Core Mold And Method For Making Same

Abstract

A core mold is made up of an annular body of substantially H-shaped cross-section, and two annular side portions of semicircular cross-section, the legs of which are bonded to the legs of the body on opposite sides thereof. The resulting core is of substantially oval cross-section, and two recessed areas are formed in the body portion of the core to readily receive tire roll-restraining hoops during assembly of the core. The core elements are pressed in a manner to provide proper shape thereto for assembly of the final core.

Description

BACKGROUND OF THE INVENTION

This invention relates to sand cores, and method and apparatus for producing same, and more particularly, to method and apparatus for producing a core which includes hollow portions and is made up of separate pressed core parts.

U.S. Pat. No. 3,606,921 to Grawey discloses the use of a sand core on which the invention of that patent, i.e., a tube-tire, is formed. In that patent, the sand core, after the formation of such tube-tire, is disintegrated and removed from within the tube-tire.

The problem of the formation of the sand core itself is a serious one, since, because of the extremely great size of such tube-tire to be formed, the core by necessity must be extremely large in overall dimension. Such a large core will, of course, be relatively heavy and unwieldy, so that any saving in weight thereof will aid in the ability to handle such core conveniently. Naturally, even though the weight may be reduced, there can be no sacrifice in overall strength in the core for the purpose for which it is designed.

For these reasons, a hollow core would be quite advantageous in this use, and the apparatus should with advantage be designed to so form such a core.

Such a hollow core, when compared to a solid-type core, also includes the advantage that the volume of material to be semi-cured by gassing is reduced, so that the time required for such step is also reduced. Such saving in time also applies to the final curing of the core. Furthermore, the step of disintegrating and removing the core from within the tube-tire mentioned above will naturally be simpler and less time-consuming, simply because there is less material to flush from within the tire carcass in the case of a hollow core, as compared to a solid core.

It will be understood of course that the method of producing such core, and the apparatus for producing such core should both be relatively simple and efficient.

Of general interest in this area is U.S. Pat. No. 3,584,680 to Le Blanc et al.

SUMMARY OF THE INVENTION

It is an object of this invention to provide a hollow sand core which is assembled by fixing together a plurality of core portions.

It is a further object of this invention to provide a method of properly forming the core portions, so that they may be properly fixed together to define such core.

It is a still further object of this invention to provide apparatus which is capable of properly forming and pressing sand into the shapes and configurations of the particular core parts.

Broadly stated, the inventive core of granular material disclosed herein comprises a body in cross-section defining first and second outwardly extending legs and a depression therebetween, and third and fourth outwardly extending legs, and a depression therebetween. A first side portion in cross-section defines first and second legs fixed to the first and second legs of the body, and a depression therebetween positioned along the depression defined between the first and second legs of the body. A second side portion in cross-section defines first and second legs fixed to the third and fourth legs of the body, and a depression therebetween positioned along the depression defined between the third and fourth legs of the body. Also broadly stated, a method of forming a core of granular material comprises forming a core body defining first and second depressions, forming a first side portion defining a depression, forming a second side portion defining a depression, fixing the first side portion to the body with the depression of the first side portion along the first depression of the body, and fixing the second side portion to the body with the depression of the second side portion along the second depression of the body. Also broadly stated, the apparattus for pressing and forming granular material into a portion of a core comprises base means, a first-projecting press member of generally U-shaped cross-section connected to the base means, first sidewall means positioned along the first press member and supported by the base means, and securable thereto, second sidewall means positioned along the first press member on the side thereof opposite the first sidewall means, and supported by the base means, and securable thereto, a second projecting press member of generally U-shaped cross-section, the first and second press members projecting toward eachh other, and means for moving the second press member toward the first press member inwardly of and between the first and second sidewall means, to press and form granular material disposed between the first and second sidewall means into the portion of the core.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects of the invention will become apparent from a study of the following specification and drawings, in which:

FIG. 1 is an exploded view of the core as disclosed herein;

FIG. 2 is a cross-sectional view of the core shown in FIG. 1;

FIG. 3 is a cross-sectional view of a portion of the apparatus used in forming the core side portions;

FIG. 4 is a cross-sectional view of a portion of the apparatus used in forming the body of the core; and

FIG. 5 is a cross-sectional view of a second embodiment of core.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Shown in FIGS. 1 and 2 is a first embodiment of core 10 made of granular material such as sand. The core 10 itself is made up of an annular body 12, and first and second annular side portions 14,16. The body 12 is generally H-shaped in cross-section, defining first and second outwardly extending legs 18,20 and a depression 22 therebetween, and third and fourth outwardly extending legs 24,26 and a depression 28 therebetween. The legs 18,24 extend in substantially opposite directions, and the legs 20,26 extend in substantially opposite directions.

The side portion 14 defines in cross-section legs 30,32 which are bonded to the legs 18,20 respectively, and a depression 34 therebetween positioned along the depression 22. Likewise, the side portion 16 defines in cross-section legs 36,38 bonded to the legs 24,26 respectively, and a depression 40 therebetween positioned along the depression 28.

The core 10 is of overall toroidal configuration, and is substantially oval in cross-section as shown.

It will be seen that the legs 18,24 are adjacent the inner periphery of the toroidal core 10. These legs 18,24 define annular recessed portions 42,44 respectively substantially along the inner periphery of the core 10.

The initial step in assembling a core 10 from these parts is to install an annular element 46 in the form of a roll-restraining hoop in the annular recessed portion 42 of the body 12. After application of the roll-restraining hoop 46, adhesive is applied to the extending surfaces of the legs 18,20, the side portion 14 is applied thereto. The roll-restraining hoop 46 is thus confined between the assembled parts 12,14. The assembly is then turned over, and after a roll-restraining hoop 48 is applied to recessed portion 44, adhesive is applied to the extending surfaces of the legs 24,26, and side portion 16 is applied thereto, confining the roll-restraining hoop 48.

Apparatus 50 for pressing and forming sand into the body 12 of the core 10 is shown in FIG. 4. Such apparatus 50 includes base means 52 which include part of a press frame 54 which is shown supporting the several parts of the core mold. Although this view is fragmentary, it will be understood that all parts of the apparatus 50 are essentially annular in form since the body 12 being formed is an annular member. A support bracket 56 is one of a plurality of brackets supporting a power mechanism on frame 54 for ejecting the shaped core sections.

An annular projecting press member 58 of generally U-shaped cross-section rests on the frame 54.

First ring means 60 are positioned about the press member, and are supported by the frame 54, and securable thereto. Such first ring means are made up of rings 62,64,66. Second ring means 68 are positioned inwardly of the press member 58, and are also supported by the frame 54 and securable thereto. Such second ring means 68 are made up of rings 70,72,74. The rings 62,70 are bolted to the frame 54. Rings 64,72 are then located atop these rings 62,70 respectively and secured by a plurality of toggle clamps 76. The ring 66 is then bolted to ring 64, and the ring 74 is bolted to ring 72.

At this point, a cavity is formed for receiving a mixture of sand and silicate binder. The loading member 78 of the press is comprised of a welded fabrication 80 which includes an annular projecting press member 82 of generally U-shaped cross-section, the projecting press members 58,82 positioned to project toward each other as shown. An L-shaped ring 84 is attached to the fabrication 80 by a plurality of bolts. This assembly is lowered on top of the core mixture previously placed in the mold cavity, and a box frame member 86 is placed over the upper surface of the loading member 78. A number of long tie bolts (indicated by dashed lines 88) are then inserted from the top through openings, and secured by nuts at the underside of the press frame 54. The nuts attached to the tie bolts 88 are then torqued until the bottom surface of the box frame member 86 is flush with the top surface of ring 66. Thus, the press member 82 is moved relatively toward the press member 58 inwardly of and between the ring means 60,68, to press and form granular material disposed between the ring means 60,68 into the portion 12 of the core.

After the body 12 is formed as outlined above, gas fittings are attached at tube 90 and port 92, and a suitable core gassing agent is supplied simultaneously above and below the core body 12. The gas passes through a plurality of orifices 94, then through the material of the core body 12, and exits through a plurality of orifices 96, hardening the silicate binder mixture and transforming the core body 12 to a semi-cured state. Due to the positioning of the L-shaped ring 84 and an annular protruberance 98 defined within the ring 70, the core body 12 is formed with the annular recessed portions 42,44 described above, which receive the roll-restraining hoops 46,48 adjacent the inner periphery of the finished toroidal core 10. In the formation of the core body 12, the press members 58,82, it will be seen, form the depressions 22,28 described above on substantially opposite sides of the body 12.

At the end of the gas-curing period, the gas lines are disconnected from tube 90 and port 92. Bolts 88 are removed, and the box frame 86 is lifted free. The welded fabrication 80 is removed leaving ring 84 in place, and toggle clamps 76 are released and rings 64,66 are lifted as a unit. Rings 72,74 are then removed as a unit. The power press means exert force through a multiplicity of radially extending arms having upwardly extending bosses at their terminal ends on the underside of the frame 54. The bosses extend through openings in the press frame 54, and are of sufficient diameter to span ports 92. The press member 58 and core body 12 with L-shaped ring 84 still in place is lifted free of the rings 62,70. The L-shaped ring 84 is then removed separately to insure that the reduced section of the core body 12 is not damaged. The core body 12 remains on the press member 58 until later assembly of the completed core 10.

Shown in FIG. 3 is the apparatus 100 for forming and pressing sand into either side portion 14 or 16 of the core 10. The apparatus 100 consists of base means 102 in the form of a frame 104, support brackets 106, and a power mechanism for ejecting the core portions, which may be the same as used in formingg the core body 12. The frame 104 has connected thereto a press member 108 defining a recessed portion of generally U-shaped cross-section. Such press member 108 is made up of a fabrication 110, and a contoured ejector ring 112 placed in an annular channel 114 in the fabrication. Such press member 108, it will be understood, is annular in form. A ring 116 is positioned about the annular press member 108, and a ring 118 is positioned inwardly of the annular press member 108. These rings 116,118 are bolted to the press frame 104 as shown. These rings 116,118 act as sidewall means, between which a measured amount of core sand and silicate binder is distributed. A press member 120 is sized to be in close proximity to the rings 116,118, and has an annular projecting portion 122 of generally U-shaped cross-section, disposed toward the recessed portion defined by the press member 108. A box frame 124 is placed over the press member 120, with its cross members resting on the upper surface of the press member 120.

A plurality of long tie bolts 126 are then inserted through holes in the flange of the box frame 124, to extend through holes in the press frame 104 to be engaged by large nuts below the frame 104. Torquing of the nuts on the tie bolts 126 forces the press member 120 downwardly until surfaces 128,130 are flush and the core portion is pressed and formed between the rings 116,118.

The pressed core material is then gassed from the top and bottom by applying a gassing agent at the tube 132 and at the port 134. Gas enters the core material through orifices 136 and exits through orifices 138 transforming the core to a semi-cured state.

At the end of the prescribed gassing period, tie bolts 126 are removed, and the box frame 124 is lifted free. The press member 120 is then removed and the core portion is elevated on ring 112 by an ejecting mechanism as previously discussed.

It will be understood that the other side portion is formed in an identical manner. The depressions of the side portions are, of course, formed by the projecting press member of the apparatus. In the final assembly of the core, the side portion 14 is fixed to the core body 12 with the depression 34 along the depression 22, so that an annular void 140 is formed. Likewise, the side portion 16 is fixed to the core body 12 with the depression 40 along the depression 28, forming a second annular void 142 in the core 10.

In FIG. 5 is shown a variation of configuration of core, wherein the side portions 14, 16 of the core 144 are similar to those previously described, but wherein the core body 146 is made up of a first body portion 148 in cross-section defining the legs 18,20, and the depression 22 therebetween, and a second body portion 150 fixed to the first body portion 148 and in cross-section defining the legs 24,26 and depression 28 therebetween.

It has been found that, because of the particular construction of the cores described above, the weight of the finally assembled core is approximately one third less than the weight of a solid core of the same dimension. Thus, the cores disclosed herein are much easier to handle than the solid core. The time required to transfer the core parts to a semi-cured state by gassing is somewhat reduced over that for a solid core. This is true because the volume of material to be gassed in either inventive core is considerably less than the volume of a solid core. Final curing time for the assembled core as compared to that for a solid core is reduced in direct proportion to the difference in volume. Additionally, after a completed tube-tire is formed on the core, the time required to flush the core from the tire carcass is also reduced by one third when compared to the same operation for a solid core.

Claims

What is claimed is:

1. A core of material comprising:

a body in cross-section defining first and second outwardly extending legs and a depression therebetween, and third and fourth outwardly extending legs and a depression therebetween.

a first side portion in cross-section defining first and second legs fixed to the first and second legs of the body, and a depression therebetween positioned along the depression defined between the first and second legs of the body; and

a second side portion in cross-section defining first and second legs fixed to the third and fourth legs of the body, and a depression therebetween positioned along the depression defined between the third and fourth legs of the body.

2. The core of claim 1 wherein the first and third legs of the body extend in substantially opposite directions, and the second and fourth legs of the body extend in substantially opposite directions.

3. The core of claim 2 wherein the core comprising the body and first and second side portions is substantially oval in cross-section.

4. The core of claim 3 wherein said core is of toroidal configuration.

5. The core of claim 4 wherein the first and third legs of the body are adjacent the inner periphery of the toroidal core, and define first and second annular recessed portions substantially along the inner periphery thereof respectively.

6. The core of claim 5 and further comprising first and second annular elements disposed in said first and second annular recessed portions.

7. The core of claim 6 wherein the body comprises a first body portion in cross-section defining said first and second legs and the depression therebetween, and a second body portion fixed to the first body portion and in cross-section defining said third and fourth legs and depression therebetween.

8. A method of providing a core of formable material comprising:

forming a core body defining first and second depressions;

forming a first side portion defining a depression;

forming a second side portion defining a depression;

fixing the first side portion to the body with the depression of the first side portion along the first depression of the body; and

fixing the second side portion to the body with the depression of the second side portion along the second depression of the body.

9. The method of claim 8 and further comprising the step of forming the body with the first and second depressions on substantially opposite sides thereof.

10. The method of claim 9 and further comprising the step of providing an annular core body, and annular first and second side portions, together defining a toroidal core.

11. The method of claim 10 and further comprising the step of providing first and second annular recessed portions in the body, formed adjacent the inner periphery of the toroidal core.