Drill Examination

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Contents

Product Examination

Purpose:

The purpose of gate 3 is to discuss the subsystem components by gathering as much information as is possible. The following sections and information will be gathered, discussed, and analyzed in this presentation.

Project Management: this portion will update the reader on how well the group is working together as a team. Any issues in this regard will be presented here.

Component Summary: This section will identify the various components within the produce. All manufacturing data will be recorded, and the actual manufacturing processes will be analyzed.

Product Analysis: The engineering design decisions behind seven subsystem components will be analyzed, and discussed.

Solid Modeled Assembly: A solid modeling program of choice will be used to make a three dimension model of four to five components.

Engineering Analysis: A key component or function will be chosen, and an explanation of how engineering analysis would have been used in the development and testing of the component will be discussed.

Design Revisions: Observations made in dissection the drill will not be put into application of how the drill can be improved. Three main revisions will be made based on performance, cost effectiveness, and GSEE factors.

Cause for Corrective Action

Our group has worked well together so far this semester. For this gate we decided that the most convenient method to tackle the project was to assign each group member one of the sections stated in the purpose statement. This allowed each member two and a half weeks to tackle their assignment, and discuss any issues with other members of the group. This being the case we have not had any issues with this approach. The deadline to hand the assigned portion of the project is two days before the gate is due. This allows enough time for the Wiki editor to create a professional presentation.

Component Summary

The following component summary table will summarize the components used in the drill, and also give a quick overview of the manufacturing used to produce them.

Component Summary Table
Part Name Description Manufacturing Reason for Materials Reason for Shape Forces Applied Functional/
Cosmetic
Quantity Complexity Picture
Washer Holds the torque adjuster to the rest of the drill, separates the ball bearings from the falling out of their bearing holes, separates the gear assemblies Sheet metal stamping Steel because of its availability and to keep down cost Standard Normal forces applied from the materials that the washer is separating Functional 3 1 Washer100.JPG
Ball Bearings Allows the chuck to gear assemblies spin almost frictionaly from the clutch Cold forged in dies Steel because of demand for strength and durability Standard Mostly compressive forces as ball bearings create a frictionless turning surface. Functional 6 1 Ballbearings100.JPG
Gear Shifter Shifts a gear between a lower gear ratio for high torque, and a higher gear ratio for higher speed Machined Steel because of demand for rigidness Allows for easy shifting back and forth in linear direction Normal force to slide the shifter between gears Functional 1 1 Gearshifter100.JPG
Spring Applies tension towards the gear shifter to keep it form moving freely Coiling Steel because its common and has a consistent elastic modulus with life cycle Coil shape because of the principles of a spring Mostly compressive forces in design Functional as it keeps the spring in place 1 1 Spring100.JPG
Motor Cage Holds the motor to direct power into the gear assemblies Plastic injection molding Plastic because it is easy to mold, inexpensive, and also absorbs any motor vibrations Circular to form to the shape of the motor None Functional as it holds the motor in place 1 1 Motorcage100.JPG
Sliding Gear Gear that slides between the higher and lower gear Plastic injection molding Plastic possible for easier shifting with lighter weight than metal gear Circular so that it can easily switch between the gear assemblies None Functional as it is the gear that changes between the low and high gear speeds 1 1 Sliding gear.JPG
Clamshell Casing Used for housing the components of the drill The casing is made from plastic injection molding Plastic is used because it is easy to mold and easy to make intricate designs The plastic is molded in a way to give a more ergonomic feel to the user while operating the drill User applies normal force into the trigger style handle and helps keep the drill in place The part if both functional and cosmetic. Illustrating the name plate and company logo, as well as housing most of the components 2 1 Casing100.jpg
Switch Assembly Switch for controling the power in the circuit The switch house is made from plastif injection molding and the copper wire is shapped drawn into a wire The plastic used for the injection molding is easy to mold and design, and the copper in the wires is a great conductor The switch assembly is cubical to fit tightly within the clamshell set and not move around. The copper wires are thin to be able to be routed through the drill User applies normal force to pull in trigger to operate the drill The part is functional as it completes or breaks the circuit to power the drill 1 2 Switch100.jpg
Screws Used to hold components together as well as the clamshell casing and switch component Thread rolling is used The steel screws provides good structural integrity The standard shapes are used none Functional as they hold the casing and other parts together 25 1 Screws100.JPG
Electric Motor Turns electrical energy into magnetic energy imported from the battery. It turns magnetic energy into rotational energy. The current in the wires of the field creates a magnetic field near the armature and causes a force Composed of a field and armature assembly. The housing is machined for maximizing cost and time efficiency. The armature was made by milling and turning due to the precision need for the armature shaft to fit in the field casing and rotate freely without any friction. The copper coil is made by shaping and wound around the armature shaft. Steel was used because it is a tough and strong alloy and can withstand the torque provided by the field assembly. Copper is used for the wiring because of the low resistance and to maximize the cost effectiveness. The armature is cylindrical so that it can rotate freely and be place with ease into the field casing. The housing is circular in shape which has a cylindrical hole in its center to properly house the armature and deliver a magnetic field. The armature assembly is subject to torque provided by the field assembly Functional as it is what delivers power through the gear assemblies that powers the chuck of the drill 1 4 Motor100.JPG
Gear Assemblies Used to deliver power from the motor to the chuck Milling and injection molding is used to manufacture the gears Steel is used due to it's strong integrity and its ability to efficiently deliver power to the. Plastic because it relieves stress throughout the assemblies The standard gear shape is used, due to the easy manufacturing process and efficiency The torque applied to the gears from the electric motor which applies torque to the chuck Functional as it delivers power to the chuck 2 3 Gears100.JPG
Keyless Chuck A clamping device with three hand-adjusted jaws that hold a bit in the drill. The plastic is injection molded while the steel is die cast and machined The injection molding is an inexpensive method of producing a high volume of chuck shells while die casting and machining that provide a strong core and grip the bit well. Circular due to it's rotational motion and to easily attach and lock in new drill bits Torque from the rotating gears and any additional normal force from the user Functional as it holds the bit in place 1 2 Chuck100.JPG
Clutch The clutch has one shaft driven by the motor and the other drives a drill chuck. The clutch connects the two shafts so that they can either be locked together and spin at the same speed, or be decoupled and spin at different speeds. The plastic housing is injection molded while the steel plates are stamped. The ball bearings are cold forged in dies The plastic in for the casing is used to keep down the cost and the steel for the clucth plates and ball bearings are used because of its strength and durability Rotational motion demands a circular clutch. Frictional forces from contact with gears. Functional as it prevents the user from using too much force while drilling in screws or damaging the inner gear assemblies 1 3 Clutch100.JPG
Torque Adjuster Allows user to adjust the torque setting for the drill Plastic injection molding Plastic because it is easy to form and mold Shape provides easy grip and a convenient change of torque. Normal force from the user to change the settings Functional as it adjusts the torque settings and cosmetic as it shows different pictures for each application 1 1 Torqueadjuster100.JPG

Product Analysis

Trigger

Switch100.jpg

  • Component Function: The trigger is one of the most important components on this drill due to the fact that it is the component that the user interacts with most frequently. The function of this component is to allow the user to use the drill, and that being said, the trigger performs only this function in this drill.
  • Component Form: The general shape of the component is roughly that of a rectangle. There are no truly notable properties of the trigger, and it is primarily a three dimensional component. The dimensions for the trigger are roughly (as seen looking at the side of the drill): Length: 3 cm, Width: 2 cm, and Height: 4 cm. The rather large, and generic shape of the component allows for moderate ergonomic comfort for a wide variety of users. The rough weight of the trigger is about 100 grams, and it is made out of plastic. Manufacturing the trigger from plastic was a good idea because the shape is not overly complicated, and an injection mold would not have been tremendously complicated to make for the trigger. Of the four GSEE factors that were used to design this trigger the economic factor would weigh most heavily. Making the trigger out of plastic (as opposed to metal or ceramic) keeps the material, and manufacturing cost of the component low. There is no aesthetic purpose to the component, it is simply there to perform the function of a trigger.
  • Manufacturing Methods: The manufacturing method most likely used for this part is that of injection molding. There are ejector pins on the inside of the trigger body that would incline one to suspect this manufacturing method. Since the material is plastic this method would make the most sense given the geometry of the part.

Battery

Battery1001.JPG

  • Component Function: The function that the battery performs Is to deliver power to the motor which allows the drill to perform its fastening function. This is the only function that the battery performs, and the flows associated with it are electrical energy flowing to the motor. The battery is attached to the bottom of the drill so the environment functions in are whatever environment the consumer chooses to use the drill.
  • Component Form: The general shape of the batter is that of a rectangular cube. There are no notable properties about the battery, and it is primarily three dimensional. The dimensions of the battery are as follows: Length: 15 cm. Width: 7 cm. Height: 6 cm. The component roughly weighs 450 grams, and the material of choice for the battery is primarily plastic. The plastic body serves as a convenient material from a manufacturing and cost stand point (cheap, and easy to manufacture). The environmental factors that influenced this design is due to the fact that the plastic is a robust form. This allows the user to operate the drill in adverse conditions without having to worry about corrosion or destroying the battery because of dropping it on the ground etc. The color of the component is black, and the reason for this is that it nicely compliments the orange casing of the drill, and allows the consumer to see that it is a Black and Decker drill quickly.
  • Manufacturing Methods: The most likely manufacturing method used was that of injection molding. This is evidenced by parting lines that show where the battery casing came together around the internal workings of the battery. The material choice is plastic , and since the geometry and dimensions are not overly complex the most cost efficient method is that of injection molding.

Casing

Casing100.jpg

  • Component Function: The function of the body casing is too contain, or attach all the components of the frill (motor, trigger, chuck, etc.). The casing has two primary functions: contain/attach all other components, and give a good ergonomical grip for the consumer, and as such there are no flows associated with the component.
  • Component Form: The shape is roughly that of a pistol, and has no notable properties. It is also primarily three dimensional. The dimensions of the drill are: Length of base: 15 cm. Height (when stood up by it’s base): 35 cm. Width: roughly 10 cm. The components shape is primarily ergonomical. It allows the user to comfortably grip the product, and use it for it’s intended purpose. The component is rather light and weighs roughly 275 grams. The component is made from mainly plastic, but also has portions that are rubber for increased user comfort. Again, the easiest way to manufacture this component is through the use of injection molding. There is no specific material required for this component as there are drills that are also made from metal, however the plastic serves as a more economical material and keeps the manufacturing and thus the consumer cost down. The component is colored a mix of bright orange and black. This is simply to allow the component to quickly be identified as a Black and Decker drill.
  • Manufacturing Methods: There are ejector pins and parting lines which give weight to the idea that indeed injection molding used to manufacture this component. The shape is rather complex, and therefore the best way to achieve the desired geometry was to utilize the injection molding process.

Slip gear

Sliding gear.JPG

  • Component Function: The main function of the slip gear is to engage one of two sets of gears that vary the speed of the drill. This is the only function of the drill. The component is a high temp environment as the gears are constantly spinning at relatively high rpms.
  • Component Form: The shape of the component is circular with gear teeth on the inner, and outer portion of the ring, and it is primarily a three dimensional component. The shape must be circular as the design is that of a planetary gearing system where the ring moves between the two gears at the users discretion to adjust the speed of the drill. The outer diameter of the gear is 3.5 cm and the inner diameter is 2.5 cm. The depth the gear is about 2 cm. The component roughly weighs 45 grams, and the material of choice is a high quality plastic. The plastic stands out from the rest of the plastic in the drill due to the fact that the component sees higher temperatures and more wear and tear through the life cycle of the drill. This is purely a performance decision. Environmental factors were present in the design due to the fact that it would be in a much more rough operating condition than any other plastic part in the drill. There is no aesthetic purpose to this component as it is hidden within the drill.
  • Manufacturing Methods: From inspecting the component it appears that it was made in an investment casting. It was a much higher tolerance mold as parting lines are non existent.

Slip Gear Spring

Spring100.JPG

  • Component Function: The function of this component is to create an interface between the user and the gearing system within in the drill. The spring is attached to the slip gear, and is the mechanism by which the slip gear engages one of the two gearing systems within the drill. This is the only function of this component. The environment of the spring is within the drill, so it does, presumably, see higher temperatures than the external portion of the drill.
  • Component Form: The general shape is hard to describe, but it is basically a rod with two prongs at the end which go out at a 45 degree angle from the rod (when looking from the side). It is axial symmetric, and one of the more intricate and interesting components of the drill. It is primarily a three dimensional component. It is roughly 7 cm in length. The shape is necessary so that the user can move the spring at the top of the drill, and the slip gear can oscillate between gearing systems within the drill. The component material appears to be a medium grade steel. The properties of this component are that it must be fairly robust. It has to withstand the slamming of the user from gear to gear without shearing, and ceasing to function as a gear shifter. Steel is good for this purpose as it has a relatively high tensile strength, but is also fairly ductile. This would be an environmental design decision. It also falls under the economic GSEE factor due to the fact that steel is a fairly inexpensive material (not as inexpensive as plastic, but still on the cheaper side none the less). The component has no aesthetic purpose as it is hidden within the drill, however, the color is a generic silver metallic.
  • Manufacturing Methods: The manufacturing method most likely used to create this part was most likely metal forming. The material choice and shape of the component makes this the most likely manufacturing process used. This is because the shape could simply be cut to the rough dimensions, and then bent into the desired shape through the use of a die. This is a less expensive alternative to creating a mold for the part.

Motor

Motor1001.JPG

  • Component Function: The function of the motor is to convert electrical energy delivered from the battery, and convert it into torque which allows the drill to fasten objects. This is the only function of this component. The flows associated with this component are electric energy flow entering the motor and mechanical energy exiting the motor, and traveling to the bit. The environment of the component is that of high temperature. The spinning caused by the rpm generating ability of the motor will create high temperatures within the operating environment of the drill.
  • Component Form: The general shape of the component is cylindrical, and it is axially symmetric for the most part. There are odd shapes here and there, but overall it is axially symmetric, and it is primarily three dimensional. The diameter of the component is 5 cm, and the depth of the component is roughly 10 cm. The weight of the component is roughly 400 grams. The primary materials for the motor are aluminum with copper. Copper is specific to motors due to the fact that it is necessary to generate torque from electrical energy entering it. There are no aesthetic purposes to this component as it is concealed within the drill. The component is a silver/metalic color, and has a rough metal surface finish.
  • Manufacturing Methods: The most likely manufacturing method to make this part would be die casting the aluminum motor body, and wire drawing the copper within the motor. Creating copper wire is a standard process in which they use wire drawing, and there are riser marks on the aluminum body which lend credence to the die casting method.
  • Component Complexity: This is the most complex component within the drill due to the fact that it requires multiple manufacturing methods (die casting and wire drawing) to create the single component. The number of materials, and the amount of flow moving through it also make it the most complex piece in the product.

Bit Chuck

Chuck100.JPG

  • Component Function: The function of the bit chuck is to be a receptacle for the bit. The flows associated with the component are the at of mechanical energy. The energy flows from the motor and allows the bit to spin and fasten objects.
  • Component Form: The general shape of the component is that of a cone. It is axially symmetric, and it is primarily three dimensions. The dimensions are length: 7 cm. Large diameter: 6 cm. Smaller diameter at the top: 2 cm. The component weighs roughly 140 grams. The component is made primarily out of plastic with the inner portion where the bit is fastened being made of metal. The metal within the chuck is necessary to keep a good grip on whatever bit the user decides to place within the chuck. Environmental factors where key in designing this component since the inner portion of the chuck will have to accurately fasten the metal bit without allowing it to slide out. The component has no aesthetic purpose although it is painted black to match the color scheme of the rest of the drill.
  • Manufacturing Methods: The manufacturing methods for this component are as follows: The plastic portion of the chuck was injection molded while the metal inner workings were most likely die cast. The fact that the outer is plastic supports the theory of injection molding while the metal on the inner portion supports that of die casting.
  • Component Complexity: While the outer plastic portion of the drill is not a complex shape the inner workings of the chuck are in fact much more complex. The interactions of the inner chuck are quite complex because it is a fastening mechanism that allows the user to tightly hold the bit in place.

Solid Modeled Assembly

The reasons for choosing these three components are because they are one of if not the most important components that the drill uses to perform its function. These three gears form one gear assembly which is used and appears three times in the drill in conjunction with each other and the motor of the drill. The motor of the drill spins these sets of gears depending on which torque setting is selected and this makes these three components vital in the operation of the drill.

We used AutoDesk Inventor for our CAD package. The reason we chose this is because one of our group members has a fair amount of experience in Inventor. He took classes three separate years in high school and has a good understanding of how Inventor works.


Gear100.jpgGear200.jpgGear300.jpgGear400.jpg

Engineering Analysis

1. Problem Overview:

  • What function or component can turn electrical energy into mechanical energy?
  • How much torque will this component have to put out?
  • How fast will this component need to rotate?
  • How efficient should this component be?
  • What size will the component need to be in order to fit into the design of the drill?

2. Diagram:

Motordiagram.jpg

3. Assumptions:

  • Friction is neglectful.
  • 12 volts from battery is constant.
  • Energy is conserved.

4. Governing Equations:

  • T = P x 9.554 / n

9.554 = Constant based on SI units [1]
T = torque (Nm)
PW = power (watts)
n = revolution per minute

  • efficiency=Power out(watts from shaft)/Power in(watts from battery)

5. Calculations

  • An engineer would take into account the torque that a drill of an average consumer would need. According to blackanddecker.com this drill has a motor with a torque of 130 in-lbs. It also lists the top rpm as 1200. An engineer would consider a suitable torque range and max rpm acceptable to perform the functions expected by this drill. Not only would this motor have to meet these requirements but would also have to meet the size requirements to fit well into the mold. The electrical energy supplied by the battery is also only 12 volts with a maximum compacity of 500 recharges which means that the engineer would need to choose a fairly efficient motor that does not have a huge draw on the battery.

6. Discussion

Here is a list of all the qualifications that can be considered by the engineer in deciding on which motor to use.

  • A range of torque values are established.
    • Range is from minimum to maximum torque.
    • Range is most likely based on hands on testing with different types of screws and materials being screwed into.
      • Material and screws based on average needs in households since the target audience is the common household/handyman.
  • A range of rpm values are also established.
    • There is a need for a motor that handles variable rpms well.
    • Not only is there research into how much torque is needed for a certain screw and material, but also an optimum rotational speed is developed as well.
  • This motor must meet a certain efficiency level.
    • The power source is 12 volts and has a maximum capacity which means that the motor cannot draw too much power to drain the battery quickly just to meet the torque and rpm ranges.
    • An engineer would also have to take in surveys or do hands on tests of how long they want this drill to last between recharges.
  • This motor must not be too heavy nor take up too much space.
    • The idea behind a household drill is that it is compact, lightweight, and does the expected jobs around the house with ease.
    • Consider the cylindrical size constraints and motor weight range based on making this drill as compact and lightweight as possible.

Design Revisions

Design Revision Table
Original part/setup Revision GSEE reflection Strengths Weaknesses
Electric Motor
(Carbon brushes)
Brushless Motor Economic: Fewer charges from battery with more efficient motor
Longer lasting motor provides less waste with fewer thrown away drills from broken motors.
Environmental: More durable motor and longer lasting power through greater efficiency decreases terrain vulnerability of breaking and running out of power.
Greater torque
Up to 50% less demand on battery
less repair because motor lasts longer
lighter motor
quieter
cost increase by 15%
No cognitive assistance light and level Societal: A light and level attached to drill can offer the consumer an innovation that can be seen and advertised as convenient.
Environmental: A light can provide convenience in conditions of low light.
A level can provide convenience in areas where being level is impertinent such as drilling or screwing upside down.
Illumination
Cognitive assistance
Uses some battery power in led light
Adds an estimated 10% increase in cost
Basic NiCad battery Lithium Battery
with life indicator
Societal: Lithium battery especially with life indicator contributes as a good selling feature
Economic: Battery lasts longer and requires fewer charges than original
Contributes to fewer thrown away drills from dead batteries.
Environmental: Drill can be taken to locations without as much worry about recharging.
Life indicator allows consumer to know when he must recharge it, which would provide more versatility of use.
Lighter
Longer usage
Life indicator convenience
No memory effect (sustains maximum battery life)
Very little loss of charge when not in use.
cost increase by 15%