Method and apparatus for trimming containers

1. A method for trimming a plastic container having open end and a base, which comprises: providing a multi-station assembly for holding a container during trimming, wherein said assembly includes a plurality of spaced stations and wherein said container traverses stations of said multi-station assembly for operating stages; moving the container to be trimmed onto said multi-station assembly at a first operating stage; moving a knife by a knife actuating arm into engagement with the container to be trimed at a second operation stage; trimming said container by said knife at a third operating stage, with said container held stationary during trimming and with the knife moving around the container at the area to be trimmed; ejecting the trimmed portion at a fourth operating stage; and ejecting the trimmed container at a fifth operating stage; wherein the base of the container is supported during its traverse through the multi-station assembly, and the container is also held by a holder beneath the area to be trimmed to hold the container stationary during trimming, including camming, positioning and moving the knife and knife actuating arm by moving a roller on a tapered cam.

2. A method according to claim 1 wherein said container to be trimmed is a blow molded container.

3. A method according to claim 1 , wherein the trimming operation in the second stage occupies a plurality of stations.

4. A method according to claim 1 , wherein separate stages are performed in the area of separate stations.

5. A method according to claim 1 , wherein the upper portion of the trimmed container has a finish portion, and wherein the outer diameter of the trimmed portion is no greater than the outer diameter of the finish portion.

6. A method according to claim 1 , wherein said method is a high speed operation for trimming at least 5,000 containers per hour.

7. A method according to claim 6 , including trimming at least 10,000 containers per hour.

8. A method according to claim 1 , wherein the container is held on a pedestal during its traverse through the multi-station assembly.

9. A method according to claim 1 , wherein the knife is cammed into engagement with the container to be trimmed.

10. A method according to claim 1 , including an inlet wheel for holding a plurality of containers to be trimmed, and sequentially feeding the containers onto said multi-station assembly from said inlet wheel.

11. A method according to claim 10 , wherein the trimmed containers are ejected onto an outlet wheel.

12. A method according to claim 8 , wherein the container is raised into the holder by the pedestal.

13. A method according to claim 12 , including the step of lifting the container into trimming position by raising the pedestal.

14. A method according to claim 1 , including the step of separating the trimmed portion from the trimmed container after the trimming operation and before ejecting the trimmed portion.

15. A method according to claim 13 , including the step of lowering the pedestal to a starting position after the trimming operation.

16. A method according to claim 1 , including moving the knife on a mounting plate and spring tensioner connected to the roller, wherein the spring tensioner is spaced from the axis of the tapered cam.

17. A method according to claim 1 , including moving the knife actuating arm downward and engaging the knife with the container to be trimmed by moving the roller on the cam.

18. A method according to claim 1 , including rotating the knife around the container during trimming by the cam, roller and knife actuating arm.