Machining Apparatus

The present invention relates to an apparatus for machining an outer periphery of a cylindrical work piece and, in particular, although not exclusively, a machining apparatus for grinding an outer periphery of a work piece.

In the oil and gas industry it is common for machined items to be inserted into a pipe, such as a drill tube or drill pipe. For example, fishing operations are carried out which require the insertion of a fishing tool into a drill tube. Similarly, stabilisers are used to stabilise a work-string or shaft within a drill tube during use. Frequent refurbishment of such generally cylindrical components is required due to their operating conditions.

Refurbishment of such components is usually performed using old grinding machines, which are also in need of replacement. Such old equipment is often slow to machine a work piece. Both of these factors increases a cost machining a work piece. In addition, the dimensions of the work pieces in need of refurbishment vary considerably, requiring a plurality of machines. For example, drill tubes are typically over 12 meters long and 254mm in diameter, whereas a stabiliser is much shorter, but up to 914mm in diameter. Thus, a number of machines of different sizes are often required.

It is an aim of the present invention to provide a machining apparatus which overcomes at least some of the above-mentioned problems.

It is an aim of the present invention to provide an apparatus for machining an outer peripheral surface of generally cylindrical work pieces having a wide range of diameters and lengths.

It is an aim of the present invention to provide a machining apparatus which is relatively cheap to purchase and operate.

It is an aim of the present invention to provide an apparatus which reduces a machining time.

It is an aim of the present invention to provide an apparatus which is capable of machining an outer peripheral surface of a drill tube, a fishing tool, a stabiliser or other tool for use in an oil or gas pipeline or drill tube.

According to the present invention there is provided an apparatus and method as set forth in the appended claims. Preferred features of the invention will be apparent from the dependent claims, and the description which follows.

According to an aspect of the present invention, there is provided a machining apparatus for machining an outer periphery of a generally cylindrical work piece, comprising rotating means arranged to grip an outer periphery of a work piece at an intermediate region thereof and to, in use, rotate the work piece, and machining means arranged to, in use, contact against and machine an intermediate region of the work piece.

According to a first aspect of the present invention, there is provided a machining apparatus for machining an outer periphery of a generally cylindrical work piece, comprising: rotating means arranged to grip an outer periphery of a work piece at an intermediate region thereof and to, in use, rotate the work piece; machining means arranged to, in use, contact against and machine an intermediate region of the work piece; first supporting means for supporting an end of the work piece; and second supporting means for supporting an intermediate region of the work piece; wherein the first and second supporting means are selectively utilised to support the work piece.

According to a second aspect of the present invention, there is provided a method of machining an outer periphery of a generally cylindrical work piece, comprising: gripping an intermediate region of a work piece; selectively supporting either an end of the work piece or a an intermediate region of the work piece; rotating the work piece; and machining the rotating work piece.

According to a third aspect of the present invention, there is provided a support means for supporting a work piece upon a machining apparatus, comprising: support means for engaging a work piece and providing support thereto; and attachment means for readily releaseable attachment to a machining apparatus.

For a better understanding of the invention, and to show how embodiments of the same may be carried into effect, reference will now be made, by way of example, to the accompanying diagrammatic drawings in which:

Figure 1 is a perspective view of a preferred embodiment of the present invention;

Figure 2 is a perspective view of a preferred embodiment of a work head;

Figure 3 is a further perspective view of the work head;

Figure 4 is a rear perspective view of the work head and work head end region of a work bed;

Figure 5 is a perspective view of a preferred embodiment of a wheel head, without a grinding wheel attached;

Figure 6 is a close-up perspective view of a lower portion of the wheel head;

Figure 7 is a perspective view of a work bed carriage mounted upon the work bed having a tail stock detachably mounted thereon; and

Figure 8 is a perspective view of a work piece steady suitable for detachably mounting up the work bed carriage.

The machining, and in particular the grinding, of generally cylindrical tools used in the oil and gas industry is required to refurbish or manufacture said tools, since the materials from which the tools are manufactured is very hard. However, the tolerances of manufacture or refurbishment are relatively low, in the region of 0.8 mm. Therefore, grinding, as opposed to

other types of machining, e.g. cutting etc., is normally preferred. However it will be realised that the preferred embodiment may be adapted to machine work pieces in other ways .

As shown in Figure 1, a preferred embodiment of a machining apparatus 1 of the present invention comprises a work bed 10, which has mounted thereon a work head 20, a moveable work-bed carriage 30 having detachably mounted thereon a tailstock 40, and a wheel head 50.

The work bed 10 is generally rectangular in shape and is manufactured from a suitably heavy-duty machined metal element. The function of the work bed is to provide a support structure upon which the work head 20 is fixedly mounted, and on which the work bed carriage 30 and grinding head 50 are moveably mounted.

The work bed 10 comprises means for levelling, such as extendable feet and allows a liquid coolant tank to be attached thereto. The work bed 10 has a greater longitudinal axis, in parallel with which the work piece to be machined is arranged in use. Perpendicular to the longitudinal axis is a transverse axis of the work bed 10. The length of the transverse axis is less than the length of the longitudinal axis. In use, the work piece to be machined is suspended over the front half of the work bed

10 between the work head 20 and tail stock 40, or between the work head 20 and a work steady 60 mounted upon the work bed carriage 30.

A pair of carriage rails 11 or tracks are mounted upon the upper surface of the work bed 10. The carriage rails

11 are arranged in spaced-apart relation, parallel to the longitudinal axis of the work bed 10, in the front half of the work bed 10. The rails 11 extend from the work head 20 along the length of the work bed 10.

The work bed carriage 30 is moveably mounted upon the carriage rails 11, such that the carriage 30 may be moved along the length of the work bed 10 in alignment with the longitudinal axis. In this way, the carriage 30 may be brought closer toward, or moved away from the work head 20 in order to accommodate work pieces of different lengths. The carriage 30 may be locked in position on the rails 11 by a user.

Figure 2 shows the work head 20 in more detail.

The work head 20 comprises an aperture there-through, within which is rotatably mounted a hollow-spindle 21 headstock. The work head 20 is a generally box-type fabrication which supports and rotates the work piece in use. The hollow spindle 21 is rotatably mounted between opposed pairs of bearings within the work head 20. In order to deal with both axial and radial forces, taper roller bearings are used at a forward or centre facing end of the hollow spindle 21, whilst roller bearings are used at a rear or outward end. The work head 20 is fixedly mounted to the work bed 10 so as to remain stationary during use.

In use, a work piece to be machined is inserted through the hollow spindle 21. The work piece is arranged to protrude from the centre-facing end of the hollow spindle 21 to be machined. In addition, the work piece

may protrude from the outer end of the hollow spindle 21. Advantageously, this arrangement of through-hole mounting of the work piece allows a work piece to be machined which is longer than the length of the work bed 10. The work piece may extend from the outer end of the hollow spindle

21 during machining. In this way, a length of work piece is not limited by the length of the work bed 10. The outer end of the hollow spindle 21 may also comprise a plurality of radially extending apertures which are arranged to intersect a centre of the hollow spindle aperture. Suitable bolts or other fasteners can be inserted through the aperture to contact the work piece in order to centralise it within the hollow spindle 21 aperture .

An outer end of the hollow spindle 21 comprises a toothed drive wheel 22. In use, the toothed drive wheel

22 is driven, via a toothed belt (not shown) , by a drive motor (not shown) mounted atop the work head 20. In use, through suitable electronic control of the drive motor and gearing, the work piece mounted through the hollow spindle 21 can be rotated to machine an outer periphery of the work piece, as will be explained. Typical rotational speeds of the work piece are in the region of between 10 and 100 RPM.

Referring to Figure 3, an inward end of the hollow spindle 21, opposed to the toothed drive wheel 22, comprises a chuck 23 having radially extending flange or disc 22 with, at it its centre, an aperture through which the item to be machined or work piece protrudes in use, thus forming a chuck 23 to grasp an outer peripheral circumference of the work piece. The chuck 23 comprises

four chuck teeth, or jaws, 24 arranged at 90 degree intervals. The teeth 24 are inwardly and outwardly moveable in relation to the aperture so as to grasp and hold a work piece to be machined. The chuck 23 is able to grasp or hold an intermediate portion of the work piece, and apply a rotational force thereto. That is, the chuck 23 is not required to grip an end of the work piece.

Figure 4 shows a rear view of the work head 20 and of the work bed 10 surrounding the work head 20. As can be seen, the work head 20 occupies approximately half of the work bed depth. The rear-most half of the apparatus comprises a second pair of rails 12, arranged in spaced apart relation parallel to the longitudinal axis of the work bed 10. The first 11 and second 12 pairs of rails are transversely offset and run along side each other.

The wheel head 50 is moveably mounted upon the second pair of rails 12 such that the wheel head 50 may be moved along the length of the work bed 10 in order to machine a corresponding portion of the work piece. The work piece is longitudinally stationary during machining, whilst the wheel head 50 moves alongside the work piece.

The wheel head 50 comprises a threaded aperture in a lower region, through which a threaded drive shaft 51 is arranged. The drive shaft 51 is arranged between the second rails 12, parallel to the longitudinal axis of the work bed 10. The drive shaft 51 is driven by an electric motor (not shown) , in order to propel the wheel head 50 along the second rails 12. In order to increase operational safety, a collapsible telescopic cover 52 is arranged to surround the second rails 12 and drive shaft

51. An end of the cover 52 is normally attached to the

wheel head 50 such that movement of the wheel head 50 causes a corresponding extension or collapsement of the cover 52 so as to prevent items becoming trapped under the moving wheel head 50. In use, the wheel head 50 moves alongside the longitudinally stationary work piece in order to machine a corresponding section of the work piece. An outer periphery of the work piece is machined.

As shown in Figures 5 and 6, the wheel head 50 comprises a lower portion 50a which is arranged to move along the second rails 12. The lower portion 50a has a pair of rails 54 formed thereon, upon which an upper portion of the wheel head 50b is moveably mounted. The rails 54 upon the lower portion are arranged parallel to the transverse axis of the work bed 10. The upper portion 50b of the wheel head 50 is moveably mounted to run upon the rails 54 of the lower portion 50a. The upper portion 50b is thus able to move toward, and away from, the work piece. This motion allows a machinery tool such as a grinding wheel to engage and disengage the work piece during use. In order to automate motion of the upper portion 50b, a motor 55 and drive shaft are mounted upon the lower portion 50a of the wheel head 50 and operate in the same way as the motor and drive shaft 51 moving the wheel head 50 along the work bed 10.

The upper portion 50b of the wheel head 50 has rotatably mounted therein, and having an end protruding there-from at either end, a wheel spindle 53. The wheel spindle 53 is mounted between bearings within the wheel head 50. A drive-end of the spindle 53 has mounted thereon a toothed drive wheel which is connected, via a suitable toothed drive belt, to a drive motor 56. The

opposing end of the spindle 53 is suitable for mounting a grinding wheel thereon. In use, the drive motor 56 is arranged to rotate the grinding wheel in an opposed direction to the rotation of the work piece. This opposing rotation serves to increase an abrasive effect upon the work piece.

As shown in Figure 7, the work-bed carriage 30 has detachably mounted thereon the tailstock 40. The work bed carriage 30 has a generally flat upper surface, with raised edges 31 at opposing sides, between which the tailstock 40 locates. The tailstock 40 is secured onto the carriage 30 by means of bolts 41, which are arranged through apertures in a base 44 of the tailstock into corresponding apertures in the carriage 30.

The tailstock 40 comprises a Morse taper bore 42, as is known in the art, into which tapered tooling can be inserted to hold an end of an item to be machined. The taper bore 42 is finely adjustable by a user to accommodate items of different lengths by winding the taper bore 42 in or out of the tailstock 40 along the axis of the work bed 10 using a handwheel 43.

Alternatively, a work piece steady 60 can be attached to the carriage 30 in place of the tailstock 40. The steady 60 is used to support an intermediate region of a work piece around an outer periphery. The steady 60 allows the work piece to extend beyond an end of the work bed 10 opposed to the work head 20, thus allowing the apparatus to machine longer work pieces than the work bed 10.

The tailstock 40 and work piece steady 60 may be alternately or selectively mounted upon the carriage 30 as desired by a user to appropriately support a work piece.

The steady 60 comprises a base 61, which is arranged to engage and rest upon the carriage 30 and locate between the raised edges 31 of the carriage 30. The base 61 has apertures there-through for allowing bolts to secure into the carriage 30. A column 62 extends upwards from the base 61. An aperture 63 is provided in the column, through which the work piece extends in use. The aperture 63 is suitably sized to allow the work piece to project there-though and rotate in use. The column 62 further comprises three turrets 64 arranged around the work piece aperture. An axis of each turret 64 is arranged to intersect the centre of the work piece aperture. Each turret 64 comprises an aperture, arranged axially thereto, within which is arranged an arm 65 which projects into the work piece aperture. The extent that each arm 65 projects into the work piece aperture is adjustable by a user. A handwheel 66 control is provided to extend or retract each arm 65 from the respective turret in the same way as the tailstock 40 bore operates, as will be appreciated by those skilled in the art. The adjustable extension of each arm 65 is provided to accommodate work pieces of different diameters.

An end of each arm 65 has mounted thereon a roller bearing 67. A rotational axis of each bearing 67 is arranged parallel to the rotational axis of the work piece. The roller bearings 67 are provided to contact against a periphery of a work piece, at an intermediate

region thereof, and provide support thereto, whilst allowing the work piece to rotate.

In order to operate the apparatus, a user determines the dimensions of the work piece to be machined. According to the length of the work piece, either the tailstock 40 or steady 60 is suitably chosen by the user and is mounted upon the carriage 30. The position of the carriage along the work bed 10 is then adjusted. For example, if the tailstock is selected then the position of the carriage is adjusted to position the tailstock 40 to engage an end of the work piece. Alternatively, if the work piece is longer than the work bed 10 and the steady is utilised, the carriage 30 may be positioned at an end of the work bed 10 distal from the work head 20 to support the work piece at a maximum distance from the work head 20. The work piece is then loaded into the apparatus from the outer end of the work head 20 through the collar 21. The chuck teeth 23 are then brought to bear against and grip an outer periphery of the work piece. The work piece is further supported by the selected tailstock 30 or steady 60.

The present invention provides a grinding apparatus having an increased flexibility by supporting and rotating work piece at an intermediate region. In this way, the work piece can extend beyond the work head 20. Further, by interchangeably supporting a work piece distal from the work head by either an end of the work piece or an intermediate region of the work piece, work piece length is not limited to a length of the work bed 10.

The present invention provides a machining apparatus for machining an outer periphery of a generally cylindrical work piece. The apparatus is suitable for work pieces of a wide range of lengths and diameters.

Although a few preferred embodiments have been shown and described, it will be appreciated by those skilled in the art that various changes and modifications might be made without departing from the scope of the invention, as defined in the appended claims.

Attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of the foregoing embodiment (s) . The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.