WO2017203067A1

WO2017203067A1 - Equipment for machining curved pieces

Info

Publication number: WO2017203067A1
Application number: PCT/ES2016/070393
Authority: WO
Inventors: Luis CALLEJA MARTÍNEZ; Javier Orive de Diego; Asun RIVERO RASTRERO; Antonio RUBIO MATEOS
Original assignee: Zayer, S.A.
Priority date: 2016-05-25
Filing date: 2016-05-25
Publication date: 2017-11-30

Abstract

The invention relates to equipment for machining curved pieces, which can be adapted to said curvature, provided with a continuous securing means and providing a low-cost solution in relation to the existing solutions, comprising a bracket that adopts said curvature, with said bracket being disposed on at least two supports and comprising at least one first sheet of a semi-flexible, porous and air-impermeable material on which the piece to be machined is deposited, characterised in that the semi-flexible material has a hardness greater than 40 Shore A, a Young's modulus greater than 3 MPa and a breaking strain greater than 0.75 N/mm2 and wherein the distance between supports is less than or equal to 175mm, such that the bracket is not deformed under the machining forces and maintains the adaptation thereof to the curvature.

Description

TOOL FOR MACHINING OF CURVED PARTS

TECHNICAL FIELD OF THE INVENTION

The present invention is encompassed in the field of tooling for machining parts with curvature, usually in pieces of relatively reduced thickness that allows them to adopt curvature. BACKGROUND OF THE INVENTION

To mechanize pieces of reduced thickness, chemical milling is known, which involves submerging the pieces in different pools with chemical agents that attack the material reducing the thickness in the desired areas, while the rest of the surface is protected by masking. It is the most widespread solution today. It has the disadvantage that it is a slow process, several hours, of the need for a large work area / volume, a high maintenance cost and a huge toxicity and treatment of the chemical agents used.

Mechanical milling with double head solution is also known, which are solutions based on having a head on each side of the panel to be machined. On the one hand the tool mechanizes, while on the other the second head measures and supports the skin for a correct machining, such as patents with publication number US7682112 and WO2013 / 160504. Normally a third element is necessary to hold the parts that is formed by a discrete tooling commanded by the machine control, it has to be moved to give access to the other two heads during machining, so It has an investment cost and high management complexity. The disadvantage is that they are complex and therefore expensive solutions that involve high investments.

Milling on a flexible surface is also known, presenting solutions based on the mooring of the piece by vacuum on a semi-flexible plate, such as patents with publication number ES2354793 and ES2258893. These solutions have the following disadvantages:

• The cost of automating the movement and control of all the pillars on which the piece rests has an impact on the increase in the cost of the solution, since each pillar has its own drive and is controlled by the machine control, that is, it is a further axis in the machine, understood as such the linear or circular movement controlled by the electronic control of the machine;

· The properties of the semi-flexible material are proposed, but it is not indicated what material it is; the requirements for it are high, since it has to be flexible to adapt to different curvatures of the piece, it has to withstand the machining forces and not vibrate during it, it also has to be non-porous;

• the distance between supports of the piece, measured in the arc it describes or on the surface of the piece, is intrinsically determined by the curvature of the piece, and has a great impact on the rigidity of the tooling and the mooring of the piece, and therefore, the precision of machining;

• in ES2354793 the pivots only move vertically, so the distance between supports depends on the curvature of the piece; • In the ES2258893 patent, as the holes for making the vacuum have to coincide with the situation of the support pivots, if it is necessary to join the support pivots to have a greater rigidity, another semi-flexible plate should be used.

DESCRIPTION OF THE INVENTION

The present invention is established and characterized in the independent claims, while the dependent claims describe other features thereof.

The object of the invention is a tool for machining parts with curvature that allows adapting to said curvature, also provides a continuous mooring, being a low cost solution with respect to existing solutions. The technical problem to solve is to establish the components of the tooling, its configuration and the relation between them to reach the mentioned object.

The material of the workpiece can be metallic, such as the aluminum of the aeronautical panels, although it can be any ferric or non-ferrous material, such as other metal alloys, and even resin composites with fiberglass or carbon, other plastics , etc., with the preference that it is not porous.

An advantage of the invention set forth in claim 1 against chemical milling is that it reduces manufacturing times and avoids the use of any chemical agent, as opposed to this and the double head is that it can be installed in a milling machine standard, it implies a smaller investment and has hardly any maintenance costs, another advantage over the tools with flexible material is that it does not deform or has negligible deformation under the machining efforts, assumable by the tooling, and maintains its adaptation to the curvature , and it is economical because it is an available material.

Other advantages related to features of the dependent claims are cited in the detailed statement of the embodiment of the invention.

BRIEF DESCRIPTION OF THE FIGURES

The present specification is complemented with a set of figures, illustrative of the preferred example, and never limiting the invention.

Figure 1 represents a profile view of the tooling with a support with a first plate. The right half shows the supports while the left is fairing hiding them.

Figure 2 represents a plan view of the first face of the first plate showing the grilles.

Figure 3 represents a sectional view of a detail of the support with a sheet of a porous material.

Figure 4 represents a plan view of the second face of the first plate showing strips. For clarity, only one of the strips of the supports is represented with a dotted line.

Figure 5 represents a plan view of the support without iron showing the supports. For clarity, only one of the strips is represented with a dotted line of the first iron.

Figure 6 represents a sectional side view of a pillar.

Figure 7 represents a side view of a pillar placed by the head of a machine.

Figure 8 represents a part of the same side view of Figure 6 in which the support has extended in height.

Figure 9 represents a part of the same side view of Figure 6 in which the support has been oriented by a turn.

Figure 10 represents a side view of a part of the tooling showing the first and second strip where the first plate is several plates.

Figure 11 represents the same view as Figure 9 in which another plate has been superimposed.

Figure 12 represents a side view of a part of the tooling showing a second plate.

Figure 13 represents a plan view of the first plate with grooves.

Figures 14A to 14D represent different stages in which a third plate is placed on the piece and is helped with rollers and flanges to achieve curvature. Arrows indicate movements of rotation and translation of the rollers.

EXHIBITION OF CARVING OF THE PREFERRED EMBODIMENT OF THE INVENTION An embodiment of the invention with support in the figures is set forth below.

Figure 1 shows the tooling for machining parts with curvature comprising a support (1) that adopts said curvature, said support (1) arranged on at least two supports (2) comprises at least a first plate (1.1) of a semi-flexible material on which the piece (3) to be machined, non-porous and impermeable to air is deposited.

The semi-flexible material is hardness greater than 40 Shore A, Young's modulus greater than 3 MPa and breaking stress greater than 0.75 N / mm ² , the distance between supports

(2) is equal to or less than 175 rom, so that the support (1) does not deform under machining efforts and maintains its adaptation to curvature.

Thus, the first plate (1.1) does not deform excessively by its own weight due to the distance between supports (2). The distance between supports (2) is a characteristic that is not defined as critical in this type of materials because they are not designed for this use, so the selection of the material together with the distance between supports (2) is something not contemplated in the state of the art and characteristic of the invention. With this, the first plate (1.1) is able to withstand the machining efforts, for example, maximum process forces of less than 0.65 N / mm ² are estimated.

Specifically, a semi-flexible material option is nitrile butadiene (NBR).

It is advantageous that the face of the first plate (1.1) in contact with the part, first face (1.10), is a smooth non-slip surface with friction coefficient greater than 0.7, said first plate (1.1) is capable of absorbing vibrations of high frequency equal to or greater than 50 Hz derived from the machining process, normally due to the tapping of the teeth of the tool against the part (3) when it is made of sheet metal, while the tool rotates and advances. In the known, the working range in which the behavior of this type of materials is used and studied is limited to lower frequencies, between 30 Hz and 50 Hz.

Preferably, as shown in Figure 2, the first face (1.10) of the first plate (1.1) has at least one grid (1.11), each grid (1.11) being composed of grooves (1.12) connected to each other; In addition, the option of connecting a high flow vacuum pump (5) to each grid (1.11), figure 3 is added. Thus, it helps to keep the part (3) properly tied to the first plate (1.1), helped by the high flow vacuum pump (5). This system distributes the vacuum throughout the entire work surface.

One option is that between the piece (3) and the first plate (1.1) there is at least one sheet (4) of a porous material, figure 3, as a sacrificial material and that helps maintain the gap between the plate (1.1) and the piece (3). In addition to milling, this material allows reheating, cutting and / or drilling operations. In addition, this sheet (4) redistributes the vacuum more evenly so losses are reduced. This allows working with parts (3) smaller than the vacuum grids (1.11). It is a significant advance because for this you do not need any type of joint adapted to each geometry or piece size (3).

Figure 3 shows a sleeve (13) that ends in a fitting (12) connected to an outlet duct (1.15) for each grid (1.11). This elements they are valid for all figures, although not complicating them, they are only represented in the option of figure 3. Preferably, each support (2) provides a linear and continuous support, figures 1, 4 and 5, on the supports (2 ) the face of the first plate (1.1) opposite the piece is supported, second face (1.13), so that the curvature is achieved, each support (2) is arranged on at least two pillars (6), pillar layer ( 6) comprises a foot (6.1) slidably attached to a frame (7) of the tool on which it can be moved, a body (6.2) of adjustable height and an adjustable head (6.3), figure 6. As can be seen in said figure 6, the foot (6.1) in this embodiment presents a projection that runs inside a housing in the frame (7), although it could be carried out in any other known way, the same can be said of the height adjustment of the body (6.2) shown as a piston running inside a jacket, and the same for fixing the head (6.3) to each support (2), represented by a bar fixed by screws. In figures 1, 5, 7, 10 and 11 a central support can be seen without pillars (6) as described, specifically in figure 5 it is represented with four supports (2) on each side. It is an advantageous central support option as a reference point to position the rest of the supports (2) and therefore does not need adjustment in height or orientation.

Thus, the height, orientation and distance between the supports (2) can be modified manually, semi-automatically by the assistance of the machine or automatically directly by the machine or an external control. With this configuration it is possible adapt the support and mooring of parts (3) from flat geometries to any simple curvature.

The positioning of the supports (2) by the machine head (14) can be carried out by joining each of them using a fixation to, for example, the central area (15) of each of the supports ( 2), figure 5, using fixings known as Vero-S® from Shunk®. In the way of doing it, first the support (2) slides in the longitudinal direction of the tooling, at that point they are blocked by brakes (mechanical, pneumatic or hydraulic), figure 7, then it is adjusted to the desired height, it is locked at that point (also by means of mechanical, pneumatic or hydraulic brakes), figure 8, it is finally rotated in such a way that it is tangent to the curvature of the support (1) and at that point it is locked (mechanical, pneumatic or brake hydraulic), figure 9. This manipulation of the tooling with the machine head (14) is a great advantage over other solutions that have an axis and commanded by the machine control for each support (2).

Optionally, fixing means (8) are arranged between the first plate (1.1) and the supports (2), said fixing means (8) are of the type of a first strip (8.1) with flexible spikes that end in the form of a hook or mushroom that is fixed to a second strip (8.2) with flexible spikes that end in the form of a hook or mushroom or with tangled fibers that form loops and that allow the grip of each hook or mushroom, along a portion of each support (2) a first (8.1) or second strip (8.2) is arranged, on the second side (1.13) of the first plate (1.1) a second (8.2) or first strip is arranged in correspondence and transversely (8.1), so that there is a contact area between a first and a second strip, figures 4 and 5. The arrangement of one strip over another or vice versa does not affect the fixation between the two, so that its relative arrangement is indifferent each. These strips are Velero®, DualLock® 3M® or similar. These strips (8.1,8.2) provide a joint:

• continues, giving greater rigidity to the support of the plate (1.1) on the supports (2);

· Reusable, easy to remove and put on; because each time the curvature is changed, the plate (1.1) must be removed, the supports (2) must be placed in the desired position and then the plate (1.1) will be tied again;

• non-mechanical, a mechanical type could deform the plate material (1.1);

• stiffener, arranged as a "rib", improves geometric accuracy.

Thus, in the exposed arrangement, figures 4 and 5, the strips (8.1,8.2) are placed along the supports (2) and covering a large plate surface (1.1). The transverse arrangement facilitates the set-up of the mooring (greater ease in handling the plate (1.1)).

As shown in Figure 10, several first plates (1.1) can be arranged contiguously so that the edges of each one that supports the tooling do so on the supports (2) so that there is no edge left located between supports (2). This option solves the problem that the plates (1.1) have a width that is defined by the dimensions of the presses that manufacture them; therefore, if a greater width is needed it can be solved using more than one first plate (1.1). On the other hand, since the plates (1.1) could be damaged during machining, it is convenient to use smaller ones so that in case of repair their change is easier and more economical since they are smaller.

Another similar but more stiffening option than the previous one, shown in Figure 11, is that several first plates (1.1) are arranged contiguously in several overlapping layers so that the edges of each of them that contact each other do not coincide with each other. contiguous layers, that is to say, they are arranged alternately or to the tresbolillo. The curvature that has been cited can be of any type, for example, simple, either concave or convex, or double, concave or convex or a combination of both. When the simple curvature requires it or when there is double curvature it is preferable that between the first plate (1.1) and the supports (2) a second plate (1.2) is arranged on whose upper face (1.20) at least a third strip ( 8.3) to correspond with a first (8.1) or second strip (8.2) on the first plate (1.1), on whose lower face (1.21) there are means for joining and adjusting height (9), so that it produces a local elevation to provide a curvature, figure 12. Specifically and as an option, the joining and height adjustment means (9) are a fourth strip (9.1) of the same type as the first (8.1) or second strip (8.2) , to correspond with a fifth strip (9.2), of the same type as the fourth strip (9.1), on the supports (2). That is, a double tooling is done locally, in an area of the first plate (1.1) duplicate it with a second plate (1.2) and duplicate the same joining means. Another option not shown is that the joining and height adjustment means (9) were integrated in the supports (2) or were of another type, such as endless screws, external to them.

One option is that the support (1) has diagonal grooves (1.14) from each vertex to the vicinity of the center of the support (1) so that the grooves (1.14) do not touch each other, figure 13. Thus, when there is very pronounced double curvature the adaptation to it is facilitated.

In small, thin and flat pieces (3) it is relatively easy to achieve vacuum conditions on the tooling. However, as the size and / or thickness increases, or if it comes with a preset curvature, Figure 14A, bringing it to a suitable support and mooring condition against the first plate (1.1) is more complicated. To facilitate this work, the vacuum flow of the pump (5) can be increased, although since the diameter of the hole through which the vacuum is made is predefined, there may be several cases in which it is not sufficient. In these cases it is necessary to have a tread system that "pushes" the piece (3) against the first plate (1.1), of sufficient dimensions and that is also semi-flexible. Therefore, the best option is a third plate (1.3) that is arranged on the part (3), figure 14B, and pushes it to adapt it to the first plate (1.1). Thus, until adequate vacuum conditions are achieved.

Thus, this option provides a pusher (10) that acts on the third plate (1.3) so that it helps the piece (3) to adapt to the curvature of the support (1), figure 14C, although they can be several, figure 14D, specifically in the form of a roller. Additionally, at least one lateral flange (11) can be arranged to tie the support (1) with the first plate (1.1) with the part (3) and with the third plate (1.3). In short, as shown in Figures 14A to 14D, the process would be carried out in the following sequence:

1-The piece (3) is placed with a defined curvature on the first plate (1.1), figure 14A.

2-The third plate (1.3) is placed on the piece (3), figure 14B.

3- The vacuum is applied and the third plate (1.3), figures 14C and 14D are pressed with rollers (10).

4- The third plate (1.3) is kept pressed until the correct vacuum is obtained throughout the surface.

4.-It may also be necessary to step on, tie each other with flanges (11), figure 14D, the sandwich formed by the first plate (1.1), the piece (3) and the third plate (1.3) to reduce temporarily vacuum losses.

5- The third plate (1.3) is removed.

Claims

1.-Tooling for machining parts with curvature comprising a support (1) that adopts said curvature, said support (1) arranged on at least two supports (2) comprises at least a first plate (1.1) of a semi-flexible material on which the piece (3) to be machined, non-porous and impermeable to air is deposited, characterized in that the semi-flexible material is hardness greater than 40 Shore A, Young's modulus greater than 3 MPa and breaking stress greater than 0, 75 N / mm ² , the distance between supports (2) is equal to or less than 175 rom, so that the support (1) does not deform under the machining efforts and maintains its adaptation to the curvature.

2. - Tooling according to claim 1 wherein the semi-flexible material is nitrile butadiene (NBR).

3.-Tooling according to any of the claims

1 or 2 in which the face of the first plate (1.1) in contact with the part (3), first face (1.10), is a smooth non-slip surface with friction coefficient greater than 0.7, said first plate (1.1 ) is capable of absorbing high frequency vibrations equal to or greater than 50 Hz derived from the machining process.

4.-Tooling according to any of the preceding claims in which the first face (1.10) of the first plate (1.1) has at least one grid (1.11), each grid (1.11) being composed of grooves (1.12) connected to each other .

5. Tooling according to claim 4 comprising a high flow vacuum pump (5) connected to each grid (1.11)

6. Tooling according to any of claims 4 or 5 wherein between the piece (3) and the first plate (1.1) at least one sheet (4) of a porous material is provided as a sacrificial material and collaborates Keep the gap between the plate (1.1) and the piece (3).

7.-Tooling according to any of the preceding claims in which each support (2) provides a linear and continuous support, on the supports (2) the face of the first plate (1.1) opposite the piece (3) is supported, second face (1.13), so that the curvature is achieved, each support (2) is arranged on at least two pillars (6), pillar layer (6) comprises a foot (6.1) fixed to a frame (7) of the tooling on which it can move, a body (6.2) of adjustable height and an adjustable head (6.3).

8. Tooling according to claim 7 wherein fixing means (8) are arranged between the first plate (1.1) and the supports (2), said fixing means (8) are of the type of a first strip (8.1) with flexible spikes that end in the form of a hook or mushroom that is fixed to a second strip (8.2) with flexible spikes that end in the form of a hook or mushroom or with tangled fibers that form loops and that allow the grip of each hook or mushroom, along a portion of each support (2) a first (8.1) or second strip (8.2) is disposed, on the second side (1.13) of the first plate (1.1) a second is arranged in correspondence and transversely (8.2) or first strip (8.1), so that there is a contact area between each first (8.1) and each second strip (8.2).

9.-Tooling according to any of the preceding claims in which several first plates (1.1) are arranged contiguously so that the edges of each of them that supports the tooling do so on the supports (2) so that there is no edge between supports (2).

10. Tooling according to claim 9 wherein several first plates (1.1) are arranged contiguously in several overlapping layers so that the edges of each of them that contact each other do not coincide between adjacent layers.

11.-Tooling according to any of the preceding claims in which the curvature is simple, concave or convex, or double, concave or convex or combination of both.

12.-Tooling according to any of the preceding claims wherein between the first plate (1.1) and the supports (2) a second plate (1.2) is disposed on whose upper face (1.20) there is at least a third strip (8.3 ) to correspond with a first (8.1) or second strip (8.2) on the first plate (1.1), on whose lower face (1.21) there are means for joining and adjusting height (9), so that it produces an elevation local to provide a curvature.

13. Tooling according to claim 12 wherein the joining and height adjustment means (9) are a fourth strip (9.1) with flexible spikes that end in the form of a hook or mushroom, or with tangled fibers that form loops and which allow the grip of each hook or mushroom, to correspond with a fifth strip (9.2) of the same type as the fourth strip (9.1) on the supports (2).

14. Tooling according to any of the preceding claims in which the support (1) has diagonal grooves (1.14) from each vertex to the vicinity of the center of the support so that the grooves (1.14) do not touch each other.

15.-Tooling according to any of the preceding claims comprising a third plate (1.3) that is arranged on the part (3).

16. - Tooling according to claim 15 comprising at least one pusher (10) acting on the third plate (1.3) so as to help the piece (3) adapt to the curvature of the support (1).

17.-Tooling according to claim 16 wherein the pusher (10) is at least one roller.

18.-Tooling according to any of claims 15 to 17 wherein at least one lateral flange (11) is provided for mooring the support (1) with the first plate (1.1) with the part (3) and with the third plate (1.3).