Team 2 Final Report

IntroductionA power hacksaw is a machine used to cut across materials like metal and bone. Aluminum, brass, and mild steels are other materials the power hacksaw is capable of slicing through. It comes in various types, such as utility, heavy duty, and high-production styles. In most machine shops, these tools are used due to the reciprocating motions that are able to cut through diameters of more than ten inches (25.4 cm) in size.

Power hacksaws have an arm section, which is the rotating portion of the machine that cuts the material on a backward stroke. This is the part of the tool where the blade is located. To hold the object to be cut together, the tool is equipped with a vice that has handles one can turn to tighten or loosen the hold on the material. It is a powerful part of the hacksaw that locks the object in position for cutting. An emergency foot switch and coolant are also part of the tool as safety precautions.

The power hacksaw blades are used to cut through the material or object and are usually graded according to the steel it is made of and the number of teeth that it has. As a cheaper alternative for the metal blades, some manufacturers use carbon steel materials. Each blade of the power hacksaw is composed of 14 to 24 teeth per inch of the blade. More teeth present in the hack blade produce a smoother output. Blades of hacksaw devices can become brittle; proper care should be taken to prevent this.There are several variants of the power hacksaw on the market. One type of the power hacksaw is the panel style. This design allows sheets of metal to be cut without the hindrance of the frame. Another type is the electric hacksaw, which is charged with a motor or stationary engine. The latter type is still produced but is somewhat limited in use.The history of the power hacksaw machine is associated with regular hand saws. Handsaws per se have been present since the time of the ancient Egyptians. Hieroglyphics in that era showcased the importance of wood in the community and how the Egyptians dealt in cutting it. Modern versions of the hand saw are based on the first one developed by the Kulibert Saw Company. As the demand to cut and saw harder types of materials grew, the power hacksaw was developed and created to alleviate the effort in doing the procedure.Project EthicWe made power hacksaw but its operation method is different from conventional that runs with solar energy. We made an alteration so that can run on solar energy power through solar cell.Solar EnergyThe surface of the earth receives about 1014 kW from sun in the form of solar energy which is approximately five orders of magnitude greater than that currently being consumed from all resources. It is evident that sun will last for 1011 years.There are two obvious obstacles to harnessing solar energy. Firstly it is not constantly available on earth. Thus some form of storage is needed to sustain solar energy through the night and during rainy season. Secondly the solar energy is diffused. Although the total amount of energy is enormous, the collection and conservation of solar energy into useful forms must be carried out over a large area which entails large capital investments.Photovoltaic Cells (Solar Cells)Photovoltaic (PV) cells are structures designed to allow light to be directly converted into electricity at the atomic level.

Components to Photovoltaic Cells:1) Photovoltaic Effect: PV cells are able to create electricity at the atomic level using the photovoltaic effect. Often the photovoltaic effect is confused with the photoelectric effect. One is related to the other as both begin with the basic understanding that the universe is created of two core entities: matter and energy. Matter is anything that has mass and takes up space. In physics energy is defined as a source providing the ability to do work (e.g. light, heat, sound, electricity). In the photoelectric effect, there are two components: photons (energy) and electrons (matter). Photons are light packets. Each one carries a specific quantity (quanta) of energy revealed in different frequencies of light (higher energy photons are found in higher frequencies of light waves). Using the correct light frequency (photons) focused on a material (usually metal), it is possible to knock off or release electrons. So, the photoelectric effect uses light to eject electrons. Similarly, in the photovoltaic effect photons are used to eject the electrons, but these electrons are harnessed to produce an electric current or electricity. 2) Semi-Conductor: The flow of electrons or an electric current is possible within the photovoltaic effect if a conductor is present. Electricity is conducted through a material by moving electrons through orbitals at varying energy levels in atoms. Electrons move from lower energy levels (valance band) to higher energy levels (conduction band). The energy difference between these levels is known as the band gap. Semi-conductors have an intermediate band gap. Meaning they require more energy to move electrons than a conductor, but less than an insulator. Once electrons are moved they create electron holes or unoccupied orbitals in the valance band and easily released electrons in the conduction band. In PV cells, semi-conductors are often used because they can regulate conduction band electrons and electron holes more readily, especially if the semi-conductor is doped or impurities are added.3) P-N Junction (Photodiode): The photovoltaic effect within a PV cell is able to produce an electric current by using a P-N junction. The P-N Junction is made of two kinds of semi-conductors. The N-type (N for Negative or electron-rich) is doped to have a high density of electrons and few holes, while the P-type (P for Positive or electron-poor) is doped to be the opposite. Electrons flow from areas of high to low concentration. The difference between these concentrated areas is known as voltage. A P-N junction regulates the voltage, so current only flows in one direction resulting in an electric current.

Operation of Photovoltaic Cells (Solar Cells): PV Cells are able to convert light into electricity by first allowing radiant energy from the sun to pass through a transparent layer (glass). A small portion of the light frequencies (10 17% with technology commercially available in 2011) (photons) are absorbed ejecting electrons from the doped N-type semiconductor layer. The amount depends on intensity and angle of light sent and the continuing development of the manufacturing technology. These electrons are passed to a conductor, which completes a circuit back to the P-type semiconducting layer. After transporting electrical energy utilized by electrical devices or stored in batteries, the electrons will fill holes in the P-type semiconducting layer. Due to electrons being deposited in P-type semiconductor layer the voltage increases forcing the electrons to move across the junction into the N-type semiconductor allowing the process to repeat itself. As technology advances, improvements in conversion efficiencies demonstrated in the laboratory (some approaching 40%) ma become commercially available, subsequently lowering costs.

Literature Review

Photovoltaic System Design

There are many types of solar systems but most can be categorized into a variation of the following: A grid-tie system where there are no batteries and the power grid provides back-up power. A hybrid grid-tie system where the power grid provides back-up for the solar panels and batteries act as a backup for the grid. In cases where there is no access to grid power an off-grid system is used, in which the battery bank stores and provides all the energy for the system without a backup. Since this is generally the case in under-developed areas this will be the system discussed here. There are also systems with generators as backups, they are comparable to grid-tie systems and will also be omitted from discussion here.Determining Size of Photovoltaic Panel Array:There are several steps involved in sizing the PV array, determining load power consumption, accounting for losses and dividing by solar insolation levels for deployment region.Determining Load Power Consumption:The first step is to determine how much power the total system load will draw. Power is measured in Watts:P = V I (Joules Law)

However, the power rating is more useful when looked at in terms of time, this is indeed how electric companies charge consumers. For example a 200Watt light bulb running for 24 hours uses 4.8 KWh.200Watts 24hrs = 4800 Watt-Hours or 4.8 KWh

A list of all devices connected to the system should be made with their appropriate power draw available from specifications sheets or better yet, actual measurements.Since these devices are designed to plug into AC power, a DC-AC power inverter is needed. The power inverter ideally operates at 90% efficiency. Therefore the maximum inverter draw from batteries is:238 Watts / 0.90 = 264.60 Watts

This system power draw is then multiplied by the amount of hours per day that it will operate.264.60 Watts 8hrs/day = 2116.80 Watt Hrs/day

To compensate for system losses during battery charge/discharge cycles the total system power consumption is multiplied by a 20% compensation factor (Sunwize).2115.52 Watt Hrs/day 1.2 = 2540.16 Watt Hrs/dayDetermining Solar Insolation Levels:In order to determine a good approximation of how much power the PV panels will output, solar insolation levels need to be considered. Solar insolation is the amount of incoming solar radiation incident on a surface, for PV applications the surface of interest is the earths surface. The values of solar insolation are commonly expressed in kWh/m2/day, which is the amount of solar energy that strikes a square meter of the earth's surface in a single day. This is commonly referred to as a Sun-Hour-Day. The amount of insolation received at the surface of the Earth is controlled by the angle of the sun, the state of the atmosphere, altitude, and geographic location.

Figure 3 - World insulation levels.This map divides the world into six solar performance regions based on winter peak sun hours.It is important to keep this in mind when designing the system because as seen below in Figure 4, during the winter you have a much smaller Solar Window. Worst case scenarios should be calculated as it is better to have extra energy in the summer than not enough in the winter. Therefore the Sun-Hour-Day values for December (since December days are shortest) are generally used.

Figure 4 - Sun path chart.

Figure 5 - Hankins.Solar Insolation Levels for Arusha, the prototype deployment area, are seen below in Figure 5.The compensated total power consumption per day value calculated above is then divided by the solar insolation values for given deployment region to determine minimum PV panel array power output requirement:2540.16 Watt Hrs/day / 5.5 = 461.84 WattsSizing Battery ArrayNearly all large rechargeable batteries in common use are Lead-Acid type, although there are three variations, flooded, gelled electrolyte (Gell Cells) and absorbed glass matt (AGM). Flooded is the oldest and cheapest technology used but can be dangerous, in case of a malfunction acid can spill. Gell Cells contain acid that has been "gelled" by the addition of Silica Gel, turning the acid into a solid mass, therefore even if the battery where cracked open, no acid would spill. Gell batteries need to be charged at a slower rate (capacity / 20) but this is not a concern in the PV setup as the panels will not be outputting nearly this much current. AGM batteries are the newest technology and have all the advantages of Gell Cells without the charging limitations.All deep cycle batteries are rated in amp-hours. An amp-hour (Amps x Hours) is one amp for one hour, or 10 amps for 1/10 of an hour and so forth. The accepted AH rating time period for batteries used in solar electric and backup power systems is the "20 hour rate". This means that it is discharged down to 10.5 volts over a 20 hour period while the total amp-hours it supplies is measured (Windsun).

The compensated total power consumption per day value is used again to calculate minimum battery array size. 2540.16 Watt Hrs/12 Volts = 211.68 AmpHrs/day

Number of days of autonomy to support: 1 (8hrs)211.68 1 = 211.68 AmpHrs

Battery life [deep cycle] is directly related to how deep the battery is cycled each time. If a battery is discharged to 50% every day, it will last about twice as long as if it is cycled to 80% DOD [depth of discharge]. If cycled only 10% DOD, it will last about 5 times as long as one cycled to 50%. Obviously, there are some practical limitations on this - you don't usually want to have a 5 ton pile of batteries sitting there just to reduce the DOD. The most practical number to use is 50% DOD on a regular basis (Windsun).Depth of discharge for battery: 0.5211.68 / 0.5 = 423.6 AmpHrs

This means that after 8 hrs of use without sun the battery will be discharged to 50%

8 Hrs of autonomy and battery depth of discharge at 0.80 (Half the life-span of 0.50):264.60 Amp Hrs

6 Hrs of autonomy and battery depth of discharge at 0.50: 264.6 Watts 6 Hrs = 1587.6 Watt Hrs / day 1.2 = 1905.12 Watt Hrs / day1905.12 Watt Hrs/12 Volts = 158.76 AmpHrs142.8 AmpHrs / 0.5 = 317.52 Amp Hrs

4 Hrs of autonomy and depth of discharge at 0.50:238 Watts 4 Hrs = 1058.4 Watt Hrs / day 1.2 = 1270.08 Watt Hrs / day1270.08 Watt Hrs / 12 Volts = 105.84 Amp Hrs105.84 Amp Hrs / 0.5 = 211.68 Amp HrsWire Sizing and Connections:Another important consideration for the system is the electrical wiring. All wiring needs to safely accommodate the amount of current draw of the system with an acceptable amount of losses. In a DC system losses quickly become an issue. This is especially a concern PV systems as they can only handle a small voltage drop as there must be enough potential to charge the battery array, and of course it is good practice to keep energy loss sourced from the sun to a minimum. Generally a 3% drop between PV array and batteries is acceptable. Also, any type of connection bigger than AWG 10 should have a proper compression connector, with appropriate joint compound and preparation. This does require special tools and dies. Otherwise you are running the risk of burning up your connections if you get any kind of heavy current flowing. (SolarForum)

Losses associated with transmission of DC power:CM = (22.2 A D)/VD

CM = Circular Mills In Copper A = current in ampsD = one-way cable distance in feetVD = Voltage Drop22.2 = Constant for Copper

For wiring from the PV panels to charge controller the maximum PV short circuit current specification (from PV data sheet) is used.

Maximum Solar Power Output:24 Volt Systems:ConfigurationMax Current Out (Amps)

6 x PW0803 x (5.14A-ISC) = 15.42

3 x ST-16520.63

4 x KY12520.83

Figure 612 Volt Systems:ConfigurationMax Current Out (Amps)

6 x 80 Watt6*(5.14A-ISC) = 30.84

3 x PW16541.25

Figure 7Using the loss equation above the following result was obtained for the selected system:Distance: 50ftVoltage Drop: 0.72Current: 15.42 AmpsCircular Mills: 23772.5AWG: 6Inverter to Battery WiringFor current level estimates from the battery to inverter maximum power draw levels are used although this distance is generally short and maximum available wire gauge is recommended. This is also due to the fact that the system will encounter surge currents as various components are turned on. Since the system used as an example here is not continuously running and is to be turned off every night and back on in the morning this was a serious issue that needed to be tested. (Refer to Figure 9).

Maximum Power Draw:ComponentPower (Watts)

DC Motor19 volt

Solar Panel5W

Battery12 Volt

Figure 8Assuming the inverter that will be sourced in deployment area is operating at 90% efficiency:270 Watts = 300 Watts x 90%

Maximum current draw in 12 Volt system = 300 Watts / 12 Volts = 25 AmpsMaximum current draw in 24 Volt system = 300 Watts / 24 Volts = 12.5 Amps

Figure 9Figure 9 shows DC current draw as measured during power-up of Lenovo S10 Workstation (custom configuration) and L193p Monitor. Although the system is only drawing 5 amps while running the surge current spikes are clearly visible. This is indeed one of the reasons why proper electrical connections are crucial.Charge ControllerThe charge controller chosen for this system is the Outback Power FlexMax 60. This decision was based on versatility, efficiency, robustness, and availability in deployment area. The Outback can accept a wide range of voltage inputs as well as various battery arrays, this was important for this specific system as ultimately whatever solar panels are in stock at the time of deployment in the region will be used.

Figure 10 - Outback charge controller.Note, the efficiency curves (Figure 10 and Figure 11) are for the Flexmax80, they are identical to the Flexmax60 other than the fact that the FX60 does not accept 85 and 100V.The highlighted area on the graph represents the highest efficiency while charging a 12V battery array. The charge controller is operating at about 95.5% efficiency with an input Voltage between 17-34V. Typically a 12V PV panel's Voltage at Peak Power is around 17 Volts.

Figure 11 - Outback charge controller.The highlighted area in this graph represents the optimum efficiency if the system where charging a 24V battery array. The charge controller is operating at about 98% efficiency with an input Voltage around 34V. Two 12V panels in series will typically have 34 Volt equivalent Voltage at peak power.In an ideal setup the FlexMax 60 would operate at 98.1% efficiency with an input of 68V while charging a battery array at 48V. This would be the case with the optimum PV panel chosen in section 1, the Kaneka G-EA060 as the VPM is 67Volts. ConclusionDesigning an off grid photovoltaic system involves many steps and although the math is simple all calculations should be double checked. If the calculations for one component are off chances are the whole system will not work, every stage relies on the previous one. Designing the system for worst case scenarios is good practice, it is better to have extra energy than not enough. All safety precautions should be followed especially on electrical connections that have a possibility of carrying a lot of current. Breaker boxes before and after battery connections for easy power disconnect should be implemented. These breakers should be rated for DC voltages.

A hacksaw is a fine-toothed saw, originally and principally for cutting metal. They can also cut various other materials, such as plastic and wood; for example, plumbers and electricians often cut plastic pipe and plastic conduit with them. There are hand saw versions and powered versions (power hacksaws). Most hacksaws are hand saws with a C-shaped frame that holds a blade under tension. Such hacksaws have a handle, usually a pistol grip, with pins for attaching a narrow disposable blade. The frames may also be adjustable to accommodate blades of different sizes. A screw or other mechanism is used to put the thin blade under tension. Panel hacksaws, forgo the frame and instead have a sheet metal body; they can cut into a sheet metal panel further than a frame would allow. These saws are no longer commonly available but hacksaw blade holders enable standard hacksaw blades to be used similarly to a Keyhole saw or Pad saw. Power tools including Nibblers, Jigsaws and Angle Grinders fitted with metal cutting blades and discs are now used for longer cuts in sheet metals.

On hacksaws, as with most frame saws, the blade can be mounted with the teeth facing toward or away from the handle, resulting in cutting action on either the push or pull stroke. In normal use, cutting vertically downwards with work held in a bench vice, hacksaw blades should be set to be facing forwards. Some frame saws, including Fret Saws and Piercing Saws, have their blades set to be facing the handle because they are used to cut by being pulled down against a horizontal surface.

While saws for cutting metal had been in used for many years, significant improvements in longevity and efficiency were made in the 1880s by George N. Clemson, a founder of Clemson Bros., Inc of Middletown, New York, USA,. Clemson conducted tests which involved changing the dimensions, shapes of teeth, styles of set, and variable heat treatments of blades. Clemson claimed enormous improvements to the cutting ability of blades and built a major industrial operation manufacturing hacksaw blades sold under the trade name Star Hack Saw. In 1898, Clemson was granted US Patent 601947, which details various improvements in the hacksaw BladesBlades are available in standardized lengths, usually 10 or 12inches for a standard hand hacksaw. "Junior" hacksaws are typically 150mm long. Powered hacksaws may use large blades in a range of sizes, or small machines may use the same hand blades.The pitch of the teeth can be anywhere from fourteen to thirty-two teeth per inch (tpi) for a hand blade, with as few as three tpi for a large power hacksaw blade. The blade chosen is based on the thickness of the material being cut, with a minimum of three teeth in the material. As hacksaw teeth are so small, they are set in a "wave" set. As for other saws they are set from side to side to provide a kerf or clearance when sawing, but the set of a hacksaw changes gradually from tooth to tooth in a smooth curve, rather than alternate teeth set left and right.Hacksaw blades are normally quite brittle, so care needs to be taken to prevent brittle fracture of the blade. Early blades were of carbon steel, now termed 'low alloy' blades, and were relatively soft and flexible. They avoided breakage, but also wore out rapidly. Except where cost is a particular concern, this type is now obsolete. 'Low alloy' blades are still the only type available for the Junior hacksaw, which limits the usefulness of this otherwise popular saw.For several decades now, hacksaw blades have used high speed steel for their teeth, giving greatly improved cutting and tooth life. These blades were first available in the 'All-hard' form which cut accurately but were extremely brittle. This limited their practical use to benchwork on a workpiece that was firmly clamped in a vice. A softer form of high speed steel blade was also available, which wore well and resisted breakage, but was less stiff and so less accurate for precise sawing. Since the 1980s, bi-metal blades have been used to give the advantages of both forms, without risk of breakage. A strip of high speed steel along the tooth edge is electron beam welded to a softer spine. As the price of these has dropped to be comparable with the older blades, their use is now almost universal.Hacksaw blade specifications: The most common blade is the 12 inch or 300mm length. Hacksaw blades have two holes near the ends for mounting them in the saw frame and the 12 inch / 300mm dimension refers to the center to center distance between these mounting holes. 12 Inch Blade:Hole to Hole: 11 7/8 inches / 300mmOverall blade length: 12 3/8 inches / 315mm (not tightly controlled)Mounting Hole diameter: 9/64 to 5/32 inch / 3.5 to 4mm (not tightly controlled)Blade Width: 7/16 to 33/64 inch / 11 to 13mm (not tightly controlled)Blade Thickness: 0.020 to 0.027 inches / 0.5 to 0.70mm (varies with tooth pitch and other factors)The kerf produced by the blades is somewhat wider than the blade thickness due to the set of the teeth. It commonly varies between 0.030 and 0.063 inches / 0.75 and 1.6mm depending on the pitch and set of the teeth.The 10 inch blade is also fairly common and all the above dimensions apply except for the following:Hole to Hole: 9 7/8 inches / 250mmOverall blade length: 10 3/8 inches / 265mm (not tightly controlled)

Types

An electric hacksawA panel hacksaw (no longer commonly available) eliminated the frame, so that the saw could cut into panels of sheet metal without the length of cut being restricted by the frame.Junior hacksaws are the small variant, while larger mechanical hacksaws are used to cut working pieces from bulk metal.A power hacksaw (or electric hacksaw) is a type of hacksaw that is powered either by its own electric motor or connected to a stationary engine. Most power hacksaws are stationary machines but some portable models do exist; the latter (with frames) have been displaced to some extent by reciprocating saws such as the Sawzall, which accept blades with hacksaw teeth. Stationary models usually have a mechanism to lift up the saw blade on the return stroke and some have a coolant pump to prevent the saw blade from overheating.[4]Power hacksaws are not as commonly used in the metalworking industries as they once were. Bandsaws and cold saws have mostly displaced them. While stationary electric hacksaws are not very common, they are still produced. Power hacksaws of the type powered by stationary engines and line shafts, like other line-shaft-powered machines, are now rare; museums and antique-tool hobbyists still preserve a few of them.

ADVANTAGES Time saving as compared to simplehacksaw Power savingas it ismanully operated Easy machinary used As it ispedal operated so good for health Comfortable then ordinaryhacksaw

DISADVANTAGESIts totallymanuallyoperated .Time consuming as compared toelectrical powerhacksawWithout human effort its not operated.Not fit for heavy production.

TYPES OF SAWCoping Saw :Coping saws are used to remove complicated shapes and cut curves in wood and plastic.

Power HacksawPower hacksaws are used to cut large sizes (sections) of metals such as steel. Cutting diameters of more than 10/15mm is very hard work with a normal hand held hacksaw. Therefore power hacksaws have been developed to carry out the difficult and time consuming work. The heavy arm moves backwards and forwards, cutting on the backwards stroke.The metal to be cut is held in a machine vice which is an integral part of the base. Turning the handle tightens or loosens the vice. The vice is very powerful and locks the metal in position.When cutting is taking place, the metal and especially the blade heats up quickly. Coolant should be fed onto the blade, cooling it down and lubricating it as it cuts through the metal.Without the use of coolant the blade will over heat and break/snap. This can be dangerous as the blade can break with powerful force, shattering. When the metal is placed and fixed in the vice, the blade is lowered onto its top surface. The diagram below shows the arm being lowered with the adjusting handle. Blades of power hacksaws are graded according to the material they are made from and the number of teeth per inch. Top quality blades are manufactured from High Speed Steel. although there are cheaper alternatives such as carbon steel blades. In general the number of teeth per inch (TPI) range from 14 to 24. The more teeth per inch - the smoother the cut.Every power hacksaw should have a foot switch / emergency switch. This allows the operator to turn the machine off quickly by using his/her foot to step on the switch. The foot switch is normally positioned at the front or side of the machine. Power hacksaws have electric motors that power the blade through a pulley system. Some have ratchet systems. The pulley system shown below shows how rotary power is transferred from the motor and changed to reciprocating motion, allow the blade to cut through the material. Most power hacksaws have two pulley wheels. If the belt is placed on the smaller pulley wheel the speed of cut will be fast. Changing the belt so that it runs round the larger pulley wheel will reduce the speed.

Methodology

Review of Design

Bill of Material

Components detailsFrameIt is made up of MS Angle Iron as its basic structure on which all components to be assembled.Dimensions & Pics below:Height :Width:Length:Angle ThicknessMaterial of frame:

Motor :It is a DC motor operated on DC supply of 19V.Specifications of Motor:Rpm of Motor:70rpmVoltage:19VPower consumption:Loading Capacity:

Solar Panel:It is Solar modules use light energy (photons) from the sun to generate electricity through the photovoltaic effect. The majority of modules use wafer-based crystalline silicon cells or thin-film cells based on cadmium telluride or silicon.Specifications:Power consumption:5watts

Battery:Wet Battery is used for power supply to run motor.Specifications of Battery:Volatge:6Amp-hrMaterial of Battery:Lead-Acid BatteryChemical Formula:H2SO4-Pb

Battery Charger:It is used to charge battery from solar energy through solar panel. Its main components from electronics so that we take help from department of electronics engineering to make circuit. We dont have knowledge of its components.

Overall Project:

Result

Experimental Work on it to check is that working or not?

We set up the overall project in sunlight to charge, than we can found that it would take 12 hours for charging the battery & when we run the power hacksaw through it, the power hacksaw would run 2 hour & cut aluminum sheet of 3mm in 15minutes.

If my department allows me to give the demo than I can show the demo but it takes minimum 3 days.

Conclusion

We concluded that if it is made on large scale than it would be more economical in running & eco-friendly for environment & an industry run through at negligible running cost. & it has bright future in future because of expensive & limited amount of coal, Diesel, & other means of energy which is require to generate electric power.

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