US 2627378 A
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Description (OCR text may contain errors)
Feb. 3, 1953 P. R. HIRSH 2,627,378
METHOD FOR SECURING A TENSIONED WIRE AROUND CORES Filed June 16, 1949 IN VEN TOR.
19 TTORNE' 7 Patented Feb. 3, 1953 METHOD FOR SECURING A TENSIONED WIRE AROUND CORES Philip R. Hirsh, Montclair, N. J assignor to Look Joint Pipe Company, East Orange, N. J a corporation of New Jersey Application June 16, 1949, Serial No. 99,460
2 Claims. 1
This invention relates to a method for securing a tensioned line around a core, and more particularly to producing a prestressed concrete body such as a pipe, pile, post or the like, having a plain concrete exterior wrapped with a tensioned wire winding.
Among the objects of the invention is to fasten or bind a wrapping of tensioned wire about a core having no metallic parts accessible to which the wire may be anchored. According to the invention, loose turns of a wire are passed around a core to form a snubbing. The free end of the wire and a portion of the wire between the free end and the snubbing turns are fastened, respectively, to a portion of the machine by which the core is rotated and to a loose plate of metal. The loose plate is located against the core and under the snubbing turns The wire is tensioned by a pull exerted upon a loop of the wire between the plate and the snubbing. The applied tension is transmitted to the snubbing turns which are tightened about the core and bear upon and stabilize the plate in fixed position against the core. The wire is then wound about the core in a helix by relatively rotating and translating the core and the tensioned loop of wire with respect to each other. Before the intended length of the winding is completed a second plate is located against the core in advance of the snub- .bing so that the snubbing and following turns of wire will travel over the second plate. When the wire being wound has advanced onto the second plate and the second plate is firmly secured in place against the core by the wire, the wire is fastened to the second plate. Thereafter, the tension on the loop of Wire between the point of fastening to the second plate and the snubbing is relieved and the snubbing is removed by cutting the wire. The wire Winding is held in its tensioned condition solely by its fastenings to the plates which are held secure and immovable by the winding.
Other objects of the present invention will be hereinafter set forth in the accompanying specification and claims and demonstrated by the drawings which show by way of illustration a preferred embodiment of the principle of the invention and the best mode which is contemplated for applying that principle.
In the drawings:
Fig. 1 illustrates the manner in which the first end of the wire winding is secured in place at the beginning of the winding operation;
Fig. 2 is a section transverse of the core as viewed from the right of Fig. l
Fig. 2A is a detail of a connector-restraining device;
Fig. 3 illustrates an intermediate stage of the winding operation;
Fig. 4 illustrates a stage following the placement of a second plate against the exterior of the core;
Fig. 5 illustrates the stage of operation reached when the winding has been completed and the wire is fastened to the second plate;
Fig. 6 illustrates a prestressed core having a wire winding secured in accordance with the present invention; and
Fig. '7 is a longitudinal section of a portion of an end of a concrete pipe about which the wire winding has been placed.
The concrete body or core illustrated in the drawing is in the form of a pipe IEI having no appurtenances to which a tensioned wire winding may be connected. The ends of the pipe are engaged in and by the rings H and I2 which are adapted to be mounted in a machine for rotation. The pipe and the rings are rotated under power and it is indifferent as to the form of the apparatus by which they are rotated, suitable machines for this purpose being well-known.
The rings, together with the pipe or other form of core, are rotated on their axis, and for this purpose the rings may be supported on pairs of rollers 13 and M, as best shown in Fig. 2.
In initially applying the Wire about the core, a few turns of the wire are wrapped around one end of the core to provide a snubbing [5. A loop It of the wire is left rearward of the snubbing and the loop is caused to engage a pulley I! of a tensioning device. may be temporarily fastened by a clamp or by welding I8, or in any other suitable manner, to a part of the machine which is rotatable with the core, such as the ring H, and a portion of the wire adjacent the fastened end is secured to a steel plate I9 or other suitable metallic member, which is located under the snubbing turns It. The order of attachment of the Wire to the machine part or to the plate is immaterial.
Since high tensile steel wire is commonly used for making a prestressed concrete pipe,it is not desirable that any part of the wire which is to constitute a permanent part of the wire wrapping may be excessively heated, as by temperatures incident to Welding, or that the wire be secured in any manner which could weaken the wire. While ordinarily any suitable fastening means may be employed, it is preferable to secure high tensile steel wire to the plate by a device The end of the wire.
of such nature as not to affect the strength of the wire at this location. A steel compression sleeve having hard granular particles lining its bore, when compressed upon a wire, is serviceable for use as a connecting device. A connecting device of this kind is described in the United States Patent No. 2,375,921, and if such a device is used it is necessary to initially thread the wire through the several sleeves which are to be used before the end of the wire is secured to the rotating part of the machine. Such sleeves 20 and 2| are illustrated in the drawing. The sleeve 20 has been compressed upon the wire and has been fastened to the plate 19, by welding. The sleeve 2! is loosely supported on the wire (Figs; 1, 2 and 2A) and the wire is permitted to slide therethrough during the winding operation and until it is to be compressed to seizeuponthe wire (Fig.
At the beginning and during the winding operation, the sleeve 2| is heldv in reserve by a guide which is translated axially of the core at the rate of operation at which the winding progresses. This guide may take the form of a socket member 22, pivotally supported from links 23 2 1 which are pivotally. attached to the hubs or axles of'the pulley Ill. The sleeve 2! is manually relievedfrom the socket22 whenever it is desiredto'cornpress th sleeve and secure it to the wire.
When the end of the wire has been attached to a rotating portion ofthe, machine and also to the plate l9, which is located under thesnubbing, the desired force is. applied, to the pulley I! andthe core is rotated asthe pulley is caused to travel axially of the core, This relativerotation and axial movement of. the core and the pulley Il'with respect to each other may be accomplishedwith any of several machines well known in the art, such, for example, as the one described. in the United States Patent No. 2,375,921, and, therefore, it suihces for the purposes of thepresent disclosure, to illustrate the pull upon the pulley. as being supplied by a weight 25; supported. from the. pulley by a clevis.
25. Theweight 25 1 epresents the application of a constant pull upon, hewire. loop It. As the Winding operation continues, the wire is drawn fromthe source. of supply and wound about the core and into the snubbing turns it and the permanentwinding 2] (Fig. 3). The permanent windingsecurely, holds the plate Win a fixed position. 7
Just prior to the advance of thesnubbing to a position where .the second attachment. of the. winding to the core isv to bemade, a second plate 23 is placed. against. the exterior of the core andthe winding operation is continued with the. snubbing I5 and the. permanent winding 21 advancingover the plate (Fig. 4). The tensioned winding secures thegplate in fixed position.
When the plate 28 has beentraversed by several turns of the permanent winding, the rotation of thepipe is stopped and the last coil of the winding is v secured-to the plate. This may be, accomplished. byjany'. suitable type v of anchoring device. In the. accompanying. draw-.- ing a compreSSibl'e. steel grippingsleeve 2 l, simi;
lar to the sleeve 29, is illustrated. The sleeve 2| is released from the retaining device 22 and fastened to the wire in such a position as to locate the sleeve opposite the fixed plate 28, as illustrated in Fig. 5, by rotating the pipe sufilciently for that purpose. The sleeve 2| or other fastening device may be secured to the plate by weldin and when secured, the tension developed by the pulley is released and the Wire is severed between the fastening device and the snubbing turns. The snubbing turns are subsequently removed. The appearance of the wrapped core is illustrated in Fig. 6, and a detail of a prestressed concrete pipe having a tensioned winding fastened in the manner described is illustrated in Fig. 7.
Whatis claimed is: V
i. In a method for securing a tensioned wire around a core, the steps comprising passing severalturns; of a wire around a core to form a snubbing, fastening the end of the wire and=-a portionof the wire between the end and the snubbing. turns, respectively, to'a portion of the machine. by. which the core is. rotated -andfto a loose plate of. metal,v stabilizing. the. looseplate againstthe. core by tensioning aloop .of the wire.
forward of the fastening to theplate and rear ward of the snubbing. turns,. relatively rotating and translatingthe core and the. tensioned loopof wire and thereby winding the wire about the core and. over asecond plate located against the core in advance of thesnubbing turns, and fastening the wire to the second plate. before, relieving the tension in the wire.
2. In a method for securing atensioned wire around a core, thesteps-comprising passing several turns ofv a. wire around; a core'to form, a" snubbing, threading twocompression sleeves onto" the. wire, fastening the end of the wire toa portion of the machine by which the core is rotated and fastening the first of: the compression sleeves to the wire and the said first compression-sleeve to laloose plateof metal, holding the plate against the core by tensioning a loop of the-Wire-forward' of the plate and; rearward 0f the snubbing turns,
relatively-rotatingand. translating the coreand the tensioned loop of wire and thereby winding.
the wire about the core and over avsecond plate located-against the core. in advance'of the snub bingturns; and fastening; the second of thecompression' sleeves to the 'wireand to thesecond,
plate while mainttininggthe tension in the-wire.
PHILIP R.- HIRSH;
REFERENCES GITED The following. references. are of record in the file of, this, patent:
UNITED STATES PATENTS"