US3003493A

US3003493A - Core drill adapter

Info

Publication number: US3003493A
Application number: US813765A
Authority: US
Inventors: Harold C Miller
Original assignee: Super Cut Inc
Current assignee: Super Cut Inc
Priority date: 1959-05-18
Filing date: 1959-05-18
Publication date: 1961-10-10
Anticipated expiration: 1978-10-10
Also published as: GB946090A

Description

1961 H. c. MILLER 3,003,493

CORE DRILL ADAPTER Filed May 18, 1959 FIGI F|G.2' J

I0 I K) 40 so 1 so I 44 73 44 l 8O 73 l I 52 62 l i 3 5o 42 50 H, 48 l 26 l g l I I 46 so i l 82 INVENTOR: HAROLD C. MILLER IIIPIIIIIII is M ATT'Y,

3,003,493 CORE DRILL ADAPTER Harold C. Miller, Chicago, Ill, assignor to Super-Cut, Inc., Chicago, Ill., a corporation of Illinois Filed May 18, 1959, Ser. No. 813,765 1 Claim. ((31. i25-=2tl) The present invention relates to drilling apparatus of the type commonly employed for producing holes in a body of vitreous or ceramic material such as tile, glass, porcelain, cement, marble or the like and which employes as the drilling element proper a tube type drill employing a diamond impregnated matrix or other abrasive element at its forward rim, a suitable coolant or flushing liquid being supplied to the interior of the drill during drilling operations.

Various methods are currently employed for introducing a coolant and flushing liquid to the interior of tube type drill elements including the use of specially designed drill chucks, drill chucks having hollow spindles, and stationary adapters or jackets which provide a hollow annulus around the rotating drill and which are sealed to the outer cylindrical surface of the drill so that liquid 'under pressure introduced into the annulus may pass through an opening or openings formed in the drill and in register with the annulus and from thence flow forwardly within the drill to the rotating abrasive segment. It is to this latter class of fluid feeding devices that the present invention pertains.

Jacket type adapters of the type briefly outlined above are possessed of numerous limitations, principal among which are, first, the inability eilectively to seal the stationary jacket to the body of the rotating drill, and secondly, the tendency for the drill body to become misaligned with the axis of the drill press spindle or other rotating driving element employed for supporting and rtating the drill. Heretofore, in order to seal such adapters, it has been commonly the practice to provide a stutling or packing gland at each end of the adapter and to employ a graphited or other loose packing material within the packing glands. While such a method of sealing the ends of the adapter may be eiiective for sealing purposes for a time, when the tube drill becomes worn in the vicinity of the packing material, leakage will occur, thus necessitating frequent repacking of the gland.

Furthermore, packed glands of this nature, when employed in connection with a tube drill, are messy both in handling and in service. The graphite, lubricant, or other material employed in connection with the packing material frequently seeps from the gland during use of the drill so that, upon handling of the drill, especially during packing-chan ing operations, the graphite material will contaminate the hands of the operator.

Jacket type adapters of the packed gland type briefly outlined above are not conducive toward easy withdrawl of the core drill shank endwise from the adapter. This is due to the fact that the packing material at the ends of the adapter, in its free state, presents a bore which is smaller in diameter than the external diameter of the core drill shank. Gnce the drill shank is withdrawn from the adapter, the packing material within the adapter at the ends thereof will expand and render it dlfilC'Jli to re-introduce the shank into the adapter or to introduce a fresh drill shank thereinto. Because of this, manufacturers of core drills design the same so that the shank portions thereof may remain more or less permanently in the adapter while only the core drill tip is removable from the assembly. To accomplish this, it is customary to provide a threaded connection between the core drill shank and the core drill tip, the threaded connection, of course, making provision for passage of the 3,93,493 Patented Get. it), 1951 coolant fluid from the shank to the tool proper. Because of the relatively rough usage to which such core drills are put and because of the high lateral stresses to which the drill is subjected, these threaded connections are relatively massive, considering the small diameter of the drill, and they involve brass or other companion fittings which make threaded connection with each other as well as with the shank and drill proper to which they are attached. Alternatively, such fittings are welded or brazed on the ends of the shank and drill proper. The shank may thus permanently be received within the chuck of a drill press and have the jacket type adapter permanently associated therewith so that, when it is necessary to change the core drill tool prop-er, it is merely necessary to uncouple the fittings and apply a fresh core drill proper with its attached fitting to the shank fitting.

Core drills of this type are possessed of numerous limitations, principal among which is the fact that there are at least two and frequently more than two places where shank and tool misalignment may occur. Wherever there is a threaded connection, there is a region of possible misalignment. Additionally, wherever there is such a threaded connection there is also a possibility of fluid leakage.

The present invention is designed to overcome the above noted limitations that are attendant upon the construction and use of conventional core drills and the adapters associated therewith and, accordingly, it is one of the principal objects of the invention to provide a core drill and jacket-type adapter therefor wherein the use of packing material within the adapter is eliminated and wherein, in its stead, there is employed a novel form of balanced dual end-face seal embodying sealing washers which are effectively statically sealed to the core drill shank so as to be rotatable in unison therewith, and which are dynamically sealed to the adapter casing by a running fit. According to the present invention, the material from which the sealing washers are formed, although being resilient, possesses an appreciable degree of resistance to compressional forces so that it may make relatively tight sealing engagement with the drill shank which it surrounds while at the same time permitting the drill shank, when necessary, to be manually slid from its telescopic relationship with the washers and thus Withdrawn from the adapter. Due to the fact that when such compressional forces are relieved the material of the washers is slow to resume its original shape, the openings in the Washers will not close to such a degree as to preclude the easy insertion of a fresh core drill shank into the adapter.

Another and important object of the invention is to provide a core drill and jacket-type adapter therefor wherein the core drill is of one-piece construction and is thus devoid of threaded connections or sectional joints, such a unitary core drill body being made possible due to the facility with which the drill shank may be withdrawn from and inserted into the assembled adapter for purposes of drill inspection or drill replacement.

Other objects and advantages of the invention, not at this time enumerated, will become more readily apparent as the following description ensues.

In the accompanying single sheet of drawing forming a part of this specification, a preferred embodiment of the invention has been shown.

In this drawing:

FIG. 1 is a side elevational view of a core drill and jacket type adapter therefor showing the same in operative drilling position, the drill and adapter assembly being constructed in accordance with the principles of the present invention;

FIG. 2 is a side elevational view similar to FIG. 1 with the composite adapter and a portion of the core drill being shown in central vertical elevation to more clearly reveal the nature of the invention;

FIG. 3 is a sectional view taken substantially along the line 3-3 of FIG. 2;

FIG. 4 is an exploded perspective view of the core drill and adapter assembly; and

FIG. 5 is an enlarged fragmentary sectional view taken substantially through one end region of the core drill and adapter assembly to more clearly reveal the nature of a seal assembly employed in connection with the invention.

Referring now to the drawing in detail, a diamondimpregnated tube type drill, commonly referred to as a core drill, has been designated in its entirety at 10. The drill is comprised of a relatively thin wall metal tube having a central bore 14 extending therethrough. The lower end of the tube carries a diamond-impregnated cutting portion or segment 16 while the upper end of the tube in the medial regions thereof is thickened as at 20, thus providing an enlarged outside cylindrical surface 22. A relatively narrow annular groove 23 is formed in the surface 22 adjacent to the bottom end thereof, this groove being designed for reception therein of a split retaining element 24, the function of which will 'be made clear presently. A transverse bore 2-6 is formed centrally through the tube and, in effect, provides a pair of diametrically disposed aligned openings in the thickened wall portion of the tube so that coolant fluid may be introduced into the interior of the tube through these openings for downward flow in the tube to the work undergoing drilling by the tube for cooling and flushing purposes in a manner that is common to core drills of this general type. It is to be noted at this point that, except for the threaded plug 18 and the diamond-impregnated matrix 16, the drill is of one-piece steel construction by virtue of which certain advantages that will be outlined presently may be attained. When the core drill is in actual operation, as for example in drilling holes in a sheet of glass such as has been illustrated at in FIG. 1, the upper end of the core drill is held in a chuck, such as the chuck 32 shown in dotted lines and which may be associated with a conventional drill press (not shown). The work 39 may be mounted on a resilient pad 33 which, in turn, is supported on a suitable bed plate 34.

Diamond impregnated core drills of the general character described herein rely for their cutting action on the superior abrasive quality of the diamond particles which are embedded in the metal of the cutting segment 16. The coolant which is supplied to the interior of the drill operates to flush away the cuttings and it may also, if desired, carry a lubricant. To enhance proper lubricating and flushing action, drills of this general character are sometimes slotted as at 36.

As previously stated, in order to supply coolant fluid to the interior of the hollow drill 14 means are provided for establishing an annular reservoir or fluid pressure chamber around the drill in the vicinity of the enlarged cylindrical surface 22. Such a reservoir exist, according to the present invention by virtue of a novel form of adapter which has been designated in its entirety at 40 and which is comprised of a generally cylindrical casing 42 having novel and substantially sealing

assemblies

44 and 46 disposed therein at the opposite ends of the casing to seal the upper and lower ends of the casing respectively to the cylindrical surface of the core drill. An opening 48 formed in one side of the cylindrical casing communicates with a fitting in the form of a shut-01f valve or cock 50 by means of which the supply of coolant fluid to the interior of the reservoir established by the casing 42 may be shut off at will.

The upper and lower open ends of the adapter casing 42 are closed by the two sealing assemblies. These assemblies are substantially identical and are of the rotary mechanical seal type having a seat member which is fixed relative to the casing 42 and sealed with respect thereto, and a sealing washer which is sealed relative to and rotates with the core drill, the seal seat and washer presenting to each other substantially flat running seal surfaces across the faces of which no fluid may pass. Since the two seal assemblies 44 and 46 are substantially identical in construction, a description of one of these assemblies will suflice for the other. Each seal assembly involves in its general organization a combined seat and closure member in the form of an annular end cap or ring 66 having a flange portion 62, the outer cylindrical surface of which is flush with the cylindrical surface of the casing wall 42, and a reduced plug portion 63 which fits snugly within the bore of the cylindrical casing wall 42. A circular recess 65 is provided on the inside face of the plug portion 63 and serves a function that will be made clear presently. The forward face of the plug portion 64 between the outer rim thereof and the rim of the circular recess 65 presents a flat annular sealing surface 66 which is preferably lapped to a high degree of flatness and which is designed for running sealing engagement with a similarly flat surface 68 provided on a sealing ring or washer 79 which surrounds the core drill and which is sealingly fitted thereto in a manner and for a purpose that will be described presently. The combined closure and seat member 60 is formed with a central opening 72 therethrough and through which the core drill passes and within which opening the drill is freely rotatable. The two seat members 60 associated with the upper and lower sealing assemblies 44 may be soldered as at 73 to the upper and lower rims respectively of the casing wall 42.

Each sealing washer 70 is in the form of an annular ring of plastic material which embraces the enlarged cylindrical portion 22 of the core drill 10 with a tight fit so that there will be no leakage of fluid along the core drill through the ring, the degree of inward pressure exerted upon the core drill through the ring, the degree of inward pressure exerted upon the core drill by the sealing ring being such as to permit sliding of the core drill axially through the ring for core drill removal and replacement purposes. The scaling washer 70 has an overall diameter which is slightly less than the internal diameter of the bore of the casing wall 42 at the longitudinal region of the casing where the wall of the casing and the outer periphery of the ring oppose each other so that there is a slight clearance as at 74 between the washer and the casing wall. The washer 70 is formed with a reduced portion 75 which extends into the circular recess 66 but which is of less longitudinal extent than the depth of the recess so that a clearance exists as at 76 between the bottom face of the recess and the extreme forward annular face of the washer. The previously mentioned fiat annular sealing surface 68 provided on the sealing washer 7G is of slightly less width than the width of the cooperating flat sealing surface 66 provided on the seat member 60 and the washer 70 is adapted to be yieldingly urged forwardly against its respective seat member by means of a compression spring 80 which surrounds the core drill within the casing wall 42 and the flat ends of which bear against the opposed inside annular end faces 82 of the washer 70. As will become clear presently, the fluid pressure maintained within the chamber or annulus existing between the core drill and adapter wall during operation of the drill is suflicient to maintain the cooperating

sealing surfaces

66 and 68 in running sealing engagement. However, to ensure intial engagement between the washers 70 and seat members 60 the spring member 80 is provided. This spring also serves to maintain the washers 70 in position within the assembly during withdrawal of the core drill from the adapter or application of a new drill to the same.

The sealing Washers 70 are preferably made of polytetrafiuoroethylene polymer which is described in Industrial and Engineering Chemistry, volume 38, page 70,

- under the 'trade name Teflon.

., dated September 1946, and is currently being manufactured and sold'by E. I; du Pont de Nemours & Co.

This material is characterized' byits chemical" inertness, the resistance to attack by corrosive reagents, .and dissolution by solvents. Molded Teflon is a tough solid, waxy to the feel, white in coloryand high resistant to abrasion. Although Teflon has a relatively low tensile strength at high temperaetures in excess of 600 F., at lower temperatures its tensile. strength is greatly improved. Because of these qualities, Teflon is an ideal material for use in constructing the washers 70 of the present invention. At the relatively low temperatures normally encountered in core drill use, the degree of cold flow of which this material is capable is practically negligible and, consequently, the degree of pressure exerted by the inside cylindrical face 84 of the ring 70 on the outside cylindrical surface of the enlarged portion 22 of the core drill will at all times be maintained so that an adequate seal is effected between these two surfaces despite any centrifugal forces which may be applied to the material due to the relatively high speed of the core drill in use. At such temperatures, the material of the sealing washer 70 is extremely tough and has satisfactory tensile strength and admirable friction and abrasive qualities rendering the same ideal for use in the present installation.

In the operation of the apparatus, coolant fed to the interior of the adapter casing 42 flows through the annulus 52 and passes radially inwardly through the openings 26 and downwardly through the bore 14 provided in the core drill 10. Upon application of the diamond impregnated segment 16 to the work 30, an appreciable degree of internal fluid pressure is built up within the annulus 50 and this pressure is exerted upon the flat annular inner faces 82 of the sealing rings or washers 70 tending to force the same apart and against their respective seat members 60. It will be understood that after the seal core drill and adapter have initially been assembled and the unit is ready for operation, the spring 80 will supply the pressure required to hold the sealing washers 70 against the seat members 60 in fluid tight relationship whether there be any fluid pressure in the annulus or not, and whether the core drill is stationary or rotating. The spring pressure involved at this time is the minimum pressure to which the seal assemblies will at any time be subjected. When fluid is admitted to the annulus 52, all areas of the sealing ring which are exposed to the fluid will thus be subjected to the unit fluid pressure developed within the fluid. The entire areas of the annular surfaces 82 will be subjected to such pressure and will function as pistons tending to force the sealing rings for washers 70 outwardly away from each other. While the core drill is in actual use, the split retaining element 24 serves to bear the weight of the entire adapter and the hose connection leading thereto.

The medial region of the cylindrical side wall 42 of the adapter casing is preferably thickened as at 9!) so that the internal diameter of the casing between the two sealing rings or washers 70 is less than the over-all diameter of each washer. I he two washers 70 are thus confined at the ends of the casing and even if the spring 80 were not employed, these two sealing rings would be thus maintained separated on opposite sides of the openings 26. As previously stated, however, the use of the spring 80 is preferred since it causes the seal ing rings initially to seat against the seat members 60 and prevents an initial out-rush of fluid when the latter is first admitted to the annulus 52.

When it is desired to have access to the interior of the adapter casing for seal inspection or replacement purposes, it is not necessary that the assembly be removed from the drill press chuck 32. It is merely necessary to remove the split ring 24 from the groove 23 and melt the soldered connections -73: so ,that the various parts of the assembly may easily be separated.

When it is necessary to replace a core drill 10, the entire drill and adapter assembly may be removed from the chuck 32 and the core drill may then be manually slid from the adapter axially and the replacement core drill installed by simply sliding it into the adapter in a reverse direction. Because of the fact that the regions of the core drill on opposite sides of the enlargement are reduced, the two sealing washers are maintained out of frictional contact with these reduced regions during removal of the drill from the adapter so that these sealing washers will not become contaminated with loose abrasive particles which may cling to the drill.

While one specific and preferred form of the improved core drill and adapter asesmbly by means of which the principles of the present invention may be carried out has been illustrated and described herein, it will be understood that this form does not by any means indicate the only form contemplated. The form illustrated herein is merely one which has been developed for commercial application. The invention, therefore, is not to be limited to the exact construction illustrated and described herein as various changes in the details of construction may be resorted to without departing from the spirit of the invention as defined in the appended claim.

Having thus described the invention, what 1 claim and desire to secure by Letters Patent is:

In an apparatus for drilling holes in, and producing cores from, glass, ceramic and similar articles, in combination, a one-piece tube type core drill having an opening in the side wall thereof through which a coolant fluid is adapted to pass radially inwardly of the drill for flow longitudinally along the tube to the cutting edge of the latter, an adapter for said drill comprising an open-ended tubular cylindrical casing of larger internal diameter than the over-all external diameter of the drill, said drill being adapted to be removably projected axially through said casing and, in combination therewith, defining an annular fluid reservoir surrounding the drill and in register with said opening, there being an opening, in the wall of said casing defining an inlet port for fluid under pressure, means for supplying fluid under prmsure to said port, a mechanical seal for substantially preventing the flow of fluid from the reservoir at each end of said casing, each seal comprising a sealing washer formed of resilient material surrounding said drill, said washer being formed with an axial bore therethrough through which the drill extends with the bore closely and yieldingly hugging the shaft in sealing relationship coextensively around the bore whereby the washer is constrained to rotate with the shaft, the outer side of said sealing washer being formed with a peripheral recess defining a flat outwardly facing annular sealing surface and a forwardly projecting central reduced portion, a combined closure and seat member for said casing and sealing washer respectively, telescopically and sealingly received within the adjacent end of the casing and presenting an inwardly facing sealing surface designed for running sealing engagement with said outwardly facing sealing surface, the inner face of said closure and seat member being formed with a circular recess therein of a depth greater than the longitudinal extent of said forwardly projecting reduced portion and into which recess said reduced portion projects, the inside Wall of said casing being formed with a continuous outwardly facing annular shoulder at each end region of the casing spaced inwardly and in opposition to and engageable with the inner face of the adjacent sealing washer for preventing inward shifting of said washer longitudinally within the casing, and a helical compression spring surrounding said core drill within the adapter casing and hearing at the opposite ends thereof against the inner faces of the sealing washers respectively, the radial Width of the running seal afforded by said sealing surfaces being 8,003,493 7 8 less than the radial width of the inner side of said sealing 2,297,477 Huhn Sept. 29, 1942 washer. 7 2,578,523 Llewellyn Dec. 11, 1951 2,777,702 Rodal Ian. 15, 1957 References Clted 1n the file of thrs patent UNITED STATES PATENTS 5 FOREIGN PATENTS 537 495 Germany Nov. 4, 1931 91 ,074 I A 6, 19 2 Great Brltam Aug. 2 2:133:524 Baal-s Oct 1 193 686,778 Great Britain l 1953 2 270 927 Browne Ia 27 1942 10 756,240 Gl'cat Britain P 1956