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Thermal Process and Mild Steel Pipework - eCollege

By Floyd Henry,2014-07-09 03:40
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Thermal Process and Mild Steel Pipework - eCollege

Module 2: Geometry and Pattern

Development

Unit 5: Oblique Cylinders

Phase 2

Trade of Sheet Metalwork Phase 2

Module 2 Unit 5

List of Figures................................................................................................................ 4

List of Tables ................................................................................................................. 5

Document Release History ............................................................................................ 6

Module 2 Geometry and Pattern Development ......................................................... 7

Unit 5 Oblique Cylinders .......................................................................................... 7

Learning Outcome: .................................................................................................. 7

Key Learning Points: ............................................................................................... 7

Training Resources: ................................................................................................. 7

Key Learning Points Code: ...................................................................................... 7 Oblique Cylinders ......................................................................................................... 8

Exercise ...................................................................................................................... 8

Developed Pattern Procedure ...................................................................................... 9

The Right and Oblique Cylinders............................................................................... 10Self Assessment............................................................................................................ 12

Answers to Questions 1-2. Module 2.Unit 5 ............................................................... 13

Index ............................................................................................................................ 15

Unit 5 3

Trade of Sheet Metalwork Phase 2

Module 2 Unit 5

List of Figures

Figure 1 - Oblique Cylinders ........................................................................................... 8 Figure 2 - Developed Pattern ........................................................................................... 9 Figure 3 Right and Oblique Cylinders ........................................................................ 11

Unit 5 4

Trade of Sheet Metalwork Phase 2 Module 2 Unit 5

List of Tables

Unit 5 5

Trade of Sheet Metalwork Phase 2

Module 2 Unit 5

Document Release History Date Version Comments 26/07/06 First draft

09/10/06 Implemented edits from

Brendan Deasy.

Unit 5 6

Trade of Sheet Metalwork Phase 2

Module 2 Unit 5

Module 2 Geometry and Pattern Development Unit 5 Oblique Cylinders

Duration 8 Hours

Learning Outcome:

By the end of this unit each apprentice will be able to:

; Identify the properties of the oblique cylinder

; Identify the geometrical differences between the right cylinder and the oblique

cylinder

; Develop patterns for oblique cylinders cut by angular and curved planes

; Develop true shape of holes of intersection

Key Learning Points:

Plan and elevation layout. D

Transferral of points from false lengths to true D

lengths.

Oblique cylinder cutting planes. D

Intersection of oblique cylinders. D

Joint location/positioning. Rk

Oblique pattern development. D

Training Resources:

; Drawing instruments, equipment and materials

; Textbook: The Geometry of Sheet Metalwork

; Instructor handouts, drawings

Key Learning Points Code:

M = Maths D= Drawing RK = Related Knowledge Sc = Science

P = Personal Skills Sk = Skill H = Hazards Unit 5 7

Trade of Sheet Metalwork Phase 2

Module 2 Unit 5

Figure 1 - Oblique Cylinders

Oblique Cylinders

Exercise

1. Fig. 1 shows the elevation of an oblique cylinder. Develop the full template to the

dimensions given.

2. Fig. 2 shows the junction of two oblique cylinders. Draw the elevation given and

develop the full template for one leg, placing the seam on the short side. Scale: 1:10. 3. The elevation of intersecting cylinders of equal diameter is shown in Fig. 3. Develop

the full template for each cylinder with the seam on the short side. Scale: 1:5. 4. The inlet to a square tank is shown in elevation in Fig. 4. Develop the full template

for the cylindrical member with the seam at SS and draw also the true shape of the

hole required in the tank. Scale: 1:2.

5. The elevation of an elliptical tank is shown in Fig. 5; the bottom is a circular plate

350 mm in diameter. Develop the full template, locating the seam on the short side.

Scale: 1:5.

Unit 5 8

Trade of Sheet Metalwork Phase 2

Module 2 Unit 5

Figure 2 - Developed Pattern

Developed Pattern Procedure

1. Draw plan and elevation.

2. Divide the base on the plan into a number of parts, e.g. 12.

3. Bring these divisions up to the base in elevation, and then up parallel to the leaning

edge, as shown.

4. Project each division line on the elevation at right angles.

5. Choose a starting point A and with radius L from the plan, swing an arc to find B.

6. Continue to locate other points.

7. Construct the panels and add top and base.

Unit 5 9

Trade of Sheet Metalwork Phase 2

Module 2 Unit 5

The Right and Oblique Cylinders

The ordinary process of rounding up or rolling a pipe makes it circular in cross-section, but there are times when a pipe must be oval and not circular, as, for example, when a connecting piece is required between two circular holes which are in parallel planes, but not in perpendicular line with each other. Sometimes these cases prove troublesome, not because of any special degree of intricacy, but generally through failure to appreciate the simple geometrical difference between the right cylinder and the oblique cylinder. The one can so easily be mistaken for the other unless careful observation is exercised in noting the particulars given. For instance, the branches forming a "Y" piece might be taken for ordinary round or cylindrical pipes, but actually the pipes are oval in cross-section.

A very simple method of demonstrating the geometrical difference between these two cylinders is to take a number of pennies and place them one above another in an upright pile. If the pile stands vertically on a horizontal surface, as shown in Figure 3(a), then a right cylinder is represented. Suppose now that some small block is placed under the base at one side of the pile, causing the whole to lean over as shown in (b): this does not alter the geometrical properties of the pile itself. It is merely inclined at an angle to the vertical. Each penny is still at right angles to the central axis, and the pile still represents a right cylinder.

Let the small block now be removed so that the pile may return to its original position. If, now, each penny is pushed slightly forward, sliding on the one below, so that the pile as a whole, but not each penny, leans forward forming an angle with the vertical, as shown in Figure 3(c), then an oblique cylinder is represented. In this case it will be observed that the pennies do not lie at right angles to the central axis of the pile, as they do in the right cylinder. The figure at (d) shows the oblique pile titled into the vertical position, but the geometrical conditions remain the same.

Unit 5 10

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