US 6,086,806 AGranted

Method of splicing thermoplastic articles

AssigneeRonald H. Ball

InventorsDouglas J. Weatherall, Andrew O. Kenny, Ronald H. Ball, A. Stuart Caunce, David S. Ball

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Abstract

A method and apparatus are provided for forming a joint in an elongate article formed from a thermoplastic material, for example an escalator handrail or a conveyor belt, which also includes a plurality of reinforcing cables and a slider fabric. End parts of the article are held in a mold and heated to remelt the material. Portions adjacent the end parts are chilled, at ends of the mold, to prevent remelting. The molten end parts then fuse, and the molten joint is then cooled to resolidify the material and form the joint. With reinforcing cables being present, these can be cut into an interlace pattern, which advantageously is provided in just a layer of the article rather than extending through the full depth of the article. A top layer can then be replaced by a separate top cap of the material of the body of the article. Where a slider is present, to provide an effective interlacing effect, a bottom layer or portion of a handrail is cut at an inclined angle, to form an inclined joint in the slider.

Claims24

Dependent claims

A method of forming a joint in an elongate article, which has a body of generally uniform cross-section, is formed from a hygroscopic thermoplastic material containing water and has end parts and which includes a plurality of elongate inextensible members, the method comprising the steps of:

(1) cutting the inextensible members in each end part to at least two different lengths together with a corresponding portion of the material of the body of the article, to form an interlace pattern at the joint, with the inextensible members terminating in a plurality of planes transverse to the elongate article, wherein said corresponding portions are cut such that the ends of the elongate inextensible members are aligned with one another so that a bond between the elongate inextensible members and the thermoplastic material is not disturbed;
(2) placing the end parts of the article in a mold comprising at least two mold parts displaceable between open and closed configurations and defining an elongate mold cavity with a cross-section corresponding to the cross-section of the article, interlacing said corresponding portions together, such that there are no substantial voids and enclosing the end parts of the article within the mold cavity, the two mold parts being separable and displaceable relative to one another in a direction generally perpendicular to the elongate mold cavity;
(3) while maintaining portions of the article adjacent the end parts cool, to prevent melting thereof, heating the end parts of the article to provide temperature conditions along the mold such that the article expands and contacts the mold to pressurise the end parts, before the thermoplastic melts;
(4) while continuing to maintain portions of the article adjacent the end parts cool, to prevent melting thereof, further heating the end parts of the article to melt the thermoplastic material, thereby to form molten end parts and to fuse the end parts together, and simultaneously pressing the two mold parts together into the closed configuration to pressurize the molten end parts within the mold cavity to a pressure high enough to prevent vaporization of water in the molten end parts;
and
(5) while continuing to maintain said portions of the article adjacent the end parts cool and pressing the mold parts together, cooling the molten end parts of the article to resolidify the material and to form a joint.

3 more elements

A method of forming a joint in an elongate handrail having a generally C-shaped external section and defining an internal T-shaped slot, the handrail comprising a body of generally uniform cross-section formed from a thermoplastic material and having end parts, an internal slider fabric around the T-shaped slot and a plurality of elongate inextensible members extending in the body above the T-shaped slot, the method comprising the steps of:

(1) providing a mold comprising first and second mold parts displaceable between open and closed configurations and a mandrel having a cross-section corresponding to the internal T-shaped slot of the handrail, the mandrel being mountable between the first and second mold parts, whereby the first and second mold parts and the mandrel define an elongate mold cavity with a cross-section corresponding to the cross-section of the handrail, and the two mold parts being separable and displaceable relative to one another in a direction generally perpendicular to the elongate mold cavity;
(2) cutting the inextensible members in each end part to at least two different lengths together with a corresponding portion of the material of the body of the handrail, to form an interlace pattern at the joint, with the inextensible members terminating in a plurality of planes transverse to the elongate handrail, wherein said corresponding portions are cut such that the ends of the elongate inextensible members are aligned with one another and such that a bond between the elongate inextensible members and the thermoplastic material is not disturbed;
(3) inserting the mandrel into the T-shaped slot of the end parts, interlacing said corresponding portions together such that there are no substantial voids and enclosing the end parts of the handrail and the mandrel within the mold cavity;
(4) while maintaining portions of the handrail adjacent the end parts cool to prevent melting thereof, heating the end parts of the handrail around the mandrel to melt the thermoplastic material, thereby to form molten end parts and to fuse the end parts together, and simultaneously pressing the two mold parts together into the closed configuration to pressurize the molten end parts within the mold cavity;
(5) while continuing to maintain said portions of the handrail adjacent the end parts cool and pressing the mold parts together, cooling the molten end parts of the handrail to resolidify the thermoplastic material and to form a joint in the handrail;
and
(6) opening the first and second mold parts and removing the mandrel from the T-shaped slot.

4 more elements

Dependencies are inferred from the claim text.