US3256592A

US3256592A - Continuous tube forming and galvanizing

Info

Publication number: US3256592A
Application number: US337948A
Authority: US
Inventors: Theodore H Krengel; Wilk Emil
Original assignee: Allied Tube and Conduit Corp
Current assignee: Allied Tube and Conduit Corp
Priority date: 1964-01-15
Filing date: 1964-01-15
Publication date: 1966-06-21
Anticipated expiration: 1983-06-21

Description

June 21, 1966 T, H. KRENGEL ETAL 3,256,592

CONTINUOUS TUBE FORMING AND GALVANIZING ODMQWMM ATT'Ys June 21, 1966 T. H. KRENGEL r-:TAL 3,256,592

CONTINUOUS TUBE FORMING AND GALVANIZING 2 Sheets-Sheet 2 Filed Jan. 15, 1964 INVENTORS 'THEODORE H KRENGEL cmd EM-LL WILK 0 M7 'l ATTYs United States Patent O 3,256,592 CONTINUGUS TUBE FORMING AND GALVANIZING Theodore H. Krengel, Chicago, and Emil Wilk, Park Forest, lll., assignors to Allied Tube & Conduit Corporation, Harvey, lll., a corporation of Illinois Filed Jan. 15, 1964, Ser. No. 337,948 3 Claims. (Cl. 29-200) This invention relates to a continuous process for forming and galvanizing tubing of endless strips of steel and it relates more particularly to the processing of endless strips of steel to form tubing'in a continuous operation and in the treatment of the external surfaces of the formed tubing for galvanizing as a continuous operation in combination with tubing formation.

This is a continuation-in-part of application Ser. No. 106,699, filed May 1, 1961, entitled Continuous Tube Forming and Galvanizing, now U.S. Patent No. 3,122,- 114, issued February 18, 1964.

It is an object of this invention to provide a new and improved process for the continuous forming of tubing from endless lengths of strip steel and for continuous galvanizing of the formed tubing as a continuous operation with the formation of the tubing and it is a related object to produce a new and improved machine for use in the practice of same.

Another object is to provide a machine and process for the continuous forming and galvanizing Iof tubing from sheet steel in a simple and efiicient manner to produce a galvanized tubing at less cost from the standpoint of labor, from the standpoint of material utilization and cost, from the standpoint of space requirements, and from the standpoint of heat and power requirements, and it is a related object-to produce and to provide a method for producing galvanized tubing having improved characteristics and appearance without substantial variation in such characteristics and appearance between lengths.

These and other objects and advantages of this invention will hereinafter appear and, for purposes of illustration, but not of limitation, an embodiment of the `invention is shown in the accompanying drawings in which:

FIG. 1 is a schematic flow diagram of the continuous forming and galvanizing of tubing in accordance with the practice of this invention;

FIG. 2 is a sectional elevationalview of the furnace for the continuous galvanizing ofthe formed tubing in accordance with the practice of this invention;

FIG. 3 is a sectional View taken substantially along the line 3-'3 of FIG. 2;

FIG. 4 is a sectional elevational view taken substantially along the line 4-4 of FIG. 3;

FIG. 5 is a sectional view taken substantially along the line 5 5 of FIG. l;

FIG. 6 is a sectional view taken substantially along the line 6 6 of FIG. l; and

FIG. 7 is a schematic elevational view of a fragmentary portion of the tube forming apparatus illustrating the arrangement of elements for welding the tubing.

Since the important concepts of this invention reside in the method and means for the continuous forming and galvanizing of tubing by the processing of endless lengths and strip steel, the invention will be described with .reference to a continuous process for forming the metal tubing and in the processing of the formed tubing in a galvanizing, sizing and shearing operation for cutting the nished tubing into desirable lengths.

Referrring now to FIG. 1 of the drawings, the tubing forming mill is fed with strip steel 10 supplied in the form of coils 12 mounted on a pay-out reel 14 for free rotationl azaasaa Patented June 2l, 1966 al movement to pay out strip steel as it is required by the continuous tube forming mill. In a continuous mill for forming tubing, the strip steel is processed substantially continuously at a relatively constant rate through the mill. Advancement is effected primarily by engagement between the strip steel and the forming and sizing rolls rotating at relatively constant speed whereby the strip steel is drawn into the mill for processing.

Since the lengths of the steel strip in the coils 12 come to an end after a short period of operation of the mill and since strip is taken up continuously by the mill in its continuous operation, it is essential to provide mean-s for splicing the end of one coil 16 with the leading end 18 of another lcoil for joinder of the strips into continuous lengths without stoppage of the mill in its continuous operation. For this purpose, a loop 20 is taken in the rstrip of steel dimensioned to have a length sufficient continuously to feed strip to the mill while the trailing end 16 of the strip is stationarily held for splicing, as by Welding, onto the leading edge of the new reel which has been displaced into position of use. The loop is formed by feeding the strip 10 under the roller 22 and over the roller 24 to about the roller 26 and back over the roller 28 and under the roller 30 into the mill. The rollers are each mounted for free rotational movement while the roller 26 is carried by a carriage 32 having wheels 34 rotatably positioned upon a track 36 for endwise displacement of the carriage in one direction to make strip available to the mill and in the other direction, responsive to the actuation Iof the winch 38 through the cable 40, to return the carriage and to reform the loop.

Normally, the carriage is in its retracted position to provide a full loop 20 of strip steel which rests upon a platform 42 overlying the mill and underlying the track. When the end is reached, a portion adjacent the end is l-ocked in a clamping member 44 to hold the end section while the end 16 of the coil is joined, as by welding, to the beginning of the next coil in the joiner 46. The operation takes but a few seconds. In the meantime, the mill continues to draw its requirements of strip from the loop to displace the carriage 32 in the direction away from the winch as the loop is shortened. When the ends of the coils have been joined, the clamping device 44 is inactivated to free the strip whereby strip can thereafter be supplied from the new coil as the winch 38 and cable 40 are effective to return the carriage to normal retracted position and replenish the loop in preparation for the next splicing operation. It will be apparent that the strip 10 feeds from the coil through the loop to the mill for continuous operation.

Hereafter description will be made of the sequence of operations effected in the mill with the elements in the mill longitudinally aligned for the passage of strip and the tubing formed thereof continuously linearly therethrough. In the preferred prac-tice, the strip 10 is dimensioned to be slightly greater in width than is required to form the tubing so that an edge can be made available from each side to be shaved therefrom in sizing the strip and to provide freshly cut metal in the meeting edges forming the seam thereby t-o enhance joinder as by a continuous welding operation to'form the closed tubing. From the edge shaver 45 the strip is advanced to wiper 47, such for example as a pad, which sweeps or otherwise removes chips or other pieces of metal released from the shaving operation. This operation has not heretofore been employed in the continuous formation of galvanized thin Wall tubing, yetfailure to remove such metal particles from the surface of the metal strip has been found to leave the metal particles where they can become bonded to the surface during subsequent processing steps, such as heating, welding, galvanizing and the like, to constitute an obstruction in the interior of the formed tubing and to provide undesirable surface roughness. Instead of a wiper pad, the loose particles can be removed by a blow-off jet, etc. From the cleaning stage 47, the strip enters a series of aligned conventional tube forming rolls, identified by the numeral 48, whereby the strip is deformed from a flat section to a rounded tubing having the freshly cut edges of the strip in abutting relation to form the seam of the tubing.

From the tubing forming roll section 48, the `formed tubing is advanced directly to the seam Welder 50 where the abu-tting free edges of the strip formed to tubular shape are joined by Welding, preferably using a continuous resistance Welder in order to keep the upset on the inside of the formed tubing at a minimum. Otherwise, it would require the use of a support within the tubing and/ or an upset removing tool employed in combination with a water suction device. Since sufficient space is not available in small diameter tubing for housing such support, upset removal tool and water suction means, it has been found t-o be expedient, in accordance with the practice of this invention, to make use of a continuous Welder in the form of a roller adjusted to effect the major upset on the outside of the tubing where access is available for removal.

It has been conventional practice to apply cooling water to the entry end of the welding operation for purposes of cooling the electrode. However, it has been found that the application of cooling water before the seam has been closed enables water to gain access to the interior of the formed tubing, where, in the continuous tube forming and galvanizing process described and claimed by applicants, it can raise numerous problems, as by vaporization of the water at the high temperatures to which the tubing is exposed during the subsequent galvanizing operations. As a result, as a further irnprovement in the process of continuous forming and galvanizing of thin wall tubing, the coolant is applied directly onto the cylindrical welding electrode in the portion immediately after it leaves the surface of the tubing, or the nine oclock position, so that by the time that the wetted portion travels around to again come into Welding engagement with the oncoming tubing, it has had time to dry from the applied cooling medium. Thus the coolant is applied onto the electrode aligned with the trailing portion of the welding operation wherein the same has already been closed and water is incapable of finding its way into the formed tubing. Cooling of the electrode remains efficient even with the described transformation.

When, as in the practice of this invention, the upset is concentrated on the outside, the upset or flash can be removed by a `seam shaving tool 52 which follows immediately after the seam Welder. The seam shaver embodies a scarng tool which shaves the seam to leave a smooth surface on the outer periphery of the formed tubing and whereby the seam would be concealed except for the presence of a heat line indicated by a dark discoloration of metal oxide formed along the weld surface.

By way of a still further improvement in the means and 4method for the continuous forming of galvanized thin wall tubing, it has been found to be desirable to quench the hot surface of the tubing immediately after the scarfing operation to minimize oxidation of the freshly cut and hot surface. For this purpose, cold water is applied t-o the surface of the tubing 53 immediately after the scarfing operation with the result that a heat treating effect to produce a blue coloration indicative of a metallic surface free of oxidation is secured, as distinguished from an otherwise formed brownish discoloration on the freshly cut surface, indicative of oxide formation. This minimum film secured by water cooling of the freshly cut hot -metal surface can be easily removed by the subsequent cleaning fiuids whereas the otherwise formed oxide film is incapable of removal sufficiently cleanly to permit the formation of a desired zinc coating during the subsequent galvanizing step.

To this point, welded tubing is continuously formed of strip steel with the exception of the possible short lengths of formed tubing which remain with an open seam in the event of skidding of the tubing and the machine when Ithe mill is stopped for one reason or another. As a result, in the described continuous processing for forming tubing, an auxiliary Welder 54 in the form of a heliarc Welder may be employed, Where desired, to take over the welding operation whenever the seam Welder fails to weld the seam of the formed tubing. When employed, an overlap is effected with the stop and start of the mill continuously to weld the seam and to insure closure of the seam' throughout the length of the tubing. In actual practice with good controls, it has been found that the heliarc Welder is not essential.

After the tubing has been welded to provide a continuous weld throughout the length thereof, the tubing is advanced from the Welders to elements linearly aligned therewith for washing and pickling the outer surfaces of the formed tubing in preparation for continuous galvanizing. The welded tubing 56 is advanced first into a housing 58 having a removable cover 60 for access thereto. The housing is provided with a plurality of axially aligned ring members 62 in the form of headers having a plurality of spray nozzles 64 arranged equally spaced about the inner periphery for directing a spray 66 onto the outer periphery of the tubing 56 advanced axially therebetween. Each spray head is connected to a reservoir 68 of Wash water for recirculating the wash water from the reservoir through pipe 70 to the spray head 62 and from the drain in the housing back through pipe 72 for return to the reservoir. In the illustrated modification the reservoir is shown alongside the housing but it may equally be arranged in other positons such as beneath the housing. A pump means is interposed between the reservoir and the spray heads for displacement of wash water forcibly to spray the wash water onto the exposed surfaces of the tubing as it passes through the housing. For purposes of washing to remove grease and the like, use can be made of an alkali wash which may be represented by a solution of 5 ounces of alkali per gallon of Water and it is preferred to heat the wash water to a temperature below the boiling point of the alkali solution, such as to a temperature of 200 F. to accelerate removal of grease from the surface.

From the hot alkali wash, the tubing 56 is advanced continuously into the adjacent section of housing 74 in which the tubing is treated with a dilute alkali Wash. The housing 74 is similar to that of the housing 58 for the hot alkali wash including spray heads to direct the dilute alkali wash onto the periphery of the tubing and with a separate reservoir 76 connected to the headers to feed dilute alkali from the reservoir to the headers and connected to the drain in the base of the housing for returning the dilute alkali wash from the housing back to the reservoir. The dilute alkali wash is employed for more complete removal of grease and dirt from the surface of the tubing and the use of the dilute alkali wash following immediately after the strong alkali wash operates to save alkali loss since strong alkali carried on the surface of the tubing from the strong alkali wash will be recovered in the wash with dilute alkali to supply some of the alkali for maintaining the desirable concentration thereof. The dilute alkali wash'may be formulated to contain about 2 ounces of alkali per gallon and it may also be heated to an elevated temperature such as to a temperature below boiling, or up to 200 F. more effectively to remove grease and other undesirable material from the surface of the welded tubing.

From the alkali washes the tubing is advanced into a rinse housing 78 aligned endwise with the alkali wash housing and similarly constructed. The rinse housing is fitted with a number of axially aligned spray heads,

similar to the rings employed in the alkali wash systems, from which rinse water is sprayed onto the surface of the tubing as it passes therethrough to rinse remaining alkali from the surface before passing the tubing into the pickling bath. The .rinse water is circulated under pressure from a water supply source to the spray heads and the water collected in the bottom of the rinse housing can be released to the drain unless water is at a premium, in which event the water is recirculated with suicient makeup water to provide for substantial removal of alkali. The rinse water may be used either cold or warm, but is economically undesirable to invest in warming the water unless the warm water is recirculated between the housing and a water storage reservoir for re-use.

From the rinse', the tubing 56 is advanced directly into a pickling housing 80 of similar construction as the wash and rinse housings and separated therefrom only by a separating wall 82. The pickling housing is provided with a pair of longitudinally arranged, laterally spaced apart spray pipes 84 arranged in the upper portion of the housing to overlie the tubing 56 which passes linearly through an intermediate portion of the housing beneath the spray pipes to face the weld seam in the direction of the pipes. The pipes are each provided with a plurality of spray nozzles 86 in the underside positioned to direct the spray 88 angularly downwardly to converge on the weld seam positioned uppermost in the tubing passing therethrough. Thus the spray is directed forcefully from the spray nozzles onto the seam to react with the oxides on the surface which are formed at the weld. Use can be made of conventional pickling solutions for removal of the metal oxide, such for example as an acid solution containing about 30 percent by volume HC1 dissolved in aquey ous medium. For best results, it is desirable to make use of a pickling solution heated to an elevated temperature such as at a temperature of 100-120 F., but a heated pickling solution is not essential.

The solution is stored in a suitable reservoir 90 and is connected with the spray heads through lines 92 and 94 and circulation is effected by means of a displacement pump. The reservoir, pump and housing are all provided with a rubber lining to protect the metal parts from the acids of the pickling solution.

From the pickling housing 80, the pickled tubing is advanced into an aligned section of housing 96 for rinsing the pickling solution from the surface of the tubing. T-he rinse housing following pickling is very similar to the rinse housing 76 wherein water is sprayed from spray rings onto surfaces of the tubing passing therethrough to rinse the picklin g solution from the surface.

In the aforementioned alkali washes, rinse, pickling and final rinse, the housings can be of a unitary construction subdivided into separate sections by separating walls each of which is provided with aligned openings dimensioned to enable the tubing to pass lengthwise therethrough in and out of the housings. Instead, the housings can be separated members with aligned openings in the end walls for the continuous passage of the tubing from one to another without bending.

- An important concept of this invention resides in the means and method for continuously galvanizing the formed tubing as a continuous operation with the described forming, welding and cleaning operations. For

this purpose, it is desirable to contact the cleaned sur-A face of the steel tubing with molten zinc for sufficient time to enable the desired react-ions to take place to form the desired thickness of galvanize on the surface and it is irnportant to carry out the reactions under non-oxidizing conditions, otherwise undesirable oxides of the metal will form at the elevated temperatures under which the re- -actions are carried out.

The desired reducing or non-oxidizing atmosphere can be maintained by the enclosure of the galvaniz-ing zone within a sealed housing into which an inert, or reducing gas can be introduced for maintenance of a non-oxidizing atmosphere. This can be accomplished by a sealed enclosure but it is preferable to make use of an enclosure which is capable of removal to gain access to the interior of the galvanizing zone but without interfering with the ability to .achieve atmospheric control, when in position of use.

The desired characteristics have been achieved in the construction illustrated in FIG. 13 of the drawings -by the use of a rectangular hood 100 having a horizontally disposed top wall 102, side and end walls 104 which depend perpendicularly downwardly from the edges of the top wall into .a trough 106 facing upwardly from a frame 108 which extends all about the galvanizing zone. The bottom edges 110 of the side walls are received within the trough for support of the hood on the bottom wall thereof. The trough is at least partially filled with `a pulverulent material 112, such as tine sand, into which the lower edge of the side walls become embedded to effect a seal- -ing relationship all around lwhich militates against the ow of free gases all around for atmospheric control. One or more inlets 114 for the inert or reducing gas are provided in the walls of the hood for introduction of such inert or reducing gases in amounts tornaintain .an nonoxidizing atmosphere therein.

It has been found that the galvanizing reactions can becarried out more rapidly with greater uniformity when the tubing is preheated to an elevated temperature, such as -to .a temperature above the melting point temperature for the zinc, such as at 750 F., before being contacted with the molten zinc, although it is not essential to preheat. When preheating is effected, it is again important to achieve the desired preheat without exposure of the metal surface to oxidizing conditions, 'otherwise the metal oxides that would form at an accelerated rate while the tubing is heated to an elevated temperature would interfere with the formation of a suitable galvanize on the surface. In the illustrated modification, the preheat section comprises a tubular -housing 116 which has its center .aligned with the line of travel of the formed tubing lthrough the machine and which communicates with the enclosure 100. Inert gas is introduced into the tubular housing through an inlet 118 in the forward end of the tubular mem-ber for the circulation of the inert or reducing gas lengthwise through the housing into the hood or enclosure 100 to maintain non-oxidizing conditions within the 4tubular housing during passage of the tubing therethrough.

The tubing can be heated to elevated temperature by the introduction of heat from suitable and conventional internal or external heaters lbut it is preferred to make use of induction heating means 120 within the tubular housing to accelerate the build-up of temperature Within the tubing walls in minimum time thereby to minimize the lengths necessary for the tubular housing.

Having described the preheat of the tubing and the introduction of the preheated tubing into the inert galvavdisposed housing 122 in the form of a trough Valigned axially with the line of travel of the tubing for passage of the tubing axially through an intermediate section of the housing from an inlet 124 at one end to the outlet 126 at the opposite end. The housing is provided with one or more inlets 128 which are connected by a passage 130 to a reservoir 132 of molten zinc with means for displacement of the molten zinc from the reservoir to the inlets ata rate suicient to maintain the housing substantially filled with molten zinc to cover the tubing advanced therethrough. The inlet 128 is preferably, though not necessarily, located in the portion of the housing adjacent the inlet end 124 through which the tubing is introduced into the housing for concurrent flow of the molten zinc through the housing with the tubing and in position to overlie the tubing so as to direct the stream or streams of molten zinc onto the tubing.

The housing is further provided with a drain opening 180 in the bottom wall 182 of the housing with a downpipe 184 leading from the drain to the reservoir. The drain opening is of small dimension to enable a thin stream of molten zinc constantly to ow therethrough but at a rate that is considerably less than the rate of introduction of molten zinc into the housing less the amount that escapes through the openings so that there will be an overow of molten zine over the ends of the trough forming the inlet and outlet to the housing Ibut with `an amount of molten zinc in the trough to cover the tubing passing therethrough. The drain opening 180 is effective in the event of some failure in operation or stoppage of the machine thereby to drain molten zinc from the housing before the zinc has cooled to a temperature below its melting point, otherwise the zinc would become solidified within the housing and thereby render the housing unfit for future use until the solidified zinc is passed from the housing or otherwise, with difficulty removed.

The zinc in the reservoir can be heated by suitable burners or other heating means to maintain the zinc in the bath at a temperature above its melting point temperature of about 750 F. and preferably at a temperature above about 850 F. Access means are provided in the hood 100` for addition of pigs of zinc to the reservoir in amounts corresponding to the zinc that is used or otherwise removed with the tubing.

It is important to provide a sufficient weight of coating of molten zinc onto the surface of the formed tubing but it is undesirable to enable excess molten zinc to be carried off with the tubing thereby to increase the cost of galvanizing and/or prevent bead formation by excess zinc remaining on the outer surface. One means particularly adapted to control the thickness of the zinc coating without bead formation and to provide for removal of excess for return to the reservoir, while in a molten state and while still in a protective atmosphere, comprises an elongate block 150 of stainless steel or ,the like formed with a groove 152 extending lengthwise across the top wall 154 in which at least the leading edge portion 156 of the block still extends into the trailing end portion of the hood. The groove 152 in the top surface of the block is adapted to corresponding in curvature with a hemispherical section of the tubing to engage the lower half thereof during passage of the tubing lengthwise therethrough. In the preferred practice, the groove is formed to a diameter corresponding to that of the tubing or slightly greater.

Cooperating with the block is a roller 158 mounted for rotational movement about an axis crosswise of the line of travel of the tubing with an annular, arcuate recess 160 formed in the periphery of the roller shaped to correspond somewhat to a hemispherical section of the tubing being processed. As in the block, the arcuate recess 160 is dimensioned to have a diameter corresponding to that of the tubing or slightly greater. The roller is positioned with its lower edge 162 in endwise alignment with the top side of the recess 152 to more or less define :a circular section therebetween corresponding to the (circular section defined by the tubing or slightly greater.

Thus the roller 158 operates to engage the top side 'of the tubing after it issues from the galvanizing trough to preposition the tubing both in its travel through the galvanizing system and for its subsequent engagement with the grooved block for wiping excess molten zinc from the surface. Some excess zinc will also be removed by the roller upon engagement.

The cooperation between the roller and the block is believed to make the block effective as .a wiper for removal `of excess molten zinc from the 0111er wall of the tubing.

Such excess zinc is removed while the tubing is still within the hood thereby to provide premature freezing of the metal while simultaneously protecting the molten metal from oxidation so that the excesses removed can be allowed to tiow back into the reservoir for re-use.

The block is effective to still leave a desirable amount of zinc as a coating on the outer wall of the tubing. To prevent ow and bead formation, it is desirable to freeze the metal as soon afterl wiping as possible. For this purpose, use can be madeof a water quench, as in the form of a water spray or flow coat 164 following substantially immediately after the tubing emerges from the hood.

From the galvanizing section, the galvanized tubing is advanced sequentially through a series of water spray sections to cool down the galvanized tubing if the tubing has not otherwise been sufficiently cooled in the freezing step, and, from the cool-down operation, to conventional tube sizing rolls 192, and from the tube sizing rolls to a traveling shear section 194 where the endless tubing is cut into lengths of predetermined dimension for shipping. The water spray sections are similar to the rinse sections which follow alkali cleaning or acid etch and the tube sizing rolls and flying shear are of conventional construction.

As an alternative, the galvanized tubing, after being cooled, may be processed through a spray housing similar to the alkali cleaning, wherein the galvanized surface is wetted with a chromate and nitric acid solution for reaction to form a surface of zinc chromate whereby still greater resistance to oxidation is secured by comparison with a plain zinc galvanized surface. If a section of the spray housing is devoted to the chromate spray, an additional section should be provided for a water rinse to remove excess chromate solution from the surface.

As another innovation, the tubing is marked, as by means of a marking roll, after galvanizing as distinguished from the conventional practice of indenting to mark the tubing before galvanizing or even before the formation of the tubing. This is because the marking applied to the surface of the tubing before galvanizing becomes lled with molten zinc so that it would no longer be visible and the marked depressions appeared also to interfere with the proper galvanizing of the tubing surface. Thus the marking roll precedes tube sizing, as indicated by the position 191.

It will be apparent from the foregoing description that I have provided a simple, efficient and effective means for continuously forming tubing of strip steel and for galvanizing the formed tubing as a continuous operation with the continuous tube Vforming process.

It will be understood that changes may be made in the details of construction, arrangement and operation, as well as in materials employed, without departing from the spirit of the invention, especially as defined in the following claims.

We claim:

1. In a machine for the continuous forming and galvanizing of tubing including means for continuously feeding the endless strip of steel to the machine, means for forming the strip steel into rounded shape to bring the lateral edges together, welding means for joining the free edges of the strip steel in a continuous seam to form completely enclosed endless lengths of tubing, scarfing means for removing portions extending outwardly from the periphery of the tubing, washing and cleaning means for removal of grease and dirt from the outer surfaces of the formed tubing, means for treating the outer surface of the formed tubing to remove metal oxides, means for applying molten zinc onto the surface of the cleaned tubing and means for cutting the endless tubing into predetermined lengths, the improvement wherein the welding means comprises a welding member in the form of a fiat circular disc member having its lower peripheral edge portion in welding engagement with the upper side of the formed tubing to Weld the edges together to seal the tubing, means for rotating the disc member for displacement of the lower peripheral edge adjacent the tubing in the direction of linear movement of the tubing, and means for applying a coolant liquid onto the portion of the disc member immediately after it leaves the tubing and in a portion overlying the welded portion of the tubing, and rotating the electrode at a rate to enable the coolant liquid to drain from the electrode before returning into Contact with the tubing.

2. A machine as claimed in claim 1 in which the coolant is applied at about the nine oclock position on the welding disc.

3. A machine as claimed in'claim 1 in which the coolant is water.

References Cited by the Examiner UNITED STATES PATENTS CHARLES W. LANHAM, Primary Examiner.

R. J. HERBST, Assistant Examiner.

Claims

1. IN A MACHINE FOR THE CONTINUOUS FORMING AND GALVANIZING OF TUBING INCLUDING MEANS FOR CONTINUOUSLY FEEDING THE ENDLESS STRIP OF STEEL TO THE MACHINE, MEANS FOR FORMING THE STRIP STEEL INTO ROUNDED SHAPE TO BRING THE LATERAL EDGES TOGETHER, WELDING MEANS FOR JOINING THE FREE EDGES OF THE STRIP STEEL IN A CONTINUOUS SEAM TO FORM COMPLETELY ENCLOSED ENDLESS LENGTHS OF TUBING, SCRAFING MEANS FOR REMOVING PORTIONS EXTENDING OUTWARDLY FORM THE PERIPHERY OF THE TUBING, WASING AND CLEANING MEANS FOR REMOVAL OF GREASE AND DIRT FROM THE OUTER SURFACES OF THE FORMED TUBING, MEANS FOR TREATING THE OUTER SURFACE OF THE FORMED TUBING TO REMOVE METAL OXIDES, MEANS FOR APPLYING MOLTEN ZINC ONTO THE SURFACE OF THE CLEANED TUBING AND MEANS FOR CUTTING THE ENDLESS TUBING INTO PREDETERMINED LENGTHS, THE IMPROVEMENT WHEREIN THE WELDING MEANS COMPRISING A WELDING MEMBER IN THE FORM OF A FLAT CIRCULAR DISC MEMBER HAVING ITS LOWER PERIPHERAL EDGE PORTION IN WELDING ENGAGEMENT WITH THE UPPER SIDE OF THE FORMED TUBING TO WELD THE EDGES TOGETHER TO SEAL THE TUBING, MEANS FOR ROTATING THE DISC MEMBER FOR DISPLACEMENT OF THE LOWER PERIPHERAL EDGE ADJACENT THE TUBING IN THE DIRECTION OF LINEAR MOVEMENT OF THE TUBING, AND MEANS FOR APPLYING A COOLANT LIQUID ONTO THE PORTION OF THE DISC MEMBER IMMEDIATELY AFTER IT LEAVES THE TUBING AND IN A PORTION OVERLYING THE WELDED PORTION OF THE TUBING, AND ROTATING THE ELECTRODE AT A RATE TO ENABLE THE COOLANT LIQUID TO DRAIN FROM THE ELECTRODE BEFORE RETURNING INTO CONTACT WITH THE TUBING.