Plastic article or earthenware shaping or treating: apparatus – Reshaping – resizing or vulcanizing means for tire – tire... – Toroidal or annular female shaping means and coacting means...
Patent
1987-10-26
1991-01-15
Silbaugh, Jan H.
Plastic article or earthenware shaping or treating: apparatus
Reshaping, resizing or vulcanizing means for tire, tire...
Toroidal or annular female shaping means and coacting means...
264296, 264326, 264DIG67, 425 281, 425 47, 425 49, 425393, 425441, 425446, 4254515, 4254519, B29C 3502, B29C 3326, B29D 2908
Patent
active
049849760
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to fabricating annular polymeric articles, and more particularly to a method of making annular polymeric articles and moulds for carrying out the method.
2. Description of the Prior Art
Known in the art are methods of making annular polymeric articles in which a workpiece is placed on a shaping cylindrical surface, after which the workpiece is squeezed on this surface and vulcanized. Squeezing is done by sector elements arranged around the cylindrical shaping surface by moving the sectors radially.
There are also known moulds for making annular polymeric articles comprising a cylindrical core (cylindrical shaping surface) serving to accommodate thereon elements of the article. Arranged around the cylindrical core are sectors for squeezing the workpiece kinematically linked with a drive for moving these sectors radially to form a closed circuit. For avoiding unproductive losses the outer sides of the sectors at their abutments are provided with recesses accommodating locks to prevent leaks of elastic material (SU, A, 195,088).
The aforedescribed devices can be used, however, only for making one-sided toothed belts, because in the course of moulding the elastic material is at first forced to the clearance between the sectors to gradually flow then to the molding interior as the clearance diminishes accompanied by the formation of fins in the zone of abutment. When making polymeric articles having a wear-resistant fabric lining at the outer surface, such as double-sided toothed belts, the fabric lining between the sectors is subject to biting or cutting. Due to the flow of the elastic material to the clearance between the sectors and then due to the backflow of the elastic material to the molding zone insufficient moulding takes place in the abutment zone, especially during fabrication of shaped articles.
SUMMARY OF THE INVENTION
The invention aims at providing a method and a mould for making annular polymeric articles in which the moulding process would be so carried out as to ensure fabrication of both single-sided and double-sided toothed belts with wear-resistant tooth lining of a higher quality.
The aims of the invention are attained by a method of making polymeric articles, in which a workpiece is placed on a cylindrical shaping surface, after which it is moulded by squeezing it on this shaping surface and is vulcanized. According to the invention, the surface of the workpiece is divided about the perimeter into alternating first and second portions, and moulding is done in two stages, the first stage including moulding the first portions, whereas the second stage includes moulding the second portions interposed between the first portions at the same time maintaining the pressure applied to the first portions.
A mould for carrying out the method comprises a cylindrical core having a shaped surface, mounted on a base and serving to accommodate the workpiece thereon, and elements for squeezing the workpiece arranged around the cylindrical core and kinematically linked with a means for moving these elements radially to the formation of a closed circuit, in which mould. According to the invention, the elements are arranged around the cylindrical core alternately, each first element having side surfaces parallel with the axis of symmetry of this element, whereas each second element has side surfaces adjacent to the side surfaces of the neighbouring first elements arranged at an angle to the axis of symmetry of this element, the kinematic linkage between the first and second elements and the means for moving them in the radial direction being adapted for a successive movement initially of all the second elements and then all the first elements.
Preferably, the mould has two first elements and two second elements, the side surfaces of each second element resting at an angle of .alpha.=90.degree. to the axis of symmetry thereof.
Such an arrangement of the mould is structurally simple, and is especially adaptable to making
REFERENCES:
patent: 2381395 (1945-08-01), Brown
patent: 3989439 (1976-11-01), Schmitzberger
Boikov Vladimir P.
Gorodnichev Jury N.
Guskov Valery V.
Kozachevsky Gennady G.
Molodan Oleg I.
Silbaugh Jan H.
Vargot Mathieu
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