Apparatus for removing a welding bulge from pipes

Abstract

A welding bulge removing apparatus comprises a U-shaped carrier adapted to be placed by means of rollers on welded pipes at the weld bulge, and being provided with an arcuate guideway and a toothed segment. It also comprises a motor-operated carriage having a driving gear wheel and support rollers. Mounted on the carrier are cutting tool holders movable to and from the weld bulge. The gear wheel and the support rollers of the carriage are respectively brought into engagement with the toothed segment and the arcuate guide-way of the carrier. The carriage is adapted to be rigidly connected to a lifting mechanism of a vehicle used for raising and carrying the welding bulge removing apparatus, whereby rotation of the carrier is effected, while the carriage remains immobilized.

Description

BACKGROUND OF THE INVENTION

The present invention is related to an apparatus for removing a welding bulge, and in particular, to an apparatus for removing a welding bulge from resistance welded pipes while laying pipelines.

Variously constructed and modified apparatus for removing a welding bulge, intended for operation in specific conditions, are well known in the art.

The invention is directed to an apparatus designed for field operation while laying pipelines for the long-distance transporation of petroleum and gas. More specifically, the present invention deals with the apparatus designed for removing a welding bulge from resistance welded pipes under the aforesaid conditions.

Apparatus thus far proposed, as exemplified in USSR Inventor's Certificate Nos. 507373, 468729, 468730, generally comprise impact or cutting tools, motion and static parts, and mechanisms for driving the tools.

Such apparatus, particularly those intended for large-diameter (over 1,000 mm) pipes, are of large dimensions and heavy weight, and therefore present problems in service and are greatly time-consuming for setup under field conditions in pipeline construction. As a consequence, their performance has proved to be lower than that of the electric resistance welding machines, which machines together with the apparatus in question forming part of a single production complex.

Known in the prior art is an apparatus for removing a welding bulge from resistance welded pipes as disclosed in USSR Inventor's Certificate No. 589090. This apparatus comprises a U-shaped carrier adapted to be placed at the bulge zone in spaced circumferential relationship to the welded pipes and it is provided with centering rollers, at least two of which are radially movable with respect to the center of the welded pipes circumference and are generally disposed on the end portions of the carrier, and cutting tool holders disposed on the carrier provide movement to and from the weld bulge.

The radially movable centering rollers are motor-operated, whereby the carrier will be turned about the pipes at the weld bulge zone.

In operation, the motor-operated centering rollers by rolling over the pipes impart rotary motion to the carrier. As this takes place, the holders will perform the approach of the cutting tools to the weld bulge and the carrier will provide the feed of this tool.

Though simple in construction, this apparatus will suffers from a number of disadvantages.

Inasmuch as the motor-operated centering rollers of the known apparatus are supported upon the welded pipes, the reliability of the drive for feeding cutting tools is completely dependent on the engagement of the motor-operated rollers with the surface of the pipe, providing the drive power is sufficient to defeat resistance to the cutting tools.

The reliability of the roller-pipe engagement is in turn dependent on the surface condition of the pipes and the rollers, since under field conditions there may be ice formation, oil film, and other friction-affecting deposition formations which can affect the friction between the contacting parts. This brings about vibration in the tools and a drop in the speed of feeding thereof, which in turn impairs performance of the prior art apparatus. The problem of performance is even more acute in view of the fact that the welding bulge has to be removed in more than one pass.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an apparatus for removing a welding bulge from resistance welded pipes, which is of a simple construction.

One more object of the present invention is to provide an apparatus of the kind specified, which exhibits a higher performance as compared to that of the apparatus of a similar design.

A further object of the invention is to provide a more reliable apparatus for removing a welding bulge.

These and other objects of the invention, will become clear from the following detailed description of an embodiment of the invention, when taken in conjunction with the accompanying drawing, wherein an apparatus for removing a welding bulge from resistance welded pipes comprises a motor-operated carriage adapted to be rigidly connected to a lifting mechanism of a vehicle used for raising and carrying the apparatus. The carriage includes support rollers and a driving gear wheel. The apparatus further includes a U-shaped carrier having an arcuate guideway and a toothed segment both adjacent the outer periphery of said carrier and extending the length thereof, and they are brought into engagement with the support rollers and the driving gear wheel of the motor-operated carriage respectively. In operation, this arrangement provides for rotation of the carrier, while the carriage remains immobilized.

The apparatus of the invention, being specifically adapted for an in-the-field operation while laying pipelines, provides for the required performance and reliability as well as a higher quality surface after bulge removal. In the course of test runs of the apparatus about 2000 butt welds between pipes of a large diameter (1420 mm) were machined, the performance being 5 to 6 butt welds per hour.

BRIEF DESCRIPTION OF THE DRAWING

The nature and principles of the present invention will be understood by reference to the accompanying sole FIGURE of the drawing which shows diagrammatically an apparatus of the invention as viewed along the axis of the welded pipes.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the drawing, the apparatus for removing a welding bulge from resistance welded pipes comprises a U-shaped carrier 1 adapted to be placed at the weld zone in spaced circumferential relationship to the welded pipes. The carrier is preferably of a disk-like shape having a central opening 2 of a diameter, which complies with the above condition, and a slot 3 as wide as the diameter of the central opening so that the carrier 1 takes the form of a U with end portions separated by a spacing or the slot 3 to pass the welded pipes therebetween in placing the carrier 1 into position.

The carrier 1 is provided with centering rollers which are arranged adjacent the periphery of the central opening 2 of the carrier 1 or the inner periphery of the same carrier. The centering rollers are mounted in pairs, of which rollers those designated by the reference numeral 4 are made stationary with respect to the carrier 1 and are disposed on the middle portion of the carrier, and those referred to as rollers 5 are mounted for radial movement relative to the center of the circumference of the welded pipes by means of hydraulic cylinders 6 and together with the hydraulic cylinders 6 are disposed on opposite end portions of the carrier 1. Also, the rollers 5 of one end portion of the carrier 1 are so related to those of the other end portion that in the operating position when the same are in contact with the pipe surface, the distance between them is less than the pipe diameter. It is to be noted that the number of the centering rollers is for illustrative purposes only in that present disclosure and the one skilled in the art can easily find some other solution as to the number of the rollers and their arrangement.

Mounted on the carrier 1 are two holders 7 for cutting tools, for example milling cutters 8, each of the holders 7 being disposed at diametrically opposite locations on the carrier 1. Each holder 7 is belt driven from an electric motor 9 and together with the latter are mounted on a suspension member 10, which is articulated to the carrier 1 at 11. Each suspension member 10 apart from being articulated as shown in the drawing at 11 is also connected to the carrier 1 via means providing radial movement, such as a hydraulic cylinder 12 mounted for moving the holder 7 to and from the weld bulge on the suspension member 10 swinging about a link pin at 11. The suspension members 10 also carry former rollers 13.

According to the invention, the carrier 1 is provided with an arcuate guideway 14 and a toothed segment 15, both being adjacent its outer periphery. The apparatus is also furnished with a motor-operated carriage generally designated by reference numeral 16 and comprising a frame 17 supported by support rollers 18, a driving gear wheel 19 and an electric motor 20 for setting in motion the gear wheel. In the drawing, the support rollers 18 and the driving gear wheel 19 are respectively brought into engagement with the arcuate guideway 14 and the toothed segment 15, with the support rollers 18 being arranged and in engagement with the arcuate guideway 14 at both sides the inner and outer thereof.

According to the invention, the carriage 16 is adapted to be rigidly connected to a lifting mechanism of a vehicle, such as a pipe laying crawler-type machine, which may be used for raising and carrying the present apparatus.

For the purposes of this disclosure, "a rigid connection" is thought of as the provision of a carriage which is stationary with respect to the welded pipes at the zone of a weld bulge to be removed and this can be achieved by means of a link 21 and a suspension fixedly connected to a vehicle boom designated by reference numeral 22 for the purposes of illustration only.

OPERATION OF THE APPARATUS DESCRIBED

As previously stated, the apparatus of the invention may be moved by any suitable vehicle, and with reference to one of the sequence of butt joints in a pipeline which has been welded, the carrier 1 is placed at the bulge zone on the pipes, such as shown in the drawing by reference numeral 23. It is to be understood that the carrier 1 will be supported by means of the centering rollers 4 and 5, the pipes having been preliminarily centered by the rollers 5 through the use of the hydraulic cylinder 6.

In operation, the milling cutters 8 in holders 7, which are set in rotational motion by the electric motors 9, approach the weld bulge by the use of means in the form of hydraulic cylinders 12 so as to incise or cut into an upset or bulge metal until the former rollers 13 come into contact with the surface of the pipes 23.

In this manner, the holders 7 are radially moved, i.e., the cutting tools approach the weld bulge.

By switching on the electric motor 20 the gear wheel 19 is set in motion and rolls thereby over the toothed segment 15. Since the carriage 16 is stationary with respect of the pipe 23, the carrier 1 begins rotation about the pipes. In this manner the cutting tools are fed along the entire circumferential weld of the butt joint.

The cutting tools are fed during one half of the rotation of the carrier 1, inasmuch as one half of the rotation is sufficient for each of the two milling cutters 8 to machine half of the weld length, i.e. the wed bulge will be completely removed in half the rotation or one-half revolution of the carrier 1. It will be readily understood that by increasing the number of cutting tool holders the length of feeds may be decreased, which is in conformity with the principles of the present invention provided such increase in the number of holders does not unduly complicate the apparatus.

After the weld bulge has been removed, the cutting tool holders 7 are moved from the surface of the pipes 23 with the help of the hydraulic cylinders 12, and the carrier 1, having made a reverse motion for half the rotation, again takes the initial position. Now, after the rollers 5 have been removed off the pipe surface the apparatus is ready for transfer to the next butt joint without any additional operations in the case as the apparatus is dependent on electric and pressure sources from the vehicle.

As hereinabove disclosed, the apparatus of the invention is simple in construction, offers good service conditions, and is less time-consuming for setups. This permits more efficient utilization of such apparatus in laying pipelines.

While the invention has been described in terms of the preferred embodiment, numerous variations may be made in the apparatus illustrated in the drawings and herein described without departing from the invention as set forth in the appended claim.

Claims

1. An apparatus for removing a welding bulge from resistance welded pipes, which comprises:

a U-shaped carrier adapted to be placed at the bulge zone in spaced circumferential relationship to the welded pipes and having end portions spaced apart for the welded pipes to pass therebetween, an arcuate guideway having inner and outer surfaces, and an arcuate toothed segment both adjacent the outer periphery of said carrier and extending the length thereof;

centering rollers mounted on said carrier adjacent the inner periphery thereof, means providing that at least two of said centering rollers are radially movable with respect to the center of the welded pipes circumference and disposed on opposite end portions of said carrier;

cutting tool holders disposed on said carrier for movement to and from the weld bulge;

a motor-operated carriage with means to be rigidly connected to a lifting mechanism of a vehicle used for raising and carrying the apparatus, which carriage including spaced support rollers and a driving gear wheel, said spaced rollers being disposed in engagement with the inner and outer surfaces of said arcuate guideway and said driving gear being in driving engagement with the toothed segment of said carrier to rotate said carrier while said carriage remains immobilized.

2. The apparatus according to claim 1, wherein said cutting tool holders are two in number and they are disposed at diametrically opposite locations on said carrier.