Black and Decker Grinder - Revision history

Bfriday at 01:21, 26 March 2007

2007-03-26T01:21:39Z

Bfriday at 01:16, 26 March 2007

2007-03-26T01:16:20Z

Bfriday at 01:06, 26 March 2007

2007-03-26T01:06:18Z

Bfriday at 01:04, 26 March 2007

2007-03-26T01:04:09Z

Bfriday at 23:29, 24 March 2007

2007-03-24T23:29:34Z

Bfriday at 23:29, 24 March 2007

2007-03-24T23:29:06Z

Bfriday at 23:27, 24 March 2007

2007-03-24T23:27:43Z

Bfriday at 23:24, 24 March 2007

2007-03-24T23:24:08Z

Bfriday at 19:53, 23 March 2007

2007-03-23T19:53:35Z

Bfriday at 19:52, 23 March 2007

2007-03-23T19:52:56Z

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 To calculate the stress in the gears, a stress equation was used from the ''Fundamentals of Machine Components Design'' by Robert C. Juvinall.  The velocity factor was caluated with the assumption that the gears were precision shaved and ground.  The overload factor was calculated with the assumption that the source of power is uniform and the driven machinery is assumed to have moderate shock.  Both gears were overhung, which gave a mounting factor of 1.25.  The calculated stress in the smaller gear was 613.601 PSI and the stress in the larger gear was 442.438 PSI.
-To calculate the life of the bearing a life expectancy equation was used from the ''Fundamentals of Machine Components Design'' by Robert C. Juvinall.  It was found that common practice was to use a dynamic load for a like of 9X10^6 seconds. Assuming the grinder will be used constantly the bearing will last 1.83 years before failure.  If the grinder will be used six hours every day, 365 days a year then the bearing will last 7.33 years.  Under the more realisitic assumption that the grinder will be used six hours a day, five days a week, the bearing will last 10.26 years.
+To calculate the life of the bearing a life expectancy equation was used from the ''Fundamentals of Machine Components Design'' by Robert C. Juvinall.  It was found that common practice was to use a dynamic load for a like of 9X10^6 seconds. Assuming the grinder will be used constantly the bearing will last 3.33*10^7 years before failure.  If the grinder will be used six hours every day, 365 days a year then the bearing will last 1.33*10^8 years.  Under the more realisitic assumption that the grinder will be used six hours a day, five days a week, the bearing will last 1.86*10^8 years.
 ==Parts==
@@ Line 148: / Line 148: @@
 ! 4
 |align="center"|Type of Analysis and method of obtaining results. List relevant equations and describe how they relate to the design decisions
-| align="center"|The major design considerations are the size and strength of the bearing in combination with the force exerted on the shaft. The force exerted on the shaft will probably be known before the bearing is chosen. Hence the only variables in the equation are the dynamic load and the life rating of the bearing. It seems to be common practice that the bearings are rated at a given dynamic load for a life of   s. The Dynamic load depends mainly upon two factors, the dimensions of the bearing and the material composition.
+| align="center"|L=Lr(C/Fr)^3.33 is the one equation that governs the life expentancy of bearings.  The major design considerations are the size and strength of the bearing in combination with the force exerted on the shaft. The force exerted on the shaft will probably be known before the bearing is chosen. Hence the only variables in the equation are the dynamic load and the life rating of the bearing. It seems to be common practice that the bearings are rated at a given dynamic load for a life of  9*10^6 s. The Dynamic load depends mainly upon two factors, the dimensions of the bearing and the material composition.
 |-
 ! 5
 |align="center"|Quantitative Results (plots, calculations). How do these relate back to the engineering specifications? How do they verify the quality of the design?
-| align="center"|This quantity turned to be about 10.26 years if the grinder was used for 6 hours a day 5 days a week. This exceeds the life requirement target of 10 years and reinforces the quality of the design.
+| align="center"|This quantity turned to be about 1.86*108 years if the grinder was used for 6 hours a day 5 days a week. This exceeds the life requirement target of 10 years and reinforces the quality of the design.
 |-
 ! 6

@@ Line 159: / Line 159: @@
 |-
 |}
 The table belows explains the caclation of the force on the gears:
@@ Line 195: / Line 197: @@
 |align="center"|What changes could be made to improve the quality of this design with respect to this engineering specification? What trade-offs would this introduce?
 | align="center"|Lowering the force on the gears would improve this engineering specification.  This would allow the motor to be smaller as well as the grinder to be more compact.  The draw backs of this is that it decreases RPM’s at the grinder wheel which would decrease the performance of the grinder.
 |-
 |}

← Older revision		Revision as of 01:06, 26 March 2007
Line 160:		Line 160:
	\|}		\|}

		+	The table belows explains the caclation of the force on the gears:

		+	{\| border="1" align="center"
		+	\|+ '''Table 2.2: Force on gears'''
		+	! width="50"\| !! width="200"\| !! width="400"\|
		+	\|-
		+	! 1
		+	\| align="center"\|Engineering Specification (description, target value, direction of improvement) and related User requirement.
		+	\| align="center"\|Force on the Gears in a tangential direction, the target value is the lowest possible value to achieve 10,000 rpm at the grind wheel, direction of improvement is ↓, the user requirements related are tool life and grinding ability.
		+	\|-
		+	! 2
		+	\|align="center"\|Design decisions/parameters affected
		+	\| align="center"\|Torque required at the motor, type of gears used, design of gears
		+	\|-
		+	! 3
		+	\|align="center"\|Key geometric, inertia, and material properties
		+	\| align="center"\|Gear Ratio (31:9), Strength of gear
		+	\|-
		+	! 4
		+	\|align="center"\|Type of Analysis and method of obtaining results. List relevant equations and describe how they relate to the design decisions
		+	\| align="center"\|We looked up the power requirement for the grinder using P=IV. Then using P=Tω we found the torque provided by the motor. Knowing the radii of the gears we found the tangential force on the gears.
		+	\|-
		+	! 5
		+	\|align="center"\|Quantitative Results (plots, calculations). How do these relate back to the engineering specifications? How do they verify the quality of the design?
		+	\| align="center"\|P=IV (5.5 amps/2)*120V = 330 Watts
		+	P=Tω ω = (10,0002pi) / 60
		+	T = 330/ω = 0.315 Nm
		+
		+	.315/0.05715 = 5.51 kg
		+	5.51 * 9.81 = 12.4626 N at the gears
		+
		+	\|-
		+	! 6
		+	\|align="center"\|What changes could be made to improve the quality of this design with respect to this engineering specification? What trade-offs would this introduce?
		+	\| align="center"\|Lowering the force on the gears would improve this engineering specification. This would allow the motor to be smaller as well as the grinder to be more compact. The draw backs of this is that it decreases RPM’s at the grinder wheel which would decrease the performance of the grinder.
		+	\|-
		+	\|}
	[[Image:caddrawings.jpg\|Figure 2: CAD Drawings]]		[[Image:caddrawings.jpg\|Figure 2: CAD Drawings]]

@@ Line 20: / Line 20: @@
 For the force requirement on the gears to rotate the grind wheel at 10,000 RPM, the power consumption of the grinder was researched.  From the power consumption the torque was calculated to be 0.315 Nm, which equates to about 2.61 lbs of force on the workpeice from the grind wheel.  This calculates to 12.4626 N of force at the gears to rotate the grind wheel at 10,000 RPM.
 To calculate the stress in the gears, a stress equation was used from the ''Fundamentals of Machine Components Design'' by Robert C. Juvinall.  The velocity factor was caluated with the assumption that the gears were precision shaved and ground.  The overload factor was calculated with the assumption that the source of power is uniform and the driven machinery is assumed to have moderate shock.  Both gears were overhung, which gave a mounting factor of 1.25.  The calculated stress in the smaller gear was 613.601 PSI and the stress in the larger gear was 442.438 PSI.
 ==Parts==

@@ Line 158: / Line 158: @@
 | align="center"|The major changes that could be made to improve the quality of the bearing would be to increase the strength of the bearing, to increase the size of the bearings, to use higher quality lubrication and to lower the force exerted by the shaft. Lowering the force on the shaft would have a dramatic effect on the performance of the grinder and hence is not very feasible. The only negative to all the other modifications is that making these changes would increase the cost of the grinder and in any engineering decision optimizing cost is always a primary concern.
 |-
 |}
 [[Image:caddrawings.jpg|Figure 2: CAD Drawings]]

@@ Line 160: / Line 160: @@
 |}
 <embed src="http://www.youtube.com/v/Ocex8YbNa_o" type="application/x-shockwave-flash" width="425" height="350"></embed>
 [[media:badawesomegear.avi|Right-click here and select "Save Link As" to download the video (.avi)]]

@@ Line 132: / Line 132: @@
 {| border="1" align="center"
 |+ '''Table 2.1: Bearing Life Expenctancy'''
-! width="200"| !! width="300"|
+! width="50"| !! width="200"| !! width="400"|
 |-
 ! 1
@@ Line 143: / Line 143: @@
 |-
 ! 3
-|align="center"|Top disk holder
+|align="center"|Key geometric, inertia, and material properties
-| align="center"|Support Element
+| align="center"|The bore of the bearing is 7 mm, the Outside Diameter is 22 mm, the bearing type is the plain- Double shield, the Material is 52100 Steel, the lubrication is Chevron SR1 #2, width 7 mm and a  Dynamic Load 3300 N.
-| align="center"|Attaches to disk holder to lock grinding disk in place
-| align="center"|Metal
-| [[Image:badtopdiskholder.JPG |center|thumb|50px]]
 |-
 ! 4
-|align="center"|Washer
+|align="center"|Type of Analysis and method of obtaining results. List relevant equations and describe how they relate to the design decisions
-| align="center"|Support Elements
+| align="center"|The major design considerations are the size and strength of the bearing in combination with the force exerted on the shaft. The force exerted on the shaft will probably be known before the bearing is chosen. Hence the only variables in the equation are the dynamic load and the life rating of the bearing. It seems to be common practice that the bearings are rated at a given dynamic load for a life of   s. The Dynamic load depends mainly upon two factors, the dimensions of the bearing and the material composition.
-| align="center"|Attacjes grinding shield to the grinder
-| align="center"|Metal
-| [[Image:badwasher.JPG |center|thumb|50px]]
 |-
 ! 5
-|align="center"|Handle
+|align="center"|Quantitative Results (plots, calculations). How do these relate back to the engineering specifications? How do they verify the quality of the design?
-| align="center"|Structural Components
+| align="center"|This quantity turned to be about 10.26 years if the grinder was used for 6 hours a day 5 days a week. This exceeds the life requirement target of 10 years and reinforces the quality of the design.
-| align="center"|Provides grip and stability for the grinder
-| align="center"|Plastic with metal screw on end
-| [[Image:Blackanddeckerhandle.JPG |center|thumb|50px]]
 |-
 ! 6
-|align="center"|Griding Shield
+|align="center"|What changes could be made to improve the quality of this design with respect to this engineering specification? What trade-offs would this introduce?
-| align="center"|Structural Components
+| align="center"|The major changes that could be made to improve the quality of the bearing would be to increase the strength of the bearing, to increase the size of the bearings, to use higher quality lubrication and to lower the force exerted by the shaft. Lowering the force on the shaft would have a dramatic effect on the performance of the grinder and hence is not very feasible. The only negative to all the other modifications is that making these changes would increase the cost of the grinder and in any engineering decision optimizing cost is always a primary concern.
-| align="center"|Protects operator from any parts that may get grinded off from work material
-| align="center"|Metal with greese lubricant
-| [[Image:blackanddeckerguard.JPG|center|thumb|50px]]
 |-
-! 7
-|align="center"|Transmission
-| align="center"|Transmission
-| align="center"|Transfers energy from horizontal plane into vertical plane for grinding wheel
-| align="center"|Metal with grease lubricant
-| [[Image:blackanddeckertransmission.JPG |center|thumb|50px]]
-|-
-! 8
-|align="center"|Internal Motor Assembly
-| align="center"|Output
-| align="center"|Converts the electrical energy into the horizontal mechanical energy
-| align="center"|Metal, plastic, and ball bearings
-| [[Image:Camera Spindle.JPG  |center|thumb|50px]]
-|-
-! 9
-|align="center"|Outer Motor Assembly
-| align="center"|Input
-| align="center"|Creates the electromagnetic field that provides the power for the tool
-| align="center"|Metal, wires and plastic
-| [[Image:badmotoroutput.JPG |center|thumb|50px]]
-|-
-! 10
-|align="center"|Transmission Casing
-| align="center"|Structural Components
-| align="center"|Attaches the transmission to the motor and allows the shaft and transmission to run smoothly
-| align="center"|Metal Composite with grease lubricant
-| [[Image:badtranscase.JPG  |center|thumb|50px]]
-|-
-! 11
-|align="center"|Washer
-| align="center"|Support elements
-| align="center"|Attaches the motor to the gears.
-| align="center"|Metal
-| [[Image:badwasher.JPG  |center|thumb|50px]]
-|-
-! 12
-|align="center"|Hypoid Gear
-| align="center"|Motion Conversion Elements
-| align="center"|Transfers power from shaft to transmission.
-| align="center"|Metal
-| [[Image:badhypoidgear.JPG  |center|thumb|50px]]
-|-
-! 13
-|align="center"|Drill handle and electrical circuits
-| align="center"|Input and support elements
-| align="center"|Provides the electrical power to the motor and turns the grinder on and off.
-| align="center"|Plastic and Electrical Circuits
-| [[Image:Dissectedblackanddeckergrinder.JPG  |center|thumb|50px]]
 |}
 <embed src="http://www.youtube.com/v/Ocex8YbNa_o" type="application/x-shockwave-flash" width="425" height="350"></embed>
 [[media:badawesomegear.avi|Right-click here and select "Save Link As" to download the video (.avi)]]

@@ Line 11: / Line 11: @@
 The purpose of this Wiki is to give the reader insight as to why this grinder works, through the use engineering specifications.
-== Why It Works ==
+==How It Works==
 Inside the grinder there is an electric motor that spins a shaft connected to a bevel gear.  The bevel gear is then attached to another driving shaft.  A grinding wheel is clamped onto the driving shaft, causing the grinding wheel to spin.
 Every component in the assembly has a life expectancy due wear generated by constant friction and other forces acting on the parts.  This expectency varies between individual parts based on the location, direction and magnitude of the forces acting on the part and also the geometery and material compositon of the part.
@@ Line 25: / Line 27: @@
 ==Parts==
-The table belows lists the Bill of Materials for the disposable camera:
+The table belows lists the Bill of Materials for the Black and Decker Grinder:
 {| border="1" align="center"
-|+ '''Table 3.1: Disposable Camera Bill of Materials'''
+|+ '''Table 1: Black and Decker Grinder Bill of Materials'''
 ! width="50"|Part # !! width="100"|Part Name !! width="50"|# Category !! width="120"|Function!! width="145"| Material !! width="100"|Picture
 |-
@@ Line 123: / Line 125: @@
 |}
 [[Image:caddrawings.jpg|Figure 2: CAD Drawings]]

@@ Line 123: / Line 123: @@
 |}
-[[Image:caddrawings.jpeg|right|thumb|300px|Figure 1: Fully dissected product]]
+[[Image:caddrawings.jpeg|Figure 2: CAD Drawings]]
 <embed src="http://www.youtube.com/v/Ocex8YbNa_o" type="application/x-shockwave-flash" width="425" height="350"></embed>
 [[media:badawesomegear.avi|Right-click here and select "Save Link As" to download the video (.avi)]]