Equipment used in drawing

EQUIPMENT USED IN DRAWING

The equipment for drawing is basically of two types.

1. Draw bench 

2. Bull block.

1. Draw Bench

The draw bench is shown in Figure 3.61 in page 3.68. A draw bench is used to pull the tube or rod through a drawing die. Draw benches are used for single length drawing of straight rods and tubes. One end of the tube or rod to be drawn is collapsed and fed through the die. This end is then clamped to a travelling carriage. The carriage is then moved away from the die using either mechanical or hydraulic traction.

A cold-draw bench for tubes or rods consists of a heavy steel frame or bench, at the middle in which it is located in a die head for holding the die. At one end of the bench, an adjustable holder is located to anchor the mandrel rod. At its other end, a shaft is mounted carrying a sprocket wheel over which passes a heavy, endless and square-linked chain. This chain lies in a holder at the top of the bench. It extends from the sprocket wheel to the die head where the chain passes around an idler and it returns underneath the bench to the sprocket wheel. The sprocket wheel is driven by a variable speed motor through a suitable reduction gearing.

2. Bull Block

It is used to make very long rod and wires in smaller cross-sections, usually less than 13mm. The tension in this setup provides the force required for drawing the wire. It is shown in Figure 3.69.