Mechanical pencil with self-tapping propelling nut and the method of producing same and propelling a lead contained therein
AssigneeScripto, Inc.
InventorJohn C. Lockwood
Life of this patent
Estimating the term…
Abstract
A screw feed mechanical pencil having a propelling nut which self-taps on an unthreaded interior barrel wall. The pencil's barrel and split tube are plastic extrusions and a square lead is used to prevent lead rotation during writing.
Claims20
In a mechanical pencil of the type including a barrel having a rear portion adapted to hold a ferrule and a forward portion with a conical end, a tube formed with a longitudinal slot therein disposed within said barrel, means to cause relative rotation between said tube and said barrel and a writing lead propelling means mounted to travel longitudinally in said slot of said tube, the improvement comprising:
- an axially moveable writing lead propelling means having an angled outwardly extending ear which upon forward longitudinal axial movement engages and cuts into the interior of said barrel thereby forming a helical path responsive to rotation of said tube with respect to said barrel, whereby writing lead may be projected forwardly and outwardly from said barrel and said tube.
In a mechanical pencil having a barrel containing a writing lead therein and an axially moveable propelling means disposed within the barrel and operably associated with the writing lead the improvement of said propelling means being a transversely L-shaped member with two legs being longitudinally extending and having an angled outwardly extending ear projecting from one leg thereof, said ear being resilient so as upon forward longitudinal axial movement it engages and cuts into the interior of the barrel a path to position the writing lead at an advanced position.
In a mechanical pencil having a writing lead contained therein for selective advancement, the improvement of a barrel being an extruded hollow member with a plurality of longitudinally extending splines projecting inwardly from the interior thereof, and an axially moveable lead propelling means operably associated with the barrel so as upon forward longitudinal movement it deformably engages said splines to form a path and position the writing lead at an advanced position.
A method of propelling lead out of a mechanical pencil comprising the steps:
- rotating a split tube disposed within a barrel;
- cutting a helical path in the interior of said barrel by longitudinally advancing a propelling means having an angled outwardly extending ear that deformably engages the interior of said barrel to form a helical path therein;
- and
- advancing a piece of lead in said split tube in response to the advancement of said propelling means.
A method of constructing a disposable mechanical pencil comprising the steps:
- (a) cutting off a predetermined length of an extruded barrel;
- (b) cutting off a predetermined length of an extruded split tube;
- (c) inserting a piece of lead in said extruded split tube;
- (d) inserting an axially moveable self-tapping propelling means into said split tube that is adapted to engage and cut into the interior of said extruded barrel thereby forming a split tube assembly;
- (e) inserting said split tube assembly into said barrel;
- and
- (f) attaching a ferrule and a washer at the rear portion of said barrel for rotating said split tube and advancing said lead.
In a mechanical pencil of the type including a barrel, a tube formed with a slot therein disposed within said barrel and adapted to receive a writing lead for advancement therein, a writing lead propelling means mounted to travel in said slot of said tube, and means for advancing said writing lead propelling means relative to said barrel and said tube, the improvement including an axially moveable writing lead propelling means having means to deformably engage the interior of said barrel thereby forming a path therein for positioning said writing lead at an advanced position.
A method of propelling lead in a mechanical pencil comprising the steps of:
- rotatably moving a slotted tube within a barrel;
- advancing an axially moveable propelling means with respect to said slotted tube that deformably engages the interior of said barrel to form a helical path therein;
- and
- advancing a piece of lead in said slotted tube in response to the advancement of said propelling means.
Dependencies are inferred from the claim text.