  Two plates or pieces to be riveted together have holes punched or drilled in them in such a manner that one may be made to overlap the other so that the holes in the one may be opposite the holes in the other. The rivets, which are round bars of iron, or steel, or other metal, are heated to redness and inserted in the holes; the head already formed on the rivet, and called the tail, is then held up, and the point is hammered or pressed so as to form another head. This process of Forms of Rivet Heads.—In fig. 1 are shown four different forms of rivet heads: (a) is a snap head, (b) a conical head (c) a pan head, and (d) a countersunk head. Proportions of Rivet Heads.—The diameter of the snap head is about 1·7 times the diameter of the rivet, and its height about ·6 of the diameter of the rivet. The conical head has a diameter twice and a height three quarters of the rivet diameter. The greatest diameter of the pan head is about 1·6, and its height ·7 of the rivet diameter. The greatest diameter of the countersunk head may be one and a half, and its depth a half of the diameter of the rivet. Fig. 1. Fig. 1. In fig. 1 at (a) and (b) are shown geometrical constructions devised by the author for drawing the snap and conical head for any size of rivet, the proportions being nearly the same as those given above. Geometrical Construction for Proportioning Snap Heads.—With centre A, and radius equal to half diameter of rivet, describe a circle cutting the centre line of the rivet at B and C. With centre B and radius BC describe the arc CD. Make BE equal to AD. With centre E and radius ED describe the arc DFH. Construction for Conical Head.—With centre K, and radius equal to diameter of rivet, describe the semicircle LMN, cutting the side of the rivet at M. With centre M and radius MN When a number of rivets of the same diameter have to be shown on the same drawing the above constructions need only be performed on one rivet. After the point E has been discovered the distance AE may be measured off on all the other rivets, and the arcs corresponding to DFH drawn with radii equal to ED. In like manner the height KP of the conical head may be marked off on all rivets of the same diameter with conical heads. Caulking.—In order to make riveted joints steam- or water-tight the edges of the plates and the edges of the heads of the rivets are burred down by a blunt chisel or caulking tool as shown at Q and R. Fig. 2. Fig. 2. Fig. 3. Fig. 3. Exercise 1: Forms of Rivets.—Draw, full size, the rivets and rivet heads shown in fig. 1. The diameter of the rivet in each case to be 11/8 inches, and the thickness of the plates 7/8 inch. Exercise 2: Single Riveted Lap Joint.—Draw, full size, the Table showing the Proportions of Single Riveted Lap Joints for various Thicknesses of Plates. (Plates and Rivets Wrought Iron.)
All the dimensions are in inches. Fig. 4. Fig. 4. Exercise 3.—Draw, half size, a plan and section of a single riveted lap joint for plates 3/4´´ thick to the dimensions given in the above table. Exercise 4: Double Riveted Lap Joint.—Draw, full size, the two views of the double riveted lap joint shown in fig. 3. Table showing the Proportions of Double Riveted Lap Joints for various Thicknesses of Plates. (Plates and Rivets Wrought Iron.)
Fig. 5. Fig. 5. Exercise 5.—Draw, half size, a plan and section of a double riveted lap joint for plates 7/8 inch thick to the dimensions given in the above table. Exercise 6: Single Riveted Butt Joints.—In fig. 4 are shown single riveted butt joints. One of the sectional views shows a butt joint with one cover plate or butt strap; the other sectional view Fig. 6. Fig. 6. Exercise 7.—Fig. 5 shows a plan and sectional elevation of the connection of three plates together, which are in the same plane, by means of single riveted butt joints and single cover plates. The butt straps where they overlap are forged so as to fit one another as shown, and thus form a close joint. Draw these views to the scale of 6 inches to a foot. The plates are 1/2 inch thick and the butt straps 9/16 inch thick. All other dimensions must be deduced from the table for single riveted lap joints. Exercise 8.—The connection of three plates by single riveted lap joints is shown in fig. 6. To make the joint close one plate has a portion of its edge thinned out, and the plate above it is set up at this part so as to lie close to the former. Draw the three views shown in fig. 6 to the same scale as the last exercise. The plates are 7/16 inch thick. All other dimensions to be obtained from table for single riveted lap joints. Exercise 9: Corner of Wrought-iron Tank.—This exercise is to illustrate the connection of plates which are at right angles to one another by means of angle irons. Fig. 7 is a plan and elevation of the corner of a wrought-iron tank. The sides of the tank are riveted to a vertical angle iron, the cross section of which is clearly shown in the plan. Another angle iron of the same dimensions is used in the same way to connect the sides with the bottom. The sides do not come quite up to the corner of the vertical angle iron, excepting at the bottom where the horizontal angle iron comes in. At this point the vertical plates meet one another, and the edge formed is rounded over to fit the interior of the bend of the horizontal angle iron so as to make the joint tight. Draw half size. The dimensions are as follows: angle irons 2½ inches × 2½ inches × 3/8 inch; plates 3/8 inch thick; rivets 11/16 inch diameter and 2 inches pitch. Exercise 10: Gusset Stay.—In order that the flat ends of a steam boiler may not be bulged out by the pressure of the steam they are strengthened by means of stays. One form of boiler stay, called a 'gusset stay,' is shown in fig. 8. This stay consists of a strip of wrought-iron plate which passes in a diagonal direction from the flat end of the boiler to the cylindrical shell. One end of this plate is placed between and riveted to two angle irons which are riveted to the shell of the boiler. A similar arrangement connects the other end of the stay plate to the flat end of the boiler. In this example the stay or gusset plate is ¾ of an inch thick; the angle irons are 4 inches broad and ½ inch thick. The rivets are 1 inch in diameter. The same figure also illustrates the most common method of connecting the ends of a boiler to the shell. The end plates are flanged or bent over at right angles and riveted to the shell as shown. The radius of the inside curve at the angle of the flange is 1¼ inches. Draw this example to a scale of 3 inches to 1 foot. Fig. 7. Fig. 7. Fig. 8. Fig. 8. |
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