FR3116315A1 - SPRING WASHER OFFERING IMPROVED TEMPERATURE RESISTANCE - Google Patents

Abstract

Spring washer comprising a body integrating a fluidic circuit intended for the circulation of a heat transfer fluid, said washer being manufactured by additive manufacturing. Figure for abstract: 1

Description

SPRING WASHER OFFERING IMPROVED TEMPERATURE RESISTANCE

TECHNICAL AREA AND PRIOR ART

The present invention relates to a spring washer or Belleville washer offering improved temperature resistance.

A spring washer or elastic washer, also referred to as a Belleville washer from the name of its inventor, is a washer which performs a spring function by elastic deformation.

This type of spring washer is frequently used when low flexibility is desired under heavy load, as opposed to a conventional spiral spring which will provide it with high flexibility.

In addition to their low cost, these washers have the advantage of being able to be combined in various ways, which not only makes it possible to obtain the desired stiffness for the assembly, but also to create systems with variable stiffness. Indeed, unlike the springs, the elastic washers can be arranged together to increase the rigidity by mounting them in series, or to increase the movement by mounting them in parallel, or even by mounting certain washers in parallel and certain in series.

However, when washer springs are used at high temperatures, they lose their stiffness over time due to material creep. Indeed, despite the implementation of active cooling of the washer, it is possible depending on the case that it rises in temperature or drops in temperature and that the assembly obtained by the spring washer(s) deteriorates over time. course of time.

It is therefore an object of the present invention to provide a spring washer having improved temperature resistance.

The objective stated above is achieved by a spring washer incorporating at least one channel configured for the circulation of a heat transfer fluid allowing thermal control of the washer. The realization of this channel is made possible by using an additive manufacturing process.

In addition, additive manufacturing makes it possible to manufacture washers in material grades that are resistant to creep at high temperatures, for example around 700°C. While these grades are not available for conventional manufacturing of spring washers by stamping or the available materials are very few. For example, the Schnorr company offers a single nickel-cobalt alloy designated Nimonic 90® (NiCr20Co80Ti) whose working temperature is between -200°C and +700°C.

In other words, the spring washer incorporates its heat exchange circuit to extract or supply heat to the washer.

One of the subjects of the present application is a spring washer comprising a body integrating a fluidic circuit intended for the circulation of a heat transfer fluid, said spring washer being manufactured by additive manufacturing.

Advantageously, the fluidic circuit comprises channels distributed in a body of the spring washer.

For example, the fluidic circuit comprises a plurality of concentric channels connected in parallel.

The fluidic circuit may comprise at least one heat-transfer fluid supply orifice and at least one heat-transfer fluid discharge orifice, said supply and discharge orifices being formed in an outer lateral edge of the body of the spring washer.

Advantageously, the spring washer comprises a supply channel connected to the supply orifice and an evacuation channel connected to the evacuation orifice, said ducts being intended to be connected to a fluid circulation system coolant, said ducts being made in one piece with the body of the washer by additive manufacturing.

For example, the spring washer being at least partly made of a nickel-based superalloy, for example Inconel®718 manufactured by powder bed fusion.

According to an additional characteristic, the spring washer comprises parts made of different materials and/or having different mechanical properties.

Another object of the present application is a system of spring washers comprising several spring washers according to the invention, the spring washers being assembled so as to have all the tapers oriented in the same direction and produced in one piece by additive manufacturing.

Another object of the present application is a system of spring washers comprising several spring washers according to the invention, said spring washers being assembled so that two adjacent spring washers have tapers oriented in opposite directions and made in one piece by additive manufacturing.

Another object of the present application is a system of spring washers comprising several spring washers according to the invention, the spring washers being assembled so that at least two adjacent spring washers have tapers oriented in the same direction, and so that at least two adjacent washers have tapers oriented in opposite directions and made in one piece by additive manufacturing.

For example, the fluidic circuits of the spring washers are connected between them and in which the system comprises a supply conduit connected to all the fluidic circuits and an evacuation conduit connected to all the fluidic circuits.

The present invention will be better understood on the basis of the following description and the appended drawings in which:

is a longitudinal sectional view of an example of a spring washer.

is a schematic representation of a top view of the spring washer of the in transparency showing the circulation of the heat transfer fluid.

is a perspective view of the sectional view of the .

is a perspective view of another example of a spring washer.

is a top view of the spring washer of the , the upper wall being removed.

is a graphic representation of the load in N of the washer as a function of the crushing in mm for a washer of the state of the art and a washer according to the invention.

is a perspective view of an example of a system of spring washers arranged in series.

is a sectional view of the system of the .

is a sectional view of the according to two secant planes at the level of the axis of the washer.

is a perspective view of an example of a system of spring washers arranged in parallel.

is a sectional view of the system of the .

is a sectional view of the according to two secant planes at the level of the axis of the washer.

DETAILED DISCUSSION OF PARTICULAR EMBODIMENTS

Figures 1 to 3 show an example of a spring washer according to the invention.

The spring washer R has a generally frustoconical shape with a longitudinal axis X. The washer R has two frustoconical annular faces 2, 4 connected by side faces 6, 8 inside and outside respectively.

The washer comprises a fluidic circuit 10 arranged between its two annular faces 2, 4 for the circulation of a heat transfer fluid, at least one supply orifice 12 of said circuit and at least one discharge orifice 14 of said circuit.

Advantageously, the supply and discharge orifices are formed in the outer side face 6, in at least one part which remains accessible even after assembly of the washer in the system in which it is used.

The fluidic circuit 10 is configured to allow a relatively uniform circulation of the fluid throughout the washer and thus ensure a relatively uniform extraction or heat supply.

The fluidic circuit 10 comprises at least one fluidic channel 16.

In the example shown, the fluidic circuit 10 comprises five cavities or channels 16 of circular and concentric shape. The channels are centered on the X axis.

In this example and advantageously, the channels are connected in parallel to the supply port and to the outlet port. Thus a single supply port and a single outlet port are implemented.

Two adjacent channels are separated by a circular wall 18 and two adjacent channels are connected to each other by passages formed through the wall 18.

In the example shown, the channels are connected in parallel to the supply port 12 by passages 20 aligned radially with the supply port and are connected in parallel to the discharge port 14 by passages 22 aligned radially with the evacuation orifice 14. The circulation of the fluid in the spring washer is symbolized by the arrows F.

The parallel supply and evacuation of the channels offers the advantage of ensuring homogeneous heat extraction throughout the body of the washer.

In the example shown, the washer comprises ducts 24, 26 respectively connected to the supply orifice and to the discharge orifice allowing connection to a heat transfer fluid circulation system. Advantageously, the ducts are made in one piece with the body of the spring washer.

The circulation system is for example a closed circuit comprising for example a heat transfer fluid reservoir, a circulation pump and advantageously a heat exchanger to cool the heat transfer fluid at the outlet of the washer in a high temperature application, or means for heating the heat transfer fluid in a low temperature application.

As a variant, the fluidic circuit comprises a circular channel radially inside the washer and a circular channel radially outside the washer and radial channels. The circuit is configured to supply the radially-inward circular channel with coolant which will flow through the radial channels to the radially-outward circular channel which is connected to the exhaust port .

In FIGS. 4A to 4C, one can see another example of spring washer R′ comprising a fluidic circuit in which portions of channels 28 are oriented radially and are connected to each other so as to cause the fluid to circulate alternately towards the outside and outward from the washer in the radial direction. The channel portions 28 are connected by circular arc-shaped channel portions 30 located on the radially outer periphery and bordering the latter, and circular arc-shaped channel portions 32 located on the radially outer periphery. inside and bordering it. The arrows F' symbolize the flow of the fluid. The washer comprises ducts 34, 36 respectively connected to the supply orifice and to the discharge orifice allowing connection to a circulation system for the heat transfer fluid. In this example, channel portions 28 and 30 are interconnected so that the fluidic circuit has two separate channels connected in parallel to supply channel 34 and to exhaust duct 36.

As a variant, the channel portions 28 and 30 are connected together so that the fluidic circuit forms a single channel connected to the supply conduit by one end and to the evacuation conduit by the other end.

The heat transfer fluid can be a gas or a liquid which, by its physical properties, makes it possible to transport heat from one point to another.

The gaseous heat transfer fluid can be chosen, for example, from nitrogen, helium, air, carbon dioxide and superheated steam. Halogenated fluids, for example Perfluorocarbon (PFC) and Hydrofluoroether (HFE), can be used in applications requiring their dielectric strength and volatility.

The liquid heat transfer fluid can be chosen from organic fluids in the form of mineral or synthetic oil for operating temperatures below 350°C. For applications at higher temperatures, heat transfer fluids such as molten salts or even liquid metals can be used.

By way of example only, the washer has an outside diameter of
125 mm, an inside diameter of 51 mm, a thickness of 6 mm, a free height h of 9.4 mm. The thickness e of the walls of the channels is equal to 1 mm. The wall thickness between the channels can be different from the wall thickness of the faces 2, 4.

The spring washer with integrated cooling circuit is manufactured by additive manufacturing, which makes it possible to produce channels in a reduced volume.

The washer can be made, for example, by a process by powder bed fusion or PBF (Powder Bed Fusion in Anglo-Saxon terminology) or by a process of material deposition under concentrated energy or DED (Directed Energy Deposition in Anglo-Saxon terminology). ). PBF processes consist in melting, for example by means of a laser beam, certain regions of a powder bed, we then speak of LBM (Laser Beam Melting in Anglo-Saxon terminology) for laser beam melting. This method offers a better resolution, it makes it possible to produce thin walls, of the order of 0.2 mm to 2 mm. Powder bed fusion processes offer great geometric freedom and flexibility in production. The LBM method is more suitable for materials based on iron, nickel and aluminium, and the method by electron beam melting or EBM (Electron Beam Melting in Anglo-Saxon terminology) is more suitable for materials based on titanium.

For example, the LBM method can proceed as follows. The alloy used to form the powder bed is in the form of powder with a particle size of less than 50 μm. It is spread by a bed scraper with a variable thickness between 30 μm and 50 μm. For example, a fiber optic YAG laser is used, with a power of 400 to 1000 W. the beam produced by this laser is oriented by mirrors to selectively scan the bed so as to merge the grains in the zones defined upstream in a digital file. The melting point depends on the metal alloy used but at the focusing point of the laser beam, the temperature can reach 2000°C, melting the upper layer of powder but also one or more of the lower layers, thus locally creating a bath liquid. The solidification of successive layers will form the part. All of the production takes place in a controlled chamber under an atmosphere of nitrogen or argon, for example, in order to avoid oxidation or even ignition of the metals. Preferably, elements forming supports are planned and manufactured at the same time as the part in order to ensure its maintenance in the bed and avoid any risk of it collapsing which would deform the final geometry of the part. These supports advantageously form the role of heat sinks, ensuring a wider distribution in the room of the heat concentrated around the focal point.

In another example, a high energy electron beam is used to melt and fuse metal powder. This method is called EBM (Electron Beam Melting in Anglo-Saxon terminology) for electron beam melting. The process takes place under vacuum. This method nevertheless offers a lower resolution than the LBM method.

DED processes consist in depositing a molten material, for example by means of a laser beam, an electrical resistance, an electron beam, a UV light beam, the material being brought into solid form, for example in the form with wire or powder.

Advantageously, the ducts are produced simultaneously with the body of the spring washer by additive manufacturing.

The manufacture of spring washers by additive manufacturing also has the advantage of being able to manufacture spring washers in materials which are not generally used to manufacture state-of-the-art spring washers, because they are not suitable for the process of conventional manufacture of spring washers. Spring washers having substantially improved creep resistance independent of the coolant circuit can be manufactured.

An example of making the washer by additive manufacturing is as follows:

The dimensions of the washer and the shape and dimensions of the channels of the fluidic circuit are determined according to the application of the washer (temperature, load, etc.). A model in the form of a digital file is produced. The file is loaded into a microcomputer of a machine implementing a process such as the extrusion or solidification of metal powder, polymer and polymer wire, making it possible to create, step by step, the spring washer. The machine sequentially prints each layer, one on top of the other, building an actual spring washer inside the machine's build chamber. Once the machine has finished the last layer, a short drying cycle begins. Then the actual spring washer can be removed, and potentially given a finishing treatment if necessary, such as sanding, baking for hardness, etc.).

By way of example, the spring washer can be made of a nickel-based superalloy, for example Inconel®718 by the LBM process, i.e. by the powder bed fusion process using the laser to melt the material, which gives it a very good resistance to creep at high temperature, of the order of 700° C. in air.

For resistance to creep at high temperature, the spring washer can also be made of a titanium alloy, for example TA6V, of stainless steel, for example 310s austenitic stainless steel.

Similarly, it is possible to manufacture spring washers with very good mechanical strength at low temperature, which can reach -200°C. For example, the spring washer can be made of S460 carbon-manganese, A420F.M carbon steel with reduced brittleness at low temperatures.

There represents the load curve C1 of a washer of the state of the art and the load curve C2 of a washer according to the invention (force E in N as a function of crushing EC in mm) for a washer in IN718 having the dimensions given above. Spring washers C1 and C2 have the same external dimensions.

It can be seen that the spring washer according to the invention has a rigidity equal to approximately 60% of a spring washer of the state of the art.

By increasing the thickness e of the walls of the washer, we increase its rigidity.

In addition, thanks to the coolant circuit, this rigidity can be maintained at high or low temperature, unlike state-of-the-art spring washers.

Additive manufacturing also makes it possible to produce washers in several materials, which makes it possible to produce a spring washer combining the advantages of the properties of these. For example, similar materials can be used but having different ductilities.

It can also be envisaged to vary the thickness of the walls according to the mechanical stresses applied to them. Thicker and therefore more rigid walls are made in the highly stressed areas, and walls are made with less material in the weakly stressed areas to obtain a certain flexibility.

When it is desired to electrically isolate the system on which the spring washer is mounted, it is advantageous to interpose between the spring washer and the system, a ceramic washer forming an electrical insulation interface.

During manufacture, for example by LBM, the laser melts certain areas of the ceramic powder bed, then a bed of metal powder is formed on the base thus formed to manufacture the rest of the washer.

In FIGS. 6A to 6C, one can see an embodiment of a system of spring washers R1 mounted in series and having increased rigidity. In an assembly, the spring washers are superimposed and two adjacent washers are arranged so as to have their tapers oriented in opposite directions. The washers are made in one piece by additive manufacturing and the fluid circuits of the washers are connected to each other. A supply conduit 38 common to all the circuits is provided at one longitudinal end of the system and an evacuation conduit 40 common to all the fluid circuits is provided at the other longitudinal end of the system. Ducts 38 and 40 are diametrically opposed. As a variant, the two ducts 38 and 40 extend on the same side or in intersecting planes and/or are located at the same longitudinal end.

The arrows F1 symbolize the circulation of the fluid in the fluidic circuit.

This system also has the advantage of offering simplified handling since it is in one piece.

The washers are made in one piece by additive manufacturing and at least one fluid circuit is formed in the system of washers. This system also has the advantage of offering simplified handling since it is in one piece.

In FIGS. 7A to 7C, one can see an embodiment of a system of washers R2 mounted in parallel and having increased clearance. In an assembly, the spring washers R are superimposed with their tapers oriented in the same direction.

Supply 42 and evacuation 44 ducts are provided at the ends of the system. The circulation of the fluid between the washers is obtained by orifices 46 formed in the annular faces of the washers ensuring a connection of the fluid circuits between them. The arrows F2 symbolize the circulation of the fluid in the fluidic circuit. The pressurized liquid flows successively through the stages from the inlet to the outlet.

As for conduits 38 and 40, the relative arrangement of conduits 42 and 44 on the is not limiting.

In another example, the system comprises at least two spring washers mounted in parallel and at least two washers mounted in series.

The systems of FIGS. 6A to 6C and 7A to 7C allow energy storage.

The use of several materials allowing to combine the properties of these materials is particularly interesting in the systems of spring washers in series and in parallel.

The spring washer according to the invention is particularly suitable for use in high temperature environments, for example for mounting on a high temperature electrolyser, for example in the space field, for example in satellites and rocket engines, in the field of the steel industry, in furnaces in which elements must be pressurized, in the field of aeronautics, for example in the reactors of fighter planes, or airliners.

Claims (11)

Spring washer comprising a body integrating a fluidic circuit intended for the circulation of a heat transfer fluid, said spring washer being manufactured by additive manufacturing. Spring washer according to Claim 1, in which the fluidic circuit comprises channels distributed in a body of the spring washer. Spring washer according to claim 1 or 2, in which the fluidic circuit comprises a plurality of concentric channels connected in parallel. Spring washer according to Claim 1, 2 or 3, in which the fluidic circuit comprises at least one heat-transfer fluid supply orifice (12) and at least one heat-transfer fluid discharge orifice (14), the said supply orifices (12) and discharge (14) being formed in an outer side edge of the body of the spring washer. Spring washer according to 4, comprising a supply channel connected to the supply orifice (12) and an evacuation channel connected to the evacuation orifice (14), the said conduits being intended to be connected to a system circulation of a heat transfer fluid, said ducts being made in one piece with the body of the washer by additive manufacturing. Spring washer according to one of the preceding claims, said spring washer being at least partly made of a nickel-based superalloy, for example Inconel®718 manufactured by powder bed fusion. Spring washer according to one of the preceding claims, comprising parts made of different materials and/or having different mechanical properties. System of spring washers comprising several spring washers according to one of the preceding claims, the washers being assembled so as to have all the tapers oriented in the same direction and produced in one piece by additive manufacturing. System of spring washers comprising several spring washers according to one of Claims 1 to 7, the said washers being assembled so that two adjacent spring washers have conicities oriented in opposite directions and produced in one piece by additive manufacturing. System of spring washers comprising several spring washers according to one of Claims 1 to 7, the washers being assembled so that at least two adjacent spring washers have tapers oriented in the same direction, and so that at least two adjacent have tapers oriented in opposite directions and made in one piece by additive manufacturing. Spring washer system according to one of Claims 8 to 10, in which the fluidic circuits of the spring washers are connected to one another and in which the system comprises a supply conduit connected to all the fluidic circuits and an evacuation conduit connected to all fluid circuits.