US2858649A

US2858649A - Radius-grinding apparatus

Info

Publication number: US2858649A
Application number: US531539A
Authority: US
Inventors: Scheubeck Oskar
Original assignee: Individual
Current assignee: Individual
Priority date: 1955-08-30
Filing date: 1955-08-30
Publication date: 1958-11-04
Anticipated expiration: 1975-11-04

Description

Nbv.l4, 1958 o; SCHEUBECK- 5 RADIUS-GRINDING APPARATUS Filed Aug. 30. 1955 v s Sheets-Sheet 1 //v VENTUR OSKAR SCHEUBECK ATTORNEYS Nov.- 4, 1958 v o. S-CHEUBECK 2 ,858,649

RADIUS-GRINDING APPARATUS Filed Aug. 30'. 1955 A s Sheets-Sheet 2 FIG. 2

/N VE N TOR OSKAR SCHEUBECK BY Mf/ZAL A TTORNE Y5 O. SCHEUBECK RADIUS-GRINDING APPARATUS Nqv. 4, 1958 3 Sheets-Sheet 3 Filed Aug. 30. 1955 FIG. 4

OSKAR SCHEUBE'CK BY M ATTORNEYS United States Patent RADIUS-GRINDING APPARATUS Oskar Scheubeck, Regeusburg, Germany Application August 30, 1955, Serial No. 531,539

Claims. (Cl. 51-33) This invention relates to a radial grinding apparatus.

In engineering, especially in the case of milling cutters, the task often occurs of grinding rounded corners with precise radius.

The arrangements provided hitherto for this purpose consisted of a grinding .apparatus with a cup-shaped grinding wheel and a pivoting arrangement receiving the workpiece to be ground, inthe case under consideration a milling cutter. The cutter could here be oriented by slide guides within the pivoting device in the desired manner and was brought up, for the purpose of grinding, to the side or edge of the grinding wheel and pivoted back and forth through a certain angle, for example about 90, when a rounded ground part was produced on the cutter.

However the known arrangements possess substantial disadvantages. As a result of the difiiculty of orientation of the workpiece the working requires a considerable time, normally a number of hours. Then the accuracy of the ground face remains limited, and does not correspond to the reguirements made of modern milling tools. There is also the unwieldiness of the operation due to the considerable pivoting masses of the cutter-securing and adjusting arrangement. Furthermore the cup-shaped grind-' ing wheel signifies a'considerable expenditure of abrasive material, where it must also be considered that the working edge of the grinding wheel easily suffers damage and therefore the'grinding operation becomes irregular. Furthermore even when the grinding wheel is undamaged the danger of undesired formation of grooves on the workpiece is very great. Finally due to the circular working edge the ground face of the workpiece does not become cylindrical, as desired, but more or less wasted. In order to reduce this phenomenon, it is necessary to work with the greatest possible radius of the grinding wheel. However this again has other disadvantages, such as wobbling of the wheel etc., as its results.

It is the task of the invention to avoid all these disadvantages and to provide an arrangement which permits a maximum of accuracy of the ground face and a significant saving of time, with very simple and convenient operation and avoidance of large pivoting masses and large grinding wheels.

In accordance with the invention in the case of the new radial grinding apparatus the workpiece to be ground, for example a milling cutter, is not pivoted as in the known case, but is mounted stationarily during the grinding operation, While a rotating grinding element, for example a Bosch or compressed air grinder, is arranged on a circularly moved swivelling member. Since a cylinder of very small diameter is suflicient as grinding element, for the drive of which a light motor is suflicient, a swivelling element is obtained the mass of which amounts to only 'a fraction of the pivoting mass of the former radial grinding apparatuses. The operation of the swivelling element is therefore as easy as can be, so that the operator is subjected to substantially less fatigue. At the same time the orientation of the workpiece, in relation to the known arrangement, is significantly facilitated.-

Furthermore the ground face is also exactly cylindrical, in the case of cylindrical grinding elements, or corresponds to the generating curve of the grinding cylinder in.each case, while in the known case only the aforementioned waist-shape can be obtained.

Usually in the case of milling cutters a clearance angle or a backing-off clearance is desired. This can be achieved in the case of the invention, by making the axis of the grinding arrangement pivotable through a certain angle.

An angle scale is preferably provided for the setting of the grinding axis, on which scale the measure of the clearance angle can be read ofi directly. For practical operation it is further proposed to make the grinding device ad-' justable or displaceable in the radial direction on the swivelling element, in order to move the grinding tool nearer to or further from the workpiece in the desired manner. The displacement can be effected through a set screw, which can be provided with a scale.

The arrangement is expediently here made such that a special handle is provided with the aid of which the grinding device can be lifted by a small amount from the workpiece during the changing of the working position or during the transition from one cutter tooth to the next, independently of the working setting, in order to render possible the unhindered passage of the tooth. The lifting off here takes place against a spring force which automatically returns the grinding device into the original position on release of the handle.

The invention further provides measures in order to set the desired radius on a scale before the arrangement is set in operation. This takes place with the aid' of a hollow prism, preferably of right-angled shape, which serves as a kind of template, and is insertable in a bore concentric with the swivelling axis, the edge of the hollow prism coinciding with the swivelling axis in the zero position. By displacement of the edge of the prism out of the swivelling 'axis or zero position the radius of the future ground surface is determined and can be set or read off on an appropriate scale. Due to the fact that thereupon the workpiece is pushed into the template to the stop, the orientation of the template is transmitted to the workpiece and thus the grinding radius is also determined for the latter.

-In a further development of the invention a resiliently movable support tongue is provided for the grinding of milling cutters, which bears during the grinding against the front of the tooth which is just to be ground, while on tooth-changing or during the passing of the tooth it automatically deflects resiliently and thereafter returns again to the supporting position. The operator therefore merely has to rotate the milling cutter through a small angle and need not trouble about the supporting means.

-In order to render possible a rapid and exact orientation of the workpiece in relation to the template and'the grinding element an intermediate arm is provided on the base plate of the apparatus, which arm is pivotably and securably mounted on the base plate, and upon which in turn the workpiece bracket is pivotable and securable. Furthermore stops are arranged on the base plate, which permit of securing the pivot angle of the swivelling element andwhich are either displaceable in a circular guide path or insertable in appropriate setting holes.

An example of embodiment of the invention is represented in the figures, wherein: V

Figure 1 shows the plan view of the radial grinding apparatus in accordance with the invention,

Figure 2 shows a lateral elevation,

Figure 3 shows the prism, seen from the side,

Figure 4 shows the prism with the workpiece, seen from above.

, In the figures, 1 is a base plate, uponwhich an intermediate arm 3 is pivotably mounted at 2. This arm is securable in a desired swivelled position with a clamping device 4, which engages in a guide groove 5 of the base plate. At the same time a support bracket 6 for the workpiece 7 ispivotably mounted on the spindle of the clamping device, and can be secured similarly in its swivelled position by a clamping device 8. The workpiece, for example a milling wheel 7, is clamped fast upon a bearing journal 9 by a nut 10 and will be varied in its rotational position with the aid of a knurled handle 11. A support tongue 12 (Figure 2) serves for securing the rotational position in each case, being mounted at 13 for pivoting through a small angle and being drawn by a spring (not shown) automatically into the supporting position or in the direction towards the workpiece 7.

For the working of the workpiece there serves a grinding cylinder 14, which is axially adjustablev by means (not further shown) in a retaining arm 15 and is driven by an ordinary grinding motor 16. The retaining arm 15 is a part of a stand which consists of the upper part 17 and the lower part 18, which are adjustable in a circular guide 19 in relation to one another. The centre point of the circular guide 19 coincides with the working point 20, so that on a shifting of the stand parts17, 18 the axial direction of the grinding device 14 is pivoted, without the working point 20 being substantially displaced. The angle of pivoting can be ascertained on a scale (not shown) of the guide path 19. As mentioned at the outset, it determines the measure of the clearance angle of the ground surface.

A foot 21 formed on the bottom part 18 of the stand is displaceable in a guide prism 22 of a swivelling; element 23. The swivelling element- 23 is pivot-ably mounted about a journal 24, the axis 25 of whichleads through the centre-point of the radius of curvature of the ground surface. The journal 24 possesses a con' centric bore 26,into which either the support pin 27 of the support tongue 12 or a pin 28 of a template 29 can be inserted, the details of which may be seen from-Figures 3 and 4. The essential measurement part' of the template consists of a hollow prism. 30, the edge 31 ofwhich coincides with the axis 25, if the prismisin" the zero position; It can be moved out of this position with the aid of a set screw 32, when a mark 33 indicateson a scale 34 the measure of the eccentricity and thus the radius of the surface to be ground, in millimetres.

For the removal of the grinding element 14 from the workpiece 7 during the change of working there is provided a lifting-off device, consisting of a handle 35 which is supported at 36 on a support bracket 37 ofthe swivelling element 23 in pivotable fashion. If the handle- 35' is pivoted out of the position as illustratedin the direction, the stand 17, 18 is lifted ofi with the grinding cylinder 14, against the force of a spring 38, from the workpiece 7, and after shifting of the-workpiece and release of the lever 35 automatically returns into its rest position. With the aid of a set screw 39 in combination with a scale 40 the stand 17, 18 and thus the grinding cylinder 14 can be displaced in the guide prism 22 and moved towards or away from the workpiece 7.

Stops

41, 42, which are adjustable in a circular guide path 43 of the base plate, serveto limit the pivoting angleof the swivelling element 23 to the desiredamount, preferably 90.

The apparatus is used in the following manner:

1 Setting A radius with r=5 mm. is to be trued for'example on a milling wheel-i with rounded corners. For this'purpose firstly the template 29 is inserted with the pin-28 in the bore 26, and with the aid of the set screw'32 the setting mark 33 'is set to the numeral 5:5- mm. Then after release of the clamping devices 4'and8 the workpiece 7 is shifted until the edges of the milling tooth to be-worked bear againstthetace's w of the hollow prism.

The workpiece is clamped fast in this position, the prism is pushed a little further outwards by means of the screw 32 if necessary, the pin 28 is removed from the bore 26 and the prism is replaced by the support tongue 12, which is now inserted with its pin 25 in the bore 26.

The stand 17, 18 is here removed far enough from the workpiece with the aid of the threaded spindle or set screw 39, in order to avoid damage to the milling cutter 7 and also'to the grinding cylinder 14. The stops 41, 42 are so shifted in the guide path 43 that the pivoting angle of the swivelling element 23 amounts to about 2. Grinding The upper stand part 1 7 with the clamped-in electric or compressed air grinding motor 16 and the grinding cylinder 14 is rotated through the desired angle, for example 5, out of the vertical, utilising the guide 19, and secured in this position. Thereupon the lower stand part 18 is displaced in the guide prism 22 of the swivelling element 23 with the aid of the set screw 39 in the direction a, that is to say towards the workpiece; 7, until the rotating grinding cylinder 14 comes into contact with the milling. tootlrto be ground. Now the swivelling; element is moved about the pin 24 from the stop 41 to the stop 42 inthe direction i'k, whereby the grinding cylinder 14 sweeps over an arc of 90 about the axis 25, and thus grinds the desired radius s.

3. Tooth shifting The swivelling element 23 is brought into the initial positionand the grinding cylinder 14 is removed from the workpiece 7 by the handle 35. Now the milling cutter 7 is rotated one tooth further, with the knurled disc 11-, when the stop tongue 12 mounted resiliently. for rotation about the'point 13 is lifted. ofi in the direction 1 by the cutter tooth sliding past. The resiliently held stop tongue 12 jumps in the direction e into the gap following' the tooth moved away, and supports the next tooth which is now to be ground. The milling cutter 7 can be clamped fast in this position, but usually it is suflicient if the milling cutter tooth is pressed manually with the aid of the knurled disc 11 upon the stop tongue 12, in order to secure the precise position of the tooth. This last-described manner of holding the milling cutter shortens the overall working time. If the handle 35 is slowly released, the compression spring 38 returns the stand 17, 18 and the grinding tool 14 in the direction a into the initial position, so that now the next tooth is worked in exactly the'same manner as the preceding one.

It is a special advantage of the new arrangement that wear upon'the grinding tool has no influence upon the grinding radius, since this is determined solely by the orientation of the workpiece in relation to the template 30 displaced out of the central position; As may be seen, in comparison with the'forrner cup-like, large grinding plates, a simple grinding cylinder of small diameter, the abrasive material of which can be completely used up, is sufiicient. The. operation of the entire arrangement is so easy and rapid that the working time can be reduced to a small fraction of the former working time, without particular strain upon the operator, who can carry out the work sitting comfortably.

I claim:

1. In a radius grinding apparatus of the type described,

' in combination, means for holding a work piece stationary during the grinding operation, rotatable grinding means arranged on a swivelling element and suitable for being pivoted about a pivot axis around the center of curvature of a surface of the work piece which is to be ground, said grinding means including a grinding cylinder' and a driving motor connected thereto for driving the same, said cylinder and motor being arrange'd'coaxially with respect to each other, support means for supporting said grinding means on said swivelling elementin such a manner that said pivot axis extends substantially parallel tothe axis of rotation of said grinding means, and adjustable mounting means for adjustably mounting said grinding means on said swivelling element in such a manner that the angle between the common axis of said cylinder and motor and said pivot axis may be varied to correspond to the clearance angle of the ground surface.

2. The combination as described in claim 1, wherein said support means is adjustable in a direction transverse to said pivot axis, the combination further comprising means for removing said support means with said motor and said cylinder, spring means urging said support means into adjusted position, and a pivotable handle connected to said support means whereby said support means can be temporarily displaced against the action of said spring means to permit movement of said work piece without changing the adjustment of said grinding means.

3. The combination as described in claim 1, wherein said swivelling element is formed with a bore arranged concentrically with respect to said pivot axis, the combination further including an adjusting device comprising a pin, a template and a hollow prism, said adjusting device being positioned within said bore through the intermediary of said pin, a support comprising a pin and a support tongue, said last-mentioned pin being suitable for being positioned in said bore, said adjusting device thus being replaceable by said support.

4. The combination as described in claim 1 wherein said adjustable mounting means for said motor and said 6 cylinder comprise two parts having at their junction a slot forming the segment of a circle the center of which coincides with the spot of grinding, said mounting means thus allowing for changing the clearance between work piece and grinding means without changing the location of the spot of grinding.

5. The improvement as described in claim 1 wherein said means for holding the work piece stationary during the grinding operation comprise a swivelling arm and a base plate, said swivelling arm being mounted on said base plate, and means for arresting said work piece on said swivelling arm, thus allowing said arrested work piece to be moved together with said swivelling arm into a predetermined position.

References Cited in the file of this patent UNITED STATES PATENTS 727,981 Lomasney May 12, 1903 766,978 Symington Aug. 9, 1904 838,250 Hudlow Dec. 11, 1906 1,281,512 Carothers Oct. 15, 1918 1,596,727 Goldberg Aug. 17, 1926 1,836,482 Lyon et a1 Dec. 15, 1931 2,224,959 Galloway Dec. 17, 1940 2,396,281 Noble et al Mar. 12, 1946 2,436,873 Sneva Mar. 2, 1948 2,552,164 Foss May 8, 1951