The invention relates to a tool-holding device according to the preamble of independent claim 1.

According thereto, the invention relates in particular to a tool-holding device for a pipe-machining apparatus, wherein the tool-holding device has a tool holder for fastening a tool to the tool-holding device in such a manner that the tool is rotatable about a longitudinal axis of a pipe to be machined.

A tool-holding device of this type is generally known in principle from the prior art. For example, the publication DE 197 26 498 A describes a pipe-machining apparatus which has a tool-holding device for holding a tool, and a motor and a transmission arrangement for rotation of the tool-holding device about an axial longitudinal axis of the pipe-machining apparatus. The tool is a cutting tip for machining a pipe end, which cutting tip is designed as an indexable tip and has two active cutting edges. In order to secure the pipe, the end of which is to be machined, the pipe-machining apparatus known from this prior art has an internal clamping device which can be inserted into the pipe to be machined. The internal clamping device has three clamping wedges, with the aid of which the pipe is held. The previously known pipe-machining apparatuses are usable ^" for different pipe-machining operations depending on the tool-holding device being used. Thus, tool-holding devices which receive the cutting tips in such a manner that the cutting edges are oriented radially are suitable for smoothing a pipe end. If, by contrast, the cutting tips in the tool-holding device are oriented in such a manner that they enclose an acute angle with the pipe axis, said cutting tips are suitable for beveling the pipe ends.

Different radial positions of the cutting tips are required depending on the diameter and wall thickness of the pipe to be machined with the pipe-machining apparatus. Different welding techniques for connecting pipes also require a multiplicity of different profiles of the pipe ends, for example V-shaped, U-shaped or else Y-shaped. For the use of one pipe-machining apparatus in the different use scenarios, a multiplicity of different tool-holding devices with cutting tips fitted thereon is therefore required, this requiring high-costs . There may also be an increase in the time required for machining a pipe end by means of at least two separate working steps for smoothing and beveling in each case and because of reequipping the pipe-machining apparatus between the working steps. On the basis of this definition of the problem, the present invention is based on the object of developing a tool-holding device of the type mentioned at the beginning to the effect that a plurality of machining steps can be executed in one operation in a manner which is easy to realize but is nevertheless effective using the pipe-machining apparatus.

This object is achieved according to the invention by the subject matter of independent patent claim 1. Advantageous developments of the solution according to the invention are indicated in the dependent patent claims .

According thereto, the tool-holding device for a pipe- machining apparatus is proposed, wherein the tool- holding device has a tool holder for fastening a (first) tool to the tool-holding device in such a manner that the tool is rotatable about a longitudinal axis of a pipe to be machined, wherein, according to the invention, the tool holder is fastenable to the tool-holding device in different positions spaced apart from one another in the longitudinal direction of the tool-holding device, the longitudinal direction of the tool-holding device being predetermined by the longitudinal axis of the pipe to be machined.

Owing to the fact that the tool holder and therefore the (first) tool which is fastened to the tool holder is fastenable to the tool-holding device in different positions spaced apart from one another in the longitudinal direction of the tool-holding device, the machining of the pipe can be varied without changing the tool-holding device. By means of a change in the longitudinal position of the tool relative to the tool- holding device, the pipe end profile to be achieved during the machining can be influenced, for example from V-shaped to Y-shaped.

In a preferred realization of the solution according to the invention, the tool-holding device furthermore has a receptacle for fastening a further (second) tool to the tool-holding device in such a manner that the second tool advances ahead of the first tool in the advancing direction of the tool-holding device during the machining of the pipe. In detail, in a state in which it is fastened in the receptacle, the second tool advances ahead of the first tool along the longitudinal axis of the pipe toward the end of the pipe.

The second tool, because of the position in which it advances ahead, is capable of executing a machining step on the pipe end while the first tool executes a second, consecutive (different) machining step. In this case, the first machining step may prepare the pipe end for the second machining step, and therefore the latter can be executed with lower loading for the first tool. In principle, it is conceivable for the first tool to be fastenable in the tool-holding device to the tool holder in a receptacle in different radial positions. In other words, in a preferred embodiment of the solution according to the invention, the tool holder has a receptacle which serves for fastening the first tool to the tool-holding device, wherein, in detail, the first tool is fastenable at various positions spaced apart from one another in the radial direction. As a result, it is possible, without changing the tool- holding device, to change the position of the first tool in such a manner that different pipe diameters, wall thicknesses and pipe end profiles can be machined.

The first tool of the tool-holding device is preferably designed for smoothing a pipe end. In this case, it is conceivable for the first tool to have a cutting edge which, in the state in which the first tool is fastened to the tool holder, is oriented perpendicularly to the longitudinal axis of the pipe to be machined.

It is thereby also possible for smoothing of the pipe end to be carried out with the pipe-machining apparatus, in which case an exactly planar surface oriented in a radial plane with respect to the pipe axis can be produced at the pipe end.

Furthermore, it is conceivable for the second tool to be designed for beveling a pipe end. In particular, the cutting edge of the second tool is intended to enclose an acute angle with the longitudinal axis of the pipe to be machined. According thereto, it is possible to carry out both smoothing machining and beveling machining at the end of the pipe to be machined in one working step. In this case, it is in principle conceivable for the cutting edge of the second tool to be curved convexly in such a manner that the cutting edge of the second tool runs from that side facing the longitudinal axis of the pipe to be machined to the side facing away from the longitudinal axis of the pipe to be machined. There is also the possibility of the cutting edge of the second tool following a convex curvature from the side facing the longitudinal axis to the side facing away from the longitudinal axis. The tool-holding device can therefore be used not only to form V-shaped or Y-shaped bevels at the pipe ends, but also U-shaped bevels.

In a preferred realization of the solution according to the invention, the tool-holding device has a multiplicity of receptacles for fastening a multiplicity of second tools in such a manner that the second tools are arranged in a rotationally symmetrical manner about the longitudinal axis of the pipe to be machined. The rotational symmetry of the tool receptacles results in forces acting radially on second tools fastened to said tool receptacles during the machining operation being able to be mutually neutralized. In connection with the acute angle of the cutting edges of the second tools, the tool-holding device is automatically centered on the pipe end, and the guide of the pipe-machining apparatus is subjected to a less severe load or may be designed to be lighter structurally .

Furthermore, the present invention provides a pipe- machining apparatus with a tool-holding device according to the invention. The invention is described by way of example below using an embodiment and with reference to the attached drawings, in which: Fig. 1 shows an embodiment of a pipe-machining apparatus with a tool-holding device according to the prior art in a side view with a pipe to be machined in a sectional view;

Fig. 2 shows a perspective view of a tool-holding device according to one embodiment of the invention;

Fig. 3 shows a top view along the pipe axis of that side of the tool-holding device according to fig. 2 which faces the pipe end;

Fig. 4 shows a side view perpendicularly to the pipe axis of the tool-holding device according to fig. 2;

Fig. 5 shows a section of the tool-holding device with a tool holder along the axis B-B from fig. 3;

Fig. 6 shows a partial section of a perspective view of the tool-holding device according to fig. 2 of the invention;

Fig. 7 shows a section of the tool-holding device without a tool holder along the axis B-B from fig. 3; and

Figs 8a-c show a top view of a tool holder according to one embodiment of the invention.

Fig. 1 shows a pipe-machining apparatus 1 which has a tool-holding device 4 known from the prior art. The pipe-machining apparatus 1 has a housing 2 and a handle 3. A tool carrier 5 which carries a tool in the form of a cutting tip 6 is arranged or accommodated in the tool-holding device 4. In the embodiment shown, the cutting tip 6 serves to taper that end of a pipe 7 which faces the pipe-machining apparatus 1 or the tool carrier 5, i.e. to provide said end with a bevel, and therefore to prepare said end for a welding process. The tool-holding device 4 together with the tool carrier 5 and the cutting tip 6 is arranged concentrically with respect to an axial longitudinal axis 105 of the pipe-machining apparatus 1 and so as to be rotatable about said longitudinal axis 105.

In order to securely fix the pipe 7 prior to and during a planned machining operation, the pipe-machining apparatus 1 shown in fig. 1 has an internal clamping device 8 with three clamping wedges 9 which can be inserted into the pipe 7 to be machined. The three clamping wedges 9 each consist of a metal plate, the plate plane of which extends in each case in the radial direction and in the axial direction with respect to the longitudinal axis 10. The clamping wedges 9 are guided in a radial guide body 12.

In the embodiment described here, the radial guide body 12 is of cylindrical design and has a through hole in the center thereof. The radial guide body 12 is fastened to an actuating rod which is arranged movably in the axial longitudinal direction, i.e. the direction of the longitudinal axis 10. A mast 24 is arranged with respect to the axial longitudinal axis 10 so as to be movable in relation to the tool-holding device 4 (and to the housing 2) . The actuating rod is arranged in the mast 24 so as to be movable and displaceable along the axial longitudinal axis 105 relative to said mast and therefore likewise relative to the tool-holding device 4. Therefore, on the one hand, the actuating rod can be moved axially relative to the mast 24 and, on the other hand, the mast 24 can be moved in the axial longitudinal direction in relation to the tool-holding device 4 and in relation to the tool carrier 5. Clamping or fixing of the pipe 7 prior to the planned machining operation is accordingly realized by the actuating rod being moved along the axial longitudinal axis 105 in a direction from the clamping wedges 9 toward the housing 2 (the mast 24 remains fixed in position in the process) until the clamping wedges 9 bear against the inside of the pipe 7 and hold the latter securely in the position thereof. The actuating rod is then fixed in the position thereof by means of a retaining sleeve 25 which is formed integrally with a handle 26 assigned thereto.

After the pipe 7 has been fixed in place, the machining thereof can be begun. The relative movability between the tool-holding device 4 (including the housing 2 and handle 3) and the mast 24 ensures that the tool-holding device 4 together with the tool carrier 5 and the cutting tip 6 is movable along the axial longitudinal axis 105 in relation to the pipe 7, and therefore an advancing of the tool in the direction of the pipe 7 or into the pipe 7 and an opposed movement are possible. For the machining, the tool-holding device 4 is set into rotation relative to the pipe 7 and to the housing 2 by means of an electric motor (not illustrated) , which is located in the housing 2 and is placed in the region of the handle 3, via a transmission (likewise not illustrated) such that the tool-holding device 4 together with the tool carrier 5 and cutting tip 6 rotates about the axial longitudinal axis 105.

A tool-holding device 100 according to one embodiment of the present invention is shown in fig. 2 to fig. 7. Said tool-holding device 100 is suitable for use in a pipe-machining apparatus 1 according to fig. 1, specifically instead of the tool-holding device 4.

The tool-holding device 100 according to the invention has a cylindrical basic body 101 with an axial leadthrough 102 arranged along the axis of rotation 105. The basic body 101 may also have different geometries, for example the shape of a prism. The axial leadthrough 102 serves to receive an axial guide, wherein the axial guide is suitable, as is apparent, for example, from fig. 1, for clamping a pipe 7 and for fixing said pipe with the tool-holding device 100 relative to the pipe- machining apparatus 1. On the side facing away form the pipe end, the basic body 101 has means for transmitting force from a drive to the tool-holding device 100, which drive can set the tool-holding device 100 into a rotating movement about the axial guide. The means may be a cylindrical recess 103 with a toothed ring which is arranged on the inside of the circumference of said recess and is in engagement with one or more gear wheels of the drive. As an alternative, pins or depressions may be formed on that side of the basic body 101 which lies opposite the drive, said pins or depressions being in engagement with corresponding depressions or pins of the drive. The axial guide may also be in the form of a prism and transmit a force to a corresponding, prismatic leadthrough 102.

On the side facing the pipe end, the basic body 101 has a recess 110 for receiving a tool holder 120. The recess 110 is arranged between the axial leadthrough 102 and that edge of the basic body 101 which is remote from the axis, and extends parallel to the axis of rotation 105 into the basic body. An axial leadthrough 111 reaches from the side facing away form the pipe end through the basic body 101 into the recess 110, and a means for fastening and adjusting the axial position of the tool holder 120 can be guided through said leadthrough. At least one radial leadthrough 112 which opens into the recess 110 is arranged through the basic body 101 from the cylinder casing or a circumferential side of the basic body 101. By means of a thread in the radial leadthrough 112, a threaded pin 113 can be screwed into the leadthrough 112, said threaded pin securing the tool holder 120 in the recess 110 and preventing rotation parallel to the axis of rotation 105.

As an alternative, the recess 110 can deviate from rotational symmetry at least on one side such that a corresponding tool holder inserted into said recess can rotate freely not parallel to the axis of rotation 105.

Figs 8a-c show the tool holder 120 in various views.

According thereto, the tool holder 120 has a foot 121 which is designed to be accommodated in the recess 110. In a preferred embodiment, the foot has a cylindrical shape and has a flattened portion in the form of a surface 122 perpendicularly to the radial leadthrough 112 on a side which, in the state in which said foot is fastened in the recess 110, faces the radial leadthrough 112. In this manner, a threaded pin which is inserted through the radial leadthrough 112 can secure the tool holder 120 against rotation in the recess 110. The foot 121 furthermore has a longitudinal bore 123 with an internal thread. If the foot 121 is located in the corresponding recess 110 of the basic body 101, a fastening means, for example a bolt 114, can be inserted through the axial leadthrough. Ill in the basic body 110, said fastening means engaging in the thread in the longitudinal bore 123 in the foot 120. The bolt 114 is secured in the axial leadthrough 111 by a suitable means, for example a snap ring, in such a manner that said bolt can absorb an axial pressure and at the same is mounted rotatably. The axial position of the tool holder 120 can be adjusted by rotation of the bolt 114, thus also enabling the axial position of a tool located on said tool holder to be adjusted. As an alternative, the bolt 114 can be fastened in the leadthrough 111 or can be manufactured integrally with the basic body 101 in the form of a journal with an external thread. In this case, the tool holder 120 is screwed onto the journal by the thread in the interior of the foot 121 such that the axial position of the tool holder 120 can be adjusted. In the screwed-in state, the threaded pin 113 in the radial leadthrough 112 together with the surface 122 already described then secures the tool holder 120 against rotation and therefore against adjustment of the axial position.

Furthermore, it is conceivable that, instead of the bolt 114, a journal without an external thread in the recess 110 protrudes axially. A threaded pin with a central, longitudinal bore which ends within the threaded pin and does not extend through the entire threaded pin is then located in the longitudinal bore

123 in the foot 121, which bore has an internal thread, and the journal instead of a bolt 114 enters the opening in said threaded pin. The foot 121 can thereby be placed into the recess 110 and onto the journal until the journal strikes against the end of the bore in the threaded pin. If the tool holder 120 is removed from the recess 110 and the threaded pin is screwed into the foot 121 or unscrewed therefrom, the stop for the journal changes and therefore so does the axial position of the tool holder 120 when the latter is inserted again into the recess 110.

The tool holder 120 furthermore has a tool receptacle

124 for receiving a first tool which is fitted on the foot 121 on the side facing the pipe end. The tool receptacle 124 has a receiving surface 125 which, in the preferred embodiment, when the tool holder 120 is fastened in the tool-holding device, extends parallel to the axis of rotation 105 and radially away from the axis of rotation 105. Threaded bores 127 which are arranged radially in a line and are spaced apart from one another are located in the receiving surface 125. Bolts 128 can be passed through fastening bores 141 in a cutting tip 140 and can connect the latter fractionally to the tool receptacle 124.

Furthermore, the tool receptacle 124 has a side surface 126 adjacent to the receiving surface 125, which side surface lies in the plane of rotation about the axis of rotation 105 and extends radially outwards. The side surface 126 is in contact at least in regions with a side surface of the cutting tip 140, which side surface is located opposite the pipe end, and thereby transmits the axial force exerted by the pipe-machining apparatus 1 on the tool-holding device 100 and the tool holder 120 to the cutting tip 140 without loading the bolt 128 with high shearing forces . A plurality of threaded bores 127 in the receiving surface 125 makes it possible to arrange the cutting tip 140 in different radial positions and thus to adapt the position of the cutting tip to different pipe diameters and pipe wall thicknesses.

In the preferred embodiment, the cutting tip 140 is designed by means of the radial orientation of the cutting edge 142 thereof to smooth a pipe end. However, it is possible, with a different orientation of the receiving and/or side surfaces, also to equip tool holders with different tools and thereby to carry out other operations .

The tool holder 120 can be manufactured in single-piece or multiple-piece form.

Furthermore, the basic body has at least one tool receptacle 150 for receiving a second tool. The tool receptacle 150 extends in the radial direction entirely or partially along a line from the central leadthrough 102 to the circumferential delimitation of the basic body 101. The tool receptacle 150 has a receiving surface 151 which is oriented parallel to the axis of rotation and radially. Threaded bores 153 arranged in a line and spaced apart from one another are located in the receiving surface 151. Bolts 154 can pass through fastening bores 161 in a cutting tip 160 and can connect the latter frictionally to the tool receptacle 150.

The tool receptacle 150 has a side surface 152 adjacent to the receiving surface 151. The side surface 152 bears tangentially against an envelope of a cone which is oriented in a rotationally symmetrical manner to the axis of rotation 105 and opens towards the pipe end. The threaded bores 153 are arranged in a line parallel to the side surface 152. The side surface 152 is in contact at least in regions with a side surface of the cutting tip 160, which side surface is located opposite the pipe end, and thereby transmits the axial force exerted by the pipe-machining apparatus 1 on the tool- holding device 100 to the cutting tip 160 without loading the bolts 154 with high shearing forces.

A plurality of threaded bores 153 in the receiving surface 151 makes it possible to arrange the cutting tip 160 in different radial positions and thus to adapt the position of the cutting tip to different pipe diameters and pipe wall thicknesses.

In the preferred embodiment, the cutting tip 160 is designed by orientation of the cutting edge 162 thereof with an envelope of a cone about the axis of rotation to bevel a pipe end. However, it is possible, of course, with a different orientation of the receiving and/or side surfaces, also to equip tool holders with different tools and thereby to carry out other operations .

The cutting edge 162 of the cutting tip 160 is mounted ahead of the cutting edge 142 of the cutting tip 140 along the axis of rotation in the direction of the pipe end in such a manner that first of all the cutting edge 162 comes into contact with the pipe end and, by rotation of the tool-holding device 100 about the axis of rotation 105, machines the pipe end in a metal- removing manner. By means of the adjustable axial position of the tool holder 120, the distance at which the cutting edge 142 of the first cutting tip 140 comes into contact with the pipe end and begins to machine the latter can be changed.

In the preferred embodiment, the cutting edge 162 encloses an acute angle with the axis of rotation 105 and rotates about the pipe end along an envelope of a cone and bevels said pipe end in a conical manner. The cutting edge 142 is arranged in the plane of rotation and thereby smoothes off the sharp edge of the pipe end in order to prepare a Y groove for the connecting seam of two pipes machined in such a manner. If the cutting edge 142 is arranged closer towards the pipe end by means of adjustment of the axial position, the planar region of the pipe end is correspondingly wider.

Instead of a cutting tip 160 with a straight cutting edge 162, a cutting tip 160 with a convex cutting edge 162 can also be used. The pipe-machining apparatus 1 then produces a concave groove in the pipe end in a manner corresponding to the external line of the cutting edge. When two pipe ends machined in such a manner are joined together, a U-shaped groove arises for the welded joint. The possibility of fastening the cutting tips 140 and 160 in the receptacles 124, 150 thereof in different radial positions permits the tool-holding device 100 to be adapted to different pipe diameters.

In one possible embodiment, a plurality of pipe receptacles 150 can be arranged on the tool-holding device 100 in a rotationally symmetrical manner about the axis of rotation 105. The rotational symmetry of the tool receptacles 150 results in forces acting radially during the machining on cutting tips 160 fastened in said tool receptacles being mutually neutralized. In conjunction with the acute angle of the cutting edges of the second tools, the tool-holding device is centered automatically with respect to the pipe end, and the guide of the pipe-machining apparatus is subjected to less loading or can be designed to be structurally lighter. Although the invention is described with reference to an embodiment having a fixed combination of features, it nevertheless also comprises the conceivable other advantageous combinations as stated in particular, but not exhaustively, by the dependent claims. All of the features disclosed in the application documents are claimed as being essential to the invention to the extent that said features are novel over the prior art individually or in combination.