WO1991013773A1

WO1991013773A1 - Improved method and apparatus for making tires and the like

Info

Publication number: WO1991013773A1
Application number: PCT/US1991/001641
Authority: WO
Inventors: Vincent F. Panaroni
Original assignee: Panaroni Vincent F
Priority date: 1990-03-14
Filing date: 1991-03-11
Publication date: 1991-09-19

Abstract

Apparatus and method for producing articles of polyurethane or the like wherein a mold (14) of the article shape is positioned to centrifugally receive polyurethane constituents such that the polyurethane molecules will strike and break against the wall (79) of the mold (14) to provide a resulting smooth non-porous outer skin (85) for the article (84), with additional polyurethane constituents that flow into the mold (14) to provide a foamed interior (86) for the article (84) and may surround a reinforcement system (80) positioned in the mold (14).

Description

unprove_d met_hod & apparatus for making tires & the like

BACKGROUND OF THE INVENTION

Field of the Invention

This invention relates to apparatus and method for processing polyurethane foams to form vehicle tires and the like. Prior Art

For several years now polyurethane foams have been used to produce products having outer integral skins surrounding or partially surrounding a core. It has been recognized, for example, that bicycle tires and wheelchair tires can be produced having an integral skin and a solid core. Such products have gained acceptance because they give a ride that is rather comparable to pnuematic tires while not being subject to loss of air through punctures, blow-outs, etc. The previously known products, however, have been of inconsistent quality, frequently having areas in the finished part which will vary in density. Such density variances, result in inconsistent wear of the tires and will not provide consistent comfortable riding qualities.

More recently, there is disclosed in my U.S. Patent No. 4,855,096, apparatus and a method useable in the production of non-pneumatic tires, and other products having a tough, non- porous, outer integral skin surrounding a foamed inner core with a density varying uniformly from the inside of the tire to the solid, outer skin.

The tire made according to the method of U.S. Patent No. 4,855,096, provides the ride and comfort of a pneumatic tire, while having greater wear-life and is not subject to puncture or blow-out.

In the past, solid polyurethane tires, semi-pnuematic polyurethane tires, solid rubber tires, and solid tires made of other materials, have been proposed. Polyurethane foams have also been used. In all such former tires, however, the variation of density throughout the finished product, together with voids and blemishes in the product surface have greatly limited the acceptance of the products produced. Also, various kinds of reinforcement bands have been proposed for tires, as well as different ways of installing the bands in the tires. The installation of the bands is often slow and costly, however.

Also, while the apparatus disclosed in my aforesaid U.S. Patent is very suitable for making many products some vehicle tires are better formed using a central distribution system to a mold.

SUMMARY OF THE INVENTION Objects of the Invention

Principal objects of the present invention are to provide apparatus and method for producing reinforcement banded vehicle tires from polyurethane foams that have uniformly varying density throughout the cores thereof and integral surfaces free of voids, blemishes and other defects.

Another object of the invention is to produce a non- pneumatic reinforcement banded tire at a cost that will allow such tire to compare favorably in the marketplace with pneumatic tires.

Yet another object is to provide a reinforcement banded, non-pneumatic tire, that is not subject to loss of air as a result of punctures and blowouts, but that will provide the ride characteristics of a pneumatic tire. Features of the Invention

Principal features of the apparatus of the invention include a mold holder, with means to position a two-piece article forming mold thereon and a clamping plate adapted to engage the mold whereby the mold is sandwiched between the mold holder and the clamping plate. The mold holder and clamping plate are mounted to rotate about a common central axis, to thereby spin the mold secured between them. A drive motor is provided to drive a shaft of the mold holder to obtain the desired spinning action.

A resin supply head receives the components of the resinous material used to make the polyurethane foam and supplies the materials through a feed tube that passes through the clamping plate and into a clamped two-piece mold. The two-piece mold has band support pins with a supported expanding reinforcement band thereon. Both the mold pieces are formed from a single master mold.

The mold has a central receiving passage and a distributor plate therein to receive and evenly distribute the polyurethane foam throughout the mold.

The method of the present invention involves a utilization of polyurethane foam mixes that are formulated such that cells of the foam when projected against the surface of a host mold will collapse as the bulk of the foam is forced into the mold and against the cells at the wall. The collapsing cells form a tough, solid, outer skin for the product being molded. The collapse of the cells is more rapidly developed and improved by the rotation of the mold about a central axis. The rotation of the mold also results in a foamed core that is surrounded by the tough outer skin, with the core being of uniformly varying density, throughout the article produced. The speed of rotation of the mold is selected to achieve a desired skin thickness and consistency for the article being molded. It is also possible to use varying speeds of rotation speeds correlated to the various stage of polymer growth so as to enhance the forming mass in the production of molded items with uniform skins that surround uniformly varying inner cores of foam.

The foam mixture used preferably comprise conventional polyisocyanates and polyols and water. Halogenated aliphatic hydrocarbon blowing agents may also be used along with the water. Also, silicone surfactants may be used to maintain a fine uniform stable bubble for cell development. Alternatively, Freon (flourinated hydrocarbons) is added to the mix to provide for proper foaming and uniform density of the core of the product.

A reinforcement band system is pre-formed and is merely set in the mold to become an integral part of the formed tire.

While the apparatus and process are here disclosed as being suitable for the production of vehicle tires, it will be apparent that other items can be produced by changing the shape of the mold used.

Additional objects and features of the invention will become apparent from the following detailed description and drawings, disclosing what is presently contemplated as being the best mode of the invention.

THE DRAWINGS In the drawing:

Fig. 1 is a side elevation view of the apparatus of the invention with the two-piece mold shown centrally mounted on a mold plate;

Fig. 2, a top plan view of the apparatus;

Fig. 3, a front elevation view;

Fig. 4, a perspective view of the two-piece mold of the invention, with mold halves separated and a tire band system positioned to be placed in the mold;

Fig. 5, a sectional view through the two-piece mold; and

Fig. 6, a perspective view of a vehicle tire produced using the apparatus and method of the invention, partially cut-away to show the uniformly varying cross-section of the tire and the band system formed therein.

DETAILED DESCRIPTION OF THE INVENTION Referring now to the drawing:

In the illustrated preferred embodiment of the invention, as shown in Figs. 1 through 3, the apparatus of the invention comprises a mold holder 10, having a support base 11 and a clamping plate assembly 13. A two-piece mold 14 is adapted to be positioned on a mold support base, as will be further described, and a resin supply head 15 is movably mounted to be positioned to supply resinous materials to the mold, also as will be further described.

Resin components and water, as well as such other additives as may be used, i.e., a blowing agent, silicone surfactants and Freon are pumped from suitable reservoirs through respective supply lines 16-20 to a proportioning control valve 21 of standard construction. The resin components and other additives are mixed in the valve 21 and are supplied through a nozzle 22 to the mold. The nozzle 22, like the valve 21, lines 16-20 and pumps and reservoirs (not shown) are conventional and well known in the art.

Valve 21 is mounted on an arm 25 that swings up and down and back and forth on a articulated coupling 25a mounted to a pivoted support arm 37 to enable the valve to be easil positioned by an operator.

The base 11 includes ground engaging legs 26 and 27 interconnected by a rear brace 28 and upright struts 29, 30, 31, 32, and 33 that interconnect the legs 26 and 27 and rea brace 28 with a fixed support arm 34 that carries the suppor base 11 on a cantilevered end thereof.

Uprights 35 fixed at opposite sides of the fixed suppor arm 34 and a diagonal brace 36 rigidly extending from uprigh strut 33 to the fixed support arm, pivotally support one en of a pivoted support arm 37. The pivoted support arm 37, i addition to being pivotally connected at 38 to the uprights 3 has a flange 39 to which ends of short links 40 are pivotall connected. The other ends of the short links 40 are connecte to a pivot axis 41 that has the end of a rod 42 of a hydrauli cylinder 43 pivotally connected thereto. The cylinder housin 44 of cylinder 43 is pivotally connected at 44a to the end o the pivoted support arm 37 adjacent to pivot 38.

Long links 45 each have one end pivotally connected at 4 to a clamp 47 on the fixed support arm and another en pivotally connected to the pivot axis 41.

The mold support base comprises a circular disk 50 havin a downwardly projecting central axle shaft 51 that extend through bearings 52 in the cantilevered end of fixed suppor arm 34 and that has a pulley 53 fixed to the shaft.

A motor 55, is carried by a bracket 56 that is fixed t the upright struts 29 and 30. A belt 58 interconnects pulle 53 and a pulley 57 on the output shaft of the motor such tha operation of the motor will rotate the disk 50.

The clamping plate assembly 13 includes a circular disk 6 sized to conform to disk 50, and having a central projectin feed tube 61 journaled through bearings 62 in the end o pivoted arm 37. A washer 63 surrounds a threaded end 64 of tube 61 and a nut 64a is threaded onto the tube to hold the disk 60 to the arm 37. The disk 60 is thus mounted to rotate with the disk 50, as will be further explained.

Shown in Fig. 5, the bottom of mold 14 has a recess 66 formed in the center thereof below a concave distributor chamber 72, shown in Fig. 4, as described hereinbelow, to receive a pin 66a that projects from the center of disk 50. The pin 66a thus serves as a centering pin to position the mold 14 centrally between the disks 50 and 60.

The mold 14, shown in Fig. 4, is made of a suitable material such as polyurethane, epoxy, silicone, polyester reinforced resins, or of a metal such as aluminum, steel or the like, and is of two parts 70a and 70b. The parts 70a and 70b are each separately molded in a single master mold, with the interiors of the mold halves then being mirror images, except for a receiver opening 71 that is formed through one mold half and a concave distribution chamber 72 formed in the other mold half. The distribution chamber and receiver opening are merely blocked out in the master mold during formation of the parts 70a and 70b. A ring 73 surrounds the receiver opening 72 inside part 70a and a similar ring 74 surrounds the distribution chamber 72. When the mold halves are assembled in face to face relationship passages 75 are formed through the abutting rings 73 and 74 and are aligned to receive polyurethane material spinning out of the concave distribution chamber 72. A circular recess 78 is provided between each of the rings 73 and 74 as is a spaced surrounding outer wall 79 of the mold.

A reinforcement band or cord system, shown generally at 80, may be positioned in the recess 78 as well be further described.

A locking hole 81 is formed in the outer wall 79 of each mold half between the ring 73 or 74 and the outer surface of the mold half.

A locking lug 82 is formed on the outer wall 79 of the mold diametrically opposite the locking hole 81. When the mold halves are assembled the locking hole of one half receives the locking lug of the other half to prevent relative rotation of the mold halves and to hold the mold halves i aligned relationship.

When the mold 14, as shown in Fig. 1, is positioned on th circular disk 50 it receives the pin 66a from the disk int the recess 66.

In operation, the mold 14 is assembled and is placed o disk 50. The cylinder 44 is operated to pivot the clampin plate assembly forward and down about the pivots 38, 46, 41, and 39 until the disk 60 is flush against the mold 14. Th pressure applied by the disk 60 to the mold is determined b the pressure setting of cylinder 44.

The arm 25 and nozzle 22 are then moved to position th nozzle to discharge into and through the tubular feed tube 6 and receiver opening 71 and into the concave distributio chamber 72.

The motor 55 is actuated to rotate the disk 50, mold 1 and disk 60 and valve 21 is actuated to supply the resi components, water and other additives through the nozzle 22.

The resin mix supplied through nozzle 22 and into th concave distribution chamber 72 spins out through the passage 75 and into the recesses 78 to fully fill the recesses and t enrobe a band system 80 placed in the recesses. The rotatio of the mold then causes the initially entering resin mix t impinge on the walls of recesses 78, and in accordance wit the process of the invention, the cells of the impingin polyurethane resin collapse against both the recess walls an the mold outer wall 79 to form a tough outer surface withou pores or voids and the cells of the subsequently enterin resin provide a foamed inner core. The pores of which inne core will vary uniformly from the outer wall of recesses 78 t the center thereof with the smallest pores adjacent the oute skin and the largest pores adjacent to the recess center.

A pair of lamp holders 90 and 91 are shown in Fig. 1 mounted at opposite sides of pivoted support arm 37 and lamp 92 threaded into the usual sockets in the lamp holder ar directed against the disk 60. The lamps are to provide necessary heat for curing the resins used in practicing the method of the invention. Similarly, lamp holders 93 and 94 mounted at opposite sides of the fixed support arm 34 that receive lamps 92 turned therein, provide an arrangement for directing heat from the lamps against the disk 50 to further provide necessary heat for curing the resin inside the mold 14. The lamps 92 in the holders 90, 91, 93 and 94 can be separately actuated or can be actuated by operation of motor 55.

After a product has been formed and cured in the mold 14, the mold is removed from the mold holder, the parts 70a and 70b are separated and the cured product, formed in the recesses 78 is pulled from the mold. The part formed in the herein described mold is a solid vehicle tire.

The motor 55 may be a variable speed motor that can be used to selectively change the speed of rotations of the disks 50 and 60 and a mold 14 positioned between them.

The method of the invention is best performed using the apparatus heretofore described.

In practicing the method, the usual polyurethane foam material, consisting of conventional polyisocyanates and polyol in an amount sufficient to fill the mold are supplied to receiver opening 71 of the mold 14, as through the valve 21 and nozzle 22 and water is added to the mix. While it has long been believed that addition of water to a polyurethane foam will cause excessive foaming and a weak and unstable mass, it is important to the present invention that extraneous water be added to the mixture. The extraneous water serves as a reactive polyol and reacts with the polyisocyanate to create carbon dioxide gas which yields an increased expansion pressure greater than is normally experienced during processing of urethane. This, when coupled with the controlled speed of centrifugal spinning during the critical foaming stages of the generated foaming polymer mass, allows the foam to produce uniform skins around a cellular inner core of the part being produced. With the use of the extraneous water, concurrently with the spinning of the mold, a remarkable strength increase in the product is achieved. The resulting product has an outer skin with zero pores and with the porosity of the material increasing uniformly from the interior of the outer skin to the innermost portion of the tire.

In practice it has been found that some suitable tires can be processed using uniform rotational speeds of between one hundred fifty and three hundred (150-300) RPM.

It has also been found that a more dense product suitable for more uses can be produced utilizing varying rotational speeds. This is accomplished, for example, if a high speed of rotation such as four to five hundred (400-500) RPM is applied during the initial introduction of the urethane system into the mold, i.e., for a period of one to three seconds; the speed is then reduced for three to nine seconds; and is then increased again for three to nine seconds before being slowed until the cure of the formed product is complete.

The temperatures at which the foam material is cured also affects the density and porosity of the product. It has been found that by maintaining the molds used at a temperature of between ninety degrees and one hundred ten degrees (90-110°⁾ Farenheit and preferably at one hundred degrees (100°F.) Farenheit the cure time will allow for proper impingement of the material onto the walls of the molds so as to form the hard, impervious outer skin and the foamed inner core. It has also been found that the controlled addition of a foaming agent, such as Freon 11 (trichloro-flouro Methane) will permit controlled changes in the size of the voids present in the foamed core.

In a typical process, as used to make vehicle tires for example, twenty-five one hundredths percent (0.25%) by weight of water is added to the urethane foam constituents and two to six percent (2-6%) by weight Freon 11 is added. The constituents are mixed at a nozzle as they are pressure injected into a mold. The mold is then rotated at approximately two hundred fifty (250) RPM for about twenty- eight (28) seconds until the product is cured, whereupon it is removed from the mold. The resultant tire product 84 (Fig. 6) has a uniform, non-porous outer surface 85 that is essentially free of voids and blisters and an inner core 86 of foamed material. Strings or cords, preferably of nylon and/or polyester or steel, provide increased radial strength for the tire if used and molded into the formed tire.

The band system 80 shown in Fig. 4, is particularly suitable for providing reinforcement for a tire produced in the mold 14. The band system includes a ring-shaped band 97 made of nylon or other suitable tire reinforcing material and having a width that is dependent on the size of the tire being produced and a plurality of elongate spacer pins 98. Each spacer pin includes a bifurcated clip 99 is elongate and is formed on one end thereof to clip to a side of the band 97. The band 97 includes a female receiver latch member 100 and a male receiving latch member 101 that cooperates to hold the band in a circular configuration.

In use, a plurality of spacer pins 98 are spaced around the band at opposite side edges. The pins extend inwardly with respect to the band and the band is made to retain its circular configuration. The band system 80 is positioned in the recesses 78 whereby the band 97 will be properly located to provide the desired reinforcement for the formed tire, extending into the recesses 78, with the pins engaging the walls of the recesses in both mold halves 70a and 70b. While here shown as projecting inwardly from the band 97 it will be apparent that the pins 98 can be mounted to extend outwardly from band 97 to engage an out wall 79 of the mold 14

While the apparatus and process are disclosed herein as being particularly suitable for production of tires, it should be understood they are suitable for production of other items as well. For example, bowling balls, innersoles for shoes, automobile body parts, and many other.

Although a preferred form of my invention has been herein disclosed, it is to be understood that the present disclosure is by way of example and that variations are possible without departing from the subject matter coming within the scope of the following claims and reasonable equivalency thereof, which subject matter I regard as my invention.

Claims

THE CLAIMS I Claim:

1. Apparatus for producing products using polyurethane foams comprising a support base; a distribution plate assembly carried by the support base, said distribution plate assembly including a disk and means to center a mold on said disk; a clamping plate assembly having a disk with a central feed opening therethrough; a mold having means on a bottom thereof to center said mold on the disk of said distribution plate, a receiver opening of said mold positioned to align with said central feed opening through said clamping plate disk, with tire forming cavities in the mold, and a receiver surface inside said mold that are positioned to receive polyurethane resin components received through said receiver opening and to spin them into said tire forming cavities; means mounting the clamping plate assembly to move said disk thereof into and out of clamping engagement with said mold; means mounting said disk of said distribution plate assembly to allow said disk to pivot about its central axis; and means for rotating said disk of said distribution plate assembly about its central axis and to thereby rotate said mold and said disk of said clamping plate assembly.

2. Apparatus as in Claim 1, wherein the mold is separable into two parts to facilitate removal of product therefrom.

3. Apparatus as in Claim 2, wherein a band system is provided for location in the tire cavity to be surrounded by polyurethane resin and to provide internal reinforcement for a tire formed in said mold.

4. Apparatus as in Claim 3, the means mounting the clamping plate comprises a pivoted support arm and pivot links that are interconnected to the support base and said pivoted support arm; and motor means for pivoting said pivoted support arm and said clamping plate.

5. Apparatus as in Claim 4, wherein the means mounting the clamping plate includes a hydraulic cylinder.

6. Apparatus as in Claim 1, further including means to heat the mold and resin components therein to a desired temperature.

7. Apparatus as in Claim 6, wherein the means to heat the mold and resin components therein comprises heat lamps carried by the support base and the means mounting the clamping plate assembly to move the disk thereof into and out of clamping engagement with said mold.

8. Apparatus as in Claim 1, wherein the central feed opening through the clamping plate disk is a tube journaled to the means mounting the clamping plate assembly to pass polyurethane resin components from a nozzle of a resin supply head to the receiver opening of the mold.

9. Apparatus as in Claim 8, wherein the resin supply head is mounted on an arm to the means mounting the clamping plate assembly so as to move up and down and from side-to-side.

10. Apparatus as in Claim 1, further including a band system for placement in the mold tire forming cavities composed of a circular band formed of reinforcement material with a plurality of pin means for releasably attachment to said circular band; and means for adjusting the diameter of said circular band.

11. A method for producing non-pneumatic tires and the like comprising supplying polyurethane materials composed of polyisocyanates, polyol and added water and fluoro carbons through a mixing valve and nozzle and into the center of an upper surface of a mold circular distribution surface; rotating said distribution surface in a horizontal plane abou a central axis at a speed of rotation that is sufficient t move the polyurethane materials centrifugally to the edge o said distribution surface and into a tire cavity of said mol and into inpingement with the interior wall of said mold; an continuing the rotation of said distribution surface as sai mold is filled and during the cure time of said polyurethan materials.

12. A method as in Claim 11, wherein the water is abou twenty-five one-hundreths of the weight of the polyurethan materials.

13. A method as in Claim 12, the fluoro carbons compos about two to six percent by weight of Freon in th polyurethane materials.

14. A method as in Claim 11, further including installing a band system within and around the interior of the walls of the mold forming the tire cavity to be surrounded by the polyurethane materials.

15. A method as in Claim 11, wherein the distribution plate is rotated at one hundred fifty to three hundred revolutions per minute.

16. A method as in Claim 15, wherein the temperature of the mold and the polyurethane materials is maintained at between ninety and one hundred ten (110) degrees Farenheit during rotation of the distribution plate.

17. A method as in Claim 11, wherein a rapid rotation speed is established during initial movement of the polyurethane materials into the mold to impact said materials against the walls of the mold forming the tire cavity and to collapse the cells of the material whereby a non-porous surface is formed against the tire cavity surface; the speed of rotation is then controlled whereby cell structure is uniformly maintained inwardly of the collapsed cells during product formation; and the speed of rotation of the mold is then increased until the product formed has cured.

18. A method as in Claim 16, wherein the initial and final rotation speeds are between four and five hundred revolutions per minute.

19. A vehicle tire comprising a solid, non-porous ring- shaped outer skin; and a foamed interior within the outer skin, said outer skin and said interior being formed from the same material and having a uniform porosity graduation from zero at the outer skin to more porous at the interior.

20. A tire as in Claim 19, further including a ring of reinforcement material spaced from the walls of the tire and totally enclosed within the tire to provide strength for the tire.

21. A tire as in Claim 20, wherein the ring of reinforcement material consists of a ring having means for adjusting the diameter thereof; and pin means of said reinforcement material for mounting to extend inwardly or outwardly from said ring.