CN112711814A - Assembly tolerance distribution method for unmanned ship power propulsion device - Google Patents
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Abstract
The invention relates to an assembly tolerance distribution method for an unmanned boat power propulsion device, which comprises the following steps: 1, acquiring a three-dimensional assembly model and assembly precision requirements of an unmanned ship power propulsion device; 2, extracting the fit constraint relation and the initial tolerance information of the power propulsion device of the unmanned ship; 3, identifying key characteristics of the power propulsion device of the unmanned ship and determining an assembly deviation transfer relationship; 4, performing characteristic point dispersion on a key characteristic surface depending on key characteristics; 5 determining the tolerance distribution type of the key characteristic; 6, calculating the assembly deviation by adopting a Monte Carlo method according to the deviation transfer relationship; 7, redistributing the assembly tolerance according to sensitivity analysis; 8 obtaining an assembly tolerance distribution scheme according to the assembly precision. The invention analyzes and calculates the assembly tolerance of the unmanned ship power propulsion device based on the discrete characteristic points and introduces a statistical analysis method, thereby not only providing reference for the actual assembly of the unmanned ship power propulsion device, but also improving the assembly precision and the assembly efficiency of the unmanned ship power propulsion device.
Description
Technical Field
The invention relates to the manufacturing technology of unmanned boats, in particular to an assembling tolerance distribution method of an unmanned boat power propulsion device.
Background
The assembly of the power propulsion device of the unmanned ship has higher requirement on the coaxiality, and the poor assembly precision can influence the torque transmission during working and directly influence the power performance of the unmanned ship and the reliability of the power propulsion device. At present, the assembly process of the unmanned ship power propulsion device is complex, no effective method is available for controlling the assembly precision, the assembly process is slow, time and labor are wasted, and the method is a key problem for restricting the progress in the construction process of the unmanned ship.
Disclosure of Invention
The invention aims to overcome the defect of low assembly efficiency of the prior art and provides an assembly tolerance distribution method of an unmanned boat power propulsion device.
The invention provides an assembly tolerance distribution method for an unmanned boat power propulsion device, which aims to achieve the aim and comprises the following steps:
step 1, obtaining a three-dimensional assembly model of the power propulsion device of the unmanned ship and relevant design requirements. The components involved in assembly need to be numbered and identified, and the final assembly precision requirement is specific to the gap precision requirement between two or more characteristic surfaces.
And 2, extracting the fit constraint relation and the initial tolerance information of the unmanned ship power propulsion device assembly. The description of the fit constraint relationship is based on the part number in step 1. Because the deformation of the parts is not involved in the assembling process of the power propulsion device, the geometric position state of the parts is mainly considered in the assembling constraint relation. The assembly relationship can be divided into: the internal size and the form and position of the part are restricted, and the matching and restricting relationship between the parts and the tooling is restricted. The initial tolerance information is one of the input variables for the assembly deviation calculation.
The fit constraint relationship between the power propulsion unit parts extracted in step 1 is described as follows:
e(fx，fy)
e denotes the established constraint relationship, fx、fyRepresenting two feature planes participating in a fit constraint;
and 3, identifying key characteristics of the assembly of the power propulsion device of the unmanned ship, and determining the assembly deviation transfer relationship. The key characteristics involved are determined according to the assembly precision requirement in step 1 and the assembly constraint relation in step 2, and the Key Characteristics (KC) are the basis of the deviation transfer analysis. The assembly deviation is a process gradually accumulated according to an assembly constraint relation, and a deviation transfer process can be described by the following formula:
Δui＝ui(ui-1，KCi1，KCi2，…)
in the formula:
Δui-assembly deviation of the ith part;
ui-1-assembly deviation of the (i-1) th part;
KCi1，KCi2-KC deviations in the ith part that participate in the transfer of deviations;
ui-the part deviation transfer function is determined by a specific fit constraint relationship.
And 4, performing characteristic point dispersion on the key characteristic surface depending on the key characteristics according to the characteristic point dispersion rule.
The feature plane based discrete rule is as follows: according to the "321" positioning principle, the main positioning surface limits three degrees of freedom: a z-translation and a rotation in both directions around the x and y axes, the secondary positioning surface limits two degrees of freedom: an x-direction translation and a rotation around the z-axis, the third positioning surface limits the y-direction movement. The 6 degrees of freedom are limited, enabling full positioning of the part in space. Evaluating the quality of the positioning scheme through geometric stability, and determining the following positioning point discrete method: when the area of a triangle formed by 3 positioning points on the main positioning surface is larger, and the projection line segment of 2 positioning points on the secondary positioning surface on the main positioning surface is longer, the better the positioning scheme formed by discrete points is.
And 5, determining the tolerance distribution type of the key characteristic, including the tolerance value of the key characteristic and the obedience distribution rule thereof, wherein the obedience distribution rule of the key characteristic is obtained according to relevant actual processing experience, and if relevant statistical data is lacked, the key characteristic can be considered to obey normal distribution.
And 6, calculating the assembly deviation by adopting a Monte Carlo method according to the deviation transfer relation. And (4) taking the tolerance value of the key characteristics in the step (5) and the distribution rule obeyed by the tolerance value as input, and calculating the assembly deviation according to the deviation transfer function in the step (3).
And 7, redistributing the assembly tolerance according to sensitivity analysis. If the assembly deviation obtained according to the initial tolerance does not meet the design requirement in the step 6, sensitivity analysis is needed to be carried out on the key characteristics, the assembly tolerance is redistributed according to the sensitivity analysis result, and the steps 6 and 7 are repeated until the precision requirement is met.
And 8, obtaining an assembly tolerance distribution scheme according with the assembly precision. And if the assembly deviation analysis result calculated in the step 7 meets the design requirement, outputting the current tolerance distribution scheme as a final tolerance distribution scheme.
The invention has the advantages and positive effects that:
1. the method takes the assembly precision requirement as a control target, identifies the geometric characteristics closely related to the assembly precision as key characteristics, disperses the characteristic surfaces related to the key characteristics as characteristic points, and can conveniently and quickly calculate the assembly deviation by relying on a deviation transfer function so as to determine an assembly tolerance scheme, provide guidance for actual assembly, and improve the assembly precision and the assembly efficiency.
2. The method verifies whether the existing product tolerance can meet the assembly precision requirement or not through the analysis of the assembly deviation, provides guidance for actual assembly, and can greatly improve the assembly precision and the assembly efficiency.
3. The method is a deviation analysis method based on a three-dimensional digital model in a three-dimensional environment, is closer to actual assembly compared with the traditional two-dimensional deviation analysis method, can comprehensively consider various tolerances, and has wide application range.
4. The method is characterized in that the feature points are used as basic units to carry out deviation transmission calculation, the characteristic lays a foundation for the subsequent connection with finite element analysis, and the application range of the method is further expanded.
Drawings
FIG. 1 is a flow chart of an assembly tolerance assignment method of the present invention;
FIG. 2 is a schematic view of an unmanned boat configuration;
FIG. 3 is an assembled cross-sectional view of the power propulsion device of the unmanned boat;
FIG. 4 is a schematic view of a propeller assembly with discrete points, 4a, perspective view 1; 4b, a perspective view of fig. 2;
FIG. 5 is a schematic diagram of host component feature point dispersion.
The specific implementation mode is as follows:
a method of assigning assembly tolerances for an unmanned boat power propulsion device, as shown in figure 1, comprising the steps of:
step 1: and acquiring a three-dimensional assembly model of the product, checking whether the model information is complete, and if the model information is incomplete, adding related models or information. And extracting the research object, and numbering the feature surfaces of the components, wherein the numbering is the unique numbering of the parts and the feature surfaces in the method. And obtain the assembly accuracy requirements, translated into a gap (or distance value) between two or more features.
The overall structure of the unmanned boat is shown in figure 2, and the cross section schematic view of the power propulsion device is shown in figure 3. The assembly precision of the shaft of the power propulsion device requires that the distance between two axes of the power propulsion device is less than or equal to 3 mm. Wherein f is01The inner surface of the hole for the tail plate to fit with the propeller shaft, f02Is the outer surface of the tail plate, f03The upper surface of the rib plate matched with the host machine; f. of11Is the outer surface of the propeller shaft, f12End face of propeller flange, f13、f14、f15Is the inner surface of the flange end surface hole; f. of21、f22、f23Is the lower surface of the damping sheet of the main machine f24、f25、f26Are respectively reducedThe inner surface of the seismic patch hole.
Step 2: and extracting the fitting constraint relation and the initial tolerance information of the unmanned boat power propulsion device. The description of the fit constraint relationship is based on the part number in step 1. Because the deformation of the parts is not involved in the assembling process of the power propulsion device, the geometric position state of the parts is mainly considered in the assembling constraint relation.
The fit constraint relationship between the power propulsion unit parts extracted in step 1 is described as follows:
e1＝(f01，f11)，e2＝(f02，f12)，e3＝(f03，(f21，f22，f23))，
and 3, identifying key characteristics of the power propulsion device of the unmanned ship, and determining an assembly deviation transfer relationship. The key characteristics involved are determined according to the assembly precision requirement in step 1 and the assembly constraint relation in step 2, and the Key Characteristics (KC) are the basis of the deviation transfer analysis.
The transfer relationship here can be described as: Δ ui＝ui(ui-1，KCi1，KCi2，…)。
Combining the above results, the initial tolerance of Kc is:
and 4, performing characteristic point dispersion on the key characteristic surface depending on the key characteristics according to the characteristic point dispersion rule. The propeller and the main engine assembly are dispersed into 6 positioning points according to a dispersion rule, and refer to fig. 4 and fig. 5 respectively: two end points of propeller axis
And a center point
The flange surface is discrete at 3 points
Two end points of main machine axis
And a midpoint
Center point of 3 damping sheet holes
Step 5, determining the tolerance distribution type of the key characteristic,
the distribution rule of the key characteristic obeying is obtained according to relevant actual processing experience, and if relevant statistical data are lacked, the key characteristic can be considered to obey normal distribution. All tolerances are considered herein to follow a normal distribution.
And 6, calculating the assembly deviation by adopting a Monte Carlo method according to the deviation transfer relation. And (5) taking the tolerance value of the key characteristics in the step 5 and the distribution rule obeyed by the tolerance value as input, and calculating the assembly deviation according to the deviation transfer relation in the step 3.
And 7, redistributing the assembly tolerance according to sensitivity analysis. If the assembly deviation obtained according to the initial tolerance does not meet the design requirement in the step 6, sensitivity analysis is needed to be carried out on the key characteristics, the assembly tolerance is redistributed according to the sensitivity analysis result, and the steps 6 and 7 are repeated until the precision requirement is met.
Through sensitivity analysis, the adjusted tolerance value is as follows:
and 8, obtaining an assembly tolerance distribution scheme according with the assembly precision. And if the assembly deviation analysis result calculated in the step 7 meets the design requirement, outputting the current tolerance distribution scheme as a final tolerance distribution scheme.
It should be emphasized that the embodiments described herein are illustrative rather than restrictive, and thus the present invention is not limited to the embodiments described in the detailed description, but also includes other embodiments that can be derived from the technical solutions of the present invention by those skilled in the art.
Claims (9)
1. An assembly tolerance distribution method for an unmanned boat power propulsion device is characterized by comprising the following steps: the method comprises the following steps:
step 1, obtaining a three-dimensional assembly model of an unmanned ship power propulsion device and assembly precision requirements;
step 2, extracting the matching constraint relation and the initial tolerance information of the unmanned ship power propulsion device;
step 3, identifying key characteristics of the power propulsion device of the unmanned ship, and determining an assembly deviation transfer relationship;
step 4, performing characteristic point dispersion on a key characteristic surface depending on key characteristics according to a characteristic point dispersion rule;
step 5, determining the tolerance distribution type of the key characteristics, including the tolerance value of the key characteristics and the distribution rule obeyed by the key characteristics;
step 6, calculating the assembly deviation by adopting a Monte Carlo method according to the deviation transfer relation;
step 7, redistributing the assembly tolerance according to sensitivity analysis;
and 8, obtaining an assembly tolerance distribution scheme according with the assembly precision.
2. The assembly tolerance assignment method for an unmanned boat power propulsion device according to claim 1, wherein: and (3) numbering and identifying the components related to the three-dimensional assembly model in the step (1), wherein the final assembly precision requirement is specific to the gap precision requirement between two or more characteristic surfaces.
3. The assembly tolerance assignment method for an unmanned boat power propulsion device according to claim 2, wherein: the matching constraint relation in the step 2 is described based on the number of the components in the step 1; the geometric position state of the part is mainly considered in cooperation with the constraint relation; fitting constraint relationships can be divided into: the internal dimension and the form and position of the part are restricted, and the matching and restricting relationship between the parts and the tooling is realized.
The fit constraint relationship between the power propulsion unit parts extracted in step 1 is described as follows:
e(fx,fy)
e denotes the established constraint relationship, fx、fyRepresenting two facets that participate in the fit constraint.
4. The assembly tolerance assignment method for an unmanned boat power propulsion device according to claim 1, wherein: the key characteristics involved in the step 3 are determined according to the assembly precision requirement in the step 1 and the assembly constraint relation in the step 2; the Key Characteristic (KC) is the basis of the bias transfer analysis, which can be described by the following formula:
Δui＝ui(ui-1,KCi1,KCi2,…)
in the formula:
Δui-assembly deviation of the ith part;
ui-1-assembly deviation of the (i-1) th part;
KCi1,KCi2-KC deviations in the ith part that participate in the transfer of deviations;
ui-the part deviation transfer function is determined by a specific fit constraint relationship.
5. The assembly tolerance assignment method for an unmanned boat power propulsion device according to claim 1, wherein: the feature plane-based discrete rule in step 4 is as follows:
according to the "3-2-1" positioning principle, the main positioning plane limits three degrees of freedom: a z-translation and a rotation in both directions around the x and y axes, the secondary positioning surface limits two degrees of freedom: an x-direction translation and a rotation around the z-axis, the third positioning surface limits the y-direction movement; the 6 degrees of freedom are limited, and the complete positioning of the part in the space is realized; evaluating the quality of the positioning scheme through geometric stability, and determining the following positioning point discrete method: when the area of a triangle formed by 3 positioning points on the main positioning surface is larger, and the projection line segment of 2 positioning points on the secondary positioning surface on the main positioning surface is longer, the better the positioning scheme formed by discrete points is.
6. The assembly tolerance assignment method for an unmanned boat power propulsion device according to claim 1, wherein: the distribution rule of the key characteristic obeying in the step 5 is obtained according to relevant actual processing experience, and if relevant statistical data are lacked, the key characteristic can be considered to obey normal distribution.
7. The assembly tolerance assignment method for an unmanned boat power propulsion device according to claim 1, wherein: the monte carlo deviation calculation method in the step 6 takes the tolerance value of the key characteristics in the step 5 and the obedient distribution rule thereof as input, and calculates the assembly deviation according to the deviation transfer relationship in the step 3.
8. The assembly tolerance assignment method for an unmanned boat power propulsion device according to claim 1, wherein: and 7, when the assembly deviation obtained by the initial tolerance does not meet the design requirement, sensitivity analysis is needed to be carried out on the key characteristics, the assembly tolerance is redistributed according to the sensitivity analysis result, and the steps 6 and 7 are repeated until the precision requirement is met.
9. The assembly tolerance assignment method for an unmanned boat power propulsion device according to claim 1, wherein: in step 8, if the assembly deviation analysis result calculated in step 7 meets the design requirement, the existing tolerance distribution scheme is output as the final tolerance distribution scheme.
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| CN111783249A (en) * | 2020-06-30 | 2020-10-16 | 北京理工大学 | Assembly precision analysis method, device and system |
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- 2021-01-08 CN CN202110027809.3A patent/CN112711814A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108629453A (en) * | 2018-05-04 | 2018-10-09 | 西北工业大学 | A kind of aircraft assembled in situ accuracy prediction method based on measured data |
| CN111158314A (en) * | 2019-12-31 | 2020-05-15 | 东南大学 | Satellite partial assembly precision control method based on digital twinning technology |
| CN111783249A (en) * | 2020-06-30 | 2020-10-16 | 北京理工大学 | Assembly precision analysis method, device and system |
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