Method and apparatus for spin welding container closures

• US 6,296,726 B1
• Filed: 06/13/2000
• Issued: 10/02/2001
• Est. Priority Date: 06/13/2000
• Status: Expired due to Term

• Current Assignee: Silgan Containers Corporation (Silgan Holdings Incorporated)
• Original Assignee: Silgan Containers Corporation (Silgan Holdings Incorporated)
• Inventors: Pencak, John
• Primary Examiner(s): SELLS, JAMES D
• Application Number:
  US09/593,064
• Time in Patent Office: 476 Days
• Field of Search: 156/64, 156/69, 156/73.5, 156/292, 156/580, 533/34, 534/85
• US Class Current: 156/64
• CPC Class Codes: B29C 65/0672 Spin welding
• CPC Class Codes: B29C 65/7841 Holding or clamping means for handling purposes clamping means for the purpose of applying pressure on the parts to be joined, in the area to be joined B29C66/81; work holders in general B25B; devices for holding or positioning work for welding metal B23K37/04
• CPC Class Codes: B29C 65/7873 using cooperating conveyor belts or cooperating conveyor chains B29C66/83423, B29C66/83523, B29C66/83533 take precedence
• CPC Class Codes: B29C 66/12463 being tapered
• CPC Class Codes: B29C 66/12469 being asymmetric
• CPC Class Codes: B29C 66/1248 Interpenetrating groove joints interpenetrating fingered joints B29C66/139
• CPC Class Codes: B29C 66/131 Single flanged joints, i.e. one of the parts to be joined being rigid and flanged in the joint area
• CPC Class Codes: B29C 66/542 joining hollow covers or hollow bottoms to open ends of container bodies
• CPC Class Codes: B29C 66/8242 Pneumatic or hydraulic drives using fluid pressure directly acting on the parts to be joined B29C66/8266
• CPC Class Codes: B29C 66/8246 Servomechanisms, e.g. servomotors
• CPC Class Codes: B29C 66/8322 Joining or pressing tools reciprocating along one axis
• CPC Class Codes: B29C 66/849 Packaging machines
• CPC Class Codes: B29C 66/9221 by measuring the pressure, the force or the mechanical power
• CPC Class Codes: B29C 66/92431 the pressure, the force or the mechanical power being kept constant over time B29C66/92613 takes precedence
• CPC Class Codes: B29C 66/929 characterized by specific pressure, force, mechanical power or displacement values or ranges
• CPC Class Codes: B29C 66/92921 in specific relation to time, e.g. pressure-time diagrams
• CPC Class Codes: B29C 66/932 by measuring the speed
• CPC Class Codes: B29C 66/93441 the speed being non-constant over time
• CPC Class Codes: B29C 66/93451 by controlling or regulating the rotational speed, i.e. the speed of revolution
• CPC Class Codes: B29C 66/939 characterised by specific speed values or ranges
• CPC Class Codes: B29C 66/9392 : in explicit relation to another variable, e.g. speed diagrams
• CPC Class Codes: B29C 66/961 : involving a feedback loop mechanism, e.g. comparison with a desired value
• CPC Class Codes: B65B 7/2878 : by heat-sealing

Abstract

Sealed synthetic resin containers are spin welded by bringing opposed, generally complimentary horizontal mating surfaces of the lid and bowl into contact under a predetermined axial pressure and rapidly accelerating rotation of the lid relative to the bowl while maintaining substantially the axial pressure to produce melting of the mating surfaces until a desired torque value is attained. Thereafter, the rotation of the lid is immediately decelerated to terminate the rotation and allow the mating surfaces to bond. Generally, the torque is monitored repeatedly during the accelerating rotation until a plateau is reached and the accelerating step is continued for at least 50 milliseconds thereafter.

Claims

1. The method of making sealed synthetic resin containers comprising:

(a) molding thermoplastic synthetic resin into bowls and lids therefor, said lid and bowl having substantially complimentary mating surfaces extending about the periphery thereof;

(b) filling one of said bowls with product;

(c) bringing opposed, generally horizontal mating surfaces of said lid and bowl into contact under a predetermined axial pressure while gripping said product filled bowl and lid securely;

(d) rapidly accelerating rotation of said lid relative to said bowl while maintaining substantially said axial pressure to produce melting of said mating surfaces until a desired torque value is attained; and

(e) then immediately decelerating said rotation of said lid to terminate said rotation and allow said mating surfaces to bond.

2. The method of making sealed synthetic resin containers in accordance with claim 1 wherein said rotation is effected at a high degree of acceleration and said termination of rotation is effected at a high degree of deceleration.

3. The method of making sealed synthetic resin containers in accordance with claim 1 wherein torque is monitored repeatedly during said step of accelerating rotation until a plateau is reached and said rotation step is continued for at least 50 milliseconds thereafter.

4. The method of making sealed synthetic resin containers in accordance with claim 3 wherein said monitoring of said torque is effected by monitoring the power being drawn by a motor used for producing the accelerating rotation.

5. The method of making sealed synthetic resin containers in accordance with claim 1 wherein said predetermined axial pressure is 200-500 p.s.i.

6. The method of making sealed synthetic resin containers in accordance with claim 1 wherein said acceleration and termination of rotation is effected in less than four relative rotations of said lid relative to said bowl.

7. The method of making sealed synthetic resin containers in accordance with claim 2 wherein said acceleration is at a rate of 35,000-250,000 rpm/sec.

8. The method of making sealed synthetic resin containers in accordance with claim 2 wherein said deceleration is at a rate of 35,000-250,000 rpm/sec.

9. The method of making sealed synthetic resin containers in accordance with claim 1 wherein there is included the step of directing steam onto said mating surface of said bowl prior to bringing said lid into contact therewith.

10. The method of making sealed synthetic resin containers in accordance with claim 9 wherein nitrogen is admixed with said steam.

11. The container spin welding apparatus in accordance with claim 9 wherein a partial vacuum is produced in sealed container.

12. Apparatus for producing spin welded containers comprising:

(a) a holder for firmly gripping a bowl;

(b) a holder for firmly gripping a complimentary lid;

(c) means for moving said holders relative to each other to bring mating surfaces into contact;

(d) pressure applying means for applying predetermined axial pressure on the mating surfaces;

(e) acceleration and deceleration means for rapidly accelerating rotation of the holders relative to each other and for rapidly decelerating said relative rotation while maintaining substantially the predetermined axial pressure; and

(f) torque sensing means for sensing the torque generated at the mating surfaces and is operative upon said acceleration means to determine when the acceleration has reached a desired value indicative of the desired melting of the mating surfaces to effect said deceleration.

13. The container spin welding apparatus in accordance with claim 12 wherein said torque sensing means senses the current drawn by the acceleration and deceleration means during acceleration until a plateau is reached.

14. The container spin welding apparatus in accordance with claim 12 wherein said predetermined axial pressure is 200-500 p.s.i.

15. The container spin welding apparatus in accordance with claim 12 wherein said acceleration and termination of rotation is effected in less than four relative rotations of the lid relative to the bowl.

16. The container spin welding apparatus in accordance with claim 12 wherein said acceleration is at a rate of 35,000-250,000 rpm/sec, and wherein said deceleration is at a rate of 35,000-250,000 rpm/sec.

17. The container spin welding apparatus in accordance with claim 12 wherein there is included means for directing steam onto the mating surface of the bowl prior to bringing said lid into contact therewith.

18. The container spin welding apparatus in accordance with claim 17 wherein there is included means for admixing nitrogen with the steam.