US1294161A - Gromet. - Google Patents

Description

A. C. PRATT.v

GROMET.

APPLlCATlON FILED DEC. 10. 1917.

1 ,294, l 6 l D .7 Patented Feb. 11, 1919.

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GROMET.

Specification of Letters Patent.

Patented Feb... it, 119th Application filed December 10, 1917. Serial No. 206,568.

To all whom it may concern:

Be 'it known that I, ALPHoNso CoMs'rooK PRA'I'I, a citizen of the United States, residing at Deep River, in the county of Mid dlesex, State of Connecticut, have invented certain new and useful Improvements 1n Gromets; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to gromets of the type consisting of a. plurality of convolutions of a single length of wire, each convolution being wound spirally upon the others and the ends of the piece of wirebeing united together as by butt welding.

Such gromets are widely used, more particularl in the manufacture of the shoes of automo ile tires of the type known as straight side tires, wherein one of the gromets is incased within the rubber and fabric near the base of each of the straight sides.

The distinctive feature of the gromet constituting the present invention is that the spirals of the several convolutions of the gromet are not wound upon a core. The common practice heretofore followed in the manufacture of gromets has involved the provision of a complete convolution of straight wire serving as a core, followed by winding successive convolutions spirally upon this core. Usually the gromet has con sisted of seven convolutions, one constituting the core and siX others wound spirally upon this core, the spirals of the six outer convolutions lying side by side. The employment of such a straight convoluti n constituting a core has been essential h reason of the fact that the outer oonvolutions have been wound spirally by hand and a core was necessary to sustain the spirals during the winding operation.

The gromet of the present invention is erably made by machinery, in accordance with a procedure which is distinctive in that the spirals are formed in the wire prior to applying the wire to the gromet, whereas the procedure heretofore followed in the manufacture of gromets by hand has involved spiraling the wire as an incident to its application to the gromet. By reasonof this different procedure, it is possible to make a gromet which is hollow, that is, one

in'which all of the several convolutions of spirally formed wire which constitute the gromet lie upon the surface of the gromet. Thus, a gromet of substantially circular cross-section can be made corresponding closely to those heretofore widely used in automobile tires but having six convolu trons arranged symmetrically about the axis of a-central space, instead of seven convolutions, six arranged symmetrically around a seventh one constituting a core.

Such a hollow gromet of circular crosssection made as above owtlined may be subjected to pressure in any suitable manner to cause it to assume the crosssection of an equilateral triangle, contracting its crosssectional size by taking up the central space. When the pressing devices are so applied that the apex of the triangle is at the outer side of the gromet and the inner side of the gromet is one of the fiat sides of the triangle, a gromet is produced which is well adapted for use in automobile tires. When the hollow gromet of circular cross-section consists of six spirally wound convolutions of a single length of wire, the pressing of the gromet to the desired triangular crosssection causes the wire of. three convolutions to lie side by side at the base of the triangle on the inner side of the gromet, one convolution to take position upon the apex of the triangle and the Wire of the two remaining convolutions to lie between the one at the apex and the row of three at the base. At regular intervals around the circumference of the gromet, one convolution succeeds another at the apex of the triangle and at each other point around the surface of the gromet, but the triangular cross-sectional form of the gromet and the general arrangement of the six convolutions constituting this gromet of triangular form is maintained as above indicated.

An embodiment of the invention is illustrated in the drawing annexed hereto. wherein Figure 1 is a view of the gromet in ele-. vation; Fig. 2 is a detail view of a section of the gromet on an enlarged scale; Fig. 3 is a cross-sectional view of the hollow gromet of circular form, that is, the gromet as originally made and before being sub jected to pressure; and Fig. at is a. similar cross-sectional view of the gromet after it has been subjected to pressure, the section of Fig. i being the line 33 of Fig. 2, so

asawh the gromet in elevation. It consists of a ring or hoop formed from a plurality of convolutions of wire, the wire ofeach of the several convolutions being wound spirally and the two ends'of the wire being butt welded together. Preferably, the gromet consists of six convolutions of the spirally formed wire, the six convolutions being arranged concentrically about the axis of-a central space, as indicated in Fig. 3. The spiral arrangement of the wire in each of the sevral convolutions is indicated in Fig. 2, from hioh it will appear that the several turns of the spirals of the several convolutions of wire forming the gromet lie side by side around the entire circumference of the gromet. y

' After the manufacture of the gromet in the form indicated in Fig. 3 has been completed, the gromet is subjected to pressure to contract its cross-sectional size by taking up thespace at the center of the gromet and the pressing devices employed for this purpose are such as to give the gromet a triangular cross-sectional shape with the apex of the triangle lying at the outer side of the gromet. This cross-sectional shape of the grometis illustrated in Fig. 4, from which it appears that the central space within the gromet has been taken up and the several convolutions of the wire from which the gromet is formed are caused to assume positions wherein three wires lie abreast on the inner side of the gromet, two wires lie side by side and against these three, and a single wire lies at the apex of the triangle. The

apex of the triangle is on the outer side of the gromet and at the inner side is one of the sides of the triangle? The spiralformation of all of the convolutions of the gromet iauses the six Wires tocome successively to he apex position and each of the other positions within the triangle indicated in Fig. 4, but notwithstanding this, the triangular cross-sectional shape of the 1gromet and the arrangement of the wires in t e manner indicated in Fig. 4, is substantially maintained throughout the entire circumference of the gromet. Any suitable mechanism may be employed for pressing the gromet from the cross-sectional shape indicated in Fig. 3 to that indicated in Fig. 4. For instance, a pair of rolls may be employed, one having a V-shaped circumferential groove therein and the other having a flat periphery, means being provided for pressing the rolls together with the requisite force. The use of such a mechanism may result in increasing the circumferential length of the gromet; ordinarily this would not be objectionable as the gromet would be originally made of a size which would allow for this increase. If desired, other forms of pressing mechanism may be employed, wherein the pressure is applied to all parts of the gromet simultaneously, thus avoiding any, increase in the circumferential length of the gromet.

It will be noted by reference to Figs. 3

and 4, that all of the six convolutions of spirally :formed wire constituting the gromet as a whole lie upon the surface of the gromet. There is no convolution constituting a central core upon which the other convolutions are wound, as has been characteristic of groinetsheretoi'ore made. This characteristic of the gromet shown in Fig. 8 permits ofpressing the gromet to the form illustrated in Fig. 4, which is particularly favorable to use of the gromet in the manufactureof automobile tires. The manufacture of gromets in the form indicated with all of the several convolutions lying upon he surface is made possible by giving the wire constituting the several convolutions its spiral formation and killing the metal of the wire so that it will hold its spiral formation, before applying the wire to the gromet, as distinguished from giving. the

' substantially as described.

' 2. A gromet comprising the combination of a plurality of convolutions, each wound spirally, the gromet being formed from a continuous piece of Wire having its ends secured together and being of trian lar crosssection throughout; substantia ly as described.

3. A gromet consisting of six. convolutions of a continuous piece of wire having its ends secured together, each convolution consisting of a succession of spirals, and the gromet being substantially! triangular in cross-section throughout and at each of a multiplicity of points having three convolutions lying side by side on the inner side of the gromet, one convolution lying at the apex of the triangle on the outer side of the gromet and the two remaining convolutions lying between them; substantially as described.

In testimony whereof I ailix my signature.

ALPHONSO COMSTOOK PRATT.

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