US2498813A - Machine for applying helical fins to cylindrical bodies by means including ironing tools - Google Patents

Description

E. s. LEA 2, MACHINE FOR APPLYING HELICAL. FINS TO CYLINDRICAL BODIES BY MEANS INCLUDING IRONING TOOLS 4 Sheets-Sheet 1 Feb. 28, 19 50 Original Filed March- 21, 1942 .ZNVE'NTQR Edward/5. [fa

17. TOR/V153 Feb. 28, 1950 E. s. LEA 2,498,813 W MACHINE FOR APPLYING HELICAL FINS TO CYLINDRICAL BODIES BY MEANS INCLUDING IRONING TOOLS Original Filed March 21, 1942 4 Sheets-Sheet 2 Willi INVHVFQK Edward 5. [d

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WFI'ORNEY 2,498,813 NS T0 CYLINICAL Feb. 28, 1950 E. s; LEA

MACHINE FOR APPLYING HELICAL FI BODIES BY MEANS INCLUDING IRONING T00 Original Filed March 21, 1942 4 Shets-Sheet 3 Feb. 28, 1950 E s LEA 2,498,813

MACHINE FOR APPLYING HEI JICAL FINS TO CYLINDRICAL BODIES BY MEANS INCLUDING IRONING TOOLS- Original Filed March 21, 1942 4 Sheets-Sheet 4 [WE/V705 Edwdm/S'. [Pd

Patented F eb. 28, 1950 UNITED STATES PATENT OFFICE MACHINE FOR APPLYING HELICAL FIN S T0 CY-IiIlSTZDRIGAL BODIES BY MEANS INCLUD- ING IRONING TQOLS Edward .S. Lea, Morrisville, Pa., assignor to Buensod-Stacey, Incorporated, New York, N. Y., a corporation of Delaware 4'Claims. 1

This invention relates to an apparatus for applying upstanding helical fins to cylindrical bodies, and is a division of my copending application S. N. 435,728, filed March 21, 1.942, issued March 19, 1946, as Patent No. 2,396,795. Since it has been especially devised for use in forming heat radiating fins upon aircraft engine cylinders and the like, the invention will be described with particular reference to its utility in such an op eration.

The principal object of the invention is to provide a machine for drawing a preformed helical fin which has been fitted to a cylindrical body until its inner edge tightly engages the outer surface of that 'body, so that it may be bonded in place, and of mechanically working the fin after it has been softened and warped by the heat of the bonding operation for the dual. purpose of hardening it sufiiciently and of straightening it so that its convolutions define a series of unitorm air cooling passages.

It-is a furtherobject of the invention to provide a; machine of the foregoing kind which is of simple design and rugged construction-and which lends itself to operation by an unskilled mechanic to carry out the several steps of the method disclosed and claimed in the parent application at high speed, thus permitting that method to be put into practice at minimum expense,

The foregoing and other objects .of the invention, as well as its various features, will be more fully understood from the tollowing description in the light of the accompanying drawings,

which:

Figure 1 is an elevational view, partly in section, of a barrel of a standard airplane engine cylinder having :an outer cylindrical surface adapted to receive separately formedcooling Fig. 2 is an elevational view of a preformed helical fin which is adapted tobe applied to cylinder barrel of Fig. 1 by the method of the present invention; I

Fig. 3 is an jelevational view of a cylinder having the fin of Fig. '2 fitted :over its barrel, with its leading end secured toone end of the cylinder, this view illustrating the fin at an intermediate stage of its application to the cylinder;

Fig. 4 is a plan view. partly in section, of a fragment of .a machine embodying the principles of the invention and designed to carry out several of the steps of the method, and illustrates that method at another one of its intermediate stages;

Rig. .5 is a sectional view of a fragment of the cylinder barrel after finshave. been applied to surface, and after those fins have been finally secured in place.

Fig. 6 is a sectional view of a clamping member which is used to secure the trailing end of the fin in fixed relation to the cylinder barrel at the completion of one of the steps of the method;

Fig. 7 is afront view of the clamp of Fig.6;

Fig. 8 is a sectional view taken on the line -8--8 of Fig. 4;

Fig. 9 is a sectional view of a portion of the machine of Fig. 4;

Figs. 10 and 11 are views illustrating the details of certain portions of the machine of Figs. 4 and 8;

Fig. 12 is a sectional view taken substantially along the plane of the line "|2-'I2 of Fig. 4;

Fig. 13 is a sectional view of a fragment of a cylinder barrel with a cooling fin partially applied to its surface, the view illustrating the method of the invention at one of its intermediate steps;

Fig. 14 is an end view of a portion of the machine of Fig. 4 as viewed from the left end thereof;

Fig. 15 is a plan view, partly in section, of a fragment of the structure of Fig. 14; and

Figs. 16 and 1'! illustrate one way in which the convolutions of a fin applied by the method of the invention may be held in spaced relation while they are being soldered to the barrel.

In the drawings, and referring to Fig. '1, numeral l2 identifies a flanged steel barrel having a flange l3 near one of its ends by which the barrel may be secured to the crankcase of an engine, an enlarged shoulder I4 near its other end which will subsequently be threaded to receive a conventional cylinder head, and an intervening cylindrical surface l5 of lesser diameter than either the flange or the shoulder. It will be assumed for the purpose of description that a helical fin of copper is to be applied to this barrel in place of the usual integrally formed steel heat radiating fins. In accordance with the method of the parent application, a flat strip 16 of copper is first rolled to form a helix (Fig. 2) having an inside diameter 1 such as to permit that element to :be passed endwise over enlarged shoulder 14 of the barrel and be brought to rest on thesmaller diametered surface 15. At this stage of the operation the helical strip will rest loosely upon the barrel with its convolutions touching one another as is shown in Fig. 3. Preliminary to the drawing out step of the method, the leading end of the helix is mechanically fixed to the barrel in any suitable way. This may conveniently be done by inserting the hook ll, whichhas been formed at the end of the strip for that purpose, in a slot 18 of a clamp N3; the clamp preferably comprising a part of a driving rin which has theretofore been'secured on the end of the barrel by set-screw 24. When this has been done, the barrel is fitted to a stub arbor 2!! with the driving ring disposed adjacent face plate 22. The arbor, face plate, and certain other elements hereinafter considered, may be parts of any standard screwcutting lathe the construction and operation of which is sufficiently well known not to require description and illustration here. At this point, the leading end of strip I6, immediately adjacent clamp i9, is engaged between a pair of tools 25, 26, (see Figs. 4, 8 and 13) which are mounted on a frame 21 secured by screws 28 to the cross slide of the lathe so that they may be advanced toward and withdrawn from the cylinder barrel at appropriate times. One of the tools, 25, is preferably secured to an arm 29 which is mounted to swing about pivot pin 30 (see Fig. 4) and a spring 3| serves to urge this tool inwardly whereby to squeeze the strip between its inner face and that of the fixed tool 26. The pressure which must be applied to the strip by the tools will depend upon the size and thickness of the strip, and upon the extent to which the diameter of the helix must be reduced. In the illustrative case it has been found that the tools should actually deform the surfaces of a copper strip. Thus, when the tools have been advanced toward the barrel, and the leading end of the strip it has been disposed between them, the tension of spring 3i may be adjusted by screw 32 whereby to squeeze the strip to a desired degree; and the screw may then be locked in its adjusted position by locknut 33.

The preliminary set-up for the drawing-out step of the method is now complete; and the relative positions which the barrel, strip and ironing tools occupy at the beginning of that step are shown in full lines in Fig. 4. Upon the starting up of the machine, a driving pin 34 carried by the face plate engages cross flange 35 of the driving ring, thereby rotating barrel I! about its own axis and drawing strip is between the ironing tools. Simultaneously, the frame 21, and the tools which it carries, are advanced lengthwise of the barrel by automatic feed screw 36 at a uniform rate which is set by the relative speeds of the arbor 2i and of the feed screw. This action therefore serves to locate the convolutions of the strip at regularly spaced intervals alon surface i5, and at the same time to draw out the strip progressively until its inner edge tightly engages the barrel.

The drawing out of the helical strip to reduce its inside diameter to that of the outside of the barrel may have three separate components. First, there is the normal reduction in diameter which is occasioned by the stretching of the helix, that is to say, by the increase in spacing between its convolutions from the touching condition which existed when the helix was applied to the barrel to that existing when the fin is properly located at spaced intervals along surface l5. Next, the tightening of the helix as it is twisted about its own axis, much as a spring is wound, causes some reduction of its internal diameter. In certain Cases the drawing-out step may be limited to these two phases. If, for example, the helix has an initial inside diameter d which is substantially equal to the outside diameter of the surface over which the fin is to be applied, then its reduction in the foregoing manner may be entirely adequate to cause the inner edge of the fin tightly to engage the surface. Where, however, the helix must be passed over any considerable enlargement at the end of the barrel, then the drawing-out step will include a further component, namely, an actual drawing and thinning of the outer edge of the strip as it is progressively squeezed between the irons. This action produces a lengthenin of the outer edge of the strip, and the helix immediately adjusts itself to this new condition by contracting until its inner edge engages the surface of the barrel in the desired way. In the case under discussion the diameter of the shoulder M was one-quarter of an inch greater than that of the surface I5, while in another instance the difference amounted to as much as fiveeighths of an inch. In both cases the fin was drawn sufficiently to make its inner edge tightly hug the smaller diametered cylindrical surface of the barrel. Whatever the character of the action may be, it results in an actual reduction of the diameter of the helix which is of such extent as to cause the inner edge of the strip [6 tightly to engage the surface of the barrel in the desired way. For purposes of description and claiming,

this action will .be referred to as a drawing-out of the fin.

The drawing operation proceeds in the foregoing manner until the ironing tools reach the position shown in dotted lines in Fig. 4, at which time the machine is brought to a stop. At this point, and while the major portion of the strip is still held in its tightened condition by its engagement with the tools 25, 26, the hook 38 at its trailing end is inserted in a slot 39 of a clamp 40 (see Fig. 6) the clamp is fitted over flange I3 of the barrel and is advanced manually along that flange in such a way as to draw the trailing end of the strip tightly to the barrel; and the trailing end is then secured in fixed relation to the barrel by turning down a set-screw 43 of the clamp. In many cases this completes the drawing-out step, and the tools may be backed away from the barrel. Before doing so, however, it is desirable to lessen the tension of spring 3| so that the tools will have no tendency to pull away the strip from the barrel in the backing-off operation.

It has been found in practice that the strip has a tendency to heel over when it is first drawn between the tools; and that this can readily be corrected by a repetition of the operation. In order to simplify the repeat step, it is preferred that, when the tendency to heel first appears, the strip be caused to turn away from the direction of movement of the tools, so that its convolutions will lie in the positions shown in Fig. 13. If this is done, then upon completion of the rundown of the tools in the direction indicated by the arrow (Fig. 13), and after the trailing end of the strip has been secured to the barrel by clamp it, it is only necessary to reverse the machine to cause the strip to be drawn in the opposite direction. In this runback over the barrel the ironing tools will lift each convolution without interference from the next adjacent one, and without any change in adjustment will complete the drawing operation and cause the strip to assume a substantially perpendicular position on the surface of the barrel. Under these circumstances the drawing operation will be completed at the end of the runback and the tools may then be withdrawn after first loosening the spring 3i, as heretofore mentioned.

It has also been noted, particularly with barrels of larger sizes, that the strip does not assume a position tangent tothe suriace:.l5 immediately opposite the ironing tools, but first touches the barrel at a point some two or three inches behind the tools, as is shown in Fig. 14. If this condition tends to cause any inaccuracy in the locating and proper spacing of the convolutions of the fin, the defect may readily be corrected by engaging the strip between the surfaces of a pair of guide-rolls mounted on the end of an arm 16 which is pivoted at 11 to an upright E8. The upright is secured to the traveling carriage of the machine so that it will advance the guiderolls along the barrel at precisely the same rate as are the tools 25, 26; and the rolls 15 are preferably urged toward each other by a spring 19 (Fig. 15) so that they may engage the strip tightly enough to lay it on the barrel at precisely the desired rate, thereby to assure proper spacing between the convolutions. In the illustrated structure the arm 16 is urged away from the barrel by a spring 80 so that the rolls are normally held in an out-of-contaot position. When it is desired to guide the strip in the manner just described, the arm is lowered by an appropriate movement of a lever 8| having a cam portion 82 which is adapted to engage the arm and press it downwardly.

Upon the completion of the drawing-out step the helical fin l6, held in its tightened condition upon the barrel by the engagement of its ends in the two clamping rings, is ready to be bonded to the surface I5. Where the fin is made of copper, as in the assumed case, it has been found that a low melting point silver solder will serve adequately to secure it to the barrel and at the same time to form a perfect thermal bond therewith. In the preferred method, after first cleaning'and fiuxing both the barrel and the fin, a strip of solder wire 46 of appropriate character is hooked under the leading end of the fin within a notch which has been provided for that pur pose, and the barrel is again rotated whereby to Wind the wire between the convolutions of the fin. During this operation a hand tool may be inserted between the fins and is pressed against the wire whereby to cause that element tightly to hug the surface l5. At the completion. of the winding operation the tail end of the wire may be hooked under the trailing end of the fin within a suitable notch if desired.

It will be recognized'that when the barrel and fin are subsequently heated, the copper of the latter will expand to a considerably greater ex tent than will the steel of the former, and that this differential expansion will loosen the fin. It is desirable, therefore, to apply some means to the fin at this time which will hold its convolutions in the desired spaced'relationsh-ip during the period of looseness. One such means may consist of a cord of asbestos or glass fibre, which is of such size that when wound around the barrel it will fill the space between adjacent convolutions of the fin, wherefore to hold them in place. Another suitable means comprises a series of combs 83 applied to the fins at spaced points, with their teeth 84 engaging the convolutions to hold them in place, as is shown in Figs. 16 and 17. 'In still another instance a quick-setting cement was smeared over the fins, and this served adequately.

The barrel, fin, etc. are now ready to be heated for the purpose of fusing the solder wire. This operation may be performed in an induction furnace, or in any other suitable way. When an induction furnace is employed, it is of importance that the clamping rings and shall be asth-in as possible in order that the current needed for their heating may not be so high as to cause an overheating of the barrel.

It has been noted above that in the heatin operation the copper fin will expand to a greater extent than will the steel barrel. This is of some advantage in that it permits the molten solder to flow under the fin and establish a perfect bond between its inner edge and the surface of the barrel. Insofar as the differential heating tends to loosen the fin, any bad effect is completely offset by the presence of the holding means which were described above. After the cylinder and fin have been cooled, and the solder has thoroughly set, the combs .83 or other holdin means may be stripped away. The results of the bonding operation may be seen in Fig. 5.

It will be recalled that the method includes a final step the purpose of which is to straighten the strip and simultaneously to harden it where that is required. The copper strip of the illustrative case requires both, for at the completion of the bonding step it is usually bad-1y warped and is in almost dead-soft condition. As a preliminary to this step the barrel is again set up on the stub arbor 2| of the machine of Fig. 4, with its driving flange 35 engaged by the driving pin 34 of the face plate; the leading end of the strip is again engaged between the faces of the ironing tools 25 and 26; and the guide-rolls which take no part in the hardening step are moved out of the way. The exact pressure which should be applied to the strip by tools 25 and .26, and spring 3], at this time will again depend .upon the size and character of the strip, and upon the extent of the work which is to be performed in this final step .of the method. If, for example, straightening alone is required, then the tools need do no more than iron the strip, the spring 3| being adjusted accordingly. straightening and hardening are required, as in the assumed case, then the spring must be ad justed to such a point that the tools actually deform the metal of the strip.

The preliminary set-up of the barrel, strip and .tools .in the machine having been completed, that machine may again be started. Obviously, rotation of the barrel around its own axis again results in the drawing of the strip between the faces of the ironing tools, thereby fiattening'and straightening it. Simultaneously, of course, the metal of the strip is progressively squeezed and cold-worked from one end to the other to such an extent as to work-harden it. After the entire strip has been ironed in this way, the machine may be stopped, the tools backed ofl, and

I the barrel l2 removed from the stub arbor. The

driving ring 20 may be removed, as may also the clamp 40, and the two ends of the helical fin may now be cut away. It is preferred, however, that they be retained in the clamps during the straightening and hardening step, so as to assure that the strip will not be pulled away from the barrel during this last-mentioned operation. When this straightening and hardening step has been completed, and the ends of the strip have been cut away, the entire finning operation is complete; and the barrel may be subjected to whatever treatment is required before it is incorporated as a part of a finished engine.

In carrying out the straightening and hardening step of the method, the ironing tools 25 and 26 may be advanced along the barrel by the automatic feed screw of the machine, just as they were advanced during the earlier applying and tightening step. It is preferred, however, that Where both they be driven by the strip itself during this operation, so that they may follow precisely the lead of the strip. This may be done by releasing the carriage of the machine, and the frame 21 which it carries, from the automatic feed screw 36 through any usual clutch device (not shown). Under such circumstances the tools, squeezing the strip between them, must follow the lead of that strip when the barrel is rotated, thereby advancing themselves, frame 21, and the carriage.

It is further preferred, however, that the fin be relieved of the load of driving the carriage and other heavy parts. Thus in the machine of Figs. 4 and 8 it will be noted that the tools 25, 26 are mounted in a U-shaped block 50, which has a pair of trunnions and 52 journaled in the forward ends of the arms 53 and 54 of the forked frame 21 so that the block, and the tools which it carries, may have some limited sliding movement in the frame 21 under certain circumstances hereinafter to be considered. It will also be noted that the block 50 is provided with an arm 55 having a roller bearing 56 on its outer end which rides on the frame 21 to prevent rotation of the block in a counterclockwise direction; and that a stop element 51 has been provided to prevent rotation in the opposite direction.

In setting up the machine to perform the drawing-out step of the method, the block 50 is moved to the position shown in Fig. 4, with its left edge abutting against the arm 53 of the frame 21; and suificient tension is applied to sprin 58 by an adjustment of nuts '59 on the stud portion 60 of trunnion 5!, to hold the block in this established position. With this set-up, frame 21 and block 58 are to all intents and purposes a single unit which can be advanced by feed screw 36 at a desired rate, consequently advancing the tools and performing the locating and drawing-out step of the method in the manner which has heretofore been :described.

Where the machine of Figure 4, is to be employed for carrying out the straightening and hardening step of the method, it is set up in a slightly different way from that just described. Thus, the tension of spring 58 is relieved by unscrewing nuts 59, the frame 21 is disengaged from the feed screw 36 and is backed up to such an extent that block 5!] lies substantially midway between arms 53 and 54; and the feed screw 36 is then re-engaged with the frame through the usual clutch device. It is evident that with this set-up, the frame 21 is adapted to be advanced lengthwise of the barrel by the feed screw 36 in precisely the same way that it was during the earlier fin-applying step. The block 5|] and tools 25, 26 are, however, free to float on trunnions BI, 52, between arms 53 and 54 on the frame 21. These parts are, therefore, advanced along the barrel entirely by the engagement of the tools with the helical strip. In the event that the fin has been retained in the position originally established, the tools will be moved along the barrel in perfect unison with the frame 21. If, however, there has been a slight shifting of the positions of the convolutions of the fin, during the bonding step for example, then the tools will move block 53 in frame 21 so that they may follow precisely the lead of the fin during the hardening step. With this arrangement it is evident that the tools are always driven by the fin during the hardening and straightening step, and yet that fin is completely relieved of the load of .drivingthe.

frame 21, the carriage, and other heavy parts of the machine.

The ironing of the strip during both the drawing-out step and the straightening and hardening one, places a very heavy load upon the tools 25 and 26 in a vertical direction. In order that this load may not be concentrated upon pivot pin 30 for the swinging tool 25, a member 63 (see Fig. 9) is secured to the forward end of the block 50 with its arm 64 overlying the tools 25 and 26 so as to support them. It is evident, however, that vertical support may be provided for the arms in any other convenient and satisfactory way.

The machine is also provided with a quickopening device 61 which facilitates the application of tension to spring 3! when the tools are engaged with the strip at the start of any drawingout or straightening operation, and to relieve the tension of that spring at the completion of that operation. This device may be constructed in any desired way. As here shown, it comprises a pair of collars 68 and 69 (Figs. 4, 10 and 11), of which the collar 68 is mounted to rotate upon a stub shaft 10 carried by the swinging arm 29, whereas collar 69 is keyed at 11 to the shaft so that it may not rotate but have some limited axial movement thereon. The two opposing faces 12 of the collars are cams, wherefore rotation of collar 68 through a quarter turn will move collar 69 outwardly to compress spring 3| or inwardly to relieve the tension of the spring, depending, of course, upon the direction of rotation. When the collars are in the position shown in full lines in Fig. 4, the tension of spring M is verylight, or perhaps non-existent, and hence the tools 25 and 26 may readily be engaged with the leading end of strip It. When that has been done, the collar 68 may be given a quarter turn in clockwise direction by its integral handle 13, thereby moving collar 69 to the right to compress spring 3| and apply its tension to the swinging arm. The machine may then be operated to carry out either the drawing-out step or the hardening one. At the completion of that operation, whatever its character, the collar 68 may be given a quarter turn in a counterclockwise direction to relieve the tension of spring 3|, and allow the tools to be Withdrawn from the strip with a minimum of efiort. With this arrangement it will be apparent that screw 32 and lock-nut 33 need be used only for an initial adjustment of the tension of spring 3| to a desired value for the particular operation to be performed. If, for example, a series of identical fins are to be drawn out on the surfaces l5 of a series of barrels of the same size, the tension of spring 3| may be adjusted by screw 32 at the start of the drawing-out operation on the first of the cylinders, and that adjustment will serve for the entire group. Likewise, if a group of barrels are to have their fins straightened and hardened, a single adjustment of the screw for the first of the barrels is all that is required.

The machine which is illustrated in the drawings is intended for more or less universal use, and the stub 2| and face plate 22 are threaded to the mandrel (see Fig. 4) so that they may readily be removed and another arbor and face plate substituted to receive a barrel of difierent size from the one shown. Of equal importance, the ironing tools 25 and 26 are so designed and arranged that they may be employed to carry out either the drawing step, or the ironing-straightening step of the method, upon fins of different widths and thicknesses. Thus it will be observed that theinnerfacesof, these members are substantially flat; and that the pivot pin 30 about which tool 25 swings has its bearing surface '14 (Fig. 12) formed eccentrically to the portion 85 at its lower end by which the pin is secured to block 50. With this arrangement any rotation of the pin 39 about its seat 86 in the block will move the rear end of tool 25 closer to or farther away from the rear end of tool 26. Thus the tools may be set with their faces at such an angle as to produce a thinning of the outer edge of the strip during a drawing-out operation, for example; or they may be set substantially parallel to one another for the performance of a straight ening-ironing step. Likewise, of course, the positions of the tools may be adjusted to accommodate fins of greater or lesser thickness or various widths.

1n the foregoing the method and apparatus have been described with particular reference to the application of a copper fin to a steel body. The method is not, however, so limited in its character. It may be used for applying a fin of any desired material. If, for example, steel fins are preferred, they may be applied to the illustrated cylinder barrel by the method much more readily and economically than by any presently known practice. Thus, a strip of comparatively soft steel may be reduced to helical form so that it may be fitted over the barrel, and its convolutions may be located and drawn out in exactly the same way as was the copper fin which has already been described. That steel strip may I then be bonded to the cylinder by soldering, or if more strength is required, by a brazing or welding operation. Finally, the strip may be mechanically worked to straighten it, and to harden it if that is required, exactly as heretofore described in connection with the copper strip.

It is likewise evident that my method is not limited to use in applying heat radiating fins to cylinders of internal combustion engines, or in fact to a body having the ends of its cylindrical surfaces bounded by enlarged flanges or shoulders. On the contrary, it is readily applicable to the firming of conventional tubing or other body, and the machine of the present invention may be used for carrying out the several steps of the method in such an application in exactly the way which has been described herein.

Having described my invention, what I claim as new and useful is:

1. In a machine of the character described, a supporting block, a pair of ironing tools having opposing faces for engaging a strip disposed between them, one of said tools being secured in stationary relation to said block and the other being adapted to move towards and away from the stationary one, a projection on said block, a spring disposed between said projection and the movable one of said tools to urge it towards the stationary one, an adjusting screw for varying the tension of said spring and a quick-opening device between said spring and the movable one of said tools, said quick-opening device comprising a stub shaft mounted on said movable tool,

a pair of collars mounted on said shaft with the outer collar engaging an end of said spring, and a key for preventing rotation of said last-mentioned collar while permitting it to slide along said shaft, said collars having opposing cam faces whereby rotation of the inner one will move the outer one to increase the tension of said spring.

2. In a machine of the character described, a supporting block, a pair of ironing tools having substantially fiat opposing faces for engaging a strip disposed between them, means for securing one of said tools in fixed relation to said supporting block, a pivot pin for supporting the rear end of the other of said tools, and spring means for urging the latter tool towards the stationary one, said pivot pin being eccentrically mounted in said block whereby it may be rotated to move the rear end of the pivoted tool towards and away from the rear end of the stationary one.

3. In a machine of the character described, an arbor, means for rotating said arbor about its own axis, a frame mounted alongside of said arbor, a supporting block having trunnions journaled in said frame, said block and trunnions being adapted to slide in said frame in a direction parallel to the axis of said arbor, a pair of ironing tools having their opposing faces adapted to engage the opposite sides of a strip carried on said arbor, spring means for urging said ironing tools towards each other, and other spring means releasably holding said block against sliding movement in said frame.

4. In a machine according to claim 3. characterized by a stud secured to one of said trun- REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 715,180 Trowe Dec. 2, 1902 1,107,005 White Aug. 11, 1914 1,151,721 Sahlin Aug. 31, 1915 1,404,122 Hofuring Jan. 17, 1922 1,639,912 Whittinghain May 31, 1927 1,909,704 Morseth May 16, 1933 1,992,297 Dewald Feb. 26, 1935 2,004,387 Dewald June 11, 1935 2,041,461 Floyd et a1. May 19, 1936 2,087,723 McCord July 20, 1937 2,151,685 Berg Mar. 28, 1939 FOREIGN PATENTS Number Country Date 423,356 Germany Dec. 29, 1925

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