US2949121A - Cleaning apparatus - Google Patents

Description

Aug. 16, 1960 T. J, KEARNEY CLEANING APPARATUS Filed Oct. 3, 1956 FIG Z mmvron. mama s1 Heap/leg PMR' a P A TTORNEYS United States atentO CLEANING APPARATUS Thomas J. Kearney, Detroit, Mich., assignor to Detrex Chemical Industries, Inc., Detroit, Mich., a corporation of Michigan Filed Oct. 3, 1956, Sela-No.- 613,657 1 Claim. 01. 134-120 This invention relates to apparatus for treating a work object. More particularly it is concerned with apparatus for cleaning and degreasing of intricately formed metal parts by application of chlorinated hydrocarbon solvents and ultrasonic energy. Reference is hereby made to my co-pending application Serial No. 438,429, filed June 22, 1954, now Patent No. 2,831,785, of which this applica tion is a continuation-in-part.

Finely machined parts which have been bufied, lapped or ground, as for example, heads for electric razors, hypodermic needles, deep drilled metal parts and the like, are very difficult to clean and previous methods and apparatus as ordinarily constructed did not accomplish the complete removal of grease and adhering dirt or soil" from the hollows or interstices of intricately machined parts.

The generation of ultrasonic vibrations in a bath of liquid solvent has presented some difficulty. Previously compression waves have been produced from fiat piezoelectric or magnetostrictive devices and standing waves have been formed. Non-uniform washing is sometimes obtained. It is thought that standing waves produced between the source of the ultrasonic energy and the surface of the liquid solvent are the cause of alternate soiled and unsoiled strips on the work object being cleaned, the distance between strips being approximately equal to one-half the wave length of the ultrasonic wave energy being used.

United States Patent No. 2,650,872, to Goldwasser discloses a method and apparatus for eliminating the alternate soiled and unsoiled strip effect. Although devices of the character illustrated in the Goldwasser patent are entirely adequate for their intended service, the present invention performs more efiiciently and is less complicated, being based on a new and entirely different principle.

Accordingly, the object of the present invention is to provide a new and improved apparatus for cleaning and degreasing with ultrasonic energy in a liquid solvent.

It is another object of this invention to overcome the disadvantages of flat transducers heretofore mentioned. Another object is to obtain satisfactory cleaning results from beams of parallel ultrasonic waves.

Further features and objects of the invention, as well as the details of a typical and preferred embodiment thereof, will be understood from the detailed description to follow, throughout which reference is made to the accompanying drawings wherein:

Fig. 1 represents a view in side elevation of cleaning apparatus constructed in accordance with the invention; and

Fig. 2 represents a view of the liquid in the well of Fig. 1 with the apparatus operating.

Turning now to the drawings, the apparatus comprises a housing 11 which, in practice, is constructed of sheet metal. Located within the housing 11 is a well 12 which includes an overflow dam 13. Well 12 contains a chlo- '2, rinated hydrocarbon liquid solvent which will .rise no higher in the well than the level defined by overflow dam 13'which permits the liquid to overflow into well 14. Well 12 is provided at the bottom with pipe coil 15 through which either water or steam is circulated as may be required to maintain the liquid in said well at the temperature desired.

A pair of supporting angles 16 are fixed to the side of housing 11 and extend horizontally into the well 12 below the surface of the liquid.

A doublechain conveyor 19has a work carrier 20 depending from a cross rod 21. A work object 22 to be cleaned is positioned on work carrier 20, and con veyor 19 operates to transport work object 22 around sprocket wheels 23, 24 and 25-, immersing'the work object 22 in the liquid of well. 12. Work object 22 follows a substantially horizontal path through the liquid parallel to the liquid surface.

An ultrasonic wave emittingv device designated generally by the number 31 is positioned beneath the surface of the liquid in well 12, and" a similar ultrasonic'wave emitting device 32 is spaced horizontally away from device 31. The upper portion of emitting device 31 is provided with a flat emitting surface 33 which is positioned at an angle of 30 from the horizontal. Similarly, emitting device 32 is provided with a flat emitting surface 34 which is also positioned at an angle of 30 from the horizontal.

As is shown in Fig. 2, emitting device 31 produces a beam 35 of substantially parallel ultrasonic waves that are normal to flat emitting surface 33, and emitting device 32 produces a like beam 36 that is normal to fiat emitting surface 34. The emitting surfaces 33, 34 are canted at an angle of 30 to the horizontal for the purpose of converging beams 35, 36 to form an overlapping, ultrasonic wave zone 37 having a peak concentration of ultrasonic energy of high intensity. It is through this high intensity energy zone 37 that work object 22 is passed to be cleaned. It is to be understood that any number of ultrasonic wave emitting devices can be used from any position within the well 12, and the beams produced directed toward this overlapping zone 3'].

According to the present invention, the work object is immersed in a bath of chlorinated hydrocarbon liquid solvent. This solvent is preferably trichlorethylene. Perchlorethylene and methylene chloride have been used and have given satisfactory results. While immersed in the bath, ultrasonic waves in the range of about 20 to 1000 kilocycles are generated in the liquid which are focused and directed toward the work object, striking the work object while the ultrasonic waves are diverging.

The work object is transported across the ultra sonic waves in a substantially horizontal path below the surface of the liquid.

The following specific examples serve to illustrate the process of the invention:

Example 1 The work object is immersed in a bath of trichlorethylene at a temperature in the range of about to F. and subjected to ultrasonic waves of a frequency of about 400 kilocycles.

Example 2 The work object is immersed in a bath of perchlorethyb ene at a temperature in the range of about 140 to F. and subjected to ultrasonic waves of a frequency of about 400 kilocycles.

Example 3 The work object is immersed in a bath of methylene chloride at a temperature in the range of about 58 to 78 F. and subjected to ultrasoniciwaves of a frequency of about 400 kilocycles.

While the specific embodiment of the invention described herein has been confined to the cleaning or degreasing .of a work object by contact with a chlorinated hydrocarbon solvent, it will be appreciated that the invention can be used to aocomplishavarietyof objects and is not limited to cleaning or degreasing. For example, the invention has application in the field of plating where the work object is immersed in aliquid and the ultrasonic vibrations induce an even coating to cover the work object. Further, the Work object may be pre-dipped before being subjected to the invention. 7

It is to be understood that the form of the invention herein shown and described is to be taken as a preferred embodiment. Various changes may be made in the shape, size and arrangement of parts. Equivalent elements may be substituted for those described .herein, parts may be reversed, and certain features of the invention may be utilized independently .of the use of other features, all without departing from the spirit of the invention or the scope of the subjoined claims.

Having thus described my invention, I claim:

Apparatus for degreasing a work object comprising a well being adapted to contain a chlorinated hydrocarbon liquid, transducer means including a pair of spaced apart transducers mounted below the surface of said liquid for emitting ultrasonic waves, each of said transducers having a flat emitting surface from which said ultrasonic waves are emitted in a direction normal to said emitting surface, said transducer means having said emitting surfaces inclined toward each other at an angle of 30 degrees to the horizontal so that the ultrasonic waves from one overlap the ultrasonic waves from the other to create a non-uniform sound field including a wave overlapping zone of higher intensity and a non-overlapping zone of lower intensity, and means for carrying the work object through said overlapping zone so that every part of the work object is bombarded by the waves of said overlapping zone.

Refereuces Cited in the file of this patent UNITED STATES PATENTS

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