Patent EA-000217-B1 (EA)
Title: Method of injection molding of a tire annular element (variants) and device threfor
Inventor: RAMBACHER JOHN SYLVESTER
IPC: B29L31/00
Filed: 1996-08-29
Abstract: 1. A method of injection molding a circular tire component comprising: (a) heating and mixing an elastomeric material; (b) injecting said elastomeric material into a plurality of runners in a cold plate of a mold assembly; (c) controlling the temperature of said elastomeric material in said runners in said cold plate; (d) communicating said elastomeric material from said runners to a generally circular manifold in a heated mold having opposing mating surfaces; characterized by (e) communicating said elastomeric material from said circular manifold through a landing area to a mold cavity and subjecting said material to shear and contact with the surface of said heated mold so as to increase the temperature of said material from 115 degree C to 165 degree C plus or minus 11 degree C to accelerate the curing of said material; (f) curing said elastomeric material for a period of time; (g) opening said mold; and (h) removing said tire component from said mold. 2. The method of Claim 1 wherein said tire component is a tire tread and said cooling of said cold plate includes providing for the flow of a coolant in passages in said cold plate adjacent each of said runners characterized by said flow being directed from a first position downstream of said manifold to a second position further downstream from said manifold back to a third position adjacent said manifold and then to a position adjacent said first position. 3. The method of Claim 1 further characterized by said tire component being a bead and apex assembly and said bead being placed in said mold cavity and engagable with blades extending outwardly from a radially inner surface of said cavity for supporting said bead during injection of said elastomeric material into said cavity. 4. The method of Claim 3 further characterized by said landing area being in communication with said mold cavity at radially inward positions around said mold cavity to place said bead in tension and coat a radially inner side of said bead with said elastomeric material upon injection of said elastomeric material into said cavity. 5. The method of Claim 1 further characterized by said tire component being cured for a predetermined length of time past the blow point of said material before removal of said component from the mold. 6. The method of Claim 3 further characterized by said blades being positioned so chat the resulting grooves in the bead apex assembly extend in a direction other than the direction of the ply cords wrapped around said bead apex assembly in a tire built with said assembly so that the cords will not be pulled into said grooves. 7. The method of Claim 1 further characterized by said elastoroeric material being communicated to said manifold at a plurality of equally spaced apart runner inlet positions and then communicated through a section of said manifold and a corresponding section of said landing area having a configuration whereby the sum of the pressure drop in said section of said manifold and the pressure drop in said corresponding section of said landing area from said runner inlets to said mold cavity is substantially equal at all positions circumferentially of said mold cavity. 8. The method of Claim 1 further characterized by said section of said manifold being curved from a circular position towards said mold cavity whereby said elastomeric material undergoes a smaller pressure drop in said landing area as it is communicated circumferentially away from said inlet positions. 9. A method of injection molding a circular component of elascomeric material comprising: (a) heating and mixing said elascomeric material; (b) injecting said elastomeric material into a plurality of runners in a cold plate of a mold assembly; (c) controlling the temperature of said elastomeric material in said runners in said cold plate; (d) communicating said elascomeric material from said runners to a generally circular manifold in a heated mold having opposing mating surfaces; characterized by (e) communicating said elastomeric material from said circular manifold through a landing area to a mold cavity and subjecting said material to shear and contact with the surface of said heated mold so as to increase the temperature of said material to accelerate the curing of said material; (f) curing said elastomeric material for a period of time; (g) opening said mold; and (h) removing said component from said mold. 10. The method of Claim 9 further characterized by said circular component being cured for a predetermined length of time past the blow point of said elastomeric material before removal of said component from said mold. 11. The method of Claim 9 further characterized by said elastomeric material being communicated to said manifold at a plurality of equally spaced apart runner inlet positions and then communicated through a section of said manifold and a corresponding section of said landing area having a configuration whereby the sum of the pressure drop in said sections of said manifold and the pressure drop in said corresponding sections of said landing area from said runner inlets to said mold cavity is substantially equal at all positions circumferentially of said mold cavity. 12. A method of injection molding a component of elastomeric material comprising: (a) heating and mixing said elastomeric material; (b) injecting said elastomeric material into a plurality of runners in a cold plate of a mold assembly; (c) controlling the temperature of said elastomeric material in said runners in said cold plate; (d) communicating said elastomeric material from said runners to a generally elongated manifold in a heated mold having opposing mating surfaces; characterized by (e) communicating said elastomeric material from said elongated manifold through a landing area to an elongated mold cavity and subjecting said material to shear and contact with the surface of said heated mold so as to increase the temperature of said material to accelerate the curing of said material; (f) curing said elastomeric material for a period of time; (g) opening said mold; and (h) removing said component from said mold. 13. The method of Claim 12 further characterized by said elastomeric material being communicated to said manifold at a plurality of equally spaced apart runner inlet positions and then communicated through a section of said manifold and a corresponding section of said landing area having a configuration whereby the sum of the pressure drop in said section of said manifold and the pressure drop in said section of landing area from said runner inlets to said mold cavity is substantially equal at all positions along the length of said elongated cavity. 14. Apparatus for injection molding a component of elastomeric material comprising: (a) a mold assembly having a cold plate and a heated mold mounted on said cold plate; (b) an injection apparatus for heating, mixing and injecting said elastomeric material into said mold assembly; (c) a plurality of runners in said cold plate for communicating said material from said injection apparatus to said mold; (d) a generally elongated manifold defined by opposing faces of said mold connected to said runners in said mold; (e) an elongated mold cavity adjacent said elongated manifold defined by said opposing faces of said mold and characterized by; (f) a landing area between said manifold and said mold cavity defined by said opposing faces of said mold and having a narrow opening providing for heating and shearing said material as it is injected into said mold cavity to increase the temperature and decrease the curing time of said elastomeric material. 15. Apparatus in accordance with Claim 14 wherein said generally elongated manifold is connected to said passages at spaced runner inlet positions along said manifold further characterized by said manifold and said landing area having a configuration whereby the sum of the pressure drop in a section of said manifold and the pressure drop in a corresponding section of said landing area is substantially equal at all positions along said elongated mold cavity. 16. Apparatus in accordance with Claim 15 further characterized by said manifold being curved towards said mold cavity between said runner inlet positions whereby said elastomeric material undergoes a smaller pressure drop in said landing area as it is communicated circumferentially away from said runner inlet positions. 17. The apparatus of Claim 14 further characterized by said elongated component being a circular tire component, and said manifold is circular with said mold cavity positioned radially outward of said manifold. 18. The apparatus of Claim 17 wherein said tire component is a tire tread and said cold plate includes cooling passages disposed adjacent said runners further characterized by at least one of said passages extending from a first position upstream from said manifold to a second position further upstream from said manifold, back to a third position adjacent said manifold and then to a position adjacent said first position. 19. The apparatus of Claim 17 wherein said tire component is a bead and apex assembly characterized by said mold cavity having a plurality of spaced blades embedded in a radially inner surface of said mold for supporting said bead of said assembly during injection of said elastomeric material into said mold cavity. 20. The apparatus of Claim 19 further characterized by said blades being inclined in a direction other than the direction of the cords of the plies wrapped around said bead apex assembly in a tire built with said assembly. 21. The apparatus of Claim 20 further characterized by said blades being tapered to facilitate removal of said bead and apex assembly from said mold assembly. 22. Apparatus for injection molding an elongated component of eiastomeric material comprising: (a) a mold assembly having a cold plate and a heated mold mounted on said cold plate; (b) an injection apparatus for heating,