JPH05507445A - Improved hot runner mold construction and its use - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Improved hot runner mold structure and its technical field of use The present invention combines a plurality of needle valves, specifically a spring biased needle valve. An improved runnerless, or hot runner, mold structure and a phone using this structure. The present invention relates to a tranner injection molding method, preferably a holding chamber type injection molding method.

Background technology Holding chamber systems for injection molding of plastic materials and mold gauges used in injection molding Spring-biased needle valves that open and close ports are known.

This spring biasing means provides a valve drive means that is consistent with melt pressure during injection molding. Ru.

As an alternative to the spring bias type, there are known valve drives such as hydraulic, pneumatic, and electromagnetic types. There is a means of movement.

Known injection molding machines are equipped with means for plasticizing, metering and injecting plastic materials. Machine body, nozzle forming a nozzle flow path from the machine body, and multiple launches and gates The mold structure has a mold structure defining a cavity having a diameter. The mold structure is inside the machine body and the mold cavity through a nozzle channel including a runner. It is combined with sea urchin. Injection molding machine: Plasticized material is plasticized and weighed during each shot cycle while heating the machine body. Process; This thermoplastic material is injected under pressure into the mold cavity through a nozzle channel. Process; cooling the mold structure, thereby providing a molded article therein, and while cooling; A process in which at least a portion of this thermal radiation material is retained under pressure within the entire mold cavity. The injection molding method is carried out including steps.

By using such an injection molding machine, the method with the above characteristics has not been possible until now. It can be applied in widely used non-pressurized chamber systems. In this system , the nozzle flow path remains open to the machine body even after the injection process, and the holding pressure is maintained within the injection machine itself. This is provided by its own scree injection plunger.

However, compared to the widely used systems mentioned above, the shortening time is significantly shorter. This type of injection molding is equipped with a pressure holding chamber system that increases productivity through short cycle times. More preferably, the above features are applied using a shaping machine. Due to this pressure chamber system For example, in the nozzle flow path, a material holding process is performed after the injection process. During this time, the communication between the machine body and the mold cavity is cut off, and this nozzle As soon as the flow path is shut off, or after that, the plasticizing and metering process will be restarted for the next shot, i.e. injection. It is carried out by an injection machine.

There are three types of pressure chamber systems.

One type is disclosed in EP 0204133A1, GB Patent No. 888,448, etc. and in this system: the piston cylinder cooperates with the nozzle flow path to The mold cavity and nozzle are closed spaces whose volume changes according to the stone stroke. The nozzle flow path can be blocked by a combination of flow paths or this combination and a piston cylinder. in the disconnected state; and in the packing process. As soon as the injection material packed in this closed space blocks the nozzle flow path, the piston cylinder External holding pressure is applied by

Another type of system is the International Application H (English) No. P (:T /JP89101052. In this system, the pressure The closed space consisting of the cavity and the front part of the nozzle flow path that follows it is the nozzle flow path. The volume is fixed in the closed state, which causes the injection material packed in this closed space to maintain internal pressure. Let your power play out.

The third type system is an improved version of the second type system, which was also developed by the applicant. It is disclosed in the International Application No. PCT/JP90100300 (English) filed by the applicant. Ru. This system has the above-mentioned internal pressure chamber system, which is fixedly closed at each shot. If the material packed in between blocks the nozzle flow path, or if there is an excess of the stuffed material The portion, if any, is reweighed or adjusted by expelling it out of the system.

U.S. Pat. No. 3,800,027 discloses a tip having a probe with an axial tip. Discloses the first sharp-edge heat generating module, U.S. Pat. No. 4,643,66 No. 4 discloses an improved version of this first module.

Conventional modules require cold storage of deformable material in an axial gate for injection molding. This is very effective for opening the gate by temporarily and instantaneously heating the area. This cold material The molding part is a part that is integrated with the molded product inside the cavity, but when the mold is opened, The heat residue inside the mold structure, which is later separated from this to remove the molded product, It is in one piece with the material part.

The module has a material flow channel formed inside with an outlet near the axial tip. The hot runner mold has a long body and this flow path communicates with the nozzle of the injection machine. The launch is in communication with the axial gate so that the hot material exits the nozzle and enters the mold cavity. Iheranna is then allowed to flow through the annular gap formed in the axial gate. ing.

A local area of cold material fills this annular void, which is affected by the axial gate and axial quantum It is designed to have a relatively small thickness relative to the knob. Therefore, cold material The localized portion of the material can be easily and quickly melted by instantaneous heating of the axial tip.

According to the prior art, the above-mentioned pressure holding chamber system includes a plurality of this kind of sharp-edged intermittent heat generation modules. joules, which are used to create multiple runnerless molded products at the same time. The runner is incorporated into the runner within the nozzle flow path to perform injection molding.

This module has multiple components that control the timing of instantaneous heating of the chip. Requires a complicated and expensive controller. These chips are Immediately and simultaneously heated just before injection. This chip heating is done by the cold material at each gate. It is desirable to have the effect of instantaneously and simultaneously melting the materials, but in reality this is not possible. It is not easy to obtain such effects. Furthermore, this cold material at the gate Contrary to expectations, there is a problem in that it is not effective as a plug for closing the gate. this From the viewpoint, the nozzle is pulled back together with the machine body relative to the mold structure and inside the launch. sac bank with a decrease in melt pressure, thereby reducing the amount of cold material at the gate. Together, they prevent melt dripping from occurring when the cavity mold is opened. This is commonly done. Cooling at the gate can be reduced by increasing the chip length. It is also possible to improve the plug effect of the material and omit the Santa-back rubbing. death However, another problem is that it is not easy to instantaneously melt the long cold material at the gate. There is a problem. As a result, this long cold material is accompanied by a trailing hot material, i.e. melt. Therefore, it tends to move into the cavity without being completely melted just before injection. child This causes the cold material to damage the molded product. In this current situation, molding The desired effect of opening and closing the gate without causing this kind of damage to the product. To provide modules and controllers that can be combined to achieve maximum performance at low cost. is not easy.

The above-mentioned spring-biased needle valve for opening and closing the gate is used in non-pressure chamber systems. has been commonly used until now. This type of valve is also called a nozzle valve, and there are numerous patent documents. , for example, as disclosed in Japanese Patent Publication No. 62-13889 and Japanese Patent Application Laid-Open No. 5L65639. There is. These needle valves each have separate springs housed in the runner mold. a launch formed within the runner mold and configured with a biasing means; is activated by changing the melt pressure of the

Conventionally, there has been a piston-cylinder type needle valve as another type of needle valve. oil, air Alternatively, multiple electromagnetic piston cylinders can be installed in the runner mold to actuates the individual needle valve bodies to open and close the gates.

With the above two types of needle valves, it is actually easy to synchronize the opening and closing operations of multiple valve groups. They have a common problem that they are not. Inability to synchronize valves can cause multiple motors to The weight of products molded simultaneously in the mold cavity may fluctuate significantly or defects may occur. This results in the creation of a tangible product.

Each needle valve has separate means for driving its needle valve, the driving means being Because they occupy substantial radial space, multi-cavity molds and runner molds If the valve is forced to have a radial size as large as possible to accommodate these valves, There is another common problem. Furthermore, the valve drive means is generally a runner mold. The runner mold is designed to incorporate these valve drive means in order to install the device inside the valve. It's not easy to do.

Disclosure of invention SUMMARY OF THE INVENTION It is an object of the present invention to provide various To provide an improved mold construction for use in types of real runner injection molding. There are many things.

Another object of the present invention is to use the improved mold construction of the present invention to Hot runner injection in a holding chamber system for simultaneous production of molded parts The purpose is to provide a molding method.

According to the present invention, gates defined within a plurality of mold cavities are opened. Hot runner mold assembly combined with corresponding needle valve groups for closing In this case, these needle valve groups share a common valve driving means provided outside the mold structure. A hot runner mold structure is provided.

In this case, the answering needle valve body is inserted into the mold structure from the inside of the mold structure to its outside. provided extending outward through a corresponding hole formed and cooperating with the gate. It has a free end forming a valve head for controlling the valve and the other end fixed to an external valve driving means. Ru.

The valve drive means may be hydraulic, pneumatic, electromagnetic or spring biased.

For mold constructions combined with spring-biased needle valves, the present invention provides the following: A mold structure is provided below.

A mold for use in the above hot runner injection molding provided by the present invention The structure defines a plurality of cavities each having a gate extending in the axial direction. Cavity mold; removably connected to the cavity mold; The axially extended front of the injection machine forms the corresponding gate and nozzle of the mold A manifold forming a group of runners extending in multiple axial directions and communicating with the runner mold containing; and varying the melt pressure to open and close the corresponding gate group It consists of multiple spring-biased needle valve groups that are activated by Ru. The response comprises an axially extending valve body in the form of a needle or probe. This valve body has a corresponding valve which wanders as a valve chamber with a radial gap therebetween. inserted into the connector. This needle valve body has a valve head at its front end, and this valve head is Interact with the corresponding gate. Each needle valve body is located axially and rearward from the runner mold. extending in the direction through a corresponding hole drilled therein and through this hole in the axial direction radially relative to the hole such that it is movable to the hole but makes this hole substantially airtight. Compatible with The plurality of needle valve groups are further configured to make the bore substantially airtight. It includes common means for These needle valve groups are also attached to the outside of the runner mold. The first stopper provided on the outside of the runner mold In contrast, the needle valve body is biased so that the valve head group closes the gate group. and a common biasing means.

This common biasing means is a radially extending plate provided on the outside of the runner mold. and a needle valve body group with respect to the stopper provided on the outside of the runner mold. to bias or urge the valve head group to close the gate group. It may also include a common flange that is movable in the axial direction of the two.

Preferably, this common biasing means is a radially disposed external part of the two runner mold. A flange of an extending plate from which the needle valve body extends forward. , such an axially movable common flange; there is an axis between the outside of this flange plate and Fixed common spring seat of radially extending plates arranged with directional gap; valve The front and rear positions in the axial direction of the movable flange plate corresponding to the common opening and closing positions of the group are respectively regulated. a second stopper provided so that the Also, a means for supporting the movable flange plate in the radial direction and guiding it in the axial direction; is biased or biased against the first stopper relative to the spring seat plate. A plurality of sprues extending in the axial direction are provided in the gap between the flange plate and the spring seat plate. It is composed of

The common biasing means further adjusts the coiled primary spring with respect to its axial length; comprising means for adjusting the total spring force acting on the flange plate by the Ru. The spring seat plate is inserted into the combination of the nozzle and the rear hollow extension of the runner mold. It has a central hole.

The flange plate has a central hole coaxial with the central hole of the spring seat plate. Preferably, The ring adjustment means: extends rearward from the flange plate and surrounds its central hole. It comprises an empty bolt; and an adjustment nand screwed onto the bolt. hollow bolt , the main coil spring is surrounded by this, and the standard is inserted between the adjustment nut and the spring seat plate. located in a defined axial gap.

Preferably, the support guide means includes a plurality of axial rods extending forward from the spring seat plate. It consists of: At least some of the rods have a coil type other than the main spring. An axial spring is wound around it.

These spring-wound rods are inserted into corresponding holes drilled in the flange plate, It fits slidably into this hole.

Preferably, the remaining rods are step-shaped, each having a hole in the flange plate. a shoulder providing a front part and a second stomper axially slidable in corresponding holes in the It has a shaped rear part.

Fixed the axial position of the spring seat plate relative to the runner mold and cavity. Spacer means may be provided for providing the first stop. This first stopper is in contact with the flange plate in the closed position of the valve group. I will come into contact with you.

Preferably, each needle valve body is threaded into a corresponding threaded hole drilled in the flange plate. The front part of the valve body extending from the flange plate is connected to its axis. Adjust with respect to direction.

To open and close the gate, each needle valve group is activated by a different melt pressure. For this reason, each needle valve body has a front part forming a frustoconical tip at its front end, and It then has a large-diameter adjacent portion that expands into a stepped shape. This enlarged part is a flange plate radially fits into the corresponding hole of. This flange plate is used when injection is done. , due to the melt pressure in the runner, it moves toward the second stopper along with all the needle valve bodies. move in the axial direction and open all gate groups. This melt pressure is It acts on the total difference cross section between. From this relationship, the total spring force and valve system produce A predetermined melting force is generated that resists the resultant force of the flange plate. The total difference is large enough to open all the gates and start moving backwards. Preferably, the cross-sectional area is designed.

Preferably, the runner mold includes a plurality of axial front extensions, each having a A runner is formed on the runner, and a body heater is provided near the runner.

Each gate is formed into a corresponding front extension instead of a cavity mold. Each needle valve body may have a built-in body heater, but the runner mode Each axial front extension of the mold is adapted to heat the material intermittently and instantaneously. If a chip heater is installed near the gate, the above-mentioned Body heaters are not required.

These heaters are generated at the gate and applied to the valve head when the gate is opened. 11! Provided to reduce friction.

A corresponding valve body is radially fitted into a corresponding hole in the mold, preferably An additional heater is installed near the periphery of this hole to prevent the increase in friction that occurs in this hole. I'll do what I do.

As an alternative to the above additional heater in the runner mold, another additional heater may be installed in the runner mold. The same effect as above can be obtained by placing the needle valve body part that fits radially into the hole in the mold. It may be possible to make the effect more effective.

The needle valve of the present invention may be a valve seat type in which the valve head abuts against the gate in the valve closed position. Ru. Alternatively, when the gate is closed, the valve head is inserted into the gate and the valve is opened in half. It may also be of the spool type that fits the gate in the radial direction. In either of these cases When the valve is in the open position 1, the valve head moves forward and enters the cavity. It may also be something that is forced.

However, it is better to have the valve head retract from the gate into the launch when the gate closes. More preferred, this is because the valve head does not damage the molded part, whereas the former case If the valve head is, the molded product will be damaged in the local area corresponding to the gate. .

Each valve head is cylindrical rod-shaped, and the corresponding gate is For such spool-type valves that define a matching cylindrical hole, the gate A plurality of axial grooves formed at the rear of the gate around its axis in its cylindrical surface. The rear part of the gate coaxially holds the cylindrical valve head in the valve open position. so that the front part of the gate can communicate with the corresponding launch through these axial grooves. It is preferable to do so.

Regarding the needle valve body, this is not a single component, i.e. one part, but two separate parts. In the case of single-piece valve bodies, straight sealing holes in the runner mold may be In contrast to having a single shaft, in the case of a two-part valve body, the corresponding airtight holes are mutually connected. It is of stepped type with front and rear sections having eccentric and different axes. Ru. This front part of the valve body fits radially into the front bore section, but the rear part of the valve body The product has two valve bodies inserted into the rear hole section with a radial gap between them. The parts have radially extending end faces where both parts are subject to melt pressure and spring force. During this contact, the rear parts move between the different axes of the two parts. Allows for radial movement relative to the front part within the radial gap There is. Therefore, the two-part valve body with stepped airtight holes is not suitable for the runner mold. In cases where there is a relatively large difference in thermal expansion between the members before and after the runner mold due to thermal expansion. Reduces resistance and ensures smooth valve operation during long-run injection molding There is an advantage to this. This type of differential thermal expansion causes reciprocating movement through the hermetic hole in the valve body. tends to increase resistance to resistance. In the case of single-component discs, this differential thermal expansion Two types of parts tend to be bent relative to their original axis due to tension. In the case of a valve body, the radial relative movement of the rear part with respect to the front part results in this different thermal expansion. is allowed to occur to compensate for the increase. The fixed spring seat plate is heated or As long as the runner has a good thermal connection to the mold body, this kind of different thermal expansion is reduced to a level low enough to virtually ensure smooth valve operation with a single-piece valve body. It can be done.

In the above mold structure of the present invention, synchronization of gate opening is ensured for each shot, and the synchronization of gate opening is ensured for each shot. The radial space occupied by the valve within the Namold is smaller than that of a conventional valve. and decrease significantly. That is, since the valve biasing means is located outside the runner mold, , each launch accommodates only a needle valve body. This biasing means prevents melts within the runner. and/or undamaged by the thermal energy applied to the runner mold. There is another advantage to this.

Furthermore, the spring force and length of each valve body can be easily adjusted as required; However, prior art valves are not capable of this type of adjustment.

The mold structure of the present invention is applicable to widely used non-pressure holding chamber systems and pressure holding chamber systems. It can be used effectively and beneficially in both systems. For non-pressurized chamber systems, this The mold construction of the invention can be used in the same manner as conventional real runner mold constructions.

From this point of view, according to the invention, a pressure chamber system is used as follows.

According to the invention, at least one, preferably multiple mold keys with gates are provided. Hot runner injection molding method using the above-mentioned second type pressure holding chamber system including a cavity The spring for opening and closing the gate is activated by changing the melt pressure. The combination of friction and spring produced by this system uses a bias-biased needle valve. The gate is forcibly opened by injecting the material that applies melt pressure to the , the gate is kept open during the pressure holding process when the melt pressure decreases, and the nozzle flow is Close the gate by releasing the path block and thereby further reducing the melt pressure. A method is provided, characterized in that:

In the above method, metering is completed during nozzle flow path interruption, after which this interruption Released to close the gate. Alternatively, during the nozzle flow path interruption, the initial stage of metering The final step of metering is when the nozzle flow path block is released and the gate is closed. May be executed.

This method is used in the above-mentioned type 3 pressure holding chamber system, where reweighing is performed in the pressure holding chamber. It may be applied when

Hot runner injection molding method according to the present invention for the above-mentioned type 1 pressure holding chamber system The piston cylinder associated with the pressure holding chamber is activated to increase the melt pressure to open the gate. It is characterized by decreasing the

Brief description of the drawing FIG. 1 is a sectional view showing a hot runner injection molding machine of the present invention with an internal pressure chamber system type. 2 shows examples of two types of mold structures; FIG. 2 shows one example of the mold structure in FIG. FIG. 2 is an exploded perspective view showing a part of the assembled spring-biased needle valve group of the present invention; FIG. 3 is an enlarged sectional view showing the rear part of the needle valve shown in FIG. 1; FIGS. 4A and 4B; is an explanatory view showing an enlarged cross section of the gate of the mold structure shown in FIG. 1 and the valve head of the valve; FIG. 5 is an explanatory diagram partially showing another example of the hot runner mold structure according to the present invention. can be; Figure 6 shows a combination of a spool valve type valve head and gate that is incorporated into the mold structure of Figure 5. FIG.

BEST MODE FOR CARRYING OUT THE INVENTION Figure 1 shows a real runner injection molding machine for an internal pressure holding chamber system according to the present invention. Ru. However, regarding the mold structure built into this injection molding machine, the upper half of the diagram Two examples are shown in the lower half.

In Figure 1, the real runner injection molding machine is a conventional single-hole injection molding machine 1 and this one. It has a mold structure 10 combined with. The injection machine 1 has a sac bar at the nozzle 22. It is movable in the axial direction to allow for locking. For injection, visibility and metering operations The injection machine has a barrel 2 with a screw plunger 3 inside, this plunger A piston cylinder (not shown) equipped with a piston connected to the carrier 3, and a no. It comprises a cylindrical hollow cylinder extension body extending forward from the handle 2. Mold structure The adult body 10 is formed by combining a cavity mold 11 and a manifold 13a inside. It includes a runner mold 13. The cavity mold 11 is a fixed half mold 11a (shown) and a movable half-mold (not shown), both of which have cooling means, and a molded product group. Has multiple mold cavities for cloudy The runner mold 13 has heating means 15. Each cavity has gate 11B have. The fixed half mold of the cavity mold 11 is attached to the runner mold 13. Connected removably.

The hollow extension 20 has three parts: a front part 21, the so-called "sublube body", a middle part The piston part 220 includes a "nozzle" inserted in the axial direction into the so-called sprue bush, and a nozzle. It is divided into a rear part 23 connected to a nozzle 22. This cylindrical hollow extension body 20 is It is equipped with a band heater around it.

In this combination, the hot runner mold 13 and the cylindrical extension body 20 of the injection machine 1 form a barrel. A hollow nozzle flow path Y was defined to communicate the inside of 2 with the cavity gate IIB. It constitutes a hollow extension.

The rear cylindrical extension 23 is associated with valve means 40. The nozzle flow path Y is a valve means 40 An internal pressure holding chamber X is formed between the cavity gate 11B and the cavity gate 11B.

The intermediate piston part 22 of the cylindrical extension body 20 is connected to the cylindrical body and its abutting end surface against the front part 21. It acts as a stopper in the process and prevents hot melt from leaking during material injection. It consists of an annular flange arranged to act as a gas-tight or sealing means.

The relative axial position of the nozzle 22 with respect to the front part 21 is such that the flange is in contact with the front part 21. It is fixed when it comes into contact with the end face. The injection machine l is located at the above position along with the nozzle 22. It is sucked back by a predetermined stroke.

The valve means 40 is a drive means, for example, a pulse motor (not shown) provided in the cylindrical rear part 23. ) and a circular valve stem 42 extending vertically from the motor. It has a vertical circular hole 30 that crosses the flow path Y. Valve stem 42 can rotate into vertical hole 30 It has a horizontal through hole 42a. This valve hole 42a has a valve means 40, That is, when the valve stem 42 is in the open position, it forms a portion of the nozzle flow path Y. valve stem 4 2 provides nozzle flow for communication with cavity IIA of barrel 2 when in the closed position. In other words, the pressure chamber is closed.

The melt of plasticized and metered material is poured into the mold cavity using screw plunger 3. Immediately after being injected from the barrel 2 through the nozzle channel Y towards IIA, the valve means 4 0 is forced into the closed position by the pulse motor, blocking the nozzle flow path, thereby A closed space Z consisting of the mold cavity 11A and the pressure holding chamber X is fixed in volume. The result As a result, most of the injected material is packed into this fixed closed space Z, thereby causing the cavity to Internal pressure is exerted on the melt filled in the mold IIA, but this pressure is It is called pressure J.

In contrast, conventional pressure holding chamber systems (not shown) are connected to the corresponding chamber X'. It comprises a piston-cylinder device with which it is attached. As soon as the corresponding nozzle flow path blockage occurs , the space to which the piston and cylinder correspond, but whose volume is not fixed but variable. External pressure is applied to the melt in the interval Z'. From this, the conventional pressure holding chamber system is In contrast to the "inner pressure chamber system" shown in 1, it is called the "outer pressure chamber system."

Both types of pressure chamber systems built into injection molding equipment have a screw plunger system where the pressure is hitherto widely used non-holding pressure produced by the injection machine itself with a There are common advantages compared to room systems.

This common benefit results in significantly shorter one-shot cycle times and increased productivity. It's in the point of letting go. This is because the injection is carried out during the outer pressure holding process or the inner holding pressure process. This is because the output machine can carry out the plasticizing and metering process for the next shot. . Therefore, the duration of one shot cycle in continuous operation of cyclic injection molding can be minimized. In order to achieve It is preferable to perform a plasticizing and metering process for the next shot.

The external holding pressure is made using a screw plunger for use in plasticizing, metering, and injection. A widely available non-holding chamber system, performed by the injection machine itself, is the injection machine (in non-pressure chamber systems) or an additional piston cylinder (in outer pressure chamber systems). The system relies on an external hydraulic drive source, such as a The external holding pressure chamber system is substantially equivalent to the stem.

In contrast, in an internal pressure chamber system, the pressure fluctuations described above are caused by the internal pressure holding process. Both of the systems mentioned above This is advantageous compared to other systems. From this point of view, the internal pressure chamber system can produce precision molded products with high productivity. Therefore, it can be effectively used for manufacturing. In this case, speaking in -a terms, , the ratio of the volume of the chamber X to the volume of the entire mold cavity is around 1 or less. It is preferable to design it to be larger.

The embodiment shown in FIG. 1 has a valve means other than the valve means 40 to cooperate with the internal pressure holding chamber X. not present.

Another type of internal pressure holding chamber system, the so-called "reweighing pressure holding chamber system", is the implementation of Figure 1. For example, if the hollow extension 20 has an additional or second check in the chamber X for metering the melt. This can be realized by modifying it to include a valve means. In this case, The head 23 is provided with remetering means associated with the first-mentioned valve means 40. Re The metering means comprises a seated pressure sensitive check valve associated with the first valve means 40. 1st valve The valve stem 42 of the means 40 has grooves formed on its surface. Barrel head, i.e. rear 2 3 has an outlet hole extending horizontally therefrom, when the first valve means 40 is in the closed position. A vertical hole is formed at such a position that the groove 42b communicates with both the valve means 40 and the second check valve. This outlet hole is open when the first valve means 40 is in the open position, and this horizontal hole is open when the first valve means 40 is in the open position. is closed by the valve stem 42.

This reweighing internal pressure chamber system is subject to operational fluctuations in metering each shot cycle. The amount of melt injected and packed into the space Z, which tends to fluctuate, is remeasured, that is, the amount of melt is kept at a predetermined level. adjustment so that the resulting, i.e., reweighed melt has a reduced amount of variation. This is advantageous compared to non-reweighing internal pressure chamber systems. As a result, the reweighing system The system reduces part weight fluctuations compared to non-reweighing systems, and therefore the reweighing system TEM is more preferred for manufacturing precision molded products.

In the embodiment shown in FIG. 1, the screw plunger 3 has a plunger head 3a and a check valve. A filter 3c, which is a porous member, is provided between the filters 3b and 3b.

This filter 3c allows the weighed melt to be filtered from impurities contained in the plasticized melt. It is passed by the mouth.

1-3, the mold assembly 10 further includes a plurality of spring-biased needles. It includes a dollar valve group 100. The valve 100 includes a group of individual valve bodies 110, a common movable valve. It includes a hinge plate 120 and a common fixed spring seat plate 130. Valve seat plate 1.30 is no. It has a central hole 131 coaxial with the sprue 22 through which the sprue of the hollow extension 20 is inserted. A bush or front portion 21 contacts a nozzle or middle portion 22. Runnamoo The lead 13 is connected to the spring seat plate 130 via a spacer 140.

The spring seat plate 130 is screwed to this, and a plurality of guide rods extend forward from there. It has a head 133. The spring seat plate 130 is further fixed to this with bolts, It has a support and stop rod 134 extending forwardly therefrom.

The flange plate 120 has a hole coaxial with the nozzle 22 through which the sprue butt is inserted. A central hole 121 in which the shoe 21 extends forward and is fixed to the runner mold 13; Guide hole 122 for guide rod 133 and support for support stop rod 134 It has a stop hole 123. The guide hole 122 has a corresponding guide rod 133. is radially fitted and designed to be axially movable therethrough. Each support guide The hole 123 is designed with a radial gap between it and the front part of the rod 134. . The rear part of the rod 134 is enlarged compared to the front part and has a second stop for the flange plate 120. A shoulder 135 is formed to provide a top. Preferably, rod 134 is a runner. A space is provided between the mold 13 and the spring seat plate 130 to provide the first stopper shown in FIG. It is designed to provide a different type of spacer than the spacer 140. In other words, in this example, For the dynamic flange plate 120, the first (135) and second (141) stoppers are [Fixed runner mold] 3 and the fixed spring seat plate 130 are provided by two types of spacers. Served.

The flange plate 120 is fixed to this, and a hollow port 125 extends rearward from this. The hole 121 and the sprue bush 21 are surrounded by this hollow bolt. this Bolt 125 has an 11m nut 126 threaded thereon.

Rods 133 and 1 inserted into holes 122 and 123 corresponding to the flange plate 120 ．． In combination with the spring seat plate 130 having the main coil spring 15 0 and a plurality of auxiliary coil springs 160 are connected to the central port 125 and the rod 133, respectively. It is set up so as to surround the

The spacer 140 is a shoulder 1 that provides the above-mentioned first stiffener for the flange plate 120. It has 41. For convenience in understanding the mold structure, the upper half of the mold structure in Figure 1 is A case is shown in which the lunge plate 120 is in contact with the shoulder 141, that is, the first stopper. , on the other hand, the flange plate 120 is separated from the stopper 141 in the lower half of the mold structure in FIG. This shows a case where

In the above combination of the flange plate 120 and the spring seat plate 130, the The auxiliary coil spring 160 urges the flange plate 120 and and the spring seat plate 130, surrounding the hollow bolt 125 and the adjustment nut. The main coil spring 150 located between the spring plate 126 and the spring seat plate 130 is The flange plate 120 is urged forward against the shoulder 141 of the spacer 140. let The total force of springs 150 and 160 is applied to adjusting nut 1 against spring seat plate 130. Adjustment can be made by changing the relative axial position of 26.

The runner mold 13 has an axial direction whose front portion is provided by the sprue bush 21. A central flow path 13A extends from the central flow path 13A, and a central flow path 13A branches from the central flow path 13A to extend in the radial direction. a distribution channel 13B, and a runner that extends in the axial direction and communicates with the distribution channel 13B. It has 13C. Runner mold provided by Runner Bush Group 112 a plurality of front extension body groups, each of which defines a front portion of a corresponding runner 13C; are doing.

The cavity mold 11 has gates IIB and IIB of mold cavity IIA, respectively. It has a group of axial holes forming a large diameter section with a shoulder between it and the gate. run The front extension body group 13D of Namold 13 is inserted into the axial hole group of the cavity mold! and abut against the shoulders of these axial hole groups, respectively.

The relative radial position of the front extension body 13D to the gate IIB is determined by the positioning pin. 13E.

The needle valve group has a plurality of needles with valve heads 171 for the corresponding gate group 11B. Each has a dollar valve body 170. Each needle valve body has a threaded rear end 172. are doing. The flange plate 120 has a plurality of threaded holes 127, which are provided with needle holes. A valve body group 170 is inserted and screwed at its threaded end 172.

The runner mold 130 is attached to a seal bush 13F installed in a pre-drilled hole. It has a plurality of pores provided therein. The needle valve body group 170 has a corresponding gate. The valve body extends forward toward the group through this seal bush group 13F. The enlarged portion, ie, the hermetic portion 173, fits radially into the seal bushing 13F. It is formed so that it can be moved in the axial direction.

As clearly shown in FIG. 3, the enlarged diameter portion 173 of each needle valve body 170 shaped with a shoulder having a flat, i.e. radially extending, surface 173A. when the gate is closed, i.e. the valve closed position as shown in the upper half of Figure 1 and Figure 3. , this flat surface is the inner surface of the virtual extension body of the distribution channel 13B extending in the radial direction. It is preferable to make contact with the imaginary extension and avoid running into this imaginary extension.

The annular surface 173A of the needle valve body is integrally formed with the enlarged diameter airtight portion 173 and the valve head 171. The differential cross section between the adjacent front portion 174 of the shaped valve body.

Melt pressure acts on these annular surfaces 173A, thereby causing Forced forward against the first stopper 141 by all of the springs 150 and 160 The flange plate 120, which has been The entire annular surface is designed to have a size of . Retraction of the flange plate 120 has started. At this time, all the needle valve groups 170 start retracting to open the gate group 11B. Then, the entire cross-sectional area of the hermetically sealed portion 173 is subjected to melt pressure.

The needle valve body 170 is in the form of a probe with a truncated conical tip forming a valve head 171. and the gate 11B is of frustoconical shape as clearly shown in FIGS. 4A and 4B. . Preferably, the gate has a dispersion angle θ1 that is smaller than the dispersion angle θ2 of the chip. .

Most preferably, both the gate and the chip are connected so that when the gate is closed, both are in front of it. The chip ends correspond to the inner ends of the gate 11B with substantially circular line contact with each other at the ends. It is designed to coordinate on the virtual surface of cavity IIA. In other words, the molded product Make sure that there is neither a recess that corresponds to the chip nor a protrusion that corresponds to the gate. In order to Make sure it doesn't get stuck.

When each gate 11B is opened, as depicted in the lower half of the mold structure of circle 1, , flange plate 120 against a second stop 135 provided by rod 134. until the needle valve body 170 of the corresponding probe contacts the needle valve system. The melt pressure inside runner 13C resists the resultant force of the frictional force and the total spring force generated in and is pulled back. During this gate opening, that is, the probe retraction process, friction The force acts to increase the resultant force, whereas the gate closes, i.e. the probe In the forward stroke, this frictional force acts to cancel the resultant force. Therefore, the melt pressure is To close the gate, a relative force equal to the total spring force minus (-) friction force is required. must be destroyed to a low level. This further reduces the melt pressure to that low level. This means that the probe 170 does not move while it is in the process of decreasing. High rate Bell and low level gaps depend on friction and total spring force.

Under such an environment, it is necessary to The axial melt force applied to all needle valve groups by the melt pressure causes the valve groups to open. the needle valve group so that it equals or exceeds the total spring force at the position. In such cases, it is practically preferable to design and determine the total spring force. In this case, each needle valve may move toward the gate even at the final stage of the pressure holding process. Definitely blocked.

Theoretically, the probe length should be at the threaded rear end of the probe relative to the flange plate 120. If the front edge is sufficiently and accurately adjusted, the pro The first striker 141 prevents the needle valve body 170 of the valve from colliding with the gate 11B. expected to be prevented. However, in reality, the probe 170 Due to expansion, it may collide with gate IIB. Therefore, this type of desirability Make the probe out of relatively flexible metal to avoid potential collisions. is preferred.

Regarding the heater provided for the spring biased needle valve according to the present invention, A first example of a valve is depicted in the upper half of the mold arrangement shown in Figure 1, and a second example of a valve is depicted in the upper half of the mold arrangement shown in Figure 1. It is painted on the lower half of the body.

According to the first example showing the gate closed state described above, the runner bush 13D is The probe 170 has a body heater 185 inside. have. Furthermore, the sprue bush 13F is located inside the enlarged airtight portion 173. It has a body heater 190 in the section. A pair of bodyhire related to each runner 13c The motor 180°185 is connected to the gate IIB and the probe tip 171 for cold or semi-cold melting. It is effective to reduce the friction caused by each seal bushing 1. The other body heater 190 on the 3rd floor is located between the airtight part 173 and the seal bushing 13F. due to the intrusion of melt that can penetrate into the very small radial voids of Friction that occurs between the seal bushing 13F and the enlarged airtight portion 173 of the probe It is effective in reducing

According to the second example depicting the gate open state, each runner bush 13D is similar to the first example. has the same body heater 180, but this bushing is in cavity I. A tip hitch is placed at the front end of the runner bush located near the IA and probe tip 171. It has a data 181.

Instead, probe 170 does not have any body heater.

The runner bush 13D of the first example does not have a front end as described above.

The enlarged seal portion 173 of the probe has a body heater 191 . That cost In addition, the seal bushing 13F does not have any podium heater.

All of the above-mentioned Pode heaters provide continuous heating, but chip heaters The heater 181 is a means for instantaneous intermittent heating. The chip heater 181 is It is started just before exit.

The combination of the heaters 1.80 and 185 in the first example and the heater 180 in the second example , 1.81 combination and the truncated cone-shaped thousand tubes 171, the gate can be started to open. The area of action of each probe 170 on which the melt pressure should act in order to The cold material is melted so that the area between the enlarged hermetic part and the front part of the probe increases beyond the differential cross section mentioned above.

In the injection molding machine of the above-described example shown in FIG. The flow path Y is activated to open, and then the melt is pushed by the screw plunger 3. be ejected. This melt then fills each runner 13C under high pressure. this high Melt pressure is applied to the first stopper 141 via the flange plate 120. the needle valve 170 of each probe.

All the probe groups are connected until the flange plate 120 abuts against the second stopper 135. is moved rearward together with the common flange plate 120.

As a result, all the gate groups 11B are opened at the same time, and the melt flows into the cavity group 11B. Injected into A. This injection process is completed and the valve 40 is then inserted into the upper half of the injection molding machine. When it is closed as shown, it changes to the internal pressure holding process. This internal pressure holding process is completed. However, this reduced melt pressure in the holding chamber is due to the total spring force and friction. The resultant force of friction (negative force) is not small enough to overcome the melt force, and therefore the gap The port remains open. Therefore, valve 40 is opened, thereby reducing the melt pressure. must be further destroyed. The further decrease in melt pressure causes the relatively high pressure chamber During the packing process, the melt is prepared at a relatively low pressure for the next shot cycle. It is generated by mixing with the metered melt. As a result, the total spring force minus the frictional force overcomes this reduced melt pressure, thereby increasing the common flux. In order to close all the gate groups 11B simultaneously, the probe plate 120 closes all the probe groups 1. 70 and is moved forward.

There are two cases in this process. One case is that when the valve opens, This is the case when the next weighing process has been completed.

Another case is that when the valve opens, this next shot metering process is not yet completed. This is the case if you have not done so. In the latter case, there are virtually no problems with metering. this Since all gates are closed at the final stage of the weighing process, the However, it can continue just like the conventional weighing process carried out in the industry.

Of course, in the latter example above, instead of opening the valve, the service is performed by pulling back the nozzle 22. performs a back-back operation, whereby during metering with valve 40 kept closed, all the probe 170 to close all gates IIB. The melt pressure may be reduced to a lower level.

5 and 6 have multiple needle valve groups of spring bias type and spool valve type. Another embodiment of the hot runner mold arrangement is shown, while FIG. It shows what you have. In Figure 5, the same numbers as in Figure 1 refer to the numbers in Figure 1. Qualitatively equivalent parts are shown.

5 and 6, the mold construction is substantially the same as that of FIG. 1 except for the following features: It is.

Each guide rod 133 passes through a hole in the movable flange plate 120 to the fixed spring seat plate 130. and inserted into the guide hole of the fixed support guide plate that provides the back plate 13G of the runner mold. is included. A plurality of coil spring groups 16 surrounding corresponding rod groups 133 0 is installed between the movable flange plate 120 and the spring seat plate 130. each needle The valve body 170' extends through the axial hole in the back plate 13G and is connected to the runner mold body. It is inserted into a hole 13'F extending in the axial direction and having a radial step.

The spacer 140 is installed between the back plate 13G and the spring seat plate 130. Back plate 1. 3 G is the front surface of the flange plate 120, and the stone barring provided thereon. 128.

The spring seat plate 130 has a plurality of rod groups 135' extending forwardly therefrom. , a combination of these rod groups forms a second rod opposing the flange plate 120 at the front end. Provides a stopper. The main spring is also a spring in the sprue bush 21. There is also no force adjustment means provided. Preferably, as shown in FIG. Means as shown can be provided. 21A surrounds sprue bush 21 A coil heater is shown. The runner 13'C and the gate 11'B are formed on the runner 13'C. The inner bush 13'D has a coil-shaped body heater 180 inside.

Each gate 11'B has a truncated conical shape plus a cylindrical shape extending forward. . The frustoconical portion of this gate 11'B has grooves A, B, or C as shown in FIG. are doing. The valve head or valve tip 171' has a circular shape corresponding to the type of gate 11'B. Although it is a combination of a frustum and a cylinder, it does not have a kerf. valve The cylindrical tip is inserted into the cylindrical part of the gate when the valve is in the closed position. .

When the valve is in the open position, this cylindrical tip is pulled back into groove A, B or C. In this combination, the chip defines a flow path opening in the cylindrical gate part as shown in Figure 6. It is established.

Pass through the hole 13'F that extends in the axial direction of the runner mold body or has a stepped shape. The corresponding needle valve body 170' extends into the corresponding launch 1, 3C. The hole 13'F has a front hole section 130A and a rear hole section 130B. have. Both bore sections have axes that are radially offset from each other.

Each knee valve body 170' has a front part 170'A and a rear part separated from the front part 170'A. Consisting of 170'B. Both parts have abutment surfaces at their opposing ends, and these The contact surface is in contact with the other party.

The rear part 17Q'B is inserted into the rear hole section l3QB with a radial gap. , while a front part 170'A is inserted into the front hole section 130A and has a half half therein. radially compatible. The valve body front part 170'A is shown when the valve is in the closed position. E, on the conical surface of the valve head tip 171' formed at the front end of the front part 170'A. Due to the melt pressure acting on the other side, it comes into contact with the rear part 170'B of the other party. be forced to. When the valve closes the corresponding gate, both parts of the valve body Therefore, the spring force applied by all the spring groups 160 causes the gear to be forced to move forward towards the target.

However, this spring force is the sum of the melt pressure and the frictional force created in the associated valve system. It is something that overcomes force.

The above-mentioned valve body 17 has a step hole 13'F having sections 130A and 130B. 0' (170'A, 170'B) is the radial direction of the rear part 170'B of the valve body The position is set to a predetermined relative position due to the thermal expansion difference between the back plate 13G and the runner bush 13'D. The front part 170'A of the valve body has a relatively large shift from the position to the radial position of the front part 170'A of the valve body. Even if the valve body is injected, it is necessary to ensure smooth movement of the valve body back and forth during long-run injection molding operations. Make it real. In this case, the valve body parts 170'A, 170'B are sliding relative to the abutment surface in the radial direction without being substantially bent with respect to the axis of the is allowed.

It is shaped by a combination of a deflection section with holes as described above and a needle valve body. The heat of the runner mold is not necessarily required, but Taking expansion into account, the example of FIG. 1 may also be applied as necessary. Furthermore, as shown in Figure 1 An example of the mold structure is a spool type as shown in Figures 5 and 6 instead of a valve seat type valve group. It may be modified to have a plurality of valve groups.

abstract a plurality of needle valve groups for opening and closing corresponding gate groups of the mold cavity groups; Specifically, a hot runner mold assembly with a spring-biased valve group is provided. In this case, each needle valve body has a corresponding one drilled into it from inside the mold structure. It extends to the outside through the air-tight hole, and is also connected to all of the valve body groups. A valve drive means is disposed external to the mold structure. Spring biased needle valve This mold arrangement is preferably used in injection molding of internal pressure chamber systems. However, in that case, a valve installed to block the nozzle flow path and define a pressure holding chamber is required. opened, thereby releasing the nozzle flow path blockage provided by said valve driving means. Melt pressure resisting the spring force is reduced to a low enough level to close the gate. Make it less.

National avR inspection report DrT/, ID (H/nn1l; A1,, -l- ^--~ + PCT/JP 91100166 International Search Report

Claims (26)

[Claims] 1. Implements hot runner injection molding, which is combined with an injection machine with coaxial nozzles. A mold structure for forming a mold, the mold structure comprising a plurality of molds each having a gate extending in the axial direction; A cavity mold defining a cavity; including a manifold, the cavity mold The mold is removably connected to the mold, and is connected to the corresponding gear of the cavity mold. a plurality of holes communicating with an extension body extending axially forward of the injection machine and including the nozzle; a runner mold forming an axially extending runner; and a corresponding gate; A spout provided to be activated by varying melt pressure to open and close. Consists of a plurality of ring-biased needle valves, each valve serving as a bud chamber. Needle or probe style shaft inserted with a radial gap into the runner comprising a valve body extending in the direction, the needle valve body having a valve head at its front end; Such a hot runner type valve head is adapted to cooperate with a corresponding gate. In the mold structure, Each needle valve body shafts through a corresponding hole drilled into it from the runner mold. extends rearward in the direction and is movable in the axial direction through the hole; radially fits into the bore so as to be substantially air-tight, and the needle valve group Furthermore, the needle valve body group is moved against a first stopper provided on the outside of the runner mold. of the runner mold for biasing the valve head group to close the gate group; A hot runner type mold structure comprising an externally provided common means. . 2. The common biasing means is: a radially extending plate provided on the exterior of the runner mold. A body of this type, from which the needle valve body group extends forward. A common flange movable in the axial direction; installed with an axial gap on the outside of the flange plate. a common fixed spring seat of plate type extending in the radial direction; a common closed position of the valve group; In order to define the front and rear axial positions of the movable flange plate corresponding to the open position, respectively. said first stopper and second stopper provided for said fixed spring seat plate; means for radially supporting and axially guiding a moving flange plate; biasing or biasing the plate relative to the first stopper and relative to the second stopper; A plurality of axially extending holes provided in the gap between the flange plate and the spring seat plate so as to The radial position of the spring group is such that the radial position of the spring group corresponds to the spring seat plate. The mold structure according to claim 1, wherein the mold structure is distributed over substantially the entire front surface. 3. The common biasing means biases a coil-type main spring in the plurality of springs. a group of springs that is adjusted with respect to the axial length of the flange plate and thereby acts on the flange plate; 3. A mold arrangement according to claim 2, comprising means for adjusting the overall force of the mold assembly. 4. The spring seat plate has a central hole into which the nozzle and the rear hollow of the runner mold are connected. A combination body with an extension body is inserted, and the flange plate is aligned with the central hole of the spring seat plate. having a central hole in the shaft, the spring adjusting means: extending rearwardly from the flange plate; , an axial hollow bolt surrounding the center hole of the spring seat plate; and an adjustment screw threaded onto the bolt. the hollow bolt is surrounded by the main coil spring; , arranged in an axial gap defined between the adjustment nut and the spring seat plate. Item 3. The mold structure according to item 3. 5. The support guide means includes a plurality of axial rods extending forwardly from the spring seat plate. and at least some of the rods are of a coil type other than the main coil spring. It is surrounded by the remaining spring, which is an axial spring, and the spring The surrounding rod group is inserted into the corresponding hole group drilled in the flange plate. 5. The mold arrangement of claim 4, wherein the mold arrangement is slidably adapted to. 6. The remaining rod groups were of the stepped type, each drilled into the flange plate. with corresponding holes forming an axially movable front part and a shoulder providing said second stop; the shoulder is in contact with the flange plate when the valve group is in the open position. The mold structure according to claim 5, which is adapted to do so. 7. The axial position of the spring seat plate is adjusted to the cavity mold and the runner mold. A spacer means is provided for relatively fixing the spacer means to the a shoulder providing the first stop, the shoulder disengaging the flange in the closed position of the valve group; 7. The mold structure according to claim 6, which comes into contact with the die plate. 8. Each needle valve body is screwed into a corresponding threaded hole drilled in the flange plate. a front portion of the valve body having a threaded portion thereby extending from the flange plate; 8. A mold arrangement according to claim 1, wherein the mold structure is adjusted with respect to its axial length. 9. The runner mold has a plurality of front axial extensions, each corresponding to an interior A runner is formed, and a body heater is provided near the periphery of the runner. The mold structure according to any one of claims 1 to 8. 10. Claim 9, wherein each needle valve body is provided with a body heater therein. Mold construct. 11. Each front axial extension of the runner mold is internally disposed near the periphery of the corresponding gate. A chip heater is provided in the part, and the chip heater is activated intermittently and instantaneously. The mold structure according to claim 9. 12. The runner mold has a corresponding one in which each corresponding needle valve body radially fits. A heater is installed near the periphery of the hole in order to prevent an increase in the frictional force generated in the hole. The mold structure according to any one of claims 9 to 11. 13. A valve in which each needle valve body radially fits into a corresponding hole in the runner mold. Place a heater on the corresponding part of the body to prevent an increase in the frictional force generated in the hole. The mold structure according to any one of claims 9 to 11, comprising: 14. The valve group is a valve seat type, each valve head is a truncated conical tip, and each gate is a valve seat type, and each valve head is a truncated conical tip. providing a frustoconical valve seat diverging toward a conical tip, the flange plate When abutting against the stopper, the conical tip substantially abuts against the gate. , thereby closing the gate. The mold structure shown above. 15. Each needle valve body has a front portion formed with a conical tip at the front end and a large diameter. It has an adjacent part that expands in a step-like manner from this front part, and the enlarged part extends from the front part. It fits radially into the corresponding hole in the flange plate and when injection is carried out, the flange The lunge plate, together with the entire needle valve body group, is moved by the melt pressure in the runner group. 2 to the axial direction to close all the gate groups. However, the melt pressure is applied to the entire cross-sectional area of the expanded portion of the valve body group. , whereby the flange plate is given a spring by all the spring groups. generates a melt force that resists the resultant force of the mechanical force and the frictional force generated in the associated valve system. The mold structure according to claim 14. 16. The total differential cross-sectional area between the enlarged portion and the front portion is equal to the spring force and the friction force. produces a predetermined melt pressure that opposes the resultant force between the flange plate and the Claim 15, wherein the gate is large enough to initiate a retraction movement to open the group of gates. Mold construction as described. 17. The conical tip is smaller than that of the gate and diverges to Any of claims 14 to 16, wherein a substantially circular line contact is made with the gate. The mold structure according to item 1. 18. The valve group consists of spool type valves each having a cylindrical rod type valve head with a uniform diameter. and the corresponding gate forms a cylindrical hole into which the rod radially fits. and the cylindrical gate has at least one axial groove formed on its rear cylindrical surface. having a groove while the rear portion retains the valve head coaxially in the open position of the valve; The front part of the gate communicates with the corresponding runner through the groove. The mold structure according to any one of Items 1 to 13. 19. Opening/closing corresponding gate groups of multiple mold cavity groups defined inside In a hot runner mold structure combined with a plurality of needle valve groups, The needle valve group has a common valve driving means provided outside the mold structure, and each valve has a common valve driving means provided outside the mold structure. within said mold structure forming a runner in which a needle valve body communicates with a corresponding gate; Extending from the part to the outside of the mold structure through a corresponding airtight hole drilled in the mold structure. The needle valve body cooperates with the gate to open and close the gate. the free end forming a valve head which is to be fixed to an external means for driving said common valve; and the mold structure is moved toward the knee valve group or the gate group. It is characterized by having a common stopper provided on the outside to prevent movement. Hot runner mold structure. 20. The valve group is a spool type or a valve seat type, and the valve driving means is a hydraulic type, The hot run according to claim 19, which is pneumatic, electromagnetic or spring biased. Na mold construction. 21. Each needle valve body is a single member, i.e., a single part, which is part of the mold assembly. 19. Radially adapted to a corresponding gastight hole drilled in the adult body. and 20. The hot runner mold structure according to any one of 20. 22. Each needle valve body is separated from the front part but connected to the valve drive means. and a rear part extending in the radial direction, both parts abutting each other in the axial direction. Each airtight hole has an end face through which the corresponding valve body is inserted into the mold configuration. The front part of the valve body, on the other hand, has a half-section at the rear part. The radially matching front bore section and the valve body rear part have a radial clearance of less than The rear hole section is inserted by Claims 19 and 20, characterized in that they have axes that communicate with each other. Hot runner mold construction. 23. Includes means for internally plasticizing, metering, and injecting plastic materials and a hollow extension body comprising a nozzle forming a nozzle channel. an injection molding machine defining at least one cavity having a gate; It is combined with the injection machine and connects the inside of the injection machine main body and the mold door through the nozzle flow path. Hot runner injection using such a mold structure in which cavities are communicated with each other. A molding method: During each shot cycle, the plastic material is heated inside the injection machine body. Plasticizing and metering process; Injecting thermoplastic material under pressure through a nozzle channel into a mold cavity process; and At least a A portion of the thermal injection material is retained, thereby providing a molded part inside and cooling it. The nozzle flow path is located between the inside of the injection machine body and the mold cavity. After the injection process, the communication is interrupted in the middle of the flow path while the material pressure holding process is being performed. Immediately after or after the nozzle flow path is shut off, the plasticizing and metering processes are carried out at the holding pressure. executed by the injection machine for the next shot during the process, i.e. injection. In the injection molding method, Built into the mold structure and activated to open and close the gate by changes in melt pressure Spring-biased needle valve groups are used to reduce friction in the associated valve system. material with melt pressure acting against a combination of friction and springs, i.e. melt injection. During the holding process where the melt pressure decreases, the gate is opened. and release the nozzle flow path blockage thereby further reducing melt pressure. A hot runner injection molding method characterized in that the gate is closed by closing the gate. 24. Metering is completed during the nozzle flow path shut-off, and then this is done for gate closure. 24. The injection molding method according to claim 23, wherein the flow path blockage is released. 25. The initial stage of metering is performed while the nozzle flow path is shut off, and the final stage of metering is performed at the gate. 2. Performed immediately or after release of said nozzle flow path blockage resulting in closure. 3. The injection molding method described in 3. 26. Includes means for internally plasticizing, metering, and injecting plastic materials and a hollow extension body comprising a nozzle forming a nozzle channel. an injection molding machine defining at least one cavity having a gate; It is combined with the injection machine and connects the inside of the injection machine main body and the mold door through the nozzle flow path. Hot runner injection using such a mold structure in which cavities are communicated with each other. A molding method: During each shot cycle, the plastic material is heated inside the injection machine body. Plasticizing and metering process; Injecting thermoplastic material under pressure through a nozzle channel into a mold cavity process; and At least a A portion of the thermal injection material is retained, thereby providing a molded part inside and cooling it. The nozzle flow path is located between the inside of the injection machine body and the mold cavity. After the injection process, the communication is interrupted in the middle of the flow path while the material pressure holding process is being performed. Immediately after or after the nozzle flow path is shut off, the plasticizing and metering processes are carried out at the holding pressure. executed by the injection machine for the next shot during the process, i.e. injection. In the injection molding method, Built into the mold structure and activated to open and close the gate by changes in melt pressure Spring-biased needle valve groups are used to reduce friction in the associated valve system. material with melt pressure acting against a combination of friction and springs, i.e. melt injection. During the holding process where the melt pressure decreases, the gate is opened. the nozzle and the injection machine body relative to the mold structure. At the same time, the melt pressure can be further reduced while the nozzle flow path is blocked. A hot runner injection molding method characterized in that the gate is closed by.