Difference between revisions of "Group 3 - Black and Decker Drill"

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(Design Changes on the Component Level)
(Operation)
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===Operation===
 
===Operation===
  
The drill works by converting power from the AC power cord and changes it to mechanical energy to rotate the spindle and motor.  This allows for mechanical energy to be produced to rotate the chuck to allows the drill to operate. Also a magnetic field exists between the stator and the armature. This allows for a current to be produced in the field, which in turn produces a voltage that is controlled by the trigger. This controll allows for the variable speeds of the drill.  The commutator allows the drill to run on direnct power (DC) instead on alternating (AC) power. It does this by periodically reversing the direction of the current produced by the motor.  This produces rotational motion that is transfored along the spindle to the chuck.  The reverse switch allows for the change in direction of the current which in turn changes the direction that the chuck rotates in.  The fan on the spindle allows for the constant cooling down of the gears and other rotating parts.
+
The drill works by converting electrical energy from the AC power cord to mechanical energy to rotate the spindle and motor.  The now mechancial energy allows the chuck to rotate and the drill to operate.. Also, a magnetic field exists between the stator and the armature. This allows for a current to be produced in the field, which in turn produces a voltage that is controlled by the trigger. This control allows for the variable speeds of the drill.  The commutator allows the drill to run on direct power (DC) instead on alternating (AC) power. It does this by periodically reversing the direction of the current produced by the motor.  This produces rotational motion that is transfored along the spindle to the chuck.  The reverse switch allows for the change in direction of the current which in turn changes the direction in which the chuck rotates.  The fan on the spindle allows for the constant cooling down of the gears and other rotating parts.
  
 
===Analysis Discussion===
 
===Analysis Discussion===

Revision as of 22:25, 7 December 2006

Contents

Executive Summary

We disassembled, analyzed, and reassembled a Black & Decker power drill. This drill is a DR 202, 120 V, 50/60 Hz, 5 A, 0-1350 revolutions per minute power drill

We took each component of the drill apart and analyzed it to determine the function and why each part was made of it material and shape. This helped us better understand how the drill worked on the component level.

By analysis and research, we were able to determine what each component was, and produced CAD drawings and pictures of each component. After all this information was gathered, we reassembled the drill.

Assembly was fairy easy and basically the reverse of the dissassembly process.

After we disassembled, analyzed, and reassembled the Black & Decker power drill we gained a better comprehension of how the drill worked.

Introduction

This product is a Black & Decker Drill which is designed to use different size bits to drill holes in various materials. The drill runs by changing electrical energy into mechanical energy inside the drill motor. The drill also has a reverse function.

Each member was responsible for the following parts of the project:

Shawn Lazarus (Disassembly & Presentation)

Christopher Sendlak (Group Leader, Dissassembly & Reassembly & Manufacturing Processes)

Angela Davis (Reassembly & Web Site)

Jennifer Tewes (Disassembly & Reassembly & Web Site)

Jerry Theresanathan (Disassembly & Pictures & Presentation)

Before Disassembly

Purpose

The Black and Decker Drill is used to drill holes into various materials (ie. wood, sheetrock). The drill uses an AC current from a wall and directs electricty to a motor to create rotational motion. This motion is transferred to the gears in order to create rotation within the drill bit.

Operation

The product works and runs smoothly by changing AC power from a power outlet into mechanical energy in the drill to turn the bit. This is demonstrated best when the drill's trigger is pulled because you can hear the motor and the cooling fan rotating.

Amount of Components

We estimated that the drill is made of approximately ten components. These ten components include:

  1. Motor
  2. Trigger switch
  3. Cord
  4. Drill bit
  5. Level
  6. Cooling fan
  7. Casing
  8. Direction switch
  9. Trigger lock
  10. Chuck
  11. Screws
  12. Gears

Types of Materials

We estimated that the drill is made of approximately five materials. These five materials include:

  1. Plastic
  2. Rubber
  3. Steel
  4. Copper wiring
  5. Water (Liquid in level)

Disassembly Procedure

Disassembly Process Table

Step Number Process Tool Level of Difficulty
1 Unscrewed screws to remove plastic casing (housing) # 15 Torque Driver/Phillips Head Screwdriver Easy. Required minimal force to remove screws. Housing than fell apart in two pieces
2 Removed electrical cord by unscrewing screws # 15 Torque Driver/Phillips Head Screwdriver Easy. Required minimal force to remove screws once the wires were exposed
3 Removed reverse switch that fits into hole at the base of the motor Hands Very Easy. Simply pulled out of the hole
4 Removed circuit box and its parts (two springs, metal strips, wires, silicon chip) Pliers and Alan Key Hard. The circuit box is very small making it hard for the removal of the small pieces inside of the circuit box
5 Separated drill bit, motor, gears, and magnetic field Hands Easy. All parts were easy to seperate once they were free from the housing
6 Separated and removed small brushes Hands Easy. Brushes pushed out of thier holders with minimal force
7 Unsnapped plastic casing around magnetic field Hands Medium. The casing was pressed together tightly making it difficult to remove
8 Unscrewed large screws on magnetic field # 15 Torque Driver/Phillips Head Screwdriver Easy. Once the field was exposed the screws were easy to see and required minimal force to remove
9 Unlocked the wire locks Hands Easy. Simply twist wire locks apart
10 Removed plastic ring that included two wires Hands Easy. Simply pull the ring with wires away from the field

After Disassembly

Part Table

Part Number Part Name Number of Parts of This Type Part Material & Reason for Material Function Reason for Shape Part Manufacturing Process Image of Part CAD File
1 Housing 1 Plastic
Non-conducting to shield user from electricity and moving parts inside
Rubber (grip)
Comfort to user
To contain all components, and make the drill user-friendly To contain all of the components inside and to allow the user to easily use the drill Injection Molding
MAE pics 007.jpg
2 Screws 11 (Casing Screws) 2(Long Screws) Metal
Strength and longivity of part
Holds separate components together Phillips head to allow for easy alignment during manufacturing Machined
MAE pics 062.jpg
3 Level 1 Plastic (externally)
Strengh and durability
Liquid (internally)
To allow for the bubble to balance in the liquid
Shows the user if the drill is being held horizontally To effectivly allow for the bubble to be read easlily and to show if the drill is horizontal Injection Molding
MAE pics 055.jpg
4 Keyless Chuck 1 Plastic (externally)
Comfort of use for user
Steel (internally)
Stength and longevity
Place for the bit to be held To allow for the drill bit to be held in place easily Injection Molding and Machined
MAE pics 039.jpg
Drill Head assembly 2.jpg
5 Wiring 1 Copper
Conductor of electricity
Plastic (insulation)
Shield other components from electricity
Supplies power to components To supply enough power to the components but also small enough to fit into tight spaces in the drill Extruded
MAE pics 061.jpg
6 Cord 1 Plastic (externally)
Shield user from electrcity
Copper wiring (internally)
Conductor of electricity
Supplies power to the whole drill Allows for the cord to be flexible and fit into a standard power outlet Extruded
MAE pics 052.jpg
7 Trigger 1 Plastic
Sheild user from electricity on the inside
Contolls the speed Easily conforms to the users fingers to allow for easy use Injection Molding
MAE pics 054.jpg
8 Chip 1 Silicon
Condutor of electricity and computational power
Controls the power supply Allows for efficient power control Silicon Dipping Implantation
MAE pics 013.jpg
9 Armature Coil 1 Copper
Conductor of electricity
Allows for the generation of power Many coils to more effectivly produce current Copper wire wound around central axel(Insulated)
MAE pics 037.jpg
10 Commucator 3 Metal
Strength and durability
Allows tranfer of electricity in the coil of the central axis Cylindrical and formed around the axial to be able to connect effectivly to the field and the axial which allows for the rotation of the components Sheet Metal Forming and Machining
MAE pics 038.jpg
11 Reverse Switch 1 Plastic
Strength and comfort for user
Changes the direction that the chuck rotates in Allows of eas of use by the user and to efficiently switch the direction of the current. Injection Molding
MAE pics 053.jpg
12 Armature Axel 1 Metal
Strength and durability
Allows for motor rotation Allows for easy rotation because it is a cylindrical shape Machined
MAE pics 034.jpg
13 Cooling Fan 1 Plastic
Light weight and durability
Draws air into the drill to cool down the motor Fin shape to sufficiantly draw air over the drill components Injection Molding
MAE pics 030.jpg
14 Field 1 Copper
Conductor of electricity
Allows for power genetration from the motor Many coils allow for the effective generation of power Copper wire wound on Injection Molded plastic encased in formed sheet metal
MAE pics 041.jpg
15 Heat Sink 1 Metal
Strength and longevity
Regulates the rotation of the spindle, aides in dissapation of heat Ridges to control the rotation and the holes to allow for heat to escape Die Cast
MAE pics 033.jpg
16 Armature 1 Metal
Conductor of electrcity
Facilitates transfer of power from the coil Circular to encase the coil and to effectivly transfer the electriity to the otehr components Die Cast
MAE pics 037.jpg
17 Cord Clamp 1 Metal(Aluminum)
Durability
Holds the cord in place To hold the wires down without beiing bulky to get in the way of other components Sheet metal forming
MAE pics 059.jpg
18 Casing of copper coil and metal rings 1 Plastic
Light weight and non-conductor of electricity
Protects and insulates the coil Formed around the field to contain the the electricity that the field forms Injection molding
MAE pics 060.jpg
19 Brushes 2 Carbon
Longevity to withstand repeated friction
Contact commuter determines drive direction To make efficient contact with the commutator Machined
MAE pics 056.jpg
20 Brush Holders 2 Metal(Brass)
Strength and longevity to withstand friction
Hold the brushes stationary To effectivly hold the brushes in place Sheet metal forming
MAE pics 046.jpg
21 Coil Springs 2 Metal
Conductor of electricity
Regulates power supply to the brushes Spring shape efficiently regulate power to the brushes Sheet metal forming
MAE pics 046.jpg
22 Gear and Pinion 3 Metal
Strength and Durability
Transfers motion to the chuck To allow for maximum amount of rotational motion transfer along the drill head Extruded
MAE pics 058.jpg
Small Gear Assembly.jpg
23 Plate 2 Metal
Strength and longevity
Holds the gears in place To hold all of the gears in place without causing unneccesary friction Die Cast
MAE pics 063.jpg
Large Plate.jpg
24 Cloth Washer 1 Cloth
Good cushion to prevent parts from rubbing together
Reduces friction due to the rotating gears and chuck Circular to fit on the axial and thick to cushion the rotating parts from each other Machining
MAE pics 028.jpg
Large washer.jpg
25 Magnetic Insultator 1 Cardboard
Insolator
Insulates the copper coil from outside interference Inside of the coil and shaped like the coil to insulate the coil and to minimize space taken up by the insulator Machining
MAE pics 045.jpg
26 Circuit Box 1 Plastic
Insulator of electrcity
Controlls the speed of motor To contain all of the internal components effectivly in as small of a space as possible Injection Molding (casing) Machining(Inside components)
MAE pics 016.jpg

Drill Head and Gear Box Assembly

Part Name Picture CAD File
Whole Front Assembly
MAE pics 022.jpg
Front assembly 2.jpg
Drill Head Assembly
MAE pics 040.jpg
Drill Head assembly 2.jpg
Gear Assembly
MAE pics 028.jpg
Gear assembly.jpg
Gear and Plate Assembly
MAE pics 021.jpg
Plate gear assembly.jpg
Small Gear Assembly
MAE pics 021.jpg
Small Gear Assembly.jpg
Small Gear
MAE pics 021.jpg
Small gear.jpg
Small Washer
MAE pics 021.jpg
Small washer.jpg
Small Plate
MAE pics 021.jpg
Small plate.jpg
Large Gear
MAE pics 021.jpg
Large gear.jpg
Large Washer
MAE pics 021.jpg
Large washer.jpg
Large Plate
MAE pics 021.jpg
Large Plate.jpg


Design Changes on the Component Level

A change that could be made on the component level of the drill would be to mold the bit holder and level into the plastic housing. This could be accomplished by setting holder and level to one side of the two housing halves, because in the current design the bit holder and the level are placed between the two halves of the housing. This would be advantagous because these pieces would not be able to slide around in their current slots, and it could also decrease assembly time. Unfortunately, there are no components on the inside of the drill that could be combined because most of the parts need to rotate seperatly to allow the drill to function.

Assembly

Assembly Process Table

Step Number Process Tool Level of Difficulty
1 Connect Chuck to Gears and Plate. Place in Housing Hands Easy. Just place parts together and set into housing
2 Attach Brushes into Brush holders Needle nose pliers Hard. Needed to pull springs back to attach brushes
3 Connect wires to straiter and armature Hands Medium. Make sure wires are correctly aligned and attached to the field
4 Using the long screws, connect motor and commuter together # 15 Torque Driver/Phillips Screwdriver Hard. Needed to make sure all parts were aligned, which was difficult due to the lack of visability
5 Attach trigger to the housing Hands Easy. Just place in the hole in the housing
6 Connect wires from straiter and armature to the trigger Hands Easy. Make sure that the wires are connected into the corrent holes
7 Connect cord to wires Hands Easy. Make sure that like wires are connected to each other and simply twist ends together
8 Screw wire clamp over the wires from the cord # 15 Torque Driver/Phillips Screwdriver Easy. Screws are easy to attach becasue of the high visability of the parts
9 Attach reverse switch to housing Hands Easy. Slides into hole
10 Attach level to housing Hands Easy. Simply place in slot on top of housing
11 Attach level to housing Hands Easy. Slide into the hole in the housing
12 Attach bit holder to housing Hands Easy. Slide into hole on the housing
13 Fit top half of housing on top and screw two halves together # 15 Torque Driver/Phillips Screwdriver Easy but time consuming to screw in all the individual screws into the casing; also to properly align housing make sure that the wires are out of the way

After Assembly

Disassembly vs. Reassembly Discussion

The disassembly and reassembly process were basically the reverse of each other. It took less time to dissasemble then to reassemble because during reassembly we had to make sure that everything was properly aligned. When the drill was disassembled it basically fell out of the housing once the two halves were seperated. To reassemble the drill it took more time to properly align all of the components. The exact same tools were used for both disassembly and reassembly. The entire drill was able to be reassembled with relative ease but it is suggested that it is not used for an extended period of time because of the grease that was lost form the gears during the disassembly process.

Operation

The drill works by converting electrical energy from the AC power cord to mechanical energy to rotate the spindle and motor. The now mechancial energy allows the chuck to rotate and the drill to operate.. Also, a magnetic field exists between the stator and the armature. This allows for a current to be produced in the field, which in turn produces a voltage that is controlled by the trigger. This control allows for the variable speeds of the drill. The commutator allows the drill to run on direct power (DC) instead on alternating (AC) power. It does this by periodically reversing the direction of the current produced by the motor. This produces rotational motion that is transfored along the spindle to the chuck. The reverse switch allows for the change in direction of the current which in turn changes the direction in which the chuck rotates. The fan on the spindle allows for the constant cooling down of the gears and other rotating parts.

Analysis Discussion

Thermodynamic analysis could be used to determine the threshold condition that will cause the drill to overheat and possibly start on fire. A working prototype of the drill or an actual drill could be used as the model for this test. Stress analysis could be used to determine the wear and tear on the chuck from repeated use. The model for this agin could be a working prototype or actual drill. Another type of analysis that could be is strenth and durability testing on the plastic housing. This is important because the consumer does not want to buy a product that will break the first time it is dropped. A model that could be used for this is a working prototype can be used to model this test.

Design Changes and Recommendations

A design change would be to have another handle on the drill along the chuck. This would provide more stability for the user because most of the wieght of the drill is above the handle, making it top heavy and awkward to hold. This extra handle would allow for the user to more easily support the drill. This handle could be removable so that consumer who do not lke this extra handle or if the handle will get in the way then the consumer could remove it. This could be accomplished with clips on the casing that this extra handle could be attached to. Also the drill could have a cord that is retractable, this would allow the user to determine how much cord they need to have. Another feature that could be changed is allowing the chuck to fit various size bits. This would allow the user to customize the drill to it their own specifications. This can be accomplished by having the option for the user to change the chuck to hold one that could use a larger sized bit. At a marketing standpoint this is a good ploy because the company will be able to make more money off of the different chucks that they sell. From the consumers view this is also good because it means they can own one drill that can use many different bit sizes for all their drilling needs. Also the company could make the housing from recycleble plastic. This is a way to cut down on material cost for the company because it they could recycle the plastic from old or broken drills. This could be accomplished by having consumers return their broken drills for a discount or some other marketing ploy. These could make the drill a more desirable product for consumers which in turn would make the company more productive.

References

Black & Decker. (2003). Instruction Manual for Models DR201, DR202, DR211, DR220, DR403, DR501 and DR601. Towson, MD: Author.

Commutator (electric). (2006, September 18). In Wikipedia, The Free Encyclopedia. Retrieved 14:06, November 22, 2006, from http://en.wikipedia.org/w/index.php?title=Commutator_%28electric%29&oldid=76368620