US2852892A - Automatic grinding machine - Google Patents

Description

Sept. 23, 1958 w. FLUCKIGER AUTOMATIC GRINDING MACHINE 3 Sheets-Sheet 1 Filed Dec. 27, 1956 hdwfli I?! P 23, 1958 w. FLUCKIGER 2,852,892

AUTOMATIC GRINDING MACHINE Filed Dec. 27, 1956 5 Sheets-Sheet 2 Sept. 23, 1958 w. l 'LUcKlGER AUTOMATIC GRINDING MACHINE 5 Sheets-Sheet 3 Filed Dec. 27, 1956 9 I 114 119 no 33v l E/V 7-0/8 1404/, i F4 vhf/gm United States Patent Ofifice 2,852,892 AUTOMATIC GRINDING MACHINE Willy Fliickiger, Grandc Fin, Moudon, Switzerland, assignor to John J. Schuler, Temple, Pa.

Application December 27, 1956, Serial No. 630,953

Claims priority, application Switzerland December 30, 1955 11 Claims. C1. 51-33 This invention relates to an automatic grinding machine,

and more particularly to a machine for grinding and sharpening or otherwise shaping cutting tools. It is an object of the present invention to provide means facilitating grinding and sharpening of cutting tools and like instrumentalities in a novel and greatly simplified manner which considerably enhances both the accuracy and the quality of the grinding operation.

Another object of the present invention is to provide means contributing to a novel and improved grinding machine for use in connection with sharpening of cutting tools, said machine being constructed for use with all types of cutting tools regardless of the sizes. or shapes of the latter.

Still another object of the present invention is the, provision of means redounding to rapid-acting and highly a minimum of time and with an extremely high degree of accuracy.

In general, a grinding machine constructed in accordance with the present invention includes a headstock which, together with a grinding wheel and the drive means therefor, is mounted on a first vertical axle arranged to be rotated by means of a hydraulic actuating system. The grinding wheel and drive means are further arranged for rotation as a unit with a horizontal axle disposed laterally of the grinding wheel, such rotation being effected by means of a mechanical actuating system.

A horizontal guide member, on which the headstock may be horizontally and reciprocally displaced by suitable hydraulic means, is rigidly connected with the aforesaid vertical axle. Opposite the headstock a tool holder is arranged on a second, rotatably and reciprocally mounted vertical axle, the second vertical axle and tool holder being reciprocated longitudinally of said second axle by hydraulic means and being rotated about the axis of said second vertical axle by mechanical means.

These and other objects of the invention will become further apparent from the following detailed description, reference being made to the accompanying drawings showing a preferred embodiment of the invention.

In the drawings:

Fig. 1 is a longitudinal, vertical sectional view of a grinding machine constructed in accordance with the present invention;

Fig. 2 is a sectional view of a vertically arranged tool carrier or holder adapted to be employed with the machine of Fig. 1;

Fig. 3 shows a detail of the grinding machine of Fig. 1;

Fig. 4 is a front elevational view of the upper portion of the machine and illustrates the tool holder and the grinding wheel attachment;

Fig. 5 is a top plan view of the machine portion shown in Fig. 4;

Fig. 6 is a partly sectional view of the means for I0- 2,852,892 Patented Sept. 23, 1958 2 tatably or swingably displacing the grinding wheel attachment;

Fig. 7 shows the abutmentswhich limit the extent of swinging of the grinding Wheel attachment;

Fig. 8 is a partly sectional view of a rotatable, else trically actuated control valve employed in the machine according to the present invention;

Fig. 9 is a top plan view of the valve shown in Fig. 8

Fig. .10 is a sectional view taken along the line X-X in Fig. 8 and illustrates the fluid flow control member of the valve in a first position;

Fig. 11 is a similar sectional view taken along the line X--X in Fig. 8 but illustrates the control member in a second position;

Fig. 12 is a schematic illustration of the hydraulic control arrangement used in accordance with the present in vention, the control valves being shown in section;

Fig. 13 is a plan view of a control panel for the machine according to the present invention; and

Fig. 14 is an electrical wiring diagram for the aforesaid control arrangement.

While there is shown and described herein certain specific structure embodying the invention, it will be manifest to those skilled in the art that various modifications and rearrangements of the parts may be made without departing from the scope of the invention, and that the same is not limited to the particular form herein shown and described, except in so far as indicated by the ap pended claims.

Referring now more particularly to the drawings, the machine according to the present invention includes a hollow, frame-like base 1 provided at its top or upper end with a depressed table or platform 2 in which an opening 3 is formed. Positioned over the opening 3 is a cover plate 4- having a central aperture and an eccentric aperture 4a having an axis a, the plate being further provided with a lower guide boss or hub 6 and with an upper guide boss or hub 7.

The bosses 7 and 6 are provided, respectively, with bores S and 8a, the bore 8 substantially constituting the aforesaid central aperture and being dimensioned to receive an enlarged portion 9a of a rotatable pivot member or axle 9 which carries at its upper end a slide carriage or support 11 for the headstock of the grinding wheel attachment. The lower bore 8a is appropriately dimensioned to receive a portion of the axle E9 of smaller diameter than said enlarged portion, the axle being thus supported by the bosses or hubs 6 and 7 for rotation about an axis 10.

Slidabiy disposed on the uppersurface of the slide carriage 11 is a grinding wheel table 12 having an upwardly directed extension or projection 13 on which the headstock 14 of the grinding wheel attachment is mounted. The carriage 11 thus constitutes guide means for the table 12. The headstock 14 is recessed at its upper end to accommodate and provide bearings for a horizontal axle 14a provided with a worm gear 15a, the latter meshing with and being arranged to be rotated by a worm 15b fitted with a hand wheel 15c.

Connected to the axle 14a for rotation therewith is a bracket 1412 which carries a grinding wheel 16 and its shaft 15 at one end and suitable drive means, such as an electric motor 17, at its other end. The output shaft of the motor supports a relatively large pulley 18, while the grinding Wheel shaft 15 supports a relatively small pulley 19', these pulleys being drivingly interconnected by a belt 20. As may be seen especially from Fig. 1, the shaft 15 and axle 14a are located at the same elevation above the table 12 but substantially at right angles with respect to one another. 1

Fixediy connected to the lower end of the vertical axle 9 is a plate or disc 21 which is provided with a r 3 peripheral groove or recess 22 in which two abutments 23 (see Fig. 7) are adjustably arranged. These abutments serve to define and limit the extent of the angular swinging movement of the axle or pivot member 9'and thus of the slide carriage 11 together with the table 12, headstock 14 and grinding wheelqld Advantageously, this movement-limiting function is effected through engagement of the abutments 23 with one or the other of a pair of arms 24 extending from a holder or bracket 25 fixedly attached to the lower boss or hub 6 of the cover plate 4. The engagement between the abutrnents and the arms actuates, i. e. either opens or closes, suitable control contacts or limit switches positioned on said arms and connected to a motor 26 located in the base 1 of the machine, this motor being arranged to control the feeding of a suitable pressure fluid, such as oil, to a hydraulic actuating mechanism.

Positioned beneath the motor 26 and coupled thereto is a rotary slide valve arrangement 27 which communicates with a pair of control cylinders 3t) and 31 of a reversing mechanism through valve bores or conduits 28 and 29 (see Fig. 12), the cylinders being fixedly positioned in the base. Reciprocally disposed in the cylinders 30 and 31 are pistons 32 and 32a, respectively, (Figs. '6 and 12) which are fixed to piston rods 33 extending out of the cylinders and connected at their free ends to a belt or tape 34.

The belt 34 passes around a plate or disc 35 which is fixedly arranged on the vertical axle 9 of the slide carriage or guide means 11 in such a manner that reciprocal displacement of the pistons 32 and 32a in the cylinders 30 and 31 results in a corresponding rotary displacement of the plate or disc 35 through the intermediary of a nose or projection 34a of the belt 34 extending into a suitable recess in the periphery of the disc 35. This rotary displacement is thus transmitted to the axle 9, the extent of the angular movements of the latter and of the plate or disc 35 being limited and controlled in accordance with the adjusted position of the abutments 23 on the plate 21.

Fixed to the top of the motor 26 (see Figs. 8 and 9) is a crown or ring member 36 having a recess 37 in its periphery. A shaft 40 extends vertically through the motor 26 and carries at its upper end a lever 33 provided with a roller 39, the lever and roller extending through the recess 37.

At its lower end the shaft 40 carries a rotary slide valve 41 which controls the conduits 28 and 29 and additional valve bores or conduits 42 and 43 through which the pressure fluid is led to and removed from the control .valve arrangement. The rotary slide valve 41 is provided on its periphery with a recess 44 which extends over more than one half of said periphery and with a recess 45 which extends over approximately one fourth of said valve periphery.

As will be seen from Figs. 10, ll and 12, to be more fully described hereinafter, rotary adjustment of the control valve effects a rotary or swinging movement of the slide carriage 11 together with the headstock 14 and the grinding means mounted thereon.

A container or reservoir 46 for the pressure or hydraulic control fluid, e. g. oil, is located in the base 1 of the machine, and a pressure pump 47 is arranged above the reservoir 46, the pump 47 being driven by means of an electric motor 48 interposed between the pump and the reservoir. The oil is conducted through pressure conduits 49, 49a, 49b and 490 to three different rotary slide valve arrangements I, II and III (Fig. 12), in the centers of which rotatable control valves 41a, 41 and 57, respectively, are arranged for rotation about vertical axes.

Movement or actuation of the control valves is controlled by an electric control system which may include relays, solenoids or the like connected in suitable electric circuits. Each rotary slide valve housing is provided with four pipe connections or bores through which the pressurized oil flows to and from the appropriate actuating mechanisms and thereafter back to the reservoir 46. From the latter, the oil is then again forced through the pressure conduits 49 to 49c by means of the pump 47.

The control valve arrangement 11, which constitutes a part of the means for imparting the desired swinging or rotary movements to the axle 9 and the elements carried thereby, operates as follows. In the valve position shown, the oil under pressure flows from the reservoir through conduits 49 and 4% into the bore 28 and thence through the recess of the rotary slide valve 41 and the bore 42 into the cylinder 31 at one end thereof to force the piston 32a toward the opposite end of the cylinder. A small exhaust or ventilating conduit 5% enables air to escape from the cylinder 31.

The second cylinder 30 communicates with the bore 29 through a pipe or conduit 51, the bore 29 communicating through the recess 44 of the rotary slide valve 41 with the bore 43. in this manner, oil being forced out of the cylinder 3% due to movement of the piston 32 under the action of the piston 32a, is able to how into the conduits S2 and 53b and from the latter back to the reservoir 46.

When the rotary slide valve 41 is now actuated by the above-mentioned electric control means and moved to another position, the pressure conduits 49 and 4% are connected to the bore 29 via the bore 2% and valve recess 45, whereby the oil under pressure enters the cylinder 36) through the pipe 51 to press the piston 32 downwardly. At the same time, the bore 42 communicates with the bore 4-3 via the recess and oil can flow from the cylinder 33ft, as the piston 32a is moved with the piston 32, through the pipes or conduits 52 and 53b back to the reservoir 46.

As will be readily seen, the plate or disc 35 and the axle 9 are now rotated or swung in a direction opposite to that corresponding to the illustrated position of the valve member 41, thereby moving the grinding means into a difierent end position. As before, air can be exhausted from the cylinder F4] whenever necessary through a pipe Stla.

The slide carriage 11, which is fixed to the upper end of the axle or pivot member 9, carries on a portion of its outer peripheral surface a pair of adjustably spaced abutments 53 (see Fig. 3). Extending laterally from the grinding wheel table or support 12 are limit switches 53a which project into the space between the abutments 53 and are arranged, when contacted by the latter, to actuate the electric control system for reversing the position of the rotary slide valve 41.

Located in an internal recess or cavity of the slide carriage 11 and fixedly connected to the latter is a cylinder 54 (see Figs. 1 and 12) closed at both of its ends and provided with a piston 55 reciprocal therein. The piston 55 is rigidly connected by means of a piston rod to the grinding wheel support 12. As may be seen from Fig. 12, the reciprocal movements of the grinding wheel support or table together with the headstock 14 fixed thereto, to the left and to the right as seen in Fig. 1, are effected by means of the control arrangement III which has a rotary slide valve 57 similar to the valve 41 and arranged to control the flow of oil from the pressure conduits 49 and 490.

In the illustrated position of the valve 57, a recess 58 thereof establishes communication between a bore 56 and a bore 59 which is in turn in communication with the left hand end of the cylinder 54 through a conduit 60. Accordingly, oil under pressure forces the piston 55 to the right to'effect a concurrent movement of the grinding Wheel table 12 to the right.

At the same time oil not under pressure is forced by the piston 55 from the right hand end of the cylinder 54 through a pipe 61 into a bore 62 of the housing for the rotary slide valve 57, this last mentioned oil. then flowing via a valve recess 63 and a bore 64 to a conduit 65 and therefrom to the reservoir 46 through the pipe orconduit 53b.

If the rotary slide 'valve 57 is now turned to the right to establish communication between the bore 56 and the bore 62 on the one hand and between the bore 59 and the bore 64 on the other hand, the above operation of the piston is reversed. In other words, the pressure fluid will now flow through the pipe 61 into the cylinder 54 and force the piston 55 to the left together with the grinding wheel table 12, while at the same time oil flows from the left hand end of the cylinder 54 through the conduit 60, bore 59, recess 63 and bore 64 to the pipe 65 and thence to the reservoir 46.

In order to support and rigidly hold the tool to be ground, there is provided in front of the headstock 14 an adjustable tool holder or carrier which is mounted in a bushing 67 disposed in the eccentric aperture 4a of the cover plate 4, i. e., eccentrically with respect to the boss 7. The upper edge of the bushing 67 projects slightly above the upper surface of the cover plate 4 (see Fig. 2). Fixedly attached to the lower end of the bushing 67 is a guide element 68 open at one side and provided at its upper end with a laterally extending arm 69 having a guide element 70 at its outermost extremity.

Slidably arranged in the bushing 67 is a sleeve or tube 71 which is closed at its upper end by an end wall 71a and carries at its lower end an arm 72 provided at its outer extremity with a guide rod 73, the rod 73 being received in and axially displaceable with respect to the guide element 70. A head or cap member 74 is-positioned on the upper end of the sleeve 71 and supports a bearing 75 to which an angle member 76 provided with guide ledge means 77 is adjustably connected.

A plate 78 is located on the guide ledge means 77 and is displaceable therealong by means of a suitably threaded spindle 78b arranged at the lower surface of the plate and rotatable by a hand wheel 78a. The plate 78 carries additional guide ledge means 80 oriented at right angles to the guide ledge means 77, and a head 79 is displaceably positioned on the guide ledge means 80.

The upper surface of the head 79 is provided with an arcuate recess having a circular curvature in cross-section and in which a clip plate 81 for the tool 82 to be ground is received. The junction between the head 74 and the upper edge of the bushing 67 is sealed by means of a H dust-tight bellows 74a.

-A boss or hub 83 having a bore 84 is provided at the lower end of the guide element 68 A cylindrical tube 85 is closed at its opposite ends by suitable plugs or closure members 85a and 85b and is inserted in the bore 84, being retained in position by one or more set screws 85c. A piston 86 is reciprocally arranged in the tube or cylinder 85 and is provided with piston rods 87 and 106 extending, respectively, from both sides or faces of the piston.

The upwardly directed piston rod 87 extends slidably through the plug or closure member 85a. Both the piston and the rod are resiliently supported by a helical spring 88 and are connected by means of a sleeve 89 with a vertical axle or shaft 90 which is rotatably supported in the end wall 71a of the sleeve 71 by means of a ball and socket joint 91a connected to a hand wheel 91 located on the bearing 75.

The cylinder 85 is provided with two pipe connections 92 and 93 through which oil under pressure may be selectively fed into the cylinder to move the piston 86 and thus the tool holder down or up, respectively.

Referring again to Fig. 12, it will be seen that actuation of the piston 86 is controlled by means of the rotary slide valve arrangement I. In the illustrated position of the rotary slide valve 41a, a bore 94 communicates with a bore 95 through a valve recess 97, the bore 94 being connected to the pressure conduits 49 and 49a and the bore 95 being connected to a pipe 96 communicating thi'ough the pipe connection 93 with the lower end of the 6 cylinder 85. Consequently, oil under pressure will flow into the cylinder from the conduit 49 so as to move the piston 86 and thus the tool holder assembly 76--81 upwardly.

The upper end of the cylinder 85 at the same time communicates through the pipe connection 92 with a pipe or conduit 98 connected to a bore 99 in the slide valve housing, the bore 99 communicating in turn through a valve recess 100 with a bore 101 and a pipe 102 connected to the conduit 53b. Thus, as the piston 86 moves upwardly, oil flows from the upper end. of the cylinder 85 back to the reservoir 46.

Arranged at the lower end of the cylinder 85 is a contact carrier 103 (see Fig. 2) provided with two contact arms 104 and 105 bearing limit switches disposed to co operate wih two contact or switch-actuating rings 107 formed adjacent the lower extremity of the piston rod 106. These switches are connected to the electric con trol system, whereby the flow of pressure fluid during vertical displacement of the tool holder may be controlled.

In each of the rotary slide valve arrangements, all of which are located in the base 1 of the machine, the conduits through which the pressure fluid flows may be provided with suitable flow-regulating means, e. g. valves, while each of the cylinders may be provided with ex; haust conduits similar to the pipes 50 and 50a connected to the cylinders 31 and 30, respectively.

To facilitate the operation of the grinding machine, a control panel 108 is provided on which signal or pilot lights corresponding to the various arrangements are located. The system is so arranged that the lights are extinguished during actuation of the various arrangements. The control arrangements 1, II and III are designated on the control panel by the reference numerals 109, 110 and 111, respectively. p v

In the top row of-controls on the panel 108, 112 is the control for a to and fro movement of the swingable slide 11, 113 is a push button for a single forward move ment and 114 is a push button for a single backward movement. Through a light 115 it is: indicated that pressure exists in the pressure conduits, whereas 116 indicates that the pressure pump is in operation and 117 indicates through a red light that the relays are energized. Through adjustment of the lever 118 the voltage on the motor and thus the rotational speed of the motor can be altered. Actuation of the push buttons 119 and 120 eflfects swinging of the slide 11 to the le ft or to the right, while the push button 121 limits the vertical adjustment of the tool holder. y,

Through pulling of the button 113 and depressing the button 112 the swinging slide 11 runs uninterruptedly to and fro, its path of to and fro movement being limited at its end points by means of limit switches 127 and 128. Through depressing of the button 114 the table moves back one stroke and thereafter again runs to and fro.

The radial movement is released through depression of the button 119 to the left or through depression of the button 120 to the right.

For adjusting the tool holder there is provided the button 121. Upon actuation of the latter the holder moves uninterruptedly up and down and the limiting of its movement is effected by means of limit switches 1-32 and 133. I p,

The grinding motor is driven at about 1,400 to 2,800 R. P. M. and has 380 volts applied to it. Its strength is about 0.5 H. P.

In the wiring diagram 122 designates the signal po'si- 1 tions for the tool holder, 123 the transformer, 124 fuses for the transformer, 125 fuses for the pump motor, 126 fuses for the grinding motor 17 and 118 the control for the motor 17. 115 is a signal light for the tool holder, 112 to 114 are the push buttons for effecting displacement of the table, 127 and 128 are limit switches, 119 and 120 are push buttons for actuating the tool holder and 129 and 130 are limit switches for the slide. 131 is the control for the transformer, 117 the signal light for the pump 47, 121 for the vertical movement of the tool holder and 132 and 133 the limit switches for the vertical movement of the tool holder.

This automatic grinding machine operates in the following manner:

After a workpiece, such as a tool to be ground, has been positioned in the adjustable tool holder, push buttons 112, 113 and 114 are selectively actuated to position the slide 11 and hence the grinder 16 carried thereby. Push but-- tons 119 and 120 are actuated to further swing the slide 11 to the right or left as the case may be to align the grinder 16 with the workpiece. Then the speed of rotation of the grinder 16 is adjusted through adjustment of lever 118.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent, is:

1. A machine for grinding cutting tools, comprising a hollow base having an opening in its top, a cover plate supported by said base over said opening, said cover plate being provided with a central aperture and with an eccentric aperture, a first vertical axle rotatably arranged within said base and having an upper end portion extending through said central aperture, first hydraulic means located within said base and operatively connected to said first vertical axle for rotating the same, a horizontal slide carriage fixed to said upper end portion of said first vertical axle and rotatable therewith, a table slidably disposed on said carriage, second hydraulic means operatively connected to said table for reciprocating the same on said carriage, a headstock supported by said table, a horizontal axle rotatably carried by said headstock, a bracket fixed to said horizontal axle, a grinding wheel and drive means therefor supported by said bracket with said grinding wheel facing said eccentric aperture, worm gear means operatively connected to said horizontal axle for rotating the same together with said bracket, said grinding Wheel and said drive means, a second vertical axle rotatably and reciprocally disposed within said base and having an upper end portion extending through said eccentric aperture, a tool holder connected to said upper end portion of said second vertical axle, means operatively con nected to said second vertical axle for rotating the same together with said tool holder, and third hydraulic means located within said base and operatively connected to said second vertical axle for reciprocating the same and said tool holder vertically toward and away from said grinding wheel, respectively.

2. In a grinding machine for use in sharpening cutting tools and having a base and grinding means; a first vertivcal axle rotatably arranged on said base and having an upper end portion protruding above said base, first hydraulic means operatively connected to said first vertical axle for rotating the same, guide means fixed to said upper end portion of said first vertical axle and rotatable therewith, a table slidably carried by said guide means, second hydraulic means operatively connected to said table for reciprocating the same on said guide means, a headstock supported by said table, a horizontal axle rotatably carried by said headstock, support means for said grinding means fixed to said horizontal axle and rotatable therewith, means operatively connected to said horizontal axle for rotating the same together with said support means and said grinding means, a second vertical axle rotatably and reciprocally arranged on said base and having an upper end portion extending above said base, tool holder means connected to said upper end portion of said second vertical axle, means operatively connected to said second vertical axle for rotating the same together with said tool holder means, and third hydraulic means operatively connected to said second vertical axle for reciprocating the latter together with said tool holder means vertically towardand away from said grinding means, respectively.

3. In a machine for use in grinding cutting tools and having a grinding wheel rotatable about a first horizontal axis, and holder means for gripping a tool to be ground; first supporting means carrying said grinding wheel for rotary movement about a second horizontal axis oriented substantally at right angles to said first horizontal axis, mechanical means operatively connected to said first supporting means for imparting said rotary movement thereto, second supporting means carrying both said first supporting means and said mechanical means, third supporting means carrying said second supporting means for swinging rotary movement about a first vertical axis and for linear reciprocal movement toward and away from said holder means, respectively, and in a horizontal direction parallel to said second horizontal axis, first hydraulic means operatively connected to said third supporting means for swingingly rotating the same together with said first and second supporting means and said grinding wheel, and second hydraulic means operatively connected to said second supporting means for imparting said reciprocal movement to the latter together with said first supporting means and said grinding wheel.

4. in a machine according to claim 3, fourth supporting means carrying said holder means for rotational movement about a second vertical axis spaced from said first vertical axis and for reciprocal rectilinear movement longitudinally of said second vertical axis, third hydraulic means operatively connected to said fourth supporting means for imparting said rectilinear movement to the same together with said holder means, whereby the latter and said tool when gripped thereby are selectively moved toward and away from said grinding wheel, and additional mechanical means operatively connected to said fourth supporting means for imparting said rotational movement to the latter together with said holder means.

5. In a machine according to claim 4, guide means operatively interconnected between said holder means and said fourth supporting means facilitating horizontal linear movement of said holder means along a first line parallel to said first horizontal axis and along a second line perpendicular to said first horizontal axis, and means operatively connected to said holder means for moving the same, selectively, along said lines.

6. in a machine according to claim 4, a plurality of flow control means operatively connected, respectively, to said first, second and third hydraulic means for regulating flow of hydraulic pressure fluid to said hydraulic means, and electrical means for actuating said control means.

7. A machine for grinding cutting tools, comprising a base, holder means on said base for gripping a tool to be ground, a vertical axle rotatably arranged on said base laterally of said holder means and having an upper end portion disposed above said base, first hydraulic means operatively connected to said vertical axle for rotating the same, guide means fixed to said upper end portion of said vertical axle and rotatable therewith, a table disposed on said guide means for sliding horizontal reciprocal movement, second hydraulic means operatively connected to said table for imparting said reciprocal movement to the same on said guide means, a headstock supported by said table, a horizontal axle rotatably carried by said headstock, a bracket fixed to said horizontal axle, a rotatable grinding wheel and drive means therefor supported by said bracket with said grinding wheel facing said holder means, the axis of rotation of said grinding wheel being oriented at an angle to said horizontal axle, and mechanical means operatively connected to said horizontal axle for rotating the same together with said bracket, said grinding wheel and said drive means relative to said holder means, whereby said machine is adapted to grinding of a variety of surface portions of said tool as well as togrinding of tools of various sizes.

8. A machine according to claim 7, further comprising a disc attached to said vertical axle substantially coaxial therewith, said disc being provided with a recess in its periphery, said first hydraulic means comprising a pair of spaced cylinders, pistons reciprocal in said cylinders, respectively, each of said pistons having a piston rod extending therefrom exteriorly of said cylinders, and belt means interconnecting said piston rods and extending about :at least a portion of said periphery of said disc, said belt means being provided with a projection extending into said recess, whereby upon reciprocation of said pistons in said cylinders said vertical axle is rotated together with said guide means, said table, said horizontal axle, said bracket and said grinding Wheel.

9. A machine according to claim 8, further comprising a plate connected to said vertical axle and rotatable there with, abutment means adjustably connected to said plate at spaced locations along the periphery thereof, and fixed arm means disposed in the path of movement of and engageable by said abutment means, whereby the extent of rotation of said vertical axle is defined by the spacing between said abutment means.

10. A machine according to claim 7, further comprising another vertical axle arranged on said base for rotation and axial displacement, said other vertical axle having an upper end portion disposed above said base, said holder means being connected to said upper end portion of said other vertical axle, third hydraulic means operatively connected to said other vertical axle for imparting said axial displacement to the same and thereby to said holder means, and additional mechanical means operatively connected to said other vertical axle for imparting said rotation to the latter and to said holder means.

11. A machine according to claim 10, further comprising electrical limit switches located adjacent said other vertical axle and spaced vertically with respect to one another, said other vertical axle being provided with switch-actuating means, and electric control circuit means for actuating said third hydraulic means, said limit switches being connected to said circuit means and operable, respectively, upon actuation by said switch-actuating means to affect said circuit means so as to interrupt operation of said third hydraulic means and thus limit said axial displacement of said other vertical axle.

References Cited in the file of this patent UNITED STATES PATENTS 856,662 Smith June 11, 1907

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