CN116756849A - Method, device and equipment for analyzing size chain based on part centering assembly - Google Patents
Method, device and equipment for analyzing size chain based on part centering assembly Download PDFInfo
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Abstract
The application relates to a dimension chain analysis method, a dimension chain analysis device and dimension chain analysis equipment based on part centering assembly, which comprise the steps of determining a part assembly scheme related to a target dimension chain as a centering assembly scheme; determining a closed loop and a component loop in the target size link; determining the calculation direction of the target size chain as the direction needing centering; calculating a centering influence coefficient K, and determining a size chain calculation table of centering assembly of the parts; after determining the tolerance requirement of the matched parts, substituting the tolerance requirement into a calculation table to obtain a final result; the application aims to define a dimension chain analysis method of a centering assembly scheme, considers the centering assembly influence in a dimension chain, and summarizes a quick and relatively accurate dimension chain analysis and calculation method after three-dimensional simulation analysis, comparison and verification, wherein the calculation result is more accurate, the deviation is small, and the real vehicle state can be accurately pre-judged; the calculation result can be directly obtained by substituting the tolerance through a general calculation tool, and the calculation precision and efficiency are improved.
Description
Technical Field
The application belongs to the technical field of vehicle design methods, and relates to a dimension chain analysis method, a dimension chain analysis device and dimension chain analysis equipment based on part centering assembly.
Background
During machine assembly or part machining there are always a number of interconnected dimensions that are connected in a sequence to form a closed set of dimensions, called a dimensional chain. The size chain is composed of a component ring and a closed ring; the closed loop is formed last, so that before the processing or assembly is completed, it does not exist, the size of the closed loop cannot be guaranteed by itself, and is guaranteed by other sizes; other dimensions are called component rings, which are dimensions obtained directly during processing, the variation of which has an effect on the closed ring.
In the actual production and manufacturing process of automobile parts, perfect parts are difficult to manufacture, the actually manufactured parts often deviate from ideal design (manufacturing tolerance), positioning deviation (assembly tolerance) can be generated in the assembly process of the parts, the deviation is accumulated continuously in the assembly process, and finally, the deviation is accumulated into the dimensional deviation of a product.
For the characteristics of the automobile, the assembly size chain is relatively complex, and the accumulated tolerance is large; aiming at certain parts, such as an engine cover, a back door, an instrument board and the like, the assembly of the parts needs to be compatible with the parts on two sides, otherwise, the parts positioned on one side can have inconsistent real vehicle states in bilateral symmetry positions, the contrast of the left and right differences of gap section differences is obvious, the visual perception is poor, and the defective products easily cause customer complaints after flowing into the market. Therefore, the key parts are required to be assembled in a part centering way, the matching state of the key parts and the parts at two sides is ensured to be close, and the left-right difference of the gap section difference is well controlled; meanwhile, the dimension chain checking of the centering assembly scheme of the part is required to be carried out in the earlier stage design, so that the positioning system can support the appearance quality target requirement of the product, the out-of-tolerance risk is identified as early as possible, and optimization measures are adopted in advance.
In the current modeling stage of the vehicle model item, the dimension chain analysis method aiming at the part centering assembly scheme is not clear, generally, one-dimensional dimension chain analysis is carried out according to the traditional dimension chain transmission mode only based on the part tolerance before centering, the centering assembly influence is not considered, the out-of-tolerance risk is large, the calculation result is inaccurate, the deviation is large, the scheme comparison analysis cannot be effectively guided, and the deviation real vehicle state cannot be accurately pre-judged.
The most common calculation of the dimension chain of the centering assembly scheme of the parts by most host factories in the automobile industry is that the dimension chain is analyzed by computer software such as 3DCS, VSA and the like; the method has harsh analysis conditions, the preconditions of the method are digital-analog, the modeling time is long, the workload is large (the modeling of the whole vehicle level is often needed), and the calculation result of a certain specific-size chain cannot be obtained quickly.
Patent document CN102490137B discloses a centering and positioning tool for automobile assembly, which comprises a positioning bracket, wherein a workpiece positioning pin is arranged on the positioning bracket; the bottom end of the positioning support is provided with a Z-direction supporting block, and X-direction positioning pins are respectively arranged on two sides of the positioning support, which are positioned in the X direction of the automobile; centering and positioning mechanisms are respectively arranged on two sides of the positioning bracket in the Y direction of the automobile; the central lines of the centering and positioning mechanisms are coincident. The centering positioning tool realizes centering positioning of the workpiece when assembling the workpiece, reduces the assembly adjustment time and the assembly adjustment work, reduces the labor intensity of staff, reduces the assembly error of the workpiece, and improves the production assembly efficiency and the product quality and the production efficiency. This patent document mainly relates to centering and positioning tools for automobile assembly, and does not mention a method for calculating a dimension chain for centering assembly.
Patent document CN108108555B discloses an assembly dimension chain calculation method, apparatus and device, the assembly dimension chain calculation method comprising: determining a deviation vector of geometric features involved in matching when at least two components are matched and a variation interval of each component in the deviation vector; determining a fit deviation expression of an actual fit surface between the at least two components relative to an ideal fit surface according to the deviation vector; calculating the variation interval of each component in the coordination deviation expression according to the variation interval of each component in the deviation vector; and solving an assembly dimension chain of at least one assembly group according to the fit deviation expression and the variation interval of each component in the fit deviation expression, wherein the assembly group is formed by matching at least two components. This patent document is mainly directed to assembly dimension chain calculation methods, which are dimension chain calculation with respect to conventional positioning, and does not mention dimension chain calculation methods for centering assembly.
Patent document CN113032903B relates to the technical field of vehicle design methods, and specifically discloses a white body size chain tolerance allocation optimization calculation method. Acquiring a distance sensitivity coefficient according to the distance of the white body size chain ring; obtaining a connection influence coefficient according to a connection assembly mode of the white automobile body parts; correcting the statistical tolerance calculation model through the distance sensitivity coefficient and the connection influence coefficient to obtain a tolerance distribution calculation model conforming to the white car body; and calculating the tolerance zone of the white car body according to the tolerance distribution calculation model. The influence of the distance of the dimension chain ring on tolerance distribution is considered on the basis of considering the dimension of the parts and the connection assembly mode, so that the accuracy of dimension chain tolerance calculation is further improved. The method for optimizing the allocation of the dimensional chain of the white body disclosed in the document mainly calculates the tolerance zone of the white body according to the connection influence coefficient of the white body parts and the tolerance calculation model, wherein the method for calculating the dimensional chain of the centering assembly is not mentioned.
The above patent has low relevance to the present application.
Disclosure of Invention
The application aims to solve the technical problems in the prior art and provides a dimension chain analysis method based on part centering assembly.
It is noted that relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.
In order to solve the technical problems, the application is realized by adopting the following technical scheme:
a dimensional chain analysis method based on part centering assembly, comprising:
determining a part assembly scheme related to a target size chain as a centering assembly scheme;
determining a closed loop and a component loop in the target size link;
determining the calculation direction of the target size chain as the direction needing centering;
calculating a centering influence coefficient K, and determining a size chain calculation table of centering assembly of the parts;
and after the tolerance requirement of the matched parts is determined, substituting the tolerance requirement into a calculation table to obtain a final result.
The end result is a cumulative tolerance of the dimensional chain corresponding to the centered assembly, i.e., a cumulative tolerance of the apparent gap of the corresponding two mating parts in the finished vehicle.
Further, the component assembly scheme involved in determining the target dimension chain is a centering assembly scheme, which specifically comprises the following steps: only part A, gap block and part B are involved in the target size chain; the positioning and centering assembly of the clearance direction are realized by the clearance block between the part A and the part B, the positioning point and the assembly point of the part are the contact points with the clearance block, and the assembly is completed when the clearances at the two sides are consistent.
The present application is directed to a centered assembly between two parts because the centered assembly involves only a centered condition of the a piece relative to the B piece.
Further, the closed loops and constituent loops in the determined target size links; the specific contents include:
the fit clearance G/G' between the part A and the part B is a closed ring, and the rest is a component ring.
Further, the calculated direction of the target size chain is the direction needing centering; the specific contents include:
the direction of the chain ring is the direction needed to be centered, and the direction is Y-direction for the automobile.
Further, the centering influence coefficient K is obtained through calculation, and a size chain calculation table for centering assembly of the parts is determined; the specific contents include:
each component ring comprises a gap measurement point tolerance, a Y-direction positioning point tolerance and a gap block tolerance of two parts;
the profile of the left and right clearance matching surfaces of the part A are Ta and Ta ', the profile of the left and right clearance matching surfaces of the part B are Tb and Tb', and the manufacturing tolerance of the clearance block is +/-Tz;
the point a and the point a 'are centering reference points on the part A, and the point B' are centering reference points on the part B, namely Y-direction positioning reference points; the point c is the middle point of fitting after centering of the part A, and the point c' is the middle point of fitting after centering of the part B;
the tolerance of the two part gap measuring points (g, g ', g1 and g 1') needs to consider the tolerance of the two part gap measuring points relative to the Y-direction positioning reference point, so that the tolerance is the parallel difference of the parts and is half of the profile of the part gap matching surface, namely Tg=Tg '=Ta/2, and Tg1=Tg1' =Tb/2;
the tolerance of the Y-direction locating points of the two parts is the tolerance obtained after the centering assembly of the parts, and is the tolerance obtained after the equipartition of the functional sizes of the left locating point and the right locating point at the bilateral symmetry positions, namelyThe tolerance requirements for the symmetrical mating position of the Y-direction symmetrical parts are uniform, i.e. ta=ta ', tb=tb', soThe centering influence coefficient k of the two mating parts is +.>
And obtaining a chain calculation table of the gap sizes of the two matched parts assembled in a centering way.
Further, point c coincides with point c' when part a is centered with respect to part B.
Further, after the tolerance requirement of the matched part is determined, substituting the tolerance requirement into a calculation table to obtain a final result; the specific contents include:
taking the clearance matching surface profile of the part A as 1.4 and the clearance matching surface profile of the part B as 2.0, taking the clearance block manufacturing tolerance + -0.15 as an example, substituting each component ring tolerance into a calculation table respectively to obtain a calculation result;
i.e.
TG' =tg=3σ - (-3σ) =6σ, which is the tolerance of the fit clearance of the parts of the whole vehicle.
A dimensional chain analysis device based on part centering assembly, comprising:
the first determining module is used for determining that the part assembly scheme related to the target size chain is a centering assembly scheme;
a second determining module for determining a closed loop and a component loop in the target size link;
the third determining module is used for determining the calculation direction of the target size chain as the direction needing centering;
the first calculation module is used for calculating a centering influence coefficient K and determining a size chain calculation table of the centering assembly of the parts;
and the second calculation module is used for determining the tolerance requirement of the matched parts and substituting the tolerance requirement into the calculation table to obtain a final result.
Further, the first calculation module is used for calculating a centering influence coefficient K and determining a dimension chain calculation table of the centering assembly of the part; the specific calculation method comprises the following steps: the centering influence coefficient k of the two matched parts isDetermining extreme values, probabilities and contribution rates in a dimension chain calculation table assembled in the part pair;
determining a probability method calculation result in a dimension chain calculation table of part centering assembly, namely a calculation result of +/-3 sigma; the calculation result of the probability method is obtained based on a tolerance zone, and the relation between the probability method and + -3 sigma is a double relation;
i.e.
TG' =tg=3σ - (-3σ) =6σ, which is the tolerance of the fit clearance of the parts of the whole vehicle.
An apparatus comprising a processor, a memory, and a computer program stored on the memory and executable on the processor, which when executed by the processor implements a dimensional chain analysis method based on part centering assembly as described above.
Compared with the prior art, the application has the beneficial effects that:
the application aims to define a dimension chain analysis method of a centering assembly scheme, considers the centering assembly influence in a dimension chain, and summarizes a quick and relatively accurate dimension chain analysis and calculation method after three-dimensional simulation analysis, comparison and verification, wherein the calculation result is more accurate, the deviation is small, and the real vehicle state can be accurately pre-judged; the calculation result can be directly obtained by substituting the tolerance through a general calculation tool, and the calculation precision and efficiency are improved.
Drawings
The application is further described below with reference to the accompanying drawings:
FIG. 1 is a schematic illustration of a part centering assembly scheme and a dimensional chain;
FIG. 2 is a flow chart of a method for analyzing a dimensional chain based on centering assembly of parts according to the present application.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application become more apparent, the technical solutions in the embodiments of the present application will be described in more detail below with reference to the accompanying drawings in the embodiments of the present application. In the drawings, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The described embodiments are some, but not all, embodiments of the application. The embodiments described below by referring to the drawings are illustrative and intended to explain the present application and should not be construed as limiting the application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application. Embodiments of the present application will be described in detail below with reference to the accompanying drawings.
In the description of the present application, it should be understood that the terms "center," "longitudinal," "lateral," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, merely to facilitate describing the present application and simplify the description, and do not indicate or imply that the devices or elements being referred to must have a specific orientation, be configured and operated in a specific orientation, and therefore should not be construed as limiting the scope of the present application.
The application is described in detail below with reference to the attached drawing figures:
the dimension chain analysis thought is novel and clear, the centering assembly influence is integrated into the dimension chain ring through calculating the centering coefficient, and the analysis method is more accurate and comprehensive;
the size chain analysis method is clear, the calculation process is simple, convenient and quick, and the real vehicle assembly risk can be quickly and intuitively identified;
the size chain analysis and calculation method is suitable for part centering assembly schemes of various parts;
the one-dimensional dimension chain calculated by the method is more accurate in result, small in deviation and closer to a real vehicle state in assembly risk.
In order to make the technical problems, technical schemes and advantages to be solved more clear, the component centering assembly scheme and the one-dimensional dimension chain calculation method thereof will be further described with reference to the accompanying drawings.
1. The specific analysis and calculation steps of the application are described with reference to fig. 2:
1.1 definition of the part Assembly scheme involved in the target size chain
Only part A, gap block and part B are involved in the target size chain; the positioning and centering assembly of the clearance direction are realized by the clearance block between the part A and the part B, the positioning point and the assembly point of the part are the contact points with the clearance block, and the assembly is completed when the clearances at the two sides are consistent.
1.2 definition of target size links and their orientation
The fit clearance G/G' between the part A and the part B is a closed ring, the rest is a component ring, the direction of the chain ring is the direction needed to be centered, and the direction is generally Y-direction for automobiles.
1.3 tolerance requirement and centering coefficient of explicitly matched parts
Each component ring comprises a gap measurement point tolerance, a Y-direction locating point tolerance and a gap block tolerance of two parts.
The profile of the left and right gap matching surfaces of the part A are Ta and Ta ', respectively, the profile of the left and right gap matching surfaces of the part B are Tb and Tb', respectively, and the manufacturing tolerance of the gap block is +/-Tz.
The point a and the point a 'are centering reference points on the part A, and the point B' are centering reference points on the part B, namely Y-direction positioning reference points; point c is the mid-point of the fit after centering of part a and point c 'is the mid-point of the fit after centering of part B, point c and point c' being coincident when part a is theoretically centered with respect to part B.
Referring to fig. 1, the tolerance of the two parts gap measurement points (g, g ', g 1') needs to consider the tolerance of the two parts gap measurement points relative to the Y-direction positioning reference point, so the tolerance should be the parallel difference of the parts, generally half of the profile of the part gap matching surface, i.e. tg=tg '=ta/2, tg1=tg1' =tb/2; when the parallel difference has special requirements, the tolerance value is directly substituted into the tolerance list.
The numbers 1-5 in FIG. 1 represent the numbers of the constituent rings, and the numbers 1-5 in Table 1 represent the transfer directions of the constituent rings according to the numbers 1-5.
The tolerance of the Y-direction locating points of the two parts is the tolerance obtained after the centering assembly of the parts, so the tolerance is the tolerance obtained after the functional dimensions of the left locating point and the right locating point are equally divided at the bilateral symmetry positions, namelySince the tolerance requirements for the symmetrical mating position of the Y-direction symmetrical parts are uniform, i.e. ta=ta ', tb=tb', the tolerance requirements are identicalTherefore, the centering influence coefficient k of the two matched parts is +.>
Based on the above analysis, a two-fitting part gap dimension chain calculation tool for centered assembly was obtained as shown in table 1.
Table 1 shows a chain of gap sizes for two mating parts assembled in a pair
After the obtained dimension chain calculation table, a dimension chain accumulation method corresponding to the centering assembly scheme is found, and after the similar centering assembly scheme is encountered, the dimension chain calculation table can be directly carried into the table based on part tolerance. The cumulative tolerance of the apparent clearances of the corresponding two mating parts in the finished vehicle in table 1 is obtained. The calculation result is a specific whole vehicle tolerance value, and the tolerance values corresponding to different parts are different. Such as a back door and a side wall, and a front windshield and a side wall, because the tolerance of parts at different positions is different, the tolerance calculation result corresponding to the appearance clearance of the whole vehicle is different.
The + -3σ represents the corresponding standard deviation under a normal too much distribution, i.e., the degree of dispersion of the gap state that may occur after assembly of the part. The table is mainly used for calculating the cumulative tolerance under the probability method, namely the forward distribution method, so that parameters such as an extremum method, a contribution rate and the like can not be referred to.
The relation between every two parts can be accumulated, the method is mainly used for explaining a tolerance accumulation calculation method between every two parts under centering assembly, and aiming at non-centering assembly, the matching surface profile corresponding to the two parts can be directly used, but for centering assembly parts, the centering process is carried out, the centering influence needs to be considered, and the calculation result is more accurate and more practical.
Table 1 is a calculation tool, and as long as the calculation tool accords with centering assembly, the surface profile of the gap matching surface of two parts can be known and substituted into a formula for calculation, the formula is mainly embodied on a centering coefficient, the coefficient is not generated in a common size chain calculation method, and the calculation result is larger and has larger phase difference with the actual one.
The universality is shown in that the formula is suitable for analyzing matched parts assembled in all pairs, and the calculation result can be obtained rapidly and accurately. The calculation method is suitable for tolerance stack-up between parts of a centering assembly scheme, such as centering assembly of parts of a back door, a trunk lid, a back air window, a front air window, an engine cover, an instrument panel and the like of an automobile.
1.4 bringing the component Ring tolerance to obtain the target size chain calculation
Taking the clearance matching surface profile of the part A as 1.4 and the clearance matching surface profile of the part B as 2.0, and taking the clearance block manufacturing tolerance of +/-0.15 as an example, substituting each component ring tolerance into the table 2 respectively, and obtaining the following calculation results:
TABLE 2 chain of gap size calculation for part A and part B
Taking the example that the back door is assembled on the side wall in a centering way, the clearance matching surface profile degree Ta of the part A (the back door) is 1.4, the clearance matching surface profile degree Tb of the part B (the side wall) is 2.0, the manufacturing tolerance Tz of the clearance block is +/-0.15, and the accumulated tolerance calculation results of the back door and the side wall matching clearance shown in the table 2 can be obtained by substituting the component ring tolerances into the table 1. The tolerance mode for each component ring is illustrated by the 1 st component ring as follows, part A: the profile of the clearance fit face (parallel difference) with the part B was found by substituting Ta for Ta/2=1.4/2=0.7 for the corresponding tolerance (tolerance zone) in the first row of the table, ta/4=1.4/4=0.35 for the corresponding ±3σ, and so on, and respectively substituting the respective constituent zones into table 1, the cumulative tolerance zone for the fit clearance of the corresponding back door and side wall after the back door was fitted to the side wall as shown in table 2 was found to be 2.14, which ±3σ was
±1.065。
The application realizes the innovation of a one-dimensional dimension chain analysis thought and a calculation method for the centering assembly of the parts. The conventional thinking of a one-dimensional chain is broken through, the influence of the centering process is added into the dimensional chain ring through calculating the centering influence coefficient, and the analysis process is more accurate and comprehensive.
The method has the advantages of very simple calculation formula, easy understanding and ensured accuracy, and is suitable for size engineering beginners.
The method has universality and can be used for calculating the dimension chain calculation of the part centering assembly of various parts.
The assembly risk of the parts calculated by the size chain calculation method is more accurate and is closer to the state of a real vehicle.
The application mainly obtains centering influence coefficients after definite centering assembly, and then substitutes part tolerances according to a table 1 to obtain the calculation result of the whole vehicle clearance tolerance. The main protection point is the identification of the process and size chain links that derive the impact coefficients. The difference is that the conventional size chain algorithm has no influence coefficient in the past calculation, the size chain loops are fewer than the prior size chain algorithm (only 3 loops), and the consideration is incomplete.
The application protects the relationship of two centrally mounted parts. The universality is shown in that the formula is suitable for analyzing matched parts assembled in all pairs, and the calculation result can be rapidly and accurately obtained based on the centering influence coefficient and the identification of the composed chain ring. The calculation method is suitable for tolerance stack-up between parts of a centering assembly scheme, such as centering assembly of parts of a back door, a trunk lid, a back air window, a front air window, an engine cover, an instrument panel and the like of an automobile.
The application provides another embodiment, a dimension chain analysis device based on part centering assembly, comprising: the first determining module is used for determining that the part assembly scheme related to the target size chain is a centering assembly scheme; a second determining module for determining a closed loop and a component loop in the target size link;
the third determining module is used for determining the calculation direction of the target size chain as the direction needing centering;
the first calculation module is used for calculating a centering influence coefficient K and determining a size chain calculation table of the centering assembly of the parts;
and the second calculation module is used for determining the tolerance requirement of the matched parts and substituting the tolerance requirement into the calculation table to obtain a final result.
The first calculation module is used for calculating a centering influence coefficient K and determining a size chain calculation table of the centering assembly of the parts; the specific calculation method comprises the following steps: the centering influence coefficient k of the two matched parts isDetermining extreme values, probabilities and contribution rates in a dimension chain calculation table assembled in the part pair;
and determining the calculation result of the probability method in the dimension chain calculation table of the assembly of the part pair, namely the calculation result of +/-3 sigma. (the probability method calculation result is based on the tolerance zone, the relationship with + -3σ is a double relationship.)
I.e.
TG' =tg=3σ - (-3σ) =6σ, which is the tolerance (tolerance zone) of the fit-on gap of the whole vehicle parts.
The application provides another embodiment, an apparatus comprising a processor, a memory, and a computer program stored on the memory and executable on the processor, which when executed by the processor, implements a dimensional chain analysis method based on part centering assembly as described above.
The foregoing is merely illustrative of specific embodiments of the present application, and the scope of the application is not limited thereto, but any modifications, equivalents, improvements and alternatives falling within the spirit and principles of the present application will be apparent to those skilled in the art within the scope of the present application. And all that is not described in detail in this specification is well known to those skilled in the art.
Claims (10)
1. A dimensional chain analysis method based on part centering assembly, comprising:
determining a part assembly scheme related to a target size chain as a centering assembly scheme;
determining a closed loop and a component loop in the target size link;
determining the calculation direction of the target size chain as the direction needing centering;
calculating a centering influence coefficient K, and determining a size chain calculation table of centering assembly of the parts;
and after the tolerance requirement of the matched parts is determined, substituting the tolerance requirement into a calculation table to obtain a final result.
2. A method for dimensional chain analysis based on centered assembly of parts according to claim 1, wherein:
the component assembly scheme involved in determining the target dimension chain comprises the following specific contents: only part A, gap block and part B are involved in the target size chain; the positioning and centering assembly of the clearance direction are realized by the clearance block between the part A and the part B, the positioning point and the assembly point of the part are the contact points with the clearance block, and the assembly is completed when the clearances at the two sides are consistent.
3. A method for analyzing a dimensional chain based on centering assembly of parts according to claim 2, wherein:
the closed loop and the component loops in the link with the determined target size; the specific contents include:
the fit clearance G/G' between the part A and the part B is a closed ring, and the rest is a component ring.
4. A method of dimensional chain analysis based on centered assembly of parts according to claim 3, wherein:
the calculation direction of the target size chain is the direction needing centering; the specific contents include:
the direction of the chain ring is the direction needed to be centered, and the direction is Y-direction for the automobile.
5. The method for analyzing the dimensional chain based on the centering assembly of the parts according to claim 4, wherein the method comprises the following steps:
the centering influence coefficient K is obtained through calculation, and a size chain calculation table for centering assembly of the parts is determined; the specific contents include:
each component ring comprises a gap measurement point tolerance, a Y-direction positioning point tolerance and a gap block tolerance of two parts;
the profile of the left and right clearance matching surfaces of the part A are Ta and Ta ', the profile of the left and right clearance matching surfaces of the part B are Tb and Tb', and the manufacturing tolerance of the clearance block is +/-Tz;
the point a and the point a 'are centering reference points on the part A, and the point B' are centering reference points on the part B, namely Y-direction positioning reference points; the point c is the middle point of fitting after centering of the part A, and the point c' is the middle point of fitting after centering of the part B;
the tolerance of the two part gap measuring points (g, g ', g1 and g 1') needs to consider the tolerance of the two part gap measuring points relative to the Y-direction positioning reference point, so that the tolerance is the parallel difference of the parts and is half of the profile of the part gap matching surface, namely Tg=Tg '=Ta/2, and Tg1=Tg1' =Tb/2;
the tolerance of the Y-direction locating points of the two parts is the tolerance obtained after the centering assembly of the parts, and is the tolerance obtained after the equipartition of the functional sizes of the left locating point and the right locating point at the bilateral symmetry positions, namelyThe tolerance requirements for the symmetrical mating position of the Y-direction symmetrical parts are uniform, i.e. ta=ta ', tb=tb', soThe centering influence coefficient k of the two mating parts is +.>
And obtaining a chain calculation table of the gap sizes of the two matched parts assembled in a centering way.
6. The method for analyzing the dimension chain based on the centering assembly of the parts according to claim 5, wherein the method comprises the following steps:
when part a is centered relative to part B, point c coincides with point c'.
7. The method for analyzing the dimension chain based on the centering assembly of the parts according to claim 5, wherein the method comprises the following steps:
substituting the determined tolerance requirement of the matched part into a calculation table to obtain a final result; the specific contents include:
taking the clearance matching surface profile of the part A as 1.4 and the clearance matching surface profile of the part B as 2.0, taking the clearance block manufacturing tolerance + -0.15 as an example, substituting each component ring tolerance into a calculation table respectively to obtain a calculation result;
the calculation formula is thatI.e.
TG' =tg=3σ - (-3σ) =6σ, which is the tolerance of the fit clearance of the parts of the whole vehicle.
8. A dimensional chain analysis device based on component centering assembly, comprising:
the first determining module is used for determining that the part assembly scheme related to the target size chain is a centering assembly scheme;
a second determining module for determining a closed loop and a component loop in the target size link;
the third determining module is used for determining the calculation direction of the target size chain as the direction needing centering;
the first calculation module is used for calculating a centering influence coefficient K and determining a size chain calculation table of the centering assembly of the parts;
and the second calculation module is used for determining the tolerance requirement of the matched parts and substituting the tolerance requirement into the calculation table to obtain a final result.
9. The dimensional chain analysis device based on part centering assembly according to claim 8, wherein:
the first calculation module is used for calculating a centering influence coefficient K and determining a size chain calculation table of the centering assembly of the parts; the specific calculation method comprises the following steps: the centering influence coefficient k of the two matched parts isDetermining extreme values, probabilities and contribution rates in a dimension chain calculation table assembled in the part pair;
determining a probability method calculation result in a dimension chain calculation table of part centering assembly, namely a calculation result of +/-3 sigma; the calculation result of the probability method is obtained based on a tolerance zone, and the relation between the probability method and + -3 sigma is a double relation;
the calculation formula is thatI.e.
TG' =tg=3σ - (-3σ) =6σ, which is the tolerance of the fit clearance of the parts of the whole vehicle.
10. An apparatus comprising a processor, a memory, and a computer program stored on the memory and executable on the processor, the computer program when executed by the processor implementing the part centering assembly-based dimensional chain analysis method of any one of claims 1 to 8.
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