EP0779115A1

EP0779115A1 - Coil-forming head for rolling plants

Info

Publication number: EP0779115A1
Application number: EP96118899A
Authority: EP
Inventors: Gianni Nonino; Attilio Sacchi; Ferruccio Tomat
Original assignee: Danieli and C Officine Meccaniche SpA
Current assignee: Danieli and C Officine Meccaniche SpA
Priority date: 1995-12-04
Filing date: 1996-11-25
Publication date: 1997-06-18
Also published as: ITUD950238A0; IT1281459B1; ITUD950238A1

Abstract

Coil-forming head for rolling plants to produce coils (21) starting from continuous and substantially straight products (16) such as round rods, wire rods or other products arriving from a rolling mill or from another analogous source, the head being of a type comprising a rotary mandrel (11) supported by bearings and driven by a suitable motor, within which head is introduced axially a product (16) which is conveyed and partly curved in coils by an appropriate delivery channel, the head comprising a bell element (13) cooperating axially with the rotary mandrel (11) and solidly joined in prolongation of the rotary mandrel (11), at least one delivery channel (22) being included within the bell element (13) and cooperating with the inner part of the bell element (13) which can be positioned at an angle to the rotary mandrel (11), the delivery channel (22) being lined internally with wear-resistant material.

Description

This invention concerns a coil-forming head for rolling plants, as set forth in the main claim.
The coil-forming head according to the invention is applied to machines which form coils from continuous and substantially straight semi-finished products arriving from a rolling mill or from another analogous source, the products being for instance round rods, wire rods or other products.
Coil-forming machines of the state of the art comprise a rotary coil-forming head cooperating axially with the round rod or wire rod arriving from the rolling process; the coil-forming head comprises a mandrel supported on bearings and set in rotation by a motor.
The rotary mandrel cooperates axially with a tube delivering the rolled product or other product, that tube being conformed with a coil at its end.
Two or more tubes can be included advantageously and be positioned symmetrically so as to balance the centrifugal forces arising from the high speed of rotation of the coil-forming head.
The rolled product during rotation of the coil-forming head is curved by the delivery tube so as to form a succession of coils having a determined pitch and diameter, which are normally deposited by falling onto a roller conveyor belt so as to be cooled and delivered to the subsequent processing steps.
According to the state of the art the delivery tube and the possible balancing tube are fixed as cantilevers by means of suitable fixture collars or by other suitable means to the outside of a longitudinal structure solidly fixed axially to the rotary mandrel.
Since the present technologies enables speed of rotation to be reached which at one time were not possible, it has been found that the high speed of rotation of the coil-forming head causes considerable centrifugal stresses on the tubes, and these stresses tend to break the fixture collars and to deform the tubes.
These centrifugal stresses not only entail frequent downtimes for repair of the coil-forming head but prevent the ability of increasing the speed of rotation still further.
Document DE-A-3.002.026 discloses a plurality of solutions including one, shown in Fig.10, which has a single bell type element associated with an insert whose outer periphery mates with the inner profile of the bell, and the periphery of the insert has a hollow where the channel through which the rolled product passes is inserted.
This solution may solve one problem but it also creates a plurality of other problems.
First of all there is the problem of the considerable masses in rotation, then there is the problem of regulating the reciprocal position of the bell with respect to the entrance channel, then there is the problem of mating the channel which cooperates with the bell with the hollow which cooperates with the insert.
Further, there is the problem of the wear of the channel, and finally there is the problem of balance.
The present applicants have designed, tested and embodied the following invention to overcome this shortcoming, which particularly affects operators in this field, and to achieve further advantages.
This invention is set forth and characterised in the main claim, while the dependent claims describe variants of the idea of the main embodiment.
The purpose of this invention is to provide a coil-forming head which is able to work at very high speeds without suffering from the problems of the yielding or loosening of the means which fix the tube delivering the rolled product, and without causing deformation of the tubes themselves.
The coil-forming head embodied according to the invention comprises a bell element having advantageously a truncated-cone form and associated axially with the rotary mandrel; the inner surface of the bell element cooperates with the tube or tubes fixed thereto with suitable fixture means.
The inclusion of a plurality of tubes meets the problems of balance and also the problems of quick replacement of tubes worn out with use.
The centrifugal force which stresses the tubes radially outwards is thus opposed by the bell element through the presence of a surface of contact between the tube and the bell element.
Moreover, the bell element ensures greater rigidity and better balancing of the rotating masses.
The bell element can be embodied advantageously by using light materials having a high mechanical strength, such as light alloys or composite materials, for instance, which owing to their properties make possible an increase of the speed of rotation and therefore the attainment of very high speeds of feed of the rolled product, such speeds not being possible where conventional materials are employed.
According to another embodiment of the invention the coil-forming head comprises a hollow truncated-cone insert ring associated axially with the inside of the bell element and cooperating with the inner surface of the same.
To be more exact, at least the last segment of the channel delivering the rolled product is defined by a groove machined on the outer surface of the hollow insert ring, which has its outer side closed by the inner surface of the bell element.
This embodiment achieves a better distribution of the stresses due to the centrifugal action and a stable and defined positioning of the means guiding the rolled product.
According to a preferred embodiment of the invention a second groove is provided in a position axially symmetrical with the delivery hollow and has the function of compensating the centrifugal forces and can be used as an alternative to the first hollow when the latter becomes worn.
According to another variant of the invention three or more delivery grooves are machined in the hollow insert and are arranged in positions symmetrical with each other so as to compensate the centrifugal forces.
These grooves may have the same section of their passage or may have different sections, two by two for instance, of their passage so as to process rolled products of different cross-sections.
These grooves can be used alternately for the feed of the rolled product so as thus to prolong the working life of the coil-forming head.
According to another variant these grooves are lined with a wear-resistant material of a ceramic type, for instance, so as to protect the delivery grooves against the wear caused by the high temperature and by the scraping of the rolled product.
The attached figures are given as a non-restrictive example and show some preferred embodiments of the invention as follows:-

Fig.1: shows a longitudinal section of a first form of embodiment of the coil-forming head according to the invention;
Fig.2: shows a cross-section of the coil-forming head of Fig.1 along the line A-A;
Fig.3: shows a longitudinal section of a second form of embodiment of the coil-forming head according to the invention;
Fig.4: shows a cross-section of the coil-forming head of Fig.3 along the line B-B.

The reference number 10 in the attached figures denotes generally a coil-forming head embodied according to the invention to produce coils 21.
In this case, the coil-forming head 10 comprises a rotary mandrel 11 supported by bearings 12 of any type and driven by a motor, which is not shown here.
The rotary mandrel 11 is associated axially with a bell element 13 by means of flanges 14 so that the bell element 13 can be detached so as to be repositioned at an angle or to be replaced.
A delivery channel 22 is positioned within the rotary mandrel 11 and within the bell element 13 and is defined in this case by a delivery tube 15b conformed with a spiral at its end and cooperating with the rolled product 16.
A second tube 15a is positioned advantageously within the bell element 13 at a position diametrically opposite to the first delivery tube 15b and has the task of balancing the great stresses due to the centrifugal force which the coil-forming head 10 undergoes during working.
According to a variant of the invention this second tube 15a can perform also the tasks of a spare tube to deliver the rolled product 16 after rotating the bell element 13 by 180° in relation the rotary mandrel 11.
In this case, which is not shown, the segments of the delivery tubes 15a, 15b within the containing bell element 13 can be detached from the relative segments of the tubes within the mandrel 11.
In this case, the tubes 15a, 15b are associated substantially by contact with the inner surface of the bell element 13 and are fixed to that element 13 by means of clamping collars 17.
The stresses arising from the centrifugal forces are substantially discharged onto the zone of contact between the tubes 15a, 15b and the inner surface of the bell element 13, so that the clamping collars 17 perform substantially the task of positioning the tubes 15a, 15b and are very little stressed during the working of the coil-forming head 10.
According to a variant of the invention shown in Figs.3 and 4 a hollow insert 18 of a form mating with the bell element 13 is inserted into the bell element 13 and is clamped there by suitable fixture elements 20 or by other means.
The hollow insert 18 contains in its outer surface at least one delivery groove 19b, which is formed substantially as a spiral and defines the delivery channel 22.
This delivery groove 19b is placed in prolongation of the first segment of delivery tube 15b associated with the rotary mandrel 11 and acts as an element to convey and guide the rolled product 16 within the coil-forming head 10.
This embodiment enables the stresses arising from the centrifugal force to be further reduced and ensures a prolonged and efficient use of the coil-forming head 10.
In the preferred embodiment shown in Fig.3 there are four delivery grooves machined symmetrically in the hollow insert 18, only the grooves 19a, 19b being at least partly visible.
This embodiment enables a better balancing of the masses to be obtained during rotation of the coil-forming head 10.
Moreover, this embodiment enables the working life of the coil-forming head 10 to be lengthened since it is possible to use the four delivery grooves alternately to convey and guide the rolled product 16.
According to further variants two, three, five or more delivery grooves 19 may be included and be symmetrically distributed in the periphery of the hollow insert 18.
Fig.4 shows all the four delivery grooves 19a, 19b, 19c, 19d.
The bell element 13 and the hollow insert 18 are made advantageously of light materials such as light alloys or composite materials which enable very high speeds of rotation to be achieved.
The delivery grooves 19 are advantageously lined with a wear-resistant material, such as a ceramic material or another, so as to prolong their working life.

Claims

Coil-forming head for rolling plants to produce coils (21) starting from continuous and substantially straight products (16) such as round rods, wire rods or other products arriving from a rolling mill or from another analogous source, the head being of a type comprising a rotary mandrel (11) supported by bearings and driven by a suitable motor, within which head is introduced axially a product (16) which is conveyed and partly curved in coils by an appropriate delivery channel, the head being characterised in that it comprises a bell element (13) cooperating axially with the rotary mandrel (11) and solidly joined in prolongation of the rotary mandrel (11), at least one delivery channel (22) being included within the bell element (13), and cooperating with the inner part of the bell element (13) which can be positioned at an angle to the rotary mandrel (11), the delivery channel (22) being lined internally with wear-resistant material.
Coil-forming head as in Claim 1, in which the delivery channel (22) positioned within the bell element (13) consists of a first delivery tube (15b) secured to the inner sidewall of the bell element (13) by clamping collars (17).
Coil-forming head as in any claim hereinbefore, in which a second tube (15a) having the function of balancing the masses is included in a position symmetrical to the first delivery tube (15b).
Coil-forming head as in Claim 3, in which the second tube (15a) and the first tube (15b) perform alternately the task of delivering the product (16) in the coil-forming head (10).
Coil-forming head as in Claim 1, in which the delivery channel (22) positioned within the bell element (13) consists of a delivery groove (19b) machined in the outer surface of a hollow insert (18) having a form mating with the bell element (13), the hollow insert (18) being clamped coaxially within the bell element (13) in contact with the inner surface thereof (13).
Coil-forming head as in Claim 5, in which at least two delivery grooves (19a, 19b) positioned symmetrically in the outer surface of the hollow insert (18) are included.
Coil-forming head as in Claim 5 or 6, in which the hollow insert (18) is made of a light alloy.
Coil-forming head as in Claim 5 or 6, in which the hollow insert (18) is made of a composite material.
Coil-forming head as in any of Claims 5 to 8 inclusive, in which the delivery grooves (19) are lined internally with a wear-resistant material.
Coil-forming head as in any claim hereinbefore, in which the bell element (13) is made of a light alloy.
Coil-forming head as in any of Claims 1 to 9 inclusive, in which the bell element (13) is made of a composite material.