Method and apparatus to vent a mold
A method and apparatus for venting a mold for vulcanizing a tire is provided. The mold comprises a plurality of tread segments for forming the tread on a green tire, wherein each of said tread segments further comprises an outer cavity plate having an interior surface and an exterior surface, the cavity plate having a plurality of channels. Each of the channels has a vent hole extending from the channel to the exterior surface of the outer cavity plate, and a rib mounted over the channel. The adjoining surface of the rib mating with the interior surface of the cavity plate, wherein one of the mating surfaces has a roughened surface forming a vent passageway with the interior surface of the cavity plate for venting mold gasses from the interior of the mold to the exterior of the mold. The invention may further include a blade and blade passageway wherein the blade outer surface has a rough outer surface for forming a vent passageway with the blade passageway.
The invention relates to a method and apparatus for venting a vulcanization mold, and more particularly to a vulcanization mold for making rubber products such as a tire.
BACKGROUND OF THE INVENTIONTires have long been manufactured by vulcanization within a tire mold. Typical tire molds have small holes or vents to allow air trapped within the mold to escape. After the tire is vulcanized and removed from the mold, tiny rubber burrs or extensions extend radially outward from the tire. These burrs are formed from rubber trapped within the vents of the mold. These rubber burrs are a waste of rubber, and detract from the appearance of the tire. The removal of the burrs requires an extra manufacturing step. In addition, the mold vents must be periodically cleaned in order to maintain the vents.
Some prior art molds utilize vent holes wherein blocking members are inserted in the holes and function to prevent the burrs. The use of these blocking members while preventing the rubber burrs, have the disadvantage of producing a small mark on the tire surface. In addition, the blocking members must be cleaned periodically or replaced. Thus an improved ventless mold is desired wherein no marks or burrs are formed on the tire.
SUMMARY OF THE INVENTIONThe invention provides in one aspect a mold for vulcanizing a tire, the mold comprising a plurality of tread segments for forming the tread on a green tire, wherein the tread segments can be assembled side by side circumferentially about the green tire, each of said tread segments further comprised of an outer cavity plate having an interior surface and an exterior surface, said cavity plate having a plurality of channels, each of said channels having a vent hole extending from the channel to the exterior surface of the outer cavity plate; each of said channel having a rib mounted thereover, the adjoining surface of said rib mating with the interior surface of the cavity plate, wherein the adjoining surface located about the perimeter of said rib has a roughened surface forming a vent passageway with the interior surface of the cavity plate for venting mold gasses from the interior of the mold to the exterior of the mold.
The invention provides in a second aspect a mold for vulcanizing a tire, the mold comprising a plurality of tread segments for forming the tread on a green tire, wherein the tread segments can be assembled side by side circumferentially about the green tire, each of said tread segments further comprised of an outer cavity plate having an interior surface and an exterior surface, said cavity plate having a plurality of channels, each of said channels having a vent hole extending from the channel to the exterior surface of the outer cavity plate; each of said channel having a rib mounted thereover, the adjoining surface of said rib mating with the interior surface of the cavity plate, wherein the interior surface of the cavity plate has a roughened surface forming a vent passageway with the adjoining surface of the ribs for venting mold gasses from the interior of the mold to the exterior of the mold.
The invention provides in another aspect a method of making a tread segment for use in a mold, the tread segment having a plurality of ribs and lands, the method comprising the steps of: providing a cavity contour plate having an interior surface and an exterior surface, roughing the interior surface of the cavity contour plate to a surface roughness of about 10 to about 40 mils, forming a plurality of channels in the interior surface of the cavity contour plate at the location of the ribs; forming a vent hole in each channel to the exterior surface of the cavity contour plate, securing an inner surface of a tread profile plate to the interior surface of the cavity contour plate at the location of the ribs, and forming the ribs from the tread profile plate.
The invention provides in yet another aspect a method of making a tread segment for use in a mold, the tread segment having a plurality of ribs and lands, the method comprising the steps of: providing a cavity contour plate having an interior surface and an exterior surface, forming a tread pattern of channels on the interior surface of the cavity contour plate; forming one or more slots on the interior surface of the cavity contour plate; mounting a blade in each slot, wherein the outer surface of the blade has a roughened surface.
The invention provides in yet another aspect a mold for vulcanizing a tire, the mold comprising a plurality of tread segments for forming the tread on a green tire, wherein the tread segments can be assembled side by side circumferentially about the green tire, each of said tread segments further comprised of a cavity plate having an interior surface and an exterior surface, said cavity plate having a plurality of slots on the interior surface, one or more blades secured within each slot, an outer surface of said blade mates with an inner surface of said slot, wherein one of said mating surfaces is roughened relative to the other mating surface forming a vent passageway for venting mold gasses from the interior of the mold to the exterior of the mold.
DEFINITIONSFor ease of understanding this disclosure, the following terms are defined:
“Bead” means that part of the tire comprising an annular tensile member wrapped by ply cords and shaped, with or without other reinforcement elements such as flippers, chippers, apexes, toe guards, and chafers, to fit a design rim. The beads are associated with holding the tire to the wheel rim.
“Curing” means the process of heating or otherwise treating a rubber or plastic compound to convert it from a thermoplastic or fluid material into a solid, relatively heat-resistant state by causing cross-linking of the compound. When heating is employed, the process is called vulcanization.
“Elastomer” means a resilient material capable of recovering size and shape after deformation.
“Elastomeric article” is an article that is at least partially made from an elastomer.
“Innerliner” means the layer or layers of elastomer or other material that form the inside surface of a tubeless tire and that contain the inflating fluid within the tire.
“Pneumatic tire” means a laminated mechanical device of generally toroidal shape, usually an open torus, having beads and a tread and made of rubber, chemicals, fabric and steel or other materials. When mounted on the wheel of a motor vehicle, the tire, through its tread, provides traction and contains the fluid that sustains the vehicle load.
“Radial” and “radially” are used to mean directions toward or away from the axis of rotation of the tire.
BRIEF DESCRIPTION OF THE DRAWINGSThe invention will be described by way of example and with reference to the accompanying drawings in which:
The mold illustrated in
A first embodiment of the invention is shown in
Mating with the inner surface 102 of cavity contour plate 16A is the inner mating surface 120 of tread profile plate 16B. The inner mating surface 120 is relatively smooth compared to the mating surface of the tread profile plate 16B. For example, the inner mating surface 120 may have a surface roughness of about 0.015 mm (15 mils). Profile plate 16B is secured to cavity plate 16A via screws 122 so that the mating surfaces 102,120 contact with each other. Then holes 130 are drilled throughout 16A and 16B. The holes 130 are threaded and headless screws (not shown) are inserted (countersunk) therein. The holes13O are located where the ribs 100 will be located. The holes are then filled by welding or other means known to those skilled in the art.
Next, the lands and grooves of the reverse tread profile are milled into the profile plate 16B and cavity plate 16A. Thus, the mating surface where the ribs are joined to the contour plate 16A have a surface roughness forming pathways in the crevices to vent mold gases. The vent gases can escape through the interface 140 of the ribs and contour plate, wherein the interface of the plates 16A,B is located about 0.3 mm above or radially outward of the external contour of the tire. The vent gases are vented through the rib/contour plate interface and down into the channels located underneath the ribs. The channels have vent holes to allow the gases to vent to the exterior surface 112 of the tread segments.
In a second embodiment of the invention, the above description of the steps to form the tread mold segments 16 comprised of the mold cavity contour plate 16a and profile plate 16B are the same, except for the following. The outer mating surface 120 of the profile plate 16B is milled rough with the peaks having a height of about 0.02 mm (20 mils). For example, the outer mating surface may be milled to have a scallop pattern. The peaks are oriented perpendicular to the ribs 100. The adjoining surface of the cavity contour plate is milled relatively smooth, with a surface roughness for example, on the order of about 0.015 mm (15 mils), wherein the peaks are aligned perpendicular to the peaks of the profile plate 16B.
In a third embodiment of the invention, blades 200 may be utilized in the tread segments 216. The blades are used to form the sipes in the tread shoulder. In this embodiment shown in
Inserted within each slot is a metal blade 200 having outer surfaces 201 having a surface roughness of about 0.02 mm (20 mils), but may range from about 10 mils to about 40 mils. The roughened surface of the blade may be formed by knurling or other means known to those skilled in the art. The roughened surface mating within the slot provides a vent pathway to vent the blades. The blades are secured to the contour plate via welds or other means known to those skilled in the art. The backside 270 of the mold cavity contour plate 215 has recesses 275 which allow for welding or securing the blades and further provide a vent passageway for the air venting from the blades.
Mating with the upper surface 220 of cavity contour plate 215 is the inner mating surface 222 of tread profile plate 210. The inner mating surface 222 is relatively smooth compared to the mating surface 220 of the cavity contour plate 215. Alternatively, the inner mating surface of the tread profile plate may be roughened, while the upper surface of the cavity contour plate may be machined relatively smooth. Tread profile plate 210 is secured to cavity plate via screws so that the mating surfaces contact with each other. Then holes are drilled throughout both plates. The holes 130 are threaded and headless screws (not shown) are inserted (countersunk) therein. The holes130 are located where the ribs 100 will be located. The holes are then filled by welding or other means known to those skilled in the art.
Next, the lands and grooves of the tread profile are milled into the profile plate and cavity plate. Thus, the mating surface where the ribs are joined to the contour plate have a surface roughness forming a pathway to vent mold gases. The vent gases can escape through the interface of the ribs and contour plate which is located about 0.3 mm above or radially outward of the external contour of the tire. The vent gases are also vented through the blade/slot interface in the contour plate and out through the backside of the contour plate.
Variations in the present invention are possible in light of the description of it provided herein. While certain representative embodiments and details have been shown for the purpose of illustrating the subject invention, it will be apparent to those skilled in this art that various changes and modifications can be made therein without departing from the scope of the subject invention. It is, therefore, to be understood that changes can be made in the particular embodiments described which will be within the full intended scope of the invention as defined by the following appended claims.
Claims
1. A mold for vulcanizing a tire, the mold comprising a plurality of tread segments for forming the tread on a green tire, wherein the tread segments can be assembled side by side circumferentially about the green tire, each of said tread segments further comprised of an outer cavity plate having an interior surface and an exterior surface, said cavity plate having a plurality of channels, each of said channels having a vent hole extending from the channel to the exterior surface of the outer cavity plate; each of said channel having a rib mounted thereover, the adjoining surface of said rib mating with the interior surface of the cavity plate, wherein the adjoining surface located about the perimeter of said rib has a roughened surface forming a vent passageway with the interior surface of the cavity plate for venting mold gasses from the interior of the mold to the exterior of the mold.
2. The mold of claim 1 wherein the adjoining surface of said channel mating with the interior surface of the cavity plate is located radially outward of the external contour of the tire.
3. The mold of claim 1 wherein adjoining surface of said rib has a roughened surface on the order of about 10 to about 40 mils.
4. The mold of claim 1 wherein adjoining surface of said rib has a roughened surface on the order of about 20 mils.
5. The mold of claim 1 wherein adjoining surface of said rib has a roughened surface formed of peaks and valleys, wherein the peaks are oriented perpendicular to the adjoining surface of said rib.
6. The mold of claim 1 wherein adjoining surface of said rib has a roughened surface having a scalloped pattern.
7. A mold for vulcanizing a tire, the mold comprising a plurality of tread segments for forming the tread on a green tire, wherein the tread segments can be assembled side by side circumferentially about the green tire, each of said tread segments further comprised of an outer cavity plate having an interior surface and an exterior surface, said cavity plate having a plurality of channels, each of said channels having a vent hole extending from the channel to the exterior surface of the outer cavity plate; each of said channel having a rib mounted thereover, the adjoining surface of said rib mating with the interior surface of the cavity plate, wherein the interior surface of the cavity plate has a roughened surface forming a vent passageway with the adjoining surface of the ribs for venting mold gasses from the interior of the mold to the exterior of the mold.
8. The mold of claim 7 wherein the adjoining surface of said rib mating with the interior surface of the cavity plate is located radially outward of the external contour of the tire.
9. The mold of claim 7 wherein the interior surface of said cavity plate has a roughened surface on the order of about 10 to about 40 mils.
10. The mold of claim 7 wherein the interior surface of said cavity plate has a roughened surface on the order of about 20 mils.
11. The mold of claim 7 wherein the interior surface of said cavity plate has a roughened surface formed of peaks and valleys, wherein the peaks are oriented perpendicular to the interior surface of said cavity plate.
12. The mold of claim 7 wherein the interior surface of said cavity plate has a roughened surface having a scalloped pattern.
13. A method of making a tread segment for use in a mold, the tread segment having a plurality of ribs and lands, the method comprising the steps of:
- providing a cavity contour plate having an interior surface and an exterior surface,
- roughing the interior surface of the cavity contour plate to a surface roughness of about 10 to about 40 mils,
- forming a plurality of channels in the interior surface of the cavity contour plate at the location of the ribs;
- forming a vent hole in each channel to the exterior surface of the cavity contour plate,
- securing an inner surface of a tread profile plate to the interior surface of the cavity contour plate at the location of the ribs, and forming the ribs from the tread profile plate.
14. A method of making a tread segment for use in a mold, the tread segment having a plurality of ribs and lands, the method comprising the steps of:
- providing a cavity contour plate having an interior surface and an exterior surface,
- forming a plurality of channels in the interior surface of the cavity contour plate at the location of the ribs;
- forming a vent hole in each channel to the exterior surface of the cavity contour plate,
- providing a tread profile plate having an interior surface,
- roughening the interior surface of the tread profile plate,
- securing an inner surface of a tread profile plate to the interior surface of the cavity contour plate at the location of the ribs, and forming the ribs from the tread profile plate.
15. A mold for vulcanizing a tire, the mold comprising a plurality of tread segments for forming the tread on a green tire, wherein the tread segments can be assembled side by side circumferentially about the green tire, each of said tread segments further comprised of a cavity plate having an interior surface and an exterior surface, said cavity plate having a plurality of slots on the interior surface, one or more blades secured within each slot, an outer surface of said blade mates with an inner surface of said slot, wherein one of said mating surfaces is roughened relative to the other mating surface forming a vent passageway for venting mold gasses from the interior of the mold to the exterior of the mold.
16. The mold of claim 15 wherein the blades have a roughened surface on the order of about 10 to about 40 mils.
17. The mold of claim 15 wherein the inner surface of said slot has a roughened surface on the order of about 10 to about 40 mils.
18. The mold of claim 15 wherein the blades have a roughened surface on the order of about 20 mils.
19. The mold of claim 15 wherein the blades have a roughened surface having a scalloped pattern.
20. A method of making a tread segment for use in a mold, the tread segment having a plurality of ribs and lands, the method comprising the steps of:
- providing a cavity contour plate having an interior surface and an exterior surface,
- forming a tread pattern of channels on the interior surface of the cavity contour plate;
- forming one or more slots on the interior surface of the cavity contour plate;
- mounting a blade in each slot, wherein the outer surface of the blade has a roughened surface.
21. A method of making a tread segment for use in a mold, the tread segment having a plurality of ribs and lands, the method comprising the steps of:
- providing a cavity contour plate having an interior surface and an exterior surface,
- forming a tread pattern of channels on the interior surface of the cavity contour plate;
- forming one or more slots on the interior surface of the cavity contour plate;
- mounting a blade in each slot, wherein the inner surface of the slot has a roughened surface.
Type: Application
Filed: Dec 22, 2004
Publication Date: Jun 22, 2006
Inventor: Eric Henrotte (Saint-Leger)
Application Number: 11/021,648
International Classification: B29C 35/02 (20060101);