EP2498933A1

EP2498933A1 - Method for shaping a workpiece using friction

Info

Publication number: EP2498933A1
Application number: EP10785334A
Authority: EP
Inventors: Werner Homberg; Daniel Hornjak; Tim Rostek
Original assignee: Universitaet Paderborn
Current assignee: Universitaet Paderborn
Priority date: 2009-11-10
Filing date: 2010-11-08
Publication date: 2012-09-19
Also published as: WO2011057748A1; DE102009052408A1

Abstract

The invention relates to a method for machining at least one workpiece (1) by means of at least one tool (2), wherein - at least one workpiece (1) and at least one tool (2) are brought in frictional contact and a temperature increase of the material of the at least one workpiece (1) is generated by a relative movement between the at least one workpiece (1) and the at least one tool (1) in the friction zone (3) and/or in the regions surrounding the friction zone (3) at least until the material of the at least one tool (1) is plasticized, characterized in that plasticized material of the at least one workpiece (1), in particular during the continuous frictional movement, is repositioned on the at least one workpiece (1) by moving the at least one tool (2) relative to the at least one workpiece (1) to create a shape of the at least one workpiece (1) that is at least locally different from the original shape of the workpiece.

Description

PROCESS FOR REAMING FORMS OF A WORKPIECE

The invention relates to a method for machining at least one workpiece by means of at least one tool, in which the at least one workpiece and the at least one tool are brought into frictional contact and by a relative movement between a workpiece and a tool in the

Friction zone and / or surrounding areas in the friction zone

Temperature increase of the material of the workpiece at least until

Plasticization / softening of the material of the workpiece is generated.

Such a method is e.g. known as friction stir welding, in which two workpieces to be joined with the joining areas are arranged adjacent to each other and by a friction-stirring by rubbing in a contact zone of tool and workpieces to be joined, heating is generated, wherein the heated material of the workpieces to be joined plasticized and by a stirring movement of the tool, the material components of both to be joined workpieces are mixed together, resulting in a joining seam after movement of the tool along the joining direction.

In this type of assembly of two or more workpieces, none of the workpieces undergoes forming, i. The assembled Gesamttwerkstück has the same geometric shape after joining as the individual before joining joined workpieces.

Further, in the prior art, methods of forming workpieces are known, e.g. the pressing or pressing, which entails the disadvantage that the deformability of the workpieces to be formed is limited

CONFIRMATION COPY and it can come during reshaping to failures. To counteract this, it has also become known, upstream or in between

Perform heat treatments.

The object of the invention is to provide a method for forming workpieces, with which the disadvantages of known methods are overcome and with the simple design and procedural manner, a change in shape of workpieces can be achieved. It is also an object of the invention to obtain a method for forming, by means of which forms, in particular hollow structures can be created, which can not be produced by other known Umformprinzipien.

The invention solves this problem by the fact that plasticized material of the at least one workpiece, in particular during the ongoing

Frictional movement, is repositioned by moving the at least one tool relative to the workpiece on the at least one workpiece to build a least differing from the original workpiece shape of the at least one workpiece.

Here, it is the essential idea of the invention, by a rubbing motion between at least one tool and at least one workpiece not only a local plasticization of the grated material of the at least one

Workpiece locally and, if necessary, in the vicinity of the friction zone and thus to achieve a softening, but by a relative movement between the at least one tool and the at least one workpiece a

Repositioning of the plasticized material to make.

In this case, several workpieces can be processed at the same time, for example, if they are arranged next to each other / in each other / next to each other and / or attached. For example, cylindrical workpieces can be arranged one inside the other. Likewise, the forming can be done with several tools. For example, by means of at least one tool, the process of rubbing and thus the temperature increase can be carried out, whereas with at least one further tool, the softened by the plasticization material of the at least one workpiece is repositioned / shifted. In a structurally preferred variant of the method, it can be provided to carry out both the rubbing and thus the temperature increase by means of one and the same tool, as well as the repositioning of the plasticized material.

This repositioning can be effected by means of the at least one tool, the plasticized mass of the material of the workpiece is moved to any desired location. This can be done in one embodiment so that during the shifting or repositioning continually rubbing with the same or another tool is performed to ensure the deformability and displaceability of the plasticized material mass over the entire displacement. Thus, by moving the tool, the plasticized mass in front of the tool in

Movement be pushed, essentially to any location of the workpiece, which can be achieved on the inner or outer surface, in particular with continuous rubbing. It can also be provided to perform the repositioning of the plasticized material and thus the forming without continuous rubbing, especially if previously enough heat energy has been entered into the at least one workpiece.

In a preferred embodiment, according to the invention, by the movement of the at least one tool, one of an, in particular original or already created by previous deformation inner and / or outer

Surface of the at least one workpiece at least locally projecting accumulation of material are generated, in particular in the nature of an opposite surrounding areas increased at least local accumulation of material. It can thus inventively accumulate material and shape in the geometry, in the dimension of the order of the dimension or even larger than the dimensions of the workpiece to be formed, for example, based on the order of magnitude of thickness, length, wall thickness, etc. of the workpiece, thus in the range of many millimeters or centimeters. Likewise, very filigree geometries can be produced by forming the plasticized material.

Material accumulation can be, for example, generate in the axial displacement direction in front of a tool. In the same way, material quantity reductions, e.g. generate in the axial displacement direction behind a tool.

It should be noted that a movement of at least one

Tool is to be understood as any relative movement between the tool and the workpiece. In this case, the movement of a tool can be used to move on the one hand the plasticized material and on the other to shape, for. in that the tool is merely pressed against a material accumulation of plasticized material without causing a local displacement. In particular, the movement of a tool is used to increase by friction the temperature of the at least one workpiece at least until plasticization.

In a preferred embodiment, it is provided that the at least one workpiece and / or the at least one tool moves, for example, to generate a friction movement, e.g. is rotated about an axis of rotation at least partially, with a further relative movement between the workpiece and

Tool is a tool to a workpiece radially and / or tangentially and / or axially employed. The setting can be done, for example, from the outside, for workpieces that have an original or formed in the context of this process mold, even from the inside. The relative movement between a tool and a workpiece for the purpose of friction may be a linear movement rather than a rotating movement.

A structurally and procedurally simple embodiment results when the at least one workpiece is rotated about an axis of rotation, in particular continuously rotating or oscillating over a predetermined angle. For example, this can be achieved if the at least one workpiece in one

Lathe is clamped. Preferably, workpieces can then be rotationally symmetrical workpieces, such as e.g. Tubes or rods with round cross-section, this cross-sectional shape is not mandatory. Likewise, workpieces with any polygonal cross section can be used and formed using this method.

As a tool, any element can be used that can preferably be made non-cutting to the rotating workpiece. Such a tool may e.g. be rigid and e.g. have a blunt end, e.g. plan, spherical, convex or concave may be formed. It is only essential that the material of the workpiece plasticized at a lower temperature than the material of the tool, so that an effective material deformation and

Displacement only takes place on the sides of the workpiece. This can also be achieved by actively cooling a tool or by using a tool

Having plasticizing influencing coating.

A tool can also be flexible. For example, For example, a tool, in particular a tool for generating friction by a belt or a belt, can be formed. This has the advantage that it rests against a workpiece during rubbing or deformation with a larger positive engagement. A belt or belt can also contact a larger peripheral area of a workpiece at the same time.

Accordingly, with a suitable selection of the material pairings of workpiece and tool, essentially any materials can be deformed or reshaped on the side of the workpiece, in particular metals and plastics.

Preferably, light metals such as aluminum or magnesium can be formed by this method. In a preferred variant of the method, provision can be made for a tool to be set against the at least one rotating workpiece axially and / or tangentially and / or radially, and plasticized material of the at least one workpiece at least partially into an area in the direction of adjustment in front of the tool and / or at least partially displaced into an area in Anstellrichtung next to the tool. Here, too, essentially only a relative movement between tool and workpiece or workpiece parts is important.

Especially in the case of one or more revolving workpiece (s), a grinding tool results in an annular (in case of molds) or

Disc-shaped (in full forms) plasticized area within the

Workpiece. Here, by a relative movement of the axially on both sides of this area arranged workpiece parts to each other to be effected in the axial direction, ie parallel to the axis of rotation, that the plasticized material region is compressed and therefore evades the plasticized material of this area in the radial direction. Thus, such an axial movement towards one another results in a radially upstanding movement

Accumulation of material at the location or in the vicinity of the friction zone. Such an accumulation of material can stand up as a workpiece radially outward in the case of solid profiles, as a workpiece radially inward and / or outward in the case of hollow profiles.

In the axial direction, the workpiece parts on both sides of a plasticized area can also be moved away from each other, so that this to a

Material volume reduction leads in the plasticized area.

All axial movements are only dependent on relative movement, i. It may remain stationary one of the workpiece parts, wherein the other is moved axially.

With oscillating relative movements between at least one workpiece and at least one tool, it does not come to a circumferential Heating and plasticization, but essentially only to a local plasticization, in particular, which is essentially limited to a range in the size of the oscillation amplitude or smaller. Such locally plasticized areas can only be locally processed and reshaped, for example, to create recesses, depressions or local accumulations of material.

Material can be translated or re-framed over larger ranges than the amplitude of oscillation if the location of the oscillation is along an e. G. axial or tangential extent of the workpiece is continuously displaced and thus also the place of plasticization mitwandert.

With simultaneously employed tool can by movement of the axially arranged laterally of the tool rotating part of the workpiece in the axial direction on the tool to a laterally arranged in the axial direction next to the tool and generated in the radial direction, in particular inwardly and / or outwardly accumulating material become.

A created by one of the previously mentioned process steps

Material accumulation can e.g. shifted by the tool, i. be moved almost arbitrarily along the axis of rotation or be further formed at the place of production.

By the width of the rubbed and plasticized region and thus the amount of plasticized material, as well as by the width of the axial displacement of at least one laterally arranged plasticized portion workpiece can be determined which radial height and / or axial width receives the upstanding material accumulation.

For example, by such an approach directly integral flanges can be molded to the workpiece and both on

End region as well as in any position along the axial extent. The axial movement of a workpiece or only one workpiece part laterally from a plasticized region can be done for example by movement of a spindle or a lathe chuck, in which the workpiece is received.

Of course, such accumulations of material can be created several times axially spaced on a workpiece. It may then also be provided that a material accumulation projecting in the radial direction is displaced by axial movement of at least one part of a workpiece onto another accumulation of material projecting in the radial direction, if a region located between the accumulations of material has previously been plasticized, in particular by friction. Thus, the accumulations of material can be combined and the amount of aggregated material increased, e.g. for subsequent

Forming steps or other subsequent processing.

Advantageously, the invention also provides the possibility of holding a material accumulation arranged laterally next to the tool in the axial direction and protruding in the radial direction by movement of the tool in the axial and / or radial direction at least partially by friction in the plasticized state or again after cooling to plasticize and then further deform, in particular to form a further axially and / or radially extended area.

In general, the inventive method has the advantage that it can be stopped at any time and - even after cooling - can be resumed.

In an exemplary application, it may be provided that plasticized by axial and / or radial movement of a tool and repositioning

Quantities of material, e.g. cylindrical, conical, convex or concave

Generate lateral surface or freeform surface. Such a surface, in particular, which extends axially, for example, can also be generated so that it connects at least two previously created axially adjacent upstanding material accumulations in the radial direction. Thus, by multiple generation of material accumulations standing up in the radial direction and their at least partial deformation in the axial direction, at least one chamber rotating in the direction of rotation can be arranged inside one particular one

rotationally symmetrical workpiece are generated. By multiple

Application of this Umformungsprinzips in the axial and / or radial direction and several rotating in the direction of rotation chambers can be generated, which are arranged axially and / or radially side by side within the workpiece.

Here, the method has particular advantages over the prior art, since such closed chambers, in particular those without inner webs can not be created by other common methods, in particular not by casting or machining.

It can be provided that a generated by displacement of the plasticized material radially and / or axially open profile shape of the workpiece is filled before closing by further displacement of plasticized material with a filler / filler.

A shaping can also take place in this method in that plasticized material of the at least one workpiece is pushed by movement of a tool to a shape-defining counter bearing. Such an abutment may e.g. as a negative form of the later desired form

be educated. The anvil can rotate with the workpiece

be formed or rotatably to be, which forms the advantage that over the entire surface of the later desired shape frictional forces act and so the material is kept plasticized until the end of the molding process.

In order to achieve shape designs that differ from a rotational symmetry, it may be provided in a development that the movement of a Tools, in particular a radial and / or tangential and / or axial movement of a tool as a function of the angular position of the at least one rotating workpiece takes place. For example, so eccentric shapes or transformations of a workpiece can be made, such as cams. In this case, eccentric molds are possible with the method, for example, hollow cams, which for example in engine construction to significant

Weight savings can result.

Overall, it can be provided in this method, the surface quality of the formed workpiece by the relative movement speed between the workpiece and the tool, in particular by the

Set rotational speed of the workpiece to a desired level.

Furthermore, it may also be provided that the process parameters, e.g. To monitor the speed of movement, in particular web speed during rotation and / or the pressure forces when hiring the tool to the workpiece and or the temperature of the workpiece in the friction zone. For this purpose, appropriate sensors may be provided for receiving the relevant measured variable, the signal of which is subjected to an evaluation, and based on the regulation of one or more process parameters.

In a preferred embodiment, it may be provided to metrologically detect and analyze sound produced during the grinding process, in particular with respect to its spectral frequency components and / or

Intensities, in particular in dependence thereon, the process parameters, such as temperature and / or friction force and / or travel paths and / or

To regulate and / or control rotational speed, etc. This may be acoustic or airborne sound or structure-borne noise. For it has been shown that below one reached

Plastification The acoustic emission is different in terms of spectrum and intensity than in a sufficient plasticization or at too high a temperature. In particular rotation speed or generally the Relative speed hiss tool and workpiece and / or the contact force can therefore be controlled depending on the spectrum and intensity of the sound.

It is also possible to measure the temperature without contact, e.g.

pyrometric in order to achieve optimum control of the operating parameters.

To achieve a partially different plasticization of the material, a local cooling or heating, in particular by a fluid flow, e.g. Air flow, which locally counteracts or supports the heating by the friction.

Furthermore, local application of the rubbing, plasticizing and shaping of the plasticized material can also result in a local grain change.

in particular grain refining and / or hardness change in the material are generated. There is such a possibility, the scope of this invention changed areas of a workpiece subsequently another, especially different

Undergo forming.

Embodiments of the invention are in the following figures

shown. Show it:

Fig.1: An application of the deformation by axial movement of a

Tool relative to the workpiece

Fig. 2: Forming stages in radial and axial movement of a not

illustrated tool.

Fig. 3: The sound emission during processing

FIG. 1 shows two different applications of the method in the partial illustrations a to c and d to f. According to FIG. 1 a), a hollow cylinder 1 is set in rotation as a workpiece and a tool 2, here as a disk with a central projection, is set in the axial direction against the end face of the workpiece 1, as FIG. 2 shows. Due to the friction creates a front side of a zone 3 of plasticized material due to

Temperature increase. By an axially acting force F along or parallel to the axis of rotation 4, a radially upstanding accumulation of material 6 is achieved, which if necessary also processed with a further radially employed tool 5, i. can be shaped, e.g. to form a flange 6. The tool 5 may be formed in this case, as well as with general validity as a role, in particular braked or driven roller.

FIG. 1 d) shows, as a rotated workpiece 1, a plate to which a tool 2 is set in the axial direction. Here, the plate between two rotational receptacles 7a, 7b be clamped, the right-hand receptacle 7b is a negative mold and thus a form-defining abutment 12. By rubbing a rotating plasticized area 3 is generated, wherein this material is pushed by axial movement on the female mold 7b and 12 respectively and applies to the outside of the negative mold, so that the material receives exactly this shape.

Figure 2 shows transformation stages in the forming of a cylindrical

Hollow profile as a workpiece 1, which is also set in rotation, e.g. in a lathe.

At the marked point 8, a tool, not shown, is attached to the workpiece 1 in the radial direction, which produces by rubbing at the point 8 an annular zone of plasticized material at this point. It will now be the two left and right of the tool, or from the friction zone

arranged part 1a and 1b of the workpiece simultaneously or sequentially in the axial direction according to the arrows moves toward each other, so that the plasticized material is compressed in the friction zone and evades in the radial direction, namely both left and right side of the tool and forms in each case in the radial direction upstanding accumulations of material 9. By adjusting the tool in the axial direction of each of these two

Clusters 9, especially only in an upper, i. radially outward area each of this area is plasticized by friction and can in

Direction to the adjacent cluster 9 to be moved. It thus forms a closed cylindrical surface 10 around the original hollow cylindrical workpiece 1 around, so that in the workpiece 1, an annular circumferential chamber 11 is formed. Such chambers can also be created several times both axially and radially lying side by side.

FIG. 3 shows a realized process monitoring. In the upper area is the e.g. shown with a microphone recorded sound intensity versus time. It is recognizable that at the beginning of the rubbing, if still no sufficient

Plastification or high enough temperature is achieved

Acoustic emission is recorded here in the area a). The associated

Frequency spectrum, e.g. can be calculated by Fourier transformation shows for this case, especially in the high-frequency range, a significantly different form of the spectrum, in comparison to the range b), if sufficient plasticization was achieved. Accordingly, these two ranges can be distinguished acoustically well, so that a regulation of the process parameters on the basis of the sound emission, in particular as a function of the intensity and / or the frequency components, can take place. Also, the range c) is outside optimal conditions and produces high-intensity spectral peaks in the frequency spectrum.

Claims

claims

1. A method for processing at least one workpiece (1) by means of

at least one tool (2), in which at least one workpiece (1) and at least one tool (2) are brought into frictional contact and by a relative movement between the at least one workpiece (1) and the at least one tool (1) in the friction zone ( 3) and / or in the friction zone (3) surrounding areas, a temperature increase of the material of the at least one workpiece (1) at least until the plasticization of the

Material of the at least one workpiece (1) is generated, characterized in that plasticized material of the at least one

Workpiece (1), in particular during the continuous friction movement, by moving the at least one tool (2) relative to the at least one workpiece (1) on the at least one workpiece (1) is repositioned to build a shape of the at least locally deviating from the original workpiece shape at least one workpiece (1).

2. The method according to claim 1, characterized in that by the

Movement one of an inner and / or outer surface of the at least one workpiece (1) at least locally projecting

Material accumulation (9) is generated, in particular in the nature of a relative to surrounding areas increased at least local accumulation of material (9).

3. The method according to any one of the preceding claims, characterized in that for generating a friction movement, the at least one workpiece (1) and / or the at least one tool (2) is moved, in particular about an axis of rotation (4) is rotated at least partially, wherein by a relative movement between the workpiece (1) and tool (2) a tool (2) to a workpiece (1) is made radially and / or tangentially and / or axially.

4. The method according to claim 3, characterized in that the at least one workpiece (1) about an axis of rotation (4) is rotated, in particular continuously rotating or oscillating over a predetermined angle.

5. The method according to claim 4, characterized in that the at least one tool (2) to the at least one rotating workpiece (1) is made axially and / or radially and / or tangentially and plasticized material of the workpiece (1) at least partially into one Area in Anstellrichtung before the at least one tool (2) and / or at least partially in a range in Anstellrichtung next to the at least one tool (2) is displaced.

6. The method according to any one of the preceding claims 3 to 5, characterized

characterized in that by moving the axially laterally of the at least one tool (2) arranged rotating part (1a, 1b) of the at least one workpiece (1) in the axial direction of a tool (2) to an axially laterally adjacent to the Tool (2) arranged and upstanding in the radial direction accumulation of material (9) is generated.

7. The method according to claim 6, characterized in that a radially upstanding material accumulation (9) is plasticized by movement of the at least one tool (2) in the axial and / or radial direction at least partially by friction or remains and / or further deformed , in particular for the formation of a further axially and / or radially extended region, or that a radially accumulating material accumulation (9) by axial movement of at least one part (1 a, 1b) of a workpiece (1) to another upstanding in the radial direction

Material accumulation (9) is pushed, with a between the

Material accumulations (9) lying area was previously plasticized.

8. The method according to any one of the preceding claims, characterized in that by axial and / or radial movement of a tool (2) and repositioning of plasticized amounts of material, a lateral surface (10), in particular a cylindrical, conical, concave or convex lateral surface (10) is generated in particular, which connects at least two adjacent radially extending material accumulations (9).

9. The method according to any one of the preceding claims, characterized in that by multiple generation of protruding in the radial direction material accumulations (9) and their at least partial deformation in the axial and / or radial direction at least one rotating in the direction of rotation chamber (11) within at least one workpiece (1), in particular within at least one rotationally symmetrical workpiece (1) is generated.

10. The method according to claim 9, characterized in that a plurality of rotating in the direction of rotation chambers (1) are generated, which are arranged axially and / or radially side by side / are.

11.Verfahren according to any one of the preceding claims, characterized in that a generated by displacement of the plasticized material radially and / or axially open profile shape of the workpiece (1) before closing by further displacement of plasticized material with a filler /

Filling material is filled.

12. The method according to any one of the preceding claims, characterized in that plasticized material of the at least one workpiece (1) by moving a tool (2) is pushed to a form-defining abutment (12).

13. The method according to any one of the preceding claims, characterized in that the radial and / or axial movement of a tool (2) in

Dependence of the angular position of the at least one rotating

Workpiece (1) takes place, in particular for producing eccentric shapes of the at least one workpiece (1).

H.Verfahren according to any one of the preceding claims, characterized in that for monitoring process parameters, in particular for

Monitoring the temperature of the material of at least one

Workpiece (1) the sound resulting from the rubbing Breiten is metrologically recorded and analyzed, in particular with regard to its spectral frequency components and intensities.

15. The method according to any one of the preceding claims, characterized in that for monitoring process parameters axial and / or radial travel paths of tool (2) and / or workpiece (1) or between the workpiece (1) and tool (2) acting forces or on Workpiece (1) prevailing temperatures are detected and evaluated.

16. The method according to any one of the preceding claims, characterized in that to achieve partially different plasticization of

Material local cooling or heating is carried out in particular by a fluid flow locally counteracts the heating by the friction or supports them.

17. The method according to any one of the preceding claims, characterized in that by the local application of the grinding, plasticizing and forming the plasticized material, a local grain change,

in particular grain refining and / or hardness change in the material is produced, in particular according to which the changed regions are subjected to a further, in particular different, shaping.