A Method for Integrating Form Errors Into Geometric Tolerance Analysis

2005 ◽  
Author(s):  
Robert Scott Pierce ◽  
David Rosen
Keyword(s):  
Manufacturing Process ◽  
High Speed ◽  
Tolerance Analysis ◽  
Analysis Model ◽  
Geometric Tolerance ◽  
Form Errors ◽  
Product Function ◽  
Component Models ◽  
Insight Into

In this research we describe a computer-aided approach to geometric tolerance analysis for assemblies and mechanisms. This new tolerance analysis method is based on the “generate-and-test” approach. A series of as-manufactured component models are generated within a NURBS-based solid modeling environment. These models reflect errors in component geometry that are characteristic of the manufacturing processes used to produce the components. The effects of different manufacturing process errors on product function is tested by simulating the assembly of these imperfect-form component models and measuring geometric attributes of the assembly that correspond to product functionality. A tolerance analysis model is constructed by generating-and-testing a sequence of component variants that represent a range of manufacturing process capabilities. The generate-and-test approach to tolerance analysis is demonstrated using a case study that is based on a high-speed stapling mechanism. As-manufactured models that correspond to two different levels of manufacturing precision are generated and assembly between groups of components with different precision levels is simulated. Misalignment angles that correspond to functionality of the stapling mechanism are measured at the end of each simulation. The results of these simulations are used to build a tolerance analysis model and to select a set of geometric form and orientation tolerances for the mechanism components. It is found that this generate-and-test approach yields insight into the interactions between individual surface tolerances that would not be gained using more traditional tolerance analysis methods.

A Method for Integrating Form Errors Into Geometric Tolerance Analysis

2007 ◽  
Vol 130 (1) ◽  
Author(s):  
Robert Scott Pierce ◽  
David Rosen
Keyword(s):  
High Speed ◽  
Tolerance Analysis ◽  
Manufacturing Processes ◽  
Analysis Model ◽  
Geometric Tolerance ◽  
Form Errors ◽  
Product Function ◽  
Computer Aided ◽  
Component Models

In this research, we describe a computer-aided approach to geometric tolerance analysis for assemblies and mechanisms. A series of as-manufactured component models are generated within a NURBS-based solid modeling environment. These models reflect errors in component geometry that are characteristic of the manufacturing processes used to produce the components. The effects of different manufacturing process errors on product function are tested by simulating the assembly of imperfect-form component models and by measuring geometric attributes of the assembly that correspond to product functionality. A tolerance analysis model is constructed by generating and testing component variants that represent different manufacturing precision levels. The application of this approach to tolerance analysis is demonstrated using a case study that is based on a high-speed stapling mechanism.

Process Signature Modeling for Tolerance Analysis

2010 ◽  
Vol 10 (2) ◽  
Author(s):  
R. Ascione ◽  
W. Polini ◽  
Q. Semeraro
Keyword(s):  
Concurrent Engineering ◽  
Manufacturing Process ◽  
Tolerance Analysis ◽  
Actual Surface ◽  
Contact Points ◽  
Geometric Tolerances ◽  
Systematic Pattern ◽  
Process Signature ◽  
Nominal Surface

Many well-known approaches exist in the literature for tolerance analysis. All the methods proposed in the literature consider the dimensional and the geometric tolerances applied to some critical points (contact points among profiles belonging to couples of parts) on the surface of the assembly components. These points are generally considered uncorrelated since the nominal surface is considered. Therefore, the methods proposed in the literature do not consider the actual surface due to a manufacturing process. Every manufacturing process leaves on the surface a signature, i.e., a systematic pattern that characterizes all the features machined with that process. The aim of the present work is to investigate the effects of considering the manufacturing signature in solving a tolerance stack-up function. A case study involving three parts has been defined and solved by means of a method of the literature, the variational method, with and without considering the correlation among the points of the same surface due to the manufacturing signature. This work represents a first step toward the integration of the design and the manufacturing in a concurrent engineering approach.

New Tolerance Analysis Model for Normal Mean Shift in Manufacturing Process

2008 ◽  
Vol 594 ◽  
pp. 339-350 ◽  
Author(s):  
Chang Hsin Kuo ◽  
Jhy Cherng Tsai
Keyword(s):  
Normal Distribution ◽  
Uniform Distribution ◽  
Manufacturing Process ◽  
Mean Shift ◽  
Tolerance Analysis ◽  
Analysis Model ◽  
Normal Mean ◽  
The Mean ◽  
The Difference ◽  
Conventional Models

In this paper, we discuss the tolerance analysis methods for the component with a mean shift or drift. A new tolerance analysis model that assumes the mean shift in normal distribution rather than in uniform distribution is proposed. Simulation shows that the difference between the uniform distribution and normal distribution is 1.7%, which can be ignored, for mean shift to one standard deviation (σ). However, the difference becomes significant when the mean shift increases. The difference increases to 5.2% with 1.5σ shift, to 10.9% for 2σ shift, and up to 30.4% for 3σ shift. As normal distribution is a better model for statistical mean shift in manufacturing process, this investigation shows that the proposed tolerance analysis model can give a better model compared to conventional models.

EFFECT OF TRUCK COLLISION ON DYNAMIC RESPONSE OF TRAIN–BRIDGE SYSTEMS AND RUNNING SAFETY OF HIGH-SPEED TRAINS

2013 ◽  
Vol 13 (03) ◽  
pp. 1250064 ◽  
Author(s):  
CHAOYI XIA ◽  
HE XIA ◽  
NAN ZHANG ◽  
WEIWEI GUO
Keyword(s):  
Dynamic Response ◽  
High Speed ◽  
Dynamic Responses ◽  
Illustrative Case ◽  
Analysis Model ◽  
Box Girders ◽  
Running Safety ◽  
High Speed Trains ◽  
Safety Indices

A dynamic analysis model is established for a coupled high-speed train and bridge system subjected to collision loads. A 5 × 32 m continuous high-speed railway bridge with PC box girders is considered in the illustrative case study. Entire histories of a CRH2 high-speed EMU train running on the bridge are simulated when the truck collision load acts on the bridge pier, from which the dynamic responses such as displacements and accelerations of the bridge, and the running safety indices such as derailment factors, offload factors and lateral wheel/rail forces of the train are computed. For the case study, the running safety indices of the train at different speeds on the bridge when its pier is subjected to a truck collision with different intensities are compared with the corresponding allowances of the Chinese Codes. The results show that the dynamic response of the bridge subjected to truck collision loads is much greater than the one without collision, which can drastically influence the running safety of high-speed trains.

scholarly journals To model bolted parts for tolerance analysis using variational model

2015 ◽  
Vol 4 (1) ◽  
pp. 139 ◽  
Author(s):  
Wilma Polini ◽  
Massimiliano Marziale
Keyword(s):  
Contact Surface ◽  
Tolerance Analysis ◽  
Variational Model ◽  
Solid Model ◽  
Functional Requirements ◽  
Form Errors ◽  
Proposed Model ◽  
Mechanical Products ◽  
Planar Contact

Mechanical products are usually made by assembling many parts. Among the different type of links, bolts are widely used to join the components of an assembly. In a bolting a clearance exists among the bolt and the holes of the parts to join. This clearance has to be modeled in order to define the possible movements agreed to the joined parts. The model of the clearance takes part to the global model that builds the stack-up functions by accumulating the tolerances applied to the assembly components. Then, the stack-up functions are solved to evaluate the influence of the tolerances assigned to the assembly components on the functional requirements of the assembly product.The aim of this work is to model the joining between two parts by a planar contact surface and two bolts inside the model that builds and solves the stack-up functions of the tolerance analysis. It adopts the variational solid model. The proposed model uses the simplified hypothesis that each surface maintains its nominal shape, i.e. the effects of the form errors are neglected. The proposed model has been applied to a case study where the holes have dimensional and positional tolerances in order to demonstrate its effectiveness.

A Geometric Model for Tolerance Analysis with Manufacturing Signature and Operating Conditions

2019 ◽  
Vol 9 (3) ◽  
pp. 1-13
Author(s):  
Wilma Polini ◽  
Andrea Corrado
Keyword(s):  
Concurrent Engineering ◽  
Manufacturing Process ◽  
Geometric Model ◽  
Tolerance Analysis ◽  
Operating Conditions ◽  
Geometric Reasoning ◽  
Assembly Sequence ◽  
Turning Process ◽  
Engineering Approach

In this work, a geometric model for tolerance analysis has been carried out. Geometric reasoning has been implemented in the model to simulate the manufacturing process and, then, the assembly sequence. The proposed geometric model has been applied to a case study consisting of two circular profiles due to the turning process, and a hollow rectangular box. The two circular profiles have been assembled inside the box by considering the gravity, and the friction among the parts and the actual points of contact with and without using the manufacturing signature. Matlab® software has been used to implement the geometric model for tolerance analysis. The results have been compared with those obtained by using a literature model with and without considering the manufacturing signature. This work aims to be a first step towards the integration of the design and the manufacturing in a concurrent engineering approach.

Manufacturing Signature for Tolerance Analysis

2015 ◽  
Vol 15 (2) ◽  
Author(s):  
Polini Wilma ◽  
Moroni Giovanni
Keyword(s):  
Sensitivity Analysis ◽  
Manufacturing Process ◽  
Tolerance Analysis ◽  
Variational Model ◽  
Form Tolerance ◽  
Systematic Pattern

Every manufacturing process leaves on the surface a signature, i.e., a systematic pattern that characterizes all the features machined with that process. The present work investigates the effects of considering the manufacturing signature in solving a tolerance stack-up function. A new variational model was developed that allows to deal with the form tolerance. It was used to solve a case study involving three parts with or without considering the correlation among the points of the same surface due to the manufacturing signature. A sensitivity analysis was developed by considering different values of the applied geometrical tolerances.

Margins and Modernity: A Geocritical Approach to Anna Seward's Llangollen Vale

Romanticism ◽  
2019 ◽  
Vol 25 (1) ◽  
pp. 69-80
Author(s):  
Ruth Knezevich
Keyword(s):  
Analytic Approach ◽  
Romantic Era ◽  
Insight Into

The genre of annotated verse represents an under-explored form of transporting romanticism. In annotated, locodescriptive poems like those in Anna Seward's Llangollen Vale, readers are invited to read not only the spatiality of the landscapes depicted in the verse but also the landscape of the page itself. Seward's poems, with their focus on understanding geographical, political, and historical spaces both real and imaginary, provide geocritical insight into poetic productions of the early Romantic era. Likewise, geocriticism offers a fresh and useful – even necessary – analytic approach to such poems. I adopt Anna Seward as a case study in annotated verse and argue that attending to the materiality and paratextuality of her work allows us to access the complexities of her poetry and prose as well as her position within the wider framework of transporting Romanticism.

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