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"today technology" for old engine

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Battler Britton

Well-Known Member
Joined
Nov 14, 2015
Messages
594
Location
Montpellier,LFNG (Candillargues)
New casting for Renault 4PO5 ...

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Published on December 11, 2016 by François Besse

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and , of course: https://www.youtube.com/watch?v=8YxVHX1yoTg

New cranks of modern technology for Renault 4PO5 to restore engine power to the Stampe SV-4.
Co-owners of a Stampe (F-BCQB), with a Renault 4PO5 engine totaling more than 2,100 hours since its start-up and more than 950 hours since the last RG, Laurent Stuck realized that one day Its replacement. However, the 4PO motor casings in good condition all have several thousand hours of operation. Taking into account "the fatigue characteristics of aluminum alloys subjected to cyclic loads", these casings are "inexorably at the end of their life and the risk of failure is high and will be increasingly ".
Moreover, the "metallurgical experiments carried out on these original parts show a large amount of impurities and weak mechanical qualities. There is virtually no more, on the used market, of casings in a satisfactory condition. Their welding repair as
Could be carried out leads to locally alter the metallurgical characteristics and report the problem in other areas of the room ".
This having been done, a solution had to be found by imagining that it would be possible to "derive many advantages in terms of strength, reliability and longevity, the use of a modern alloy, carried out by industrial processes during Of which the metallurgy is perfectly mastered ". Hence the project to realize ... a new crankcase for Renault 4PO5, an idea carried by Laurent Stuck, line engineer and with the "friendly and enthusiastic cooperation" of Jacques Rogemont, specialist of the Renault 4PO since 1957 with a long experience of Aeronautical mechanic.
The project quickly became "to restore the Renault engines with the aim of improving reliability, longevity, ease of maintenance, oil tightness while respecting the original design and performance, So Stampe remains what it is, "says Laurent Stuck. Hence the creation of the company Vint'air (Pau) in 2005 to build Renault 4PO5 engine blocks, while benefiting from the advice and workshop of Jacques Rogemont with milling machine, on-line boring machine and boring machine. Connecting rods.
In order to benefit from technical means at the level of the project, Vint'air used the skills of Ventana, a company working in the aeronautical field and benefiting from technical means enabling "rapid production of foundry parts that have become rare, without costly tools. The process is completely digital, from design to casting and then machining the part ". The skills of Ventana, a subcontractor in precision engineering, range from back-design to digital foundry and boiler making.
The main steps in the realization of a new part are as follows:
- Digitization of an original part: by optical acquisition by the company Tomoadour, the piece is digitized, with an accuracy of the order of 0.01 mm, complete with a full radiography. A 3D file with precise metrology is obtained.

- Development in CAD and manufacturing plan: digitization allows the development of a computer-aided design (CAD) directly exploitable in manufacturing.
Analysis of the composition of the alloy and choice of the material: the composition of the original part is determined precisely with a mass spectrometer. "Tensile test specimens are taken and analyzed. Once known the characteristics of the original metal, it is possible to choose an alloy with much higher qualities (mechanical strength four times higher). The operating temperature was measured during tests on an engine of origin, to ensure compliance with the limitations of the chosen alloy.



- Foundry simulation: CAD is used to study the casting mold. "A simulation tool of last generation allows to anticipate the flow
Molten metal, shrinkage and thermal gradients, and thus decrease the number of tests. The costs and delays of industrialization are drastically reduced ".

- Production of the mold: the latter is of the mold type lost in sand. It is "printed" by the 3D printing machine. "Each layer of sand is deposited, then cured to form the shapes of the mold. The assembly is then freed of the uncured sand, then "remolded" (the parts constituting the mold are assembled). A lost single-use mold is thus formed ".

- Casting of the part: the "spaces left in the sand mold are replaced by the molten metal introduced by many ducts, on a low pressure casting system. Once cooled, the piece is stripped of sand by shot blasting. Its geometry is Controlled by a laser scan of the actual part, which is computationally compared to the theoretical form. This also makes it possible to "swing" the machining (positioning the starting points of the machining operations). The heat treatment gives its mechanical properties to the aluminum alloy. - Control of the foundry: an x-ray of the part obtained "makes it possible to verify the absence of defects embedded in the thickness of the metal. The housing also undergoes a penetrant check (search for cracks) and traction specimens make it possible to ascertain the mechanical strength of the part. These checks are identical to those performed for foundries of reactor casings currently produced by Ventana. - Machining: always in a fully computerized process, the CAD model is used to "program the machining center on which machining is carried out with great precision, in a few hours. To ensure optimum concentricity of the crankshaft and camshaft bearings, their bore is made on an in-line boring machine ». - Assembly and finishing: once machined, the casing can accommodate all attachments (studs, shrinked camshaft bearings, pusher guides, helicoils). Some of these parts are hot-mountable, with controlled tightening to keep them in place at operating temperatures. The bearing line is then bored, with the bearing caps in place, with a high accuracy (0.01 mm) on an in-line boring machine dedicated to this task ". For Vint'air, "this manufacturing is part of a global project aimed at mounting a Renault 4PO5 engine whose longevity and reliability would approach newer engines". Substitution of more resistant materials at the level of the bearings will be permitted by "a rebuilding of the crankshaft (deposit of high hardness) and an optimized oil filtration. The cylinders were also rectified and then returned to the original dimension by a nickel-ceramic type deposit. Other uses of modern materials are being studied to improve the longevity of the Renault. " It should be noted that all the back-design (CAD, technology choice, DGAC file) was provided by Laurent Stuck within Vint'air. With the idea that there are niche markets for this type of service (parts for warbirds, cars or vintage motorcycles) and at the request of Ventana to "structure the offer aimed at collectors and restoration workshops" , Vint'air was created. For the crankcase project for Stampe, Vint'air ensured the design, technical responsibility, preparation of the manufacturing file (drawings, tolerances, technical specifications), machining of the main shaft and line (Helicoils, friction rings, dowels), Ventana then realizes the foundry crusts and the other machinings. Refurbishing costly, Vint'Air has planned to launch "new manufactures only when there is shortage or if there is an improvement from the point of view of the objectives mentioned above". Used are "stocks of new vintage parts and modern techniques of reconditioning used parts, which have the double advantage of being economical and improving the characteristics of parts". Thus, on a case-by-case basis, hard chrome plating, nickel-ceramic deposition, weld reconstruction and other innovative surface treatments are used which make it possible to restore the parts to the original dimensions by improving their resistance to Wear and sometimes friction coefficients ". The use of these techniques will be "particularly valuable on crankshafts and cylinders, which would be very costly to remake" with a "technological leap of 50 years on bearings and connecting rod". For the time being, an upper 4PO5 magnesium casing was produced - "a piece that has become untraceable". The first casing is still in the workshop. "The next step is the bore of the shaft line and the camshaft", with a vibration problem encountered during machining during the first tests. The reason is "too large a span between the bore guides" hence the design of "bore arms capable of holding the bar inside the casing. These cast-iron arms are being manufactured at a central French founder with a reception scheduled for early 2017. In early 2017, all parts will be ready for final assembly. This project is carried out in addition to an airline pilot activity, a precise timetable remains difficult to establish but "ideally" it is planned to assemble the engine and to pass it in the first half of 2017, for 20 to 30 hours of operation before checking. On the basis of these results, it will be necessary to obtain the agreement of the official services to conduct the flight tests on the Stampe. The flight tests are scheduled for the second half of 2017. For flights, it will be with a second crankcase already made since the first one, dating from 2015, has been used in multiple exhibitions and damaged during transport ... Vint's project 'Air has already been officially presented, notably at the La Ferté-Alais meeting in 2015 and 2016, the Nogaro Classic in 2015, the Goodwood Festival in 2015 and the AirVenture in Oshkosh in 2016 ... At the end Of this flight test program, it will then be possible "to envisage being able to respond to the request of the Stampists who would like to benefit from the fruit of this work", specifies Laurent Stuck. If Vint'air is satisfied with the results obtained, a "top-of-the-range restoration including all the innovations and the new crankcase if necessary" will then be proposed. The objective is to "get out engines whose lifespan approaches 1.500 h between general revisions". It would be necessary to "gather a dozen pieces to arrive at a price of around 7,900 € HT", amount to be compared with "an unreliable and costly remotorization (about 35,000 € for a Lycoming conversion)". These parts will "probably have a lifespan of more than 70 years, considering the improvements of the materials and the performances of the originals". Laurent Stuck states that this first financial evaluation is "a cost of production and that the studies (retro-design, mold design and machining programs) are not included and will not be invoiced on the first series to promote its diffusion ". Dossier to follow so ... [FONT=&quot]♦♦♦[/FONT] Photos © Vintair http://www.vintair.com
 
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