US3815400A

US3815400A - Apparatus for reducing the thickness of metal

Info

Publication number: US3815400A
Application number: US00307825A
Authority: US
Inventors: K Saxl
Original assignee: Imperial Metal Industries Kynoch Ltd
Current assignee: Imperial Metal Industries Kynoch Ltd; Imperial Metal Industries Ltd
Priority date: 1972-11-20
Filing date: 1972-11-20
Publication date: 1974-06-11
Anticipated expiration: 1991-06-11

Abstract

A pendulum mill for reducing the thickness of metal and in which driving means to the pendulum arms are interconnected to eliminate backlash in the system.

Description

[451 June 11,1974

United States Patent [191 Saxl m Q m m, w 9 U. G N I mi n E M mw S U Tm m R MC Pm AT Q 5 UNITED STATES PATENTS [75] Inventor:

Limited, Witton, Birmingham, England 1 Primary ExaminerLowe11 A. Larson Attorney, Agent,

[22] Filed: Nov. 20, 1972 [21] Appl. No.: 307,825

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APPARATUS FOR REDUCING THE THICKNESS OF METAL BACKGROUND OF THE INVENTION ing the thickness of metal.

2. Description of the Prior Art In the specification of our British Pat. No. 889,662 there is described a method of reducing the thickness of metal which comprises advancing the metal between and beyond a pair of freely rotatable work-rolls disposed on opposite sides of the metal, and subjecting the metal to the rolling action of the pair of workrolls, the rolls moving in synchronism in pendulum-like manner at high speed and effecting reduction in both directions of movement.

This method is performed by apparatus comprising a frame, a pair of arms oscillatable about pivotal axes, these arms having freely rotatable workrolls mounted on their free ends which lie closer together than their pivotal axes, and mechanical driving means operable so as to cause oscillation of the arms in synchronism with one another. The mechanical driving means is provided by two crankshafts which are interconnected by a gear train, and one of the crankshafts is driven from an electric motor. During use of the apparatus, the oscillating parts absorb energy whilst accelerating from a momentary stationary position at the beginning of a stroke to full speed at approximately mid-point between the ends of the travel of the workrolls. This energy is reabsorbed in the rotating parts of the drive mechanism during travel between the mid-point and the end of the stroke. Because of the different drives to the two crankshafts, i.e. motor and drive shaft to one crankshaft, and gear train drive to the other crankshaft, it has been found that the difference in the flywheel effect of the rotating parts connected to the two crankshafts disturbs the synchronisation of the oscillatable arms to the extent permitted by the backlash in the gear train.

An object of the present invention is to provide an apparatus in which the above disadvantage is reduced.

SUMMARY OF THE INVENTION According to the present invention, apparatus for reducing the thickness of metal comprises a frame, upper and lower oscillatable arms, each pivotally mounted about a pivotal axis upon the frame, the upper and lower arms having free ends which lie in closer relationship than their pivotal axes, a freely rotatable workroll mounted on the free end of each arm and forming part of a workroll assembly, driving means associated with each arm for oscillating the arms in synchronism through a common plane in which the pivotal axes lie and for a distance on each side of the plane, each driving means including an electric driving motor, the motors being connected-in an electrical circuit whereby one provides a greater torque than the other, and a gear train connecting the driving means of one arm with the driving means of the other arm at positions between the motors and the arms.

Preferably the gear train comprises a drive connecting shaft with gears at each end for connecting the driving means of one arm with the driving means of the other arm.

. posed of two half-shafts drivably connected together by means of a couplingwhichpermits relative angular adjustment of the half-shafts.

' With the one motor supplying greater torque than the other one, the motor supplying the greater torque places the drive connecting shaft in torque as the other motor tends to run at a slower speed. The torque provided by the drive connecting shaft tends to speed up the slower moving driving means so that relative movement out of phase of the arms otherwise permitted by backlash is resisted.

ln one practical construction, the oscillating movement of the arms is imparted by connecting rods driven by crankshafts. To ensure that as much as possible of backlash and out of phase movement is eliminated, it is necessary to put the driving connecting shaft at the closest position to the arms themselves. The most convenient position for the connecting shaft and gear train is, therefore, one in which it connects the crankshafts together so as to maintain the rotational movement of the crankshafts in phase.

It is preferable that in the electrical circuit, means are included for infinitely varying the voltage to one of the motors relative to the other so as to vary the load placed by the drive connecting shaft and gears upon the driving means which would tend to run at a slower speed.

DESCRIPTION OF THE DRAWING One embodiment of the invention will now be described by way of example only, with reference to the sole accompanying drawing which is a side elevational view partly in section of apparatus forming the embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENT In the embodiment, apparatus for reducing the thickness of metal consists of a rolling mill which is basically of similar construction to apparatus for reducing metal thickness first described in the specification of our UK Pat. No. 889,662.

The mill basically comprises a pair of pendulum arms 1 and 2, the upper arm 1 being pivotally mounted between spaced apart arm carrying beams 3 about a pivotal axis 4 located intermediate the beam ends, and the lower arm 2 being pivotally mounted in a similar manner between spaced apart arm carrying beams 3a. The beams are pivotally mounted to the mill frame by pivot pins 5 adjacent one end of each beam. The other end of each beam is free and is operably engaged by a screw-down load device 6. A tension spring 7 is provided to urge the two arms apart so as to hold the upper beam 3 upwards when this is not subjected to a component of rolling load and prevent it from dropping under its own weight. The two pivotal axes 4 of the two arms are disposed one directly above the other. A part of each arm extends from its pivotal axis towards the other arm to terminate in an end of the arm opposing that of the other arm. Each of the opposing ends is provided with a workroll 8 freely rotatably mounted thereon with its axis parallel to the pivotal axis 4 of the arm and a plurality of supporting or back-up rolls 9 for the workroll. The arms oscillate about their axes on both sides of a pass-line A-A for metal to move the workrolls in synchronism alternately in the direction of 3 feed of the metal and then in the opposite direction with the axes of the workrolls extending in a direction normal to the pass-line.

Driving means is provided for oscillating each arm 1, 2, through a plane in which the pivotal axes 4 lie, the driving means comprising a connecting rod pivotally mounted at one end to a part 11 of the arm on the side of the pivotal axis 4 of the arm remote from its workroll 8. The other end of the connecting rod is pivotally mounted to an eccentric'crank portion 12 of a crankshaft 13. Each crankshaft is drivably connected to a respective electric-driving motor 14 through an intermediate coupling (not'shown). The driving motors are connected in an electrical circuit whereby, in use, the motor'driving the upper arm 1 is subjected to a greater voltage than the other motor so that it supplies a greater torque than the other motor. I

.The end of each crankshaft l3 remote from its motor has keyed thereto a bevelgear 15 which engages with a respective bevel gear 16 secured to an adjacent end of a connecting shaft 17. The shaft 17 is composed of two half shafts 17a, 17b drivably connected together by means of a coupling 18 which permits fine angular adjustment to be made between the two half shafts. The shaft 17 is thus connected to the upper and lower crankshafts by means of the bevel gears and connects the driving means of the upper arm 1 with the driving means of the lower arm 2 at positions between the electric motors I4 and the arms.

in use of the apparatus, metal is fed towards and between the workrolls 8 by feed rolls [9, the metal being reduced in thickness by the oscillating movement of the workrolls. By virtue of the arrangement that the motor which drives the upper arm 1 supplies a greater torque than the motor which drives the lower arm 2, and because the connecting shaft 17 connects together the driving means for the upper and lower arms, the connecting shaft is maintained in a state of torsion and eliminates backlash in the system between the crankshafts and the arms. Consequently, any variation in the static or dynamic forces acting on the crankshafts is counteracted by the drive connecting shaft 17 and the movements of the upper and lower arms are maintained insynchronism.

In the above described construction, a means may be included for infinitely varying the voltage supplied to one of the motors so that the potential differential speeds of the two driving means may be infinitely varied. The torsional stresses in the drive connecting shaft may, therefore, be infinitely varied to suit any out of balance static or dynamic forces which may be set up in the apparatus so as to counterbalance these forces and reduce or virtually eliminate any out of phase rotation of the crankshafts and thereby improve synchronisation of the workrolls.

The alteration of the voltage upon one of the motors may be carried out manually. Alternatively, an automatic control may be provided for the voltage and this automatic control may be operated by a sensing device monitoring the actual relative position of the rollcarrying arms.

I claim:

1. Apparatus for reducing the thickness of metal comprising a frame, upper and lower oscillatable arms, each pivotally mounted about a pivotal axis upon the frame, the upper and lower arms having free ends which lie in closer relationship than their pivotal axes, a freely rotatable workroll mounted on the free end of each arm and forming part of a workroll assembly, driving means associated with each arm for oscillating the arms in synchronism through a common plane in which the pivotal axes lie and for a distance on each side of the plane, each driving means including an electric driving motor, the motors being connected in an electrical circuit whereby one provides a greater torque than the other, and a gear train connecting the driving means of one arm with the driving means of the other arm at positions between the motors and the arms.

2. Apparatus according to claim 1 wherein the gear train comprises a drive connecting shaft with gears at each end for connecting the driving means of one arm with the driving means of the other arm.

3. Apparatus according to claim 2 wherein the drive connecting shaft is composed of two half-shafts drivably connected together by means of a coupling which permits relative angular adjustment of the half-shafts.

4. Apparatus according to claim 1 wherein the driving means associated with each arm comprises a connecting rod driven by a crankshaft and the drive connecting shaft and gear train connects the crankshafts together.