Plastic and nonmetallic article shaping or treating: processes – With measuring – testing – or inspecting – Positioning of a mold part to form a cavity or controlling...
Reexamination Certificate
2001-12-07
2004-08-03
Sells, James (Department: 1734)
Plastic and nonmetallic article shaping or treating: processes
With measuring, testing, or inspecting
Positioning of a mold part to form a cavity or controlling...
C264S315000, C264S326000, C425S029000
Reexamination Certificate
active
06770229
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
This invention pertains to applications for bladder securement mechanisms for a tire press utilizing a position sensor mechanism, and more specifically to a method for relieving pressure in a newly vulcanized tire that is still in the tire press, and even more specifically to a method for more safely opening a tire press in the event a bladder has ruptured.
2. Description of the Related Art
Tire presses and methods for making tires are well known in the art.
FIG. 2
shows a green tire
12
undergoing a curing process in a tire press
10
. The green tire
12
is placed within a cavity defined by a lower mold
14
and an upper mold
16
. The lower mold
14
is fixedly installed on a base frame
18
. The upper mold
16
can be closed and opened in relation to the lower mold
14
. In
FIG. 2
, the tire press
10
is shown in the closed position.
A bladder securement mechanism
40
, some aspects of which are currently known in the art, is illustrated in FIG.
1
. The bladder securement mechanism
40
is commonly referred to as a “center mechanism.” In the bladder securement mechanism
40
, a center mechanism tube
42
is supported by a guide cylinder
44
, which is fixed on the base frame
18
. The upper end
32
of a bladder
30
is held by an upper clamping mechanism
70
, which is attached to the upper end
48
of a center mechanism rod
46
. The center mechanism rod
46
is positioned on a piston
50
of the center mechanism tube
42
. A lower clamping mechanism
80
, which holds the lower end
34
of the bladder
30
, is attached to the upper end of the center mechanism tube
42
through a hub
51
. A pressurized fluid is supplied by way of a first port
52
formed in the lower part of the center mechanism tube
42
to a portion below the piston
50
. The pressurized fluid is also supplied from a second port
54
through a pipe
56
to a portion on the top of the piston
50
. The pipe
56
passes through the piston
50
and is inserted into the center mechanism rod
46
.
The piston
50
and the center mechanism rod
46
move upward together. When the bladder
30
is deformed around the lower clamping mechanism
80
, a heated pressurized medium such as steam is supplied through a fluid supply tube
58
via a through hole on the hub side into the bladder
30
. Then the bladder
30
comes tightly into contact with the inner side of the green tire
12
.
A floating piston
60
is adapted to contact the hub
51
and is slidably attached to the center mechanism rod
46
. A stacking spacer
62
is positioned above the floating piston
60
, and a stretch height spacer
64
is positioned below the floating piston
60
but above the piston
50
. The stacking spacer
62
and the stretch height spacer
64
are exchangeably attached to the outside of the center mechanism rod
46
. The stacking spacer
62
sets the lower limit position of the upper clamping mechanism
70
so that the upper clamping mechanism
70
is set to a shaping height corresponding to the tire size. The stretch height spacer
64
limits the upper clamping mechanism's
70
upward movement.
While suited for their intended purpose, present bladder securement mechanism designs of the tire curing presses have the following disadvantages. As different sized tires are cured, the top clamping ring of the upper clamping mechanism must be repositioned to accommodate each tire size. This requires spacers of different lengths to be changed on the bladder securement mechanism. These spacers are cumbersome to change as different sized tires are cured. In addition, valuable production time is wasted. Also, since the spacers are generally fabricated from standard pipe, their lengths are not as precise as desired. Further, the spacers are subject to wear and tear over time, which leads to further imprecision and, thereby, possible imprecision in the tire.
Another problem with traditional spacers is that adjustment of the top ring is extremely limited during the curing process because the top clamping ring cannot advance towards the bottom ring once it has contacted the spacer. Still yet, another disadvantage of utilizing spacers is that the tire press only has two positions: open and closed. There is no mechanism for fine precision to ensure the green tire will cure correctly without any flaws or inaccuracies.
Present bladder securement mechanisms are limited in performance due to the restrictive nature of the spacers. For example, the tire press utilizes a variety of pressure sensors to ensure that it is safe to open the press. If pressure sensors indicate excess pressure in the tire press, the tire press cannot open. Currently, there is no way to detect pressure between the bladder and the vulcanized tire that is still in the press. If a defect in the bladder causes the pressure medium to pass therethrough and into the tire, there is no way to detect the pressure. Since all pressure sensors would appear to show normal pressure in the tire press, the press can be opened. This could result in the excess pressure being directed toward the tire press operator, which is undesirable. Even if the excess pressure was detected, there is no way to release it with the press closed due to the presence of the spacers in the bladder securement mechanism.
Therefore, a need exists in the art for a bladder securement mechanism that operates without a spacer and that overcomes the foregoing difficulties and others. The present invention is contemplated to overcome these disadvantages by utilizing a linear position sensor mechanism with the bladder securement mechanism, such that the upper clamping mechanism may be moved at any time during the curing process. Having the ability to move the upper clamping mechanism offers safety and tire forming advantages.
SUMMARY OF THE INVENTION
The present invention is a method for relieving pressure in a vulcanized tire while still in a tire press. A tire press comprises a lower mold, an upper mold, and a bladder securement mechanism. The bladder securement mechanism has an upper clamping mechanism for securing the upper periphery of a bladder and a lower clamping mechanism for securing the lower periphery of the bladder. A center mechanism tube has a center mechanism rod positioned therein. A piston is disposed within the center mechanism tube. The piston provides reciprocating motion to the center mechanism rod. A position sensor mechanism is operatively associated with the bladder securement mechanism. The method comprises the steps of positioning a green tire on the bottom mold; lowering the upper clamping mechanism; inflating the bladder, thereby forming a seal between the bladder and the tire; closing the press so that the green tire is enclosed within the upper and lower molds; curing the green tire; breaking the seal; releasing pressure from the tire; and, dissipating the released pressure. Accordingly, it is an object of the present invention to provide a method for directing excess pressure captured in a newly vulcanized tire away from the operator and into the tire press structure.
Another object of the present invention is to provide a method for relieving pressure in a vulcanized tire while still in a tire press, wherein the position sensor mechanism comprises a linear sensing rod disposed in the center tube; a magnet positioned within the piston, the magnet being laterally spaced from the linear sensing rod, and a signal generating unit for determining the travel distance of the piston.
Yet, another object of the present invention is to provide a method for relieving pressure in a vulcanized tire while still in a tire press further comprising the steps of moving the magnet with the piston; determining the displacement of the piston relative to the bottom of the center tube; and, controlling the vertical movement of the upper clamping mechanism.
Further, another object of the present invention is to provide a method for relieving pressure in a vulcanized tire while still in a tire press, wherein breaking the seal comprises the step of moving the u
Barnes Heather M.
Emerson Roger D.
McDowell Brouse
Sells James
LandOfFree
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