DE3113062A1 - "METHOD FOR DRILLING HOLES WITH A PREDICTED DIAMETER IN AN ARRANGEMENT OF PLATED PLATES, INCLUDING AT LEAST A PLATE OF GLASS OR CARBON REINFORCED MATERIAL, AND AN" ALUMIUM PLATE - Google Patents

Description

AERITALIA Societä Aerospaziale

Italiana p.A.,

Piazzale V. Tecchio 51 / A

Turin / Italy

"Method of drilling holes with a predetermined Diameter in an arrangement of plates arranged one above the other, comprising at least one plate made of glass or carbon fiber reinforced material and an aluminum plate "

The invention relates to a method for making holes. of a predetermined diameter in an array of one above the other arranged plates, comprising at least one plate made of glass fiber or carbon fiber reinforced material and an aluminum plate.

Composite panels of this type are used in aerospace engineering to create structures with very high mechanical strength and extremely low weight. To the two plates the arrangement to be firmly connected to each other and / or to other parts of a structure, the panels are connected by connecting elements connected to each other in corresponding holes made therein can be used.

The invention relates to a method for producing such Holes in composite panels of the specified type.

Such drilling is usually done with the help of a manually controlled Drill or by means of a suitable drilling machine, which is provided with a tool carrier head, which is pre-determined with a Feed speed is movable on suitable guides. In

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A twist drill made of tungsten carbide is used as a tool for both balls.

Have bores made in this known manner various disadvantages, which make them unsuitable for aeronautical constructions, for the construction elements entirely free of elements are required.

Bores, which are produced in the specified manner, have usually numerous defects, and not only because they are not designed in terms of shape and dimensions according to the desired are, but because in particular the surfaces of the holes and the areas in the immediate vicinity thereof are damaged, whereby the mechanical strength of connections, which are made herewith, is impaired, while, however, the connections in a known manner have to withstand very high workloads.

Sometimes small breaks and broken pieces of fibers appear in the edge area of the holes in the plate made of glass fiber or carbon fiber reinforced Material or damage to the surfaces of the holes found that were generated by drilling chips of the aluminum. Furthermore, the surfaces of the holes produced in this way are very rough. In addition, it is only possible to obtain very wide tolerances with regard to the diameter of the bores, and these often have an undesirable one oval or conical shape.

Ultimately, there is considerable wear and tear on the tools, which is mainly due to the action of the carbon fibers on the cutting edges of the tool. The tools must therefore be replaced frequently.

The object of the invention is therefore to create a method of the type mentioned at the outset in which the above-mentioned disadvantages are eliminated are, so that bores can be economically produced without defects, in which shape and dimensions are the desired accordingly, with very tight tolerances and a high surface quality being obtained.

The invention therefore relates to a method for producing bores of a predetermined diameter in an arrangement of Plates arranged one above the other, comprising at least one plate

fiberglass or carbon fiber reinforced material and an aluminum plate, the thickness of these plates between 2 and 1o im or 2 and 8 in lies, which is characterized in that a first for each hole Drilling process is carried out with the help of a manually controlled drill, that with a twist drill head with a first diameter smaller than that of the predetermined end diameter is provided to at the end of the first drilling operation to obtain a bore with a diameter substantially equal to the first diameter, after which a second operation to enlarge the hole obtained at the end of the first operation is made with the help of a manually controlled drill, which is a twist drill head having two sections of different diameters, a first section with a diameter equal to the predetermined one Final diameter reduced by 1/32 "(0.078 cm) and a lower section with a diameter equal to that of the upper section reduced by 1/32 "(o, o78 ση) to drill a hole with a diameter equal to the final diameter reduced to obtain 1/32 "(o, o78 an), followed by a third operation to broach the at the end of the second operation obtained drilling with the help of a manually controlled Drill is provided with a broach vorgenoimen that two sections of different diameter, an upper portion with a diameter equal to the final diameter and a lower portion Section with a diameter equal to the diameter obtained at the end of the second operation, so that the broach with the help of the lower section of the tool itself guided during the broaching process will.

Further refinements of the invention can be found in the claims and the following description.

The invention is explained in more detail below with reference to the accompanying figures.

1 and 2 show schematically the arrangement of two plates at the beginning and at the end of the first working process,

3 and 4 show schematically the arrangement of the two plates at the beginning and at the end of the second working process,

Fig. 5 and 6 show schematically the arrangement of the two plates at the beginning and at the end of the third work process,

FIGS. 6 and 7 show the plate arrangement at the beginning and at the end of an alternative working process to FIG.

The inventive method is used to drill holes in a Arrangement of plates arranged one above the other, as shown in FIG is and from at least a first plate made of glass fiber or carbon fiber reinforced Material and a second aluminum plate 2 is used. Disk assemblies of this type are widely used used in aeronautical constructions to construct construction pension with very high mechanical strength and extremely low weight. The connection between the panels of the arrangement or between different structural elements is made with the aid of connecting elements achieved, which are used in bores that can be produced by the method according to the invention.

The best results are obtained with the method when the thickness of the two plates 1 and 2 is between 2 and 10 µm and 2 and 8 mm, respectively. The diameter of the holes is usually between 4 and 6.5.

A first drilling process is required to produce each of these holes with the help of a manually controlled drill (not shown), equipped with a twist drill tool 4 made of tungsten carbide is. The relative position of the drilling tool 4 with respect to the plate assembly at the beginning of the first operation is shown in FIG.

The twist drill is a normal right-hand twist drill of the type used in ordinary drilling operations, such as spiral flutes forming an angle of 3o with the

Form the axis of the drill. The angle of the drill tip ⁰ ^ in Fig. 1 must be 135 °.

The diameter d of the drilling tool is 1/2 and 2/3 of the predetermined

th final diameter of the hole that you want to make, while the Rotational speed of the drill itself, which is constant during the entire first working process, must be between 28oo and 9ooo rpm.

The first operation is carried out wildly by the twist drill 4 is inserted into a guide bush 5, which is supported in a suitable manner, for example by means of a plate 6, and its axis coincides with that of the hole to be made, so that the drill while it penetrates through the arrangement of the plates 1 and 2, is firmly guided. For this purpose, there is a diameter clearance between the drilling tool and the inner surface of the socket 5, which must be of the order of o, o1 mn. The height h of the socket 5 is usually between 25 and 30 mm.

To carry out this operation, after the bushing 5 has been arranged so that its axis coincides with the axis of the The hole coincides, the twist drill 4 is inserted into the socket 5, sufficient force is manually applied to the drill to determine the drill advance. During this process, the central core of the bore substantially removed, so that with sufficient speed, as can be seen from Fig. 2, a bore with substantially a diameter d, which is made with respect to both

Dimensions as well as from the point of view of the surface texture not needs to be very regular. Whom the diameter of the final hole should be very low, the first operation described can be omitted.

The second operation consists in enlarging the one so produced Drilling. In Fig. 3, the tool used here is shown schematically, which is again formed from a twist drill 7, which is shown in with respect to the arrangement of the plates 1 and 2 at the beginning of this operation is shown in FIG.

The twist drill 7 comprises two sections, a lower section 9 and an upper portion 8 with different diameters, the diameter of the upper portion d is with the predetermined final one Diameter d ^ of the hole linked by the following relation:

d _c = d _f - 1/32 "(1)

while the diameter d, of the lower section 9 with the diameter d (and therefore according to (1) with the diameter d _f ) is linked by the following relation:

d _d = d _c - 1/32 "= d _f - 2/32" (2)

Except for the presence of two sections different The diameter of the twist drill 7 is a normal right-cutting Wblrairkarbid twist drill, for example with spiral flutes, the 30 ° inclined with respect to the axis of the drill. The angles (2> (Fig. 3) at the tip and in the connection area to the lower section 9 and the lower section 8 of the drill 7 are equal to 135 °.

During this operation, the twist drill 7 is also attached to a manually controlled drill (not shown).

The speed of the drill 7 must be in the range of 28oo to 9oco rpm to get voted.

During this operation, the twist drill 7 is guided through a socket 1o, which in a suitable manner, for example by means of a Plate 11, is supported. The remaining game between the drill bit and the inner surface of the socket 1o is also o, o1 um, while the height h of the socket 1o is between 25 and 30 mm.

During this operation, the one at the end of the first operation obtained bore with the diameter d initially through the

lower section 9 and then enlarged by the upper section 8 of the drill 7, so that, as can be seen from Fig. 4, at the end of this operation, a bore with a diameter d is obtained, which according to equation (1) is slightly smaller than the final one Is diameter d _f to be obtained.

In the third operation, the hole obtained in this way is broached in order to bring it to the final desired diameter and its To give the surface a very high surface quality.

The broach used during this process is shown in Fig. In the relative position it is with respect to the arrangement of plates 1 and 2 at the beginning of this operation.

The broach is a normal tungsten carbide bore broaching tool that includes two sections of different diameters, a lower section 16 and an upper section 17 with corresponding diameters d and d _f, respectively. The connection angle q between the

intersections 16 and 17 and the point angle ^ (Fig. 5) is 135 or 9o °. The broach 15 becomes like the tools in the previous ones Operations attached to a manually controlled drill and guided here through a socket 18. Between the broach 15 and the inner surface the bush 18 has a diameter clearance of 0.01 mm. The speed of the broach must be between 23oo and 28oo rpm.

During the third operation, the lower section 16 of the broach 15 is inserted into the bore, the diameter of which is the same that of this section itself, so that the upper section 18 is firmly guided by this coupling. While the broach is moving 15 this takes a complete clearance of the bore of the Diameter d before to provide a final diameter d ^ (Fig. 6).

Holes made this way are perfect cylindrical, and the diameter tolerance with respect to the nominal diameter is in the order of magnitude of 0.02 "(0.05 ntn). Also the The surface quality is extremely high and almost reflective. The middle Roughness obtained in this way is equal to or less than 8o RHR. No damage to the edges of the holes in the panels 1 and 2 occurs; these edges are free from delamination or other defects.

If so, drill holes with those just described Properties, but to produce with larger tolerances with regard to the diameter, which lie between o, oo2 "(o, o5 mm) and o, oo3" (o, o76 mm), the guidance of the tool (twist drill and broach) can be simplified in the three work processes. These can be used instead of the Guiding through the sockets 5, 1o and 18 easily and less precisely with the help vcti normal clamping devices, as shown by way of example in FIG are to be guided. These usually comprise a plate 2o which is provided with holes 21, the axes of which correspond to those of the ones to be produced Bores coincide, as well as a socket 22, which is in a the holes 21 can be inserted and to which an Abdedcscheibe 23 is rigidly attached is, in the opening of which the spiral cutter or the broach is inserted will.

Claims (6)

AERITALIA Societä Aerospatiale Italiana ρ ¹ .Α. Turin A η s ρ r ü c h e Method for producing bores with a predetermined diameter in an arrangement of plates arranged one above the other, comprising at least one plate made of glass fiber or carbon fiber reinforced iteterial and an aluminum sheet, the thickness of the Plates between 2 and loran or 2 and 8 mm, characterized in that a first work step with the aid of the production of each hole a manually controlled drill using a twist drill with a first diameter smaller than the predetermined one Final diameter to obtain a treatment at the end of the first step is provided with a diameter substantially equal to this first diameter, after which a second operation to enlarge the The bore obtained in the first step was controlled with the help of a mamjell Drill is made, the with a Spiraltohrwerkzeuq is provided having two portions of different diameters, an upper portion with a diameter equal to the predetermined one Final diameter reduced by 1/32 "(o, o78 cm) and a lower section reduced with a diameter equal to that of the upper portion by 1/32 "(o, o78 cm) to make a hole with a diameter substantially equal to that of the end diameter knife at the end of the second pass reduced to get 1/32 "(o, o78 an), followed by a third pass for broaching the bore obtained in the second operation is carried out with the help of a manually controlled drill, which is carried out with a Rüuntwerkzeug is equipped, which has two sections of different diameters, an upper section with a diameter equal that of the final diameter and a lower portion with a diameter equal to that obtained at the end of the second operation Diameter so that the broach is guided through its lower portion during the broaching process. 2. The method according to claim 1, characterized in that in the first and second operation, the speed of the twist drill in the range between 2800 and 900 rpm is selected, while the third step selected the speed of the broaching tool in the range of 23oo ~ 28oo rpm will. 3. The method according to claim 1 or 2, characterized in that to achieve a tolerance less than or equal to o, co2 "with respect to the predetermined final diameter of the bores, the twist drill or the Broaching tools are guided during each of the three operations with the aid of a guide bushing, the length of which is between 25 and 3o itm, with the respective Vferkzeug in the guide bush with a clearance in the order of magnitude of o, o1 mn is used. 4. The method according to any one of claims 1 to 3, characterized in that that to achieve a tolerance with respect to the predetermined final diameter the hole equal to or greater than o, oo2 "the twist drill or the broach be guided during the three operations by means of a device comprising a plate which is to be provided with holes above the Plate assembly can be arranged and has a plurality of holes, with at least one socket in each of these holes the plate can be used and is provided with a guide opening by means of which the twist drill or the broach can be guided. 5. The method according to any one of claims 1 to 4, characterized in that that the angle at the tip of the drilling tool of the first operation is 135 °. 6. The method according to any one of claims 1 to 5, characterized in that that the angle of the tip of the broach 9o ° and the angle of the connection between the lower and upper portions of the broach 135 °.