Machine Guarding Technology - PowerPoint PPT Presentation

Loading...

PPT – Machine Guarding Technology PowerPoint presentation | free to view - id: 1ad244-ZDc1Z



Loading


The Adobe Flash plugin is needed to view this content

Get the plugin now

View by Category
About This Presentation
Title:

Machine Guarding Technology

Description:

Machine Guarding Technology – PowerPoint PPT presentation

Number of Views:62
Avg rating:3.0/5.0
Slides: 148
Provided by: ste8160
Category:

less

Write a Comment
User Comments (0)
Transcript and Presenter's Notes

Title: Machine Guarding Technology


1
Machine Guarding Technology
2
Objective
  • To introduce some methods and technologies that
    can be used to reduce the exposure of employees
    to point of operation hazards.

3
Goal
  • The goal is to provide you with a better
    understanding of the technology that is available
    and how it is used

4
Technologies
  • Safety Interlock Switches
  • Non Contact Interlocks
  • Guard Locking Devices
  • Trip Cords
  • Safety Mats
  • Safety edges
  • Two hand trip controls
  • Safety Light Curtains

5
Technologies
  • Safety Laser Scanners
  • Enabling Switch
  • Trap key Systems
  • Control Reliable Fluid Power Valves
  • Hydraulic Press Brake Safeguarding

6
Safety Interlock Switches
7
Safety Interlock Switches
  • Principles interlocks a guard door or access
    panel with the power source of the hazard
  • Application They are used where physical hard
    guarding protects personnel from dangerous
    machine motion or other hazardous
  • Advantages Provides a physical barrier that
    prevents reaching or walking into the hazardous
    area and Guards against flying chips and sparks

8
Safety Interlock Switches
  • Disadvantages Requires careful adjustments and
    maintenance. Inhibits access to the point of
    operation. Can reduce visibility of point of
    operation
  • Cost Under 100 to over 400
  • Maintenance Requires periodic testing
  • Consensus Standards ANSI B11.19, 3.32, 7.1.6
    2003,

9
What to look for in a safety interlock switch
  • Defeat resistant The method of using the
    machine and the severity of the hazard should
    dictate how difficult it should be to override
  • Reliability It must operate reliably under all
    conditions

10
Defeat resistant
  • Designed so they cannot be defeated in a simple
    manner. With readily available objects.

11
(No Transcript)
12
(No Transcript)
13
(No Transcript)
14
Reliability
  • The switch should be designed to operate reliably
    under all conditions such as
  • Broken switch The switch should have Isolated
    contacts
  • Welded contacts The switch should have positive
    mode operations

15
Isolated Contacts
  • On contact blocks with two sets of contacts a
    galvanic isolation barrier is required if it
    would be possible for the contacts to touch each
    other in the event of a contact weld or other
    component failure

16
Isolated Contacts
Galvanic IsolationBarrier
17
Overcoming a welded contact
  • Positive Mode Operation A moving mechanical
    component inevitably moves another component
    along with it, either by direct contact or via a
    rigid element. It should not rely solely on
    spring pressure to open the contacts

18
(No Transcript)
19
Can they do this?
20
(No Transcript)
21
(No Transcript)
22
Standard
  • This is the international symbol for a positive
    acting switch
  • This is the standard the
  • switch was built to

23
Non-Contact Interlocks
24
Non-Contact Interlocks
  • Principles rely on the presence or absence of
    some sort of magnetic or electronic field
  • Application They are used where conditions make
    it difficult or imposable to use a mechanical
    switch
  • Advantages They can be used in harsh or wet
    environments, they do not require careful
    alignment

25
Non-Contact Interlocks
  • Disadvantages switches without redundancy and
    automatic monitoring are generally not suitable
    for interlocking duties. Require a controller
  • Cost Under 250 to over 800 (with controller)
  • Maintenance Requires periodic testing
  • Consensus Standards ANSI B11.19, 3.32, 7.1.6
    2003,

26
What to look for in a non-contact interlock
switch
  • Defeat resistant The method of using the
    machine and the severity of the hazard should
    dictate how difficult it should be to override
  • Reliability It must operate reliably under all
    conditions

27
Defeat resistant
  • By using multiple magnetically biased reed
    contacts, or an electrically coded read head,
    intentional defeat is drastically reduced.

28
Difficult to use a mechanical switch
29
Typical non-contact interlocks
Control Monitor Relay
Electrically Coded
Magnetically Coded
30
Reliability
  • These devices rely on the presence or absence
    of some sort of magnetic or electronic field.
    Because they do not have the benefit of true
    mechanical positive mode operation, they must
    rely on oriented failure modes and/or the use of
    duplication and monitoring

31
Guard Locking Devices
32
Guard Locking Devices
  • Principles The guard remains closed and locked
    (retaining the actuator) until the risk of injury
    from the hazard has passed, to insure that no
    entry can be made to the hazardous area until all
    motion has ceased
  • Application used in applications where dangerous
    motion behind a panel or door will continue for
    some period of time after power is removed from
    a machine
  • Advantages They can be used on machines with
    long stopping times.

33
Guard Locking Devices
  • Disadvantages Needs a method to detect the
    stopping of motion or a safety rated timer.
  • Cost Under 150 to over 700
  • Maintenance Requires periodic testing
  • Consensus Standards ANSI B11.19, 3.32, 7.1.6
    2003,

34
What to look for in a Guard Locking Device
  • In a Conditional Guard Unlocking Device- That it
    can only be opened on Receipt of a Signal That
    the contactor is OFF or a pre set time interval
    has elapsed or that dangerous motion has ceased.
  • In an Unconditional Guard Locking device That
    he handle or guard lock also opens the circuit
    and that a sufficient amount of time is required
    to enable the motion to stop

35
Guard Locking
  • Locking Family Switches are typically used in
    applications where dangerous motion behind a
    panel or door will continue for some period of
    time after power is removed from a machine

36
Guard Locking
  • The guard remains closed and locked (retaining
    the actuator) until the risk of injury from the
    hazard has passed, to insure that no entry can be
    made to the hazardous area until all motion has
    ceased

37
Four Types of Guard Locking
  • Manually Applied/Manually Released
  • Spring Applied/Power Released
  • Power Applied/Spring Released
  • Power Applied/Power Released

38
Manual
39
Power Type Switches
40
Solenoid operated locking switch
41
Guard Locking
  • Spring applied, power release devices must
    have manual unlocking that requires the use of a
    tool to operate.

42
Manual unlocking
43
Trip Cords
44
Trip Cords Rope or Wire pulls
  • Principles when pulled or cut (made slack) will
    cause the attached switch to generate an
    emergency stop
  • Application They are used horizontally across
    the points of hazard generated by rotating
    machinery, conveyor motion etc.
  • Advantages they can be located at the point of
    hazard for the involved operators use, unlike an
    E-Stops which may be located away from the point
    of hazard

45
Trip Cords
  • Disadvantages They do not prevent injury, but
    may limit the extend of injury, can have zones of
    unknown action
  • Cost Under 250 to over 500
  • Maintenance Requires periodic testing, need to
    be kept in tension
  • Consensus Standards ANSI B11.19, 3.32, 7.1.6
    2003,

46
What to look for in trip cord
  • Proper Tension The unit should be designed to
    be under constant steady tension. To slack or to
    tight should trip the device
  • Proper Installation It must be installed to
    minimize the unknown action zone

47
Proper Tension
48
Proper Installation
49
Proper installationVector Eyebolt
50
Vector Eyebolt
51
Distance between Eyebolts
52
Direction Change
53
Turning the corner
54
Turning the corner
55
(No Transcript)
56
When Properly Installed
  • The switch should activate with reasonable force
    (5 to 20 lbs.) and reasonable deflection (3 to 6
    inches) over the zone of protection

57
Safety Mats
58
Safety Mats
  • Principles A signal is transmitted through the
    upper and lower plates. When sufficient pressure
    is applied to the mat the plates touch causing
    the controller to send a stop signal to the
    machine.
  • Application They are used where perimeter access
    guarding is required protects personnel from
    dangerous machine motion or other hazardous
  • Advantages Provides improved productivity while
    providing access guarding.

59
Safety Mats
  • Disadvantages Requires a controller to monitor
    the status of the mats, may need frequent
    replacing if in areas of heavy vehicle traffic
  • Cost Under 700 to over 5,000
  • Maintenance Requires periodic inspection and
    testing
  • Consensus Standards ANSI B11.19-2003
  • ANSI/RIA R15.06-1999

60
What to look for in a safety mat
  • Mat Controller- A controller is necessary to
    monitor for a failure in the mat system.
  • Proper Installation Most important is the
    calculation of the safety distance. To insure a
    minimum mat size is placed between a worker and
    the hazard, and that the mat is secured to the
    floor

61
Mat Controller
62
Typical Application
Pressure Sensitive Safety Mats
63
Mat Safety Distance Calculations
  • The first and by far the most important
    consideration is the calculation of the safety
    distance. There is a Minimum mat size that should
    be placed between a worker and a Hazardous motion.

64
ANSI B11.19-2003Annex D
  • The added distance, in inches for a ground level
    device which can be reached over (safety mats) is
  • 48 inches

65
DsK (TsTcTrTspm)Dpf
66
  • K 63 in./sec (hand speed constant)
  • Ts Tc 0.200 (Total machine stop time)
  • Tr 0.030 (mat control system 30ms)
  • Tspm .050 (A brake monitor set of .250
    seconds - .200 total stop time)
  • Dpf 48 in

67
DsK(TsTcTrTspm)Dpf
  • Ds63(.200.03.05)48
  • DS65.64 in.

68
65.64
K(TsTcTrTspm)17.64
48
69
Only authorized persons may relocate the safety
mat
70
Safety Edges
71
Safety Edges
  • Principles The safety contact is located inside
    the safety contact strip. Pressing the safety
    contact strip will cause the controller to change
    to an open state, but when pressure is removed
    the contacts will NOT transfer back without a
    reset
  • Application flexible edging strips fixed to the
    edge of a moving part. If the moving part
    strikes the operator (or vice versa) a stop
    signal is sent
  • Advantages can be used where there is a risk of
    crushing or shearing, or a risk of operator
    entanglement.

72
Safety Edges
  • Disadvantages Requires a controller to monitor
    the status of the edges, can only be used on
    machine with short stop times , or to limit the
    extent of an injury
  • Cost Under 600 to over 1,000
  • Maintenance Requires periodic inspection and
    testing
  • Consensus Standards ANSI B11.19-2003 3.59

73
What to look for in a safety edge
  • Edge Controller- A controller is necessary to
    monitor for a failure in the mat system.
  • Proper Installation The switch edge should be
    of sufficient size to insure that the switch will
    activate and stop motion before the edge is fully
    compressed

74
Safety Contact Strips
  • Safety contact strips are used on edges of guard
    or gates and at possible crushing or shearing
    points

75
(No Transcript)
76
How they work
77
(No Transcript)
78
Two Hand Trip/control
79
Two Hand Control/Trip
  • Principles Two start buttons have to be operated
    at the same time to run the machine. This ensures
    that both hands of the operator are occupied in a
    safe location and cannot be in the hazard area
  • Application They are common on single cycle and
    index table applications
  • Advantages Can provide effective protection for
    the operator, Two-hand trip can be used on
    machines that cannot be stopped

80
Two hand control/Trip
  • Disadvantages Provides protection for the
    operator only, Inefficient because the operators
    hands must maintain the buttons through the
    hazardous portion of the cycle
  • Cost Under 400 to over 600
  • Maintenance Requires periodic inspection and
    testing
  • Consensus Standards ANSI B11.19-2003 3.71 3.73

81
What to look for in a Two hand control/Trip
  • Mounting separation the installation should be
    such that the two controls cannot be operated
    with the hand and elbow from the same arm. The
    device shall be located at a distance such that
    the operator cannot reach the hazard with a hand
    or other body part before the hazard is removed.
  • Synchronous Actuation/Simultaneity An output
    signal shall be generated only when both buttons
    are actuated within .5 seconds of each otherif
    not, both must be released before the next output
    signal can occur.

82
Two Hand Control Relay
83
Two-Hand Control
84
Safety Light Curtains
85
Safety Light Curtain
  • Principles A photoelectric transmitter projects
    an array of synchronized, parallel infrared light
    beams to a receiver unit. When an opaque object
    interrupts one or more beams the control logic of
    the light curtain sends a stop signal to the
    guarded machine
  • Application They are very often used for point
    of operation guarding and for perimeter guards
  • Advantages Protects multiple operators and
    other employees, Allows freer movement for
    operator, No adjustments required

86
Safety Light Curtain
  • Disadvantages Not practical for machines with
    long stop times, Does not protect against flying
    chips and sparks, Does not protect against
    mechanical failure
  • Cost Under 1000 to over 7000
  • Maintenance Requires periodic inspection and
    testing (once per shift)
  • Consensus Standards ANSI B11.19-2003 3.44
    ANSI/RIA R15.06-1999, UL508

87
What to look for in aSafety Light Curtain
  • Proper Installation- The curtain must be at the
    proper distance from the hazard, and installed in
    such a manner that you cannot stand between it an
    the hazard without being detected the light
    curtain or other device.
  • Supplemental Guarding- May be needed to prevent
    reaching over under or around the Safety Light
    Curtain

88
Safety Light Curtains
89
A Light Curtain in its Simplest Form
Receiver
Emitter
90
(No Transcript)
91
Safety Light Curtain Design
  • Redundant Logic Systems
  • Dissimilar microcontrollers
  • Unique software for each controller
  • Written by different authors
  • Comparison of Status
  • Exercising of System Components

92
Safety Light Curtain
93
Optical Performance
  • The presence sensing device shall have
    identifiable minimum object sensitivity.
  • Not Beam Spacing

94
Minimum object sensitivity
  • This refers to the smallest object (diameter)
    that the light curtain can detect. It is
    sometimes referred to as the resolution of the
    light curtain or as its detection capability

95
Beam Spacing, or Optical Pitch
  • Refers to the distance from the center line of
    one beam to the center line of the next beam
  • It is possible for an object that is the same
    diameter as the optical pitch to be in such a
    position that it does not block the path of a
    single beam

96
Some Common light curtain resolutions
  • 14mm or less (0.55 inches) for finger
    protection
  • 30mm or less (1.25 inches) for hand protection
  • 50mm 500mm or less (2.00 20.00 inches) for
    body protection

97
(No Transcript)
98
Three Box System
Two Box System
99
Type 2 vs., Type 4
  • Fault Detection Circuits Type two light
    curtains lack the redundant automatic
    self-checking circuits employed in type 4 light
    curtains. As a result they do not meet the OSHA
    or ANSI requirements for control reliability
  • Optical Angle- Type 4 safety light curtains have
    an effective optical angle of 2.5º, while type 2
    devices have an effective optical angle of 5º.
    The wider angle increases the possibility of
    reflective surface interference which may cause
    an optical short circuit

100
(No Transcript)
101
Optical Short Circuit
102
(No Transcript)
103
(No Transcript)
104
Test Procedure
105
Safety Laser Scanners
106
Safety Laser Scanner
  • Principles Safety laser scanners are optical
    sensors that used pulsed laser light to scan its
    surroundings. It then compares the scanned
    information to its predefined zones. If it
    detects an intrusion into that area it sends a
    stop signal to the guarded machinery
  • Application Robotic work cells, in front of
    press or other machinery, and guarding the front
    or rear of an automated guided vehicle
  • Advantages Can guard stationary and moving
    equipment, and can be configured for multiple
    irregularly shaped hazardous areas. Can provide a
    warning Zone

107
Safety Laser Scanner
  • Disadvantages Does not protect against flying
    chips and sparks, Does not protect against
    mechanical failure, May not work in very dusty or
    Smokey environments
  • Cost Under 4500 to over 8000
  • Maintenance Requires periodic cleaning and
    inspection and testing.
  • Consensus Standards ANSI B11.19-2003 3.44
    ANSI/RIA R15.06-1999, 11.5

108
What to look for in aSafety Laser Scanner
  • Warning and Protected Zones Clearly Marked- The
    Zones should be clearly marked to give persons in
    the area a clear indicator of the location of the
    zones.
  • The System is Installed Properly- The units
    should not be more than 12 above the walking
    surface when mounted horizontally

109
Laser Scanners
  • Are opto-electronic protective device that
    operates similar to radar, but using light
    transit time to measurer its environment
  • The time of flight measurement is directly
    related to the distance the light has traveled to
    an object

110
(No Transcript)
111
(No Transcript)
112
(No Transcript)
113
(No Transcript)
114
(No Transcript)
115
Trap Key / Captive Key Systems
116
Trap Key System
  • Principles the premise that no one key can be in
    two places at once, Trap key systems can be
    configured to require a predetermined sequence of
    events takes place to eliminated or reduced
    hazards to a tolerable level before operators are
    exposed to them
  • Application Robotic work cells, to prevent the
    accidental or illegal discharge of processing
    material, to control access to equipment or
    machinery while it is in a dangerous state
  • Advantages Can be used in an explosive
    atmosphere, Can provide a higher degree of
    security and tamper resistance

117
Trap Key Systems
  • Disadvantages May not be best for machines that
    require frequent manual operation, may requires
    additional hard guarding
  • Cost Under 1,100 to over 15,000
  • Maintenance Requires periodic cleaning and
    inspection and testing.
  • Consensus Standards ANSI B11.19-2003 3.44
    ANSI/RIA R15.06-1999, 5.2.1

118
What to look for in a Trap Key System
  • The lock can only be operated by the dedicated
    key It should not be possible to defeat the
    lock by means of a tool or by mistreating it in
    any manner, and the specifying of the key code
    should insure that only one key works.
  • It is not possible to obtain the key in any other
    manner than the intended manner Any excessive
    force will result in a broken key as opposed to a
    broken lock

119
Time Delay Trap Key
120
Non Time Delay Example
121
Dual Key Lock
122
How it works
B Key
123
3-Port Spool Valve
124
Valve Interlock
125
Enabling Switch Device
  • Principles- A manually operated device which when
    continuously activated, permits motion
  • Application- Allows for troubleshooting, set-up,
    programming, or servicing of robotic or automated
    machinery
  • Advantages- Provides the margin of safety needed
    when no other safety devices are possible or
    practical

126
Enabling Switch Device
  • Disadvantages Requires the use of one hand to
    control the switch, may cause fatigue if used for
    long periods
  • Cost Under 300 to over 500
  • Maintenance Periodic inspection of switch and
    cable, testing of device
  • Consensus Standards ANSI/RIA R15.06-1999, 3.12
    10.10.3

127
What to Look for
  • Ergonomic Design Switch should be designed to
    minimizes discomfort and allow the hand to be in
    as much of an at rest position as possible
  • That the switch is used in conjunction with some
    other presence-sensing safeguarding device to
    ensure the safety of others in the area

128
Enabling Device
129
  • Position 1 This is the released STOP position
  • Position 2 This is the ENABLED position, the
    trigger is pressed and held in this position to
    allow machinery to operate
  • Position 3 This is Squeezed STOP position, the
    trigger is pressed beyond the middle position

130
Control Reliable Fluid Power Valves
131
Safety SystemsDo not end at the wire!
Fluid power devices used in a safety circuit can
experience diminished performance or failures
that slow machine stopping time or cause
unexpected hazardous motion.
Accidental manual override Burnt solenoid Jammed
spool Partial shift and temporary
positions Failure to LOTO Broken return spring
T
T
132
Control Reliable
  • They are redundant, fail to safe, monitor
    stopping time and lock out and inhibit further
    operation upon failure

133
Control Reliable Fluid Power Valves
  • Disadvantages The removal of large volumes of
    air can be expensive. Concerns of holding
    positions and the re-application of pressure may
    need to be addressed.
  • Cost Cost-500 to 2000 depending on flow rates.
  • Maintenance Monitor for sluggish valve element
    and operation to prevent an increase in
    exhausting time
  • Consensus Standards B11.1, B11.19, ANSI/PMMI
    B155.1-2006, ANSI/ASSE Z244.1-2003

134
What to look for in a Control Reliable Fluid
Power Valve
  • Proper Sizing Proper sizing of the valve for
    flow rate exhausting capacity.
  • Reliability It must be Control Reliable if ANSI
    Standards, or the risk assessment call for that
    level of reliability.

135
Additional Fluid Power Safety Solutions
Cat 2 Load Holding Dump
Valves (Industrial rated valve with a spool
monitoring switch) Cat 4 Redundant Monitored
Pilot Operated check Valves Lock Out/Tag Out
and EEZ-On Valves (With full flow exhaust)
  • Fluid Power Safety Applications
  • Pinch Points
  • Lock Out/Tagout
  • Energy Isolation
  • Clutch / brakes
  • Counterbalance
  • Monitored Power systems
  • Partial de-energization
  • Vertical loads
  • Load holding
  • EEZ0-On gradual buildup
  • Cylinder mid-stroke positioning

136
Laser Safeguardingfor Hydraulic Press Brake
137
Laser Safeguardingfor Hydraulic Press Brake
  • Principles- A continuous band of laser light that
    senses the zone below the punch. If an
    obstruction is detected, the ram movement is
    stopped and retracted
  • Application- For use on most down and up acting
    hydraulic press brakes
  • Advantages- Permits freedom of handling the work
    piece and higher throughputs while providing
    operator protection and real time monitoring for
    press brake failures

138
Laser Safeguardingfor Hydraulic Press Brake
  • Disadvantages Will not work on all Hydraulic
    press brakes, requires professional installation
  • Cost 9,000 to 15,000 installed
  • Maintenance Requires periodic inspection and
    testing
  • Consensus Standards ANSI B11.19, ANSI/UL 1998
    Rev.1, EN954-1

139
What to look for
  • Failure detection Should be performed by
    real-time monitoring of the process under control
  • Third party Certification The system should be
    inspected an certified by a third party such as a
    NRTL or a EU Notified Body

140
the Agency has determined that the laser
guarding device may be considered an acceptable
form of guarding under 1910.212, OSHA also has
cautioned employers that guarding systems
generally are appropriate only if they are
designed, installed, used, and inspected in a
manner that will effectively and reliably prevent
injury. Thus, OSHA will consider carefully
individual laser guarding systems installed in
conjunction with hydraulic press brakes to
determine whether they effectively and reliably
protect employees from point of operation hazards
and other equipment-related hazards..
141
Laser Scanning System
142
(No Transcript)
143
System in Use
144
(No Transcript)
145
Summary
146
Questions?
147
Thank You
About PowerShow.com