BS EN 14081-3-2012 Timber structures Strength graded structural timber with rectangular cross section Machine grading additional requirements for factory production control《木结构 带矩形.pdf

1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationBS EN 14081-3:2012Timber structures Strengthgraded structural timber withrectangular cross sectionPart 3: Machine grading; additionalrequirements for factory production controlBS

2、 EN 14081-3:2012 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of EN 14081-3:2012. It supersedes BS EN 14081-3:2005, which is withdrawn.The UK participation in its preparation was entrusted to T e c h n i c a l C o m m i t t e e B / 5 1 8 , S t r u c t u r a l t i m

3、 b e r .A list of organizations represented on this committee can be obtained on request to its secretary.This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. The British Standards Institution 2012Published by BSI

4、 Standards Limited 2012ISBN 978 0 580 71351 4 ICS 79.040 Compliance with a British Standard cannot confer immunity from legal obligations.This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 March 2012.Amendments issued since publicationDate T

5、e x t a f f e c t e dBS EN 14081-3:2012EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 14081-3 January 2012 ICS 79.040 Supersedes EN 14081-3:2005English Version Timber structures - Strength graded structural timber with rectangular cross section - Part 3: Machine grading; additional requirement

6、s for factory production control Structures en bois - Bois de structure section rectangulaire class pour sa rsistance - Partie 3: Classement mcanique - Exigences complmentaires relatives au contrle de la production en usine Holzbauwerke - Nach Festigkeit sortiertes Bauholz fr tragende Zwecke mit rec

7、hteckigem Querschnitt - Teil 3: Maschinelle Sortierung, zustzliche Anforderungen an die werkseigene Produktionskontrolle This European Standard was approved by CEN on 16 December 2011. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving

8、 this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN member. This European Standard exists in three offici

9、al versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the same status as the official versions. CEN members are the national standards bodies of A

10、ustria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Ki

11、ngdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: Avenue Marnix 17, B-1000 Brussels 2012 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 14081-3:2012: EBS

12、 EN 14081-3:2012EN 14081-3:2012 (E) 2 Contents Page Foreword 3Introduction .41 Scope 52 Normative references 53 Terms and definitions .54 Symbols 55 Requirements for the operation, calibration and maintenance of a grading machine .66 Additional requirements for factory production control for machine

13、 controlled systems 66.1 General 66.2 Requirements for strength grades with a characteristic strength level above C30 .67 Additional factory production control requirements for output controlled systems .7Annex A (normative) Requirements for using control planks 8A.1 General 8A.2 Requirements for se

14、lecting the control planks 8A.3 Requirements for the use of control planks for internal factory production control .8A.4 Requirements for the use of control planks for third party factory production control 9Annex B (informative) Additional factory production control requirements for output controll

15、ed systems 10B.1 General . 10B.2 Production control 10Annex C (informative) Example of cusum control charts 13Bibliography . 17BS EN 14081-3:2012EN 14081-3:2012 (E) 3 Foreword This document (EN 14081-3:2012) has been prepared by Technical Committee CEN/TC124 “Timber structures “, the secretariat of

16、which is held by AFNOR. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by July 2012, and conflicting national standards shall be withdrawn at the latest by July 2012. Attention is drawn to the possi

17、bility that some of the elements of this document may be the subject of patent rights. CEN and/or CENELEC shall not be held responsible for identifying any or all such patent rights. This document supersedes EN 14081-3:2005. This document has been prepared under a mandate given to CEN by the Europea

18、n Commission and the European Free Trade Association. Other parts of the series of EN 14081 are: EN 14081-1, Timber structures Strength graded structural timber with rectangular cross section Part 1: General requirements; EN 14081-2, Timber structures Strength graded structural timber with rectangul

19、ar cross section Part 2: Machine grading; additional requirements for initial type testing; EN 14081-4, Timber structures Strength graded structural timber with rectangular cross section Part 4: Machine grading Grading machine settings for machine controlled systems. Compared to EN 14081-3:2005 the

20、following modifications have been made: the additional factory production control requirements for output controlled systems are transferred in Annex B (informative); in Annex A, the requirements for using control planks are updated. According to the CEN/CENELEC Internal Regulations, the national st

21、andards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway

22、, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. BS EN 14081-3:2012EN 14081-3:2012 (E) 4 Introduction Machine grading is in common use in a number of countries. The countries use two basic systems, referred to as output controlled and machin

23、e controlled. Both systems require a visual override inspection to cater for strength-reducing characteristics that are not automatically sensed by the machine. The output-controlled system is suitable for use where the grading machines are situated in sawmills grading limited sizes, species and gra

24、des in repeated production runs of around one working shift or more. This enables the system to be controlled by testing timber specimens from the daily output. These tests together with statistical procedures are used to monitor and adjust the machine settings to maintain the required strength prop

25、erties for each strength class. With this system it is permissible for machine approval requirements to be less demanding and for machines of the same type to have non-identical performance. The machine controlled system was developed in Europe. Because of the large number of sizes, species and grad

26、es used it was not possible to carry out quality-control tests on timber specimens drawn from production. The system relies therefore on the machines being strictly assessed and controlled, and on considerable research effort to derive the machines settings, which remain constant for all machines of

27、 the same type. The acceptability of grading machines and the derivation of settings rely on statistical procedures and the results will therefore depend on the method used. For this reason, this European Standard gives appropriate statistical procedures. The requirements in this European Standard a

28、re based on machines in current use and on future types of machines as far as these can be foreseen. It is recognised that additional clauses or standards may be required if unforeseen developments take place. BS EN 14081-3:2012EN 14081-3:2012 (E) 5 1 Scope This European Standard specifies requireme

29、nts additional to those given in EN 14081-1 for factory production control of machine graded structural timber with rectangular cross-sections shaped by sawing, planing or other methods, and having deviations from the target sizes corresponding to EN 336. 2 Normative references The following referen

30、ced documents are indispensable for the application of this European Standard. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN 408, Timber structures Structural timber and glued laminat

31、ed timber Determination of some physical and mechanical properties EN 14081-1, Timber structures Strength graded structural timber with rectangular cross section Part 1: General requirements EN 14081-2, Timber structures Strength graded structural timber with rectangular cross section Part 2: Machin

32、e grading; additional requirements for initial type testing 3 Terms and definitions For the purpose of this document, the terms and definitions given in EN 14081-1 and the following apply. 3.1 depth dimension perpendicular to the longitudinal axis of a timber beam, in the plane of the bending forces

33、 3.2 grade determining property mechanical or physical property for which a particular value of that property has to be achieved for the material to be assigned to that grade, e.g. bending strength, mean modulus of elasticity and density for the strength classes of EN 338 3.3 indicating property mea

34、surement or combination of measurements made by the grading machine, which are closely related to one or more of the grade determining properties. For grading machines which compute and predict values of the grade determining properties directly from numerous measuring devices, the indicating proper

35、ty may be a predicted value of a grade determining property 3.4 sample number of specimens of timber of one size and representative of one species population 4 Symbols A cusum control parameter B cusum control parameter Bacusum parameter associated with acceptable quality level BS EN 14081-3:2012EN

36、14081-3:2012 (E) 6 Brcusum parameter associated with rejectable quality level Epactual modulus of elasticity measured in a proof load test (in N/mm2) E0,meancharacteristic mean modulus of elasticity parallel to grain (in N/mm2) Fpproof load (in N) K cusum control parameter Larun length in acceptable

37、 region for cusum control Lrrun length in rejectable region for cusum control N cusum control parameter Y cusum control parameter Z cusum control parameter 5 Requirements for the operation, calibration and maintenance of a grading machine 5.1 No modifications that are in conflict with the machine ma

38、nufacturers specification shall be made to the machine. 5.2 Access to all machine adjustments shall be limited to personnel authorised to operate or set up the machine. 5.3 The strength grading machine shall be regularly calibrated in accordance with the manufacturers specification. 5.4 A strength g

39、rading machine shall only be fitted with spare parts equivalent to, or improving upon, the performance of those fitted at the time the machine was assessed by initial type testing. If spare parts are fitted that are not identical to those fitted at the time the machine was assessed by initial type t

40、esting, the machine shall be reassessed to establish their effect on grading accuracy. 5.5 The results of routine service and maintenance to the strength-grading machine and ancillary equipment shall be recorded together with the results of calibration checks. 6 Additional requirements for factory p

41、roduction control for machine controlled systems 6.1 General When grading structural timber in a machine controlled system, grading accuracy shall be monitored, A grading machines dynamic performance shall be controlled by the use of control planks using the procedures given in Annex A. 6.2 Requirem

42、ents for strength grades with a characteristic strength level above C30 During each working shift, two pieces of timber from each grade produced shall be randomly selected and tested for edgewise bending strength as given in EN 408 with the tension edge selected at random and the estimated weakest c

43、ross section positioned where possible within the centre third of the span. The fifth BS EN 14081-3:2012EN 14081-3:2012 (E) 7 percentile value, determined by ranking, of the 100 bending strength values from 50 consecutive shifts shall meet the required bending strength (as given in EN 14081-2). A st

44、rength property other than edgewise bending strength may be used for factory production control as an alternative, provided the relation between the two properties is verified from test data. If the timber is graded to tensile strength classes then this test shall be carried out in tension or bendin

45、g in accordance with EN 408. 7 Additional factory production control requirements for output controlled systems A procedure is given in Annex B and Annex C. BS EN 14081-3:2012EN 14081-3:2012 (E) 8 Annex A (normative) Requirements for using control planks A.1 General When grading structural timber in

46、 a machine controlled system, grading accuracy shall be monitored by controlling the grading machine whilst it is running at production speed. The installation and calibration shall be checked by the use of control planks, using the procedures given in this Annex. The grading process shall be consid

47、ered to be in control when the procedures given in A.3 and A.4 indicate it to be so. If the indicating property or the values measured by the machine to determine the indicating property deviate more than 7 % from the original data, the control plank shall be defined as out of control. Where the mac

48、hine measures in fixed increments then the limit shall be taken as the next increment boundary above 7 %. For each control plank, all data shall be recorded on the datasheet including: a) the date; b) density or weight and dimensions of the control plank; c) grading model (reference to the report nu

49、mber for deriving the grading machine settings); d) indicating property; e) values measured by the machine to determine the indicating property. A.2 Requirements for selecting the control planks Three control planks labelled A, B, and C shall be randomly selected from timber that is typical, in terms of species, size and strength reducing characteristics, of timber to be graded by the particular machine installation. Each control plank shall be indeli