US460496A - Croft - Google Patents

Description

4 SheetsSheet 1.

.(No Model.)

J. S. BANOROFT. TOOL GRINDING MACHINE.

Patented Spt. 29, 1891.

W/T/VESSES:

(No Model.) 4 Sheets-Sheet 2.

J. S. BANCROFT. TOOL GRINDING MACHINE.

y. SMMM WITNESSES:

m: uonms PETERS co.. PNOTO-LITHBL, WASHINOTDN, A! c4 (No Model.) 4 Sheets-Sheet 3.

J. S. BANCROI'T.

TOOL GRINDING MACHINE. No. 460,496. Patented Sept. 29, 1891.

m5 Nomus r'nzns cm. PHOTO-LYING" wAsHmGTON, n, c.

UNITED STATES PATENT OFFICE.

JOHN SELLERS BANCROFT, OF PHILADELPHIA, PENNSYLVANIA, ASSIGNOR TO THE WVILLIAM SELLERS & COMPANY, INCORPORATED, OF SAME PLACE.

TOOL-GRINDING MACHINE.

SPECIFICATION forming part of Letters Patent No. 460,496, dated September 29, 1891.

Application filed May 12, 1887.

To all whom it may concern:

Be it known that I, JOHN SELLERS BAN- CROFT, of the city and county of Philadelphia, and State of Pennsylvania, have in vented certain new and useful Improvements in Tool- Grinding Machines, of which improvements the following is a specification.

My invention relates to machines for forming by grinding the faces and cutting-edges of cutting-tools used on machine-tools. In order to produce the best output from machine tools in the two essentials of quality and quantity, the shape of the cutting-tools which remove the material is an exceedingly important factor. In most shops the shapes of these tools have been and are left to the judgment of the individual operator, with the result that few, if any, tools in such shops are made in the best shapes. Machines have been made for many years for the purpose of grinding some forms of cutting-tools mechanically; but none of them have come into general use, either because they were too limitedin their range or because, as has generally been the case, they were constructed in defiance of the underlying principle that should govern all grinding-machines for cuttingtoolsnamely, that the area of contact between the grinding-surface of the wheel and the face of the tool should be so narrow as to approximate a mathematical linethat is, length without breadth. Machines heretofore in use have been provided with compound slide-rests, 011 which the tool to be ground was clamped and by which it could be presented to the abrading-face of the wheel and traversed across it, the motions of the slide-rests being one parallel to and one at right angles to the axis of the wheel, and whether the tool was ground on the cylindrical face or the plane side of the grindingwheel the result was in most cases the samenamely, that the face of the tool was gradually made to conform to the shape of the abrading-surface, and as the surface in coni tact increased the rate of abrasion decreased and the heating effect increased until after a certain increase of surface all abrading action was converted into heating action, to the manifest ruin of the tool, the only remedy in such machines being to change the position Serial No. 237,986. (No model.)

of the tool on the rest, so as to present a new and smaller surface.

It is an object of my present invention to provide means forrapidlyand economically forming, by grinding, the working faces of metal cutting-tools.

It is a further object of my invention to provide means whereby these faces can be accurately located with reference to each other and to the shank of the tool; and to these ends my invention consists in providing a grinding-wheel with two convex abradingsurfaces, preferably at right angles to each other, in combination with two slide-rests with their respective lines of traverse parallel to the convex abrading-surfaces of the grinding-wheel; and it further consists in arrangingarotatabletool-holdingchuckinwhich thetool to be ground is clamped, so that it can be rotated and secured at any desired'angle of rotation about the axis of the chuck, and in moving this chuck in a line parallel to the plane of rotation of a grinding-wheel; and it further consists in arranging a slide-rest to move in a line parallel to the plane of rotation of a grinding-wheel and in connecting to this slide rest a supporting-bearing for this chuck, which rotates about an axis at right angles to the axis of rotation of the chuck, whereby a face at any desired angle with the shank of the tool to be ground may be presented to an abrading-surface of a grinding-wheel; and it further consists in combining with a toolholding chuck two slide-rests arranged so that their lines of traverse are respectively parallel to a plane tangent to the abrading-surface of the grinding-wheel and perpendicular to this plane, whereby a face of a tool held in the chuck can be brought against and trav- 9o ersed across the abrading surface of the wheel; and it further consists in providing means for moving the two slide-rests that support the rotatable chuck in a line perpendicular to the lines of their own traverse and parallel to the plane of revolution of a grinding-wheel; and it further consists in so arranging a water-supply pipe that water can be directed onto the tool being ground in whatever position the tool maybe placed and too maintained in this relative position to the tool during the motion of the vertical sliderest; and it further consists in providing this water-supply pipe with universal joints provided with frictional clamps, whereby the discharging-nozzle may be instantly adjusted to and maintained in the required position; and it further consists in counter-balancing the vertically-moving weight of the slide-rest by means of a spring, whereby the work of overcoming the inertia of a counter-weight is avoided and the operationfacilitated.

In the accompanying drawings, which form part of this specification, Figure 1, Sheet 1, represents an elevation of a machine embodying one form of my present improvements. Fig. 2, Sheet 9, is a plan view of Fig. 1, showing a partial horizontal section through the center of the tool-holding chuck on the line 00 cc of Fig. 3. Fig. 3, Sheet 3, is an elevation at right angles to and from the right of Fig. 1, but on a larger scale, showing a vertical section through the slide-rests and'chuck on the line :2 y of Fig. 1. The lower part of the frame and the vertical slide-rest are shown broken to bring the rockshaft and connections onto the sheet. Fig. 4, Sheet 4, represents a sectional elevation of the jointed water-supply pipe with the means for moving it in unison with the vertical slide-rest. Fig. 5 is a plan view of the jointed water-pipe. Fig. 6 is a section through the discharge-nozzle on the line e f of Fig. at.

I prefer to hinge the adjustable toolholding chuck to the supporting-bearing in order to adapt it to receive a vibratory motion to and from the face of the grinding-wheelthat is, so-that the same machine can be used for grinding either straight or curved faced tools at will. The details and operation of the devices for grinding curved-face tools are fully described and shown in a division of this application, numbered 330,450, filed November 15, 1889, and further description here is deemed unnecessary.

This specification describes a grinding-machine arranged to grind plane surfaces and to form cutting-tools the cutting-edges of which are formed by theintersection of plane surfaces. For the purposeof this specification I shall assume that the axis of the grinding-wheel is horizontal and that the direction in which the tool is traversed past a grinding-surface of the wheel is vertical, and I shall designate the plane which is tangent to a grinding-surface of the wheel as a tangent plane.

The grinding-wheel A, Figs. 1, 2, and 3, is secured upon a mandrel a, journaled in a bearing 1), adjustable on the main frame B, in order that the abradiug-surfaces of the wheel may be kept in nearly the same position relatively to the tool-holding mechanism. The wheel A is driven in the usual way by a pulley c, secured to the mandrel a. The grindin g-wheelA is formed with two convex abrading-surfaces e 6, preferably at an angle of forty-five degrees with the axis of the wheel and at an angle of ninety degrees with each other, or, geometrically, the wheel A is formed of two frnstums of similar right cones joined at their bases, the rectilinear elements of the cones forming an angle of ninety degrees with each other. Two of the rectilinear elements which lie in the horizontal plane of the axis of the cones are indicated by the broken lines pdpd, Fig. 2, which lines are also the projections of the tangent planes, hereinbefore de scribed, of the grinding-surfaces of the wheel A, being the projection of the line of intersection of these tangent planes. This double truncated cone presents two convex grindingsurfaces e and 6', giving the advantage of two abrading-surfaces at right angles with each other, neither of which is a plane surface, so that either surface can be used, as may be most convenient.

In this specification the term convex is not used in its limited meaning of spherically protuberant, but is used in its broader sense, signifying any exteriorly-cu rved surface, such as, for instance, the rounded surface of a cylinder or cone.

The tangent planes pd andpcl make equal angles with the axis, so that the convex surfaces 6 and e are similar, and the wheel A can be reversed on the arbor in any convenient way, so as to equalize the wear due to the different amount of use to which the two surfaces may be subjected, which advantage could not be obtained if the angles were unequal.

D, Fig 1, 2, and 3, represents a chuck for holding tools on which plane faces are to be ground. It has a square or rectangular hole through it and is provided with set-screws g g, passing through from the outside into the hole perpendicular to each other and to the sides of the hole. The tool to be ground is inserted in this chuck and clamped against its base and one side or its base alone by means of these set-screws. If the tool is much smaller than the hole, it is sometimes convenient to use a packing-piecesuch as h-to avoid unnecessary length of the set-screws; but it is not essential that the tool should be in the center of the hole. The chuck D is provided with a journal the axis of which is parallel to the two sides of the square hole against which the tool is clamped, which journal rotates freely in a corresponding horizontal bearing in the adjustable supporting-bearing N, but can be firmly fixed at any desired point of this rotation by the set-screw i. A ring K, secured firmly on the journal of the chuck D, is provided with suitable graduations, (preferably divided into three hundred and sixty degrees,) and an index a, Fig. 2, is made to correspond with the zero when the base of the tool is horizontal. This index is provided with a Vernier for fine adjustment, when required.

The bearing N is fitted upon the slide-rest E and can be swung about the pivot-pin 9 in a horizontal plane through any desired are, which in the construction shown, with the two convex surfaces of the grinding wheel at lead to confusion.

ninety degrees with each other, need not exceed one hundred degrees. The bearing N can be clamped at the desired point by the bolt m, the head of which fits in the circular T-slot m in the slide-rest E. The pin 9 is secured in the slide-rest E and fits easily in a socket in the supporting-bearingN and serves as an axis about which the bearing can be swung. It is desirable to have this axis as near the end of the tool where the faces are to be ground as circumstances will permit, in order that these faces may change their position as little as possible with relation to the grinding-wheel in the various adjustments, and thus avoid an unnecessary amount of motion of the slide-rests to bring the faces in contact with the grinding-wheel. The circular T-slot m is concentric with the pin 9. The slide-rest E is provided with a flange n, the arc of which is concentric with the pin 9 and is graduated in degrees. The adjustable supporting-bearing N is provided with an index and vernier n, adjoining the flange n, and when this index coincides with the point of the graduations on the flange n the horizontal axis of the chuck D is parallel with the tangent plane pd and perpendicular to the other tangent plane pd. If the tangent planes were at any other angle than ninety degrees with each other, it would be necessary to have two sets of indices or graduations, one for each plane, which might The graduations may be upon the adjustable bearing N and the index on the flange n, if preferred.

The slide-rest E can be moved across the top of the slide-rest l in a horizontal plane by means of the screw 10 in a direction parallel to the tangent plane pd. The Slide-rest E can be moved across the top of the vertical slide-rest F in a horizontal plane by means of the screw 11 in a direction at right angles to that of the slide-rest E and parallel to the tangent plane pd.

The vertical slide-rest F, Figs. 1 and 3, can be moved up and down in a vertical line parallel to the plane of rotation of the grindingwheel, and also parallel to the line of intersection of the tangent planes pd and pd, sliding in a bearing b, carried by the main frame B of the machine. Near the lower end of the vertical slide-rest F is secured a stud c, to which is journaled one end of a linkj, the other end of which is hinged by means of the pin n to the bell-crank lever G, which is keyed to the rock-shaft 12, the journals of which are carried by the bearings q and q in the main frame B. The lever G is made in the form of a bell-crank with the arms in different planes, connected by the hub G in Fig. 3. To the lower arm G is attached the spring H, the other end of which is secured by means of the adjusting-bolt 13 to a projection 14 from the main frame B, and is adjusted so as to counterbalance the weight of the vertical slide-rest F and the parts it carries at the middle of its stroke. As the sliderest F is moved down the spring H is extended, and its action is to retard the motion of the rest, and by thus overbalancing the weight of the slide at the bottom of the stroke the return is made easier. The diminished tension of the spring at the top of the stroke underbalances the rest, the weight of which tends to arrest its motion upward and assist its return, thus facilitating the operation and avoiding the inertia resulting from the use of an ordinary counter-weight. The spring H will always return in contracting as much power as it required to extend it, as its ac tion is frictionless, and the power required to put the vertical slide-rest into oscillation by means of the lever J is therefore very slight, and this motion can be continued by the workman without fatigue. WVith the ordinary counter-weight the workman has to overcome the inertia at the beginning of each stroke and to check the momentum at the end of the stroke, and the force required to do this is not available for the return, as with the spring, and hence is entirely wasted and rapidly fatigues the operator.

In setting the tool to be ground and in adjusting it to the grinding-wheel it is desirable that the tool-holding chuck D, which is carried by the vertical slide-rest F, should be in the horizontal plane of the axis of the grinding-wheel-that is to say, midway in the vertical movement of the slide-rest. effected by means of the spring H, the tension of which is adjusted to counterbalance the weight of the slide-restF and the parts it carries when in this position.

The rock-shaft 12 has fastened to its end a hand-lever J, which is curved, as shown, to permit the horizontal swing of the chuck when holding a long tool which may project through the back of the chuck. The handle of the lever is carried up to a place convenient to the hand of the operator. The motion of this hand-lever J forward and backward imparts the up-and-down motion to the vertical slide-rest F, thus carrying a tool held in the chuck up and down across the abrading-surface of the wheel.

The operation of grinding a tool with plane faces is as follows: 0, Figs. 1, 2, and 3, represents a tool whose cutting-edges are formed by the intersection of four planes. \Vhen this tool is doing work in the lathe, it rests upon its base f, and in order to obtain the best results the planes which form the cutting-edges should make certain definite angles with this base and with each other. This tool is clamped in the chuck D with its base resting on that side of the square hole which is intended to receive it, or on a parallel packing-piece h, as shown. If the zero of the graduations on the chuck coincides with the index, the basefof the tool will be horizontal. If new the adjustable bearing N is swung about its vertical axis, so as to bring the 90 point of its graduations to coincide with the index and is clamped there, the tool would be in the position shown This is ITO in Figs. 1, 2, and 3. The side face of the tool would, if ground in this position, form a plane perpendicular to its base and would not have any clearance, to obtain which the chuck I) must be rotated about its axis the required number of degreessay three degrees-and be held there by the set-screw z', the graduations on the ring K definitely indicating the angle of rotation. By operating the horizontal slide-rests E and E the side face of the tool can be brought to touch the grinding-surface e. The vertical slide-rest F is then moved up and down by operating the hand-lever J, thus carrying the tool O past the grinding-surface e and touching it only on the line pd of the tangent plane and fulfilling the conditions required for the greatest efficiency in grinding, the slide-rest E feeding the tool against the wheel as the tool is ground away and the slide E being used to change the position of the tool from time to time to prevent grooving. The surface ground on the tool will be parallel to the tangent plane pd and to the line of'traverse of the vertical slide-rest F. The opposite side is ground in the same way after rotating the chuck D half-way round and setting to the angle of clearance required. To grind the top face, the set-screw 'i is released, the chuck D rotated until the index points to the required angle-say ninety degreesand the tool again brought in contact with the grinding-surface. lVhen the top has been finished, the end can be ground by presenting it to the grinding-surface e of the wheel, the desired clearance being obtained by moving the adjustable bearing N about its vertical axis 9 until the desired angleis obtained, in every case the face to be ground being traversed past the abradingsurface by means of the vertical slide-rest F, the four planes forming the cutting-edges being ground without removing the tool from its chuck D, and consequently all of the faces will have definite relations to each other and to the base of the tool.

If a parting-tool is to be ground having its shank at an angle or bent, the operation of grinding is the same as before, excepting that most of the faces have to be presented to the grinding wheel by using the adjustments about both the vertical and horizontal axes, the position required being determined by calculation or by the use of a gonion1eter,and then recorded in a table for future use.

The slide-rests E and E are used in conjunction to bring any face of a tool in contact with the appropriate grinding-surfaee of the wheel, and then the movement parallel to that surface is used to traverse the tool-face along the grinding-line to keep it straight and true and prevent the grinding of ridges in the toolface. If the bearing N be set so that the zero of its graduations coincides with the index, and the slide-rest F be adjusted vertically until the axis of rotation of the chuck D is in the plane of the axis of the grinding-wheel,

and if the chuck D be rotated while a tool held in it touches the grinding-surface c, then the tool will be ground to a cylindrical shape, the radius of which will be the distance from the axis of the chuck to the grinding-surface. If the bearing N be set at an angle, the tool will be ground to a conical shape. In these cases, however, the axes of the cylinder and cone will be parallel with the side of the tool instead of perpendicular to it, as is generally required in practice, for which purpose the shank of the tool must be clamped or secured at right angles to the axis of the chuck I).

The main frame Bis provided with or formed in the shape of a tank, as shown, to provide a reservoir for the water used in keeping the tool cool. To supply the water,I use a pump of any suitable kind driven as may be most convenient, and to its discharge-pipe I attach one end of a flexible hose 70, the other end of which is attached to and discharges into a system of adjustable pipes'provided with a discharge-nozzle 71. (Shown in section in Fig. 6.) This nozzle is provided with a trunnion turning freely in its bearing 72, secured to the end of the pipe 73. The trunnion is perforated, as shown, so as to allow water from the pipe 73 to flow freely through it to the nozzle 71. The upper end of the pipe is secured to the ball 74, which fits into a spherical recess provided in the casting 7 5, secured on the end of the pipe 76. A clamp 77, which fits the ball 74, serves to hold the ball 74 to its seat and prevents leak of the water and gives sufficient friction to hold the pipe 73 in any required relation to the pipe 76, while permitting easy adjustment by hand. The other end of the pipe 76 is provided with a socket 78 and clamp 79,by which it is held to place on the ball 80, secured to a pipe 81, connected with the discharging end of the hose 7 O. The adjustable-pipe system is preferably counterbalanced, as shown, by a weight 82, carried by a rod secured to the casting 78. The adjustable-pipe system is carried by a rod 83, which is guided near its upper end in a bearing Sat, secured to the main frame 13, and its lower end is carried by a lever 85, of the same length as the lever G and secured to the same shaft 12, whereby the rod 83 is moved in unison with the vertical slide F, so that when the nozzle 71 is set so as to deliver water in the proper relation to a tool being.

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formed of two frustums of cones joined at their bases and two slide-rests, each of which has a traverse parallel to an abrading-surface of the wheel,in combination with a toolholding chuck.

2. In a tool-grinding machine, a grindingwheel with two abrading-surfaces formed of two frustums of cones joined at their bases, in combination with two slide-rests, each of which has a traverse parallel to an abradingsurface of the wheel and a traverse, common to both, parallel to the plane of rotation of this wheel.

3. A grinding-wheel provided with two abrading-surfaces formed of two frustums of cones joined at their bases, in combination with a tool-holding chuck rotatable about its axis and a supporting-bearing rotatable about an axis at right angles to that of the chuck and parallel to the plane of rotation of the grinding-wheel.

4. In a tool-grinding machine, a grindingwheel, in combination with a tool-holding chuck rotatable about an axis, with an interior clamping-surface parallel to this axis, upon which the tool to be ground may be secured, and a supporting-bearing for said chuck adjustable about an axis at right angles to that about which the chuck is rotatable.

5. In a tool-grinding machine, in combination, a tool-holding chuck, a supporting-bearing in which the chuck may be rotated and secured at any angle of rotation, a slide-rest which supports and moves the said hearing at right angles to the axis of the chuck and parallel to the plane of rotation of the grinding-wheel, and mechanism for regulating the distance between the chuck and the grinding-wheel.

0. In a tool-grinding machine, a slide-rest which moves parallel to the plane of rotation of the grinding-wheel, a supporting-bearing I which is adjustable about an axis parallel to the plane of rotation of the grinding-wheel, and mechanism for regulating the distance between this supporting-bearing and the grinding-wheel, in combination with a toolholding chuck rotatable about an axis at right angles to that of the supporting-bearing.

7. In a tool-grinding machine, a grindingwheel, in combination with a tool-holding chuck rotatable about an axis approximately parallel to the tool which it holds, with mechanism for securing it at any angle of rotation, and a supportingbearing for said chuck adjustable about an axis at right angles to that of the chuck, with mechanism through which this bearing is supported and moved in two planes, one parallel to a plane tangent to the grinding-surface of the wheel and the other at right angles thereto.

8. In a tool-grinding machine, a grinding- -wheel, in combination with a tool-holding chuck rotatable about its axis, a supportingbearing adjustable about an axis at right angles to that of the chuck and parallel to the plane of rotation of the grinding-wheel, and three slide-rests which support and move this bearing in three lines, each of which is at right angles to the other two.

9. In a tool-grinding machine, a grindingwheel, a tool-holding chuck, and a system of slide-rests, in combination with an adjustable water-supply pipe connected to the movable parts of the slide-rest, which moves parallel to the plane of rotation of the grinding-wheel.

10. The combination of a grinding-wheel, a vertically-movable slide-rest that moves parallel to the abrading-face of the wheel, and an adjustable water-supply pipe movable with the slide-rest and provided with a balljoint at its discharging end.

11. In a tool-grinding machine, a tool-holding chuck, a vertical slide-rest, and mechanism substantially as described between the chuck and the vertical slide-rest, in combina tion with mechanism which operates to return these parts to a midway position in their vertical traverse whenever they are removed therefrom.

CHAS. E. PANcoAsT, JOHN L. PHILLIPS.

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