WO2012000986A1

WO2012000986A1 - Cutting tool, in particular cutting wheels, and method for producing the same using an inclined laser beam

Info

Publication number: WO2012000986A1
Application number: PCT/EP2011/060805
Authority: WO
Inventors: Heinrich Ostendarp; Otto Abich; Siegfried Piontek
Original assignee: Bohle Ag
Priority date: 2010-06-28
Filing date: 2011-06-28
Publication date: 2012-01-05
Also published as: DE102010017625A1

Abstract

The invention relates to a cutting tool, in particular cutting wheels, and a method for producing the same. For the purposes of smoothing the surfaces (6a, 6b) and of sharpening the cutting edge (4), use is made of a method in which at least one side surface, at least in a region adjacent to the cutting edge (4), is subjected to the action of a laser beam, and in which the laser beam is oriented at a shallow angle to the surface of the cutting edge (4). It is thus possible to produce cutting tools with improved properties which satisfy at least one of the following parameters: rectilinear deviation of less than 2 μm, in particular of less than 1 μm, cutting-edge undulation of less than 0.5 μm, in particular of less than 0.3 μm, negative cutting-edge blunting and/or starting distance of the cutting-edge rounding of less than 4 μm, in particular of less than 2 μm.

Description

CUTTING TOOL, ESPECIALLY CUTTING WHEELS, AND METHOD FOR THE PRODUCTION THEREOF BY USING A TILTED LASER BEAM

The invention relates to a cutting tool, in particular cutting wheel and a method for its production.

Cutting tools and cutting wheels of the type in question are used in particular for cutting or scoring brittle materials, such as ceramic and / or glass. To increase performance in such processing and

Cutting processes are defined and preferably reproducible along the edge of the tool

Aspired edge geometries. In particular, it is difficult to produce a uniformly sharp geometry.

Previously known from the prior art

Cutting wheels strive for a smooth cutting edge. This allows smooth cutting edges, especially in

Glass workpieces are achieved.

The patent EP 0 773 194 Bl discloses a

A cutting wheel of polycrystalline material, in particular of diamond material, provided with a tooth structure along the circumference of the cutting wheel. With this embodiment of the cutting wheel is to improve the

Cutting result in particular a slipping of the

Schneidrädchens be prevented on the surface of the cutting material during the rolling caused during the cutting process. A method for producing a cutting wheel with a tooth structure is disclosed in the patent application EP 1 666 426 A1, according to which the tooth structure by means of a

Grinding tool is ground into the cutting edge of the cutting wheel. A disadvantage of these cutting wheels known from the prior art, however, is that the cracks generated by the cutting process in the material to be cut too

Break edges with an edge quality that is not always optimal for today's applications.

WO 2009/036742 discloses a cutting wheel with a peripheral structure of protruding teeth and

intervening interdental spaces, which show improved cutting behavior. WO 2009/036743 discloses a

Method for producing such a cutting wheel, in which by means of a pulsed laser beam, the surface of a prefabricated cutting wheel without tooth structure on

predetermined locations along the cutting edge and in the area adjacent to the cutting edge region of the side surfaces material is removed. In this structuring of the

Laser beam substantially at right angles to

Side surface applied to the most intense possible

To achieve material removal and to reduce the production times.

In the manufacture of cutting wheels by means of

Grinding or laser machining generally has the problem of rounding or local breakouts just along the cutting edge and adjacent thereto

Side faces. These roundings or outbreaks are locally different due to the manufacturing process. In the manufacture of cutting wheels for scribing glass, some problems are particular

Requirements for the cutting edge. Will with some

Applications with a reproducible but deliberately rough cut - combined with local breakouts along the cutting edge - are sought in other applications for an ideally uniform and sharp cutting edge. such

Applications exist for example in cutting wheels for scribing thin glass, for example, in the

Display industry is used. The invention therefore preferably relates to cutting tools and in particular

Cutter wheels for the latter application. Due to the grinding process or by the

Laser processing occurs in the prefabricated cutting wheels a rounding already in one compared to

Penetration depth of the cutting wheel relatively large distance from the cutting edge, in the context of this description

"Starting distance cutting edge rounding" is called.

The real central cutting edge thereby recedes from the approximated central cutting edge by a distance which in the context of this description is referred to as

"Cutting edge blunting" is called.

Due to the irregularity of the cut or the

Laser processing, the straightness deviation and the cutting edge ripple are quite high.

Thus, the present invention is based on the technical problem already prefabricated in the macrogeometry To treat side surfaces of a cutting tool, in particular a cutting wheel, and a cutting edge formed by the side surfaces so that the sharpest possible and uniform surfaces having cutting edge.

The above-indicated technical problem is inventively solved by a method for smoothing a surface of a prefabricated cutting tool, in particular cutting wheel with two side surfaces which extend at an angle to each other and form a cutting edge, wherein at least one side surface at least in one of

Cutting edge adjacent area is exposed to a laser beam and in which the laser beam is aligned at a shallow angle to the surface of the side edge.

The inventive method can therefore also as

Laser grinding or laser smoothing are called. Under a laser beam becomes a directed beam

Electromagnetic radiation understood, the

Wavelength does not necessarily have to be in the visible range, but also wavelengths in the infrared or ultraviolet range can be used. The starting point for the present invention are the previously described cutting wheels for working brittle materials, such as ceramic and / or glass. Nevertheless, the invention relates generally to cutting tools, which require a high degree of precision

Cutting surfaces and the cutting edges for cutting any materials arrives. Thus, the invention described below can also be applied to tools such as knives, saws, drills, Milling tools, inserts and similar tools

Find application. For all tools, the

Machining effect by a sharp-edged cutting edge, even if the process itself is not in all cases

Cutting, but as sawing, drilling, machining or turning / milling is called. The following description of the invention is based on the exemplary application

Cutting wheels for working brittle materials, such as ceramic and / or glass, but the invention is not limited to this application.

According to the invention, it has been recognized to remove material by means of a suitable beam guidance in such a way that, in comparison with the prior art, sharper and more uniform

Cutting edges can be produced. These are places with large Schneidabantenabundungen as well as places with

slight rounding be transferred to about the same edge geometry. For this purpose, bumps are smoothed on the two side surfaces of the prefabricated cutting wheel and on the cutting edge, especially in areas with large

Cutting edge rounding targeted less material removed.

The effect of smoothing out unevennesses on the two side surfaces and deliberately removing less material at the cutting edge, particularly in areas with large cutting edge roundings, is achieved by guiding the laser beam at a shallow angle, ie relatively tangentially to the surface of the side surfaces of the cutting wheel , Projecting tips on the side surfaces thus provide a large surface for the laser radiation,

recessed areas and in particular rounding on the cutting edge a smaller attack surface. This occurs the effect of smoothing unevenness on the side surfaces and sharpening of the cutting edge.

In the present case, a low angle is understood to mean angles in an angular range of less than 45 °, preferably of 5 ° to 45 °, in particular 10 ° to 30 °. The exact setting of the angle depends on the boundary conditions such as material, size of the material removal to be achieved, laser power and length, cutting angle and / or radius of the

Cutting wheel off.

The tilt of the incoming laser beam to

Side surface of the cutting wheel should therefore be adjusted within an angular range in order to ensure the success of the invention. This will be the focus in the

Depending on the angle of incidence, the longitudinal axis is enlarged approximately 2-fold to 12-fold. In order to achieve a sufficient intensity for a sufficient material removal, is

preferably made a beam expansion, which reduces the focus diameter in the subsequent focusing, here for example to about 10 to 50 ym.

The method can lead to an improved geometry of the cutting edge just by the application on a side surface. However, it is preferred that the invention

Apply method on both sides.

The method is preferably carried out so that the

Laser beam is focused on the cutting edge adjacent area of the side surfaces. As a result, a sufficient removal rate is applied to the cutting wheel in the area important for the quality of the cutting edge. At the same time on the side surfaces at a greater distance from the cutting edge only a smaller and smaller with increasing distance, eventually not sufficient

Intensity available.

The method described above can be performed with different laser sources, depending on the application and material of the cutting tool or Schneidrädchens

can be different. It has proven to be advantageous to use a pulsed laser.

The pulsed laser beam has the advantage that within each laser pulse a sufficient power density can be achieved. By using a pulsed laser, the side surface of the cutting wheel is only detected selectively and only for a short period of time in each case in the area covered by the focus. However, can be achieved by a suitable process management that the entire machined portions of the side surfaces largely

be applied uniformly with laser light.

However, the invention is not based on the application of a

limited to pulsed laser. Thus, it is possible to use a continuous wave laser for materials that require less laser power for removing material. In this case, a particularly uniform processing is achieved, since no single-spaced laser pulses in the side surface and the cutting edge by individual time-spaced

can arise. Preferably, during the application of the

Laser beam, regardless of whether the laser beam is pulsed or unpulsed, the cutting wheel so rotated so that essentially the area of the side surface to be machined is exposed to the laser beam. For this purpose, the cutting wheel can be rotated continuously or in separate steps.

Furthermore, during laser processing, the relative position of the laser focus to the side surface can be adjusted continuously or in individual steps. By the

Adjusting the laser beam relative to the side surface ensures that a portion of the side surface which is wider than the focal length, successively with the

Laser beam is applied.

When changing the relative position of the laser beam on the side surface, there are various possibilities as to whether and how the alignment of the laser beam is tracked. For the respective tracking suitable, known per se optics are used. First, it is possible that the laser beam parallel to the propagation direction while maintaining the angle to

Side surface is adjusted. By the same

Angular alignment of the laser beam is achieved a substantially uniform processing of the side surface, even if some areas of the side surfaces are less in focus than others, if the focus is not tracked.

Alternatively, the angle of the laser beam during the adjustment of the laser beam relative to the side surface can be changed. For example, the angle in the

Area of the cutting edge less, that is flatter than in the Be set areas that are spaced from the cutting edge.

In addition to adjusting the beam alignment of the

Laser beam can be the relative distance of the focus to the

Side area either maintained or changed. If in each case the focus distance tracked and maintained substantially the same, then this is also a

achieved more even processing. Will, however, the

Focus distance changed or not tracked, so the effect of the laser beam can be changed to different areas of the side surface. For example, it is thus possible to increase the intensity of the laser beam in the region of the cutting edge and in the direction of a larger one

Distance to reduce the cutting edge.

The machining of the surface with a stepwise or continuous adjustment of the position of the focus relative to the side surface of the cutting wheel can advantageously during a continuous rotation of the

Cutting wheels are performed. As a result, either separate tracks are processed or the laser beam drives a spiral curve from the outside, so starting from a larger

Distance to the cutting edge over the cutting edge to the

Cutting edge or beyond this. The track offset should be chosen so that with one side surface

a sufficient number of tracks (revolutions) are traveled to achieve a fully overlapping processing of the side surface. The laser beam can be approximately on the

Cutting edge to be focused here to a maximum

To have power density of the laser radiation. One of the above Changes in the beam guidance already described can also be selected during machining.

The above-indicated technical problem is solved according to the invention by cutting tools and in particular cutting wheels, which differ by different independent features from the prior art. These various features arise for the first time by the application of the method according to the invention, but can also be achieved by other manufacturing methods.

Furthermore, for all features of the cutting tool described below, the parameter values are determined from a three-dimensional measurement of the spatial profile of a section of the cutting edge. The measuring range has, for example, and the invention not

limiting a length in the direction of the cutting edge of about 500 ym and a width across the cutting edge on both sides of about 250ym, so a total of about 500 ym on. For example, the white light interferometer can be used for this, which can determine the spatial course of the side surfaces and the cutting edge with an accuracy of approximately 1 μm. Is preferably the confocal

Microscopy used, the lateral resolution is depending on the lens about lym or less than lym, the

In contrast, depth resolution is below lym. From the data of a measurement can then be formed for any given sections of the side surfaces and / or the cutting edge, in particular line or area wise, the real course and mean values, which then brought into relation with each other and

Characteristics of the cutting tool are derived. The invention first relates to a cutting tool,

especially cutting wheels for cutting brittle

Materials, such as ceramic and / or glass, with two at a predetermined angle to each other

Side surfaces and with one through the side surfaces

formed cutting edge, which is characterized in that the side surfaces have an average cutting angle to each other, which is determined by the angle of two sections which are bounded on both sides of the cutting edge of the cutting edge to a first distance to the cutting edge, and that the angle between two sections of the

Side surfaces bounded in a range between a second distance near the cutting edge and a third distance smaller than the first distance is smaller than the average cutting angle.

In other words, the two are lost

Sections of the side surfaces in the direct vicinity of the cutting edge steeper than the average cutting angle

to each other, which is determined over a wider range. Since it first arrives at the foremost portion of the cutting edge when the cutting edge penetrates, it is

advantageous if this area is steeper so sharper than the adjoining part of the side surfaces.

For example, when glass processing penetrates with a

Slicing the cutting edge between 10 ym and 30ym, depending on the glass thickness on both sides of the cutting edge in the glass surface. The resulting area where the glass undergoes damage is also called scratch width. If now in particular in this width the

Side surfaces at a more acute angle than the rest of the side surfaces converge, then this affects positive for the quality of the cutting process and for the life of the cutting tool.

The invention also relates to a cutting tool, in particular cutting wheel for cutting brittle materials,

For example, ceramic and / or glass, with two at a predetermined angle to each other extending side surfaces and with a cutting edge formed by the side surfaces, which is characterized in that the cutting edge has a straightness deviation of less than 2 ym, in particular less than 1 ym.

For the determination of the magnitude of the straightness deviation, the measured spatial progression of the cutting edge is compared with an interpolated linear course of the cutting edge.

For this purpose, the section of the highest elevation, ie the largest elevation values, is first determined on the basis of the line of the recorded measurement data running transversely to the cutting edge, and its center is defined as the position of the cutting edge in this line. From this results from the measurement data over a length of approx. 500 ym the real course of the

Cutting edge. From these an ideal cutting line

fluctuating values, an interpolated, ie smoothed, linear curve is first determined. Then, for each measured value of the course of the cutting edge, the distance to the interpolated linear course is calculated and the

Standard deviation of the real progression from the interpolated curve then represents the value of the straight-line deviation. The stated values according to the invention of less than 2 μm and in particular less than 1 μm for the straightness deviation have the advantage that the cutting line of such a tool runs so straight that the disturbance introduced during cutting into the material of the workpiece to be cut extends along that contained in the material Structures can spread. Thus, the cutting, so the

Separating the material can be done easier and with less force. The precision of the cutting is thereby also improved.

The invention further relates to a cutting tool,

especially cutting wheels for cutting brittle

Side surfaces and with one through the side surfaces

formed cutting edge, characterized in that the cutting edge has a cutting edge waviness of less than 0.5 ym, in particular less than 0.3 ym.

For the determination of the value of the cutting edge waviness, the measured spatial progression of the cutting edge is compared with a circular arc approximated to an interpolated course of the cutting edge.

For this purpose, the section of the highest elevation, ie the largest elevation values, is first determined on the basis of the line of the recorded measurement data running in each transverse to the cutting edge. This results, for example, over a length of about 500 ym, the real course of the cutting edge as a result of

Height values. These height values, which fluctuate radially around an ideal circular-arc-shaped cutting line, are initially determined the course of the cutting edge with the slightest error approximated by a circular cutout. At the interpolated

Course is - in the case of a round cutting tool like a cutting wheel - approximated a circular arc, which represents the ideal radial course of the cutting edge. In straight cutting edges, however, a straight line is approximated to the interpolated course. Thereafter, for each measured height value of the radial path of the cutting edge, the distance to the approximated ideal path is calculated, and the standard deviation of the real path from the approximate path then represents the value of the cutting edge waviness.

The indicated values of the cutting edge waviness of less than 0.5 μm, in particular of less than 0.3 μm, have the advantage that the cutting edge deviates so little from an ideal cutting edge in the direction transverse to the snow direction that during the cutting process the cutting edge is uniform can penetrate the workpiece to be cut. For a cutting wheel this means that the cutting edge deviates very little from an ideal arc.

The invention also relates to a cutting tool,

especially cutting wheels for cutting brittle

Side surfaces and with one through the side surfaces

formed cutting edge, which is characterized in that the cutting edge has a negative Schneidkantenabuntpfung.

The cutting edge truncation represents a measure of how far the average of the measured data in radial Direction determined maximum values of the real cutting edge in the middle deviates from the radial course of the central cutting edge. The course of the mean cutting edge results from the intersection of the two averaged spatial

Gradients of the side surfaces that form the cutting edge. The value of the cutting edge blunting is positive when the real cutting edge is below the middle cutting edge, that is blunted. The value is negative if the real cutting edge runs above the middle cutting edge, that is, protrudes further. It is obvious that one

negative cutting edge blunting for a better

Cutting result results because the cutting edge causes the first contact with the surface of the workpiece to be cut at a more acute angle.

The invention further relates to a cutting tool, in particular cutting wheels for cutting brittle

Side surfaces and with one through the side surfaces

formed cutting edge, which is characterized in that the cutting edge a starting distance of

Cutting edge rounding of less than 4 ym, in particular less than 2 ym.

The starting distance of the cutting edge rounding is determined by starting from the cutting edge in the case of the real average over the measuring range and, depending on the distance to this left and right, determining the local slope. From the slope progression defined in this way, depending on the distance to the cutting edge, the local

Angle course determined. From this, starting from the Cutting edge determines the distance at which the angle for the first time only 1 degree above the over the entire

Side edges determined value lies. This distance value is the starting distance of the cutting edge rounding. In other words, starting at the starting distance from the cutting edge, the rounding of the cutting edge begins. The position of the

Starting distance can also be optionally determined on both sides and the mean then used as the starting distance.

The smaller the value of the starting distance of the

Cutting edge rounding is the sharper it is

Cutting edge formed. At each cutting edge, there is a transition between the two side surfaces, where at one point the cutting angle is 180 °. Since this angle of 180 ° can not be detected metrologically, the starting distance is defined as a measure to characterize the extent of the rounding of the cutting edge. However, the narrower the transition region is formed, the sharper the cutting edge.

The described cutting tool according to the invention,

in particular the cutting wheel has a starting distance of less than 4 ym and in particular less than 2 ym. Thus, the area of the rounding of the cutting edge represents only a small proportion of the above-mentioned scribe width. The advantageous effect is thus further improved at values of less than 2 ym. The values of the starting distance to be achieved also depend on the material structure of the material of the cutting tool. The previously described embodiments of the invention have been described for a continuous cutting edge.

On the other hand, it is also possible that the cutting edge is provided with a sequence of teeth and interdental spaces and that the properties of the cutting edge explained above apply at least to the teeth.

Generally applies to cutting, especially for cutting wheel, that at shallow, ie blunt cutting angles, the ripple less than at acute cutting angles fails. In contrast, the straightness deviation is greater at blunt cutting angles. Conversely, with sharp cutting angles, the waviness is greater and the straightness deviation is lower. The inventive method therefore has an advantageous effect on the design of cutting wheels for scribing

Thin glasses, as they are needed in the display production. Because with this application, cutting wheels with pointed cutting angles (eg 105-125 ° cutting angle) with low penetration depth into the thin glass to be scratched

used. The inventive method therefore leads to the improvement of these cutting wheels over the prior art, just by the ripple in these

Cutting wheel is reduced, at the same time the straightness is improved.

The invention is based on

Embodiments explained, reference being made to the drawing. In the drawing show

1 is a cutting wheel in a side view, Fig. 2 is a schematic diagram of a first

Embodiment of an inventive

Method, Fig. 3 is a schematic diagram of a second

Embodiment of an inventive

Method,

4 is a schematic diagram for illustrating the

Carrying out the method according to the invention,

Fig. 5 is a schematic diagram for a third

Embodiment of an inventive

Method,

Fig. 6 is an input image of a three-dimensional

Height structure of a cutting wheel,

7 is a grayscale image showing deviations of the measured surface from an ideal one

Surface of a prefabricated cutting wheel known from the prior art,

8 is a grayscale image showing deviations of the measured surface from an ideal one

Surface of a cutting wheel produced by the method according to the invention,

9 shows diagrams for explaining the parameter of

line deviation, 10 is a diagram for explaining the parameter of the Sehneidkantenwelligkeit,

Fig. 11 is another diagram for explaining the

Parameters of the cutting edge waviness for a manufactured by the inventive method

Cutting wheels,

Fig. 12 is a diagram for explaining the parameter of

Cutter blunting for a prefabricated cutting wheel known from the prior art,

FIG. 13 is a diagram for explaining the parameter of FIG

Cutting box stump for one with the

produced according to the invention

Cutting wheels,

14 is a diagram for explaining the parameter of FIG

Starting distance of the cutting edge rounding for a prefabricated, known from the prior art

Cutting wheels,

FIG. 15 is a diagram for explaining the parameter of FIG

Starting distance of the cutting edge rounding for a produced by the method according to the invention

Cutting wheel.

FIG. 1 shows a schematic side view

Cutting wheel 2 with along the entire circumference

extending cutting edge 4. The cutting wheel 2 has in this example rotational symmetry with respect to an axis A. which is used as the rotation axis of the cutting wheel 2 during the cutting operation.

The cutting edge 4 is of two wedge-shaped in axial cross-section side surfaces 6a, 6b, respectively

Truncated cone shape, formed. The side surfaces 6a, 6b include a cutting edge angle X between them. The cutting edge angle X may be, for example 135 ° in the cutting wheel of FIG. The cutting wheel 2 may further be made of a polycrystalline material, in particular polycrystalline diamond material or of a hard metal, for example tungsten carbide.

Due to the convergence of the side surfaces 6a, 6b, the cutting edge 4 also forms a peripheral line, which in the

Essentially arranged a plane 8 in this representation perpendicular to the plane considered and therefore spanned as a line. The plane 8 of the circumferential line in the present case runs perpendicular to the cutting wheel axis A.

The cutting edge 4 shown in Fig. 1 is formed continuously, the cutting edge 4 thus extends along a line and can thus at any angular position in the

Have substantially the same effect on the material to be cut. In addition, it is known from the prior art mentioned that the cutting edge can also be formed with teeth and interdental spaces, so that a regular or irregular tooth structure is given.

In particular, the up to the outer diameter of the cutting wheel 2 protruding teeth must have the best possible cutting edge, since the teeth represent the essential elements for cutting the material. In addition, the Interdental spaces have their own, slightly recessed cutting edge, provided that they penetrate during the cutting process in addition to the teeth in the material. Fig. 2 shows a schematic representation of a

Embodiment of a method according to the invention. In the diagram, a triangle-like line is drawn in micrometer resolution, which shows the irregular course of the

Surface of a prefabricated cutting wheel in section shows.

Coming from diagonally lower right is the course of a

Laser beam shown. The middle dotted line 10 shows the axis of the laser beam, while the slightly curved lines 12 and 14 illustrate the waist of the focus F of the laser beam. The focus of the laser beam is in the area of the cutting edge 4, ie at the upper end of the triangle-like line. In this position meets the

Laser beam only halfway to the surface of the

Cutting wheel. Because the axis 10 of the laser beam only affects the upper end of the cutting edge 4, so that the upper half of the laser beam emits beyond the cutting edge. Therefore, the upper line 12 is shown throughout, while the lower line 10 left of the cutting edge 4 is shown only in dashed lines. There is of course due to the shading by the cutting edge 4 no light of the

Laser beam (except by diffraction) on.

The axis of the laser beam is opposite the right one

Side surface 6 a of the cutting wheel inclined, wherein the

Slope angle is flat and less than 45 °, in particular between 5 ° and 45 ° can be adjusted. In the Representation of FIG. 2 is an example of an angle ι of slightly more than 15 ° have been chosen.

In the plan view in Fig. 2 above on the

Cutting wheel in the region of the cutting edge 4 is the relative position of the focus F to recognize as an elongated oval. On the side edge 6a shown on the right, the light spot can be seen on the surface. On the left of the cutting edge 4, the oval is shown in dashed lines to the symmetrical

Course of the focus F, but of course the laser beam does not strike the left side surface 6b.

The oval is all the more stretched, the shallower the angle of the axis of the laser beam is set to the surface. This distributes the focus of the laser beam

concentrated light output on a larger surface.

Therefore, the laser beam must not be too low

Angle hit the surface, otherwise not enough light energy density is applied to the surface in order to remove material.

When the focus of the laser beam is positioned in the area of the cutting edge as in FIG. 2, the effect is that in the region of the cutting edge, approximately over half a focal length, the entry of light energy is lower overall than in areas further away from the cutting edge 4 when the laser beam is positioned and focused there. Presumably by this effect and the so

Connected different removal of the material of the side surface 6a, there is a special design of the cutting edge 4. Because this has directly to the

Cutting edge 4 immediately adjacent area a more acute cutting angle as calculated over a larger area of the side surface 6a, 6b mean cutting angle. This feature will be further explained below. This effect is probably based on the described

different energy input, but it can also occur by diffraction effects on the cutting edge 4 or by another not yet recognized effect.

The angle of incidence may but for the inventive

Procedure should not be too steep. Because the desired effect of the method is that protruding tips on the side surfaces a larger attack surface for the

Laser radiation as recessed areas and in particular provide rounding at the cutting edge. As a result, the effect of smoothing unevenness on the side surfaces and sharpening the cutting edge occurs. If the angle is set too large, the laser light falls too steeply on the side surface and the smoothing and sharpening effect is reduced. Fig. 3 shows another constellation. Here is the

Laser beam not on the area of the side edge 4

focused, but at a distance. In addition, the axis 10 of the laser beam at an angle 2 of about 30 ° to the side surface 6a.

By varying the angle, the distance of the focus to the cutting edge and the distance of the focus relative to

Surface of the side surface, the inventive

Procedures are varied. In particular, areas of the side surface 6a that are larger than the extent of the focus of the laser beam can be processed by the

Positioning of the laser beam relative to the cutting edge and is changed to the side surface to be machined 6a, 6b. If the cutting wheel is rotated at the same time, the entire area of the side surface to be machined can be smoothed in one process step.

4 shows a schematic representation of a further exemplary embodiment of a method according to the invention, in which the oval-shaped impingement region of the focus of the laser beam is positioned in separate tracks on the side surface 6a during the rotation of the cutting wheel.

The spaced tracks are shown with the vertical arrows and numbered from n-4 to n + 2. The laser beam is applied sequentially to each of these tracks

set, wherein the track n comes closest to the cutting edge, ideally coincides with this substantially within the setting accuracy. Since the oval formed by the focus of the laser beam in each track

Processing spots a greater longitudinal extent than that

Have spacing between the tracks overlap the processing areas of the individual tracks, so that the overlapping positioning of the focus results in a comprehensive coverage on the side surface.

In the embodiment shown in Fig. 4, the oval focus has a width of about 20 ym and a length of about 120 ym, so a to the approximately 6 times greater length. If the tracks are at a distance of approx. 10-20 ym, then the entire side surface is lowered

Surface areas repeatedly and therefore processed very evenly, so smoothed or ground with the laser. Fig. 5 shows another example of a cutting wheel, which is processed by the method according to the invention. in the

Contrary to FIGS. 2 and 3, the cutting wheel in the illustrated cross-section in the region of the cutting edge 4 ', the side surface 6a a recessed paragraph 20a and the side surface 6b on a shoulder 20b. The step leads to a set-back structure with a width which is indicated by the double arrow B and which has already been referred to above as the interdental space. Thus, Fig. 2 can be understood as a cross section of the same cutting wheel, in which the illustrated cross section shows a region with a tooth projecting up to the cutting edge 4, while Fig. 5 shows the interdental space between two teeth.

As can be seen from Fig. 5, the laser beam irradiated at a shallow angle at the shoulder 20a becomes a little

shadowed. However, this shadow does not continue to the cutting edge 4 ', so that at this point no or only slight impairment of the smoothing of the surface structure occurs. The influence of the shading can be reduced by the fact that the paragraph 20a further spaced from the

Cutting edge 4 'is arranged and / or by the angle of the laser beam is increased within the possible limits.

Another difference to FIGS. 2 and 3 is that the scaling of the illustrated diagram shows a greater width of the cutting wheel over slightly more than 600 ym. The laser to be used must always be adapted to the application. Therefore, the following description of laser parameters is purely exemplary. The performance of for the Machining of the cutting wheel used in polydiamantenem material shown in FIGS. 1 to 5 is at a maximum of 2.8 watts at 500 kHz and a

Pulse length of 10 picoseconds.

Due to the high pulse frequency of this laser can

Cutting wheel during processing with a

rotate comparatively high speed. Is that the

Cutting wheel diameter, for example, 2 mm and the speed 20 U / sec. or 1200 rpm, the resulting local pulse spacing between two successive pulses is approximately 0.25 μm, which is far below a beam diameter. The individual pulses can thus not be recognized on the laser-machined cutting wheel surface, that is to say the side surface, or only to a very limited extent.

In the following, various characteristics of the cutting blade smoothed and sharpened by the method described above will be described.

Figs. 6 to 15 show measured data and evaluations of

Measured data for an untreated, under this

Description as "prefabricated" designated cutting wheel, as it is known from the prior art, as well as for an inventively processed cutting wheel

Cutting wheels have a rather large cutting angle of about 140 °. Nevertheless, the invention is not on

Cutting wheel limited with such a cutting angle. From this description the differences and the associated advantages become clear. So there are different parameters for the characterization of the geometry and Surface texture of the cutting edge and the adjacent portions of the side surfaces, which can be applied individually or in any combination linked together.

Fig. 6 shows a three-dimensional structure of a

Cutting wheel in a micrometer-accurate resolution, which has been detected with a camera device. The

Three-dimensional height structure was determined by white-light interferometry using confocal microscopy. The measured structure reproduces, with an accuracy in the range of approximately 1 μm, the three-dimensional shape of a section of the cutting edge whose quality and quality is to be determined. In this case, the individual pixels each indicate a specific value for the respectively associated subarea on the surface. Both

Depending on the objective, the lateral resolution was approx. lym or less than lym

In contrast, depth resolution is below lym.

The gray levels in FIG. 6 represent different height values, wherein the same gray levels do not represent the same height values at the lower edge and at the cutting edge. The black-and-white representation has been obtained from a colored representation, with red colors at the cutting edge and blue colors at the bottom, which gave the same gray tones in the black and white representation.

Both from the measured three-dimensional data and from derived two-dimensional views, as shown for example in FIGS. 8 and 9, the Geometry, both qualitatively and quantitatively.

In the following, it is assumed that the cutting edge runs from top to bottom within the input image that is being evaluated. When taking the

Three-dimensional structure, therefore, the cutting wheel is therefore arranged as centrally as possible. At the beginning of the evaluation, first the horizontal position of the cutting edge or the vertical position of the cutting wheel axis is searched for in the input image and thus symmetrically the

Evaluation range. Furthermore, the geometry of the

Schneidrädchens be determined. In the analysis of the evaluation range, the geometry of the cutting wheel is first approximated by an ideally round, and on the opposite cutting edges flat, smooth cutting wheel.

FIG. 7 shows an evaluation for a prefabricated cutting wheel known from the prior art. Shown is the height difference between the measured geometry of the

Cutting wheel in the evaluation area, so in the top

described input image of FIG. 6, and the approximated by an ideal round and unstructured cutting wheel geometry. Different gray values represent

different deviations from the ideal form.

Clearly visible in the center of the image, the lighter area of the almost vertical cutting edge.

This is already a first indication that the Cutting edge in the area of the tip deviates significantly from the ideal shape.

From the approach to an ideally round and unstructured, so no tooth structure exhibiting cutting wheel can first of the cutting angle and the diameter of the

Schneidrädchens be determined.

Furthermore, two vertical lines are shown in Fig. 7, which are located at a predetermined distance from the left and right edge of the evaluation area. These lines symbolize the expected scribe distance of +/- 10 ym and +/- 20 ym, ie the area of the cutting edge and the side surfaces used for the scoring of the material

are responsible. The scratch distance thus represents the

Contact width with the material, for example. The glass.

Fig. 8 shows the same evaluation for one with a

inventive method processed cutting wheel. The shades of gray are the same and at that compared to

Fig. 7 more regular structure of the gray scale can be seen that the side surfaces are much smoother. In addition, it can be seen in the area of the cutting edge that it differs only slightly from the ideal shape. The cutting edge is thus significantly sharper than the prefabricated

Cutting wheel.

When analyzing the evaluation range, the straightness deviation of the cutting edge can be determined as an important parameter. The cutting edge is first determined by the horizontal position of the highest points of each line

Evaluation area defined. Because the cutting edge depending on Alignment of the input image partially passes diagonally through the evaluation, determines the

Straightness deviation as deviation from one

interpolated linear cutting edge.

Figures 9a and 9b show details of determining the value for the straightness deviation. FIG. 9a shows the profile of the position of the cutting edge derived from the measurement data according to FIG. 2 in each row over a range of 500 μm. A curve running in steps of measuring resolution of about 1 ym can be seen, which is slightly inclined

runs because the input image has not been aligned exactly. Fig. 9a further shows a linear interpolation of

Measurements, in this case, resulting from the pixel resolution of approximately 1, 6ym and in stages. The

Interpolation can also be done through a low-pass filter

carried out. The course of the cutting edge is thus

smoothed and approximated with a straight line.

9b then shows the deviation of the measured values from the linear interpolation according to FIG. 9a. As dashed

horizontal lines, the range of the standard deviation is additionally shown in FIG. 9b. The value of this

Standard deviation, ie the distance of the dashed line from the zero line in Fig. 9b, is then taken as the value for the straightness deviation. The cutting edge accordingly has a straight-line deviation of less than 2 μm, in particular approximately 1 μm. This value can be further improved by the parameters of the invention Processing of the side surfaces and the cutting edge can be optimized.

In Fig. 10 are details for determining the

reproduced interpolated cutting edge of the processed with a method according to the invention Schneidrädchens. These are the measured height values along the course of the

Cutting edge derived from the data of the three-dimensional shape of the input image of FIG. 6 and as a line 30th

drawn. Fig. 10 thus represents the radial

Course of the cutting edge with the radial waviness to be determined along the measured portion of

Cutting wheel dar.

The wavy curve 32, which extends at a distance below the measured values, represents the averaged cutting edge. From this approximation, the average cutting edge becomes an ideal round wheel with flat side surfaces

circular arc-shaped curve 34 determined because a circular cutting edge is to be produced. The distance between the measured data 30 and the circular arc-shaped curve 34 reproduces the negative cutting edge truncation described in more detail below with reference to FIG. 13, that is to say that the real profile of the cutting edge extends above the averaged cutting edge.

FIG. 11 now shows the deviations of the measured values of the curve 30 in FIG. 10 from that at the interpolated cutting edge

adapted circular curve 34, wherein the values fluctuate to a certain extent around the zero line. The difference curve does not fluctuate around the value zero due to the negative cutting edge truncation, but by the value of Cutting edge blunting around. The curve in Fig. 11, however, was corrected for the value of the negative cutting edge blunting to determine the standard deviation, and thus made averaging. This results in Fig. 11. The two horizontal dashed lines represent the

Standard deviation, wherein the distance of the dashed line from the zero line, the determined value of

Cutting edge ripple represents. The cutting edge thus has a cutting edge waviness of less than 0.3 ym, in particular of about 0.2 ym.

FIGS. 12 to 15 show evaluations which are directed to the sharpness of the cutting edge 4 and serve to

Sharp edge checking parameter too

win.

FIGS. 12 and 13 give evaluation results for the im

Evaluation range of the input image averaged sharpness or quality of the cutting edge or the cutting edge for a

prefabricated cutting wheel and for one with a

process according to the invention processed cutting wheel again.

In Figs. 12 and 13, for an evaluation of the measured cutting edge shape, one is an ideal cutting edge shape

Approximated triangular lines 40 and 50 have been drawn. For this purpose, as has been described above with reference to FIG. 7, the geometry approximated to an ideally round and unstructured cutting wheel is used. The curves 40 and 50 thus represent the approximation of the left and right

Cutter flanks are represented by two equalization lines that meet at the cutting edge. In Fig. 12, for a prefabricated cutting wheel, the curve 42 represents the line-average averaged shape of the cutting edge, the average shape of the cutting edge being obtained from all the lines, passing through all the "pixels" of the image that are the same

have corrected distance to the cutting edge, the height value is averaged. It was considered that the

Cutting edge in each line of the evaluation range along the cutting edge varies laterally or radially to the cutting axis. FIG. 13 shows the corresponding line 52 for the cutting wheel processed by the method according to the invention.

Two different averaging methods are preferably used.

In a first alternative, the line-average averaged shape of the cutting edge is represented by the values of the measured profile with respect to the maximum value in each line, i. determined based on a non-straightened cutting edge.

In a second alternative, the line-average averaged cutting edge shape is interpolated with respect to one

Cutting edge shape approximated circular arc determined. The approximate circular arc shape has been described above with reference to FIG. The line averaged

In the second alternative of interpolation, cutting edge forms somewhat duller than the first alternative. From the approximation of an ideal cutting wheel

Thus results for each line a curve. FIGS. 12 and 13 show this curve and the measured course of a line. As can be seen from FIG. 12, the line-wise averaged cutting edge shape 42 deviates from the ideal shape, in particular in the region of the cutting edge. A clear

Dulling over a width of about +/- 3-4 ym laterally of the cutting edge (x = 0 ym) can be seen.

In contrast, Fig. 13 shows averaged line by line

Cutting edge mold 52 for the cutting wheel machined by the method according to the invention, which projects beyond the shape of the geometry approximating the ideal round and unstructured cutting wheel in the region of the cutting edge. The

measured cutting edge has just in the range +/- 30-50 ym around the cutting edge on an exaggerated more pointed shape. In addition, the course of the curve 52 is much smoother than the curve 42 in Fig. 12, which again a reference to the

Smoothing effect of the method according to the invention gives.

The difference between the two curves 40 and 42 and the difference between the two curves 50 and 52 at the

Position of the cutting edge (x = 0 ym) is used as a measure of the cutting edge blunting. This results in a positive value for FIG. 12, while the

Cutting edge blunting for Fig. 13 is negative. For an ideal cutting edge, both curves would be identical and the cutting edge blunting would be zero.

FIGS. 14 and 15 show an evaluation of the angles of the measured cutting edge averaged over all lines in comparison to a geometry approximated to an ideally round and unstructured cutting wheel. This approximate geometry has been explained with reference to FIG. The scaling has been chosen the same in both diagrams, so that the curves of the individual curves can be directly compared with each other.

The dash-dot line 60 and 70 shown in FIGS. 14 and 15 at an angle of approximately 138 ° in FIG. 14 and of approximately 141 ° represents the cutting edge angle spanned in the approximate geometry between the two edge regions.

The lines 62 and 72 drawn in FIGS. 14 and 15 represent the cumulative cutting angle. To calculate the cumulative cutting angle, the height value of the cutting edge averaged over all lines is first calculated. Thereafter, the mean vertical value on the side surface, which is averaged over all rows, is determined on both sides of the edge of the snow at equal intervals on the right and left. The cumulative angle is then the angle defined by the two straight lines between the averaged height value of the cutting edge and the two averaged values in the

Distance points left and right of the cutting edge.

The waveform of lines 62 and 72 is therefore symmetrical to the cutting edge (x = 0 ym). The shape of the cumulative

Cutting angle is to be interpreted as follows.

In Fig. 14, the cumulative cutting angle is large

Distances of approx. +/- 50 ym from the cutting edge only slightly above the angle of the line 60 approximating to the ideal shape. The closer the distance to the cutting edge is reduced, the more the cumulative angle increases until it reaches x = 0 ym reached the value 180 °. Even if the waveform gives a peak, increases in the representation of the cutting angle to larger values in the y-direction.

The width of the curve 62 gives an indication that the cumulative cutting angle already increases sharply from +/- 20 ym and at +/- 10 ym exceeds the angle of about 150 °, ie becomes flatter. The shallower angles are therefore a measure of the blunting of the cutting edge. When scribing thin glasses, the scribe width is considerably lower compared to scribing thick glasses. If the scribe width to the left and to the right of the cutting edge is, for example, only 10 μm, the edge angle coming into contact with the glass in FIG. 14 is slightly more than 151 °, with a scratch width left and right of the cutting edge of 20 μm about 144 °. In addition, in FIG. 15, significantly lower fluctuations in the surface structure occur.

In contrast, the curve 72 in Fig. 15 for greater distances to about +/- 50 ym initially below the approximated to the ideal shape angle of the line 70. This means that in this area, the cutting edge at a steeper angle than that of the ideal Geometry has approximate shape. Only from values below +/- 5 ym does the cumulative angle exceed the value of approximately 150 °. The cutting edge therefore rounds off only at significantly smaller values than is the case in the prior art. Even with minor scoring, as is common in scribing thin glass, the cutting angle in the area of contact of the cutting wheel with the glass is comparatively constant and sharp compared to that of the prefabricated one. In FIGS. 14 and 15, lines 64 and 66, and 74 and 76 respectively represent the angle formed by the two mean local slopes left and right of the cutting edge in FIG

Depends on the distance to the cutting edge. In this case, the dashed curve 64 and 74, the over a

Pixel pitch determined local slopes and the

the first 2 pixels in the immediate vicinity of the cutting edge are not filtered (first pixel) or only with a 2X1 low-pass filter (second pixel).

A comparison between the amplitudes of the two curves 64 and 74 results in a significantly smoother for the cutting wheel processed by the method according to the invention

Surface .

From the course of the curve 66 or 76 can be the

Derive the starting distance of the cutting edge rounding, which defines the distance to the cutting edge at which the continuous curve 66 and 76, starting from the cutting edge for the first time reached a value of 1 degree above the dashed curve 60 and 70, respectively. This value is additionally marked with a cross. For distances to the cutting edge, which are smaller than this starting distance of the cutting edge rounding, the local cutting angle is thus continuously more than 1 ° larger than the middle, to the ideal

Cutting edge shape approximate cutting angle. This is interpreted as meaning that the rounding of the cutting edge starts from this point. From Fig. 14 it can be seen that the starting point of the cutting edge rounding for the prefabricated cutting wheel is at values of +/- 7 - 10 ym. In contrast, the value of the starting point of the cutting edge rounding in the cutting wheel machined by the method according to the invention according to FIG. 15 is at values of +/- 3-4 μm. This value also represents a measure of the sharpness and accuracy of the cutting edge. The following can also be read from FIG. 15. The side surfaces have a middle

Cutting angle to each other, which are limited by the angle of two sections, which are on both sides of the cutting edge of the cutting edge to a first distance, here about +/- 250 ym to the cutting edge. This corresponds to the width of the input image and the angle corresponds to the mean cutting angle of the line 70. The angle between two

Sections of the side surfaces, in an area between a second distance near the cutting edge, here the

Starting point of the cutting edge rounding, and a relation to the first distance smaller third distance, here is limited to +/- 50 ym, is smaller than the middle

Cutting angle. Because the curves 74 and 76 run in this section below the line 70.

Claims

P a n t a n s p r e c h e

Method for smoothing a surface of a

prefabricated cutting tool, in particular

Schneidrädchens with two side surfaces which extend at an angle to each other and form a cutting edge, wherein at least one side surface at least in a region adjacent to the cutting edge with a

Laser beam is applied and

wherein the laser beam is aligned at a shallow angle to the surface of the side edge.

Method according to claim 1,

in which the flat angle is set in an angular range of less than 45 °, preferably 5 ° to 45 °, in particular 10 ° to 30 °.

Method according to claim 1 or 2,

in which the laser beam on the cutting edge

is focused adjacent area.

Method according to one of claims 1 to 3,

where the cutting wheel is continuous or in

separate steps is rotated.

Method according to one of claims 1 to 4,

where the relative position of the laser focus to

Side surface is adjusted continuously or in single steps. Method according to claim 5,

in which the laser beam is parallel to the propagation direction while maintaining the angle to the side surface and maintaining the relative position of the focus of the

Laser beam is adjusted.

Method according to claim 5,

wherein the angle of the laser beam is adjusted to the side surface while maintaining the relative distance of the focus of the laser beam to the side surface.

Method according to claim 7,

wherein the angle of the laser beam to the side surface at the cutting edge is set lower than in the area remote from the cutting edge.

Cutting tool, in particular cutting wheels for

Cutting brittle materials, such as ceramics and / or glass,

with two at a predetermined angle to each other extending side surfaces (6a, 6b) and

with a through the side surfaces (6a, 6b) formed

Cutting edge (4),

characterized ,

the side surfaces (6a, 6b) have a middle one

Cutting angle to each other, which is determined by the angle of two sections which are bounded on both sides of the cutting edge (4) from the cutting edge to a first distance to the cutting edge (4), and

that the angle between two sections of the

Side surfaces (6a, 6b) which are in a range between a second distance near the cutting edge and a are limited to the first distance smaller third distance, smaller than the average cutting angle.

Cutting tool, in particular cutting wheels for

Cutting brittle materials, such as ceramics and / or glass,

with a through the side surfaces (6a, 6b) formed

Cutting edge (4),

characterized ,

at least one of the following parameters a) to d) is fulfilled:

the cutting edge (4) has a straight-line deviation of less than 2 μm, in particular less than 1 μm,

the cutting edge (4) has a cutting edge waviness of less than 0.5 μm, in particular less than 0.3 μm,

the cutting edge (4) has a negative

Cutting edge blunting on,

the cutting edge (4) has a starting distance of

Edge rounding of less than 4 ym, especially less than 2 ym on.

11. Cutting tool according to claim 9 or 10,

characterized,

that the snow edge is continuous.

12. Cutting tool according to claim 9 or 10,

in that the cutting edge is provided with a sequence of teeth and interdental spaces and that the properties of the cutting edge according to claim 10 or 11 apply at least to the teeth.