WO2019208663A1

WO2019208663A1 - Injection molding method and injection molding machine using said method, and injection molding screw used therewith

Info

Publication number: WO2019208663A1
Application number: PCT/JP2019/017520
Authority: WO
Inventors: 壮下楠薗; 井上　玲; 靖丈澤田
Original assignee: 東洋機械金属株式会社
Priority date: 2018-04-27
Filing date: 2019-04-24
Publication date: 2019-10-31

Abstract

[Problem] To forcibly knead both solid and liquid phases at the early stage of a plasticization process and promote melting of a solid bed (SB) in a screw groove. [Solution] Some of a solid phase part serving as a solid bed (SB) in a screw groove or some of a melt pool (MP) in a preceding screw groove is forcibly introduced into a solid-liquid phase kneading zone via a branch stream formation opening part forming a branch stream. As a result, resin materials of both solid and liquid phases are kneaded at an early stage to promote melting of the solid phase, and the kneaded and melted resin materials are measured. After the measurement operation, a screw is advanced by an advancing/retracting driving means provided with an injection motor and a ball screw mechanism to inject a measured amount of the melted resin materials into the cavity of closed molds via an injection nozzle.

Description

INJECTION MOLDING METHOD, INJECTION MOLDING MACHINE USING THE METHOD, AND INJECTION MOLDING SCREW USED FOR THEM

The present invention relates to an injection molding method based on a novel kneading / melting model, an injection molding machine having a novel configuration using the method, and an injection molding screw having a novel configuration used therefor.

In particular, the invention of the present application introduces a part of the supplied resin material into the solid phase part or the kneading zone of the liquid phase part in the spiral screw groove at an early stage of the plasticizing process, thereby forcing the solid-liquid both phases. The present invention relates to an injection molding method for forcibly kneading a solid-liquid phase of a supplied resin material through a kneaded / molten state to promote melting of a solid phase part. Furthermore, the present invention relates to an injection molding machine used in the method, and an injection molding screw having a novel configuration used for them. In the present invention, a part of the supplied resin material is a part of a liquid phase part (melt pool MP: Melt Pool) in a molten state in a screw groove, or a solid phase part (solid bed SB) in an unmelted state. : Solid Bed).

The present invention specifically relates to an injection molding method based on a novel solid-liquid both phase kneading / melting model at an early stage of the plasticization process when the supplied resin pellets are kneaded and melted by rotating a screw. About. Here, the new solid-liquid both-phase kneading / melting model is a method in which a part of the supplied resin material is formed as a branch flow with respect to the molten resin flow as the main flow by the rotation of the screw. In other words, a part of the liquid phase part (MP) is introduced into the solid phase kneading zone of the solid phase part (SB) in an unmelted state in the spiral screw groove, or a more advanced spiral screw groove In the liquid phase kneading zone of the liquid phase portion (MP) that is in the molten state, a solid phase portion (SB) is partially introduced or a solid phase that forcibly kneads both the solid phase and the liquid phase. This constitutes a liquid phase kneading zone. As a result, in the early stage of the plasticization process, the solid phase part (SB) in the melted state in the screw groove is forcibly kneaded with the liquid phase part (MP) in the molten state to melt the solid phase part. It is possible to provide an injection molding method that promotes the above. The present invention also provides an injection molding machine used for the novel method and an injection molding screw having a novel configuration used for them.

In another embodiment, the present invention is specifically plasticized when the resin pellets supplied by the rotation of the screw are kneaded and melted to form a molten resin flow as the main flow in the spiral screw groove. In an early stage of the process, a tributary formation opening (notch) is provided in a part of the flight portion between the spiral screw grooves so as to form a tributary with respect to the resin flow as the main flow. As a result, a part of the melt pool (MP) in the liquid phase portion in the molten state in the screw groove preceding the solid bed (SB) in the solid phase portion in the unmelted state in the screw groove is introduced. Thus, both solid-liquid phases are forcibly kneaded. In this way, by going through the solid-liquid phase kneading zone, the resin material in an unmelted state is forcibly kneaded with a part of the liquid phase portion at an early stage of the plasticizing process to promote melting of the solid phase portion. It is possible to provide an injection molding method, an injection molding machine used in the method, and an injection molding screw used for them.

In addition, the present invention is different from the above, depending on the difference in the resin to be injection-molded and the difference in the injection conditions, as another embodiment, the resin pellet supplied at the time of injection molding is kneaded and melted with a screw to form a spiral shape. When forming a molten resin flow as a main flow in the screw groove, a part of the unmelted solid bed (SB) in the screw groove passes through the above-described branch flow forming opening (notch), and the preceding screw groove The solid-liquid phase kneading zone can be configured to be introduced into the melted melt pool (MP) and forcibly kneaded as both solid-liquid phases. By passing through such a solid-liquid phase kneading zone, the molten resin material is rapidly and forcibly kneaded with the unmelted solid phase portion at an early stage of the plasticizing process, and the melting of the solid phase portion is promoted. It is possible to provide an injection molding method, an injection molding machine used in the method, and an injection molding screw used for them.

In any case, the present invention forms a tributary to the molten resin flow as the main flow, and at an early stage of the plasticizing process, a part of the liquid phase part in the molten state (melt pool MP) or the solid state in the unmolten state. An injection molding method based on a new kneading / melting model in which a part of a phase portion (solid bed SB) is introduced into a kneading zone in a screw groove in which the respective phase states are different, and an injection molding machine used for the method Further, the present invention relates to an injection molding method and an injection molding screw used in an injection molding machine.

As described above, in the present invention, when the supplied resin material is kneaded and melted, the unmelted state in the spiral screw groove at the timing when the supply resin is compressed by the screw at the initial stage of the plasticizing process. A tributary formation opening for forming the above-mentioned tributary of either a part of the solid phase part (solid bed SB) or a part of the liquid phase part (melt pool MP) in the molten state in the screw groove preceding it. It is introduced into the solid-liquid phase kneading zone through the (notch portion), forcibly kneading a part of the solid bed (SB) in the solid state or a part of the melt pool (MP) in the liquid state, The injection molding is promoted by promoting the melting of the resin.

More specifically, the present invention flows as a melt pool (MP) in a solid phase part that stays as a solid bed (SB) in a spiral screw groove formed on the outer periphery of the screw, and in a screw groove preceding it. A solid-liquid phase kneading zone is formed by forcibly introducing a part of the liquid phase to be introduced through the above-described branch flow forming opening. Accordingly, the present invention relates to an injection molding method in which both solid and liquid phases of a resin material are rapidly kneaded at an early stage of a plasticizing process to promote melting of a solid phase portion. In the novel plasticization process of the present invention, the resin material is forcibly and rapidly kneaded a part of the liquid phase part (melt pool MP) into the solid phase part (solid bed SB) at an early stage of the plasticization process. In order to promote melting of the solid phase portion, this can be achieved by forming a notch as a branch forming opening in the flight.

Further, according to the present invention, the solid phase staying as a solid bed (SB) in the screw groove formed on the outer periphery of the screw, contrary to the plasticizing process, depending on the difference in the resin to be injection-molded and the difference in the injection conditions. A solid-liquid phase kneading zone is also formed by forcibly introducing a part of the part into a melt pool (MP) that flows as a liquid phase part in a screw groove preceding the part. Accordingly, the present invention relates to an injection molding method for forcibly kneading a solid-liquid resin material at an early stage of the plasticizing process and promoting melting of the solid phase. In such a plasticization process of the present invention, in the early stage of the plasticization process, the solid phase part (solid bed SB) is forcibly kneaded in the liquid phase part (melt pool MP) and the solid phase part is formed. In order to promote melting, this can be achieved by forming a tributary formation opening (notch) as a tributary formation portion in the flight.

Further, the present invention relates to an injection molding machine used in the above method, and further relates to an injection molding screw used in the injection molding machine.

In the present specification, the meanings of terms are as follows.
The “kneading / melting model” is the behavior of the resin flow as the main flow of the resin material when the resin material supplied by the rotation of the screw is heated, kneaded and melted in the plasticizing process in the plasticizing process. The form of change.
“Solid Liquid Mixing Zone” is a model of resin material kneading and melting in an injection molding machine that forms a tributary in a spiral flight between a screw groove and the adjacent screw groove. Forcibly forming both solid and liquid phases by introducing a part of the phase of either the solid bed (SB) or melt pool (MP) into the other phase. A kneading zone in the screw groove that kneads and promotes melting of the solid bed (SB). The “kneading zone” configured in the screw groove is referred to as follows depending on the phase state of the resin to be kneaded.
“Solid bed mixing zone” refers to a kneading zone in which a solid bed (SB) of a solid phase portion is kneaded in a screw groove in a resin material kneading / melting model in an injection molding machine.
The “liquid phase kneading zone: Melt Pool Mixing Zone” refers to a kneading zone in which the melt pool (MP) of the liquid phase portion is kneaded in the screw groove in a resin material kneading / melting model in an injection molding machine.

In the present invention, more specifically, in the solid-liquid phase kneading zone, in the kneading zone (solid phase kneading zone) of the solid bed (SB) formed by the lump of unmelted solid particles in the screw groove, A tributary from the preceding screw groove is formed, a part of the melt pool (MP) is forcibly introduced, and a part in the solid phase (solid bed SB) and a part in the liquid phase (melt pool MP) Forced kneading to promote melting of the solid phase part.
As another embodiment, the present invention is a solid bed formed by a lump of unmelted solid particles in the screw groove, contrary to the above-described form, depending on the difference in resin to be injection molded and the difference in injection conditions. A part of (SB) is forcibly introduced into the melt pool (MP) through a tributary toward the solid-phase kneading zone in the screw groove that precedes it, and the solid-phase part (solid bed SB) and the liquid-phase state The (melt pool MP) portion of the material is forcibly kneaded to promote melting in the solid phase (solid bed SB).

“Screw groove” and “screw groove preceding it” are a single continuous groove formed around the injection molding screw, but are used when referring to spiral adjacent grooves.
“Resin flow as main flow” and “branch flow” means “main flow” of “melt resin flow flowing from the resin supply hopper side toward the nozzle side in the spiral groove of the screw for injection molding” and “screw groove” It refers to a flow as a “branch” through a tributary formation opening (notch) formed in the flight part between the “screw groove preceding it”.

Patent Document 1 discloses a conventional screw used in an injection molding machine. This screw has a rotating shaft portion and a spiral flight projecting from the outer periphery of the rotating shaft portion, and is rotated from the proximal end side (hopper side) to the distal end side (nozzle side) by the rotation of the rotating shaft portion. The material is melted while feeding the resin material along the axial direction. For that purpose, it is necessary to make the molten state of the resin material uniform.

In this regard, in the prior art, by adjusting the depth of the screw groove between the flights of the screw, the shearing force acting on the resin material is changed to smooth the molten state of the resin material.

In injection molding, in order to stabilize the quality of a molded product, as described above, it is necessary to make the molten state of the solid-liquid both phase resin material uniform in the molten resin flow as the main stream. Therefore, the inventors of the present application said that it is one of the important elements in injection molding that the resin material is kneaded and melted overall at a relatively early stage of the plasticizing process to make the molten state uniform. We have obtained knowledge.

Generally, a screw (full length L) used in an injection molding machine has a structure of a supply unit, a compression unit, and a metering unit in order from the resin inlet side (hopper side) to the resin discharge port side (nozzle side). ing. By adopting such a screw shape and configuration, the supplied resin material was thought to be efficiently kneaded and melted. Many studies have been made on the model in which resin pellets are melted by the screw rotating in the cylinder.

These were mainly studied as a model of the plasticization process of resin material in an extruder using a screw, but at present, as a model of plasticization of a resin material in an injection molding machine using a screw. Known and generalized. For example, the Tadmor model described in Non-Patent Document 1 is known. This is common in the present invention and will be described in detail below.

As shown in FIG. 9A, a general injection molding screw 130 has screw grooves M formed by spiral flights 133 protruding from the outer peripheral portion of the rotating shaft portion. In other words, the flight 133 is spirally formed on the outer periphery of the screw 130 with a predetermined flight pitch (FP: Flight Pitch), a predetermined flight width (FW: Flight Width), and a predetermined flight depth (FD: Flight Depth). Is formed. As a result, a spiral screw groove M is continuously formed on the outer periphery of the screw 130. FIG. 9B schematically shows the kneading and melting mechanism of the resin material in the screw groove of the injection molding screw represented by the Tadmor model when such an injection molding screw 130 is used.

In such an injection molding screw 130, the solid resin material introduced from the hopper is directed toward the injection nozzle side (left side in FIG. 9) in the screw groove M formed between the flights 133 by the rotation of the screw 130. Then, it is pumped as the main flow of the molten resin flow. When the resin material is pumped by the rotation of the screw 130, a shearing force acts on the resin material and is heated from the heating cylinder 121, and the resin is sequentially melted. Thereby, the state of the solid-liquid phase of the resin material in the screw groove M is a melt film (MF) in contact with the solid phase portion of the unmelted resin material called a solid bed (SB) and the inner peripheral surface 121a of the heating cylinder 121. : Melt 溶融 Film) and a rotating flight 133 form a liquid circulating molten phase called a melt pool (MP) in which the melt film (MF) is scraped. As the supplied resin pellets are pumped from the resin charging port side (hopper side) toward the resin discharge port side (nozzle side) by the rotation of the screw 130, the ratio of the melt pool (MP) increases and melting progresses. It is a waste.

When the melt film (MF) in contact with the inner peripheral surface 121a of the heating cylinder 121 is formed, heat generated by shearing energy is applied by the rotation of the screw 130, and the solid bed (SB) in the screw groove M is sequentially melted. A melt film (MF) grows in the radial direction of the screw. When the thickness of the melt film (MF) grows to a thickness equal to or greater than the clearance C formed by the outer peripheral surface of the flight 133 and the inner peripheral surface 121a of the heating cylinder 121, the melt film (MF) is moved forward by the flight 133. Is scraped off. The melt film (MF) scraped off is collected at the resin inlet side (hopper side) of the screw groove M, and a circulating melt pool (MP) grows, and is kneaded while refluxing as indicated by an arrow. Is done.

Further, Patent Document 1 (Japanese Patent Laid-Open No. 2016-182687), which is a screw of a conventional injection molding machine, provides an injection device that suppresses the swirling of the screw and reduces the friction between the screw and the cylinder. It is said.
Patent Document 1 discloses an injection device having a cylinder for heating a molding material and a screw rotatably disposed in the cylinder. The screw has a rotating shaft portion and a spiral flight protruding from the outer periphery of the rotating shaft portion, and the molding material is moved from the upstream side to the downstream side along the rotating shaft portion by the rotation of the rotating shaft portion. To send. The flight has a spiral first flight part and a spiral second flight part arranged on the downstream side of the first flight part, and the second flight part has an upstream end at the top. This is a different-diameter flight portion in which the height of the downstream end portion of the top portion is lower than the height of the portion. The ratio of the flight width of the second flight part to the pitch of the second flight part is larger than the ratio of the flight width of the first flight part to the pitch of the first flight part.

JP 2016-182687 A

As described above, when a resin material is injection-molded, it has been conventionally performed to provide a screw with a flight in order to make the resin material melt and kneaded uniformly. However, since resin materials have different characteristics depending on the type, advanced technology and experience are required to adjust the screw groove specifications (pitch, width, depth, etc.) according to the resin material. At that time, if the screw groove is too shallow due to insufficient adjustment, the shearing force acting on the resin material becomes too strong, causing burns. Conversely, if the screw groove is too deep, the shearing force acting on the resin material becomes weak. It will pass too much and melt away. Therefore, it has been difficult to make the molten state of the resin material uniform.

In particular, in the melted form found in conventional general-purpose screws, efficient kneading and melting can be achieved for materials that must be uniformly kneaded, such as those with added colorants. I didn't.

In such a situation, the inventors of the present application conducted extensive experimental studies on the melting mechanism of various resin materials, and as a result, formed a tributary flow in the flight portion between the screw groove and the preceding screw groove. An opening (notch) is formed, and a part of the solid bed (SB) or a part of the melt pool (MP) is introduced into the solid-liquid phase kneading zone, and at an early stage of the plasticization process, the solid phase It has been found that it is preferable to provide a zone for forcibly kneading the liquid phase and promoting melting of the solid phase.

That is, the inventors of the present application, more specifically, by forming a tributary formation opening (notch) in the flight portion constituting the wall between the screw groove and the preceding screw groove adjacent thereto, We have found a structure that accelerates melting of the solid bed (SB) early by introducing a part of the melt pool (MP) of the preceding screw groove into the unmelted solid bed (SB) region that stays in the screw groove. Is. On the other hand, depending on the difference in the resin to be injection-molded and the difference in the injection conditions, a part of the unmelted solid bed (SB) region staying in the screw groove may be adjacent to the melt of the preceding screw groove. It has been found that it is desirable to have a configuration in which the solid bed (SB) is accelerated to be melted at an early stage by introducing it into the pool (MP).

In the present invention, the solid bed (SB) in the solid-liquid phase kneading zone in the screw groove, regardless of which process (see FIGS. 4 (a) (b) and 5 (a) (b)). And the melt pool (MP) are forcibly kneaded and melted to promote melting of the solid bed (SB). From the viewpoint of the same problem of promoting kneading and melting of the supplied resin material, The configuration of an injection molding screw as one embodiment is shown in FIGS.

In the embodiment of the screw shown in FIGS. 6 and 7, the rotary shaft portion and the spiral flight provided on the outer peripheral surface thereof are provided, and the angle formed between the axis of the rotary shaft portion and the base end side surface of the flight is These are formed so as to gradually become larger on the nozzle side than on the hopper side. In that case, it has the compression part formed so that the depth of the screw groove M between flights or the length of the axial direction of a screw groove may become small as it goes to a nozzle side from a hopper side. In the compression section in the section in which the flight is formed, it is preferable that the flight angle gradually and continuously increase from the hopper side toward the nozzle side.

Thus, when forming a flight, the flight is formed such that the angle of the section disposed on the tip side from the compression section is larger than the angle of the section disposed on the hopper side from the compression section. It is preferable.

By adopting such a mode, at least a part of the flight is such that the tip side (nozzle side) portion of the flight and the axis of the rotating shaft portion are in flight with the base side (hopper side) portion. It is formed such that the angle formed with the base end side surface of the is large. At that time, in the screw groove M formed between the flights, the molten resin material stays near the hopper and the unmelted resin material stays near the nozzle. With this configuration, the shearing force acting on the resin material staying closer to the nozzle can be strong at the hopper side portion and weak at the nozzle tip side portion in a partial section or the whole of the flight. it can.

For this reason, a strong shearing force is applied to an unmelted resin material at an early stage to promote melting, and an excessive shearing force can be prevented from acting on the resin material after melting. The molten state can be effectively leveled at an early stage.

In the present invention, in addition to such a mode, as a specific mode in consideration of the process up to the achievement of kneading / melting at an early stage of the plasticizing process, a spiral screw groove and a preceding one are adjacent thereto. A tributary formation opening (notch) is formed in the flight part between the screw grooves, and a part of the solid bed (SB) or a part of the melt pool (MP) is forcibly introduced into the solid-liquid phase kneading zone. Thus, it has been found that it is preferable to provide a zone for forcibly kneading both solid-liquid phases and promoting melting of the solid phase at an early stage of the plasticization process (see FIGS. 4 and 5). 4 and 5, the illustration forms of the branch flow forming opening are different, but these conceptually show that a notch opening is formed in a part of the flight.

More specifically, according to the present invention, as shown in FIGS. 4A and 4B, a branch forming opening is formed in the flight 33 between the spiral screw groove M and the preceding screw groove M adjacent thereto. (Notch) 37 is formed to forcibly introduce a part of the melt pool (MP) in the preceding screw groove M into the solid phase portion as the solid bed (SB) in the screw groove M It is. FIG. 4B shows a state in which a part of the melted part jumps into the unmelted part through the tributary formation opening (notch part) 37. This makes it possible to achieve an injection molding method comprising a novel kneading / melting model in which the solid-liquid phase is rapidly kneaded and the melting of the solid phase part is promoted at an early stage of the plasticizing process of the resin material.

Further, contrary to the resin behavior of such an injection molding model, depending on the difference in the resin to be injection molded and the difference in the injection conditions, as shown in FIGS. 5 (a) and 5 (b), a spiral screw groove A tributary formation opening (notch) 37 is formed in a flight 33 between M and the preceding screw groove M adjacent thereto, so that a part of the solid phase portion as a solid bed (SB) is replaced with the preceding screw groove. It is forcibly introduced into the melt pool (MP) in M. FIG. 5B shows a state in which a part of the unmelted portion jumps into the melted portion through the tributary flow forming opening (notched portion) 37. As a result, an injection molding method comprising a novel kneading / melting model in which both solid-liquid phases are rapidly kneaded in an early stage of the plasticizing process of the resin material, and melting of the solid phase is promoted can be achieved.

Furthermore, the present invention proposes an injection molding machine and an injection molding nozzle used in the method of the present invention.

The injection molding method of the present invention comprises:
The resin material is supplied from the hopper into the heating cylinder, the screw having the spiral flight is rotated in the heating cylinder, and the resin material supplied from the hopper is kneaded in the screw groove formed by the spiral flight. When sending forward while melting,
A portion of the solid bed (SB) in the screw groove or the melt in the preceding screw groove through a tributary opening that forms a tributary to the spiral flight between the screw groove and the screw groove preceding the groove. By forcibly introducing a part of the pool (MP) into the solid-liquid phase kneading zone, both the solid-liquid phases of the resin material are kneaded at an early stage of the plasticization process to promote melting of the solid phase.
Thereafter, the screw is moved backward while rotating by a predetermined number of revolutions, and the kneaded and melted resin material is weighed,
After the metering operation, the screw is advanced, and the measured molten resin material is injected through the injection nozzle into the mold cavity closed.

Furthermore, the injection molding method of the present invention comprises:
Forced introduction of a portion of the solid bed (SB) in the screw groove through the tributary opening or a portion of the melt pool (MP) in the preceding screw groove may result in a solid bed (SB) in the screw groove. In this part, a part of the melt pool (MP) in the preceding screw groove is forcedly introduced into the solid-liquid phase kneading zone through the tributary formation opening and kneaded to thereby obtain a solid-liquid both-phase resin material. Is kneaded at an early stage of the plasticizing process to promote melting of the solid phase.

Furthermore, the injection molding method of the present invention comprises:
Forced introduction of a portion of the solid bed (SB) in the screw groove through the tributary opening or a portion of the melt pool (MP) in the preceding screw groove may result in a solid bed (SB) in the screw groove. Is forced into the melt-pool (MP) in the preceding screw groove through the tributary opening and introduced into the solid-liquid phase kneading zone to knead the resin material in both the solid and liquid phases. It is characterized by kneading at an early stage of the plasticizing process to promote melting of the solid phase.

Furthermore, the injection molding method of the present invention comprises:
Forcing a portion of the solid bed (SB) in the screw groove or a portion of the melt pool (MP) in the preceding screw groove into the solid-liquid phase kneading zone through the tributary opening. The screw groove is introduced at an intermediate position of the entire length of the screw groove or at a position ahead of the intermediate position, and knead the resin material of both solid-liquid phases at an early stage of the plasticizing process to promote melting of the solid phase. And

The injection molding machine of the present invention is
A heating cylinder having a plurality of heaters, a hopper for supplying a resin material to the heating cylinder, and an injection molding screw accommodated in the heating cylinder so as to be able to rotate and move forward and backward are provided. The injection molding screw has a helical flight, the resin material supplied from the hopper is accommodated in a screw groove formed by the helical flight, and the resin material in the screw groove is kneaded by rotation. An injection molding machine configured to feed forward while melting,
A spiral flight between the screw groove and the screw groove preceding the groove is provided with a branch forming opening that forms a tributary, and a part of the solid bed (SB) in the screw groove through the branch forming opening. Alternatively, by forcibly introducing a part of the melt pool (MP) in the preceding screw groove into the solid-liquid phase kneading zone, the resin material of both solid-liquid phases is kneaded and solidified at an early stage of the plasticization process. It is configured to promote melting of the phase.

Furthermore, the injection molding machine of the present invention is
Forcing the introduction of a portion of the solid bed (SB) in the screw groove through the tributary opening or a portion of the melt pool (MP) into the preceding screw groove, the solid bed ( SB) has a tributary formation opening for forming a tributary for forcibly introducing a part of the melt pool (MP) in the preceding screw groove into the solid-liquid phase kneading zone. It is characterized in that solid phase and liquid phase resin materials are kneaded at an early stage of the process to promote solid phase melting.

Furthermore, the injection molding machine of the present invention is
Forcing the introduction of a portion of the solid bed (SB) in the screw groove through the tributary opening or a portion of the melt pool (MP) into the preceding screw groove, the solid bed ( SB) has a tributary opening that forms a tributary to force a portion of the SB) into the melt pool (MP) in the preceding screw groove. A resin material is kneaded to promote melting of the solid phase.

Furthermore, the injection molding machine of the present invention is
The injection molding screw has a tributary opening for forming a tributary for forcibly introducing a part of the solid bed (SB) in the screw groove or a part of the melt pool (MP) in the preceding screw groove. By providing a part at an intermediate position of the entire length of the screw groove or a position in front of the intermediate position, the solid-liquid and double-phase resin materials are kneaded at an early stage of the plasticizing process to promote solid phase melting. It is characterized by.

The screw for injection molding of the present invention is
A rotating shaft, and a spiral flight provided protruding from the outer peripheral surface of the rotating shaft,
A solid-liquid phase kneading zone can be constructed at an early stage of the plasticizing process through a tributary formation opening that forms a tributary in a partial section of the spiral flight from the central portion of the spiral flight toward the tip of the screw. In addition, a branch flow forming opening is formed so as to force a part of the solid bed (SB) in the screw groove or a part of the melt pool (MP) in the preceding screw groove into the solid-liquid phase kneading zone. It is characterized by comprising.

Furthermore, the screw for injection molding of the present invention is
A plurality of the spiral flights are provided at least in a partial section in the axial direction of the rotating shaft,
A tributary formation opening that forms the tributary is provided in at least one of the plurality of flights, and a screw groove on the rear side and a preceding screw groove on the front side across the spiral flight. It is a notch part connected, It is characterized by the above-mentioned.

Furthermore, the screw for injection molding of the present invention is
A tributary formation opening that forms the tributary is provided in a spiral flight between two adjacent screw grooves, and a tributary formation opening provided in the helical flight between these adjacent grooves is in the circumferential direction. It is characterized by being displaced.

The invention of the present application has been achieved by injection molding by the obtained new plasticization process as a result of examination by empirical experiments. For this purpose, the present invention forms a tributary flow in addition to the molten resin flow as the main flow, and a part of the solid phase part of the supplied synthetic resin or a part of the liquid phase part at an early stage of the plasticization process. Is introduced into the solid-liquid phase kneading zone of the screw groove M adjacent thereto and forcibly kneaded, whereby the melting of the solid phase portion can be promoted.

In the present invention, a part of an unmelted solid bed (SB) staying in a screw groove or a part of a melt pool (MP) in a screw groove preceding the screw bed is introduced into a solid-liquid phase kneading zone. By promoting the kneading / melting of both solid-liquid phases at an early stage of the conversion process, the resin material can be efficiently and uniformly kneaded / melted.

In order to realize the kneading / melting mechanism as described above, the present invention is specifically a mainstream in which the resin material supplied from the hopper supply port is kneaded, melted and pumped from the hopper side to the nozzle side. In addition to the molten resin flow, a tributary is formed by a tributary formation opening (notch) provided in the spiral flight. Through this tributary, a part of the unmelted solid bed (SB) staying in the screw groove, or a part of the melt pool (MP) in the screw groove preceding the solid bed is mixed with the solid-liquid phase kneading zone in the adjacent screw groove. It is possible to promote melting of the solid phase portion by introducing the mixture into the inside and forcibly kneading.

In other words, while the resin is kneaded and melted in the screw groove from the proximal end side to the distal end side of the heating cylinder, the molten resin flow as the main flow is pumped, and a branch flow forming opening is formed in the middle of the spiral flight forming the spiral groove. Forming a part of the melt pool (MP) from the adjacent preceding screw groove in the solid phase portion as a solid bed (SB) in the screw groove, By forcibly introducing a part of the melt pool (MP) into the solid-liquid phase kneading zone and kneading, the resin material of both solid-liquid phases is kneaded and melted from the early stage of the plasticizing process to make it uniform. It becomes possible.

In the present invention, the mainstream molten resin flow is pumped while kneading and melting the resin material supplied from the hopper supply port in the screw groove formed by the spiral flight from the proximal end side to the distal end side of the heating cylinder. At this time, a tributary formation opening (notch) is formed in the middle of the spiral flight. As a result, contrary to the behavior of the resin in the kneading and melting mechanism in the plasticization process described above, a part of the solid phase portion as a solid bed (SB) in the screw groove is replaced with a melt pool in the preceding screw groove. By forming a tributary into (MP) and forcibly introducing it into the solid-liquid phase kneading zone, it becomes possible to homogenize the resin material by kneading and melting from an early stage of the plasticization process. .

Furthermore, since the injection molding method, injection molding machine and screw configuration of the present invention are difficult to form a solid bed (SB) that is difficult to mix in the screw groove M, there is also an effect of coloring and kneading, which improves color unevenness. Is also effective.

It is a top view which shows schematic structure of the injection molding machine which concerns on one Embodiment of this invention. It is a side view which shows the screw for injection molding with which the injection molding machine which concerns on one Embodiment of this invention is equipped, (a) is the whole screw, (b) is what equipped the screw with the screw head, (c) is (b) ) With a nozzle and a heating cylinder. It is a fragmentary sectional view which shows the detail of the kneading | mixing and melting part of the screw for injection molding of FIG. It is a figure which illustrates typically the behavior in the melting mechanism of resin in the screw groove of the screw used for the injection molding method concerning one embodiment of the present invention. It is a figure which illustrates typically the behavior in the melting mechanism of the resin in the screw groove of the screw used for the injection molding method concerning another embodiment of the present invention. It is a side view of the screw for injection molding with which the injection molding machine of another mode is provided. It is a side view of the screw for injection molding with which the injection molding machine of another mode of Drawing 5 is provided. It is a figure which shows typically the melting mechanism in the screw groove of the screw for injection molding of FIG. It is a figure which illustrates typically the behavior in the melting mechanism of resin in the injection molding method concerning the embodiment of the prior art of the present invention.

Hereinafter, an injection molding method according to an embodiment of the present invention, an injection molding machine used in the method, and a screw of the injection molding machine will be described with reference to the drawings. However, although the drawings are specifically described along the embodiments of the present invention, they are for facilitating the understanding of the present invention and not for reducing the technical scope.

FIG. 1 is a diagram showing a schematic configuration of an injection molding machine according to an embodiment of the present invention. FIG. 2 is a side view of an injection molding screw provided in the injection molding machine of FIG. FIG. 3 is a partial detail view of the injection molding screw of FIG.
FIG. 4 is a diagram schematically illustrating the behavior of the resin in the kneading / melting mechanism in the screw groove of the injection molding screw shown in FIG. 2 as one embodiment. FIG. 4 (a) shows one continuous virtual screw groove as one embodiment of the present invention, and shows a continuous transition of the kneading / melting state in the screw groove. FIG. 4 (b) is a development of three adjacent flights, and a tributary flow is formed by providing a tributary formation opening (notch) in the flight section of the screw groove and the preceding screw groove adjacent thereto. It is a conceptual diagram showing a situation where a part of the melt pool (MP) is introduced into the solid phase of the solid bed (SB).
FIG. 5 is a diagram corresponding to FIG. 4, and is a diagram schematically illustrating the behavior of the resin in the melting mechanism in the screw groove of the screw used in the injection molding method according to another embodiment of the present invention. . FIG. 5A shows, as another embodiment of the present invention, a single continuous virtual screw groove, and shows a continuous transition of the kneading / melting state in the screw groove. FIG. 5 (b) is an expanded view of three adjacent flights, and a tributary flow is formed by providing a tributary formation opening (notch) in the flight section of the screw groove and the preceding screw groove adjacent to the screw groove. It is a conceptual diagram showing a situation where a part of the solid bed (SB) is introduced into the liquid phase of the melt pool (MP).
Moreover, the screw shown in FIG.6 and FIG.7 is a screw which consists of one aspect for solving the same subject as this invention, and FIG. 8 is a conceptual diagram which illustrates the melting mechanism typically. FIG. 9 is a diagram schematically illustrating the behavior of the molten resin in the conventionally considered resin melting mechanism.

An injection molding machine 1 according to an embodiment of the present invention shown in FIG. 1 is for molding a molded body using a thermoplastic granular resin material (resin pellet) as a raw material. The injection molding machine 1 has a mold clamping unit 10 and an injection unit 20 disposed on a machine base 2.

The mold clamping unit 10 moves the movable die plate 12 forward and backward with respect to the fixed die plate 14 by bending the toggle link mechanism 11 using a driving force of a motor (not shown) as a driving source. Thereby, the movable mold 13 attached to the movable die plate 12 is subjected to the mold closing operation and the mold opening operation with respect to the fixed mold 15 attached to the fixed die plate 14.

The injection unit 20 includes a cylindrical heating cylinder 21, an injection nozzle 22 provided at the tip of the heating cylinder 21, and a resin material that is accommodated in the heating cylinder 21 and supplied to the heating cylinder 21. An injection molding screw (hereinafter sometimes simply referred to as “screw 30”) that is kneaded and melted and pumped toward the nozzle side, a support member 23 that supports the screw 30 so as to be able to rotate and move forward and backward, and a heating cylinder 21 It has a hopper 24 for introducing a resin material therein, a hopper block 25 provided with the hopper 24, and a plurality of heaters 26 disposed outside the heating cylinder 21.

In the injection molding operation of the injection molding machine 1, the resin material is heated by the shearing force acting on the resin material when the screw 30 accommodated in the heating cylinder 21 is rotated, and the heating cylinder 21 is heated. The heater 26 is heated to a high temperature. As a result, the resin material supplied from the supply port 24a of the hopper 24 is kneaded and melted while being fed from the proximal end side (hopper side) to the distal end side (nozzle side) of the heating cylinder 21, and from the rear to the front. A molten resin flow is formed as a main flow toward the vehicle. In the molten resin flow as the main flow, solid resin pellets are kneaded and melted during the pressure feeding from the rear to the front. The kneaded and melted resin material is weighed by rotating the screw 30 back at a predetermined rotation speed by a rotational driving means such as a metering motor (not shown). After the metering operation, the screw 30 is advanced by an advancing / retracting drive means including an injection motor and a ball screw mechanism (not shown), whereby a predetermined amount of molten resin material is mold-closed through the injection nozzle 22. The product is molded by being injected into the inside. In the present specification, the injection nozzle 22 side is referred to as “front”, and the hopper side is referred to as “rear”.

Next, the screw 30 accommodated in the heating cylinder 21 will be described in detail. Since the configuration of the screw is the same as that of the present invention, first, the configuration of the screw shown in FIGS. 6 and 7 will be described as one embodiment in consideration of promotion of kneading / melting.

This screw does not directly achieve the effect of the present invention, which is intended to achieve kneading and melting at an early stage of the plasticizing process, but there are many configurations common to the screw of the present invention. The configuration and function of the screw will be described. The screw 30 is sequentially provided with a supply unit (A), a compression unit (B), and a measurement unit (C) from the base end side (rear side: hopper side) to the front end side (front side: nozzle side). Further, the screw 30 is provided so as to protrude from the outer peripheral surface of the rotary shaft portion 31 and the screw head 32 functioning as a backflow suppression valve provided at the tip of the rotary shaft portion 31. The spiral flight 33 is provided.

The rotation shaft portion 31 is formed to have the same diameter throughout the supply portion (A), and the compression portion (B) has a continuous diameter from the base end side (hopper side) to the tip end side (nozzle side). The measuring portion (C) is formed to have the same diameter throughout, and has a larger diameter than the portion serving as the supply portion (A).

The flights 33 formed on the outer periphery of the rotary shaft portion 31 are formed so that the distance from the axis L of the rotary shaft portion 31 to the outer peripheral tip surface is constant and the entire pitch is a spiral. Here, in the compression part (B), the diameter of the rotating shaft part 31 increases from the base end side (hopper side) to the front end side (nozzle side), so that the compression part (B) has a base end side (hopper side). The depth of the screw groove M formed between the flights 33 decreases from the side) toward the tip side (nozzle side). In the compression section (B), the flight pitch (the length of the screw groove M in the axis L direction) continuously decreases from the proximal end (hopper side) toward the distal end (nozzle side). You may form.

The flight 33 has a flight part 34 of the supply part (A), a flight part 35 of the compression part (B), and a flight part 36 of the weighing part (C).

The flight part 34 of the supply part (A) is formed so that the angle α formed between the axis L of the rotary shaft part 31 and the base end side face 34a is constant throughout. The flight portion 34 of the supply unit (A) is a section arranged in the supply unit (A) on the proximal end side with respect to the compression unit (B) in the flight 33.

The flight part 35 of the compression part (B) is connected to the flight part 34 of the supply part (A), and is connected to the axis L and the base of the rotary shaft part 31 from the base end side (hopper side) toward the tip end side (nozzle side). The angle β formed with the end side (hopper side) surface 35a is formed to be continuously increased. Here, β7> β6> β5> β4> β3> β2> β1 ≧ α. The flight part 35 of the compression part (B) is a section arranged in the compression part (B) in the flight 33.

The flight portion 36 of the measuring portion (C) is connected to the flight portion 35 of the compression portion (B), and an angle γ (where γ ≧ β) formed between the axis L of the rotary shaft portion 31 and the base end side (hopper side) surface 36a. ) Is constant throughout. The flight part 36 of the measuring unit (C) is a section arranged in the measuring unit (C) on the tip side (nozzle side) of the compression unit (B) in the flight 33.

In this embodiment, the angle α is 20 degrees, the angle β continuously changes from 20 degrees to 80 degrees, and the angle γ is 80 degrees. However, the angles α, β, and γ are other than these. It may be a size.

The flight 33 includes the axis L of the rotating shaft 31, the flight part 34 of the supply part (A), the flight part 35 of the compression part (B), and the front end side surface of the flight part 36 of the weighing part (C) (on the left side in FIG. 7). The angle formed with the (facing surface) is constant, for example, 90 degrees.

Next, the behavior of the molten resin in the molten state in the melting mechanism of the resin material in the screw groove M of the compression portion (B) in the injection molding method of the present invention using such a screw 30 will be described. In the injection molding method of this aspect, in the molten resin flow as the main flow in the screw groove M, the solid bed (SB) as the solid phase and the liquid phase so as to overlap the solid bed (SB). A melt film (MF) is formed. In the melt film (MF) in the liquid phase melted along the inner periphery of the heating cylinder 21, the melt pool (MP) scraped by the flight 33 is closer to the rear of the screw groove M, that is, closer to the base end (closer to the hopper). Formed. Such behavior of the resin is similar in both the present invention and the prior art as shown in FIGS.

And in the screw groove M of the base end side (hopper side) part in a compression part (B), as shown to Fig.8 (a), the axis line L of the rotating shaft part 31 and the flight 33 (specifically, compression) Part of the flight part 35) has a small angle with the base end side surface 35a, and thus there are many portions where the distance between the base end side surface 35a and the inner surface 21a of the heating cylinder 21 is narrow, and therefore, with respect to the solid bed (SB) Has a relatively strong shear force. Therefore, melting of the solid bed (SB) in the screw groove M can be promoted.

Further, in the screw groove M on the tip side (nozzle side) of the compression portion (B), as shown in FIG. 8B, the axis L of the rotary shaft portion 31 and the flight 33 (specifically, the compression portion Since the angle formed by the base end side surface 35a of the flight part 35) is large, the distance between the base end side surface 35a and the inner surface 21a of the heating cylinder 21 is wide, so that the molten resin material refluxed as shown by the arrows. The working shear force is suppressed.

According to the injection molding machine 1 provided with such a screw 30, the flight portion 35 in a partial section of the compression portion (B) is located on the tip side (nozzle side) portion from the base end side (hopper side) portion. The angle β formed between the axis L of the rotating shaft portion 31 and the base end side surface 35a is increased. As a result, the molten resin material (melt pool MP) stays near the base end (hopper side) in the screw groove M formed between the flights 33, and is not near the tip end (nozzle side). Molten resin material (solid bed SB) stays. As a result, the shearing force acting on the resin material (solid bed SB) staying near the tip is strengthened on the base end side (hopper side) of the flight portion 35 of the compression portion (B) and weak on the tip side (nozzle side). can do. Therefore, since a strong shearing force can be applied to unmelted resin material (solid bed SB) at an early stage to promote melting, the molten state of the resin material can be achieved at an early stage and effectively melted. Can do.

When the overall configuration of the screw 30 is viewed, the angle γ of the flight part 36 of the weighing unit (C) is larger than the angle α of the flight part 34 of the supply unit (A). Accordingly, a strong shearing force is applied to the unmelted resin material (solid bed SB) in the supply section (A) to promote melting, and the molten resin material (melt pool MP) in the measuring section (C). The molten state can be effectively leveled.

Further, the depth of the screw groove M of the flight portion 35 of the compression portion (B) is formed so as to become shallower from the base end side (hopper side) toward the tip end side (nozzle side), and the angle β is set to the base end side. It is formed so as to increase from the (hopper side) toward the tip side (nozzle side). Since it did in this way, the shear force which acts on the resin material which stagnates near the front-end | tip in the screw groove M can be made comparatively strong initially, and can be gradually weakened as it progresses from the base end side to the front end side. . Therefore, the molten state of the resin material can be made more effective.

Further, since the angle α, the angle β, and the angle γ are within a range of 20 degrees to 80 degrees, the angle range is relatively large, and the shearing force can be changed in a wide range.

In the above-described aspect, the angle β of the flight portion 35 of the compression unit (B) is continuously changed from 20 degrees to 80 degrees, but is not limited thereto. For example, the flight portion 35 of the compression section (B) is formed so that the angle β is constant over the whole, for example, 50 degrees, and the relationship between the angle α, the angle β, and the angle γ is You may make it change in steps as it progresses to a supply part (A), a compression part (B), and a measurement part (C) so that it may become (gamma)> (beta)> (alpha).

The kneading / melting model in the injection molding machine has been described in, for example, the conventionally known Tadmor model, but in the field of the injection molding machine, it has been verified that it is the same as the actual operation. Yes. In this kneading / melting model, the portion of the solid body called the solid bed (SB) has a relatively low temperature and is difficult to melt compared to the temperature of the portion called the melt pool (MP) in the molten state. Therefore, at an early stage of the injection molding model, the solid-phase solid bed (SB) portion, which is relatively low in temperature and hardly melted, is forcibly replaced with the molten liquid-phase melt pool (MP) portion. By kneading, melting of the solid phase portion can be promoted.

The screw configuration of the above aspect is effective as a means for accelerating the kneading / melting of the molten resin material as the mainstream, but the present invention is an early stage of the plasticizing process according to a further novel aspect. The solid phase solid bed (SB) of the solid phase in the screw groove, by introducing a part of the melt pool (MP) of the liquid phase in the preceding screw groove, or the solid bed (SB) of the solid phase By introducing a part of the resin into the liquid phase melt pool (MP) in the preceding screw groove, the resin material in both solid and liquid phases is forced to knead rapidly and melt, thereby promoting solid phase melting. It is possible to provide an injection molding method and an injection molding machine.

However, as described above, the temperature of the unmelted portion is relatively low with respect to the melted portion of the resin material (melt pool portion MP), and when the solid bed (SB) is generated, it is difficult to melt. is there. Therefore, the inventors introduce a part of the melt pool (MP) having a higher temperature than the generated solid bed (SB) into the unmelted solid bed (SB) and forcibly knead (FIG. 4). (See (b)) or forcibly kneading by introducing a part of the unmelted solid bed (SB) into the melt pool (MP) where the temperature is high (see FIG. 5 (b)). As a result, various trial and error experiments and verifications were conducted to efficiently knead and dissolve both the solid and liquid phases of the resin material in the solid-liquid phase kneading zone at an early stage of the plasticization process.

As a specific injection molding machine for that purpose, what type of screw is adopted is shown in FIG. 2 and FIG. 3 as the flight configuration of the part called the compression part and the measurement part in the conventional screw. It is comprised as follows. This is because a notch 37 is provided as a branch flow forming opening in a part of the multi-threaded thread, and a part of the melt pool (MP) in the screw groove M preceding the part of the solid bed (SB) in the screw groove M. In other words, a tributary flow is formed in the notch portion of the flight so that the molten phase of the liquid phase jumps into the unmelted portion of the solid phase. Further, by providing the flight with a notch configuration as a tributary forming section, a part of the solid bed (SB) in the screw groove M is forced to a portion of the melt pool (MP) in the preceding screw groove M. In this way, the solid-liquid both-phase resin material can be kneaded at an early stage of the plasticizing process and can be easily melted.

Conventionally, a screw generally called a subflight screw has been known as a screw for promoting melting. This is intended to speed up melting by providing a plurality of flights in a plurality of measuring sections, but the unmelted part and the melted part are separated by the flight.

Therefore, in the present invention, as shown in FIGS. 4A and 4B, the melted portion (melt pool MP) in the preceding screw groove M into the unmelted portion (solid bed SB) in the screw groove M. ) To form a tributary so that a part of it can be introduced. Further, as shown in FIGS. 5A and 5B, a part of the unmelted portion (solid bed SB) in the screw groove M is replaced with a portion of the melted portion (melt pool MP) in the preceding screw groove M. It is set as the structure which forms a tributary so that it can introduce into. Thus, a part of the melted part (melt pool MP) in the preceding screw groove M or a part of the unmelted part (solid bed SB) in the screw groove M was formed in the spiral flight 33. It is possible to forcibly knead in the solid-liquid phase kneading zone through the branch forming opening 37, and to send it forward without dividing the melted portion and the unmelted portion. The formation of the tributary can be achieved by forming a notch 37 as a tributary forming opening in the spiral flight 33, which promotes the kneading and melting of both the solid and liquid phases in the solid and liquid phase kneading zone. Is.

The conventional screw is composed of a continuous single thread, but a plurality of flights may be provided in order to make a structure in which a portion not melted is ground. When such a screw is used, the solid phase resin material (solid bed SB) staying in the first part of the screw groove M is sent forward, but the ability to melt at a certain region is reduced. End up. This is because the ability to melt by the rotation of the screw cannot keep up with the ability to pump. In contrast, in the injection molding method and the injection molding machine using the screw according to the present invention shown in FIG. 2 and FIG. 3, the transport speed seems to be relatively slow, but the molten resin flow as the mainstream Since there are few undissolved parts of the solid phase, stable plasticization can be achieved from an early stage of the plasticization process. This has been confirmed by experiments, and according to such a configuration, the amount of the resin material is increased or decreased, but the plasticizing ability is not affected.

In addition to stabilizing plasticization, paying attention to the color mixing or kneading function of the resin material, the ability to stir in the solid bed (SB) when mixed with a few percent of pigment that adds color to the resin material Therefore, the kneading ability becomes small and the color becomes difficult to mix, and in order to solve the problem, each company has made a screw considering the kneading function.

An injection molding method and an injection molding machine having a screw configuration according to the present invention include a flight that forms a screw groove M in addition to a molten resin flow as a main flow from a proximal end (hopper side) to a distal end side (nozzle side). Constructing a tributary through the tributary formation opening 37 (notch) between the flight 33 and the flight 33 is novel. In addition, this also makes it possible for the resin material to go back and forth. In the conventional parallel flight configuration, the resin material is pumped along the same screw groove. However, in the present invention, in addition to the molten resin flow as the main flow, a tributary formation opening that forms a tributary in a part of the flight 33. A notch 37 is provided as a part. As a result, it is possible to form a tributary that allows the resin material to move back and forth between the first lead and the second lead of the screw groove M, and kneading both solid-liquid phases. It will be promoted.

When a screw having a plurality of screw grooves M having different pitches is used, if the above-described tributary flow is formed between the screw grooves M, an unmelted portion (solid bed SB) in the screw groove M is formed. A part of the melt pool (MP) in the preceding screw groove M jumps in adjacent to the part of the screw groove M, or a part of the unmelted part (solid bed SB) in the screw groove M is adjacent to the opposite direction. A notch portion 37 as a tributary formation portion is formed in the flight 33 so as to jump into the melt pool (MP) portion in the preceding screw groove M.

The formation of the notch in the flight itself was a shape that has been conventionally known as a shape in which a melted resin material is agitated in a dalmage screw. However, conventionally, in order to stir after the molten resin material is melted, the conventional dull image portion is formed on the relatively distal end side of the screw. In a conventional kneading / melting model, a solid bed (SB) can be formed in a form in which a resin material melts, and is melted and liquefied in a molten resin flow as a main stream. That is, in the conventional kneading / melting model, there is no idea that the dull image is applied at the position of the screw where the resin material is not melted.

On the other hand, in the present invention, a tributary formation opening 37 (notch) is formed in the spiral flight 33, and the solid-phase solid bed (SB) is formed from a relatively early stage in the plasticizing process. By forcibly introducing a part of the melt pool (MP) of the liquid phase in the preceding screw groove M into the kneading zone, the solid and liquid phases are forcibly kneaded to melt the solid bed (SB). To promote. Alternatively, the present invention forces both solid and liquid phases by forcing a portion of a solid phase solid bed (SB) into a liquid phase melt pool (MP) in a preceding screw groove M. To promote melting of the solid bed (SB).

More specifically, in one aspect of the present invention, a branch forming opening 37 is formed so as to form a tributary of the resin flow in the flight 33 between one screw groove M and the preceding screw groove M. (Notch portion) and a solid phase solid bed (SB) portion in one screw groove M, a part of the liquid phase melt pool (MP) in the preceding screw groove M It is forcibly introduced to knead the undissolved solid phase portion and the melted liquid phase portion from an early stage of the plasticizing process to promote melting. That is, a notch portion 37 as a branch flow forming portion is provided in a flight portion called a compression portion arranged in a central portion of a conventional screw, and a melt pool (SB) is formed in a solid bed (SB) portion in the screw groove M. MP) is introduced to promote melting of a solid phase in which both solid-liquid phases are forcibly kneaded. Thus, the solid bed (SB) and the melt pool (MP) are forcibly kneaded so as to enter and mix at an early stage of the plasticizing process. Further, the present invention promotes melting of a solid phase in which a part of a solid bed (SB) is introduced into a melt pool (MP) in a preceding screw groove M to forcibly knead both solid and liquid phases. Anyway.

However, the position where the notch 37 is formed can be selected as appropriate, and is not limited by whether or not it is the compression part of the screw. As described above, the concept relating to the kneading / melting behavior is completely different between the injection molding method using the conventional injection molding model and the injection molding method using the injection molding model of the present invention.

In other words, the present invention is a part of the solid bed (SB) of the solid phase of the single screw groove M or a part of the melt pool (MP) of the liquid phase of the preceding screw groove M. A good result can be obtained by being introduced into the kneading zone freely through the tributary opening 37 (notch) and forcibly kneading so that both the solid phase and the liquid phase dance. With such a configuration, a part of the melt pool (MP) in the preceding screw groove is introduced into the kneading zone of the solid bed (SB) portion in the screw groove to force the solid phase solid bed (SB). It stirs and promotes melting of the solid phase part and does not stay as a large solid bed (SB). Alternatively, a part of the solid bed (SB) in one adjacent screw groove is introduced into the kneading zone of the melt pool (MP) part in the preceding screw groove to force both solid-liquid phases. Kneading to promote melting of the solid phase part.

In the conventional kneading / melting model, the solid bed (SB) part melts gradually along the molten resin flow as the main stream. From the early stage of the composting process, the melted resin material (melt pool MP) and the unmelted resin material (solid bed SB) are forcibly mixed in the same flight to knead and solidify It consists of the idea of promoting the melting of On the other hand, the concept of the conventional subflight is an idea of applying excessive pressure to crush and melt by force by narrowing the flight interval sequentially.

As shown in FIG. 2, the screw 30 used in the injection molding method and injection molding machine of the present invention comprises a rear hopper side supply unit 30-1 and a front nozzle side kneading unit 30-2. As shown in FIG. 2, the screw 30 has a supply portion 30-1 at the rear half of the total length of the screw and a kneading portion 30-2 at a front half. The transition part from the supply part 30-1 to the kneading part 30-2 is preferably the central part of the entire length of the screw. Here, the central portion does not mean the position of exactly 1/2 of the total length of the screw, but the position of the intermediate portion of the total length of the screw. If the position of the intermediate portion, depending on the type of resin and molding conditions, It is possible to change the position of the transition part back and forth. However, it is desirable to be located at a substantially central portion. Thereby, kneading and melting can be achieved rapidly at an early stage of the plasticizing process. Reference numeral 32 in FIG. 2B denotes a screw head, reference numeral 21 in FIG. 2C denotes a heating cylinder, and reference numeral 32 denotes a screw head. The resin material supplied from the hopper into the heating cylinder 21 is melted by the rotation of the screw 30 while being heated by the plurality of heaters 26 and is transferred to the front side on the nozzle side.

Further, the details of the kneading part 30-2 of the screw 30 of the present invention are shown in FIG. 3, and the kneading groove depth changing part 30-3 in which the dalmage is formed and the kneading groove depth in which the dalmage is formed are constant. It consists of part 30-4. In the embodiment of the screw 30 of the present invention shown in FIGS. 2 and 3, the axial lengths of the kneading groove depth changing portion 30-3 and the kneading groove depth constant portion 30-4 are substantially equal. Although it is formed, it can be appropriately changed depending on the material used for molding.

The screw shaft diameter D of the screw 30 is D1 at the rear of the kneading groove depth changing portion 30-3 on the hopper side, and at the transition portion between the kneading groove depth changing portion 30-3 and the kneading groove depth constant portion 30-4. When D3 is D3 in front of the nozzle side of the constant kneading groove depth portion 30-4,
D1 <D2
D2 = D3.
As a result, the depth to the groove bottom in the kneading groove depth changing portion 30-3 changes, and the depth to the groove bottom in the kneading groove depth constant portion 30-4 is formed constant. It is desirable that the change in depth to the groove bottom in the kneading groove depth changing portion 30-3 is continuously changed at a constant inclination angle. Of course, it is also possible to change the rate of change (inclination angle) so as to change continuously or stepwise.

As described above, in the screw 30 of the present invention, the flight 33 is entirely formed from the central portion of the screw 30 toward the front side of the nozzle, and the flight 33 has a notch 37 as a branch forming portion. Is formed and constitutes a dalmage.

The injection molding screw 30 of the present invention includes a rotary shaft portion 31 and a spiral flight 33 provided so as to project from the outer peripheral surface of the rotary shaft portion 31. A tributary formation opening (notch) 37 serving as a tributary formation portion is formed in a partial section of the flight 33 from the central portion of 30 toward the tip of the screw 30. Thereby, the tributary which introduce | transduces a part of resin between the one screw groove M and the screw groove M preceding it can be formed.

Furthermore, in the injection molding screw 30 of the present invention, a plurality of flights 33 are provided at least in a partial section in the axial direction of the rotating shaft portion 31, and the branch flow forming opening 37 is formed of the plurality of flights 33. Provided on at least one flight 33. In this case, the tributary formation opening 37 communicates the screw groove M on the rear side (hopper side) and the screw groove M on the front side (nozzle side) with the one flight 33 interposed therebetween. 37. Further, in the injection molding screw 30 of the present invention, the branch flow forming openings 37 are provided in two adjacent flights 33, and the branch flow forming openings 37 provided in the adjacent flights 33 are circumferentially connected to each other. They are offset.

In the present invention, the solid bed (SB) in the screw groove M is sent in contact with the flight 33 because the resin material is pumped forward along the mainstream molten resin flow by the rotation of the screw. By forming the notch 37 as the branch forming opening in the flight 33, the melted portion (melt pool MP) in the screw groove M of another flight preceding the solid bed (SB) portion is mixed. It is done. Further, a part of the solid bed (SB) is mixed with the melted part (melt pool MP) in the screw groove M of another preceding flight.

As described above, in the kneading / melting model of the conventional method, the melt film (MF) is sequentially grown along the main flow of the molten resin flow and scraped off to form a melt pool (MP), which is an unmelted part (solid The bed SB) was gradually made smaller. On the other hand, the kneading / melting model of the present invention has a solid portion (solid) that is not melted from an early stage of the plasticizing process by a notch 37 as a tributary formation opening formed in a part of the flight 33. A part of the melted liquid phase part (melt film MF) in the screw groove M preceding the bed SB) is kneaded to rapidly melt the undissolved solid phase part (solid bed SB). Also, from an early stage of the plasticizing process, the undissolved solid phase portion (solid bed SB) is introduced into the melted liquid phase portion (melt film MF) in the preceding screw groove M and kneaded. The solid phase portion (solid bed SB) that is not melted is rapidly melted. This approach is performed from a compression section located in the central part of the screw.

The present invention relates to an injection molding method and injection capable of forming a forced solid-liquid phase kneading zone by coexisting both solid-liquid phases in the kneading zone of the screw groove M from an early stage of the plasticizing process. It relates to a molding machine. That is, this relates to an injection molding method and an injection molding machine based on a completely new injection molding model. Specifically, in the case of an injection molding machine using a 20 pitch screw over the entire length of the screw, a notched portion 37 is formed from a position about 1/2 (10 pitch) from the base end portion, and solid-liquid phase kneading is performed. It creates a state. The screw used in the injection molding method and the injection molding machine of the present invention has a main flight portion formed in the supply portion (30-1) of the base end portion, and a position close to about a half of the central portion of the total length of the screw. In the kneading section (30-2), a multi-strip flight is formed, and a notch 37 as a branch forming opening is formed in the multi-strip flight. This creates a solid-liquid phase kneading zone from an early stage of the plasticization process. The formation position of the solid-liquid phase kneading zone is preferably approximately in the vicinity of half the central portion of the entire screw, but the optimum position varies depending on the type of resin material. The position is preferably formed from the position where the resin starts melting by the rotation of the screw.

The present invention relates to an injection molding method based on a novel resin kneading / melting model, an injection molding machine, and a screw used in the injection molding method. It is also possible to form. In addition, the formation of the notch portion 37 as the flight tributary formation opening may be formed in the flight of only the solid-liquid phase kneading zone. You can have no flight.

In the present invention, the notch 37 as a branch forming opening of the flight is forcibly forming a solid-liquid phase kneading zone, and the starting position for forming the notch 37 is the base end of the full length of the screw. A position in the vicinity of ½ from the portion is desirable. Specifically, one of the specific embodiments of the present invention is notched in a multi-threaded flight formed from a position 1/2 to 3/4 from the base end of the entire length of the screw. The part 37 is formed.

From the conventional viewpoint, the idea of forming the subflight part from the compression part of the screw is insane from the screw manufacturer of those skilled in the art, and such a screw cannot be measured. It was what was said.

As a specific embodiment of the present invention, a notch portion 37 as a branch flow forming portion is formed in a multi-thread flight formed from a position 1/2 to a position 3/4 from the base end of the entire length of the screw. However, the notch part may be provided in the flight of the compression part of the screw shown in FIGS. 5 and 6.

Although the embodiment has been described above, the present invention is not limited to these examples. As long as a person skilled in the art appropriately adds, deletes, and changes the design of the above-described embodiment, and appropriately combines the features of the embodiment, the present application It is included in the scope of the invention. Of course, the present invention can also be applied to an extrusion apparatus.

DESCRIPTION OF SYMBOLS 1 ... Injection molding machine, 2 ... Machine stand, 10 ... Clamping unit, 11 ... Toggle link mechanism, 12 ... Movable die plate, 13 ... Movable die, 14 ... Fixed die plate, 15 ... Fixed die, 20 ... Injection Unit: 21 ... Heating cylinder, 21a ... Inner surface, 22 ... Injection nozzle, 23 ... Support member, 24 ... Hopper, 24a ... Supply port, 25 ... Hopper block, 26 ... Heating heater, 30 ... Screw (screw for injection molding), 30-1 ... Supply section, 30-2 ... Kneading section, 30-3 ... Kneading groove depth changing section, 30-4 ... Kneading groove depth constant section, 31 ... Rotating shaft section, 32 ... Screw head, 33 ... Flight 34 ... Flight part of supply part, 34a ... Base end side, 35 ... Flight part of compression part, 35a ... Base end side, 36 ... Flight part of measuring part, 36a ... Base end side, 37 ... Tributary forming part Notch Part 121, heating cylinder 130, screw for injection molding, 133, flight, L, axis, M, screw groove, SB, solid bed, MF, melt film, MP, melt pool.

Claims

The resin material is supplied from the hopper into the heating cylinder, the screw having the spiral flight is rotated in the heating cylinder, and the resin material supplied from the hopper is kneaded in the screw groove formed by the spiral flight. When sending forward while melting,
A portion of the solid bed (SB) in the screw groove or the melt in the preceding screw groove through a tributary opening that forms a tributary to the spiral flight between the screw groove and the screw groove preceding the groove. By forcibly introducing a part of the pool (MP) into the solid-liquid phase kneading zone, both the solid-liquid phases of the resin material are kneaded at an early stage of the plasticization process to promote melting of the solid phase.
Thereafter, the screw is moved backward while rotating by a predetermined number of revolutions, and the kneaded and melted resin material is weighed,
After this metering operation, the screw is advanced to inject the weighed molten resin material through the injection nozzle into a mold cavity closed.
Forced introduction of a portion of the solid bed (SB) in the screw groove through the tributary opening or a portion of the melt pool (MP) in the preceding screw groove may result in a solid bed (SB) in the screw groove. In this part, a part of the melt pool (MP) in the preceding screw groove is forcedly introduced into the solid-liquid phase kneading zone through the tributary formation opening and kneaded to thereby obtain a solid-liquid both-phase resin material. The injection molding method according to claim 1, wherein the melting of the solid phase is promoted by kneading at an early stage of the plasticizing process.
Forced introduction of a portion of the solid bed (SB) in the screw groove through the tributary opening or a portion of the melt pool (MP) in the preceding screw groove may result in a solid bed (SB) in the screw groove. Is forced into the melt-pool (MP) in the preceding screw groove through the tributary opening and introduced into the solid-liquid phase kneading zone to knead the resin material in both the solid and liquid phases. The injection molding method according to claim 1, wherein melting of the solid phase is promoted by kneading at an early stage of the plasticizing process.
Forcing a portion of the solid bed (SB) in the screw groove or a portion of the melt pool (MP) in the preceding screw groove into the solid-liquid phase kneading zone through the tributary opening. The screw groove is introduced at an intermediate position of the entire length of the screw groove or at a position ahead of the intermediate position, and knead the resin material of both solid-liquid phases at an early stage of the plasticizing process to promote melting of the solid phase. The injection molding method according to one of claims 1 to 3.
A heating cylinder having a plurality of heaters, a hopper for supplying a resin material to the heating cylinder, and an injection molding screw accommodated in the heating cylinder so as to be able to rotate and move forward and backward are provided. The injection molding screw has a helical flight, the resin material supplied from the hopper is accommodated in a screw groove formed by the helical flight, and the resin material in the screw groove is kneaded by rotation. An injection molding machine configured to feed forward while melting,
A spiral flight between the screw groove and the screw groove preceding the groove is provided with a branch forming opening that forms a tributary, and a part of the solid bed (SB) in the screw groove through the branch forming opening. Alternatively, by forcibly introducing a part of the melt pool (MP) in the preceding screw groove into the solid-liquid phase kneading zone, the resin material of both solid-liquid phases is kneaded and solidified at an early stage of the plasticization process. An injection molding machine configured to promote melting of a phase.
Forcing the introduction of a portion of the solid bed (SB) in the screw groove through the tributary opening or a portion of the melt pool (MP) into the preceding screw groove, the solid bed ( SB) has a tributary formation opening for forming a tributary for forcibly introducing a part of the melt pool (MP) in the preceding screw groove into the solid-liquid phase kneading zone. 6. An injection molding machine according to claim 5, wherein the resin material of both phases of solid and liquid is kneaded at an early stage of the process to promote melting of the solid phase.
Forcing the introduction of a portion of the solid bed (SB) in the screw groove through the tributary opening or a portion of the melt pool (MP) into the preceding screw groove, the solid bed ( SB) has a tributary opening that forms a tributary to force a portion of the SB) into the melt pool (MP) in the preceding screw groove. 6. The injection molding machine according to claim 5, wherein the resin material is kneaded to promote melting of the solid phase.
The injection molding screw has a tributary opening for forming a tributary for forcibly introducing a part of the solid bed (SB) in the screw groove or a part of the melt pool (MP) in the preceding screw groove. By providing a part at an intermediate position of the entire length of the screw groove or a position in front of the intermediate position, the solid-liquid and double-phase resin materials are kneaded at an early stage of the plasticizing process to promote solid phase melting. The injection molding machine according to one of claims 5 to 7.
A rotating shaft, and a spiral flight provided protruding from the outer peripheral surface of the rotating shaft,
A solid-liquid phase kneading zone can be constructed at an early stage of the plasticizing process through a tributary formation opening that forms a tributary in a partial section of the spiral flight from the central portion of the spiral flight toward the tip of the screw. In addition, a branch flow forming opening is formed so as to force a part of the solid bed (SB) in the screw groove or a part of the melt pool (MP) in the preceding screw groove into the solid-liquid phase kneading zone. The screw for injection molding characterized by comprising.
A plurality of the spiral flights are provided at least in a partial section in the axial direction of the rotating shaft,
A tributary formation opening that forms the tributary is provided in at least one of the plurality of flights, and a screw groove on the rear side and a preceding screw groove on the front side across the spiral flight. The injection molding screw according to claim 9, wherein the injection molding screw is a notch portion that communicates.
A tributary formation opening that forms the tributary is provided in a spiral flight between two adjacent screw grooves, and a tributary formation opening provided in the helical flight between these adjacent grooves is in the circumferential direction. The injection molding screw according to claim 10, wherein the injection molding screw is displaced.