FRICTIONAL ROLL SPEED SYNCHRONISATION DEVICE FOR SPIRAL WELD PIPE ONLINE CUTTING SYSTEM

FIELD OF THE INVENTION:

The present invention relates to carriage dragging mechanism by rubber rolls for on line spiral weld pipes, in synchronization with pipe gas cutting system for a symmetrical cutting. More particularly, the present invention discloses synchronize cutting system by frictional rolls.

BACKGROUND OF THE INVENTION:
Spiral weld pipe plant has two identical pipe forming machines, in which pipes of 20 inch to 64 inch outside diameter pipes are produced by submerged arc welding process.
Here in these machines the HR coils passed through several equipments of the machine to form SW pipes and finally the travelling Oxy-acetylene torch cuts off the pipes to required length, as per customer requirement at RFC (rotary flame cutter). This cutting is carried out online process without stopping the mill.
RFC: Rotary Flame Cutter: This is an online cutting equipment of machine which cuts the pipes by oxy-acetylene gas cutting system. It comprises of two identical parallel rings of 68 inch internal diameter connected with each other by means of 3 nos. of barrel. Out of these two rings one ring is call entry side and another is called exit side.
These 3 barrels comprises of 3 nos. of gear boxes mounted on each connecting end of two rings. These 3 gear boxes are also interconnected with a single shaft so as to work simultaneously when driven. So there are 3 nos. gear boxes are mounted at entry side ring and 3 nos. gear boxes are mounted at exit side ring. Each gear box shaft of entry side is connected with each other by means of 3nos link arms. Out of these 3 link arm one arm is connected with a hydraulic operated cylinder
The entire RFC assembly having no electrical or other drive system, it dragged forward by means of pipe speed when the 6nos pins clamp the pipe body.
The requirement of this cutting system is that, the start and the end of cutting meets at same point. Due to any mismatch of electrical signal or failure of mechanical spares leads to no cutting or step cutting (step cutting means the start and end point of cutting not meeting at a point) leads to stoppage of production and repeated cutting of pipes done by hand cutting further symmetrical cutting is carried out at different machine, which cause finishing mill congestion causing interruption in production. Apart from this, mostly mechanical and electrical spares are not available due to obsolesce.

OBJECTIVE OF THE INVENTION:
The principle object of the present invention is to reduce the downtime due to rotary flame cutter failure and to increase equipment availability to increase quality pipe production

SUMMARY OF THE INVENTION
Replacing the gigantic RFC structure by simple modification. The entire ring assembly was taken out from the carriage and one simple frame was attached to the carriage. The frame comprises of two rubber roll and two simple double acting hydraulic cylinders.

BRIEF DESCRIPTION OF ACCOMPANYING DRAWING:
Fig. 1 illustrates two nos. of schematic carriage dragging mechanism in accordance with the present invention;

Fig. 2 illustrates side view of carriage dragging mechanism in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION:

The best part of the present entire RFC assembly is that it had no electrical or other drive system. During cutting, earlier the assembly was getting clamped with the pipe body and getting dragged forward along with the motion of the pipe. This entire clamping mechanism is replaced with bottom supported rubber rolls which due to friction dragged the RFC assembly along with the motion of the pipe.

This innovative mechanism has ensured symmetrical cutting by achieving perfect speed synchronization and eliminated the cutting problems of pipes. The new system has the advantage of being very simple in design and user friendly. Further it reduces the spare requirement and ease in adjustments during different size diameter change. Besides, it has enhanced safety, reliability and availability of the equipment.

The gigantic RFC structure was replaced by one simple modification. The entire ring assembly was taken out from the carriage and one simple frame was attached to the carriage. The frame comprises of two rubber roll and two simple double acting hydraulic cylinders. The attached frame consists of two platforms, one is fixed platform and another is movable one just placed over the fixed platform.

The fixed platform is attached to the main carriage rigidly by means of welding. Then two small size double acting hydraulic cylinder are fixed vertically and parallel at a distance apart and connected to the hydraulic system , then the movable platform is placed over the fixed platform and cylinder shackles are fixed with this movable platform’s brackets situated at bottom surface of movable platform.

At the top of movable platform two rubber roll around 300mm dia. is fixed at a distance apart facing each other at 600/1200 in such a way that it should not touch the pipe when the hydraulic cylinder is not actuated upward. When the cutting command is given, the hydraulic cylinder is actuated upward and touches the pipe body and then the carriage start dragging forward with same speed of pipe due to the friction between pipe body & rolls. These rolls are mounted on a lead screw for to & fro motion required for diameter change settings.

At the exit side of the carriage one half cut ring was placed on the carriage and the same oxy-acetylene cutting arrangement attached to it for cutting to the desire length.
When the desire length of pipe is required to cut the hydraulic cylinder actuates upward and the roll mounted frame lifted up to touch the pipe sidewise. When the rolls touch the rotating pipe then there is a relative motion between the pipes and rolls.

Initially the rubber rolls are set slightly opposite angle of pipe rotating angle, as a result a frictional force is generated between pipe and rolls , which leads to drag the cutting carriage in the direction of pipe formation and simultaneously symmetrical cutting is carried out without fail.

USEFULNESS OF THE INVENTION :
I. Huge economics of cost saving.
II. Easier mechanical maintenance/repair/replacement.
III. Production loss due to equipment downtime eliminated.
IV. Material yield increased by avoiding step cutting and mill stoppage.
V. Quality of pipes enhanced.
VI. Higher production- the machine could be run at its optimal speed and produce better quality due to continuous smooth online cutting.
VII. Repair/replacement of roller and hyd.cylinder is comparatively very easier.
VIII. ECONOMIC:
a. TOTAL COST OF MAINTENANCE PER YEAR IN ONE M/C: RS. 58.55 LAKHS
b. TOTAL COST OF MAINTENANCE PER YEAR IN TWO M/C: RS. 117.10 LAKHS
c. ONE TIME SAVING - ONGOING AMR SCHEME COST AROUND RS. 94.0 LAKHS DROPPED
d. Total saving : RS.211.10Lakhs
Further, unnecessary time and manpower wastage eliminated leading to improvement in morale of the workmen.

INDUSTRIAL APPLICABILITY:
This frictional roll speed synchronisation device can be implemented at any spiral weld pipe online cutting system to improve productivity and quality. Apart from this, the innovation can be used in non-SAIL sinter plants also in India and abroad.
Although the foregoing description of the present invention has been shown and described with reference to particular embodiments and applications thereof, it has been presented for purposes of illustration by way of examples and description and is not intended to be exhaustive or to limit the invention to the particular embodiments and applications disclosed. The particular embodiments and applications were chosen and described to provide the best illustration of the principles of the invention and its practical application to thereby enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. All such changes, modifications, variations, and alterations should therefore be seen as being within the scope of the present invention as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly, legally, and equitably entitled.

WE CLAIM:

1. A frictional roll speed synchronization device for spiral weld pipe online cutting system comprising of :
a frame including two rubber roll and two simple double acting hydraulic cylinder; wherein the attached frame consists of two platforms, one is fixed platform and another is movable one just placed over the fixed platform.

2. The frictional roll speed synchronization device as claimed in claim 1, wherein the said fixed platform is attached to the main carriage rigidly by means of welding.

3. The frictional roll speed synchronization device as claimed in claim 1, wherein the said two double acting hydraulic cylinder are fixed vertically and parallel at a distance apart and connected to the hydraulic system.

4. The frictional roll speed synchronization device as claimed in claim 1, wherein the said movable platform is placed over the fixed platform and cylinder shackles are fixed with the said movable platform’s brackets situated at bottom surface of movable platform.

5. The frictional roll speed synchronization device as claimed in claim 1, wherein the said two rubber roll around 300mm dia. is fixed at a distance apart facing each other at 600/1200 in a such a way that it should not touch the pipe when the hydraulic cylinder is not actuated upward positioned at the top of movable platform.

6. The frictional roll speed synchronization device as claimed in claim 1, wherein during working, the hydraulic cylinder is actuated upward and touches the pipe body and then the carriage start dragging forward with same speed of pipe.

7. The frictional roll speed synchronization device as claimed in claim 1, wherein the said rolls are mounted on a lead screw for to & fro motion required for diameter change settings.
8. The frictional roll speed synchronization device as claimed in claim 6, wherein at the exit side of the carriage one half cut ring was placed on the carriage and the same cutting arrangement attached to it for cutting desire length.

9. The frictional roll speed synchronization device as claimed in claim 6, wherein during working, when the rolls touches the rotating pipe then there is a relative motion between the pipes and rolls.

10. The frictional roll speed synchronization device as claimed in claim 6, wherein the said rubber rolls are set with slightly opposite angle of pipe rotating angle, as a result a frictional force is generated between pipe and rolls , which leads to drag the cutting carriage in the direction of pipe formation and simultaneously symmetrical cutting is carried out.