Machine for forming seams of two-piece paper cups

In a machine for making cups of thermoplastic coated paper, each comprising a side wall blank and a disc-like bottom wall blank that has its margin formed as a circumferential axially projecting flange portion, said machine comprising a mandrel around which a side wall blank is rolled and which has at an outer end thereof a flat outwardly facing surface against which a bottom wall blank is held with its flange portion projecting outwardly and surrounded by a bottom portion of the rolled side wall blank, heating means for melting coating on said portions of the blanks to provide for their adhesion to one another, said heating means comprising:

• A. a stationary air duct with which the mandrel can have coaxial alignment and which has a rear end remote from the mandrel wherein there is an air inlet;
• B. an electric heater in said air duct for heating air that flows forwardly therethrough from said inlet;
• C. a hollow nozzle body into which said air duct opens forwardly and which is axially slidable on the front end portion of said air duct between a forward operative position and a rearward inoperative position, the front end portion of said nozzle body
• (1) having an outside diameter to be closely coaxially receivable within the bottom portion of a rolled side wall blank on the mandrel and
• (2) having circumferentially spaced air outlets that open radially outwardly from its interior;
• and
• D. said nozzle body and said air duct having cooperating throttling portions which restrict flow of air from the air duct to said air outlets when the nozzle body is in its inoperative position and which permit substantially unrestricted flow of air from said air duct to said outlets when the nozzle body is in its operative position.

In a machine for making cups of thermo-plastic coated paper, each comprising a side wall blank and a disc-like bottom wall blank that has its margin formed as a circumferential axially projecting flange portion, said machine comprising a mandrel around which a side wall blank is rolled and which has at an outer end thereof a flat outwardly facing surface against which a bottom wall blank is held with its flange portion surrounded by a bottom portion of the rolled side wall blank, heating means for melting coating on said portions of the blanks to provide for their adhesion to one another, said heating means comprising:

• A. an air duct with which the mandrel can have coaxial alignment and which has a front end proximal to said outer end of the mandrel;
• B. means for delivering heated air through said air duct to the front end portion thereof;
• C. a hollow nozzle body at the front of said air duct into which said air duct opens forwardly, said nozzle body being movable between a forward operative position and a rearward inoperative position, the front end portion of said nozzle body
• (1) having an outside diameter to be closely coaxially receivable within the bottom portion of a rolled side wall blank on the mandrel and
• (2) having circumferentially spaced air outlets that open radially outwardly from its interior;
• D. a heat shield comprising a tubular wall surrounding the front end portion of said nozzle body in radially spaced substantially concentric relation thereto and defining therewith an annular passage through which hot air issuing from said outlets is deflected rearwardly along said nozzle body;
• E. said heat shield having a substantially reflective radially inner surface whereby heat of air flowing through said annular passage tends to be radiated to said nozzle body;
• and
• F. said nozzle body having a dull radially outer surface so that it tends to absorb heat of air flowing through said annular passage.

In a machine for making cups of thermoplastic coated paper, each comprising a side wall blank and a disc-like bottom wall blank that has its margin formed as a circumferential axially projecting flange portion, said machine comprising a mandrel around which a side wall blank is rolled and which has at an outer end thereof a flat outwardly facing surface against which a bottom wall blank is held with its flange portion surrounded by a bottom portion of the rolled side wall blank, heating means for melting coating on said portions of the blanks to provide for their adhesion to one another, said heating means comprising:

• A. an air duct with which the mandrel can have coaxial alignment and which has a front end proximal to said outer end of the mandrel;
• B. means for delivering heated air through said air duct to the front end portion thereof;
• C. a hollow nozzle body at the front of said air duct into which said air duct opens forwardly, said nozzle body being movable between a forward operative position and a rearward inoperative position, the front end portion of said nozzle body
• (1) having an outside diameter to be closely coaxially receivable within the bottom portion of a rolled side wall blank on the mandrel and
• (2) having circumferentially spaced air outlets that open radially outwardly from its interior;
• D. a heat shield comprising a substantially thick tubular wall surrounding the front end portion of said nozzle body in radially spaced substantially concentric relation thereto and defining therewith an annular passage through which air issuing from said outlets is deflected rearwardly along said nozzle body;
• E. said tubular wall having circumferentially spaced axially extending bores therein which
• (1) open to the front end of said tubular wall,
• (2) are communicated near their rear ends with said annular passage, to provide for forward flow through the bores of heated air that has flowed rearwardly through said annular passage, and
• (3) are also communicated near their rear ends with bore outlets through which heated air can pass out of the heat shield;
• and
• F. means for adjustably restricting said bore outlets to control the relative proportions of heated air that are discharged through said bore outlets and flow forwardly through said bores.