US2632858A - Support for vibratory devices - Google Patents

Description

March 24, 1953 c. L. CALOSI 2,632,858

SUPPORT FOR VIBRATORY DEVICES Filed NOV 16, 1950 2 SHEETS-SHEET l hum/r0? OM10 A. Cazos/ wwggh 197'7'0 A/EX March 24, 1953 Q ALQ$| 2,632,858

SUPPORT FOR VIBRATORY DEVICES Filed NOV. 16, 1950 2 SHEETS-SHEET 2 //V b EA/ 7'01? 00 940 1. c0; 05/

HTTOIP/VZ'Y Patented Mar. 24, 1953 UNITED STATES PATENT OFFICE SUPPORT FORv VIBRATORY DEVICE S1 CarloLt Calosi, Cambridge, Massi, assignor'to Raytheon' Manufacturing Company; Newton, Mass, a corporation of Delaware,

Application November 16, 1950, Serial'No. 195,925

Claims; 1.

This invention relates' to-tools and devices in which a-vibratory element is supported from anonvibratory platform or'handling element, and more particularly to support means which rigidly connects these'two elements together;

Vibratorydevices for drilling, chipping, abrad-- ing, and heating materials of various. kinds, operated ata wide variety-of fr'equenciesof vibration, are now well known. In copending application, Serial No; 128,989, filed November 23, 1949, there are disclosed andigenerically claimed ltwo embodiments .of'the invention. One of said embodiments is.1not specifically claimed insaid; co.- pending. application, but is. disclosedv andspecifically claimedherein; More recentlmdevices have been developed which operate at frequencies of vibration well above the upper limit ofhuman audibilitypand withiorces so great that substantial heat is generated in the devices. Thisrapid advance in design has necessitated consideration of theeproblemsof cooling and supporting the vibratoryelements; It has thus heretofore been a practice to supportthe vibratoryele-- ment of such a device froma nonvibratory ele-'- ment by means ofa flexible connection, forexample, a diaphragm; connected. to the vibratory, element at a node, in the hope thatthis arrangement would prevent vibratory energy from escaping from the vibratory; element into the. nonvibratory element. For coolingpurposes a housing is then usually arranged about thezmeans for. driving thevibratory. element, the housing being. attached to thenonvibratory element, andsealed watertight thereto.. A cooling. liquid" is then passed throughth'e housing whenthe device is operated For various reasons, the f oregoingarrangement is unsatisfactory. The diaphragm, contraryto expectations, is vibrated radially when a longi tudinal vibrator, passing through its center; is setinto vibration; The reason for this'isthat,

althoughwthe point of attachment ofthedia phragm to the longitudinal vibrator is a node for longitudinal vibrations, the Poissons ratio for the material of the longitudinal vibrator-determines the extent of radial oscillation of thelongitudinal begins to appearinthecooling liquid lwh'ichis in contactwith the diaphragm, and, as a'result,1the diaphragm is endangered. In addition, a diaphragm is nota rigid support; and, consequently, when alongitudinal'vibrator is so supported and brought into contact withamateria1tobedrilled; abraded, or otherwise operated'upon, precision work is quite diflicult; nor are these difficulties removed or lessened by' slidably mountingi'the vibratory element. in its support,.. for such a mounting cannothold the vibratory; element rigid and permit it *to vibrate 'atithei'same time, and is in addition quite complicated;

In" accordance'withi the present invention; a vibratory device'is providediin.whichavibratory system; consisting'essentially offanjelementwhich is'capable of being set into vibrationiandameans fori'driving' the same; isisupported" froiiiga non vibratory; element" by means. of axrigid, rather than a; flexible,- support ofja kindwhich presents an impedance to" vibrations intro ducedtherein" from the vibratory system, which impedance is 10v compared-with" that of the load into which the vibratory system is working: This combination of a rigid" support having'low impedance to the vibrations of the supporte tem'provides the desired ieature r gid wlth out extracting appreciableenergyfroin thew'ork ing system: It hasafurtheradvantage inthat only "very low 'order vibrations occur in the supeporting structure, which-can then-conveniently become" part of a Watertight 'housingsurround-- ing the driving means' withoutdanger-qtj being injuredon account of cavitationin'the cooling-- liquid.

Preferably; therigidsupport structure is at-- tached to the'vibratory system at 'anantinode; rather than a node;and'interposes aouarter wave length path between the-vibratory system and the nonvibratory element for vibrations at the :fre-

quency-of operation. With thisarrangement} the Fig. f is a graph useful in explaining the operation of the invention.

Referring now to Figs. 1, 2 and 3, the device there shown employs a longitudinal vibratory element it which is driven by a magnetostrictive driving means i i, these two parts together forn ing a vibratory system. The driving means. i i is of a kind which, iswell known and consists es have a length substantially equal to one-half a I wave length therein of oscillations at the operating frequency, while the vibratory element it may be any integral number of half wave lengths long, being illustrated herein as substantially one whole wave length. An antinode in this vibratory system at the region id where the driving means It is joined to the vibratory element it. The joining is readily effected in a well-lrnown manner by silver soldering the two parts together, for example.

A comparatively thin tube it, having a length which is substantially equal to one-quarter wave length therein of vibrations at the operating frequency of the device, is connected at a first end it to the vibratory element in at the region it of the antinode. At the other, or second end, the tube i5 is terminated in a relatively massive ring I! which constitutes the nonvibratory element of the device. The first end it of the tube i5 is slightly thickened and threaded internally, and the region M of the vibratory element it which is supported therein is correspondingly threaded for engagement therewith. An extending rim or boss i8 is provided at this end of the vibratory element, and a pair of spanner wrench holes it in this boss is employed to bring the boss tightly up against the confronting edge of the first end it of the tube i5. To this end, a second pair of spanner wrench holes 2!] (see Fig. 3) in the lower face of the nonvibratory element, ring ii, is provided for cooperative use in tightening the vibratory element in on the supporting structure. This assures that the vibratory element id will not be losened during operation. The relatively thin wall of the tube 15 is substantially thickened in the region 21 close to the massive ring ll.

When the vibratory system is set into operation, the region it thereof, being an antinode, undergoes oscillatory longitudinal displacement at the frequency and maximum amplitude of the system. The first end to of the tubular support l moves with this region and undergoes similar displacement. However, since tube i5 is onequarter wave length long as far as this oscillatory displacement is concerned, substantially no vibrations are impressed upon the nonvibratory support member, ring ll. Thus, ring I! can be made massive without danger that it will absorb any energy from the vibratory system. The tube l5 enjoys the rigidity of a tubular structure and, at the same time, extracts substantially no energy from the vibratory system. In fact, if the desired dimension are carefully observed, the region i l, in which the vibratory system is attachedto the first end It of the tube 115, will be one of zero impedance,

as far as the supporting structure is concerned, and absolutely no energy will be passed from the vibratory system into the supporting structure. It should be emphasized in this connection that in this region the supporting structure moves with the vibratory system as though it were a part thereof. Thus, with a properly designed supporting structure, the vibratory element I0 need not be threadedly engaged with the tube l5, but actually a simple frictional fit will be satisfactory.

Referring now to Fig. 4, the curves there shown illustrate the change of impedance of the supporting structure, tube 5, with frequency under various conditions. The solid curve 23 illustrates generally the nature of this relationship. At a frequency below the resonance frequency, that is, below the frequency at which the tube i 5 is a quarter wave length long, the impedance has a negative sign. As the frequency approaches resonance, the curve becomes a straight line, and, at the frequency of resonance, the impedance of the supporting structure is zero. As the frequency increases beyond that of resonance, the impedance assumes the opposite a1- gebraic sign, but the curve 23 is still a straight line, the shape of the curve being substantially the same on both sides of resonance. The change in impedance of the supporting structure is observed from the straight line position of the curve 23. It has been found that, when the wall of the tube 15, between the first end it which is attached to the vibratory system and the second end at the nonvibratory element 57, is made thin, the straight portion of the curve 23 becomes nearly parallel to the horiaontal axis along which frequencies are plotted, as is illustrated by the dotted line curve 2%. This means that, with small changes in frequency about the frequency of resonance, the impedance of the supporting structure [5 undergoes smaller changes in value as the wall of tube 35 is thinned, or in other words that the tuning of the supporting structure is less critical. Electrically, this is equivalent to inserting an impedance in series with a parallel resonant circuit to broaden its response curve. Curve 25 illustrates an opposite situation in which the tuning of the support structure is more critical. This situation might exist, for example, if it were desired to have the wall of the tube I5 very thick for extremely rigid support under sever operating conditions, and in this case it would be desirable to observe carefully that the length of the supporting structure and its point of attachment to the vibratory system were properly chosen.

The use of a thin-wall. tube l5 has been found to provide a supporting structure which is so uncritical in frequency that it can be attached to the vibratory system at regions other than an antinode without serious detriment. The reason for this is that, when the wall of the tube [5 is very thin, the amount of mass existing in a given length of support structure between the ends of the tube is greatly less than the amount of mass existing in an equivalent length of the vibratory element iii. For this reason, the impedance of the supporting structure is still very low, although it is not zero, and the amount of energy which is extracted from the vibratory system is quite small and not appreciable. Since 1 the supporting structure is a tube, it will be appreciated that the wall thereof may be made quite thin without appreciable loss of rigidity.

The nonvibratory element, ring 11, provides a convenient platform upon which to mount a watertight housing 26. The housing is in the form of a cylinder closed at one end and havin a heavy ring 27 at the open end. The rings 2'! and i? are bolted together, and a gasket (not shown) may be included between them, as is well known. A tube '28 in the form of a rin and having openings 29 therein is positioned at the top of the housing 25, and an inlet 39 for cooling fluid is connected to this tube through the wall of the housing. An outlet 3| for cooling fluid is provided in the nonvibratory element, ring H. In operation, the device is customarily supported with the closed end of thehousing 26 at the top and the open endat the bottom so that a cooling liquid, water for example, may be introduced through the inlet 39 and be sprayed downwardly over the driving means H and supporting structure i5, and escape through the outlet 3 i.

The coils it are furnished with leads 32 which are brought through an opening 33 in the nonvibratory element, ring H. A rigid pipe 34 is affixed in this opening and extends part way into the housing 28. For the purpose of preventing water from. leaking out through the opening 33, a watertight cap 35 surrounds the leads 32 and seals the top of the pipe 34.

The device may be mounted in any convenient manner. In the event that it is desired to mount the device in a drill press, the top 36 of the housing 26 is made of substantial thickness, so that an attachment member 3?, having a threaded extension 38, may be bolted thereto.

The free end 40 of the vibratory element is also at an antinode of the vibrations therein, and to this end a suitable workin tool may be attached for drilling, abrading, or other purposes. Since this feature forms no part of the prevent invention, no further discussion of it will appear.

It is realized that various other modifications of the invention may be made without departing from the spirit and scope thereof and without the exercise of further invention, and no attempt is here made to exhaust all such possibilities. It is, therefore, intended that the claims which follow shall not be limited by the details of the embodiment herein described and illustrated.

What is claimed is:

1. In combination, an elongated mechanical vibratory system, and substantially rigid tubular support means for supporting said system loosely enveloping a portion of said system and attached at one end to said system in a region which is substantially an antinode, said support means being of a length equal substantially to an odd integral number of quarter wave lengths therein of vibrations of said system.

2. In combination, an elongated mechanical vibrator and means attached to one end thereof to set said vibrator into longitudinal oscillation, said vibrator having a length equal substantially to one or more integral half wave lengths of the vibrations therein and antinodes at its ends, a substantially rigid cylinder having low sonic dissipation and having internal diameter larger than the cross-section of said vibrator and length equal substantially to an odd number of quarter wave lengths therein of said vibrations, telescopically enveloping said vibrator and attached at an end to said one end of said member, and a ring of comparatively great mass attached to the remaining end ofsaid cylinder.

3. In combination, a mechanical vibratory system including an elongated vibratory element and driving means attached to one end'thereof, rigid cylindrical support means attached at one. end to said element substantially at the junction with said driving means, said support means extending away from said junction along said element and terminating at the other end in a ring of substantial mass which surrounds and is spaced from said element, housing means including a top and side wall means attached to said ring and forming with said support means an enclosure completely enveloping said driving means.

4. In combination, a mechanical vibratory system including an elongated vibratory element and driving means attached to one end thereof, rigid cylindrical support. means attached at one end to saidelement substantially at the junction with said driving means, said support means extending away from said junction along said element and terminating at the other end in a ring of substantial mass which surrounds and is spaced from said element, housing rneans including a top and side wall means attachedto said ring and forming with said support means an enclosure completely enveloping said driving means, means,

providing fluid passages about said' side wall means near said top, means to conduct a cooling fluid into said enclosure via said'passages, and means in said enclosure near the bottom thereof providing a cooling fluid outlet.

5. In combination, a mechanical vibratory system comprising a vibration source and a tapered impedance transition element coupled to said source, and substantially rigid support means attached to said system for supporting said system, the inertia of said support means to vibrations introduced therein from said system being substantially less in the region of attachment of said support means to said system than the inertia of said system in said region, said inertia of said support means gradually increasing as a direct function of the distance away from said region of attachment, said support means being substantially resonant at the operating frequency of said source.

6. In combination, a mechanical vibratory system. comprising a vibration source and a tapered impedance transition element coupled to said source, having a substantially resonant operating frequency, and substantially rigid support means attached to said system substantially at an antinode of said system for supporting said system, the inertia of said support means to vibrations introduced therein from said system being substantially less in the region of attachment of said support means to said system than the inertia of said system in said region, said inertia of said support means gradually increasing as a direct function of the distance away from said region of attachment, said support means being substantially resonant at the operating frequency of said source.

'7. In combination, a mechanical vibratory system comprising a vibration source and a tapered impedance transition element coupled to said source, means to set said system into vibration, and substantially rigid support means attached to said system for supporting said system, the inertia of said support means to vibrations introduced therein from said system. being substantially less in the region of attachment of said support means to said system than the inertia of said system in 7 said region, said inertia of said support means gradually increasing as a direct function of the distance away from said region of attachment, said support means being substantially resonant at the operating frequency of said source.

8. In combination, a mechanical vibratory system comprising a source of ultrasonic vibrations, a tapered impedance transition element coupled to said source, and substantially rigid support means for supporting said system of a length equal substantially to an odd integral number of quarter wave lengths therein of vibrations of said source attached at one end to said system and terminated at the other end with a comparatively large mass, said attached end having a comparatively low mass.

9. In combination, an elongated mechanical vibratory system comprising a vibration source and a tapered impedance transition element coupled to said source, and substantially rigid tubular support means for supporting said system of a length equal substantially to an odd integral number of quarter wave lengths therein of vibrations of said source attached at one end to said transition element at a region in said system which is substantially at anti-node.

10. In combination, an elongated vibratory system comprising a vibration source, a tapered intpedance transition element coupled to said source, substantially rigid tubular support means for supporting said system attached at one end to said system, said support means being of a length equal substantially to an odd integral number of quarter wave lengths therein of vibrations of said source and having its wall intermediate its ends thin and of low mass compared with the mass of an equivalent length of said system, and a ring of comparatively greater mass attached to the free end of said support means, the thickness of said wall increasing gradually toward said ring.

CARLO L. CALOSI.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 924,195 Scribner June 8, 1909 1,966,446 Hayes July 17, 1934 2,383,383 Harding Aug. 21, 1945 2,445,318 Eldredge et al July 20, 1948 2,47 8,207 Robinson Aug. 9, 1949 2,514,080 Mason July 4, 1950 FOREIGN PATENTS Number Country Date 581,123 Great Britain Oct. 2, 1946 919,021 France Nov. 18, 1946

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