US3295349A - Method and apparatus applying vibratory energy - Google Patents

Description

N. MAROPIS 3,295,349

METHOD AND APPARATUS APPLYING VIBRATORY ENERGY Jan. 3, 1967 Filed Oct. 4, 1965 INVENTOR.

86701:" L and 60/VOA Attorneys.

Patented Jan. 3, 1967 3,295,349 METHOD AND APPARATUS APPLYING VIBRATORY ENERGY Nicholas Maropis, West Chester, Pa, assignor to Aeroprojects Incorporated, Chester, Pa., a corporation of Pennsylvania Filed Oct. 4, 1965, Ser. No. 492,669 4 Claims. (Cl. 72-283) The present invention relates to a method and apparatus applying vibratory energy, and more particularly to a method and apparatus for applying vibratory energy in plug-drawing of articles including tubing.

Floating-plug drawing can be used on either discrete straight tubing lengths or long-length or coiled tubing (a draw bench being used for the first, and a draw block for the second). The application of vibratory energy in connection with such floating-plug drawing has been suggested heretofore, in US. patent application Serial No. 321,041 filed November 4, 1963, in the name of Charles A. Boyd, entitled, Apparatus and Method for Applying Vibratory Energy, now Patent No. 3,209,574. In that application, it was proposed to use :a plug having a length equal to an integral number of one-half wavelengths in the material of which it is made at the frequency of operation.

It has now been found that considerably improved results are obtained using a plug having a physical length corresponding to an acoustic length of an odd integral number of one-quarter wavelengths of sound in the material of which it is made at the frequency of operation.

Accordingly, it is an object of this invention to pro vide an improved method and apparatus for drawing of tubing.

Another object of the invention is to provide an im proved system for plug drawing of tubing under vibratory energy application.

It is also an object of this invention to provide an improved floating plug system for drawing of tubing under vibratory energy application without the necessity for joining the plug securely to a source of vibratory energy.

A further object of this invention is to provide an improved method and apparatus for continuous drawing of tubing.

These and other objects of the invention are accomplished by providing a plug having a controlled acoustical geometry and by drawing with said plug under the infiuence of a vibratorily activated die.

For the purpose of illustrating the invention, there is shown in the drawings forms which are presently preferred, it being understood, however, that this invention is not limited to the precise arrangements and instrumentalities shown.

FIGURE 1 is an elevational view of apparatus embodying the present invention, partly in section and partly in diagrammatic form.

FIGURE 1A is an enlarged sectional view of a fragment of the apparatus illustrated in FIGURE 1.

Referring to the drawings in detail, wherein like numerals indicate like elements, there is shown in FIGURE I 1 a vibratory tube drawing apparatus designated generally as 10.

The apparatus is in the nature of a draw bench (block) and includes a die 12 having an orifice 14. A floating plug 16 (see FIGURE 1A) extends into or through the orifice 14 and defines with the die 12 a restricted passageway through which the tube material 30 is drawn.

Die 12 is an element of a transducer-coupling system (designated generally 'as 38), other elements of which are acoustical coupler 40 and a plurality of transducers designated a, 50b, 50c, and 50d (the last not shown).

System 38 is designed to operate at a given frequency, which is preferably a resonant frequency. System 38 is preferably dimensioned to have an over-all physical length equivalent to an acoustical length of a whole even number multiple of one-half wavelength in the material of which it is made at the said frequency, so as to have, for efficient operation, an antinode (loop) area of the vibration at the tube-contacting portion of the die.

Each of the transducers 50a, 50b, 50c, and 50d is preferably of the electrostrictive-assembly type as shown. Reference is made to United States patent application Serial No. 456,900 filed May 11, 1965, in the names of James Byron Jones and Nicholas Maropis and entitled, Transducer Assembly, for details concerning construction and advantages of a transducer such :as transducer 50a. The transducers 50b, 50c, and 50d are constructed in the same manner as transducer 50a.

While the above indicated electrostrictive transducer construction is preferred for purposes of the present invention, it will be appreciated by those skilled in the art that other known types of transducers may be substituted. For example, other types of electrostrictive, piezoelectric, or magnet-ostrictive transducers may be utilized.

The transducers StPa-b-c-d are connected to a power supply (not shown) suitable for powering them at the desired frequency. In the case of this embodiment, that frequency is 28,000 cycles per second (28 kc.), inasmuch as each of the transducers Stla-b-c-d is constructed to operate at that nominal frequency. Such power supply equipment is well known to the art.

The aforesaid power supply system, in a typical example, is capable of producing electrical signals in the range of between about cycles per second and about 300,000 cycles per second. This frequency range is suitable for purposes of the present invention, including as it does frequencies in both the audible range (such as up to about 15,000 cycles per second) and the ultrasonic range (generally above about 15,000 cycles per second). A preferred frequency would be in the range of from about 3,000 to about 50,000 cycles per second, with the optimum being between about 14,000 to about 35,000 cycles per second. Normally, :a frequency is chosen which will provide a suitable size of apparatus for a given application or set of applications, with the ultrasonic range having the further advantage of inaudibility for operator comfort.

Thus, transducer-coupling system 38 may be constructed to operate at 28,000 cycles per second, for example.

As is well known to the art, the electrical frequency of the alternating current power supply (such as 60 cycles per second) is changed to match the mechanical or elastic vibratory frequency of the transd.ucers.(28,000 cycles per second in this example, as aforesaid).

It is to be noted that the source of high frequency alternating current may be of the solid state type (generally more suitable for relatively low power requirements), the vacuum tube type (generally for low or intermediate power requirements), or the motor alternator type with suitable frequency control (particularly appropriate for applications requiring relatively large amounts of power).

The die 12 has, for purposes of ease of attachment to acoustical coupler 40, an axially extending portion 42 (see FIGURE 1A) to whose outer surface one end of coupler 40 is secured by means of cooperating threads. The other end of coupler 40 which is remote from the die (said end having four projections in this embodiment) is fixedly secured to the transducers 50a-b-c-d. That is, one end projection of coupler 40 is joined to transducer 50a, the second end projection is joined to transducer 50b, the third to transducer 500, and the fourth to transducer 50d, preferably by brazing or some other type of metallurgical joint or as described (for the transducer-assembly of this embodiment) in the above-identified application Serial No. 456,900.

Acoustical coupler 40 is essentially a mechanical transformer and is of contoured construction for purposes including the increasing of the amplitude of vibration. Reference is made to United States Patent No. 3,148,293 issued September 8, 1964, in the names of James Byron Jones et al., entitled, Vibratory Device for Delivering Vibratory Energy at High Power, for details concerning construction and advantages of a coupler such as coupler 40.

The horn-type construction of system 38 is particularly suitable for application of relatively high levels of vibratory energy at a given frequency, and for avoiding undesirable modes of vibration in connection with both .die 12 is supported by a force-insensitive mount 52.

Such force-insentitive mount 52 may comprise a sleeve,

.one-half-wavelength long at the operating frequency and made from steel or other low hysteresis material such as nickel, aluminum bronze, beryllium-copper, or Monel. One end of the sleeve 52 is metallurgically joined to the coupler 40, preferably at an antinode or loop region of the vibration on the cylindrical portion of the latter, and the other end of the sleeve 52 is free from attachment. Sleeve 52 is provided with a radially outwardly extending flange 58 located one-quarter wavelength from its free end, and a true acoustical node will develop at the region of flange 58. Reference is made to United States Patents Nos. 2,891,178, 2,891,179, and 2,891,180 each of which issued in the name of William C. Elmore and is entitled, Support for Vibratory Devices.

Flange 58 is removably secured to a support 60 as by a clamping ring 61 and suitable bolts. Support 60 is rigidly secured to the draw bench 36.

The mount 52 in the drawing comprises a conical tubular member (a form which is not necessarily preferred').

' Acoustical coupler 40 and die 12, like support mount 52, are preferably made from K-Monel or other material having low hysteresis, good thermal conductivity, and high acoustical transmission efiiciency even when strained as much as 0.00l-inch per inch, for example, including such materials as aluminum-bronze or beryllium-copper. The materials named are non-magnetic and are known to the art for their relatively good acoustical power handling qualities. However, for drawing purposes the die 12 may be made of other materials, such as those chosen principally for suitability for the drawing operation per se rather than for their acoustical properties, provided that such change in material for the die is taken into consideration in connection with the design of the system for operation at a resonant frequency, as has been indicated to be preferable for purposes of the present invention.

In accordance with the present invention, there is provided a free-floating plug 16 having a forming end 18 and a free-floating end 20. Plug 16 may comprise a single member or ends 18 and 20 may be manufactured as separate members which may be fixedly connected (as by a metallurgical joint such as a brazed joint) or removably connected (as by cooperating threads).

It is to be noted that (unlike coupler 40, die 12, and mount 52, and unlike the floating plug in the above-identified application 321,041) the plug 16 is preferably made of a non-acoustically-optimum material. Thus, it may be and preferably is made of a material such as tungsten carbide, which is not only suitable for the drawing operation per se but is also particularly suitable for purposes of the present invention.

Thus, for purposes of appropriate acoustical behavior of the plug of the present invention, it is not desired to transmit acoustical energy from the end 18 of the plug 16 to the tube 30 and/or the die 12. Rather, it is desired that the plug 16 behave as an essentially noncompliant element acoustically in the region of actual material reduction (i.e., at the region of the plug 16 adjacent to the die 12). That region on the plug 16 will then present a high impedance to the transmission of vibratory motion in an axial direction; it will be an axial node, so to speak.

Thus, while I do not wish to be bound by any explanation or theory as to the mechanism of operation of the present invention, it appears that the free end 20 of plug 16 (when dimensioned as aforesaid) may behave as a loop or antinode, both by virtue of its freedom and its relationship to the nodal region from which vibration is transmitted back to it via the Poissons ratio effect, which effect causes end 20 to vibrate in phase with the vibration of the die 12. However, the primary concern of the present invention is in providing the aforesaid acoustically non-compliant behavior of the end 18 of the plug 16.

The aforesaid quarter-wave dimensioning of the plug 16 and its acoustically non-compliant behavior appears to serve to concentrate the vibratory energy in the area of material reduction where it is most useful, thus enhancing the tube drawing process without the direct addition of vibratory energy through the plug (such as the prior art has contemplated).

In operation, as shown in FIGURES 1 and 1A, the forming end 18 of the plug 16 extends into and through the orifice 14 and defines with the die 12 a restricted passageway through which the tube material 30 is drawn.

Plug 16 (like transducer-coupling system 38) is designed to operate at a given frequency, which as aforesaid is preferably a resonant frequency, namely, the design frequency of system 38 (such as the 28,000 cycles per second :above mentioned, for example). However, plug 16 is preferably dimensioned to have an over-all physical length equivalent to an acoustical length of an odd in tegral number of one-quarter wavelengths of sound in the material of which it is made at the said frequency. This is so that it will vibrate in the direction of the vibration system 38, and so as to have for efficient operation an acoustical node area of the vibration at the tube-contacting portion of the forming end 18 of plug 16, namely, juxtaposed to the die orifice 14. Also, in this embodiment, plug 16 will have each of its two ends 18 and 20 operating out of phase with one another, and end 18 being acoustically non-compliant with respect to longitudinal vibrations of the die 12.

It is to be noted that the shape of forming end 18 of die 12 may involve a slight adjustment in the aforesaid acoustical dimensioning requirements above indicated for plug 16, but this is within the skill of the art.

As is well known, the velocity of compressional waves in a medium varies according to the medium; the appropriate length of plug 16 may be found by use of the well known equation (wavelength=velocity/frequency) showing the relation among frequency, velocity, and wavelength of sound. Thus, if the plug 16 is to be made of tungsten carbide (such as a tungsten carbide comprising 87% tungsten and 13% cobalt), the pertinent characteristics of the tungsten carbide are ascertained (various tungsten carbides may have various values for Youngs modulus and density which will result in various velocities of sound), and the one-quarter wavelength dimension is calculated.

In this embodiment, the tungsten carbide had a modulus of 80 10 p.s.i. (=53.4 10 dynes/cm. a density of 14.15 gm./c-m. and a sound velocity of about 6150 meters/ sec. Therefore, a plug 16 having a length of one (1) one-quarter wavelength would have a physical length of 2.16 inches according to the equation for operation at 28 kc. With a small correction for the tapered end 18, the plug length could be about 2.25 inches for operation at that nominal frequency.-

It will be appreciated that, as in conventional drawing, various die angles and plug-end angles may be used. As yet these angles have not been shown to be critical as to use with the present invention, except as may concern the reduction desired to be obtained in a particular application.

In operation, tubing 30 is telescoped over the plug 16 (usually after tubing pre-treatment such as pickling, cleaning, and lubrication, although tubing pre-treatment may be minimized or eliminated in some instances and with some materials when the present invention is used). The plug 16 is so arranged that the plug forming end 18 floats in the proper position in the die orifice 14. The tubing 30, in accordance with standard practice, may be pointed, i.e., provided with a reduced outside diameter end portion, which may be accomplished in a variety of ways including swaging. Such reduced end portion is fed in the direction of arrow 90 through the die orifice 14. The jaws 64a and 64b of a pulling device 62 are clamped to the reduced end portion 32 of the tubing 30. Pulling device 62 is movably mounted on drawbench 36 for pullin the tubing 30 through the passageway defined by die 12 and forming end 18 of plug 16. The pulling device 62 is first actuated in the direction of arrow 90 to seat the forming end 18. That is, the tubing 30 is pulled in the direction of arrow 90 until the tubing 30 is locked between the die orifice 14 and the outer peripheral surface of the forming end 18 of plug 16.

The tubing 30 can be translated by the pulling means for a short distance, so that the plug will seat properly and drawing can be readily accomplished. However, the invention is not limited to any particular sequence of steps in pointing the tubing and/or seating the plug, although certain sequences may be far more favorable than others. As is readily evident, various lengths of tubing may be accommodated in accordance with the present invention, including very long lengths, as for example in continuous drawing.

After the forming end 18 of plug 16 is properly seated and positioned, and vibratory energy is applied to the system 38 including the die 12 (and by reason of its acoustical geometry to the plug 16), the pulling device 62 will move the jaws 64a and 64b in the direction of arrow 90. A wide variety of devices may, of course, be utilized to pull the jaws 64a and 64b, such as a hydraulic cylinder, a cable windup device, etc. It will be appreciated that the jaws 64a and 64b will be provided with means for selectively opening and closing the same, so that the reduced end portion of the tubing 30 may be inserted and gripped therebetween.

It will be appreciated that the power input to the transducers may be varied according to the operating conditions utilized, including the material being drawn and the conditions of draw (such as the reduction to be achieved, the drawing speed, and the drawing tension), and also according to the transducer-coupling system and plug employed.

The position of the forming end 18 of plug 16 relative to the die 12 and die orifice 14 is a determinant of the depth of draw, and a free-floating plug such as plug 16 is more susceptible to dislodgement (under either conventional or vibratory drawing conditions) than is a backsupported plug, for example.

The amount of power supplied and transmitted to the die area should not be suflicient to dislodge the forming end 18 of plug 16 from its location specified for drawing purposes. On the other hand, the power should be suflicient to accomplish the given reduction under a given set of operating conditions for a given material.

As is well known to those skilled in the art, power output (to the work) of acoustical vibration devices is not readily ascertainable directly, and indirect determination thereof often involves the use of liquids and other aspects not suitable for ready adjustment to differing industrial applications. Moreover, permissible power input is variable according to the transducer utilized and the acoustical coupler geometries and materials used, as well as such factors as the efliciencies of joints between the various members of the transducer-coupling system. For example, a magneto-strictive transducer is far more rugged and trouble-free than the ceramic transducers which have been in commercial use, but it has a lesser efiiciency in converting electrical power into mechanical vibration. Also, steel is a more readily machinable and joinable coupler material than Monel or beryllium-copper, but it has a lesser acoustical transmission efficiency. The implications are obvious for differing amounts of acoustic power (expressed in electrical watts output from the power supply or input to the transducer) used with various equipments, even without taking a given drawing operation into consideration.

A lubricant may be applied to the inner and/ or outer surfaces of the tubing 30 by means well known in the art. Such lubricants and lubrication are well known to the art, and they do not form a part of the present invention, except to the extent that the present invention (with some materials and undersome conditions of draw) enables elimination or minimization of lubrication, including a lessening of criticality concerning the use of a special lubricant for a given material.

For example, in one example of utilization of the present invention, successful drawing was obtained of an ironnickel alloy tubing which could not be successfully drawn without vibratory energy as provided by the present inlention. However, a careful choice of tube lubricant was necessary if tube failures were to be reproducibly avoided.

In another example, also using the tungsten carbide plug with the above single one-quarter wavelength dimensions, successful drawing at 75 feet per minute was obtained (at a 40% area reduction) of copper tubing having a diameter of 0.093-inch and a wall thickness of 0.0062-inch before the vibratory drawing. This reduction could not be made without the present invention, not even with the invention of the aforementioned Serial No. 321,041, now Patent No. 3,209,574.

US. patent application Serial No. 289,559 filed June 21, 1963, in the names of Charles A. Boyd et al., entitled, Vibratory Energy Method and Apparatus, now Patent No. 3,209,572, has been found useful in connection with initial seating of the plug of the present invention and subsequent approach to the ultimately used vibratory drawing conditions. Thus, drawing may be initiated at a very low electrical input to the transducer to permit plug seating (drawing speed 37.5 feet per minute) and then power may be increased to the operating'level as drawing speed is increased to the above-indicated 75 feet per minute for the application specified.

Other advantages of the present invention in some applications may include the providing of optimum material plasticity with resultant optimum drawing tension reduction, decreased chattering tendencies, increased drawing speed, and greater material reductions per pass than are obtainable in conventional free-floating plug drawing.

In view of the free-floating end 20 of plug 16s being acoustically free at its outer end (i.e., delivering no vibratory energy in view of the acoustical impedance mismatch with air), the nodal region(s) at odd whole number multiples of one-quarter-wavelength from said end 20s outer end are true acoustical nodes, which is a condition nonaachievable as a practical matter, so far as is known, in a transducer-coupling system under power delivery conditions.

For efiicient operation, the pulling device 62 (including the jaws 64a and 64b) should not resonate in any mode at the frequency of operation.

Although the invention is shown and described in connection with the drawing of tubes, it is to be understood that the invention is applicable generally to the drawing of elongated articles having wall structure formed at least partly about a longitudinal axis thereof.

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 description as indicating the scope of the invention.

I claim:

1. Vibratory tube drawing apparatus comprising a die having an orifice therein, a vibratory generator coupled to said die, means on one side of said die for pulling tubing in an axial direction through said orifice, a free-floating plug partially disposed in said orifice, said plug having a physical length corresponding to an acoustical length of an odd integral number of one-quarter wavelengths of sound in the material of which it is made at the frequency of said vibratory generator, said plug having one end thereof in said orifice and a second end thereof on the side of said die opposite from said pulling means, said plug being acoustically non-compliant at said one end.

2. Apparatus for drawing elongated articles wherein said articles have wall structure formed at least partly about a longitudinal axis thereof, said apparatus comprising a die having an orifice therein, a free-floating plug extending at least partially into said orifice from one side of said die and defining with said die a restricted passageway for an article to be drawn, means associated with said die on the side thereof opposite said plug for pulling an article through said passageway, a vibratory generator including a transducer and an acoustical coupler coupled to said die, said transducer and coupler being arranged so as to vibrate in an axial direction so that a vibratory antinode occurs in said die, said plug having a length equal to an odd integral number of one-quarter Wavelengths of sound in the material of which it is made at the frequency of said vibratory generator, the portion of said plug which cooperates with said die to form said passageway being a vibratory node on said plug.

3. A method of drawing tubes comprising the steps of providing an acoustically non-compliant free-floating plug, telescoping a tube around the plug, feeding a reduced diameter portion of said tube to a die, seating a vibratory node on said plug against the portion of said tube juxtaposed to the orifice of said die, coupling vibratory energy to said die, inducing vibrations in said plug out of phase with vibrations of said die, and pulling said reduced diameter portion of said tube in an axial direction away from said die to reduce the cross sectional area of said tube as it passes through said die.

4. The method of claim 3 wherein the step of providing a plug includes providing a plug having a length equal to an odd integral number of one-quarter wavelengths of sound in the material of which it is made at the frequency of the vibratory energy applied to said die.

References Cited by the Examiner UNITED STATES PATENTS 2,891,180 6/1959 Elmore 31026 3,002,614 10/1961 Jones 72253 3,203,215 8/1965 Jones 72-253 3,209,574 10/1965 Boyd 72-283 FOREIGN PATENTS 955,943 1/1957 Germany.

CHARLES W. LANHAM, Primary Examiner.

H. D. HOINKES, Assistant Examiner.

Claims (1)

1. VIBRATORY TUBE DRAWING APPARATUS COMPRISING A DIE HAVING AN ORIFICE THEREIN, A VIBRATORY GENERATOR COUPLED TO SAID DIE, MEANS ON ONE SIDE OF SAID DIE FOR PULLING TUBING IN AN AXIAL DIRECTION THROUGH SAID ORIFICE, A FREE-FLOATING PLUG PARTIALLY DISPOSED IN SAID ORIFICE, SAID PLUG HAVING A PHYSICAL LENGTH CORRESPONDING TO AN ACOUSTICAL LENGTH OF AN ODD INTEGRAL NUMBER OF ONE-QUARTER WAVELENGTHS OF SOUND IN THE MATERIAL OF WHICH IT IS MADE AT THE FREQUENCY OF SAID VIBRATORY GENERATOR, SAID PLUG HAVING ONE END THEREOF IN SAID ORIFICE AND A SECOND END THEREOF ON THE SIDE OF SAID DIE OPPOSITE FROM SAID PULLING MEANS, SAID PLUG BEING ACOUSTICALLY NON-COMPLIANT AT SAID ONE END.

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