Tool Head

Abstract

A tool head includes a first tool and a second tool disposed circumferentially on the tool head where the tool head has a rotation axis. The first tool of the tool head is an adjustable tool that is axially movable such that an axial position, relative to the second tool of the tool head, is settable.

Description

BACKGROUND AND SUMMARY OF THE INVENTION

The present invention relates to a tool head, to a method for machining an inner surface of a cylinder, and to a use of a tool head.

The cylinders in question are, in particular, the cylinders of internal combustion engines. It is state of the art to provide the cylinder inner surfaces, in particular of aluminum crankcases, with a coating, for example applied by means of a thermal spraying process, this coating process being preceded by activation of the cylinder inner surface to ensure the adhesion of the coating. In this context, it is known to roughen the cylinder running surfaces, by means of high-pressure water-jet technology, before coating. This process, however, is highly dependent on the quality of the casting. Moreover, the process-related necessary input of investment, energy and resources is problematic. A more recent approach consists in mechanical machining of the cylinder wall before coating, in particular, for example, applying grooves that, in a subsequent forming or deforming step, are possibly also deformed so as to produce undercuts that are intended to enable the coating to grip. Thus, in certain circumstances, some of the aforementioned disadvantages may be eliminated. The difficulty, however, is to ensure that the coating will last reliably over the entire service life.

It is therefore an object of the present invention to specify a tool head, a method for machining an inner surface of a cylinder, and a use of a tool head that eliminate the aforementioned disadvantages and that, at the same time, can be realized in a simple and inexpensive manner.

According to the invention, arranged circumferentially, in particular rotatably, on a tool head, which has a rotation axis, there are at least one first and at least one second tool, wherein the at least one first tool is an adjustable tool that is arranged in an axially movable manner, in such a manner that an axial position, relative to the at least one second tool, can be set. In other words, the adjustable tool is arranged so as to be movable along a direction of advance of the tool head, or along the aforementioned rotation axis, in such a manner that a machining sequence can be set along the rotation axis/direction of advance. This is advantageous, in particular, when machining includes a forward and back movement, or an in and out movement, as is the case in the machining of a cylinder of a crankcase of an internal combustion engine.

The term position, or (machining) sequence, means in this case that it is possible to define an engagement sequence, i.e., that which tool, or which of the tools, that is/are to be the first, or also last, to reach, or machine, a particular region of the cylinder wall can be set. To that extent, the tool integrally provides for at least two-stage machining, depending on the tools used.

Expediently, the first and second tools are arranged in a rotatable manner in the tool head. The tools may be mounted via a rolling bearing arrangement. According to a preferred embodiment, they are mounted only on plain bearings.

For the purpose of machining the cylinder, the tool head, according to an embodiment, connected, or driven, via a machine tool or a machining center, etc., is put into rotation and inserted into a cylinder. Advantageously, the tools, since they are arranged, or mounted, in a rotatable manner in the tool head, are in this case automatically put into a rotary motion by the contact with the cylinder wall. Advantageously, therefore, there is no need for them to have their own drive.

The positioning of the at least one adjustable tool during insertion into the cylinder can then advantageously be used to set the machining sequence of the tools, as it were along a first direction of advance. During withdrawal, as it were along a second direction of advance that is opposite to the first direction of advance, the at least one adjustable tool is repositioned relative to the other tool or tools, such that it is possible, for example, during withdrawal of the tool head from the crankcase, to maintain the same machining sequence that was also used during insertion. A surface structure produced during insertion is thus not destroyed—by a possibly “incorrect” tool sequence—but is actually worked further and/or reworked.

According to a preferred embodiment, the at least one adjustable tool is arranged with play, or has an adjustment distance, in the axial direction, in other words along the rotation axis of the tool head. It is thereby possible to realize the orientation, and thus the adjustment, of the adjustable tool without any mechanical adjusting mechanism. The adjustment is effected, as it were, automatically as the tool head is inserted into or withdrawn from the respective cylinder to be machined. The magnitude of the adjustment distance depends on the dimensions of the tool head, and is in a range, for example, of between 1 and 10 mm. The at least one second tool also expediently has an at least slight axial play, which, however, does not serve to effect any adjustment, but to mount the tool, in particular in a rotatable manner. Expediently, the position, or location, of the at least one second tool is defined axially or, also, radially.

Alternatively, the tool head is designed to actively adjust the at least one adjustable tool along the axial direction, for example by provision of an electrical, hydraulic and/or pneumatic, in particular mechanical or kinematic, drive, that is designed to displace, or position, the at least one adjustable tool in the axial direction.

According to a preferred embodiment, the at least one adjustable tool is a roughening tool, wherein the at least one second tool is a forming tool. Particularly preferably, a multiplicity of forming tools, for example five to ten, and a multiplicity of roughening tools, in the same number, are provided circumferentially and alternately on the tool head. Alternative configurations are likewise conceivable. Preferably, the tools have a substantially cylindrical (possibly also conical) basic body, or tool body, since this shape allows mounting in the tool head in a structurally simple manner. In particular, this enables the tools to rotate very easily about their respective longitudinal axes. Moreover, the aforementioned play can very easily be set over the length of the cylindrical tool body, such that no further adaptations are necessary on the tool head, or on a corresponding bearing portion or bearing ring of the tool head, in or on which the tools are arranged. Preferably, the tool head has a correspondingly realized cage, for mounting the first and/or second tools. In the case of preferred embodiment, a length of the tool bodies is approximately 5 to 30 mm, particularly preferably approximately 10 to 20 mm. Typical diameters are approximately 5 to 20 mm, preferably approximately 8 to 15 mm.

According to an embodiment, the tool head has an upper and a lower base plate, arranged between which is a cylindrical basic body, on or on which the tools are arranged and mounted, for example in combination with the aforementioned cage. Alternatively, the aforementioned basic body may be surrounded by an additional bearing ring that, additionally or alternatively, is used for arranging and/or mounting the tools. As another alternative, the tools may also be mounted, at least partly, via the upper and the lower base plate, the upper base plate expediently have a suitable connection region for arrangement of the tool on a tool spindle. The basic structure of the tool is not limited to the aforementioned variants, but may be realized in a great many ways, in particular owing to the structurally simple basic concept.

According to an embodiment, the first and the second tool have engagement regions, wherein the engagement regions are preferably cylindrical. The engagement regions are those regions of the tools that are designed for machining, and bear against the surface to be machined.

Expediently, because of ease of production, the first and the second tool have cylindrical basic bodies. According to an embodiment, the basic bodies are initially set, or positioned, at a slight angle, to facilitate insertion into a cylindrical body to be machined. For this purpose, also advantageously, the basic bodies are mounted in a floating manner, making it possible to achieve a certain orientation.

Preferably, the engagement regions have a greater diameter than the otherwise cylindrical basic bodies of the tools. The engagement regions are thus preferably realized as a kind of offset. Alternatively, however, the engagement regions (of the first and/or second tools) may also be realized directly on the circumferential surfaces of the, in particular cylindrical, basic bodies of the tools. Realization as an offset offers the advantage that the length of the offsets can be used, in combination with the adjustment distance, to set the machining sequence in a very exact manner. In preferred embodiments, diameters of the engagement regions are in a range of from approximately 5 to 25 mm.

Preferably, the engagement regions each form effective diameters, wherein the effective diameter of the at least one first tool, in particular the roughening tool, projects over the effective diameter of the at least one second tool, in particular the forming tool. Since, according to a preferred embodiment, the roughening tool follows the forming tool, forming is effected first, following by roughening. In preferred embodiments, the aforementioned oversize is in a range of from approximately 0.01 to 1 mm, particularly preferably in a range of from approximately 0.02 to 0.5 mm. According to various embodiments, in particular for the machining of crankcases/cylinders of passenger-car engines, the effective diameters are approximately 70 to 100 mm. In the case of motorcycle motors, the diameters may also be, for example, significantly smaller or larger, or also significantly larger in commercial vehicle engineering or in the case of large engines. However, the basic structure does not change as a result. The differing effective diameters may be realized by a different arrangement of the tools in the tool head, or by differing diameters of the tools themselves, or of their engagement regions, or also by the design or shape of the first and second tools, cf. the aforementioned conical tool basic bodies.

According to an embodiment, the at least one second tool is arranged in a radially displaceable manner. For this purpose, according to an embodiment, the at least one second tool has a conical main body that is supported on a corresponding conical portion of the tool head, and that is arranged on the latter so as to be adjustable, or movable, along the rotation axis. The conical basic body in this case tapers along a first direction of advance that corresponds to one direction, for example in the case of insertion into a cylinder, such that, when being inserted into a cylinder, the at least one second tool is pressed radially outward. In the case of design as a forming tool, forming of the cylinder wall, in particular of the webs, grooves, etc. applied therein, is thus advantageously effected during insertion into the cylinder. During withdrawal from the cylinder, the at least one second tool moves, as it were, in reverse.

Preferably, the at least one first tool has a cylindrical basic body, wherein the engagement region may be realized as an offset or, also, directly on the basic body. Owing to the displacement capability of the at least one first tool along the direction of advance, it is ensured that roughening of the cylinder wall is effected last, during withdrawal from the cylinder. As mentioned, that at least one second tool also has a cylindrical basic body.

It must be mentioned at this point that the tool head is used, in particular, in the context of activation of cylinder inner surfaces in the case of thermal coating, in particular in the further machining of a cylinder following machining to remove material from the cylinder inner wall. In the case of the aforementioned machining to remove material, grooves/webs, for example, are applied for the purpose of activating the cylinder wall for the subsequent coating. Preferably, not only are the grooves then deformed by means of the present tool, in particular for the purpose of producing undercuts, but the webs between them are also structured by the roughening tools, thereby effecting optimal micro and macro gripping with the subsequently applied coating, which is applied, for example, by means of thermal spraying.

According to an embodiment, the engagement region of the first tool, thus in particular of the roughening tool, is coated, in particular diamond-coated or corundum-coated, or is formed by a coating. Alternatively or additionally, the engagement region has protuberances, projections, ridges, flutes and/or the like. In the case of a diamond coating, a grain diameter of between D91 and D301 is preferably selected. Preferably, the coating is harder than the material to be formed. Preferably, the coating exhibits no affinity with the material to be formed.

The engagement region of the at least one second tool expediently has a substantially smooth or flat surface.

Preferably, the first and/or the second tool are/is made of hard metal. It is thus possible, advantageously, to realize tools that have an extremely long service life.

According to an embodiment, the axial movement capability and/or a length of the engagement regions are/is dimensioned in such a manner that the engagement regions of the roughening tools and of the forming tools overlap, or do not overlap, in an end position. The end position in this case means the maximum adjustment distance of the adjustable tool in the one or the other direction. Depending on the length of the engagement regions, or depending on the maximum adjustment distance along the axial direction, the tool head may be designed such that an engagement of the differing tools, relative to the rotation axis, is effected, or also not effected, as it were completely in succession. The adjustment may also be designed such that, for example, a portion of a cylinder—as a result of the rotation of the tool head—is machined alternately by a forming tool and then by a roughening tool, etc. In this case, also, however, it can be ensured that a particular location of the cylinder “sees” a roughening tool last.

According to an embodiment, the tool head comprises a drive unit, for driving one or more first and/or second tools.

According to an embodiment, the tool head comprises a cooling means. In particular, the cooling means is designed to cool the circumferentially arranged tools. Such a cooling means is advantageous, in particular, if coated roughening tools are used, such as, for example, diamond-coated roughening tools, since it can thus be ensured that the coating, for example in the form of diamond, or also corundum, holds on the corresponding tool. Typical coolant flows in this case operate at a pressure of up to 80 bar. According to an embodiment, the coolant flow may be used to drive the tools. As mentioned at the beginning, according to an embodiment the rotatably arranged, or mounted, tools are driven as it were indirectly by the rotation of the tool head relative to the stationary cylinder wall. This results, during insertion into the cylinder, in a very pronounced rotational speed gradient. To that extent, a drive, or a certain impulsion, that puts the tools at least into a certain rotary motion has proved to be extremely advantageous in respect of the wear behavior.

The invention is also directed toward a method for machining an inner surface of a cylinder, in particular a cylinder of an internal combustion engine, comprising the steps: providing a tool head that has a rotation axis and a multiplicity of circumferentially arranged tools;

preferably rotating the tool head and inserting it into a cylinder for the purpose of machining a cylinder wall;

altering an axial position of at least one tool, relative to the other tool or tools, for the purpose of setting a machining sequence.

Expediently, the method comprises the step:

changing the sequence of the tools, at least while or for the purpose of withdrawing them from the cylinder.

In other words, a change of direction is thus effected. For example, it is thus possible to ensure the same machining sequence during withdrawal as during insertion into the cylinder. The tools are thus not fixedly oriented in relation to each other, but flexibly, such that optimal machining can be effected, irrespective of the direction of advance. In particular, the operation of withdrawing from the cylinder can be used, advantageously, to roughen the cylinder wall.

According to a preferred embodiment, at least one tool is a roughening tool, and at least one tool is a forming tool, the method comprising the step:

arranging the at least one roughening tool entirely or at least partly behind the at least one forming tool with respect to the direction of advance.

This arrangement may be realized by a corresponding adjusting mechanism of the tool head. Particularly advantageously, however, the arrangement is realized by mounting the roughening tools with play, such that the aforementioned setting can be effected, as it were, automatically.

According to an embodiment, the method comprises the steps:

machining the cylinder wall for the purpose of applying, in particular for the purpose of forming and applying, a surface structure;

coating the inner wall of the cylinder following the machining by means of the tool head.

As already indicated, the surface structure comprises, for example, a multiplicity of grooves, flutes, threads or spirals, preferably applied mechanically. Alternatively or additionally, the structuring may also be effected by means of suitable laser technology. Preferably, thermal spraying is used for the coating operation, for example with so-called flame spraying, or plasma spraying, or arc spraying, being used. In this case, powder particles and/or wire particles are spun, or sprayed, onto the surface of the substrate to be coated. The coating is effected following machining of the cylinder wall by means of the tool head.

The invention is additionally directed toward a use of a tool head according to the invention for the purpose of producing an internal combustion engine, or a crankcase.

The advantages and features mentioned in connection with the tool head also apply analogously and correspondingly to the method and to the use, and vice versa and between each other.

Further advantages and features are given by the following description of preferred embodiments of a tool head, with reference to the appended figures.

Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial top view of a tool head, as viewed along a rotation axis, and a detail view to illustrate the differing effective diameters of the tools; and

FIG. 2 is a schematic sectional representation of a tool head, to illustrate the functionality of the adjustable tool.

DETAILED DESCRIPTION OF THE DRAWINGS

Shown in FIG. 1, in the left half of the figure, as viewed along a rotation axis R, is a tool head 10 having a multiplicity of circumferentially arranged first and second tools 20 and 22, respectively, wherein a roughening tool 24 and a forming tool 22 are shown alternately in each case. A cylinder wall 50, which is machined by means of the tool head 10, is represented by a broken line. Shown in outline in the right half of the figure are a roughening tool 24 and a forming tool 22, with their respective engagement regions 23 and 25, respectively, wherein it is evident that the engagement region 25 of the roughening tool 24 projects over the engagement region 23 of the forming tool 22 by a radial offset d. In other words, an effective diameter D24 of the roughening tool 24 is greater than an effective diameter D22 of the forming tool 22. Typical values in this case are in a range of from approximately 0.01 to 1 mm. To aid orientation, the course of the rotation axis is again indicated by the reference R.

FIG. 2, in its left figure half, then shows half of a tool head 10, comprising an upper and a lower base plate 13, between which a cylindrical basic body 12 is arranged. A bearing portion, or bearing ring 14, which serves, inter alia, to support the tools 22, 24, is indicated by the reference 14. In principle, the configuration comprising the basic body 12, or the base plates 13 and the bearing portion 14, is to be understood as being merely an example. The arrangement, or support, of the tools 22, 24 may be effected in many ways. In particular, the axial movement capability, or the axial play along the rotation axis R, may be achieved by various types of design. FIG. 2 serves, in particular, to illustrate the functioning of the first tool, or adjustable tool, in this case a roughening tool 24, in the right half of the figure. If the tool head is directed downward, along the direction of advance V1 (in the middle region of the figure), for example during the insertion of the tool head 10 into a cylinder, this results in the adjustable tool, in particular the roughening tool 24, moving backward in relation to the direction of advance V1, this resulting in an axial offset x. During withdrawal from the cylinder, shown in outline in the right half of the figure (cf. reference V2), a realignment of the adjustable tool, or of the roughening tool 24, is effected automatically (or as a result of the provision of an adjusting means), such that the latter tool (again) follows with respect to the forming tool 22. The axial position/location of the at least one second tool 22 is maintained in this case. Consequently, a forming operation is performed first, and then a roughening operation. The automatic orientation may be effected, in particular, by mounting of the corresponding tool basic bodies 26 with play. Advantageously, it can be ensured, at least in the case of this embodiment, that roughening of the cylinder wall is effected as a final machining step.

LIST OF REFERENCE CHARACTERS

• 10 tool head
• 12 cylindrical basic body
• 13 base plate
• 14 bearing portion, bearing ring
• 20 first tool, adjustable tool
• 22 second tool, forming tool
• D22 effective diameter of forming tool
• 23 engagement region of forming tool
• 24 roughening tool
• D24 effective diameter of roughening tool
• 25 engagement region of roughening tool
• 26 tool body
• 50 cylinder wall
• d radial offset
• x axial offset
• V1, V2 direction of advance
• R rotation axis

The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.

Claims

1. A tool head, comprising: a first tool and a second tool disposed circumferentially on the tool head, wherein the tool head has a rotation axis;wherein the first tool is an adjustable tool that is axially movable such that an axial position, relative to the second tool, is settable.

2. The tool head as claimed in claim 1, wherein the adjustable tool is disposed with play, or has an adjustment distance, in an axial direction.

3. The tool head as claimed in claim 1, wherein: the adjustable tool is a roughening tool;the second tool is a forming tool; andthe roughening tool follows the forming tool along a direction of advance.

4. The tool head as claimed in claim 1, wherein the first tool and the second tool each have a respective engagement region and wherein the respective engagement region is cylindrical.

5. The tool head as claimed in claim 1, wherein the first tool and the second tool each have a respective cylindrical basic body.

6. The tool head as claimed in claim 4, wherein the respective engagement regions each form a respective effective diameter and wherein the effective diameter of the first tool projects over the effective diameter of the second tool.

7. The tool head as claimed in claim 1, wherein the second tool is radially displaceable.

8. The tool head as claimed in claim 4, wherein the engagement region of the first tool is diamond-coated.

9. The tool head as claimed in claim 4, wherein an axial movement capability and/or a length of the respective engagement regions are/is dimensioned such that the respective engagement regions overlap, or do not overlap, in an end position.

10. The tool head as claimed in claim 1 further comprising a drive unit, wherein the first tool and/or the second tool is drivable by the drive unit.

11. A method for machining an inner surface of a cylinder, comprising the acts of: providing a tool head that has a rotation axis and a plurality of circumferentially disposed tools;inserting the tool head into a cylinder for a purpose of machining a cylinder wall; andaltering an axial position of at least one tool of the plurality of circumferentially disposed tools relative to another tool of the plurality of circumferentially disposed tools for a purpose of setting a machining sequence.

12. The method as claimed in claim 11, further comprising the act of: changing the machining sequence for a purpose of withdrawing the tool head from the cylinder.

13. The method as claimed in claim 11, wherein a first tool of the plurality of circumferentially disposed tools is a roughening tool and a second tool of the plurality of circumferentially disposed tools is a forming tool; and further comprising the act of:arranging the roughening tool entirely or at least partly behind the forming tool with respect to a direction of advance.

14. The method as claimed in claim 11, further comprising the acts of: machining the cylinder wall for a purpose of applying a surface structure; andcoating the cylinder wall following the machining by the tool head.

15. A use of the tool head as claimed in claim 1 to produce an internal combustion engine.