US3299580A

US3299580A - Internal grinding machines

Info

Publication number: US3299580A
Application number: US361648A
Authority: US
Inventors: Gluchowicz Gerszon
Original assignee: Ulvsunda Verkstader AB
Current assignee: Ulvsunda Verkstader AB
Priority date: 1963-04-24
Filing date: 1964-04-22
Publication date: 1967-01-24
Anticipated expiration: 1984-01-24
Also published as: SE308075B; GB1060981A; DE1477915A1; DE1477915B2; DE1477915C3

Description

1967 I G. GLUCHOWlCZ 3,299,580

INTERNAL GRINDING MACHINES Fig.1

lnvenior Gerszon Gluchowicz At tor ney G. GLUCHOWICZ INTERNAL Jan. 24, 1967 5 Sheets-Sheet 2 Filed April 22, 1964 Attorney Jan. 24, 1967 e. GLUCHOWICIZ 3,299,580

INTERNAL GRINDING MACHINES Filed April 22, 1964 5 Sheets-Sheet 3 Inventor Gerszon Gluchowicz Attorney 5 Sheets-Sheet 4 Inventor G'erszon Gluchowicz figm zzz w Ahorney G. GLUCHOWICZ INTERNAL GRINDING MACHINES m A 1 m w n m J n J i; m w e L 7 8 m m 4 E fi F Wu F 2 w n F irm F Jan. 24, 1967 Filed April 22, 1964 Jan 1. 24, 1967 Filed April '22, 1964 G. GLUCHOWICZ INTERNAL GRINDING MACHINES 5 Sheets-Sheet 5 inventor Gerszon Gluchowicz Attorney United States Patent 3,299,580 INTERNAL GRINDING MACHINES Gerszon Gluchowicz, Stockholm, Sweden, assignor to Ulvsunda Verkstader Aktiebolag, Bromma, Sweden, a corporation of Sweden Filed Apr. 22, 1964, Ser. No. 361,648 Claims priority, application Sweden, Apr. 24, 1963, 4,497/ 63 11 Claims. (Cl. 51-165) This invention relates to internal grinding machines.

More particularly this invention relates to internal grinding machines comprising a chuck carrying a work piece and a grinding wheel mounted on a spindle in a bracket both the chuck and the grinding wheel mounted to be rotatable about their axes and simultaneously displaceable axially \and radially for successive working olf of an internal revolving surface of the work piece.

The axial relative or reciprocating movement has for its purpose to allow a machining of revolving surfaces having a greater length than the thickness of the grinding wheel, and to achieve a higher degree of surface finish as well. Furthermore, the machines are provided with sharpening tools, generally with diamond tips made to rub off the grinding wheel at equal intervals, preferably before the completion of the grinding operation on the work piece to restore the grinding wheel to its correct geometric shape and make it more freely cutting.

The invention further relates to internal grinding machines in which a pneumatic measuring instrument is disposed with a gauge head provided with outlet nozzles for a pressure medium, preferably compressed air, to perform an axially reciprocating movement in and out of the work piece. Between the outlet nozzles and the revolving surface machined there is a gap causing a pressure drop when the air escapes through the nozzles, which drop is proportional to the size of the gap and which is utilized for affecting, for example, the radial feeding. In this known embodiment the measuring instrument is located at the opposite end of the work piece seen from the grinding wheel, it thus being pulled through the chuck supporting the work piece. The gauge is carried by a rod mounted inside the chuck spindle and besides rotationally stationary, which makes the bearing complicated and expensive. In addition, the rod must be actuated via the table, which complicates the structure still much more.

It has been suggested already to make the gauge head so that during the grinding process it may be disposed inside the work piece together with the grinding wheel as is disclosed in the British patent specification No. 849,524, for example. Also in this case the measuring instrument is placed behind the work piece on a rod extending through the chuck spindle.

According to another known method, the so-cal-led indirect measuring method, after sharpening by or dressing of the diamond and the grinding wheel generatrix in the transverse feeding direction having taken :a definite position in the machine, the cross slide is fed a constant distance towards the machined surface, the grinding wheel then being retracted. (Compare US. patent specification No. 3,003,293.)

During recent years the demands for extremely small tolerances have increased to such an extent that the devices hitherto known for measure control do not meet these demands, in particular in an automatic machine which over a long period of time shall be able to produce details with diameter tolerances within the scope of 0.00l-0.002 millimeter, without being adjusted.

One main object of the invention is to provide a meas-.

ure control system which meets very high demands in the respects set forth above.

A further object of the invention is to provide a measure 3,299,580 Patented Jan. 24, 1967 control system which in operation is more reliable and more accurate in respect of desirable measure control.

A still further object of the invention is to provide a measure control device which is simpler and cheaper than devices known in prior art.

Further objects and advantages of the invention will become apparent from the following description considered in connection with the accompanying drawings which form part of this specification, and of which:

FIG. 1 is a lateral, partly sectional view of an internal grinding machine embodying the main features of the invention and provided with a measuring device made according to the invention;

FIG. 2 is an enlarged sectional view following line IIII of FIG. 1 of a gauge head of a measuring instrument inserted in a grinding wheel;

FIG. 3 is "an enlarged partial view of the measuring instrument together with the grinding wheel and a work piece viewed in the same section as in FIG. 1;

FIGS. 4 and 5 show enlarged elevations, partly in section following lines IVIV and VV, respectively, of FIG. 1;

FIG. 6 is a lateral, partially sectional elevation of a modified embodiment of an internal grinding machine, the section being taken along line VI-VI of FIG. 7;

FIGS. 7 and 8 are top views of the same machine with parts assumed cut open and in two difi'erent operational positions;

FIG. 9 is a view of the measuring instrument along line IXIX of FIG. 6 and on a larger scale;

FIG. 10 is a lateral view of a grinding spindle bracket, and

FIG. 11 is a cross sectional view following line XIXI of FIG. 10.

In the various figures the same reference numerals have been used for equivalent parts.

Referring to the drawings, reference numeral 10 designates the machine support on which is mounted a head stock 12 in which a chuck 14 made so as to support the work piece 16 is rotatably journalled. A table 18 is displaceable on the support 10 in a reciprocal path in the longitudinal direction of the machine support and carries a bracket 20 in which an arbor or spindle 22 is rotatably journa-lled, which spindle supports the grinding wheel 24. The bracket 20 moves together with the table 18 in its reciprocal movement in the longitudinal direction of the support. In the embodiment shown in FIGS. l5, said bracket is adapted to perform simultaneously a lateral feeding movement, as it is mounted on a cross slide 26 displaceable transversally to the table on guides 28. The size of the oscillating movement of the table 18 can be set as well as that of the bracket 20, and there-through the lateral feeding movement of the grinding Wheel 24 also. The said parts of the machine are known per se and for this reason is not described more in detail.

A foot 30 of a measuring instrument generally designated with 32 is rigidly attached to the table 18 and therefore is entrained by said table in its oscillating movement in the longitudinal direction. The foot 30 is located between the bracket 20 and the grinding wheel 24 but does not participate in their transverse feeding movement. The measuring instrument comprises a gauge composed of a flange 34 and a head 36. The flange 34 is inserted in an annular groove 38 in the foot 30 having a recess 40 for the passage of the grinding spindle 22 or a coupling 42 for the same, respectively. The flange 34 is in a plane perpendicular to the spindle axis divided into two discs 44, 46 fixed into the foot 30 by means of screws 48 (FIG. 4), and at their interior periphery each terminating in

portions

49, 50 of the peripherally divided head 36. The

said portions have each the shape of a section-cylindric sleeve with a peripheral extension over slightly more than half a circle. The gauge head 36 is of such a shape that it fits into the crescent-like gap formed between the work piece 16 and the grinding spindle 22, when the grinding wheel is in its operational position inside the work piece 16, and thus grinds the internal face 52 of the work piece. The gauge head has a smallest internal diameter suflicient to make it possible to thread it over the spindle 22, as will be easily seen in FIG. 2, and which diameter may preferably be smaller than the external diameter of the grinding wheel, at least before the latter has been worn down to any large extent. The centre 51 for the inner (and outer) section-cylindric limiting surface of the gauge is at :a predetermined distance from the centre 53 of the grinding spindle 22, thus giving the spindle sufficient liberty of motion to perform the feeding movement in a radial direction.

The foot 30 has a supply passage 54 for the pressure medium and a branch 56 extending therefrom, which passage and branch end in two diametrically opposed passages formed in the flange 34. The said passages terminate in radical passages 60, which in turn continue in an axial passage 62 each formed in the gauge head 36. The passages have nozzle apertures 64 at two diametrically opposed places. The apertures 64 are located at the external surface of the gauge head close to its extreme end. The

passages

60, 62 are formed between the two

portions

49, 50 of the head prior to their assemblage. The gauge head 36 is of very little thickness in the radial direction in order to fit for grinding spindles of grinding wheels having a diameter of merely a few millimeters. Consequently, the total thickness of the

portions

49, 50 may be substantially less than one millimeter.

By a further passage or

duct system

66, 67, 68 and 70 a coolant, such as water, is supplied to the grinding Wheel 24. Said system ends, in contradistinction to the system described hereinbefore, axially at a point situated right between the apertures 64. Thus the coolant flows in an axial direction towards the grinding wheel 24.

A pressure source for a gaseous medium, preferably air, communicates with a duct 72 (FIG. 1) branching into two branch ducts 74, 76, which are controlled by choking means or throttles 78, 80. The branch duct 74 is via a duct 82 connected to the passage 54 in the measuring instrument 32. Another duct 84 extends to a valve 86 and from there through a duct 88 to a bellows 90 in an indicator device 92. The air supply to the duct 88 is shut off as soon as the gauge head 36 escapes from the workpiece 16. The valve 86 has a valve body actuated by a button 94, the body cooperating with an adjustable shoulder 96 located on the table 18. The button 94 keeps the valve 86 shut, until the shoulder 96 hits the button when the gauge head 36 has entered the work-piece 16. To the air supply duct 76 and between the throttle 80 and a throttle 98 discharging into open air and being adjustable to various values by means of a valve body 100 there is connected a duct 102 extending to another bellows 104 provided in the indicator means 92. The bellows 90, 104 are interconnected and separated from one another by a partition wall 106. Owing to the pressures prevailing in the

ducts

88 and 102 the partition wall 106 is displaced into various axial positions which may be read off on a scale 112 by means of a transmission means 108 and a hand 110. The partition wall 106 also carries a pin 114 following the same and closing the current between two

contacts

116, 118, When the hand 110 has reached a predetermined preset value, normally the -point on the scale 112. The

contact arms

116, 118 are included in an electric circuit cutting off the current supply to the grinding machine in such a manner as to interrupt the grinding operation when the preset value has been reached.

To perform a grinding operation the table 18 with the grinding wheel 24 is inserted into the work-piece 16. The button 94 is now hit by' the shoulder 96, so that the same air pressure will prevail in all the ducts connected to the branch duct 74 behind the throttle 78. Among the said ducts the duct 82 communicates with the passages of the gauge, and a pressure will prevail in the duct 82 which is dependent on the distance of the nozzle apertures 64 from the internal face 52 of the work-piece 16. This distance grows as the grinding operation proceeds, which results in a pressure drop in the duct 82, and from there through the ducts 84, 86 in the bellows 90. On the .other hand, the pressure in the other branch duct 102 will remain at a constant value set by the valve body 100. The hand moves towards the 0-point of the scale 112 according to FIG. 1, and when the

contacts

116, 118 get in touch with one another the grinding operation is interrupted. The face 52 of the work-piece 16 has got the desired diameter with an accuracy that may be of a magnitude of one thousandth of a millimeter.

The grinding wheel 24 is sharpened or dressed by means of a tool generally designated with 120 (see especially FIG. 5) and provided with a diamond tip 122 adjustable by means of a screw 124 and a setting wheel 126. The tool 120 is pivotally mounted on a horizontal shaft 128 located on a bracket 130 which is rigidly attached to the support 10. The dressing .of the grinding wheel is performed in a well-known manner, generally after a first grinding process has been completed but before the grinding of the work-piece is finished. The dressing tool 120 is brought down towards the grinding wheel 24 and through the dressing the generatrix of the grinding wheel acting on the work-piece 16 gets an accurate position, so that it can perform the final grinding to the set measure of the diameter of the machined surface.

This mode of operation presumes that the diamond tip 122 has a fixed position in the machine. This position is checked by means of the embodiment shown in FIG. 5 comprising a measuring instrument generally designated with 132 and through a passage 134 communicating with a pressure source, preferably for compressed air. The passage has a nozzle 136, which normally covered by a washer 138 actuated by a spring 140. By supplying compressed air when the dressing tool takes its inactive position as shown in FIG. 5, the washer 138 which suitably is made of a hard material will swing 'out, until it bears on the tip 122. Owing to the position of the tip a gap will arise between the nozzle 136 and the washer 138, which, in turn, affects the pressure in the passage 134. The passage 134 is included in a system of compressed air passages of the same kind as described hereinbefore. An indication means corresponding to the indicator 92 is thus provided with a hand set to point at a certain point, such as the 0-point, when the diamond tip 122 takes the set position. In the embodiment illustrated in the FIGURES 1 through 5, any deviations are corrected manually by turning the set wheel 126, although it may be possible to arrange for an automatic adjustment, if desired.

By means of the said setting device the diamond tip is caused to take its correct position while taking into consideration unavoidable temperature changes in the machine or such caused by wearing out of the diamond. According to the invention, the dressing of the grinding wheel can be performed by removing as little material as possible each time, which again results in the wheel lasting for correspondingly more Work-pieces before being worn out. In contradistinction hereto, it has previously been necessary initially to set the magnitude of dressing to meet even the highest possible alterations in the position of the diamond tip, and therefore not to risk the lack of sharpening, and in this way the grinding wheel had been subjected to a reduction in diameter which had been unnecessarily great. The device shown in FIG. 5 is particularly applicable to the measure control method disclosed in the U.S. Patent No. 3,003,293, granted to Gerszon Gluchowicz.

The embodiment shown in FIGS. 6 through 9 is distinguished from the embodiment described hereinbefore with reference to the FIGS. 1 through 5 by the feature that the head stock 12 carrying the work-piece 16 is movable laterally and thus adapted to perform the feeding motion in this direction during the grinding operation. On the other hand, the bracket 20 for the spindle 22 and the grinding wheel 24 have a constant lateral position to the support during the grinding operation, and the table 18 performs an oscillating or reciprocative movement in the longitudinal direction of the support. It is assumed that the work-piece is an injection nozzle for diesel engines and has a cylindric internal face 52 and a taper face 142, which are to be machined in the grinding machine to a final dimension. The surface 52 is machined by means of the grinding wheel 24 and the taper face 142 by means of another grinding wheel 144 with an end taper attached to a spindle 146 journalled in a support 148. The latter is mounted on a slide 150 supported by the table 18 but able to perform an oscillating movement in an angle towards the longitudinal axis of the spindle 146 as indicated by arrows 152.

The head stock 12 is capable of taking two positions, as will be understood from FIGS. 7 and 8, in one of which the cylindric face 52 is machined according to FIG. 7, while the grinding wheel 144 is inactive and included in a space 154 in the head stock to be out of the way. In the position shown in FIG. 8, on the other hand, the grinding 144 is machining the taper 142, while the grinding wheel 24 is embraced by a so-called master ring 156 rigidly mounted in the chuck stock.

The measuring instrument 32 with its gauge head 36 is in the same manner as in the embodiment described hereinbefore disposed between the bracket 20 and the grinding wheel 24 and is threaded over the arbor or spindle 22 supporting the grinding wheel. The foot 30 of the measuring instrument is in this embodiment pivotally mounted on a spindle 158 which is parallel to the spindle arbor 22 and disposed at a distance beneath the said arbor. The foot 30 is under the action of a spring 160 bearing on a shoulder 162 on the table 18, causing the measuring instrument to swing clockwise viewed in the plane of FIG. 9. The oscillating or reciprocative movement of the measuring instrument is limited by a stationary stop 164 located on the table 18.-

In order to secure that the centre of the cylindric external face of the gauge head 36 coincides with the cylindric face 52 of the work-piece the measuring instrument 32 is-connected to an arm 166 adapted to co-operate with a

cam

168 or 169, respectively, attached to the head stock 12. Thus, when the grinding spindle 24 is brought towards the Work-piece 16, the arm 166 is raised onto the cam 168 and the measuring instrument 32 oscillated, while the spring 160 is compressed, until the centre of the internal face of the work piece coincides with the centre of the external face of the gauge head 36. During the grinding process the gauge head follows the head stock 12 in the lateral displacement of the latter, so that the mutual central positions will be maintained. When the head stock 12 takes its active position as shown in FIG. 8, and thus the grinding wheel 24 is embraced by the cylindric recess of the master ring 156 the cam 169 sets the central position of the cylindric external face of the gauge head 36 in relation to the centre of the master ring.

As soon as the gauge head has the true central position according to FIG. 7 it is ensured that the head stock 12 will perform a laterally directed feeding movement, which will be interrupted at the right moment by actuating the means 92 described hereinbefore. In the position shown in FIG. 8 of the grinding wheel 24 the correct setting of the measuring instrument is checked, since the master ring has a definite internal diameter. Any possible deviations from the correct value of the indicator or the reading on the instrument 92 is adjusted by a corresponding alteration in the passage system connected to the measuring instrument and consequently in the instrument proper. The adjustment of the measuring instrument in the master ring 156 may, according to the invention, be carried out at a moment when the grinding machine is in all events 6 engaged in an operation process not concerning the grinding wheel 24, and which in the embodiment according to the FIGS. 6 through 9 concerns the grinding of the taper face 142.

The spindle 158 is journalled in the bracket 20 by means of balls 170 (FIG. 6) allowing for an axial movement of the measuring instrument 32 against the action of a yielding bellows 171, which simultaneously acts as a packing to prevent any contamination to penetrate into the space occupied by the balls 170. The displacement of the spindle 158 towards the head stock 12 is limited by a washer 172. In the extension of the spindle 158 is placed a stop 173 hit by the spindle before the grinding wheel 24 has reached its innermost position in the work-piece 16. This embodiment is particularly advantageous in the case of long work pieces, in which the gauge head 36 takes its measuring position at an early phase of the axial feeding of the grinding wheel but, at the same time, need not be given a great axial length.

After the grinding wheel 24 has completed a grinding operation and the internal face 52 of the work-piece 16 has got its final dimension, the grinding wheel is generally allowed to run at a distance from the internal face in order not to leave any marks on it when pulled out. Such a lateral movement or so -called retraction may preferably be performed with the structure of the bracket 20 as shown in FIGS. 10 and 11. It is provided with a slot 174 extending horizontally over the greater part of the bracket just above its guide track 175 in the table. In the track is placed a plate 176 which round its edges is sealed against the upper face of the recess by means of an O-ring 178. In this way a closed spaced or a gap 180 will be defined by a plate 176 and the upper face of the recess 174 within the O-ring 178. The gap communicates through a passage 182 with a source of compressed air. The recess 174 may externally be a closed ruler 184 simultaneously serving as a spacer limiting the downward resiliency of the bracket. When a retraction is to be performed, compressed air is introduced through the passeage 182 into the gap 180. This will rotate the bracket about its uninterrupted portion 186 sufficiently to bring the grinding wheel 24 out of contact with the finished surface. This device is extremely simple in its structure but nevertheless very reliable in its function.

The cam 169 and the stop 164 may be omitted and replaced by a cam portion attached to the gauge head and formed to co-operate directly with the machined surface 52 of the work-piece.

While several more or less specific embodiments of the invention have been shown and described, it is to be understood that this is for purpose of illustration only, and that the invention is not to be limited thereby, but its scope is to be determined by the appended claims.

What I claim is:

1. An internal grinding machine comprising a support, a chuck for carrying a workpiece, and a grinding wheel mounted on a spindle in a bracket, both said chuck and said grinding wheel being mounted on said support to be rotatable and relatively reciprocally displaceable axially as well as radially for grinding an internal face of the Work piece, a sharpening tool adapted to dress the grinding wheel at predetermined intervals, and a pneumatic measuring instrument provided with a gauge head having outlet nozzles for a pressure medium, said head being axially reciprocable in and out of the work-piece with a gap between the head and said internal face affecting the pressure of said pressure medium, the improvement that the measuring instrument is disposed between said grinding wheel and said bracket with the gauge head partially embracing the spindle.

2. In an internal grinding machine as claimed in claim 1, the improvement that the measuring instrument is mounted on a table with the bracket, and said table is mounted to be displaceable in relation to said support.

3. In an internal grinding machine as claimed in claim 1, the improvement that the measuring instrument is adapted with the external face of its gauge head to maintain a true position relative the internal face of the workpiece independent of the radial reciprocating movement of the grinding wheel and the work-piece.

4. In an internal grinding machine as claimed in claim 1, wherein the bracket is disposed to effect the lateral feeding, the improvement that the measuring instrument is adapted to participate in the axial movement of the table only but not in the feeding movement of the bracket relative the table.

5. In an internal grinding machine as claimed in claim 1, wherein the chuck is disposed to effect the radial feeding movement, the improvement that the measuring instrument is laterally displaceably mounted on the table and adapted to be affected by a cam member adjusting the central position of the gauge head relative the central position of the work-piece carried by the chuck.

6. In an internal grinding machine as claimed in claim 3, wherein the chuck is disposed to be set in two different lateral positions relative the support, one for performing the grinding operation, the other for other operational steps, the improvement that in the latter position the gauge head of the measuring instrument is embraced by a master ring in a :position set by a cam relatively to the chuck for checking the correct set-ting of the measuring instrument.

7. In an internal grinding machine as claimed in claim 5, wherein the chuck is disposed to be set in two different lateral positions relative the machine frame, one for performing the grinding operation, the other for other operational steps, the improvement that in the latter position the gauge head of the measuring instrument is embraced by a master ring in a position set by a cam relatively to the chuck for checking the correct setting of the measuring instrument.

8. In an internal grinding machine as claimed in claim 1, th improvement that the measuring instrument is provided wit-h a gauge composed by a head of substantially section-cylindric shape, and a flange with a mainly radial extension, both said parts of the gauge being divided the former peripherally and the latter radially, said parts between themselves defining passages leading to outlet nozzles for the pressure medium.

9. In an internal grinding machine as claimed in claim 8, the improvement of ducts for supply of a coolant be- 8 ing formed in the measuring instrument and its gauge head.

10. An internal grinding machine comprising a chuck carrying a work-piece, and a grinding wheel supported by a spindle mounted in a bracket, both said chuck and said grinding wheel being mounted to be rotatably and relatively reciprocally displaceable axially as well as radially for grinding an internal face of the work-piece, a dressing tool adapted to dress the grinding wheel at predetermined intervals, the improvement that the dressing tool has a tip, the position of which in the machine is controllable by a measuring means built into the same, said measuring means comprising an outlet nozzle for a pressure medium and a spring loaded member positioned in front of said nozzle and adapted upon actuation by the pressure medium to bear on'said tip and thereby to form a gap between the nozzle and the said member in response to the position of the tip.

11. An internal grinding machine comprising a chuck for carrying a work-piece, and a grinding wheel supported by a spindle mounted in a bracket, both said chuck and said grinding which being mounted to be relatively reciprocally displaceable axially as well as radially for successive working off of an internal face of the workpiece, the improvement that the bracket has a slot reducing its material thickness and leaving an uninterrupted portion about which the bracket is resiliently rotatable for permitting the grinding wheel to perform a retraction movement, said slot being formed with a closed space containing a pressure medium for producing said resiliency.

References Cited by the Examiner UNITED STATES PATENTS FOREIGN PATENTS 9/1960 Great Britain.

SWINGLE, Primary Examiner.

LESTER M.

Claims

1. AN INTERNAL GRINDING MACHINE COMPRISING A SUPPORT, A CHUCK FOR CARRYING A WORK-PIECE, AND A GRINDING WHEEL MOUNTED ON A SPINDLE IN A BRACKET, BOTH SAID CHUCK AND SAID GRINDING WHEEL BEING MOUNTED ON SAID SUPPORT TO BE ROTATABLE AND RELATIVELY RECIPROCALLY DISPLACEABLE AXIALLY AS WELL AS RADIALLY FOR GRINDING AN INTERNAL FACE OF THE WORK PIECE, A SHARPENING TOOL ADAPTED TO DRESS THE GRINDING WHEEL AT PREDETERMINED INTERVALS, AND A PNEUMATIC MEASURING INSTRUMENT PROVIDED WITH A GAUGE HEAD HAVING OUTLET NOZZLES FOR A PRESSURE MEDIUM, SAID HEAD BEING AXIALLY RECIPROCABLE IN AND OUT OF THE WORK-PIECE WITH A GAP BETWEEN THE HEAD AND SAID INTERNAL FACE AFFECTING THE PRESSURE OF SAID PRESSURE MEDIUM, THE IMPROVEMENT THAT THE MEASURING INSTRUMENT IS DISPOSED BETWEEN SAID GRINDING WHEEL AND SAID BRACKET WITH THE GAUGE HEAD PARTIALLY EMBRACING THE SPINDLE.