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A numerical approach for 3D manufacturing tolerances synthesis

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A numerical approach for 3D manufacturing

tolerances synthesis

Frédéric VIGNAT, François VILLENEUVE

G-SCOP Laboratory, Grenoble University, 46 avenue Félix Viallet,

38031 Grenoble Cedex 1

frederic.vignat@inpg.fr, francois.villeneuve@hmg.inpg.fr

Abstract: Making a product conform to the functional requirements indicated by the customer suppose to be able to manage the manufacturing process chosen to realise the

parts. A simulation step is generally performed to verify that the expected generated

deviations fit with these requirements. It is then necessary to assess the actual deviations

of the process in progress. This is usually done by the verification of the conformity of

the workpiece to manufacturing tolerances at the end of each set-up. It is thus necessary

to determine these manufacturing tolerances. This step is called "manufacturing

tolerance synthesis". In this paper, a numerical method is proposed to perform 3D

manufacturing tolerances synthesis. This method uses the result of the numerical

analysis of tolerances to determine influent mall displacement of surfaces. These

displacements are described by small displacements torsors. An algorithm is then

proposed to determine suitable ISO manufacturing tolerances.

Keywords: Manufacturing, process, tolerance, synthesis

1. INTRODUCTION

In this paper, a method for qualitative and quantitative tolerance synthesis is

proposed, in the field of manufacturing tolerancing. The qualitative synthesis is defined

by convert functional (or design) tolerances into manufacturing tolerances, i.e., the

tolerances of intermediate working dimensions in part manufacturing processes,

including the identification of the defect parameters to be limited for each

manufacturing set-up and the proposal for corresponding ISO tolerances. The

quantitative synthesis is the determination of a set of values for manufacturing

tolerances making it possible to guarantee the respect of the studied functional

tolerance. The second stage of the quantitative synthesis consists in a choice of values

making it possible to minimize the cost of the selected manufacturing process. This

second stage of optimization will not be treated in this paper.

In the proposed method, the tolerance synthesis comes after the analysis step. The

process has been verified as capable to produce part fitting with the functional

tolerances. It is thus necessary to determine manufacturing tolerances to verify, during

the process execution, the generated defects. These defects have to remain in the

expected range in order to be certain that the produced part is suitable. These tolerances must respect two requirements:

• Only the active surfaces in a set-up will be toleranced in this set-up. Active surfaces are positioned and manufactured surfaces in the set-up.

• For ISO tolerances, positioned surfaces cannot be toleranced but only be a part of the datum system.

The tolerance analysis has been performed by the way of constrained optimisation

leading to the determination of the worst cases. The result of this analysis is the starting

point of the tolerance synthesis:

• First, the study of the influence of each defect parameters on the analysis result allows determining the key surfaces and defects categories (orientation or

position) for each surface.

• Second, the set of defects lead to a proposition of a set of ISO manufacturing tolerances suitable to limit their variation.

• The last step consists in the verification of the set of ISO manufacturing tolerances proposed and the determination of the suitable values.

2. LITERATURE REVIEW

In a close field of our work, [Zhou et al, 2003] use a vectorial model to describe defects

relative to a nominal model. They gather the modeled defects in a state vector named

x(k) for the set-up k. They propose that each manufacturing set-up generates defects

which are classified in three categories:

• Positioning defects that correspond to the positioning of a perfect workpiece in an imperfect part-holder,

• Machining defects that correspond to the defects of the machined surfaces relative to the machine-tool,

• Reference defects corresponding to the positioning defects of an imperfect part in a perfect part-holder.

They then use matrices operators to combine the defects and to determine the state

vector at the end of the set-up x(k+1).

[Benea et al, 2001] propose a graph based model of the manufacturing process in

which the positioning surfaces are underlined with arrows and the machined surfaces by

letters "ij". "ij" means that the designated surface has been machined in step j of the set-

up i. In the manufacturing process, the positioning defects (ε), the machining defects (δ)

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欧盟食品法规(英文版)

欧盟食品法规(英文版)

30.4.2004 Official Journal of the European Union L 139/1 EN I (Acts whose publication is obligatory) REGULATION (EC) No 852/2004 OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL of 29 April 2004 on the hygiene of foodstuffs THE EUROPEAN PARLIAMENT AND THE COUNCIL OF THE EUROPEAN UNION, Having regard to the Treaty establishing the European Community, and in particular Articles 95 and 152(4)(b) thereof, Having regard to the proposal from the Commission 1, Having regard to the Opinion of the Economic and Social Committee 2, Having consulted the Committee of the Regions, Acting in accordance with the procedure laid down in Article 251 of the Treaty 3, 1 OJ C 365 E, 19.12.2000, p. 43. 2 OJ C 155, 29.5.2001, p. 39. 3 Opinion of the European Parliament of 15 May 2002 (OJ C 180 E, 31.7.2003, p. 267), Council Common Position of 27 October 2003 (OJ C 48 E, 24.2.2004, p. 1), Position of the European Parliament of 30 March 2004 (not yet published in the Official Journal) and Council Decision of 16 April 2004. Whereas: (1) The pursuit of a high level of protection of human life and health is one of the fundamental objectives of food law, as laid down in Regulation (EC) No 178/2002 1. That Regulation also lays down other common principles and definitions for national and Community food law, including the aim of achieving free movement of food within the Community. (2) Council Directive 93/43/EEC of 14 June 1993 on the hygiene of foodstuffs 2 laid down the general rules of hygiene for foodstuffs and the procedures for verification of compliance with these rules. (3) Experience has shown that these rules and procedures constitute a sound basis for ensuring food safety. In the context of the common agricultural policy, many Directives have been adopted to establish specific health rules for the production and placing on the market of the products listed in Annex I to the Treaty. These health rules have reduced trade barriers for the products concerned, contributing to the creation of the internal market while ensuring a high level of protection of public health. (4) With regard to public health, these rules and procedures contain common principles, in particular in relation to the manufacturers' and competent authorities' responsibilities, structural, operational and hygiene requirements for establishments, procedures for the approval of establishments, requirements for storage and transport and health marks. 1 Regulation (EC) No 178/2002 of the European Parliament and of the Council of 28 January 2002 laying down the general principles and requirements of food law, establishing the European Food Safety Authority and laying down procedures in matters of food safety (OJ L 31, 1.2.2002, p. 1). Regulation as amended by Regulation (EC) No 1642/2003 (OJ L 245, 29.9.2003, p. 4). 2 OJ L 175, 19.7.1993, p. 1. Directive as amended by Regulation (EC) No 1882/2003 of the European Parliament and of the Council (OJ L 284, 31.10.2003, p. 1). (5) These principles constitute a common basis for the hygienic production of all food, including products of animal origin listed in Annex I to the Treaty. (6) In addition to this common basis, specific hygiene rules are necessary for certain foodstuffs. Regulation (EC) No /2004 of the European Parliament and of the Council of ................. laying down specific hygiene rules for food of animal origin 1 lays down these rules. (7) The principal objective of the new general and specific hygiene rules is to ensure a high level of consumer protection with regard to food safety. (8) An integrated approach is necessary to ensure food safety from the place of primary production up to and including placing on the market or export. Every food business operator along the food chain should ensure that food safety is not compromised. (9) Community rules should not apply either to primary production for private domestic use, or to the domestic preparation, handling or storage of food for private domestic consumption. Moreover, they should apply only to undertakings, the concept of which implies a certain continuity of activities and a certain degree of organisation. 1 See page of this Official Journal. (10) Food hazards present at the level of primary production should be identified and adequately controlled to ensure the achievement of the objectives of this Regulation. However, in the case of the direct supply of small quantities of primary products, by the food business operator producing them, to the final consumer or to a local retail establishment, it is appropriate to protect public health through national law, in particular because of the close relationship between the producer and the consumer. (11) The application of hazard analysis and critical control point (HACCP) principles to primary production is not yet generally feasible. However, guides to good practice should encourage the use of appropriate hygiene practices at farm level. Where necessary, specific hygiene rules for primary production should supplement these guides. It is appropriate for the hygiene requirements applicable to primary production and associated operations to differ from those for other operations. (12) Food safety is a result of several factors: legislation should lay down minimum hygiene requirements; official controls should be in place to check food business operators' compliance and food business operators should establish and operate food safety programmes and procedures based on the HACCP principles. (13) Successful implementation of the procedures based on the HACCP principles will require the full cooperation and commitment of food business employees. To this end, employees should undergo training. The HACCP system is an instrument to help food business operators attain a higher standard of food safety. The HACCP system should not be regarded as a method of self-regulation and should not replace official controls.

中英文翻译(Engineering Tolerance)

中英文翻译(Engineering Tolerance)

英文：

Engineering Tolerance

Introduction

A solid is defined by its surface boundaries. Designers typically specify a

component’s nominal dimensions such that it fulfils its requirements. In reality,

components cannot be made repeatedly to nominal dimensions, due to surface

irregularities and the intrinsic surface roughness. Some variability in dimensions

must be allowed to ensure manufacture is possible. However, the variability

permitted must not be so great that the performance of the assembled parts is

impaired. The allowed variability on the individual component dimensions is called

the tolerance.

The term tolerance applies not only to the acceptable range of component

dimensions produced by manufacturing techniques, but also to the output of

machines or processes. For example , the power produced by a given type of

International Communications in Heat and Mass Transfer

International Communications in Heat and Mass Transfer

7 Numerical simulation of residual stress and

birefringence in the precision injection molding of plastic

microlens arrays Original Research Article

International Communications in Heat and Mass Transfer,

Volume 36, Issue 3, March 2009, Pages 213-219

Can Weng, W.B. Lee, S. To, Bing-yan Jiang

Close preview | Related articles | Related reference work articles

Abstract | Figures/Tables | References

Abstract

Microlens arrays are critical components in the assembly of display devices used

in various telecommunication products. The optical quality of these plastic lenses

is very sensitive to the presence of residual stress. In this paper the distribution of

residual stress and birefringence of these microlens arrays has been investigated.

It is found that maximum residual stress always occurs in the regions near the

外文参考资料及译文

外文参考资料及译文

毕 业 设 计（论 文）外 文 参 考 资

料 及 译 文

译文题目： development and application of combined

machine tool

组合机床的发展与应用

学生姓名： 王斑 学 号： 1021108014

专 业： M10机械设计制造及其自动化

所在学院： 机电工程学院

指导教师： 赵海霞

职 称： 教师

2014年 2 月 25 日

Development and application of combined machine tool

The aggregate machine-tool is take the general part as a foundation, matches by

presses the work piece specific shape and the processing technological design

special-purpose part and the jig, the composition semiautomatic or the automatic special

purpose machine. The aggregate machine-tool selects the method which generally

multiple spindle, the multi-knives, the multi-working procedures, many or the

multi-locations simultaneously process, production efficiency ratio general engine bed