BLIND CUTTING METHOD USING A HIGH-PRESSURE JET FOR AN ENGINE BODY

Abstract

A method for cutting, in a non-through manner, a body of a thruster of an aerospace vehicle, water jets, the method including a plurality of passes of a high-pressure water jet along the same cutting path extending across the external perimeter of the thruster body, the cutting path describing a closed loop circuit, and each water jet pass starting from a starting point located on the cutting path and stopping just after returning on the starting location. The starting point of each high-pressure water jet pass is different from the starting points of the other water jet passes.

Claims

1. A method for cutting, in a non-through manner, a body of a thruster of an aerospace vehicle, using water jets, the method comprising a plurality of passes of a high-pressure water jet (210, 230) along the same cutting path extending across the external perimeter of the thruster body, the cutting path describing a closed loop circuit, and each water jet passage starting from a starting point located on the cutting path and stopping just after returning on the starting location, wherein the starting point of each high-pressure water jet pass is different from the starting points of the other water jet passes.

2. The non-through cutting method according to claim 1, wherein at least the first high-pressure water jet pass uses an abrasive water jet.

3. The non-through cutting method according to claim 1, wherein at least the last pass of the high-pressure water jet uses a pure water jet.

4. The non-through cutting method according to any of claim 1, further comprising, at each pass of a water jet, a step of detecting the end of cutting.

5. The non-through cutting method according to claim 4, wherein the step of detecting the end of cutting comprises the application of a pulling force on a portion of the thruster body located on one side of the cutting path, and, if said pulled portion is moved relative to the other portion, comprises an indication of the end of cutting.

6. The non-through cutting method according to claim 1, wherein the thruster body to be cut has the shape of a cylinder closed at both its axial ends by covers curved outwardly, the body comprising a multilayer wall including a stack, from outside to inside, of an external thermal protection layer, of a layer made of composite material and of an internal thermal protection layer, and the convex covers also having an elastomer skin intended to be in contact with the fuel contained in the body and separated from the internal thermal protection layer by a space, and the non-through cutting method comprises a step of centering the cutting path on a convex cover, the cutting being carried out until the space separating the elastomer skin and the internal thermal protection layer is reached.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Other characteristics and advantages of the present invention will emerge from the description given below, with reference to the appended drawings which illustrate an exemplary embodiment devoid of any limitation.

[0032] FIG. 1, already presented, schematically presents a sectional view of a known thruster.

[0033] FIG. 2 presents a flowchart of a method for cutting in a non-through manner a thruster body according to one mode of implementation of the invention.

DESCRIPTION OF THE EMBODIMENTS

[0034] FIG. 2 presents a flowchart of a method for cutting, in a non-through manner, using water jets, a thruster body of an aerospace vehicle according to one mode of implementation of the invention.

[0035] The thruster body of the aerospace vehicle to be cut may have the shape of a cylinder closed at both of its axial ends by covers curved outwardly. The body comprises a multilayer wall including a stack, from the outside of the body to the inside of the body, of an external thermal protection layer, of a layer made of composite material and of an internal thermal protection layer. The convex covers further have an elastomer skin intended to be in contact with the fuel contained in the body and separated from the internal thermal protection layer by a space.

[0036] To prevent the content of the thruster, generally the propellant, from being altered, the cut must be a non-through cut. And for the cut to be sufficient to remove the cover and allow access to the propellant without the risk of altering the propellant, it is preferable that the cut stops in the gap that is to say in the space existing between the elastomer skin and the internal protective layer which is also generally made of elastomer.

[0037] For this, the method according to the invention includes, first of all, a first step 200 of centering the cutting path on a convex cover in which the cutting water projection system is centered facing the starting point of the cut-out of the thruster body to be cut.

[0038] In a second step 210, the method includes a pass of a first cutting operation, the first cutting operation being carried out using an abrasive water jet, and the pass being made over the entire outer circular perimeter of the cylindrical body.

[0039] The use of an abrasive water jet at the beginning of the cutting method, that is to say for the first pass(es) of the high-pressure water jet, makes it possible to start the cutting operation properly, in particular to cut the layer made of composite material which is generally harder than other layers. For such hard layers, the use of an abrasive water jet makes it possible to carry out a cutting without creating delamination or loosening of fiber.

[0040] At the end of the pass, the method includes a third step 220 in which the number of passes of the first cutting operation carried out, that is to say the cutting operation using abrasive water jet, is compared to a threshold of passes of the first cutting operation.

[0041] If the number of passes carried out is below the threshold, the second and third steps 210 and 220 are repeated. When the number of passes carried out is equal to the threshold, the method carries out, in a fourth step 230, a pass of a second cutting operation using a pure water jet. The use of a pure water jet for the last passes allows reducing the risk of pollution of the materials to be treated.

[0042] The pure water jet can be used after several passes with an abrasive water jet, in particular after the hard material layers, such as the composite materials, have been cut. The pure water jet can be used in particular to cut an elastomer layer without risking water pollution.

[0043] Each pass of the first cutting operation or second cutting operation is carried out over the entire circular perimeter of the thruster body. And each pass, that is to say each passage, of a pure water jet or of an abrasive water jet, is carried out by projection of a high-pressure water jet along the same cutting path extending across the external perimeter of the thruster body.

[0044] The cutting path thus described during each pass is a closed loop circuit. And each pass of an abrasive or pure water jet begins from a starting point located on the cutting path and stops just after returning on the starting location. The path followed by the water jet at each pass is therefore longer than the closed loop formed by the cutting path, in other words longer than the circular perimeter of the body.

[0045] The starting point of each pass of pure or abrasive high-pressure water jet is therefore different from the starting points of the other water jet passes, whether it is anterior or posterior passes.

[0046] After each second cutting operation pass, the method carries out, in a fifth step 240, a detection of the end of cutting of the cover of the body. The step of detecting the end of cutting includes in this example the application of a pulling force on a portion of the thruster body located on one side of the cutting path, and, if said pulled portion is moved relative to the other portion, an indication of the end of cutting in a last step 250, since it reflects the fact that the cut-out has reached the space separating the elastomer skin and the internal thermal protection layer.

[0047] The method according to the invention thus provides a solution allowing to cut only the external thermal protection (PTE), the composite structure and the internal thermal protection (PTI) of a thruster body of an aerospace vehicle, without altering the propellant contained inside the thruster.