WO1993020974A1

WO1993020974A1 - Pipe cutting machine

Info

Publication number: WO1993020974A1
Application number: PCT/BE1992/000011
Authority: WO
Inventors: Frans Ludo Nuyens
Original assignee: 'ml Construct', Naamloze Vennootschap
Priority date: 1992-04-22
Filing date: 1992-04-22
Publication date: 1993-10-28
Also published as: AU1588392A

Abstract

The machine comprises a support (36, 37) for the pipe (38); means (36 to 43) for rotating said pipe (38); a cutting device (11); a frame (1); a first longitudinal guide (2) fixed on the frame (1); a moving unit (4) reciprocating on said guide (14) and carrying said cutting device (11); a transversal guide (10) mounted on the moving unit (4); a second longitudinal guide (13, 14, 15) mounted on the frame (1) movable parallel to itself with respect to the parallel first longitudinal guide (14); means (19 to 26) for moving said second longitudinal guide (13, 14, 15), said means (19 to 26) comprising a first arm (19) rotatably mounted on the frame (1) around an axis perpendicular to the guides (2; 13, 14, 15; 10) and hingedly with respect to the second longitudinal guide (13, 14, 15) around a hinge axis parallel to said rotation axis and means (26) for rotating the arm (19) with the same rotational speed with which the pipe (38) is rotated; a guided element (16) movable on both the transversal guide (10) and the second longitudinal guide (13, 14, 15); and a second arm (27) hingedly connected to said guided element (16) and to the frame (1) around axes which are parallel to the rotation axis of the first arm (19).

Description

Pipe cutting machine.

The invention relates to a pipe cutting machine for cutting a pipe to be connected to a round element with a greater diameter, said machine comprising a support for said pipe, means for rotating said pipe on the support and a controlled cutting device for cutting said pipe.

Such pipe cutting machines are used because, in order to obtain a perfect junction of the pipe to the element with greater diameter, for example another pipe or a tank, the pi e has to be cut according to a rather complicated path.

In known cutting machines this path is obtained by moving the cutting device by means of a computer controlled meachnism.

Such computerized machines are, however, relatively expensive. They have to be operated by highly qualified operators. The machines are delicate so that transport and use on the building site have to be avoided.

Cutting machines are known wherein the cutting device is mechanically moved by means of a template. Such template complicates the use of the machines.

The aim of the invention is to remediate these drawbacks and to provide a pipe cutting machine which is relatively inexpensive, easy to operate and very robust and which does not require any template.

For this purpose, the pipe cutting machine comprises a frame; a first longitudinal guide fixed on the frame; a moving unit reciprocating on said guide and carrying said cutting device; a transversal guide perpendicular to the longitudinal guide and mounted on the moving unit; a second longitudinal guide movably mounted on the frame and movable parallel to itself with respect to the parallel first longitudinal guide and crossing said transversal guide; means for moving said second longitudinal guide parallel to itself_r said means comprising a first arm rotatably mounted on the frame around a geometrical axis perpendicular to the longitudinal and transversal guides and hingedly with respect to the second longitudinal guide around a hinge axis parallel to said rotation axis and means for rotating the arm around said axis ^"with the same rotational speed with which the pipe is rotated by the rotating means therefor; a guided element movable at the same time on both the transversal guide and the second longitudinal guide; and a second arm hingedly connected to said guided element and to the frame around geometrical hinging axes which are parallel to the rotation axis of the first arm.

In a particular form of embodiment of the invention, the support for the pipe is mounted on the frame so that the axis of the pipe supported by the support is parallel to the longitudinal guides.

In a remarkable form of embodiment of the machine according to the invention, the means for rotating the pipe and the means for rotating the first arm comprise electrical motors which are electronically coupled so that the pipe makes one revolution when the arm makes one revolution. In another embodiment of the machine according to the invention, the second longitudinal guide is guided itself with respect to the frame without possibility to move in its longitudinal direction and the first arm is hingedly connected to a carriage movable on said second longitudinal guide.

Preferably, the second longitudinal guide is fastened to a carriage movable on a second transversal guide fastened to the frame.

In a preferred embodiment of the machine according the invention, the effective length of the first arm is adjustable and/or the effective length of the second arm is adjustable.

Other particularities and advantages of the invention will appear from the following description of a pipe cutting machine according to the invention. This description is only given as example and does not limit the scope of the invention. The reference numerals refer to the accompanying drawings, wherein :

Figure 1 represents a schematical perspective view of a pipe cutting machine according to the invention;

figure 2 is a top view of the pipe cutting machine from figure 1;

figure 3 represents a cross-section according to the line III-III from figure 2, drawn on a larger scale;

figure 4 represents a cross-section according to the line IV-IV from figure 2, drawn on a larger scale; - A -

figure 5 represents a cross-section according to the line V-V from figure 2, drawn on a larger scale;

figure 6 represents a cross-section according to the line VI-VI from figure 2, drawn on a larger scale;

figure 7 represents a cross-section according to the line VII-VII from figure 2, drawn on a larger scale;

figure 8 represents schematically a cross-section of a pipe cut with the pipe cutting machine according to figures 1 to 7 ready to be welded on a mother pipe.

The pipe cutting machine shown in the drawings comprises a frame 1 on two edges of which guide forming rails 2 and 3 are fixedly mounted. Rail 2 extends horizontally in the longitudinal direction, rail 3 horizontally in the transversal direction.

A moving unit 4 is movably mounted on the longitudinal rail 2. Said moving unit 4 comprises two carriages 5 and 6 connected to each other by a bar 7. Both carriages 5 and 6 are of a known type comprising a horizontal body 8 and four wheels 9 rotating around vertical axes, two on each side of the rail 2 or 3 so that any pivoting of the carriage with respect to the single rail 2 or 3 is prevented while the rails 2 and 3 are composed of an aluminium bar and a steel wire incrusted in both edges of the bar.

Carriage 5 carries a transversally extending similar guide rail 10 fixed to the carriage body 8 and extending horizontally in the transverse direction across the frame 1.

The other carriage 6 of the unit 4 carries an oxy-acetylene cutter 11. Another similar carriage 12 is moving on the transversal rail 3 and carries a longitudinal guide composed of two superposed rails 13 and 14 of the above-mentioned kind extending horizontally in the longitudinal direction of the frame 1 and crossing said transversal rail 10, said rails 13 and 14 being held at a distance from each other by a vertical body 15. At the crossing point, a double carriage 16 is guided as well by the transversal rail 10 as by the upper rail 13 of the longitudinal guide 13, 14, 15. The double carriage 16 has a body 17, two pairs of wheels 18 on the under side, one pair rolling on each side of the rail

13 and two pairs of wheels 18 on the upper side, one of said pairs rolling on each side of the transversal rail 10 as shown in detail in figure 4.

A first arm 19 connected to the longitudinal guide 13, 14, 15 is rotatably mounted on the frame 1 around a vertical geometrical axis. The connection to the guide 13, 14, 15 is through the intermediary of a carriage 20, sirάlar to the carriages 5, 6 and 12 and comprising a body 8 and two pairs of wheels 9. Said carriage 20 is rolling on the lower rail

14 and one end of the arm 19, situated under the carriage 20, is pivotably connected to the body 8 by means of a vertical hinge pin 21. The effective length of the arm 19 is adjustable. The arm 19 is therefore part of a toothed bar 22 cooperating with a gear wheel 23 mounted in a holder 24 through which the arm 19 extends, as shown in figure 5.

Said holder 24 is mounted on a vertical shaft 25 of an electrical motor 26 fixed on the frame 1, the axis of said shaft 25 being the rotation axis of the arm 19.

A second arm 27 with adjustable effective length is connected with one end pivotably to the upper side of the body 17 of the double carriage 16 by means of a vertical hinge pin 57 and with the other end pivotably around a vertical axis on the frame 1. This second arm 27 is part of a bar 28 slidably traversing a U-shaped holder 29 but lockable therein in an adjustable position by means of a lid 30 pressed against the holder 29 by means of two bolts 31 screwed in it. By loosening one or both bolts 31, the second arm 27 may be disconnected with respect to the frame 1.

As especially shown in figure 6, the holder 29 itself is rotatably mounted on a leg of an L-shaped support 32 by means of a vertical hinge pin 58 carried by the holder 29 and beared in a bearing 59 fixed on the support 32. The other leg is extending downwardly and its lower end is slidable in a transversally extending guide bar 33 which in turn is slidably mounted in the longitudinal direction on two longitudinal guide bars 34 fixed on the frame 1.

Along its main part, the frame 1 comprises a subframe 35 at the level of the ground. Said subframe bears two horizontal shafts 36 extending parallel to the longitudinal rail 2 and each provided with two rollers 37 for supporting the pipe 38 to be cut. The subframe 35 comprises an adjustable part bearing one of the shafts 36, so that the distance between the two shafts may be adjusted in function of the diameter of the pipe 38.

On one of the shafts 36 a belt wheel 39 is fixed. A drive belt 40 extends around the wheel 39 and a second wheel 41 fixed on the shaft 42 of an electric motor 43 mounted on the frame 1. The motor 43 is electronically coupled with the above mentioned motor 26 by means of a frequency control, in such a way that, when the shaft 25 and consequently the first arm 19 makes one revolution, the pipe 38 carried by the rollers 37 also makes exactly one - 1 -

revolution. When the rotating speed of the pipe 38 is changed, the rotating speed of the arm 19 is automatically also changed. This speed is adjustable by means of a speed control unit which allows the above-described roller support of the pipe to be used as a welding manipulator.

The oxy-acetylene cutter 11 has to be correctly positioned with respect to the pipe 38 so as to cut on the right place. Adjusting in the longitudinal direction of the pipe 38 may be performed by longitudinally moving the pipe 38. Positioning with respect to the surface of the pipe 38 and in height, this is according to the drawings so that the cutter 11 is situated approximately at half the height of the pipe 38 immediately adjacent the outer surface of the pipe 38, is done by moving the cutter 11 with respect to the carriage 6. The cutter 11 is therefore, as shown in detail in figure 7, adjustable in height on a support 44, hanging on one end of a transversal guide bar 45 movably mounted in the transversal direction in a stationary carriage 46 vertically mounted on the above-mentionned carriage 6. The guide bar 45 comprises a part with an L-shaped section and a rail shaped part extending along the first part and held between two pairs of wheels 47 mounted on the body 48 of the carriage 46. The wheels 47 are mounted on the body 48 in such a way that the guide bar 45 is slightly inclined downwardly in the direction of the support 44 so that the bar 45 automatically moves laterally so that the cutter 11 approaches the pipe 38. This lateral movement is limited by means of an abutment bar 60 which hangs on a support plate 61 fixed to one end of the guide bar 45 and having its lower end surrounded by a rotatable tube 78 entering in contact with the pipe 38. This abutment bar 60 is laterally adjustable so as to have the correct distance between the top of the cutter 11 and the outer surface of the pipe 38. Therefore its top end is formed by a threaded stem traversing a transversally extending slot 62 in the plate 61. A knob 63 screwed on this stem presses against the upper side of the plate 61. The cutter 11 is locked at the desired height on the support 44 by means of a screw 49.

The support 44 is not fixedly mounted on the guide bar 45 but is rotatable around a vertical axis in a holder 50 mounted on the end of the guide bar 45. Said axis traverses approximately the top of the cutter 11 and therefore the support 44 is not straight. Above the holder 50, the support 44 carries a gear wheel 51 cooperating with a gear wheel 52 mounted on a vertical shaft 53 rotatably mounted in a second holder 54 mounted on the guide bar 45, adj cent the holder 50. The upper ends of the support 44 and the shaft 53 are traversed by an opening 56. A transversally extending bar 64 enters in one of these openings, normally the opening 56 in the shaft 53. Said bar 64 is pivotably connectec" to another bar 65, extending mainly in the longitudinal direction, by means of a connector 66. The connector 66 comprises two^{^} pivotably connected parts. Each of the bars 64 and 65 traverses one of these parts and is locked to it by means of a screw 67. The bar 65 is pivotably fixed to the frame 1 at a great distance from the connector 66 by means of a pivot 79.

The support 44 is composed of an upper part 68 rotating in the holder 50 and a lower L-shaped part 69, one leg of which carries the cutter 11, the other leg having an open-ring shaped end 70 surrounding the part 68 underneath the holder 50 and clamped on this part 68 by means of a bolt 71 and a nut 72. The lower end of the part 68 is provided with a scale 73. For cutting a pipe 38 which has to be connected to a mother pipe 74, the pipe 38 is put into place on the rolls 37 with its axis in the longitudinal direction. By means of an electronic control unit, not shown in the drawings, the speed of the motor 43 is adjusted so that for one revolution of the pipe 38 the shaft of the motor 26 also makes one revolution. Before starting the motors 26 and 43, the length of. the first arm 19 is adjusted by rotating the gear wheel 23 and thus moving the toothed bar 22 with respect to the holder 24 untill it is equal to the radius of the pipe 38 to be cut. By loosening the bolt 31 and sliding the bar 28 with respect to the holder 29, the effective length of the second arm 27 is adjusted so that it is equal to the radius of the mother pipe 74. The cutter 11 is positioned on the support 44 so that it is situated at half the height of the pipe 38 and the bar 45 is positioned so that the top of the cutter 11 nearly touches the outside of the pipe 38. The moving unit 4 is put in an outmost position whereby both arms 19 and 27 are extending" parallel to the longitudinal direction, with their end connected to a carriage 20 or 16 directed away from the cutter 11, this is directed towards the left in figure 2. All rotation axes of the arms 19 and 27 lie then on the same longitudinal line. The pipe 38 is positioned in its longitudinal direction by moving it axially.

The cutter 11 is ignited. After starting of the motors 26 and 43 the first arm 19 will rotate and thereby reciprocate the longitudinal guide 13, 14, 15 in the transversal direction. The double carriage 16 moves with the guide 13, 14, 15 but as it is connected to the second arm 27 it moves also in the longitudinal direction on the upper rail 13 of the guide 13, 14, 15. The moving carriage 16 takes during its longitudinal displacements the transverse guide rail 10 with it, so that the result of all these movements is a longitudinal movement of the moving unit 4 and consequently of the cutter 11 with respect to the pipe 38.

If the pipe 38 has to be connected symmetrically to the mother pipe 74 the rotating axis of the holder 29 and of the second arm 27 must lie on the theoretical longitudinal line trough the rotating axis of the first arm 19. The support 32 should then be situated on this theoretical line as shown in the drawings.

When the pipe 38 has to be connected offset with respect to the symmetry plane of the mother pipe 74 the rotating axis of the second arm and the support 32 have to be adjusted to lie offset with respect to said theoretical longitudinal line, which can be obtained by moving the support in the transversal direction over the guide bar 33.

If the connector 66 is unlocked from the bar 65, the support 44 will not rotate and the cutter 11 will always be perpendicular to the outer surface of the pipe 38, this means that it will cut according to the lines 75 in figure 8. As can be seen from this figure 8, the cut end of the pipe 38 can only fit to the outer surface of the mother pipe 74 if the direction of the cut or the cutting angle A changes continuously over the circumference of the pipe 38 during one revolution of said pipe. The cutting angle A varies from zero degrees in point 76 and in an opposite point to a maximum in points 77 lying 90 degrees further.

This variation of angle is obtained by oscillating the cutter 11 by means of bars 64 and 65 connected to each other. When the moving unit 4 reciprocates in the longitudinal direction, the cutter 11 not only follows the desired path over the surface of the pipe 38 but it is also oscillated around a vertical axis as the bar 64 also causes a rotation in succesively opposite directions of the gear wheel 52 and the cooperating gear wheel 51. The bevel angle A is thus automatically adjusted during the cutting process.

By inserting the bar 64 through the opening 56 in the upper part 68 of the support 44 instead of through the opening 56 in the shaft 53, the oscillation of the cutter 11 is inversed as the gear wheels 51 and 52 rotate in opposite directions. This permits to cut both ends of a same pipe without the pipe having to be inversed. After cutting one end with the bar 64 connected to the shaft 53, the pipe 38 is displaced axially and the other end is cut with the bar 64 directly connected to the support 44.

In several cases it may be advantageous to deviate from the above-mentioned cutting direction in order to obtain a so-called welding angle B. Seen over the thickness of the pipe wall, the cutting direction always make the same angle B with respect to the tangent plane of the pipe surface. This can be obtained by putting the pipe 38 in the position that its point 76 is opposite the top of the cutter 11, which cutter then normally is radially directed, and by loosening the end 70 of the lower part 69 of the support and relocking this lower part 69 to the upper part 68 after rotation over the angle B. This angle can be read on the scale 73.

The above-described machine can be used to cut the pipe 38 according to a plane perpendicular to its longitudinal axis. Therefore the second arm 27 should be disconnected from the holder 29.

The construction and use of the described machine is very simple. The machine is very robust and practically maintenance-free. The path of the cut is obtained mechanically. No templates nor complicated programming or computer steering are required.

The fact that the pipe is supported on rolls and the use of relatively long arms of adjustable effective length for commanding the movement of the moving unit permit to cut pipes with a great range of diameters.

The present invention is in no way restricted to the form of embodiment described above as example and shown in the drawings , but within the scope of the patent application as defined in claim 1, many changes may be made to this form of embodiment, amongst other things with regard to the shape, the composition, the disposition and the number of the components which are used for it.

Particularly, the moving unit may be guided along both longitudinal edges of the frame. In this case two longitudinal guides are necessary but the carriages of the moving unit may be of a simpler structure.

Both carriages of the moving unit have not necessarily to move on one and the same guide rail. The guide for the moving unit may be comprised of two separate rails which are parallel to each other, one for each carriage.

In order to simplify the positioning of the pipe with respect to the cutter in the longitudinal direction, the carriage carrying the cutter may be adjustable in the longitudingal direction with respect to the other carriage of the moving unit. In this case longitudinal positioning of the pipe may be obtained by adjusting the former carriage without moving the pipe in its longitudinal direction. The first arm has not necessarily to be connected to the second longitudinal guide by the intermediary of a carriage either. It may be connected by a stationary pivot in which case the second longitudinal guide has to be movable along its longitudinal axis. In such a case, two simultaneously rotating arms may be connected to the second longitudinal guide for moving it parallel to itself and said guide then has not to be carried by a carriage moving on a transversal guide. The effective length of both arms should be identical and their rotating axes should lie on a line extending in the longitudinal direction of the frame.

The cutting device has not necessarily to be an oxy-acetylene cutter. It may e.g. be a so-called plasma-torch especially for cutting pipes of stainless steel or a laser-cutter.

This cutting device has not necessarily to be placed adjacent the tube to be cut, at the height of the center, either. This device may be placed anywhere on the circumference and also on top of the tube.

The above-mentioned guiding rails and driving arms have not necessarily to be situated in a horizontal plane. They may e.g. be placed in a vertical plane as well.

The axis of the pipe to be cut has not to be parallel to the longitudinal guiding rails or the moving direction of the moving unit, either. In case the pipe should connect to a mother pipe under an angle different from 90 degrees, the pipe to be cut has to be put under a corresponding angle with respect to said moving direction.

Claims

CLAIMS .

1.- A pipe cutting machine for cutting a pipe (38) to be connected to a round element with a greater diameter, said machine comprising a support (36,37) for said pipe (38); means (36 to 43) for rotating said pipe (38) on the support

(36,37) and a controlled cutting device (11), for cutting said pipe (38) , characterised in that it comprises a frame

(1) ; a first longitudinal guide (2) fixed on the frame

(1) ; a moving unit (4) reciprocating on said guide (14) and carrying said cutting device (11) ; a transversal guide (10) perpendicular to the longitudinal guide (2) and mounted on the moving unit (4); a second longitudinal guide (13,14,15) movably mounted on the frame (1) movable parallel to itself with respect to the parallel first longitudinal guide (14) ; means (19 to 26) for moving said second longitudinal guide

(13,14,15) parallel to itself, said means (19 to 26) comprising a first arm (19) rotatably mounted on the frame

(1) around a geometrical axis perpendicular to the longitudinal and transversal guides (2; 13,14,15; 10) and hingedly with respect to the second longitudinal guide

(13,14 ,15) around a hinge axis parallel to said rotation axis and means (26) for rotating the arm (19) around said axis with the same rotational speed with which the pipe

(38) is rotated by the rotating means (36 to 43) therefor; a guided element (16) movable at the same time on both the transversal guide (10) and the second longitudinal guide

(13,14,15); and a second arm (27) hingedly connected to said guided element (16) and to the frame (1) around geometrical hinging axes which are parallel to the rotation axis of the first arm (19) .

2.- A pipe cutting machine according to claim 1, characterised in that the support (36,37) for the pipe (38) is mounted on the frame (1) so that the axis of the pipe (38) supported by the support (36,37) is parallel to the longitudinal guides (2; 13,14,15).

3.- A pipe cutting machine according to any one of the preceding claims, characterised in that the means (36 to 43) for rotating the pipe (38) and the means (26) for rotating the first arm (19) comprise electrical motors (26 and 43) which are electronically coupled so that the pipe (38) makes one revolution when the arm (19) makes one revolution.

4.- A pipe cutting machine according to any one of the preceding claims, characterised in that the second longitudinal guide is guided itself with respect to the frame (1) without possibility to move in its longitudinal direction and in that the first arm (19) is hingedly connected to a carriage (20) movable on said second longitudinal guide (11,14,15) .

5.- A pipe cutting machine according to the preceding claim, characterised in that the second longitudinal guide (13,14,15) is fastened to a carriage (12) movable on a second transversal guide (3) fastened to the frame (1) .

6.- A pipe cutting machine according to any one of the preceding claims, characterised in that the effective length of the first arm (19) is adjustable.

7.- A pipe cutting machine according to any one of the preceding claims, characterised in that the effective length of the second arm (27) is adjustable.

8.- A pipe cutting machine according to any one of the preceding claims, characterised in that the guided element (16) is a double carriage moving at one level on the transversal guide (10) and at another level on the second longitudinal guide (13,14,15).

9.- A pipe cutting machine according to claims 4 and 8, characterised in that the second longitudinal guide (13,14,15) comprises two guiding elements (13 and 14) at different levels, one (14) for guiding the carriage (20) to which the first arm (19) is connected, the other (13) for guiding the double carriage (16) .

10.- A pipe cutting machine according to any one of the preceding claims, characterised in that the moving unit (4) comprises two carriages (5 and 6) and a connection (7) between them, one of said two carriages (5) being connected to the transversal guide (10) , the other carriage (6) carrying the cutting device (11) .

11.- A pipe cutting machine nccording to any one of the preceding claims, characterised in that the hinged connection (29,30,31) of the second arm (27) to the frame (1) is adjustable in a direction parallel to the transversal guide (10) .

12.- A pipe cutting machine according to claims 7 and 11, characterised in that the second arm (27) is adjustably connected to a structure (32) which is movable on a guide (33) in one direction, which guide (33) is in its turn movable on another guide (34) in a perpendicular direction.

13.- A pipe cutting machine according to any one of the preceding claims, characterised in that the second arm (27) is disconnectable from the frame (1) .

14.- A pipe cutting machine according to any one of the preceding claims, characterised in that the cutting device (11) is an oxy-acetylene cutter.

15.- A pipe cutting machine according to any one of the preceding claims, characterised in that the cutting device (11) is adjustably mounted as well in the transversal direction as in the height with respect to the moving unit (4).

16.- A pipe cutting machine according to the preceding claim, characterised in that the cutting device (11) is adjustable in the vertical direction on a support (44) , which support is mounted on a transversal guide (45) which is movable in the transversal direction in a bearing (46) mounted on the moving unit (4) .

17.- A pipe cutting machine according to the preceding claip., characterised in that the bearing (46) causes a downward inclination of the transversal guide (45) so that due to gravity said guide (45) moves in the direction of its lower end, an adjustable abutment (60) being mounted on the transversal guide (45) .

18.- A pipe cutting machine according to any one of the preceding claims, characterised in that the cutting device (11) is rotatably mounted on the moving unit (4) around an axis parallel to the rotating axis of the first arm (19) .

19.- A pipe cutting machine according to the preceding claim, characterised in that the cutting device (11) is mounted on a support (44) which is rotatably mounted in a holder (50) mounted on the moving unit (4) , the support (44) being connected to the frame (1) by means of a connection (51,52,64,65,66,79), said connection causing an oscillation of the support (44) and the cutting device (11) mounted thereon when the moving unit (4) reciprocates.

20.- A pipe cutting machine according to the preceding claim, characterised in that the connection (51,52,64,65,66,79) comprises a first bar (64) extending along the transversal guide (45) and connected to the support (44) , a second bar (65) extending along the longitudinal guide (2) for the moving unit (4) and a connector (66) pivotably and adjustably connecting both bars (64 and 65) .

21. A pipe cutting machine according to the preceding claim, characterised in that the connection (51,52,64,65,66,79) also comprises a gear wheel (51) mounted on the support (44) , a gear wheel (52) cooperating with gear wheel (51) , mounted on a shaft (53) extending parallel to the rotating axis of the support (44) and born in a holder (54) mounted on the transversal guide (45) , the first bar (64) being releasably connected to one of the elements constituted by the support (44) or the cooperating shaft (53).

22.- A pipe cutting machine according to any one of claims 17 to 20_r characterised in that the support (44) comprises an upper part (68) and a lower part (69) which is adjustable around the rotation axis of the upper part (68) .