US 2831295 A
Description (OCR text may contain errors)
April 22, 1958 M, E. wElss 2,831,295
ULTRASONIC DRILL Filed Sept. 21, 1955 j 3 Sheets-Sheet l l 27 4:. T O C&
INVENTOR. MORTIMER 5. wa /5s HTTOENEY April 22, 1958 M. E. WEISS 2,831,295
. ULTRASONIC DRILL Filed Sept. 21, 1955 v s Sheets-Sheet 2 TiTE.
INV MORTIMER E. WEISS HTTORNEY I M. E. WEISS ULTRASONIC DRILL 3 Sheets-Sheet 3 INVENTOR. MORTIMER E. WEISS BY i /MW H TTO BN5 7 April 22, 1958 Filed Sept. 21, 1955 Industries,
for coupling the piezoelectric transformer of the drill.
,My invention relates to ultrasonic drills and cuttingequipmentand in particular to those'ultrasonic drills and cutters which are driven bypiezoelectric elements.
A principal objectof my invention is to provide means element to the velocity A further object of my invention is to'provide means for mounting the velocity transformer so that the entire assembly is rigidly supported without restricting the operation of the machine.
A still'furtherfobject of my invention is to provide former. V v
A still further 'object of my invention is to provide means for'coolingthe piezoelectric element.
A still further object of my invention is to provide U i e W8 mf Mortimer E. Weiss, Flushing, assignor to (Fulton c., Metuchen, N. J., a corporation of 2,831,295 Pa te rt-ea 2.5
My design overcomes many of the disadvantages whieh existed heretofore. l I
' To prevent stresses and possible fracture of the ceramic piezoelectric element 30, I "provide a bond 35 between 30 and velocity transformer 13 which possesses some compliance. This compliance permits'a slight movement of 35} radially without appreciable attenuation of its desired longitudinal vibration. B on'd35 is composed preferably 1 of an epoxypla stic or polymer or other suitable polymer with proper adhesive and acoustical properties. Other agents of similar bonding and compliance characteristics may also be employed. The, longitudinal vibrations are utilized to drive velocity transducer 13 whpse motion piece of material with"the basic shape consisting of two means for attaching various tools to the velocity transmeans for accommodating variousfsized velocity transformers to thesamedrill unit. s Other objects" and advantages ofjmy invention will be apparent during the-course ofthc following description; In the accompanying drawings, forming a partof this takes place along its axis.
Velocity transformer 13 is fabricated item .a isin'gle cones13a and 13b with differing slopes, so combined that the nodal surface of"-13 is located at the plane at which the transition from l3a to 135 takes place; The surfaceof velocity transformer 13iscylindrical at. this transition plane so that clamping ofthej assembly may be accomplished at the nodal surface. "'1" Bushing 33 is placed on 13 at the nodal surface and mounting flange 34 is placed around 33. Mounting flange 34 has a slot which maybe aligned with the slot in transducer support 16, therebypermitting the tightening means of 16 to suitably tighten both 16 and 34. This mounting method permits the entire assembly to be clamped rigidly in-place simply and easily and alsomakes itpdssiblefor a single transducer support 16 to be used for clamping variouslysized velocity transformers 13. This maybe ac- Icomplished by the use of suitably sized mountingflanges 34 with their outside diameters properly dimensioned so application, and in which like numerals are employed to designate like parts throughout thefsame Figure 1 is a side elevation of a preferred embodiment of my invention,
Figure 2 is a side elevation of the embodiment of Figure 1, viewed from the opposite side from that of Figure 1,
Figure 3 is a vertical sectional viewl or the housing of the preferredembodiment of Figure11,--
Figure 4 isa cross-sectional view along the line of Figure 2, I
Figure 5 is a front elevational v1ewyof, the work table of ,the preferred embodiment of Figure, ,1, and
Figure 6 is a cross sectional view-along the line,6 6 of Figure 5. a
In the drawings, wherein for the purpose of illustration, is shown a preferred-embodiment of my invention, the numeral 10 designates the drill housing, thenumeral 11 designates the generator cable and the numeral 12 designates the drill stand, generally. Velocity transformer 13 is a dual cone, the larger diameter cone being designated as l3a and the small diameter cone being designated as13b. Tool tip 14 is suitably attached to the end of 13. Transducer support 16 is held in place on drill stand post 17 by transducer support adjustment clamp 15.
Ventilation holes 18, 18a and 18b serve to air cool piezo- A electric element 30,;the air being kept in circulation by fan 29 which is driven by fan motor 28 whose power is supplied through cable 27. The inner electrode connector 31 is electrically connected to electrical lead 11-1 and outer electrode connector 32 is electrically connected to electrical lead 11-2. Electrical leads 11-1 and 11-2 together form the electrical elements of operator cable 11. Bushing 33 is placed in flange mounting 34 of transducer support 16. Bond 35 mechanically bonds 30 to 13.
Ultrasonic drills and cutting tools, produced in accordance with my invention, are more stable in operation and as to fit into transducer support 16.?
Bushing *33 is made of nylon or a like thin compliant material. Its function is to acoustically isolate the burn from the drill stand and its size maybe changedwithin 1 reasonable limits, thereby increasing the'flexibilitybf the mounting sothat varying sizes of velocity transfermers 13 may-be used in conjunction with a single transducer support 16. i v
In operation, piezoelectric element 30 will get hot and crack after long service unless steps are taken to cool it. I choose to air-cool 30 by means of fan 29, motor 28, and ventilation holes 18, 18a and 18b. The blades of fan 29 and its direction of rotation is so arranged that the air is drawn in through the lower holes 18 inhousing 10 and out throughthe upper holes 18in housing 10.
This draws cooling air along the outside surface of. 30. In
addition, I have provided holes 18a and 18b in velocity transformer 13 which permits cooling air to bedrawn up inside 30 and out through upper holes 18. In this manner, greater cooling of 30 is achieved than is possible with outside air-cooling only, thereby providing sufiicient cooling and eliminating the expense and inconvenience of liquid cooling.
Work table 19 is arranged so that itgmaybe moved vertically along drill stand post 17 and clamped in places by tightening work table adjustment clamp 20. The level of 19 is determined by work level adjustment 21 which cooperates with rack 36. Limit screw 26 is now set so that 19 will move upward under the urging of extension arm 24 and weight 23 only as far as the setting of 26 will permit. This upward motion of 19 keeps moving the a work toward tool tip 14 rather than requiring the tool tip to be moved down as the drilling takes place in the work. More accurate drilling and cutting is possible when the work is moved toward the tool tip because it is possible to mount the drill housing 10 rigidly and thereby accurately position 13 and 14. Dial indicator 25 is employed to set limit screw 26 and to read the depth of cuttingor produce better results than previously used equipment. I drilling directly. Limit screw arm 37 serves to mechani- 3 c'ally couple the action of limit screw 26 to the resultant "leverer is. Limit screw arm 37 is rigidly attached to work table rack 36 and indicator 25 is fixedly attached QtOQW-OIK table -support-22. 36; moves up and down with "fel'ation to'fl audit cannofmove beyond the setting of ,26 because as 36 rises, 26 also rises and depresses the element of'j25 with whichj'it is in contact. When this lement of 25 is pushed completely'intothe-housing of 25 under the urging. of 26, the upward motion of 26, 36 and 19 with respect to 22wil1 stop. 7 7' Tool tip" 14 is hard soldered onto a screw stud or is fshap ed from'the screw stud itself. Various-shapes of 14 m ay be used. This drilling method is particularly advantageousfor cutting holes with sharp corners such as 1 squares, triangles,- etc" I have preferred to tap the end of 'I'I3Qand1to screw 14: into the tapped hole until the end of 14 bottoms firmly into the tapped hole. When 14 is made of. a capped screw, namely one in which the work- 'ing end of the tool is larger in cross-section than the threaded portion,'it is necessary for the end of the tool tip 14 to bottom firmly and for the cutting end of the tool to be seated firmly against 13. When the tool 14 is tof be subjected to long, continued use, it is advisable to 1nelt a small amount of shellac or similar mate rial onto the threads of 14 and'in the tapped hole of 13 before screwing of'1-4 into 13. This serves to securely bond 14 [Z0 13. I
" In addition tothe special techniques, herein described,
standard ultrasonic drilling and cutting processes may be employed during'use of ultrasonic drills produced inaccordance with my invention. Examples of the standard ultrasonic drilling and cutting processes referred to above are those which employ liquidsolutions of abrasive par-= fticlesIto accomplish the cutting and those inrwhich the drill moves toward the work which is held in a stationary position;
While'I have'described my invention by means of specific examples and in a specific embodiment, I do not wish to be limited thereto, for obvious modifications will occur to those skilled in the art without departing from the spirit of my, invention or the scope of the subjoined claims;
Having thus described my invention, 1 claim:
1. An ultrasonic drill comprising a hollow, piezoelectric ceramic, cylindrical body, a velocity transformer bonded to said cylindrical body by compliant bonding means,;tool means attached to said velocity transformer,
, housing means containing said cylindrical body and said velocity transformer, -air circulation means Within said housing means, housing support means, work carrying means and support means supporting said housing support means and said work carrying means, said velocity transformer being formed of two joined truncated cones of dilfering base radii and with a common axis, the'base of said cone with smaller'base radius being of substancone withlarger base radius and joined to said smaller base of the cone with larger base radius at the nodal surface of said velocity transformer, said velocity transformer being supported at said nodal surface, said velocity transformer carrying openings therein, one of said openings being in the larger base of said velocity transformer adjacentsaid cylindrical body, at least one opening being in the surface of revolution of said velocity transform'en'said openings being connected within said velocity transformer, said air circulation'means being positioned was to circulate cooling air over the surfaces of said cylindrical body, the inner surface of said cylindrical body being cooled by air drawn through said openings carried by said velocity transformer by said air circulation means. I
2. An ultrasonic drill comprising an electro-mechanically sensitive body, a velocity transformer bonded to said clectro -mechanically sensitive body by compliant bonding means, tool means attached to said velocity transformer, housing' meanscontaining saidelectro-mechanically sensitive body and said velocity transformer,
"air circulation means within said housing means, said means andsupport means supporting said housing support means and said work'carrying means, said velocity I Q transformer being formed of 'two joined truncated cones of diifering base radii and with a common axis, the base of said cone with smaller base radiusvbeing of substantially the same dimensions as the smaller base of said cone with larger base radius and joined tor said smaller base of the cone Ywithlarger base radius at the nodal surface of said velocitytransformer, said velocity transformer being supportedat said nodal'surface, said work carrying means comprising a table, a weight, extension arm and'trave llimiting means 'such that'when said ultrasonic drillis operated in its normal and intended manner said weight and extension arm urge the object being worked upon toward said'tool means, said travel limiting meanslimiting such travel to a predetermined amount.
'ReferencesLCited'in the file of this patent UNITED STATES PATENTS OTHER REFERENCES Design News, volume 9, No. 20, October 15, pages 38 and 39.