US2680179A - Machine for fabricating metallic ladders - Google Patents

Description

June 1, 1954 J M MACHINE FOR FABRICATING METALLIC LADDERS 8 Sheets-Sheet 1 Filed Aug. 27, 1952 INVENTOR. WoMg/QICGAQ/ J. A. MASE V MACHINE FOR FABRICATINC METALLIC LADDERS Filed Aug. 27, 1952 June I, 1954 8 Sheets-Sheet ,2

INVENTOR June 1, 1954 J. A. MASE 2,680,179

- MACHINE FOR FABRICATING METALLIC LADDERS Filed Aug. 27, 1952 8 Sheets-Sheet 3 IN VENTOR June 1, 1954 J. A. MASE 2,680,179 MACHINE FOR FABRICAT'ING METALLIC LADDERS Filed Aug. 27, 1952 8 Shets-Sheet 4 INVENTOR Jpugm? 9W0 BY dxflsgmy June 1, 1954 J. A. MASE MACHINE FOR FABRICATING METALLIC LADDERS 8 Sheets-Sheet 5 Filed Aug. 27, 1952 IN VENTOR June 1, 1954 A, M SE 2,680,179

MACHINE FOR FABRICATING METALLIC LADDERS Filed Aug. 27, 1952 8 Sheets-Sheet 6 5P0 CONTROL ARAOW //Vfl/CA7'E-5 FREE F1014 60/965 TAN/f Jo/042 04? M50444; 916410 0,

d bjn INVENTOR ladder in a hot up Patented June 1, 1954 MACHINE FOR FABRICATI NG METALLIC A LADDERS Joseph Anthony Mas Internationa a corporation of Indi e, Detr 1 Steel ana ompany,

cit, Mich., assig'nor to Evansville, Ind.,

Application August 27,'1952, Serial No. 306,57 7

6 Claims. 1 My invention relates bro means for fabricatin adapted for railway c a machine and met ladders.

One of the objects of m a method for fabricating car use by the hot upsetti rungs with respect to the sides of the ladder.

Another object of m a method for fabricatin adly to a method and g steel ladders especially ar use and particularly to hod for fabricating steel y invention is to provide steel ladders for freight ng of the metallic ladder steel angles forming the y invention is to provide g steel ladders using angle members as side supports and steel rods as ladder treads which involves the hot upsetting of the opposite ends of the ladder treads for securing the ladder treads in the angle members.

Another object of my invention is to provide a construction of machine for fabricating railway car ladders from steel angles forming the sides of the ladder and steel rods forming the treads of the ladder in which successive operations for clamping, forging, quenching and unclamping the setting machine are performed ject to manual placement and der in the forging of successive ween the steel angles. bject of my invention is to proontrol circuit for a hot upsetting ularly adapted for the fabricaautomatically sub guiding of the lad ladder rungs bet Still another 0 vide a program 0 machine partic tion of steel la rungs are clam ends extendin the flanges o ped in position with their opposite g through aligned perforations in f angle members forming ladder stiles and the projecting ends of each rung successively subjected to th rent for raising the ru whereby the opposite en axially subjected to pre material thereof and securing the rung with respect to the ladder stiles.

Another object of my invention is to provide an arrangement of timing means for the electrical and compressed air control means of a hot upsetting machine for fabricating railway car steel ladders whereby steel ladder stiles and steel rungs may be clamped with the ends of the rungs projecting through perforations in the flanges of the stiles, the ends of the rungs electrically heated, axial pressure applied to the ends thereof for upsetting the ends of the rungs with respect to the ladder stiles, the electrical heat-- ing current and pressure removed and the ladder unclamped for manual displacement to the next succeeding operating position for successively securing the rungs in position.

ngs to a suitable heat ds of the rungs may be ssure for upsetting the dders whereby successive ladder e passage of heating cur- I Still another 0 vide adjustable tions of the cl railway car 1a ted flanges of steel angle members tion of axial pressure Other and furth er objects of my invention reside in the method of operation and specification h to the accomp Figure 1 is a matic hot u ereinafter following by reference anying drawings, in

which chine of Fig. 3 on line i'l thereof; Fig. 5 is a transverse vertical sectional view on an enlarged scale taken on line 5-5 of Fig. 3 with certain of the parts shown in elevation; Fig. 6 is a plan view; Fig. '7 is a vertical transverse sectional view taken substantially on line 1-"i of Fig. 5; Fig. 8 is a detail view illustrating the adjustin mechanism with certain of the parts shown in section; Fig. 8a shows the assembly of the adjusting mechanism illustrated in Fig. 8; Fig. 9 is a fragmentary vertical sectional View looking in the direction of arrow A in Fig. 8; Fig. 10 is a fragmentary sectional view through one of the outside head forming dies shown in clamped relation to an inside head formin die, the dies being shown in position just after the completion of a hot upsetting operation and illustrating particularly the means for quenching the outside head forming die; Fig. 11 is a schematic diagram illustratin the programmed operation of the air control system in the hot upsetting machine of my invention; Fig. 12 is a schematic diagram of the program control circuit employed for timing the application of heatin current to the ends of the treads while in clamped position between the ladder stiles for effecting an upsetting operation; Fig. 13 is a theoretical diagram showing the manner of applying the heating current to the ladder rungs under control of the circuit illustrated in Fig. 12; Fig. i4 is a, theoretical diagram of the electrical current path through the ends of the transverse ladder treads and the outside head forming dies in accordance with my invention; and Fig. 15 is a transverse sectional view through the ladder rung as finally secured in the ladder stiles in accordance with my invention.

My invention is directed to a method of making steel ladders particularly adapted for railway car installation and to the construction of a machine for fabricating such steel ladders. I provide an arrangement of resistance bridge hot upsetting machine which employs a pair of axially disposed outside head forming dies adapted to be moved inwardly toward each other under pressure and a pair of electrodes adapted to be moved downwardly in a vertical direction under pressure in coplanar alignment with the axes of the advancin outside head forming dies and in proportion to the movement thereof for conjointly clamping the steel rung of a ladder resting loosely and transversely through longitudinally spaced angle members forming the ladder stiles. The loosely assembled ladder rung positioned in the ladder stiles is introduced in successive positions between the head forming dies and the pair of electrodes. The pair of electrodes grip the ladder rung interiorly of the flanges of the ladder stiles while the outside head forming dies establish pressure connection with the projecting ends of the ladder rungs. The alignment of the ladder stiles and the loosely arranged ladder rungs therein is effected manually, but, thereafter all operations are programmed automatically.

When the ladder stiles and the associated projecting ladder rung are firmly tion the opposite ends of the ladder rung are subjected to the passage of electrical current which raises the temperature of the ends of the ladder rung to a red heat. When a flow condition of the steel is reached, the inwardly advancing outside head forming dies apply axial inward pressure to the rung. The electrodes which grip clamped in position which includes a the ladder rung in a position spaced from the interior sides of the flanges of the angle members constituting the stiles coact with anvils and form therewith an inside forming die whereby the material of the rung is upset in a position both inside and outside of the flanges of the ladder stiles, thereby firmly fastening the rungs in the ladder stiles. When the forging operation is completed the outside head forming dies effect a blast of air against the upset ends or" the rungs suddenly cooling the rungs and settin the inaterial thereof with respect to the ladder stiles. The program mechanism then eiiects a withdrawal of the outside head forming dies, a retraction of the electrodes and the release of the clamped stiles enabling the stiles to be moved to the next succeeding tread forging position for effecting a repeat operation. The total fabrication time for each ladder is but a small fraction of the time required for the production of conventional steel ladders.

Referring to the drawings in more detail, reference character 1 designates the frame structure of the hot upsetting machine Of my invencentral arch structure 2 which serves to support the vertically depending, spaced electrode operatin cylinders 3 and 4. The electrode operating cylinders 3 and 4 control the depending electrode carrying piston rods 5 and t which suspend the electrodes 7 and 8 which grip the upper surface of the ladder run 9 and provide part of the inside forming die for allowing the upsetting of the material or the ladder rung 9. The otherportion of the inside forming die is constituted by anvils it and H aligned with the electrodes '5 and 8, respectively, on the inside of the flanges of the angle members l2 and i i, constituting the sides of the ladder.

The angle members i2 and I are fitted to the hot upsetting machine along a table shown at i5 in Figs. 1 and 2. The table I5 is erected on an angular iron frame Hi, supported from the floor adjacent one end or the machine and supported by bracing members il from the top of the frame i of the hot upsetting machine. The top of the frame l is provided with spaced mountin means shown at i8, 19, it} and 21 disposed forwardly and rearwardly of the arch structure 2 and in alignment with the angle members 12 and ill being guided through the hot upsetting machine along table it. The spaced mounting means are each adjustable in a vertical direction for properly supporting the angle members in positions in which the successive ladder rungs 9 may be gripped between electrodes and 8 and anvils it and ii. That is, each of the spaced mounting means l5-2i includes a central screw threaded head therein shown at i801, Na, 2% and Zia, which may be elevated or lowered to accurately guide the angle members 92 and id in the course of the movement thereof through the hot upsetting machine. The central screw threaded heads include vertically adjustable supports llb-ib, which operate in vertical paths within guides lilo- M0. The supports are projectible in a vertical direction by means of a mechanical linkage shown more clearly in Fig. under control of an air supply cylinder 22 which controls the piston rod 2:"; connected at its center with the two laterally extending links 2% and 2'5. The laterally extending links and 25 are pivoted at the inner ends thereof at 26 and connect with piston rod :13. The links 2d and are pivotally mounted at El and 23 with respect to the frame 1 and have their outwardly extending ends piv adjustable supports otall'y connected through lost motion connections a and 25a with the lower ends of the i812 and I92), whereby air supplied to cylinder 22 moves piston rod 23 downwardly, ejecting the central screw threaded heads |8a and |9a upwardly, engaging the flanges of the angle members l2 and M for elevating the angle members into a position in which theladder rung 9 may be clamped between electrodes 1 and 8 and anvils iii and H. The identical remote end of the machine adjacent the spaced mounting means 20 and 2| is similarly constructed, and the central screw threaded heads 26a and Zla projected upwardly under control of the cylinder shown at 30 to the operation described cylinder 22.

The frame I of the machine has laterally extending supports thereon serving as mounting in a manner similar in connection with means for the oppositely disposed air controlled clamping cylinders 3| and 32, which are aligned on opposite sides of the arch structure 2 and in alignment with the outside head forming dies shown at 33 and '36. The outside head forming dies are cylindrically constructed as shown more clearly in Fig. 10, in which the outside head forming die 3d i shown as constituted by a cylindrical member having hollow tubular interior 34a externally screw threaded on its end 34?) to engage the interior screw threads formed in the trans verse block to which transverse movement is imparted by operation of the piston in cylinder 32. Each of the head forming dies is cooled by an internal air blast conducted through a tubular member such as 340 in Fig. 10 connected to supply a blast of air from the air source connected through port 3 3d from which the air strikes the inside of the end wall of the hollow outside head forming die and is thereafter exhausted through discharge port 34c. A symmetrical construction is provided on the opposite side of the machine where outside head forming die 33 is coupled to the moving piston of cylinder 3| through block 36. Transverse guides 37 and 38 are provided for insuring the lineal movement of the outside head forming dies toward and away from the angle members as they are passed through the machine. The setting of the position of the outside head forming dies 33 and 3c is accurately adjusted by means of adjusting screws 39 and 43 mounted in bracket members ii and "42 adjacent opposite ends of the frame I and connected with the casings of the air controlled clamping cylinders 3| and 32 for shifting the cylinders transversely in guides represented at 33 and 64 in Figs. 2 and 3.

In addition to the air actuated cylinders 22, 30, 3| and 32, there is also provided an ejector air controlled cylinder 35. The ejector air controlled cylinder 65 operates an adjustable piston rod 46 which is pivoted at iii to a pair of links 48 and 4s arranged in the form of a Y. The ends of links 48 and 49 pivotally' connect with the inner ends of a pair of ejector bars represented at 56 and 5|. The outer ends of these bars extend through guides 52 and 53 supported in aligned positions on arch structure 2, so that the bars 5e and; 5! are guided in a plane transverse to the direction of movement of the angle members i2 and Hi through the machine. The ejector bars 5!] and 5| carry guide shoes 54 and 55 adjacent their bottom faces, which rest upon the mounting plates 56 and 51. The mounting plates 56 and 5? are in turn spacially adjustable on frame support 58 between guides 59. Operation of piston rod 46 serves to project or retract the ejector bars 50 and 5| in a lateral direction and simultaneously engage the shoes 68 and BI with the inside surface of the webs of the angle members 2 and M for facilitating the pressing of the angle members against the forces applied by the outside head forming dies 33 and 3 1 and insuring the upsetting of the metal or the rungs web of the angle member immediately surrounding the apertures through which the rungs project.

In addition to the foregoing air control cylinders, air control cylinders 62 and iii are provided adjacent the front of the machine mounted on brackets 6d and 55 carried by the arch structure 2. The air control cylinders 62 and as operate transversely disposed bars 66 and 5t carrying anvil members 6 8 and st, operative to engage the inner faces of the webs of the angle members 12 and I4 adjacent the position of entry of the angle members into the forging zone of the machine.

On opposite sides of the arch structure 2 there is provided centering lever arrangements for insuring the centering of the rungs t through the apertures in the webs of the angle members i2 and M. The centering means comprise a bracket 79 extending from one side of the arch structure 2, serving as a pivotal mounting at 'H having an arm projecting inwardly and curved in a position extending within the rolled section constituted by the angle member such as It in Fig. 8 and having a curved end 72a adapted to be engaged by the projecting end of the rung 9 as it is loosely mounted between the webs of the angle members. As the rungs are advanced into the forging position, the rungs lever 73 mounted on the opposite side of the arch as schematically illustrated in Fig. 8a. Each bell lever is assembled in a symmetrical manner and Fig. 8 will serve to illustrate the assembly of both levers indicated more particularly in Fig. 8a. The projecting end 12b of hell lever i2 is slotted at 720 for the passage of the adjustable screw threaded rod M, pivoted at '15 to the arch structure 2. The screw threaded rod id is engaged by sets of nuts Ma on one side and an adjustable gripping means 75 on the other side. By adjusting the gripping means it along the screw threaded rod M and locking the said gripping means in position by lock nut i? the position of the curved ends 52a and Eta of hell levers i2 and 73 may be set for properly centering the rungs Q, preparatory for the forging operation, when the rung is moved to a position aligned with the outside head forming dies 33 and 3d.

The several air control cylinders hereinbefore described are associated as represented schematically in Fig. 11, wherein the air controlled clamping cylinders 3| and 32 are shown in approxioutside head forming dies shown schematically at 33 and 3d. The electrode operating cylinders are schematically shown at 3 and d in a vertical position for operating electrode carrying piston rods 5 and 6. The ejector or spreader bar air at substanand 51 carrying anvils 68 and 69. The ejector cylinders are shown at 22 and 30 at opposite ends of the machine for respectively operating the heads 20a and 21a at one end of the machine and the heads lBa and lea at the opposite end of the machine for simultaneously elevating the angle members into a centered position for eiiecting a forging operation. The interconnection of the several air controlled cylinders has been schematically illustrated in the diagram all controlled from the pressure source connected to main air supply line 18, from which the air is distributed through pipe lines "I9, 8%, 3i and 32 to the several groups of cylinders, as shown, and controlled by valve systems, as illustrated.

In Fig. 12 there is shown the program control circuit employed for timing the application of the heating current to the ends of the treads while in clamped position between the ladder stiles for effecting a hot upsetting operation. The power source, such as 110 volts 6o cycle alternating current, has been indicated as connected with the terminals 83 and con ected to the control circuit through switches 84 and fuses 85 to the relay system, which includes across the circuit 5', 6' the cycle start contacts 2| and contacts CR5 connected through circuit element I with emergency stop unclamped contacts 22, connected through circuit element 2 connected to CR4 which are connected through circuit element 3 with circuit CRI. The next progressive section of the program control circuit includes contacts CRI' connected through circuit element 3' with clamp pressure switch #1 shown at Psi connected through circuit element 1 with contacts CR2 and connected through circuit element 8 with solenoid valve and the solenoid valve control circuit for positioning the angle members l2 and H1. represented at 3G. The next level of the program control circuit includes contacts TDRll and solenoid TDRG. The succeeding level of the program control circuit includes timer valve relay 8'1 connected through circuit elements we and Hit and through circuit element 9 with circuit TDR3 for controlling the weld press solenoid C. The next level or" the program control circuit includes the forge valve relay contacts represented at 88 between circuit elements I98 and i555 connected through circuit element W with solenoid valve D and circuit CR2. The next progressive level of the program control circuit contains contact CR1, circuit element l i and solenoid valve A for the clamping dies and 34. The next level of the program control circuit includes the heating contacts for turning the heat on and oif, shown at 89 connected through circuit element i2 and circuit elements iiis and 65 to the timer contactor relay shown at se. The circuit is completed through circuit element iii to the contactor firing relay t l. The final level of the program control circuit contains contacts TDRS, contacts 92, circuit element I l and relay 01% shown at es.

Fig. 13 illustrates the manner of applying the heating current to the ladder rungs under control or t e circuit illustrated in 12, where the circuit elements -.,ustrated 12 have been schematically described by the reference characters used in Fig. 12 and showing the relative sequence of the different components represented by the legends for controlling the ignitron contactor system, such the General Electric CR7503E1U3 ignitron contactor, including gaseous discharge tubes 9 and 55 operating from a source or" 44f) volts 6'0 cycle power supply connected to terminals 86 for delivering an aproximately kva. to the welding transformer represented at 91 shunted by the load resistor or surge suppressor 98. The circuit through the ladder rung 9 has been indicated schematically at 99. The timer has been indicated in block diagram at I00, designating, for example, a General Electric type CR75G3F130 nema 5B timer, and the relay panel has been shown at iili containing the several relays indicated by reference designations which are similar to the designations shown in Fig, 12. The contactor PSI and the relative circuit positions or" solenoids A, B, C and D have been indicated in Fig. 13.

In Fig. 14 the manner of and forging operation has in the positive terminal of the power supply is fed to the electrodes '2 and 8, while the negative side of the power supply is fed to the outside head forming dies 33 and (i l for raising the temperature of the ends of the rung 3, according to the current flow path indicated by the arrows and enabling the hot upsetting operation to be effected as the ladder rung is subjected to axial pressure producing the headed ends Ba and 9b, as shown in Fig. 15, on the ladder rung on the sides of the webs of the angle members i2 and. id, adjacent the flanges thereof, and producing the rounded shoulders to and 53d on the sides of the webs which are disposed in spaced parallel relation to each other.

The method of producing ladders has proven very rapid in mass production. The upsetting of a single rung has been described, but it will be llllflEl'SJOOd that the angle members constituting the ladder with the rungs loosely fitted therein are fed through the machine in successive steps for fastening the several treads in position. A complete railway car ladder including eight rungs may be fabricated in a time period averaging approximately seven minutes, utilizing the methed and machine of this invention.

The machine is set in operation by activating an electrical switch, thereby clamping the preplaced ladder rung with the electrodes 1 and 8 operated from the vertical cylinders 3 and 4. The cylinders are located between the ladder stiles and operate the electrodes which form with the anvils id and ii a very rigid rung clamp and also incorporate the inside rung head forming dies.

While pressure is maintained by the two cylinders 3 and i, the two horizontal cylinders 3i and 33 which operate the outside head forming dies automatically proceed inward to the rung ends.

Through the use of a surge tank It?! (Fig. 11) for the storage of an additional supply of air over and above that furnished by the direct airline pressure, these two cylinders 35 and 33 are held with pressure on both sides of the pistons within the cylinders to cushion the contact of the outside forming dies 33 and 34 to the ends of the ladder rung.

Just before the circuit is closed, or, in other words, just before the contact of the outside head forming dies 33 and 34 with the ends of the rung, three cylinders 45, 82 and 63, connected to fulcrum lev rs on each side of the dies, spread the ladder stiles i2 and M an amount equivalent to the metal used to shape the inside head.

Upon contact of the two outside head forming dies 33 and 3d operated by cylinders 31 and 32 with the ends of the ladder rung, the heating cycle through the electrical timers (Figs. ll1213) is activated. Through automatic operation of effecting the clamping been illustrated, wherethe electrical controls at this point, the spreader bars are retracted, the air is discharged from in front of the two cylinder pistons of cylinders 3| and 32, and the upsetting of the inside and outside forged heads of the ladder rung is performed with the full capacity of approximately 10c pounds per square inch.

Then, with the forging of the ladder rung completed, and again through automatic electrical controls, all cylinders and dies are returned to a retracted, or open position. The ladder rung is ejected from the dies by two vertical cylinders 22 and 30 by pushing the ladder upward and maintaining the ladder in an upward position for pushing the ladder forward and advancing the ladder to the next run location. Ihe loading of the ladder stiles and the ladder rungs is a man ual operation, but all other operations are completely automatic.

While the method and construction of the machine has been described in one of its preferred embodiments, it is realized that modifications and changes may be made, and it is to be understood that no limitations upon the invention are intended other than may be imposed by the scope of the appended claims.

What I claim is:

1. Apparatus for fabricating metallic ladders of the type which includes a pair of spaced metallic angles having metallic ladder rungs extending between the metallic angles comprising a frame, an arch structure on said frame, means for guiding a pair of substantially parallel longitudinally extending spaced metallic angles in parallel relation beneath said arch structure, the webs of said metallic angles carrying metallic ladder rungs projecting transversely thereof and means extending transversely through said arch structure and aligned with the opposite projecting ends of the ladder rungs for gripping the projecting ends of the ladder rungs for applying axial pressure thereto, composite electrodes and anvils gripping opposite end portions of the ladder rungs in positions immediately adjacent the inner faces of the webs of the angles for maintaining said rungs in position while pressure is applied to the opposite ends thereof, circuit means connected with the electrodes of the composite electrodes, adjustable means engaging the opposite projecting ends of the ladder rungs for symmetrically centering the ends of the ladder rungs with respect to the angles prior to each upsetting operation and anvils forpassing the heating current through the end portions of the ladder rungs for performing a hot upsetting operation and fastening the ends of the ladder rungs with the webs of said metallic angles.

2. Apparatus for fabricating metallic ladders of the type which includes a pair of spaced metallic angles having metallic ladder rungs extending between the metallic angles comprising a frame, an arch structure on said frame, means for guiding a pair of substantially parallel longitudinally extending spaced metallic angles in parallel relation beneath said arch structure, the

i webs of said metallic angles carrying metallic ladder rungs projecting transversely thereof and means extending transversely through said arch structure and aligned with the opposite project v ing ends of the ladder rungs for gripping the projecting ends of the ladder rungs for applying axial pressure thereto, composite electrodes and anvils gripping opposite end portions of the ladder rungs in positions immediately adjacent the inner faces of the webs of the angles for maintaining said rungs in position while pressure is applied to the opposite ends thereof, circuit means connected with the electrodes of the composite electrodes, adjustable means on each side of said arch structure and aligned with the ends of the ladder rungs, said adjustable means each including a pivotally mounted bell lever carried by the side of the arch structure, a shoe carried by one end of said lever and extending in the path of the ends of the ladder rungs projecting through said angles, the other end of said lever being adiustably engaged by an adjustable screw device pivotally supported with respect to said arch structure for adjusting the position of the shoe carried by said lever, whereby the symmetrically arranged shoes engage and center opposite projecting ends of the ladder rungs, preparatory for a pressure applying and current .applying operation and anvils for passing the heating current through the end portions of the ladder rungs for performing a hot upsetting operation and fastening the ends of the ladder rungs with the webs of said metallic angles.

3. Apparatus for fabricating metallic ladders of the type which includes a pair of spaced metallic angles having parallel ladder rungs extending between the metallic angles comprising a frame, an arch structure on said frame, means for guiding a pair of substantially parallel longitudinally extending spaced metallic angles in parallel relation beneath said arch structure, the

webs of said metallic angles carrying metallic ladder rungs projecting transversely thereof and means extending transversely through said arch structure and aligned with the opposite projecting ends of the ladder rungs for gripping the projecting ends of the ladder rungs for applying axial pressure thereto, composite electrodes and anvils gripping opposite end portions of the ladder rungs in positions immediately adjacent the inner faces of the webs of the angles for maintaining said rungs in position while pressure is applied to the opposite ends thereof, circuit means connected with the electrodes of the composite electrodes, a pair of spreader members aligned with the angles and engaged with the angles for displacing the angles to positions for shaping the inside head of the ladder rung during the heating and forming operation and anvils for passing the heating current through the end portions of the ladder rungs for performing a hot upsetting operation and fastening the ends of the ladder rungs with the webs of said metallic angles.

4. Apparatus for fabricating metallic ladders of the type which includes a air of spaced metallic angles having parallel ladder rungs extending between the metallic angles comprising a frame, an arch structure on said frame, means for guiding a pair of substantially parallel longitudinally extending spaced metallic angles in parallel relation beneath said arch structure, the webs of said metallic angles carrying metallic ladder rungs projecting transversely thereof and means extending transversely through said arch structure and aligned with the opposite projecting ends of the ladder rungs for gripping the projecting ends of the ladder rungs for applying axial pressure thereto, composite electrodes and anvils gripping opposite end portions of the ladder rungs in positions immediately adjacent the inner faces of the webs of the angles for maintaining said rungs in position while pressure is applied to the opposite ends thereof, circuit means connected with the electrodes of the composite electrodes, a pair of spreader bars operative to engage the inside faces of the webs of the angles-for spreading theiangles in a position prior to the alignment of the ladder rung carried thereby with the means for gripping the ladder rung, separate means for spreading the angles ata position located beyond the means for gripping the ladder rung, and anvils for passing the heating currentthrough' the end portions of the ladder rungs for performing a hot upsetting operation and fastening the ends of the ladder rungs withithe webs of said metallic angles.

5. Apparatus for fabricating metallic ladders eithe -type which includes a pair of spaced metallicangles having parallel ladder rungs extending between the metallic angles comprising a frame, an arch structure on said frame, means for guiding a pair of substantially parallel longitudinally extending spaced metallic angles inparallel; relation beneath said arch structure, the webs of said metallic angles carrying metallic ladder rungs projecting transversely thereof and meansextending transversely through said arch structure and aligned'with the opposite project-- ing ends of the ladder rungs for gripping the projecting ends of the ladder rungs for applying axial pressure thereto, composite electrodes and anvils gripping opposite end portions of the ladder rungs in positions immediately adjacent the inner faces of the webs of the angles for maintaining said rungs in position while-pressure is applied to the opposite ends thereof, circuit with metallic treads extending transversely of versely disposed, outside head, forming dies for gripping opposite projecting ends of the ladder rung, means disposed above the ladder rungand constituting electrodes movable into position for. gripping the ladderrungs immediately adjacent the inner faces of the webs of the said angles. anvils carried by said frame structure-and located below the ladder rung and in alignment with the.

said electrodes in a plane coincident with the transverse plane of said outside head forming dies, whereby a heating current path may be established through said electrodes and through the end portions of said rungs and completed through the outside head formingdies for raising the temperature of the end portions of the ladder rung'to deformation temperature and effecting a hot upsetting operation for fastening the ladder rung through the webs of. the angles, means displaced at opposite sides of the hot upsetting position forengaging and spreading. said angles and separate means disposed beyond the aforesaid means and remote from. said hot upsettingposition for engaging and displacing said angles. from the aligned position thereof with said outside head forming dies.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,578,019 Ellis Mar. 23, 1926 1,901,334 Reed Mar. 14, 1933v 1,996,250 McNamara Apr. 2, 1935 2,136,619 Johnson Nov. 15, 1938 2,473,245 Hanna June 14, 1949

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