Riveted joints

This topic helps you to understand very well about riveted joints.

1. RIVETED JOINTS

2. Sub Topics: Different types of riveted heads. Single riveted lap joint. Double riveted chain lap joint. Double riveted Zig-Zag lap joint. Single riveted single strap Butt joint. Single riveted double strap Butt joint. Double riveted double strap Butt joint. Double riveted double strap Zig-Zag Butt joint.

3. Introduction of Riveted Joints: Riveted joints are permanent fastenings and riveting is one of the commonly used method of producing rigid and permanent joints. Manufacture of Boilers, storage tanks etc… involve joining of steel sheets, by means of riveted joints.

4. Rivets as permanent joints: Often small machine components are joined together to form a larger machine part. Design of joints is as important as that of machine components because a weak joint may spoil the utility of a carefully designed machine part. Mechanical joints are broadly classified into two classes viz., non-permanent joints and permanent joints . Non-permanent joints can be assembled and dissembled without damaging the components. Examples of such joints are threaded fasteners (like screw-joints), keys and couplings etc. Permanent joints cannot be dissembled without damaging the components. These joints can be of two kinds depending upon the nature of force that holds the two parts. The force can be of mechanical origin, for example, riveted joints, joints formed by press or interference fit etc, where two components are joined by applying mechanical force. The components can also be joined by molecular force, for example, welded joints, brazed joints, joints with adhesives etc.

5. Rivet: A rivet is a round rod of circular cross-section. It consists of two parts…Head & Shank

6. Riveting: Riveting is the process of forming a riveted joint. For this, a rivet is first placed in the hole drilled through the two parts to be joined. Then the shank end is made into a rivet head by applying pressure, when it is either in cold or hot condition.

7. Different types of Riveted Heads: Various forms of rivet heads, used in general engineering works and boiler construction and as recommended by Bureau of Indian Standards , are shown in Fig… The standard proportions are also indicated in the figure. Snap head High button head Pan head Cone head Round top countersunk head Flush countersunk head Flat head Truss head

8. Important terms used in riveted joints: Few parameters, which are required to specify arrangement of rivets in a riveted joint are as follows: Pitch : It is the distance between the centers of the adjacent rivets in the same row. It is denoted by ‘ p ’ and usually taken as 3 d , where d is the rivet diameter. Row Pitch : It is the distance between two adjacent rows of rivets. It is denoted by ‘p r ’ and is given by, p r = 0.8p, for chain riveting p r = 0.6p, for Zig-zag riveting. Diagonal pitch : This term is usually associated with zig -zag riveting and is denoted by ‘p d ’. It is the distance between the centre of a rivet in a row to the next rivet in the adjacent row. Margin or marginal pitch : It is the distance from the edge of the plate to the centre of the nearest rivet. It is usually taken as 1.5 d , where d is the rivet diameter. It is denoted by ‘ m ’. Back Pitch : This is the shortest distance between two successive rows in a multiple riveted joint. (usual symbol p t or p b )

9. Types of riveted joints and joint efficiency: Riveted joints are mainly of two types Lap joints Butt joints Lap joints : The plates that are to be joined are brought face to face such that an overlap exists, as shown in fig. Rivets are inserted on the overlapping portion. Single or multiple rows of rivets are used to give strength to the joint. Depending upon the number of rows the riveted joints may be classified as single riveted lap joint, double or triple riveted lap joint etc. When multiple joints are used, the arrangement of rivets between two neighboring rows may be of two kinds.

10. Single Riveted Lap joint:

11. Double Riveted chain Lap joint:

12. Double Riveted Zig-Zag Lap joint:

13. Butt Joint : In this type of joint, the plates are brought to each other without forming any overlap. Riveted joints are formed between each of the plates and one or two cover plates. Depending upon the number of cover plates the butt joints may be single strap or double strap butt joints.

14. Single Riveted single strap Butt joint:

15. Single Riveted double strap Butt joint:

16. Double Riveted double strap Butt joint: