DE102007009641B4 - Device for guiding a milling tool and its use - Google Patents

Abstract

Device for guiding a milling tool for machining a curved surface (92) of a workpiece (90) comprising a frame (12) which can be locked on the surface (92) of the workpiece and a region bounded by the frame (12) relative to the frame ( 12) movable tool holder (16) for the milling tool,
wherein a first guide rail assembly (18-1, 18-2) elongated in a first direction (x) is provided for movability of the tool holder (16) in the first direction (x),
wherein the frame (12) comprises a second guide rail assembly (12-1, 12-2) elongated in a second direction (y) transverse to the first direction (x) for movability of the first guide rail assembly (18-1, 18-2) in the second direction (y) comprises
characterized in that the first guide rail arrangement (18-1, 18-2) as such and / or the second guide rail arrangement (12-1, 12-2) as such has a curved course of curvature adapted to the curvature of the surface (92) to be machined ,

Description

The invention relates to a device for guiding a milling tool according to the preamble of claim 1 and to the use of such a device according to claim 8.

Such a tool guide is for example from the DE 43 20 750 A1 known. In this publication, to repair a component made of carbon fiber reinforced plastic (CFRP), it is proposed to guide a milling cutter over a curved component surface by means of the tool guide in such a way as to create a so-called puncture of the damage area around the damage center (eg hole). By subsequent grinding a conical Schäftungsfläche is formed, on which then a repair patch is glued.

Also from the US 6,926,094 B2 a tool guide is known, wherein a guideway assembly is guided over the component surface in the xy direction. From the JP 8 252 710 A a milling device is known. The WO 01/94072 A1 describes a tool guide by means of a guide rail assembly.

The known tool guide is relatively complicated and bulky. The frame of the tool guide, which can be locked on the component surface, consists of a plurality of respectively two-limbed articulated arms (eg "tripods") whose positions and joint positions must first be carefully adjusted and fixed so that a bearing housing hinged to inner joint legs of the frame in the center of the device properly oriented and positioned. The actual tool holder for the milling tool is connected via an adjustable pivot lever assembly with the bearing housing. After a once made adjustment of the tool guide, the tool holder can be performed with the milling tool only along a circular path around the centrally arranged bearing housing around.

The result of the known repair is not satisfactory in all applications. In addition, the operation of the tool guide requires some experience in order to achieve a well-defined relationship as possible (ratio between the radius of the conical surface and the depth of the conical surface or component thickness). Inaccuracies of the Schäftungsform would have the consequence that an "adaptable" repair material is required, for example, after the introduction into the Schaftung still in a separate step forma-fitting and curing repair patches.

It is an object of the present invention to provide a simple and compact constructed tool guide of the type mentioned.

This object is achieved by a device for guiding a milling tool according to claim 1. The dependent claims relate to advantageous developments of the invention.

It is essential for the invention that a first guide rail arrangement elongated in a first direction is provided for movability of the tool holder in the first direction, that the frame comprises a second guide rail arrangement elongated in a second direction transverse to the first direction for movability of the first guide rail arrangement in the second Direction includes, and that the first guide rail assembly and / or the second guide rail assembly has a curvature adapted to the curvature of the surface to be processed curved guideway course.

Unlike the known tool guide described above can be realized with the tool guide according to the invention in a simple manner virtually any trajectories for the tool holder together with milling tool. Essential for this is a "functional coupling or series connection" of two transversely oriented guide rail arrangements. For the invention is also essential that - unlike a conventional "x-y-guide" - at least one of the two guide rail assemblies has adapted to the curvature of the surface to be machined curved guideway course.

The concrete design of the milling tool used is of secondary importance in the context of the invention. It can be used in an advantageous manner known per se, suitable for machining, tools, in particular rotary cutting tools.

If the surface of the workpiece to be machined is only curved in one direction (eg cylindrical surface section), then it is sufficient if either the first or the second guide rail arrangement with the suitably curved guideway course is provided. Accordingly, for surfaces that are curved in two directions (eg, spherical surface portion), both of the guide rail assemblies have a suitably curved track course. If the surface is only curved in one direction or there is no rotational symmetry of the surface with respect to a normal in the case of a curvature in two directions, then an adjustment of the (curved) "Milling plane" to the (curved) workpiece surface to orient the entire tool guide according to the azimuth angle.

With regard to the most universal usability of the tool guide, an embodiment is particularly advantageous in which at least one of the two guide rail arrangements can be exchanged easily (for example, after loosening a screw connection). For example, an assortment of guide devices of different length and / or curvature can be provided, from which a device suitable for the relevant workpiece surface is selected and used as first or second guide rail arrangement of the tool guide.

With regard to the locking of the frame on the workpiece surface, the device may for example comprise a Saugfußanordnung, in particular a plurality of distributed over the circumference of the frame arranged and preferably hingedly connected to the frame suction cups.

In an embodiment, it is provided that the first guide rail arrangement comprises a pair of guide rails running parallel to one another. The term "parallel to each other" is to be understood here as including an identically curved course of the two guide rails.

With a curvature of the guide rail pair can be realized in a simple manner, a corresponding curvature of the so-managed guideway course. It should be noted, however, that a curved guideway course by no means necessarily requires a corresponding curvature of the respective guide rails. For example, in the case of a straight guide rail, a guide path which is curved to a certain extent can be realized by a correspondingly curved guide projection or a correspondingly curved guide groove (eg oblong hole).

If a guide rail arrangement is formed from a pair of mutually parallel guide rails and should be interchangeable, it can be provided that the two guide rails of the pair are firmly connected to each other.

In a preferred embodiment it is provided that the frame is formed of four parallelogram-like, in particular rectangular, interconnected frame parts, of which two frame members lying opposite one another support or form the second guide rail arrangement. In this case, the first and second directions of the first and second guide rail assemblies are defined by the two "parallelogram directions".

Regarding a simple Verschraubbarkeit and interchangeability of frame parts, which z. B. form a guide rail assembly or serve as "spacers" between two guide rails of a pair of guide rails, it is particularly advantageous if the frame has an overall rectangular shape.

In a parallelogram-like, in particular rectangular frame is provided according to a development that in the course of at least one of the four frame parts at one or more points in the longitudinal direction, a device or mark is provided which as "positioning aid" for the positioning of the tool holder with respect to the tool Frame and / or for positioning the entire device with respect to the workpiece surface to be machined is useful.

In one embodiment, it is provided that the guideway course of the second guide rail arrangement is predetermined by oblong holes in opposite frame parts of the frame. The course of the elongated holes then determines whether and, if appropriate, to what extent the relevant guideway is curved.

In a particularly advantageous embodiment for many applications, it is provided that a linkage connected to the tool holder is provided for controlling the movement of the tool holder relative to the frame. In this regard, it should be considered that in the device according to the invention by the coupling of two guide rail assemblies in transverse directions, a mobility of the tool holder is provided along a surface. However, if you want to move the tool holder within this achievable area along a predetermined, lying in this area tool guideway, the corresponding drive and / or a corresponding positive guidance of the tool holder can be realized with such a linkage in a simple manner.

In a preferred embodiment of this linkage control of the tool holder movement is provided that the tool holder is firmly connected to one end of at least one control rod, the other end extends out of the area bounded by the frame and driven there during the milling process and / or forced.

The linkage for motion control, for example, a part of a mechanical Forming a copy unit for defining a tool guideway based on a template. As far as the formation of the linkage or the template is concerned, it is advantageously possible to make use of the prior art from the area of so-called copy milling machines. In the simplest case, the copying unit can provide that a trajectory defined by the template used is imaged 1: 1 on the tool guideway. However, it should not be ruled out that the copying unit, in the manner of a so-called pantograph, provides for an imaging ratio not equal to 1: 1.

In a definition of the tool guideway based on a template can be provided that at least a portion of the frame has on its outer side fastening means for releasably securing the stencil to be used.

By using the device according to the invention, it is advantageously possible in principle to carry out any desired milling work on workpiece surfaces, in particular curved workpiece surfaces, in a simple manner.

A preferred use is, for example, the shanks of the workpiece.

More generally, the term "shank" refers to a recess formed on a workpiece (or the corresponding process), the depth of which increases conically towards the center of the recess. For this purpose, the Schäftung z. B. be created by milling away gradually enlarged in diameter concentric circular rings. In the sense of a "hand-milling unit" here an operator can move the tool holder manually on the respective circular path around the center of the work around, this circular path z. B. by means of a copying unit of the type described above of a template defined (enforced) is.

In order to achieve the most exact possible conical shape of the milled bearing surface, it is conceivable to use a milling tool for the incrementally increased in diameter (but reduced in the milling depth) Fräsgängen, which already prepares the conical shape of the respective circular ring area according to the desired Shawn ratio at each Fräsgang , Alternatively, a "stepped shank" created by milling stepwise enlarged diameter concentric annulus areas may be appropriately post-processed (eg, by abrading) to obtain a cone shape.

The term "stepped stiffening" is intended to express that although the recess depth increases towards a center of the recess, the recess surface does not have a cone-shaped but at least one step. In the context of a special application of the device according to the invention or of the method of stitching effected therewith as described below, such a stepped support is of particular advantage.

Both for the formation of a tapered shank and the formation of a stepped shank, provision may also be made for the shank to be created by milling out progressively reduced diameter concentric circular areas, as already mentioned above DE 43 20 750 A1 is proposed. Also in this case, the tool holder movement can be forcibly limited to the desired circle area by means of a copying unit.

• – Schäftung des Bauteils im Bereich einer Schadensstelle, und
• – Einbringung von Reparaturmaterial in die Schäftung.

A preferred use of the device according to the invention consists in the repair of a component, in particular z. B. a fiber composite component, comprising the steps:

• - Lining of the component in the area of a damaged area, and
• - Carrying of repair material in the Schäftung.

This type of repair is as such from the above DE 43 20 750 A1 However, it is particularly convenient to carry out by means of the device according to the invention.

According to a development of this repair method, it is provided that the shank is formed with a step surface and, as the repair material, a repair piece prefabricated with a corresponding step surface is introduced into the shank.

The formation of a shank with a predetermined step surface is often simpler and more precise in practice than the formation of a corresponding conical surface. The introduction of a prefabricated repair piece with a corresponding step surface therefore requires, if at all, at most slight shape adjustments. With sufficiently precise training of the stepped stiffening as well as the prefabricated repair piece is advantageously a "flush" repair of the damage possible, especially without a separate step for reworking the Schaftung or for adapting the shape of the repair piece. In addition, the repaired according to the invention component site tends to be more resistant to later occurring mechanical loads.

A preferred application of the invention is for the repair of structural components in the aerospace industry. Both flat and curved components or Component surfaces to be repaired, in particular z. B. plate or cup-shaped components. In the component to be repaired, it may, for. B. may be a curved in one or two directions fuselage shell.

In one embodiment, it is provided that the component is a fiber composite component (eg made of CFRP) or a light metal component.

The step surface may have rounded and / or abgefufste step edges, for example, thereby to reduce notch effects and mechanical stress peaks at the finished repair site.

The step surface can z. B. have at least two stages. Preferably, the step surface on at least three stages.

Each step can consist of a ring-shaped, in particular annular, around the damage center and extending substantially parallel to the component surface recess surface, which via an annular closed and substantially orthogonal to the component surface extending edge surface with a higher or lower, again substantially parallel to the component surface extending recess surface is connected.

In one embodiment of the repair method, it is provided that a hard or cured part, for example of the same material as the component itself, is used as repair piece. Such a "finished" repair piece, in particular z. B. by gluing in the Schäftung be attached to the component.

The invention will be further described by means of embodiments with reference to the accompanying drawings. They show:

1 is a perspective view of a tool guide for milling a workpiece surface,

2 is a perspective top view of the workpiece to be machined,

3 is one of the 2 corresponding view after a locking of the tool guide of 1 on the surface of the workpiece from 2 , and

4 is one of the 1 corresponding view of a tool guide according to another embodiment.

1 shows one below as a tool guide 10 designated device for guiding a milling tool (not shown).

2 shows the workpiece to be machined in this example, namely a substantially curved in one direction aircraft fuselage shell 90 , The hull shell 90 indicates on its curved, here outer surface 92 a damaged place 94 which is to be eliminated by a per se known repair method in which the hull shell 90 first in the area of the damaged area 94 is repaired and then introduced repair material in the Schaftung and glued, for example, or anchored in any other way.

This repair is done using the in 1 illustrated tool guide 10 carried out.

3 shows the hull shell 90 after placing and securing the tool guide 10 on the surface 92 in the area of the damage site 94 ,

Coming back to 1 includes the tool guide 10 for guiding the milling tool for machining the fuselage shell 90 one on the surface 92 the hull shell 90 lockable frame 12 consisting of a rectangle, each elongated frame parts 12-1 . 12-2 . 12-3 and 12-4 , The frame is locked to the workpiece surface by suction feet 14 , one of each in the area of each corner of the overall rectangular frame 12 is arranged.

With the frame 12 connected and disposed within the same is a tool holder 16 for holding and positioning the milling tool (not shown) in a vertical direction z during machining of the workpiece surface.

In the figures, orthogonal to the vertical direction z and orthogonal to each other oriented lateral directions x and y are also drawn, which the extension directions of the frame parts 12-3 and 12-4 (x direction) or 12-1 and 12-2 (y direction).

The tool guide 10 further comprises a pair of linearly elongated guide rods in the x-direction 18-1 and 18-2 , on each of which one at the bottom of the tool holder 16 mounted glider 20 rode. Through this "x-guide" is the tool holder 16 in an area between the frame parts 12-1 and 12-2 relative to the frame 12 movable in x-direction.

The ends of the guide rods 18-1 and 18-2 run in pairs in oblong holes 22-1 and 22-2 on the inside of the frame part 12-1 respectively. 12-2 , Just before the ends of the guide rods 18-1 and 18-2 from these interspersed connecting struts 24-1 and 24-2 ensure a parallel course of the two guide rods 18-1 and 18-2 ,

The frame parts extending in the y-direction 12-1 and 12-2 form with their respective slotted holes 22-1 respectively. 22-2 a second guide rail arrangement for y-mobility of the guide rods 18-1 and 18-2 formed first guide rail assembly which the tool holder 16 stored movable in the x-direction.

Unlike in a conventional "xy-guide" is in the example shown, however, the peculiarity that extending in the y-direction slots 22-1 and 22-2 define a slightly curved guideway path for the y-motion.

Due to the functional series connection of the x-guide and the slightly curved y-guide results in a mobility of the tool holder 16 within the frame 12 bounded area along a corresponding curved surface. The shape of this intended for the tool holder movement surface is due to the surface shape of the workpiece to be machined, here the surface 92 the hull shell 90 , customized. For the purpose of milling out a shank in the area of the damaged area 94 For the most part, it is expedient for the surface accessible to the tool holder movement to be more or less exact like the shape of the workpiece surface 92 to provide in the area to be processed.

In the described application example of the approximately cylindrical shape of the surface 92 So there is the curved course of the slots 22-1 and 22-2 the corresponding surface course at the point of damage 94 in the y direction again.

The at the damage site 94 trainee Schäftung can be created for example by milling away gradually changed in diameter concentric circular areas or circular ring areas. The lateral drive of the tool holder together with the inserted milling tool required for sweeping the regions to be milled takes place manually in the illustrated embodiment by an operator, wherein the circular region or annular region to be milled out advantageously by a mechanical copying device of the tool guide 10 is defined.

The copying device used in the illustrated embodiment consists of a fixed to the tool holder 16 connected and in a lateral direction (here: x-direction) from the frame 12 out extending control rod, on which one of them in the z-direction downwardly projecting Abtastzapfen 28 is arranged, and one on a frame part (here: frame part 12-2 ) arranged template holder 30 for fixing a template 32 on the tool guide 10 ,

In the illustrated embodiment is as a template 32 a plate oriented in the xy plane with a recess defining the desired tool holder travel path or toolholder movement surface area, respectively.

At the in 1 illustrated template 32 is z. B. provided a circular recess. This allows the operator of the tool guide 10 in a simple manner, namely by scanning the recess edge or alternatively the entire recess surface with the scanning pin, in the ratio 1: 1, a corresponding movement path or movement area for the tool holder 16 comply.

After replacing the template 32 Accordingly, in another operation, a further concentric circular path or a further concentric circular surface area can be worked out by another template with a larger or smaller recess. Before each further Fräsgang can be used on the milling tool or the tool holder 16 a modified milling depth (in z-direction) can be set.

In summary, the described tool guide 10 a "geometry-adaptive hand-milling unit", by means of which an exact and reproducible machining on curved structures can be performed. The device is particularly suitable for processing fiber composite components (eg CFRP) or light metals, for example in aerospace engineering. Certain predefined areas on flat or curved structures can be machined or removed. In particular, for the application of the repair of the relevant component by means of milling processing both a certain cut away removed and a stepped Schaftung be formed. A drive unit including a milling tool of commercially available type can be attached to the tool holder 16 be mounted on which also the height delivery (z-direction) is realized. The frame parts 12-1 and 12-2 or their guide grooves or slots 22-1 and 22-2 are adapted to the shape (geometry), ie the curvature or the radius of curvature of the structure to be processed. For accurate and reproducible processing, a copy unit is integrated into the design. This gives the possibility of using predetermined mold plates or templates and the copy rod 26 to depart defined tracks. After placing the tool guide 10 on the area to be repaired their orientation can be simplified by positioning (position and Azimutwinkelstellung).

In the illustrated embodiment are z. B. in each case halfway the frame parts 12-1 and 12-4 such centering aids 34-1 respectively. 34-2 , The locking of the tool guide 10 on the fuselage shell segment to be repaired takes place in a simple manner on the suction feet 14 , which also optimally the curvature or the shape of the surface to be machined 92 to adjust. The device can with small dimensions and low weight as a mobile milling unit and thus z. B. be used directly at the place where a damage to be repaired occurs.

In the following description of a further embodiment, the same reference numerals are used for equivalent components, each supplemented by a small letter "a" to distinguish the embodiment. In this case, essentially only the differences from the exemplary embodiment already described are discussed and, moreover, explicit reference is made here to the description of the preceding exemplary embodiment.

4 shows a slightly modified tool guide 10a which in construction and function essentially the above with respect to 1 corresponds described tool guide.

A special feature of the tool guide 10a However, it is not just the frame parts 12a-1 and 12a-2 realized y-guide rail assembly has a curved track course, but also by a pair of guide rods 18a-1 and 18a-2 realized x-guide rail arrangement. This is accomplished in the illustrated embodiment, characterized in that the guide rods 18a-1 and 18a-2 Although parallel to each other, but each slightly curved in the x-direction.

Due to this curved bar run are also on the bottom of the tool holder 16a provided sliders for each of the two guide rods 18a-1 and 18a-2 executed twice. In 4 are the two gliders 20a-1 and 20a-2 for storage of the tool holder 16a on the guide rod 18a-2 to recognize.

In the 4 illustrated tool guide 10a is thus particularly suitable for adapted machining of a workpiece surface curved in two directions.

The described tool guides 10 ( 1 ) and 10a ( 4 ) can each be provided from a modular "kit" containing different pairs of frame members and guide rods, from which, if necessary, the currently required geometry (size of the frame and curvatures in the x and y directions) is created.

Claims (9)

Device for guiding a milling tool for machining a curved surface ( 92 ) of a workpiece ( 90 ), comprising one on the surface ( 92 ) of the workpiece lockable frame ( 12 ) and one in the frame ( 12 ) bounded area relative to the frame ( 12 ) movable tool holder ( 16 ) for the milling tool, wherein a first guide rail arrangement elongated in a first direction (x) ( 18-1 . 18-2 ) for the mobility of the tool holder ( 16 ) is provided in the first direction (x), wherein the frame ( 12 ) comprises a second guide rail arrangement elongated in a second direction (y) running transversely to the first direction (x) ( 12-1 . 12-2 ) to the mobility of the first guide rail arrangement ( 18-1 . 18-2 ) in the second direction (y), characterized in that the first guide rail arrangement ( 18-1 . 18-2 ) as such and / or the second guide rail arrangement ( 12-1 . 12-2 ) as such a to the curvature of the surface to be processed ( 92 ) has adapted curved guideway course. Apparatus according to claim 1, comprising a squeegee assembly ( 14 ) for locking the device to the surface ( 92 ) of the workpiece ( 90 ). Device according to one of the preceding claims, wherein the first guide rail arrangement ( 18-1 . 18-2 ) and / or the second guide rail arrangement ( 12-1 . 12-2 ) comprises a pair of mutually parallel guide rails. Device according to one of the preceding claims, wherein the frame ( 12 ) of four parallelogram, in particular rectangular, interconnected frame parts ( 12-1 . 12-2 . 12-3 . 12-4 ) is formed, of which two opposing frame parts ( 12-1 . 12-2 ) support or form the second guide rail assembly. Device according to one of the preceding claims, wherein the guideway course of the second guide rail arrangement ( 12-1 . 12-2 ) through slots ( 22-1 . 22-1 ) in opposite frame parts of the frame ( 12 ) is given. Device according to one of the preceding claims, wherein a with the tool holder ( 16 ) connected linkage ( 26 ) for controlling the movement of the tool holder ( 16 ) relative to the frame ( 12 ) is provided. Apparatus according to claim 6, wherein the linkage ( 26 ) a part of a mechanical copying device for defining a tool guideway based on a template ( 32 ). Use of a device according to one of claims 1 to 7, for shanking the workpiece ( 90 ). Use according to claim 8, wherein as a workpiece ( 90 ) a component to be repaired, in particular fiber composite component, is provided.

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