Elif Naz Aladağ, 030060027, 8th Week

Octree representation (March 31, 23:14):

An octree is a recursive decomposition of a cubic space into subcubes. The octree representation of a workspace has often been used in heuristic path planning approaches that are designed to be efficient. In an octree representation, initially, the root node is used to represent the workspace. If the whole workspace is not completely filled by objects or completely empty, it will be split into eight equal subcubes (octants), which become the children of the root. This process continues until all the nodes are completely filled or not completely empty, or until some resolution limit is researched.

(Sheu, P. C-Y., Kue, Q., Intelligent Robotic Planning Systems, p. 122)

Servomechanisms (Servomechanizm) (March 31, 23:59):

A servomechanism is a power-amplifying feedback control system in which the controlled variable is mechanical position, or a time derivative of position such as velocity or acceleration.

DiStefano, J. J., Stubberud, A. R., Williams, I. J., Feedback and Control Systems, p. 22

Burcu Atay, 140060029, 8th week

Hydraulics

Hyraulic motors are mainly used for heavy-duty machines that require high torque or force. Control of hyraulic motor is, however, more difficult due to nonlinear characteristics of various components in the hyddraulic system. These actuators are used to construct feed drives and, therefore, are required to have good velocitycontrollability. Asignal from the controller is amplified and supplied to the motor. The motor produces a torque to rotate the shaft through a coupler, while linear motors drive the table directly. The position or velocity signal measured by an encoder, a resolver, or a

tachometer is fed back to the controller so that closed-loop control of the feed drive can be achieved.

(Dorf, R.D., Kusiak, A., Handbook of Design, Manufacturing and Automation,1994, pg.247)

Cladding

Explosive welding or cladding, as it is often called, brings together two metal surfaces with sufficient impact and pressure to bond. Pressure is developed by a high-explosive shot placed in contact with or in close proximity to the metals. In some instances a protective material such as rubber is placed over the upper panel to prevent damage to the surface. The entire assembly is placed upon a buffer plate or anvil to absorb energy generated during yje jıining operation. Of the two arrangements showing cladding or laminating of metals, the left one is preferred.

To obtain a metallurgical bond, atoms from boh surfaces must come into intimate contact. The oxides and films always present on the surface of metals are broken or dispersed by high

pressure or dissolved in the molten region. The explosive force brings the clean surfaces together and produces a sound bond.

(Amstead, B. H., Ostwald,P. F., Begeman, M. L., MAnufacturing Processes,8th Edition, pg. 189)

Cupola

Heat is provided externally ( for example, by electric, gas , or oilheating), internally(as by electic induction) or, only for cast iron, by mixing the fuel with the charge itself. CAst iron is usually melted semicontinuously in a vertical shaft furnace (cupola); lining of the cupola with a refractory is being abondened in favor of water-cooled steel jackets. The charge is mixe

d with coke and some minerals(primarily limestone, CaCO3), and hot air is blown through the column. Coke burns to give heat and is also a source of carbon for the cast iron. The liquid metal is tapped at the bottom, seperately from the slag which is formed by the limestone with nonmetallic contaminants and metal oxides. In the duplex process, the liquid metal is tapped into an electic holding furnace where alloying and suğerheating is also practiced.

(Schey, J., A., Introduction to Manufacturing Processes, 2nd Edition, pg.148-149)

Feedforward Control

The strategy in feedforward control is to anticipate the effect of disturbances that will upset the process by sensing them and compansating for them before they can affect the process. As shown in Figure, the feedforward control elements sense the presence of a disturbance and take corrective action by adjusting a process parameter that compensates for any effect the

disturbance will have on the process. In the ideal case, the compensation is completely effective. however, complete compensation is unlikelybecause of imperfections in the feedback measurements, actuator operations, and control algorithns, so feedforward control is usually combined with feedback control, as shown in our figure. Regulatory and feedforward control are more closely associated eith the process industries than with discrete production manufacturing.

(Groover, M. P., Automation, Production Systems and Computer-Integrated Manufacturing, 3rd Edition, pg.93)

Ozlem Salman (8. week)

1 Hydraulics 2 Pneumatics 3 AC motor 4 DC motor 5 Stepper motor 6 Servomechanizm 7 Potentiometer 8 3D blow molding 9 Coextrusion 10 Octree represantation

Doğuş Cendek 030060101 8th week

Adhesion (in turning) (31.03 11.36) Mechanical adhesion is that portion of total adhesion provided by physical entrapment of portions (larger than molecul size) of one phase of joint in another.Specific adhesion includes formation between any two surface of bonds based on primary valence force,secondary valence forces or combination of the two. (Instutation of Mechanical Engineers,Adhesion,p. 33) Figure 1: Ferguson's Paradox (modern design) Ferguson's Paradox (31.03 11.52) It would appear from our memoranda as also from other references,that it was during the year 1750 that Ferguson invented and celebrated machine called 'The Mechanical Paradox'.In several of his works he mentions that he made it 'On a vary particular occasion' but without informing us of anything regarding this 'particular occasion'.But it is now certain that be made this curious machine for the purpose of silencing of London watchmaker who did not believe in the doctrine of Trinity as will be shown by a vary interesting letter ,written by Ferguson a few months before his death to a clericel friend of his in the north of Scotland a copy of which the reader will find at the conclusion of description of the Paradox. (Ferguson J.,Life of James Ferguson,p.139) Figure 2: Ferguson's Paradox (The First Design) Flank Wear (31.03 12.31) The contact condition on the tool flank surface is of interest due to its impact on modeling of tool flank wear and the integrity of the machine surface.The way to look the problem is to understand physical processes taking place at the tool workpiece interface which is known as flank contact area.The contact processes on the tool flank are determined by the normal and the frictional forces acting at the tool/workpiece interface.The flank wear of the cutting tool increases with increasing averange normal stress acting along the flank face and the number of hard ceramic particles contacting the cutting tool and decreasing with increasing tool hardess. (Kannan S.,Machining of Metal Matrixe Composite:Forces,Tool Wear and Attainable Surface Quality,p. 102) Ratchet Mechanism (31.03 12.47) It consist of wheel calles Ratchet with saw-shaped teeth which engage with an arm called a pawl. The arm is pivoted and can move back and forth to engage the wheel.The shape of teeth are such that rotation can occur in only one direction. (Onwubolu G.C.,Mechatronics:Principles and Applications,p. 380)

Figure 3: Ratchet Mechanism

Ahmet Alp Gündüz - 030060034 - 8th Week

Residual-stress Distribution (31 Mart 2011 07:09)

Residual stresses induced by machining operations can be assessed directly using, for instance, the X-ray diffraction method to measure the distance between planes of atoms, or indirectly, employing strain gauges or optical, electronic or mechanical displacement transducers to determine the deformation induced when the stresses are relieved. The residual stresses induced on a component are the result of a combination of mechanical and thermal effects. In general, the mechanical action (burnishing) leads to plastic deformation and promotes compressive residual stresses. The thermal effect (temperature rise due to friction and plastic strain) however, may promote tensile or compressive residual stresses depending on the maximum temperature reached at the workpiece and corresponding microstructural changes that take place. For instance, the transformation from austenite to martensite during rapid cooling (by the bulk material, cutting fluid or air) involves a volume expansion caused by the change from a face-centred cubic structure to a more open tetragonal structure, thus resulting in compressive stresses in the surface layers. The layers beneath the surface, however, reach lower temperatures and cool at slower rates, therefore, their contraction is restrained by the higher strength of the layers above. Consequently, tensile residual stresses may be induced below the machined surface. The resulting residual stress depends on the magnitude of the mechanical and thermal effects, nevertheless phase transformation induced by cutting can be neglected as a cause of residual stresses on hardened steels.

(Machining of Hard Materials, J. Paulo Davim; Page:129-130)

Microstructural Alterations (31 Mart 2011 07:09)

Microstructural changes in steels may be either mechanically or thermally induced. In the case of hardenable steels, if the workpiece temperature exceeds the austenization temperature during machining (due to friction and plastic strain), austenite will be formed and, after quenched by the cold bulk material or by the cutting fluid, a brittle, highly stressed and crack-prone martensite layer (usually called a white layer) is formed at the surface. However, if the workpiece temperature exceeds the tempering temperature only, then overtempering will take place, leading to the softening of the affected layers (identified as a dark layer after etching). The formation of the white layer is a thermal process involving phase transformation and, probably plastic deformation, which has not been fully understood yet. Turning tests on hardened AISI H13 tool steel (54–56 HRC) with PCBN inserts indicated that the hardness and depth of the white layer decreased as cutting speed was elevated owing to a slight reduction in the workpiece temperature. In

contrast, neither a white layer nor a heat affected zone were observed after high-speed milling AISI H13 hot-work die steel hardened to 47–49 HRC with TiAlN coated carbide ball-nose endmills. This difference can be explained by the fact that in the former work cutting speeds of 100, 400 and 700 m/min were tested, the thickest white layer being observed at the lowest cutting speed. For cutting speeds of 400 and 700 m/min, the depth of the white layer decreased dramatically. In the case of the latter work, cutting speeds of 200 and 300 m/min were used, which seem to be above the critical value required for the formation of the white layer.

(Machining of Hard Materials, J. Paulo Davim; Page:124-125)

Stepper Motors (31 Mart 2011 15:22)

The essential property of the stepping motor is its ability to translate switched excitation changes into precisely defined increments of rotor position (‘steps’). Stepping motors are categorised as doubly salient machines, which means that they have teeth of magnetically permeable material on both the stationary part (the ‘stator’) and the rotating part (the ‘rotor’). Magnetic flux crosses the small airgap between teeth on the two parts of the motor. According to the type of motor, the source of flux may be a permanent-magnet or a current-carrying winding or a combination of the two. However, the effect is the same: the teeth experience equal and opposite forces, which attempt to pull them together and minimise the airgap between them. As the diagram shows, the major component of these forces, the normal force (n), is attempting to close the airgap, but for electric motors the more useful force component is the smaller tangential force (t ), which is attempting to move the teeth sideways with respect to each other. As soon as the flux passing between the teeth is removed, or diverted to other sets of teeth, the forces of attraction decrease to zero.

(Stepping Motors a Guide to Theory and Practice, 4th edition, Paul Acarnley; Page:1)

3D Blow Molding (31 Mart 2011 15:57)

3D blow molding was introduced to

• Reduce flash

• Lower clamping forces

• Improve wall thickness distribution

• Reduce finishing work on the outside surface

3D blow molded parisons are made by moving the tool as the parison is pushed out of the die or accumulator. This lays the parison into the 3D mold. Alternatively, a robot arm can be used to position the parison. This process has gained its name from the three dimensional parison manipulation. In the first step, the parison is laid across the bottom of the tool; in the subsequent two steps, the bottom half of the tool moves downward as the parison is laid across its surface. After the parison is completely across the bottom mold, the top half closes to clamp the parison just prior to inflation.

(Extrusion: The Definitive Processing Guide and Handbook, Harold F. Giles, Jr., John R.Wagner, Jr.; Eldridge M. Mount, III; Page: 509)

Hüseyin E. DEMİRTAŞ - 8th Week

1. Microstructural Alterations

2. Hardness Alterations

3. Residual-stress Distribution

4. Fatigue Strength

5. Response Surface Methodology

6. Evolutionary Algorithms

7. Crater wear (in Turning)

8. Notch wear (in Turning)

9. Flank wear (in Turning)

10. Adhesion (in Turning)

M. Burak Toprakoğlu - 030070082 - 8th week

Worm Gear: (02:16 - 31.03.2011)

In worm gears, the axes are non- intersecting and the planes containing the axes are normally at right angle to each other. Worm- gear is a special case of a crossed helical gear or spiral gear in which the shaft angle is 90o. The hand of helix is the same for both mating gears. To get large speed reduction in skew shafts and to transmit a little higher load than usual spiral gear, use of worm and worm gears can be made. Worm gears have wide application in hoisting equipments, due to the itself locking ability.

A single-enveloping worm gear set has a cylindrical worm with a throated gear wrapped around the worm and there is a line contact between the teeth.

A double-enveloping worm gear set has both members throated and wrapped around the worm each other and there is a area contact between the teeth.

The worm gear is normally the driven member of the pair and is amde to envelop (or wrap around) the worm. The axis length of the worm is increased so that at least one or two threads, called as teeth, complete the circle on it.

The worm is a member having the screwlike thread and worm theet are frequently named as threads. Worms in common use have 1 to 8 teeth, and, as well as there is no definite relation between the number of teeth and the pitch diameter of a worm. Worms may be designed with a cylindrical pitch surface as shown in the figure. A worm can be single, double or triple start.

(Theory of Machines and Mechanisms - II, H.G Phakatkar, p.636-637)

Response Surface Methodology: (03:41 - 31.03.2011)

Response surface methodolgy (RSM) is a collection of statistical an d mathematical techniques useful for developing, improving, and optimizing processes. It also has important applications in the design, development, and formulation of new products, as well as in the improvement of existing product designs.

The most extensive applications of RSM are in the industrial world, particularly in situations where several input variables potentially influence some performance measure or quality characteristics of the product or process. This performance measure or quality characteristics is called response. It is typically measured on a continuous scale, although attribute responses, ranks, and sensory responses are not unusual. Most real-world applications of RSM will involve more than one response. The input variables are sometimes called independent variables, and they are subject to the control of the engineer or scientist, at least for purpose of a test or an experiment.

(Response surface methodology: process and product optimization using designed experiments ,Raymond H. Myers,Douglas C. Montgomery,Christine M. Anderson-Cook, 3rd Edition, p.1)

Potentiometer: (18:11 - 31.03.2011)

A potentiometer is a device that is designed to measure an unknown e.m.f by comparing it with known e.m.f. The konwn e.m.f may be obtained from a standart cell or any other standart cell. If any one of the e.m.f.s is known, then other unknown e.m.f can be obtained by only comparison of unknown e.m.f with known e.m.f. i.e a standart e.m.f.

The result obtained with potentiometer are with high degree of accuracy, because the e.m.f measurement is done by comparison method and result is not dependent upon the deflection of pointer actually. Thus,the degree of accuracy totally depends upon the accuracy with which the reference voltage is known.

The potentiometer makes use of balance or null condition for the unknown e.m.f. measurement, then under the balance condition no current can flow through any element in the branch consisting the unknown e.m.f. Thus the potentiometer can measure e.m.f of source which is not dependent on the source resistance. As no current flows the branch consisting unknown e.m.f., there is no voltage drop across source resistance.

The main application of the potentiometer is to measure e.m.f., it can also be used for the current measurement by measuring voltage due to unknown current across known standart resistance. Then by ohm's law, the unknown current can be obtained. Along with this the potentiometers can also be used for the calibration of voltmeters and ammeters, for testing of energymeter and wattmeter, for the measurement of self resistance.

There are two types of potentiometers; namely

1) D.C. potentiometer
2) A.C. potentiometer

(Electrical Measurements & Measuring Instruments, K.A.Bakshi A.V.Bakshi U.A.Bakshi, 1st Edition, 2007, p. 5-1)

Coextrusion: (18:38 - 31.03.2011)

Coextrusion is the simultaneous extrusion of two or more polymers through a single die where the polymers are joined together such that they form distinct, well-bonded layers forming a single extruded part. Coextrusion has been applied in film, sheet, tubing, blown film, wire coating, and profile extrusion.

Advantages of coextrusion are better bonds between layers, reduced materials and processing costs, improved properties, and reduced tendency for pinholes, delamination and air entrapment between the layers. Another advantage is that it is often possible to reuse scrap material and locate it in an inside layer of the extruded product. so that it does not affect the appearance of the product. An obvious disadvantage of coextrusion is that the tooling is more difficult to design and manufacture and, therefore, more expensive.. Further, it requires at least two extruders and it takes more operational skill to run a coextrusion line.

(Polymer extrusion, Chris Rauwendaal, 4th Edition, p.567)

Aycan PARLAK -- 030060129 - 8th Week

Pantograph Mechanism

A pantograph is a combination of links which are so connected and proportioned as to length that any motion of one point in a plane parallel to that of the link mechanism will cause another point to follow a similar path either on an enlarged or a reduced scale. Such a mechanism may be used as a reducing motion for operating a steam engine indicator, or to control the movements of a metal cutting. For instance, most engraving machines have a pantograph mechanism interposed between the tool and a tracing point which is guided along lines or grooves of a model or pattern. As the tracing point moves, the tool follows a similar path, but to a reduced scale, and cuts the required pattern or design on the work.

A simple form of pantograph is shown by the diagram, Fig. 12. There are four links, a, b, c and d. Links a and b are equal in length, as are links c and d, thus forming a parallelogram. A fifth connecting link e is parallel to links c and d. This mechanism is a free to swivel about a fixed centre f. Any movement of h about f will cause a point g (which coincides with a straight line passing through f and h )to describe a path similar to that followed by h, but on a reduced scale. For instance, if h were moved to k following the path indicated by the dotted line, point g would also trace a similar path.

( Franklin Day Jones, Mechanisms and Mechanical Movements, Elibron Classics, 2005, p. 19-20)

Toggle Joint

A link mechanism commonly known as a toggle joint is applied to machines of different types, such as drawing and embossing presses, stone crushers, etc., for securing great pressure. The principle of the toggle joint is shown by diagrams A and B, in Fig. II.

There are two links, b and c, which are connected at the center. Link b is free to swivel about a fixed pin or bearing at d, and link c is connected to a sliding member e. Rod f joints links b and c at the central connection. When force is applied to rod f in a direction at right angles to centre-line xx, along which the driven member e moves, this force greatly multiplied at e, because a movement at the joint g produces a relatively slight movement at e. As the angle é becomes less, motion at e degreases and the force increases until the links are in line, as at B. If R= the resistance at e, P= the applied power or force, and é= the angle between each link and a line xx through yhe axes of the pins then: 2R sin é =P cos é.

( Franklin Day Jones, Mechanisms and Mechanical Movements, Elibron Classics, 2005, p. 18-19)

Notch Wear

Notch wear is often attributed to the oxidation of the tool material from the sides of major and minor cutting edges, or to abrasion by the hard, saw- tooth outer edge of the clip ( for example, in hard machining). Notching is serious technological problem with workpiece materials that tend to have high work-hardening and generate high tool-tip temperatures, such as austenitic stainless steels and nickel-based superalloys. Notch wear can obviously lead to tool fracture and can be minimized by applying tools with chamfered edges, rounded inserts and avoiding small depth of cut.

( Wit Grzesik, Advanced Machining Processes of Metallic Materials, Elsevier BV. 2008, p.165)

Crater Wear

In metal cutting, the highest temperatures occur along some length of tool face. At high cutting speeds, these temperatures can be of the order of 1000 degree of C or more. There is a thermal softening and HSS tools wear rapidly. In carbide tools, solid-state diffusion at these temperatures can cause rapid wear.

A crater is formed on the tool face taking the shape of chip under side. This factor determines the life of the cutting tool. The cratering becomes very severe and the tool edge is weakened and fractured.

(R.K. Singal, Mridul Signal, Rishi Signal, Fundamentals of Machining and Machine Tools, I.K. International Pub., 2008, p.233 )

Gani Can Öz - 8th Week

1	Crank Mechanism
2	Lever Mechanism
3	Ratchet Mechanism
4	Pantograph Mechanism
5	Cam Mechanism
6	4 Bar Linkage
7	Ferguson's Paradox
8	Hook's Coupling (Universal Joint)
9	Toggle Joint
10	Worm Gear

Gani Can Öz - 503101305

Onur OZAYDIN___8th Week

1. Retaining (Snap) Ring (About Assembly)

2. Stitching

3. Stapling

4. Sewing

5. Cotter Pins

6. Preload (Force)

7. Acid Cleaning (About Surface Treatments)

8. Blast Finishing

9. Vibratory Finishing

10. Emulsion Cleaning

503101307 Onur OZAYDIN