EP0351543B1 - Polishing disc - Google Patents

Description

The invention relates to a grinding wheel with stress on the wheel circumferential surface, the wheel side surfaces and the transition areas forming these surfaces, the grinding wheel being divided into two axially adjustable dividing discs and the circumferential discs alternately having claw-like intermeshing grinding segments. Such a grinding wheel is known for example from DE-C-290 422.

There are grinding operations in which not only the circumference of a grinding wheel is used straight or at a certain angle below 90 ° for chip removal, but also where the grinding wheel side is used for grinding. A typical example is the bearing seats of crankshafts, where, in addition to the connecting rod or the crankshaft bearing seat itself, transition radii on both sides and the bearing shoulders on both sides have to be ground 90 ° to the seat. Here, the side surfaces of a grinding wheel calibrated to the exact seat width are heavily stressed because the shoulder height must be pierced as quickly as possible. The corresponding wear at the transition point from the radius to the side face of the grinding wheel is adjusted and renewed in the case of conventional grinding wheels made entirely of corundum or silicon carbide by frequent heavy dressing on the circumference. This process leads to high grinding wheel consumption. In the case of superhard abrasives, such as diamond or cubic crystalline boron nitride (CBN), the entire grinding wheel does not consist of the abrasive, but a layer of coating is on the circumferential surface of a support body and, if applicable, the areas adjacent to the side of the wheel applied from the mentioned super hard bonded abrasive of less than a few millimeters. This is necessary for economic reasons because of the high-quality abrasive, but also possible for technical reasons because experience has shown that with the harder abrasives, higher grinding performance and a long service life between dressing cycles can be achieved. With, for example, diamond or CBN-coated grinding wheels, up to 1000 times longer tool life is achieved between dressing processes. The dressing processes on the circumference are only a few microns per cycle, so that the wear of such abrasives can be limited to a few millimeters. A problem with the use of such grinding wheels with a layer of superhard abrasives in grinding operations with side loading of the grinding wheel is that the grinding wheel becomes narrower with each dressing process and the seat width, for example a crankshaft, changes undesirably.

Solutions are already known which can be used to reduce the influence of the abovementioned high grinding wheel consumption on grinding wheels which are also stressed on the side surfaces of the wheel but are uncoated. DE-PS 290 422 describes a grinding wheel of the type mentioned at the outset, in which the distance between the two partial wheels, which are provided with alternating claw-like grinding segments, can be changed to adjust the overall width of the grinding wheel. This change in the mutual spacing of the indexing disks is accomplished by turning a nut which engages in a thread fastened in the indexing disk. Special means must be provided to keep the indexing disks in the set position.

It is an object of the present invention to develop a grinding wheel of the type mentioned at the outset in such a way that the grinding wheels can be used for grinding operations with stress on the side surfaces of the wheel while maintaining high accuracy over the entire circumference of the grinding wheel and adjustment of the indexing wheels can be carried out easily and quickly.

According to the invention, this object is essentially achieved in that the indexing disks are designed as indexing disk support bodies with a layer covering of diamond, crystalline boron nitride (CBN) or the like Adjusting elements having a cylindrical basic shape are arranged on a pitch circle which is concentric with the partial disk support bodies and bear an adjusting thread cooperating with an internal thread of one partial disk support body over part of their length, while free end faces of the adjusting elements are each intended for contacting the other partial disk support body and the adjusting elements on another Part of its length has a drive toothing which interacts with a drive toothed ring which is in drive connection with all adjusting elements.

Due to the use of super hard coated part body, a longer service life and thus a higher precision of the grinding operation is guaranteed. Due to the nature of the axial adjustment of the partial disk body via jointly adjustable adjusting elements, it is ensured that the disk side surfaces have a constant distance over the circumference, the adjustment being quick and easy to carry out. The threads have the fineness required for the accuracy of the compensation of the worn lining thickness.

In order to ensure a small joint spacing of the alternating claw-like interlocking grinding segments, these are - in plan view - preferably essentially triangular or trapezoidal, with the larger base lying on the outer edge of the associated part-disk support body.

In order for the grinding surface to be formed as uniformly as possible, it is also expedient to design the grinding segments of the two part-disk support bodies essentially identically to one another.

It is indeed possible to form the grinding segments in one piece with the respective partial disk support body. However, it is more economical for production and operation if the grinding segments and / or the layer covering are fixed to the preferably metallic base body of the respective partial disk support body, for example via annular groove connection surfaces, e.g. are cemented on. This gives you the required reliable fit during operation, but on the other hand it can be replaced if necessary.

In an advantageous embodiment of the invention, the device for axially adjusting the partial disk support bodies relative to one another has adjusting elements arranged on the pitch circle at the same angular distance. As a result, if, for example, the adjusting elements are provided at an angular distance of 20 °, a particularly uniform adjustability is ensured while maintaining the required accuracy over the entire circumference of the grinding wheel.

The drive toothed ring can be arranged concentrically with the two partial disk support bodies and can be in drive connection with all adjusting elements. This ensures that the two partial disk support bodies can be adjusted uniformly over their entire circumference with little structural effort.

The drive toothed ring can be driven, for example, by a drive pinion mounted in the partial disk support body. This also ensures simple actuation of the grinding wheel to compensate for the worn covering thickness.

This also helps if the drive pinion has an engagement recess for a drive tool on the end face. The drive pinion can also be designed at one end of its axis, for example as a hexagon or the like, so that it can be attacked with a drive tool.

In a further embodiment of the concept of the invention, the two part-disk support bodies can be clamped together by means of tensioning screws, in each case in the position which permits the position of the adjusting elements. In the tight The position of the partial disk support body, which does not have the internal thread for receiving the adjusting elements, lies evenly all around on the free end faces of the adjusting elements.

The adjusting elements can be essentially hollow cylindrical and the tensioning screws can be passed through the adjusting elements. In this way, a compact and reliable solution is found, the two part disk support bodies advantageously always being clamped together precisely at the points at which the adjusting elements also act as spacers. This ensures high latitude accuracy.

It is also possible to firmly screw the grinding wheel to a flange of the grinding spindle. Here, grinding spindle bearings are preferably provided on both sides of the flanges of the grinding spindle. When changing the grinding wheel, the entire spindle set is changed. This means that the lateral run (runout) remains unchanged if, e.g. when changing the grinding wheel the grinding machine is converted to another grinding task.

Further advantages and possible uses of the present invention result from the following description of exemplary embodiments with reference to the drawing.

Fig. 1

im Radialschnitt die obere Hälfte einer die Erfindung aufweisenden Schleifscheibe,

Fig. 2

die Ansicht A der Schleifscheibe gemäß Fig. 1,

Fig. 3

einen Teilschnitt durch eine Schleifscheibe gemäß Fig. 1 im Bereich des gemeinsamen Antriebs der Nachstellelemente,

Fig. 4

in Seitenansicht (teilweise weggebrochen) eine Schleifscheibe gemäß Fig. 1, und

Fig. 5

eine (als Drahtmodelldarstellung wiedergegebene) Schrägansicht einer die Erfindung aufweisenden Schleifscheibe auf einer Schleifspindel mit zwei seitlichen Schleifspindellagern.

Show it:

Fig. 1

in radial section the upper half of a grinding wheel having the invention,

Fig. 2

the view A of the grinding wheel of FIG. 1,

Fig. 3

1 in the area of the common drive of the adjusting elements,

Fig. 4

in side view (partially broken away) a grinding wheel according to FIG. 1, and

Fig. 5

an oblique view (reproduced as a wire model representation) of a grinding wheel according to the invention on a grinding spindle with two lateral grinding spindle bearings.

The grinding wheel 9, which is subjected to stress on the wheel side surfaces 15 for grinding operations, has a layer covering 16 of diamond, crystalline boron nitride (CBN) or the like, super hard bonded grinding materials of a few millimeters on its wheel peripheral surface 14 and on the adjoining regions of the wheel side surfaces 15 of a wheel carrier body 17. The disk body 17 is subdivided into two disk-like, preferably metal, part-disk support bodies 1, 2, which are axially adjustable relative to one another and have claw-like interlocking engagement segments on their outer circumference across the entire width of the grinding disk 9, carrying the abrasive coating 16 or formed therefrom. In the case shown, the two partial disk support bodies 1, 2 themselves have claw-like projections distributed over their circumference, which are coated, for example, with diamond grain or CBN on the outside diameter and on the sides. The ceramic-bonded grinding segments 3, 4 are cemented onto the part-disk support bodies 1, 2 with annular groove connection surfaces 18. A direct coating of the claw-shaped lugs of the two part-disk support bodies 1, 2 is also conceivable.

For the axial adjustment of the pulley support bodies 1, 2 relative to one another, a plurality of adjustment elements 5 - in the illustrated case 9 - arranged on one and the same pitch circle are provided in the one disk support body 1, which in one section have an adjustment thread 5 'on their cylindrical outer circumference, which is provided with a Internal thread 19 of the part-disc support body 1 cooperates, carry and in a section facing the other part-disc support body 2 a drive toothing 5 ''. The drive teeth 5 ″ of all adjusting elements 5 are constantly in engagement with a drive toothed ring 6. The drive toothed ring 6 is driven by one or more drive pinions 7 (see FIG. 2) via its toothing 7 '. When the drive pinion 7 rotates by means of a tool which engages in the engagement recess 21, all the adjusting elements 5 are rotated uniformly via the drive ring 6 and adjusted by the same amount via the adjusting thread 5 '. With clamping screws 8, each of which passes through the hollow cylindrical adjusting elements 5, the two partial disk support bodies 1, 2 are braced against one another in such a way until the partial disk supporting body 2 rests with its inner side face against the free end faces 20 of the adjusting elements 5.

The entire grinding wheel 9 is firmly screwed to a grinding spindle 10 via a flange 11 by means of bolts 22 (FIGS. 1 and 4). On both sides of the grinding wheel 9, grinding spindle bearings 12, 13 are provided on the grinding spindle 10 (FIG. 5), which are part of the grinding spindle 10 as ring bodies. The entire spindle set is changed when the grinding wheel is changed. The lateral run (stroke) is unchanged when the grinding machine is converted to a different grinding task, for example.

Reference symbol list:

1

Partial disk support body

2nd

Partial disk support body

3rd

Segments

4th

Segments

5

Adjuster

5 '

Adjustment thread

5 ''

Drive teeth

6

Drive gear ring

7

Drive pinion

8th

Turnbuckles

9

Grinding wheel

10th

Grinding spindle

11

flange

12th

Grinding spindle bearing

13

Grinding spindle bearing

14

Disk peripheral surface

15

Disk side surface

16

Layer covering

17th

Disc support body

18th

Ring groove connection surfaces

19th

inner thread

20th

End faces

21

Intervention deepening

22

bolt

Claims (12)

1. A grinding wheel with stress on its circumferential surface (14), its side surfaces (15) and the transitional areas forming these surfaces, the grinding wheel being divided into two wheel components axially adjustable relative to one another and the wheel components having alternating claw-like interlocking grinding segments (3, 4) on their periphery, characterised in that the wheel components are in the form of wheel component bearing members (1, 2) with a coating (16) of diamond, crystalline boron nitride (CBN) or similar super-hard abrasives on the stressed surfaces, and the bearing members (1, 2) are axially adjusted via adjustment members (5), the adjustment members (5) having a basically cylindrical shape and being disposed on a pitch circle concentric with the bearing members (1, 2) and, over part of their length, having an adjusting thread (5') co-operating with an inner thread (19) of one bearing member (1), whereas projecting end faces (20) of the adjustment members (5) are adapted to abut the respective other bearing member (2) and, over another part of their length, the adjustment members (5) bear driving teeth (5''), which co-operate with a driving-tooth ring (6) in common driving engagement with all the adjustment members (5).
2. A grinding wheel according to claim 1, characterised in that the grinding segments (3, 4) in plan view are substantially triangular or trapezoidal.
3. A grinding wheel according to claim 2, characterised in that the grinding segments (3, 4) on both bearing members (1, 2) are substantially identical in shape.
4. A grinding wheel according to claim 2 or 3, characterised in that the grinding segments (3, 4) and/or the coating (16) is secured, e.g. cemented, to the preferably metal base part of the respective bearing member (1, 2) via connecting surfaces (18) in the form of annular grooves.
5. A grinding wheel according to any of claims 1 to 4, characterised in that the adjustment members (5) on the pitch circle are disposed at equal angular distances.
6. A grinding wheel according to any of claims 1 to 5, characterised in that the driving-tooth ring (6) is disposed concentrically with the two bearing members (1, 2).
7. A grinding wheel according to any of claims 1 to 6, characterised in that the driving-tooth ring (6) is drivable by a pinion (7) mounted in one bearing member (1).
8. A grinding wheel according to claim 7, characterised in that the end face of the pinion (7) has a recess (21) for engaging a driving tool.
9. A grinding wheel according to any of claims 1 to 8, characterised in that the two bearing members (1, 2) are clamped together by bolts (8).
10. A grinding wheel according to claim 9, characterised in that the adjustment members (5) are roughly hollow cylinders, and the bolts (8) go through the adjustment members.
11. A grinding wheel according to any of claims 1 to 10, characterised in that it can be tightly screwed to a flange (11) of the grinding spindle (10).
12. A grinding wheel according to claim 11, characterised in that grinding-spindle bearings (12, 13) are provided on both sides of the flange (11) of the grinding spindle (10).

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