US2950578A

US2950578A - Grinding machine with tool dressing means

Info

Publication number: US2950578A
Application number: US703696A
Authority: US
Inventors: Fouquet Eugene
Original assignee: Individual
Current assignee: Individual
Priority date: 1956-12-28
Filing date: 1957-12-18
Publication date: 1960-08-30
Anticipated expiration: 1977-08-30
Also published as: LU35594A1

Description

Aug. 30, 1960 E. FOUQUET GRINDING MACHINE WITH TOOL DRESSING MEANS 6 Sheets-Sheet 1 Filed Dec. 18, 1957 E FOL/ w t, m/mvroe PEP ATTOENEY/ Aug. 30, 1960 E. FOUQUET GRINDING MACHINE WITH TOOL DRESSING MEANS Filed Dec. 18, 1957 s Sheets-Shet 2 5 F0 u ue /NVENTOP p52 44 ATTOPIVEY/ Aug. 30, 1960 E. FOUQUET GRINDING MACHINE WITH TOOL DRESSING MEANS s Sheets-Sheet 3 Filed Dec. 18, 1957 5 Fou uefJ/VVE/VTOP 7 A59 Arm/2N0;

Aug. 30, 1960 E. FOUQUET 2,950,578

GRINDING MACHINE WITH TOOL DRESSING MEANS Filed Dec. 18, 1957 6 Sheets-Sheet 4 E Fou uez wmvme PER 3 4 Aug. 30, 1960 E. FOUQUET 2,950,578

GRINDING MACHINE WITH TOOL DRESSING MEANS Filed Dec. 18, 1957 6 Sheets-Shet 5 Foiuguel, INVENTOP I PER Y ATTORNEY Aug. 30, 1960 E. FOUQUET 2,950,578

GRINDING MACHINE WITH TOOL DRESSING MEANS Filed Dec. 18, 1957 6 Sheets-Sheet 6 E Fog L705 Z INVENTOP PEA? O'ZLA 5M.

AWODNEYI atent Patented Aug. 39, 1960 fiice GRINDING MACIEQE WITH TOOL DRESSING MEANS Eugene Fouquet, 63 bis Rue Jean-Jaures,

Bois-Colornbes, France Filed Dec. 18, 1957, Ser. No. 703,696

Claims priority, application France Dec. 28, 1956 12 Claims. (CI. 51-95) In another application of the applicant there has been disclosed a novel machining process uniting the characteristics of grinding and milling, said process comprising the steps of acting on the metal surface to be treated, by means of a tool in the shape of a grindstone, while continuously subjecting said tool to a beating operation whereby chips are chopped off the abrasive grains apparent on the active surface of said grinding tool, said process enabling, under particular circumstances, to effectuate the removal of material in the form of metal shavings from said metal surface at very high speeds, without modifying the technological properties of the metal thus treated, said process being moreover applicable to any metal surface, even when the latter has previously been subjected to a hardening heat treatment.

Application of this novel process, which will hereinafter be referred to as mill-grinding evidently requires the use of a machine specially adapted to this application and fully meeting all requirements arising therefrom.

It is the purpose of this invention to provide such a machine. To achieve this, many difierent designs can of course be contemplated as best adapted to the particular application in view; most generally however, these machines, whatever power, size, destination and performance they may be designed for, shall comprise at least the following elements in combination:

(a) supporting and driving means for the special grinding tool used for the mill-grinding operation;

(b) supporting and driving means for the beating tool used for cleaving the abrasive grains apparent on the active surface of the grinding tool;

supporting means and means imparting suitable motion to the spouts supplying lubricant fluid to the points of contact between the object subjected to the machining process and the grinding tool, on the one hand, and between the latter and the chopping tool, on the other;

(d) means for interlinking the longitudinal feed motions of the grinding and the chopping tool and that of the lubrication spout adjacent the zone of interaction between said grinding tool and the object to be processed, both said tools moving in one direction, whilst said spout is moving in the opposite direction;

(e) means for controlling said interlinking means as mentioned sub d;

means for imparting transverse motion to the chopping tool along a generating line of the grinding tool and simultaneously controlling the path to be described by said chopping tool so as to shape said grinding tool with a desirable profile;

(g) supporting and driving means for the object to be machined;

(11) means enabling the aforesaid elements to effectuate their different movements with respect to each other.

By way of example without limitation whatsoever, one embodiment will be described in detail hereinafter, with reference to the accompanying drawings, wherein:

Figures 1a and 1b, placed side by side, represent a plan view, part sectional, of the machine according to the invention; 1

Figures 2a and 2b together constitute a lateral, part sectional view of the machine; I

Figure 3 is a part sectional back elevation of the-machine, the back wall of the casing being removed; l

Figure 4 is a part lateral view of the grinding tool, the object subjected to the machining process -and -the spouts supplying lubricant fluid; 1

Figure 5 is a partial perspective view of the grinding tool with the lubricant delivery spouts;

Figure 6 is a diagrammatic representation showing the stream lines in the jets of lubricant iiuid springing-from the spouts;

Figure 7 is an enlarged view of the device'for controlling the longitudinal feed motion of the mobile parts of the equipment;

Figure 8 is an enlarged view of the device for-cleaving or chopping the abrasive grains of the grinding tool.

Referring to the drawings representing the'main elements of the machine, the grinding tool 1 is'preferably composed of a resinous product containing abrasives, said product being of such hardness, that the abrasive grains will not be torn out by the cutting nor by the pressure acting on the tool; preferably also said grinding tool is similar to the grinding wheel with a felloe such-ashas been disclosed in another patent in the name of theapplicant, according to which the ring shaped grinding tool is mounted on a felloe 2 secured on the flange 3'fixed on the nave 4. The latter, in the present case; has a conical bore 5 tightly fitting on the conical portion 6 of a shaft 7, said grinding tool being firmly secured on said shaft by means of a tightening nut 8 screwed-om the threaded end 9 of said shaft, said nave 4 being-alsosecured against angular displacement with respect=to said conical check 6 by means of a cotter 10. Said'shaft is supported in a bearing 11, axial displacementof said shaft being prevented by a shoulder 12 in conjunction with a nut 13 bearing against either side of said axle bearing 11. Secured on the free end of said shaft projecting from said bearing, there is provided a pulley-14; connected by means of a belt 15 to another pulley 16,-the latter being secured on the shaft of an electromotor L7.

The bearing 11 as well as the electric motor are-fixed on a slide 18 capable of longitudinal motion and supported and guided on a pair of slide bars 19-40.

The slide or carriage 18 comprises a nut-21 having a threaded hole extending lengthwise with respect tothe machine. This threaded hole cooperates with- ,the threaded end 22 of a shaft 23 having longitudinal grooves on a major part of its length. On the smooth intermediate part of this shaft 23 is mounted a'pinion 24 with helical teeth and laterally provided with a' wide coaxial conical bore, an axially movable clutch part 2 5 being slidably mounted on the grooved part of said shaft 23, said clutch part having on one side a conical boss directed towards the conical bore of said pinion, and on the other side a peripheral groove cooperating with the prongs 26-27 of a fork member pivoted as at 28 and provided with a handle 29, said shaft 23 further carrying a sleeve 30 butting, via a thrust ball bearing 31, against a terminal gland or stop ring 32, the latter being secured in a bushing 33 fixed to the case-34, --acompression spring 35 being disposed betweenesaid' axially slidable clutch part 25 and said sleeve 30. Thefree end of said shaft 23 may eg be squared, to receive a hand crank lever or a hand wheel (not shown):-The pinion 24 is in permanent gear with the endless-screw portion 36 of a spindle 37, the latter being supported at both ends by bearings, 38 and 39 respectively, ;fiXed to the casing 34. In order to ensure perfect-5stability of the shaft 23, the latter is also supported by an intermediate bearing 40. As particularly shown in Figures 7 1b, 2b and especially in Figure 8, the choppingor dressing tool provided adjacent the grinding tool, in the present example, consists of a percussion element 41 fitted in a cylindrical head' 42 secured on the end of a rod 43, said head being slidably mounted within the front side bore of a cylindrical body 44 enclosing a compression ping tool thus formed is fixed on a carriage 50, which is in turn supported and guided by a slideway 51 paralleling the axis of rotation of the grinding tool, said slideway being fixed on a carriage 52, which is again supported and guided by parallel slide bars extending lengthwise. Said carriage 52 comprises a nut 55 having a threaded hole extending lengthwise with respect to the machine. In said nut is engaged a screw spindle 56 having equal but opposite pitch as compared with the screw spindle 22 controlling the longitudinal feed motion of the grinding tool. way, the terminal part of a shaft 57, which also comprises another threaded portion 58 having equal but opposite 'pitch as compared with the first mentioned threaded portion '56, a smooth portion 59 and a portion 60 having longitudinal grooves. The second threaded portion 58 is engaged in the threaded passage 61a of a cross member 61 terminated, at both ends, by a

pipe clamp

62 and 63 respectively, whereby the

pipes

64 and 65 respectively, are secured to said cross member. The smooth part 59 is supported by a bearing 66.

The drive and clutch means of the shaft 57 are identically equal to those of the shaft 23. In fact, there is again provided a pinion 24' mounted on the smooth 'portion'of said shaft 57 and laterally provided with a wide coaxial conical bore, an axially movable clutch" part being slidably mounted on the grooved portion of said shaft 57, said clutch part having on one side of a conical boss directed towards the conical bore of said pinion, and on the other side a peripheral groove cooperating with the prongs 2627' of a fork memberwheel (not shown). The pinion 24' is in permanent gear with another endless screw portion 67 of the afore Said screw spindle 56 constitutes, in a in detail hereinafter in the description of the operation of the machine.

Connected to the conduit 64 by a support 74a there is provided a branch conduit, e.g. a flexible tube 74 leading to the carriage 50 and debouching close upon the point 41 of the chopping tool of the grindstone. With a view to efiectuating transverse motion of the chopper along the width of the grinding tool, said carriage 50, by

means of a projecting part 75, is fixed to the rod 76 of a piston 77, by means of a nut 78 screwed on the thinned and threaded end of said rod 76. Said piston 77 is housed in a cylinder 79 secured on the aforementioned carriage 52, so that it is subject to longitudinal 'motion, i.e. it follows all longitudinal movements of the carriage 50 carrying the chopping tool. Debauching into either end of the cylinder 79 there is provided a conduit, 80-81 respectively, communicating with a source of a pressure fluid via a device for controlling or regulating the mentioned spindle 37. The conduits 6465 terminate in i a T-junction 68, wherethrough said conduits communicate vra a connecting pipe 69 with a source of an adequate lubrrcant. To the other end of said conduits 6465 are connected spouts 70-71 of a very particular 1 form and profile. In fact, as shown particularly in Figures 4, 5 and 6, said spouts extend on the entire width of the grinding wheel 1. The shape of said spouts is such, that their face nearest to the grinding wheel 1,

. while gradually drawing nearer to the periphery of said admission and eduction of said pressure fluid. The rear- Ward extending free end of the rod 43 integral with the chopping tool, by the action of the compression spring 45, is made to bear against a cam 82, which is interchangeable according to the transverse profile to be obtained on the grinding tool, said cam being fixed on the cylinder 79, e.g. by means of bolts 83-84.

With a view to eflectuating and controlling the longitudinal feed motion of the mechanisms driven by the common shaft 37, the latter carries a ratchet wheel 85 duly secured on said shaft, as well as a rocker 86 freely rotatable on said shaft and having a pawl 87 pivotally mounted atone end thereof, the opposite end of said rocking lever 86 being linked, by means of the pivot 89, with one end of a rod 90, said rod having a piston 91 fixed to its other end, said piston being housed in a cylinder 92 pivoted to the casing 34 of the machine by means of a pivot 93. Debauching at either end of said cylinder 92, there is provided a conduit 94--95 respectively, communicating via suitable control means with a source of a pressure fluid. V

Surrounding said ratchet wheel 85 on part of its periphery there is provided an arcuate strip 96 concentrically disposed, and having an arcuate rack portion secured to one of its ends, said rack gearing with the teeth ofa pinion 98, which is mounted on a shaft 99 provided with a handle 100. The latter carries a stud 101 capable of axial displacement so as to be engageable in one of a series of holes 102 provided in an arcuate strip 103, which is mounted concentrically with said shaft 99. The object to be processed may be clamped in position in the way as usual for mechanical operations such as turning and the like. It may for instance be fixed between a chuck 109 and a back center 104. The chuck 109 has a shaft 110 supported by a bearing 111 integral with the base of the machine. The means for securing said object P are mounted on a carriage 105, which can be displaced by means of a leading screw 106 driven by a prime mover (not shown). The driving mechanism for rotating said object P includes a pulley 112 keyed upon the shaft 110 and driven by an endless belt 113 from a pulley 114 keyed upon a motor shaft 115 of an electromotor 116. Adjacent the grinding tool and the chopper associated therewith, the housing 34 is provided with an opening normally covered with a protecting screen or flap 107 hinged as at 108. Said screenor flap 107 may e.g. be made of transparent material. The assembly as described above may of course be completed with all accessories as usually provided in machine tools known in the art.

The operation of the machine as hereinbefore described and shown in its main elements in the accompanying drawings, may substantially be understood as follows:

. the grinding tool 1 duly secured on the shaft 7 is continuously rotated at high speed and in the appropriate direction, via the pulley 16, the belt 15 and the pulley 14 fixed on said shaft 7, by the electromotor 17. Said grinding tool 11 operates on said object P so that metal is removed from said object at high speed and in large quantities in the form of relatively long and very narrow shavings. During this operation the chopping tool represented diagrammatically as a pointed percussion element 41 of great hardness, is engaged in a reciprocating motion according to a generating line of said grinding tool 1. This reciprocating movement is obtained by alternately admitting and letting off a pressure fluid through the one and the other of the conduits 80-81 debouching into either end of the cylinder 79. As a result the piston 77 is driven alternately towards the one and the other end of said cylinder, whereby the rod 76 as well as the carriage Si) is engaged in the same reciprocating movement. On said carriage is mounted the complex comprising the hollow body 44 as well as the chopping tool and its support. The carriage 50, positively guided by the slideway 51, is thus engaged in a rectilinear reciprocating movement parallel to the rotation axis of the grinding tool. However, during this rectilinear transverse motion, the chopping tool is simultaneously engaged in an axial translational movement on account of the fact, that it is acted upon by the spring 45 urging the back end of the rod 43 against the fixed cam 82. The track along which the back end of said rod 43 is guided by said cam 82 is made identical with the transverse profile which must be given to the grinding tool 1. Consequently the chopping tool 41 perfectly follows a path identically equal to the wanted profile of the grinding tool, thereby ensuring said profile to be maintained until the grinding tool is completely worn off.

Due to the very action of the chopping tool 41 on the grinding tool, the latters diameter is very slowly but gradually reduced, which entails the necessity of a continuous feed motion, whereby said chopping tool is displaced towards the axis of the grinding tool. In the machine described this displacement is produced by a translational motion of the whole mechanism carrying the chopper as well as the means for producing the transverse motion of the latter. With this end in view the shaft 57 is automatically given a rotational movement in exact accordance with the gradual reduction of the diameter of the grinding tool 1. The direction of rotation of said shaft 57 is such as to cause the carriage 52, which carries the entire mechanism responsible for the movements of the chopper, to move towards the grinding tool at a rate corresponding to the reduction of the diameter of the latter. At the same time the whole assembly comprising the grinding tool 1, its driving mechanism, the chopping device and the driving mechanisms of the latter, must be engaged in a translational motion towards the object P to be processed, the rate of said movement being determined by the operating conditions and the depth of the cavities to be produced in the object being processed. This general translational motion is eifectuated by automatically rotating the screw spindle 22, which by its rotation displaces the nut 21, whereby the same movement is imparted to the slide 18 and to all elements mounted thereon. This translational motion thus proceeds in the same direction as the aforesaid translational feed motion of the chopper and the grinding tool.

Finally it is also necessary, that the lubricant delivery spouts 7071 be gradually shifted in accordance with the reduction of the diameter of the grinding tool 1, but in this case the movement, though quantitatively equal to that of the chopper, must proceed in the opposite sense in order that projection of lubricant fluid onto the zone of contact between the object to be processed and the grinding tool be continuously ensured. This motion of the spouts 70-71 is produced by the rotation of the threaded portion 58 of the shaft 57. The reverse translational movement of the spouts 7071 with respect to the axial feed motion of the chopper of the grinding tool is due to the fact, that the portion 58 is threaded in the opposite sense with respect to the threading of the portion 56. The provision of longitudinal grooves at the end of both

shafts

23 and 57 enables said axial feed motions to be produced without said

shafts

23 and 57 being prevented from being driven into rotation, together with the elements mounted thereon. Synchronism between these different feed motions is ensured by the combined effect of providing the same pitch for the threaded portions 225658, providing equal transmission means for both

shafts

23 and 57 and providing common driving means for both said shafts.

Said

shafts

23 and 57 may also without difliculty be rotated independently of each other, by manual means. To achieve this, in the case of the shaft 23, it suflices to throw the lever 29 in order to disengage the conical boss of the clutch part 25 from the conical bore of the pinion 24. In this way instant decoupling of the shaft 23 is obtained, the latter thus becoming independent of the driving spindle 37 and all elements coupled therewith. After mounting a crank lever or hand wheel on the square end of said shaft 23 the threaded portion 22 may be rotated manually, whereby the slide 18 as well as all devices mounted thereon, may be shifted forward or backward at will. Particularly, by this means, it is possible to effectuate the initial positional adjustment of the grinding tool in accordance with the requirements of the object P to be processed. In a similar way, the shaft 57 may be actuated individually, after throwing the lever 29, whereby the clutch part 25' is disengaged from the pinion 24. After placing a crank lever or a hand wheel on the square end of said shaft 57, it will be possible to manually rotate the threaded portions 56-58 having opposite pitch, thereby to produce automatically and simultaneously the positional adjustment of both the chopping tool 41 and the lubricant delivery spouts 70-71 relative to the grinding tool 1. If on the other hand both said clutches of the

shafts

23 and 57 are in their normal position as particularly indicated in Figure lb, said shafts are positively coupled with their respective pinions 24 and 24'; the latter are permanently engaged with the threaded portions 36-67 of the common drive shaft 37. It suffices, then, to determine correctly the rotational movements of said shaft 37, in order to ensure perfect synchronism between the different feed motions as described hereinbefore. This may be achieved by simply placing the lever 100 in a position corresponding with the number of teeth of the ratchet wheel it is desired to uncover, i.e. the number of teeth by which said ratchet wheel must be advanced each time the rocking lever 86 with the pawl 87 passes. By displacing this lever 100, the pinion 98 is made to turn about its axis 99, whereby the arcuate rack portion 97 is shifted in one or the other direction, resulting in a left or right shift of the opposite end of the masking strip 96. Each of the holes 102 might e.g. be made to correspond with a tooth of the ratchet wheel 85 in such a way, that if said lever is successively brought into alignment with holes numbered 1, 2, 3, 4, 5, etc., this would cause one, two, three, four, five, etc. teeth of the ratchet wheel to be uncovered. The oscillating angular movement of the rocker 86 being determined by the constant amplitude rectilinear reciprocating motion of the piston 91 within the cylinder 92, said oscillating angular movement of the rocker 86 is also constant, so that this simple arrangement provides for preset control of rotational motion of the common drive shaft 37, consequently of the synchronized feed motions of the slide 18, the chop ping tool and the lubricant delivery spouts of the grinding tool. The admission and control of the pressure fluid flowing alternately through the conduits 9495 into cylinder 92, as well as of the pressure fluid flowing alternately through the conduits 9495 into the cylinder 79 Which controls the movement of the carriage supporting the chopper, may be elfectuated by any known means.

It is to be understood that the essential and characteristic features of the machine as set forth in the specification may be embodied in, or replaced by any device or mechanism equivalent, or operating in an equivalent way, to those which, simply by Way of an example, have been specifically described and illustrated in the accompanying drawings.

What I claim is: t

1. A grinding machine, comprising a grinding tool containing abrasive grains, supporting means for said grinding tool, meansfor imparting rotational motion to said grinding tool, means for imparting longitudinal feed motion to said supporting means of'said grinding tool, dressing means adapted to cleave abrasive grains apparent on the surface of said grinding tool, supporting ,means said longitudinal feed motion of said grinding tool, said longitudinal feed motion of said dressing means and said feed motion of said first lubricant delivery means, so as to cause the last said feed motion to proceed in an opposite direction with respect to said first and second feed motions, control means for controlling said interlinking' means, means for imparting reciprocating transverse motion to said dressing means, means controlling the shape of the transverse path described by said dressing means,

supporting means for the object to be ground, means for rotating said object to be ground.

2. A grinding machine, comprising a grinding tool containing abrasive grains, supporting means for said grinding tool, means for imparting rotational motion to said grinding tool, slidingly supported means carrying said supporting means as well as said rotation imparting means of said. grinding tool, means for imparting to said sliding means a feed motion parallel to the longitudinal axis of said machine, dressing means adapted to cleave abrasive grains apparent on the surface of said grinding tool, supporting means for said dressing means, means for imparting longitudinal feed motion to said dressing means, lubricant delivery means adapted to project lubricant fluid onto the contact points between the object to be ground and said grinding tool, lubricant delivery means adapted to project lubricant fluid onto the contact points between said grinding tool and said dressing means, supporting means for said first and second lubricant delivery means,- means for imparting longitudinal feed motions to said first and second lubricant delivery means, mechanical means for interlinking said longitudinal feed motion of said sliding means, said longitudinal feed motion of said dressing means and said feed motion of said first lubricant delivery means, so as to cause said last feed motion to proceed in a direction opposite to said first and second feed motions, means for controlling said interlinking means, means for imparting reciprocating transverse motion to said dressing means, supporting means for the object to be ground and means for rotating said object.

3. A grinding machine, comprisingla grinding tool containing abrasive grains, supporting means for said grinding tool, means for imparting rotational motion to said grinding tool, a sliding support carrying said supporting means and said rotation imparting means of said grinding tool, said sliding support comprising a nut, a

, shaft extending parallel to the longitudinal axis of said "nut of said sliding support, a friction clutch mounted on said longitudinal shaft, one part of said friction clutch being mounted on said smooth intermediate portion of said longitudinal shaft, the complementary part of said friction clutch being engaged on said grooved portion of said shaft so as to be capable of axial displacement into engagement with said first part of said friction clutch, said complementary clutch part being formed with a peripheral groove, a manual control member having a forked end portion, the prongs of said forked end portion being slidably engaged in said peripheral groove of said complementary clutch part, a drive shaft transversely disposed with respect to said longitudinal shaft and having a portion formed as an endless screw, said f first clutch part being integral with a pinion having helical teeth, said pinion being permanently in gear with said endless screw portion of said transverse drive shaft, means for imparting rotational motion to said transverse drive shaft, dressing means adapted to cleave abrasive grains apparent on the surface of said grinding tool, supporting means for said dressing means, means for imparting longitudinal feed motion to said dressing means, lubricant delivery means adapted to project lubricant fluid onto the contact points between the object to be ground and said grinding tool, lubricant delivery means adapted to project lubricant fluid onto the contact points between said grinding tool and said dressing means, supporting means for said first and second lubricant delivery means, means for imparting longitudinal feed motions to said first and second lubricant delivery means, the means imparting longitudinal feed motions to said dressing means and said first lubricant delivery means, respectively, being so interlinked with each other and with said longitudinal shaft as to cause the feed motion of said first lubricant delivery means to proceed in a direction opposite to the longitudinal feed motions of said dressing means and said grinding tool respectively, supporting means for the object to be ground and meansfor rotating said object.

'4. A grinding machine, comprising a grinding tool containing abrasive grains, supporting means for said grinding tool, means for imparting rotational motion to said grinding tool, means for imparting longitudinal feed motion'to said supporting means of said grinding tool, dressing means adapted to cleave abrasive grains apparent on the surface of said grinding tool, supporting means for said dressing means, means imparting a longitudinal feed motion to said dressing means, lubricant 'delivery means adapted to project lubricant fluid onto the contact points between the object to be ground and said grinding tool, lubricant delivery means adapted to project lubricant fluid onto the contact points between said grinding tool and said dressing means,'supporting means for said first lubricant delivery means, supporting means for said second lubricant delivery means,.a shaft extending parallel to the longitudinal axis of said machine, said shaft having a first threaded portion, a second threaded portion, a smooth portion and an end portion formed with longitudinal grooves, said first and said second threaded portions having equal but opposite pitch, said supporting means of said dressing means having a nut engaged with said first threaded portion of said shaft, said supporting means for said first lubricant delivery means having a threaded hole engaged with said second threaded portion of said shaft, a friction clutch mounted on said shaft, one part of said friction clutch being mounted on said smooth intermediate portion of said shaft, the complementary part of said friction clutch being engaged on said grooved end portion of said shaft so as to be capable of axial displacement on said shaft into engagement with said first part of said friction clutch, said complementary clutch part being formed with a peripheral groove, a manual control member having a forked end portion, the prongs of said forked end portion being slidably engaged in said peripheral groove of said complementary clutch part, a drive shaft transversely disposed with respect to said longitudinal shaft and having a portion formed as an endless screw, said first clutch part being integral with a pinion having helical teeth, said pinion being permanently in gear with said endless screw portion of said transverse drive shaft, means for imparting rotational motion to said transverse drive shaft, the means imparting longitudinal feed motion to said supporting means of said grinding tool being so interlinked with said longitudinal shaft as to cause the feed motion of said supporting means of said grinding tool to proceed in the same direction as the longitudinal feed motion of said dressing means, supporting means for the object to be ground and means for rotating said object.

5. A grinding machine, comprising a grinding tool containing abrasive grains, supporting means for said grinding tool, means for imparting rotational motion to said grinding tool, a first sliding support carrying said supporting means and said rotation imparting means of said grinding tool, dressing means adapted to cleave abrasive grains apparent on the surface of said grinding tool, supporting means for said dressing means, a second sliding support carrying said supporting means for said dressing means, lubricant delivery means adapted to project lubricant fluid onto the contact points between the object to be ground and said grinding tool, lubricant delivery means adapted to project lubricant fluid onto the contact points between said grinding tool and said dressing means, supporting means for said first lubricant delivery means, supporting means for said second lubricant delivery means; a first shaft extending parallel to the longitudinal axis of said machine, said shaft having a threaded end portion, a smooth intermediate portion and a longitudinally grooved end portion, said first sliding support having a nut engaged with said threaded end portion of said first shaft, a first friction clutch mounted on said first shaft, one part of said friction clutch being mounted on said smooth intermediate portion of said first shaft, the complementary part of said first friction clutch being engaged on said grooved portion of said first shaft so as to be capable of axial displacement on said first shaft into engagement with said first part of said first clutch, said complementary clutch part being formed with a peripheral groove, a first manual control member having a forked end portion, the prongs of said forked end portion being slidably engaged in said peripheral groove of said complementary clutch part; a second shaft extending parallel to the longitudinal axis of said machine, said second shaft having a first threaded portion, a second threaded portion, a smooth portion and an end portion formed with longitudinal grooves, said first and second threaded portions of said second shaft having equal but opposite pitch, said second sliding support having a nut engaged with said first threaded portion of said second shaft, said supporting means of said first lubricant delivery means having a threaded hole engaged with said second threaded portion of said second shaft, a second friction clutch mounted on said second shaft, one part of said second friction clutch being mounted on said smooth portion of said second shaft, the complementary part of said second friction clutch being engaged on said grooved end portion of said second shaft so as to be capable of axial displacement on said second shaft into engagement with said first part of said second friction clutch, said complementary clutch part being formed with a peripheral groove, a second manual control member having a forked end portion, the prongs of said forked end portion being slidably engaged in said peripheral groove of said complementary clutch part of said second clutch, a drive shaft transversely disposed with respect to both said first and said second shaft and having a first portion adjacent said first shaft formed with a helical groove, and a second portion adjacent said second shaft formed with a helical groove, said first clutch part of said first friction clutch being integral with a pinion having helical teeth, said pinion being permanently engaged with said first helical portion of said transverse drive shaft, said first clutch part of said second friction clutch being integral with a pinion having helical teeth, said last pinion being permanently engaged with said second helical portion of said transverse drive shaft, and means for imparting rotational motion to said transverse drive shaft, supporting means for the object to be ground and means for rotating said object.

6. Machine as claimed in claim 5, in which said means for imparting rotational motion to said transverse drive shaft comprises a ratchet wheel having teeth and secured on said transverse drive shaft, a rocking lever freely mounted on said drive shaft, said rocking lever having a pawl pivotally mounted on one end thereof, said pawl" being disposed and adapted so as to be able to engage the teeth of said ratchet wheel, a cylinder, a piston sliding within said cylinder, said piston being secured to a rod pivotally connected to the other end of said rocking lever, pressure fluid supply pipes debouching into either end of said cylinder, a first arcuate strip rotatably mounted concentrically with said ratchet wheel and adapted to be interposed between said pawl and said teeth of said ratchet wheel so as to mask said ratchet wheel on part of its circumference, said first arcuate strip having an arcuate rack portion mounted on one end thereof, a pinion secured on a shaft, said last pinion being in gear with said arcuate rack portion, a lever secured on said shaft of said last pinion, a second arcuate strip fixedly mounted concentrically'with said last pinion and having a plurality of spaced holes contrived therein, said lever having locking means engageable in any of said holes so as to lock the gear comprising said lever, said pinion and said first arcuate strip in any of a plurality of predetermined positions.

7. A grinding machine, comprising a grinding tool containing abrasive grains, means for imparting rotational motion to said grinding tool, means for imparting longitudinal feed motion to said grinding tool and said rotation imparting means, dressing means adapted to cleave abrasive grains apparent on the peripheral surface of said grinding tool, a rod mounting said dressing means on one of its ends, a piston secured on said rod, a cylindrical body disposed coaxially with said rod, said piston being slidably adjusted in a cylindrical bore of said body, guiding means comprising a profiled edge extending substantially at right angles with said rod, resilient means adapted to urge the free end of said rod against said guiding edge, a carriage mounting said cylindrical body, a slide way adapted to guide and support said carriage and disposed so as to permit rectilinear reciprocating motion of said carriage in a direction parallel to the axis of rotation of said grinding tool, means for imparting longitudinal feed motion to said slide way, lubricant delivery means adapted to project lubricant fluid onto the contact points between the object to be ground and said grinding tool, lubricant delivery means adapted to project lubricant fluid onto the contact points between said grinding tool and said dressing means, means for imparting longitudinal feed motion to said lubricant delivery means, supporting means for the object to be ground and means for imparting suitable motions to said object to be ground, said means for imparting longitudinal feed motions to said grinding tool, said dressing means and said first lubricant delivery means being mechanically interlinked so as to cause the feed motion of said first lubricant delivery means to proceed in a direction opposite to that of said dressing means and that of said grinding tool.

8. Machine as claimed in claim 7, further comprising a cylinder mounted on said carriage, a piston slidably ad justed within said cylinder, said piston being mechanically linked with said carriage carrying said chopping means, pressure fluid supply pipes debouching into either end of said cylinder, this arrangement being such as to enable imparting rectilinear reciprocating motion to said carriage in a direction parallel with the rotation axis of said grinding tool, by alternately, admitting pressure fluid through the one and the other of said supply pipes, said guiding edge being in, fixed relationship with respect to said cylinder and acting to transform said rectilinear motion of said carriage into transverse motion of said dressing means along a prescribed path.

9. A grinding machine, comprising a grinding tool containing abrasive grains, supporting means for said grinding tool, means ,for imparting rotational motion to said grinding tool, means for imparting longitudinal feed ino- 'said pipes being connected to said lubricant delivery 'means, a cross member uniting said pipes and having a threaded hole formed therein, a shaft extending parallel 'to the longitudinal axis of said machine and having a threaded portion engaged in said threaded hole of said cross member, means for imparting suitable rotation to said shaft, lubricant delivery means adapted to project lubricant fluid onto the contact points between said grinding tool and said dressing means,'supporting means for said second lubricant delivery means, means for imparting suitable feed motion to said second lubricant delivery means, means for imparting reciprocating transverse motion to said dressing means, means controlling the shape of the transverse path described by said dressing means, supporting means for the object to be ground, means for imparting suitable motions to said object to be ground, said means for imparting longitudinal feed motion to to proceedin a directionopposite to the feed motion of said second lubricant delivery means 10. Machine as claimed in claim 5, in which said first and said second, helically grooved portions of said transverse drive shaft have equal pitch going in the same direction, said first helically grooved portion being in engagement with the upper side of said pinion of said first clutch, said second helically grooved portion being inengagement with the lower side of said pinion of said second clutch.

11. Machine as claimed in claim 1, in which said first lubricant delivery means comprise a pair of delivery spouts having gradually flattening whistle-like ends extending substantially on the whole width of the grinding tool, said ends being provided with a cut-away opening, said spouts being disposed on either side of the processing zone so as to penetrate as deeply as possible into the nips between the grinding tool and the object to be ground.

12. Machine as claimed in claim 9, which said second lubricant delivery means comprises a flexible tube branched off one of said lubricant supply pipes, the free end of said flexible tube being fixed on said supporting means of said chopping means, said flexible tube supporting means of said chopping means, said flexible tube debouching opposite and in proximity of the operative end of said dressing means.

References Cited in the tile of this patent V UNITED STATES PATENTS 1,765,890 Vates June 24, 1930 2,194,422 Flygare et al Mar. 19, 1940 2,310,977 Mathys Feb. 16, 1943 2,720,062 Fouquet Oct. 11, 1955