Claims
- 1. The method of forming a sheet blank of thermoplastic material into a sleeve comprising the steps of: affixing the leading end of said sheet blank to the exterior of a generally cylindrical shaped forming member; rotating said forming member to cause said sheet blank to be wrapped thereabout into a generally tubular shape with the trailing end portion of the sheet blank overlapping the leading end portion; transferring said tubular shape axially relative said forming member by applying pressure against an axial end thereof; directing air from a heating means toward said end portions to pneumatically lift said overlapping portion and to progressively heat soften the facing surfaces of said end portions as said tubular shape is axially transferred, concurrently maintaining unheated facing surfaces of said end portions in contacting relationship; and pressing said overlapping end portion against the other end portion to compress said softened surfaces to form a sleeve having a liquid-tight seam.
- 2. The method according to claim 1 wherein said affixing step is performed by supplying vacuum to the leading end portion of said sheet blank to cause it to be held on said forming member, said vacuum being terminated when said shape is transferred axially on said forming member.
- 3. The method according to claim 1 wherein said transferring and maintaining steps include the steps of feeding said end portions between the nip of a first set of rollers, the outer roller of said first set of rollers being tapered to engage the overlapping end portion at a spaced location from the end thereof, whereby said overlapping end portion is supported by the tapered surface of said outer roller as it is lifted, rotating said outer roller in the feed direction to transfer said tubular shape; directing said end portions between the nip of a second set of rollers having surfaces complementary to said tubular shape whereby said two rollers press said end portions together to form a seam; and driving one roller of said second set to transfer said sleeve.
Parent Case Info
This is a now abandoned division, of application Ser. No. 418,612, filed Nov. 23. 1973.
US Referenced Citations (7)
Divisions (1)
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Number |
Date |
Country |
Parent |
418612 |
Nov 1973 |
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