Metal deforming – By pulling workpiece through closed periphery die – Utilizing plural metal-deforming tools
Patent
1998-06-03
2000-06-27
Crane, Daniel C.
Metal deforming
By pulling workpiece through closed periphery die
Utilizing plural metal-deforming tools
72287, 72291, B21C 124
Patent
active
060792485
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a process for drawing, for example, metal bars or tubes. The invention also relates to a machine for the application of the said process.
Conventional drawing machines have a main structure including: head provided with a draw plate, and, before the drawing bench with respect to the direction of advance of the workpiece, or tubes; drawing with a mandrel, and, after the drawing bench,
On the drawing bench, after the drawing head, a carriage is disposed slidably on longitudinal guides and is provided with clamp means to grip one end of a piece to be drawn, while it draws it through a corresponding draw plate, in each working stroke, to carry out the drawing operation.
The drawing carriage is made to execute its working stroke along the corresponding guides from an area in the proximity of the drawing head, by means of a chain (or similar means) continuously driven by motor means. The drawing carriage is temporarily coupled to the chain during the working stroke and is uncoupled from it at the end of the drawing operation.
At the end of the working stroke, in other words when the drawn piece has completely left the draw plate on completion of the drawing, the carriage, which is in an area remote from the drawing head, is stopped. It is then returned to the proximity of the drawing head, executing an idle return stroke, to grip with its clamp an end of another piece (bar or tube) to be drawn.
As will be clear from the above description, in each drawing cycle, one productive working stroke of the carriage is associated with a non-productive return stroke of the carriage. The cycle time for this drawing process is evidently unfavourable for mass production.
To increase the output for a given drawing cycle time, drawing machines known as "double or triple drawing machines" have been produced, with drawing heads having two or three draw plates each.
Consequently, two or three mandrels and the corresponding mandrel support means (for tube drawing) are provided, while the carriage is provided with two or three gripping clamps and the accessory and auxiliary devices of the machine are designed accordingly.
Although these "multiple draw" machines do in fact enable output to be increased, they do not resolve the problem of the idle times due to the non-productive return stroke of the carriage in each drawing cycle. Moreover, the mechanical means for driving the carriage translationally (for example, chain means), from which the carriage is uncoupled at the end of each operating stroke, has the disadvantage of a considerable noise level, often at the limits permitted by the current regulations in respect of noise in the workplace.
Indeed, the chain (or similar means) which is slightly raised from its travelling path by the driving hook connected to the carriage during the operating stroke, falls on to its travelling travelling path when the carriage is uncoupled, producing a loud mechanical noise.
Furthermore, the chain (or similar means) for driving the carriage translationally is kept constantly in motion, although it works only when the carriage is coupled to it. Its considerable weight and the consequent friction when it is idle therefore cause a considerable expenditure of energy, not used for work. However, it is impracticable to stop the.motion of the chain (or similar means) during the idle times, owing to the long stoppages required.
It should also be noted that the retooling of any known drawing machine, to change to the drawing of pieces having different dimensions and/or shapes, entails thie stopping of the machine to enable the equipment to be changed.
DE-A-30 10 942 and Be-A-372 968 seek to solve the technical problem of having, in each draw cycle, an unproductive return stroke of the carriage for each productive working stroke of the carriage, because the cycle time associated with such a drawing method is unfavorable for mass production.
The solution proposed in DE-A-30 10 942 and BE-A-372 968 is to provide a drawing method and machine in which at least two drawing carria
REFERENCES:
patent: 1984756 (1934-12-01), Offutt
patent: 3257833 (1966-06-01), Good
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