Coating implements with material supply – With means to impart heat to material – At discharge portion of implement
Reexamination Certificate
2001-12-03
2002-10-01
Maust, Timothy L. (Department: 3751)
Coating implements with material supply
With means to impart heat to material
At discharge portion of implement
C222S146200, C126S401000
Reexamination Certificate
active
06457889
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a hot melt glue gun with prevention of abnormal melting of a glue stick outside a heating chamber thereof, thereby preventing undesired hardening of the melted glue stick in the solid stick feeding passage and the resultant blockage of the solid stick feeding passage.
2. Description of the Related Art
FIG. 1
of the drawings illustrates a conventional hot melt glue gun comprising a housing
10
having a grip
11
. A gas container
12
containing flammable gas is mounted in the grip
11
. A combustion chamber
14
is provided in a front portion of the housing
10
and communicated with the gas container
12
via a conduit or gas tube
13
. An igniting device
141
is provided to ignite the flammable gas fed into the combustion chamber
14
. The heat generated in the combustion chamber
14
is transferred to a heating chamber
17
that is also located in the front portion of the housing
10
. The outer wall defining the heating chamber
17
is in direct contact with the outer wall defining the combustion chamber
14
to proceed with heat conduction. A dispensing nozzle
161
is provided at the front end of the housing
10
for dispensing melted glue. A solid glue stick passage is defined in a rear portion of the housing
10
for receiving a solid glue stick
16
. A carrier
152
is mounted in the rear portion of the housing
10
and connected to a spring
151
at an end thereof. The carrier
152
comprises a bore that defines a portion of the solid glue stick passage. A sleeve
18
is mounted between the heating chamber
17
and the carrier
152
for holding the solid glue stick
16
. When a trigger
15
is pulled, the carrier
152
is actuated to move the solid glue stick
16
into the heating chamber
17
. The solid glue stick
16
is melted in the heating chamber
17
and dispensed via the dispensing nozzle
161
.
The sleeve
18
is soft and may expand or shrink in diameter in response to a temperature change, thereby accommodating solid glue sticks of various diameters as a result of tolerance. However, the heat from the heating chamber
17
is transferred to the sleeve
18
and thus melts the solid glue stick outside the heating chamber
17
(see bulged portion
162
in FIG.
1
). A solid bulged portion
162
is formed after the sleeve
18
is cooled, and the solid glue stick passage is blocked in an end of the sleeve
18
. As a result, the solid glue stick
16
cannot be moved, and the user has to remove the solid bulged portion
162
via a fixing hole
19
in the rear portion of the housing
10
.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a hot melt glue gun with prevention of abnormal melting of the glue stick outside a heating chamber thereof, thereby preventing undesired hardening of the melted glue stick in the solid stick feeding passage and the resultant blockage of the solid stick feeding passage.
In accordance with the present invention, a hot melt glue gun is provided for receiving a solid glue stick, heating the glue stick to its melting point, and dispensing the melted glue. The hot melt glue gun comprises a housing comprising a grip portion and a dispensing nozzle, a heating chamber defined in the housing for heating a solid glue stick to its melting point, means for heating the heating chamber, means for feeding the solid glue stick into the heating chamber, a sleeve for holding a portion of the solid glue stick outside the heating chamber, and insulating means for prohibiting heat transfer from the heating chamber to the sleeve. The insulating means keeps the sleeve at a temperature below the melting point of the solid glue stick, thereby preventing melting of the portion of the solid glue stick outside the heating chamber.
Other objects, advantages, and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.
REFERENCES:
patent: 4314655 (1982-02-01), Leibhard et al.
patent: 4358030 (1982-11-01), Leibhard et al.
patent: 4804110 (1989-02-01), Sperry et al.
patent: 5479914 (1996-01-01), Tsai
patent: 5960996 (1999-10-01), Hsu
Kamrath Alan
Maust Timothy L.
Rider Bennett Egan & Arundel LLP
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