US 3640180 A
A device for delivering vibratory energy to a work-performing tool is disclosed having one end connected to a vibration generating means and providing for mechanical attachment and alignment of the tool at the work-performing locale which is located at a vibrational antinode in the vibratory system. The vibratory device, or toolholder, may be conveniently mounted on a lathe crossfeed table.
Description (OCR text may contain errors)
O ilmted States Patent [151 3,640,18d
Mampis 1 Feb. 8, 1972  APPARATUS FOR DELIVERING  References Cited VlBRAToRY ENERGY UNITED STATES PATENTS  Invent N'dmlas westcheste" 3,466,970 9/l969 Jones ..90/1| R  Assignee: Aeroprojects Incorporated, West Chester,
Pa. Primary Examiner-GilWeidenfeld  Filed: A 17, 19,70 At:orney-Seidel, Gonda & Goldhammer  Appl.No.: 29,588  ABSTRACT r A devicefor delivering vibratory energy to a work-performing  U.S.C|. ..90/1l R, 82/1 R, 408/24l l is i lo e h ing n en c nnec to a vibration  Int. Cl ..,.;.B23b 3/00 generating means and providing for mechanical attachment  Field of Search .;9()/l l R; 82/2'R,l R, DIG. 9; andalignment of the tool at the work-performing locale which 29/470, DIG. 46; 5 l/DlG. 11
is located at a vibrational antinode in the vibratory system.
-The vibratory device, or toolholder, may be conveniently mounted on a lathe crossfeed table.
12 Claims, 4 Drawing Figures PATENY ED EB 8 I972 SHEET 1 [IF 3 O E aa.
PATENTED FEB .8 I972 SHEET 3 [IF 3 rpm OVER/Mus =5/8l/VCH TOOL OVERHAIVG= O O O o 0 5 4 3 2 I $29630? women 60k ELECTRICAL POWER TO TRANSDUCER (WOHS) APPARATUS FOR DELIVERING VIBRATORY ENERGY The invention described herein was made in the course of, or under, a contract with the United States Atomic Energy Commission.
This invention relates to a vibratory device for the delivery of high-frequency mechanical energy to a work-performing tool and more particularly to the tool retention member fonning a part of said vibratory device.
This invention is an improvement over the apparatus disclosed in U.S. Pat. No. 3,466,970, Transducer Coupling System, issued Sept. 16, 1969. That patent discloses apparatus for effective operation of a vibratory cutting tool, such as may be used for instance on a lathe, shaper, or planer, with provision for removal and replacement of cutting tool tips. In said apparatus, however, the position of the tool relative to the workpiece is adjustable only through gross movement of the ultrasonic apparatus, so that adjustment parameters of more conventional cutting machines are not attainable.
Power transmission in vibratory devices is most efficient when, insofar as possible, all vibratory components are designed to resonate at some frequency of operation in the proper mode to facilitate function of the apparatus. Component dimensions are selected in accordance with their material of construction and the selected operating frequency. It is not uncommon, however, for a vibratory energy delivery system to incorporate, or to terminate in, a work-performing tool such as dies for wire or tube drawing or abrasive-impregnated drills for impact machining. Although obvious benefits are derived from utilizing work-performing components of standard design and availability, these components are not of acoustic design and therefore must be vibratorily accelerated at the operating frequency of the vibrating system, thereby imposing a mass-loading effect on the system and reducing the ability of the system to deliver power.
As convenient replacement of work-performing tools is es sential in a practical system, straightforward mechanical attachment of the tool as by bolts, nuts, or threaded collars, may be desirable. Attachment means must be sufficiently rigid to preclude unacceptable tool deflection, which can lead to chatter, resulting in poor surface finish on the workpiece and/or tool failure. Such rigid attachment means further increases the mass-loading effects on the vibratory system and reduces power delivery.
The present invention comprises a vibratory toolholding device which is adapted for use in vibratory energy delivery systems to overcome the above disadvantages. The toolholding device is resonant-dimensioned to partake in the vibratory motion of the ultrasonic system while serving as an attachment means for essentially standard commercial cutting tools. In addition, the device provides the necessary rigidity so that the cutting process can be carried out without random vibration being excited in the ultrasonic system.
In the present invention, the cutting tool is interposed between a rocker base and a spherical segment, which are maintained in alignment under static compression by the mechanically connected tool base and toolpost screw member, and which permit angular, rotative, and axial adjustment of the tool. Additionally, the tool base and the toolpost screw member are resonant-dimensioned according .to their material of construction and the operating frequency of the system, and acoustically couple the tool to the transducer array so that the tool will be made to excursion in continuum with the vibrating system and deliver the necessary ultrasonic power to the work locale. The rocker base and spherical segment constitute negligible mass loads on the tool base and toolpost screw member respectively. Therefore, the 1 toolholder, or tool attachment means, is an integral part of the ultrasonic transmission system and does not constitute a mass load on the system.
An object of the present invention is the provision of\a vibratory tool-retention device adapted for application in a vibratory cutting process.
The invention has as a further object provision'for tool adjustment in the axial, rotative, and angular positions'not associated heretofore with vibratory cutting devices.
Other objects and advantages will appear hereinafter. For the purpose of illustrating the invention, there is shown in the drawing a form which is presently preferred; it being understood, however, that this invention is not limited to the precise arrangements and instrumentalities shown.
FIG. 1A is an elevation view, partly in section, of one embodiment of the present invention.
FIG. 1B is a sectional view of a portion of the device in FIG. 1A, but in accordance with another embodiment of the present invention.
FIG. 2 is a graph illustrating the effect of tool overhang on cutting force in a vibratory energy delivery system.
FIG. 3 is a graph'illustrating the ultrasonic influence on cutting force.
Referring to the drawings in detail, wherein like numerals indicate like elements, there is shown in FIG. [A an ultrasonically activated cutting device designated generally as 10 associated with a machine tool such as a lathe. The cutting device 10 includes a means for generating vibratory energy such as the ceramic transducer array 12 of the type shown in U.S. Pat. No. 3,283,182 titled Transducer Assembly" issued Nov. 1, 1966 in the name of J. B. .lones, et al. The disclosure of U.S. Pat. No. 3,283,182 is incorporated herein by reference. It will be recognized by those skilled in the art that other types of ultrasonic transducers or arrays, such as nickeliron magnetostrictive, may be substituted for the transducer array 12.
Member 14 of transducer array 12 and toolpost screw member 16 are of the same diameter and are joined together coaxially at interface 18 by the threaded member 20. Interface 18 is located at a vibratory antinode in the system. At its lower end, toolpost screw member 16 is contoured to accept essentially all of the spherical segment 24 at its concave face 21. Member 16 has a transverse passageway, 22 to facilitate clamping of cutting tool 26 as will be made clear hereinafter. In FIG. 18, there is illustrated an alternative construction for the toolpost screw member designated 17. Member 17 is identical with member 16 except that it is hollow and internally sculptured at 19 in accordance with its cross-sectional area for the purposes of increasing the amplitude of vibration, such sculpturing being well known in the art;
As illustrated, member 16 is one-half wavelength long in the material of construction and at the operating frequency of the transducer array 12. However, the total distance from interface 18 to the other end of member 16 maybe any aggregate whole number multiple of one-half wavelengths.
A tool base 38 is provided below and axially aligned with member 16. Base 38, as illustrated is one-half wavelength long. At the upper end of base 38, there is provided a radially outwardly extending flange for metallurgical attachment as by brazing to a force-insensitive mount 30 which surrounds it. The brazed attachment is between said flange on base 38 and a radially inwardly extending flange 29 on mount 30. While it is normally not desirable to join a force-insensitive mount to a vibration transmitting member at any location other than an antinode (location of minimum strain), in the present embodiment, attachment of mount 30 by brazing at flange 29 is permissible since the cross-sectional area-and therefore the vibratory strainat flange 29 is essentially the same as that of base 38 at the flange site, resulting in insignificant vibratory stress on the braze joint. At its lower end, base 38 is free from attachment. Hence, base 38 provides the effect of a heavy mass without mass loading the vibratory system, thereby sta bilizing the excursion of rocker base 27 in the area of its support for the cutting tool 26. Base 38 also precludes unusual and extraneous modes of vibration such as might detract from system efficiency and effectiveness.
Mount 30is ofthe type disclosed in U.S. Pat. No. 2,891,178 or 2,891,180. Mount 30 is internally threaded at its upper end for threaded attachment to member 16 at joint23 located at an antinode in the system. Therother end of mount 30 is free from attachment. At a location which is one-quarter wavelength from the free end of mount 30 there is provided a radially outwardly extending flange 32 for metallurgical attachment as by brazing to support sleeve 36 at interface 34, which is located at a node in the system. The other end of support sleeve 36 extends radially outward at flange 40 for attachment to lathe cross feed table 42 or an adapter plate thereof by means of clamping ring 44 and threaded fasteners 46. It should be clear that the entire device 10 can be rotated about its longitudinal axis AA by loosening fasteners 46. It should be clear that the entire device 10 can be rotated about its longitudinal axis AA by loosening fasteners 46 so that flange 40 can be rotatably moved under clamping ring 44. Support sleeve 36 may be of any convenient length, preferably approximately one-quarter wavelength long. Table 42 facilitates movement of the system and tool toward and away from workpiece 50.
Rocker base 27, in the form ofa segment of a right cylinder, is juxtaposed to the concave mating surface 31 of base 38. Base 27 supports cutting tool 26 which may be disposed in a transverse notch on the upper surface thereof. Said tool 26 extends through windows 28 of mount 30 and is free from contact with said windows. With spherical segment 24 supported by the cutting tool 26, member 16 is threadedly connected at joint 23 to the force-insensitive mount 30. Transverse passageway 22 is provided to accept a tool for applying torque at the threaded joint 23 to provide the appropriate static compression for tool retention, or to release the compressive load on cutting tool 26 for realignment or for tool removal for maintenance or replacement. Angular rotation of the cutting tool 26 to accomplish change in the position of the cutting edge 26A vertically upwards or downwards with reference to the workpiece 50 is accomplished by loosening member 16 and manually rotating tool 26 about the axis of rocker base 27 within the limits of window 28, Thereafter, member 16 may be retightened. Such angular rotation of tool 26 is with respect to the longitudinal axis of base 27, parallel to the longitudinal axis of workpiece S in FIG. 1A.
The overhang of the cutting tool 26 can be adjusted so that said cutting tool resonates flexurally with the ultrasonic system, thus reducing the mass loading effects of said cutting tool and increasing the effectiveness of the system. Said overhang is the linear distance between cutting edge 26A and the outside periphery of the clamping zone on tool 26 effected by segment 24 and rocker base 27 and is measured parallel to the axis of the tool 26. Overhang of tool 26 is adjusted by loosening the threaded joint 23 between member 16 and mount 30. Tool 26 is then moved in its axial direction and said joint is retightened.
The apparatus of the present invention and its associated vibration generating means were mounted on a Sebastian Model B-6 lathe, and the effect of tool overhang was investigated. A 3 inch long, inch square machining tool was used to reduce the 2% inch diameter ofa l045 steel billet at a cutting speed of 90 surface feet per minute, a feed rate of 0.002 inch per revolution, and a depth of cut of 0.085 inch. Said cutting tool was vibration activated by 200 watts of nominal 28 kHz. electrical power into the transducer. Tool force reductions effected by tool overhang L are indicated in FIG. 2. As noted, best performance was obtained with overhang ranges of 0.59 to 0.70 and 1.05 to H inches. In some instances it may be necessary to select tool overhang not only on the basis of flexural response of the cutting tool 26 but also upon the machine clearance limitations, so that in a cutting operation tool overhang L may be selected from one or the other of the recommended ranges.
At the same machining parameters noted above and at tool overhangs selected in accordance with the foregoing, the highfrequency electrical power delivered to the transducer was varied and efi'ected force reductions under ultrasonic influence at the power levels as illustrated in FIG. 3. Additionally in face-cutting 2% inch diameter 1045 steel, force reductions up to 39 percent were effected. Force reductions up to 50 percent were effected when face-cutting 3 inch diameter aluminum.
While the present invention has been illustrated and described in its relation to a lathe, it will be appreciated that it may be used in other applications wherein rigid mounting, controlled vibratory motion, and adjustment parameters relative to a workpiece are desired or necessary.
The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof and, accordingly, reference should be made to the appended claims rather than to the foregoing specification as indicating the scope of the invention.
1. Apparatus comprising a vibratory generating means, a vibratory energy coupling system having one end coupled to said means, said system having a length corresponding to at least two or an integral number in excess thereof, of one-half wavelengths according to the material properties and geometry of said system and its intended operating frequency, a work-performing tool removably and adjustably supported between the ends of said system adjacent an antinode thereon, means for adjusting said tool in axial, angular, and rotative positions, means for moving the system and tool as a unit, and means for supporting the system at a node of vibratory energy in said system, said node being located between said tool and the other end of said system.
2. Apparatus in accordance with claim 1 wherein said means for moving the system and tool as a unit supports the system and tool for rotation about a vertical longitudinal axis of the system.
3. Apparatus in accordance with claim 1 wherein said means for adjusting the tool includes a spherical segment above the tool, a rocker base below the tool, said tool being clamped between flat surfaces of said segment and rocker base by components of said system.
4. Apparatus in accordance with Claim 3 wherein the components of said system are removably coupled together at a joint located at said antinode in the system.
5. Apparatus in accordance with claim 3 wherein one of said components has one end engaging said segment and is hollow.
6. Apparatus in accordance with claim 5 wherein said hollow component is sculptured in accordance with its cross-sectional area so as to have a nonuniform wall thickness with the thickness of the wall increasing in a direction away from said segment.
7. Apparatus in accordance with claim 1 wherein said means for adjusting angular and axial positions of said tool includes two coaxial components of said system removably coupled together at said antinode in the system, said tool extending through an opening in a support connected to one of said components.
8. In a lathe having a head stock means, a crossfeed table mounted for movement parallel and perpendicular to a horizontal axis of the lathe, a cutting tip supported by said table for movement therewith and effecting a cutting action on material rotating on said axis, a vibratory coupling system supported by said table, a vibratory energy generating means, said coupling system having one end coupled to said generating means for transmitting vibratory energy to said tip, said coupling system having a length corresponding to at least two, or an integral number in excess thereof, of one-half wavelengths according to the material properties and geometry of said coupling system at its intended operating frequency, means removably and adjustably supporting said tip adjacent an antinode on said coupling system for rotation about the axis of said system and for rotation about an axis perpendicular to the axis of said system, with the longitudinal axis of said coupling system being generally perpendicular to said horizontal axis.
9. In a lathe in accordance with claim 8 wherein said toolsupporting means includes coaxial components of said system threadedly coupled together for supporting said tool in a clamped position.
10. In a lathe in accordance with claim 9 wherein a support system. connected to one of said components has an opening adjacent 12. Apparatus in accordance with claim 11 wherein said one end through which the tool ext nds, tool overhang is in the range of 0.59 to 0.70 or 1.05 to 1.15
11. Apparatus in accordance with claim 1 wherein said tool inchesoverhangs to an extent so that it resonates flexurally with said 5 vis