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343 results about "Position tolerance" patented technology

Position Tolerance (symbol: ⌖) is a geometric dimensioning and tolerancing (GD&T) location control used on engineering drawings to specify desired location, as well as allowed deviation to the position of a feature on a part. Position tolerance must only be applied to features of size, which requires that the feature have at least two opposable points.

Processing method of flexible nozzle thin-wall dual-spherical reinforcing part and device thereof

The invention discloses a processing method of a flexible nozzle thin-wall dual-spherical reinforcing part and a device thereof. The processing method comprises the following steps of: 1, preparing a forging blank; 2, carrying out rough turning; 3, carrying out quenching and tempering; 4, carrying out half finish turning on an inner spherical surface; 5, carrying out destressing and tempering; 6, carrying out turning reference; 7, carrying out finish turning on the inner spherical surface; and 8, carrying out finish turning on an outer spherical surface. The device for implementing the processing method comprises a special inner spherical surface fixture and a special outer spherical fixture. According to the invention, the thin-wall dual-spherical reinforcing part is processed by adopting a special tool and a special clamping and aligning method; the processing accuracy is high; the form and position tolerance totally meets the requirement of a product on the design accuracy. The product prepared by the method provided by the invention achieve complete success by repeated ground test examination. The processing method provided by the invention not only can be used for processing the thin-wall dual-spherical reinforcing part, but also can be used for carrying out processing and controlling on other like thin-wall spherical products.
Owner:湖北三江航天江北机械工程有限公司

Method for precisely measuring inner diameter of multi-direction shaft hole based on laser triangulation method

InactiveCN101788272ASolve the problem of small measurement gapReduce the radial dimension of the measuring rodUsing optical meansPosition toleranceSize measurement
The invention discloses a method for precisely measuring the inner diameter of a multi-direction shaft hole based on a laser triangulation method. A measuring rod extends to the shaft hole to measure the inner diameter of the shaft hole, at least one measuring section is distributed on the measuring rod, at least two measuring heads are distributed on each measuring section, and each measuring head is a measuring member based on the measuring principle of the laser triangulation method. By applying the measuring principle of the laser triangulation method, the invention solves the problem of small measuring gap of the traditional measuring method and accomplishes the precise measurement under the condition of a large gap. A light source for measuring in the invention adopts the light transmission mode of an optical fiber so that the method greatly reduces the radial size of the measuring rod, lowers heat productivity and has obvious superiority in the size measurement of small hole diameters. The invention can accomplish the measurement of the multi-radial direction diameter size and the form and position tolerance of the shaft hole, has the advantages of high measuring efficiency and high speed and precision and can realize high-automation on-line measurement of products.
Owner:TIANJIN UNIV

Unified modeling method of mechanical product tolerance

The invention relates to a tolerance unified modeling method for a mechanical product, which adopts technologies of graph theory, vectors and characteristics, etc., and implements part tolerance element modeling, part tolerance modeling, assembly fit tolerance modeling and assembly body tolerance modeling layer by layer from bottom to top according to an assembly decomposition structure of the product, thereby realizing the unified modeling of product tolerances. The tolerance unified modeling method of the invention is characterized in that: the part tolerance element model is firstly established; each part tolerance element modeling built by extended directed graphs is adopted, and all the part tolerance element modeling are adopted to establish the part tolerance element models by a summation operation of the extended directed graphs; and each assembly fit tolerance modeling built by the extended directed graphs is adopted to establish a produc tolerance unified modeling. The tolerance unified modeling method for the mechanical product has the advantages of realizing the unified modeling of a dimension tolerance, a shape tolerance, a position tolerance and an assembly matching tolerance of the mechanical product. First, the diversity and the ambiguity of the tolerance models are eliminated; second, an assembly dimension chain and error accumulation analysis can be established conveniently.
Owner:NORTHWESTERN POLYTECHNICAL UNIV

Airbag overall dimension detection method based on binocular vision

The invention relates to an airbag overall dimension detection method based on binocular vision. The airbag overall dimension detection method comprises the steps of: (1) calibrating a binocular vision system by using a calibration board; (2) simultaneously shooting a to-be-detected airbag by using a binocular camera, preprocessing two images, then extracting edges, thinning into single pixel, and filling breakpoints; (3) segmenting and matching a contour curve of the to-be-detected airbag; (4) reconstructing a three-dimensional curve segment, and optimizing the curve segment; (5) performing coordinate transformation on the three-dimensional curve segment of the to-be-detected airbag, and matching the three-dimensional curve segment of the to-be-detected airbag with a three-dimensional digital-analog curve segment of the edge contour of a standard airbag; (6) calculating position tolerances Vx,Vy and Vz of detection points and a form tolerance K of the contour curve segment in which the points are positioned, so as to respectively determine whether the detection points are in the ranges of the position tolerances and the form tolerance. Traditional airbag overall dimension detection methods including a three-coordinate detection method and a test tool detection method can be simultaneously replaced by the airbag overall dimension detection method, the cost can be reduced, the efficiency can be improved, and the airbag overall dimension detection method has the advantages of automation, non contact, high precision, high adaptability and the like and can be used for effectively detecting the overall dimensions of various airbags.
Owner:CHANGCHUN UNIV OF TECH

Special-shaped curved surface stator precise compound plasticity shaping process and die

The invention discloses a precise compound plastic forming method of a special shaped curved surface stator of a steering pump. The method is carried out with the following steps: blanking, heating the stock to a full-recrystallization temperature plus or minus 10 DEG C and holding; pre-heating a thermoplastic inverted extrusion mould to a temperature of 200 DEG C-400 DEG C, brushing a lubricant on the mould, placing the stock in the thermoplastic inverted extrusion mould to extrude and obtaining the rough with a single-side working allowance of the inner-type cavity curve of less than or equal to 0.4mm; then heat treating, eliminating the residual stress, processing the upper and the lower end surface of the rough until the depth of parallelism thereof is less than or equal to 0.02mm, placing the rough in a cold-trimming mould for trimming at cold state until the single-side working allowance is 0.15mm-0.25mm; processing positioning holes with a position tolerance of less than or equal to Phi 0.02m, hear treating again until the rigidities of surface and core meet the requirement, grinding and obtaining the special shaped curved surface stator of the steering pump. The inventive method is characterized by small forming force, good forming quality, high production efficiency and low cost, and the formed parts have high abrasion resistance and fatigue resistance.
Owner:CSIC NO 12 RES INST

Machining method for precision inner cavity thin-wall integral centrifugal impeller of aerospace engine

The invention provides a machining method for a precision inner cavity thin-wall integral centrifugal impeller of an aerospace engine. The machine method comprises the steps of material preparation, blank rough outline turning, semi-fine profile turning, blade type rough milling, natural failure, profile 1 fine milling, drilling, blade type fine milling, blade profile 2 fine milling, clamp repair,dynamic balance, fluorescence inspection and final inspection. According to the machining method for the precision inner cavity thin-wall integral centrifugal impeller of the aerospace engine, in particular to the machining of a centrifugal impeller of a high rotation speed engine used in an aerospace vehicle, an ultra-thin multi-curved surface blade with thickness of 1.2mm can be machined, the blade does not deform during the machining process, the residual height of a hub is ensured, the knife mark in the direction of air flow is machined; meanwhile, the extremely high coaxiality of inner holes in the two end surfaces of the hub and the micron accuracy of the machining of the inner holes in the large end surface of the hub can be ensured, and the requirements of very high dynamic balance, dimensional accuracy and shape and position tolerance of parts can be met.
Owner:黑龙江省机械科学研究院

Thin-walled vane nine-point control variable-allowance milling method based on Newton interpolation

The invention provides a thin-walled vane nine-point control variable-allowance milling method based on Newton interpolation. Modeling is carried out by utilizing a three-dimensional modeling software, and an auxiliary surface and a boundary surface are formed, so that a driving surface is determined by utilizing a section line lofting process. Cutter machining paths are generated according to the driving surface, and the machining allowance of each cutter position point on each machining path is determined by adopting a Newton interpolation method. Finally, vanes are cyclically processed according to symmetrical milling rules. Compared with a traditional longitudinal fixed-allowance cutting and spiral milling method, the thin-walled vane nine-point control variable-allowance milling method has the advantages that technical problems, such as large torsional deformation, low contour precision, poor section position tolerance and difficult error control, in the machining process can be solved; and by adopting a Newton interpolation process allowance fine adjustment method, surface quality can be more comprehensively controlled, and problems, such as large bending deformation, poor section position tolerance and low surface contour precision, in the machining process can be effectively solved.
Owner:NORTHWESTERN POLYTECHNICAL UNIV

Manufacturing method for motor shell body

The invention discloses a manufacturing method for a motor shell body. The method includes the flowing steps: S100, pre-machining a central hole of a motor base; S200, fixedly connecting the motor base with either end cover, taking the axis of the central hole as a standard to machine a circle of an externally connected stopping opening of the fixedly connected end cover, and taking the end face of the motor base as a standard to machine an externally connected stopping opening end face of the externally connected stopping opening of the end cover; S300, fixedly connecting the motor base with the other end cover, taking the axis of the machined circle of the externally connected stopping opening as a standard to machine bearing installation holes of two end covers and a circle of an externally connected stopping opening of the other end cover, and taking the machined end face of the externally connected stopping opening as a standard to machine an end face of the externally connected stopping opening of the other end cover. Compared with the prior art, the manufacturing method for the motor shell body enables the motor shell body to have a high-precision form and location tolerance, an assembled motor can still meet requirements of the high-precision size and the shape position tolerance even under the condition that assembling errors exist in an accumulated assembling process, the repairing rate of the motor shell body is reduced, abrasion of a motor in the running process is reduced, and the service life of the motor is prolonged.
Owner:CSR ZHUZHOU ELECTRIC LOCOMOTIVE RES INST

A method for selecting and matching mechanical parts based on geometrical tolerance and dimensional tolerance is disclosed

The invention discloses a method for selecting and matching complex mechanical products based on genetic algorithm, which comprehensively considers shape and position tolerance and dimension tolerance, through the coding method of complex dimension chain, the assembly problems of complex mechanical products are mapped into mathematical models, assembly accuracy and assembly success rate are used as the evaluation indexes of quality requirements, a comprehensive optimization model of selection and matching under the multi-quality requirements is established, by using the effective characterization form of the measured values of geometrical tolerances in the selection, the optimization model of geometrical tolerances and dimensional tolerances is established, Based on Pareto intensity and density as fitness evaluation criteria of genetic algorithm, the algorithm is improved by introducing the priority of parts and the priority of quality requirement. The method not only realizes the selection and matching of complex mechanical products, improves the success rate of assembly, ensures the assembly accuracy, ensures the dimensional tolerance assembly accuracy, but also effectively reduces the shape and position tolerances of products, and the genetic algorithm with the priority of selection and matching has a better convergence speed.
Owner:XI AN JIAOTONG UNIV
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