US 3601084 A
Description (OCR text may contain errors)
United States Patent Tamas-A. Biro;
Jeffrey R. Sherry, both of Danbury, Conn. 878,605
Nov. 21, 1969 Aug. 24, 1971 Bramon instruments, Incorporated Stamford, Conn.
lnventors Appl. No. Filed Patented Assignee ULTRASONIC-VlBRA'IION-TRANSMITI'ING MEMBER 7 Claims, 7 Drawing Figs. U.S.C1 116/137 A, 156/73, 259/1, 310/8.3, 310/26 Int. Cl. B061) 3/00 FieldofSearch ..1l6/137-137 A; 310/8, 8.2, 8.3, 26, 9, 9.1; 259/1;
Primary ExaminerLouis J. Capozi Attorney-Ervin B. Steinberg ABSTRACT: A vibration-transmitting member having large dimensions in planes perpendicular to the direction of vibration transmitted and adapted to be resonant in the sonic or ultrasonic frequency range is provided with internal bores to interrupt Poisson couplings between portions of such member. The bores are parallel to the direction of the vibration transmitted by the member.
Patented Aug. 24, 1971 2 Sheets-Sheet 2 FIG. 4
INVENTORS. TAMAS A. BIRO R. SHERRY BY JEFFREY ISA-*7 ULTRASONIC-VIBRATION-TRANSMITTING MEMBER This invention relates generally to ultrasonic devices and, more particularly, is directed to vibration-transmitting members having large dimensions in planes perpendicular to the direction of the vibration to be transmitted.
When vibratory energy is introduced at a restricted area of one surface of a vibration-transmitting member for utilization at an opposed surface thereof, vibrations having uniform amplitudes, that is a plane wave front, can be obtained at that opposed surface only if the dimensions of the vibrating transmitting member in planes perpendicular to the direction of the vibration to be transmitted to not exceed a predetermined value which is a function of the wavelength of the vibrations, as determined by the nature of the material forming the vibration-transmitting member and the frequency of the vibrations. Generally, the maximum dimensions in planes perpendicular to the direction of the vibrations should not exceed one-third the wavelength of the vibrations. Thus, for example, in the case of a vibration-transmitting member formed of aluminum or titanium with the configuration of a cylinder or block and having vibrations introduced at the center of one end surface from a conventional electromechanical transducer at a frequency lying in the range of kHz., a plane wave front is obtained at the opposite or output end surface only if the maximum dimensions in planes parallel to the end surfaces do not exceed approximately 3 inches. If such dimensional limits are not observed, the vibrations at the output surface have greater amplitudes at the center than at the periphery of the output surfaces. The foregoing phenomenon obviously limits the uses to which such vibration-transmitting members can be applied.
U.S. Pat. No. 3,1 l3,225 dated Dec. 3, 1963, issued to Claus Kleesattel et al. entitled Ultrasonic Vibration Generator" discloses one arrangement for providing a vibration-transmitting member of large dimension which produces at the output surface vibrations having substantially uniform amplitudes. This is accomplished by disposing in the transmitting member slots for interrupting Poisson couplings. Quite specifically, the slots are provided in a direction from the input surface to the opposed output surface of the transmitting member and extend transversely through the member and are located, moreover, to pass through the nodal plane of the transmitting member. The nodal plane or nodal region is the area at which there exists substantially no motion along the major axis of vibration, but on account of Poisson coupling the motion is in the direction normal to the desired output motion provided by the vibration-transmitting member. By arranging decoupling means in the form of slots in the area of the nodal region, the existence of a plane wave front at the output surface of the vibration-transmitting member is preserved. For a. more detailed and explicit discussion of this problem and one of the solutions, reference is made to the patent to Kleesattel et al.
In practice, it has been found, nevertheless, that it is not only difficult to machine slots of the type suggested heretofore, but when using certain material, such as titanium, the machining of slots is time consuming and expensive. The present invention, therefore, concerns itself with a simpler and less expensive method for providing relatively massive, blocktype vibration-transmitting members which include means for breaking the Poisson couplings. As will be described in greater detail hereafter, instead of longitudinal slots, the present disclosure describes the use of internal holes which, based on test conducted, have been found to be effective in serving the same purpose as the slots known heretofore.
One of the principal objects of this invention is, therefore the provision of an ultrasonic-vibration-transmitting member having large dimensions in planes perpendicular to the direction of the vibration transmitted.
Another important object of this invention is the provision of a vibration-transmitting member provided with less expen sive means for breaking Poisson couplings between portions of such member.
A further object of this invention is the design of a metallic vibration-transmitting member dimensioned to operate as a half wavelength resonator having a relatively large input surface and a relatively large output surface, and being provided with internal bores parallel to the directionof the vibration transmitted and extending across the nodal plane of the member for breaking Poisson couplings between portions of the member.
Further and still other objects of this invention will be more clearly apparent by reference to the following description when taken in conjunction with the accompanying drawings in which:
FIG. 1 is a schematic illustration of an arrangement requiring the use of an ultrasonic-vibration-transmitting member;
FIG. 2 is a top plan view of a typical transmitting member per the present invention;
FIG. 3 is a side elevational view of the member per FIG. 2;
FIG. 4 is a top plan view of another vibration-transmitting member per the present invention;
F IG. 5 is a side elevational view of the member per FIG. 4;
FIG. 6 is an elevational view of still another embodiment of a vibration-transmitting member, and
FIG. 7 is an elevational view of the other side of the transmitting member shown in FIG. 6.
Referring now to the figures and FIG. 1 in particular, numeral l0 identifies an electrical high frequency generator which supplies via a cable 12 electrical high frequency energy to a converter unit 14 which converts the supplied electrical energy to acoustic energy in the sonic or ultrasonic frequency range. The converter unit 14 includes for this purpose magnetostrictive or piezoelectric transducing means (not shown) and typically may be constructed as shown in detail in U.S. Pat. No. 3,328,610 issued to S. E. Jacke et al., entitled Sonic Wave Generator dated June 27, I967. A converter unit of this type is designed most suitably to operate in the range from 18 to 25 kHz., although other frequencies may be employed without deviating from the scope of the invention.
The converter unit 14 is coupled to a vibration-transmitting member 16 which applies the vibrations produced by the converter unit 14 to the workpiece comprising parts 18 and 20 which meet along a surface 19. If the workpiece parts are made of thermoplastic material, the arrangement depicted may be employed for producing a weld between the parts 18 and 20 along the mating surface 19 as illustrated and described in U.S. Pat. No. 3,224,916 issued to R. S. Soloff et al., dated Dec. 21, 1965 entitled Sonic Method of Welding Thermoplastic Parts."
The vibration-transmitting member 16 is a relatively massive member made of metal, such as aluminum or titanium, and is dimensioned so that the distance between the input surface at which the vibration-transmitting member receives the vibratory energy from the converter unit and the output surface at which the member transmits the vibratory energy to the workpiece is equal to an integral number of half wavelengths of the vibrations in the member. The design and dimensioning of vibration-transmitting members is described also in the book Ultrasonic Engineering" by Julian R. Frederick John Wiley & Sons Inc. New York, N.Y. (I965 pages 87 to 103.
Referring now to FIGS. 2 and 3 a typical embodiment of the vibration-transmitting member in accordance with the present invention is shown. The vibration-transmitting member, made for instance of aluminum or titanium, is a rectangular elongated block having an input surface 22 and an opposed output surface 24. The input surface 22 is provided with a threaded stud 23 which threads into a threaded hole in the converter unit 14. The vibration-transmitting member is designed so that its dimension from the input surface 22 to the opposite output surface 24 corresponds to an integral number of half wavelengths of the vibrations, this causes the member 16 to be resonant along its longitudinal axis along which the vibratory energy is introduced as seen in FIG. 1.
In order to interrupt Poisson couplings between the portions of the vibration-transmitting member, the member I6 is provided with a set of internal bores 25 which extend from the input surface 22 to the output surface 24. Thus, the bores are parallel to the direction of vibration and traverse the nodal region or regions of the transmitting member. If the-transmitting member 16 is a single half wavelength resonator the nodal region will be located half way between the surfaces 22 and 24, the latter being located at antinodal regions of the motion along the longitudinal axis.
It will be apparent to those skilled in the art that the circular holes or bores can be machined with much greater ease and facility than slots which require both a drilling and a milling operation.
A similar vibration-transmitting member is shown in FIGS. 4 and 5. The vibration-transmitting member 16A again is provided with a vibration-receiving input surface 22A and an opposite output surface 24A. In order to interrupt Poisson couplings the vibration-transmitting member 16A is provided with a plurality of bores 25A which extend from the input surface 22A to the output surface 24A. When comparing the design per FIG. 4 with the previous FIG. 2, it will be observed that three bores 25A replace the single bore 25 disposed at either side of the stud 23. The multiple-bore construction will be especially advantageous when the transmitting member is rather massive and a single hole would either remove too much material or is too time consuming for machining. Smaller holes are machined more readily when considering time and tool expense.
A further vibration-transmitting member is shown in FIGS. 6 and 7. The transmitting member 168 is designed to have increased vibrational amplitude at the output surface 248 and for this reason the output portion of the transmitting member is of reduced cross-sectional area, see Julian Frederick supra. In order to interrupt Poisson couplings, the vibration-transmitting member is provided with a set of bores 258 which start at the input surface 228 and extend toward the output surface 248 in the direction parallel to the applied and standing vibrations in the member.
As the bores 25B enter the reduced crosssectional area of the vibration-transmitting member, the holes break out and take the shape of slots. The slots terminate, in the example shown, a certain distance short of the output surface 248.
In a practical example, a vibration-transmitting member adapted to be resonant as a half wavelength resonator per FIGS. 2 and 3 made of aluminum material and designed for a frequency of 20 kHz. had the following dimensions: cross-sectional area 1% inch by 6 inch, length about /8 inch (tuned to kHz.), two holes I inch dla. spaced on centers 2.330 inch apart.
It will be apparent that the provision of circular holes or bores significantly simplifies the fabrication of such vibration msmitting members and that these members, using the teachmgs of the present invention, can be furnished with can ility and substantially reduced cost.
Whz; .c claim is:
l. The combination of:
an elongated vibration-transmitting member having an input surface and an output surface disposed at opposite ends;
means disposed at said input surface for receiving a vibration-generating means for introducing high frequency standing waves in said member, the distance between said input surface and output surface being equal to an integral number of half wavelengths of the vibrations in said member so that antinodal regions of motion appear at said respective surfaces and at least one nodal plane therebetween, and said member having internal bores whose axes are disposed substantially parallel to the axis of the introduced standing waves and said bores extending across said nodal plane to interrupt Poisson couplings between the portions of said member. 2. The combination as set forth in claim 1, said vibrationtransmitting member being of metal and dimensioned to be resonant at a frequency of at least 16 kHz.
3. The combination as set forth in claim 2, said internal bores being of circular cross section.
4. The combination as set forth in claim 2, said bores extending across the entire dimension of said transmitting member from said input surface to said output surface.
5. The combination as set forth in claim 2, said transmitting member being of rectangular cross section.
6. The combination of:
an elongated vibration-transmitting member having an input surface and an output surface disposed at opposite ends; means disposed at said input surface for receiving a vibration generating means for introducing high frequency sanding waves in said member, the distance between said input surface and output surface being equal to an integral number of half wavelengths of the vibrations in said member so that antinodal regions of motion appear at said respective surfaces and at least one nodal plane therebetween, and said member having internal bores extending from said input surface toward said output surface and across said nodal plane to interrupt Poisson couplings between th portions of said member. 1
7. The combination of:
an elongated vibration-transmitting member having an input surface and an output surface disposed at opposite ends and said surfaces lying in substantially parallel planes;
means disposed at said input surface for receiving a vibration-generating means for introducing ultrasonic high frequency standing waves in said member, the distance between said input surface and output surface being equal to one-half wavelengths of the vibrations in said member so that antinodal regions of motion appear at said respective surfaces and one nodal plane therebetween, and
said member having internal bores whose axes are disposed substantially parallel to the axis of the introduced standing waves and extending across said nodal plane to interrupt Poisson couplings between the portions of said member.