Apparatus for ultrasonic sealing of non-uniform folded carton bottom closure

Apparatus for use with a bottom closure folding machine for sealing cartons composed of foldable thermoplastic double coated material such as polyethylene double coated paperboard comprising:

• a sealing horn for ultrasonically sealing the carton, said sealing horn having a cylindrical body portion surmounted by a substantially cubical head having a rectangular face with a recessed portion and a knurled raised portion;
• a mandrel pad having a rectangular cross-section for forcibly engaging said sealing horn, said mandrel pad having primary and secondary surfaces separated by walls, said primary surfaces lying in first and second parallel planes, said secondary surfaces lying in third and fourth parallel planes, certain of said primary surfaces defining air grooves through which air is allowed to pass to cavities formed between the carton bottom closure and said mandrel pad during removal of the sealed carton from the mandrel pad after sealing;
• vibrator means connected to said sealing horn for vibrating said sealing horn at ultrasonic frequencies for a predetermined interval of time during the forcible engagement of said sealing horn and said mandrel pad enshrouded by the folded carton to create an ultrasonic seal over the area defined by the raised portion of said rectangular face of said sealing horn;
• drive means for urging said sealing horn and said mandrel pad into forcible engagement during the sealing process.

Apparatus for use with a bottom closure folding machine for sealing cartons composed of foldable thermoplastic double coated material such as polyethylene double coated paperboard comprising:

• a sealing horn having a body portion surmounted by a head having a face with a recessed portion and a knurled raised portion, said knurled raised portion comprising a series of segments and legs whose center lines lie substantially coincident during sealing with certain of the folded edges and overlaping portions of the carton bottom closure after folding;
• a mandrel pad having a body portion surmounted by a face for forcibly engaging said sealing horn during sealing, said face having a multiplicity of recesses corresponding substantially to the contour of the inner surface of the carton bottom closure after folding, said multiplicity of recesses for receiving and engaging portions of the folded bottom closure tabs and panels of varying thicknesses thereby leaving exposed for forcible engagement with said sealing horn a surface which can be pressed into a substantially flat position by the forcible engagement of said sealing horn and said mandrel pad;
• vibrator means for ultrasonically vibrating said sealing horn to cause the thermoplastic coatings of adjoining sections of the carton bottom closure held in compression by the forcible engagement of said sealing horn and said mandrel pad to combine to form an ultrasonic seal;
• drive means for urging said sealing horn and said mandrel pad into forcible engagement after said vibrator means initiates ultrasonic vibrating of said sealing horn and holding said sealing horn and said mandrel pad in forcible engagement for a period of time after said vibrator means has ceased vibrating said sealing horn.

Apparatus for use with a bottom closure folding machine for sealing thermoplastic double coated cartons such as polyethylene double coated paperboard cartons wherein a mandrel pad is inserted into the carton blank during the folding and sealing of the carton and said mandrel pad, enshrouded by said folded carton, is urged into forcible engagement with a sealing horn during the final sealing steps, comprising:

• a mandrel pad having a body portion surmounted by a face portion, said face portion having first, second, third and fourth planar surfaces, said first planar surface having two co-planar constituents, the first constituent defining a trapezoidal plane and the second constituent defining an irregular pentagonal plane, said second planar surface having two co-planar constituents, the first defining a triangular plane and the second constituent defining an irregular hexagonal plane, said third planar surface having four co-planar triangular constituents and said fourth planar surface having two co-planar constituents, the first constituent defining an irregular heptagonal plane and the second constituent defining an irregular pentagonal plane;
• a sealing horn having a body portion and a face with a raised portion and a recessed portion, said raised portion comprising a series of segments and legs whose shape substantially coincides with the pattern formed by the edges of said first, second, third and fourth planar surfaces and a portion of the surface of said second constituent of said second planar surface and a portion of the surface of the first and second constituents of said fourth planar surface;
• an ultrasonic vibrator for creating ultrasonic vibration which is imparted to portions of the carton bottom closure;
• a drive means for urging said mandrel pad and said sealing horn together during sealing.

Apparatus for use with a bottom closure folding machine for sealing cartons composed of foldable thermoplastic double coated material such as polyethylene double coated paperboard comprising:

• a sealing horn having a cylindrical body portion surmounted by a cubical head portion having a face with a recessed portion and a knurled raised portion, said knurled raised portion comprising a series of segments and legs whose center lines lie substantially coincident during sealing with certain of the folded edges and overlapping portions of the carton bottom closure after folding;
• a mandrel pad having a body portion with a rectangular cross section surmounted by a rectangular face, said mandrel pad for forcibly engaging said sealing horn during sealing, said rectangular face having a multiplicity of recesses corresponding substantially to the contour of the inner surface of the carton bottom closure after folding, said multiplicity of recesses comprising first, second, third and fourth planar surfaces, said first planar surface having two co-planar constituents, the first constituent defining a trapezoidal plane and the second constituent defining irregular pentagonal plane, said second planar surface having two co-planar constituents, the first constituent defining a triangular plane and the second constituent defining an irregular hexagonal plane, said third planar surface having four co-planar triangular shaped constituents and said fourth planar surface having two co-planar constituents, the first constituent defining an irregular heptagonal plane and the second constituent defining an irregular pentagonal plane, said first, second, third and fourth planar surfaces lying parallel with one another such that adjacent planar surfaces are separated by an intergral multiple of a distance slightly less than the thickness of the material of which the thermoplastic double coated carton is composed, said multiplicity of recesses for receiving and engaging portions of the folded bottom closure tabs and panels of varying thicknesses thereby leaving exposed for forcible engagement with said sealing horn knurled raised portion a surface which can be pressed into a substantially flat position by the forcible engagement of said sealing horn raised portion and said mandrel pad such that a uniform force is exerted on the carton bottom closure throughout the area defined by the knurled raised portion of the face of said sealing horn;
• vibratory means for ultrasonically vibrating said sealing horn to cause the thermoplastic coatings of adjoining sections of tabs and panels of the carton bottom closure lying between the knurled raised portion of said sealing horn and said multiplicity of recesses of said mandrel pad to combine to form an ultrasonic seal;
• drive means for urging said sealing horn and said mandrel pad into forcible engagement after said vibrator means initiates ultrasonic vibrating of said sealing horn and holding said sealing horn and said mandrel pad in forcible engagement after said vibrator means has ceased vibrating said sealing horn for a period of time sufficient to permit the thermoplastic coatings combined in the ultrasonic sealing process to assume their rigid state.

A method for ultrasonically sealing a prescored thermoplastic double coated container such as a polyethylene double coated paperboard carton comprising the steps of:

• a. sliding the carton blank over a mandrel pad having a circumpheral shape substantially conforming to the interior wall shape of the carton to be sealed thereby shaping the carton;
• b. crimping the carton closure to cause said carton to fold slightly along major score lines;
• c. folding the carton closure to substantially its final closed position;
• d. forcing portions of the interior surface of the folded carton closure into a multiplicity of planar recesses in said mandrel pad;
• e. causing a sealing horn with a face having a raised portion and a recessed portion to vibrate ultrasonically;
• f. pressing the folded carton closure between said mandrel pad and the raised portion of an ultrasonically vibrating sealing horn thereby softening the thermoplastic double coating of the carton material over the specific contact area defined by the raised portion of the sealing horn;
• g. forcing the softened surfaces of adjoining laminates of the folded carton closure together causing the thermoplastic coatings of portions of adjoining tabs and panels to unite;
• h. stopping the ultrasonic vibration of said sealing horn;
• i. holding the folded carton closure in compression with portions of the folded carton closure within said multiplicity of surfaces of said mandrel pad until said softened thermoplastic coatings assume their hardened state;
• j. removing the sealed carton from said mandrel pad.