MEM05 Metal and Engineering Training Package MEM05039B Perform advanced geometric development - conical Learner guide Version 1 Training and Education Support Industry Skills Unit Meadowbank Product Code: 5805
Acknowledgement The TAFE NSW Training and Education Support Industry Skills Unit, Meadowbank would like to acknowledge the support and assistance of the following people in the production of this learner resource guide: Writer: Prepared by Jim Miles from existing TAFE pulbilications Reviewers: Nathan Gilbert (South Western Sydney Institute) Stephen Davies (TES Industry Skills Unit) Project Manager: Stephen Davies Education Programs Manager TAFE NSW Enquiries Enquiries about this and other publications can be made to: Training and Education Support Industry Skills Unit, Meadowbank Meadowbank TAFE Level 3, Building J, See Street, MEADOWBANK NSW 2114 Tel: 02-9942 3200 Fax: 02-9942 3257 The State of New South Wales, Department of Education and Training, TAFE NSW, Training and Education Support Industry Skills Unit, Meadowbank, 2013. Copyright of this material is reserved to TAFE NSW Training and Education Support, Industry Skills Unit Meadowbank. Reproduction or transmittal in whole or in part, other than for the purposes of private study or research, and subject to the provisions of the Copyright Act, is prohibited without the written authority of TAFE NSW Training and Education Support, Industry Skills Unit Meadowbank. ISBN 978-1-74236-513-8
Table of Contents Introduction... 7 1. General introduction... 7 2. Using this learner guide... 7 3. Prior knowledge and experience... 8 4. Unit of competency overview... 8 5. Assessment... 10 Student organiser... 12 Topic 1: Principles of radial line development used in the metal fabrication industry... 13 Pattern development... 13 Radial line development terminology... 14 Uses of oblique cones... 17 Determination of true length of lines (TL)... 18 Pattern and templates... 25 Computerised development... 25 Review questions... 26 Topic 2: Application of radial line development to produce complex patterns for conical intersections... 27 Pattern development for right cones... 27 Conical lobsterback bends (tapered)... 30 Method to mark out pattern of conical intersections... 35 Suggested practical jobs and projects... 38 Job 1: Conical pipe connector... 38 Job 2: Offset flaring transition... 40 Job 3: Intersection of square duct with conical branch... 42 Job 4: Intersection of cylinder with conical branch... 44 Job 5: Intersection of cone with cylindrical branch... 46 Job 6: Intersection of cone with square branch (duct)... 48 Job 7: Intersection of cone with rectangular branch (duct)... 50 Answers to review questions... 52 Sample assessment (Theory)... 53 Answers to sample assessment (Theory)... 55 Terms and definitions... 56 Resource evaluation form... 57
Topic 1: Principles of radial line development used in the metal fabrication industry Pattern development Pattern development is used to produce templates or to develop a single pattern which is then cut, formed, joined, finished and installed to become a completed article. Objectives To demonstrate competence at the end of this topic you will be able to: identify occupational areas in the metal fabrication industry which use the radial line development method to produce patterns define terms commonly used in radial line development identify types of cones and their application identify the principles and applications of complex radial line development for right and oblique cones and conic sections correctly label and identify points and lines used in the layout of views and patterns describe the use of templates, identification and storage develop patterns for truncated and oblique conical sections on paper/sheetmetal to a tolerance of ±0.5 mm. Methods of pattern development There are three common methods of developing patterns/templates. These include: parallel line radial line triangulation Patterns based on the above methods may also be generated by a range of computer software packages. The methods used depend upon the geometric form of the article. In this resource we concentrate on the radial line development method to produce patterns for complex conical shapes. Uses of radial line development Radial line development is used in the following occupational areas of the metal fabrication industry. General manufacture Ventilation and air conditioning Stainless steel Cubicle manufacture Rainwater fittings Applications of radial line development for storage containers, buckets and funnels. ductwork, cowls and hoods. for kitchenware, food preparation equipment and handrails for switchboards, cabinets and cupboards such as rainwater heads and roof flashings. Radial line development is the common method used in the fabrication industry to develop patterns for conical articles. To understand how we use the radial line method you must think of the curved surface of a cone having a series of triangles radiating out from a common point called the apex to equal divisions on the circular base. The conic section may be part of either a right cone or an oblique (offset) cone. Complex conical shapes including hoods, intersections (penetrations), bends and elbows are developed using the radial line development method. The following articles are typical of those developed using the principles of radial line development. (a) Conical hood (b) Conical intersection (c) 90 Conical tapering elbow (Lobsterback) Page 13 of 60
Radial line development terminology Before you start to develop shapes it is important to understand the terminology used to describe geometrical terms. Terms and definitions commonly used in radial line development include: Axis Generator lines Projection line Seam True length True shape Base Curved surface Flat surface True shape of section Pattern blank is the centreline about which an object may rotate are the main dividing lines used in pattern development (used to determine slant heights around conical shape) is drawn from one view to another is where two edges are joined together is the length of a line viewed at right angles to the line (TS) is the shape of an object when viewed at 90 to its face is the bottom surface of an object is rolled or formed to a radius has no deviations (TSS) is the shape viewed when a prism is cut at 90 to its axis is the cutting size of the material, including allowances required for the pattern The above terminology will be referred to in this resource. Some examples are shown here: curved surface centre of base Curved surface apex axis Right cone Generator lines true slant height base generator line Chord Flat surface Circumference of base Pattern radius or slant height of cone Pattern of a right cone True slant heights Flat surface Types of cones There are two types of cones, right cones and oblique cones. Both types have a circular base but the position of the apex varies. Right cones Right cones are either full right cones or, if the top is removed, the remainder is called a frustum or truncated right cone. Full right cone A full right cone can be defined as a shape which has a circular base and a curved sloping surface which radiates from a point situated vertically above the centre of the base. The point is called the apex of the cone. Frustum of a right cone (conical frustum) A conical frustum is a right cone that has been cut by a plane parallel to its base. Truncated right cone (right conic sections) A truncated right cone is a right cone that has been cut by a plane or planes not parallel to its base. Full right cone Frustum of a right cone Oblique cone Centre of base Pattern of an oblique cone. Truncated right cone Page 14 of 60
Oblique cones (offset) Oblique cones are either full oblique cones or, if they are cut, the remainder is called a frustum or truncated oblique cone. Identification of cones A single view drawing as shown below, an object may be either a right or offset cone You may use the following method to determine which it is: Full oblique cone An oblique cone, often referred to as an offset cone, is a three dimensional shape with a circular base and curved sloping surface that radiates from the apex which is not above the centre of the base. There are three (3) types of full oblique cones, as shown below: on the base inside the base outside the base of the circle of the circle of the circle Frustum of oblique cone An oblique conical frustum is an oblique cone that has been cut by a plane parallel to its base. Truncated oblique cone A truncated oblique cone is an oblique cone that has been cut by a plane or planes not parallel to its base. Example 1: Single view drawing 1. Extend the outlines of the single view drawing to make a triangle with a horizontal base. 1. 2. 2. Find the centre of the triangle base and extend the axis of the object. If the three lines go through the same point (apex) then the object is a cone if the triangle formed is isosceles (opposite sides equal) or equilateral (all sides equal) then the object is a right cone if the triangle formed is scalene (no sides equal) then the object is an oblique cone. Note: To accurately mark out a pattern for cones the apex height must be determined either geometrically or by calculations. If the three lines do not intersect at the same point (apex), as illustrated below, the radial line development method is unsuitable and another method of development will need to be used. Frustum of an oblique cone Truncated oblique cone Single view drawing Page 15 of 60
Exercise 1 Using the single view drawings shown below determine if the objects are: point (a) right cone (b) right cone offset cone neither of the above Calculation for cones offset cone neither of the above To accurately mark out a pattern for a cone, its dimensions must be determined either geometrically or by calculations. The calculations relating to cones include: Circumference of a circle = C = D = 2 R Hypotenuse of a right angled triangle = c = a 2 + b 2 Referring to sketch of the cone opposite; Pattern radius = PR = H 2 + R 2 Included angle = IA = C x 180 degrees = 180D PR x PR Chord length = CL = 2 x PR x sin(½ia) D R c a b (SH) Slant height (pattern radius) (sht) Slant height frustum Small diameter (d) Large diameter (D) Diameter of base Applications of cones Radius of base (R) Frustum height (h) height (H) Cones have many uses within industry and for domestic purposes. Examples of articles based on right cones are: round air duct connectors funnels parts of cyclone separators light poles covers exhaust hoods transit cement mixers buckets Examples of articles based on oblique cones are: round pipework connectors hoppers chutes funnels reducers silos. Included Angle (IA) Chord Length (CL) cowls vats hoppers and chutes tundishes flashings reducers silos. Circumference (C) Pattern Radius (PR) Page 16 of 60
Uses of oblique cones Oblique conical shapes are used for many applications. The various shapes or types of oblique cones are used in industry for transporting and storing materials, ventilation systems, large pipeline transitions and are formed to shape from developed patterns on flat materials. Truncations of oblique cones A truncated oblique cone is the base section of an oblique cone whereby the base or top is cut at an angle other than 90 to the vertical plane. The sketches below show various front view examples of truncated oblique cones. Examples: petro-chemical industry: LPG tankers, oil and chemical storage / transfer mining industry: ore crushing plant, storage and transfer systems power generation plants: hydropipework, ventilation ducting domestic uses: hoods, funnels and flues. Oblique cones (offset cones) Oblique cones are either full oblique cones or, if they are cut, the cone is called a frustum or truncated oblique cone. Frustums of oblique cones A frustum of an oblique cone is the base section below a cutting plane, parallel to the horizontal base. The following sketches show the three types of frustum of oblique cones: TOP VIEW TOP VIEW TOP VIEW Top truncated Base truncated Obtuse angle FRONT VIEW 90 angle FRONT VIEW Acute angle FRONT VIEW Top and base truncated Page 17 of 60