Decelerator apparatus for hot rolled product

Decelerator apparatus acting to reduce the distance over which lengths of hot rolled product slide before coming to a halt on leaving a rolling mill stand. So as to avoid the use of pinch rolls or the like, the apparatus employs deforming rollers acting on a leading length of said rolled product in a direction perpendicular to its length and a shear for severing the leading length of product from a following length being acted on by said rolling mill stand whilst said rollers are still in motion.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The invention relates to decelerator apparatus for hot rolled product being 
produced in a rolling mill. 
2. Description of the Prior Art 
Rolled product generally leaves the finishing stand of a rolling mill at a 
speed roughly inversely proportional to its cross sectional area so as to 
maintain as near as possible a constant rolling rate in terms of tonnage 
of finished product produced. 
When rolled product is delivered in straight lengths from the finishing 
stand it is cut into the lengths required and these then have to be 
brought to rest before being transferred sideways across a cooling bed. 
However, it will be understood that the smaller the cross sectional area 
of the rolled product, the greater is the rolling speed and consequently 
the greater is the stopping distance required before the lengths of 
product can be moved sideways onto the cooling bed. There is obviously a 
practical limit to the distance over which the lengths of product can be 
allowed to decelerate and the time this takes which has to be within the 
cycle time of products being delivered from the mill less time for the bed 
to clear the first notch of the cooling bed. The result is that in many of 
the higher production rolling mills it is found that the rolling rate in 
terms of tonnage produced per hour drops substantially when product of 
relatively small cross sectional area is being produced purely because of 
the high output speed of the product from the finishing stand. 
Various attempts have been made to solve this problem. For example, 
so-called double lifting aprons associated with walking beam type cooling 
beds have been used, and have reduced the sliding time of the lengths of 
product on the take off apron immediately following the finishing stand 
and also before the first rake. In other words, the total sliding time of 
a length of rolled product has been shared between the two systems, but in 
fact the overall sliding distance has not been affected to any significant 
extent. A more positive action not limited by the frictional force which 
can be generated by the weight of the product on a supporting surface has 
been used, this involving the provision of so-called pinch rolls between 
which the lengths of product after having been sheared to length are 
trapped near to their back ends and, by virtue of the relatively slow 
running of said pinch rolls, decelerated fairly quickly. However, this has 
various drawbacks. For example, it is not easy to provide variable 
controlled deceleration when using pinch rolls because they depend 
ultimately on indeterminate frictional contact if deformation of the 
rolled product is to be minimised. Furthermore, the longer the length of 
rolled product and the greater its weight. Consequently, the greater is 
the required pressure applied to the surfaces of the product by the pinch 
rolls. The result is that some marking of the product is always likely to 
occur and in some cases the trailing end of a length of product can be 
deformed. In fact the hot rolled product can be pulled in two or severely 
necked. For this reason the use of pinch rolls is usually limited to the 
production of relatively short lengths of rolled product of round cross 
section or a cross section of some other simple shape. 
A further braking device which has been used for the braking of lengths of 
wire which have been produced in a wire rolling mill has included a number 
of tiltable braking elements equipped with rollers, the device also 
including mechanism for tilting the tiltable braking elements by a 
variable amount. Such a device has been used to brake the lengths of wire, 
after they have been sheared to length, the braking effect being produced 
solely by the flexing of the wire as it passes through the device. In 
other words, the braking effect has been due to the deformation of the 
wire and by the physical work which has been put into the material by such 
deformation. For this reason, the amount of braking which can thereby be 
brought about by such a device on hot rolled lengths of material of 
relatively small cross sectional area is very small indeed and is very 
largely indeterminate. 
SUMMARY OF THE INVENTION 
The invention as claimed is intended to provide a remedy. It solves the 
problem of how to decelerate lengths of hot rolled product in a most 
convenient and highly determinate manner. 
The advantages offered by the invention are, mainly, that it provides a 
method of and means for decelerating lengths of hot rolled product which 
greatly reduces the sliding time of the lenghts of product without the use 
of pinch rolls or the like which could damage the lengths of rolled 
product. The invention in addition enables the rolling rate in terms of 
tonnage produced per hour to be much higher than that which has been 
possible when using conventional decelerator apparatus.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT 
Referring now to FIG. 1 of the drawings, the decelerator apparatus there 
illustated is located on the output side of a finishing stand S of a 
rolling mill producing hot rolled product of relatively small cross 
sectional area. The apparatus includes switching means, generally 
indicated 10, for switching successive lengths of product into alternate 
tracks 12 and 14 for guiding the product as it leaves said finishing 
stand, the switching means being associated with shearing means, generally 
indicated 11, for shearing the lengths of product from the rolled product 
still being acted on by said stand. The switching and shearing means may 
be of conventional construction, and are arranged to coact with deforming 
apparatus 15 located along each track 12, 14. 
In FIG. 2 there is illustrated, in only its bare essentials, a deforming 
apparatus of the type associated with each of the alternate tracks 12 and 
14. Apparatus 15 includes including means for acting on the hot rolled 
product and deforming it in the sense of bending it. Consequently, said 
means act on the hot rolled product in a direction perpendicular to its 
original length, said means being constituted by sets of rollers 16 and 18 
on opposite sides of the product. Said rollers are spaced apart in 
alternate fashion longitudinally of the direction in which the product 
issues from the finishing stand, as shown. In other words, the rollers on 
one side of the rolled product are staggered relative to the rollers on 
the other side. Also associated with each one of the alternate tracks are 
rollers 48, adapted to be driven at a speed corresponding to the velocity 
at which the rolled product is to issue from the finishing stand of the 
mill. Respective sets of lifting aprons 50 are provided between adjacent 
pairs of rollers 48 along the alternate tracks. 
The arrangement is such that the sets of rollers 16 and 18 can be acted 
upon to move them from the positions in which they are shown in 
chain-dotted lines in FIG. 2, in which they lie on opposite sides of the 
rolled product passing, as shown chain-dotted, in straight line fashion 
from the finishing stand, to the positions in which they are shown in full 
lines so that the length of rolled product between them is brought to a 
sinuous form as shown in full lines. 
Referring now to FIGS. 3 and 4 which still illustrate the invention in only 
its bare essentials, apparatus for controlling the sets of rollers 16 and 
18 include respective sets of bell crank levers 20 and 22 linked together 
for simultaneous movement by sets of links 24 and 26. An endmost pair of 
the levers 20 and 22 are linked by means of respective connecting rods 28 
and 30 to respective crankshafts 32 and 34 which are geared together, as 
shown, for contra-rotation. A clutch and brake system (not shown) is used 
to power the crank shafts in timed relation to the switching means 10 and 
shearing means 11. 
Referring now to FIG. 5, this view illustrates mechanism which for the sake 
of clarity has been omitted from FIGS. 3 and 4, this mechanism being 
guiding means for guiding the lengths of rolled product along the 
alternate tracks 12 and 14. Said guiding means are constituted by lengths 
of tube 36 articulated together to allow the required deformation of the 
product in a direction perpendicular to its direction of movement from the 
mill as the sets of rollers are displaced. In fact, as shown, a leading 
end of each length of tube is connected by means of a pivot bracket 38 to 
the spindle 40 of the adjacent roller 16 or 18, and a trailing end of each 
length of tube has sliding connection with the spindle 40 of the next 
successive roller by means of a slotted bracket 42. The leading ends of 
the lengths of tube are slightly flared, as shown, to ensure the smooth 
flow of rolled product into and through the tubes. 
In the position in which the mechanism is shown in full lines in FIG. 3, 
and with the crankshafts at angles `a`, the sets of rollers 16 and 18 are 
shown to be just making contact with the hot rolled product passing 
between them. In the position in which the mechanism is shown in 
chain-dotted lines in FIG. 3, the sets of rollers are shown to have moved 
across the original path of movement of the product to have deformed it 
(in the sense of having formed a series of bends in it) in a direction 
perpendicular to its original length and to have brought it to a sinuous 
shape. It will be seen from the positions of the crankshafts 32 and 34, at 
angles `b`, that the rollers are still moving across at this instant, but 
the arrangement is such that at crank angles `b` the shearing means are 
operated to shear a leading length of product from a following length of 
product still being acted on by the final rolling mill stand. Thus, as 
illustrated in FIG. 7, shear actuation at crank angle `b` occurs prior to 
full roller deployment, while the product is still undergoing deceleration 
caused by the gradually increasing length of the sinuous path defined by 
the rollers. Simultaneously, the switching means are operated to switch 
the following length of rolled product into the alternate track for the 
subsequent deceleration and shearing of a further length of product. 
It will be seen that the action of the sets of rollers 16 and 18 on a 
length of hot rolled product passing between them is to decelerate the 
leading length of the product relative to a following length of product 
not being acted on by said rollers. In other words, because the forming of 
the series of bends takes up a certain amount of length of the rolled 
product, and the product issues from the mill at a fixed speed, although 
still travelling forwardly, the leading length of said product is, in 
effect, smoothly decelerated relative to the length of rolled product 
still being fed through the finishing stand of the mill. The result is 
that the leading length of product is decelerated to a significant extend 
before it has been sheared from the rolled product still passing through 
the mill, and in a manner not dependent on a frictional retardation of the 
product or on the frictional gripping of the product between pinch rolls. 
It will be understood that at the instant of shearing of the leading length 
of product from the following length of product still being acted on by 
the final rolling mill stand, the leading end of said leading length will 
be travelling at the declerated rate but that the trailing end of said 
leading length will be travelling at the un-decelerated rate of travel of 
the following length of product. The result of this is that following the 
shearing of said leading length of product from said following length, 
some of the kinetic energy of its trailing end portion will be immediately 
transferred to its leading end portion so that the entire cropped length 
of product will proceed forwardly at a mean decelerated rate. 
The final deceleration of the lengths of product after they have been 
sheared to length will of course be by way of frictional retardation or by 
the gripping of the product between pinch rolls, but this will be a 
relatively small part of the total deceleration required. For example, it 
is thought that if the speed of the rolled product issuing from the 
finishing stand of the mill is in the region of, say, 25 meters/sec, the 
lengths of product can be decelerated to about 7.5 meters/sec or less in 
apparatus embodying the invention before being sheared. The final 
deceleration of the sheared lengths of product by conventional apparatus 
will then not be a problem. The arrangement is of course such that as the 
initial deceleration means are brought into operation, and the switch 
means and shearing means then operated simultaneously, the lifting aprons 
50 of the track along which the just sheared length of product is passing 
are lifted to cause the final deceleration of the sheared length. 
As shown in FIG. 2, a pair of pinch rolls 44, 46 are provided on the output 
side of the means for initially decelerating the lengths of product, a 
driven one, 44 of said pinch rolls being driven at the initially 
decelerated speed and being retractable, as shown in chain-dotted lines, 
from contact with the product during the free passage of said product 
through the apparatus. The pinch rolls can be used for straightening the 
trailing ends of the lengths of product as they emerge from the apparatus 
and will also clear the lengths of product from the apparatus if the 
sliding distance for final deceleration is less than the overall length of 
the apparatus for effecting the initial deceleration. As previously 
mentioned, the run off table rollers 48 are adapted to be driven at a 
speed matching the velocity of the rolled product as it leaves the 
finishing stand of the rolling mill. The respective sets of lifting aprons 
50 which are located along the alternate tracks 12 and 14 along which 
successive lengths of product emerge from the initial deceleration 
apparatus are arranged to be lifted, by means not shown, to bring the 
lengths of product to a halt following their initial deceleration and 
shearing from the rolled product still passing through the finishing stand 
of the mill. 
Referring now to FIG. 6, the walking beam cooling bed apparatus which is 
shown associated with the deceleration apparatus just described has sets 
of walking beams 52,54 with a double pitch walk as illustrated 
diagrammatically. The arrangement is such that lengths of product can be 
deposited by the lifting aprons of the adjacent track 12 into a first set 
of notches 56 of the walking beams and by the lifting aprons of the remote 
track 14 into a second set of notches 58, the lengths of product being 
kept separate during subsequent walking of said walking beams. As shown, 
carry-over plates 60 are provides to enable the lengths of product being 
lifted by the lifting aprons of the track 14 to be deposited into the 
second set of notches of the walking beams, said carry-over plates being 
pivotally mounted to enable them to be displaced, as shown in chain-dotted 
lines, to permit the operation of the walking beams. 
Thus there is provided deceleration apparatus whereby hot rolled product 
can be decelerated in a manner which overcomes the disadvantages 
associated with previously known decelerator apparatus. Basically this is 
because all previously known decelerator apparatus has relied on slowing 
down the lengths of product after they have been sheared from the product 
still emerging from the finishing stand of the mill. In apparatus 
embodying the invention, the deceleration is achieved immediately prior to 
shearing and therefore does not rely on means for frictionally gripping 
the trailing ends of the lengths of product or involve an excessive 
sliding distance of the sheared lengths of product before they are finally 
brought to rest. The apparatus, in effect, makes use of the rolled product 
still passing through the final rolling mill stand as an anchor. The 
greater part of the mass of the length of rolled product about to be 
sheared to length is, in effect, drawn rearwardly relative to the 
following length of product immediately prior to shearing. The result is 
that by the use of apparatus embodying the invention it will be possible 
to allow hot rolled product of relatively small cross sectional area to 
issue from the finishing stand of a rolling mill at a velocity far in 
excess of that which has been possible hitherto. 
It will of course be understood that the rate of initial deceleration can 
be accurately controlled, and can be arranged to be substantially 
constant, by adjusting the drive geometry and adjusting its speed of 
operation so as to adjust the rate at which the rollers form the bends in 
the lengths of product. The pressure of the rollers against the rolled 
product is much less than that of pinch rolls and will not deform the 
cross sectional shape of the product. Specially shaped grooves in the 
rollers, that is to say matching the cross sectional shape of the product, 
will not be required. 
Various modifications may be made. For example, the mechanism for 
displacing the rollers for forming the bends in the rolled product may be 
varied in numerous ways. One different way of displacing the rollers for 
forming the bends in the rolled product would be to mount oppositely 
disposed but staggered pairs of said rollers on rotatable carriers, the 
rotatable carriers being spaced apart longtiduinally of the direction of 
travel of the rolled product as it issued from the final rolling mill 
stand, said carriers being arranged to be rotated, simultaneously, through 
pre-determined angles to move the pairs of rollers to positions in which 
they bring a leading length of the rolled product to a sinuous form. The 
mechanism need not necessarily be driven by mechanical means, that is to 
say for example by the contra-rotating crankshafts 32 and 34 of the 
illustrated embodiment. It could for example be powered by at least one 
hydraulic ram arranged to displace the connecting rods for moving the bell 
crank levers of the illustrated embodiment or for displacing a toothed 
rack or a series of toothed racks engaging toothed segments associated 
with the rotatable carriers of the possible modification just described, 
as the case may be. The number of bends being formed to effect the initial 
deceleration of the product may also be varied, depending upon the lengths 
of the sheared product and hence their weight. Furthermore, instead of 
arranging for both sets of rollers to be movable, it may be preferred to 
hold one set of rollers stationary and to drive the other set of rollers 
through twice the distance.