EP1409167B1 - Method and device for shaping structural parts - Google Patents

Abstract

A structural part includes a plate-shaped base body and ribs that extend longitudinally approximately parallel to one another, and that are joined integrally to and protrude orthogonally from the base body. In a shaping method, the structural part is shaped by particles of blasting or peening shot, which strike the surface areas of the structural part at a high velocity to cause a plastic deformation thereof. Opposite surface areas of the ribs, located on opposite longitudinal sides of each rib, are simultaneously subjected to the action of particles of the blasting shot. An apparatus to perform the method includes two nozzles arranged facing toward one another with the rib therebetween, to form two jets of the blasting shot particles directed toward one another at the rib.

Description

The invention relates to a method for forming structural components, in particular those for use in aerospace, wherein the structural components a plate-shaped body and approximately at right angles outgoing, integral with the body connected, elongated and approximately parallel to each other Have ribs, wherein the deformation is carried out by particles of a blasting agent with high speed impact surface areas of the structural component and a cause plastic material deformation.

Especially in aerospace engineering so-called structural components are often used. Integral components used, which - usually one-sided, but possibly also both sides - have parallel ribs, while possibly not with ribs provided side is even. If both longitudinally and transversely of the component Ribs are present, which are approximately perpendicular to each other, the component receives a Cassette structure. To bend such components, complex procedures must be applied because the ribs - especially if they are parallel to the direction of curvature run - represent a significant deformation resistance.

Forming of the type described above are used in aerospace engineering for a long time to the curvature of large-scale components, such as wings or hull shells, applied. When forming structural components come mainly abrasive with a particle diameter of up to 2 - 4 mm used. While the abrasive for large-scale machining of the components using Spinning wheels is applied, become a localized deformation Hand jet systems used. These hand blasting machines are also used to bend Used ribs. Due to the beam geometry and the beam diameter the To be able to deform usually flat ribs purposefully, are to be processed Ribs partially covered with a mask, so that in the rib areas to be reshaped the desired strain gradient is achieved. To cover the not to impinging surface sections of the ribs will be rubber or a different shock absorbing material used. The cover of the ribs requires a lot great effort, especially when multiple masks must be made.

As an alternative to the above-described shot peening method is known in the art the so-called forceps method (Eckhold method) known. In these procedures packs a pliers with a kind of staple grip the rib with two spaced gripping jaws two adjacent places. By a short movement of the two jaws from each other away or towards each other, the rib is either locally stretched or compressed. By repeated application along the longitudinal extension of the rib can be continuous convex or concave curvatures are generated. The curvature can be through the Pliers lift and the number of repetitions of these applications are affected.

Even if such pliers method can be automated, it is to be regarded as a disadvantage that due to the low strains per Zangenhub the forming process a very large time requires. Despite the fundamentally possible automation requires the implementation of this Pliers method by the operator much experience, especially because of the risk of buckling and the Springback behavior of the ribs.

Also commonly known are so-called creep forming processes (Age creep forming). for structural components. The component is in this case by cutting, in particular by Milling first made in a flat shape. Then the component becomes placed in a mold having the outer contours of the finished component. Under influence of pressure and temperature, the component is adapted to the shape. This Forming process usually takes several hours. Another disadvantage is that special shapes have to be made for each geometry. Besides, it is required to separately determine the parameters, temperature, pressure and time for each component. In addition, the use of the creep forming process for materials used for the heat treatment performed are not suitable. Another difficulty is to overstretch the component in the mold to a certain extent to the To compensate for springback after removal of the component from the mold, so that the exact desired component geometry is present.

The prior art also includes the known from US 4,329,862 method for Shot blasting of plate-shaped components, in particular of Hydrofoil structures. However, it is not intended that the blasting with acting wing components are reinforced by ribs. The aforementioned US patent rather teaches the component in a first step by a two-sided Strain to apply and then by a only one-sided Blasting abrasive agent in another direction.

Finally, there is a practical method for reshaping Structural components in this, using modern CNC milling machines made of solid material milling. Apart from the considerable cost of materials, this is only weak curved structures possible. The cost of this in big thickness to be provided raw material is significant. Therefore, this procedure - especially for large-area components - only economically usable in very few cases. Furthermore also result from the machining strong springback effects in the finished Component that affect its dimensional stability.

The invention is based on the object, a method for forming To propose structural components, with which in a reliable and cost-effective manner Different geometries can be realized on the finished components.

Starting from the forming process of the type described above, this task According to the invention solved in that on opposite longitudinal sides in each case one Rib arranged, opposite surface areas of the ribs from opposite sides simultaneously with Particles of the abrasive are applied.

Since the applied surface areas are directly opposite, a Fault or distortion of the rib in the direction transverse to its longitudinal extent safe prevented. Such a delay is particularly to be feared when a rib - like in Handstrahlverfahren according to the prior art - only one-sided with blasting is charged. On the other hand, by the same time from both sides on the The surface of the blasting abrasive impinges on the effectiveness of each individual puncture impact elevated. The energy losses due to elastic material deformations are in the minimized inventive method. Depending on the height of the rib - related on the body - the two-sided Strahlmittelbeaufschlagung according to According to the method of the invention can be both convex and concave To achieve curvatures of the thus treated structural component. The strength of the radius of curvature is determined by the size and speed of the particles of the blasting medium and the Duration of the blast treatment influenced. A particular advantage of the invention Method is to be seen in that the transformation of structural components exclusively by Loading the ribs can be done so that an additional treatment of the Basic body can be dispensed with. Automation of the proposed method is also possible, especially if the geometry of the treated structural component Measured online and included in a control strategy to control the process.

According to one embodiment of the method according to the invention, either one to a Rib foot of adjacent longitudinal strips of the rib or adjacent to a rib head Longitudinal strips of the rib are exposed to particles of the blasting medium, wherein the width the longitudinal strips can correspond at most to the height of the ribs.

In the first case mentioned above, the longitudinal and / or transverse ribs of the component are in Extended foot area by the Strahlmittelbeaufschlagung. This results in a concave Curvature of the component, the term concave on the side provided with the ribs the plate-shaped base body is related.

In the alternative case, a convex curvature of the component by an extension of the Longitudinal and / or transverse ribs in the head area, d. H. near its longitudinal direction extending end face achieved.

If the inventive method in structural components with a cassette structure, d. H. with intersecting longitudinal and transverse ribs, applied, so can be both uniaxial as well as produce multi-axial component curvatures and unwinds. Become For example, the longitudinal ribs in the foot area extended, whereas the transverse ribs in Extended head area, resulting in a combination of concave and convex Curvature of the component, creating a saddle-shaped geometry. For components have only longitudinal or transverse ribs, a saddle-shaped structure can thereby achieve that a curvature transverse to the longitudinal direction of the ribs by a Blasting agent treatment of the body in the known in the prior art (one-way) manner is performed.

The invention further ausgestaltend it is proposed that the particles of the blasting agent have a mean diameter of more than 4 mm. This can also be done Reliably transform structural components with thick-walled ribs. Large particles, in particular Large balls with a diameter of more than 4 mm, allow a penetration the rib to a great depth.

A development of the method according to the invention is that the particles of the Blasting agent from opposite, each other directed nozzles one Emerge jet device, which proceed in the longitudinal direction and in the vertical direction of the ribs becomes. As a result, an automation in the implementation of the method and the Realization of various geometries allows.

Furthermore, it is advantageous to synchronize the nozzles in the same direction and with the same Speed to move. This ensures that even with a continuous Relocation of the treatment site always opposite surface areas of the Rib are applied.

A device for forming structural components, in particular those for Use in aerospace, wherein the structural components of a plate-shaped Main body and right angles outgoing, integral with the body have connected, elongated and approximately mutually parallel ribs, allows the application of particles to surface areas of the structural component a blasting medium impacting at high speed, whereby a plastic Material deformation is caused, and is inventively by at least two nozzles for a directed exit each of a particle beam, wherein the two Particle beams are directed towards each other and the nozzles a greater distance from each other as the thickness of the rib. Preferably, the nozzles are in Interspaces between adjacent ribs placeable, whereby it is possible, the To direct particle beams at an angle of about 90 ° on the rib surface.

With such a device can be with the forming method described above perform comparatively simple means. Due to the fixed assignment of the two nozzles or the exit directions of the particle beams to each other is always ensured that opposite surface areas of the rib are acted upon. If the nozzles in Interspaces between adjacent ribs are placeable, is a vertical Auftreffrichtung the particles on the surface areas to be processed possible.

Finally, it is still provided according to the invention that the nozzles together in Longitudinal direction and vertical direction of the ribs are movable, resulting in large Have components carried out at various points of the ribs. It can thus be a variety of possible geometric transformations of the Realize the component to be formed.

Fig. 1

Eine Vorrichtung zum Umformen eines Strukturbauteils mit zwei aufeinander zugerichteten Düsen;

Fig. 2a

eine perspektivische Ansicht eines Ausschnitts eines Strukturbauteils;

Fig. 2b

eine Seitenansicht des Bauteils gemäß Figur 2a;

Fig. 2c

wie Figur 2 b, jedoch nach Herstellung einer konvexen Krümmung;

Fig. 3a bis 3c

wie Figuren 2 a - 2 c, jedoch zur Herstellung einer konkaven Krümmung;

Fig. 4

die Dehnungsverteilung in einer Rippe bei konvexer Krümmung;

Fig. 5

wie Figur 4, jedoch bei konkaver Krümmung.

The inventive method will be explained in more detail with reference to an embodiment of a device shown in the drawing. It shows:

Fig. 1

An apparatus for forming a structural component with two nozzles directed towards each other;

Fig. 2a

a perspective view of a section of a structural component;

Fig. 2b

a side view of the component according to Figure 2a;

Fig. 2c

like Figure 2 b, but after making a convex curvature;

Fig. 3a to 3c

as Figures 2 a - 2 c, however, for producing a concave curvature;

Fig. 4

the strain distribution in a rib at convex curvature;

Fig. 5

like Figure 4, but with concave curvature.

FIG. 1 shows only two of a device for forming structural components Nozzles 1a and 1b, from the front side 2 a and 2b, respectively, a slightly conical expanding beam 3a / 3b exits a particulate abrasive. The particles of the Blasting agents have a spherical shape and have a diameter of more than 4 mm (For example, 6 mm). The supply of the blasting agent to the nozzles 1 a and 1 b as well the other components of the blasting device are well known and therefore not shown in more detail.

With the forming device partially shown, a structural component 4 of a reshaped metallic material. This structural component 4 consists of a plate-shaped, only partially shown basic body 5 and a plurality of rectangular thereof outgoing, integrally connected to the main body 5 ribs 6, of which the For clarity, only a single section is shown. The ribs 6 run parallel and equidistant at the machined component at such a distance to each other, that the nozzles 1a and 1b including the associated feeding in the Gaps between adjacent ribs 6 can be positioned. The distance A between the nozzles 1a, 1b is dimensioned such that the rib 6 to be treated with the Thickness D is to be arranged between them and at the same time there is still enough space between them Nozzles 1a, 1b and the rib surfaces remain to a trouble-free flow of the To ensure blasting agent.

FIG. 1 shows the case with nozzles 1a / 1b oriented perpendicular to the rib 6. It is but also possible, the particle beams obliquely deviating from above at an angle of 90 ° on the surface of the ribs. The nozzles 1a / 1b can then in a Level above the rib top are arranged and moved.

The common longitudinal axis 7 of both nozzles 1a / 1b, perpendicular to the two Side surfaces 8a and 8b of the rib 6. Thus, it is ensured that on the opposite side surfaces 8a and 8b opposite and substantially congruent surface areas are acted upon by the beams 3a and 3b. In the event of the same blasting agent intensity thus prevails in the area of the exposed rib sections a balance of forces, the buckling or unilateral deflection of the rib. 6 prevented.

Figures 2a and 2b can be a fragmentary and perspective in a See side view illustrated structural component 4, in which one of a fin head. 9 outgoing longitudinal strip 10 which runs parallel to the longitudinal extent of the rib 6, is particularly highlighted. This longitudinal strip 10, whose width 11 about 40% of the height 12 of the Make rib 6, is applied with the aid of the nozzle 2b with blasting agent. Corresponding is an opposite in the figures not visible longitudinal strip 10b with the same Width 11 also loaded with blasting agent, with the aid of the nozzle 2a. The nozzle arrangement shown in Figure 1 is therefore a total, d. H. without the two Doors 2a / 2b change their position and orientation relative to each other, in the longitudinal direction of Rib 6 - for example, at a constant speed - movable.

In Figure 2 c is shown, which form the structural component 4 after a Blasting treatment has taken in the field of longitudinal strips 10 a and 10 b. Due to the occurring in the region of the rib head 9 material elongation, d. H. one Extension of the component in this area, takes both the rib 6 and the integrally associated main body 5 a convex curved shape. Despite the curved shape are the side surfaces 8a and 8b of the rib 6 within each one Level.

In addition to the curvature in the longitudinal direction of the rib 6, the structural component 4 by a blasting treatment either the bottom 13 or the top 14 of the main body. 5 additionally obtained a curvature perpendicular to the longitudinal extent of the ribs 6. To this Manner can produce saddle-shaped structures.

In the case of structural components with Kassettsstmktur, d. H. intersecting ribs in longitudinal and Transverse direction of the component can be such a saddle-shaped structure alone Beam treatment of the ribs achieve. Optionally, however, here is an additional Beam treatment of the body possible.

Figures 3 a to 3c show the case that by means of a blasting agent treatment a concave curvature of the structural component 4 is to be generated. The longitudinal strip 10a ' is in this case in the area of the rib foot 15 and joins immediately the top 14 of the main body 5 at.

After blasting treatment of the opposing longitudinal strips 10 a 'and 10b ', the structural component 4 assumes the concavely curved shape shown in FIG. 3c. Due to the elongation of the rib 6 in the foot area at the same time the material of plate-shaped base 5 mitgedehnt. The width 11 of the longitudinal strips 10a 'and 10b' is again about 40% of the height 12 of the structural component 4th

Finally, FIGS. 4 and 5 allow the strain distribution in the region of FIG Blasting agent to be acted upon longitudinal strips 10a (on the rib head) or 10a '(am Remove ribbed foot). While the strain in the case shown in Figure 4 starting from a lower boundary line 16 of the edge strip 10a up to the Rib head 9 increases linearly from zero to a maximum value, the strain increases at the Structural component 4 according to Figure 5 also linear starting from an upper Border line 17 of the longitudinal edge strip 10 a 'up to the rib foot 15 at the transition in the main body 5, where a maximum value of the elongation is present.

Claims (9)

1. A method for shaping structural parts, especially such for use in aviation and space travel, with structural parts comprising a plate-shaped base body and ribs which are longitudinally extended, are parallel to one another, are joined integrally to the base body, and protrude from the base body in an orthogonal manner, with the shaping occurring by means of particles of blasting shot which strike the surface areas of the structural part at a high velocity and produce a plastic material shaping, characterized in that opposite surface areas of the ribs, with said surface areas being located on opposite longitudinal sides of each rib, are simultaneously subjected to the action of particles of the blasting shot from the opposite sides.
2. A method as claimed in claim 1, characterized in that a longitudinal strip adjacent to a rib base is blasted with particles of the blasting shot, with the width of the longitudinal strip corresponding at most to half the height of the rib.
3. A method as claimed in claim 1, characterized in that a longitudinal strip adjacent to a rib head is blasted with particles of the blasting shot, with the width of the longitudinal strip corresponding at most to half the height of the rib.
4. A method as claimed in claim 3, characterized in that the particles of the blasting shot comprise an average diameter of more than 4 mm.
5. A method as claimed in one of the claims 1 to 4, characterized in that the particles of the blasting shot emerge from oppositely situated, mutually facing nozzles of a blasting apparatus, which nozzles are moved in the longitudinal and upward direction of the ribs.
6. A method as claimed in claim 5, characterized in that the nozzles are moved synchronously in the same direction with the same speed.
7. An apparatus for shaping structural parts (4), especially such for use in aviation and space travel, with the structural parts (4) comprising a plate-shaped base body (5) and ribs (6) which are longitudinally extended, are approximately parallel to one another, are joined integrally to the base body(5), and protrude from the base body (5) in an orthogonal manner, with the apparatus being used for conveying particles of blasting shot at high velocity onto the surface zones of the structural part (4) where they produce a plastic material deformation, characterized by at least two nozzles (1a/1b) for a directed delivery of a particle jet (3a, 3b) each, with the two particle jets (3a, 3b) being directed towards each other and the nozzles (1a, 1b) having a larger distance (A) from each other than the thickness (D) of the rib (6).
8. An apparatus as claimed in claim 7, characterized in that the nozzles (1a, 1b) can be placed in the intermediate spaces between adjacent ribs (6).
9. An apparatus as claimed in claim 7 or 8, characterized in that the nozzles (1a, 1b) can be moved jointly in the longitudinal direction and upward direction of the ribs (6).

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