|Publication number||US2308825 A|
|Publication date||Jan 19, 1943|
|Filing date||Aug 2, 1940|
|Priority date||Aug 19, 1939|
|Publication number||US 2308825 A, US 2308825A, US-A-2308825, US2308825 A, US2308825A|
|Inventors||Joseph Rawlings John|
|Original Assignee||Rawlplug Co Ltd|
|Export Citation||BiBTeX, EndNote, RefMan|
|Referenced by (22), Classifications (23)|
|External Links: USPTO, USPTO Assignment, Espacenet|
Jan. 19, 1943. w s 2,308,825
PROCESS FOR THE MANUFACTURE OF WALLYPLUGS awue/rvtom Filed Aug. 2, 1940 Shauna/1 Patented Jan. 19, 1943 PROCESS FOR THE MANUFACTURE OF WALL PLUGS John Joseph Rawlings, London, England, assignor to The Rawlplug Company Limited, London,
England Application August 2, 1940, Serial No. 349,524 In the Netherlands August 19, 1939 '7 Claims.
This invention relates to improvements in wall plugs of the kind intended to be inserted in prepared holes in walls or the like in order to provide a secure fastening for screws, nails and like fastening devices, and further relates to improvements in the manufacture of such plugs.
Wall plugs are already known comprising strands of fibrous material arranged longitudinally to form a tube, and held in the tubular form by means of an adhesive. Tubular wall plugs are also already known wherein thin metal wires are combined with fibrous strands, and are woven or plaited into a tubular form, e. g., around a mandrel; such woven or plaited fibrous plugs, with or without the inclusion therein of wires, have been impregnated with various media, such as glue or other suitable adhesive, sodium silicate, or artificial resin.
In such known plugs, the impregnation of the plug has always been obtained either by passing the separate strands of fibre through a bath of the impregnating medium before formation into a plug or by passing the already formed plug through a bath of impregnating medium.
According to the present invention, a tubular wall plug is provided having an inner layer formed either of strands arranged longitudinally side by side, or by a strip of thin metal bent longitudinally to form a tube, and having an outer layer formed of strands which are woven or plaited together, the two tubular layers of strands being held together by means of an adhesive or the like with which all the strands in both layers of the plug are impregnated.
Each tubular layer may comprise only strands of fibrous material, but preferably the outer layer comprises thin metal wires combined with some or all of the woven or plaited fibrous strands. If desired wires may also be incorporated with the inner layer when such layer comprises longitudinally arranged fibrous strands.
The wires may be incorporated with the outer layer of woven or plaited fibrous strands by being woven or plaited therewith or by being twisted around the separate fibrous strands before weaving or plaiting or may be present in such separate fibrous strands before weaving or plaiting in the form of cores. Similarly, where wires are provided in combination with longitudinal fibrous strands to form the inner layer of the plug, they may either be twisted around some or all of the separate strands or may form cores to some or all of such strands.
In the formation of wall plugs in which thin metal Wires, e. g.,. copper wires, are incorporated,
difiiculties have arisen in the withdrawal of the tubular structure from the mandrel on which it is formed, before it is out into lengths, and further disadvantages have been encountered when it has been proposed to avoid the use of a mandrel in that when the tubular structure, unsupported by any mandrel, is impregnated and thereafter dried and hardened, distortion of the tube often results and it is difiicult or impossible to obtain a dried tubular structure of a true circular shape in cross section or with any accuracy to obtain a tubular structure of given definite internal and external diameters.
The disadvantages and difficulties above mentioned are obviated in the manufacture of wall plugs according to the present invention.
In the manufacture of the improved wall plugs in accordance with the invention, the woven or plaited strands. comprising the outer layer of the plug are led in a braiding machine from the usual separate spools or bobbins to the point where they are plaited one over the other, the inner layer of the plug being fed inwardly of the separate strands so that the braiding or plaiting takes place actually around the inner tubular layer. The braiding or plaiting is completed within a closed chamber to which the impregnating medium is fed under a constant pressure.
Thus the impregnating medium is forced into contact with the strands of fibre comprised in the outer layer of the plug at a time when such strands are still separate, i. e., just before they are braided or plaited together, with the result that a complete impregnation into the component fibres of each separate strand of fibre takes place. Since the. impregnating media commonly employed in the manufacture of wall. plugs are ordinarily of a relatively thick and viscous nature, it is obvious that complete impregnation through the fibres form-ing each of the strands cannot be obtained by passing an already plaited tubular structure through a bath of impregnating medium even if the medium is under pressure in such bath. The new process of manufacture accord.- ing to this invention thus provides a considerable advance in respect of the step of impregnation. The other prior known method of impregnation, i. e., that of impregnating the separate strands before they reach the braiding or plaiting point, obviously results in the loss of impregnating medium, accumulation of partially dried and hardened impregnating medium at the point of braiding (which causes frequent stoppages of the machine for removal thereof) and difiiculty in drawing the impregnated strands through the or without the incorporation of metal wires, the
said inner layer may be formed in the known manner upon a mandreklwhich extends inwardly through the braiding machine, the outer layer of strands being braided or plaited around the inner layer while the latter is upon the mandrel,
It has been found that the presence upon the mandrel of this inner layer of longitudinally arranged strands of fibrou material overcomes the diificulty which is usually experienced in attempting to withdraw a Woven or plaited tubular structure from a mandrel owing to the fact that any longitudinal tension applied to a woven or plaited tubular structure results in an increase in the length of the tube and a contraction in its diameter which causes the tube to grip and hold the mandrel. The presence between the mandrel and the plaited or woven tube of the inner layer of longitudinally arranged strands prevents such gripping of the mandrel.
When the inner layer of the improved plug is formed of a strip ofsheet metal of suitable thickness bent to form a tube or cylinder, the said tube or cylinder serves. adequately to maintain to form a tubular structure 5, shown partly in section in Figure 1.
An impregnating medium of the kind previously mentioned isfed into the chamber 4 under pressure from a supply pipe or conduit 6; it will be seen from the drawing that the separate strands 3 of fibre comprising the outer layer of the plug, with or without wires incombination with such strands, are substantially each surrounded by the impregnating mediumv in the chamber 4, thus ensuring complete impregnation Qof each strand just before and also during the time in which it is plaited with the other strands to form the tubular structure 5, by reason of the the composite plug in its true cylindrical shape,
andno mandrel is thus necessary. The inner layer may be formed by leading a strip of sheet metal inwardly towards the chamber in which the outer fibrous strands are braided in an impregnating medium, the said strip passing into this chamber through a collar or die through which it is pulled by any convenient means and by which it is bent and shaped into a tube or cylinder.
In the accompanying drawing,
Figure 1 is a diagrammatic view illustrating the characteristic elements of apparatus for carrying out the process accordingto the invention, applied to the production of a plug having an outerlayer of fibrous strands woven together with or without metal wires, and an inner layer of fibrous strands with or without metal wires, such strands extending longitudinally of the plug Figure 2 is a diagrammatic view illustrating in plan the formation of a wall plug by the apparatus shown in Figure 1, V V
Figure 3 is a view similar to Figure 1, wherein the inner layer of the plug is formed by a thin metalistrip bent to the shape of a tube or cyl inder. 7 Figures 4 and 5, respectively, are diagrammaticviews illustrating the construction of the finished wall plugs produced by the apparatus shown in Figures 1 and 3.
As shown in the drawing, Figures 1 and 2, the improved wall plug may comprise an inner layer formed of longitudinally arranged strands 2 of fibrous material of any suitable kind, e. g., of jute, disposed side by side upon 'a cylindrical mandrel I. If desired, the strands 2 may have metal wires, e. g., thin copper wires, combined therewith, either as cores or twisted around some or allof the individual strands.
The outer layer of the plug is formed by strands ,3,.which may be of fibre alone, but preferably some or all of the strands 3 are combined with thin metal wires. The strands 3 are led in a pressure under which the impregnating medium is supplied.
It is to be understood that the drawing is diagrammaticonly, in order that the invention may be readily and clearly understood, and that for this purpose the dimensions of the strands 3 have been reduced and the size of the entry aperture in the chamber 4 ,ha been exaggerated for the sake of, clarity. It WilI-beappreciated that in this apparatus, as shownin Figures '1 and 3, the aperture through which the separate outer strands 3 and the inner strands 2 or the tube 8' are fed into the impregnation pressure chamber t is considerably smaller than is indicated in the drawing, and is of such dimensions as to be substantially completely filled or occluded by the inward passageof the fibrous strands, in
. order to prevent the escape of impregnating mestant pressure in the chamber 4.
braiding machine of a known kind to a chamber dium through such aperture. In practice, the,
pressure of the impregnating medium in the pres! sure chamber 4 is regulated inrelation to the speed at which thefibrous strands pass into and out of the chamber 4, and is such a speed that the rate of supply of impregnating medium through the pipe 6 is equal to the rate of adsorption thereof into the fibrous strands, thus maintaining a con- In Figure 3 of the drawing, the strands 2 of Figure 1 are replaced by a tube 8 formed by bending a strip 1 of thin sheet metal. Suitable forming or=shaping means are provided as at 9,
' whereby the fiat strip 1 is formed into the tube 8.
As shown in Figures land 3, the improved plug passes directly from the chamber'4, in which braiding of the fibrousstrands 3" of the outer layer of the plug is completed and in whichimpregnation of the strands 3 and alsoof the strands 2 takes place, into a shaping and sizing die H], which is preferably. heated, wherebyla-rod or tube of wall plugisformed of therequired accurate dimensions and of .a true cylindrical shape, and wherebythe impregnating medium is dried and hardened A plurality of suchsizing dies may be provided to reducethe diameterof the plug, if desired, so that accurate meansmay be available for the continuous production-from one machine of plugs'of differing diameters..--
After passing through the sizing dies,-suitable means of any suitablekind are provided for cut-' ting off the desired .lengths of-plug,
I claim: i
1. A process for the braiding together the fibrous strandsiand the m tal wires into a ubu rstructure in said cham anufacture of wall plugs. comprising feeding ap stripof sheet metalto'a shaping die whereby it is bent to form atube; leading a plurality of fibrous strands and a plurality of thin-metal wires to aisubstantially closed chamber, drawing the sheet metal tube through such chamber, maintaining a supply of impreg' nating fluid under pressure in such: chamber,
her around the sheet metal tube, drawing a continuous length of the composite tube thus formed from the said chamber, drying such tube by heating, and cutting it into suitable lengths.
2. A process for the manufacture of tubular wall plugs, comprising leadin a plurality of fibrous strands and a plurality of thin metal wires to a substantially closed chamber, maintaining a supply of impregnating fluid in such chamber, braiding together the fibrous strands with the metal wires into a tubular structure in such chamber, applying pressure to the impregnating fluid in such chamber, drawing a continuous length of impregnated tube from such chamber, drying the impregnated tube and cutting it into suitable lengths.
3. A process for the manufacture of tubular wall plugs, comprising leading a plurality of fibrous strands and a plurality of thin metal wires to a substantially closed chamber, maintaining a supply of impregnating fluid in such chamber, braiding together the fibrous strands with the metal wires into a tubular structure in such chamber around a mandrel passing through such chamber, applying pressure to the impregnating fluid in such chamber, drawing a continuous length of impregnated tube from such chamber, drying the impregnated tube and cutting it into suitable lengths.
4. A process for the manufacture of tubular wall plugs, comprising leading a plurality of fibrous strands and a plurality of thin metal wires to a substantially closed chamber, maintaining a supply of impregnating fluid under pressure in such chamber, braiding together the fibrous strands with the metal wires into a tubular structure in such chamber around a mandrel passing through such chamber, drawing a continuous length of impregnated tube from such chamber through a sizing and shaping die, drying the impregnated tube and cutting it into suitable lengths.
5. A process for the manufacture of tubular wall plugs, comprising arranging a plurality of fibrous strands longitudinally around a cylindrical mandrel, such mandrel together with the fibrous strands arranged around it extending through a substantially closed chamber, leading into said chamber a plurality of separate fibrous strands and a plurality of separate metal Wires, maintaining a supply of heated impregnating fluid in said chamber, braiding together in said chamber said separate fibrous strands and said separate metal Wires to form a tubular structure around the fibrous strands arranged longitudinally around said mandrel, withdrawing the composite layered tubular structure from the mandrel, and cutting it into suitable lengths.
6. A process for the manufacture of tubular wall plugs, comprising leading a plurality of fibrous strands and a plurality of thin metal wires to a substantially closed chamber, maintaim'ng a supply of impregnating fluid in such chamber, maintaining the said fluid under a constant pressure in such chamber, braidin together the fibrous strands with the metal wires into a tubular structure in such chamber, drawing a continuous length of impregnated tube from such chamber, drying the impregnated tube and cutting it into suitable lengths.
7. A process for the manufacture of tubular Wall plugs, comprising leading a plurality of fibrous strands and a plurality of thin metal wires to a substantially closed chamber, maintaining a supply of impregnating fluid within such chamber, braiding together the fibrous strands with the metal wires into a tubular structure Within such chamber, app-lying pressure to the impregnating fluid in such chamber, drawing a continuous length of impregnated tube from such chamber through a heated sizing die, and cutting the dried and sized tube into suitable lengths.
J. J. RAWLINGS.
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|U.S. Classification||87/1, 87/6|
|International Classification||F16B13/00, D04C1/06, D04C1/00, B29C70/52, F16B13/14, B29C70/08, B29C70/04, B29C70/86, B29C70/00|
|Cooperative Classification||D04C1/06, B29C70/085, B29C70/525, B29C70/523, B29C70/865, F16B13/14|
|European Classification||B29C70/08B2, B29C70/52C, B29C70/86A, B29C70/52B, D04C1/06, F16B13/14|