1. Technical Field
The invention relates to curing presses and in particular to a curing press and method for forming tapered airsleeves. More particularly, the invention relates to such a curing press and method which utilizes a straight cylindrical bladder for curing a preshaped airsleeve against a tapered cartridge located within a curing chamber.
2. Background Information
Airsleeves are used for a variety of shock absorbing purposes such as in vehicle suspension systems, and suspension system for other structural components such as presses, seats, etc. intended to absorb shock. Airsleeves also are used as elevation adjusting devices between a fixed member and a movable member in various pieces of apparatus and equipment. These airsleeves consist of a cured elastomeric bladder or bellow which may or may not contain reinforcing fiber or fabric, which is sealed against an end plate and/or a piston and pressurized with a fluid contained within a fluid chamber for absorbing shock imparted to either the end plate and/or piston.
These airsleeves may be cylindrical or tapered or have other configurations, and are formed by various curing methods. One method of curing a tapered airsleeve is to slide a preform or preshaped uncured green sleeve into a hollow contoured mold and then insert a correspondingly specially contoured bladder into the green sleeve and thereafter expanding the contoured bladder and subsequently the green sleeve, radially outwardly against a contour mold for forming the same. Although this curing press and procedure is satisfactory, it requires the use of specially contoured expansion bladders which are relatively expensive and which have a relatively short life requiring continual replacement after a predetermined number of airsleeves are produced thereby.
Examples of known prior art cure presses and methods for forming airsleeves and other elastomeric members are shown in the following patents.
U.S. Pat. No. 3,057,768 discloses a method of forming an air spring wherein the uncured sleeve is pressed outwardly against a static outer mold by means of an inner expandable mandrel.
U.S. Pat. No. 3,964,846 discloses an apparatus for the manufacture of power transmission belts in which the belt body or sleeve is sandwiched between radially expandable and radially contractible members in a vulcanizing chamber. Outward radial pressure is first applied to the belt body and then a radial inwardly pressure is applied together with heat, to cure the body within the chamber.
U.S. Pat. No. 4,126,659 discloses a method and apparatus for making a hollow resin impregnated fibrous article wherein a layup of the article to be manufactured is placed within a female mold and is forced against the interior of the mold, afterwhich and heat is applied to cure the resin.
U.S. Pat. No. 4,252,760 discloses a method and apparatus utilized to make articles from thermosetting plastics by means of pressing and sintering. A central mandrel has positioned therearound a backing member. Core members have positioned on their interior a pair of bladders which are used to press by fluid means, powdered material toward the backing member to form the desired product. Upon finishing the pressing procedure, the freshly compressed material is removed from the mandrel and the backing member which is frangible, is destroyed, rendering the compressed article in a state such that it may undergo the centering procedure. For the next pressing procedure a new backing material which is made of plaster, must be formed.
U.S. Pat. No. 4,263,237 discloses a method of molding an article using both inward and downward forces. An elastic material is expanded by fluid means to cause inward pressure against granular material that is positioned in a cavity which will be forced against a central mandrel. A ram with a closure member, also is utilized to create downward pressure.
U.S. Pat. No. 4,496,299 discloses the use of a molding tool for semi-isostatic compacting of powder. A mold cavity is positioned between a central steel core and an elastomeric jacket. Hydraulic fluid is positioned within a space to provide the medium for the elastomeric jacket to press the powder material within the mold cavity against the central steel core.
U.S. Pat. No. 4,704,082 discloses an isostatic press mold that uses a resilient outer member to apply pressure to powdery material forcing it against an inner mandrel to form the desired product. The powdered ceramic material is positioned in the mold cavity and is formed between the core mold parts and a pressed diaphragm. Fluid material causes a covering diaphragm to displace the pressed diaphragm toward the mold cavity. The covering diaphragm appears to be positioned around the ends of a rigid tube and a cover with a corresponding cover gasket, is used to seal the chamber.
U.S. Pat. No. 4,888,144 discloses a method for pressing dry type rubber. A flexible mold presses powder inwardly against a core member, and a pressure tube has its end portions positioned around both ends of the inner tube.
U.S. Pat. No. 4,937,025 discloses an apparatus and method for molding articles from particulate material, wherein the material is positioned between a central mandrel and an elastomeric bladders that may be pressed inwardly at a variety of points around the mandrel.
U.S. Pat. No. 4,997,511 discloses the use of a tubular autoclave for forming composite parts by applying pressure to a workpiece and then later subjecting the workpiece to heat. A workpiece which consists of a central mandrel that has layers of thermoplastic resin applied thereon, is positioned within a resilient sleeve which is inflated, causing pressure against the layers of thermoplastic resin that are positioned on the workpiece. The autoclave has covers which are secured by clamping means to form a fluid tight chamber.
U.K. Patent Application 2 139 934 discloses a press for forming contoured sheet material such as aromatic polymer composites, by pressing the sheet material between rigid contoured tools and a complementary contoured semi-rigid diaphragm. The diaphragm is thrust against the sheet material and the tool by fluid pressure in a manner to cause the sheet material to conform to the tool.
Although the above known prior art patents disclose various types of curing presses for forming airsleeves and other elastomeric and metal articles, they do not disclose the particular curing press and method of the present invention set forth in greater detail below and defined in the appended claims.