Method and arrangement for controlling the feeding of rods to a work tool in automatic screw machines and the like

In an arrangement for working rod-shaped articles, in combination, a cyclically operating work tool having a null position which it assumes at the beginning of its work cycle;

• an automatically operating rod-feeding unit for feeding rods to be worked into the range of operation of said tool and including pushing means for pushing a rod to be worked into the range of operation of said tool;
• selecting means for selecting a minimum and a maximum distance through which a rod to be fed by said unit towards said tool is to be permitted to advance per work cycle of said tool;
• means for determining the actual distance advanced by said rod during a work cycle of said tool;
• means for determining whether said actual distance falls within the range defined between said minimum and maximum distances;
• means for terminating operation of said rod-feeding unit when said actual distance falls outside said range;
• and means for terminating operation of said work tool upon a determination that said actual distance falls outside said range but only after said work tool has returned to said null position thereof.

A method of automatically monitoring and controlling the operation of a rod-working apparatus of the type including an automatically operating rod-feeding unit which longitudinally feeds a certain increment of a rod towards a cyclically operating work tool per work cycle of the work tool and which includes engaging means for engaging the rod and travelling longitudinally with the rod along the path of longitudinal movement of the rod towards the work tool, comprising the steps of selecting a minimum and a maximum distance through which a rod is to be longitudinally fed towards the tool is to be permitted to advance per work cycle of the tool;

• longitudinally feeding a rod towards and into the range of operation of the tool using said rod-feeding unit with said engaging means in engagement with said rod;
• determining the actual longitudinal distance advanced by said rod during a work cycle of said tool by determining the longitudinal distance traveled by said engaging means during a work cycle of said tool;
• determining whether said longitudinal distance traveled by said engaging means falls within the range defined between said minimum and maximum distances;
• terminating operation of said rod-feeding unit when said longitudinal distance traveled by said engaging means falls outside said range;
• said step of feeding a rod comprises feeding successive segments of said rod into the range of operation of the tool by moving said rod in discrete successive steps towards said tool using said rod-feeding unit with said engaging means in engagement with said rod, one step per work cycle of said tool, said tool being operative per work cycle for cutting off the segment of rod fed into the range of operation thereof during such work cycle;
• said step of terminating operation comprises terminating operation of said rod-feeding unit before all of the segments of the rod being fed have entered into the range of operation of said work tool;
• subsequently effecting a resumption of the feeding by said rod-feeding unit of the incompletely fed rod;
• said cyclically operating work tool having a null position which it assumes at the beginning of each of its work cycles;
• and further comprising the step of terminating operation of said work tool upon a determination that said actual distance falls outside said range but only when said work tool has been allowed to return to said null position thereof.