DE1652134A1 - Grinding process and grinding wheel - Google Patents

Description

DR.-ING. DIPL-ING. G. RIEBLING PATENT ADVOCATE My sign

IU 136 Gö '/ room

Please repeat in the answer

899 Lindau (Bodensee) Your message from My message from Rennerle 10 PO Box 365

February 28, 1967

NORTON ABRASIVES LIIYIITED, Bridge Road East, llJeliuyn Garden City, Hertfordshire / England

Grinding experience and grinding wheel

The present invention relates to a method for grinding a workpiece surface to remove defective ones Make and generate a proportionate smooth surface and grinding wheels for use in such a process.

The invention particularly relates to grinding relatively large workpieces, it is z. B for

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Fernichrtlbar: Office hours Bank account: Pottecheckkonto:

06 4374 patent from the agreement Bayer Staattbank Lindau (B) No. 1M9 Manchen 2M2S

Beard-en

the grinding won steel plates and usable, before these workpieces are rolled into sheet metal. Such a The grinding process is commonly known as cast cleaning or rough grinding and involves removing a relatively large amount of FlatBrial to a surface to get that free from blemishes or Errors are that would otherwise remain during the rolling process and the finished sheet or the Sheet metal strips would spoil.

In this type of grinding process with a grinding wheel For a given type of abrasive and a given degree of hardness, it has been found that the grinding efficiency (expressed as a ratio of the total metal removed to the disc wear) increases, when the average particle size is increased; and diBs is especially observed when the Abrasive type has a high resistance to breakage. However, it has also been observed that the finished Surface roughness increases as the particle size is increased and, in some cases, when relatively small fine finished surface is required, it was not always possible to use a composition which had the highest grinding efficiency. Such rough surfaces could of course with a

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Grinding wheel of smaller particle size grinded again ujerden, but this would be more expensive than if van Start with a grinding wheel with a smaller particle size and slightly lower grinding efficiency of the used would be.

Cast plastering operations are often performed by pendulum M

Rahnifjnschl ei f he can be used on which the grinding wheel is moved in a plane or by "manual methods" on a stand machine in which the article to be ground is moved in one plane. It was observed that in both cases the greatest grinding work through the outer parts or edges of the grinding wheel appears to be running and the disc develops a convex grinding surface.

Another very important type of machine is the automatic or mechanical plate or billet cleaning machine in which the disc is substantially perpendicular to that relatively uneven plates or flat surfaces is held under high pressure pneumatically or hydraulically is pressed onto the workpiece in a is moved in the axial direction along the workpiece (or the jerk piece moves in a similar line relative to Jerr stationary grinding head) and at the end of the movement in

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one direction of the grinding head adore the workpiece is switched to the side, whereupon the movement repeated in the opposite direction. Again it was established that the main work is done by the outer parts or edges of the grinding wheel, the movement in one direction first causes the wear of the front edge of the grinding wheel and the reverse movement that the opposite edge, which in turn leads to formation an essentially convex disk surface.

The present invention provides a method for Smoothing of a workpiece, the workpiece with the peripheral surface of a rotating grinding wheel in Contact is made, the peripheral surface a first Area of relatively high grinding efficiency and Binsn second surface area of relatively contains low grinding efficiency. The first surface area in another radial Distance to the ScheibBnachsB is arranged as the second Surface area during which relative movement is effected between the workpiece and the dBr grinding wheel, in such a way that that the workpiece comes into contact with the second surface area after it comes into contact with the first surface area came into contact, the relative movement was a component of movement parallel to the axis of rotation BB of the disk,

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whereby the workpiece is given a finish grinding, which is better than having the workpiece alone with you the first area would have been brought into contact, while the achieved grinding efficiency is greater as if the workpiece is only allBin with dBm second Bbreich been brought into contact wMtb.

The invention also provides a grinding wheel, dBren Circumferential area a first area of relatively contains high grinding efficiency and a second region of relatively low grinding efficiency, wherein the first area is arranged at a different radial distance from the disk axis than the second Area.

The invention is particularly applicable to Bußputz- or Grschleif operations in which a grinding wheel is brought into contact with the workpiece, while a relative movement between the grinding wheel and the Workpiece with a motion componentB parallel to the SchleifBcheibenachBB takes place and the grinding wheel is usually moved over the workpiece in a Biner path, which is essentially parallel to the grinding wheel axis runs. In the UsrglBich with well-known oil processes Kind in which the grinding wheel has a circumferential surface of

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Has uniform SchlBifujirkungsgrad, includes the present invention the use of a grinding wheel, the circumferential surface of which has at least one area, whose grinding efficiency is higher than that of another Area.

lilenn diB invention thus z. B. used in conjunction with a known Gußputz- odBr rough grinding process
tuird, ωά the grinding wheel is guided in a back and forth movement over the surface of the workpiece, the veneered grinding wheel is designed so that the grinding efficiency on each side of its circumferential surface is greater than in dBr center of the circumferential surface. The simplest constructive embodiment of such a grinding wheel is represented by a wheel which is formed from two outer layers of high grinding efficiency and an inner layer of lower grinding efficiency between the two layers.

If a cylindrical disc of this type in a cast plaster or an engraving process is used in which a Back and forth movement between the disc and the workpiece takes place, it has been shown that both express Edges of the disc circumference acquire a curvature in such a way that

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that the peripheral surface of the disc becomes somewhat convex. Continued grinding of the workpiece with the curved wheel then results in the production of a finer finished surface than would have been achieved using a wheel only from the material of the outer layers, while a grinding efficiency is achieved which is higher than that one with λ

a disc made only from the material dBr inner layer could achieve "

It should be noted that the disc can have a structure that differs from that just described can, for example, be designed in such a way that a continuous Consequence in the composition and the grinding efficiency van one peripheral edge of the disc to the opposite one Edge is present, the efficiency reaching a minimum in the middle of the circumferential surface, ™

Discs of this type are, however, relatively difficult and it is generally more practical to have the desired sequence of grinding efficiency over the circumferential surface of the wheel by assembling a number of layers of different grinding efficiencies to achieve, as in the case described above the three-layer disc. It goes without saying that the number of layers can be increased to more than three.

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Z, B, a disc with five layers can be formed by joining an inner layer of low grinding efficiency between two layers of higher grinding efficiency, whereupon two outer layers of even higher grinding efficiency can be applied.

All the different types of discs are used on both Circumferential edges arched when aie in a reciprocating motion Cast plaster vein grave grinding process used will. As a result, the workpiece is always first in contact with an area of higher grinding efficiency brought and finally comes into contact with an area of lower grinding efficiency, regardless of the Direction of relative movement between the disc and the workpiece. The presence of the curved ones Areas on the disc is an important feature of the method of the invention, and in some cases it will it may be desirable to provide the disks with such curvatures when they are manufactured, instead of to form these bulges only at the beginning of the grinding process.

Cast plastering and rough grinding where the grinding wheel instead of the reciprocating movement only being moved in one direction across the surface of the workpiece

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not common. In one case, however, ujürda did Method of the invention involves the use of a washer include, one peripheral edge of which has a higher grinding efficiency more than the other circumferential edge »The Disc could simply consist of two layers, one with a higher grinding degree than the other, or Bs could use a number of layers ^

which are arranged according to increasing grinding efficiency. Otherwise, the composition of a Biner disk made of a Binary piece can be changed from one peripheral edge to the other in such a way that a continuous increase in the grinding efficiency a on the peripheral surface is prevented. Whatever the particular structure chosen, the grinding process is handled in such a way that the peripheral edge B with a higher degree of grinding efficiency first comes into contact with the workpiece. This edge obtained βϊπβ curvature (or is produced so) and the results achieved are then similarly jBnen which have been described in connection with the reciprocating reciprocating type of Gußputz- or GrobschlsifVorganges, d, h _# a good finished surface is obtained, while a degree of grinding efficiency is achieved which is normally not possible in connection with such a grinding process.

The grinding wheels described above for use

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in the method of the invention are through the first Area v / an v / relatively high grinding efficiency characterized, which is at a smaller radial distance is arranged from the disk axis than the second area ν / απ relatively low grinding efficiency. When such discs are used it is possible to keep the plane of the disc in motion substantially at right angles across the workpiece to keep to the surface of the workpiece. In the other case, the disk can be at an acute angle with its plane to be moved towards the surface over the workpiece the relative movement between the disc and the workpiece. However, it is not possible to take advantage of the Obtain invention when the disc is moved over the workpiece, its plane being an obtuse angle to the surface of the workpiece occupies in the direction of relative movement.

In contrast, if a disk of a second type now to be described is used, the advantage of the invention can only be achieved when the disc is moved over the workpiece, its plane being a blunt Angle to the direction of movement. Discs of this second type are characterized by the first area of relatively high grinding efficiency, which in

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a larger radial distance from the disk axis is arranged as the second area. It will be appreciated that this second type of grinding wheel is in construction is completely opposite to the first type of grinding wheel.

Thus, a grinding wheel of the second type is so designed

forms that it has a lower grinding efficiency on each side of the peripheral surface than in the middle of the peripheral surface. The simplest structural embodiment of such a disk is one of two
outer layers of low grinding efficiency and an inner layer of higher grinding efficiency embedded between the two outer layers.

If a cylindrical disc of this type in one
Cast plastering or rough grinding is used, in which a back and forth movement takes place between the disk and the workpiece, it has been shown in the case of disks of the first type that the peripheral surface of the disk becomes slightly convex. Provided that the
above-mentioned obtuse angles between the washer and
the workpiece is adhered to, it has been shown that
that the workpiece has a finer end surface,

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as if a disc were used that only made from the material of the inner layer is while a grinding efficiency is achieved, which is higher than when a disc is used that would be made only from the material of the outer layers has been made.

As in the case of the disks of the first type, it is possible to construct the disks of the second type differently. Thus, the disc B can have a continuous sequence in composition and grinding efficiency from one peripheral edge of the disc to the opposite peripheral edge of the disc, with the efficiency reaching a maximum at the center line of the peripheral surface. In another case, the discs of the second type contain more than three layers, wherein the middle layer has a high Schleifw i rkungsgrad and the outer layers are provided with SchMfWirkungsgraden which decrease towards the edges of the disc out. All of these disks acquire a convex circumferential surface when used in the method of the invention if they have not already been made with such a surface.

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The invention becomes a Lü Dsug limitation with reference to the accompanying drawings described, uorin:

Figures 1, 2 and 3 show grinding wheels that are suitable for dia

Use in the practice of the invention are suitable; ^

Figures 1a _f 2a and 3a the contours of the peripheral surfaces of the

Grinding wheels of Figures 1, 2 and 3 show more clearly;

FIGS. 4, 5 and 6 show the various flexion farms

a grinding wheel over a workpiece represent,

As shown in Fig. 1a, it includes a grinding wheel 1 for each outer ring-shaped layer 2 high degree of abrasion, which consist of a relatively coarse abrasive and an inner annular layer 3 lower Grinding efficiencyBs that consist of a finer or more abrasive abrasives.

Such a composition of a grinding wheel Brgab the surprising result that, uisnn are in one

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Cast plastering or rough grinding process was used in which the disk has been reciprocated substantially parallel to its axis of rotation without undue B. Showing wear and tear on the inner layer resulted in a finished surface that was better than those from the outer coarse layer composition could be expected and at the same time a grinding efficiency was achieved which was higher than whoever expects the finer or more friable inner abrasive layer or layers could be.

Such a composition of layers can be formed into a single disk by known methods will. Layers can be made separately and then can be joined together to form a single disk, or layers can be made as separate disks and suitably mounted on a single spindle of a grinding machine to form a uniform layer structure of the desired layer distribution.

FIG. 1a illustrates in an exaggerated form the contour of the circumferential area MchB of the disk of FIG. 1 of the invention can diB grinding wheel 1 during

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their manufacture are formed with such a contour. Otherwise, the disk can be made cylindrical, with the circumferential edges of the disk then being curved at the beginning of the grave grinding process, so that the circumferential surface of the disk is somewhat curved outwards, as in FIG. 1a. It can be seen that as a result of this convex farm the work M

the surface of the piece with the circumferential surface exercises layer 3 last comes into contact in both the forward and backward movement of the disc over the Workpiece.

Figure 2 illustrates another type of disk which is suitable for use in accordance with the invention in a rough grinding or cast cleaning operation with to-and-fro movement of the disk. The grinding wheel k of FIG. 2 contains outer annular layers 5 of high grinding efficiency, annular intermediate layers 6 of lower grinding efficiency and an annular middle layer 7 of even lower grinding efficiency. 3a shows in an exaggerated form how the peripheral surface of the disk is formed during manufacture and how it is curved on the outside at the beginning of the grinding process, so that the peripheral surface of the layer 7 always comes into contact with the workpiece last

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comes and determines the type of final touch.

Dia Fig. 3 illustrates a grinding wheel that for use according to the invention in a grinding core Grinding process is suitable, in which the grinding wheel_only in one direction over the surface of the workpiece is moved. The grinding wheel 8 consists of an annular layer 9 of high grinding efficiency and an annular layer lower grinding efficiency and is used with the Layer 9 moved over the workpiece as the leading edge. At the beginning of the grinding process, the peripheral surface is obtained a bulge, as shown in exaggerated form in Fig. 3a. Otherwise the washer can so made. The grinding efficiency is comparable with that of a corresponding disk made only from the material of layer 9, while the final sanding of the surface is achieved is comparable to that of a corresponding disk that consists only of the material of layer 10.

FIGS. K and 5 illustrate alternative solutions in which a grinding wheel of the type shown in FIGS. 1 or 3 is moved over the surface of a workpiece 11. In each of the figures moves

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the disc in the direction indicated by the arrow. In Fig. 4, the grinding wheel 1 moves with its center plane at right angles to the surface of the workpiece 11. In Fig. 5, the grinding wheel 1 moves with its center plane at an acute üJinkel to the surface of the Ulerkstückas 11 in the direction of the movement of the disk. It can be seen that with the arrangement of FIG. 4 the grinding wheel 1 can simply be moved back and forth without changing its position at the end of each movement be reversed in order to obtain the desired acute angle between the center plane of the disc and the surface of the workpiece 11. Furthermore, the disc must be rotated at the end of jaden DurchgangsB to 1BQ in the case illustrates the grinding wheel of Fig. 3, so that the surface of the lower ä

Grinding efficiencyBs last with the surface dee Workpiece comes into contact.

The grinding wheels of Figures 1, 2 and 3 are allB of the kind in which the first area is proportionate high grinding efficiencyBs in lower radial Distance from the disk axis is arranged as the second area. Ea is from dar -eicht to understand that grinding wheels whose

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srstsr area of relatively close efficiency is arranged at a greater radial distance from the disk axis than a second area of relatively low degree of efficiency can be produced by simply reversing the constructions of the disks of FIGS. 1, 2 and 3. Thus, the grinding wheel of Fig. 1 can be modified in that the layers 2 have low grinding efficiency and the layer 3 has high grinding efficiency. Similarly, the grinding wheel of FIG. 2 can be modified in that layers 5 have lower grinding efficiency, layers 6 have higher grinding efficiency and layer 7 has higher grinding efficiency. The grinding wheel of FIG. 3 can also be modified in that the layer 9 has a lower grinding efficiency and the layer 1D has a higher grinding efficiency. It can be seen that the grinding wheels with the curved circumferential edge are produced in the manner described, or otherwise they achieve such a curvature at the beginning of the cast plaster or grave grinding process.

Figure 6 illustrates the manner in which the BB modified grinding wheels of the second type over the Surface of the workpiece are moved. The grinding

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Disk 12 moves under a blunt UiinkBl their flat plane to the surface of the workpiece in Direction of occupancy of the disc. The goal is ensure that the surface has the lowest grinding efficiency last came into contact with the workpiece. As can be understood, the angle of inclination the grinding wheel 12 reversed at the end of each pass, The disc is used in a reciprocating grinding operation.

In a particular example, a grinding wheel of the type shown in Fig. 1 was produced with two outer layers 2 of 25 mm thick made of sintered bauxite grains of grain size 1U _{1 held} together by a synthetic resin binder and an inner layer 3 of 25 mm thick made of sintered bauxite grains of Grain size 2D held together by the same resin binder. Layers 2 and 3 were also held together by the same resin binder to form a unitary whole.

This SchMfscheibe (hereinafter referred to as SchBibe A) was used in an automatic plate cleaning machine to smooth the surfaces of stainless steel pits, wherein the grinding wheel in a substantially parallel

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to the disk axis direction and its median plane was moved across the plate substantially at right angles to the surface of the workpiece, Ee also comparative contempt carried out by in the same Two grinding wheels of corresponding dimensions were used on the machine, one of 75 mm thick, Completely made of sintered bauxite of Carn size 14 (Disc B) and one of 75 mm thickness, completely sintered bauxite of size 20 (disc C).

Which was to be expected, it was found that the Abrasive efficiency of wheel B (expressed as the ratio of total metal removal from the plate for material abrasion from the disc) was higher than the of disk C, but that of the surface of the disk The final grinding given for the G was smoother. In the wheel A, on the other hand, was the grinding efficiency only slightly less than in the case of disc B, while the finish was only a little rougher than in the fall of disc C.

In another series of experiments, grinding wheels were made, different layers of grinding, medium of the appropriate grain size and the in the same automatic cleaning machine on austenitic

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Steel workpieces and on ferritic steel neckpieces have been checked. The grinding wheels are all of the same synthetic resin binder and all abrasives had a grain size of 14. The structure of the Grinding wheels was as follows:

Disk D was 75 mm thick and consisted entirely of M

Corundum.

Disk E mar composed of an inner layer

van sintered bauxite, embedded between

two outer layers of artificial corundum, jade

this layer was 25 mm thick.

Disk F mar composed of an inner layer of artificial karund, embedded between two outer layers of sintered bauxite, each of the layers was 25 mm thick.

Disk G was 75 mm thick and was made entirely of sintered bauxite.

The grinding efficiency B of these grinding wheels on austenitic steel and ferritic stainless steel was as follows, the efficiency being in each case as

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the difference between the metal removed in kg and dam disk wear volume was expressed in edm.

Washer D Washer E Washer F Washer G.

austenitic steel 14.5 35.3 38.9 44.7 f British steel 14.4 28.9 3D, 8 35.9

In both cases, the disk E produced a surface grind, the almost bd good uar like the one through the pane The disk F produced in both cases a surface finish which was worse than that produced by the Disk E produced but considerably better than that produced by disk G.

The invention ujurda with reference to the special Execution farms are described and it should be understood that it is not limited thereto. UIbIb changes and varieties are well within the scope of the invention possible. UiB has been described, the grinding wheels used in the invention can have layers thereof Loop materials, but different grain sizes, or Contains layers of different abrasives of the same grain size. Ea goes without saying that the layers also made of different materials of different grain sizes

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can exist.

Some of the materials and designs known heretofore can be used. Sintered bauxite and Corundum are particularly mentioned murders. However, other abrasives can also be used. Sintered However, bauxite is a preferred material because it ™ has such a high impact resistance. The production the grinding wheels can be made using such known designs such as hot pressing, using resin binders of known types.

Finally, it is noted that grinding wheels, the sheet-like layers of different composition of abrasive materials included are known, but that each composition is designed in previous cases, g to a complete grinding process to perform ainem part of a given article. Also, in some cases, very thin outer layers of a harder composition than the main body of the disc are used to prevent corner breakage or rapid wear when cylindrical shoulders and fillets are being performed or other similar operations.

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In addition, grinding wheels are known to Gußputzen or rough grinding, the annular layers towards the center from the periphery to increase the degree of hardness, than the same for the training ₌ Uerminderung the Umfangsgeschijindigkeit, Ünn the grinding wheel is worn out.

In one of these known cases, it is comparable to the present method, in which all layers cross the entire surface of the cheek piece almost simultaneously. Knowing this well-known l / could not experience it
lead to the prediction of the excellent combination of grinding efficiency and finish that the present invention provides.

In addition, the previously known grinding wheels of a cylindrical shape as compared with the disks of the present invention, the peripheral surface of which one Area of relatively high grinding efficiency which is arranged radially from the disk axis at a different distance than a surface area of relatively low grinding efficiency.

Claim ε *

1 0 9 ß 1 ίί / iU «

Claims (1)

Claims 1. A method for smoothing a piece of work, characterized in that the üJerkstück (11) with dBr circumferential surface of a rotating % Grinding wheel (1) is brought into contact with the peripheral surface a first surface area (2) of various contains proportionally high grinding efficiency and a second surface area (3) of relatively low grinding efficiency, the first surface area is arranged at a different radial distance from the disk axis than the second surface area, while a relative movement between the workpiece and the Grinding wheel takes place so that the ÜJerkstück through g the second surface area is touched after it has been touched by the first surface area, the relative movement a movement campDnenta parallel zur RatatiansachBB the grinding wheel contains, whereby the workpiece is given a finish cut, which is better is than the one who would be achieved if the work was done would only come into contact with the first area while achieving a grinding efficiency which is higher than that which would be achieved if the workpiece only - 26 - 109816/0485 would come into contact with the first area. 2, Uerfahren according to claim 1, characterized g e ke It shows that the relative movement is essentially parallel to the Ratatiansachae. 3. Uerfahren according to claim 1 wire 2, characterized g e k β η π ζ e i c h π e t that the grinding wheel is moved back and forth over the workpiece. k, Uerfahren according to claim 3, characterized in that the grinding wheel (1) contains two outer annular layers (2) of high grinding efficiency and embedded between the outer layers an inner annular layer (3) of low grinding efficiency, 5, method according to claim * »J characterized, that the grinding wheel the IJerkstück is moved, with its flitteleit im essentially at a right angle to the surface dBs üJerkstückas stands. 6. Uerfahren according to claim k _t characterized in that the SchlBifscheibe over - 27 - 1 09816/0 ^ 86 the workpiece is dimensioned, its central plane being a acute angle to the surface of the workpiece in the Direction of movement, 7. l / experience according to claim 3, characterized in that that the grinding wheel two outer annular layers of low abrasive λ efficiency and between the two outer layers embedded an inner annular layer van higher Contains grinding efficiency, with the middle band of Grinding wheel as it moves over the workpiece assumes an obtuse angle to the surface of the workpiece in the direction of movement. 8. A grinding wheel, labeled by a peripheral surface that has a first area of relatively high grinding efficiency " and a second range of relatively low Contains grinding efficiency, the first area at a different radial distance from the wheel axis is arranged as the second area, 9. Grinding wheel according to claim 8, characterized marked that the peripheral surface is slightly convex, - 28 - 1657134 10. Grinding wheel according to claim 8 or 9, characterized indicates that the first area is arranged at a smaller radial distance from the disk axis than the second area. 11. Grinding wheel according to claim 8 or 9, characterized marked that the first area in arranged a greater radial distance to the disk axis is as the second area. 12. Grinding wheel according to claim 8 or 9, characterized by two outer annular layers of a material with a relatively high Grinding efficiency and one between the two mussels Layers embedded inner annular layer of a material of relatively low grinding efficiency. 13. Grinding wheel according to claim 8 or 9, characterized in that by a number of juxtaposed annular layers that form a middle layer of relatively low grinding efficiency and outer layers of relatively high grinding efficiency contain. - 29 - 1Ö9816 / IUB5 1657134 14. Grinding wheel according to claim 8, characterized in that by an annular layer of relatively high grinding efficiency and a annular layer of relatively low grinding efficiency. 15. A grinding wheel according to claim 8 wheels 9, marked μ characterized by zuiei äusssre annular layers of a material of relatively low Schleifuirkungsgrad and an embedded between the two layers äusssren inner annular layer of material van relatively high grinding efficiency, 16. Grinding wheel according to claim 8 or 9, characterized by a number next to one another arranged annular layers that form a middle layer of relatively high grinding efficiency and external ^ Layers of relatively low sleep efficiency contain. 17. Grinding wheel according to a dBr claims 8 to 16, characterized in that the first region and the second region are composed of particles are made of the same abrasive material, üiobsi das Material of the first area has a larger grain size - 3D - 109816/0485 165? 134 than that of the second area. 18, grinding wheel according to claim 17, characterized characterized that diB particles consist of sintered bauxite. 19. Grinding wheel according to claim 17, characterized characterized in that the particles consist of artificial corundum. 2D. Grinding wheel according to any of claims 8 to 16, characterized in that the first region and the second region are composed of particles different abrasive materials are formed. 21. Grinding wheel according to claim 20, characterized characterized in that the particles are of the same size. 22. Grinding wheel according to claim 20 or 21, characterized in that the the first area and the second area are formed from sintered bauxite or synthetic corundum. 23 «grinding wheel according to one of claims 8 to 22, - 31 109816/0485 1657134 characterized in that the layers are bonded together to form a to form uniform grinding wheel. 2k, grinding billet according to claim 8 or 9, characterized by a continuous sequence of the grinding efficiency ES from one edge of the circumferential Λ face to their opposite edge. 25. Grinding wheel according to claim 2k, characterized in that dBr grinding efficiency reaches a minimum at the center line of the circumferential surface. 26. Grinding wheel according to claim 24, d a du r c h characterized that the grinding efficiency an IKlaximum at the center line of the circumferential surface achieved. ! t 27. Proceed »« »eighth B through, know ~ Schleiiiwlttiii» * ' «Η + ■ i ■ - ■ *! ' rn-t - * -t ^ iehe 1 bte .3; - «- * - * - ν e rejects that the / 28. Procedure for. Smoothing a workpiece _t as ςέ im H. wtfröe. - * "■■" Blank page