Pilots are used for the purpose of correcting the proper state of the material position before carrying out the press operation. The role of the pilot is to correct the material which is in such a state to a state in which the product accuracy can be satisfied.
BS 4185 is the series that discusses standards for machine tool components. BS 4185-14 is a part of the machine tool components series that describes a method for the determination of the pilot diameter of 60° centre holes.
BS 4185-14 provides a method for the determination of the pilot diameter, d, of a 60° centre hole, type A, B or R as illustrated in BS 328-2, covering the range 0.5 mm < d < 50 mm. This method applies only to workpieces satisfying the following conditions:
BS 4185-14 on the determination of the pilot diameter of machine is useful for:
The pilot diameter and the hole should not be of the same dimensions. This is because if they are the same, the pilot will pull up the material after piloting it to the correct position. If the number of pilots is made too large, due to the effect of the mold machining errors, etc., the material pulling up becomes frequency thereby causing problems.
BS 4185-14 is based on consideration of the stresses around the centre hole in a workpiece. The equation used to determine the maximum stress is that for the shear stress in a thick-walled pipe. Experimental work has shown that this is a good approximation to the case of a 60° centre hole at the end of a bar.
BS 4185-14 provides you with procedures for calculation of cutting force, calculation of the forces on the centre hole due to mass of workpiece, and calculation of the diameter of the centre hole pilot bore. Following BS 4185-14 specifications, help you to determine the pilot diameter of 60° centre holes of the machine.