US1815359A - Collapsible tire building core - Google Patents

Description

July 21, 1931. F. D. MASON I COLLAPSIBLE TIRE BUILDING CORE 2 Sheets-Sheet 1 Filed June 4. 1929 July 21, 1931. F. D. MASON COLLAPSIBLE TIRE BUILDING CORE Filed June 4. 1929 2 Sheets-Sheet 2 amen Joe Patented July 21, 1931 U STATES a FREEMAN D. MASON, OF AKRON, OHIO, ASSIGNOR TO THE BRIDGWATER MACHINE COMPANY, OF AKRON, OHIO, A CORPORATION OF OHIO COLLAPSIBLE TIRE BUILDING CORE Application filed June 4, 1929. Serial No. 368,413.

8 This invention relates to collapsible tire building forms and especially core forms of the type in which certain of the segments are hinged upon a rotary chuck or spider and adapted to be swung from a vertical to a 1 Such cores heretofore have commonly been of all-steel construction and breakage of the hinge members has been a common occurrence,espec1ally 1n the larger sizes, on account of the high moment of inertia developed when 15?, the operator, oftenviolently, turns the structure into its horizontal position and it is sud denly arrested bythe hinge stops. This high inertia factor is also encountered in the expanding and collapsing movements of the segjments with reference to each other in this and other types of articulated cores.

' The object of my invention is to reduce this breakage and at the same time provide a highly durable core construction. I have 'found that by making the cores with body portions of a light metal "such as aluminum or magnesium or an alloy in which such metal is the principal constituent, while the tongue portions carrying the hinge members are made of a heavier and stronger metal such as steel, breakage is practically eliminated and the core has the advantages of an all-steel construction without its draw-backs.

Of the accompanying drawings: Fig. 1 is an elevationof a collapsible core,

including the chuck or spider, embodying my I invention in its preferred form, the same be ing shown in assembled or tire-receiving position.

Fig. 2 is a section on line 22 of Fig, 1. Fig. 3 is an elevation, from the right of Fig. 1, of the core in partially collapsed condition. Fig; 1 is an elevation of the segments of a steel base ring for the core, light metal core segments molded thereon being shown in broken lines, this figure illustrating a step in the process of making the core.

Fig. 5 is a cross-section of one of the segments of a modified form of core.

' Referringto the drawings, the finished assembly, shown in Figs. 1, 2 and 3, comprises a hub member 10 secured upon the end of a rotatable, horizontal shaft 11; a core segment 12 hinged at 18,13 on a horizontal axis A A transverse to the shaft 11, to the lower part of the hub member 10; a core segment 14 hinged to one end of the segment 12 at 15, on an oblique axis such as to cause the segment 14 to swing obliquely downward from the plane of the segment 12 when the segment 1 1,

with the segment 12 in its horizontal position of Fig. 3, is swung out of a. tire mounted upon them; a segment 16 hinged to the other end of the segment. 12 at 17 on an oblique axis such as to cause the segment 16 to rise from the plane of the segment 12 in being swung" out of the tire; and a key segment 18 secured upon a pair of supporting rods 19, 19 slidably mounted in apertured guide brackets 20, 20, 21, 21 formed on the plate 10, the key seg ment being connected to the plate 10 by an over-center toggle 22 having a handle 23, for raising the key segment 18 into its core-completing position between the segments 14, 16 and for lowering it out of the tire to permit the other segments, and the tire thereon, to be swung down to horizontal position about the axis 13, in which position they are stopped by shoulders 18*, 13 on the base of core-segment 12 abutting the ears 13*, 13 of the plate 10, as shown clearly in Fig. 3,the stoppage frequently being so violent. because of the unbalanced weight and inertia of the structure, as to cause breakage of the hinge portions of the core segments when the latter areof allsteel construction as heretofore made.

Each of the core segments 12, 14, 16 and 18 comprises a'cast steel base or tongue portion such as the portion 24, Fig. 2, adapted to withstand the wearing action of trimming and other tools, and a body portion such as the portion 25, Fig. 2, of a light and strong metal such as an aluminum alloy, cast upon the base portion and interlocked against movement in any direction with relation thereto.

The casting of aluminum alloys upon and in interlocked relation to steel bodies heretofore has been difiicult and in many instances unsatisfactory, because of breakage of the alloy resulting from shrinkage thereof, es pecially in bodies of such size as a tire-buildmg core.

I have overcome the difiicult-ies and disadvantages in casting an aluminum alloy upon a base ring structure to form the core herein shown, and have provided for an accurate shapin of the core segments, by the procedure v- 11.1 is in part illustrated in Fig. 4.

A base ring is first cast, of steel, with interlocking means on its outer periphery such as the ci'cumferentially and axially interlocl-n ing spaced lugs 26, 26, each of which is formed with lateral flanges 27, 27 (Figs. 2 and 3) to provide a radial interlock. The base ring also is preferably cast with undercut groove 28 extending entirely around its circumference and of greater depth than the height of the lugs 26, to provide additional axial and radial interlock. is also cast with hinge lugs 29, 29 (Fig. 4).

The ring is then roughly machined, after which it is cut through a plurality ofpositions, as at 30, 30 (Fig. 4) 0 pro *ide a plurality of segments, 31, 32, 3o, 34. ments are then heated to approximately the melting temperature of the aluminum alloy to be used for the bodies or" the core sections and are supported in true circular form, the cuts providing gaps between them, and while they are so held they are associated with a suitable sand core and a complete ring of aluminum alloy iscast upon them and allowed to cool and shrink. In shrinking the aluminum alloy causes the gaps between the steel base sections to close, the sand being oromptly removed from the said gaps'after th metal poured, and because of the comparatively short length of the sections the differential of shrinkage between the alloy body structure and the steel base structure is not cumulative throughout the circumference of the structure in the matter of creating breaki stresses in the alloy but only throughout length of the ind' 'dual segments, so such differential is not effective to break tl alloy structure. The fact that t ing lugs 26 are circuin eren'i apart instead of being continuous also contributes to the avoidance of shrinkage cracks and breakage in service of the alloy body at its junction with. the tongue, although I do not wholly restrict myself to this feature.

The annular steel and alloy structure is then machined to final form, with permissi- The ring These seg bly the exception of the hinge lugs and other attachment elements, after which it is out through at 36, 37, 38, 39 to provide individual segments, which are then finished and mounted upon the spider.

The alloy ring is preferably cast with a cavity in each segmental portion by the use of sand cores, and with internal, transverse partitions 40, 41, 42, 43 at the positions of the final cuts, to provide strength at the ends of the sections and to provide a firm support for interlocking steel end plates such as the plates 44, 44 and 45, 45, as to the key segment 18 and the adjacent hinged segments 14 and 16. The plates 44 are secured by screws to the respective segments 14 and 16 and the plates 45 are secured to the key segment 18. Each of the plates 45 is provided with a key 46 running in a radial key-way 47 formed in the end of the adjacent hinged segment and the plates 44', 45 of each pair'are formed with complemental bevels at 48 to interlock the segments together.

I am aware that it has been proposed to use aluminum as the material for tire vulcanizing cores and molds for the benefit of its greater heat conductivity and the greater facility in lifting and transportation afforded by its lightness, and I do not claim such practice broadly. A somewhat different problem is encountered and solved by my present in;- vention in that the collapsible cores or' forms to which it relates are permanentlymounted on rotary supports and not subjected to heat,

so that mere weight is a secondary consideration and thermal conductivity is unimportant, but durability and the overcoming of breakage in. a hinged structure are highly important factors not present in the prior situations and the complete substitution of aluminum for steel would be unsatisfactory as a solution for this problem.

By making a partial substitution and providing a composite structure as described, not only are the requirements of this particular situation fully met, but a somewhat unlockedfor benefit arises in the way of a shifting of the centers of gravity and centers of inertia of the moving masses toward the hinge axis or axes as compared with the all-steel construction heretofore prevalent in these permanently-mounted hinged cores.

Referring to Fig. 1 and considering the two upright core- segments 14, 16, together with their tongue segments 32, 34, it may be assumed that the center of gravity of the segments 16, for example, lies approximately midway of its horizontal boundary planes B, B or on the line B In like manner, the center of gravity of the steel tongue section (neglecting its hinge lug) may be assumed to lie approximately midway of its boundary planes C, C or on the line G which lies considerably below or nearer to the hinge axis AA than does the center line for the aluminum segment 16. If segment 16 were infinitely heavy as compared with seg ment 34, the center of gravity of the combined segments would lie on the line 13 and if it were infinitely light, said center would lie on the line C When both the body and tongue of the segment are made of steel, as

to the hinge axis AA than where both suitable aluminum alloy are cast and tongue and body are made of steel. Since the core structure is symmetrical on opposite sides of its vertical axis, the combined center of gravity of the two composite segments 141, 32 and 16, 3 1 would be at the intersection of said vertical axis with the line D.

These centers of gravity are also the centers of inertia of the moving masses hinging about the axis AA, and a like demonstration applies to those which are mostly negative in gravity as to said axis such as the composite body and tongue segment 12, 33, whose center of gravity and inertia may be assumed to lie at the intersection of the vertical core axis'with a line G lying about midway of the line E which is half-way between the boundary planes E and E of the body 12, and F which is half-way between the boundary planes F and F.

I thereby obtain not only the advantages of lightness and long wear by employing the described composite core structure, but also a hinged collapsible core or form involving much smaller inertia forces acting closer to the hinge 13, 1.3 when the swing-out segments are turned thereon, and closer to the hinges 15, 17 when the segments 14 and 16 are turned on said hinges, thus greatly reducing the amount of breakage experienced in the use of such cores or forms.

In the modification shown in Fig. 5 a ring of steel is cast with an annular flange or web 51 extending from the middle of its outer periphery and two annular shells 52, 52 of a secured on the respective sides of the web as by bolts such as the bolt 53 extending with substantial. clearance through holes such as the hole 54L formed in the web. The steel ring and the alloy shells are formed to interlock with each other at the outer periphery of the structure against outward relative movement of the shells, as at 55, 55, and to interlock with each other at the inner peripheries of the shells against inward relative movement of the shells, as at 56, 56. Each shell is preferably formed with an apertured boss 52 at each bolt, the boss being of such length as to permit a slight springing of the shell by the bolt to permit the latter to tighten the shells and the steel ring in their interlocked relation radially of the structure but to abut the web 51 to prevent an excessive springing of the shells.

The shells and the ring also are preferably interlocked against relative circumferential movement, as by means of dowels such as the dowel 57, mounted in holes which are bored after the shells and base ring are assembled and are plugged, at the ends of the dowels, after the dowels have been inserted. Thus, a completely interlocked, as well as a tight structure is provided.

The steel ring and the alloy shells preferably are machined before being assembled, and after the structure is assembled in annular form it is out into individual core seg ments and the segments are then completed by suitable plugging or capping of their ends and mounted upon the spider. though the light- metal body members 52, 52 are or may be detachable from the tongue portion 50 as described, in this modification as Well as in the main form previously described, the body and tongue portions are permanently associated in each segment, in the sense that they remain united when the segments are moved to collapse or expand the core, and it is not necessary to remove the tongue portion for the purpose of collapsing the core.

Other modifications are possible within the scope of my invention as defined in the appended claims, and the invention may be applied to collapsible tire forms other than the specific type illustrated.

I claim:

1. A collapsible tire-building core structure comprising a segmental core including core segments, one of which is hinged to swing said segments outward, transversely of the normal core plane, and apair of segmen-ts hinged to the first-said segment, said segments having outer body portions made of a metal of the aluminum group to decrease the weight and provide low moments of in ertia centered toward the hinge axes, and inner tongue portions carrying the hinge members and made of a heavy and strong metal, a key segment fitted between the ends of said pair of segments, and a rotary chuck slidingly supporting said key segment and hinged to the first-said core segment.

2. A collapsible tire-building form composed of segments each comprising an outer body portion made of relatively light metal and cast upon an inner portion made of relatively heavy and strong metal which has longitudinally-spaced anchor lugs interlocking withthe metal of the body portion.

collapsible tire-building; core composed of segments each comprlsmg an inner tongueportion made of relatively heavy and.

strong metal and an outer body portion cast thereon and made of relatively light metal the-tongue portion being formed with anchor lugs embedded in the body portion and with. an undercut groove between said lugs for receiving an interlocking Web of the metal of said body portion.

In Witness whereof I have hereuntoset' my hand this 3d day of June,.1929.

FREEMAN De MASON.

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