US2003127A - Stretching machine and method of operating the same - Google Patents

Description

May 28, 1935,

A. VAUGHAN Files). Sept. 19, 1932 STRETGHING MACHINE AND METHOD OF OPERATING THE SAME '5 Sheets-Sheet 1 I INVENTOR am AIL-8w,

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STRETCHING MACHINE AND METHOD OF OPERATING THE SAME May 28, .1935. A. H. VAUGHAN 2,003,121

May 28, 9 A. H. VAUGHAN 1 2,603,127

STRETCHING MACHINE AND METHOD OF OPERATING SAME I Filed Sept. 19, 1932 "5 Sheets-Sheet 5 r I i I l IIIIL W @m m INVENTOR May 28,1935. A. H. VAUGHAN 2,003,127

' swamcmue MACHINE-AND METHOD OF ormm me- THE SAME Filed Sept. 19, 1932 5 Sheets-Sheet 4 a 5% vs INVENTOR May 28, 1935.

A. H. VAUGHAN STRETCHING MACHINE AND METHOD OF OPERATING THE SAME Filed Sept. 19, 1932 5 Sheets-Sheet 5 INVENTOR Patented May 28, 1935 STRETCHING MACHINE AND METHOD OF OPERATING THE SAME Arthur H. Vaughan, Salem, Ohio, assignor to The Electric Furnace Company, Salem, Ohio,

a corporation of Ohio Application September 19, 1932, Serial No. 632,799 18 Claims. (01. 153-35) This invention relates to a stretching machine and method of operating the same, and is particularly intended for the stretching of long slender metal articles. It is herein described as particularly applied to the stretching of sucker rods.

In the copending application of Samuel F. Keener, Serial No. 633,778, filed September 19, 1932, there is described and claimed a process of heat treating metal articles such as sucker rods wherein the rods, after quenching and drawing-are engaged near their ends and subjected to a stretching action. The machine which-constitutes the subject matter of this application is particularly valuable in carrying out i the process of the above-mentioned Keener application, although it is susceptible of other uses.

In the stretching of sucker rods or the like it is desirable to permanently elongate or stretch the rods in a definite amount. This cannot be done simply by placing the rods in the grip of engaging means and moving such engaging means to a predetermined distance apart. The rods, although of the same nominal length, will vary somewhat in actual length, and this, cou pled with the fact that they are sometimes slightly crooked because of the quenching step, means that there will be a varying amount of slack to be taken up between the engaging means and the rods before stretching actually commences. It is therefore important to effect a definite predetermined amount of movement of the engaging means one from the other after the slack has been taken up. In the Keener process it is contemplated that the rods will be supplied hot to the stretching machine and they may or may not be held taut while cooling. Where it is desired to hold the rods under tension while giving them an opportunity to cool, it becomes necessary to define the amount of stretching movement as above described and quenching bath. The movement of the fingers then to hold the rod-"under suitable tension while the temperature of the rod is reduced either by natural or artificial cooling. As the rod cools it contracts, and it is important to allow for such contraction while maintaining the desired tension.

These considerations make it preferable to employ fluid means, such as a hydraulic cylinder, for effecting the stretching movement. I provide for controlling the supply of fluid to the hydraulic cylinder in such fashion that there is first supplied fluid under sufflcient pressure to cause stretching, and then after the stretching movement has been effected the pressure plane of Figure 8 and taken on the line is reduced so as to hold the rod under tension, but without further stretching, until it is ready to be released.

In the accompanyingdrawings illustrating a present preferred embodiment of my invention and a modification thereof,

Figures 1, 10., lb and 1c illustrate in a diagrammatic manner respectively a heating furnace, a quench tank, a draw furnace, and a stretching machine which may be used in carrying out the Keener process Figure 2 is a top plan view of the machine partly broken away;

Figure 3 is a view partly in side elevation and partly in section on the line III-III of Figure 2;

Figure 4 is a transverse section on the line IVIV of Figure 2;

Figures 5 and 6 are detail views showing the gripping diesfor engaging the rods, and associated mechanism;

Figure 7 is a diagrammatic view illustrating the control mechanism;

Figure 8 is a vertical section through one of the control valves employed; v

Figure 9 is a section atpright angles to the IXIX of Figure 8; and

Figure 10 is a view corresponding to Figure 7 but showing a modified form of control mechanism.

Referring to Figures 1 through lc there is shown a heating furnace 2 which is supplied from a rack 3 with sucker rods S to be heat treated. When the rods have been brought up to suitable temperature they are taken out of the furnace through an opening 4 and thence supplied to notches 5 in a series of arms 6 on a rock shaft I in a quench tank 8. The rods are held in the bottom of the notches 5 by fingers 9, and while so held are lowered into the 9 relative to the arms 6 is limited by adjustable stops 9?). This construction permits of the fingers constraining the rods against major distortions, while eliminating the possibility of marring them. Of course, if desired, the stops 9b may be adjusted so the fingers will actually clamp the rod, butgenerally this will not be required. The constraint does not entirely. eliminate warping of the rods but holds them sufliciently straight to permit of their being readily handled in the after operations. After quenching. the arms 9a carrying the fingers 9 are moved to the dotted line position in the upper right-hand corner of Figure 1a, thus permitting the quenched rod to be lifted by arms II to a rack l2, from which the rods are supplied to a draw furnace I3. After being raised in this furnace to a drawing temperature, the rods are removed through an opening l4 and supplied to the stretching machine, which is indicated diagrammatically in Figure 1c. The ends of the rod are there engaged by a fixed pair of grips I5 and a movable pair of grips L6. The fixed grips are mounted on a head l1, and the movable grips are mounted on a head l8 which is movable toward and away from the head H by a hydraulic cylinder 28. After the rods have been stretched in this machine they may be allowed to cool naturally why a blast of air or other fluid as indicated at 29.

The machine is illustrated in more detail in Figures 2 to 6 inclusive. It comprises a pair of beams 2| connected by suitable cross members to form a rigid frame. The fixed head I] comprises a main cast body 22 supported on flanges 23 secured to the beams 2|. A series of bolt holes 24 in the beams -2|, and corresponding bolt holes 25 in the casting 22, are provided so that the fixed head may be placed in various adjusted positions along the frame. This is to accommodate the machine to rods of different nominal lengths. I t

The movable head I8 is constructed along similar lines but is carried by rollers 26 so that it can be readily moved back and forth. It is connected to the piston rod 21 of a double acting hydraulic cylinder 28 having a fluid port 29 at one end and a port 33 at the other, so that by supplying fluid to either end, as desired, the head I8 may be moved toward or away from the head |1.

Each of the heads and I8 is arranged to accommodate the grips l5 and I6 shown in more detail in. Figures 5 and 6. Each pair of grips is the same in general construction The grip halves I51; and I60. are fixed-in their respective heads while the grip halves |5b and |6b are slidable therein. The latter halves are secured to slides 3| actuated by toggle links 32. The

toggle links for the grip half |5b are controlled by a double-acting fluid cylinder 33 mounted on the head |1, while the corresponding links for the grip half I61) are controlled by a similar fluid cylinder 34 mounted on the head l8.

The pair of grips I5 is provided with an opening 35 of the proper diameter to accommodate the body of the sucker rod S with clearance. The recess 35 flares into a shoulder portion 36 which, in turn, continues as a recess 31 of enlarged diameter. Reliance is placed upon the engagement of the flared portion 35 of the grip with the shoulder on the sucker rod just inside the wrench portion W for engaging the rod and stretching the same. It will be noted that the wrench portion W is not engaged at all, and that the coaxial recesses 35 and 31 by engaging the body of the rod and the box end B thereof properly aline the same. In like fashion the corresponding recesses in the pair of grips l6 aline the pin end P of the rod with the body. These grips are more particularly described and claimed in the copending application of Frank T. Cope, Serial No. 633,800, filed September 19, 1932, Patent No. 1,958,419, dated May 15, 1934. In order to insure easy placing of the rod in the grips, the shoulder-- portions 36 of the dies are necessarily initially somewhat closer together than are the shoulders on the rod to be engaged. In other words, a certain amount of longitudinal clearance is necessary. This clearance and any slack in the machine (both types of lost motion are herein generally referred to as slack) must be taken up before any stretching commences. It is then desired to stretch the rod in a predetermined amount and, in some cases, to hold the same in stretched position while it is naturally or artificially cooled. One control mechanism for eflecting this is shown in Figure '1.

Fluid under pressure is supplied by apositive displacement pump 38 drawing fluid from a reservoir 39 and supplying it under pressure to a pipe 40 leading to a valve 4|. The purpose ,of the valve 4| is a safety device which limits the amount of pressure supplied to the system, and is hereinafter described in greater detail. The fluid passes through the valve 4| to a pipe 42 and thence to a control valve 43 of the socalled by-passing type. It is provided with a piston 44 actuated by a hand lever 45. When the piston is in the mid position shown, fluid entering through the pipe 42 by-passes freely around the ends of the piston 44 to ports 45 and thence to a return pipe 41, leading back to the reservoir 39. If, now, the control handle 45 is moved to the right as viewed in Figure '7, the fluid passes from the valve 43 to a pipe 48 which terminates in the port 29 of the cylin der 28, thereby applying pressure to the piston and causing the head l8 to move to the right as viewed in the drawings. The handle 45 is provided with a latch 49 and fixed quadrant 59 .so that it may be locked in this position.

The construction of the relief valve 4| is illustrated in detail in Figures 8 and 9. It com prisesv a body 5| having a chamber 52 therein through which the pipes 4!! and 42 communicate. The upper portion of the chamber is bored out as indicated at 53 to accommodate a piston 54 which is urged downwardly by a spring 55. A stem 56 projects from the bottom of the piston 54 through the chamber 52, and when the piston is in its lowermost position, substantially closes off a passage 51 communicating with a by-pass 58 leading back to the return pipe 41. A bleed 59 is provided in the piston 54 so that the fluid can pass from below the piston to above it. The fluid pressure is thus communicated to a port 50, and thence to the top of a spring loaded valve 6|. The spring 62 of the valve BI is backed by a threaded plug 33 whose position may be adjusted to vary the spring pressure as desired. When the pressure above the piston 54 builds upin an amount sufficient to overcome the pressure of the spring '62, the valve 6| isforced open and fluid leaks through the port 60 past the valve 6| to the valve chamber 61a and thence through a' port 64 to the by-pass 58. The bleed 59 is so small that it cannot immediately equalize the pressure, and in consequence the. piston 54 moves upwardly, withdrawing the stem 56 from the opening 51 and thereby allowing a certain amount of the fluid from the pipe 49 to bypass through the pipe 58 and back to the reservoir 39. The valve 4|, operating in this fashion limits the pressure of the fluid supplied through the pipe 42 and thence to the cylinder .28 to a figure determined by the setting of the spring 32.

When the movement of the head "is first initiated it takes up any slack and then begins to stretch the rod. Up to the time that stretching commences the pressure required to move the head l8 will have been much less than the maximum pressure as determined by the relief valve 4|. As soon as the slack is taken up, the pressure begins to build up in the cylinder 28 and the pipe 48 which supplies it. I take advantage of this fact in actuating a control mechanism which automatically defines the amount of stretching movement. A pipe leads from the pipe 48 to a cylinder 66. The plunger in the cylinder is normally urged downwardly by a spring 61 of such strength that no upward movement (as the apparatus is viewed in the drawings) of the plunger occurs until the pressure in the cylinder 28 begins to build up by reason of the slack having been taken up and the stretching having commenced. At this moment the pressure of the spring 61 is overcome and the plunger of the cylinder 66 thereby forces a roller 68 carried by a liead 69 against the side of a slide block 18. The slide block 18 has an opening therethrough' to accommodate a rod 1| extending from the head l8. The block 18 is normally urged to the left, as illustrated in Figure 7, by a counterweight 12 connected to the block through a cable 13, this movement being limited by a rod 14 on the block 18, which rod extends through a fixed guide 15 and is provided with a stop 16. Up until the time that the roller 68 is forced against the side of the block 18, the rod 1| slides freely through the block, but when the side pressure is applied by the roller 68 the block 18 moves forward with the rod 1|. In consequence the movement of the block from left to right corresponds to the amount of stretch of the rod being treated. A trip 11 lies in the path of the rod 14 and is located at such distance from the end thereof as tobe engaged when the desired amount of stretching has been effected. I prefer to stretch the rods in such amount that they are permanently elongated 1 5" to A" per foot of length.

When the head l8 has been moved in an amount suflicient to impart the desired stretch to the sucker rod, the end of the rod 14 engages the trip 11. This releases an arm 18 which is then rotated counter-clockwise by a spring 19. The arm 18 is secured to the stem ofa valve 88, and the purpose of tripping it is to effect a lowering of the pressure in the cylinder 28, thereby terminating the stretching movement while maintaining in the cylinder a suflicient pressure to hold the rod under tension while it cools. The valve 88 is conheated on one side through a pipe 8| with the chamber in the relief valve-4| above the piston 54. During the stretching operation the valve 88 closes off this pipe, but when the trip 11 is actuated the spring 18 opens the valve and allows fluid to pass'through the pipe 8| and the valve 88 to a pipe 82 which terminates in a relief valve 83. The relief valve 83 is constructed on the same principle as the spring loaded valve 6| but it is set to release at a lower pressure. Any fluid which is passed through the valve 83 discharges into a pipe 84 communicating with the pipe 41. Since the amount of pressure supplied to the system beyond the valve 4| is determined by the pressure above the piston 54 of such valve, and since this pressure, in turn, is determined either by the spring loading of the valve 6| or of the valve 83, it follows that when the valve 88 has established communication between the valves 4| and 83, the last mentioned valve, being set to release at a lower pressure, will supersede the valve 6| in controlling, and the fluid pressure thereafter supplied to the system will be correspondingly reduced. The valve 83 is set to determine a pressure in the cylinder 28 sufficient to holdthe sucker rod in tension but insufficient to stretch the same. When the pressure is thus reduced, the rod is maintained under a predetermined tension, and this despite contraction of the rod by cooling.

It has previously been mentioned that the grips 5 and I6 are controlled by fluid cylinders 33 and 34. Figure 7 illustrates a fourway valve 85 which controls these cylinders. Fluid under pressure such as air from any suitable source reaches the valve through a pipe 86. When the valve. is in the position shown the air pressure is communicated to the pipe 81 and thence to the proper ends of the cylinders 33 and 34 to straighten the toggles 32 and close the grips l5 and Hi. If the four-way valve is moved to the dotted line position, these ends of the cylinders are free to exhaust and air under pressure is supplied to a pipe 88 from which it is communicated to the opposite ends of the cylinders 33 and 34, thus opening the grips. The grips are, of course, closed when a hot rod has been placed in the machine, and the stretching operation, as above described, is then efiected. After the rod has cooled the grips may be opened by actuating the four-way valve 85, and it is then only necessary to remove the stretched rod and return the parts to their original position to stretch a subsequent rod. It is desirable to set the valve 43 to mid-position, thereby releasing the tension on the rod, before the grips are opened.

In order to return the parts to their original position, the valve handle 45 is moved to the position 45a. It is held in such position by a latch 89 actuated by a spring 98 bearing against a fixed guide 9|. With the valve handle in this position fluid under pressure passes from the pipe 42 through a pipe 9|a to theport 38 in the cylinder 28, while the pipe 48 is free to exhaust through the four-way valve 43 to the pipe 41. This shifting of the valve causes the piston to move to the left as viewed in the drawings, thus returning the head to its original position. When this movement takes place, a rod 92 secured to the head 18 slides through an opening in one arm of the lever 18 until a nut 93 on the rod engages the lever in the last portion of the stroke of the head 18 and respring 61 will have moved the roller 68 out of contact. with the block 18 and the weight 12 will have retracted the block 18 to the position shown in the drawings, thus freeing the trip 11 and permitting its spring "(1 to latch it over the lever 18. At the same time an extension 84 on the rod 1| will in like manner actuate the trip 89, thus releasing the handle 45 of the valve 43, whereupon a pair of springs 95 will return the same to its normal central position.

Figure 10 shows a modified form of apparatus wherein parts corresponding to like parts in Figure 7 have been given the same reference character. This form of apparatus involves electrical connections and is of advantage in that the full sequence of operations is automatically controlled and the duties of the op' erator are very much simplified. In this form of the invention the four-way valve 85 is normally urged to the dotted line position of Figur 10 by a spring I00, and in such position air pressure from the pipe 86 is communicated through the valve to the pipes 88, thus holding the dies I5 and I6 in their open position. After a hot rod has been dropped into place the valve 85 is moved 'by the operator to the solid line position of Figure 10, thereby establishing communication between the pipe 86 and the pipes 81", resulting in the dies I5 and I6 being closed. Upon such closing movement the toggles 32 close electrical contacts IOI and I02. The contact IOI is connectedby a wire I03 to the line wire LI. closed, a circuit is established from LI through the wire I03, the contact IOI, a wire I04 and the contact I02 to a wire I05. The wire I05 leads to a normally closed contact I06 and thence through a wire II to an intermediate coil I08 of a magnetic switch indicated generally by the reference character I00. The control circuit is completed through a wire IIO leading to the line wire L2. When the magnet I08 is energized the resistance of a spring III in the switch I09 is overcome and the switch arm H2 is moved from the dotted line position to the solid line position in the drawings. rent is then free to pass through a wire H3 and a wire II4 to the motor II5 of a'so-called thrustor II6. These thrustors are well known articles of commerce and consist each of a small motor driven centrifugal pump built into the piston of a hydraulic cylinder and so con structed as to cause movement of the piston when the pump motor is started. The circuit from the motor II 5 is completed through a wire III.

Thepiston of the thrustor H6 is connected through a link IIB to a lever II9 having an upstanding arm I20 which is connected through a link I2I to the piston 44 of the valve 43. When the thrustor H6 is actuated the piston is moved to the right as viewed in Figure 10, thereby establishing a fluid circuit from the pump 38 through the relief valve M and the pipe 42 to the valve 43 and thence through the pipe 48 .to the'cylinder 28. The valve 43 is normally urged to central position by springs (not shown) corresponding to the springs 95 of Figure'l.

As in the embodiment of Figure 7, it is desired to obtain a predetermined amount of stretching after the slack has been taken up. This is accomplished by the same mechanism as previously described, namely, a sliding block if! biased in one direction by a counter-weight I2, but movable in the other direction with the red II secured to the head I8 when the block is forced into frictional engagement with the red by means of the roller 68.

in this form of the invention the rod I4 which projects from the block I0 is so arranged that'after the desired amount of stretching has been effected it opens the contact I06 thereby breaking thecircuit to the magnet I38 and allowing the spring III to return the I switch arm.II2 to its dotted line position. When this occurs current fiows from the line LI through a wire I22 to a magnet I23. The magnet 23 actuates a latch I24 which releases the handle of the valve BEL-thereby permitting the spring I00 to return the valve to the dotted line position and open the dies I5 and I6 releasing t stretched rod. 'From the magnet I23 the When the contacts IDI and I02 are current flows through a wire I25 to the switch arm I I2, the circuit being completed through the wires H3 and H0. The opening of the contact I06 and the consequent movement of the switch I09 breaks the circuit to the thrustor II6, thereby allowing the valve piston 44 to return to mid-position, immediately relieving the pressure in the cylinder 28 and freeing the rod of tension.

The opening of the grips I5 and I6 closes another circuit which returns the parts to their original position. When the toggles 32 are actuated so as to open the grips they .engage contacts I26 and I2I. Current flows from the line LI through a wire I28 to the switch I26, thence through a wire I29 to the switch I21 and thence through a wire I30 through a normally closed contact I3I. From this contact the current flows through a wire I32 to the motor I33 of a thrustor I34 and thence through a wire I35 to the line L2. The thrustor II5 being out of operation at this time, the thrustor I34 serves to move the arm I20 counter-clockwise, thus moving the piston of the valve 43 to the left, thereby allowing fluid under pressure to flow from the valve through the pipe 9Ia and thence to the cylinder 28, while the other end of the cylinder is exhausted through the pipe 48, the valve 43 and the return pipe 41. When the stretching pressure is relieved, the pressure in the pipe 65 is, of course, correspondingly relieved,- thereby allowing the counter-weight I2 to retract the block I0 and permitting the contact I06 to close. At the end of the inward movement of the head I8, a finger I36 on the rod II opens the contact I3I, thereby breaking the circuit to the motor I33 and leaving all of the parts in readiness for another operation as soon as the stretched rod has been removed and another rod put in position. It will be observed that the magnet I23 is energized at this time, but as soon as the handle of the valve 85 is moved again to the solid line position it is only a moment until'the grips are closed, thereby completing the circuit through the magnet I08 which breaks the circuit through the magnet I23 and allows the latch I24 to function. It is therefore only necessary for the operator to periodically actuate the handle of the valve 85, the entire sequence of operation being thereafter automatic.

The advantages of my invention arise from the provision of mechanism which expeditiously and automatically actuates the several parts of the stretching machine, thereby efiecting rapid and accurate stretching of the rods or other articles being treated.

While I have illustrated and described the present preferred embodiment of my invention and a modification thereof, it will be understood that it is not limited to the form shown but may be otherwise embodied or practiced within the scope of the following claims.

I claim:

1. A stretching machine comprising means for engaging at spaced points the article to be stretched, the engaging means being relatively movable, means for applying a stretching force to an engaging means thereby to move the en gaging means and stretch the article, and means actuated uponstretching of the article to reduce the applied force below that required for stretching while continuing to apply sufficient force to hold the article under tension.

2. A stretching machine comprising means for engaging at spaced points the article to be stretched, the engaging means being relatively movable, means for applying force to an engaging means thereby tomove the engaging means to take up slack and thereafter stretch the article, and means efiective after the slack has been taken up for defining the amount of stretching movement irrespective of the amount of slack taken up.

3. A stretching machine comprising means for engaging at spaced points the article to be stretched, the engaging means being relatively movable, means for applying force to an engaging means thereby to move the engaging means to take up slack and thereafter stretch the article, and means movable with the engaging means but only after the slack has been taken up, said means being effective for defining the amount of further movement of the engaging means.

4. A stretching machine comprising means for engaging at spaced points the article to be stretched, the engaging means being relatively movable, means for applying fluid pressure to an engaging means whereby to move the engaging means and thereby stretch the article, and means actuated by the stretching movement to reduce the fluid pressure and thereby stop the stretching movement.

5. A stretching machine comprising means for engaging at spaced points the article to be stretched, the engaging means being relatively movable, a fluid cylinder for effecting such relative movement, means for supplying fluid at a pressure suflicient to cause stretching of the article, and control means for reducing the fluid pressure after a predetermined amount of stretching.

6. A stretching machine comprising means for engaging at spaced points the article to be stretched, the engaging means being relatively movable, a fluid cylinder for effecting such relative movement, means for supplying fluid at a pressure suflicient to cause stretching of the article, a pressure relief valve, and means for actuating the same after a predetermined amount of stretching, whereby to automatically reduce the fluid pressure.

7. A stretching machine comprising means for engaging at spaced'points the article to be stretched, the engaging means being relatively movable so as to take up slack and upon continued movement effect stretching of the article, a fluid cylinder for effecting such relative movement, means for supplying fluid under pressure to the cylinder so as to take up the slack and cause stretching, a pressure relief mechanism, a member associated therewith for actuating the pressure relief mechanism after a pre-'- determined amount of movement of such member, and means for initiating movement of such member when the slack is taken up and the stretching commences.

8. A stretching machine comprising means for engaging at spaced points the article to be stretched, the engaging means being relatively movable so as to take up slack and upon continued movement effect stretching of the article, a fluid cylinder for effecting such relative movement, means for supplying fluid under pressure to the cylinder so as to take up the slack and cause stretching, a pressure relief mechanism, a member associated therewith for actuating the pressure relief mechanism after a predetermined amount of movement of such member, and

means actuated by the increase in pressure in the system incident to the commencement of the stretching step for intiating movement of said member.

9. A stretching machine comprising means for engaging at spaced points the article to be stretched, one of such means being mounted on a movable head, means for moving the head so as to take up slack and stretch the article, and means for defining the amount of stretching movement, the last mentioned means having a control member adapted to be engaged with and moved by the head and also having means actuated upon taking up of the slack for bringing the control member into operative engagement with the head.

10. In the method of operating a stretching machine having relatively movable engaging means for holding an article to be stretched and means for effecting such relative movement, the steps consisting in supplying an article to the engaging means, eifecting relative movement thereof to take up slack, continuing the movement in an amount to give a predetermined stretch, and holding the article temporarily in tension irrespective of the slack taken up.

11. In the method of operating a stretching machine having relatively movable engaging means for holding an article to be stretched and means for effecting such relative movement, the steps consisting in supplying an article while hot to the engaging means, efiecting relative movement of such means to take up slack,

continuing the movement in an amount to give a predetermined stretch to the article irrespective of the slack taken up, and holding the article in tension until the temperature is reduced to a desired point.

12. In the method ofi operating a stretching machine having relatively movable engaging means for holding an article to be stretched and fluid pressure means for effecting such relative movement, the steps consisting in supplying to the engaging means an article to be stretched, applying fluid pressure sufllcient to take up the slack and stretch the article, continuing the application of such pressure for a suflicient time to impart a desired predetermined stretch to the article irrespective of the slack taken up, and. then reducing the pressure so as to stop the stretching movement while maintaining the article in tension.

13. In the method of operating a stretching machine having relatively movable engaging means for holding an article to be stretched and means for effecting such relative movement, the steps consisting in supplying an article to the engaging means, effecting relative movement thereof in an amount suflicient to take up all of the slack, and continuing the movement in an amount to give a predetermined stretch to the article in addition to and irrespective of the slack taken up.

14. In the method of operating a stretching machine having relatively movable engaging means for holding an article to be stretched and means for effecting such relative movement, the steps consisting in supplying an article to the engaging means, eifecting relative movement thereof to take up slack, continuing the movement in an amount to give a predetermined stretch irrespective of the slack taken up, and

maintaining a predetermined tension on the machine having relatively movable engaging means for holding an article to be stretched and means for effecting such relative movement, the steps consisting in supplying an article to the engaging means, eflfecting relative movement thereof to take up slack, continuing the movement in an amount to give a predetermined stretch irrespective of theslack taken up, and holding the article under predetermined tension until the temperature is reduced to a desired point.

16. In the method of operating a stretching machine having relatively movable engaging means Ior holding an article to be stretched and means for efl'ecting such relative movement, the steps consisting in supplying an article to the engaging means, eilfecting relative movement thereof to take up slack, and continuing the movement in an amount to give a permanent elongation of to V4" per foot of length of the article irrespective of the slack taken up.

17. In the method of operating a stretching machine having relatively movable .engaging means for holding an article to be stretched and means for effecting such relative movement, the steps consisting in supplying an article to the engaging means, effecting relative movement thereof in an amount sufl'icient to take up all of the slack, and continuing the movement in an amount to give a predetermined permanent elongation to the article in addition to and irrespective of the slack taken up.

18. In the method of operating a stretching machine having relatively movable engaging means for holding an article to be stretched and means for effecting such relative movement, the steps consisting in supplying an article to the engaging means, efiecting 'relative movement thereof in an amount sufficient to take up all of the slack, and after the slack has been taken up continuing the movement for a further predetermined distance irrespective of the movement which was required to take up slack, thereby imparting a predetermined permanent elongation to the article.

ARTHUR H. VAUGHAN.

CERTIFICATE OF CORRECTION.

Patent vNo. 2,003,127. May 28, 1935.

ARTHUR H. VAUGHAN. I

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 5, second column,

line 26, ciaim'lfl, strike out the words "irrespective of the slack taken up" and insert the same after "stretch" and before the comma in line 25, of said claim; and that said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 18th day of June, A. D. 1935.

Leslie Frazer Acting Commissioner of Patents.

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