140. Double and Single Offsets.—[Fig. 126]. The following exercises are given to explain the use of simple appliances for producing work accurately and rapidly. Examples similar to the four following ones would require considerable care and skill if they were to be produced without the use of the steam hammer.
At a is shown a double offset bend, the depth of which, for illustration, may be 1⁄2 inch. To produce this, place two pieces of 1⁄2-inch flat material, with width corresponding to that of the material to be bent, on the lower die, and sufficiently far apart to allow the offsets to form between them. On these the material is placed, and on top of that also, located midway between the 1⁄2-inch supporting pieces, a third piece of 1⁄2-inch stock is placed. The width of this should correspond with the required dimension at a and should be somewhat longer than the width of the material to be bent. This arrangement is shown at c. By delivering a sufficiently heavy blow upon them, the two offsets, will be formed simultaneously and accurately.
Fig. 127.—Simple Methods for Bending Clamps with a Steam Hammer.
In all operations of this kind the thickness of the lower forming pieces should always correspond with the required depth of the offset, and the corners should be ground round to prevent shearing or galling.
At d is shown a single offset which can be produced in a similar way, with the exception that here only two blocks are required. But the forming corners of these should also be ground as previously stated, and they are placed in position as shown at e.
Figure [127] shows the method of bending a semicircular pipe or rod clamp. Here a piece of round stock f is used above for stamping, but as the lower blocks are easily displaced, it would be advisable to make a stamping block like that shown at g. This could be used instead of the two lower pieces. If the clamps were to be made square, then the stamping block should be like the one shown at h, and the upper piece as at f should be made square.
Questions for Review
What is a forging? Name the machines used in making forgings. Who invented the steam hammer? How should material be held on the dies? What tool is used in place of a hot cutter at the hammer? How can a convex end be produced? Describe the special form of a trimming chisel. How should metal be broken after it has been nicked with the cold cutter? Describe the correct way of using a hack in cutting square stock. Explain the use of a checking tool. Describe the different fullers used at the hammer. Explain their uses. For what is a combination fuller and set used? Describe the hammer swages. The bevel or taper tool. What is it used for? What is the advantage in the use of the V block? Describe the yoke. Explain its use. What is the difference between a plug punch and a handle punch? How is a bolster used for punching? What does the word “finished” mean on a drawing? What hammer tools are brought into use in making a crank shaft? In making the connecting rod? Describe how the hammer is used in bending a rod strap. What tools are brought into use in making the eccentric jaw? Describe the method of forming the bosses on the hand lever. Explain some simple methods of bending work with the steam hammer.