Technical Safety Requirements for the Press Brake

Introduction
1. The standard is established in accordance with the requirements of GB/T 16755-1997 Safety of Machinery-Rules for the Drafting and Presentation of Safety Standard. The standard is a Class C safety standard.
2. The standard puts forward basic safety requirements for the design, manufacturing, and use of the press brake.
3. The standard is not equivalent to the American National Standard of ANSI Bll.3-1993 Machine Tool-The Safety Standard Requirements for the Construction, Care, and Use of Press Brakes.
4. The standard came into effect on 1 March 2000.
5. The standard was proposed by and is under the jurisdiction of the National Technical Committee on Forging Machinery of Standardization Administration of China.
6. The standard was drafted by the Ji'nan Casting and Forging Machine Research Institute and Huangshi Forging Press Machine Tool Company.
7. The major drafters of the standard are Liqiang Ma and Guohuo Shang.

1. JB 10148-1999 Technical Safety Requirements for the Press Brake
Applications

The standard provides the safety requirements for the design, manufacturing, and use of the press brake. The standard is applicable to the press brake which serves within its intended life span.

2. Quoted Standards
The following standards contain provisions which, through reference in this text, constitute provisions of this standard. At time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below.

GB 2893-1982 Safety Color
GB 2894-1996 Safety Mark
GB/T 3766-1983 General Technical Requirements for the Hydraulic System
GB 5083-1999 General Rules for Designing the Production Facilities in Accordance with Safety and Health Requirements
GB/T 5226.1-1996 Industrial Electro Mechanical Equipment Section I: General Technical Requirements
GB/T 6527.2-1986 General Code of Safety Color
GB/T 6576-1986 Lubrication System of Machine Tool
GB/T 7932-1987 General Technical Requirements for Pneumatic System
GB/T 14775-1993 General Ergonomics Requirements for Manipulators
GB/T 14776-1993 Ergonomics Principles for Determining Dimensions of Work Places in Manufacturing Areas and the Dimensions
GB/T 15706.1-1995 Safety of Machinery-Basic Concept, General Principles for Design-Part 1: Basic Terminology, Methodology
GB/T 15706.2-1995 Safety of machinery-Basic Concepts, General Principles for Design-Part 2: Technical Principles and Specifications
GB/T 16251-1996 Ergonomics Principles in the Design of Work Systems
GB 16754-1997 Safety of Machinery-Emergency Stop-Principles for Design
GB/T 16855.1-1997 Safety of Machinery-Safety-Related Control Parts of Control Systems-Part 1: General Principles for Design
GB/T 16856-1997 Safety of Machinery-Principles for Risk Assessment
GB 17120-1997 Technical Safety Requirements for Metal Forming Machinery
JB/T 1829-1997 General Technical Requirements for Metal Forming Machinery
JB/T 3623-1984 Metal Forming Machinery-Noise Measurement Method
JB/T 9954-1999 Hydraulic system of forging machinery Cleanness
JB 9976-1999 Noise Limit of the Press Brake and Folding Brake

3. Definitions
The following definitions and those established by GB/T 15706.1 and GB 17120 are applicable to this standard.

Machine Tool Danger Zone
The area between the upper and lower dies where relative motion takes place as well as the area where the workpiece is processed.

4. Main Risks
Risk analysis should be performed according to the requirements of GB/T 16856 and GB/T 15706.2 on the press brakes to which the standard is applicable. Possible dangers include:

4.1 Mechanical Dangers
4.1.1 In the machining process, risk of crushing, accidental shearing, and impacting might occur between the top and bottom blades.
4.1.2 The moving parts of the press brake like the movable ram may accidentally fall down under the influence of gravity or due to control failure, resulting in the danger of crushing and impacting.
4.1.3 In the working process, the moving parts like the back gauge, adjustment device, chain drive, and belt drive may cause the risks of crushing, entanglement, drawing-in or trapping, and impact to the human body.
4.1.4 Stab or puncture wounds might be caused by the sharp, pointed machine parts.
4.1.5 During the operation of moving parts like the flywheel and mould, the parts may be shaken loose, shaken off, cracked, broken, or thrown out, causing impact and projection hazards.
4.1.6 Ejection hazard might occur due to the high pressure fluid.
4.1.6.1 The maximum operating pressure of the hydraulic or pneumatic system is beyond its rated operating pressure, resulting in unexpected hazard.
4.1.6.2 Ejection hazard might arise from the leakage of hydraulic system or pneumatic system.
4.1.7 During the machine assembly, repair, or maintenance, operators might accidentally fall off. Crush or collision hazard might also occur due to the narrow operating space or inconvenient operation conditions.

4.2 Electrical Hazard
4.2.1 Direct contact with the exposed live parts or parts which have become live due to fault conditions like insulation failure, resulting in electric shock, fire, or burning hazards.
4.2.2 Electric overload leads to fire or burning hazard.

4.3 Hot Hazard  
Contact with the hot parts like the arrester brake, clutch, and hydraulic system results in burning or scalding injuries.

4.4 Noise and Vibration Hazard 
4.4.1 Loud noise of the press brake might cause the risk of hearing loss, tinnitus, fatigue, depression, and interruption of audible signal.
4.4.2 In the working process, long-duration machine vibration might lead to operators' physiological disorder.

4.5 Hazards Caused by Materials and Substances
Impact, stabbing, or puncturing hazard may occur when bending the workpiece.

4.6 Hazards Generated by Neglecting Ergonomic Principles
4.6.1 Neglecting ergonomic principles might provoke incorrect operation and excessive tension during operation.
4.6.2 Lack of operating coordination when two or more operators are using the machine.

4.7 Hazards Generated by Ineffective Energy, Damaged Parts, or Other Malfunction.
4.7.1 Function loss of the electrical system results in the machine malfunction.
4.7.2 Failure of control elements may cause machine malfunction.
4.7.3 Poor resistance to electromagnetic interference of the electrical and numeric control system brings about abnormal operation of the machine.
4.7.4 Pressure loss causes uncontrolled movement.
4.7.5 Possible presence of foreign matters like scale cinder, bur, and moisture in the hydraulic and pneumatic pipeline also poses a problem which might result in mechanism failure or human body injury.
4.7.6 The center of gravity offset might affect operational stability in the machine assembly or transport process. This might result in accidental tip-over or uncontrolled movement.

4.8 Hazards Generated by Inappropriate Safety Measures
4.8.1 Lack of reliable safety device incurs hazards.
4.8.2 Lack of reliable energy cutting device results in hazards.
4.8.3 Lack of reliable emergency stop device brings about dangers.
4.8.3 Lack of safety adjustment or repair accessories might also lead to danger.

5. Safety Requirements and Measures
5.1 General Requirement

5.1.1 The design of the press brake and its parts and components must meet the requirements of this standard as well as the GB5083, GB/T15706.1, GB/T15706.2, and GB17120.
5.1.2 The press brake must be designed with an aim to eliminate or reduce risk. Risks that can be avoided completely via applying reasonable design or safety device should not be left unsolved.  
5.1.3 Instruction for Use can only be employed to warn users of the risks which can not be completely avoided or effectively reduced even if all the possible designs or safety measures are applied. The Instruction for Use can not be used to warn users of the design defect.
5.1.4 The press brake should be designed in accordance with ergonomic principle. It should be designed with an aim to reduce the labor burden and operating tension of the operator. The product should meet the requirements of GB/T16251, GB/T14776, and other relative standards.
5.1.5 The mechanical strength, rigidity, and operational stability of the press brake should meet the job requirements. There should be no possibility of machine damage within the intended use life limit, providing that users operate the machine in strict accordance with the operating rules. The main parts need to be inspected and examined if necessary.
5.1.6 Some machine parts may be shaken loose, damaged, or drop down. The moveable ram, for example, may accidentally fall off from the machine body. In such case, effective safety measures should be taken, such as installing balance device or stop device.
5.1.7 The accessible parts of the machine, including the ancillary devices which are installed onto the parts, should not contain sharp edges or points, bulge, or any openings that might cause the danger of scratch to the human body, under the condition that the press brake function normally without these designs.
5.1.8 The press brake should be designed with an aim to minimize the dangerous effects of the moving parts.
5.1.9 Except the operation danger zone, other operation areas that conceive potential dangers, such as collision, crushing, drawing-in, machine parts being thrown out, or liquid ejection, should be fitted with safety devices according to the specific characteristics of the dangers.
5.1.10 While working in a danger zone or other operating areas that conceive dangers, such as during the assembly, adjustment, commissioning, repair, and lubrication process, operators need to take pre-active measures and use spare tools to control power source and provide operational security if the safety devices are out of use.
5.1.11 The high-speed rotation parts like the flywheel should be put through static balancing or dynamic balancing test. The residual amount of unbalance should meet the requirement of JB/T 1829-1997: 3.5.5 standard.
5.1.12 The press brake should be supplied with the work platform, ladder, and railings. The ancillary equipment should meet the requirement of GB17210-1997:6 standard.
5.1.13 Screws, nuts, pin, and other fasteners might be shaken loose or fall off, resulting in component shifting or dropping off. Therefore, effective measures should be taken to prevent loosening.
5.1.14 The spring installed on the press brake should meet the requirement of GB17120-1997:17.2 standard.
5.1.15 When operators need to assemble, disassemble, or transport the press brake and its components and parts, be aware of the following requirements:
1. Reliable safety measures need to be taken in the machine assembly and transfer process to prevent it from tipping over due to the shifting of center of gravity.
2. For the heavy, clumsy machine parts, including the moveable ram, mould, and oil cylinder, lifting holes or pillars might be supplied in order to ensure the operators' safety.
3. The press brake should allow convenient adjustment and ensure operational safety.
5.1.16 The press brake should be designed with the pressure overload protection device based on the machine's structural characteristics. The protection device should meet the requirement of GB17120-1997:9.2 standard.
5.1.17 Stop device needs to be fitted at the rear zone of the press brake in order to prevent working staff from entering that area.
5.1.18 Proper safety monitoring device needs to be installed so as to monitor the operating status.
5.1.19 Manufacturers need to specify the operating methods of the adjustment mechanism.
5.1.20 The ancillary adjustment mechanism needs to be interlocked with the moveable ram.
5.1.21 Asbestos materials should not be used in the making of the friction plate.
5.1.22. Effective measures should be taken to prevent emission of harmful oil mist from the pneumatic system.
5.1.23 There should be signals indicating the operators or effective measures to prevent damages to the workpiece.

5.2 Drive System and Operational Control System
5.2.1 Drive System

5.2.1.1 The drive system of the press brake should meet the requirement of GB 17120-1997:5.
5.2.1.2 The exposed part of the drive system which might conceive potential dangers need to be safeguarded. The safety device should be placed in a proper position to ensure that human body should not be caught or clamped between the device and moving parts.
5.2.1.3 There should be obvious turn indicating signals for the one-way rotary parts.
5.2.1.4 When the moveable ram which is performing reciprocating movement is suddenly stopped, its over drop distance should meet the requirement of relative standards or technical documents.

5.2.2 Operational Control System
5.2.2.1 The safety parts of the control system need to be designed in accordance with the requirement of GB/T 16855.1.
5.2.2.2 The operational control system should comply with the standard of GB17120-1997:10.
5.2.2.3 The friction clutch and brake need to comply with the requirements listed in the Chapter 6 of the GB17120-1997 standard.
5.2.2.4 The surface temperature of the friction clutch and brake needs to be up to the required standard listed in the related technical documents.
5.2.2.5 The pressure brake must be provided with single-stroke operational procedure.
5.2.2.6 The changer-over switch is used to control and alter the working procedure. The switch should be equipped with locking key.
5.2.2.7 The press brake must be equipped with movable buttons or foot pedals.
5.2.2.8 Emergency Stop Button 
5.2.2.8.1 The press brake must be equipped with the emergency stop button. The design of the button should comply with standard of GB/T 15706.2-1995.6.11 and GB16754.
5.2.2.8.2 At least two emergency buttons need to be set in two or more different locations.
5.2.2.9 The interlocking mechanism of the operational control device.
If there are various types of control devices installed in different locations of the press brake, then the machine can only be controlled by one single type of control device or the control device in one single location at each time, except during the emergency stop.

5.3 Manually-Operated Press Brake
5.3.1 The manually-operated press brake is controlled by a hand lever or foot pedal. Without manual operation, the machine cannot be started.
5.3.2 Return stroke of the moveable ram must be initiated by activating the hand lever or foot pedal, or by an independent return mechanism such as the spring.
5.3.3 The manually-operated press brake must incorporate an interlocking safeguard to prevent accidental pressing of the foot pedal or hand lever.

5.4 Electrical, Hydraulic, Pneumatic, and Lubricating System
5.4.1 General Requirement

5.4.1.1 The electrical, hydraulic, pneumatic, and lubricating system should function as required.
5.4.1.2 The pipes should not be used as the stair case, foot pedal, or as support to other parts.
5.4.1.3 The pipes must be fixed at both ends. More fixing points need to be added to the pipeline in order to ensure a secure fastening. The spacing between two fixing points should comply with the requirements of related standards. Pipeline damage caused by thermal expansion should be avoided.
5.4.1.4 Fasteners, connecting pieces, and other parts should not be welded onto the pipeline.
5.4.1.5 Incorrect pipeline connection might lead to hazard. In such case, the pipeline should be marked to warn operators.
5.4.1.6 The break-off or recovery of power supply or pressure oscillation shall not cause hazard to the electrical, hydraulic, or pneumatic system.
5.4.1.7 The elements or pipeline segments should be distributed properly to allow easy assembly, adjustment, repair, and disassembly.

5.4.2 Electrical System
5.4.2.1 The press brake must be properly designed to avoid electrical hazard. Its electrical system should meet the requirements of GB/T 5226.1.
5.4.2.2 The anti-interference performance of the electrical and numerical control system should comply with the requirements of relative standard

5.4.3 Hydraulic and Lubricating System
5.4.3.1 The hydraulic drive system of the press brake should be designed in strict accordance with the safety requirements of GB/T 3766 standard.
5.4.3.2 The hydraulic drive system needs to be strictly designed in order to ensure no hazard, even in the event of internal fluid leakage or severe fluid pressure loss.
5.4.3.3 There should be no foreign matters left in the pipeline, such as the scale cinder, burrs, and cuttings. Effective measures should be taken to keep the hydraulic system clean and tidy. The cleanness of the system should comply with the requirements of JB/T 9554.
5.4.3.4 Safeguard devices need to be installed onto the high pressure hose in the operating area.
5.4.3.5 The hydraulic system must incorporate safety devices to prevent hydraulic pressure overload.
5.4.3.6 When the hydraulic pump starts, operators need to push the operation button to allow the moveable ram to cycle.
5.4.3.7 In the normal operating conditions, temperature at the inlet port of the oil tank should be kept below 60℃.
5.4.3.8 The conditions of lubricating system should comply with the requirements of GB/T 6576.

5.4.4 Pneumatic System
5.4.4.1 The pneumatic system should be designed in accordance with the standard of GB/T 7932.
5.4.4.2 Steam separator should be fitted to the pneumatic system. Oil-mist lubricator is adopted to ensure successful performance of the control system.
5.4.4.3 Gas emission process should cause no danger.

5.5. Noise and Vibration
5.5.1 Measures should be taken to minimize the noise hazard that might be caused by the electromotor, hydraulic pump, and mechanical transmission system.
5.5.2 Noise-reduction measures should be taken to decrease the amount of noise emitted by the exhaust of the pneumatic system, such as installing muffler.
5.5.3 The noise level should comply with the JB 9976 noise-emission standard. Noise measurement method should be in strict accordance with the requirements of JB/T 3623.
5.5.4 Effective measures should be taken to reduce the vibration. Prior to operation, the machine needs to be fixed tightly to the ground by the foundation bolts.

5.6 Ergonomics
The operating mechanism should meet the ergonomic requirements listed in the GB/T 14775, GB/T 14776, and GB/T 16251.

5.7 Safeguard in the Danger Zone
5.7.1 Safeguard Principles
At least one proper safeguard device should be set in the danger zone as well as at the inlet throat of the press brake in an effort to prevent mechanical hazard.

5.7.2 Safeguard Device
The safeguard device should both include the safety device and guard device.
5.7.2.1 Guard Device
According to the related safeguard requirements, the guard device of the press brake is available in four types: fixed, moveable, adjustable, and interlocking types.
5.7.2.2 Safety Device
The safety device comes in two types: two-hand control type such as the two-hand button and automatic stop type such as the light-type safety device.

5.7.3 Requirements for the Safeguard Device of the Press Brake
5.7.3.1 Requirements for the Guard Device of the Press Brake
The guard device of the press brake should be designed and manufactured in compliance with the requirements listed in the GB/T 15706.2-1995:4.2.1, GB/T 15706.2-1995:4.2.2, and GB/T 15706.2-1995:4.2.4.
5.7.3.2 Requirements for the Safety Device of the Press Brake
The safety device of the press brake should be designed and manufactured in compliance with the requirements listed in the GB/T 15706.2-1995: 4.2.3.
5.7.3.2.1 The design and manufacturing of the two-hand control button should meet the requirements of GB 17120-1997:10.5.
5.7.3.2.2 The design and manufacturing of the light-type safety device should meet the regulations listed in the GB17120-1997:13.3.3.

5.7.4 Installation of the Safeguard Device
5.7.4.1 There must be a safeguard device set in the operating danger zone.
5.7.4.2 There must be a guard device set at the inlet throat of the press brake. The device should be detachable.
5.7.4.3 The safety distance between the safeguard device and danger zone should be set in accordance the requirements listed in the GB/17120-1997:13.3.4.

6. Inspection, Testing, and Commissioning of the Safeguard Performance
The inspection, testing, and commissioning of the safeguard performance of the press brake should be carried out with reference to the following methods, in order to check where the safeguard devices have been designed in compliance with the safeguard requirements and measures mentioned in Chapter 5. In case that one method fails to accomplish the inspection, another method should be adopted. For each item of safeguard requirement or measure, at least one method should be used. If there are multiple inspection methods that can be used in terms of one safeguard requirement or measure, then all the results of the said methods should be used to judge whether the safeguard device meets this safeguard requirement or measure. Any negative inspection result would lead to the judgment that the safeguard device does not comply with that safeguard requirement or measure.

6.1 Function Testing
Through the function testing, we can know whether one safeguard device meets the requirements mentioned in Chapter 5. If the function testing can not be carried out, then the following methods should be adopted.

6.2 Safeguard Performance Inspection
Use inspection apparatus or equipment to inspect whether the safeguard performance meets the required standard. If this method fails to accomplish the inspection task or there are no specific safeguard standards listed the requirements, then the following method should be used.

6.3 Safeguard Performance Inspection via Calculation and Visual Observation
With this method, users are also able to check whether the safeguard performance meet the standard requirements on the operation stability, position of center of gravity, marks, and pipeline conditions of the press brake. Make sure the inspection result is scientific and accurate.

7. Instruction for Use
7.1 The drafting of Instruction for Use should meet the requirement of GB/T 15706.2-1995:5 and GB 17120-1997:18.
7.2 The red light indicator should be installed at two diagonally opposite corners of the top of worktable or platform railings exceeding 3m above ground level in height as well as at the end of structure above the said railings.
7.3 Marks, Signs, and Text Warnings
7.3.1 The marks, signs, or text warnings should be clear, indelible, and contain the following contents:
1. Name and Address of the Manufacturer.
2. Model Name
3. Technical Parameters
4. Manufacture Date and Number
5. Limit Signs Related to the Use of the Press Brake.
6. Characteristic Marks Related to the Use of the Safety Device
7.3.2 There should be obvious warning signs at the inlet throat, danger zone, electrical equipment, and the rear end of the press brake. The warning sign should be designed in strict accordance with the regulations of GB 2894 and GB/T 5226.1-1996:18.2.
7.3.3 Make sure that users can see the text warnings clearly when the safeguard device installed at the inlet throat is removed.
7.3.4 The moveable ram, back gauge, and other moving parts need to be marked by alternate yellow and black stripes according to the requirements of GB2893 and GB/T 6527.2-1986:2.6. Depending on the actual needs, those moving parts also can be marked only by the yellow color.
7.4 Instruction for Use
The press brake should come with the Instruction for Use. The drafting of the manual should meet the requirements of GB/T 15706.2-1995:5.5.