JPH0442098Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a screw for resin molding of an injection molding machine, and particularly to a screw that can reduce noise generated when the resin is lightweight.

[Conventional technology]

Generally, an injection molding machine, as shown in Fig. 5,
A screw 12 is disposed in the barrel 10, and the raw material 16 in the hopper 14 is heated and compressed in the supply/compression zone Za, melted and measured in the metering zone Zb, and then passed through the injection zone Zc to the nozzle 1.
8. and,
The barrel 10 is provided with a heater 20 for heating the raw material on the outer peripheral surface of the supply/compression zone Za. On the other hand, in the metering zone Zb, when the raw material is melted in this zone, the flight 2 of the screw 12 is
Since the heating element 6 is subjected to a strong shearing action, internal heat generation occurs and the temperature rises. Therefore, a heater 24 including a cooling device for cooling this temperature rise to a predetermined temperature is provided.

However, in the conventional injection molding machine, one difficulty is that in the cooling operation in the aforementioned metering zone Zb, the molten raw material is cooled from the barrel 10 side, that is, from the outside of the molten metal, so the molten metal in this part is not supercooled. At the same time, the viscosity increases and the driving torque of the screw 12 increases.
Even if the rotational speed of the screw 12 is increased, the injection amount cannot be increased accordingly.

In order to solve these difficulties, a technique (hereinafter referred to as an improved technique) has been proposed, for example, as disclosed in Japanese Utility Model Application Publication No. 175428/1983. According to this, as shown in Figure 6,
The flight 26 of the screw 12 has a width W in the range of 1/300 to 1/20 of the diameter D of the screw 12, and more preferably has a back surface inclined at an angle α in the range of 10° to 80°. 26a. That is, the width Wa of the top surface of the flight 26 that applies shear force to the raw material 16 to melt it is significantly reduced compared to the conventional width. Therefore, according to such a configuration, the temperature rise of the molten raw material in the above-mentioned metering zone Zb is suppressed, and as a result, heating and
Cooling by the cooler 24 is reduced, and difficulties such as an increase in the driving torque of the screw 12 described above are reduced.

[The problem that the idea attempts to solve]

However, even with the above-mentioned technology, the following fundamental difficulties inherent in injection molding machines have not been solved.

In other words, in the screw of an injection molding machine,
Particularly in the metering zone, a strong shearing force acts between the top surface of the screw flight and the inner surface of the barrel as described above, but this shearing force not only increases the temperature of the molten raw material as described above, but also increases the When the shear force becomes unbalanced with respect to the flight circumference, interference occurs between the flight and the barrel.

This interference first of all causes the injection molding machine to produce irregular and unpleasant noises, or squeals. FIG. 7 is a graphical representation of the squealing noise of the conventional screwdriver including the above-mentioned improved technology, and as can be seen from the figure, the measurement zone Zb
The average value of the squealing sound reached approximately 80 dBA, and the amplitude varied irregularly between high and low levels of approximately 14 dBA. Moreover, the interference further causes galling between the flight and the barrel, increasing the driving torque of the screw and shortening the life of the entire injection molding machine.

Therefore, the purpose of the present invention is to suppress the temperature rise of the molten raw material, especially in the metering zone, and at the same time,
To provide a screw for resin molding that can prevent interference between the screw and the barrel, thereby further reducing the driving torque of the screw, and effectively reducing the squealing noise of an injection molding machine.

[Means to solve the problem]

In order to achieve the above objective, the resin molding screw of the present invention has a flight width of 1/10 to 1/10 of the screw diameter in the resin molding screw of an injection molding machine.
It is characterized in that the thrust side of the flight is inclined within a range of 10° to 40° from the top shoulder of the flight.

In this case, the width of the top surface of the flight is preferably set in a range of 1/2 to 1/3 of the width of the flight.

[Effect]

According to the screw for resin molding of the present invention, the top surface of the flight is set to be extremely narrow, so that
The shear stress on the raw material between the top surface of the flight and the inner surface of the barrel is reduced, and therefore the temperature rise of the molten raw material is suppressed. Furthermore, since the flight has an inclined surface on its thrust side, the molten raw material flows between the top surface of the flight and the inner circumferential surface of the barrel through the inclined surface, and performs a lubricating effect on the barrel of the screw. It performs a centering action, thus preventing interference between the screw and the barrel. That is, the driving torque is reduced and the squealing noise is effectively reduced.

〔Example〕

Next, an embodiment of the screw for resin molding according to the present invention will be described in detail below with reference to the accompanying drawings. For convenience of explanation, the same reference numerals are given to the same components as in the conventional structure shown in FIGS. 5 and 6, and detailed explanation thereof will be omitted.

First of all, the structure of an injection molding machine to which the resin molding screw according to the present invention is installed is the same as the conventional structure shown in FIG. That is, in FIG. 5, the resin molding screw 12 of the present invention is disposed in the barrel 10, and the raw material 16 in the hopper 14 is
It is configured to be heated and compressed in the supply/compression zone Za, melted and metered in the metering zone Zb, and then injected into the nozzle 18 through the injection zone Zc. The barrel 10 is provided with a heater 20 in its supply/compression zone Za, and a cooling/heater 24 in its metering zone Zb.

However, the screw 12 for resin molding of the present invention
As shown in Figure 1, flight 30 is
An inclined surface whose width W is in the range of 1/10 to 1/20 of the diameter D of the screw 12, and whose thrust side is inclined at an inclination angle β in the range of 10° to 40° from the corner of the top surface 30a. 30b. In addition, flight 30
The width Wa of the top surface of is preferably 1/2 of the flight width W.
It is set in the range of ~1/3.

According to the screw 12 of the present invention having such a configuration, the top surface 30a of the flight 30 has a width Wa.
The measuring zone Zb is configured to be extremely narrow.
The temperature rise of the molten raw material is effectively suppressed. Therefore, the cooling by the cooler/heater 24 is reduced, and supercooling of the molten raw material in contact with the inner circumferential surface of the barrel 10 is prevented, that is, an increase in the viscosity of the molten raw material in the aforementioned portion is prevented. Drive torque is reduced.

Furthermore, since the flight 30 has a thrust surface 30b, a thrust F is generated in the molten raw material 16M by the slope 30b, as shown in FIG. One component force Fa of this thrust force F moves the molten raw material 16M to the top surface of the flight 3.
0a and the inner circumferential surface of the barrel 10, and the other component force Fb acts on the screw 1
2 relative to the barrel 10. Therefore, the screw 12 rotates smoothly without being interfered with by the barrel 10 and being lubricated by the molten raw material 16M. As a result, the driving torque is further reduced and at the same time, the squealing noise is almost completely eliminated. Furthermore, as shown in FIG. 3, the inclined surface 30b prevents the solid raw material 16S supplied from the hopper 14 into the barrel 10 from being caught in the flights 30 in the hopper portion, further promoting the above-mentioned result. do.

FIG. 4 shows the above-mentioned effects, especially the effects on squealing noise, using a similar graph for comparison with the conventional example shown in FIG. According to this Figure 4, the average value and amplitude of the squealing sound in the measurement zone Zb are approximately 72 dBA and 3.5 dBA, respectively.
, respectively in the conventional example shown in FIG.
It is clear that both 80dBA and 14dBA are significantly reduced.

In this way, according to the screw of the present invention, it is possible to suppress the temperature rise of the molten raw material, and
Furthermore, interference between the screw and the barrel can be reliably prevented. Therefore, the driving torque of the screw can be significantly reduced, and the squealing noise of the injection molding machine can be almost completely eliminated.
Moreover, the life of the entire injection molding machine can be extended.

Although the present invention has been described above with reference to preferred embodiments, the present invention is not limited to the above-mentioned embodiments, and it goes without saying that various design changes can be made without departing from the spirit of the present invention. be.

[Effect of idea]

As explained above, in the resin molding screw according to the present invention, the width of the flight is set to 1/1 of the diameter of the screw.
10 to 1/20, and the thrust side of the flight is configured to be inclined in the range of 10 to 40 degrees from the top shoulder, so it is possible to suppress the temperature rise of the molten raw material and Furthermore, interference between the screw and the barrel can be reliably prevented.
Therefore, the driving torque of the screw can be significantly reduced, and the generation of squealing noise from the injection molding machine can be almost completely eliminated. Moreover, the life of the entire injection molding machine can be extended.

[Brief explanation of the drawing]

Fig. 1 is an enlarged sectional view corresponding to the section taken along the line A-A in Fig. 5 for explaining an embodiment of the screw for resin molding according to the present invention, and Fig. 2 is an illustration for explaining the operation of the molten raw material. Therefore, FIG. 3 is a cross-sectional view that is a further enlarged version of FIG. 1, and FIG. 3 is a sectional view taken along the line B--B in FIG. FIG. 4 is a graph illustrating the squealing noise in an injection molding machine equipped with the resin molding screw according to the present invention shown in FIGS. 1 to 3, and FIG. FIG. 6 is a schematic cross-sectional view showing the configuration of an injection molding machine, and FIG.
FIG. 7, which is an enlarged cross-sectional view corresponding to the section taken along the line A, is a graph illustrating the squealing noise in the injection molding machine equipped with the conventional resin molding screw shown in FIG. 6. 10... Barrel, 12... Skrill, 14...
Hotsupa, 16...Raw materials, 30...Flight, 30
a...Top surface, 30b...Slope surface, W...Flight width, Wa...Top surface width, Za...Supply/compression zone,
Zb...Measuring zone, Zc...Injection zone, β...
Tilt angle.

Claims (1)

[Scope of claims for utility model registration] (1) In the screw for resin molding of an injection molding machine,
A resin molding characterized in that the width of the flight is in the range of 1/10 to 1/20 of the diameter of the screw, and the thrust side of the flight is inclined in the range of 10° to 40° from the top shoulder. Screw for. (2) The screw for resin molding according to claim 1, wherein the width of the top surface of the flight is in the range of 1/2 to 1/3 of the width of the flight.