Method of making one-piece hollow doorknobs

• US 2,688,297 A
• Filed: 05/16/1949
• Issued: 09/07/1954
• Est. Priority Date: 05/16/1949
• Status: Expired due to Term

• Current Assignee: Frank W. Livermont, Harry E. Collins, William F. Gresham
• Original Assignee: Frank W. Livermont, Harry E. Collins, William F. Gresham
• Inventors: Livermont, Frank W., Collins, Harry E., Gresham, William F.
• Application Number:
  US03/093,524
• Time in Patent Office: 1,940 Days
• US Class Current: 72/58
• CPC Class Codes: B21D 26/033 Deforming tubular bodies corrugating tubes by applying fluid pressure B21D15/03, B21D15/10
• CPC Class Codes: B21D 26/039 Means for controlling the clamping or opening of the moulds
• CPC Class Codes: B21D 26/047 Mould construction B21D26/037 - B21D26/045 take precedence
• CPC Class Codes: B21D 45/02 Ejecting devices
• CPC Class Codes: Y10T 428/12389 having variation in thickness

Claims