure distribution was performed in the second propulsion shaft alignment calculation model 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 stern shaft rear bearing wear along the axial direction is obtained.

[0010] In combination with the first aspect, in one embodiment, based on the average specific pressure of each support point, the dimensionless proportion and the fitting result, a distribution relationship of the wear amount of the rear bearing of the stern shaft along the axial direction 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 relationship is determined to obtain the distribution relationship of the wear amount of the rear bearing of the stern shaft along the axial direction.

[0011] In conjunction with the first aspect, in one embodiment, based on the equivalent wear of the rear stern shaft bearing and the wear of the front stern shaft bearing calculated according to the simultaneous equations of the wear of the front stern shaft bearing and the wear of the front and rear bearings, the alignment state of the shaft system is adjusted to meet the specification requirements, specifically including: Based on the simultaneous equations of the wear of the front and rear bearings of the stern shaft and the equivalent wear of the rear bearing of the stern shaft, the wear of the front bearing of the stern shaft is obtained; Based on the equivalent wear of the stern shaft rear bearing and the wear of the stern shaft front bearing, the alignment status of the shafting is adjusted to meet the specification requirements.

[0012] In combination with the first aspect, in one embodiment, the average specific pressure parameter further includes an average specific pressure of the stern shaft front bearing and an overall average specific pressure of the stern shaft rear bearing.

[0013] In combination with the first aspect, in one embodiment, before obtaining the wear amount of the stern shaft front bearing based on the simultaneous equations of the wear amount of the front and rear bearings of the stern shaft and the equivalent wear amount of the stern shaft rear bearing, the method further includes: The invention relates to a step of obtaining simultaneous equations of the wear of the front stern shaft bearing and the front and rear bearings based on the average specific pressure of the front stern shaft bearing and the overall average specific pressure of the rear stern shaft bearing.

[0014] In the second aspect, an embodiment of the present application provides a ship propulsion shaft alignment system, which includes: a first module, a second module, a third module, a fourth module, a fifth module and a sixth module, the first module: it is used to establish a first propulsion shaft alignment calculation model for multi-point support of the stern shaft rear bearing, and define a dimensionless proportion; the second module: it is used to obtain an average pressure ratio parameter based on the first propulsion shaft alignment calculation model, and the average pressure ratio parameter includes the average pressure ratio of each support point of the stern shaft rear bearing; the third module: it is used to obtain the axial distance ratio of the equivalent support point of the stern shaft rear bearing based on the average pressure ratio and dimensionless proportion of each support point; the The fourth module is used to obtain the second propulsion shaft system alignment calculation model of the stern shaft rear bearing single-point support based on the first propulsion shaft system alignment calculation model and the axial distance ratio of the equivalent support point of the stern shaft rear bearing; the fifth module is used to fit the distribution relationship of the stern shaft rear bearing wear along the axial direction based on the average specific pressure of each support point, the dimensionless ratio and the second propulsion shaft system alignment calculation model, and calculate the equivalent wear of the stern shaft rear bearing; the sixth module is used to adjust the alignment state of the shaft system to meet the requirements of the specification based on the wear of the stern shaft rear bearing and the simultaneous equations of the wear of the front and rear bearings of the stern shaft front bearing.

[0015] The beneficial effects of the technical solutions provided in the embodiments of the present application include: An embodiment of the present application provides a method and system for aligning a ship propulsion shaft system. By establishing a first propulsion shaft system alignment calculation model with multi-point support of the stern shaft rear bearing and the axial distance ratio of the equivalent support point of the stern shaft rear bearing, the accuracy of wear prediction is improved, and a set of simultaneous equations for the wear of the front stern shaft bearing and the front and rear bearings are established to ensure that the wear of the front and rear bearings meet the specifications synchronously, realize the dynamic inclusion of the wear effect, and effectively ensure that the alignment state of the ship propulsion shaft system meets the design requirements throughout the life of the bearing operation, thereby ensuring the safety of the system operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0017] Figure 1 A flow chart of a method for aligning a ship's propulsion shafting system provided in an embodiment of the present application; Figure 2 An overall schematic diagram of a short-span shafting system provided in an embodiment of the present application; Figure 3 This is a distribution curve of the average specific pressure at each point of the stern shaft rear bearing supported by the embodiment of the present application as a function of the axial position.

[0018] In the figure: 1. first elastic coupling; 2. first intermediate bearing; 3. first intermediate shaft; 4. second intermediate shaft; 5. second intermediate bearing; 6. second elastic 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 DESCRIPTION

[0019] In order to enable those skilled in the art to better understand the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0020] The embodiment of the present application provides a method and system for aligning a ship propulsion shaft system, which can solve the problem in related technologies that reasonable alignment performed according to traditional methods will lead to poor bearing status during actual operation as the operating time increases, posing a risk to the safe operation of the system.

[0021] In a first aspect, an embodiment of the present application provides a method for aligning a ship propulsion shafting system, comprising: 101: Establish a calculation model for the alignment of the first propulsion shaft system with multiple support points on the rear bearing of the stern shaft, and define the dimensionless proportion; 102: Obtaining an average specific pressure parameter based on the first propulsion shaft alignment calculation model, the average specific pressure parameter including an average specific pressure of each support point of the rear bearing of the stern shaft; 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; 104: Based on the first propulsion shaft alignment calculation model and the axial distance ratio of the equivalent support point of the stern shaft rear bearing, obtain the second propulsion shaft alignment calculation model with the stern shaft rear bearing single-point support; 105: Based on the average specific pressure of each support point, the dimensionless proportion and the second propulsion shaft alignment calculation model, the distribution relationship of the stern shaft rear bearing wear along the axial direction is fitted, and the equivalent wear of the stern shaft rear bearing is calculated; 106: Based on the equivalent wear of the rear stern shaft bearing and the wear of the front stern shaft bearing calculated from the simultaneous equations of the wear of the front stern shaft bearing and the wear of the front and rear bearings, adjust the alignment of the shafting to meet the requirements of the specification.

[0022] In this application, by establishing the first propulsion shaft system alignment calculation model with multi-point support of the stern shaft rear bearing and the axial distance ratio of the equivalent support point of the stern shaft rear bearing, the accuracy of wear prediction is improved, and the simultaneous equations of the stern shaft front bearing on the wear of the front and rear bearings are established to ensure that the wear of the front and rear bearings meet the specifications synchronously, and realize the dynamic inclusion of the wear effect. It can effectively ensure that the alignment state of the ship's propulsion shaft system meets the design requirements throughout the life of the bearing operation, thereby ensuring the safety of the system operation.

[0023] See also Figure 2 As shown, the short-span shafting of this embodiment includes a first elastic coupling 1, a first intermediate bearing 2, a first intermediate shaft 3, a second intermediate shaft 4, a second intermediate bearing 5, a second elastic 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.

[0024] In step 101, a first propulsion shafting alignment calculation model for multi-point support of the stern shaft rear bearing is established. The shafting alignment calculation model is established in accordance with the requirements of CB / Z338-2005 "Ship Shafting Alignment," and the actual measured value L of the stern shaft rear bearing bushing is obtained through actual measurement or design drawings.

[0025] When defining the dimensionless proportion, specifically steps 1011 to 1013 are included: Step 1011: Determine the measured value of the bearing bush length and the number of fulcrums; Step 1012: Based on the measured value of the bearing shell length and the number of support points, obtain the actual distance between each support point and the stern end of the rear bearing of the stern shaft; Step 1013: Convert the actual distance between each support point and the stern end of the rear bearing of the stern shaft into a dimensionless ratio of the bearing shell length to define a dimensionless ratio.

[0026] Specifically, determine the measured value of the bearing shell length L and the number of fulcrums n. Establish n fulcrums within the bearing shell length L of the stern shaft rear bearing. The number n is determined based on the bearing length and calculation accuracy requirements. Generally, n ≥ 8 to ensure calculation accuracy.

[0027] Therefore, the actual distance between the ith fulcrum and the stern end of the rear bearing of the stern shaft is:

[0028] For the convenience of subsequent calculations, the dimensionless ratio of the distance from the i-th support point to the stern end of the rear bearing of the stern shaft to the bearing length is defined as:

[0029] In this embodiment, the support modeling of the rear stern shaft bearing needs to be based on the elastic support characteristics. Assuming that its total stiffness is K, n support points (n≥8) are evenly distributed within the bearing shell length L, and the stiffness of each support point is evenly divided, K / n, to more accurately reflect the non-uniform load distribution within the bearing shell length; while the front stern shaft bearing, thrust bearing 8, second intermediate bearing 5 and first intermediate bearing 2 are set as single support points in accordance with the CB / Z338-2005 standard, and the support point position is 0.5 times the length of the corresponding bearing shell (geometric center). The remaining bearings (such as other intermediate bearings) can flexibly choose elastic support (taking into account the actual stiffness characteristics) or rigid support (simplified model) according to the calculation accuracy requirements, so as to balance the alignment accuracy and calculation efficiency while meeting the requirements of the specification, and ensure the reliability and safety of the shaft system in long-term operation.

[0030] Based on the above embodiment, in this embodiment, in step 102, the first propulsion shafting alignment calculation model performs shafting alignment analysis and calculates the average specific pressure Ri (i=1-10) of each support point of the stern shaft rear bearing and the average specific pressure Q of the stern shaft front bearing, and uses the Ri value according to the formula:

[0031] Calculate the overall average specific pressure R of the rear bearing of the stern shaft h The number of fulcrums n ≥ 8 ensures the discretization accuracy of the load distribution within the bearing length, and the combination of elastic support modeling (stiffness is K) and dimensionless axial distance ratio enables the pressure ratio parameters to accurately reflect the mechanical properties of the shafting in the aligned state, providing key data support for subsequent wear analysis and alignment error correction.

[0032] Based on the above embodiment, in this embodiment, in step 103, the average specific pressure Ri of each support point of the rear stern shaft bearing is combined with the corresponding dimensionless axial distance ratio Xi, and the weighted average formula is used to calculate the axial distance ratio Xd of the equivalent support point of the rear stern shaft bearing. The formula is:

[0033] Where Ri is the pressure ratio data of each support point obtained in step 102, and Xi is the dimensionless ratio defined in step 101. The force concentration area is located by the pressure ratio weight, providing key parameter support for the subsequent single-point support model establishment and wear distribution analysis.

[0034] On the basis of the above embodiment, in this embodiment, based on the first propulsion shaft system alignment calculation model and the axial distance ratio of the equivalent support point of the stern shaft rear bearing, a second propulsion shaft system alignment calculation model with single-point support of the stern shaft rear bearing is obtained, which specifically includes: The position of the single-point support is determined based on the axial distance ratio of the equivalent support point of the stern shaft rear bearing, and the multi-point support of the stern shaft rear bearing in the first propulsion shaft system alignment calculation model is replaced with a single-point support to obtain the second propulsion shaft system alignment calculation model with a single-point support of the stern shaft rear bearing.

[0035] Specifically, in this step, the multi-point support structure of the stern shaft rear bearing is replaced with a single-point support by using the first propulsion shaft system centering calculation model of the stern shaft rear bearing multi-point support established in step 101 and the axial distance ratio Xd of the equivalent support point of the stern shaft rear bearing calculated in step 103, so as to obtain the second propulsion shaft system centering calculation model of the stern shaft rear bearing single-point support.

[0036] Specifically, the method uses the axial distance ratio Xd of the equivalent support point of the rear bearing of the stern shaft as the position reference of the single-point support, substitutes it into the first propulsion shaft system alignment calculation model, simplifies the n ≥ 8 elastic support points (stiffness is K / n) within the original bearing length into a single support point (stiffness is K or rigid support), and thus forms the second propulsion shaft system alignment calculation model. This model not only meets the requirements of the CB / Z338-2005 "Ship Shaft System Alignment" specification, but also ensures the rationality of the alignment state through mechanical equivalence and significantly reduces the calculation complexity. It is suitable for shaft system design and maintenance scenarios under different precision requirements.

[0037] On the basis of the above embodiment, this embodiment fits the distribution relationship of the wear amount of the rear stern shaft bearing along the axial direction based on the average specific pressure of each support point, the dimensionless proportion and the second propulsion shaft alignment calculation model, and calculates the equivalent wear amount of the rear stern shaft bearing, which specifically includes steps 1051 to 1052: 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 stern shaft rear bearing wear along the axial direction.

[0038] Firstly, a fifth-order polynomial fitting of the specific pressure distribution is performed in the second propulsion shaft system alignment calculation model to obtain the fitting results. Then, based on the average specific pressure of each support point, the dimensionless proportion and the fitting results, the distribution relationship of the stern shaft rear bearing wear along the axial direction is obtained.

[0039] Among them, based on the average specific pressure, dimensionless proportion and fitting results of each support point, the distribution relationship formula of the wear amount of the rear bearing of the stern shaft along the axial direction is obtained, specifically including: based on the average specific pressure, dimensionless proportion and fitting results of each support point, an initial distribution relationship formula is obtained; based on the preset maximum wear amount, the proportional coefficient in the initial distribution relationship formula is determined to obtain the distribution relationship formula of the wear amount of the rear bearing of the stern shaft along the axial direction.

[0040] Specifically, in the second propulsion shaft alignment calculation model, based on the average specific pressure of each support point of the stern shaft rear bearing obtained in step 102 (R1, R2, ..., R 10 ) and the dimensionless axial distance ratio defined in step 101 (X1, X2, ..., X 10 ) to fit the specific pressure distribution with a fifth-order polynomial and construct a continuous distribution function R(X) of the specific pressure along the axial position. Then, combined with the logic that the bearing wear is proportional to the specific pressure, the distribution relationship of the stern shaft rear bearing wear along the axial position is: ; The fitted R(X) is associated with the preset maximum wear M allowed by the specification. Since the maximum wear is located at the stern end of the rear bearing of the stern shaft, and is calculated based on the axial distribution polynomial of the rear bearing load of the stern shaft, the K value can be obtained by: The calculation results show that the distribution relationship of wear along the axial position is finally derived: Y(X)=k·R(X). This formula converts the specific pressure distribution into the wear distribution through the mapping of the dimensionless proportion X, providing a quantitative basis for the subsequent calculation of equivalent wear and adjustment of the alignment status, while ensuring that the model meets the regulatory constraints on shaft alignment error and bearing life.

[0041] Step 1052: Obtain the equivalent wear amount of the stern shaft rear bearing based on the distribution relationship and the axial distance ratio of the equivalent support point of the stern shaft rear bearing.

[0042] Specifically, step 1052 is performed by dividing the equivalent fulcrum axial distance of the rear bearing of the stern shaft calculated in step 103 by X d Substitute the wear distribution relationship Y(X)=k·R(X) derived in step 1051 (where k=M / R(0), M is the maximum wear allowed by the specification, and R(0) is the tail end pressure value) to directly calculate the equivalent wear of the stern shaft rear bearing Y h , that is, Y h =Y(X d)=k·R(X d ).

[0043] This process combines the equivalent position X d The weighted effect of the load distribution within the bearing length makes Y h It can represent the typical wear characteristics of the stern shaft rear bearing under single-point support, provide key parameters for subsequent alignment adjustments, and ensure that the shafting alignment error and bearing wear meet the technical requirements of CB / Z338-2005 "Ship Shafting Alignment". At the same time, through the correlation between equivalent wear and actual wear distribution, it takes into account both calculation efficiency and engineering accuracy.

[0044] Based on the above embodiment, in this embodiment, based on the equivalent wear of the rear stern shaft bearing and the wear of the front stern shaft bearing calculated according to the simultaneous equations of the wear of the front stern shaft bearing and the wear of the front and rear bearings, the alignment state of the shaft system is adjusted to meet the specification requirements, specifically including steps 1061 to 1062: Step 1061: Obtain the wear amount of the stern shaft front bearing based on the simultaneous equations of the wear amounts of the front and rear bearings of the stern shaft and the equivalent wear amount of the stern shaft rear bearing; Step 1062: Based on the equivalent wear of the stern shaft rear bearing and the wear of the stern shaft front bearing, adjust the alignment state of the shaft system to meet the specification requirements.

[0045] The average specific pressure parameter also includes the average specific pressure of the front stern shaft bearing and the overall average specific pressure of the rear stern shaft bearing. Based on the simultaneous equations of the wear of the front stern shaft bearing with respect to the wear of the front and rear bearings and the equivalent wear of the rear stern shaft bearing, before obtaining the wear of the front stern shaft bearing, the method further includes: The invention relates to a step of obtaining simultaneous equations of the wear of the front stern shaft bearing and the front and rear bearings based on the average specific pressure of the front stern shaft bearing and the overall average specific pressure of the rear stern shaft bearing.

[0046] Specifically, steps 1061 to 1062 adjust the shafting state by combining the front and rear bearing wear formulas and the alignment parameters, and specifically include: The materials of the water-lubricated front and rear bearings of the ship's propulsion shaft system are the same, and their wear coefficients are also the same. Since the operating conditions of the two are exactly the same, according to the definition of the bearing material wear coefficient, the wear amount of the front and rear bearings of the stern shaft after operation and the average specific pressure Q of the front bearing of the stern shaft and the overall average specific pressure R of the rear bearing are calculated. h The diameter of the stern shaft rear bearing journal Dh, the diameter of the stern shaft front bearing journal Dq, the speed n, and the running time t are calculated as follows:

[0047]

[0048] Combining the above two equations, we can get:

[0049] The equivalent wear of the rear bearing of the stern shaft Y h =Y(X d )=k·R(X d ) is substituted into the formula to calculate the wear amount Yq of the front stern shaft bearing, thereby dynamically correlating the wear amount of the front bearing with the equivalent wear amount of the rear bearing, ensuring that the wear amounts of both simultaneously meet the allowable range of CB / Z338-2005 "Alignment of Ship Shafting"; Finally, in the second propulsion shaft alignment model established in step 104, Yh and Yq are input as the elevation reduction inputs of the rear and front bearings of the stern shaft. Combined with the elevation data of the remaining bearings, the shaft alignment calculation is re-performed to obtain the load of each bearing, the rotation angle of the rear bearing of the stern shaft, and the stress of the shaft section. The results are then checked to see if they meet the requirements of the specification. By iteratively adjusting the bearing displacement values, the global optimization of the alignment state is achieved, taking into account the consistency of the material wear coefficient and the matching of the operating conditions, thus ensuring the long-term operation safety of the shaft system.

[0050] The specific implementation process is as follows: Establish a calculation model for the alignment of the first propulsion shafting system with multiple points of support on the rear stern shaft bearing, and define the dimensionless proportion: According to the requirements of CB / Z 338-2005 "Alignment of Ship Shafting System", establish a calculation model for the alignment of the first propulsion shafting system, in which 10 support points (i.e., n=10) are established within the bearing shell length L=960mm of the rear stern shaft bearing. The axial position of the i-th support point is calculated according to the following formula (with the rear end of the rear stern shaft bearing as the origin):

[0051] 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, x10=0.95L; For the convenience of subsequent calculations, the dimensionless ratio of the distance from the i-th support point to the stern end of the rear bearing of the stern shaft to the bearing length is defined as:

[0052] 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.

[0053] The rear stern shaft bearing needs to be considered as an elastic support. The stiffness K of the rear stern shaft bearing is measured to be 5×108N / m, so the stiffness of each support point of the rear stern shaft bearing is 5×107N / m. The fulcrum positions of the front stern shaft bearing, thrust bearing 8, second intermediate bearing 5 and first intermediate bearing 2 are all set as single fulcrums in accordance with the requirements of CB / Z 338-2005 "Alignment of Ship Shafting". The fulcrum positions are all at 0.5 times the bearing shell length of the corresponding bearing. The remaining bearings are treated as rigid supports.

[0054] Then, the shafting system reasonable alignment calculation is carried out: the shafting system alignment calculation is carried out, and the reasonable alignment state is determined according to the parameters such as the bearing load range specified in the design requirements. After analysis, it is determined that the second intermediate bearing 5 is raised by 0.8mm, and the elevations of the other bearings remain unchanged as the reasonable alignment state of the shafting system. After calculation, the average specific pressure of each support point of the stern shaft rear bearing is: 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 stern shaft front bearing Q=0.272MPa, and the specific pressure of the stern shaft rear bearing is calculated as follows:

[0055] After calculation, Rh=0.381MPa; Then calculate the equivalent fulcrum position of the rear stern shaft bearing: According to the calculated specific pressure Ri and dimensionless axial distance ratio Xi of each fulcrum of the rear stern shaft bearing, calculate the axial distance ratio X of the equivalent fulcrum of the rear stern shaft bearing according to the following formula: d :

[0056] After calculation, X d =0.41, that is, the equivalent fulcrum of the rear bearing of the stern shaft is located at a distance of 0.41L (~402mm) from the stern; Then, a calculation model for the alignment of the second propulsion shaft system with a single-point support of the stern shaft rear bearing was established: the equivalent support point of the stern shaft rear bearing in the multi-point elastic support alignment model was set at a single-point support at a distance of 0.41L (~402mm) from the stern, forming a calculation model for the alignment of the shaft system with a single-point support of the stern shaft rear bearing. The single-point support of the stern shaft rear bearing was set as an elastic support with a stiffness of 5×10 8 N / m.

[0057] Then, the wear distribution relationship of the rear bearing of the stern shaft is obtained: the distribution curve of the average specific pressure of each point of the rear bearing of the stern shaft is plotted as a function of the axial position (expressed by the dimensionless axial distance ratio X).

[0058] The axial distribution curve of the average specific pressure at each point of the stern shaft rear bearing is fitted using a fifth-order polynomial and determined through numerical simulation: ; Since the wear of the bearing is proportional to the specific pressure, the distribution relationship of the wear of the rear bearing of the stern shaft along the axial position is: , refer to the repair standards or design requirements to determine the maximum wear of the stern shaft rear bearing M = 5mm. Since the maximum wear is located at the stern end of the stern shaft rear bearing, and the stern shaft rear bearing load is calculated as 0.6167MPa according to the axial distribution polynomial, the K value is calculated as: The calculated value is 8.11, and the axial distribution relationship of the rear bearing wear of the stern shaft is obtained as follows: ; Then calculate the equivalent wear of the rear stern shaft bearing: According to the calculated equivalent fulcrum position X of the rear stern shaft bearing d =0.41, calculate the wear amount of the equivalent fulcrum position, that is, the equivalent wear amount of the rear bearing of the stern shaft Y h =Y(X d ) = 3.328mm; Calculation of stern shaft front bearing wear: The water-lubricated stern shaft front and rear bearings in the ship propulsion shaft system are made of the same material and have the same wear coefficient. Since the two are used under exactly the same operating conditions, according to the definition of the bearing material wear coefficient, the wear of the stern shaft front and rear bearings after operation is calculated as follows:

[0059]

[0060] In the above formula, Yh is the equivalent wear of the rear stern shaft bearing, Yq is the wear of the front stern shaft, Rh is the overall average specific pressure of the rear stern shaft bearing, Q is the average specific pressure of the front stern shaft bearing, Dh and Dq are the journal diameters of the rear stern shaft bearing and the front stern shaft bearing, respectively, which are 360mm and 376mm, the speed is n, and the running time is t. Combining the above two formulas, we can get:

[0061] The wear amount of the stern shaft front bearing calculated by the above formula is Yq=2.659mm; Finally, the shaft alignment state calculation taking into account bearing wear is carried out: in the shaft alignment model with single-point support of the stern shaft rear bearing, Yq=2.659mm and Yh=3.328mm are calculated as the elevation reduction of the front and rear stern shaft bearings, that is, the elevation of the front stern shaft bearing is -2.659mm, and the elevation of the rear stern shaft bearing is -3.328mm. The elevation positions of the remaining bearings are calculated according to the reasonable alignment of the shaft system, that is, 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. The shaft alignment calculation is carried out as input to obtain the load of each bearing, the rotation angle of the rear stern shaft bearing, and the shaft segment stress, as shown in Tables 1 to 3: Table 1 Comparison of bearing load and specific pressure before and after bearing wear is taken into account

[0062] Table 2 Comparison of bending stress of each shaft segment before and after bearing wear is taken into account

[0063] Table 3 Comparison of stern shaft rear bearing rotation angle before and after bearing wear is taken into account

[0064] According to the relevant requirements of CB / Z338-2005 "Ship Shafting Alignment" and the allowable load requirements of each bearing, the load of the stern shaft front bearing, the load of the thrust bearing 8, the load of the second intermediate bearing 5 and the load of the first intermediate bearing 2, as well as the bending stress of the thrust shaft and the second intermediate shaft 4 changed significantly after wear. The stern shaft rear bearing angular condition is better after wear. Overall, the shafting alignment condition after wear meets the relevant requirements.

[0065] It should be noted that: the ship propulsion shaft system of this application generally takes into account the wear of two water-lubricated stern bearings, which can also be expanded to three stern bearings. The calculation method is similar. The equivalent wear of the bearing support position is calculated according to the maximum wear of the bearing at the stern end, and then the wear of other bearings is calculated according to the different pressure ratios of the stern bearing to obtain the elevation status of each stern bearing, and then the shaft system alignment is evaluated according to this status. At the same time, if the shaft system alignment check does not meet the standard specifications or bearing design requirements after the bearing is worn, the shaft system should be appropriately adjusted to a reasonable alignment state, the bearing position should be adjusted, and the load should be reasonably distributed. Other types of bearings can also be replaced to solve the problem.

[0066] This application proposes a method for calculating the wear state of the stern water-lubricated bearings of a ship propulsion shaft system under the action of propeller cantilever load, and provides a reasonable alignment analysis method for the shaft system taking into account the influence of the wear of the stern water-lubricated bearings. This can effectively ensure that the alignment state of the ship propulsion shaft system meets the design requirements throughout the life of the bearings and ensure the safety of the system operation.

[0067] In the second aspect, an embodiment of the present application provides a ship propulsion shaft alignment system, which includes: a first module, a second module, a third module, a fourth module, a fifth module and a sixth module, the first module: it is used to establish a first propulsion shaft alignment calculation model for multi-point support of the stern shaft rear bearing, and define a dimensionless proportion; the second module: it is used to obtain an average pressure ratio parameter based on the first propulsion shaft alignment calculation model, and the average pressure ratio parameter includes the average pressure ratio of each support point of the stern shaft rear bearing; the third module: it is used to obtain the axial distance ratio of the equivalent support point of the stern shaft rear bearing based on the average pressure ratio and dimensionless proportion of each support point; the The fourth module is used to obtain the second propulsion shaft system alignment calculation model of the stern shaft rear bearing single-point support based on the first propulsion shaft system alignment calculation model and the axial distance ratio of the equivalent support point of the stern shaft rear bearing; the fifth module is used to fit the distribution relationship of the stern shaft rear bearing wear along the axial direction based on the average specific pressure of each support point, the dimensionless ratio and the second propulsion shaft system alignment calculation model, and calculate the equivalent wear of the stern shaft rear bearing; the sixth module is used to adjust the alignment state of the shaft system to meet the requirements of the specification based on the wear of the stern shaft rear bearing and the simultaneous equations of the wear of the front and rear bearings of the stern shaft front bearing.

[0068] In this application, by establishing the first propulsion shaft system alignment calculation model with multi-point support of the stern shaft rear bearing and the axial distance ratio of the equivalent support point of the stern shaft rear bearing, the accuracy of wear prediction is improved, and the simultaneous equations of the stern shaft front bearing on the wear of the front and rear bearings are established to ensure that the wear of the front and rear bearings meet the specifications synchronously, and realize the dynamic inclusion of the wear effect. It can effectively ensure that the alignment state of the ship's propulsion shaft system meets the design requirements throughout the life of the bearing operation, thereby ensuring the safety of the system operation.

[0069] In the description of this application, it should be noted that the terms "upper" and "lower" and the like indicate orientations or positional relationships based on the orientations or positional relationships 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, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application. Unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be internal communication between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0070] It should be noted that, in this application, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprising a ..." does not exclude the presence of other identical elements in the process, method, article or device comprising the element.

[0071] The foregoing is merely a list of specific embodiments of the present application, intended to enable those skilled in the art to understand or implement the present 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 the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the broadest scope consistent with the principles and novel features of the present application.

Claims

1. A method for aligning a ship propulsion shaft system, characterized in that: It includes: Establish a calculation model for the alignment of the first propulsion shaft system with multiple support points on the rear bearing of the stern shaft, and define the dimensionless proportion; Based on the first propulsion shafting alignment calculation model, an average specific pressure parameter is obtained, wherein the average specific pressure parameter includes the average specific pressure of each support point of the stern shaft rear 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 rear bearing, the second propulsion shaft alignment calculation model with single-point support of the stern shaft rear bearing is obtained; 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 rear bearing wear is fitted, and the equivalent wear of the stern shaft rear bearing is calculated. Based on the equivalent wear of the stern shaft rear bearing and the wear of the stern shaft front bearing calculated according to the simultaneous equations of the wear of the front and rear bearings, the alignment status of the shafting is adjusted to meet the requirements of the specification.

2. The ship propulsion shafting alignment method according to claim 1, characterized in that: Define dimensionless proportions, including: Determine the measured value of bearing shell length and the number of support points; Based on the measured value of the bearing shell length and the number of support points, the actual distance between each support point and the stern end of the rear bearing of the stern shaft is obtained; The actual distance between each support point and the stern end of the rear bearing of the stern shaft is converted into a ratio of the bearing shell length to define the dimensionless ratio.

3. The ship propulsion shafting alignment method according to claim 1, wherein: Based on the first propulsion shaft alignment calculation model and the axial distance ratio of the equivalent support point of the stern shaft rear bearing, the second propulsion shaft alignment calculation model with single-point support of the stern shaft rear bearing is obtained, which specifically includes: The position of the single-point support is determined based on the axial distance ratio of the equivalent support point of the stern shaft rear bearing, and the multi-point support of the stern shaft rear bearing in the first propulsion shaft system alignment calculation model is replaced with a single-point support to obtain the second propulsion shaft system alignment calculation model with a single-point support of the stern shaft rear bearing.

4. The ship propulsion shafting alignment method according to claim 1, wherein: Based on the average specific pressure of each support point, the dimensionless proportion, and the second propulsion shaft alignment calculation model, the distribution relationship of the stern shaft rear bearing wear along the axial direction is fitted, and the equivalent wear of the stern shaft rear bearing is calculated, including: 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 rear bearing wear is obtained. Based on the distribution relationship and the axial distance ratio of the equivalent support point of the stern shaft rear bearing, the equivalent wear amount of the stern shaft rear bearing is obtained.

5. The ship propulsion shafting alignment method according to claim 4, characterized in that: Based on the average specific pressure of each support point, the dimensionless proportion, and the second propulsion shaft alignment calculation model, the distribution relationship of the stern shaft rear bearing wear along the axial direction is obtained, including: A fifth-order polynomial fitting of the specific pressure distribution was performed in the second propulsion shaft alignment calculation model 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 stern shaft rear bearing wear along the axial direction is obtained.

6. The ship propulsion shafting alignment method according to claim 5, characterized in that: Based on the average specific pressure, dimensionless proportion and fitting results of each support point, the distribution relationship of the stern shaft rear bearing wear along the axial direction is obtained, 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 relationship is determined to obtain the distribution relationship of the wear amount of the rear bearing of the stern shaft along the axial direction.

7. The ship propulsion shafting alignment method according to claim 1, characterized in that: Based on the equivalent wear of the rear stern shaft bearing and the wear of the front stern shaft bearing calculated from the simultaneous equations of the wear of the front and rear bearings, the alignment of the shafting is adjusted to meet the requirements of the specification, including: Based on the simultaneous equations of the wear of the front and rear bearings of the stern shaft and the equivalent wear of the rear bearing of the stern shaft, the wear of the front bearing of the stern shaft is obtained; Based on the equivalent wear of the stern shaft rear bearing and the wear of the stern shaft front bearing, the alignment status of the shafting is adjusted to meet the specification requirements.

8. The method for aligning a ship propulsion shafting system according to claim 7, wherein: The average specific pressure parameter also includes the average specific pressure of the stern shaft front bearing and the overall average specific pressure of the stern shaft rear bearing.

9. The ship propulsion shafting alignment method according to claim 8, characterized in that: Before obtaining the wear amount of the stern shaft front bearing based on the simultaneous equations of the wear amount of the front and rear bearings of the stern shaft and the equivalent wear amount of the stern shaft rear bearing, the method further includes: The invention relates to a step of obtaining simultaneous equations of the wear of the front stern shaft bearing and the front and rear bearings based on the average specific pressure of the front stern shaft bearing and the overall average specific pressure of the rear stern shaft bearing.

10. A ship propulsion shaft alignment system, characterized in that: It includes: The first module is used to establish the calculation model of the first propulsion shaft system alignment with the multi-point support of the rear bearing of the stern shaft and define the dimensionless proportion; The second module is used to obtain an average specific pressure parameter based on the first propulsion shaft alignment calculation model, wherein the average specific pressure parameter includes the average specific pressure of each support point of the stern shaft rear bearing; The third module is used to obtain the axial distance ratio of the equivalent support point of the rear bearing of the stern shaft 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 of the stern shaft rear bearing single-point support based on the first propulsion shaft alignment calculation model and the axial distance ratio of the equivalent support point of the stern shaft rear bearing; The fifth module is used to fit the axial distribution relationship of the stern shaft rear bearing wear based on the average specific pressure of each support point, the dimensionless proportion and the second propulsion shaft alignment calculation model, and calculate the equivalent wear of the stern shaft rear bearing; Module 6: It is used to adjust the alignment state of the shaft system to meet the requirements of the specification based on the wear of the stern shaft front bearing calculated based on the simultaneous equations of the equivalent wear of the stern shaft rear bearing and the wear of the front and rear bearings.

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