US2414560A - Core grinder - Google Patents

Description

Jan. 21, 1947.

J. A. ROSMAIT 2,414,560

CORE GRINDER Filed Feb. 17, 1945 s Sheets-Sheet 1 IN VEN TOR.

Miwa/ A T T'OfFA/E Y5 Jan. 21, 1-947. J. A. ROSMAJT 2,414,560

CORE GRINDER Filed Feb. 17, 1945 3 Sheets-Sheet 2 IN V EN T OR.

Mat/5 A TTORA/EIYS.

Jan. 21, 1947. J. A. ROSMYAIT coma (GRINDER Filed Feb. 17, 1945 3 Sheets-Sheet 3 INVENTOR.

ATTOE Ma s Patented Jan. 21, 1947 CORE GRINDER John A. Rosmait, Appleton, Wis., assignor to D. J. Murray Manufacturing 00., Wausau, Wis., a corporation of Wisconsin Application February 17, 1945, Serial No. 578,440

2 Claims.

This invention relates generally to the art of grinding, and relates more specifically to improvements in the construction and operation of machines for facilitating the dressing and grinding of foundry cores or the like.

The primary object of my present invention is to provide a new and useful foundry core grinder which is simple in construction, flexible in its adaptations, and highly efficient in operation.

When manufacturing sand cores for foundry use, it frequently becomes desirable to construct the cores in the form of mating sections which are subsequently pasted or glued together to produce the completed cores. In order to produce perfect final core assemblages, the sections of each core must be dressed or ground so as to provide accurate plane and smooth surface coaction along the pasted areas, and to also obviate broken bounding edges at these coasting surfaces. This grinding operation has heretofore been rather slow and tedious, especially when producing large quantities of similar sectional cores; and in many cases large quantities of core sections either had to be scrapped, or the cost of production was materially increased due to subsequent patching necessitated by broken edges or the like. The prior methods of manufacturing sectional sand cores have therefore proven quite unsatisfactory and costly for various reasons, and it has heretofore been impossible to rapidly produce perfect composite cores having neat and highly finished appearance, at moderate cost.

It is therefore a more specific object of'the present invention to provide an improved core grinding machine which may be utilized to overcome all of the above mentioned difficulties, and which is adapted to quickly and effectively produce smooth and perfectly fiat surfaces of coaction upon the core-sections, without breaking or marring the bounding edges of these surfaces.

Another specific object of this invention is to provide an improved core grinding assemblage of relatively compact and durable construction, which may be disposed in any convenient location, and safely operated by a novice to produce excellent results. i

A further specific object of my invention is to provide an improved core grinding mechanism having large capacity, and adapted to be readily manipulated and adjusted to dress sand cores or the like, having diverse sizes and shapes.

Still another specific object of the invention is to provide a precision core grinderhaving enormous capacity, and which is operable without danger of chattering to produce perfectly Smooth and clean surfaces of coaction, thereby effecting great savings in paste and labor necessary for production of the final cores.

An additional specific object of this invention is to provide an efiicient core dressing mechanism which may be constructed and operated at moderate cost, and in which all parts are readily accessible for inspection while being thoroughly protected against sand and grit during normal use of the equipment.

These and other specific objects and advantages accruing from the invention, will be more clearly apparent from the following detailed description.

A clear conception of the various features constituting my present improvement, and of the mode of constructing and of utilizing core grinders embodying the invention, may be had by referring to the drawings accompanying and forming a part of this specification wherein like reference characters designate the same or similar parts in the difierent views.

Fig. '1 is a part sectional side elevation of a' relatively small and portable core grinder built according to the invention, portions of the assemblage having been broken away to more clearly reveal normally concealed parts;

Fig. 2 is a top view of the upper portion of the core grinding unit of Fig. 1;

Fig. 3 is a part sectional side elevation of another core grinder embodying the invention but of larger capacity than that of Fig. 1, this modified machine also having portions broken away in order to reveal normally concealed structure, and showing the core support revolvable from a slow speed motor directly through an endless belt drive;

Fig. 4 is an enlarged central vertical section through the anti-friction bearing for mounting the core support upon the main column of the machine;

Fig. 5 is a transverse horizontal section through the machine of Fig. 1, taken along the line 5-5 and viewed in the direction of the arrows;

Fig. 6 is an enlarged central vertical section through the anti-friction journal and thrust bearing for the grinding wheel supporting shaft; and

Fig. 7 is a transverse horizontal section through a large capacity machine such as shown in Fig. 3, the section being taken generally along the line l'l but above the annular apron associated with the revolvable core support, and the core support being rotatable by an electric motor Figs. 1, 2, 4, 5 and 6, the relatively compact portable core grinder shown therein comprisesin general a lower base 9 mounted on three wheels It, and having a sturdy upright column II firmly attached thereto at thelower extremity of the column; an upper bracket I2 vertically slidably embracing the upper cylindrical portion of the column I I and coacting with a spline I3 to positively prevent rotation of the bracket about the column axis; a grinding wheel I l secured to the lower extremity of a vertical shaft I5 disposed parallel to but remote from the column axis, and having its medial portion journalled for rotation in an anti-friction bearing assemblage I6 carried by the bracket I2, while its upper end is provided with a pulley H; a driving motor I8 mounted upon the bracket I2 near the column II and being drivingly connected to the pulley I6 by a driving belt I9; a

' cap 23 resting upon the upper end of the column II and having an adjusting spindle 2| journalled for rotation therein, the upper end of the spindle being'provided with a hand wheel 22 for effectingrotation thereof while the lower elongated spindle portion 23 is screw threaded for coaction with internal screw threads formed on thebracket I Z; .and a core supporting member 25 having a hub 25 rotatable about the lower part of the upper cylindrical portion of the column II and coacting with an annular shoulder 25 formed on the medial portion of this column through an anti-friction thrust bearing assemblage .21, the member 24 also being provided with an integral supporting plate or portion 23 for supporting sand cores 29 or the like, and which is swingable horizontally beneath the grinding wheel I4.

The main base 9 is preferably constructed in a. durable manner and in the form of a three armed spider so that two of the transporting rollers I8 are disposed some distance away from and on opposite sides of the column II, while the third roller I is located forwardly of and beyond the axis of the shaft I and plate 28, as shown in Fig. 5. The base 9 thus provides a substantial and firm portable support for the entire core grinder; and in order to facilitate transportation of the machine from place to place, the base 9 may also be provided with a draft handle 30 adapted to be held in upright position by means of a hook 3| secured to the column II, when the handle is not in use, as shown in Figs. 1 and 5. The lower end of the the elongated spline I3 and shoulder 26 rigidly and permanently associated therewith. The entire portion of the column II above the fixed shoulder 25 is cylindrical and should be formed for snug but sliding coaction with the bore of the bracket I2, so that this bracketmay be adjusted vertically along the column II but will be prevented from revolving about the column axis by the spline I3. i

longitudinally of 4 The rotary grinding wheel I 4 is detachably secured to and suspended from the lower end of the shaft I5 by means of a nut 32, and may be provided with a suitable guard 33 as indicated in Figs. 1 and 2; and the combined guide and thrust bearing assemblage I B which is carried by the forward portion of the bracket I2 and in which the shaft I5 is journalled, should be so constructed that the shaft I5 cannot tilt or shift its axis. This anti-friction bearing assemblage is illustrated in detail in Fig. 6, and comprises vertically spaced upper and lower ball bearings 34, respectively, of which the upper bearing 34 should be located as near as possible to the pulley I! while the lower bearing 35 is likewise disposed as near as possible to the grinding wheel l4. The upper anti-friction bearing 34 is moreover formed and held in place by a retaining plate so as to assume upward thrust, while the lower anti-friction bearing is formed and likewise held in place so as to as-' sume downward thrust imposed upon the shaft I5, thereby insuring accurate rotation of the' lower grinding face of the wheel [4 in any desired horizontal plane as predetermined by adjustment of the bracket I2 along the column II. The shaft I5 and grinding wheel I4 are rotatable at relatively high speed, by power applied to the pulley I'I from'the motor I8 through one i or more endless V-belts I9, and the tension of these belts may be adjusted by shifting the motor I8 upon its carrying bracket I2 with the aidof tensioning screws 36 shown in Fig. 2.

The adjusting spindle supporting cap 29 rests upon the upper end of the column II and may be firmly secured thereto in any suitable manner,.and the manipulating hand wheel 22 which is secured to the upper extremity of the spindle 7 2I may be provided with a number of grip handles 31 as depicted in Figs. 1 and 2. The threaded spindle portion 23 and the spline I3 should preferably be of considerable length, and since the spindle. H is journalled for free rotation in the fixed cap 20 but is prevented from shifting axially relative to this cap, rotation of the spindle with the aid of the hand wheel 22 will obviously cause the bracket I2 to move up or down dependent upon the direction of said rotation and by virtue of the screw thread coaction of the spindle portion 23 with the internal bracket threads. This adjustment of the bracket I2 along the column. I I permits the grinding wheel I4 to be positioned at any desired height above the core supporting plate 28; and the bracket l2 may be locked or clamped to the column II in various positions of adjustment, by means of a locking screw element 38 coacting with lugs 39 formed on the lower split portion of the main hub of the bracket I2, as clearly shown in Figs. 1 and 2. The wheel driving belt I9 may also be normally concealed by a guard 40 as shown diagrammatically in Figs. 1 and 2, and above which the hand wheel 22 is located, but this guard should be readily removable and is not essential, although it does protect the operator while manipulating the hand wheel.

Although the bracket I2 and grinding wheel I a may be thus adjusted vertically along the main column II, the core supporting assemblage 24 is not shiftable. along this column, but is merely swingable about the column axis as a center. As previously indicated, the core sup porting structure comprises ahub 25 snugly, embracing but swingable about the upper cylindric'al portion of the column II, a core supporting plate 28 formed integralwith the hub 25, and

provided with a lubricant injection fitting H for introducing abundant grease to the space between the bearing zones. The upper end of the hub 25 is closed and concealed by an annular cap 42 secured to the column ll, and the antifriction thrust bearing assemblage 21 consists of an annular ball bearing 43 which is thoroughly concealed and protected by a collar M secured to the bottom of the hub 25. This vertically elongated bearing assemblage 23' while permitting the supporting plate 28 to be swung freely about the column i i in a horizontal plane, positively prevents the core support from moving out of this fixed plane.

The core supporting plate 28 of the relatively small core grinder of Figs. 1 and 5, and which is swingable back and forth about the central column axis, may be circular or of any other desired shape, and is provided with a series of anchoring grooves 55 of well known construction to which the mounting frame 46 of the cores 29 may be firmly secured by means of bolts 41 or the like. The table or plate 28 may also be provided with suitable gripping handles 48 for facilitating swinging thereof, and it is to be noted that the centerline of the plate 28 is swingable about the central axis of the column H on a radius which is approximately equal to the distance from the column axis to the center of the grinding wheel supporting and driving shaft.

The somewhat modified larger capacity core grinders shown in 3 and 7, are quite similar to the smaller machine which has just been described in detail, and function the same as the smaller grinder except that the cores 28 may be automatically swung about the column axis by power applied to the core support. Since the 1 column ii, bracket l2, grinding wheel l4 and the supporting, adjusting and driving elements associated with these various parts are the same in structure and function in both machines, their description will not be repeated. In the large capacity machine, the lower extremity of the main column is rigidly secur d to a relatively heavy and sturdy base plate or base Ml of considerable area, and the core supporting assemblage 59 comprises an annular table or horizontal plate 5i formed integral with a pivot hub 25 and adapted to be constantly rotated about the column. axis by means of a motor driven tapered friction roller '52 coacting with an annular lower surface 53 formed on the table plate iii. The top of the plate 5! may be provided with a series of radial core anchoring recesses or T-grooves .5 formed in radial stiffening ribs 54, so that an annular series of cores 29 may be mounted upon the revolvable table, and the periphery of the plate 5| is provided with an annular apron 55 extending downwardly below the driving roller 52. This driving roller 52 is mounted upon a shaft 56 iournalled in a bracket 5'! secured to the base 49, and the inner end of the shaft 56 carries a pulley 5B which may either be driven directly from a slow speed motor 59 through speed reducing endless belts fill, as shown in Fig. 3; or from a high s eed motor 5| through speed reduction gearing 62 and belts 68, as illustrated in Fig. 7. In either case, the revolution of the core supporting plate 5! by power, should be at relatively slow speed in order to grind a perfectly smooth surface in one pass of the relatively soft sand core 29 beneath the abrasive wheel [4.

Since the operation and functioning of the two machines is substantially the same, it will suffice to describe the mode of use of only one of the core grinders, so that the mode of utilizing the smaller core grinder will be specifically described. During normal use of the core grinding machine disclosed in Figs. 1, 2 and 5, the core 29 which is to be dressed should first be firmly applied to its frame 46 and this frame should be firmly attached to the coresupporting plate 23 with the aid of bolts 45. The plate 28 with the core 23 attached thereto will then be freely swingable about thecentral vertical axis of the column H in an obvious manner. The grinding wheel 14 should then be vertically adjusted by releasing the clamping screw 38 and manipulating the hand wheel 32 so that the lower plane face of the wheel It will be at the proper dis tance from the upper plane face of the plate 28, in order to properly dress the upper surface of the core 29 when the core is swung into the zone of action of the wheel, and the clamping screw 38 should thereafter be manipulated so as to lock the bracket l2 in the properly adjusted position. The motor 58 may then be placed in operation to cause the grinding wheel l4 to revolve rapidly about the central axis of its supporting and driving shaft 5 5, after which the core supporting plate 23 may be swung about the central axis of the column ii so as to. cause the core 29 to pass beneath the revolving grinding wheel.

\ Because ofthe fact that the sand cores 29 are relatively soft. as compared to the grinding wheel it, it is onlynecessary to cause the wheel to travel once over the core, in order to insure the production of smooth core faces, but the wheel should be moved slowly in order to avoid breakage of the core edges adjoining the ground surfaces. In this manner, the successive cores may be rapidly and effectivelydressed and subsequently united along the smooth and plane dressed surfaces, with the aid of paste or other adhesive in a well known manner, and by properly manipulating the supporting plate 28, chipping and. breakage at the edges of the dressed surfaces may be entirely eliminated, thus avoiding necessity of subsequent patching. i i

As previously indicated, the normal operation of the modified core grinding machine shown in Figs. 3 and 7 is the same as that of the machine shown in Figs. 1, 2 and 5. but with the larger machine a continuous annular series of cores 29 may be dressed automatically by utilizing a motor for driving the annular core supporting table plate 5|. A series of similar cores 29' may obviously be secured to the plate 5!, and this plate may subsequently be revolved about the central axis of the column I I by applying power to the friction roller 52, and as each of the successive cores 2!! is passed beneath the revolving wheel M which has previously been vertically adjusted to the proper height. the upper surfaces of the successive cores 29 will be neatly dressed and provided with smooth and perfectly plane surfaces. Obviously the capacity of the larger machine may be made considerably greater than that of the smaller portable machine, but in both cases the result will be effective dressing of the cores so that they can. be subsequently united along the dressed surfaces without difiiculty.

' From the foregoing detailed description it will be apparent that my present invention provides an improved core grinder which besides being extremely simple, compact and durable in construction, is also highly eificient in use. The elongated anti-friction bearings provided for the grinding wheel driving shaft l and for the core supporting table or plate, will prevent misalinement of the wheel and table relative to each other and will thus insure the provision of perfectly smooth and plane surfaces. The adjustment afforded for the bracket l2 and grinding wheel I obviously provides extreme flexibility in utilizing the machine to dress cores of different sizes and shapes, and the smaller machine while being of lesser capacity than the larger machine, is extremely compact and portable so that it can readily be moved into various localities. In both machines the grinding wheel l4 while being vertically adjustable, is effectively held against possible displacement relative to the central axis of the main column II, and in both machines the core supporting table or plate is likewise effectively prevented from becoming misalined with respect to the column axis while being freely swingable about this axis. While the anti-friction bearings 34, 35, 43 have been shown as ball bearings, it is to be understood that roller. or other types of anti-friction bearings may be employed in place of these ball bearings, in a manner well known in the art. The improved machine may obviously be built and operated at moderate cost considering its effectiveness, and the inven-- tion has proven highly successful and advantageous in actual commercial use.

It should be understood that it is not desired to limit this invention to the exact details of construction or to the precise mode of use, herein shown and described, for various modifications within the scope of'the'appended claims may occur to persons skilled in the art.

I claim:

1. A core grinder comprising, a base, an upright column mounted upon said base and having an annular outwardly projecting shoulder and a shoulder, a core support swingable about said cylindrical column portion and coacting with the upper surface of said shoulder to prevent movement of the support along the column, a bracket having a hub slidably cooperable with said cylindrical column portion and being provided with an upright bearing remote from said hub and directly above the core carrying portion of said support, an abrasive wheel journalled for rotation cylindrical portion projecting upwardly from said in said bearing and having a grinding face revolvable beneath said bearing parallel to the plane of swinging of said core support, a motor mounteddirectly upon said bracket hub, a rotary motion transmitting drive connecting said motor and said wheel above said bearing and said bracket, a spline interposed between said hub and said cylindrical column portion for positively preventing swinging of said bracket about said column, a cap fixedly secured to the upper extremity of said column, a manually operable screw threaded adjusting spindle journalled in said cap and having its lower end cooperable with said bracket to move the same along said column while its upper actuating end is disposed above said drive, and means for locking said bracket to said column to prevent displacement of the bracket by said spindle.

2. A core grinder comprising, a base, an upright column mounted upon said base and having an annular outwardly projecting shoulder and a cylindrical portion projecting upwardly from said shoulder, a core support swingable about said cylindrical column portion and coasting with the upper surface of said shoulder to prevent movement of the support along the column, a motor also mounted upon said base beneath said support, a friction drive interposed between said motor and said support for imparting swinging motion to the latter, a bracketv having a hub slidably coopera'ble with said cylindrical column portion and being provided with an upright bearing remote from said hub and directly above the core carrying portion of said support, an abrasive wheel journalled for rotation in said bearing and having a grinding face revolvable beneath said bearing parallel to the plane of swinging of said core support, another motor mounted directly upon said bracket hub, a rotary motion transmitting drive connecting said last mentioned motor and said wheel above said bearing and said bracket, a spline interposed between said hub and said cylindrical column portion for positively preventing swinging of said bracket about said column,

a cap fixedly secured to the upper extremity of actuating end is disposed above said drive, and

means for locking said bracket to said column to prevent displacement of the bracket by said spindle.

JOHN A. ROSMAIT.

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