The Assembly Tolerancy Analysis Method Of The Part Location With One Surface And Two Pins

With the repetitive and large-scale production processing of machinery,all final products' quality of this type and batch determined by the tolerance design of the model product.Apparently,it also affects the final performance of products.The target component,based on the assembly part,which datum reference is one plane with two holes assembling with the target component,based on the position part,which datum reference is one plane with two axis is a kind of assembly form of machinery products.Because of the error value of boundary size and location between the design datum reference frame(DRF),which is decided by the reference axis and reference hole,and the actually measurement datum's DRF,the design datum of Mcasured feature is not unified with the actual measurement datum which makes the design datum could float that allowed by the tolerance standard in the size difference of two boundary.That affects the final assembly tolerance a lot.In order to solve this problem,the paper used position and reassembly of gear pump based on position design of two-hole-one-side,used the API function and vc ++ for secondary development based on SolidWorks 3D software as a platform.What's more,the paper researched the influence from assembly and positioning parts' assembly datum error of gear pump to alignment of the target holes,analyzed the calculation method of assembly success rate and assembling position error,based on the geometric elements control principle simulating the change of geometric elements within the tolerance zone and real parts assembly.Along with the in-depth study in the field of tolerance and the development of computer technology,Computer Aided tolerance design technology is widely used in the mechanical product tolerance analysis.On the basis of the CAT technology,this paper do the following research through the Solid Works software platform and function module developed by the second time:(1)Tolerance information extraction of 3 d entity model in the Solid Works.,The paper realized the tolerance information extraction and preservation of 3 d model surface,as well as the tolerance information of extraction and preservation of associated elements based on Solid Works built-in API function.(2)The establishment of the tolerance information structure.The paper used the extracted tolerance information as well as its associated factors of adhesion to establish tolerance information structure which contains assembly relationship between parts and theposition relationship between datum features.(3)Using the change model of control points represent graphic design and cylindrical design.The paper used Monte Carlo Simulation Method to generate locus of control variable parameters according to the geometric elements of tolerance control points of probabilistic sampling.(4)Setting up location coordinate according to machine positioning base.The paper established relative position relations between location coordinates relative to the global coordinate system of the machine.(5)Establishing the assembly coordinate system of Assembly datum by the assembly part according to the actual feature.Establishing the position relationship between each other which is the assembly coordinate system relative to the assembly parts of the local coordinate system.That means the assembly coordinate system can be confirmed by the local coordinate system.On contrary,the local coordinate system can be determined by the assembly coordinate system.(6)Establishing the relationship between positioning coordinate system and assembly coordinate system according to the instances of probability sampling from the datum reference of the orientation of machine parts and assembly datum of assembly parts.(7)Using the probabilistic method to calculate the result of probability statistics between assembly coordinate system and local coordinate system,which are from the given the tolerance of sampling.