GATE STRUCTURE OF OPEN-CHAMBER HOT-RUNNER MOLD

STRUCTURE DE PORTE DE MOULE A CANAUX CHAUFFES A CHAMBRE OUVERTE

English Abstract

A hot-runner mold gate structure includes a body having a path,
and a room is defined in one end of the path. A guide member is inserted in
a bushing, and both of which are located in the room. A locking member is
connected to the room and has a reception area in one end of the locking
member. The guide member has an axial guide slot and a guide hole. The
guide member has a tip which protrudes through an outlet in the distal end
of the bushing. Melted PET passes through the guide hole, the guide slot
and the gap between the tip and the inside of the outlet to enter into the
mold set. The contact area between the locking member and the bushing is
minimized to maintain a certain temperature at the outlet of the bushing to
avoid the PET from being cooled.

Claims

THE EMBODIMENT OF THE INVENTION IN WHICH AN
EXCLUSIVE PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED
AS FOLLOWS:
1. A hot-runner mold gate structure comprising:
a body having a path defined axially therethrough, a room defined
in one end of the path and inner threads defined in an inner periphery of the
room, the inner threads located close to an open end of the body;
a guide member having a base and a body portion extending from
the base, a guide hole defined through the base, the body portion having a
tip at a distal end thereof;
a bushing having a base and a tubular portion extending from the
base of the bushing, a chamber defined axially through the tubular portion
and the base of the bushing, the tubular portion having an engagement
section and an extension section which shares a common axis with the
engagement section, a diameter of the extension section being smaller than
that of the engagement section, the body portion of the guide member
inserted into the chamber of the bushing, the guide member and the bushing
received in the room of the body, a diameter of a distal end of the extension
section being reduced and tapered toward a center of the bushing so as to
form an arrowhead-like distal end, an outlet defined in a center of the distal

end of the extension section of the bushing, the tip of the guide member
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located within the outlet, the tip of the guide member being not in contact
with an inner periphery of the outlet, and
a locking member having outer threads formed on an outside
thereof, the outer threads being connected with the inner threads to connect
the locking member to the body, the locking member having a flange
extending from the outside thereof and a skirt portion extending from the
flange, the locking member having a reception area defined axially through
the locking member and the skirt portion, the tubular portion of the bushing
extending through the reception area, an outside of the engagement section
of the tubular portion of the bushing contacting an inner periphery of the
reception area, a gap defined between an outside of the extension section of
the tubular portion of the bushing and the inner periphery of the second
partition of the reception area.
2. The hot-runner mold gate structure as claimed in claim I ,
wherein a shoulder is formed between the engagement section and the
extension section of the tubular portion of the bushing.
3. The hot-runner mold gate structure as claimed in claim 2,
wherein the outside of the extension section is tapered toward the tip
portion of the bushing.
4. The hot-runner mold gate structure as claimed in claim 1,
wherein the body portion of the guide member has at least one guide slot
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defined along an outside thereof, the at least one guide slot communicates
with the guide hole.
5. The hot-runner mold gate structure as claimed in claim 2,
wherein the body portion of the guide member has at least one guide slot
defined along an outside thereof, the at least one guide slot communicates
with the guide hole.
6. The hot-runner mold gate structure as claimed in claim 3,
wherein the body portion of the guide member has at least one guide slot
defined along an outside thereof, the at least one guide slot communicates
with the guide hole.
7. The hot-runner mold gate structure as claimed in claim 1,
wherein the body has a base and a shank extending from the base, the base
has a peripheral wall extending from a top thereof so as to define an annular
groove which encloses the shank, a notch is defined in the peripheral wall, a
heating unit is mounted to the shank and rested in the annular groove, a
wire of the heating unit passes through the notch.
8. A hot-runner mold gate structure comprising:
a body having a path defined axially therethrough, a room defined
in one end of the path and inner threads defined in an inner periphery of the
room, the inner threads located close to an open end of the body;

a guide member having a base and a body portion extending from
the base, a guide hole defined through the base, the body portion having a
tip at a distal end thereof;
a bushing having a base and a tubular portion extending from the
base of the bushing, a chamber defined axially through the tubular portion
and the base of the bushing, the tubular portion having an identical diameter,

the tubular portion having a lower section extending from the base, and an
upper section connected to the lower section, the body portion of the guide
member inserted into the chamber of the bushing, the guide member and the
bushing received in the room of the body, an outlet formed at a distal end of
the tubular portion of the bushing, the tip of the guide member located
within the outlet, the tip of the guide member being not in contact with an
inner periphery of the outlet, and
a locking member having outer threads formed on an outside
thereof, the outer threads being connected with the inner threads to connect
the locking member to the body, the locking member having a flange
extending from the outside thereof and a skirt portion extending from the
flange, the locking member having a reception area defined axially through
the locking member and the skirt portion, the reception area having a first
partition and a second partition, the tubular portion of the bushing extending

through the reception area, an outside of a lower section of the tubular

portion of the bushing contacting an inner periphery of first partition of the

reception area, a gap defined between an outside of an upper section of the
tubular portion of the bushing and an inner periphery of the second partition
of the reception area.
9. The hot-runner mold gate structure as claimed in claim 8,
wherein the inner periphery of the second partition expands outward toward
a direction opposite to the first partition so as to form the gap defined
between the outside of the upper section of the tubular portion of the
bushing and the inner periphery of the second partition of the reception
area.
10. The hot-runner mold gate structure as claimed in claim 8,
wherein a diameter of the second partition is larger than that of the first
partition so as to form the gap defined between the outside of the upper
section of the tubular portion of the bushing and the inner periphery of the
second partition of the reception area.
11. The hot-runner mold gate structure as claimed in claim 6,
wherein the body portion of the guide member has at least one guide slot
defined along an outside thereof, the at least one guide slot communicates
with the guide hole.
12. The hot-runner mold gate structure as claimed in claim 7,
wherein the body portion of the guide member has at least one guide slot
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defined along an outside thereof, the at least one guide slot communicates
with the guide hole.
13. The hot-runner mold gate structure as claimed in claim 8,
wherein the body portion of the guide member has at least one guide slot
defined along an outside thereof, the at least one guide slot communicates
with the guide hole.
14. The hot-runner mold gate structure as claimed in claim 8,
wherein the body has a base and a shank extending from the base, the base
has a peripheral wall extending from a top thereof so as to define an annular
groove which encloses the shank, a notch is defined in the peripheral wall, a
heating unit is mounted to the shank and rested in the annular groove, a
wire of the heating unit passes through the notch.
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Description

CA 02922733 2016-03-04
GATE STRUCTURE OF OPEN-CHAMBER HOT-RUNNER MOLD
BACKGROUND OF THE INVENTION
1. Fields of the invention
The present invention relates to a hot-runner mold gate structure,
and more particularly, to an open-chamber hot-runner mold gate structure
that has a certain temperature at the tip of the sprue gate so as to avoid the

melting Polyethylene Terephthalate (PET) from being in contact with the
cold molds.
2. Descriptions of Related Art
The conventional hot-runner mold gate structure is disclosed in
Taiwan Patent No. 1318923 and generally comprises a first body 10 with a
first path 11 defined axially therein. A second body 20 is detachably
connected to the first body 10 and has a second path 21 which
communicates with the first path 11. The second body 20 has a flange 23
which is fixed between the top mold 100 and the bottom mold 200 when a
hot-runner mold is connected to a mold set. A sprue gate 30 is located in the
second path 21 and engaged with the inner bottom of the second path 21.
The head of the sprue gate 30 protrudes from the second body 20. A heating
unit 40 is mounted to the first and second bodies 10, 20 so as to provide
heat to the first and second bodies 10, 20. A cover 50 is connected to the
outside of the heating unit 40.
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Because of dis-continuous injection, the second body 20 has one
end thereof adjacent to the inside of the fifth groove 108 of the top mold
100 and the inside of the second cover 52. The heat generated from the
heating unit 40 is transferred to the top mold 100 and the head 31 of the
sprue gate 30 via the second body 20. However, during the heat transferring
process, the heat loss happens during the contact between metallic parts, so
that the temperature of the area enclosed by the inside of the top mold 100
and the head 31 is less than that of the second body 20 in the heating unit
40.
The temperature of the area is inversely proportional to the distance to the
heating unit 40. Because of the gradually reduced temperature, the PET in
the area and located at the inside of the top mold 100 and close to the
injection opening is crystalized and solidified to form a white-fog-like
layer.
Although the crystalized and solidified white-fog-like layer can be
melted again by activating the heating unit so that the following PET can
normally be ejected, the crystalized and solidified white-fog-like layer of
the PET that is attached one the inside of the mold can only be partially
melted. Therefore, the melted material located on outside of the head
together with the partially melted crystalized and solidified white-fog-like
layer of the PET are ejected by the high pressure. The partially melted
crystalized and solidified white-fog-like layer of the PET is ejected into the
cavity in the mold set by high pressure, the partially melted crystalized and
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solidified white-fog-like layer of the PET will flow with the melted PET in
the cavity to form uneven and ir-regulated traces "S" on the product "B" as
shown in Fig. 1. The product with the traces "S" is deemed as an
unqualified product.
The present invention intends to provide am improved
open-chamber hot-runner mold gate structure to eliminate the shortcomings
mentioned above.
SUMMARY OF THE INVENTION
The present invention relates to a sprue gate structure and
comprises a body having a path defined axially therethrough. The path
communicates with a room defined in one end of the path. A guide member
has a base and a body portion extending from the base. A guide hole is
defined through the base, and the body portion has a guide slot, and a tip is
formed at the distal end of the body portion. A bushing has a base and a
tubular portion extending from the base of the bushing. A chamber is
defined axially through the tubular portion and the base of the bushing. The
tubular portion has an engagement section and an extension section. The
diameter of the extension section is smaller than that of the engagement
section. The body portion of the guide member is inserted into the chamber
of the bushing. The guide member and the bushing are received in the room
of the body. An outlet formed at the distal end of the bushing. The tip of'
the
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guide member is located within the outlet. The tip of the guide member
does not contact the inner periphery of the outlet.
A locking member is connected with the room and has a flange
extending from the outside thereof. A skirt portion extends from the flange.
The locking member has a reception area defined axially through the
locking member and the skirt portion. The tubular portion of the bushing
extends through the reception area. The outside of the engagement section
of the tubular portion of the bushing contacts the inner periphery of the
reception area. A gap is defined between the outside of the extension section
of the tubular portion of the bushing and the inner periphery of the
reception area.
The primary object of the present invention is to provide a sprue
gate structure wherein there is no direct contact between the outside of the
extension section of the tubular portion of the bushing and the inner
periphery of the reception area so that a certain temperature is maintained at
the outlet of the bushing, therefore, the PET is avoided from being cooled to
eliminate the problems of the conventional sprue gate structure.
The present invention will become more obvious from the
following description when taken in connection with the accompanying
drawings which show, for purposes of illustration only, a preferred
embodiment in accordance with the present invention.
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BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 shows the uneven and ir-regulated traces on the product
made by conventional sprue gate structure;
Fig. 2 is an exploded view of the sprue gate structure of the
present invention;
Fig. 3 shows the partial cross sectional view of the parts of the
sprue gate structure of the present invention;
Fig. 4 is an enlarged cross sectional view to show the sprue gate
structure of the present invention;
Fig. 5 is an enlarged cross sectional view to show that the sprue
gate structure of the present invention is cooperated with a mold set;
Fig. 6 shows that the melted PET is injected into the cavity of the
mold set via the sprue gate structure of the present invention;
Fig. 7 shows the product made by using the sprue gate structure
of the present invention, and
Fig. 8 is an exploded view to show the second embodiment of the
bushing of the sprue gate structure of the present invention, and
Fig. 9 is an enlarged cross sectional view to show that the sprue
gate structure of the present invention with the second embodiment of the
bushing is cooperated with a mold set.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
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Referring to Figs. 2 to 7, the sprue gate structure of the present
invention comprises a body 2 which has a base 20 and a shank 21 extending
from the base 20. The base 20 has a peripheral wall extending from the top
thereof so as to define an annular groove 22 which encloses the shank 21. A
notch 201 is defined in the peripheral wall. As shown in Fig. 5, a heating
unit 6 is mounted to the shank 21 and rested in the annular groove 22. A
wire of the heating unit 6 passes through the notch 201. A path 23 is defined
axially through the shank 21 and the base 20. A room 24 is defined in one
end of the path 23 and inner threads 241 are defined in the inner periphery
of the room 24, wherein the inner threads 241 are located close to the open
end of the body 2. The body 2 is installed in a cavity 10 of a mold set 1.
A guide member 3 has a base 30 and a body portion 32 extending
from the base 30. A guide hole 31 is defined through the base 30, and the
body portion 32 has a tip 321 at the distal end thereof. The body portion 32
of the guide member 3 has at least one guide slot 322 defined along the
outside thereof. The at least one guide slot 322 communicates with the
guide hole 31.
A bushing 4 has a base 40 and a tubular portion extending from
the base 40 of the bushing 4. A chamber 45 is defined axially through the
tubular portion and the base 40 of the bushing 4. The tubular portion has an
engagement section 41 and an extension section 42 which share a common
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axis with the engagement section 41. The diameter of the extension section
42 is smaller than that of the engagement section 41. A shoulder is formed
between the engagement section 41 and the extension section 42 of the
tubular portion of the bushing 4. The diameter of the distal end 43 of the
extension section 42 is gradually reduced and toward the center of the
bushing 4 so as to form an arrowhead-like distal end 43. The body portion
32 of the guide member 3 is inserted into the chamber 45 of the bushing 4.
Both of the guide member 3 and the bushing 4 are received in the room 24
of the body 2. An outlet "A" is formed at the center of the distal end 43 of
the bushing 4, and the tip 321 of the guide member 3 is located within the
outlet "A". The tip 321 of the guide member 3 docs not contact the inner
periphery of the outlet "A" located above the chamber 45 as shown in Fig.
4.
A locking member 5 has outer threads 50 formed on the outside
thereof, the outer threads 50 are connected with the inner threads 241 to
connect the locking member 5 to the body 2. The locking member 5 has a
flange 51 extending from the outside thereof and a skirt portion 52 extends
from the flange 51. The locking member 5 has a reception area 53 defined
axially through the locking member 5 and the skirt portion 52. Specifically,
the reception area 53 has a first partition 531 and a second partition 532,
and the tubular portion of the bushing 4 extends through the reception area
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53. The second partition 532 is a tapered hole, or the diameter of the second
partition 532 is larger than that of the first partition 531 so as to form a
stepped area. The outside of the engagement section 41 of the tubular
portion of the bushing 4 directly contacts the inner periphery of first
partition 531 of the reception area 53, while a gap is defined between the
outside of the extension section 42 of the tubular portion of the bushing 4
and the inner periphery of the second partition 532 of the reception area 53.
The contact area between the engagement portion 41 of the bushing 4 and
the locking member 5 is minimized. The heat conduction between the
bushing 4 and the locking member 5 is minimized, so that the temperature
between the extension portion 42 and the tip 321 of the guide member 31 is
slightly reduced or close to the temperature of the heating unit 6, such that
the PET 7 close to the outlet "A" does not have the crystalized and
solidified white-fog-like layer.
When in use, the melted PET 7 is delivered from a machine (not
shown) into the path 23 of the body 2, and the melted PET flows through
the guide hole 31 and the guide slot 322 of the guide member 3, and then
flows into the chamber 45 of the bushing 4. The melted PET eventually
flows into the cavity 11 of the mold set 1 via the outlet "A" of the bushing 4
as shown in Figs. 5 and 6. Because the outside of the engagement section 41
of the tubular portion of the bushing 4 directly contacts the inner periphery
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of first partition 531 of the reception area 53, while a gap is defined
between the outside of the extension section 42 of the tubular portion of the
bushing 4 and the inner periphery of the second partition 532 of the
reception area 53. Therefore, during the process, the heating unit 6
generates high temperature and the heat is directly delivered to the body 2,
the guide member 3, the bushing 4 and the locking member 5. Because the
guide member 3, the bushing 4 and the locking member 5 are compact so
that the heat loss reduces, the temperature in the chamber 45 between the
guide member 3 and the extension portion 42 of the bushing 4 is only
slightly lower than that of the body 2. Besides, the melted PET 7 is located
in the chamber 45 between the guide member 3 and the bushing 4, so that
the melted PET 7 does not contact the mold set 1. That is to say, the
temperature of the heat slightly drops when being conducted by the
extension portion 42 of the bushing 4, so that the temperature of the
extension portion 42 is slightly lower than that of the body 2. The melted
PET 7 in the chamber 45 corresponding to the extension portion 42 or in the
outlet "A" is stilled maintained at a certain temperature which keeps the
PET from being cooled to form a crystalized and solidified white-fog-like
layer of the PET 7. Therefore, there will be no crystalized and solidified
white-fog-like layer of the PET 7 being injected into the cavity 11 of the

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mold set 1. Therefore, as shown in Fig. 7, no uneven and jr-regulated traces
formed on the product 9.
Figs. 8 and 9 show the second embodiment of the bushing 4,
wherein the tubular portion 410 of the bushing 4 has an identical diameter.
The tubular portion has a lower section extending from the base 30, and an
upper section connected to the lower section. Therefore, when the tubular
portion 410 of the bushing 4 is inserted into the reception area 53 of the
locking member 5, an annular gap is formed between the upper section of
the tubular portion 410 and the second partition 532, and the lower section
of the tubular portion 410 is in contact with the first partition 531. The
same
feature as the previous embodiment is obtained.
While we have shown and described the embodiment in
accordance with the present invention, it should be clear to those skilled in
the art that further embodiments may be made without departing from the
scope of the present invention.
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Representative Drawing