US2282508A - Method for butt-welding pipes and tubing - Google Patents

Description

May 12, 1942. J.. L ANDERSON 2,282,503

METHOD EQR. BUTT-WELDING PIPES AND TUBING Filed. Jan. 27,, 1940- 5 Sheets-Sheet 1 ATTORNEY y 1942- J. L. ANDERSON 2,282,508 f METHOD FOR BUTT-WEDDING PIPES AND TUBING Filed Jan. 27, 1940 5 Sheets-Sheet 2- lNVEN-TOR May .12, 1942. J. L. ANDERSON METHOD FOR BUTT-WELDING PIPES AND TUBING Fild Jan. 27, 1940 5 Sheets-Sheet s ATTORNEY EMS INVENTOR y 1942- J. 1.. ANDERSON 2,282,508

METHOD FOR BUTT-WELDING PIPES AND TUBING Filed Jan. 27, 1940 Sheets-Sheet 4 INVENTOR May 12, 1942. J. 1.. ANDERSON I METHOD FOR BUTT-WELDING PIPES TUBING 1 Filed Jarif27} 1940 5 Sheets-Sheet 5 INVENTOR' BY f 7 ATTORNEY Patented ay- 12, 3942 mrrnon' roa nu'r'r-wammc. rims AND 'runmo James L. Anderson, Clcste'r, N. 1., assignor to Air Reduction Company, Incorporated, New York, N. -Y., a corporation of New York Application January 21, 1940, Serial No. 315,931

(on. iii-=90 9 Claims.

This inventionrelates to methods for'buttwelding the ends of pipes or tubes.

One object of the invention is to provide an improved method for butt-welding the ends of pipes and tubes by flames applied directly to the separated end faces of the tubes. When welding in accordance with the method of this invention the end faces to be joined are exposed to directflame heating while spaced more closely than has heretofore been the practice, and the flames are directed against the ends in a manner to heat both ends substantially uniformly while they are moving together and until they are in actual contact.

Another object of the invention is to maintain the pipe or tube ends symmetrical with respect to the heating means during the heating period, during the time that the ends are moving together, and after the faces are in contact. This symmetry is-obtained'in thepreferred embodiment of the invention by moving both tubes at the same rate with respect to a relatively fixed heating system.- The same result can be ob tained, however, by moving only one of the tubes but also moving the heating system in the same direction at one-half the speed.

Among the advantages of this invention is the fact that the end faces to be welded can be brought together slowly and without spatter of molten metal. It is not necessary that the tubes be forced together with a hammer blow in order to make the weld as in some methods of the prior art.

Another advantage of the symmetrical relation of the heating system and the tube ends is that heating flames can be used after the weld is made to play on the seam for smoothing any flash or reinforcement at the weld.

The tube ends are preferably heated without rotating them. This is advantageous when the circumferential seam to be welded is between sections having curves or semicircular bends, or

one section is secured in place and cannot be moved. In such cases it is often impossible to rotate the tubes in av welding machine. The heating may be done with a special torch such as shown in my copendin'g application Serial No. 33,549, filed July 2'7, 1935, (Patent No. 2,196,180, dated April 9, 1940), of which this application is a continuation in part. 1

It is another feature of the invention that the heat is applied to the pipe ends by oscillating a system of heating flames back and forth along the circular extent of said faces in such a manner thatthe stopping and reversing at the end of eachoscillation is not always at the same place. In this way the development of hot spots on the end faces-is avoided.

Other objects, features and advantages of the invention will appear or be pointed out as the specification proceeds. 1 p

In the accompanying drawings, forming part hereof:

Fig. 1 is a side elevation of a machine for weld ing in accordance with the method of this invention;

Fig.'2 is a sectional view on the line 2-2 of Fig. 3;

Fig. 3 is a top plan view of the machine shown in Figs. 1 and 2;

Fig. 4 is asectional view on the line 4-4 of Figs. 1 and 3;

.Fig. 5 is an enlarged end view of. the torch shown in Figs. 3 and 4;

- Fig. '6 is a side view of the'torch illustrated in Fig.5, with a part of the torch shown in section along the line 8-8;

Figs. 7 and 8 are sectional views on the linesand 8-8 of Figs. 6 and 5, respectively:

Fig. 9 is a development along the circle 'of the jet orifices of a portion of the torch;

Fig. 10 is an enlarged side elevation of the motor and mechanism for oscillating the torch arm; and

Fig. 11 is a sectional view on the line Il -l I of I Fig. 10.

Two sections of tubing l0 and II which are to be welded together are held in chucks l3 and II,

respectively. These chucks are supported on frames l6 and I1 secured to a common base l8. The chucks have a limited movement in their supporting frames for bringing the ends of the tubes together to 'make a weld. By having both chucks movable and shifting them at the same time, the opposing end faces of the pipes can be maintained in a symmetrical relation to the heating flames, with consequent equal intensity of heating on both faces as they are brought to gether.

' A bracket 20 connected to the base 18 supports v a torch for heating the ends of the tubes l0 and II. This torch-holder and its operating mechanism will be described more fully in the explanation of Fig. 4. Y

The frame I! carries a fixed support 22 (Fig. 2) and a movable support 23. .I'hechuck It has a jaw 24 connected to the fixed support 22 by a dovetail bearing which permits movement of the law 24 lengthwise of the tubes. Antifriction and thereby avoid spatter or flash.

bearings 26 retained by the jaw 24 bear against the face of the fixed support.

The jaw 24 is moved by a pinion 26 which meshes with a rack 29 fixed to the jaw 24. The pinion 28 is driven from a shaft 38 through bevel gears 3|.

The chuck M has a jaw 34 connected to the movable support 23 by a dovetail bearing andmovable lengthwise of the tubes by rack and pinion mechanism which is driven from a bevel gear 36 on the shaft 38. bevel gear 36 turns in a bearing 31 carried by a bracket 38 depending from the movable support 23. The gear 36 slides axially on a splined portion of the shaft 38 when the movable support 23 slides lengthwise of the shaft and normal to the axis of the tubing to open or close the jaws of the chuck l4.

The chuck I4 is opened and closed. and is held closed under pressure, by a hydraulic motor 48 of the-cylinder and piston type. This motor is supported on bracket extensions of the frame l1, and is cozinected to the movable support 23 by a piston rod 2.

blocks and 52 together, and movement toward the left separates them.

The construction of the chuck l4 (Fig. 1) is similar to that of the chuck l3 already described, and the jaws are moved by similar mechanism which is indicated by the same reference characters.

The shafts 38 are turned by cranks 44 to move the chucks l3 and I4 toward each other to bring the ends of the tubes l8 and II together to make a weld. Each of the cranks 44 is connected by a link 45 to the piston rod 46 of a cylinder and piston hydraulic motor 41. The speed of these hydraulic motors can be controlled to move the ends of the tubes toward each other gradually A work-limit gauge 49 is hinged to the chuck l3 and is moved into the dotted-line position shown in Fig. 1 before the tubes are gripped by the chucks. Each tube is pushed through its chuck until the end of the tube abuts against the worklimit gauge 49. The chuck jaws are then clamped against the tubes, the ends of which are in correct position to be heated by the torch. After the tubes are gripped by the chucks, the gauge 49 is turned back into the full-line position shown in Fig. 1.

v The torch for heating the ends of the tubes is made in two sections which flt together to completely surround the tubes. The tip or burner portion of the torch comprises a right burner block 5| and a left burner block 52. The burner block 5| is connected with a stock 53 held in a clamp 54 on a slide 55. This slide 55 is supported for lateral movement in a dovetail bearing 56 (Fig. l) by a frame 51.

Referring again to Figs. 3 and 4, the burner block 52 has a stock clamped to a slide 68 which is supported by and movable laterally on the frame 51. The slides 55 and 68 are moved toward and from one another to separate the burner blocks 5| and 52 when tubes are to be placed in the machine, and to move the blocks into contact after the ends of the tubes are in position to be heated and the limit gauge 49 has been withdrawn.

The slides 55 and 68 are moved by means of a handle 62 at one end of a lever 63 which is fulcrumed intermediate its ends to a bracket 64 extending from the frame 51. The slide 55 is connected with the lower end of the lever 63 by a link 66, and the slide 68 is connected with the lever 63, above its fulcrum, by a link 61. Movement of the handle 62 toward the right brings the burner The frame 51 is supported by the bracket 28 (Figs. 1 and 3) on an arcuate undercut. bearing 69 on which the frame is free to oscillate about the axis of the tubes as a center. ing movement is imparted to the frame 51 by a motor 18 which drives a crank 1| through reduction gearing 12. The crank 1| has a pin working in a slot 13 of an arm 15 rigidly connected with the frame 51. The speed'of themotor 18 is regulated by a governor 16.

Figs. 5-9 show the construction of the torch. The inner face of the torch is recessed to form a chamber 18 which surrounds the tubes adjacent I the ends to be welded. The flame jets issue from the sloping side walls of the chamber 18. A number of jet orifices 88 at spaced points around the torch slope in a direction to direct flame jets against the end of the tube -|8, as illustrated in confine and guide the products of combustion and those gases moving across the surface of the tubing back of the end heat the metal adjacent the end, reducing the heat lost from the end face by conduction. Up to the time that the ends of the tubes l8 and H move into contact, a portion of the envelope gas from the torches enters the tubes. This is advantageous because it heats the inside of the tubes and the reducing action of the envelope gases protects the ends and inner surfaces from oxidation. 8

Jet orifices 84 (Fig. 8) open through the other sloping wall of the chamber 18 and direct flame jets against the end of the tube Grooves 15 in front of the jet orifices 84 provide exhaust conduits for the envelope gases. Air forthe combustion of the envelope gases is entrained through air ducts" 86 (Fig. 9) on both sides of each jet Oxygen and fuel gas are supplied to the burner block 5| from the flces 88 open into a gas chamber 88, and the orifices 84 into a gas chamber 89. The gas chambers are grooves, in the outer faces of the torch block closed by plates 98. These gas chambers 88 and 89 are connected by a cross conduit 9| which communicateswith the gas conduit through the torch stock 53. The construction of the other torch block is similar and its description unnecessary except to point out that the upper torch block 5| has a groove into which a tongue93 extends to hold the two sections of the torch in perfect alinement. The gas chambers of the two sections of torch are independent.

The burner blocks 5| and 52 and the upper portions of the torch stocks are water cooled. Cooling passages 95 in the burner blocks are supplied with water from pipes 96. The water outlet connection has a pipe 98 connecting with a water-jacket 99 around the stock of the torch.

Figs. 10 and 11 show in detail the mechanism for oscillating the arm 15. The motor 18 is mounted on a support 8| that extends horizontally from the motor 18 toward the stationary bracket 28 and connects with a vertically. extending slide I82 that moves in dovetail guide mem- Such oscillatstock 53 (Fig. 6). The orithe crank H meshes with a rack I on the stationary bracket 20. When the motor 1.0 is rotat- When the motor 10 is moved upward the throw of the crank Ii produces a greater angular movement of the arm 10 because the crank is closer to the axis of oscillation of the arm 10. The reversing of the direction of rotation of'the motor 10 reverses the direction of movement of the crank II. This combination of movements causes the oscillations of the arm 15, and the torches that are moved by the arm, to stop at different angular positions on successive oscillations. This produces a more even distribution of the heat and prevents the overheating of certain points on the pipe ends such as is liable to occur when the oscillations of the flames always stop and start back at the same point. a With the apparatus illustrated, the method of this invention is carried out as follows:

I With the burner blocks of the torch moved apart and the limit gauge 49 in the dotted-line position shown in Fig. 1, the tubes l0 and II are put in the chucks l3 and, respectively, and pushed into contact with the limit gauge 49. The motors 40 are operated to close the chucks and firmly clamp the tubes. The limit gauge 49 is then turned back into th full-line position to get it out of the way of the torch, and the handle 62 is moved to the right in Fig. 4 to bring the torch blocks 5! and 52 together around the ends of the tubes. The friction of the slides and operating mechanism is suflicient to hold the torch blocks together, but releasable latching or locking means can be provided for holding the torch sections together.

While the burner blocks direct flame jets against the ends of the tubes, the motor is operated to rock the frame 01 through diflerent angular distances on successive oscillations as already explained. These movements of the ,torch distribute the flame heating substantially uniformly over the entire areas of the end faces to be welded. The oscillation is limited so as to avoid twisting of the hose through which gas is supplied to the torch, but the angular movement is preferably not less than one-half the angular spacing of the heating flames. If the tubes are of a shape that can be rotated or oscillated, the invention can be carried out with stationary heating means and angularly movable tube supports.

In addition to the heating which each circle of flame jets produces in the tube against which it is directed, the end of the other tube is heated by radiation from these flames. The loss of heat from the end faces by conduction through the metal of the tubing is reduced by the envelope gases which flow across both the inside and outside surfaces of the tubing and heat the metal back from the end faces.

The torch is allowed to heat the ends of the tubes for a definite period of time, depending upon the type of weld to be produced. The direct flame heating within a partially closed space permits a positive control of the heating so that timing of the operation is practical. Oxygen in excess of that'required for the primary combustion of the acetylene may be employed to increase the heating effect of the torch in con-- trolling the torch operation. ,While this heating with oxy-fuel gas flames. and particularly oxyacetylene flames. is a feature of the invention, it should be understood that the method can be performed with ordinary torches. that do not form an enclosure. It should be understood also that some features of the invention can be used with torches that have their flame jets directed into the space between the confronting faces that are to be welded, but not toward either face. such as the flsh tail" flames of U. S. Patent 2,031,583 (Fig. 9) or German Patent 402,400

- (August 15, 1924), though the flames will, of

has been described but various changes and mod-.-

course, be disposed around a circle for pine end welding.

After the ends of the tubes have been heated for a definite length of time, depending on the type of weld desired. the motors 41 are operated to move the chucks l3 and I I toward one another and bring the ends of the tubes into contact. The motors 41 can be made to operate at any desired speed, but one of the features of the invention is that these motors can be controlled to move the tube ends into contact slowly enough to avoid spatter or splash of metal when the end faces of the pipes are coated with fused metal.

The tube ends are subject to additional heating and are enveloped by the products of combustion during all of the time that the chucks are moving the tubes together. This heating period must be taken into account in determining how long a heating period to allow before starting the motors B1.

The strongest welds are made when the tube ends are brought to a state of fusion. The heating must be performed quickly so that the faces are not heated deeply enough to flow and any fused coating is thin and adheres to the solid metal behind it so that the end faces are selfsustaining.

If a shorter heating period is used the end faces may be partially fused, that is, some parts of the faces will be melted and other areas ofthe faces may be still plastic or solid. With-fur.- ther reduction in the heating time there is no fusion of the faces.

The heating time must be chosen according to the kind of weld desired, whether it is to be a weld between fused faces, or a weld made by bringing plastic surfaces together under pressure. The tubes are brought together by the motors 41 with at least as much pressure as is necessary to eflect a weld.

The preferred embodiment of the invention iflcations can be made, and some features can be. used without others without departing from the invention as defined in'the claims.

- I'claim:

l. The method of welding together the ends of tubes which comprises holding the tubes stationary with their end faces spaced apart but confronting-one another, heating the end faces simultaneously by heating flames projected directly against the surfaces of the end faces around their circumferences, moving the tubes toward one another, heating both end faces substantially equally during the time that they are coming together, pressing the end faces of the tubes into contact with one another to weld them together, and continuing to project heating flames against the tubes after the end faces are in contact to smooth any molten metal. squeezed out from between the faces.

2. In the welding together of tube ends by projecting heating flames directly against the end faces of the tubes while they are separated and then bringing the tube ends together when they 3. The method of butt-welding the ends of tubes which comprises projecting heating flames against the end faces of the tubes with said end faces separated and symmetrical with respect to the heating flames, producing relative movement of the tubes to bring said end faces into contact, and maintaining said symmetrical relation until the end faces are in contact with one an- -other.

4. Amethod of butt-welding the ends of tubes which method is similar to that described in claim 3 but with the end faces heated by flames directed into the space between the separated end faces.

5. The method of butt-welding tube endswhich comprises projecting heating flames at an angle to the confronting end faces of the tubes and-directly against said confrontingend faces with said faces spaced from one another and with the heating flames distributed at angularly spaced points around the end faces, distributing the heat over the end faces by producing relative oscillatory movement of the heating flamesand tube ends about the' axis of the tube ends and back and forth through an angle at least as great as one-half the angular spacing of the heating flames that play against each end face. Y

6. The method of welding together sections of tubing, which comprises positioning the sections with their end faces in confronting relation but spaced apart, heating the end faces for welding by applying to each of the edge faces a system of high-temperature flames at angularly spaced regions around the faces, oscillating the flame systems angularly back and forth about the axis of the tube sections, preventing the occurrence of hot spots by causing successive oscillations of the flame systems to stop and reverse at different points, and bringing the heated end faces together to make a weld.

7. A method of welding similar to that described in claim 6 but with the end faces heated by flames directed into the space between the separated end faces.

8. The method of welding together sections of tubing which comprises heating the end faces of said sections while confronting but separated, applying the heat by projecting separate systems of flame jets directly against the respective faces, partially enclosing both systems of flame jets, confining and guiding the products of combustion from the flame jets to cause them to pass across the surfaces of the end portions of the tubing sections, and bringing the heated end faces into contact to make a weld.

9. The method of tube welding which com prises maintaining the tubes with their end faces in spaced opposition, projecting flame jets directly against the end faces at angularly spaced points around the circumference of the end faces and projecting alternate flame jets against different end faces, partially enclosing the flame jets, admitting air for combustion'of each flame jet from behind and to the side of that jet and opposite in direction to the products of combustion of the next adjacent jets on either side,

and confining and guiding the products of combustion' across the outside surface of the end 'portion of the tube against which that flame jet is projected.

. JAMES L. ANDERSON.

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