A System for Automated Fixture Planning with Modular Fixtures

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14 In order to huther automate fixhue planning pmcess. humao e xw' knowledge need to be. replaced by more precise analytical methods. In chapter 3, we will describe various analytical methods that can be used to automatidy determine furure components' locations and estimate the neesary damping force.
3.1. Introduction 15 Chapter 3 Necessary Analyses in Fixture Planning 3.1.1. Requirements for Fixture Planning F m planning with either clamps or a vise consists of locating. suppmting, and clamping a part with variom fixhue compooents. The follcwhg a~ tfie mpinmen~ that a fixlure plan with modular fixtures shouldsarisfy. 1. There should be no inmfemm between fixture ccinponents and cum path. 2. 'Iherc should be no in- between fixture comlnments and pmr geaneUy. 3. lhere shouldbe Minmfemm betweenfixturecoolpcments 4. A wcfkpiece should be held rigidly during macbhing. 5. A lixtnre plan should enslare accurate position of the wdpiece with respect to the machine corndinate system. 6. A fixture plan should prevent unacceptable deflection ar deformation of the workpiece due to cutting and clamping force. 7. No active fixture component shculdcause the part to mow after the putis bxted. 8. A fixture plan needs to be inexpensive and fast to assemble. Most Iixm requirements an be checked by analytical took to 1) check interference between various objecrs in a future plan, 2) check part rotation due to clamping, 3) compute WceSSXy clamping force m hold the put rigidly, and 4) check part deflection due to clamping or cuaing force. While a fixture plan should satisfy every requirement, it may be difhdt and trmwonsuming for a tool designer m pafm accm analysis without fast and reliable analytical tools. SecW 2 dcscrhs an existing method far intedme checking between solid objects. Also. a few simpleschemes to speedup the compotation are suggested. section 3 describesa mathem&al tool that can check any part movement due to clamping during a fixm assembly. Section 4 inuoduces a marbematical tool used to compute the minimal clamping force while a part is held rigidly under various cuuing forces. Section 5 discusses the problem of part deflection and describes schemes that a human expert use8 to prevent deflection. In section 6, a summary of this chapter is given.
Page 1: A System for Automated Fixture Plan
Page 5: Abstract This thesir desribes a sys
Page 9: Acknowledgements First of all, I wo
Page 12 and 13: 4.7.1. Position and Orientation of
Page 15 and 16: List of Figures Figure 1-1: A modul
Page 17: Figure 6-26: A force model to estim
Page 20 and 21: describes how the pan is held on .t
Page 22 and 23: 1.3. Effect of Fixture Plans on Cos
Page 24 and 25: 6 New and existiog analytical mls a
Page 27 and 28: Chapter 2 Literature review Two maj
Page 29 and 30: 11 Inim 2-2: A fixnae plan by C~OU
Page 31: 13 Thaoreridy, grasp planning and f
Page 35 and 36: Y A A x . X mul max 17 - x P i e 3-
Page 37 and 38: 19 are projected onto the same plan
Page 39 and 40: Z X 21 Wrenches from bodom referenc
Page 41 and 42: For toque: For thrust M Kp]8d1.8A T
Page 43 and 44: 2s The equation (3.5) conservativel
Page 45 and 46: n @ friction force _.. .- normal I
Page 47 and 48: Minimize N1 -p - N
Page 49 and 50: 31 area is 1 square inch. the stres
Page 51 and 52: 4.1. Introduction 33 Chapter 4 A Sy
Page 53 and 54: 35 checking part deflection and sel
Page 55 and 56: 4.4. Assumptions 37 The future plan
Page 57 and 58: 39 A touch probe should be used to
Page 59 and 60: 4.6.2. Cutting plan 41 1 major refe
Page 61 and 62: Cutting force and direction 43 Chap
Page 63 and 64: Clamp bar 45 , .....-, . strap clam
Page 65 and 66: aata base for supports> Type No. R
Page 67 and 68: 49 thickness. If the part is suppor
Page 69 and 70: 51 While the z coordinate of the pa
Page 71 and 72: 5.1. Introduction 53 Chapter 5 Fixt
Page 73 and 74: 55 Because the goal is to generate
Page 75 and 76: Accessible edge 57 Inaccessible edg
Page 77 and 78: clamps are oriented so that they am
Page 79 and 80: 61 unacceptable part deflection due
Page 81 and 82: Enlarged f I ! 63 Y 4 Figure 5-9: E
Page 83 and 84:
clamp location I 65 Pipre 5-11: par
Page 85 and 86:
67 desirable contact area Y Zt X
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69 When every candidate plan genera
Page 89 and 90:
71 5.9.1. Generation of Candidate L
Page 91 and 92:
73 Egure 5-20 shows the actual loca
Page 93 and 94:
5.10. Rating Fixture Plans 75 Typic
Page 95:
n not be possible to install a clam
Page 98 and 99:
L jaw geometry in the local c odite
Page 100 and 101:
m = no. of contact planes for a mov
Page 102 and 103:
84 The following rearming is used m
Page 104 and 105:
86 F i €4 shows obstacles mapped
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88 In our reasoning. each pan face
Page 108 and 109:
i obstacles Figure 6-11: Globally f
Page 110 and 111:
7 obstacles I case 3: If xiax < 92
Page 112 and 113:
6.7. Determining the loeation of vi
Page 114 and 115:
xo Case 1 96 X common contact area
Page 116 and 117:
98 Obr Option 1: adjust the jaw loc
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100 Parallel bars should be placed
Page 120 and 121:
When LCfc Lbor+ 2 d Case 1: When %=
Page 122 and 123:
movable jaw 1W . . . . . . There is
Page 124 and 125:
X m Pigore 6-28 Invalid fume plans
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planner getg cutting plans for a se
Page 128 and 129:
0.150 110 ; IMW Teat Part 2 -- boon
Page 130 and 131:
112 For a clamp libmy, we have cons
Page 132 and 133:
114 *** Plan with clamp type with 5
Page 134 and 135:
116 II II Fipre 7-6: F m plans with
Page 136 and 137:
118 77 1 Y II’ .- Figure 7-7: Fut
Page 138 and 139:
120 I i Figum 7-9 Fuhue plans with
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The system has generated multiple f
Page 142 and 143:
,170 Chamfered hole 124 Chamfer 1 C
Page 144 and 145:
I1 i Figure 7-14: Fixture plans for
Page 146 and 147:
I 0.150 - 2582 - 7.7.1. Speed of Fi
Page 148 and 149:
130 Figure 7-18: F’art geometry o
Page 150 and 151:
134 8.1.1. Fixfure Planning with Ov
Page 152 and 153:
for holding rectangular parts due t
Page 154 and 155:
138 series of fixture plans fm each
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the fixture plan viokea any fixture
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142
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144 Ohwovoride [Ohwovoriole 801 app
Page 162 and 163:
[Ahmad 871 t m 851 [Goldman 561 Ref
Page 164 and 165:
Menassa, R. J. and Devries, W. R. O
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A System for Automated Fixture Planning with Modular Fixtures

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