Injection mechanism for molding plastics

The invention relates to an injection mechanism for molding plastics, comprising at least one injection bushing, at least one lower needle valve, which is supplied by the injection bushing with molten plastics and opened by the pressure of the molten plastics during injection, further comprising heating means and cooling means adjacent to the flow path of the plastics, control means for maintaining the plastics at an adjusted temperature, further control means for injecting the molten plastics into at least one mold cavity via a corresponding injection aperture, and for the closing off the mold cavity after finishing the injection, wherein for improving this mechanism, especially for facilitating very small distances between injection openings, only one plunger within a heated distributor block is provided, which actuates several needle valves, situated at different locations within the distributor block, for supplying the molten plastics to the mold cavity via one single injection bushing, an injection nozzle and several lower injection openings.

The invention relates to an injection mechanism for molding plastics in at 
least one mold cavity, the injection mechanism having at least one 
injection nozzle and at least one lower needle valve supplied with molten 
plastics from an injection bushing. 
In injection molding arrangements for injection molding of products of 
plastics or other materials, these products are usually injected by way of 
a runner which is provided with a sprue. The injected products are then 
removed from this runner. If it is desirable to omit the runner, an 
arrangement is used with which it is possible to utilize runnerless 
injection molding. 
In such an arrangement for runnerless injection molding of products, one or 
more injection nozzles are assembled on a heated distribution block, which 
is spaced from the injection machine. Molten plastics flow from the 
injection molding machine through radially extending distributor channels 
in the heated distributor block downward through the injection nozzles and 
by way of an injection aperture into the product cavity. 
The products which are injection molded in the fashion may exhibit 
injection spots which can very negatively affect the function or the 
appearance of the injection molded products. In order to mold products 
which absolutely must not exhibit injection spots, needle valves must be 
utilized, which are installed in the injection nozzles and/or in the 
heated distributor block, these needle valves must be opened at the 
beginning of the injection into the cavity of the molten plastics and will 
close off the injection apertures in the product cavity after completion 
of the entire injection cycle. 
The bottom point of each needle valve is forcibly driven into the conical 
injection aperture of the product cavity and, as is well known, the most 
critical function of such an arrangement lies in the injection aperture, 
where improper functioning can cause costly break down of the injection 
machine or imperfections in the molded product. 
The lower apertures of the injection nozzle are separated from the cavity 
plate by an air space, which is filled with plastics and which provides a 
thermal insulation between the hot nozzles and the cold cavity plate. 
In injection molding arrangements for the production particularly of 
products of small dimensions, this arrangement requires several injection 
nozzles. Until the present time the minimal center distances between 
individual needle valves has been determined by their activating 
mechanism, each needle valve is activated separately and for this a 
certain minimal space is required. The center distances in the injection 
arrangement for small products to be injection molded is therefore 
entirely dependent on the minimal center distance which can be attained 
with separately activated needle valve mechanisms. 
Until the present time injection nozzles for this purpose have been 
designed such that for each selection of the manner of injection or the 
injection aperture, a different injection nozzle is required. 
The manner of injection can be among others, the so-called open nozzle, the 
nozzle provided with a fixed body in the injection aperture; the nozzles 
provided with a fixed, heated torpedo; a nozzle which is provided with a 
needle valve. 
Up to the present, a conscious selection is also required concerning the 
application of the manner of injection, if the applicable injection nozzle 
is placed centrally in the injection mold or if the injection nozzle is 
used in a hot runner design. 
Up to now, it is also necessary for the processing of certain types of 
plastics to make a conscious selection of the manner of injection, to 
commit to a certain type injection nozzle. 
It is evident that many types of injection nozzles must be purchased, in 
most cases with different dimensions and matching heights, thus not 
universally interchangeable. 
In injection molding arrangements for the production particularly of small 
products, this arrangement requires several injection nozzles. Up to the 
present time, the minimum center distances of the individual injection 
apertures have been determined by the sizes of the injection nozzles to be 
used, resulting in a minimum distance between injection apertures. 
It is the object of invention to avoid the disadvantages of the 
above-mentioned large variety of the injection nozzles to be used, and to 
facilitate very small center distances in an injection mechanism for 
molding plastics, comprising at least one injection bushing, at least one 
lower needle valve, which is supplied by the injection bushing with molten 
plastics and opened by the pressure of the molten plastics during 
injection, further comprising heating means and cooling means adjacent to 
the flow path of the plastics, control means for maintaining the plastics 
at an adjusted temperature, further control means for injecting the molten 
plastics into at least one mold cavity via a corresponding injection 
aperture, and for the closing of the mold cavity after finishing the 
injection. 
The object of the invention is achieved by an injection mechanism wherein 
only one plunger within a heated distributor block is provided, which 
actuates several needle valves, situated at different locations within the 
distributor block, for supplying the molten plastics to the mold cavity 
via one single injection bushing, an injection nozzle, and several lower 
injection openings. 
The purpose of this invention is among other things to facilitate very 
small center distances between injection apertures. In this invention this 
purpose is realized in that several needle valves are placed at very small 
center distances (minimum center distance is 3 mm) from each other in a 
single injection nozzle, which is provided with as many lower apertures as 
the injection nozzle contains needle valves. These needle valves are then 
activated by a plunger, which has been placed in the heated distributor 
block to which the injection nozzle is assembled. The plunger may be 
actuated pneumatically, hydraulically or by one or more springs and its 
motion may be derived from a mechanism outside the part in which the 
injection mechanism is installed. If the needle valves are mounted 
directly in the plunger, the plunger must be double acting. 
In applying such an injection nozzle several products can be injection 
molded with a single injection nozzle or a single large product can be 
injection molded through a single injection nozzle in several places, the 
injection nozzle being provided with needle valves in both cases. 
The main advantage of this new application is, in addition, that the needle 
valves are directly activated by a single plunger which is located in the 
heated distributor block and that in this way less height for assembly in 
an injection molding arrangement can be attained. The realization of this 
construction is such that this combination of plunger, needle valve, 
injection nozzle and heated distributor block, after assembly is one 
entity and can therefore be held within very close tolerances. 
Another additional essential advantage is that in applying several 
injection nozzles, every plunger in the heated distributor block is 
activated and controlled separately from outside the injection molding 
arrangement, also during the injection molding process. 
Another important advantage is achieved by the structure of the invention 
in that the needle valves can be exchanged or their axial positions can be 
adjusted, this latter case through the use of a spacer bushing underneath 
the head of the needle, without the necessity to disassemble the injection 
molding arrangement. 
To simplify the assembly and disassembly of these needles the axially 
adjustable guide bushing in the plunger is prevented from rotating in that 
it is provided with one or more flat spots, which are in contact with one 
or more corresponding flats in the plunger. 
Another purpose of the invention is to reduce the center distances between 
the locations where injection occurs through the use of a single injection 
nozzle as described above, but without utilizing needle valves. 
In order to facilitate full understanding of the above-mentioned parts of 
the invention through which a 100% breakdown-free injection arrangement is 
aimed at, the parts which are required for the application of the 
invention and will be part and parcel of it, will now be described. 
Because the injection nozzle contains several lower injection apertures 
which protrude with respect to it and since it is necessary to place the 
lower injection apertures as close to each other as possible, and because 
it is desirable to obtain the correct location of the lower apertures with 
respect to the injection openings in the cavity plates, a spacer and 
centering bushing is utilized, which correctly centers the entire 
injection nozzle with respect to the cavity plate so that the lower 
injection apertures are placed exactly opposite the injection openings. 
In injection molding of certain types of plastics such as polycarbonate, 
P.V.C., acetate, nylon, acrylates and other high quality plastics which 
have a narrow range of processing parameters such as melting temperature 
within which these can be properly processed, especially in the vicinity 
of the lower aperture, care should be taken that at this location the 
temperature remains constantly at the correct value. This is attained 
mainly by producing the injection nozzle from a material with high heat 
conductivity, e.g. beryllium copper, and in heating this by means of an 
integrally cast, plastics-tight heating element, provided with a 
thermocouple, which should be placed as close as possible to the lower 
aperture. 
Further, care has to be taken that little heat is lost through conduction 
from the injection nozzle to the cavity plate. In order to achieve this, 
the spacer and centering bushing has been designed as shown in the 
attached drawings, FIGS. 1 through 6. 
In order to further reduce heat conduction losses from the heated 
distributor block and the injection nozzle, the heated distributor block 
is not in contact with the front plate of the injection molding 
arrangement, but assembled directly via the spacer and centering bushing 
to the cavity plate with high strength socket head cap screws. 
In this manner, a compact assembly of the above-mentioned parts is obtained 
through which in the locations of the surfaces of contact of the spacer 
and centering bushing with the cavity plate the unit pressure against each 
other is so large (but still within permissable limits) that no plastics 
can leak through to the outside and thus a proper closure is obtained. 
Making the surface of contact of the injection nozzle with the heated 
distributor block large with respect to the length of the injection 
nozzle, facilitates a proper and regular heat exchange between them, 
through which it even becomes possible, during the processing of plastics 
with a wide melting temperature range, to perform injection molding 
without separately heating the injection nozzle. All required heat is then 
coming from the heated distributor block and will flow easily to the lower 
injection apertures, because of the large area of contact with the 
injection nozzle. This is only possible with a small ratio of length to 
diameter. To obtain a proper closure between these two parts, a special 
gasket has been placed around the distributor channel. Because the 
above-mentioned surfaces are in flat contact only, the heated distributor 
block can expand freely as a result of the heat to be supplied to it and 
thus slides freely over the surface of the injection nozzle. 
According to the subject matter to the invention, a single injection nozzle 
is provided with a heating element and a thermocouple and has one or more 
lower nozzles, as many as there are injection apertures, each with a free 
exit opening, and in which one or more externally adjustable fixed needles 
can be placed or omitted, or one or more externally adjustable needle 
valves. All above-mentioned manners of injection can be achieved in 
placing the injection nozzle centrally in the injection molding 
arrangement or installing this injection nozzle in a hot runner design.

Referring to FIGS. 1 and 2, part of the entity of a heated distributor 
block 1 of an injection molding arrangement is shown, with injection 
bushing 2 through which the molten plastics enter the injection molding 
arrangement from the injection machine by way of distributor channels 3 
and 4 and injection aperture 5 and are injected into the form cavity 6. 
The injection bushing 2 is provided with band heater element 7 and the 
heated distributor block 1 is provided with heater cartridges 8. Against 
the heated distributor block has been placed the injection nozzle 9 
provided with distributor channel 4, which in turn is provided with the 
lower injection aperture 10. In the injection nozzle has been placed a 
cast-in heater element 11, provided with a thermocouple 12. This 
thermocouple should be located nearest the vicinity of the lower aperture, 
because this is the critical point as far as keeping the molten plastics 
in the space between the lower aperture 10 and the recess 13 in the form 
cavity plate 14 at the proper temperature. Near the lower aperture the 
plastics material are kept warm and are heated or cooled, depending on the 
temperature control of the injection nozzle. The injection nozzle 9 may be 
composed of different materials. The part which contains the distributor 
channel 4 is however always made from highly conductive material such as 
beryllium copper. The heater element 11 and thermocouple may be integrally 
cast or not. 
Because the temperature of the injection nozzle can be controlled 
externally by means of an installed thermocouple, the temperature of the 
lower aperture can be managed accurately. This is of great importance in 
injection molding of so-called engineering materials having a narrow 
processing temperature range such that the molten plastics are either too 
cold and resistant to flow or too hot and thus are burned and become unfit 
for use. On the side of recess 13 in form cavity 14 the molten plastics 
are cooled off locally because the form cavity plate is cooled off by a 
cooling fluid in cooling channels 15. Because in the described system the 
temperatures of both above-mentioned sides 10 and 13 can be controlled and 
particularly at the location of side 10, injection molding with the 
described system will be performed without problems. 
The closure between the injection nozzle and the heated distributor block 
is obtained by a special gasket 16. In order to incur as little as 
possible heat conduction losses, a spacer and centering bushing 17 is 
placed between injection nozzle 9 and the form cavity plate 14, in a 
manner as shown in the attached drawings FIG. 1 through 6. Mathematically 
it can be shown that this design provides 6 to 10 times less heat 
conductivity and therefore also 6 to 10 times less heat loss. In order to 
position the injection nozzle accurately opposite the the injection 
opening 5, the spacer and centering bushing 17 is used. The injection 
nozzle is centered with respect to the rim 18 in the spacer and centering 
bushing, which in turn is centered in the form cavity plate 14 with 
respect to the diameter 19. The surfaces 20 and 21 of the spacer and 
centering bushing 17 will have to be coaxial within predetermined 
tolerances. 
Installing the spacer and centering bushings provides airspace 22 between 
bushing 17 and injection nozzle 9. This space 22 will be filled with 
plastics and will provide the proper thermal insulation between both 
mentioned parts 9 and 14. The installation of the spacer and centering 
bushing 17 also provides an air gap 23 resulting in a second thermal 
insulation between injection nozzle 9 and form cavity plate 14. Installing 
injection nozzle 9 with high quality socket head cap screws 24 in the 
heated distributor block and by way of the spacer and locating ring 17 on 
form cavity plate 14, such a large, but still allowable, pressure is 
obtained on surface 25, that this results in an absolute closure against 
leakage of the molten plastics from the distributor channels 3 and 4. 
Installation of the socket head cap screws also pulls the heated 
distributer block 1 against injection nozzle 9 resulting in both the 
proper closure as well as the proper heat flow from the heated distributor 
block in the direction of the injection nozzle. Because the mentioned 
parts are connected with each other by means of the socket head cap screws 
24, the heated distributor block 1 does not need to be supported by a 
clamping plate of the injection molding arrangement, so that here also 
there are no contacting surfaces resulting in heat losses and the 
installation height of the injection molding arrangement can be kept 
smaller. 
Correct adjustment should result in location of the front surface of the 
needle 26 of which the front end is cylindrical or nearly cylindrical, in 
the same plane as the surface of the product cavity of the injection 
molding arrangement. 
At the start of the injection process, space 28 above the plunger is vented 
to atmosphere. At the same time, at the start of the injection cycle the 
pressure to which the molten plastics are subjected will press needle 26, 
which is connected to guide bushing 27, via the surface of the enlarged 
part of bushing 27 against frictional resistance, moving it a distance of 
about 4 mm, so that the molten plastics can enter the product cavity 6 by 
way of the injection opening 5. The enlarged portion provides an enlarged 
surface against which the injection pressure of the molten plastics can 
act resulting in a large force for opening the needle valve. The enlarged 
portion of the guide bushing 27 forms a collar at the front end of the 
bushing which functions as a stop to the motion of the needle valve. The 
travel of needle 26, and thereby the travel of the plunger 30, 31 to which 
the guide bushing is attached by means of a socket head cap screw, is 
limited through contact of the shoulder of the guide bushing 27 against a 
surface in the bore in the heated distributor block. The presence of the 
collar also permits the rest of the guide bushing to be of small diameter 
resulting in a large ratio of length to diameter. 
As soon as the injection cycle has been terminated, the pressure in the 
distributor channels 3 and 4 will increase no longer and if the injection 
nozzle 57 of the injection machine (see FIG. 6), after termination of the 
injection cycle, is pulled back in the injection bushing 2, the existing 
pressure in the distributor channels 3 and 4 will be reduced rapidly and 
if there exists a proper fit between the injection nozzle and the 
injection bushing a vacuum will even result in the distributor channels. 
The instant the total injection cycle is terminated, a signal from within 
the injection machine will cause compressed air to press on surface 29 of 
the plunger consisting of parts 30 and 31. In the plunger the guide 
bushing 27 has been installed which is secured against turning and in the 
guide bushing in turn the needle 26 is installed. The compressed air 
causes a force to act through which the plunger and thereby the needle 26 
are moved downward with great force and speed, so that the injection 
opening 5 is closed and the front end of the needle 26 is caused to lie in 
one plane with the outside surface of the form cavity 6. As was described 
above, at the beginning of the injection of plastics, the compressed air 
is vented and the space 28 above surface 29 will lose its pressure. 
The height of the closure of the point of the needle valve in the injection 
opening is not critical, because during the closed condition of the needle 
valve, no large pressure differences are occuring, so that closure against 
a ring-shaped surface of minor dimension (about 0.5 mm) suffices. In order 
to minimize wear during operation, the edge of the bottom front surface of 
the needle is provided with a radius of about 0.2 mm. In addition, the 
corresponding inside edge of the injection aperture in the recess 13 is 
chamfered. 
The plunger consisting of parts 30 and 31 which are held together by socket 
head cap screws 33 are located with respect to each other through the 
accurate male-female fit 34 between the two. In addition the plunger 
contains a gasket ring 32. Axially movable guide bushing 27 is installed 
in the plunger with ample clearance but secured against rotation with cap 
screw 35, so that independant guiding of the plunger assembly as well as 
guide bushing 27 with respect to each other are assured. To prevent 
rotation of the guide bushing 27 with cap screw 35 during assembly or 
disassembly, the guide bushing 27 is provided with one or more flat spots 
corresponding with one or more flat spots in the plunger. 
Leakage around the plunger is prevented by the gasket 32 and after 
completion of its travel, surface 36 of the plunger will be in contact 
with surface 37 of the heated distributor block, so that air which could 
escape around the gasket 32, should it become worn, is stopped anyway. 
Should, after a time, seats 36 or 37 become damaged, the compressed air is 
still up against the barrier provided by the close fit between parts 1 and 
31. 
A standard commercially available pin having a cylindrical or conical head 
is used as a needle valve 26 and the needle valve is attached to the guide 
bushing 27 by means of one or more lock screws 65 and locked in the 
desired position. 
The parts 30, 31 and 27 can easily be manufactured to the required 
tolerances, since they have a round geometry. This also goes for the 
corresponding bores for these parts in the heated distributor block. For 
convenient assembly and disassembly of the plunger and the needle valve, 
the heated distributor block 1 is provided with a cover 39, which is 
attached by means of socket head cap screws 40. This has the advantage 
that in case of break down in the described system, assembly and 
disassembly can be executed easily during the injection molding process, 
without having to remove the injection molding arrangement from the 
injection machine. 
The closure against leakage of the molten plastics around the guide bushing 
27 in the heated distributor block is obtained by an accurate fit of the 
one part within the other and by a large ratio of length versus diameter. 
To prevent wear in the heated distributor block, guide bushing 27 is heat 
treated, so that the hardness of the latter is lower than that of the 
distributor block. Should some molten plastic leak through, it will be 
collected in groove or recess 41 from where it will run out via channel 42 
and tube 43. This drainage will be facilitated during admittance of 
compressed air to the plunger since during the plunger's downward travel 
air within the space 58 is compressed and expelled by way of channel 59 
which is connected to the underside of the bore in which the plunger is 
located, and tube 43 causing a partial vacuum in channel 42 one or more 
recesses 41 may be present. 
When corrosive plastics are to be used, the distribution channels are 
covered with a protective surface layer. 
In FIGS. 2 and 3 it can be seen that the lead wires from the heater element 
and the thermocouple are brought to the outside through installed tube 44 
to prevent damage in assembly and should leakage of molten plastics take 
place. Compressed air is supplied and vented through tube 45. 
In FIG. 3 the application of a manifold design of the injection nozzle with 
several needle valves is shown. 
As many lower nozzles or injection openings 10, 5 are contained in the 
manifold version as there are needle valves 26. To this design the 
operation and all applications and characteristics of the single design as 
mentioned above and to be mentioned below, are applicable, subject to the 
condition that the injection nozzle has to be secured against rotation 
outside the diameter of the spacer and centering bushing. 
A manifold design also may be provided having one injection bushing for 
receiving plastics from an injection molding machine or one injection 
nozzle but without needle valves for injection molding more than one 
product or injection molding one large product from several locations. 
In FIGS. 4 and 5 the design of the central location is shown to which the 
principles as mentioned in FIG. 3 are also applicable. The parts 46 are 
band heater elements. 
With reference to FIG. 6, the operation of a design in which the plunger is 
placed within a not directly heated distributor block 60 is described. To 
this design the operation and all applications and characteristics of the 
single and manifold design as mentioned above and to be mentioned below 
are applicable. 
The molten plastics within this distributor block are kept at the proper 
temperature by heated tubes 47. The above-mentioned injection nozzle 9 is 
now composed of parts 48, 49 and 50. The heater element 11, controlled by 
the internally installed thermocouple 12, will keep this injection nozzle 
at the desired temperature. To reduce heat conduction losses, part 49 
contacts the distributor block 60 only with the narrow edge 51 which also 
goes for part 50 with edge 52. 
Because part 49 is heated and is made from a highly conductive material, 
e.g. beryllium copper, the molten plastics which flow from distributor 
channels 53 to part 49, will flow to injection aperture 5 from distributor 
channels 54 and 55, whence to the product cavity. 
Above, in FIGS. 1 through 6, preferential designs of the single and 
manifold needle valves have been described in accordance with the 
invention. However, it will be evident that within the framework of the 
invention several variations of the details are possible. Those parts 
which in accordance with the drawings have been designed to be operated 
with Allen wrenches, may be suited for operation with other tools, such as 
a screw driver. Moreover, the plunger may be activated pneumatically, 
hydraulically or by one or more springs and its motion may be derived from 
a mechanism outside the part in which the injection mechanism is 
installed. The needle valve 26 may be installed directly in the plunger, 
in which case guide bushing 27 is eliminated and the plunger must be made 
double acting. The injection nozzle can also be composed from parts such 
as 48, 49 and 50. 
Referring to FIGS. 7 and 7a, the reference number 8' indicates the 
installation plate of the injection mechanism with injection opening 21' 
through which the molten plastics enter the injection mechanism from the 
injection machine and are injected via the distributor channels 20' and 2' 
and the injection aperture 11' into the cavity 22'. 
Against installation plate 8' has been placed the injection nozzle 1', 
which has been provided with distributor channel 2' running into the 
injection aperture 3'. The injection nozzle has been cast around a heater 
element 4' which is provided with thermocouple 5'. This thermocouple 
should be located as closely as possible in the vicinity of the lower 
aperture, because this is the critical point as far as the correct 
temperatures of the molten plastics are concerned. The molten plastics 
fill the space between the lower aperture 3' and the recess 6' in the 
cavity plate 7'. Near the lower aperture the plastics are kept warm, and 
are heated or cooled depending on the temperature control of the injection 
nozzle. 
Because the temperature of the injection nozzle can be controlled 
externally by virtue of the installation of a thermocouple, the 
temperature of the lower aperture can be exactly regulated. This is of 
extreme importance in injection molding of the so-called technical 
plastics which have a narrow processing temperature range such that if the 
molten plastics are too cold, they flow with difficulty or if too hot, 
they are burned and are destroyed. In the recess 6' in the cavity plate 7' 
the molten plastics are cooled off because the cavity plate is cooled by 
means of a coolant flowing in cooling channels. Because in the described 
system the temperature of both mentioned sides 3' and 7' can be regulated 
and especially side 3', it will be possible to injection mold with the 
described system without problems. 
The closure between the injection nozzle and the installation plate 8' is 
obtained by the special gasket 9'. In order to restrict heat losses as 
much as possible, a spacer and centering ring 10' is placed between 
injection nozzle 1' and cavity plate 7', which is designed as shown in the 
attached drawings, FIGS. 7 through 13. It can be proven mathematically 
that this design reduces heat conduction 6-10 times and thus reduces heat 
losses 6-10 times. In order to place the injection nozzle exactly opposite 
the injection aperture 11', the spacer and centering ring 10' is utilized. 
On one end the injection nozzle is centered on edge 12' in the spacer and 
centering ring, which in turn is centered in the cavity plate 7' on 
diameter 13'. Surfaces 14' and 15' of the spacer and centering ring 10' 
therefore will be coaxial with each other within predetermined tolerances. 
Installation of the spacer and centering ring results in an air space 16' 
between ring 10' and the injection nozzle 1'. This space 16' will be 
filled with plastics resulting in the proper thermal insulation between 
abovementioned parts 1' and 7'. Installation of the spacer and centering 
ring 10' also results in an air space 17', providing a second thermal 
insulation between injection nozzle 1' and cavity plate 7'. 
In assembling the injection nozzle 1' by means of high strength socket head 
cap screws and the spacer and centering ring 10', to cavity plate 7', such 
a high unit pressure (but still allowable) is obtained on surface 19', 
that this results in absolute closure against leakage of molten plastics 
from distributor channels 2' and 20'. 
Installation of the socket head cap screws pulls installation plate 8' 
against the injection nozzle as well, also resulting in proper closure as 
well as proper heat flow from the injection nozzle in the direction of the 
installation plate. To obtain proper centering of parts 1' and 8', a 
centering ring 23' is installed whereas an exchangeable bushing 24' has 
been installed in installation plate 8'. 
In FIGS. 8 and 8a, the injection molding mechanism of FIG. 7, has been 
installed such that the injection nozzle 1' is placed against the heated 
distributor block 25' (hot runner beam) and the installation plate 8' is 
placed on the heated distributor block. The installation plate 8' is 
provided with a centering edge 43' which fits accurately within the 
centering bore 44' in the hot runner beam 25'. With the socket head cap 
screws placed in the installation plate (not shown here but shown in FIGS. 
10 and 10a, ref. no. 35'), the heated distributor block 25' and the 
injection nozzle 1' are bolted to the cavity plate 26'. Thus it is 
possible to utilize the injection molding mechanism shown in FIG. 7, which 
is here placed centrally in an injection molding mechanism, in a hot 
runner design in that the hot runner beam is placed between installation 
plate 8' and injection nozzle 1', without the necessity to make any 
changes at all in parts 1' and 8'. 
In FIGS. 9 and 9a, the injection molding mechanism shown in FIG. 7, has 
been installed such that here the injection molding mechanism has been 
provided with an externally adjustable fixed needle 27'. In removing 
bushing 24' of FIG. 7 and in replacing this by needle bushing 28', an 
injection molding mechanism is obtained with a free injection aperture 
provided with an externally adjustable fixed needle. 
The needle bushing 28' has been provided with several bores 29', through 
which the molten plastics flow from the injection molding machine via 
injection aperture 21' and the distributor channels 2' and 20' to the 
cavity 22'. 
The needle bushing 28' is provided with a collar 42', which is clamped with 
a light press fit between the injection nozzle 1' and adaptor plate 8' in 
order to obtain the proper heat conductivity. Also for this purpose the 
needle bushing is made from a highly conductive material, i.e. beryllium 
copper, which can be provided with a protective surface in case corrosive 
plastics are processed. The collar 42' causes the needle bushing 28' to be 
centered correctly in the adaptor plate 8' so that a needle 27' installed 
in the needle bushing 28' is centered accurately in the middle of the 
distributor channel 2' and injection aperture 32'. 
The needle 27' is threaded on one end and provided with a hexagon socket. 
The thread fits within the internal screw thread in the needle bushing 28' 
such that the needle 27' is adjustable and can be locked in any position 
by means of one or more set screws 30'. In order to close the threaded 
hole, cap 31' has been installed. The cap 31' prevents plastics from 
entering the hole and improves the flow pattern of the entering molten 
plastics. The point of the needle can now be positioned in the injection 
aperture 32' to such extent that on the product to be injection molded no 
objectionable spot will result. 
In order to center the needle in the injection aperture 32', the lower part 
3' of the injection nozzle 1' has been designed such that the needle is 
centered between several points 33'. 
It is even possible to make the fit between the needle and the centering 
points so close that the needle is in contact with the centering points 
and this results in flow of heat from the lower part of the nozzle 3', 
which is heated by the heating element in the nozzle, to the lower tip 34' 
of the needle to such a temperature that the plastics in injection 
aperture 32' can not freeze, and the aperture thus remains open. To obtain 
a proper heat flow via the needle to point 34', the needle is made of a 
high conductive material such as beryllium copper. An injection nozzle can 
be provided with a plurality of such fixed needles. 
FIGS. 10 and 10a are is the injection molding mechanism of FIG. 9, 
installed such that here the injection nozzle 1' is placed against the hot 
runner beam 25' and the installation plate 8' containing the needle 
bushing 28', needle 27', and the lock screw 30', is placed on the hot 
runner beam. Installation plate 8' has a centering edge 43' which fits 
accurately in the centering bore 44' of hot runner beam 25'. This 
centering and the centering ring of the injection nozzle via the spacer 
and centering ring in the cavity plate, causes needle 27' to be aligned 
with the injection aperture, with the socket head cap screws 35' bolting 
the installation plate 8', the hot runner beam and the injection nozzle 
against cavity plate 26'. Here again the injection molding mechanism of 
FIGS. 7 and 9 which are installed centrally in an injection molding 
arrangement, can be utilized in a hot runner design through placement of 
the hot runner beam between installation plate 8' and the injection nozzle 
1', without any change to parts 1', 8' and 28'. The adaptor plate 8' 
contains bolt holes 38' in a standardized pattern which permits universal 
application of the apparatus to all modes of injection molding. 
In FIGS. 11 and 11a the injection mechanism has been installed such that 
here again the same injection nozzle 1' has been utilized on top of which 
the same hot runner beam 25' has been placed, to which the needle valve as 
part of assembly 36' has been assembled. The entire assembly is bolted to 
the cavity plate 26' by means of the socket head cap screws 35'. 
The needle valve contained in assembly 36' has been described in connection 
with FIGS. 1-6 of the present application. The injection mechanism 
described here, with one or more needle valves, has been installed here in 
a separate assembly 36', such that this can be manufactured more readily 
in series production. The alignment of the assembly 36' on the hot runner 
beam has been designed in the same manner and has the same dimensions as 
described in FIGS. 8 and 10. 
Here also the needle valve 27' is aligned between several centering points 
33' such as described in FIG. 3, this to obtain perfect location of the 
needle valve above the injection aperture 37', which must close off, so 
that the injection opening will not wear on one side only. 
In FIGS. 7 through 11a identically the same injection nozzle 1' is 
utilized, as a complete unit as described in FIG. 7. It is therefore 
possible to realize all existing types of injection molding with one and 
the same injection nozzle, if this is placed centrally in an injection 
molding arrangement as well as if this is placed in a hot runner injection 
molding arrangement. 
The selection of a fixed pattern of installation bolts 38' (shown in FIG. 
10) renders this injection mechanism universally applicable. 
In FIGS. 12 and 13 the design is shown of a manifold application of an 
injection molding arrangement with an injection nozzle 45' containing 
manifold lower apertures 3', in which are placed several needle valves 
27'. 
For the manifold design, the operation of all above-mentioned and hereafter 
to be mentioned applications and characteristics of the single design, 
shown and described in FIGS. 7 through 11a, are applicable to this 
manifold design, subject to the condition that the injection nozzle 45' 
besides the alignment via spacer and centering ring 46', has been provided 
with spacer and centering rings 40'. 
The lower injection apertures 3' have individual locating and centering 
rings 40' which help to align the injection nozzle 45' and allow the 
molten plastics to fill the air space 41' and assist in forming a proper 
closure between the lower injection apertures 3' and the cavity plate 26' 
so that no leakage of plastics can occur. The locating and centering ring 
40' has the same function as the locating and centering ring 10 of FIG. 1. 
The injection mechanism for use with more than one injection opening may 
comprise one or more nozzles having a total number of nozzle apertures 
equal to the number of injection openings with each nozzle aperture having 
fixed adjustable needles or needle valves. The needles can be externally 
adjusted. 
For the description of the operation of this mentioned needle valve 
reference is made to the description of FIGS. 1 through 6 of this 
application. 
Above, in FIGS. 7 through 13 preferential designs of a single and manifold 
injection mechanism have been described according to the invention, but it 
is evident that within the framework of the invention, several variations 
of the design details are possible. 
The parts which are conceived according to the drawings for servicing with 
the aid of Allen wrenches, can be conceived for servicing with other tools 
such as a screw driver.