Metal deforming – By three or more coacting relatively movable tools – With means to actuate tools in sequence
Patent
1983-11-10
1986-11-11
Crane, Daniel C.
Metal deforming
By three or more coacting relatively movable tools
With means to actuate tools in sequence
72402, 72339, 140 88, B21D 5316, B21F 3700
Patent
active
046215158
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to a method and apparatus for making precision rings such as circlips, more especially circlips of a type having a generally annular appearance but with a gap defining two free ends and with a radially thick portion diametrically opposite the gap, the circlip diminishing in radial thickness from the raidally thick portion towards the ends to yield a smooth continuous tapered appearance between the ends and said thick portion.
BACKGROUND OF THE INVENTION
Circlips of the aforementioned type, hereinafter referred to as "of the type specified", may be used for positioning and retaining machine components internally in hollow bores or externally on shafts and have to meet accurate specifications. Such circlips are made by a stamping process by stampling out circlips from sheet metal. A problem with making circlips in this way is the large wastage of material necessarily incurred because the radial thickness of the circlip is small relative to the outer radius of the circlip. In some circlips (used for internal housing bores) the gap between the ends is wide enough for another circlip of the same type to pass through so that the circlips may be stamped out from sheet metal in interleaving fashion to reduce wastage, but even so wastage of material is still significant. Moreover, with some circlips (used for external shafts) the gap usually provided is too narrow even for this interleaving and so an even larger wastage is incurred.
It is an object of the present invention to provide apparatus and method to allow circlips of the type specified to be made in which the aforementioned wastage is alleviated and also in which the costs of production of circlips is reduced.
SUMMARY OF THE INVENTION
According to the present invention there is provided a method of making circlips of a type having a planar, generally annular appearance but with a gap defining two free ends and with a radially thick portion diametrically opposite the gap, the circlip diminishing in radial thickness from the radially thick portion towards the ends to yield a smooth, continuous tapered appearance between the ends and said thick portion, the method characterised by: portion towards its ends and of a shape which is configured to be formed into a circlip of the type specified by bending the blank, that the blank distorts during the bending operation in a controlled manner to make a circlip of the type specified, with the ends of the blank being shaped into the ends of the circlip and the middle portion of the blank being shaped into the radially thick portion.
Further according to the invention there is provided a longitudinal blank for a circlip of the type specified when made as described in the immediately preceding paragraph, and also a circlip of the type specified when made as described in the immediately preceding paragraph.
Still further according to the present invention there is provided a method of making circlips of the type specified, the method comprising: preferably flat, wire or strip to adapt the profile or contour of each successive length of wire or strip in successive stages as the wire is moved relative to work stations at which said operations take place, so that longitudinal blanks are formed successively form successive lengths of the wire or strip, one of said work operations comprising tapering a respective blank from a middle portion towards its ends, the remainder of said work operation rendering said blank suitable to be bent into a circlip of the type specified, mandrel so that said blank distorts in a controlled manner to make a circlip of the type specified, with the ends of said blank being shaped into the ends of the circlip and the middle portion of the blank being shaped into the radially thick portion.
Stil further according to the invention there is provided apparatus for making circlips of the type specified comprising means to make a longitudinal blank tapered from its middle portion towards its ends and means to shape the blank so that it is capable of b
REFERENCES:
patent: 496773 (1893-05-01), Bowen
patent: 948615 (1910-02-01), Pratt
patent: 1526518 (1925-02-01), Wentworth
patent: 1973436 (1934-09-01), Hjort
patent: 2371138 (1945-03-01), Harrison et al.
patent: 2382947 (1945-08-01), Brozer
patent: 3315512 (1967-04-01), Maciorowski
Marklew, J. J., "Circlip Production at Anderton Springs Ltd.," from Machinery and Production Engineering, Oct. 11, 1972.
Bates David A.
Pearson Arthur
Sanderson Albert M.
Crane Daniel C.
George Salter & Co. Ltd.
Markva Neil F.
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