drilling tool

Abstract

Drill with a shaft (14) having a drill head (12), wherein at least one cutting edge (18) for machining a workpiece to form a drill hole is provided on the drill head (12), wherein the shaft (14) in the region of the drill head (12) further has an outer circumference (22), on which outer circumference an abrasive means (20) is provided for abrasively treating a drill hole wall produced by the cutting edge (18), characterized in that the abrasive means (20) is detachably fastened to the shaft (14).

Description

[0001] The present invention relates to a drilling tool. In particular, the present invention relates to a drilling tool that is equally suitable for machining a bore and for improving the quality of the borehole surface. State of the art

[0002] Holes are often created by machining into solid material or by reaming out an existing hole or a roughly cylindrical cavity. Various drilling tools can be used for this machining operation, such as twist drills, single- or double-fluted deep-hole drills, BTA or ejector drills, made of carbide or high-speed steel, for example. The geometrically defined tool cutting edge is either a direct part of the drilling tool body or it is firmly attached to the drilling tool body as a separate cutting element. For example, cutting inserts can be soldered in or they can be designed from replaceable elements, such as cutting plates, that are mechanically attached to the drilling tool.

[0003] During drilling, the bore diameter and the dimensional accuracy of the bore are essentially determined by the geometry of the drilling tool cutting edge. The surface quality of the bore wall, on the other hand, is determined by the outer cutting edges of the drilling tool and, if present on the drilling tool, by the guide pads.

[0004] A drilling tool for extracting a tooth root is known from document WO 2005 / 065566 A1. Such a drilling tool comprises a cylindrical shaft portion terminating in a head portion at its upper end. Furthermore, a drill bit provided with helical grooves and designed as a self-tapping drilling tool is connected to the shaft portion. A cylindrical pin attachment is integrally connected to the lower end of the drill bit. The pin attachment is coated with an abrasive surface.

[0005] US Pat. No. 5,000,630 describes a drill bit having a triangular end for forming a drill hole and a frustoconical abrasive surface for enlarging the drill hole. Such a drill bit thus comprises a drilling area and a grinding area.

[0006] Document DE 29 03 162 describes a honing tool comprising a honing stone, wherein the honing stone is mounted on the outer surface of at least one thin-walled expansion sleeve. A channel containing a hydraulic medium is provided in a base body for radial adjustment of the honing stone, with the hydraulic medium acting on the expansion sleeve. Disclosure of the invention

[0007] The subject of the present invention is a drill with a shank having a drill head, wherein at least one cutting edge is provided on the drill head for machining a workpiece to form a borehole, wherein the shank further has an outer circumference in the region of the drill head, on which outer circumference an abrasive means is provided for abrasively treating a borehole wall produced by the cutting tool, wherein the abrasive means is detachably fastened to the shank.

[0008] The drill described above makes it possible, in a particularly effective manner, to combine the two separate machining processes of drilling and thus creating a borehole and fine machining of the borehole or the created borehole wall in a single machining step by integrating one or more abrasive agents into a drilling tool.

[0009] The drill described above initially has a shaft. The shaft, which can be made from a metal in a manner known per se, comprises a drill head in a manner known per se, which represents the end region of the drill or shaft. At least one cutting edge is provided on the drill head for machining a workpiece to form a drill hole. The cutting edge can be a component of the shaft or attached to it. Only one cutting edge can be provided, or a plurality of cutting edges can be provided. The exact design or number of cutting edges depends, in a manner known per se, on the intended use of the drill and, in particular, on the size of the drill hole to be drilled or on the material of the workpiece to be machined.Thus, the cutting edge(s) serve as one or a plurality of geometrically defined cutting edges for performing a drilling process. While the invention is described below with reference to the provision of one cutting edge, it will be understood by those skilled in the art that the invention is equally disclosed for the presence of a plurality of cutting edges.

[0010] The drill can therefore be based on a known drilling tool or drill bit. This could be, for example, a twist drill, single-lip deep-hole drill, double-lip deep-hole drill, BTA drill, ejector drill, or similar.

[0011] In addition to the cutting edge described above for machining the workpiece, a drill of the type described above is provided with the shaft in the area of the drill head or on the drill head further comprising an outer circumference, on which outer circumference an abrasive means is provided for abrasively treating the workpiece or, in particular, the borehole wall created by the cutting edge. The abrasive means can be referred to as a geometrically undefined cutting edge and can be configured, for example, like a grinding or honing coating. The outer circumference can be interrupted, in particular, by the space between the cutting edges and therefore does not need to be circular.

[0012] With regard to positioning, the abrasive can, for example, be provided adjacent to a guide bar. A guide bar can have the advantage of ensuring that the drill is always correctly aligned in the drill hole, which is particularly advantageous for long drill holes.

[0013] Furthermore, a drill head can be understood in particular as a part of the drill which treats the material to be machined, i.e. in particular by the cutting edge and the abrasive agent.

[0014] In addition, the abrasive can be attached to the shaft, for example, mechanically or materially, or by means of galvanic deposition.

[0015] Such a combination of cutting edge on the one hand and abrasive agent on the other hand makes it possible to create a combination drilling tool that machines the workpiece to be machined in two different ways. The drill described above thus allows, in addition to machining the workpiece, abrasive machining of the workpiece or, in particular, the borehole wall created by the cutting edge. This makes it possible to significantly shorten the process chain comprising drilling and fine machining, since a drill according to the invention can create holes of final quality in a material in a single step or in a single-stage work process. A separate post-treatment of the borehole or the borehole wall carried out in a step following drilling can thus be omitted.This allows simultaneous drilling and surface finishing of the borehole wall created by drilling.

[0016] Furthermore, the drill described above can enable particularly good dimensional and shape accuracy compared to the methods known from the prior art. In particular, this enables particularly good component precision and improved component quality, along with reduced production times and costs. In particular, the machining quality of the drilled hole, such as a high surface quality of the drilled hole wall, can be achieved. By simply adjusting the abrasive, treating the surface hole with this abrasive can achieve not only smoothing but also tribologically optimized properties of the drilled hole surface.

[0017] Examples of applications include all products in which one or more holes must be machined with high machining quality. Non-limiting examples include retaining bodies, nozzle bodies (e.g., for injection systems), hydraulic components, and wind power components. The material to be machined can, in particular, be a metallic material, but is not limited to this.

[0018] It can be advantageous if the abrasive is located radially the same or preferably further out than the cutting edge, as this can prevent a negative influence on the reworked borehole surface when the drill is pulled out after drilling.

[0019] In summary, the drill described above provides a cost-effective way to produce high-quality products with particularly advantageous process technology.

[0020] Within the scope of one embodiment, the drill can have at least one guide bar, wherein the abrasive agent is arranged on the active surface of the guide bar, or the abrasive agent can be designed as a guide bar or form a guide bar. In particular, the provision of a guide bar can enable improved alignment of the drill in the borehole, especially in particularly deep boreholes. Furthermore, in this embodiment, it can be made particularly simple and with high synergistic effects possible for the abrasive agent to be arranged with respect to the cutting edge in such a way that a negative influence on the borehole wall produced is prevented when the drill is pulled out by the cutting edge.

[0021] Furthermore, by arranging the abrasive on the active surface of the guide bar, i.e., the surface of the guide bar that comes into contact with the borehole wall, the drill can be manufactured particularly easily and cost-effectively. This is because the drill itself, in particular comprising the shaft and the drill head, can essentially be manufactured as known from the prior art. Only the guide bar(s) can be adapted by providing an abrasive on their surface. The abrasive can be present, for example, as a coating or layer on the active surface of the guide bar.

[0022] In an alternative embodiment, it can be provided that the abrasive means itself is designed as a guide bar. In this embodiment, the guide bar can thus be replaced by the abrasive means. This embodiment can also be particularly cost-effective, since conventional guide bars can be dispensed with and appropriately shaped abrasives can be used instead. In this embodiment, the abrasive means can in particular have a compact design, for example by arranging an abrasive material in a matrix and shaping this arrangement into a guide bar. In this embodiment, in addition to cost-effective production, particularly good durability can be achieved, since high wear is possible due to the adjustable thickness of the abrasive means.

[0023] The abrasive is detachably attached to the shaft. This design allows for a solution that is particularly adaptable to the desired application. The abrasive can be selected depending on the desired fine machining or the material to be machined and can be attached to the shaft before a corresponding process. This allows for optimal fine machining depending on the desired application. Furthermore, a drill bit in this design can be particularly durable because, especially when the abrasive is already worn but the cutting edge can still be used for a further machining step, the abrasive can be replaced and the drill bit can thus be reused.Furthermore, if, for example, the cutting edge is worn or damaged but the abrasive is still suitable for abrasive treatment of the material to be machined, the abrasive can be removed and attached to a different shaft. Thus, a drill as described above, particularly in this design, allows for particularly economical work. A detachable attachment of the abrasive to the shaft can mean that the abrasive itself is detachably attached, or that the component carrying the abrasive, such as a guide rail, is detachably attached, thus indirectly detachably attaching the abrasive.

[0024] Within the scope of a further embodiment, the position of the abrasive means can be adjustable in the radial direction. In the context of the present invention, this can mean, in particular, that the radial position is adjustable when not in a borehole, or that the pressure exerted on the borehole wall is adjustable when in a borehole. A radially adjustable position of the abrasive means can mean that the abrasive means itself is radially adjustable, or that the component carrying the abrasive means, such as a guide rail, or its position, is radially adjustable, so that the abrasive means or its position is thus indirectly radially adjustable.

[0025] This configuration, in particular, allows for particularly advantageous drilling and post-treatment of the resulting borehole surface. Specifically, a defined, adjustable abrasive performance of the abrasive agent(s) can be achieved to specifically influence the borehole geometry. For example, conical boreholes, concave or convex boreholes, and boreholes with defined shoulders or pockets can be easily realized.

[0026] Furthermore, by precisely adjusting and varying the contact pressure of the abrasive against the surface, the surface quality, surface structure, and edge zone properties can be specifically influenced. For example, locally varying roughness and textures as well as targeted compressive residual stresses can be achieved.

[0027] A further advantage is that it is possible to specifically influence the process stability by varying the contact pressure of the abrasive and thus changing the friction conditions depending on the drilling progress or the current dynamic process situation, such as process disturbances or chatter vibrations.

[0028] In particular, adaptive radial adjustability of the abrasive can be achieved by piezo actuators, hydraulic adjustment, mechanical adjustment, or electromagnetic adjustment, which act on the abrasive or a component carrying the abrasive. The adjustment system can be integrated into the drill head below the abrasive, which can be configured in particular as a guide rail, or below the component carrying the abrasive. Furthermore, a corresponding supply line or connection for the means for radial adjustability can run inside the drill and, for example, can be connected to or attached to a corresponding external actuating means, such as a power source or a source of hydraulic fluid, when the drill is clamped.

[0029] With regard to piezo actuators, these can advantageously be integrated in a radially acting arrangement, particularly within the drill head. Depending on the bore diameter, the stroke of the actuator, approximately in the nanometer to micrometer range, is adjusted by the actuator length. Due to the very short adjustment times and the very high adjustment accuracy, the abrasive can be varied highly dynamically and very precisely using the piezo actuator and adjusted during the machining process. This type of adaptive adjustment is particularly suitable for specifically influencing process-dynamic effects that occur during drilling. The abrasive can be attached to a membrane or located as a radially movable element in a recess on the tool head.

[0030] With regard to hydraulic adjustment, the abrasive can be pressed radially outwards against the borehole wall by the pressure of a medium. In this case, an axial bore for guiding a lubricant can be provided, in particular wherein the axial bore is connected by a transverse bore to the abrasive or to a component connected to the abrasive or to a component carrying the abrasive, such as a guide rail. Likewise, a plurality of transverse bores can be provided, wherein the number of transverse bores can correspond to the number of abrasives, such that one or more transverse bores can run to each abrasive. Thus, the medium or hydraulic fluid can be supplied through transverse bores that are connected to the internal coolant lubricant bore of the drill or shaft.Furthermore, independent of the provision of the above-described axial bore, separate media bores can be provided, which can be arranged approximately parallel to the internal coolant bore. The pressure of the medium can be specifically adjusted and varied during the machining process. The abrasive can be attached to a membrane or located as a radially movable element in a recess on the tool head.

[0031] In the case of mechanical adjustment, the movement of the abrasive can be achieved, for example, by a defined conical expanding pin inside the drill, which presses against the bevelled undersides of the abrasive through an axial movement to the drill axis and thus adjusts them radially.

[0032] The radial adjustment can be specifically set and varied during the machining process.

[0033] Electromagnetic adjustment can also be achieved using the electromagnetic principle of mutually repelling poles. The electromagnetic actuators can be integrated into the drill head. The radial adjustment can be precisely adjusted and varied during the machining process. The abrasive can, in turn, be located as a radially movable element in a recess in the drill head.

[0034] In a further embodiment, the shaft can have a groove for, in particular, releasably receiving the abrasive or a component provided with the abrasive, such as a guide rail. This embodiment can be particularly advantageous for attaching the abrasive directly or indirectly, for example, releasably, to the shaft, since the abrasive can be easily inserted into the groove. The groove can be delimited in particular in such a way that the abrasive cannot slide out during a drilling process.

[0035] It may be particularly preferred if the groove has a cross-section that tapers outward. This configuration, in particular, can provide advantageous radial adjustability, since the outwardly tapered cross-section can prevent radial removal from the groove.

[0036] Within the scope of a further embodiment, the abrasive can comprise a solid, for example as solid particles, which are selected from the group consisting of diamond, boron nitride, in particular cubic crystalline boron nitride (BCN), corundum and silicon carbide. The solid or the solid particles can serve in particular as an abrasive or honing material and can be arranged, for example, in a matrix, such as comprising a metal and / or a ceramic and / or a plastic, such as a synthetic resin. Furthermore, the solid particles can be arranged, for example, in an electroplated layer, such as a metal layer. An example of solid particles that are not arranged in a matrix can be a particularly polycrystalline diamond layer, whereby the solids present without the matrix are not limited to this material.Such a diamond layer can be produced, for example, by a coating process such as a CVD coating process. Examples and drawings

[0037] Further advantages and advantageous embodiments of the inventive objects are illustrated by the drawings and explained in the following description. It should be noted that the drawings are for descriptive purposes only and are not intended to limit the invention in any way. Fig. 1 is a schematic view of an embodiment of a drill according to the invention; Fig. 2 a schematic side view of a drill head of the drill from Fig. 1; Fig. 3 a schematic sectional view through an embodiment of a drill head; Fig. 4 a schematic sectional view through a further embodiment of a drill head; Fig. 5 a schematic sectional view through a further embodiment of a drill head; and Fig. 6 a schematic view of a design of a drill head.

[0038] In the Fig. 1 shows a drill 10 according to an embodiment of the present invention. It will be understood by those skilled in the art that this drill 10 is shown partially sectioned for clarity, but represents a single, integral component.

[0039] The drill 10 comprises a shaft 14 having a drill head 12 for machining a workpiece and a connection area 16 for connecting the drill 10 to a drive unit. At least one cutting edge 18 is provided on the drill head 12 for machining the workpiece to form a drilled hole. Furthermore, the shaft 14 further has an outer circumference 22 in the region of the drill head 12, on which outer circumference 22 an abrasive 20 is provided for abrasively treating a drilled hole wall created by the cutting edge 18.

[0040] This in detail in the Fig. 3 to 5, which are a sectional view along the line AA of the representation of the drill head 12 according to Fig. 2 show.

[0041] In the Fig. 3 shows that the abrasive 20, which is arranged on the outer circumference 22 of the shaft 14, forms a guide strip. The position of the abrasive 20 can be adjusted in the radial direction. For this purpose, as shown in Fig. 4, a hydraulic adjustability can be provided. In particular, an axial bore 24 can be provided for guiding a cooling lubricant, wherein the axial bore 24 is connected to the abrasive means(s) 20 by transverse bores 26. Radial adjustability of the abrasive means 20 can be achieved by the pressure of the cooling lubricant.

[0042] Alternatively, as described in the Fig. 5, in addition to the axial bore 24 and independently of the provision of these, one or more further separate axial bores 28 can be provided, which are connected by transverse bores 30 to the abrasive means 20 or to the abrasive means 20 in order to be able to adjust their position radially.

[0043] In the Fig. 6 it is further shown that the shaft 14 or the drill head 12 has a groove 32, in the embodiment according to Fig. 6 has two grooves 32, in particular for releasably receiving the abrasive 20, whereby a releasable attachment of the abrasive 20 to the shaft 14 can be realized. For example, the groove 32 can have a cross-section that decreases towards the outside. An adjustment mechanism for radially adjusting the position of the abrasive can be provided inside the groove 32.

Claims

[1] Drill with a shank (14) having a drill head (12), wherein at least one cutting edge (18) is provided on the drill head (12) for machining a workpiece to form a borehole, wherein the shank (14) in the region of the drill head (12) further has an outer circumference (22), on which outer circumference an abrasive means (20) is provided for abrasively treating a borehole wall produced by the cutting edge (18), characterized by that the abrasive means (20) is detachably attached to the shaft (14). [2] Drill according to claim 1, characterized by that the drill (10) has at least one guide bar, wherein the abrasive means (20) is arranged on the active surface of the guide bar. [3] Drill according to claim 1, characterized by that the abrasive (20) forms a guide bar. [4] Drill according to one of claims 1 to 3, characterized bythat the position of the abrasive (20) is adjustable in the radial direction. [5] Drill according to claim 4, characterized by that radial adjustability can be realized by at least one of a piezo actuator, a hydraulic adjustment, a mechanical adjustment and an electromagnetic adjustment. [6] Drill according to claim 5, characterized by that an axial bore (24, 28) is provided, . [7] Drill according to one of claims 2 to 6, characterized by that the shaft (14) has a groove (32) for receiving the abrasive (20) or a component provided with the abrasive (20). [8] Drill according to claim 7, characterized by that the groove (32) has a cross-section that decreases towards the outside. [9] Drill according to one of claims 1 to 8, characterized bythat the abrasive (20) comprises a solid selected from the group consisting of diamond, boron nitride, corundum and silicon carbide.

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