Ergonomics - Atlas Copco

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EXTERNAL LOAD For evaluation purposes, it is assumed that the tool is being used for line assembly in the car industry at a workstation where it is used on horizontal surfaces. The installed torque is assumed to be 28 Nm. The height is adjusted to allow a comfortable posture for counteracting the horizontal pull force from the torque reaction. The tool is not suspended in a balancer. It is picked up from the tool rest with one hand, resulting in a radial flexion torque. It is also operated with one hand when tightening. Thus a Male operators Female operators palmar flexion torque will load the operator during tightening. When the tool is posi- tioned on the bolt head a supination torque is required to hold the tool as it enters the bolt. It is assumed that both male and female operators use the workstation. Therefore two evaluations of external load are made, one for male operators and one for female operators. Real loads can be calculated as follows: Trigger force is measured to 4 N with the air inlet connected, Table 4.16 Evaluation of external load for the Angle Nutrunner LTV29 R30-10. Evaluations are given for both male and female operators. On soft joints the installed torque will give a reaction force (pull back) on the Force/Torque MVC Safety factors Reduced Real load Real / Score N/Nm Speed Frequency Duration MVC N/Nm Reduced Trigger 380 N a1=0.8 a2=0.6 a3=0.8 148N 4 N 0.03 0 Pull back 400 N 154 N 104 N 0.7 6 Palmar fl exion 15 Nm 6 Nm 3.1 Nm 0.5 4 Radial fl exion 15 Nm 6 Nm 1.4 Nm 0.2 2 Supination 15 Nm 6 Nm 1.4 Nm 0.2 2 Total score: 14 Force/Torque MVC Safety factors Reduced Real load Real / Score N/Nm Speed Frequency Duration MVC N/Nm Reduced Trigger 245 N a1=0.8 a2=0.6 a3=0.8 92N 4 N 0.04 0 Pull back 300 N 131 N 104 N 0.9 14 Palmar fl exion 10 Nm 4 Nm 3.1 Nm 0.8 7 Radial fl exion 10 Nm 4 Nm 1.4 Nm 0.4 4 Supination 10 Nm 4 Nm 1.4 Nm 0.4 4 Total score: 29 163
164 operator equal to installed torque divi- ded by the distance from the spindle to the center of the handle. In this case: 28/0.270 = 104 N Palmar flexion torque during tightening equals the pull force (104 N) multiplied by the height of the angle head above the bolt head. In this case: 104 N • 0.03 m = 3.1 Nm Supination torque when entering the bolt is the distance from mid-handle to center of gravity, times weight, times gravity. In this case: 0.1 m • 1.45 kg • 9.81 = 1.4 Nm When the tool is picked up from the tool rest the radial flexion torque can be calculated in the same way as the supination torque. WEIGHT The angle nutrunner is a typical assembly tool, and weighs 1.4 kg. Thus, the score is 11. TEMPERATURE A typical tightening cycle lasts 2 seconds. In an 8-hour working day, the average tool running time is normally 2 hours, resulting in a work cycle time of 8 seconds. The temperature in the handle, measured with the tool in a brake running at maximum capac- ity on a soft joint, was 15ºC, thus scoring 4. SHOCK REACTION The shock reaction from an angle nutrunner depends to a large extent on the joint, i.e., whether it is a hard or a soft joint, or some- where in between. It also depends on the operator’s posture, whether the operator’s hand- arm is in line with the motion of the handle, or perpendicular to the motion. All these factors influence the magnitude of the impulse from the joint reaction that tries to rotate the tool. For the purposes of evaluation we use the impulse measured in accordance with ISO 6544 with a torque setting of 28 Nm. The impulse is 2.0 Ns, resulting in a score of 2. This is not taken into account in the evaluation since we based it on a soft joint and the torque reaction is evaluated as a load on the operator. VIBRATION During the development of the vibration test codes for declaration purposes it was found that, in all tests, angle nutrunners had vibration values below 2.5 m/s 2 . The Machine Directive stipulates that if the vibration value is below 2.5 m/s 2 , this fact should be stated. In other words the manufacturer is not obliged to give the actual value. The Standards Commit- tee decided not to develop a test code for angle nutrunners. The manufacturer must, however, be sure that the value is less than 2.5 m/s 2 . To estimate vibration during use, here again it is recommended not to use any correction. a (8) = (2/8) 1/2 • 2.5 = 1.3 m/s 2 The score is thus 9.
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Power Tool Ergonomics E V A L U A T
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Acknowledgements While doing resear
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How to get the best out of this boo
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Work with international standards I
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Good ergonomics is good economics W
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10 SOCIOLOGY INDUSTRIAL SOCIOLOGY S
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12 Work organization No organizatio
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1 outside the production system, an
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1 A seated operator usually has goo
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1 without stretching the trunk. The
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20 The arm sling as a preventive me
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22 Extreme working postures in real
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2 Working with high feed forces req
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2 Working areas of a standing works
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2 body is lifted or tilted, or the
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30 The team is an important factor
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32 Grinders Grinders and sanders ar
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34 HanDle DeSiGn The hand grips on
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36 DUSt anD oil Although the machin
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38 Working environment In general,
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40 SHoCK reaCtion Sudden changes in
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42 practice. Sometimes the chisel h
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44 SHoCK reaCtion These tools do no
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46 heavy, assembly work is often hi
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48 depends on its inertia. The same
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50 bolts. Unfortunately there are a
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52 The low reaction torque in impul
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54 the working environment A typica
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56 Today, the angle nutrunner can b
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58 High torque nutrunners for use w
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60 Wheel nuts on trucks and buses a
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62 Introduction A basic ergonomic p
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64 Handle design The handle of a ha
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66 Arteries Veins (superficial) Vei
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68 Handle size Since a tool handle
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70 However, if the texture is too c
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72 Bibliography Chaffin, D.B. and A
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74 Fig. 3.3 The same feed force app
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76 Pushing and pulling Pushing a to
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78 the object, the shape of the obj
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80 Safety factor a 2 Frequency of t
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82 Comments for different tool type
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84 The trigger is either operated b
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86 used in one handed operations. T
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88 Weight The weight of a hand-held
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90 stability of grip, the center of
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92 Temperature Hand-held power tool
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94 To ensure physical comfort durin
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96 Score 40 30 20 10 0 Bibliography
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98 the dynamic properties of the ma
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100 High motor power and fast clutc
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102 Score 40 30 20 10 0 shock react
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104 piezo-electric crystal. When th
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106 EN 50144 and EN 60745. Both ISO
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108 hole of the wheel are wider tha
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110 In the GTG 40 grinding machine,
Page 113 and 114: 112 RRH machines serves two functio
Page 115 and 116: 114 be noted that declared values b
Page 117 and 118: 116 Noise Noise was the first envir
Page 119 and 120: 118 value for 8 hours’ exposure t
Page 121 and 122: 120 We can start by looking at the
Page 123 and 124: 122 This is done with a minimum inc
Page 125 and 126: 124 microphones at a distance of 1
Page 127 and 128: 126 coated with dust or damaged by
Page 129 and 130: 128 This method has not been used b
Page 131 and 132: 130 tool cabinet. Many workplaces h
Page 133 and 134: 132 lubrication. Made from a compos
Page 135 and 136: 134 Grinder GTG 40 F085 The relevan
Page 137 and 138: 136 were simulated by fitting a whe
Page 139 and 140: 138 Drill LBB 26 EPX-060 The releva
Page 141 and 142: 140 applied to the center of the dr
Page 143 and 144: 142 Chipping hammer RRF 31 The rele
Page 145 and 146: 144 SHOCK REACTION There are no sho
Page 147 and 148: 146 Riveting hammer RRH 06 The rele
Page 149 and 150: 148 WEIGHT The weight is 1.3 kg, sc
Page 151 and 152: 150 Screwdriver LUM 22 PR4 The rele
Page 153 and 154: 152 This gives a score of 9. In pra
Page 155 and 156: 154 Impulse nutrunner EP9 PTX80-HR1
Page 157 and 158: 156 Due to friction in the hydrauli
Page 159 and 160: 158 Electric nutrunner ETP ST32-05-
Page 161 and 162: 160 WEIGHT The electric nutrunner i
Page 163: 162 Angle nutrunner LTV 29 R30-10 T
Page 167 and 168: 166 Electric angle nutrunner Tensor
Page 169 and 170: 168 WEIGHT The electric nutrunner i
Page 171 and 172: 170 High torque nutrunner LTP 51 Th
Page 173 and 174: 172 Score 40 30 20 10 0 NOISE The d
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Ergonomics - Atlas Copco

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