US2893271A - Sensitive drilling machine - Google Patents

Description

July 7, 1959 M. D. ELLEDGE SENSITIVE DRILLING MACi'iINE 2 Sheets-Sheet 1 Filed Feb. 3, 1958 INVENTOR. l-eofl 'ZZed 6'.

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July 7, 1959 Filed Feb. 3, 1958 M. D. ELLEDGE SENSITIVE DRILLING MACHINE 2 Sheets-Sheet 2 United States I 2,893,271 SENSITIVE :DRILLING MACHINE Dt Elledge, Monrovia, f

Application February 3, 1958, Serial No. 713,015" Y 8 Claims. 01.1 7-32 This invention relates to sensitive drilling machines and particularly to a machine forv performing high speed drilling operations in the formation of very small'diameter holes in hard substances. The drilling of the holes in artificial teeth formed of hard plastic or of porcelain material for reception of the securing rivets is an e'xample of such work. i v i I drilling machine for-forming small diameter holes in hard substances and in which the machine is characterized by being quickly adjustable and further by extreme sensitivity to the progress of'a drilling tool through-the work piece being drilled. Y e l Another object of the invention is to provide a sensitive drilling machine in which the drilling-tool is maintained vertically stationary while the work holding means is raised and lowered into and out of engagement with the drilling tools by means which is substantially friction free and counterbalanced wherefore, the effort expended in holding the work against the drilling tool is -substantially limited to producing the required movement with the resultant increase in the degree of sensitiveness com municated to the hand' of the operator. y i

With the foregoing objects in view, together with such additional objects and advantages as may'subsequently appeanthe invention resides in the parts, and in the construction, combination and arrangement of partsdescribed, by way of example, in the following specification of certain presently preferred embodiments of the invention; reference being'had to the accompanying draw ings which form a part of said specification and in which drawings:

Fig. l is a frontelevational view of a machine 'em- Fig. 4 is a fragmentary top plan view taken as looking at the work supporting portion of the machine 'fro'm'a" position represented by'the line 4' 4 in-Fig. 2,

Fig. 5;.is afragmentary top plan's'ectional view t'akei1- on the line 55 of Fig. 2,

Fig. 6 is an enlarged medial sectional Fig. 7. is. a fragmentary -sectional view taken on t-he staggered line 7-7 ofFig. 6,

Fig. 8 is a fragmentary sectional top plan taken? on the line 8 8 ofFig. 6, v e 4 I a I Fig. 9 is a fragmentary-top planview taken on the line 99 of Fig. 7, i w

Fig. 10isa reduced sca le 'side elevational view, of a second embodiment-of the invention and Fig. 11 is a fragmentary front elevation offthedevijce.

shown in Fig. 10.

The base 1 of the machine is preferably formed as view of the worksupporting and manipulating meansemployedeinthe.first embodiment of the .invention the section being taken" on the line 66 of Fig. 2, 4

2,893,271 tefee su 7 95 a casting having a top surface 2 and a depending skirt portion 3 forming the side wall of the base. At one end ried by thebas'e-and thence extends upwardly through i: by means presently to be described.

the standard 5 and then to the motor 9. The present inachineis, different than many drilling machines in that the drill remains vertically stationary and the work to be drilled is moved upwardly into engagement with the drill The machine is'shown equipped for use for dental work such as vdrilling of artificial teeth for the fastening thereof into bridgework and the like. vTo this end the machine p is provided with a shallow cup element 13having a de The primary object of the invention'is to provide a pending stud 14 on which is mounted a spring washer 15 and a' hand nut 16, the depression 17 in the upper surface of the cup serving to retain a wax or similar. substance in which the tooth to be drilled is secured.

The spring washer, hand nut jand;stud afford means for detachably securing the cup 13- to the upper surface of axrearwardly extending run 1 8 of a work supporting member li -disposed, in the axial line of the motor shaft, saidmember having 21* depending run. 20 and a;

forwardly extending;run 21 fixed to the upper end of a rod 22 mounted for vertical reciprocation in the axial line of the'm otor by means presently to be descr bed. Theupper. run 18 of -th e member-19is provided withaslot 23 extending rearwardly, said slot at the frontedge ofthe saidfupper run. 18 and for a short distance therefrom being only sufliciently widestore ceive the stud 14. s tws i said la w de s. l ra ha the .dmay be moved through a considerablerange -of posi tions and clamped by thenut and washer thus permitting the positioning of the cupl3 in a desired position beneath the drillingtool carried bythechuckltl. m

seine i 9 11 and .i s-as ia etnu and s e y. e mi t t animate h din m ans: f ih ll Ql k; 8 bf h mt 0? e t 93 dri led in. t e up, th e. rab ya l al ty 9 1 2s..; 2r hd with a h, drilling machine. ,1 i l The rod 22is mountedifo; in-ail axialrbore 24 te n svq ti a i nd aa m b 25 disposed below and i hsex al; 1 O th t .-i, -w

3 5 member 5 i memes st r cip sa iqn 'l j li. pe us n 6 ada ma ls1QW$= hq i sflc r e respectively, in the upper end of a cylindrical housing 28 andina sleeve 29 -fixedto and. depending from a cover the base. The member 25 at onev side thereof is cut-away to provide aflatl side 34 and a longitudinal slot 35 extends between thebore 24 and the said flat side 34. The lower end ofthe rod 22 is provided with a transverse threaded bore1 3 6 which is engaged by a threaded stud 37 having ashoulder portion 38 engaging the flat side 34 to clamp the rod 22in any desired position along the slot 35, the e shank 39 of said stud extending laterally through a,slot'.- '40 in the wallet the housing 28 and externally of the r housing carrying a knob portion 41 by which it may-bee tightened andreleased incident to the vertical adjustment of the rod 22 along .thebore24u y amet f al .op q t a lp flfl'th reihl l c i the housing 28 is provided with opposed laterally extends 3 ing bosses 42 and 43 which are provided with bushings 44 and 45 affording bearing support for a shaft 46, said shaft adjacent to the member 25 carrying an eccentric 47 on which the inner race of a ball bearing 48 is mounted. The member 25 'has 'a' transverse slot 49 formed therein in which the outerfrace of the ball' hearing 48 is received. The shaft 46 extends beyond the hearing' boss 42 and carries a handknob 50 by which it may be turned with resultant vertical movement of the member 25 being imparted by the eccentric 47. The lower end of the member 25 below the slot 49 is provided with a bore 51 in which is disposed a compression spring 52 effective to bear against the outer race of the ball bearing 48 to maintain anyplay betweenthe .ball bearing and the slot 49 taken up with the upper "end of the'slot 49 at all times bearing againstjthe outer race of the ball bearing 48. The outer end of the boss 42 terminates in an annular flange portion 53 which is the same diameter as the shank portion of the knob'50,'jsaid shank portion 54 carrying a set of graduations 55 which register with an indicia line 56 on the flange 53. The graduations may be for any desired amounts of vertical movement. In the illustrated embodiment of the invention, the graduations indicate millimeters of vertical movement'of the member 25 and consequently of the work: holding cup mounted thereon, it being understood that due to the movement of the eccentric the graduations will be spaced at varying distances apart sothatthey will indicate uniform increments of vertical'movement.

The lower end of the member 25 is reduced in diameter to a short substantially square portion 57 which is convenientlyinitially formed as a threaded portion, thereafter having the sides cut away to form a por'tion'of square cross section of such size that the threads remain on the corners. A bowed leaf spring 58 extends diametrically across the housing 24 and has its opposite ends attached to the housing side wallsby screws 59 and nut 60, said spring at its mid-length having a square opening 61 through which the said square portion '57 of the member 25 extends. A nut 62 and washer 63 engaging the threads on the corners of the squareportion 57 serve to clamp it against the shoulder 64 formed by the juncture of the square portion 57 and the larger circular portion of the member 25. Below the square portion 57 the member 25 extends in a small diameter bearing portion 65 which slidabl y engages the bushing 27. The spring 58 is initially biased totend to move the member 25 and the work supporting means carried thereby downwardly: to the extentpe'rmitted by the rotation ofthe shaft 46 i to a point bringing the high point of the eccentric extending directly downwardly. The hand knob 50' on the shaft 46 is normally maintained adjusted so that the zero line on the graduations on the hand knob is in registry with the indicia mark on the flange 53, the set screw 50' which'secures the hand knob 50 to the shaft 46 being loosened and-then retightened to achieve this setting. r

In a representative use of the device a cup 13 having the work to be drilled is mounted on the work holding means and secured by the nut 16. A drill of the proper size is placed in the chuck and the motor bracket is adjusted downwardly if necessary on the standard 5 until the drill is close to the work. The cup is then adjusted laterally until the point at which the drill is to enter the work is directly in line with the drill, the distance between the drill and the surface of the work being as little using whatever pressure, either constant or intermittent, and using whatever lubricant, if any, is necessary.

The illustrated embodiment of the invention is arranged to form holes not exceeding 5 millimeters in depth but this is merely a function of the throw of the eccentric 47, it being evident that greater or lesser throws might be employed for individual uses. When the hole is completed, the work is either removed if it is a completion of a piece being drilled or the work or the drill head may be shifted laterally for the formation of another drilled hole as the nature of the work may require. It is particularly to be noted that due to the fact that the ball bearing is employed, and that the movement of the work supporting meansin the drilling operation is opposed to the action of the spring 58, the feeling of the movement of the drill through the work can be accurately detected by the hand knob 50.

Referring to the second embodiment of the invention shown in Fig. 10, the base standard and motor are generally similar to that in the first described form, and therefore the same numbers have been added with the addition of the exponent a. The work supporting means comprises a bracket 66 having a slot formed therein similar to the slot 23 in the first form of the invention for securing the work supporting means comprising a cup, stud, washer and not which may be identical with that shown in the first form of the invention. The bracket terminates ,in a supporting portion 67 having parallel horizontal upper. and lo'werfaces to which the ends of leaf springs 68, 68 are attached by rivets, or the like. The opposite ends of theseleaf springs are similarly attached to a corresponding lug 69 carried by a clamp member 70 surrounding the standard 5a and secured in vertical adjusted positiontthereon by a screw 71. The under face of the clamp 70 carries a downwardly and forwardly extending bracket member 72 secured thereto by screws 73, said bracket terminating beneath the end of thevhand nut 16a and affording bearing support for a shaft 74 which at one end is provided with an eccentric 75 engaging the under surface of the nut 16a and at its other end carries a hand wheel or knob 76. As in the first embodiment of the invention, the springs 68, 68 normally apply a substantial downward. bias on the bracket 66 and thereby maintain the lower face of the nut 16a in constant contact with the surface of the eccentric 75. The hand wheel carries an ,indicia bearing surface 77 marked off in graduations which register with a reference mark on an arm mounted on the journal portion of the bracket 72 adjacent the end at which the hand wheel 76 is located, the said graduations being spaced to indicate uniform increments of upward movement of the work support by the rotation of the eccentric 75.

This embodiment of the invention is equally satisfactory for most of the operations for which the first described form may be used although it is not quite as accurate in that the spring 68, 68 while giving the bracket 66 a generally directly upward movement similar to a parallel rule, type of movement, do impart a slight amount of rock to this bracket and consequently to the work. The difference is a matter of perhaps one or twothousandths ofan inch and unless that difference is critical this form of the invention is just as satisfactory as the first form-of the invention and in fact is somewhat cheaper to produce. I

Thus there has been provided a sensitive drilling machine for drilling holes of very small size and of limited depth in very hard substances and in which the objectives of the invention are realized in practice.

The foregoing description has disclosed, by way of example, certain presently preferred embodiments of the invention but it will be understood that the invention is not to be deemed to be limited to the forms thus disclosed and that the invention embraces all such changes and modifications in the parts, and in the construction,

combination and arrangement of parts as shall come within the purview of the appended claims.

I claim:

1. In a drilling machine, a base, a standard rising from said base, a vertical axis shaft and driving means therefor journaled on said standard at one side thereof, said shaft having a drill holding chuck at the lower end thereof, a work manipulating means disposed beneath said drill and including a member mounted for vertical movement in a line which is substantially equal in distance from said standard as is the axial line of said shaft, a work holding means detachably mounted on said work manipulating means, spring means constantly imposing a bias on said work manipulating means tending to move said work manipulating means downwardly, and manually operable means for moving said member upwardly comprising a horizontal shaft having a hand Wheel at one end thereof and eccentric means at the other end thereof engagable with said work manipulating means and effective upon rotation of said shaft by said hand wheel through a half revolution to move said work manipulating means upwardly in opposition to the bias imposed by said spring means towards a drill carried by said chuck.

2. A drilling machine as claimed in claim 1 in which said work manipulating means and said horizontal shaft are mounted on said base.

3. A drilling machine as claimed in claim 1 in which said work manipulating means and said horizontal shaft are mounted on said standard with capacity for adjustment longitudinally of said standard.

4. In a drilling machine, a base, a standard rising from said base, a vertical axis motor carried by a bracket mounted on said standard and having a drill holding chuck at the lower end of the shaft of said motor, said shaft being disposed laterally of said standard, a work manipulating means carried by said base comprising a member mounted for vertical movement in a line which is substantially equal in distance from said standard as the axial line of the motor, a rod carried by said member and carrying a work holding means at the upper end thereof, spring means constantly imposing a bias tending to move said member downwardly, and manually operable means for moving said member upwardly comprising a horizontal shaft carrying a hand wheel at one end thereof and an eccentric means at the other end thereof engaging said member, said eccentric means being effective upon rotation of said shaft through a half revolution to move said work manipulating means upwardly against the bias of said spring means with resultant engagement of a work piece carried by said work holding means by a drill in said chuck.

5. A drilling machine as claimed in claim 4 in which said rod is vertically adjustable on said member.

6. A drilling machine as claimed in claim 4 in which said base carries a housing having aligned bearings in which said member is vertically reciprocable and other bearings in which said horizontal shaft is journaled. I

7. A drilling machine comprising a base, a standard rising from said base, a bracket projecting laterally from said standard and overhanging said base, a vertical axis shaft journaled in said bracket and held against relative endwise movement therein, said shaft having a drill holding chuck on the lower end thereof, a work holding means disposed below said shaft including manually operable devices for moving said work holding means upwardly toward a drill held in said chuck, said Work holding means including a bracket member, a shallow cup detachably secured to said bracket member adapted to support a work piece adhesively mounted thereon, and means detachably securing said cup to said bracket in an infinitely variable range of positions in a horizontal plane defined by said bracket member.

8. In a drilling machine a base, a standard rising from said base, a bracket mounted on said standard and projecting laterally therefrom a vertical axis motor mounted on said standard and overhanging said base a drill chuck on the lower end of the motor shaft, work holding and manipulating device carried by said standard adjacent to said base and comprising a bracket fixed to said standard, a pair of vertically spaced, horizontally parallel leaf spring elements each having one end thereof attached to said last-named bracket, means for supporting a detachable work holding means secured to the opposite ends of said leaf spring elements, a bearing bracket for a horizontal shaft projecting laterally from said standard below said second named bracket, a horizontal shaft mounted in said shaft carrying bracket and having a hand wheel on one end thereof and an eccentric member on the other end thereof, a work holding means detachably mounted on said supporting means and including a clamp screw element disposed above and in contact with said eccentric member whereby upon rotation of said eccentric member through a half revolution said supporting means and the work holding means mounted thereon will be elevated against the bias of said spring element in a substantially vertical line with resultant engagement of a work piece carried by said work holding means with a drill mounted in said chuck.

References Cited in the file of this patent UNITED STATES PATENTS 518,176 Brown Apr. 10, 1894 1,261,766 Challet Apr. 9, 1918 1,431,917 Antaramian Oct. 17, 1922 2,378,637 Jackson June 19, 1945

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