1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationBS EN 320:2011Particleboards and fibreboards Determination of resistanceto axial withdrawal of screwsBS EN 320:2011 BRITISH STANDARDNational forewordThis British Standard is the
2、UK implementation of EN 320:2011. It supersedes BS EN 320:1993, which is withdrawn.The UK participation in its preparation was entrusted to T e c h n i c a l C o m m i t t e e B / 5 4 1 , W o o d b a s e d p a n e l s .A list of organizations represented on this committee can be obtained on request
3、to its secretary.This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. BSI 2011 ISBN 978 0 580 71980 6 ICS 79.060.20 Compliance with a British Standard cannot confer immunity from legal obligations.This British Sta
4、ndard was published under the authority of the Standards Policy and Strategy Committee on 31 July 2011.Amendments issued since publicationDate T e x t a f f e c t e dBS EN 320:2011EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 320 April 2011 ICS 79.060.20 Supersedes EN 320:1993English Version
5、Particleboards and fibreboards - Determination of resistance to axial withdrawal of screws Panneaux de particules et panneaux de fibres - Dtermination de la rsistance larrachement des vis selon leur axe Spanplatten und Faserplatten - Bestimmung des achsenparallelen Schraubenausziehwiderstands This E
6、uropean Standard was approved by CEN on 17 March 2011. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
7、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 official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN membe
8、r 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 Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
9、Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: Avenue Marn
10、ix 17, B-1000 Brussels 2011 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 320:2011: EBS EN 320:2011EN 320:2011 (E) 2 Contents Page Foreword 31 Scope 42 Normative references 43 Principles 44 Apparatus .45 Test pieces .55.1 Samplin
11、g .55.2 Dimensions .55.3 Conditioning .55.4 Preparation of test pieces .56 Procedure .66.1 Positioning of test pieces .66.2 Application of the force .76.3 Measurement of maximum load .77 Expression of results 87.1 For a test piece .87.2 For a board .88 Test report 8Bibliography 9BS EN 320:2011EN 320
12、:2011 (E) 3 Foreword This document (EN 320:2011) has been prepared by Technical Committee CEN/TC 112 “Wood-based panels”, the secretariat of which is held by DIN. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at
13、 the latest by October 2011, and conflicting national standards shall be withdrawn at the latest by October 2011. Attention is drawn to the possibility 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
14、 or all such patent rights. This document supersedes EN 320:1993. Compared to EN 320:1993, the following modifications have been made: a) Scope extended to include also particleboards; b) Normative references updated. According to the CEN/CENELEC Internal Regulations, the national standards organiza
15、tions 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, Poland, Portug
16、al, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. BS EN 320:2011EN 320:2011 (E) 4 1 Scope This European Standard specifies a method for the determination of the resistance of fibreboards and particleboards to axial withdrawal of screws. 2 Normative references The fo
17、llowing referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN 326-1, Wood-based panels Sampling, cutting and inspe
18、ction Part 1: Sampling and cutting of test pieces and expression of test results EN ISO 1478, Tapping screws thread (ISO 1478:1999) 3 Principles Face and edge withdrawal of screws are determined by measuring the force required to withdraw a defined screw from the test piece. Edge withdrawal is only
19、determined on boards of 15 mm thickness or more. 4 Apparatus 4.1 Testing machine, which shall be capable of applying in increasing axial load to the underside of the screw head through a suitable stirrup, whilst adequately restraining the test piece at the same time and measuring the maximum load to
20、 an accuracy of 1 %. 4.2 Metal jig. For testing face withdrawal of screws of boards of less than 15 mm thickness, the use of a metal jig with a central boring, which restrains the test piece (see Figure 1), is recommended. BS EN 320:2011EN 320:2011 (E) 5 Dimensions in millimetres Figure 1 Principle
21、of testing face screwholding on boards of 15 mm thickness 5 Test pieces 5.1 Sampling Sampling and cutting of the test pieces shall be carried out according to EN 326-1. 5.2 Dimensions Five test pieces are taken from each sample board. The test pieces shall be square with a side length of (75 1) mm.
22、5.3 Conditioning The test pieces shall be conditioned to constant mass in an atmosphere with a mean relative humidity of (65 5) % and a temperature of (20 2) C. Constant mass is considered to be reached when the results of two successive weighing operations, carried out at an interval of 24 h, do no
23、t differ by more than 0,1 % of the mass of the test piece. NOTE The tests should be carried out not later than 1 h after removal of the test pieces from the conditioning environment. 5.4 Preparation of test pieces After the test pieces have been conditioned, the screws shall be inserted into prebore
24、d pilot holes. Holes shall have a diameter of (2,7 0,1) mm and a depth of (19 1) mm. They shall be drilled perpendicular to the surface of the test piece, located at the midpoints of one face and two adjacent edges (on edges for boards of 15 mm thickness only. For this test, a steel screw, nominal s
25、ize 4,2 mm 38 mm, with a thread no. ST 4,2 according to EN ISO 1478 and a thread pitch of 1,4 mm (see Figure 2) shall be used. The screws shall be inserted into the test pieces in such a way, that (15 0,5) mm of complete thread are embedded in the test piece. For testing face screwholding on test pi
26、eces of 15 mm, insert the screw in such a way that the length of the incomplete thread, y, protrudes on the opposite side of the test piece. BS EN 320:2011EN 320:2011 (E) 6 Dimensions in millimetres Key y length of incomplete thread Figure 2 Parallel shank screw, nominal size 4,2 mm 38 mm, with a th
27、read no. ST 4.2 according to EN ISO 1478, thread pitch: 1,4 mm 6 Procedure 6.1 Positioning of test pieces Mount the test pieces in the testing machine so that the surface under test is not supported at any point closer than 15 mm to the periphery of the embedded part of the screw, and is held perpen
28、dicular to the direction of the force applied to the screw (see Figure 3). For the testing of face screw withdrawal on boards of 15 mm thickness, the metal jig (see Figure 1) shall be used in such a way that the screw is inserted into the boring in the centre of the metal jig, and the test piece is
29、well restrained by the metal jig. BS EN 320:2011EN 320:2011 (E) 7 Dimensions in millimetres Key 1 Stirrup 2 Test piece t test piece thickness F load Figure 3 Screw withdrawal test on boards of 15 mm thickness (example) 6.2 Application of the force An increasing axial force is applied to the undersid
30、e of the head of each screw in turn, through a stirrup incorporating a parallel-sided slot of suitable width to fit easily to the shank of the screw. Apply the axial load to the underside of the screw head at a constant rate of movement of (10 1) mm/min until maximum load is achieved. 6.3 Measuremen
31、t of maximum load Record the maximum load, to the nearest 10 N, sustained by the test piece during the withdrawal test on the face and both edges (edge screw withdrawal for boards 15 mm thickness only). BS EN 320:2011EN 320:2011 (E) 8 7 Expression of results 7.1 For a test piece Separate withdrawal
32、strengths are recorded for the face and edges of the test piece, expressed to 10 N. The edge screwholding value of a test piece is the arithmetic mean of the two results recorded on that test piece. The face screw withdrawal values of a test piece of less than 15 mm thickness shall be expressed in N
33、ewtons per millimetre (N/mm), by dividing the maximum load, in Newton, sustained by the test piece by its thickness, in millimetres, to 1 N/mm. 7.2 For a board Face and edge screwholding values of a board are the arithmetic means of the results of all test pieced taken from that board, expressed to
34、10 N for boards of 15 mm thickness and to 1 N/mm for boards 15 mm thickness. 8 Test report According to EN 326-1. BS EN 320:2011EN 320:2011 (E) 9 Bibliography 1 EN 309, Particleboards Definition and classification 2 EN 316, Wood fibre boards Definition, classification and symbols This page deliberat
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