Metal working – Method of mechanical manufacture – Prime mover or fluid pump making
Reexamination Certificate
2000-04-27
2001-09-11
Hughes, S. Thomas (Department: 3726)
Metal working
Method of mechanical manufacture
Prime mover or fluid pump making
C029S888060, C029S527500, C123S669000, C164S100000
Reexamination Certificate
active
06286210
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention proceeds from a method for producing a cylinder liner blank to be cast into a light-metal crankcase of a reciprocating engine, with the blank likewise consisting of a light-metal alloy. Such a method is contained, for example, in the applicant's prior, not previously published, German application DE 196 34 504 A1. Although the method of this older application affords an improvement on known methods, as compared with the prior art, the fundamental aim, on an industrial scale, is to achieve a further improvement not only of the method, but also of the product produced by the method. The principle of mechanical roughening prior to the casting of the blank into the light-metal casting is basically an advantageous step of the method, but it still needs further refinements and differentiations in order to optimize the method even further.
SUMMARY OF THE INVENTION
The object of the present invention is, therefore, to improve the generic method to the effect that an even greater bonding of the at least one blank to the light-metal crankcase can be achieved. The separate production of a blank and the casting of the latter into a light-metal crankcase are carried out, as a rule, because the blank consists of a different light-metal alloy from the casting material of the light-metal crankcase.
Only when the large-area bonding of each cylinder liner to the light-metal casting material of the crankcase is ensured are special benefits achieved later when the engine equipped with this crankcase is in operation. These benefits are, above all, uniform heat transmission, a uniform temperature profile of the cylinder liner in the circumferential and the axial directions and lower thermally induced cylinder distortion. Moreover, many other advantages are associated with this, these emerging, above all, from the prior German application mentioned.
The essence of the improvement in the proposed method is, in general, a roughening of that surface of the blank or blanks which comes into direct contact with the casting material. It is proposed, in detail, that surface activation be carried out by rolling using a roll or roller which is made of a hard material and is roughened in a sharp-edged manner and which, when it rolls on the surface, roughens the blank.
An advantageous development of the method results because the copper particles referred to are conducive to the fusion of the treated surface parts during the casting-in operation. Materially integral casting over the full 100% surface is achieved with a high degree of process reliability by coppering over the entire surface.
A further development is that the time span between surface activation and the casting-in of the components is less than approximately 5 hours. The production process therefore has to be controlled in such a way that this maximum time is not exceeded, but is preferably substantially undercut. To be precise, the drawing indicates that bonding decreases more and more with increasing time, and because of this, as stated, the aim is to fall as far short of the maximum time mentioned as possible.
It is particularly advantageous, in this case, if surface activation takes place directly before the casting-in of the blanks, and the time span between surface activation and the casting-in operation corresponds approximately to the cycle time of the casting-in process.
For the blanks produced according to the method steps explained above and therefore also the final product, specifically the light-metal crankcase with cast-in liners, it is particularly important, with regard to the sought-after quality and the desired advantages, that the surface activation achieved is maintained until the casting-in of the blanks and is not impaired again, or even lost, for example on the way into the casting mould.
REFERENCES:
patent: 2693122 (1954-11-01), Fausel
patent: 4005991 (1977-02-01), Uebayasi et al.
patent: 196 34 504 A1 (1997-12-01), None
patent: 0 532 331 A1 (1993-03-01), None
Ruckert Franz
Stocker Peter
Compton Eric
Crowell & Moring LLP
Daimler-Chrysler AG
Hughes S. Thomas
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