Mechanical Design (OWN 3A)Long Design

T. J . Gerhold [200834228], T.. Lailvaux[], J. Newbold[], A. Dos Santos[]

4/12/2010

ContentsExecutive Summary...................................................................................................................4

Functional Outline......................................................................................................................5

Product Design Specification.....................................................................................................6

Strength/stress........................................................................................................................6

Distortion/Deflection/Stiffness...............................................................................................6

Wear.......................................................................................................................................6

Corrosion...............................................................................................................................6

Safety......................................................................................................................................6

Friction...................................................................................................................................7

Usability.................................................................................................................................7

Cost........................................................................................................................................7

Weight....................................................................................................................................7

Life..........................................................................................................................................7

Styling.....................................................................................................................................8

Shape......................................................................................................................................8

Size.........................................................................................................................................8

Control...................................................................................................................................8

Thermal Properties................................................................................................................8

Surface....................................................................................................................................8

Lubrication.............................................................................................................................9

Marketability..........................................................................................................................9

Maintenance...........................................................................................................................9

Volume....................................................................................................................................9

Liability..................................................................................................................................9

Recycling................................................................................................................................9

Alternatives..............................................................................................................................10

Advantages and Disadvantages............................................................................................10

Concept Design 1:................................................................................................................10

Concept Design 2:............................................................................................................10

Concept Design 3:............................................................................................................11

Concept Design 4:............................................................................................................11

Selection Criteria and Concept Selection.................................................................................12

Criteria Comparison.............................................................................................................12

Criteria 1:.........................................................................................................................12

Criteria 2:.........................................................................................................................12

Criteria 3:.........................................................................................................................13

Criteria 4:.........................................................................................................................13

Criteria 5:.........................................................................................................................13

Final Score:..........................................................................................................................13

Alternative 1:....................................................................................................................13

Alternative 2:....................................................................................................................13

Alternative 3:....................................................................................................................13

Alternative 4:....................................................................................................................14

Alternative 5:....................................................................................................................14

Performance Simulation...........................................................................................................14

Quantities.............................................................................................................................16

Known Quantities:...........................................................................................................16

Quantities to be determined:............................................................................................16

Calculations:.....................................................................................................................17

Delivery characteristics........................................................................................................19

Feeding System........................................................................................................................20

Safety........................................................................................................................................20

Safety stickers......................................................................................................................20

Design of Machine...............................................................................................................21

Environment.............................................................................................................................21

Ergonomics..............................................................................................................................22

Executive Summary

The problem was posed to design a new and innovative device based on the theme of ‘Motion in Sport’. A combination of SEW Eurodrive and Festo products were incorporated into the design to demonstrate how these products can be used to create and control motion. Thus an investigation was carried out and a gap in the market for fully automated bowling machines where SEW and Festo parts could be utilised was discovered. Following this investigation a fully automated bowling machine was designed where factors such as speed, positioning, accuracy, acceleration, repeatability and cycle time. Energy conservation was taken into account during the design. There is a need for a standardised bowling attack without the requirement of an experienced bowler present or another person to operate the bowling machine. Present day bowling machines need to be operated by someone other than the batsman and thus at least two people are required for practising with a bowling machine. This machine provides an opportunity for a batman to improve their skills without the need of a partner. This is greatly beneficial as this ‘partner’ is generally a very expensive coach. It may also be argued that a coach is necessary to see the batman’s shots to provide support but with the aid of a camera a coach or even the batsman himself is able to view the video at a later stage and thus minimal time is wasted decreasing the cost of expert advice.

The cricket bowling machine was based on the basic pre-existing models however the design was improved by integrating the Festo and Eurodrive products in order to create a new bowling machine that could be operated by the batsman alone. Furthermore a camera was attached to the machine to offer the opportunity for a shot-by-shot review and thus the batsman will be able to play with himself, better his ball strokes and improve his technique.

Thus extensive research took place in the fields mentioned above, these being the SEW Eurodrive and Festo products, cameras and bowling machines. Therefore this was all integrated into our design and a fully automated bowling machine was developed. In depth calculations as well as engineering drawings needed to be completed before the design was finalised. Presented in this report are:

Functional outline Product Design Specification Alternatives Selection Criteria and Concept Selection Performance Simulation (motion & structural) Environment, Ecology, Safety and Ergonomics Professional Engineering Drawings Cost Estimate

Functional Outline

The feeding of the balls so as to eliminate any human effort so that the a single person can utilise the machine will be carried out by a rotating door type feature where a ball rolls into the door, the door rotates and the ball rolls out 180° into the launching mechanism.

The launching mechanism consists of two high velocities, spinning, wheels which grip the ball as it rolls between them, and launches it forward at a high velocity, simulating the bowling action of a real life bowler.

The head piece of the device which holds the launching and feeding mechanisms is able to rotate horizontally via a DSMI unit and also be programmed to rotate positions between deliveries so that the batsman can experience inconsistent bowling which will help improve his skills as this simulates real life situations in a cricket match.

The headpiece of the device is able to change its pitch and delivery balls at different angles so that the batsman can experience a variety of different deliveries such as full, short, good length, etc., so as to help the batsman train for a variety of delivery lengths. The pitch changes are programmable functions so that the batsman does not have to physically readjust the machine each time.

A combination of the horizontal rotation, pitch angle changes and ball speed changes will provide a full range of deliveries for the batman. Once the device has been fully programmed, the batsman then can choose a range of pre-set deliveries and the device can be turned on and off, and the delivery interval can be set via remote that the batsman can keep with him that straps onto his pads so that he can operate the device from a distance.

This product has to be designed to operate as a fully automated bowling machine controlled by the bats man alone, via a wireless control, to simulate all types of possible deliveries. In addition to this a camera is attached to the unit in order to record the performance of the batsman to be analysed at a later stage. The machine can be programmed for a full range of deliveries to the batsman’s need, and can be operated by the batsmen alone. This is an ideal coaching tool. It is difficult for a person to pick up their own mistakes so a camera records each shot so that after a day of batting the batsman can review his/her shots and analyse where improvements can be made in form.

The advantages of this system over conventional bowling machines are: Fully automated Can be operated by a single person Work on a batsman’s specific weakness according to a specific delivery Includes all three bowling types-spin, swing and pace Vary level of deliveries according to the batsman’s skill level Includes a ball feeder system Works for hours whereas bowlers may get fatigued

Consistent deliveries vs. random deliveries

Product Design Specification

Strength/stress

Stand must support machine sufficiently Withstand shock of deliveries Withstand impact of cricket ball being hit back at machine Structure must withstand vibrations from compressor and wheels Withstand stress of unforeseen loading during transport Connections and joints must withstand forces they are subjected to

Distortion/Deflection/Stiffness

Deflection of stand and housing must be very small in order to maintain accuracy of deliveries

Must be relatively stiff in order to maintain consistency of deliveries

Wear

All moving parts must have high resistance to wear Wheels must be high wear resistant so that they maintain grip Housing to protect parts from accumulating impurities forming a third body abrasives Sleeve to prevent to wear of moving metal part

Corrosion

Anti-corrosive coating because it must endure a variety of harsh climatic conditions No stagnant areas where accumulation can occur No metal to metal contact to prevent galvanic corrosion UV protection on housing

Safety

Housing must protect user from the fast moving parts Emergency stop button on remote Compressor casing must have heat ventilation to prevent overheating

Housing must allow sufficient air circulation to prevent overheating of motors and softening of wheels

Key lock on remote Limit speed to 160km/h Unit has warning stickers

Friction

High coefficient of friction on wheels to grip balls Sufficient grease on rotating feeder

Usability

Remote must be user friendly and simple to use Easily replaceable spare parts Machine must be easy to service Easy to move Easy to assemble/disassemble Machine must be easily moved without dismantling to maximise time in use Deliver variety of balls similar size to cricket balls Machine can be repaired with standard tools

Cost

Affordable for coaching academies Affordable for clubs Afford for high performance centres

Weight

Weight must allow for easy transportation Must be heavy enough to reduce shock caused when ball is launched Weight of housing and launching mechanism must be light enough to be controlled by

DSMI

Life

Key life on motors and DSMI must be smaller than connecting parts to prevent serious damage

Competitive life span of 10 years for major parts

Services recommended every 18 months

Styling

Aesthetic appeal increase competitiveness and marketability

Shape

Housing is elliptical Broad base to prevent tipping

Size

Launch height of 1.8m Overall width of 1m Stand height of 1m

Control

Powered by 220V mains power supply Wireless remote

Thermal Properties

Working temperatures of 0 to 60

Surface

Chute must be smooth for ball to slide Feeder must have smooth finish UV protection Organic coating-vinyl laminates Offer different colours

Lubrication

Metal to metal contact area must be well lubricated with oil or grease

Marketability

Promote in Sport illustrated Advertise at Schools Advertise Academies Advertise High Performance Centre

Maintenance

Every 18 months a service and inspection Parts are easily accessed for removal and replacement Warranty 3 year warranty Instruction manual offers maintenance instructions and how to clean and with what to

clean the machine

Volume

Made on order Can take 20 orders at a time

Liability

Instruction manual as well as safety manual will be provided illustrating exactly how to operate the device

Safety stickers are visible on the device We cannot be held liable for any deviation or alternate uses of device

Recycling

Parts that aren’t standard are recyclable

Alternatives

Four concepts designs, or alternatives, were generated according to the Product Design Specification that was setup. Each alternative had advantages and disadvantages that needed to be analysed so that the best alternative could be chosen. Furthermore each concept design was pairwise compared according to the most important criteria that were set forth for the design and the highest scoring alternative was chosen.

Advantages and Disadvantages

Concept Design 1:

Advantages:

Fully automated Easily movable Durable Uses both Festo and SEW products High reliability Camera feedback High stability User friendly Able to achieve very high speeds Able to spin and swing the ball

Disadvantages:

Cost Complex programming Not all parts are easily recycled

Concept Design 2:

Advantages: Highly accurate in direction Simple concept Easily recyclable Can be used for a variety of applications Relatively cheap

Disadvantages: Limited to straight pace balls only

Large intervals required between balls while air is being compressed Invariable speed Involves high pressures Lack of consistency

Concept Design 3:

Advantages: Allows for automated lateral movement High speed deliveries Camera feedback Very stable Accurate Swing and spin

Disadvantages: Fixed onto wall Doesn’t allow for moving around Very expensive Complex programming

Concept Design 4:

Advantages: Camera feedback Fully automated User friendly Allows for high speed deliveries Accurate Variable speed

Disadvantages: Cannot spin the ball Only two pitch positions Complex design Expensive to produce

Selection Criteria and Concept Selection

1. Safety (C1)

2. Manufacturability (C2)3. Ergonomics (C3)4. Functionality (C4)5. Cost (C5)

Criteria Comparison

C1 C2 C3 C4 C5 TOTAL WEIGHTC1 0.5 1 0 1 2.5 0.25C2 0.5 1 0 1 2.5 0.25C3 0 0 0 1 1 0.1C4 1 1 1 0.5 3.5 0.35C5 0 0 0 0.5 0.5 0.05

Criteria 1:

A1 A2 A3 A4 A5 TOTAL WEIGHT (C1)

WC1.Aj=P1,j

A1 1 0.5 1 1 3.5 0.25 0.25*3.5=0.875A2 0 1 0 0.5 1.5 0.25 0.25*1.5=0.375A3 0.5 0 1 0 1.5 0.25 0.25*1.5=0.375A4 0 1 0 1 2 0.25 0.25*2=0.5A5 0 0.5 1 0 1.5 0.25 0.25*1.5=0.375

Criteria 2:

A1 A2 A3 A4 A5 TOTAL WEIGHT (C2)

WC2.Aj=P2,j

A1 0.5 1 1 1 3.5 0.25 0.25*3.5=0.875A2 0.5 1 0 0.5 2 0.25 0.25*2=0.5A3 0 0 1 0 1 0.25 0.25*1=0.25A4 0 1 0 1 2 0.25 0.25*2=0.5A5 0 0.5 1 0 1.5 0.25 0.25*1.5=0.375

Criteria 3:

Criteria 4:

Criteria 5:

A1 A2 A3 A4 A5 TOTAL WEIGHT (C3)

WC3.Aj=P3,j

A1 1 1 1 0.5 3.5 0.1 0.1*3.5=0.35A2 0 1 0 0.5 1.5 0.1 0.1*1.5=0.15A3 0 0 1 0 1 0.1 0.1*1=0.1A4 0 1 0 1 2 0.1 0.1*2=0.2A5 0.5 0.5 1 0 2 0.1 0.1*2=0.2

A1 A2 A3 A4 A5 TOTAL WEIGHT (C4)

WC4.Aj=P4,j

A1 1 1 1 1 4 0.35 0.35*4=1.4A2 0 1 0 0.5 1.5 0.35 0.35*1.5=0.525A3 0 0 1 0 1 0.35 0.35*1=0.35A4 0 1 0 1 2 0.35 0.35*2=0.7A5 0 0.5 1 0 1.5 0.35 0.35*1.5=0.525

A1 A2 A3 A4 A5 TOTAL WEIGHT (C5)

WC5.Aj=P5,j

A1 1 1 0.5 1 3.5 0.05 0.05*3.5=0.175A2 0 1 0 0.5 1.5 0.05 0.05*1.5=0.075A3 0 0 1 0 1 0.05 0.05*1=0.05A4 0.5 1 0 1 2.5 0.05 0.05*2.5=0.125A5 0 0.5 1 0 1.5 0.05 0.05*1.5=0.075

Final Score:

Alternative 1:0.875+0.875+0.35+1.4+0.175=3.675

Alternative 2:0.375+.0.5+0.15+0.525+0.075=1.625

Alternative 3:0.375+0.25+0.1+0.35+0.05=1.125

Alternative 4:0.5+0.5+0.2+0.7+0.125=2.025

Alternative 5:0.375+0.375+0.2+0.525+0.075=1.55

From the above it is evident that Alternative 1 has the highest ranking score when each alternative was evaluated according to the five most important criteria. This decision was then justified when the advantages and disadvantages of each alternative were analysed which also gave an indication that alternative 1 was the best choice for the final design.

Performance Simulation

The unit will consist of two rubber bonded aluminium wheels which will be powered by two Eorodrive electronic motors controlled by a frequency invertor (MOVITRAC), a precise and positive tilting mechanism which will be achieved by a Festo pneumatic cylinder, a shoot, fully automated feeding system, and a Festo DSMI rotary positioning unit with a CMPX controller in order to control the rotary motion. The rotary output shaft of the electrical motors mounts directly onto the wheels through an axial thrust bearing where rotations will be in opposite directions and the wheels will be positioned in a common plane. Thus the ball is gripped between the rotating wheels and projected in a forward direction.

An electrical control panel will control all the above electronic and pneumatic components. The electrical power will be provided by a 220V source and the pneumatic power will be provided by an ABAC 1.5kW motor compressor. Different ball speeds will be obtained by adjustments of the rotating speeds of the wheels and this will be achieved by the MOVITRAC. Adjustment of the trajectory of the ball arriving at the batsman’s position at various elevations relative to the batting level will be achieved by the precise and positive tilting mechanism i.e. the Festo pneumatic cylinder.

Figure 1 and Figure 2 below illustrate a control scheme in the form of a flow chart. For instance swing can be imparted on the ball being fired by controlling the relative speeds of

the two rotating wheels, and the manner in which the speeds of the rotating wheels are controlled is shown in figure 2. This shows the input switches connect to a microcontroller that controls the motors. The Microcontroller then puts a signal through to each motor individually and the speeds are then set.

Figure 1: Control Scheme Flow Chart

Figure 2: Motor Control Flow Chart

Quantities

Known Quantities:

Safety factor: C=4

Maximum rotating speed of wheels: n=1455rpm

Radius of wheels: r=0.3m

Torque of wheel driving motors: T=19.8Nm

Power of wheel driving motors: P=3kW

Yield strength of SAE-: σ=200MPa

Launch height: H=2m

Pitch length: l=20.12m

Outer diameter of shaft: douter=100 mm

Gravitational acceleration: g=9.81m /s2

Maximum moment on shaft: M bs=1.7kN.m

Maximum moment on floor casing: M f =¿500N.m

Thickness of casing floor: h=10mm

Width of casing floor: b=0.5m

Quantities to be determined:Stresses on supporting shaft

σ bs-Bending stress

σ ns-Normal stress

The shear stress is negligible due to orientation of loads

Properties of supporting shaft (See DWG. CBM-##)

A s

ls

d inner

Bending stress for casing floor:

σ f

I f

Velocity of ball

vb

Angular velocity of wheels

n

Calculations:

Stresses on supporting shaft:

For bending stress:

σ bs=C M bs ybs

I bs

σ bs=CM douter

2 I bs

With the known quantities the moment of inertia can be calculated to be:

I bs=1.688 ×10−6m4

The inner diameter of the supporting shaft can then be calculated to be 90mm from the moment of inertia equation for a circular shaft

I bs=π (douter

4−d inner4)

64

Normal Stress for the Shaft:

A s=π ( 0.52−0.452)

A s=0.15 m2

σ ns=FA s

¿ 10000.15

¿6.67 kPa

¿negligible

Bending stress for casing floor:

I f =b h3

12

I f =0.5 × 0.013

12

I f =4.1667 ×10−8 m4

σ f=M f y f

I f

σ f=M f t

2 I f

σ f=500× 0.01

2 × 4.1667 ×10−8

σ f=50 MPa

Delivery characteristics

The bowling machine will be able to be set in 5km/h interval speeds ranging from 60km/h all the way up to 160km/h. A sample calculation is shown below to demonstrate how the angular velocity of the wheels to provide the desired speed is determined and the results are displayed in Table 1.

For a 60km/h delivery the angular velocity is determined as shown below:

n=60vb

2 πr (3.6)

n= 60 × 602 π (0.3) (3.6 )

n=530 rpm

Table 1: Required RPM of Motors for Specified Delivery Speed

Delivery Speed

RPM of left motor

RPM of right motor

Nature of Swing

60 531 531 Straight65 575 575 Straight70 619 619 Straight75 663 663 Straight80 707 707 Straight85 752 752 Straight90 796 796 Straight95 840 840 Straight100 884 884 Straight105 928 928 Straight110 973 973 Straight115 1017 1017 Straight120 1061 1061 Straight125 1105 1105 Straight130 1149 1149 Straight135 1194 1194 Straight140 1238 1238 Straight145 1282 1282 Straight150 1326 1326 Straight155 1371 1371 Straight160 1415 1415 Straight

Feeding System

For the feeding system the balls will be placed into a hopper and the lowest ball in the hopper will roll into a rotating door that carries two balls at a time. The level that the rotating door is situated on is at a slight forward angle so that once the section of the rotating door that is carrying a ball is at a position where the ball is to be fed into the rotating wheels to launch the ball, the ball will simply roll out and as the empty section rotates back passed the hopper, another ball is picked up.

The rotating door is moved by a PM45 Fractional DC Motor that will be powered off a small, lightweight 12 V battery pack that is easily attached to the stand.

Safety

Seeing as though the proposed bowling machine is operated on a human interaction basis, the potential for injury or destruction to a person or to property it very evident. Thus safety is a very important aspect and was worked into the design of the bowling machine. Thus the areas where safety was included and how it was done so were:

Safety stickersIt was proposed and accepted that safety and warning stickers be put onto areas of the bowling machine where there was potential for danger. Thus to avoid human injury a sticker will be placed in the specific area to warn people of the potential danger. An example of this is shown in the figure below.

The areas that were identified as potentially dangerous areas where:

The spinning wheels The feeding chute Area in front of the bowling machine All electrical components

In addition to the safety stickers, presented with the bowling machine will be a full set of instructions and safety instructions. This will inform the buyer of all present dangers in the machine. It will also have a suggested set of rules in order for the person operating the machine to have the least possible chance of getting injured.

Design of MachineThe proposed bowling machine is going to operate in a fully automated state. This meaning that the batsmen in the nets will have a remote as to operate the bowling machine as he desires. It was then discussed what will happen if the batsmen had to become injured during one of the balls that has been bowled. Without the addition of an emergency stop the bowling machine will continue to deliver ball after ball thus putting the batsmen in greater danger. Therefore and emergency stop button will be present on the remote. This will help the stop the batsmen from getting any further injuries if something had to go wrong.

With the presence of all the moving parts i.e. the wheels and motor there is a potential for a safety hazard. Thus in our design there will be guards in place to prevent someone getting injured when they are using the machine.

In addition to this having electric motors and electrical machinery present on the proposed bowling machine, poses the danger of getting electrocuted thus correct insulation of electrical parts will be present in the design of the machine.

Ventilation is a very important aspect in this particular design as there is a compressor present in the design and the compressor needs to be properly ventilated as if it over heats it might become a very high fire hazard. Thus the ‘compartment’ where the compressor is being kept has been properly ventilated in its design.

Environment

All components on the proposed bowling machine are recyclable, except the standard components. This will ensure that after the devices lifespan has been spent, the device can be recycled into other components so that there is less waste that could have a negative effect on the environment. The proposed bowling machine will not have an adverse effect on the environment as it will not destroy any plant life or will not release harmful toxins into the air during its use.

Ergonomics

Seeing as though the proposed bowling machine is to be completely controlled by the batsman, ergonomics is a very important aspect. The bowling must be very easy to use and must have a variety of different settings in order to set it apart from the other bowling machines out there. It already does this by being completely automated but there a few aspects of this bowling machine that also set it apart.

Remote control Programming of different deliveries from ball to ball Automated feeding system Video Camera

Firstly the remote control has to be very user friendly this means as little buttons as possible, as small as possible and easy to handle. All of these factors were taken into account in the design of the remote control. They are all important due to the fact that the batsmen controlling the bowling machine will be wearing gloves, thus making it difficult for him to push buttons etc. This also includes the buttons, if there are too many complicated buttons to push the batsmen will find it difficult to use the remote.

Secondly the variety of different uses of the machine is also important when it comes to human interface. In the design it was taken into account the proposed bowling machine should be able to deliver a variety of different deliveries. This must all be controlled by the remote and thus the batsmen will be able to programme a specific number of deliveries in a variety of ways. With this the timing of each ball can also be varied within three different settings, this explains the automated feeding machine. All of the considerations that took place above all contribute to the human interface and help the batsmen enjoy a very good batting practice were he can focus on whatever area of his game by simply changing the type of delivery he receives.

Thirdly a video camera will be attached to the proposed bowling machine, with this recording during the batting session and being stored onto a hard drive. The batsmen can then afterward go and watch how he batted and then pick up on any mistakes. This also helps as he can get expert advice without the coach physically having to be there. The coach can just re-view the recordings after and offer his advice.

With the entire above human interface considerations the design was based around the simplicity of use of the machine and how to make the bowling machine most efficient.