High speed coil-forming headstock

Abstract: High speed coil-forming headstock which works at speeds up to and over 150/180 metres a second and comprises a stator (11) and a rotor (12), a planetary ring (16) being included at the position of greatest reciprocal diameter of the stator (11) and rotor (12) and comprising at least one first bearing (14) towards the rotor (12) and at least one second bearing (15) towards the stator (11), the planetary ring (16) being able to idle and having a limited lengthwise extent and bearing a plurality of pinions (19) arranged in a ring with their axis parallel to the axis of the rotor (12), the pinions (19) meshing with peripheral inner (17) and outer (18) teeth included on the stator (11) and rotor (12) respectively.

Description: This invention concerns a coil-forming headstock able to form coils at high speed. To be more exact, the invention concerns a coil-forming headstock capable of being positioned at the end of a rolling line producing wire rod at a high speed, the coil-forming headstock being located upstream of a line to cool coils of wire rod. The invention concerns a coil-forming headstock able to process up to and more than 150/180 metres of rolled rod per second. A coil-forming headstock suitable to process at this speed is KNOWN FROM US-A-4 765 556. OTHER known coil-forming headstocks work up to 100/120 metres a second and are prevented from exceeding this speed owing to the inherent limitations of the bearings and to the masses which would otherwise come into play. It is known that bearings of a given size withstand a well determined difference in speed between their inner and outer races, and this difference in speed cannot be exceeded except for very short times without damage to the bearings themselves. The disclosure of US 4,765,556 provides for a first hollow shaft and a second hollow shaft, these shafts being coaxial and concentric. Both these hollow shafts get their motion from one single motor which actuates a pair of coaxial gear wheels. This disclosure entails many drawbacks. This system is very costly as it requires a great number of auxiliary bearings; it is also very noisy as it includes a high-speed transmission with gear wheels; but above all it entails inherent limitations due to the great masses set in rotation, the masses consisting of the gear wheels and hollow shafts. These masses not only require great power but entail considerable inertia during start-up and stopping; they also require complex articulated structures for support purposes. Moreover, the result is a complex lay-out which involves heavy maintenance costs and long maintenance times. Furthermore, the outer hollow shaft can only cover a part of the inner hollow shaft and thus leaves an important part of the inner shaft supported as a cantilever, thereby entailing problems of vibrations, anomalous stresses and misaligned rotary pressures. The present invention therefore tends to overcome the limitations imposed by the state of the art. The invention provides the advantages of entailing smaller masses, a simple design easy to assemble and dismantle and lesser bearing structure requirements. The use of a rotor solidly connected directly to the rotor of the motor makes the design and finished product very clean and simple. The high speed coil-forming headstock according to the invention is set forth and characterized in the main claim. A coil-forming headstock normally comprises a stator and a rotor holding the guide for the rolled stock. According to the invention a planetary ring is positioned between the stator and the rotor at their reciprocal position of greatest diameter and has simple support functions. According to the invention the planetary ring is set in rotation by a plurality of pinions supported by the planetary ring itself and cooperating directly with the rotor and stator. The planetary ring is made to rotate at a pre-set speed, so that the bearings located between the planetary ring and the stator and rotor respectively have an acceptable speed differential. In fact, in this way the difference in speed between the inner and outer races of the bearings is substantially halved. According to a preferred variant the rotor is keyed directly to the rotor of the electric motor. The single attached drawing, which is given as a non-restrictive example, shows a partial section of a coil-forming headstock according to the invention. In the attached figure a coil-forming headstock 10 comprises a motor 20 which, in cooperation with a stator 11 and a rotor 12, brings the rotor 12 to the required speed of rotation. The motor 20 has its rotor solidly fixed to the rotor 12 of the coil-forming headstock 10. A planetary ring 16 conformed as a toric ring having a very limited length is included between the stator 11 and the rotor 12 at the position of the greatest substantial diameter. The planetary ring 16 is positioned at and cooperates with the zone of installation of bearings of the greatest diameter, that is to say, it cooperates with the zone downstream of the motor 20 where a guide 13 for the rolled stock enlarges its position. The planetary ring 16 comprises between itself and the rotor 12 first bearings 14 and between itself and the stator 11 one or more second bearings 15. Peripherally arranged outer teeth 18 are comprised on the rotor 12 and peripherally arranged inner teeth 17 are comprised on the stator 11. Pinions 19 are fitted so as to idle rotatably on the planetary ring 16 and mesh with the outer teeth 18 of the rotor and with the inner teeth 17 of the stator. In this way the planetary ring 16 rotates at a desired number of revolutions intermediate between the number, substantially nil, of revolutions of the stator 11 and the number of revolutions required by the rotor 12. Thus there will be different speeds of rotation of the stationary race and rotary race of the second bearings 15, and the difference will be much less than if the rotary race were connected directly to the rotor 12. The same applies to the first bearings 14, in which the difference in rotation speed between inner and outer races is very different from what it would be if the outer races were connected to the stator 11. In this way the difference between the speed of the inner race and that of the outer race in the bearings is therefore very small and is normally acceptable for the bearings and capable of being withstood for a very long time without any yielding or deformations. According to the invention the planetary ring 16 has small dimensions and therefore the overall bulk of the coil-forming headstock is not affected thereby. The first and second bearings 14-15 are included in a small number, advantageously but not only three (two first bearings 14 plus one second bearing 15), and have small dimensions.

Claims: A high-speed coil-forming headstock (10) comprising at its downstream end a rotary support between a rotor (12) and a stator (11), the rotary support comprising an intermediate ring (16), at least one first bearing (15) positioned between the intermediate ring (16) and the stator (11) and at least one second bearing (14) positioned between the intermediate ring (16) and the rotor (12), the intermediate ring (16) rotating in a fixed ratio to the speed of the rotor (12), characterised in that the intermediate ring (16) bears a plurality of pinions (19) which mesh with inner teeth (17) of the stator (11) and with outer teeth (18) of the rotor (12), the rotor (12) being solidly fixed to the rotor of an electric motor (20) and the stator of the motor (20) being connected to the stator (11), the axial dimension of the intermediate ring (16) being limited to the length required to accommodate for the first and second bearings (14,15) as well as the pinions (19).

Inventors: POLONI ALFREDO, POLONI, ALFREDO
Applicants: DANIELI OFF MECC, DANIELI & C. OFFICINE MECCANICHE S.P.A.
Application year: 1990
Main classification: B21C47
IPC codes: B21C47