Method and apparatus for making a component having interior and exterior threads

• US 5,518,679 A
• Filed: 01/17/1995
• Issued: 05/21/1996
• Est. Priority Date: 01/17/1995
• Status: Expired due to Fees

• Current Assignee: Sta-Rite Industries LLC (Pentair Plc (Ireland))
• Original Assignee: Sta-Rite Industries LLC (Pentair Plc (Ireland))
• Inventors: Junk, Richard A.
• Primary Examiner(s): HEITBRINK, JILL LYNNE
• Application Number:
  US08/373,437
• Time in Patent Office: 490 Days
• Field of Search: 264/318, 264/334, 249/59, 249/67, 249/68, 425/577, 425/556, 425/438, 425/443, 425/DIG. 58
• US Class Current: 264/318
• CPC Class Codes: B29C 45/262 provided with unscrewing drive means unscrewing means outside the mould B29C45/178
• CPC Class Codes: B29C 45/2681 with rotatable mould parts
• CPC Class Codes: Y10S 425/058 Undercut

Abstract

Disclosed is a new method for making a component having interior and exterior threads. Such method includes the steps of providing a thread-forming apparatus having first and second circumferential threaded portions defining a space between them. Such space is filled with a flowable material, e.g., hot plastic, which is permitted to solidify and form the component. The apparatus and the component are then separated from one another by rotating such apparatus so that both threaded portions unscrew from the component. The finished component has interior and exterior threads which are simultaneously formed and substantially free of flashing. The new thread-forming apparatus has a first threaded portion and a pocket. A plug is in the pocket and has a second threaded portion spaced from the first threaded portion.

Claims

1. A method for making a component having interior and exterior threads, such method including the steps of:

providing a thread-forming apparatus having a first threaded portion for forming the exterior threads and a second threaded portion for forming the interior threads, the portions defining a space therebetween;

filling the space with a flowable material;

permitting the material to solidify and form the component;

holding the component stationary; and

rotating the apparatus, thereby separating the apparatus from the interior and exterior threads while the component is stationary.

2. The method of claim 1 wherein the providing step includes the steps of:

providing a thread-forming apparatus having a pocket therein which is bounded by the first threaded portion; and

providing a plug secured in the pocket, the plug including the second threaded portion.

3. The method of claim 2 wherein:

the threaded portions have generally equal lengths and have substantially the same thread pitch along such lengths;

the first threaded portion has a thread crest;

the second threaded portion has a thread root; and

the crest and the root are substantially in registry with one another along the length of the threaded portions.

4. The method of claim 2 wherein the step of providing a plug secured in the pocket includes:

placing the plug in the pocket; and

securing the plug in the pocket to prevent relative plug-pocket rotation.

5. The method of claim 1 wherein the rotating step includes rotating the first and second threaded portions simultaneously while holding the component stationary.

6. The method of claim 5 wherein:

the thread-forming apparatus is provided in a cavity for molding the component; and

rotation is in a direction to move the threaded portions away from the cavity.

7. The method of claim 5 wherein:

the thread-forming apparatus is provided in a cavity for molding the component; and

rotation is in a direction to unscrew the threaded portions from the component.

8. A thread-forming apparatus for making a component having interior and exterior threads, such apparatus being mounted for rotational movement and including:

a perimeter section having a pocket and a first threaded portion for forming the exterior threads;

a plug in the pocket and having a second threaded portion spaced from the first threaded portion for forming the interior threads, such plug being axially fixed with respect to the perimeter section.

9. The apparatus of claim 8 wherein:

the threaded portions have generally equal lengths and substantially the same thread pitch along such lengths;

the first threaded portion has a thread crest;

the second threaded portion has a thread root; and

the crest and the root are substantially in registry with one another along the length of the threaded portions.

10. The thread-forming apparatus of claim 8 wherein the plug is removable from the pocket and the perimeter section and the plug include holes for receiving a pin fixing the plug in the pocket.