Writing instrument with locking core

Coating implements with material supply – Solid material for rubbing contact or support therefor – Including holder

Reexamination Certificate

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Details

Reexamination Certificate

active

06179502

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to writing instruments, in particular to color pencils and processes for making color pencils, having a core configured to mechanically lock with a slat having a corresponding configuration.
BACKGROUND OF THE INVENTION
As shown in
FIGS. 1A and 1B
, pencils are generally made up of a round pencil core
2
surrounded by an outer casing of wood or other material. The outer casing includes an upper section
6
and a lower section
4
, with an adhesive layer
8
to bind the upper and lower section. During mass production of pencils, upper
10
and lower
12
slats are used, which have multiple grooves
3
a
in slat
10
and
3
b
in slat
12
. Pencil cores are placed in the grooves of the lower slat and the upper slat is placed on the lower slat to form the upper and lower section of the pencil casing, respectively. To bond the cores to the slats and the slats to one another, an adhesive is generally used along each channel and at the bonding surface
8
between the two slats. The combination of slats and pencil cores is referred to as a “sandwich.”
The bonded slats are then cut into individual pencils in any variety of outer casing styles. These styles are well known and include round and polygonal cross-sections, as shown by the hexagonal outline 14 shown in FIG.
1
B.
With colored pencils, because the core is made from waxes, it is difficult to manufacture pencils such that the core remains in the pencil casing and does not rotate. Even with the use of adhesives, color cores often rotate and slide within the pencil casing. Moreover, the methods used to secure the core in the pencil casing should be amenable to mass produced, commercial manufacture of writing instruments.
Previous methods to secure a core to the slat have included both mechanical and chemical means used in conjunction (generally) with an adhesive. Prior mechanical methods of attachment relied on a variety arrangements. For example, as shown in Great Britain Patent 12,446, a series of thin angular ribs or flutes running the length of the core and projecting up from the surface thereof were pressed into wooden slats. The formation of the thin ribs disclosed by this reference is not amenable to modern commercial production methods. Swiss Patent 598,288 discloses a ribbed core held between two plastic by a clamping device. U.S. Pat. No. 551,288 discloses a lower slat having a deep groove for containing an entire pencil core. An upper slat caps off the lower slat and is wedged between the sides of the exposed core to restrain the core in place. In addition, an adhesive is used to restrain the core.
Chemical means, used in conjunction with adhesive, usually involve treatment of the core to allow it to better adhere to the wood slat. These treatments involve the modification of the greasy surface of a color core, to render the surface suitable for bonding with the adhesive. Examples of chemical means are disclosed in U.S. Pat. Nos. 1,892,508, 1,958,194, and 2,116,217. None of these previous methods have been entirely successful.
Thus, there is a need to design a cost efficient pencil having a core that is joined to a pencil slat in a manner that the core does not become displaced and does not rotate within the slat, and without the need of an adhesive.
SUMMARY AND OBJECTS OF THE INVENTION
In one aspect of the present invention, a writing instrument includes a core having a configuration with a plurality of channels spaced apart in a radial direction. The channels include sides which form an angle of at least 90 degrees at the centerline of each channel. The writing instrument also includes a pair of slats each having a configuration corresponding to approximately half of the configuration of the core.
In another aspect of the present invention, a process for manufacturing a writing instrument includes the steps of preparing a core material having a predetermined moisture content, extruding the core material to produce a core configuration having a plurality of channels spaced apart in a radial direction, preparing a pair of slats each to include a configuration corresponding to approximately half of the configuration of the core, positioning the core between the slats to align the configuration of the core with the configurations of the slats, and pressing together the core and the slats. The channels of the core include sides which form an angle of at least 90 degrees at the centerline of each channel.
In yet another aspect of the present invention, a writing instrument core includes a configuration having a plurality of channels spaced apart in a radial direction, where the channels have sides which form an angle of at least 90 degrees at the centerline of each channel.
In yet another aspect of the present invention, a slat for a writing instrument includes grooves having a configuration spaced apart along a radial direction, where the grooves include sides which form an angle of at least 90 degrees at the centerline of each groove.
In still yet another aspect of the present invention, a pencil includes a core having a configuration that includes a plurality of channels spaced apart in a radial direction, where the channels have sides which form an angle of at least 90 degrees at the centerline of each channel. The channels also include a first channel having a side in a first plane and a second channel having a side in a second plane substantially parallel to the first plane and positioned about 180 degrees in the radial direction from the first channel. The pencil also includes a pair of slats each having a configuration corresponding to approximately half of the configuration of the core.
Therefore, it is an object of the present invention to provide a pencil which overcomes the drawbacks of the prior art.
It is another object of the current invention to provide a pencil having a core that locks into a slat.
It is another object of the current invention to provide a pencil where a core is joined to a pair of slats without the use of an adhesive.
It is another object of the current invention whereby waxy, greasy, color cores are bonded to slats in the manufacture of a pencil.
These and other objects and aspects, and many of the attendant advantages of this invention, will be readily appreciated and better understood by reference to the following detailed description when considered in connection with the accompanying drawings summarized below.


REFERENCES:
patent: 43391 (1864-07-01), Cleveland
patent: 551288 (1895-12-01), Kaiser
patent: 972624 (1910-10-01), Kaiser
patent: 2075223 (1937-03-01), Pischel
patent: 2107816 (1938-02-01), Chesler
patent: 2131657 (1938-09-01), Ferst
patent: 2231410 (1941-02-01), Kern et al.
patent: 2319585 (1943-05-01), Chesler
patent: 3086903 (1963-04-01), Grossman
patent: 5549779 (1996-08-01), Stoecklein
patent: 78288 (1918-07-01), None
patent: 598024 (1978-04-01), None
patent: 12446 (1986-05-01), None

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