Chapter-2-may-1-2018.docx

CHAPTER II

THEORETICAL FRAMEWORK This chapter presents the relevant theories, related literature, studies, conceptual framework hypothesis of the study, definition of terms/variables, and notes.

Relevant Theories I.

Machine Design Machine design is the process of engineering design. A machine is made up of mechanisms that work together to satisfy the requirements of what the machine needs to accomplish. Mechanisms can still be used independently, such as an umbrella, but cannot accomplish what a machine can because a machine controls energy in addition to motion. Machine design takes into account kinetics and kinematics, which deal with motion and the forces on an object in motion. Machine design is applied through a specific process including determining what the machine needs to do, benchmarking and defining goals and requirements, brainstorming, evaluating and selecting from the different options, creating an in-depth design, creating and testing a prototype, and finally manufacturing the machine.

A. Power Screw A power screw is a drive used in machinery to convert a rotary motion into a linear motion for power transmission. It produces uniform motion and the design of the power screw may be such that either the screw or the nut is held at rest and

the other member rotates as it moves axially. A typical example of this is a screw clamp either the screw or the nut rotates but does not move axially. A typical example for this is a press. Other applications of power screws are jack screws, lead screws of a lathe, screws for vices, presses etc. Through the help of the worm gears, the power screw then served as one of medium of movement for the lifting mechanism of the machine. The threading of the power screw served as the main distance to be travelled by the nut in order to lift the crane.

II.

Bending stress Bending stress is the normal stress that is induced at a point in a body subjected to loads that cause it to bend. When a load is applied perpendicular to the length of a beam (with two supports on each end), bending moments are induced in the beam. The project is prone to bending stress due to lifting heavy loads. Due to limited resources, the machine have not gone through actual bending tests. However, it is highly recommended to subject the machine to an actual bending stress test.

III.

Mechanical Process A. Cutting Process Cutting is a collection of processes wherein material is brought to a specified geometry by removing excess material using various kinds of tooling to

leave a finished part that meets specifications. The net result of cutting is two products, the waste or excess material, and the finished part. In cutting metals the waste is chips or swarf and excess metal. (Metalworking, n.d.)

B. Grinding Process Grinding is a material removal and surface generation process used to shape and finish components made of metals and other materials. The precision and surface finish obtained through grinding can be up to ten times better than with either turning or milling. Grinding employs an abrasive product, usually a rotating wheel brought into controlled contact with a work surface. The grinding wheel is composed of abrasive grains held together in a binder. These abrasive grains act as cutting tools, removing tiny chips of material from the work. (Basics of Grinding, n.d.)

C. Welding Process In arc welding, the intense heat needed to melt metal is produced by an electric arc. The arc is formed between the actual work and an electrode stick that is manually or mechanically guided along the joint. The electrode can either be a rod with the purpose of simply carrying the current between the tip and the work. Or, it may be a specially prepared rod or wire that not only conducts the current but also melts and supplies filler metal to the joint. In welding, the arc not only provides the heat needed to melt the electrode and the base metal, but under certain conditions must also supply the means to

transport the molten metal from the tip of the electrode to the work. (Arc Welding Fundamentals, n.d.)

D. Mechanical Fastening and Assembly Process In mechanical fastening and assembly, various different types of hardware or fasteners (bolts, nuts, screws, etc.) to assemble multiple parts together. This method is great for an assembly that is not permanent, needs maintenance, adjustments, and replaceable parts because it allows the flexibility to remove and reinstall hardware. (Types of Joining and Assembly in Metal Manufacturing, 2014)

E. Drilling Process Drilling is the process of cutting holes in metals by using a drilling machine such as drills. Drilling is done by forcing a rotating drill into stationary job as on a drilling machine or by forcing stationary drill in a rotating work piece as on a lathe. (Elhamayel, 2015)

Related Literature Work related musculoskeletal disorders are supposed to be casually linked to physical load lifting resulting from occupational activities. Disorders or injuries affecting muscles, tendons, joints, ligaments and bones are mainly by mechanical overload of the respective biological structures. Examples of occupational activities coinciding with high mechanical requirements are handling of objects as in

transportation jobs or the application of pushing or pulling forces to tools and machines. (Luttman, Jager, & Griefahn, 2003) Dry engine weight or no fluids, without accessories, for most but not all engines can range anywhere between 130 to 350kg (approx 300–800lbs). (Rajaraman, 2017) Handling of heavy objects is a daily activity in most machine shops, welding and fabrication workshops and with the consistent maintenance need to mount heavy objects in machines, overhaul motor vehicle engines once in a while, handling of such heavy objects or engine has become a major problem in operational/automobile workshops, occasioning musculoskeletal injuries at most times where humans directly handle the carriage and installation of the vehicle engines and axles. That machining, welding and fabrication and auto mechanics work are laborious is a common saying born from the fact that most carriage and handling jobs in most workshops are purely manually executed. There are however few shops who have shop cranes. (Ambali, 2014)

Figure 2.1 Structures of (a) a boom crane, (b) a tower crane and (c) a bridge/gantry crane. The issues of different types of crane shown in Figure 2.1 involve the ability of reducing the sway angle of the payload and moving it to a desired position with a fast crane motion. In order to successfully transport the load to a desired point, the load swings need to be minimized. The crane’s motion is prone to an excessive load swing that could affect the positioning accuracy, the quality, the effectiveness and the safety. Consequently, a failure to control the sway angles would lead to a difficulty in the automation of the system by the worker, together with a possible damage to the quality of the load or the operating environment around the construction work. In addition, it would take a longer time being required for the task’s completion and this may reduce the production volume. Statistics have shown that traditional docking equipment wastes more than 30% for fixing the load per the loading time.

Figure 2.2 Image of Hydraulic Engine Hoist

Engine hoists, also known as engine cranes are common repair tools that are often used in vehicle repair shops to remove or install gasoline or diesel engines in small and crowded vehicle engine compartments. They are also used in small workshops or other businesses to lift and move heavy objects. The design of these tools is fairly simplistic, yet they must be structurally secure in order to be used in these heavy-weight situations. (Andersen, Richard, Egan, & Javier) Crane accidents and emergencies are occurring with increasing frequencies in ports around the world. This is understandable due to rapidly increasing population of cranes, increasing crane dimensions resulting in reducing visibility and operator control, frequent adverse weather conditions, and also crane maintenance and operating procedures not keeping up with increasing risks and demands of a fast paced modern terminal. (Lam, 2007) Studies have shown that 90% to 95% of hydraulic failures are caused by the factors such as fluid contamination, over-pressurization, aeration, pump aeration, implosion, cavitation, poor hydraulic fluid viscosity, and excessive heat. Although many are related to each other, each has its own specific damage profile. One of the main problem in maintenance of hydraulic lifter is the contamination of its working fluid. It is often the primary cause of hydraulic failures, as it speeds up the rate of wear and tear on the pump. Contamination occurs when foreign material gets mixed into the hydraulic fluid. Foreign materials inside a closed hydraulic system are harmful, and impede operational efficiency. Contaminants can be in solid, liquid or

gaseous form. Improper cleaning of welding burrs breaking off in the system, or the absence of a filter to prevent particles from entering the hydraulic system can also introduce contaminants. Hydraulic pumps are designed to operate at specific pressure levels. When you subject a pump to pressures higher than its design specs call for, the pressure pushes against the many internal components making up the pump. This over-pressurization can result in greater and faster wearing, and lead to permanent failure. Another factor that causes failure in hydraulic system is the aeration. It pertains to the presence of air bubbles in the hydraulic fluid. When compressed air bubbles are exposed to pressure in the pump, it leads to an implosion effect that can remove metal debris from the pressure plates and raise the local temperature to extreme levels. When this occurs, the bubbles can collapse inwardly almost instantly in a violent manner generating intense shock waves. These shock waves can result in serious pump damage. Pump aeration happens when air is trapped in the hydraulic fluid, sucked into the pump via leaky inlet joints or faulty shaft seals. It’s marked by a loud, high-pitched sound with the pitch getting higher as the pressure rises. Excessive pump aeration causes the hydraulic fluid to appear milky, and the various components in the hydraulic system to become unstable. When the hydraulic fluid doesn’t completely fill the existing space in the pump, usually caused by the pump over speeding, cavitation occurs. The intake line being too long or too restricted, or abnormally high fluid viscosity. Cavitation produces a highpitched noise very similar to that of aeration.

Fluid viscosity in a hydraulic pump needs to be maintained at a specific level. When the level of viscosity becomes higher than required, it often leads to cavitation. On the other hand, when the level of viscosity is lower than it should be, it can result in too much heat and pump leaking. Excessive heat is most often a byproduct of other factors causing hydraulic failures, but can also be a trigger. Excessive heat is always a warning sign which should be addressed immediately to prevent further damage. In recognition of this need, this project intends to develop a made, affordable shop crane.

Related Study Today’s crane parts are made of different types of metals, heavy-duty cables, and can lift and move objects many times heavier than the loads of ancient times. In olden times, thousands of slaves had to be arranged whenever a heavy load had to be lifted or dragged. Engine hoist is a tool that is used to lift heavy objects. There are different situations and places, where hoist is required for lifting, so there are also different hoists that can do that job. These two most common types of hoists for this task are hydraulic and chain hoists. (Miller, 2014) Hydraulic hoist is most used hoist for car repairs and engine lifting. These engine hoists works with hydraulic cylinders. Hydraulic cylinder uses liquid fluid for lifting job. This hydraulic fluid often called hydraulic liquid is usually special oil. These tools usually come with maximum lift capacity from 1 ton (2000 lb) to 4

tons (8000 lb), and even up to 8 tons (16000 lb). Commonly used boom capacity in repair shops is 1-1/2 ton with a boom length of 55-5/8” and a maximum hook height of 63”. (SFA Company, 2013) Chain hoist, similar to hydraulic and electric hoist, is a tool that is used for lifting heavy loads. Person operating the hoist needs to pull the hand chain in order to lift up the load. It is widely used in stores and shopping malls for lifting store equipment, in different workshops and factories for lifting heavy parts and also in car service stations for lifting engines, transmissions, gearboxes and body parts, consists of hand chain, lifting chain with a hook and lifting mechanism, which consists of axle, cog and sprockets. To lift a load hoist operator needs to pull the hand chain. Chain hoist with maximum lift capacity of 2 ton (4000 lb), which is average lift capacity of hydraulic hoist, will cost just approx. 100 dollars. Because of their cheap price and ease of use, chain hoists are very popular in different work places like construction sites, sawmills and also in factories, but because of their limited movement, chain hoists are not that much used in car workshops as engine hoists. But if you have a place in your workshop or garage to install a chain hoist, it will be able to do the job of lifting an engine. (Miller, 2014)

Conceptual Framework

Input Infoware:  Machine Design  Strength of Materials  Machine Shop Practice Technoware:  Angle Bar  Bolts and Nuts  Drilling Machine  Grinder  Hack Saw or Metal Cutter  Welding Machine

Process 1. Design of Manual Mechanical Engine Lifter 2. Preparation of Tools 3. Measurement of required length 4. Cutting 5. Drilling 6. Welding 7. Assembling 8. Painting 9. Testing 10. Evaluation

Humanware:  Machine Operator  Welder Chart 1.

Paradigm of the Study

Output

Manual Mechanical Engine Lifter

Hypothesis A hypothesis stated that the Manual Mechanical Engine Lifter was acceptable to the end users considering the following variables such as functionality, efficiency, safety and its price. And was therefore tested statistically for acceptance or rejection. The group concluded that the research project was better in terms of costing which drastically reduced the price of the existing ones. Since it’s mechanically operated, it cannot have cavitation or liquid problems.

Definition of Terms 1. Deflection – is the degree to which a structural element is displaced under a load. a. It may refer to an angle or a distance 2. Electric arc – is an electrical breakdown of a gas that produces an ongoing electrical discharge. 3. Humanware – usually refers hardware and software that emphasizes user capability and empowerment and the design of the user interface. 4. Infoware – refers to the recorded documents and facts, such as designs, specifications and relevant theories that would help enable quick learning. 5. Manual Mechanic Engine Lift – is a tool used to lift and transfer engines and heavy loads -

It is designed for use in car repair shops and private garages

6. Mechanical Overload – the failure or fracture of a product or component as a result of a single event.

7. Mechanism – a system of parts working together in a machine -

A natural or established process by which something takes place or is brought about

8. Techno ware – refers to the objects and facilities that are significant from the viewpoint of technical concerns, as participative elements in performing tasks. 9. Torque – a twisting force that tends to cause rotation

Notes in Chapter 2 Ambali, A. O. (2014). Design and Manufacture of a Hydraulic. International Journal of Engineering Research and Science & Technology, 2. Retrieved November 5, 2017 Andersen, K., Richard, S., Egan, R., & Javier. (n.d.). Strength Analysis on an Engine Hoist. 8. Retrieved November 5, 2017 Arc Welding. (n.d.). Retrieved November 5, 2017, from Wikipedia: https://en.wikipedia.org/wiki/Arc_welding Arc Welding Fundamentals. (n.d.). Retrieved November 5, 2017, from Lincoln Electric: http://www.lincolnelectric.com/en-us/support/process-and-theory/pages/arcwelding-detail.aspx Basics of Grinding. (n.d.). Retrieved November 5, 2017, from Society of Manufacturing Engineers: https://manufacturing.stanford.edu/processes/Grinding.pdf Elhamayel, M. A. (2015, April 29). Drilling Machines and Operations. Retrieved November 5, 2017, from SlideShare: https://www.slideshare.net/Mohamed-AbuElhamayel/drilling-machines-and-operations Kharchenko, V. V. (n.d.). Strength of Materials. Retrieved November 5, 2017 Khurmi, R. S. (2007). A Textbook of Engineering Mechanisms. India: Chand (S.) and Co Ltd. Retrieved November 5, 2017 Lam, L. (2007). Crane Accidents and Emergencies –Causes, Repairs and Prevention. TOC ASIA 2007. Hong Kong. Luttman, A., Jager, M., & Griefahn, B. (2003). Preventing Muscoskeletal Disorders in the Workplace. Protecting Workers' Health. Retrieved November 5, 2017, from http://www.who.int/occupational_health/publications/en/oehmsd3.pdf Machine Design. (n.d.). Retrieved November 5, 2017, from Chegg: http://www.chegg.com/homework-help/definitions/machine-design-5 Machine Shop Practice. (n.d.). Retrieved November 5, 2017, from TPC Training: https://www.tpctraining.com/products/machine-shop-practices Metalworking. (n.d.). Retrieved November 5, 2017, from Wikipedia: https://en.wikipedia.org/wiki/Metalworking Miller, B. (2014, November 03). Different Engine Hoist Types and What They Are Used For? Retrieved from KnockOutEngine: http://www.knockoutengine.com/different-engine-hoist-types-and-what-they-areused-for/ SFA Company. (2013, March). 2 Ton Foldable Engine Crane - Operating Instructions & Parts Manual. Retrieved from Shinn Fu America: http://www.shinnfuamerica.com/Owners%20Manual/BH8026%202TonFoldableE ngineCrane/3347 Strength of Materials Basics and Equations | Mechanics of Materials. (n.d.). Retrieved November 5, 2017, from Engineers Edge: https://www.engineersedge.com/strength_of_materials.htm Types of Joining and Assembly in Metal Manufacturing. (2014, November 11). Retrieved November 5, 2017, from Vista Industrial Productions, Inc.: http://www.vistaindustrial.com/blog/types-of-joining-and-assembly-in-metal-manufacturing