JPH0347853Y2 - - Google Patents

Description

[Detailed explanation of the idea]

<Industrial Application Field> The disclosed technology belongs to the technical field of preventing resin clogging of hot nozzles of injection molding equipment. Therefore, in this invention, the hot nozzle of the injection molding device has a heater attached to the outside of the heating cylinder, has a torpedo at its tip, a fixed mold is provided via the heating cylinder and a runner, and the hot nozzle is attached to the heating cylinder. This invention relates to a hot nozzle structure for an injection molding apparatus, in which the tip of a torpedo faces a gate opening in a fixed mold concentrically with the torpedo, and a seal ring is closely fitted into a spigot part of the fixed mold. <Prior Art> As is well known, there are various types of hot nozzle structures with runners in injection molding equipment, but there is no solidification and adhesion of flowing resin to the inner surface of the heating cylinder, and it is easy to operate, maintain, inspect, Externally heated open gate type devices, which are easy to maintain, are widely used, as shown in, for example, the device disclosed in Japanese Utility Model Application No. 60-238513. As shown in FIGS. 4 and 5, the structure of the hot nozzle 2 of the conventional injection molding apparatus 1 is such that a cylindrical heating cylinder 4 with a heater 3 wound around its outer side is concentric with a fixed mold 5. Furthermore, a heating cylinder 4 is slidably fitted into the spigot part 6 of the fixed mold 5 via a seal ring 7 to form a minute clearance of a predetermined dimension, and the heater 3 is heated to a set temperature. A temperature detector 8 for controlling is attached to a set position of the heating cylinder 4, and an extension nozzle 9 screwed and integrated into the upper part of the heating cylinder 4 is provided with a heater 3 wrapped around the outside thereof. , hot runner block 1 at the top end
0 is screwed and fixed. A torpedo 11 protruding and extending from the tip of the heating cylinder 4 is formed concentrically with the runner 12 and opens into the fixed mold 5 to face the gate 13 connected to the cavity. Runner 1 formed by concentrically communicating tubes 4
2′ and the communication hole 14, 1 that connects the runner 12.
4 and 14 are obliquely bored at the bottom of the heating cylinder 4. <Problem to be solved by the invention> However, in the hot nozzle 2 according to the conventional technology, depending on the design conditions such as the size of the heater 3 attached to the outside of the heating cylinder 4, the amount of water flowing through the runner 12' is The temperature of the resin cannot be reliably controlled at the gate 13, and furthermore, as shown in FIG. As shown in FIG. 6, a solidified layer 15 is formed which is cooled by the fixed mold 5, and the resin leaked due to the residual pressure is eventually solidified by air cooling and becomes a solidified film 16. . That is, in the case of the conventional mode, when the resin around the torpedo 11 tries to stay at the interface between the opening of the cavity and the surface of the torpedo 11 and sag due to its own weight, and the sagging position exceeds the tip of the torpedo 11, At that stage, the torpedo 11
Torpedo 1
The deposition progresses below the tip of the film 1, and a thick solidified film body 16 is formed. At this time, assuming that the amount of heat of the torpedo 11 is the same, the formation position of the film body 16 of the solidified film mainly depends on the viscosity of the molten resin. In any case, the solidified film body 16 is always formed in a hanging state, so if the tip of the torpedo 11 is at the same position as the cavity surface, the solidified film will inevitably cover the tip of the torpedo 11. A film body 16 is formed. As a result, so-called resin clogging occurs, which causes the gate 13 to become clogged, making it difficult to open and close the gate 13 relative to the cavity as set.Furthermore, the resin remaining in the gate 13 solidifies due to accelerated air cooling. The layer 15 and the film body 16 of the solidified film gradually grow thicker, and due to the non-uniformity of the solidified layer 15 and the film body 16 of the solidified film, a resistance difference occurs in the form of multi-point gates, etc., and the resistance will be reduced during the next molding. As the resin flows through the areas with less water, the solidified layer and membrane in other areas become thicker.
There was the inconvenience of the gate becoming increasingly clogged. In order to deal with this problem, if the opening diameter of the gate 13 is made smaller, resin clogging occurs and the reliability of the hot nozzle 2 cannot be maintained. And, as shown in FIG. 4, the seal ring 7 is
Although it is minute compared to the fixed mold 5, the above-mentioned problem cannot be solved because it is fitted to the spigot part 6 through a clearance, which has poor insulation against heat conduction from the heating cylinder 4 to the fixed mold 5. However, there was a problem with not being able to reduce the heat capacity of the heater. Furthermore, as a result of the formation of a solidified layer 15 and a solidified film body 16 due to gate clogging, injection pressure loss occurs, so a large-capacity heater 3 is required.
The life of the nichrome wire etc. of the heater 3 will be shortened,
The disadvantage is that maintenance is extremely cumbersome and costs are high. The above-mentioned problems are related to Japanese Patent Application Laid-Open No.
The same applies to the nozzle structures disclosed in No. 31128 and Japanese Unexamined Patent Publication No. 59-31129. The purpose of this invention is to solve the technical problem of the hot nozzle of the injection molding apparatus based on the above-mentioned conventional technology, and to avoid fixing the relative level between the torpedo tip of the open gate type hot nozzle and the gate opening. An object of the present invention is to provide an excellent hot nozzle structure for an injection molding device that prevents gate resin clogging of the cavity and improves the reliability of the hot nozzle, thereby benefiting fields in which molding technology is used in various manufacturing industries. It is. <Means for Solving the Problems> In order to solve the above-mentioned problems, the configuration of this invention, which is based on the above-mentioned claims for utility model registration, is based on the above-mentioned purpose. A fixed mold is provided through the heating cylinder and the runner, a seal ring is interposed between the heating cylinder and the fixed mold, and the tip of the torpedo faces into a gate concentric with the torpedo. The hot nozzle structure of the injection molding equipment is
The tip of the torpedo above protrudes a set amount into the cavity from the opening level of the fixed gate, and the amount of protrusion into the cavity is 0.3 mm or more for molten resin in the case of PP resin material, and in the case of ABS resin material. 0.7 mm or more, and has a hot nozzle structure for an injection molding device in which the seal ring is closely fitted into a fixed spigot part. <Function> During injection molding of molten resin, the open-gate torpedo of the injection molding device is not activated, and the heater attached to the outside of the hot nozzle's heating cylinder uniformly heats the resin flowing through the runner, allowing it to flow through the nozzle. In the process of maintaining the heated state until discharge, and flowing through the gate that opens in the fixed mold and connects to the cavity, the gate is fixed at the level of the tip of the torpedo that extends integrally with the heating cylinder. The tip is made to protrude by a set amount so that it protrudes into the cavity from the level of the mold opening, and when the torpedo tip protrudes in this way, the resin that has stayed in the same way will tend to sag due to its own weight, but As mentioned above, there is a limit to the hanging position of the membrane using the cavity opening as a fulcrum due to its viscosity, so if the torpedo is made to protrude beyond such a position, the amount of hanging beyond the tip of the torpedo will be reduced. A large film cannot be formed, and a film is formed with the tip of the torpedo and the opening of the cavity as fulcrums. At this time, the tip of the torpedo becomes a source of heat, although the value is small compared to the heating cylinder body. By doing so, a thick solidified layer is not formed and the necessary minimum gate seal is possible.
Therefore, if the resin has a high viscosity,
Furthermore, as the amount of possible drooping of the membrane increases, a larger amount of torpedo protrusion is required, and in the case of a material with a low viscosity, such as a PP resin material, the tip of the torpedo is gated. into the cavity from the fixed open end of the
Set the protrusion amount to 0.3 mm or more, and in the case of a material with a high viscosity, such as ABS resin material, set the protrusion amount to 0.7 mm or more to allow the resin to flow into the torpedo cavity depending on the material to be molded. The amount of protrusion of the heater can be freely selected to prevent gate clogging, and a seal ring is tightly fitted to the pilot part of the fixed mold to reduce heat conduction from the heating tube to the fixed mold. This technology takes technical measures to reduce the heat capacity of the hot nozzle and improve the reliability of the hot nozzle. <Example> Next, an example of this invention will be described below based on FIGS. 1 to 3. In addition, 4th to 6th
Components having the same features as those in the drawings will be described using the same reference numerals. Reference numeral 2' denotes a hot nozzle for injection molding, which forms the center of the gist of this invention, and in this embodiment, like the hot nozzle 2 of the conventional injection molding apparatus shown in FIG. A heater 3 such as a well-known band heater is attached to the outer side of the heating cylinder 4, and the heater 3 is attached to the outer side of the intermediate connector 15 as in the above-mentioned conventional embodiment.
A heating cylinder 4' is installed above the heating cylinder 4' and connected to a hot runner block (not shown), and the temperature of the lower heater 3 is controlled by a temperature detector 8 such as a thermocouple attached to a setting part of the heating cylinder 4. Further, the upper heater 3' is also controlled by a temperature detecting section 8 such as a thermocouple attached to the setting portion in the same manner as described above. Further, 12'' is a runner, which is connected to a predetermined resin supply device, also not shown, through a hot runner block, not shown, and allows the resin to flow through it, and connects the heating cylinder 4', the intermediate connector 15, and the heating cylinder 4 concentrically. A bottom 18 is formed in the inner part of the heating cylinder 4.The heating cylinder 4 has an integral torpedo 11' facing the gate 13 of the fixed mold 5. protruding downward,
The tip 11″ is formed into a circular cross section with a predetermined diameter,
Its outer surface faces a concentric ring-shaped gate 13 that opens into the fixed mold 5 via a concentric runner 12, and the tip 1 of the torpedo 11'
1'' is formed to protrude by a length of Δ1 into the cavity 17 from the level of the open part of the gate 13 to the fixed mold 5, as shown in FIG. 3. Also, from the bottom 18 of the runner 12'' In the torpedo 11', two communication holes 14', 14', which are connected to the runner 12 and are spaced at a predetermined distance, are bored in parallel to the torpedo 11' with a set length. The protrusion amount Δ1 of the tip 11'' of the torpedo 11' with respect to the opening connected to the cavity 17 of the gate 13 is set according to the molding resin as shown in the following table.According to experiments, the protrusion amount Δ1 is determined by the molding resin material. In combination with this, gate clogging can be prevented.
A stable supply of molten resin can be ensured.

[Table] A seal ring 7' is provided concentrically around the lower end of the heating cylinder 4 and the outer part of the upper part of the torpedo 11'. The corresponding part of the fixed mold 5 is formed in a concave spigot part 6 upward in the figure, and the heating cylinder 4 has a seal ring 7' that can be slid freely on the spigot part 6 of the fixed mold 5, but it is not in a close state. It is fitted and supported to reduce heat conduction from the heating cylinder 4 to the fixed mold 5, and to reduce the heat capacity of the heaters 3, 3'. In the above configuration, when the heaters 3 and 3' are heated by controlling the temperature detector 8 such as a thermocouple,
The heating cylinders 4, 4' are heated to a predetermined temperature, and in that state, molten resin is supplied from a hot runner block (not shown) to the runner 12'' in a set cycle via a resin supply device (not shown), and the molten resin is supplied to each communication hole 14'. A seal ring is tightly fitted between the heating cylinder 4 and the fixed mold 5 to reduce heat conduction from the former to the latter. By doing so, the heat capacity of the heaters 3, 3' can be reduced.At this time, since the heating cylinders 4, 4' are in a heated state, the resin does not solidify and adhere to the inside of the heating cylinders 4, 4', and the heating process is smooth. Gate 13
As shown in FIG. 3, is a gap formed by the protrusion amount Δ1 of the tip 11'' of the torpedo 11', which extends downward at the part opened to the fixed mold 5 and whose tip has a predetermined diameter. In the case of a material with a low viscosity of the flowing resin, such as a PP resin material, by setting the protrusion amount Δ1 to 0.3 mm or more,
The solidified layer 15 cooled by the fixed mold 5 and the resin 16' leaked due to residual pressure are removed from the tip 1 of the torpedo 11'.
1". On the other hand, in the case of a material with a high viscosity, such as an ABS resin material, the protrusion amount Δ1 is
By setting the value to 0.7 mm or more, the air cooling solidification of the molten resin is made slower and the solidified thickness of the molten resin is 1
5 can be prevented from increasing, and as a result, fluctuations in the flow rate of the molten resin and pressure loss do not occur, and the molten resin can be stably supplied to the cavity 17. Furthermore, since the torpedo 11' is formed on the heating cylinder 4, the temperature is raised by the heater 3 through thermal conduction, and the resin does not solidify and adhere, thus preventing the gate 13 from clogging. The flow and stopping of the molten resin during the molding cycle is also performed accurately. The seal ring 7' that supports the heating tube 4 slidably on the spigot part 6 of the fixed mold 5 is attached to the fixed mold 5.
The runner 12 is tightly fitted into the spigot part 6 of the runner 12, and is concentrically arranged around the lower end of the heating cylinder 4 and the outer part of the upper part of the torpedo 11'. prevent,
In addition, the heat transfer from the heating cylinder 4 to the fixed mold 5 is reduced, allowing the resin to flow smoothly, and the heating cylinder 4 and the intermediate connector 15 are not damaged, and the hot nozzle 2' is Durability is improved, maintenance of the injection molding equipment is facilitated, and the reliability of the finished product can also be improved. In addition, the heating tube 4 is heated by the seal ring 7' being closely fitted to the spigot part 6 of the fixed mold 5.
By reducing heat conduction from the fixed mold 5 to the fixed mold 5, it becomes possible to reduce the heat capacity of the heaters 3, 3'. According to experiments, when molding was performed with the protrusion amount Δ1 set to 0.8 mm in the case of PP resin and 1.2 mm in the case of ABS resin, extremely satisfactory data was obtained in preventing gate clogging. It goes without saying that the embodiments of this invention are not limited to the above-mentioned embodiments; for example, the diameter of the communication hole may be adjusted depending on the material of the viscosity of the flowing resin, or the flowing speed of the molten resin may be changed. Various aspects can be adopted, such as: <Effects of the invention> As described above, according to this invention, in the structure of an open gate type hot nozzle that basically does not operate the torpedo of the injection molding device, a predetermined gap formed between the tip of the torpedo and the gate with respect to the cavity. However, unlike conventional methods, it is necessary to heat the heater above a predetermined temperature or cool it below a predetermined temperature through the control operation of a temperature sensor depending on the material of the material being molded, which has a large or small viscosity. However, in the case of PP resin material, which is a material with a low viscosity, the flow can be controlled by setting the amount of protrusion from the torpedo gate opening to the cavity to 0.3 mm or more. It is possible to prevent excess resin from covering the torpedo tip, and in the case of ABS resin material, which is a material with a high viscosity, the protrusion amount is set to 0.7 mm or more so that the solidified layer also covers the torpedo tip. As a result, there is no gate clogging of the cavity and the excellent effect of being able to stably supply the molten resin is achieved. By selecting the amount of protrusion of the torpedo from the gate opening to the cavity depending on the viscosity of the flowing resin, the solidified layer of the flowing resin does not cover the tip of the torpedo, thereby preventing flow rate fluctuations and pressure loss. The effect of being able to do this was achieved,
In addition, the heater does not heat up beyond the specified level, thus eliminating heat transfer to unnecessary parts, requiring a smaller heater capacity, and improving the durability of the nichrome wire and temperature detector. It also has the effect of being able to do so. At the tip of the heating cylinder, a seal ring is fitted closely to the spigot part of the fixed mold, which reduces heat conduction from the heating cylinder to the fixed mold, making it possible to reduce the heat capacity of the heater. This has the effect of Furthermore, mechanical damage to the hot nozzle is eliminated.
Another advantage is that maintenance and management of the injection molding equipment can be performed smoothly and costs can be reduced. Since the heating cylinder and fixed mold are in uniform surface contact via the seal ring, heat from the heating cylinder is not transferred to the fixed mold, preventing leakage of molten resin and further improving sealing performance. It has the effect of being able to

[Brief explanation of drawings]

Figures 1 to 3 are explanatory diagrams of one embodiment of this invention. Figure 1 is a sectional view of a hot nozzle of an injection molding device, Figure 2 is an enlarged sectional view of section A in Figure 1, and Figure 3 is a torpedo. The solidified state of the tip is a cross-sectional view. Figure 4 and the following are explanatory diagrams based on the conventional technology. Figure 4 is a cross-sectional view equivalent to Figure 2, Figure 5 is a cross-sectional view of Figure 4, and Figure 6 is a gate clogging. FIG. 3...Heater, 4...Heating tube, 11'...Torpedo, 12...Runner, 2'...Hot nozzle, 11''...Tip, 5...Fixed type, 13...
Gate, Δ1...Protrusion amount, 17...Cavity,
6... Pilot section, 7'... Seal ring.

Claims (1)

[Scope of utility model registration request] A heating cylinder having a heater on the outside has a torpedo at its tip, a fixed mold is provided via the heating cylinder and a runner, and a seal ring is interposed between the heating cylinder and the fixed mold, and the seal ring is interposed between the heating cylinder and the fixed mold. In a hot nozzle structure of an injection molding device in which the tip of the torpedo faces into a gate concentric with the torpedo, the tip of the torpedo protrudes a set amount into the cavity from the opening level of the fixed gate, and the tip of the torpedo protrudes into the cavity by a set amount. For molten resin, the protrusion amount is 0.3 mm or more for PP resin material, and for ABS resin material.
1. A hot nozzle structure for an injection molding device, characterized in that the seal ring has a diameter of 0.7 mm or more, and the seal ring is closely fitted into a fixed spigot part.