Metal deforming – By use of closed-die and coacting work-forcer – Forcing work into or within closed die; e.g. – forging
Patent
1994-09-12
1997-04-15
Larson, Lowell A.
Metal deforming
By use of closed-die and coacting work-forcer
Forcing work into or within closed die; e.g., forging
72351, 72361, B21D 2200, B21D 2221
Patent
active
056198825
DESCRIPTION:
BRIEF SUMMARY
FIELD AND BACKGROUND OF THE INVENTION
The present invention relates to a process and a device for producing Phillips-head screwing tools or the like, especially in the form of bits, by cold forming from a workpiece section cut to length from a profiled rod.
It is known to produce bits by starting from a profiled rod of hexagonal cross section which is cut to the length of the bits. The workpiece section is turned on a lathe producing a hexagon and a cylindrical section with spherical end. The part produced in this manner is then formed on its headed front end by the cheek plates of a press tool to a Phillips-head shape or the like. Since the workpiece section is subjected to an increase in length in this process, there is the problem of a bending of the workpiece section which is clamped during the forming, resulting in an increased number of rejects.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a process and a device for carrying out the process in order to produce bits of high precision in a manner simple to manufacture without the disadvantage of the bending of the workpiece section in the press tool.
The object of the invention is achieved in the manner that the workpiece section, which is shaped at one end with a hexagon profile and, adjoining it, cylindrically with a supportable front end, is introduced, with axial spring-loaded support, into a press tool, whereupon the cheek plates of this press tool effect the forming into the Phillips-head profile or the like by displacement towards the center, which is controlled by a conical envelope surface which tapers towards the front end.
As a result of this development there is provided a process of this type by means of which Phillips-head screwing tools or the like, developed in the form of bits, can be produced with great precision. The problem of the workpiece section bending upon the forming is eliminated. This is achieved by the axial spring-loaded supporting of the workpiece section in the press tool. If, now, the Phillips-head profile or the like is produced by forming on the workpiece section by the displacement towards the center of the cheek plates of the press tool, the increase in length which takes place in this connection is compensated for by the spring-loaded support, without the increase in length leading to a bending, in particular, of the cylindrical section of the workpiece section. This means that the force of the spring-loaded supporting is so selected that the forces for bending are greater than the forces of the spring-loaded support. Furthermore, the tapered conical envelope surface assures a synchronous displacement of the cheek plates, together with a high precision of shaping. Another process step consists therein that the workpiece section which has been cut to length from a round rod profile is upset at one end to form a hexagon. All process steps, aside from the cutting to length, can be carried out by cold forming. The starting material for this is a round rod profile of corresponding quality. After the cutting to length of the workpiece section, it is imparted a hexagon by upsetting at one end. In order that suitable working ends are always present on the screwing tool produced by the process of the invention, a conical heading of the end of the workpiece section is effected before its introduction into the free space between the cheek plates. The front end produced by the cutting to length is therefore subjected to a separate machining prior to the shaping. In this way, a drive tip which always free of notch effect is created on the screwing tool. Without this machining process, the shear plane would otherwise lie in the region of the take-off. The formation by upsetting of the hexagon is advantageously effected in a multi-step press, in the manner that, first of all, approximately half the length is flow-pressed to a smaller cross section, whereupon the other part of the length which is of larger cross section is shaped, possibly in a press intermediate step, into a hexagonal section of
REFERENCES:
patent: 1977164 (1934-10-01), Wilcox
patent: 2656739 (1953-10-01), Mansfield
patent: 3103833 (1963-09-01), Lejdegard
patent: 3124876 (1964-03-01), Putetti
patent: 3566664 (1971-03-01), Schweizer
patent: 4463587 (1984-08-01), Werner
Butler Rodney A.
Farber Martin A.
Larson Lowell A.
Wera Werk Hermann Werner GmbH & Co.
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