Abstract: An ultrasonic processing method is disclosed wherein during the processing time interval the motional amplitude and engaging force of the resonating horn and thereby the power and engaging pressure to the workpiece is varied to improve weld strength and decrease weld cycle time. The variation in motional amplitude and engaging force may be in response to a process condition such as a change in dimensions of the workpiece, a sharp rise in the transducer power curve, or in response to the lapse of a predetermined time interval.

Abstract: A method of welding two thermoplastic workpieces (W) together along a predetermined weld line during a weld cycle utilizing a high frequency vibration sonic or ultrasonic welding apparatus. This welding apparatus includes an electroacoustic transducer (18) which transmits such vibrations to a horn (19) which is dimensioned to be resonant with the horn being brought into forced engagement with at least one of the workpieces to be welded. The method comprising the steps of bringing the workpieces into bearing relation against one another along the weld line. Then the electroacoustic transducer is energized so as to resonate the horn with a desired motional amplitude. Forceful contact is established between the horn and one of the workpieces. Then, the forceful contact between the horn and the one workpiece is maintained throughout the weld cycle. The motional amplitude of the horn is varied in accordance with a desired motional amplitude profile.

Abstract: In an ultrasonic apparatus a plurality of piezoelectric electroacoustic transducers (10, 12) are mechanically coupled to a horn (14) for providing ultrasonic vibrations thereto, and the transducers are energized in parallel from a common electrical power supply (28). In order to avoid the presence of circulating currents among the transducers, transformer balancing units (30) are connected in circuit with each of the transducers. Since the use of parallel connected piezoelectric transducers increases the total circuit capacitance, series connected capacitors (32, 34) are provided to restore the circuit capacitance to a value required for the resonant circuit condition.

Abstract: For accurately determining, in real time, the collapse of a thermoplastic workpiece processed in a press, such as an ultrasonic welding apparatus or a vibration welding apparatus, a two-phase method is used. In the calibration phase signals are generated which are responsive to the yielding or displacement of the movable press portion relative to the substantially stationary portion arising from forced engagement of the workpiece within the press. The force responsive displacement value is stored.In the subsequent workpiece processing phase, when the workpiece collapses due to the softening and flowing of thermoplastic material as the workpiece is coupled to vibrations, the previously stored force responsive displacement value is recalled as a correction signal and subtracted from the newly obtained displacement signal related to the same force. The result of the subtraction is a true on-line signal indicative of the collapse of the workpiece as it occurs.

Abstract: An ultrasonic power supply for driving piezoelectric transducers in an ultrasonic cleaning apparatus comprises a full-wave rectifier for providing unfiltered direct current to an inverter circuit of the clamped mode resonant converter type, which provides alternating current output at the series resonant frequency condition of the transducers. The inverter circuit switching cycle is controlled responsive to means for causing a set average power level to be maintained, means for causing the resonant frequency to be maintained and including means for causing the resonant frequency to be swept symmetrically by an adjustable sweep frequency. Also, power modulation means are provided for optionally providing to the transducers power bursts of a set amplitude, but at the set average power level. As a result of the unfiltered direct current from the full-wave rectifier, the power supply will operate substantially at unity power factor.

Abstract: An expert system for a welding machine has an installed knowledge base concerning weld problems and preferred solutions. Trial welds are made from which input data concerning weld quality is obtained. The expert system applies predetermined rules and historic confidence levels to determine changes in weld parameters to attempt to correct any weld defects.

Abstract: A method of welding two thermoplastic workpieces (W) together along a predetermined weld line during a weld cycle utilizing a high frequency vibration sonic or ultrasonic welding apparatus. This welding apparatus includes an electroacoustic transducer (18) which transmits such vibrations to a horn (19) which is dimensioned to be resonant with the horn being brought into forced engagement with at least one of the workpieces to be welded. The method comprising the steps of bringing the workpieces into bearing relation against one another along the weld line. Then the electroacoustic transducer is energized so as to resonate the horn with a desired motional amplitude. Forceful contact is established between the horn and one of the workpieces. Then, the forceful contact between the horn and the one workpiece is maintained throughout the weld cycle. The motional amplitude of the horn is varied in accordance with a desired motional amplitude profile.

Abstract: A mount for a vibratory member, such as an elongate half wavelength resonator, includes a pair of cylindrical flexural tubes, each tube coupled with one end to the nodal region of the member and the other end of each tube coupled to a stationary member. The axial length and the thickness of the tubes are selected to enable the tubes to flex radially responsive to the substantially radial vibrations manifest at the nodal region of the member so as to decouple the vibrations of the member from the stationary member. A method of decoupling a vibration member from its stationary mount is also described.

Abstract: A vapor degreasing apparatus includes a heated surface which is heated to a temperature above the boiling point temperature of the solvent used, but below the breakdown temperature of the solvent. The surface is disposed in the solvent vapor area provided above the customary immersion sump containing solvent in its liquid state. After a workpiece has been immersed and cleaned in the liquid solvent, the workpiece is exposed to the heated surface for becoming heated to a temperature which is above the boiling point of the solvent, thereby causing liquid solvent adhering to surfaces of the workpiece to be vaporized and enter the surrounding vapor atmosphere. As the workpiece subsequently is withdrawn from the apparatus, no further solvent adheres to the workpiece and it enters the ambient atmosphere free of any solvent. The apparatus, therefore, provides for substantially zero vapor contamination of the ambient atmosphere.

Abstract: A flexural spring support for a vibratory apparatus comprises a substantially stationary first member, a second member disposed opposite and spaced from said first member and intended to undergo translating motion in a plane, and a plurality of elongated flexural springs coupling said members to one another. Each spring is provided at its ends with a respective flange, the underside of which is in forced engagement with the surface of the associated member. Adjustable fastening means cause the engagement pressure to be of such magnitude as to prevent relative motion between the flange and member surface when said first member undergoes motion, thereby substantially eliminating fretting corrosion previously manifest at the springs. In addition, each spring is configured to form a clamped clamped constant strain tapered beam.

Abstract: Carpeted panels comprising a thermoplastic substrate and a synthetic fiber carpet are produced by bonding the respective pads to one another using a vibration welding apparatus for causing the generation of frictional heat at the interface between the substrate and the carpet. One of the platen of the welding apparatus confronting the carpet is provided with a pattern of closely spaced pins engaging the carpet and urging the carpet into forced engagement with the substrate. On account of the closely spaced pins and the relatively low amplitude of the reciprocating motion, a bond is achieved substantially over the entire interface between the carpet and the substrate.

Abstract: A flexural spring support for a vibratory apparatus comprises a unitary metal body which includes a substantially stationary member, an oppositely disposed spaced member intended to move in a plane, and a plurality of flexural spring beams coupling the members to one another. Each flexural spring beam is constructed as a substantially constant strain tapered beam.

Abstract: Mounting means for a vibratory member, such as an elongate half wavelength resonator, include a pair of cylindrical tubes, each tube coupled with one end to the nodal region of the member and the other end of each tube coupled to a stationary clamping means disposed about the member. The axial length and the thickness of the tubes are selected to enable the tubes to flex radially responsive to the substantially radial vibrations manifest at the nodal region of the member, whereby to decouple the vibrations of the member from the stationary clamping means.

Abstract: An ultrasonic processing method is disclosed wherein during the processing time interval the motional amplitude of the resonating horn and thereby the power to the workpiece is reduced. The reduction in motional amplitude may be in response to a process condition such as a change in dimension of the workpiece or a sharp rise in the power curve, or it may be in response to the lapse of a predetermined time.

Abstract: A method of providing an assembly of thermoplastic parts, which are separable upon the application of a predetermined force, includes assembling at least two thermoplastic parts in an overlapping relation and using an ultrasonically resonant horn for cutting a plug from the wall thickness of the first part and welding the plug to the underlying second part, whereby the upper portion of the plug remains surrounded by the wall of the aperture produced responsive to the cutting of the plug. Responsive to the application of a predetermined breakaway force effective on the plug, the plug breaks away from its attachment to the second part, causing the parts to become separable. The cross-sectional area of the plug is selected to meet a predetermined breakaway force requirement.

Abstract: A method and apparatus are disclosed for joining a plurality of tubular thermoplastic workpieces by causing the workpieces to be stacked with their internal surfaces axially aligned. High frequency vibrations are applied to the respective inner surfaces of the stacked workpieces, the motion of the vibrations being predominantly along the axial alignment of the workpieces. Responsive to the dissipation of the vibratory energy, thermoplastic material from the inner surfaces of the workpieces becomes molten and flows and, upon the cessation of the vibrations, the molten and flowed material rigidifies to cause the workpieces to be joined. The high frequency vibrations, most suitably, are provided by a horn adapted to be resonant as a half wavelength resonator at an ultrasonic frequency in the range between 16 and 25 kHz.

Abstract: A horn for coupling high frequency vibrations from an electroacoustic converter unit to a workpiece, such as is used for welding thermoplastic workpieces by ultrasonic vibrations, is constructed by machining sections of the horn and welding the sections together using electron beam welding or laser beam welding. The respective sections can be made from bar or plate stock.This construction eliminates the machining of deep, inaccessible slots, and as most of the surfaces to be machined are accessible, a fine surface finish can be provided, thus eliminating tool marks which cause the existence of areas of high mechanical stress concentrations when the horn is rendered resonant. Also significant economic advantages are achieved when manufacturing large, massive slotted horns in this manner.

Abstract: In a vapor degreasing apparatus solvent vapor provided by a boiling sump is subjected to further heating for producing superheated solvent vapor to which a workpiece in the process of being cleaned is exposed. The superheated solvent vapor raises the temperature of the workpiece in order to minimize solvent adhering to the workpiece surface as the workpiece is removed from the apparatus to ambient. Further heating is achieved by heating means interposed in the natural convection flow path of the solvent vapor provided by a boiling sump to a vapor zone area in the degreasing apparatus.

Abstract: A method and apparatus for cleaning printed electrical circuit boards having surface mount components by ultrasonic energy in the frequency range between 300 kHz and 1.0 MHz. The ultrasonic energy is produced by an array of piezoelectric wafers mounted to the inside surface of an immersible transducer assembly which, in turn, is disposed in a tank accommodating a bath of cleaning liquid. The ultrasonic energy provided by the transducer assembly and the circuit board to be cleaned are disposed to cause the ultrasonic wave beam to be incident upon a board to be cleaned at an angle of 90.+-.60 degrees relative to the surface plane of the board. This arrangement will remove solder flux residue and other contaminants from spaces ranging from 0.001 to 0.010 inch present underneath a surface mount component.

Abstract: Carpeted panels comprising a thermoplastic substrate and a synthetic fiber carpet are produced by bonding the respective parts to one another using a vibration welding apparatus for causing the generation of frictional heat at the interface between the substrate and the carpet. One of the platen of the welding apparatus confronting the carpet is provided with a pattern of closely spaced pins engaging the carpet and urging the carpet into forced engagement with the substrate. On account of the closely spaced pins and the relatively low amplitude of the reciprocating motion, a bond is achieved substantially over the entire interface between the carpet and the substrate.