US2751719A - Copying grinding machine - Google Patents

Description

June 26, 1956 w. REICHEL 2,751,719

COPYING GRINDING MACHINE Filed March 12, 1954 2 Sheets-Sheet l June 26, 1956 W. RE|CHEL COPYING GRINDING MACHINE 2 Sheets-Sheet 2 Filed March 12, 1954 United States Patent COPYING GRINDING MACHINE Walter Reichel, Frankfurt am Main, Germany, assignor to F. Blasi & Co., Solothurn, Switzerland Application March 12, 1954, Serial No. 415,893

Claims. (Cl. 51-100) The present invention relates generally to grinding machines and more generally to copying grinding machines.

The machines suggested in prior art for grinding cutters (used c. g. in lathes, milling machines) to give them a cut ting edge the contour of which is copied from a pattern are very complex in construction and use and expensive. Furtheremore, they do not allow for easily trueing the active profile of the grinding wheel although such trueing must be carried out frequently.

The main object of the present invention is to do away with these multiple drawbacks of the known copying grinding machines.

It is known to those skilled in the art that the cutting edge of formed cutters has a profile which is a projection of the profile formed by them on the work, since the cutters must have a clearance angle.

A further object of the invention is to make provisions in the grinding machine, which allow to take easily account of this fact and to permit the use of a pattern the contour of which is an exact image of the cutting edge to be formed, thereby allowing to omit the previous graphical determination of the pattern contour.

Other objects and features will appear from the following description of an example of performance of the machine of the invention with reference to the accompanying drawings, in which:

Figs. 1 and 2 are an elevational and a plan view, respectively, of the upper portion of the grinding machine as it looks during the grinding of a formed lathe cutter,

'Fig. 3 is a vertical section of the same portion of the machine,

Fig. 4 is a plan view similar to Fig. 2, some parts being however shown in position for trueing the grinding Wheel, and

Fig. 5 is a horizontal section along the line 5 5 of Fig. 3.

The machine represented in the drawings comprises a casing including a lower part 1 and a bed 2. A guide 3 is fixed to the upper surface of the bed 2 and guides a support 4 for motion from left to right and inversely. The mechanism for producing this motion comprises a hand wheel 5, a Cardan shaft 6, a worm gearing 7, a pinion 8 and a rack 9 fixed to support 4.

A casing 10 is fulcrumed on support 4 to be pivotable about the axis of a shaft made integral with a pinion 11 and having fixed thereto a pulley 12. An electric motor 13 has its shaft operatively connected by means of a pulley 14 and of a belt 15 with the pulley 12 and-with a pulley 16 fixed to a shaft to the ends of which two grinding wheels 17 are removably fixed. The pinion 11 meshes constantly with a toothed wheel 18 which is loosely mounted on a short shaft 19 rotatably mounted in a gearing casing 20 rigidly fixed to casing 10 and which, by means of a nut 21 screwed to shaft 19, may be pressed against a disc fixed to this shaft. The latter is madeintegral with an eccentric pin 22 rotating in a bore of a connecting rod 23 pivotally mounted to the support 2,751,719 ?atented June 26, 1956 4 at 24. When the shaft 19 is coupled with the toothed wheel 18, the mechanism including the eccentric pin 22 and the connecting rod 23 makes the shaft 19 oscillate bodily with casings 2d, 1d, the motor 13 and the grinding wheels 17 about the fulcrum axis of said casings 19, 20 on support 4, for a purpose which is well known to the constructors of grinding machines.

The bed 2 has two parallel oppositely facing guides 25 fixed to its upper surface. By means of two rows of balls 26, held in straight cage plates not shown on the drawings, a plate 27 fixed to a slide casing 28 is guided to be movable from left to right and inversely between the guides 25. The slide casing 28 has fixed thereto a plate 29 with lateral runways for two further rows of balls 36 running in oppositely facing runways of two bars 31 fixed to a slide 32. The latter is thus guided for translatory motion in two perpendicular directions of an horizontal plane. It has two end plates 33 fixed thereto which have arcuate grooves 34, the middle portion of which extends through the entire thickness of the respective end plates 33 and receives a locking bolt 35 screwed to a support plate 36 extending between the end plates 33. This support plate 36 has two guiding bolts 37 fixed to each of its end surfaces which face the end plates 33. These guiding bolts 37 engage the arcuate grooves 34, thereby guiding the support plate 36 to be pivotable about an axis extending parallel to, and approximately at the same level as, the common axis of both grinding wheels 17. The support plate 36 is normally locked by means of the bolts 35.

The support plate 36 has near each of its ends a prismatic guide 3% and a support surface 39 for a work holder 46 fitted with a clamping nut 42 and a clamping screw for its removable fixation to the support plate 36 and also with a clamping device 42, similar to those used on lathes for clamping a cutter, for clamping onto it a work piece 43 constituted e. g. by a formed cutter. Stop screws 44 threadedly adjustable in holes provided in upwardly projecting end portions 36a of the support plate 36 serve to determine the position of the two work holder's 44) (of which only one is shown in the drawings) in the longitudinal direction of the support plate 36.

The slide 32 forms, together with the parts mounted thereon, a support adapted to hold two work pieces and guided for translatory motion relative to the grinding wheels 1'7 in two perpendicular directions in a horizontal plane parallel to that meridional plane of the grinding wheels which crosses the surfaces to be ground, of the two work pieces 43.

Adjacent to each of the end plates 33 a post 45 is fixed, by means of three screw bolts 46 (Fig. 3), to the portion of slide 32 lying underneath the grinding wheels 17. Each post 45 has mounted to it a rocking arm 47 having a -arcuated groove concentric to its pivot axis and traversed by a locking screw 48 threadedly engaging a hole in the post 45, whereby the rocking arm may be locked in either one of the positions which it occupies in Figs. 1 and 4, respectively. Each rocking arm 47 has fixed to it three points 49 of diamond or the like hard material which in their active position, shown in Fig. 4, are placed for engaging respectively the periphery and the sides of the profile of the adjacent grinding wheel 17, whilst in the position of Fig. 1 they are removed from the grinding wheels to permit them to engage the work pieces 43. The posts 45 constitute, together with the rocking arms 47 and the points 49, two devices rigidly connected to the work holding support, for trueing the grinding wheels.

A bracket 50 fixed to the bed 2- has a vertical guideway for a slide 51 which may be adjusted-upwardly and downwardly by means of a screw spindle 52 and a hand wheel 53. This slide 51 has fixed thereto three superposed feeler members 54, 55, 56 having guiding profiles similar to the profiles of the grinding wheels used after one another in the course of the grinding operation, namely the two grinding wheels 17 which are for rough grinding (and for that purpose have a stable triangular profile), or grinding wheels having profiles similar to the guiding profiles of the feeler members 55, 56, respectively, for pre-finish grinding and finish grinding.

Two guides 57 fixed to the lower surface of the bed 2 have oppositely facing runways for two rows of balls 58, guiding a slide plate 59 which is rigidly fixed to a similar slide plate 60, that has two longitudinal runways 61 perpendicular to those of plate 59. A slide member 62 has fixed thereto two bars 63 similar to the guide bars 57 and guided on plate 60 by means of two rows of balls 64. A member 65 is fixed to each end of plate 59. Each of these members has two semi-circular channels 66 and the plates 59, 60 have straight bores 67, the disposition being shown in Fig. 5. The balls 64 (or 58) form two endless rows and those of each such row thus follow a path closed in itself, when the slide 62 is moved towards the left or the right side relative to plate 60 (or when the plate 59 is moved forwardly or backwardly in Fig. 3).

A bracket 68 is fixed to the upper side of the slide member 62 and has two coaxial bores receiving the smooth portions 69a of handles 69, the threaded portions 69!) of which are screwed into the opposite ends of a pattern carrier member 70. A pin 89 extends transversely through the threaded portion 69b of one handle 69 and the pattern carrier 70 to rigidly connect them with each other whereby the carrier 70 may be angularly adjusted by means of this handle when the other handle is unlocked from the bracket 68. The purpose of the angular adjustment will be described later on. A rigid master pattern plate 71 is clamped to the carrier 70 by means of a clamping member 72 and two screws 73. A trueing pattern plate 74 is clamped in a similar manner to a bar 75 fixed to the carrier 70 by means of screws not shown in the drawings.

The slide 62 forms together with the bracket 68 and the carrier member 70 a second support. This second support on the one side and the set of feeler members 5456 on the other side are guided for translatory motion relative to each other in two perpendicular directions of a horizontal plane.

A pantographic device is provided by which the motions of said first support (the work holder support) relative to the grinding Wheels 17 are made to be similar, geometrically spoken, to those of the second support relative to said set of feeler members, but reduced at a predetermined ratio which in the embodiment represented on the drawings is 1:5. This device comprises a lever member 76 pivotally mounted with one of its ends to the lower side of slide 62, a lever member 77 pivotally connected with one of its ends to the other end of the lever member 76 and with its other end to a bracket 78 rigidly fixed to casing 1, and two connecting rods 79, 80 pivotally mounted to a strong bolt 81 fixed to a part 82 made integral with, or rigidly fixed to, one of the end plates 33 of said first support. The seven pivot connections in this device each comprises a high precision antifriction bearing well enclosed for its protection against dust and the like. The mounting of said first support and second support on balls 30, 26 and 58, 64, respectively, and these almost frictionless connections in the pantographic device permit an almost efiortless shifting of the first support by means of the second support by the hands of the operator holding the handles, the thumb of one hand preferably being also in contact with one of the feeler members 54-56.

When looking at Fig. 4, it will be seen that the trueing pattern 76 has an inner contour of U-shape provided with three points 83 in a disposition which is similar, geometrically spoken, to that of the points 49 of the trueing member 47, the ratio of similarity being equal to the reducing ratio of the pantographic device, namely 1:5.

When the operator starts to work, he puts the trueing pattern 74 and the trueing member, 47 into their horizontal positions shown in Fig. 4 and mounts onto shaft 16 two grinding wheels 17 having a triangular profile. Slide 51 is adjusted to its uppermost position, so that the feeler member 54 with the triangular guiding profile is set in position to cooperate with the trueing pattern 74. The operator now trues both grinding wheels simultaneously in the following manner: at first he moves the trueing pattern 74 so that one of its oppositely facing points 83 remains in contact with the juxtaposed flank of the feeler member 54; then he does the same for the other one of said oppositely facing points 83 and then with the third of the three points to move it around the tip of member 54, this tip in most cases being semi-cylindrical. It is obvious that when the trueing operation is terminated the profile of the grinding wheels 17 has in radial cross section a configuration which is an exact image of the guiding profile of the feeler member 54, reduced at the 1:5 ratio of the pantographic device.

For preparing the subsequent grinding of the cutters 43 fixedly mounted as shown in Figs. 1 and 2, he puts the master pattern 71 into the position shown in these figures and rocks the trueing members 47 back into their inactive position. The machine is now ready for grinding, which is done by moving said second suppo so that the contour 85 of the master pattern 71 remains in contact with the feeler member 54. The two grinding wheels 17 then auomatically form on the cutters 43 ground surfaces the profile of which has in cross section a configuration which-with one possible exception to be explaned hereinafteris an exact image, reduced at the 1:5 ratio to the pantographic device, of the contour of the master pattern. The possible exception occurs if the contour 85 has abrupt steps so that it cannot be moved to remain in contact with the tip of the feeler member 54. This exception however, cannot occur during the finish grinding with grinding wheels having an active profile similar in cross-section to guiding contour of the feeler member 56.

When the rough grinding is terminated, the prefinishing grinding wheels are mounted, whereafter their active profile is trued as explained above, but with the use of feeler member 55. Thence the pre-finish grinding is accomplished, with the use of this feeler member 55.

Finally, the finishing grinding wheels are mounted, then trued with the aid of the feeler member 56 which is also used during the finish grinding.

If the cutters 43 should have a clearance angle, the support plate 36 is adjusted to occupy a correspondingly inclined position indicated by a scale 86 provided on one of the end plates 33 and the master pattern 71 is inclined at the same angle indicated by a scale 87 provided on the pattern carrier 70, during the grinding operations, but not during the trueing operations. Simple reflexions will show that the parts obtained on a lathe with cutters ground in this way will have a profile which is an exact reduced image of the contour 85 of the master pattern 71.

Machining allowances may be given by actuating the hand wheel 5 provided with a scale 88, thereby moving the support 4 together with the grinding wheels away from, or towards, the work pieces 43.

It is easily understandable to those skilled in the art that the use of three different sorts of grinding wheels, which is not new, speeds up the work and contributes to prolong the lifetime of the prefinishing and finishing grinding wheels, but that the invention is of course not restricted to the use of more than one sort of grinding wheel and the provision of more than one feeler memher.

The simultaneous grinding of two cutters provides the advantage that two exactly identical cutters can be given to the operator of the lathe, so that one cutter is in reserve and the operation of the high-production lathe is not substantially interrupted if one of the two cutters is damaged. However, it should be understood that a grinding machine with only one grinding wheel and only one work holder is within the scope of the protection claimed.

A further modification which falls within this scope of protection consists in mounting said grinding wheel or wheels and said feeler member or members to be each movable in two perpendicular directions, but interconnected by a pautographic device, whilst said first suppo and said second support would remain in fixed position during normal operation. Such modification would obviously be a mere constructional inversion and rearrangement of parts.

What I claim is:

1. A grinding machine comprising in combination, a grinding wheel; a first support adapted to hold a work piece, guide means for guiding said grinding wheel and said first support in a relative translatory motion to each other in two perpendicular directions of a plane parallel to that meridional plane of the grinding Wheel which crosses the surface to be ground; a grinding wheel trueing device which has points arranged to engage respectively the periphery and the sides of the profile of the grinding wheel and which is rigidly connected to said first support; a feeler member having a guiding profile similar to that of the grinding wheel; a second support, guide means for guiding said feeler member and said second support in a relative translatory motion to each other in two perpendicular directions of a plane; a pantographic device by which the motions of said first support relative to said grinding wheel are made to be similar, geometrically spoken, to those of the second support relative to said feeler member, but reduced at a predetermined ratio; a master pattern and a trueing pattern both fixed to said second support, the trueing pattern having points similarly located as those of the trueing device, whereby, when any one of the points of the trueing pattern is moved along the juxtaposed portion of the guiding profile of said feeler member, the corresponding point of the trueing device trues the juxtaposed portion of the profile of the guiding wheel, this profile obtaining thus a configuration which is an exact image of the guiding profile of the feeler member, reduced at the ratio of the pantographic device, when the trueing operation has been accomplished with all points, so that consequently, when said master pattern is subsequently guided to move with its contour in contact with the guiding profile of the feeler member, the grinding Wheel grinds on the work piece a surface the contour of which is an exact image, reduced at the ratio of the pantographic device, of the contour of the master pattern.

2. The grinding machine of claim 1, in which means is provided for guiding said first and said second supports for translatory motions in superposed horizontal planes.

3. The grinding machine of claim 2, comprising a grinding shaft on which said grinding wheel is removably mounted, a slide and means adjustably supporting said slide for vertical movement, said slide being adjustable by hand in vertical direction and having fixed thereto a plurality of said feeler members of which any one may be brought in operative position by adjustment of said slide.

4. The grinding machine of claim 2, in which the feeler member has the same orientation as that circumferential portion of the profile of the grinding wheel which at a determined moment engages the Work piece, and in which both the first support and the second support comprise parts angularly adjustable about axes parallel to the turning axis of the grinding wheel, these parts being those supporting the work piece and the master pattern, respectively.

5. The grinding machine of claim 4, in which the maste-r pattern and the trueing pattern are plates fixed to, and extending at an angle with regard to each other from the angularly adjustable part of the second support, and which the trueing device includes a point-carrying memher oscillatable from a first position in which the trueing points are located in their active position, into a second position in which the trueing points are located away from the grinding Wheel in any position of the first support.

References Cited in the file of this patent UNiTED STATES PATENTS

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