GB/T 42596.3-2023 Machine tools safety — Presses — Part 3: Safety requirements for hydraulic presses
1 Scope
This document specifies the technical safety requirements and measures to be adopted by persons undertaking the design, manufacture and supply of hydraulic presses which are intended to work cold metal or material partly made up of cold metal.
The presses covered by this document range in size from small high-speed machines with a single operator producing small workpieces to large relatively slow-speed machines with several operators and large complex workpieces.
2 Normative references
The following documents contain provisions which, through reference in this text, constitute provisions 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.
GB/T 3766-2015 Hydraulic fluid power - General rules and safety requirements for systems and their components (ISO 4413:2010, MOD)
GB/T 14048.20 Low-voltage switchgear and controlgear - Part 5-8: Control circuit devices and switching elements - Three-position enabling switches (GB/T 14048.20-2013, IEC 60947-5-8:2006, IDT)
GB/T 15706-2012 Safety of machinery - General principles for design - Risk assessment and risk reduction (ISO 12100: 2010, IDT)
GB/T 16855.1-2018 Safety of machinery - Safety-related parts of control systems - Part 1: General principles for design (ISO 13849-1:2015, IDT)
GB/T 16855.2-2015 Safety of machinery - Safety-related parts of control systems - Part 2: Validation (ISO 13849-2: 2012, IDT)
GB/T 18831-2017 Safety of machinery - Interlocking devices associated with guards - Principles for design and selection (ISO 14119:2013, IDT)
GB/T 42596.1-2023 Machine tools safety - Presses - Part 1: General safety requirements (IEC 16092-1:2017, MOD)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in GB/T 15706-2012, GB/T 16855.1-2018 and GB/T 42596.12023 as well as the following apply.
3.1
restraint valve
device which protects against a gravity fall of the slide/ram
4 List of significant hazards
This clause contains all the significant hazards, hazardous situations and events identified by risk assessment as significant for the machines defined in the scope and which require a specific action to eliminate or reduce the risk.
These hazards are listed in GB/T 42596.1-2023, Table A.1. Additional hazards are listed in Annex A, Table A.1.
5 Safety requirements and/or measures
5.1 General
Hydraulic presses shall comply with the safety requirements and/or protective/risk reduction measures of this clause. In addition, the machine shall be designed according to the principles of GB/T 15706-2012 for relevant but not significant hazards which are not dealt with by this document.
5.2 Basic design requirements
5.2.1 Hydraulic and pneumatic systems — Common features
GB/T 42596.1-2023, 5.2.1 shall apply..
5.2.2 Pneumatic systems
GB/T 42596.1-2023, 5.2.2 shall apply..
5.2.3 Hydraulic systems
5.2.3.1 GB/T 42596.1-2023, 5.2.3 shall apply.
Controlled gravity descent may be a deliberate design feature to facilitate rapid closing of the tools. In such a case, all the oil in the cylinder supporting the slide/ram shall be passed through the main control valve or valves in a redundant and monitored system (see Table 1 and/or Table 2).
5.2.3.2 The circuit shall be protected by pressure limiting valves. These valves shall not be capable of alteration without the use of a tool. Also, they shall be set at a pressure which is no more than 10% higher than the maximum operating pressure.
5.2.3.3 For down-stroking presses, provision shall be made to protect the cylinder and components containing the fluid in the lower part of the cylinder from damage due to pressure intensification. A relief valve used for this purpose shall be direct operated, sealed and locked against unauthorised adjustment, and shall be set at a pressure at least 10% above the maximum system pressure so that it only opens in the case of a fault. The components it protects shall be designed to withstand the pressure at which the valve is set. The relief valve shall be constructed so that, if a single break in the spring occurs, the space between the windings remains less than one wire thickness. The spring shall be guided so as to maintain the function of the relief valve.
5.2.4 Electrical system
GB/T 42596.1-2023, 5.2.4 shall apply.
5.3 Mechanical hazards in the tools area
5.3.1 Major danger zone
GB/T 42596.1-2023, 5.3.1 shall apply.
5.3.2 Safeguarding measures
GB/T 42596.1-2023, 5.3.2 shall apply.
Slow closing speed used in combination with hold-to-run control devices shall not exceed 10 mm/s. The speed shall not be limited by adjustment of variable parameters (see Tables 1, 2 and Annex B). The hold-to-run control device shall consist of a single button/foot-pedal and shall fulfil the requirements of GB/T 14048.20. For foot-pedals, the force shall not exceed 350N for switching from position 2 to position 3.
5.3.3 Other safety requirements
GB/T 42596.1-2023, 5.3.3 shall apply.
5.3.4 Release of trapped persons between the tools
GB/T 42596.1-2023, 5.3.4 shall apply.
Foreword II
Introduction IV
1 Scope
2 Normative references
3 Terms and definitions
4 List of significant hazards
5 Safety requirements and/or measures
5.1 General
5.2 Basic design requirements
5.3 Mechanical hazards in the tools area
5.4 Control and monitoring system
5.5 Tool-setting, trial strokes, maintenance and lubrication
5.6 Mechanical hazards — Other
5.7 Slips, trips and falls
5.8 Protection against other hazards
6 Verification of the safety requirements and/or measures
7 Information for use
7.1 General
7.2 Marking
7.3 Warning
7.4 Instruction handbook
Annex A (Informative) Significant hazards, hazardous situations and protective measures
Annex B (Informative) Examples for hydraulic speed limitation
Annex C (Informative) Interlocking devices associated with guards
Annex D (Normative) The response time of the hydraulic system
Annex E (Normative) Calculation of minimum distances
Annex F (Informative) The connection of the stopping time measurement equipment
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