EP1834731B1 - Process of grinding cutting tools - Google Patents

Abstract

The disc (1) has roof sides (3a,3b) including grinding layers, where straight and convex surface contour areas (13,15) of a chipping tool (11) with one of the roof sides and concave surface contour area (21) of the chipping tool with other roof side are ground. The disc is designed as a dual cone disc, where a rotation axis coincides with a cone axis. The roof sides are formed respectively on a plane, which is in an angle lesser than ninety degrees. An independent claim is also included for a method for grinding a chipping tool.

Description

Technical area

The invention relates to a method for grinding of cutting tools.

State of the art

For grinding of cutting tools cup wheels, profiled disks, peripheral disks and grinding pins were used. Flap discs are generally not used for grinding cutting tools; they are typically used for paint stripping and rust removal.

Cup wheels are designed as a straight truncated cone, being ground at the edge of the large base top. There are cup wheels with straight and oblique pot. Both types of cup wheels have an inner recess. The cup wheel with oblique pot is designed as a hollow truncated cone inside. An abrasive coating is arranged at the base edge. The cup wheel with a straight pot is also hollow inside and thus has a U-shaped cross-section, wherein the abrasive coating is arranged on the end sides of the U-legs. Both disc types are rotationally symmetrical, the axis of symmetry being the axis of rotation.

The grinding edge can have various shapes. A disadvantage of cup wheels is a long adjustment and a 180 ° rotation of the workpiece when sanding points must be grinded with each opposite on a cup wheel. Due to the disc geometry, a machining process is usually limited to the use of a single grinding wheel; Workpiece tension or machine parts would otherwise collide with the disk bodies.

Peripheral disks, also called circumferential disks, can be designed as disks with a circumferential abrasive coating arranged parallel to the axis of rotation. An undercut is difficult to carry out due to the orientation of the abrasive coating to the disk body. Concave radii can only be ground up to a quarter circle at most.

Profile discs have instead of a parallel to the axis of rotation extending, circumferential disc edge a conically converging disc edge with a rounded (toric) tip. Only with the torus profile is sanded, whereby a relief can be made. The life of the precise Torusprofils is very limited, a precise dressing of these discs is not possible on the grinding machine.

A grinding pin is generally formed analogous to a milling cutter which can be clamped in a chuck, an abrasive coating being arranged instead of the milling cutters.

Presentation of the invention task

The object of the invention is to provide a method for grinding of cutting tools, with or with the arbitrary concave and convex profiles can be ground with one and the same grinding wheel, wherein a dressing grinding a grinding wheel used for grinding already on the grinding of the tool used machine tool should be possible.

solution

The object is achieved by the features of claim 1 Preferred embodiments of the invention result from the features of the dependent claims.

In a grinding wheel for carrying out the method according to the invention for grinding cutting tools, the circumference of the grinding wheel is designed as a circumferential ridge with roof sides converging on it and each having an abrasive coating. Concave radii of a surface contour area of the cutting tool are with the ridge and / or in each case with one of the roof sides and all convex contour areas are each sandable with one of the two sides of the roof. Of course, the convex surface contour areas could also be ground with the ridge; However, it is more precise and faster with one of the roof sides. The grinding wheel can be characterized as a peripheral disk, in which the peripheral side provided with an abrasive coating is no longer a circular cylinder jacket outer side, but now two peripheral sides, an angle in cross-section, analogous to a roof ridge converge.

document US 4813188 describes a method according to the preamble of claim 1.

Typically, the abrasive wheel is coated with diamond or cubic boron nitride abrasive material; Of course, other abrasive ingredients may be used within the scope of the invention. Cutting tools are mainly, but not limited to, profile exchangeable plates or profiled rotating tools.

The symmetry axis of the grinding wheel is at the same time its axis of rotation. Preferably, the grinding wheel will be formed as a double cone wheel (V-shaped grinding wheel), wherein both cone axes coincide and form the axis of rotation. The small area of each cone can now be a plane perpendicular to the axis of rotation; it does not have to be. The two surfaces can be flat, with each other mirror-image or different curvature outwards or inwards formed.

The thickness of the grinding wheel depends, apart from mechanical stability requirements, on the surface profile radii to be ground or on the depth and the width of the profile pockets of the tool to be ground. The Doppelkonusmantelflächen or roof sides will allow to converge at an angle smaller than 90 °, preferably you will choose this roof ridge angle typically with 60 °; Of course, smaller angles are possible, in particular select smaller 30 °. Of the Roof ridge angle is selected for collision reasons about 10 ° smaller than the smallest angle of concave surface contour areas to be ground. Within this limit, the angle is chosen as large as possible in order to obtain maximum stability. This stability includes, among other things, the mechanical stability of the grinding wheel and a geometrical stability of the roof ridge or of the torus resulting from wear. Sanding is now done with one of the roof sides (cone shell sides) and / or with the roof ridge (top). Thanks to the angular orientation of the sanding pad to the disk body and thanks to the slender disk geometry, an undercut can also be created. The grinding wheel thickness and the roof ridge angle determine how deep and how narrow an undercut can be made.

Dressing is very easy, since only the roof sides, usually flat, must be processed.

The tip is usually very sharp after dressing. When sanded with it, it wears off and acts like a profile disc with a rounded tip. Although the sharp tip is used up quickly, it can also be produced again quickly with a dressing wheel already located on the same tool grinding machine. The slightly worn roof ridge is then torus-like with a very small torus radius. Because of this very small dimension deviations from a pointed geometry or the ideal torus in absolute measure are now very small and therefore tolerable. Compared to a profile grinding wheel, another grinding process is carried out with the grinding wheel according to the invention: not only with the tip, but also with the tip. H. mainly ground with the converging roof sides.

The grinding wheels have a typical wheel diameter of 300 mm. This relatively large radius is chosen to be able to grind flat surfaces.

Grinding and dressing can be performed advantageously on one and the same machine.

Typically, not only one of these grinding wheels will be arranged in one tool grinding machine, but several.

Any concave and convex profiles can be ground with the double cone disk, whereby concave radii with the point and straight lines in concave surface profiles of the cutting tool as well as all convex profiles with one of the two surfaces are ground. This very advantageous grinding technique remains on surfaces, as given in particular in pot or peripheral disk, received: The straight-disk profile of the double cone disk is easy to dress. The flat roof sides have a long service life in the grinding process and can be used to improve the surface quality oscillating.

A grinding machine with such a double cone disk provides good workpiece accessibility, no problems with clamping devices and small machine paths. The assembly of the machine with several discs (for example coarse-grained for roughing and fine-grained for finishing) is possible without collision. The use of different discs for roughing results in a higher erosion performance and allows a more stable production process as a result of sparing the discs, in particular the slices. The discs must now be dressed less and less often. It can also be followed by polishing cuts in the same machining program, which only serve to improve the surface quality with minimal abrasion. The polishing process benefits from the grinding process proposed here, since fine-grain slices with grain sizes in the range of a few thousandths of a millimeter tolerate only the smallest of cuts. Very accurate wheel geometries and equally accurate tool geometries prior to the polishing operation are required.

From the following detailed description and the totality of the claims, further advantageous embodiments and feature combinations of the invention result.

Brief description of the drawings

Fig. 1

einen Querschnitt durch eine Ausführungsvariante einer Schleifscheibe zur Durchführung des erfindungsgemäßen Vefahrens,

Fig. 2

eine Draufsicht auf die in Figur 1 dargestellte Schleifscheibe,

Fig. 3

eine Seitenansicht der in Figur 1 dargestellten Schleifscheibe,

Fig. 4a - 4j

schematische Darstellung zum Schleifen von unterschiedlichen Oberflächenprofilen eines Zerspanwerkzeuges mit der in den Figuren 1 bis 3 dargestellten Schleifscheibe,

Fig. 5

eine schematische Darstellung für ein Abrichtschleifen einer Schleifscheibe mit einer Abrichtscheibe, welche auf derselben Werkzeugmaschine, wie die Werkzeug schleifenden Schleifscheiben angeordnet ist und

Fig. 6

eine Variante zu der in den Figuren 1 bis 3 dargestellten Schleifscheibe.

The drawings used to explain the embodiments show

Fig. 1

a cross section through an embodiment of a grinding wheel for carrying out the method according to the invention,

Fig. 2

a top view of the in FIG. 1 illustrated grinding wheel,

Fig. 3

a side view of in FIG. 1 illustrated grinding wheel,

Fig. 4a - 4j

schematic representation for grinding different surface profiles of a cutting tool with in the FIGS. 1 to 3 illustrated grinding wheel,

Fig. 5

a schematic representation of a dressing grinding a grinding wheel with a dressing wheel, which is arranged on the same machine tool as the tool grinding grinding wheels and

Fig. 6

a variant to that in the FIGS. 1 to 3 illustrated grinding wheel.

Basically, the same parts and elements are provided with the same reference numerals in the figures.

Ways to carry out the invention

The in the FIGS. 1 to 3 illustrated grinding wheel 1 has on the disc circumference (disc sheath) two trained as roof sides disc edge sides 3a and 3b, which converge to a circumferential ridge 5 . In the first 5 , the two roof sides 3a and 3b collide at a ridge angle α. The size of the ridge angle α depends on the surface contour to be ground. As a rule, ridge angle α is less than 90 °, typically 60 °. The roof sides 3a and 3b are covered with an abrasive coating 7a and 7b, respectively. In the center of the grinding wheel 1 , a breakthrough 9 is present in order to attach the disc 1 on a mandrel of a grinding head, not shown, can.

The grinding wheel 1 is rotationally symmetrical about its axis of rotation 10 . The axis of rotation 10 forms the axis of the aperture 9. A plane in which the peripheral roof ridge 5 is located, also forms a plane of symmetry 12. The plane of symmetry 12 defines together with one of the roof sides 3a and 3b and one of the side surfaces 19a and 19a mentioned below. 19b a cone [ 19a-3a-12 and 19b-3b-12 ]. The grinding wheel 1 can thus also be referred to as a double cone disk, the axis of rotation 10 being identical to the cone axes.

In the FIGS. 4a to 4j is the respective relative position between a grinding workpiece 11 to be ground and the grinding wheel 1 shown at different surface contour areas. In FIG. 4a It is shown how an approximately plane, straight running surface contour area 13 can be ground with the roof side 3b of the grinding wheel 1. For grinding surface contours, the tool 11 to be ground will generally be moved. If an undercut 14 with a concave surface contour, as in FIG. 4b are indicated, ground, is worked with the roof ridge 5 of the grinding wheel 1 . A grinding of a now following straight or convex surface contour area 15, as in Figure 4c is shown with the Roof side 3a ground. A following on the surface portion 15 convex edge 17 is further ground with the roof side 3a ( FIG. 4d ). The approximately flat surface area 18 following the edge 17 is further ground with the roof side 3 a ( Figure 4e ). After grinding the surface area 18 , the tool 11 is displaced and with the same roof side 3 a a flat (or convexly curved) surface area 20 (FIG. FIG. 4f ) ground. After a slight rotation of the tool 11 , the relief surface 21 having a concave surface area is made with the roof ridge 5 (FIG. Figure 4g ). The following approximately straight surface region 22 of the relief cut is then connected to the roof side 3b ( FIG. Figure 4h ) and then also the following edge 23 ( FIG. 4i ) ground. The already ground surface area 18 could, as in FIG. 4j shown again reground with the roof side 3b , in order to obtain a good transition from the edge 23 to the surface region 18 . The surface contour areas 14 and 15 as well as 21 and 22 represent a relief section.

Instead of starting from Figure 4e the grinding process over the FIGS. 4f to 4j he can also in reverse order on the FIGS. 4j to 4f respectively. It should be ensured as far as possible that a pulling processing takes place with the roof sides, so that as little as possible is worked with the roof ridge.

On a machine tool, a plurality of grinding wheels are generally used for grinding tools. To dress the grinding wheel 1 , ie to grind the sides of the roof after a longer grinding operation and to sharpen the roof ridge, is, as in FIG. 5 indicated, a Abrichtschleifscheibe 30 used. Abrichtschleifscheibe and one or more grinding wheels 1 are located on the same machine tool. That is, a dressing of the grinding wheels can be made without removing the grinding wheels from the machine tool, resulting in a large time gain.

The grinding wheel can now as in the FIGS. 1 to 3 can be formed as a disc with mutually parallel side surfaces 19a and 19b . But it can also in addition to outwardly slightly cambered side surfaces, as mentioned above, also cambered inwardly offset side surfaces or even and parallel to each other, as in a FIG. 6 shown grinding wheel 32 are used. In the grinding wheel 32 , a base 34 of the roof sides 36a and 35b is wider than the thickness d of the grinding wheel 32. An advantage of this grinding wheel 32 over the grinding wheel 1 is the smaller dimension and thus a smaller mass, which changes rapidly the rotational frequency allows. However, to achieve a uniform rotational speed during grinding, higher speed control and constant maintenance requirements are required due to the lower mass.

Claims (7)

1. Process for grinding cutting tools (11) with one and the same grinding wheel (1; 32) on a machine tool, wherein
   the grinding wheel (1; 32) has roof sides (3a, 3b; 36a, 36b) which converge towards a circumferential ridge (5) at the wheel edge and have one grinding layer (7a, 7b) each, and
   the roof sides (3a, 3b; 36a, 36b) are dressed, with a sharp ridge (5) being formed, without removing the grinding wheel (1; 32) from the machine tool, and
   with the roof sides (7a, 7b) of one and the same grinding wheel (1; 32), straight lines (13, 15, 18, 20, 22) are ground in concave surface contour regions of the cutting tool (11) to be ground in each case,
   characterized in that all the convex contour regions (17, 23) are ground with one of the two roof sides (3a, 3b; 36a, 36b) converging towards the ridge (5) and concave radii in surface contours (14; 21) of the cutting tool (11) are ground with the ridge (5) and/or one of the roof sides (3a, 3b; 36a, 36b).
2. Process according to Claim 1, characterized in that the roof sides (3a, 3b; 36a, 36b) are dressed on the machine tool.
3. Process according to Claim 1, characterized in that the cutting tool (11) is ground with a grinding wheel (1; 32) which is designed as a double-cone wheel and in which a rotation axis (10) coincides with a cone axis.
4. Process according to Claim 1, characterized in that the cutting tool (11) is ground with a grinding wheel (1, 32) having roof sides (3a, 3b; 36a, 36b) which are designed as double-cone lateral surfaces and converge at an angle (α) of less than 90°.
5. Process according to Claim 2, characterized in that the cutting tool (11) is ground with a grinding wheel (1; 32) which is designed as a double-cone wheel and in which a rotation axis (10) coincides with a cone axis and a machine-tool spindle axis.
6. Process according to Claim 2, characterized in that at least one of the roof sides (3a, 3b; 36a, 36b) of the grinding wheel (1, 32) is dressed with at least one dressing wheel (30) of the machine tool, preferably in the form of a double-cone lateral surface.
7. Process according to Claim 1, characterized in that a plurality of these grinding wheels (1; 32) are present, preferably with different wheel thicknesses, in particular with grinding layers (7a, 7b) having different abrasive grain sizes, and preferably with different ridge angles (α).

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