US2417413A - Centerless grinding machine - Google Patents

Description

March 18, 1947. c w op ms 2,417,413

CENTERLESS GRINDING MACHINE Filed Jan. 5, 1945 2 i t 1 March 18, 1947. c, w, HO s 2,417,413

CENTERLESS GRINDING MACHINE Filed Jan. 5, 1945 2 Sheets-Sheet 2 ril .I

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Patented Mar. 18, 1947 2,417,413 CENTERLESS GRINDING MACHINE Cecil W. Hopkins, Waynesboro, Pa., assignor to Landis Machine Company, Waynesboro, Pa., a corporation of Pennsylvania Application January 5, 1945, Serial No. 571,518

8 Claims.

This invention relates to grinding machines of the centerless type in which the work piece is supported on a plate or work rest vertically mounted between the opposed peripheral surfaces of a grinding wheel and a control or regulating wheel. In such machines, the work piece is rotated upon the work rest and simultaneously forced against the peripheral face of the grinding wheel by the control wheel. Machines of this general type are shown in United States Patents Nos. 2,091,655 and 2,346,851.

The present invention relates more particularly to important improvements in the mounting and adjusting means for the work rest and the work locating and lead controlling device shown in the co-pendin applications of Arthur Scrivener, Serial No. 556,426, filed September 29, 1944, and Cecil W. Hopkins and Edwin M. Eigenbrode, Serial No. 557,128, filed October 4, 1944.

In the machines disclosed in the pending ap-' plications, designed principally for the grinding of cylindrical surfaces, the work rest plate is mounted upon an adjusting slide for the control wheel head and is supported at opposite side of the grinding and control wheels by two independently adjustable brackets for the purpose of positioning the work supporting surface of the work rest with respect to the axis of the grinding wheel. By reason of the independent vertical adjustment of the opposite ends of the work rest, certain inaccuracies in the proper setting of the work rest are inevitable. However, these are not objectionable in ordinary cylindrical grinding wherein the work rest plate is usually inclined relative to the grinding wheel axis so that the action of the control wheel and grinding wheel on the work will operate to move the work piece progressively during the grinding operation from between the opposed surfaces of the wheels. In such case, the degree of inclination of the work rest surface aflects only the rate of axial movement of the work-piece, which need not be accurate.

On the other hand, in machines intended primarily for the grinding of screw threads and other hel cal surfaces, the work rest plate must be inclined with respect to the axis of the grinding wheel by an amount equal to the helix angle of the thread being ground. As this setting must be made with some exactness, the independent adjustment of the work rest plate at its opposite ends. as shown in the above-identified pending applications, is not satisfactory, since the proper setting or adjustment of the work rest by such trial and error methods is laborious and timeconsuming.

Accordingly, it is the principal object of the present invention to provide means for facilitating the easy, quick and accurate adjustment of the work rest to position the work supporting surface thereof at a required definite inclination relative to the axis of the grinding wheel.

It is also another object of the invention to provide an oscillatable cradle for the work rest with means to releasably secure the same in a fixed adjusted position, and means for adjustably mountin the work rest on said cradle so that the work-piece will be supported slightly above the center of oscillation of the cradle, re-

gardless of the diameter of the work-piece.

A further object resides in the provision of a work locating and lead controlling device, mounted on the work rest cradle and simultaneously adjustable therewith relative to the grinding wheel axis.

It is also an additional object of this invention to provide a work locating device pivotally mounted on one end of the work rest cradle and embodying a lead controlling finger, together with means resisting pivotal movement of said device in one direction and yieldingly holding said finger in engagement with the work.

It is a still further object of my invention to provide a simple, unitary assembly of the work rest cradle and work locating and lead controL. ling device which will materially expedite quantity production of accurately finished work-pieces by obviating the time-consuming trial and error method of adjusting or setting the work rest and the independent setting or adjustment of the work locating and lead controlling finger with respect to the work-piece.

In general, the present invention comprehends a novel adjusting means for the work rest and the work locating means as above characterized, which comprises a very compact assembly of a minimum number of structurally simple cooperating elements which will be highly eflicient in their functional operation, as well as rugged and durable in practical use.

With the foregoing and other subordinate objects in view, the invention comprises the improved centerless grinding machine and the construction and relative arrangement of the several parts as will hereinafter be more fully described, illustrated in the accompanying drawings, and subsequently incorporated in the subjoined claims.

In the drawings, wherein like reference characters designate corresponding parts throughout the several views and in which I have disclosed one simple and practical embodiment of the invention:

Figure 1 is a side elevation showing one concrete example of my improved adjustable work rest and work locating mechanism, certain parts thereof being shown in section as indicated by the line ll in Figure 5.

Figure 2 is a vertical sectional view taken substantially on the line 2-2 of Figure 1. I

Figure 3 is a fragmentary sectional view take substantially on the line -33 of Figure 1.

Figure 4 is a fragmentary side elevation, partly in section, as indicated by the line 4--4 in Figure 5, and

Figure 5 is an end view showing the mounting of the work locating mechanism and being partly in section, as indicated by the line 5-5 in Fig- .ure 1.

Referring in further detail to the drawings in Figures 1 and 2 thereof, I have shown a portion of the main slide l6 upon which my imtrol wheel l6 journalled therein for adjustment relative to the work rest. Any conventional means may be provided for adjusting the main slide l0 whereby the work rest mounted thereon together with the control wheel may be adjusted as a unit relative to the periphery of the grinding wheel l8. In the present instance the peripheral face of this grinding wheel is formed with alternating V-shaped ridges and grooves indicated at for the grinding of screw threads;

In the illustrated embodiment of my invention, I provide a base 22 having alongitudinally extending rib 24 on its bottom face adapted to be seated in a transverse groove or channel 26 on the upper surface of the slide [0. The base 22 is provided with a plurality of counterbored vertical openings 28 to receive the headed attaching screws 30 adapted for engagement in threaded bores 32 in the end of slide "I, whereby said base is rigidly secured to the slide. The upper surface of the base 22 is formed with an arcuately concave seat 34 for the work rest cradle 36 having a complementary convex bottom surface for sliding contact with said seat. A concentric dovetail rib 38 is formed upon the bottom surface of the cradle and is adapted for engagement in a groove 40 formed in the upper surface of the base 22. This groove angles to the base of the groove, as at 42, while the opposite sidewall of said groove is upwardly and inwardly inclined from the base thereof to provide an overhanging V-shaped lip 44 with which one side edge face of the dovetail rib 38 on the cradle 36 is adapted to contact.

While various means might be employed for adjustably and detachably clamping the work rest cradle 36 ,on the base 22, in Figure 3 of the drawings I have shown one simple and efiective means for this purpose. Preferably, at the side of the groove 40 having the vertical edge wall 42, transverse cylindrical openings 46 are formed in the base 22 and at their inner ends communicate, at the upper sides of said openings, with the groove 46. In spaced relation to each of said openings and in axial alignment therewith, the base is provided with a threaded bore 48. In each of the openings 46a cylindrical clamping member 50 is engaged and is provided at the upper side thereof with an undercut recess 62 to receive the opposed edge portion of the rib 36 on the cradle 36. The member 56 is further formed with an'axial opening 54 counterbored at its\ outer end to receive the head of a clamping screw 56 loosely mounted in said opening. The screw headis provided with suitable means for the application of a wrench thereto and when the threaded shank of the screw is adjusted in the threaded bore 48, the member 50 is forced inwardly into clamping engagement with one side of the rib 38 on the cradle 36 and urges the said cradle transversely upon the seat 34 to force the opposite side edge of said rib into tight clamping engagement against the lip 44 on the base 22.

Above the rib 38 a laterally projecting flange 58 is formed on one side of the cradle 36, the vertical edge surface of this flange being flush with the adjacent side face of the base 22. Upon said side face of the flange 58, at a suitable location, a degree scale 60 is engraved, the individual lines of said scale being substantially radial with respect to the center of the semicylindrical surface of the cradle 36 and coact-- ing with an index line 61 provided on the side face of the base 22. It will, therefore, be understood that the amount of angular displacement of the cradle 36 with respect to the base 22 from its mean or neutral position may be directly read in degrees on the scale 60. The center of oscillation of the cradle is accurately located in the same horizontal plane as the axis of the grinding wheel l8.

As shown in Figure 2 of the drawings, the top of the cradle 36 is formed with a longitudinally extending groove 62 of rectangular form which is adapted to receive any one of a plurality of metal spacing strips -64 of a selected thickness. The groove 62 is of such depth that the strip 64 will occupy only a portion thereof, said groove above the spacing strip receiving the lower edge portion of the work rest plate 66. The opposite end portions of the cradle 36 extend for approximately the same distance on opposite sides of the control wheel l6 and grinding wheel 18 and are each formed with an upwardly projecting bifurcated lug or extension 68, the space between the separated portions of said lug being substantially equal to the width of the groove 62, and in communication with onerend of said groove. In one side portion of each lug 6 8 one or more set screws 10 are threaded for bearing contact with one side of the work rest plate 66 at each end thereof to force the plate into tight clamping engagement against the opposite side portion of the lug 68. Thus lateral shifting movement of the plate 66 relative to the supporting cradle 36 is effectively prevented.

The work rest plate 60 is centrally formed with an upwardly extending relatively narrow portion 12, one side face of which, opposed to control wheel I6, is formed with a bevelled or arcuate surface 14, providing a relatively thin upper portion of the plate extending between the contiguous peripheral surfaces of the control wheel and grinding wheel and having a transversely bevelled or inclined work-receiving top surface I6 extending downwardly from the periphery of the grinding wheel l8 towards the control wheel l6. Thus the work-piece, indicated at W, will be properly supported by the work rest plate 66 for rotation by the control wheel [6 against the peripheral grinding face of the wheel l8, in the manner described in the above-identified copending applications.

. As thus far described, it will be readily understood that by loosening the clamping members 50, the cradle 36 may be angularly adjusted relative to the base 22 to quickly and accurately position the work receiving surface 16 of the plate 66 at a desired predetermined inclination relative to the axis of the grinding wheel I8 so that the rapidity of the progressive axial movement of the work-piece in the grinding operation may bevaried as described.

For the purpose of accurate finish grinding of a work-piece having a roughly pre-formed thread, I provide the cradle 36 with a detachable unit to properly locate the thread with relation to the grooves in the peripheral face of the grinding wheel I8 and to control the lead or axial movement of the threaded workpiece. This work locating and lead controlling unit will now be described with more particular reference to Figures 1, 4 and 5 of the drawing.

As shown in Figure 1, one vertical end face of the cradle 36 is provided with a horizontal rectangular groove 18. This groove receives a rib 82 of similar form provided upon one side face of the base of a bracket member 80. This bracket is further rigidly secured to the end of the cradle 36 by a plurality of screws 84'. The base of the bracket 80 at one side edge thereof is formed with an angularly disposed upwardly extending arm 84, the lower end of this arm being provided with a lug 86 extending inwardly therefrom in spaced parallel relation to the base of the bracket. In this lug an adjustable stop pin 88 is threaded and locked in adjusted position by means of the nut 90. The purpose of this stop pin will be presently explained.

In an opening provided in the upper end of the arm 84 one end of a stud shaft 92 is rigidly fixed. preferably by means of the set screw 94 having a conical inner end coaeting with shaft 92 to urge said shaft axially and tightly hold one side face of the enlarged cylindrical section 86 of said shaft in abutting contact against the inner side face of the arm 84.

Upon the shaft 92 a bracket 98 is fulcrumed intermediate of its ends for rocking movement in a plane parallel with the plane of the work rest plate 66. I preferably journal this bracket upon the shaft 92 by means of the anti-friction bearings I00 disposed within opposite ends of the opening I02 in said bracket and having inner and outer race rings spaced apart by means of the annular spacing sleeves or bushings I04. The inner race ring of one of these hearings abuts against the shoulder formed by the shaft section 96 and the bearings are retained in properly assembled position on the shaft 92 by means of the washer I06 engaged with the outer side of the other of said bearings and the nut I08 engaged upon the threaded end IIO of the shaft 92. A hollow cap member I I2 is secured to the bracket by the screws H4 and is formed with a flange I I6 extending into the opening I02 in abutting contact with the outer face ring of the adjacent bearing.

0A suitable grade of lubricant is supplied to bearings I00 and is retained therein by means of a conventional grease seal II8 frictionally fitted within the opening of an annular cap plate I20 fixed to the bracket member 98 by means of screws I22. This cap plate also has a narrow annular flange I24 extending within the end of the opening I02 and abutting against the outer race of the adjacent bearing I00. It will be noted that the cap plate I20 is spaced from the adjacent side face of the arm 84 so that freedom of oscillating or rocking motion of the bracket 88 upon the shaft 92 is assured.

The bracket 88 at its lower end is formed with a horizontally elongated cylindrical portion I26 at right angles to the fulcrum axis of the bracket and having a cylindrical bore I28. In this bore a sleeve I30 is fitted, said sleeve having a closed outer end I32 projecting from said bore and having bearing contact against the boss I34 formed upon the base of the bracket 80. A spring I36 bears at one of its ends against the closed end of the sleeve I30 and at its other end is seated against the plug I38 slidably disposed within the inner end of the bore I28. An adjustable screw I40 threaded in the end of the bracket extension I26 and bearing against the plug I38 regulates the pressure of the spring I36 against said plug, tending to rock the bracket 98 in a clockwise direction on the said shaft 92 from the position seen in Figure 1 of the drawing. Movement of said bracket member in the counter-clockwise direction to its normal position is limited by contact of the depending lug I42 on the bracket with the adjustable stop 'pin 88. The screw I40 is locked in adjusted position by means of the nut I44 contacting the end face of extension I26 of the bracket 98.

The bracket 98 is also formed at its upper end with a horizontally elongated extension I46 having a. cylindrical bore I48. The bore I48 opens through the extension I46 adjacent to the grinding wheel I8 and from this open end of the bore the member I50 extends between the control wheel and the grinding wheel. The opposite end of the bore I48 is closed by means of the plate I52 secured to the end of the bracket extension I46 by means of screws I54. This plate has a central opening through which a rod I60 extends, said rod being threaded at its inner end, as at I58, for threaded engagement in an internal threaded section I60 of the tubular member I50. To the outer end of the rod I56 a'suitable turning knob I62 is fixed whereby said rod may be rotated to longitudinally adjust the position of the member I50 within the bore I48. A coiled spring I64 surrounds the rod I56 within the bore I48 and bears at one of its ends against plate I62 and at its other end against the base wall of the spring receiving socket I66 formed in the end of the member I50. Thus by turning the rod I56 to longitudinally adjust the member I50 the spring I64 is placed under compression and tends to urge the member I50 from the open end of said bore. Rotative movement of the member I50 within the bore I48 is prevented by means of a suitable key I68 fixed to the end of the extension I46 by the screw I10 and engaged in the external key-way I12 formed in the wall of the member I50.

Referring particularly to Figure 5 of the drawings, it will be noted that above the member I50 bracket extension I46 is formed with a transverse opening I14, the lower side of which intersects the upper side of the bore I 48. Cylindrical members I56 are fitted into the opposite ends of said bore. Each of these members is of tubular form and the wall of one member is internally threaded as at "8 while the other member is counterbored to receive a-headed adjusting screw I80. The opposing ends of the members I56 at their lower sides are provided with bevelled surfaces I82 substantially tangent to the peripheral surface of the member I50. It will thus be understood that, by adjusting the screw I in the threaded end I18 of the member I16, the opposbe set.

' The lower extremity of this fingerhas oppositely bevelled side faces providing an edge I86 dis- 1 posed transversely of the work receiving and'supporting surface I6 of the work rest plate .66 and adapted for engagement in the trough or groove of the thread on the work-piece W. The work locating finger -I84 is held in its adjusted position against vertical or rotative movement relative to the member I58 by means of the cylindrical plug I88 in the bore of member I68 urged into frictional clamping contact against one sideof the finger I84 by means of the adjustablescrew I98 threaded into the end of the bore in the member I58.

It is obvious that by adjusting the work rest cradle 36upon the base. 22 in the manner above described, the work receiving and supporting surface 16 of the plate 66 may be disposed at the required angle from the horizontal in consonance with the helix angle of the thread to be ground. The work locating and lead controlling finger I84 is first adjusted axially of the grinding wheel I8 and set in proper relationship with the thread receiving grooves of the peripheral surface of said wheel in the manner above explained. The controlwheel I6 is provided with circumferentially spaced peripheral work receiving and discharging pockets I92 as in the co-pending application above referred to. Thus in the oscillation of the control wheel the work-piece will be fed from one of said pockets upwardly over the surface 14 of plate 66 and upon the work receiving and supporting surface I6 where it is guided into proper relationship with the grooved face of the grinding wheel I8 by the finger I84. During the entire grinding operation, the lower end of this finger is in contact with the roughly formed thread of the work-piece and thus controls the lead of the thread being ground. In the adjustment of the work rest cradle 36 on the base 22, the work locating unit is, of course, also adjusted as a unit therewith so that the operation of the locatin and lead controlling device will be the same regardless of the angle at which the cradle 36 may The spring I36 acts to yieldingly urge the lower end of the finger I84 into contact with the work, and by properly adjusting the stop pin 88, the movement of the bracket member 98 in the mounter-clockwise direction in opposition to the spring I36 determines the position of the lower edge I88 of the finger I84 with respect to the threads.

It will be noted that the vertical position of the work supporting surface 16 of the plate 66 with respect to the cradle 36 is determined by the diameter of the particular workpiece and it can be accurately fixed by the use of the spacing strips 64 of various thicknesses so that the workpiece will be supported upon said surface some what above the center of oscillation of the cradle when the work-piece is parallel to the axis of the grinding wheel I 8, as shown in Figure 1 of the drawings. Therefore, for work-pieces of large diameters, thin spacing strips 64 will be used while for small diameter workpieces relativelythick spacing strips will be employed. Thus, the selection of the proper spacing strip determines the position of the work rest blade in the cradle and remains the same with respect to a. vertical planeintersecting the center ofoscillation of the cradle in all-angular adjustments of the latter.

In certain types of grinding machines, the shaft. of the control wheel I6 is mounted at its approximate geometrical center for pivotal movement in a vertical plane so that it may be set at a desired 'angle with respect to the axis of the grinding wheel. In the application and use of the present invention in connection with this type of grinding machine, the center of rocking motion of the cradle 36 is located in accurate horizontal alignment with the pivotal center-of the control wheel shaft, as well as the axis of the grinding wheel, thus insuring that the work supporting surface I6 and the work-piece thereon can always bedisposed in accurate parallel relation with the axis of the control wheel I6. This requirement is essential to the accurate grinding of a truly cylindrical surface of uniform diameter.

In the grinding of certain-kinds of work, the use of the work locating and lead controlling unit may not be required. In such a case, it can be readily detached'from the end of the cradle 36 by merely removing the screws 84'. Also when it is desired to remove the cradle 36 from the base 22, this may be readily accomplished by simply removing the members 58 so that the dovetail rib 38 on the cradle can be moved upwardly out of the groove 48 in the base'22.

From the foregoing description it is believed .that the construction, manner of use and several practical advantages of the present invention may be readily understood. It will be seen that I have devised a novel work rest supporting and adjusting means for centerless grinding machines which obviates the laborious and time-consuming operations involved in the making of separate adjustment of the work rest at opposite ends thereof. It will also be evident that the present invention is particularly advantageous for the high precision grinding of such work-pieces as threaded rods or bolts, where the pitch, helix angle and concentricity of the screw threads is of major importance. By mounting the work locating unit directly upon the supporting cradle for the work rest plate, the necessity of making a separate adjustment of the work locating finger for each adjustment or setting of said rest support is eliminated. In addition it will be seen that the present invention comprises a comparatively small,

number of elements which are of simple and durable structural form, capable of expeditious and accurate assembly, and will function in an eflicient and reliable manner to accomplish the purposes in view.

The invention may be embodied in other specific forms without departing from the spiritor essential characteristics thereof. The present embodiment is therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intendedto be embraced therein.

What is claimed and desired to be secured by United States Letters Patent is:

centerless grinding machines, comprising a work rest plate, a support for said plate, means for angularly adjusting said support to position the work receiving surface of said plate relative to the grinding wheel axis, a device mounted upon said support for movement with and relative thereto and having a finger disposed in angular relation to the path of movement of said device on the support to engage the periphery of the work piece and locate the work piece on the work rest plate with respect to the face of the grinding wheel, and means coacting with said device to yieldingly urge the same in one direction relative to the support and hold said finger in contact with the work-piece.

2. The combination defined in claim 1, in which said device is pivotally mounted on one end of the support.

3. The combination defined in claim 1, in which said device include a bracket pivotally mounted intermediate of its ends on the support, and said work locating finger is mounted on one end of said bracket, together with spring means coacting with the other end of the bracket to yieldingly hold said finger in contact with the work-piece.

4. The combination defined in claim 1, in which said device includes a bracket pivotally mounted intermediate of its ends on the support, together with means on one end of said bracket for adjustably positioning the work locating finger with respect to the pivotal axis of the bracket, and spring means coacting with the other end of the bracket to yieldingly hold said finger in contact with the work-piece.

5. Work rest supporting and adjusting means for centerless grinding machines comprising a cradle for a work rest, means for oscillatably mounting said cradle for angular adjustment about a fixed axis, means for releasably retaining said cradle in adjusted position, a work locating device mounted on said cradle for adjustment as a unit therewith, and means for angularly adjusting the position of said device relative to the cradle.

6. The combination defined in claim 5, in which said work locating device includes a work engaging finger vertically movable above the cradle, together with spring means yieldingly urging said finger into contact with the work piece.

7. The combination defined in claim 5, in which said work locating device is pivotally mounted on the cradle.

8. Work rest adjusting and supporting means for centerless grinding machines comprising a base having a concave upper surface and a concentric groove therein formed with an undercut side wall, a work rest supporting cradle having a convex surface slidable on said concave surface and provided with a dovetail rib removably engaged in said groove, and clamping means securing the cradle in adjusted position on the base including a member transversely movable in the base and coacting with one side edge of said rib to transversely shift the cradle on the base and urge the opposite edge wall of said rib into clamping engagement with the undercut side wall of said groove.

CECIL W. HOPKINS.

REFERENCE S CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,709,348 Helm Apr. 16, 1929 1,639,958 Norton Aug. 23, 1927 1,983,853 Hopkins Dec. 11, 1934 2,091.655 Scrivener Aug. 31, 1937 FOREIGN PATENTS Number Country Date 247,037 British Feb. 11, 1926 248,893 British Mar. 18, 1926

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