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 the component was. We also produced CAD drawings and pictures of each component. After all this information was gathered we reassembled the drill.

Assembly was fairy easy and the 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 works.

Introduction

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

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

Lazarus,Shawn ()

Sendlak,Christopher ()

Davis,Angela ()

Tewes,Jennifer ()

Theresanathan,Jerry()

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:

Motor

Trigger switch

Cord

Drill bit

Level

Cooling fan

Casing

Direction switch

Trigger lock

Chuck

Screws

Gears

Types of Materials

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

Drill Head and Gear Box Assembly

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 off setting 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. Unfortunatly 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 in these parts

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

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.

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.