Spot Welds
22 сентября, 2014 
Oleg Maloletnikov |
OTHER SIDE IE —©---------------- <(R! |
A spot weld is made between or on overlapping members of a joint. In cross section, the spot weld appears to be circular. The symbol for a spot weld is О. This symbol is similar to the weld-all-around symbol except that it is centered on the reference line. (Note that the weld-all-around symbol is placed at the break in the reference line, .)
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ARROW SIDE |
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^RSW NO ARROW SIDE OR OTHER SIDE SIGNIFICANCE FIGURE 18.1 ■ Location of spot-weld symbol. |
The spot-weld symbol is located tangent to the reference line (circumference of symbol touches line) when it has an arrow side or other side significance. It is centered on the reference line when there is no arrow side or other side significance, Figure 18.1.
When the spot weld is used, the tail must always be included. The welding process reference required as one of the elements of the symbol is placed in the tail. (See Unit 10 for the meanings of the abbreviations for the various welding processes.)
DIMENSIONING THE SPOT-WELD SYMBOL
Dimensions applied to the spot-weld symbol are shown on the same side of the reference line as the symbol, or on either side when there is no arrow side or other side significance for the symbol, Figure 18.2. Dimensions typically used with this symbol include the size or strength, spacing, extent, and the number of spot welds.
The size of a spot weld is shown to the left of the weld symbol. This dimension represents the diameter of the weld at the faying (joining) surfaces in fractions of an inch or in decimal fractions, with or without inch marks,
Figure 18.2 and Figure 18.3. Note that the size dimensions are given in millimeters when the drawing is dimensioned in metric.
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FIGURE 18.4 ■ Application of shear strength dimension to the spot-weld symbol. |
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Л- |
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Л- |
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FIGURE 18.7 ■ Extent of spot welding. |
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SYMBOL SIGNIFICANCE |
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If the strength of the weld is to be given rather than its size, the value is placed to the left of the spot-weld symbol. An explanation of the meaning of this value appears as a note on the drawing, Figure 18.4. Either the size of the spot weld or the shear strength is specified on the welding symbol, but not both. The shear strength may be expressed in pounds or Newtons per spot. Newtons are used when the drawing dimensions are in metric. The letter “N” is added to the strength dimension to indicate Newtons, Figure 18.6. The spacing of spot welds is indicated by a number placed to the right of the weld symbol. This number is called the pitch and refers to the center-to-center distance between the spot welds, Figure 18.5 and Figure 18.6. When the spot welding extends the full distance between decided changes in the direction of welding, or the full length of the joint, no dimension is given for the extent of welding. When the extent of welding is less than the full length of the joint or the full distance for one direction of welding, the extent dimension is shown directly on the drawing, Figure 18.7. The number of spot welds in a joint is indicated on the symbol in parentheses. The number is placed below the weld symbol when it has an arrow side significance. It is placed above the symbol when it has an other side significance, Figure 18.8. When the symbol is located astride (centered on) the reference line, the dimension can be placed on either side of the reference line, Figure 18.8. When a pattern for the application of the spot welds is not specified, the welding symbol and elements are drawn as in Figure 18.9(a). When a group of spot welds may be conveniently located by dimensioning intersecting center lines on a drawing, they are shown as illustrated in Figure 18.9(b). Note that multiple arrows are used, and that they touch the centerlines that show the weld locations. The dimension for the center-to-center spacing (pitch) of spot welds is shown to the right of the weld symbol, Figure 18.10. When the symbol is centered on the reference line, the dimension can be placed on either side of the reference line. The use of combined dimensions is shown in Figure 18.11. |
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FIGURE 18.6 ■ Application and interpretation of spacing (pitch) dimension. |
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SHEAR STRENGTH OF 1000 NEWTONS IS REQUIRED PER SPOT SIGNIFICANCE |
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-2"—H 1" 4r |
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L |
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FIGURE 18.8 ■ Number of spot welds. |
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RSW A |
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0.10" (SIZE OF j SPOT WELD) |
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SIGNIFICANCE |
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0.10’A / гОлп |
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1-4 |
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SYMBOL |
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(a) |
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FIGURE 18.9 ■ Spot welds (a) located at random and (b) located by dimensioning. |
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FOUR SPOT WELDS LOCATED WITHIN CIRCUMSCRIBED AREA |
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RSW |
-v
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SYMBOL |
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FIGURE 18.1 1 ■ Spot-welding symbol showing the і FIGURE 18.10 ■ Indicating pitch with the spot-weld symbol. of combined dimensions. |
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SPOT WELD) |
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1" 2 ”* 1" PITCH- 5 SPOT■ WELDS |
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SECTION A-A |
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SIGNIFICANCE |
-.25" (SIZE OF
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