EP0321972A2 - Grinding wheel and use of the same - Google Patents

Abstract

A grinding wheel (10) is provided with a rotating machining surface (30, 31) made of an abrasive material and is provided with a central location opening with a metallic location surface. In order to increase the mechanical stability of the grinding wheel and thus to make possible in particular external cylindrical grinding with an extremely high rate of metal removal, the grinding wheel (10) is designed as a metal wheel (16) and is provided at its periphery with a narrow border (13) of abrasive material. <IMAGE>

Description

The invention relates to a grinding wheel for grinding workpieces, with a metal wheel which is essentially rotationally symmetrical with respect to a first axis and which is provided on its circumference with a narrow edge made of bound CBN grains.

The invention further relates to a grinding wheel of the type mentioned above for external cylindrical grinding of workpieces.

A grinding wheel of the type mentioned is known from US Pat. No. 3,742,654.

In the known grinding wheel, a metallic carrier body consists of a flat disk in the outer area and an axially extending hollow cylindrical receiving body in the area near the axis, the central receiving opening of which is partly conical, partly with a thread. A narrow edge made of abrasive material, for example bonded CBN grains, is applied to a cylindrical peripheral surface of the disk-shaped metallic body. The edge also has a hollow cylindrical shape.

Due to its design, the known grinding wheel is only suitable for engaging the workpiece with its cylindrical outer circumferential surface while aligning its axis of rotation parallel to the longitudinal axis of a workpiece.

Another grinding wheel is known from US Pat. No. 3,795,497, which can be designed as a grinding roller, cutting wheel or shaped grinding wheel. In this known grinding wheel, a relatively thin edge made of grinding material is applied to a metallic body, details of which are not specified. This edge has the shape of a hollow cylinder in the case of the grinding roller and the cutting-off grinding wheel, while in the case of a shaped grinding wheel it has e.g. has a corrugated shape in cross section.

Due to the design of this known grinding wheel, only one application is also conceivable in which the axis of the grinding wheel runs parallel to a workpiece axis and the grinding wheel is fed in a direction perpendicular to these axes.

From DE-OS 26 34 154 a cup grinding wheel is known, in which a metallic support body of a trapezoidal shape in radial section is provided with a sheet steel disk which projects radially beyond the support body. At the outer edge of the steel sheet disc, its radial side surface is provided with an annular edge made of abrasive material, so that a cup-shaped structure is created. The well-known cup grinding wheel is used to grind flanks of teeth from gear wheels. For this purpose, the grinding wheel is inserted in the radial direction between two teeth of the grinding gear then axially moved the grinding wheel laterally with a radial grinding surface to a tooth flank.

From a brochure "RIEGGER diamond grinding wheels" from Riegger GmbH & Co. KG, 7015 Bittenfeld, several configurations of diamond grinding wheels are known in which an edge made of grinding material is applied to a peripheral surface of a disk-shaped carrier body. No further details can be found in this brochure.

Finally, CH-PS 364 191 also shows a disc grinding wheel, the design of which essentially corresponds to that of the previously described DE-OS 26 34 154.

The known grinding wheels have in common that they can only be applied to a surface of the workpiece with a single cutting surface, namely either a cylindrical circumferential surface or a flat radial end surface in the radial or axial direction.

The invention is based on the object of developing a grinding wheel of the type mentioned in such a way that grinding processes can be carried out in which at least two cutting surfaces on the workpiece are engaged while maintaining the mechanical stability of grinding wheels with a metallic carrier body and the advantageous grinding properties of CBN grains are.

This object is achieved in that the edge has two conical cutting surfaces inclined to the first axis, which are at an angle of substantially 90 ° cut, with one of the cutting surfaces as the main cutting surface perpendicular to a second axis of the workpiece.

When using the grinding wheel according to the invention, it is used for external cylindrical grinding of workpieces with a diameter between 5 and 250 mm at a grinding wheel peripheral speed between 100 and 300 m / s, a workpiece peripheral speed between 65 and 200 m / min and an axial feed speed between 150 and 2000 mm / min.

The object on which the invention is based is completely achieved in this way because surface grinding peeling can be carried out with the grinding wheel according to the invention, particularly when used according to the invention, in which material with a thickness of several millimeters is removed in a single pass at high axial feed speeds can be.

With the grinding wheel according to the invention, high chip removal volumes can be achieved. This leads to machining technology that is on a par with turning. However, the advantage of grinding compared to turning is that the material chips occur in grain-like form during grinding, so that grinding machines can work fully automatically because the removal of the grinding chips is unproblematic. This is different for lathes, because turning chips arise as long spiral chips and, in an unfavorable constellation, these long chips can wrap around the workpiece and cause the turning machine to lock up. Lathes must therefore be monitored so that resulting swarf can be removed using a hook.

It has also been shown in testing the grinding wheel according to the invention that it is possible to use an oil-water emulsion instead of an oil for cooling and lubricating the workpiece or the grinding wheel at the point of engagement. This represents a significant advantage from the point of view of disposal. According to the relevant regulations, the "grinding sludge" mixed with oil is classified as special waste because the metal chips of the workpieces that accumulate during grinding are soaked with oil. Such hazardous waste can, however, only be removed with a correspondingly high technical and therefore financial outlay.

This is different with grinding sludge, which is provided with an emulsion, because when this grinding sludge is stored, the emulsion runs out of the chips automatically due to its much lower viscosity, so that the remaining grinding chips with very low oil content can be removed as normal waste.

It is particularly preferred in the invention if the edge is applied to a conical edge surface of the metal disk, which is positioned perpendicular to the workpiece axis in the area of the main cutting surface. But even if the edge surface is not conical, but for example as a circumferential cylindrical annular groove, a configuration results in which the edge is held in a form-fitting manner in the region of the main cutting surface perpendicular to a workpiece axis. In all of these embodiments, there is the advantage that the

Edge is held by the metallic base body with a contact surface that is perpendicular to the main direction of the force that is exerted on the grinding wheel when grinding a workpiece.

Finally, an embodiment of the invention is preferred in which the receiving opening is designed as a polygon.

This measure has the advantage that the arrangement can be made reproducibly and without play, compared to cylindrical or conical receiving openings, because with a polygon shaped receiving opening is always a defined number of contact points between the receiving opening and the polygon mandrel of the grinding wheel spindle.

Further advantages result from the description and the attached drawing.

It goes without saying that the features mentioned above and those yet to be explained below can be used not only in the respectively specified combination but also in other combinations or on their own without departing from the scope of the present invention.

• Fig. 1 eine Draufsicht auf ein Ausführungsbeispiel einer erfindungsgemäßen Schleifscheibe;
• Fig. 2 eine Ansicht, teilweise im Schnitt, in Richtung der Pfeile II-II von Fig. 1;
• Fig. 3 in stark vergrößertem Maßstab den in Fig. 2 mit III bezeichneten Ausschnitt am Außenumfang der Schleifscheibe;
• Fig. 4 in weiterer ausschnittsweiser Darstellung eine Variante zum ausführungsbeispiel der Fig. 3;
• Fig. 5 bis 9 fünf weitere Ausführungsbeispiele in Darstellungen ähnlich Fig. 4;
• Fig. 10 eine äußerst schematisierte Darstellung zur Er­läuterung eines Anwendungsbeispiels der erfindungs­gemäßen Schleifscheibe.

Embodiments of the invention are shown in the drawing and are explained in more detail in the following description. Show it:

• Figure 1 is a plan view of an embodiment of a grinding wheel according to the invention.
• Fig. 2 is a view, partly in section, in the direction of arrows II-II of Fig. 1;
• 3 shows, on a greatly enlarged scale, the section designated III in FIG. 2 on the outer circumference of the grinding wheel;
• FIG. 4 shows a variant of the embodiment of FIG. 3 in a further cutout;
• 5 to 9 five further exemplary embodiments in representations similar to FIG. 4;
• Fig. 10 is an extremely schematic representation for explaining an application example of the grinding wheel according to the invention.

1 and 2, 10 designates a grinding wheel, the central region 11 of which is thicker and the peripheral region 12 of which is thinner. An edge 13 of the grinding wheel 10 consists of an abrasive material, as will be explained in more detail below in relation to FIG. 3.

The grinding wheel 10 is provided with a polygonal receiving opening 14. In the embodiment of Figs. 1 and 2, the receiving opening 14 has the shape of a polygon, e.g. a P3G polygon according to DIN 32 711, but it goes without saying that instead of a triangle, a square or pentagon or some other non-rotationally symmetrical shape can also be selected.

The axis of the grinding wheel 10 is designated 15.

Fig. 3 shows the section III of Fig. 2 on an enlarged scale and in further details.

As can clearly be seen, the grinding wheel 10 essentially consists of a metal wheel 16 which is provided with two radial surfaces 17 and 18 in the thinner, peripheral region 12. These surfaces can project axially towards the edge 13, shown at 19 in FIG. 3. The surfaces 17 and 18 of the thinner, peripheral region 12 merge into the thicker, central region 11 via conical transition surfaces 20, 21 or cylindrical shoulders 22 attached to them.

The edge 13 made of abrasive material is attached, preferably glued, to a conical edge surface 23 on the periphery of the peripheral thinner region 12. The conical edge surface 23 extends at a cone angle 24. The cone angle 24 is preferably 26 ° 34 '. This value is chosen because its tangent is just 0.5, which makes it easier to convert the path coordinates during the feed movement of the grinding wheel and / or the workpiece.

As the further detail at the edge 13 of FIG. 3 shows, the abrasive material consists of CBN grains 25, which are embedded in an investment compound 26. The investment material 26 can be, for example, a ceramic, a synthetic resin or a galvanized or sintered metal.

The edge 13 has a main cutting surface 30 and a secondary cutting surface 31 which run at an angle of 90 ° to one another. The secondary cutting surface 31 preferably runs parallel to the conical edge surface 23.

32 with a flat rear surface of the edge 13 is referred to, which merges on the inside via a projection 33 into the first surface 17. This means that the edge 13 can be made wider in the axial direction than the peripheral, thinner region 12.

During grinding, the grinding wheel 10 engages with the main cutting surface 30 on the workpiece. With 37 the direction of the main force component of the grinding force is illustrated. The direction 37 runs parallel to a direction 36 of the workpiece axis.

The alternative shown in FIG. 4, in which the letter "a" is added to the corresponding reference number, differs from the exemplary embodiment in FIG. 3 essentially in that it is not a conical but a cylindrical edge surface 23a that is provided on the periphery of the thinner region 12 to which the edge 13a is applied, in particular glued on.

Otherwise, the edge 13a again has a main cutting surface 30 and a secondary cutting surface 31, which run at the same angles as was the case in the exemplary embodiment in FIG. 3. However, at the edge 13a of FIG. 4, due to the cylindrical edge surface 23a, there is also a front surface 34 which runs flat and merges flush with the third surface 19.

In the embodiment of FIG. 4, the thinner area 12a is also widened in both axial directions, as indicated by 38 and 19a.

Otherwise, the conditions correspond to those of the exemplary embodiment in FIG. 3.

5 shows a further variant in which the letter "b" is added to the reference symbols already used.

In Fig. 5, the thin edge 12b is bent off at 60 at the outer end, so that a conical edge surface corresponds to 23b. The angle of the cranked area 60 is chosen equal to the angle 24 of preferably 26 ° 34 '. The conical edge surface 23b is thus perpendicular to the direction 37, in which the main force component acts on the edge 13b during grinding. With 30b there is again a main cutting edge and with 31b a perpendicular cutting edge. Around edge 13b too To hold it positively in the radial direction inwards, the cranked region 60 can be provided on its inner circumference with a ring 61 which projects beyond the conical edge surface 23b in the direction of the cranking.

6 shows a further variant in which reference numerals are provided with the letter "c". Here, too, a cranked area 60c of the thin area 12c is provided, but the edge 13c is of two-leg design in radial cross section with an outer leg 13c / 1 and an inner leg 13c / 2, which rests on the conical edge surface 23c. An outermost circumferential line 64 of the bent-off area 60c is covered on both sides by the edge 13c, so that a positive connection also occurs in this way when a force acts on the edge 13c parallel to the conical edge surface 23c. The main cutting surface 30c merges radially inwards into a conical surface 65, in order in this way to achieve a continuous transition to the cranked region 60c.

In the variant of FIG. 7, the reference symbol of which the letter "d" is added, a conical annular groove 70 is introduced into a non-cranked thin region 12, one boundary surface of which is a conical edge surface perpendicular to direction 37 and the other boundary surface of which is a conical edge surface parallel to direction 37. The embodiment of FIG. 7 is particularly preferred because it is of a very simple construction.

In the embodiment of FIG. 8, the letter "e" is added to the reference symbol and it can be seen that the narrow edge 12e is again bent at 60e. On the outer circumference of the cranked area 60e, however, there is a cylindrical outer surface 75, to which an edge 13e is applied, which has a pent roof shape in cross section. Viewed from the direction 37, the main cutting surface 30e merges into a radial surface 76, which is formed both by the edge 13e and by the cranked region 60.

Finally, the embodiment of FIG. 9 shows yet another example in which the letter "f" is added to the reference numerals. Here, too, the thin region 12f is bent off at 60f on the outer edge. In the cranked area, however, a cylindrical circumferential annular groove 80 is introduced, which holds the edge 13f - in the illustration in FIG. 9 - positively to the left, while the edge 13f to the right again forms a radial surface 76f, as already shown in FIG. 8 has been described.

10 shows an example of a typical application of the grinding wheel 10d according to the invention.

A workpiece 90, for example a shaft, is subjected to external cylindrical grinding in the machining process illustrated in FIG. 5. 91 is the raw size and 92 the finished size of the workpiece 90.

The following process parameters can typically be selected here:

The radius r of the grinding wheel 10d is approximately 300 mm and the radial width b of the edge 13d is approximately 5 to 15 mm. The axial thickness d of the peripheral region 12d is approximately 15 mm and that of the central region 11 of the grinding wheel 10 is approximately 25 mm.

The workpiece 90 can have a diameter between 5 and 250 mm, the difference between the raw dimension 91 and the finished dimension 92 being in the order of a few millimeters.

The grinding wheel 10d is now rotated at a speed at which the peripheral speed is between 100 and 300 m / s. In contrast, the peripheral speed of the workpiece 90 is between 65 and 200 m / min. The axial feed rate indicated by 95 in FIG. 10 is of the order of magnitude between 150 and 2000 mm / min.

With these process parameters, a helicoidal transition 93 is established between the raw dimension 91 and the finished dimension 92, which due to the very high axial feed speed results in an overlap 94, so that no spiral grooves (so-called "flagpoles") on the finished circumference of the workpiece 90 with finished dimension 92 ) occur.

Grinding wheel 10d and workpiece 90 rotate in opposite directions, as illustrated by arrows 96 and 97. The edge 13d processes the workpiece 90 in the area of the helicoidal transition 93 with the main cutting surface 30d, while the secondary cutting edge 31d rests on the finished surface of the workpiece 90 with the finished dimension 92.

Claims (15)

1. grinding wheel for grinding workpieces (90), with a metal disc (16) which is essentially rotationally symmetrical with respect to a first axis (15) and which is provided on its circumference with a narrow edge (13) made of bound CBN grains (25), characterized in that the edge (13) has two conical cutting surfaces (30, 31) inclined to the first axis (15) which intersect at an angle of essentially 90 °, one of the cutting surfaces (30) being the main cutting surface (30b, 30c, 30d) perpendicular to a second axis (36) of the workpiece (90). 2. Grinding wheel according to claim 1, characterized in that the edge (13; 13b; 13c; 13d; 13f) is applied to a conical edge surface (23; 23b; 23c; 70) of the metal wheel (16). 3. Grinding wheel according to claim 2, characterized in that the conical edge surface (23b; 23c; 70 as an abutment for the main cutting surface (30b; 30c; 30d) is at least partially perpendicular to the second axis (36). 4. Grinding wheel according to one or more of claims 1 to 3, characterized in that the edge (13b; 13c; 13d; 13f) in the area of the main cutting surface (30b; 30c; 30d; 30f) perpendicular to the second axis (36) is held. 5. Grinding wheel according to one or more of claims 2 to 4, characterized in that the edge (13) is glued to the edge surface (23). 6. Grinding wheel according to one or more of claims 1 to 5, characterized in that the main cutting surface extends at an angle of 63 ° (26 ') to the first axis (15). 7. Grinding wheel according to claim 2 and 6, characterized in that the other cutting surface (31) runs as a secondary cutting surface parallel to the conical edge surface (23). 8. Grinding wheel according to one or more of claims 1 to 7, characterized in that the edge (13) projects axially over the metal wheel (16). 9. grinding wheel according to one or more of claims 1 to 8, characterized in that the radius (r) of the grinding wheel (10) is about 300 mm and the radial width (b) of the edge (13) is 5 to 15 mm. 10. Grinding wheel according to one or more of claims 1 to 9, characterized in that the metal wheel (16) has a thicker central area (11) and a thinner peripheral area (12), and that the peripheral area (12) about 1 / 10 to 1/2 of the thickness of the central region (11). 11. Grinding wheel according to claim 9 and 10, characterized in that the peripheral region (12) 15 mm and the central region (11) are 25 mm thick. 12. Grinding wheel according to claim 10 or 11, characterized in that the regions (11, 12) merge into one another via conical transition surfaces (20, 21). 13. Grinding wheel according to one or more of claims 10 to 12, characterized in that the peripheral region (12) is thickened in its section adjacent to the edge (13). 14. Grinding wheel according to one or more of claims 1 to 13, characterized in that the receiving opening (14) is designed as a polygon. 15. Use of the grinding wheel (10) according to one of the preceding claims for external cylindrical grinding of workpieces with a diameter between 5 and 250 mm at a grinding wheel peripheral speed between 100 and 300 m / s, a workpiece peripheral speed between 65 and 200 m / min and an axial feed speed between 150 and 2000 mm / min.

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