A large number of tools are known having a shank with a working portion which is shaped in a variable manner as required. These tools are for example drills, in particular rock drills, chisels or the like. The configuration as a drill is the main example of this, without thereby entailing any limitation. In the case of a drill, the working portion is equipped with a drill head and an adjoining helix for transporting drillings.

In the tool in question, the working portion is adjoined by an insertion portion of the shank that is shaped in accordance with fixed requirements in order for example to be detachably secured in a tool holder. An example of the formation of an insertion portion of a tool according to the invention is the SDS-Plus mount for hammer drills, which has for years been a widespread standard for medium- weight hammer drills. It is known to manufacture SDS-Plus insertion portions of drills, for example, from a materially uniformly one-part blank. In this case, the blank is brought firstly by extrusion, turning, milling and/or grinding onto the outer diameter of the SDS insertion portion and subsequently equipped by means of further milling and/or grinding steps with corresponding coupling formations for force and torque transmission.

The problem underlying the invention consists in specifying a manufacturing method for an elongate tool, by means of which the tool can be manufactured in a particularly cost-effective manner.

According to the invention, for a manufacturing method mentioned at the outset, the foregoing problem is solved by the characterizing features of Claim 1. The reshaping of the elongate blank by extrusion in the region of the insertion portion while enlarging the outer diameter of the blank will be referred to hereinafter as the "widening reshaping step". The indication "axial" refers in this regard in all cases to the tool axis of the elongate tool. The reshaping step as proposed is suitable for manufacturing large quantities at low costs. In addition, it is possible to save material which is relatively expensive in the case of tools on account of the high steel quality.

In the simplest case, the blank has before the widening reshaping step a single outer diameter which is smaller than the subsequent outer diameter of the insertion portion. It is however also conceivable for the blank to have differing outer diameters, in particular in the region of the subsequent working portion and in the region of the subsequent insertion portion. The respective outer diameter configuration of the blank is preferably produced by extrusion.

The material saving of a manufacturing method according to the invention can have one or more aspects. On the one hand, shank material per se can be saved in that a larger outer diameter is achieved by the widening of the insertion portion, a hollow space often remaining at the same time in the central region of the insertion portion as a result of the extrusion. Depending on the configuration of the tool, an even greater material saving effect can occur when, for example, the largest outer diameter of the blank that is necessary for manufacturing the working portion is smaller than the largest outer diameter which is conventionally necessary for manufacturing the insertion portion.

For example, an SDS insertion portion is conventionally manufactured from a blank, the largest outer diameter of which corresponds at least to the subsequent outer diameter of the SDS insertion portion. After all, the outer diameter of the blank is not widened in this case. Depending on the drill variant, a considerable reduction in the outer diameter of the working portion, for example by cutting or non-cutting machining, may be required in the working portion. As a result of the widening according to the invention of the insertion portion by extrusion, it is now possible to use a blank, the largest outer diameter of which is smaller than the subsequent outer diameter of the SDS insertion portion. The reduction of the outer diameter in the working portion that is necessary in conventional manufacturing methods is dispensed with at least partly. This results in a considerable saving of material.

In a preferred embodiment of the invention, the coupling formation is formed at least partly, in particular completely, in the course of the widening reshaping step. As a result, additional machining steps, such as for example milling or grinding of the depression, either become superfluous or are reduced in their extent, as a result of which manufacturing time and wear are saved in machining tools. Numerous configurations are conceivable for the configuration of the coupling formation. Preferably, the coupling formation is configured as a depression, a plurality of depressions of this type more preferably being provided. In the case of the specific example of the insertion portion being formed as an SDS-Plus receptacle, the term "depressions" is understood in the present sense as referring to both continuous, wedge-shaped grooves for transmitting torque and non- continuous, partly circular grooves for axially mounting and securing the tool in the receptacle.

It is however also conceivable for the at least one coupling formation to be embodied in such a way that the insertion portion is embodied in a star- shaped manner in cross section, at least at an axial point. Other types of coupling formations are possible. The coupling formations described hereinafter will primarily be formations which are advantageously embodied as depressions, without thereby entailing any limitation.

In a preferred detail-form configuration of a method according to the invention, provision is made for the widening reshaping step to include driving a press mandrel axially into the blank, the press mandrel having a smaller outer diameter than the blank. The indication "axial" refers in this regard in all cases to the longitudinal axis of the elongate tool.

A foregoing flow reshaping process is sometimes referred to also as can extrusion. The reshaping by means of extrusion can use any known extrusion process, in particular cold extrusion or else semi-hot extrusion.

In a preferred development, the press mandrel is in this case driven axially starting from an end-side front face of the blank, the blank being formed in particular in one part. The one-part embodiment of the blank is not necessary in this regard. Nevertheless, it is at least possible if the press mandrel is driven into the insertion portion only from one end side of the tool.

Advantageously, the blank is inserted during the widening reshaping step into a receptacle with shaping jaws forming a negative shape in relation to the coupling formation, in particular the depression. This allows the above- addressed embodiment of the coupling formation in the course of the widening reshaping step, in particular in the course of the driving of the press mandrel, to be easily achieved.

In a generally preferred embodiment of the invention, even before the widening reshaping step, the blank is fixed in a pressing manner into a receptacle, at least a part of the coupling formation, in particular the depression, being formed in the blank by the pressing fixing in the receptacle. This may be advantageous when the depressions protrude particularly deeply into the outer circumferential face of the insertion portion, so that one part is introduced by the receiving step and a further part by the widening reshaping step. Depending on requirements, it is in this case possible for at least a part of the coupling formation to be formed by closing shaping jaws brought laterally up to the insertion portion, projections in the shaping jaws pressing into the insertion portion.

However, alternatively or additionally, shaping jaws of this type can also be closed to begin with, the blank subsequently being axially introduced into the shaping jaws in a pressing manner. The pressing introduction can be carried out while forming grooves at the points where the corresponding projections collide with an overhang of the blank to form the depressions. In the subsequent, widening reshaping step by means of extrusion, some or all of the grooves produced in this way can then be closed again in the region of the end of the insertion portion as a result of the widening of the diameter. The non-continuous, partly circular grooves of an SDS insertion portion can for example be shaped in this way.

In a further preferred development, provision is made for an opening produced by the press mandrel to be at least partly closed, in particular by means of reshaping. Alternatively or additionally, the opening produced by the press mandrel can also be closed by means of inserting a closure part into the opening. The closure part preferably has two opposing recesses which are adjoined by the two continuous grooves of the SDS insertion portion. Advantageously, a combination of inserting a closure part and reshaping can also be provided. As a result of the closure of the opening produced by the press mandrel, the end- side front face of the insertion portion is embodied as a closed, solid face; this is advantageous in particular when the insertion portion is embodied as an SDS receptacle for tools. In SDS tools, a striking bolt of the machine receiving the tool often acts on the end- side front face of the insertion portion. Depending on the specific configuration and design of the press mandrel and insertion portion, it may also be sufficient to leave the opening produced by the press mandrel. In an alternative or additional embodiment, provision is made for the press mandrel to be driven starting from a parting plane between the working portion and the insertion portion, the tool being composed in a preferred detail-form configuration as an at least two-part unit made up of the working portion and insertion portion. The parting plane is preferably oriented perpendicularly to the longitudinal axis of the tool. It is however also conceivable for the parting plane to be oriented at an inclination to the longitudinal axis.

The arrangement of the parting plane "between the working portion and the insertion portion" refers very generally to the fact that substantially the working portion is positioned on one side of the parting plane and substantially the insertion portion is positioned on the other side of the parting plane. That includes a configuration in which the insertion portion extends slightly beyond the parting plane. This understanding is appropriate, as a clear spatial distinction between the insertion portion and working portion is often not possible anyway.

If the press mandrel is driven into the insertion portion from the parting plane, it is in particular possible to avoid an opening in the opposite, end-side front face of the insertion portion. However, depending on requirements, provision may also be made for the press mandrel to be driven into the insertion portion both starting from the parting plane and starting from the end-side front face, for example in order to achieve particularly major reshaping.

As the working portion to a certain extent borders the insertion portion in the region of the parting plane, the tool is generally composed in the region of the parting plane, in an at least two-part manner, of the working portion and insertion portion.

The foregoing composing can take place by compressing and/or soldering and/or welding or by means of another known connecting process. It is also conceivable for one part to be shrunk onto the respective other part.

In a two or multiple-part embodiment of the blank, provision may be particularly advantageously be made to form the various parts from different materials in order either to save costs or to further optimize the function of the tool as a whole. Alternatively or additionally, in the case of a multiple-part embodiment, provision may be made for the blanks for the various parts to have different diameters in order to optimize material consumption. It is also conceivable for the various parts to be subjected to different heat treatments, in particular hardening processes.

In a particularly preferred detail-form configuration of the invention, the press mandrel has a non-cylindrical cross section. In particular, this can prevent a collision of the press mandrel with the coupling formation or other structures of the insertion portion. Overall, the non-cylindrical shaping of the pressing mandrel can be adapted to the shaping of the insertion portion in such a way that optimum extrusion is achieved, account being taken of desirable optimizations such as the service life of the press mandrel, material temperatures achieved during the reshaping and the like.

According to a further teaching of independent importance, a tool is claimed that was manufactured by a method according to one of Claims 1 to 11.

In a preferred embodiment, the tool has, at least over a part of the length of the insertion portion and/or the working portion, a hollow space formed in the course of the widening reshaping step. This hollow space corresponds substantially to the amount of material saved compared to a conventionally manufactured tool.

In a generally advantageous manner, the manufactured tool is a drill, in particular a rock drill, a chisel or the like.

In a particularly preferred embodiment, the insertion portion is embodied as a quick-action clamping receptacle for a drill chuck, preferably but not necessarily of the type of a drill chuck from the group comprising SPIT-R3®, SDS-Plus®, SDS-top® or SDS-Max®. The coupling formations therein are embodied as depressions in the foregoing sense. However, the embodiment of coupling formations in such a way that the insertion portion is embodied in a star-shaped manner in cross section, at least at an axial point, is also conceivable. Tools for the foregoing quick-action receptacles are manufactured in large quantities, so that the method according to the invention is particularly advantageous for receptacles of this type. Further advantages and features of the invention will become apparent from the exemplary embodiments described hereinafter and also from the dependent claims.

A plurality of exemplary embodiments of the invention will be described hereinafter and commented on in greater detail with reference to the enclosed drawings, in which:

Fig. 1 is a spatial view of a blank of a first exemplary embodiment of the invention;

Fig. 2 shows the blank from Fig. 1 after a machining step;

Fig. 3 shows the blank from Fig. 1 after a further machining step; Fig. 4 is a sectional view through the blank from Fig. 3 ;

Fig. 5 is a spatial view of a finished tool according to a second exemplary embodiment of the invention; Fig. 6 is a first spatial view of an insertion portion of the tool from Fig. 5;

Fig. 7 is another spatial view of the insertion portion from Fig. 6;

Fig. 8 is a spatial view of a working portion of the tool from Fig. 5;

Fig. 9 shows a modification of the tool from Fig. 2; and

Fig. 10 is a schematic illustration of an extrusion process as proposed carried out on a blank.

The elongate blank shown in Fig. 1 has a cylindrical cross section, a first portion, corresponding to a subsequently shaped insertion portion 1 of the tool, having in the present case a somewhat larger diameter than a second portion corresponding to a subsequently shaped working portion 2 of the tool. The blank is shaped in a materially uniformly one-part manner and can be manufactured, for example by a reshaping method, in particular extrusion, from a wire, a rod material or another suitable semifinished product form. The blank consists in the present case of a tool steel suitable for the manufacture of drills, in particular a chromium- nickel steel. A diameter Dl of the cylindrical insertion portion 1 of the blank is about 8 mm and the diameter DA of the working portion of the blank is in the present example about 6 mm. Depending on requirements, the diameters of the working portion 2 and insertion portion 1 may also be equal or the diameter of the working portion 2 may be larger than that of the insertion portion 1.

In a first step for machining the blank, referred to hereinafter as the "widening reshaping step", the blank is reshaped by extrusion in the region of the insertion portion 1, its outer diameter being enlarged. Fig. 2 shows the result of this step of reshaping by means of extrusion. The outer diameter D2 of the reshaped and widened insertion portion 1 is now about 10 mm, an outer circumferential face of the insertion portion 1 being cylindrical in the present case. In the course of the widening of the insertion portion 1 of the blank, coupling formations 3, 4 are preferably introduced at the same time into the insertion portion 1. In this case and preferably, the coupling formations 3, 4 are embodied as depressions 3, 4. The coupling formations described hereinafter will primarily be depressions 3, 4, without thereby entailing any limitation. All the following statements concerning depressions 3, 4 apply accordingly to any embodiments of coupling formations 3, 4.

The illustrated depressions 3, 4 are grooves which are typical of SDS tools, a first pair of opposing grooves 3 being provided that are each equipped with a rounded or partly circular floor for receiving a holding ball. The depressions 3, 4 also comprise a second pair of opposing grooves 4 which are each shaped as wedge grooves 4 or grooves having a wedge-shaped cross section. In the case of SDS tools, the wedge grooves 4 serve primarily to transmit a torque to the rotating tool, the closed grooves 3 providing axial mounting and at the same time axial movability over a defined stroke. In this way, the tool can be at once axially held and also axially driven by means of a striking device.

As may be seen from Fig. 2 and Fig. 10, within the widening reshaping step for extruding the insertion portion 1 , a press mandrel 5 (see the schematic illustration in Fig. 10, which differs in terms of the shaping of the tool) is driven into the insertion portion 1, starting from the end-side front side la, in the axial direction. The material displaced in this way escapes, in accordance with the principles of reshaping by means of extrusion, to the side and in other directions. Corresponding projections for producing the depressions or grooves 3, 4 are provided at the sides of shaping jaws 6 holding the tool (see Fig. 10). Not only does this allow the outer diameter of the insertion portion 1 to be widened, the depressions or grooves 3, 4 are also shaped at least partly by the extrusion step.

In the present example, the press mandrel 5 has a substantially cylindrical cross section with a diameter of about 4 mm. The grooves 3, 4 forming depressions have a depth of 1.75 and 2.2 mm respectively under the cylindrical outer circumferential face of the insertion portion, which is about 10 mm in diameter, of an SDS receptacle.

In a particularly preferred configuration, the blank is inserted during the widening reshaping step into a receptacle 6 which is equipped in this case with shaping jaws 6. The shaping jaws 6 have a negative shape in relation to the depression 3, 4, allowing the at least partial formation of the depression 3, 4 in the course of the widening reshaping step. In this case, the shaping jaws 6 can be stationary during the extrusion or be closed onto the blank during the extrusion.

It is however also conceivable for, as discussed above, the blank to be fixed, even before the widening reshaping step, in a pressing manner in the receptacle 6, in particular by means of shaping jaws 6, at least a part of the depression 3, 4 being formed by the pressing fixing in the receptacle 6.

Alternatively thereto, the shaping jaws 6 can initially be closed before the widening reshaping step, after which the blank is pressed axially into the shaping jaws 6 while forming relatively shallow grooves. As may be seen from Fig. 2, the grooves 3, 4 can be closed towards the end side of the insertion portion 1 in the course of the widening reshaping step, the grooves being reopened in a subsequent machining step, at least with regard to the wedge grooves 4.

As previously stated, the blank has in this case and preferably a cylindrical cross section. In another embodiment (not shown), the blank can have a non-cylindrical cross section. In a suitable design, this can optimize the flowing of the shank material in the course of the widening reshaping step.

The hollow space 7, which according to Fig. 2 is produced in the centre of the insertion portion 1 by the press mandrel 5, can be closed in a subsequent reshaping step, which is referred to in the present document as the "closing reshaping step", in order to provide a solid, closed end-side front face la of the tool.

The hollow space 7 or the opening 7 can be closed by a reshaping step in the end region of the insertion portion 1. Preferably, this is provided by means of the driving of a further press mandrel (not shown in this figure) axially onto the edge region of the opening 7, the diameter of the further press mandrel corresponding at least to the outer diameter of the blank at the opening 7. Alternatively, an end-side closure part (not shown), in particular with the recesses referred to for the outlets of the wedge grooves 4 of the SDS insertion portion 1, can also be used for closing the hollow space or the opening 7. In addition, it is possible to combine inserting a closure part and reshaping. In the exemplary embodiment described hereinbefore, a reshaping of the working portion 2 of the tool was not described or illustrated in the drawings. The working portion 2 can be shaped in a manner known per se either before the reshaping steps described hereinbefore for producing the desired insertion portion 1 or after these steps.

In the case of the tool configured as a drill, in particular a rock drill, the working portion 2 comprises for example a slot- like receptacle for a hard metal drill head or the like and an adjoining helix. The working portion 2 is configured in a correspondingly different manner in the case of a tool configured as a chisel or the like.

In the exemplary embodiment described hereinbefore, the working portion 2 and insertion portion 1 are embodied in a materially uniformly one-part manner. This means that the working portion 2 and insertion portion 1 are not attached to each other in the region of their transition.

Fig. 5 is a spatial view of a second exemplary embodiment of the invention. In this example, the insertion portion 1 and the working portion 2 are not embodied in a materially uniformly one-part manner, but composed of at least two parts.

As Fig. 6 shows, the insertion portion 1 is in this case shaped separately, the press mandrel 5, which is associated with the widening reshaping step, being axially driven not from the end-side front side of the insertion portion 1, but from the side of a parting plane T between the working portion 2 and insertion portion 1. As may be seen from Fig. 6, a corresponding opening of the hollow space 7 produced by the press mandrel 5 remains in the direction of the parting plane T or in the direction of the working portion 2 and not in the direction of the end-side front face la. As a result, a step for closing or reshaping the end-side front face la of the insertion portion 1 is dispensed with.

For connecting the working portion 2 and insertion portion 1, these portions have corresponding formations which are embodied in the present case as a projecting lug 8 on the insertion portion 1 and a corresponding opening 9 on the working portion 2. The lug 8 and opening 9 have a non-cylindrical cross section, preferably a rectangular cross section. In the exemplary embodiment which is illustrated and to this extent preferred, the cross section is a substantially square cross section with cushion- shaped roundings.

The lug 8 on the insertion portion 1 can also be shaped by means of extrusion, in particular in the same operation in which the grooves 3, 4 are formed and also the outer circumference of the insertion portion 1 is widened. However, alternatively, a separate reshaping step can also be carried out for forming the lug 8, in particular by means of a pressing process.

The working portion 2 shown in Fig. 8 has a thickening 10 in which is formed the opening 9 which corresponds in its cross-sectional shape to the lug 8 and into which the lug 8 is introduced in an assembly step. The working portion 2 and insertion portion 1 can be brought together as compression, in particular in conjunction with shrinking-on. Alternatively or additionally, solderings or weldings can also be provided.

The thickening 10 of the working portion 2 according to Fig. 8 results at least partly from an enlargement of the diameter in this region into the working portion

2 in the course of an extrusion of the opening 9. This allows the removal of material from the blank to be dispensed with at least partly, depending on the individual case also completely, in particular for the manufacture of drills having a smaller drill diameter than the fixed shank diameter (about 10 mm in the case of an SDS-plus system).

For example, the drill shown in Fig. 5 may be a 6 mm stone drill. The working portion 2 can in this case be manufactured from a 6 mm blank, for example, the 6 mm blank firstly being upset to 8 mm in the region of the thickening 10 and subsequently being enlarged still further in diameter by forming the opening 9 by means of extrusion. The insertion portion 1 may be in the form of a 8 mm blank which is widened to a diameter of about 10 mm by extrusion. Overall, this allows considerable amounts of material to be saved in the manufacture of the drill. In particular in the case of the example according to Fig. 5 to Fig. 8, the insertion portion 1 and working portion 2 can also be made of differing material.

Fig. 9 shows a modification of the exemplary embodiment according to Fig. 2. In Fig. 9 the drill or the tool also consists of a working portion 2 and an insertion portion 1. In addition, an intermediate portion 11 is also located between the insertion portion 1 and working portion 2 on the drill. The intermediate portion is shaped in its form as a hexagon which can serve to receive a tool marking, for example a coloured ring, a clip, a slotted bush or the like.

The intermediate portion 11 is shaped in a materially uniformly one-part manner with the insertion portion 1 and/or working portion 2, or else as a separate, attached component. Moreover, corresponding formations of the opening and lug as in the case of the insertion portion 1 and working portion 2 would be provided as shown in Fig. 6 and Fig. 8 for connecting the intermediate portion 11 to the tool.