A Guide to Understanding Laser AOPD Systems & Press Brake Applications References to ANSI B Technical Guide LS-CS-M-095

Transcription

1 A Guide to Understanding Laser AOPD Systems & Press Brake Applications References to ANSI B Technical Guide LS-CS-M Action Road, Malaga WA 6090, Australia PO Box 2368, Malaga WA 6944, Australia info@lazersafe.com

2 LS-CS-M-095 A Guide to Understanding Laser AOPD and ANSI B11.3 Document Status Document Reference Code: LS-CS-M-095 Version: 1.04 Released: 14/12/2017 Page i

3 A Guide to Understanding Laser AOPD and ANSI B11.3 LS-CS-M-095 Document Revision History Date Guide Version Software Version Summary of Change 12/12/ Converted to standard format. Page ii

4 LS-CS-M-095 A Guide to Understanding Laser AOPD and ANSI B11.3 Copyright Information Lazer Safe, Press Control Safety System, PCSS, PCSS-A, LZS-LG, LZS-LG-HS, LZS-004, LZS-004-HS, LZS- 005, IRIS, IRIS Plus, RapidBend, RapidBend Plus, RapidBend Ultimate, FlexSpeed, FlexSpeed Plus, SmartLink, BendShield, BendShield Plus, AutoSense, AutoSense Plus, AutoSense Ultimate, Sentinel, Sentinel Plus, Defender, Defender Plus, FoldGuard, PressGuard, LazerGuard and LazerGuard Plus are trademarks of Lazer Safe Pty Ltd. ISaGRAF is a registered trademark of ICS Triplex ISaGRAF Inc. Microsoft and Windows are either registered trademarks or trademarks of Microsoft Corporation in the U.S.A. and / or other countries. The content of this guide is supplied for informational use only, is subject to change without notice and should not be construed as a commitment by Lazer Safe Pty Ltd. Lazer Safe Pty Ltd assumes no responsibility or liability for any errors, inaccuracies or omissions that may appear within this publication. Copyright in this documentation is owned by Lazer Safe Pty Ltd. No part of this document may be reproduced or copied in any form or by any means (graphic, electronic, or mechanical including photocopying, recording, taping, or information storage and retrieval systems) without the written permission of Lazer Safe Pty Ltd. Lazer Safe's copyright in this document is protected by Australian copyright laws (including the Copyright Act 1948 (Commonwealth)) and by international copyright treaties Lazer Safe Pty Ltd. All rights reserved. Page iii

5 A Guide to Understanding Laser AOPD and ANSI B11.3 LS-CS-M-095 Foreword by Mr Robert Appleyard Mr Appleyard is the Managing Director at Lazer Safe Pty. Ltd. He is a member of the ANSI B11.3 sub-committee responsible for drafting the 2012 revision of the B11.3 standard, a long serving member of the European CEN/TC143 committee, and highly regarded by the global press brake community as a leading expert in the fields of press brake safety and safety standards. It is my belief that this document provides a comprehensive explanation that helps the machine builder, their agents, machine owner/operators, and safety authorities to understand the important concepts and points of the B11.3 press brake standard. It is my view that a market, and all of its participants, educated in safety requirements provide the suppliers and buyers of press brakes with a more level market capable of asking the important questions and then also understands how safety and productivity can, and should, work together. Therefore this document is written not from the viewpoint of a product supplier but from my position and experience as a member of committees writing these standards. My involvement in this is:- A member of CEN/TC143 committee that wrote the latest EN press brake standard (applicable to the European Union); I attended all meetings in the production of this standard in Europe from 2001 through A member of the B11.3 committee participating in all meetings in USA from 2008 until completion in Assisting both directly and indirectly in the Japanese standard, the Brazil NR 12, CSA Z142 of Canada and the upcoming standards for China. The EN was the first standard to be updated to include current state-of-the-art guarding systems, specific to press brakes. The fact that it is the first is one of the reasons it took so long. The other reason is that in Europe, to enable consistency, all standards must be formed and written in English then later translated into other languages. As can be imagined this becomes difficult because for most of the European participants in these committees, English is a second, third or fourth language. History A considerable amount of work, expertise and time, went into producing this excellent and up-to-date standard. However due to these language issues it would be fair to say that some of the wording could be clearer. It is also reasonable to say that some commercial interests may exploit this ambiguity to their advantage, without regard for the intent of the standards and the safety implications. As a member of this committee I know the full and true intent of each and every relevant clause and through this document I hope to provide clarity to the readers. An opportunity arose when the B11.3 standard was due for rewriting to reference all the excellent work in the EN Thereby the B11.3 was able to adopt all of the EN strengths and at the same time address any areas lacking clarity that have appeared in practice since the EN was released. Consequently, the B11.3 is written in a very clear and non-conflicting manner using the following advantages; The B11.3 is written In the USA B standard method. That is, to have the prescriptive requirements on the left side and have explanation material on the right hand side of the document. The committee members of B11.3 do not have language interpretation issues. Page iv

6 LS-CS-M-095 A Guide to Understanding Laser AOPD and ANSI B11.3 Having this second go along with these circumstances has given the B11.3 committee a great opportunity to ensure the consistency between EN and B11.3, and also have a very robust, clear and easily understood standard, still to USA specific needs. When creating standards both new construction and existing machines need to be considered. One of the slight problems generally encountered by all ANSI standards (and all World standards) is they must try and provide good guidance for both NEW machines, and OLDER machines that have been in the field for some time. In practice this is not always entirely practicable. When retrofitting new technology to older machines the installer must take extreme care to ensure that installing this equipment does not decrease the safety of the machine or add any additional hazards. The new equipment must be able to function as per the performance and specifications of its operating manual. There may be times when these older machines cannot be brought up to the requirements of the new standards. The installer should evaluate this and ensure that by adding any new components to an old machine that the full machine installation becomes safer overall than its original state. If any new components add to a hazard or introduce a new hazard then these components should not be installed. This is an opinion only and is not a standards requirement. This opinion is aided by the general knowledge of legislation in Europe that tries to deal with these situations. Requirements and legislation in the USA maybe less clear on this. There is some recognition and awareness of this in the forward sub-clauses of the B11.3 on page 8 under effective date, last paragraph. When an ISO standard is eventually produced (a global standard) for press brakes, this standard will have to ensure it covers all major requirements stated in these major standards, such as B11.3 and the EN The B11.3 will be a major contributor along with the EN in the eventual ISO standard. I do hope you can take the time to read this explanatory document and that it is of help to you. Mr Robert Appleyard Managing Director, Lazer Safe Pty. Ltd. Page v

7 A Guide to Understanding Laser AOPD and ANSI B11.3 LS-CS-M-095 Table of Contents 1 About This Guide Document Objectives Disclaimer Document Organisation Related Documentation Guide to Notes, Cautions and Warnings Obtaining Technical Assistance Introduction Detection Capability Muting Special Modes Safe Speed and Speed Monitoring Automatic Overrun Monitoring Automatic Stop Test What is the Safe Stopping Distance Limit? Laser AOPD Selection Checklist Purchasing a Laser AOPD System Expanded Notes Retrofitting Existing Machinery Section 6 - Safe Speed and Speed Monitoring Glossary of Terms Page vi

8 LS-CS-M-095 A Guide to Understanding Laser AOPD and ANSI B About This Guide This chapter contains information about this guide, containing the following elements: Document Objectives. Disclaimer. Document Organisation. Related Documentation. Guides to Notes, Cautions and Warnings. Obtaining Technical Assistance. 1.1 Document Objectives This document is intended to give an overview of the function of close proximity point of operation AOPD (also referred to as Laser AOPD) for press brakes, and as a guide to understanding critical safety requirements of the ANSI B standard for press brakes. 1.2 Disclaimer This document contains information and opinions about Laser AOPD systems, applications and understanding of the ANSI B standard. Where information is provided, Lazer Safe believes that such information is accurate and up to date, but accepts no liability if any information is inaccurate or if information has been omitted. Where opinions are expressed, Lazer Safe personnel hold such opinions in good faith based on the information known to them at the time. Any person reading this document or relying on it must appreciate that other parties may hold opinions which are different to the opinions expressed in this document. This document is not intended to reference any particular brand or model of Laser AOPD system or components. It is recommended that the reader consult the manufacturer of the Laser AOPD system or components for more information and product technical details and specifications to determine compliance with ANSI B This informative guide refers to parts of B but in no way does it replace B The information presented here is provided without prejudice. 1.3 Document Organisation This guide is organised into the following chapters: 1. This chapter. 2. Introduction. 3. Detection Capability. 4. Muting. 5. Special Modes. 6. Safe Speed and Speed Monitoring. 7. Automatic Overrun Monitoring. 8. Laser AOPD Selection Checklist. 9. Expanded Notes. 10. Glossary of Terms. 1.4 Related Documentation This guide should be used in conjunction with the following documents: ANSI B Standard (available for purchase from Page 1

9 A Guide to Understanding Laser AOPD and ANSI B11.3 LS-CS-M Guide to Notes, Cautions and Warnings Note: This symbol indicates helpful information. Caution: This symbol alerts you to situations that could result in equipment damage. Warning: This symbol indicates danger. You are in a situation that could cause bodily injury. Before you work on any equipment, be aware of the hazards involved with electrical circuitry and be familiar with standard practices for preventing accidents. To see translations of the warnings that appear in this publication, refer to the translated safety warnings that accompanied this device. 1.6 Obtaining Technical Assistance Lazer Safe highly recommends to all parties - manufacturers, suppliers and factory operators involved with press brakes, to purchase the ANSI B Standard. For further information on this document or general Laser AOPD enquiries, please customerservice@lazersafe.com detailing your specific questions. Page 2

10 LS-CS-M-095 A Guide to Understanding Laser AOPD and ANSI B Introduction Close proximity point of operation AOPD, or Laser AOPD have been developed for press brakes as an alternative to traditional light curtains. These systems, compared to light curtains are designed to provide the following. A higher level of operator safety. A higher level of machine productivity. Protection against high speed tool collision. Laser AOPD Receiver Mounted to upper ram. Laser AOPD Transmitter Mounted to upper ram. Laser AOPD Protective Zone Created by laser field across length of upper tool Figure 2-1: Laser AOPD System The main difference between Laser AOPD and light curtain systems is that Laser AOPD protects the point of hazard whereas light curtain systems restrict operator access to the point of hazard. Laser AOPDs therefore allow the operator to work within close proximity (15mm) of the point of hazard while the tools close at high speed. This significantly increases the productivity of the press brake and reduces operator fatigue associated with having to continually step in and out of the light curtain while operating the machine. Material Material Laser AOPD - Point of hazard protection Light curtain - Restricted access to point of hazard Figure 2-2 Laser AOPD (left), Light Curtain (right) Page 3

11 A Guide to Understanding Laser AOPD and ANSI B11.3 LS-CS-M-095 As the Laser AOPD protects the point of operation it is important to monitor critical safety functions of the press brake to; ensure the machine operates within strict speed and stopping distance safety limits, ensure the operator is protected at all times, ensure the operation of the machine is prevented at any time should the machine become unsafe and expose the operator to risk of serious injury. The key safety critical aspects for any Laser AOPD include the following. Automatic overrun (stopping performance) monitoring. Speed monitoring. Provide optical protection when the tool opening exceeds 6mm or ensure the closing speed does not exceed 10mm/s. Monitor the position of the material and mute (deactivate) the protective zone relative to the material position. The following sections explain the operation and critical safety aspects of Laser APODs and make reference to the ANSI B Standard. The section of the standard related to Laser AOPD is sub-clause Close proximity point of operation AOPD safeguarding device. Page 4

12 Machine overrun plus tolerance 14mm max Dimension of the protective zone LS-CS-M-095 A Guide to Understanding Laser AOPD and ANSI B Detection Capability According to sub-clause the protective zone must meet the following requirements. Extend across the entire length of the punch (upper tool). Provide protection directly under the tip of the punch within 2.5mm of the bending line. This provides protection directly at the area where the tool tip contacts the material (primary pinch point). Extend forward of the bending line by at least 15mm. This provides a safety distance between the bend line and the operator s fingers/hands. The vertical detection must be a maximum distance of 14mm from the punch tip. This is to prevent an operator s finger being inserted (and undetected) between the punch and the detection zone. Minimum bend line protection +/- 2.5mm from bend line Operator Side 14mm maximum distance from punch tip 15mm minimum distance forward of bend line Figure 3-1: Detection Capability Minimum Requirements Note: Any Laser AOPD system that is mounted to the lower ram or bed of the press brake does not comply with sub-clause and must not be used. Figure 3-2: AOPD Protective Zone Requirements Page 5

13 A Guide to Understanding Laser AOPD and ANSI B11.3 LS-CS-M-095 The vertical distance (14mm) is the maximum allowable gap between the punch and protective zone. The actual vertical size of the protective zone can vary, however it must correspond with the stopping performance of the machine during high speed closing. This is to ensure the punch does not contact a static obstruction. Refer to Section 7 for more details and examples. Page 6

14 LS-CS-M-095 A Guide to Understanding Laser AOPD and ANSI B Muting Muting is the temporary deactivation of the optical protective zone. This is required so the Laser AOPD can provide protection during tool closing (high speed movement), and then after the transition to slow speed, the protective zone can be muted (deactivated) so the closing movement is no longer stopped to allow the punch to contact the material until the completion of the bend cycle. The signal for muting can be provided by the Laser AOPD itself or an external signal (i.e. CNC system). When the protective zone is muted and the tool opening is greater than 6mm then press brake must be restricted to safe speed (sub-clause ). Safe speed is 10mm/s or slower. When safe speed is in effect then the speed must be automatically monitored (sub-clause 8.8). If the Laser AOPD provides optical protection until the opening is 6mm or less then bending speeds in excess of 10mm/s are permitted. This is only possible on press brakes that are capable of multiple speeds including safe speed. There are two important items that must be met to ensure the safety of Laser AOPDs, because of their last line of defence nature. The correct slow speed must be established before the protective field is muted. It is not acceptable to use the point where the mute signal is given to also use this as the point to start slow speed. It takes some time and distance to de-accelerate down to this slow speed from high fall speed. Therefore the slow speed signal must be given before the mute signal, to allow for this de-acceleration distance. This speed must be monitored to ensure that if the speed exceeds 10mm/sec that the cycle is stopped immediately. This is again to ensure that the safety of the whole guarding integration is performing to its designed specifications. Again the principle is that the machine must be fully guarded and only in specific situations can this guarding be replaced by safe speed of 10mm/sec. This speed must be monitored and correct at all times, just as the actual guarding system (that it is temporarily replacing) is monitored. Muting may also occur when the tool opening is greater than 6mm. In this case the optical sensing can only be muted when; the closing speed is 10mm/s or less, the closing speed is monitored and action is taken to prevent operation should the speed exceed 10mm/s. Page 7

15 A Guide to Understanding Laser AOPD and ANSI B11.3 LS-CS-M Special Modes Special modes refer to functions that require portions of the optical protective zone to be blanked, and the tools can still close at high speed (>10mm/s). This includes modes such as box bending where part of the work piece may interfere with a portion of the protective zone. By blanking a portion of the protective zone the cycle can be performed in high speed. When using special modes the following conditions must be met (sub-clause ). The portion of the protective zone that is directly under the punch tip must remain active. This is the primary pinch point and must be protected. This section of the protective zone can be positioned a maximum distance of 2.5mm from the centre line of the punch tip (sub-clause E ) to avoid interference with a work piece side flange (i.e. a box). A clear indication to the operator when the special mode is active. The special mode is automatically deactivated after each power-on of the press brake. For each stroke that requires the special mode blanking function, the operator is required to perform a separate confirming action before blanking of the protective zone is permitted. This would include an extra press of the foot pedal or activation of a separate button or switch. Permanently blanking any part of the protective zone without operator confirmation on every machine cycle is not permitted. Protective zone under the punch tip (+/- 2.5mm) must remain active when closing speed exceeds 10mm/s. Front area of the protective zone can be blanked (with additional conditions applied) to avoid interference with the work piece. Figure 5-1: Special Mode Protection Zone Page 8

16 LS-CS-M-095 A Guide to Understanding Laser AOPD and ANSI B Safe Speed and Speed Monitoring When a Laser AOPD is installed on a press brake there may be certain operations that could interfere with the protective zone. This could include bending awkward shaped material, the use of chains for multi-v die rotation, etc. In this case the protective zone can be muted provided the machine closing movement is restricted to safe speed which is 10mm/s or slower (refer sub-clause ). When safe speed is used then additional safety measures must be implemented. When the press brake is capable of a closing speed in excess of 10mm/s (as is the case with most machines) then continuous monitoring of the closing speed is required. If the Laser AOPD itself does not provide a speed monitoring function then additional systems and/or components must be installed on the press brake to provide the speed monitoring function and the systems and/or components must be compliant with sub-clause 8.3 (system fail safe and control reliability). In the event that the closing speed exceeds 10mm/s when safe speed is active then the closing movement must be stopped (refer sub-clause 8.8). > 6mm Material > 6mm X Material Protective zone active Closing speed can be > 10mm/s Protective zone muted Closing speed must be 10mm/s Figure 6-1: Protective Zone and Speed Monitoring Closing speed of the machine must be constantly monitored to ensure safe operation whenever the protective zone is muted. The closing speed in this situation must not exceed 10mm/s, which is considered to be a safe closing speed. At 10mm/s the closing speed is slow enough so that the operator has time to stop the machine should any part of their body become trapped between the tools therefore preventing serious irreversible injury. It is necessary in some situations for the protective zone to be muted. The most common is when the tools close to the material, and at a pre-defined mute point, the optical sensing must be muted in order to allow the material to be formed. Other situations include bending work pieces where the material obstructs the protective zone before the mute point is reached. In this case the optical sensing needs to be muted and the remainder of the cycle completed with a closing speed of 10mm/s. The speed monitoring device should provide the following functions. Continuously monitor the closing speed when safe speed is active. Initiate a safe stop of the machine if the closing speed exceeds 10mm/s when the protective zone is muted. Not allow machine operation to continue without the operator performing a manual reset action. Page 9

17 A Guide to Understanding Laser AOPD and ANSI B11.3 LS-CS-M-095 When safe speed is used, the machine must have a three position hold to run control. If there is more than one operator then an individual three position hold to run control is required for each operator (refer sub-clause 8.8(a)). A three position hold to run control is a safety foot pedal with three pedal positions. 1 st Position. Foot is off the pedal machine stop. 2 nd Position. Foot is on the pedal machine run (closing movement). 3 rd Position. Foot is pressed all the way down machine stop. The 3 rd position is required so that the operator can quickly stop the machine closing movement in the event of emergency (for example if the operator were to become trapped between the tools). Refer to ANSI B11.19 for additional information. See Section 9.2 for the Expanded Note on Safe Speed and Speed Monitoring. Page 10

18 LS-CS-M-095 A Guide to Understanding Laser AOPD and ANSI B Automatic Overrun Monitoring Automatic overrun monitoring ensures that the machine is, at all times, capable of stopping within a pre-defined safety distance limit whenever a stop command is issued. The reason for this extra automatic requirement above a light curtain installation on a press brake is because Laser AOPD devices are situated at the very last point of safety the dangerous tool at the pinch point - not a distance away as per a simple safety barrier (light curtain). If a failure occurs there is no second chance or the benefit of extra distance away from the dangerous point. It also means that the Laser AOPD must always be active and fault free and always fully responsive to commands given to it. It is critical that the machine can always stop before the punch makes contact with the obstruction, thereby avoiding serious injury. OBSTRUCTION OBSTRUCTION OBSTRUCTION Obstruction detected stop initiated Stop with no contact Dangerous overrun Figure 7-1: Obstruction Detection and Stopping / Overrun Sub-clause of the standard requires; An automatic stopping distance (overrun) monitor. An automatic stop test to be performed at every power-up and periodically. The stop test is to be performed at the fastest operating speed of the press brake. Stopping distance (overrun) monitoring is performed at every closing stop. This is due to the potential of the operators hands being the hazardous zone. When monitoring every closing stop an additional periodic stop test must also be performed automatically every 24 hours. This is the best safety practice and recommended method of monitoring (sub-clause E ) refer NOTE 1. If stopping distance (overrun) monitoring is not performed on every stop (as recommended by the standard sub-clause E ) then a stop test is required to be performed automatically at least every four hours. This is the minimum monitoring requirement and provides the lowest level of safety refer NOTE 2. Some Laser AOPD systems do not have an integrated automatic overrun monitor and require the operator to perform manual overrun tests using a test piece refer NOTE 3. Under sub-clause manual overrun testing is not permitted as a replacement to automatic overrun monitoring. If the Laser AOPD itself does not provide an automatic overrun monitor function then additional safety systems and/or safety components must be installed on the press brake to provide the automatic overrun monitoring function and the systems and/or components must be compliant with sub-clause 8.3 (system fail safe and control reliability). Page 11

19 A Guide to Understanding Laser AOPD and ANSI B11.3 LS-CS-M-095 Note 1: Automatic overrun monitoring on every stop is the safest and least obtrusive method of monitoring. Note 2: If applying the minimum periodic overrun test then the overrun test is performed automatically every four hours, and this will interrupt the machine operation (stop the machine cycle, program, etc.). This method of monitoring provides the lowest level of safety and is the most obtrusive to machine operation. Note 3: Manual overrun testing involves the use of a plastic test piece. The test piece is placed on the die to create a static obstruction. The machine is operated in high speed so the Laser AOPD detects the test piece and triggers a stop in closing movement. The test piece is used as a visual indicator to verify that a) the closing movement stops before contact is made and b) the overrun is within a safe limit. This type of manual test is conducted by the machine operator at regular daily intervals (i.e. start of shift, after tool change, periodically, etc). In the event that a manual overrun test fails it is the responsibility of the operator to take the appropriate corrective action. The test is solely reliant on the machine operator and in reality is rarely or never performed. This poses significant risk to the operator as the machine may not be capable of stopping within a safe distance and this could remain undetected. For this reason B does not allow the substitution of manual overrun testing in place of automatic overrun monitoring. All Laser AOPD systems must have automatic overrun monitoring, or provide this function through additional safety components. This is to ensure the machine is always in a safe operating condition. Some Laser AOPD manufacturers may require its devices to still incorporate manual overrun testing in addition to the automatic overrun monitoring required under the standard. In these cases the manufacturer must provide specific instructions in their documentation. This manual test can also be used to set and check placement of the protection zone relative to the tool tip as detailed in sub-clause and annex D. 7.1 Automatic Stop Test This test must be automatically initiated by the system on power-up and performed periodically as stated above. When the test is performed the operator will press the pedal to start the tools closing at maximum fast closing speed. The system will initiate a stop automatically and the stopping distance is measured. If the measured stopping distance is less than the safe stopping distance limit then the operator can press the pedal again to continue machine operation. If the measured stopping distance is greater than the safe stopping distance limit then the system must prevent further closing movement and require a manual reset action. The fault must be rectified before normal operation can continue. This would involve an automatic stop test to verify the machine can stop within the safe stopping limit. 7.2 What is the Safe Stopping Distance Limit? The safe stopping distance limit must correspond to the height of the detection zone and be positioned relative to the punch so that when a static object is detected the punch should not touch the object. This stopping distance must be set in to the device and must suit the system design and mounting method to the press brake. Page 12

20 10mm 5mm min Machine overrun plus tolerance 14mm max Dimension of the protective zone LS-CS-M-095 A Guide to Understanding Laser AOPD and ANSI B11.3 Figure 7-2: Stopping Distance Limit Dimensions The overall vertical dimension of the protective zone plus the distance from the punch tip must correspond with the actual overrun of the press brake at maximum closing speed. This vertical dimension must also include a tolerance so that if a static obstruction is detected 10mm above the surface of the material, the tool must stop with a clearance of at least 5mm from the obstruction (sub-clause ). OBSTRUCTION Material OBSTRUCTION Material Tools closing toward static obstruction 10mm from material surface. Tool stopped with minimum 5mm clearance Figure 7-3: Stopping Distance Additional Tolerance Warning: The overrun setting for the Laser AOPD MUST NOT be set lower than the overrun distance of the machine at maximum closing speed. Failure to do so is in DIRECT VIOLATION of the standard and will reduce the safety level of the machine that could result in an accident leading to SERIOUS INJURY or DEATH and machine operator PENALTIES AND/OR LEGAL ACTION. Configuring the Laser AOPD with a FALSE overrun setting in order to decrease the machine speed change point is DANGEROUS and could result in an accident leading to SERIOUS INJURY or DEATH and machine operator PENALTIES AND/OR LEGAL ACTION. Page 13

21 A Guide to Understanding Laser AOPD and ANSI B11.3 LS-CS-M Laser AOPD Selection Checklist Before purchasing a Laser AOPD for retrofit to an existing press brake, or purchasing a new press brake with a Laser AOPD factory fitted, you should ask your supplier if the following safety critical criteria are met. Automatic Overrun Monitoring Notes Sub-Clause Compliant? Must automatically monitor the stopping distance at: Every power-up Every stop and intervals not to exceed 24 hours; or automatically every 4 hours Manual overrun testing is not permitted (i.e. Use of a test piece/tool) E NO YES Speed Monitoring Notes Sub-Clause Compliant? To monitor that the speed does not exceed 10mm/s when the protective zone is muted and safe speed is used. 8.8 NO YES Protective Zone Notes Sub-Clause Compliant? Dimension of the protective zone and positioning relative to the tool and the overrun of the machine. Correct set-up and adjustment of the protective zone E E E Figure A20 NO YES Design and Construction Notes Sub-Clause Compliant? Fail safe and control reliability of the system and any additional components. 8.3 NO YES Special Modes (i.e. Box Bending) Notes Sub-Clause Compliant? Separate operator action (i.e. extra foot pedal press) is required on every blanking stroke. Protective zone under the punch tip must remain active. Clear indicator to operator when mode is active. Special mode automatically deactivated after system power on E NO YES Page 14

22 LS-CS-M-095 A Guide to Understanding Laser AOPD and ANSI B11.3 Muting and Visual Indicators Muting is only possible when; Tool opening is 6mm or less; or Speed is restricted to 10mm/s and monitored. Visual indicators present (i.e. mute lamp) 8.1 Purchasing a Laser AOPD System There are two ways to purchase a Laser AOPD system. Notes Sub-Clause Compliant? E E The first is when you purchase a new press brake that will have the Laser AOPD factory fitted by the press brake manufacturer. Press brakes that are imported from outside the US may not have an ANSI B compliant Laser AOPD system. There are many Laser AOPD systems available in the international market, and many of these systems will not comply with the standard or may be supplied and/or installed in a non-compliant fashion. The second is purchasing a system to be retrofitted to an existing press brake. There are two components to a retrofit Laser AOPD system; the system itself, the integration of the system to the press brake. It is important to select a Laser AOPD system that is fully compliant with the standards, but it is equally as important to have it integrated into the machine either by the press brake manufacturer, or in the case of a retrofit application, by an integration engineer who has specialist knowledge of the Laser AOPD system, the ANSI B standard and press brake applications. See Section 9.1 for the Expanded Note on retrofitting Laser AOPD systems to existing machinery. NO YES Page 15

23 A Guide to Understanding Laser AOPD and ANSI B11.3 LS-CS-M Expanded Notes 9.1 Retrofitting Existing Machinery When retrofitting new technology to older machines the installer must take extreme care to ensure that installing this equipment does not decrease the safety of the machine or add any additional hazards. The new equipment must be able to function as per the performance and specifications of its operating manual. There may be times when these older machines cannot be brought up to the requirements of the new standards. The installer should evaluate this and ensure that by adding any new components to an old machine, that the full machine installation becomes safer overall than its original state. If any new components add to a hazard, or introduce a new hazard, then these components should not be installed. This notation is an opinion of this document only and is not a standards requirement. This opinion is aided by the general knowledge of legislation in Europe that tries to deal with these situations. Requirements and legislation in the USA maybe less clear on this. Application of ANSI B in an existing machine retrofit application is referred to in the standard on page 8 as follows. The Subcommittee recommends that users evaluate whether existing machinery and machinery systems have acceptable risk within 30 months of the approval date of this standard using generally recognized risk assessment methods. If the risk assessment shows that modification(s) is necessary, refer to the requirements of this standard to implement risk reduction measures (protective measures) for appropriate risk reduction. 9.2 Section 6 - Safe Speed and Speed Monitoring The B11.3 standard that preceded this latest version did not contain a section to detail any requirements for safe speed (10mm/second). This meant that in practice there was no explanation or requirements on how light curtains could operate a bending procedure when obstructed in any manner by the material to be formed. This abnormality needed to be addressed in the new B11.3. Safe speed is protection for the operator when protection is not provided by the laser AOPD system or light curtain, i.e. after the optical system is muted (deactivated at the muting point) for the bending operation to occur. Also, if a part obstructs the protection of the optical system above the normal muting point, then the system can be put into safe speed for this part and operation. This safe speed must be automatically monitored so as to not exceed 10mm/s (as explained in Section 6) and for the machine closing movement to be stopped if this limit is exceeded. To insert these new safe speed requirements into B11.3 the committee drew on experience with this requirement in Europe and its corresponding EN12622 standard. This European standard also reflected the current state of the art for Europe with requirements for 3 position foot pedals/switches. To help the introduction of these new requirements for safe speed into B11.3, and to help OHSA understand and accept this necessity and process in the standard, the committee decided to tie this new safe speed operation to a requirement to also use the additional safety for general machine use, provided by 3 position foot pedals. This was seen as a further move of the B11.3 standard to current world state of the art for new machine construction. However, one of the slight problems generally encountered by all ANSI standards (and all world standards) is they must try and provide good guidance for both new machines, and existing machines that have been in the field for some time. Therefore, when retrofitting any guarding system (laser AOPD, light curtain, etc) that uses the safe speed feature then a 3 position foot pedal should be incorporated as well (as detailed in Section 6). Page 16

24 LS-CS-M-095 A Guide to Understanding Laser AOPD and ANSI B Glossary of Terms Close proximity point of operation AOPD AOPD Active Opto-electric Protective Device. Beam Main reciprocating press brake member that normally holds the punch on a down-stroking press brake, and which normally holds the die on an up-stroking press brake. Blanking Bypassing a portion of the sensing field of a presence-sensing safeguarding device. A safeguarding device with a sensing field located within the point of operation which provides protection from crushing hazards occurring at closing tools by utilizing collimated light, and monitored relevant to the stopping distance of the machine. Muting The automatic temporary bypassing of any safety-related function(s) of the control system or safeguarding device. Overrun Movement (distance) of the beam past a defined stopping point. Overrun monitoring device Device which provides a signal to inhibit further complete stroke when the overrun exceeds the pre-set limit(s). Protection zone (Close proximity point of operation AOPD). The area under the upper die where an object of 14 mm or larger must be detected. Ram See Beam. Safe Speed A safeguarding method that requires the press brake to operate at or below a maximum speed, at which the operator has time to take action. Tools Term for the combination of punch (upper tool) and die. Page 17