Metal fusion bonding – Process – Encasing a rodlike core within a substantially coextensive...
Patent
1997-03-10
1999-03-16
Ryan, Patrick
Metal fusion bonding
Process
Encasing a rodlike core within a substantially coextensive...
2281734, 228232, B23K 100, B23K 3102
Patent
active
058819460
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a method of manufacturing a hollow spindle that serves, in particular, as the mounting for valve-actuating levers that control exhaust-and-intake valves in an internal combustion engine.
2. Description of the Prior Art
A hollow spindle, specifically a rocker lever spindle of the aforementioned type, is known from DE 42 21 708 A1. This rocker lever spindle consists of an outer tube, in the interior of which a shaped tubular body is fixed. By means of the tubular body, which has a longitudinal rib, at least two and preferably three liquid-carrying chambers are formed. In a special embodiment (FIG. 2), the tubular body has a roughly V-shaped cutout that extends in the longitudinal direction to form a chamber. The tubular body is pushed or pressed into the outer tube and fixed in place by cam-type elevations or shapings on the mantle of the tubular body. A disadvantage of this design is that there is no assurance that the fixed position of the tubular body will be maintained or that the chambers will remain sealed under operating conditions. Furthermore, the lengths that can be manufactured are limited, so that production costs are high.
U.S. Pat. Nos. 3,863,328 and 4,125,924, disclose a method for fitting two tubes together in a rattle-proof fashion. After one tube is slipped into the other with a certain diameter clearance, a drawing point is formed on one end of the tubes. The tubes are then cold-drawn one atop the other.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a method for manufacturing a hollow spindle, particularly for the pivotal mounting of valve-actuating levers, in which the fixed position and the sealing of the chambers are maintained even under operating conditions and which allows longer lengths to be economically produced.
Pursuant to this object, and others which will become apparent hereafter, one aspect of the present invention resides in a method of manufacturing a hollow spindle by providing an outer tube, forming an inner tube having a circumference with an inwardly curved region and a circular region, the inwardly curved region being configured to pass into the circular region in a rounded, stepless manner, sliding the inner tube into the outer tube, cold drawing the outer tube onto the inner tube, heat treating the inner tube and the outer tube in a reducing atmosphere, adding a soldering agent, and final annealing the tubes to melt the soldering agent and fix the inner tube to the outer tube so that two liquid-carrying chambers are formed.
The hollow spindle produced according to the present invention that is distinguished by the fact that, instead of an inserted shaped section, a shaped inner tube rigidly connected to the outer tube by virtue of its material is used to form two chambers. The shaped inner tube, seen in cross-section, has an inwardly curved region. The inwardly curved region makes a rounded and stepless transition to the circular region. The two chambers are sealed by a soldered layer, which is provided over the entire circumferential area of the inner surface of the outer tube that comes to rest against the inner tube, as well as over the outer surface of the inner tube. Both the outer tube and the inner tube are preferably made of steel. However, other materials are also conceivable, such as Cu, Al and combinations with steel. In many cases, a hollow spindle that is used as a rocker lever spindle must be partially subjected to induction hardening. In these cases, the outer tube is preferably made of heat-treated steel.
The advantage of the method according to the invention is that the shaped inner tube can be economically drawn or rolled, whereas the inserted profile according to the prior art must be produced in an expensive extrusion process. Because a soldered layer is applied to the entire circumference that comes to rest, the requisite impermeability of the chambers is ensured. The cold drawing of tubes placed one inside the other serves to draw t
REFERENCES:
patent: 2007597 (1935-07-01), Dean
patent: 3394445 (1968-07-01), Valyi
patent: 4934579 (1990-06-01), Doble
Tempil Basic Guide to Ferrous Metallurgy, Tempil Division, Big Three Industries, Inc., 1977.
Curten Franz
Kiessling Martin
Mally Gunter
Wittenberg Dieter
Knapp Jeffrey T.
Mannesmann Aktiengesellschaft
Ryan Patrick
LandOfFree
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