DRAWING DIES.
Drawing dies are used for shaping or draw ing up sheet metal. The use of dies of this class is of comparatively recent origin; it having been first put into practical use by one De Vera of France in the latter part of the 18th century, and in the year 1827 the same process was pat ented for the drawing up of cartridge shells.
In 1860 or 1861, two Frenchmen came to this country, bringing with them draw ings of a model of a drawing press. These they had surreptitiously taken from a press upon which they had been employed in France. This press was secreted in a barn near the city of Wilmington, Del., and was finally perfected and put into actual use by Henry Marchand, who formed a company for the manufacture of the same, known as the Higgins & Marchand Co. The first press was set up in one corner of the shop which was boarded up, and only three men allowed in the room. The first piece drawn up was a washbasin made from a 14" blank, which was probably the first piece of drawn work ever made in America.
Drawing dies may be divided into three kinds: the plain drawing or °push through)) dies; solid bottom or °knock-out° where the work is to be knocked back; and combination dies which cut and draw at one stroke of the press. Combination dies are often so ar ranged as to perform three, four and some times more operations on the work at one stroke of the press. Dies of this nature are very expensive, and are only desirable when the work is to be done in large quantities.
Push Through Die.— Fig. 2 shows a plain °push through* drawing punch and die, the blank being punched out to fit the set edge, and then °drawn up)) or rather, it is pushed through the die by the punch, and as the punch rises, the work is stripped from the punch by the °pull off* which is made very sharp for the purpose. A •draw) of about one-quarter to one-half of a degree is given the die, making it that much larger on the upper side or face, and the upper edge is rounded over and left very smooth and as hard as fire and water will make it. °Don't
draw a drawing die.* The lower end of the punch is rounded and left in the same shape; often the die will work better if the finish is changed from a circular to a lateral polish. The diameter of the punch is equal to that of the die, minus double the thickness of the stock to be drawn. A die of this kind can only be used on shallow work, or in redrawing or reducing the diameter of the work that has been previously drawn up; if used on deep drawing it will pucker or crimp around the edge. To avoid this there must be a blank holder to hold the stock firmly while it is being drawn.
Action.— Fig. 3 shows a single-action cutting and drawing die, better known as a single-action combination die. A combination die is, as the name indicates, a combination of a drawing die and cutting die in one; it punches the blank, and at the same stroke of the press, draws it up into a cup or shell. The die shown is intended to be used in an ordinary single stroke power press, and will draw up work not over one or two inches deep.
Double Action.— A double-action die is a modification of a single-action die, to be used in a double-stroke press; it can be used on work that is too deep for single-action dies. The one shown in Fig. 4 is known as a °push through* die. It is somewhat like the single-action die, except that the shell is cut by the punch (B) and is carried to the drawing die (D) and the lower surface of the die acting as a blank-holder is held there while the drawing punch (A) forces it through the drawing die, and as the punch withdraws, the shell is removed by the lower edge of the die, which is ground very sharp for that purpose, and is known as the "pull off' The drawing die is held in place by the cutting die being damped upon it by the ring (G).
This style of die has this advantage; the cutting and drawing dies are independent of each other, and can be changed for a longer or shorter shell, or either die can be repaired or replaced without changing the other.