JP2022101221A - Manufacturing method for resin pipe - Google Patents

Abstract

To enable the molding of resin pipes as targeted while using simple equipment.SOLUTION: The method for manufacturing a resin pipe 1 includes a first process in which molten resin is injected and gas is pumped into a portion corresponding to one end of a pipe body 2 inside a molding die 11, and a second process in which molten resin is injected from a portion corresponding to the side or base end of a branch pipe section 3 inside the molding die 11. The molten resin made to flow in the first process is merged with the molten resin made to flow in the second process to form a hollow section by gas pressure, and excess molten resin is allowed to flow to a waste cavity 15a to be solidified.SELECTED DRAWING: Figure 5

Description

The present invention relates to a method for manufacturing a resin pipe, which manufactures a pipe using a molten resin material.

Conventionally, resin pipes have been widely used, for example, as various piping members for automobiles, and include straight pipes and complicatedly curved pipes. As a method for manufacturing this type of resin pipe, for example, as disclosed in Patent Document 1, a molten resin material is injected into a molding mold having a floating core at one end, and then gas is injected. There is a method of pumping and moving the floating core to the discharge side to form the resin into a hollow shape and pressing it against the molding surface of the molding die to solidify the resin. In Patent Document 1, the resin pipe includes a branch pipe portion. This branch pipe portion is formed by machining and communicates with the inside of the resin pipe.

Further, Patent Document 2 has a slide mold in which a molten resin material is injected into a molding mold and then arranged in a cavity of the molding mold, and the slide mold is provided with a core portion. A method is disclosed in which a slide mold slides the core portion together with the core portion along the axial direction of the cavity to form a hollow resin and presses the resin against the molding surface of the molding mold to solidify the resin.

Japanese Patent No. 6067856 Japanese Unexamined Patent Publication No. 2002-178361

By the way, in Patent Document 1, a structure in which a floating core is provided and the floating core is moved in the mold by gas pressure is required, so that the structure is complicated. Further, in Patent Document 2, a slide type is provided and a core portion is provided in the slide type, and a structure is required in which the slide type slides together with the core portion along the axial direction of the cavity. It gets complicated. That is, when an attempt is made to mold a resin pipe by a molding apparatus as in Patent Documents 1 and 2, there is a problem that the structure of the apparatus becomes complicated.

Therefore, it is conceivable to omit the floating core of Patent Document 1 and the slide type and core portion of Patent Document 2, but in that case, control of the resin flow becomes a problem.

The present invention has been made in view of this point, and an object of the present invention is to enable molding of a resin pipe as intended while using a simple device.

In order to achieve the above object, the first disclosure presupposes a method for manufacturing a resin pipe in which a pipe main body and a branch pipe portion branching from an intermediate portion in the longitudinal direction of the pipe main body are integrally molded. Then, the molten resin is injected from the portion corresponding to one end of the pipe body toward the portion corresponding to the other end of the pipe body and the gas is pumped into the inside of the molding mold for molding the resin pipe. The first step of flowing the molten resin toward the portion corresponding to the other end of the pipe body inside the molding die, and the side surface of the branch pipe portion inside the molding die for molding the resin pipe. Alternatively, a second step of injecting a molten resin from a portion corresponding to the base end portion and causing the molten resin to flow toward a portion corresponding to the pipe body inside the molding die is provided, and the gas is flowed to the molding die. The molten resin flowed in the first step and the molten resin flowed in the second step are merged inside the molding mold while flowing into the portion corresponding to the branch pipe portion inside the mold. The hollow portion of the pipe body and the hollow portion of the branch pipe portion are formed by the pressure of the gas, and the molten resin is communicated with the portion corresponding to the other end of the pipe body inside the molding mold. The excess molten resin is solidified inside the waste cavity by flowing it to the waste cavity.

According to this configuration, the molten resin injected into the inside of the molding die in the first step flows from the portion corresponding to one end of the pipe body to the portion corresponding to the other end. Further, since the gas is pumped from the portion corresponding to one end of the pipe body, the gas also flows inside the molding die from the portion corresponding to one end of the pipe body to the portion corresponding to the other end. On the other hand, the molten resin injected into the portion corresponding to the side surface or the base end portion of the branch pipe portion inside the molding die in the second step flows toward the portion corresponding to the pipe body inside the molding die, and the second step is performed. It merges with the molten resin injected in one step. The gas pumped in the first step flows from the portion corresponding to one end of the pipe body to the portion corresponding to the other end inside the molding die, and the hollow portion of the pipe body and the hollow portion of the branch pipe portion are formed. It is formed. Further, the pressure of the gas causes the molten resin to flow to the disposal cavity of the molding die and solidify. As a result, it is possible to form a resin pipe as intended by the pressure of gas without providing a floating core, a ride type, a core portion, or the like.

In the second disclosure, after a predetermined time has elapsed from the start of injection of the molten resin in the second step, the injection of the molten resin in the first step is started, so that the melting injected into the molding mold in the second step is performed. After the resin is sufficiently flowed, it can be merged with the molten resin injected in the first step.

In the third disclosure, in the second step, the molten resin is injected into the portion corresponding to the rib at the base end portion of the branch pipe portion inside the molding die.

According to this configuration, the rib can be integrally formed with the branch pipe portion. In this case, since the rib protrudes from the branch pipe portion, after injecting a predetermined amount of molten resin in the second step, the molten resin existing in the vicinity of the rib begins to solidify at an early stage. As a result, the backflow of the molten resin due to the gas pressure is suppressed, and the molding accuracy of the resin pipe is improved.

The fourth disclosure presupposes a method for manufacturing a resin pipe in which a pipe body, a branch pipe portion branching from an intermediate portion in the longitudinal direction of the pipe body, and a flange portion protruding from the branch pipe portion are integrally molded. do. Then, the molten resin is injected from the portion corresponding to one end of the pipe body toward the portion corresponding to the other end of the pipe body and gas is pumped into the inside of the molding mold for molding the resin pipe. The first step of flowing the molten resin toward the portion corresponding to the other end of the pipe body inside the molding die, and the inside of the molding die for molding the resin pipe correspond to the flange portion. A second step of injecting a molten resin from a portion and causing the molten resin to flow toward a portion corresponding to the pipe body inside the molding die is provided, and the gas is supplied to the branch pipe portion inside the molding die. The molten resin flowed in the first step and the molten resin flowed in the second step are merged inside the molding mold while flowing into the portion corresponding to the above, and the pressure of the gas causes the molten resin to merge. The hollow portion of the pipe body and the hollow portion of the branch pipe are formed, and the molten resin is allowed to flow to the waste cavity that communicates with the portion corresponding to the other end of the pipe body inside the molding die. The molten resin is solidified inside the waste cavity.

According to this configuration, the molten resin injected into the inside of the molding die in the first step flows from the portion corresponding to one end of the pipe body to the portion corresponding to the other end. Further, since the gas is pumped from the portion corresponding to one end of the pipe body, the gas also flows inside the molding die from the portion corresponding to one end of the pipe body to the portion corresponding to the other end. On the other hand, the molten resin injected into the portion corresponding to the flange portion inside the molding die in the second step flows toward the portion corresponding to the pipe body inside the molding die, and is melted injected in the first step. Merge with resin. The gas pumped in the first step flows from the portion corresponding to one end of the pipe body to the portion corresponding to the other end inside the molding die, and the hollow portion of the pipe body and the hollow portion of the branch pipe portion are formed. It is formed. Further, the pressure of the gas causes the molten resin to flow to the disposal cavity of the molding die and solidify. As a result, it is possible to form a resin pipe as intended by the pressure of gas without providing a floating core, a ride type, a core portion, or the like.

In the fifth disclosure, after a predetermined time has elapsed from the start of injection of the molten resin in the second step, the injection of the molten resin in the first step is started, so that the melting injected into the molding mold in the second step is performed. After the resin is sufficiently flowed, it can be merged with the molten resin injected in the first step.

In the sixth disclosure, in the second step, the molten resin is injected into a portion of the inside of the molding die corresponding to the tip of the flange portion.

According to this configuration, since the flange portion protrudes from the branch pipe portion, after injecting a predetermined amount of molten resin in the second step, the molten resin existing near the tip of the flange portion solidifies at an early stage. start. As a result, the backflow of the molten resin due to the gas pressure is suppressed, and the molding accuracy of the resin pipe is improved.

The seventh disclosure presupposes a method for manufacturing a resin pipe in which a pipe main body and a branch pipe portion branching from an intermediate portion in the longitudinal direction of the pipe main body are integrally molded. Then, the molten resin is injected from the portion corresponding to one end of the pipe body toward the portion corresponding to the other end of the pipe body and the gas is pumped into the inside of the molding mold for molding the resin pipe. The first step of flowing the molten resin toward the portion corresponding to the other end of the pipe body inside the molding die, and the length of the branch pipe portion inside the molding die for molding the resin pipe. After opening the valve gate from the portion corresponding to the middle portion in the direction and injecting a predetermined amount of the molten resin, the molten resin is allowed to flow toward the portion corresponding to the pipe body inside the molding die, and the valve gate is blown. The molten resin flowed in the first step while flowing the gas toward the portion corresponding to the branch pipe portion inside the molding die, and the second step, which is provided with a second step of closing. The molten resin that has flowed is merged inside the mold, and the hollow portion of the pipe body and the hollow portion of the branch pipe portion are formed by the pressure of the gas, and the molten resin is placed inside the mold. The excess molten resin is solidified inside the waste cavity by flowing it to the waste cavity communicating with the portion corresponding to the other end of the pipe body.

According to this configuration, the molten resin injected into the inside of the molding die in the first step flows from the portion corresponding to one end of the pipe body to the portion corresponding to the other end. Further, since the gas is pumped from the portion corresponding to one end of the pipe body, the gas also flows inside the molding die from the portion corresponding to one end of the pipe body to the portion corresponding to the other end. On the other hand, in the second step, a predetermined amount of molten resin can be injected into the portion corresponding to the intermediate portion of the branch pipe portion inside the molding die by the opening / closing operation of the valve gate. The molten resin injected from the valve gate flows toward the portion corresponding to the pipe body inside the molding die and joins with the molten resin injected in the first step. The gas pumped in the first step flows from the portion corresponding to one end of the pipe body to the portion corresponding to the other end inside the molding die, and the hollow portion of the pipe body and the hollow portion of the branch pipe portion are formed. It is formed. Further, the pressure of the gas causes the molten resin to flow to the disposal cavity of the molding die and solidify. As a result, it is possible to form a resin pipe as intended by the pressure of gas without providing a floating core, a ride type, a core portion, or the like.

In the eighth disclosure, after a predetermined time has elapsed from the start of injection of the molten resin in the second step, the injection of the molten resin in the first step is started, so that the melting injected into the molding mold in the second step is performed. After the resin is sufficiently flowed, it can be merged with the molten resin injected in the first step.

The ninth disclosure is that in the second step, the valve pin of the valve gate is held in a state of being projected to the outside by a predetermined amount from the gate opening of the valve gate in a state where the valve gate is closed. The molten resin existing near the gate begins to solidify at an early stage. As a result, the backflow of the molten resin due to the gas pressure is suppressed, and the molding accuracy of the resin pipe is improved.

As described above, the molten resin flows to the waste cavity of the molding mold and solidifies due to the pressure of the gas when forming the hollow portion of the pipe body and the hollow portion of the branch pipe portion. You can mold the resin pipe you want.

It is a side view of the resin pipe which concerns on Embodiment 1 of this invention. It is sectional drawing of the part where the branch pipe part of the resin pipe which concerns on Embodiment 1 was formed. It is sectional drawing of the molding mold which concerns on Embodiment 1. FIG. It is a figure corresponding to FIG. 3 explaining the molding procedure of the resin pipe which concerns on Embodiment 1. FIG. FIG. 3 is a diagram corresponding to FIG. 3 for explaining the time when the molding of the resin pipe according to the first embodiment is completed. It is a side view of the resin pipe which concerns on Embodiment 2 of this invention. It is sectional drawing of the part where the branch pipe part of the resin pipe which concerns on Embodiment 2 was formed. FIG. 4 is a diagram corresponding to FIG. 4 according to the second embodiment. FIG. 5 is a diagram corresponding to FIG. 5 according to the second embodiment. It is a side view of the resin pipe which concerns on Embodiment 3 of this invention. It is a figure which enlarges and shows a part of the branch pipe part of the resin pipe which concerns on Embodiment 3. It is sectional drawing of the molding mold which concerns on Embodiment 3. FIG. It is a figure corresponding to FIG. 12 explaining the molding procedure of the resin pipe which concerns on Embodiment 3. FIG. 12 is a view corresponding to FIG. 12 for explaining the time when the molding of the resin pipe according to the third embodiment is completed. FIG. 3 is an enlarged cross-sectional view of the vicinity of the valve gate according to the third embodiment. FIG. 15 is a diagram corresponding to FIG. 15 according to the first modification of the third embodiment. FIG. 15 is a diagram corresponding to FIG. 15 according to the second modification of the third embodiment. FIG. 15 is a diagram corresponding to FIG. 15 according to the third modification of the third embodiment.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. It should be noted that the following description of the preferred embodiment is essentially merely an example and is not intended to limit the present invention, its application or its use.

(Embodiment 1)
FIG. 1 shows a resin pipe 1 according to the first embodiment of the present invention. The resin pipe 1 is formed by integrally molding a pipe main body 2 and a branch pipe portion 3 branching from the pipe main body 2. The thickness of the pipe body 2 and the thickness of the branch pipe portion 3 may be the same, or one of them may be thinner than the other. Examples of the material of the resin pipe 1 include polypropylene and the like, but the material is not limited to this, and any resin that can be formed in a molten state by gas pressure, which will be described later, can be used. Further, the resin used as the material of the resin pipe 1 may be mixed with a reinforcing material such as glass fiber. Further, the material of the resin pipe 1 may be a resin in which a plurality of types of resins are mixed.

The resin pipe 1 can be used, for example, as a piping member for an intake system of an automobile or a blow-by gas introduction system, or as a piping member for hot water, cooling water, etc., and can be used as a pipe for circulating various liquids as well as gas. be. One end side connecting pipe portion 2a is formed at one end of the pipe main body 2, and the other end side connecting pipe portion 2b is formed at the other end of the pipe main body 2. Different piping members are connected to the connection pipe portion 2a on the one end side and the connection pipe portion 2b on the other end side, respectively. The connection structure of the connection pipe portion 2a on the one end side and the connection pipe portion 2b on the other end side is not particularly limited, and may be a tightening structure using a band (not shown) or a fastening structure using a flange (not shown). And so on.

A first curved portion 2c, a second curved portion 2d, and a straight pipe portion 2e are provided between the one end side connecting pipe portion 2a and the other end side connecting pipe portion 2b of the pipe main body 2. The first curved portion 2c is provided in a portion of the pipe main body 2 near the one end side connecting pipe portion 2a. The second curved portion 2d is provided in a portion of the pipe body 2 near the connecting pipe portion 2b on the other end side. The straight pipe portion 2e is provided between the first curved portion 2c and the second curved portion 2d. Either one or both of the first curved portion 2c and the second curved portion 2d may be omitted, or a curved portion (third curved portion) other than the first curved portion 2c and the second curved portion 2d may be provided. good. Further, the straight pipe portion 2e may be omitted, or two or more straight pipe portions may be provided.

That is, the shape of the pipe body 2 is not limited to the above-mentioned shape, and may be a straight tubular shape, or may be composed of a large number of curved portions or straight pipe portions. The length of the straight pipe portion can be freely set such as the radius of curvature of the curved portion. Further, the length, outer diameter, and inner diameter of the pipe body 2 can be freely set. Further, the cross-sectional shape of the pipe body 2 can be, for example, a circular shape, an elliptical shape, an oval shape, or the like, and can be a free shape. Further, the length of the pipe main body 2 can be arbitrarily set, and can be, for example, a length of about several tens of centimeters to several meters.

The branch pipe portion 3 is located closer to the connecting pipe portion 2b on the other end side than the central portion in the length direction of the pipe main body 2, and protrudes radially from the pipe main body 2. As shown in FIG. 2, the inside of the branch pipe portion 3 and the inside of the pipe main body 2 communicate with each other. In this embodiment, the angle formed by the branch pipe portion 3 and the pipe main body 2 is substantially a right angle, but the present invention is not limited to this, and the angle may be less than 90 ° or more than 90 °. .. The outer diameter of the branch pipe portion 3 may be the same as or different from the outer diameter of the pipe main body 2. Further, the length of the branch pipe portion 3 is set to be significantly shorter than the length of the pipe main body 2, but conversely, it may be longer, and the length of the branch pipe portion 3 and the length of the pipe main body 2 are the same. May be. The formation position of the branch pipe portion 3 is not limited to the position shown in the figure, and can be freely set. The branch pipe portion 3 may have a straight pipe shape or a curved shape. In this embodiment, the middle portion of the branch pipe portion 3 is curved. Further, one or more branch pipe portions 3 may be provided for one pipe main body 2.

As shown in FIG. 2, the connection portion of the branch pipe portion 3 with the pipe main body 2 is formed so as to increase in diameter as it approaches the pipe main body 2. That is, the inner diameter of the connecting portion of the branch pipe portion 3 becomes larger as it approaches the pipe main body 2, so that the inner peripheral surface of the connecting portion of the branch pipe portion 3 is composed of a curved surface. The shape of the inner peripheral surface of the connecting portion of the branch pipe portion 3 is formed when the gas, which will be described later, flows in. Since the inner peripheral surface of the connecting portion of the branch pipe portion 3 is curved, the flow resistance of the fluid is reduced, which is preferable.

As shown in FIGS. 1 and 2, a plurality of ribs 4 are provided at the base end portion of the branch pipe portion 3. In this embodiment, four ribs 4 are provided at intervals in the circumferential direction of the branch pipe portion 3, but the number of ribs 4 is not limited to four, and even if the number of ribs 4 is three or less. It may be 5 or more. Each rib 4 projects radially outward from the outer peripheral surface of the branch pipe portion 3 and extends in the pipe axial direction of the branch pipe portion 3. The base end portion of each rib 4 is continuous with the outer peripheral surface of the pipe body 2. As a result, the connection portion between the base end portion of the branch pipe portion 3 and the pipe main body 2 can be reinforced by the rib 4, and bending or bending of the branch pipe portion 3 with respect to the pipe main body 2 can be suppressed. The thickness of the rib 4 may be about the same as the thickness of the branch pipe portion 3 or the thickness of the pipe body 2, may be thinner than the thickness of the branch pipe portion 3 or the thickness of the pipe body 2, or may be thinner than the thickness of the branch pipe portion 2. It may be thicker than the thickness of the portion 3 or the thickness of the pipe main body 2. The shape of the rib 4 may be a shape other than the rectangular shape.

(Structure of molding equipment)
Next, the molding apparatus 10 of the first embodiment will be described with reference to FIG. The molding apparatus 10 includes an injection machine (not shown) that injects the molten resin, a molding die 11, a gas supply machine (not shown), and a control device (not shown). The injection machine is provided with an injection cylinder for kneading and heating the resin to bring it into a molten state and injecting a certain amount of the molten resin at a predetermined speed. The gas supply machine is a device for pressure-feeding a high-pressure gas (for example, air or the like) that can flow in the molten resin. The injection machine and the gas supply machine are connected to the control device. The injection machine is controlled by a control device, and the injection start, injection end, flow rate at the time of injection, etc. of the molten resin are controlled. In addition, the gas supply machine is also controlled by the control device, and the start and end of gas pumping, the flow rate at the time of pumping, and the like are controlled.

The molding die 11 has, for example, a fixed mold and a movable mold, and a mold driving device for driving the movable mold in a direction in which the movable mold is brought into contact with and separated from the fixed mold. By driving the movable mold with the mold driving device, the molding mold 11 can be switched between the mold tightening state and the mold opening state. Inside the molding die 11, there are a molding surface 12 for molding the outer surface of the resin pipe 1, a first cavity 13, a second cavity 14, a first downstream cavity 15a, and a second downstream cavity 15b. , A nozzle 16 and a first runner 17 and a second runner 18 are provided. A space R for molding the resin pipe 1 is partitioned inside the molding die 11 by the molding surface 12. The space R is composed of a first space R1 forming the pipe main body 2 and a second space R2 forming the branch pipe portion 3, and the first space R1 and the second space R2 communicate with each other. .. When there are a plurality of branch pipe portions 3, a plurality of second space R2 may be provided according to the number of branch pipe portions 3.

The first cavity 13 communicates with a portion of the first space R1 corresponding to one end of the pipe body 2, and extends in the pipe axis direction of one end of the pipe body 2. The pipe body 2 is formed by the molten resin flowing into the first cavity 13. Further, the second cavity 14 communicates with a portion corresponding to one end portion (base end portion) of the branch pipe portion 3 in the second space R2, and extends in the pipe axis direction of the branch pipe portion 3. The branch pipe portion 3 is formed by the molten resin flowing into the second cavity 14.

The first downstream cavity 15a communicates with a portion of the first space R1 corresponding to the other end of the pipe body 2, and extends in the pipe axial direction of the other end of the pipe body 2. The first downstream cavity 15a is a discard cavity for receiving and discarding the molten resin flowing through the first space R1. The second downstream cavity 15b communicates with a portion corresponding to the tip end portion of the branch pipe portion 3 in the second space R2, and extends in the pipe axial direction of the other end portion of the branch pipe portion 3. The second downstream cavity 15b is a discard cavity for receiving and discarding the molten resin flowing through the second space R2. Both the first downstream side cavity 15a and the second downstream side cavity 15b are spaces into which the excess molten resin flows, and the molten resin is formed so that the molten resin flows into the first downstream side cavity 15a and the second downstream side cavity 15b. Supply amount is set. The shape and size of the first downstream cavity 15a and the second downstream cavity 15b can be arbitrarily set. The shape and size of the first downstream cavity 15a and the second downstream cavity 15b may be the same or different from each other.

An injection cylinder of an injection machine is connected to the nozzle 16, and the molten resin injected from the injection cylinder first flows into the nozzle 16. The position of the nozzle 16 is preferably between the first cavity 13 and the second cavity 14. The first runner 17 is a resin passage extending from the nozzle 16 to the upstream side of the first cavity 13. The second runner 18 is a resin passage extending from the nozzle 16 to the second cavity 14. The first runner 17 and the second runner 18 can be composed of a hot runner.

Specifically, the downstream end of the second runner 18 communicates with the portion of the second cavity 14 corresponding to the end of the rib 4. Since the rib 4 is located at the base end portion of the branch pipe portion 3, the molten resin can be injected by the second runner 18 into the portion corresponding to the base end portion of the branch pipe portion 3 in the second cavity 14. Further, since the rib 4 protrudes from the outer peripheral surface which is the side surface of the branch pipe portion 3, the molten resin is applied to the portion corresponding to the side surface of the branch pipe portion 3 in the second cavity 14 by the second runner 18. Can be ejected. A plurality of first runners 17 and second runners 18 may be provided.

The first runner 17 and the second runner 18 may be provided with an on-off valve and a throttle member. Thereby, the timing of supplying the molten resin to the first cavity 13 and the timing of supplying the molten resin to the second cavity 14 can be individually controlled. For example, the timing of supplying the molten resin to the first cavity 13 and the timing of supplying the molten resin to the second cavity 14 may be the same, or the timing of supplying the molten resin to the second cavity 14 may be set to the first cavity 13. The timing of supplying the molten resin may be later than the timing of supplying the molten resin, or the timing of supplying the molten resin to the second cavity 14 may be earlier than the timing of supplying the molten resin to the first cavity 13.

Further, the molding die 11 is provided with a gas supply pipe 19. The downstream end of the gas supply pipe 19 is connected to the upstream end of the first cavity 13. A gas supply machine is connected to the upstream end of the gas supply pipe 19.

(Manufacturing method of resin pipe)
Next, a manufacturing method for manufacturing the resin pipe 1 using the molding apparatus 10 of the first embodiment configured as described above will be described. First, the molding die 11 is closed. After that, as shown in FIGS. 4 and 5, the molten resin is injected from the injection cylinder of the injection machine. The injected molten resin flows into the nozzle 16 and then flows through the first runner 17 to reach the first cavity 13. The molten resin that has reached the first cavity 13 is ejected from a portion corresponding to one end of the pipe body 2 in the first space R1 inside the molding die 11. The amount of the resin to be injected is such that it exceeds the first curved portion 2c of the pipe main body 2 and reaches the straight pipe portion 2e. That is, it is an amount that the molten resin is filled at least between the line L1 and the line L2 in FIG. This is the first molten resin injection step, that is, the first step.

Further, the molten resin flowing into the nozzle 16 flows through the second runner 18 and reaches the second cavity 14. The molten resin that has reached the second cavity 14 is ejected from the portion corresponding to the side surface or the proximal end portion of the branch pipe portion 3 in the second space R2. The molten resin injected into the second space R2 flows through the second space R2 and is filled up to the vicinity of the line L3 on the upstream side of the pipe body 2 in the first space R1 and to the vicinity of the line L4 on the downstream side. To. The rib 4 is integrally molded with the branch pipe portion 3 by this resin. This is the second molten resin injection process. The above is the second step of the first embodiment.

The second step may be performed at the same timing as the molten resin injection of the first step, may be performed after the molten resin injection of the first step is completed, or may be performed before the molten resin injection of the first step is completed. You may go to. Further, the injection of the molten resin in the first step may be started after a predetermined time has elapsed from the start of the injection of the molten resin in the second step. For example, the first step may be started after the molten resin injected in the second step has flowed into the second cavity 14, or the molten resin injected in the second step may pass through the second cavity 14. , The first step may be started after flowing into the first cavity 13 from the second cavity 14. The timing for starting the first step can be obtained in advance by an experiment or the like.

Further, it is also possible to start the injection of the molten resin in the second step after a predetermined time has elapsed from the start of the injection of the molten resin in the first step. As a result, the molten resin injected into the molding die 11 in the first step is sufficiently flowed from the portion corresponding to one end of the pipe body 2 to the portion corresponding to the other end, and then the second. It can be merged with the molten resin injected in the process.

The amount of the molten resin injected in the first step may be an amount that reaches the portion corresponding to the straight pipe portion 2e of the pipe main body 2 in the first space R1. That is, the amount may reach the line L2 in FIG. 4, and the injection may be stopped after injecting this amount of molten resin. The position of the wire L2 can be changed depending on the length, diameter, or the like of the resin pipe 1.

After stopping the injection of the molten resin, gas is supplied from the gas supply machine. The supplied gas flows through the gas supply pipe 19 and flows into the first cavity 13, and then is pressure-fed to the portion corresponding to one end of the pipe body 2 in the first space R1. Of the molten resin filled in the first space R1, the portion in contact with the molding surface 12 has started to solidify, so that the gas forms a hollow portion in the vicinity of the radial center portion in the first space R1. It flows toward the portion corresponding to the other end of the pipe body 2. Due to such a gas flow, the molten resin flows toward the portion corresponding to the other end of the pipe body 2 in the first space R1 while forming a hollow portion. The above is the third step of the first embodiment.

The gas may be supplied in the first step. For example, after injecting the molten resin in the first step, the gas is pumped toward the portion corresponding to the other end of the pipe body 2, so that the first step is performed. The molten resin injected in the process can be flowed toward the portion corresponding to the other end of the pipe body 2. After that, the molten resin may be injected from the portion corresponding to the tip portion of the branch pipe portion 3. Also by this method, the molten resin injected through the first runner 17 and the molten resin injected through the second runner 18 can be merged.

The molten resin flowed in the first step and the molten resin flowed in the second step merge inside the molding die 11, that is, near the line L3 corresponding to the intermediate portion of the pipe body 2 in the first space R1. .. At this time, since the gas flows in the direction toward the other end side of the pipe body 2, the flow of the gas forms a continuous hollow portion (hollow portion of the pipe body 2) from the upstream side to the downstream side. .. The excess molten resin flows into the first downstream cavity 15a by the flow of gas and solidifies.

Further, the gas flowing to the vicinity of the second space R2 flows into the portion corresponding to the branch pipe portion 3 inside the molding die 11, that is, the hollow portion of the branch pipe portion 3 due to the flow into the second space R2. It is formed. This is because the molten resin in the second space R2 and the molten resin in the second cavity 14 contain air and the like, and the gas is compressed by the high-pressure gas so that the gas is in the second space. It flows into R2. The gas flowing into the second space R2 causes the molten resin to flow into the second downstream cavity 15b and solidify. After that, by solidifying all the molten resin in the molding die 11, it is possible to obtain a resin pipe 1 in which the branch pipe portion 3 is integrally molded with the pipe main body 2 without performing machining.

After opening the mold and removing the resin pipe 1, the resin pipe 1 is desired by cutting both ends of the pipe body 2 and the end of the branch pipe (indicated by wire L1, wire L4, and wire L5). Can be shaped.

(Action and effect of Embodiment 1)
As described above, according to the first embodiment, the molten resin is injected into the portion corresponding to one end of the pipe body 2 and the gas is pumped inside the molding die 11, and further, inside the molding die 11. Since the molten resin was injected into the portion corresponding to the branch pipe portion 3 to merge with the molten resin and the gas flowed into the portion corresponding to the branch pipe portion 3 inside the molding die 11, it was machined. The branch pipe portion 3 communicating with the pipe main body 2 can be integrally formed without the need for the above.

Further, due to the pressure of the gas, the molten resin flows to the first downstream side cavity 15a and the second downstream side cavity 15b, which are the discard cavities of the molding die 11, and solidifies. As a result, the resin pipe 1 having the desired shape can be formed by the pressure of the gas without providing a floating core, a ride type, a core portion, or the like.

Further, the rib 4 can be integrally molded with the branch pipe portion 3. In this case, since the rib 4 protrudes from the branch pipe portion 3, after injecting a predetermined amount of the molten resin in the second step, the molten resin existing in the vicinity of the rib 4 begins to solidify at an early stage. As a result, the backflow of the molten resin (flow toward the second runner 18) due to the gas pressure is suppressed, and the molding accuracy of the resin pipe 1 is improved.

(Embodiment 2)
6 and 7 show the resin pipe 1 according to the second embodiment of the present invention, and FIGS. 8 and 9 show the molding apparatus 10 according to the second embodiment of the present invention. The second embodiment is different from that of the first embodiment in that the resin pipe 1 is provided with the flange portion 5 and the resin pipe 1 provided with the flange portion 5 is a molding apparatus 1 capable of molding the resin pipe 1. Hereinafter, the same parts as those in the first embodiment are designated by the same reference numerals, the description thereof will be omitted, and the different parts will be described in detail.

A flange portion 5 is provided in the middle portion of the branch pipe portion 3 of the resin pipe 1 in the pipe axial direction. The flange portion 5 is a portion integrally molded with the branch pipe portion 3, and has a plate shape that protrudes in the radial direction from the outer peripheral surface of the branch pipe portion 3 and extends in the circumferential direction. The flange portion 5 is separated from the outer peripheral surface of the pipe body 2. The thickness of the flange portion 5 may be about the same as the thickness of the branch pipe portion 3 or the thickness of the pipe body 2, may be thinner than the thickness of the branch pipe portion 3 or the thickness of the pipe body 2, or may be branched. It may be thicker than the thickness of the pipe portion 3 or the thickness of the pipe body 2. The flange portion 5 of this embodiment is circular, but may be polygonal. The number of flange portions 5 may be 2 or more. In the second embodiment, the same ribs as in the first embodiment may be provided.

Next, the molding apparatus 10 of the second embodiment will be described with reference to FIGS. 8 and 9. In the molding apparatus 10 of the second embodiment, the downstream end of the second runner 18 communicates with the portion corresponding to the end portion of the flange portion 5 in the second cavity 14. Since the flange portion 5 is located on the side surface of the branch pipe portion 3, the molten resin is injected by the second runner 18 into the portion corresponding to the tip of the flange portion 5 (side surface of the branch pipe portion 3) in the second cavity 14. Can be done. The flange portion 5 may be provided at the base end portion of the branch pipe portion 3. In this case, the molten resin is injected by the second runner 18 into the portion corresponding to the base end portion of the branch pipe portion 3 in the second cavity 14. can do.

Next, a manufacturing method for manufacturing the resin pipe 1 using the molding apparatus 10 of the second embodiment configured as described above will be described. After the molding die 11 is closed, when the molten resin is injected from the injection cylinder of the injection machine as shown in FIG. 8, the molten resin is filled between the lines L1 and L2 in FIG. This is the first molten resin injection step, that is, the first step.

Further, the molten resin flowing into the nozzle 16 flows through the second runner 18 and reaches the second cavity 14, and then is ejected from the portion corresponding to the side surface or the proximal end portion of the branch pipe portion 3 in the second space R2. To. The molten resin injected into the second space R2 flows through the second space R2 and is filled up to the vicinity of the line L3 on the upstream side of the pipe body 2 in the first space R1 and to the vicinity of the line L4 on the downstream side. To. The flange portion 5 is integrally molded with the branch pipe portion 3 by this resin. This is the second molten resin injection process. The above is the second step of the first embodiment.

After stopping the injection of the molten resin, gas is supplied from the gas supply machine to perform the third step. The gas may be supplied in the first step. The molten resin flowed in the first step and the molten resin flowed in the second step merge near the line L3 of the first space R1. At this time, since the gas flows in the direction toward the other end side of the pipe body 2, the flow of the gas forms a continuous hollow portion (hollow portion of the pipe body 2) from the upstream side to the downstream side. .. The excess molten resin flows into the first downstream cavity 15a by the flow of gas and solidifies.

Further, the gas flowing to the vicinity of the second space R2 flows into the portion corresponding to the branch pipe portion 3 inside the molding die 11, that is, the hollow portion of the branch pipe portion 3 due to the flow into the second space R2. It is formed. The gas flowing into the second space R2 causes the molten resin to flow into the second downstream cavity 15b and solidify. After that, by solidifying all the molten resin in the molding die 11, it is possible to obtain a resin pipe 1 in which the branch pipe portion 3 is integrally molded with the pipe main body 2 without performing machining.

After opening the mold and removing the resin pipe 1, the resin pipe 1 is desired by cutting both ends of the pipe body 2 and the end of the branch pipe (indicated by wire L1, wire L4, and wire L5). Can be shaped.

(Action effect of embodiment 2)
As described above, according to the second embodiment, as in the first embodiment, the resin pipe 1 having the desired shape is formed by the pressure of the gas without providing a floating core, a ride type, a core portion, or the like. can.

Further, since the flange portion 5 protrudes from the branch pipe portion 3, after injecting a predetermined amount of molten resin in the second step, the molten resin existing in the vicinity of the tip of the flange portion 5 begins to solidify at an early stage. .. As a result, the backflow of the molten resin due to the gas pressure is suppressed, and the molding accuracy of the resin pipe 1 is improved. Since the gas can be prevented from flowing out from the tip of the flange portion 5 to the runner, the fluid inside does not leak to the outside.

(Embodiment 3)
10 and 11 show the resin pipe 1 according to the third embodiment of the present invention, and FIGS. 12 to 15 show the molding apparatus 10 according to the third embodiment of the present invention. In the third embodiment, the valve gate 30 is provided in the molding apparatus 10, and the gate mark 6 is formed on the side surface of the branch pipe portion 3 of the resin pipe 1 by the valve gate 30. Is different. Hereinafter, the same parts as those in the first embodiment are designated by the same reference numerals, the description thereof will be omitted, and the different parts will be described in detail.

A gate mark 6 is formed in the middle of the branch pipe portion 3 of the resin pipe 1 in the pipe axial direction. The gate mark 6 is formed by providing the valve gate 30 in the molding apparatus 10, and is a mark corresponding to the shape of the valve gate 30. In the third embodiment, the gate trace 6 is composed of a protruding portion protruding from the side surface of the branch pipe portion 3, and is located at a position away from the base end portion of the branch pipe portion 3. Specifically, as shown in FIG. 11, the gate trace 6 is composed of an annular protrusion 6a protruding in an annular shape and a plurality of radial protrusions 6b extending radially outward from the outer peripheral portion of the annular protrusion 6a. It is configured. The shape of the gate mark 6 is not limited to the shape shown in the figure, and may be any shape according to the shape of the tip portion of the valve gate 30.

Next, the molding apparatus 10 of the third embodiment will be described with reference to FIGS. 12 and 15. In the molding apparatus 10 of the third embodiment, the valve gate 30 is provided at the downstream end of the second runner 18, and the downstream end of the second runner 18 passes through the valve gate 30 and the branch pipe portion 3 in the second cavity 14 is provided. It communicates with the part corresponding to the side surface of.

As shown in FIG. 15, the valve gate 30 includes a hot runner 31, a valve body (valve pin) 32 provided inside the hot runner 31, and a drive device (not shown) for driving the valve body 32. ing. A resin discharge port (gate port) 31a is formed at the tip of the hot runner 31. A plurality of radial recesses 31b extending radially in the radial direction of the discharge port 31a are formed around the discharge port 31a at the tip of the hot runner 31.

The valve body 32 is configured to be able to move forward and backward by a drive device, and in the advanced state (moved downward in FIG. 15), the discharge port 31a of the hot runner 31 is closed, while the valve body 32 is retracted (FIG. 15). The discharge port 31a of the hot runner 31 is opened in the state of being moved upward). FIG. 15 shows a state in which the valve body 32 closes the discharge port 31a of the hot runner 31. Further, an annular recess 32a is formed on the outer peripheral surface of the tip end portion of the valve body 32. The positions and shapes of the annular recess 32a and the radial recess 31b are set so that the annular recess 32a and the radial recess 31b communicate with each other with the valve body 32 advanced. The annular recess 32a forms the annular protrusion 6a, and the radial recess 31b forms the radial protrusion 6b.

In the third embodiment, the same first step as in the first and second embodiments can be performed. On the other hand, in the second step, the valve body 32 of the valve gate 30 is retracted to open the valve gate 30, and a predetermined amount of molten resin is applied to the inside of the molding die 11 from the portion corresponding to the intermediate portion in the longitudinal direction of the branch pipe portion 3. Eject. After that, the valve body of the valve gate 30 is advanced, the valve gate 30 is closed, and the molten resin is allowed to flow toward the portion corresponding to the pipe body 2 inside the molding die 11. The opening / closing timing of the valve gate 30 is set so as to start the injection of the molten resin in the first step after a predetermined time has elapsed from the start of the injection of the molten resin in the second step.

(Action effect of embodiment 3)
As described above, according to the third embodiment, as in the first embodiment, the resin pipe 1 having the desired shape is formed by the pressure of the gas without providing a floating core, a ride type, a core portion, or the like. can.

Further, since the valve gate 30 is provided with the annular recess 32a and the radial recess 31b, the molten resin existing in the vicinity of the valve gate 30 can be solidified at an early stage. As a result, the backflow of the molten resin due to the gas pressure is suppressed, and the molding accuracy of the resin pipe 1 is improved. Since the gas can be prevented from flowing out from the tip of the gate 6 to the runner, the fluid inside does not leak to the outside.

(Modified Example of Embodiment 3)
FIG. 16 relates to the first modification of the third embodiment. In this modification 3, the tip end portion 32b of the valve body 32 in the closed position protrudes from the discharge port 31a of the hot runner 31. The end surface of the tip portion 32b is formed of a concave surface. As a result, the recess 6c is formed in the gate mark 6. That is, with the valve gate 30 closed, the tip portion 32b of the valve body 32 of the valve gate 30 can be held in a state of protruding outward by a predetermined amount from the discharge port 31a of the valve gate 30. , The molten resin existing in the vicinity of the valve gate 30 begins to solidify at an early stage. As a result, the backflow of the molten resin due to the gas pressure is suppressed, and the molding accuracy of the resin pipe 1 is improved. Since the gas can be prevented from flowing out from the tip of the gate 6 to the runner, the fluid inside does not leak to the outside.

FIG. 17 relates to the second modification of the third embodiment. In the second modification, the tip end 32b of the valve body 32 in the closed position protrudes from the discharge port 31a of the hot runner 31 as in the first modification. The end surface of the tip portion 32b of the modification 2 is composed of a convex surface.

FIG. 18 relates to a modification 3 of the third embodiment. In this modification 3, the tip end portion 32b of the valve body 32 in the closed position is located in the discharge port 31a of the hot runner 31. The end surface of the tip portion 32b of the modification 3 is composed of a convex surface.

The above embodiments are merely exemplary in all respects and should not be construed in a limited way. Further, all modifications and modifications belonging to the equivalent scope of the claims are within the scope of the present invention.

As described above, the method for manufacturing a resin pipe according to the present invention can be used, for example, when manufacturing piping parts for automobiles and the like.

1 Resin pipe 2 Pipe body 3 Branch pipe part 4 Rib 5 Flange part 11 Molding mold 15a 1st downstream side cavity (discarded cavity)
15b 2nd downstream cavity (discarded cavity)
30 Valve gate 31 Hot runner 31a Discharge port (gate port)
32 Valve body (valve pin)

Claims (9)

In the method for manufacturing a resin pipe (1) in which a pipe body (2) and a branch pipe portion (3) branching from an intermediate portion in the longitudinal direction of the pipe body (2) are integrally molded.
Inside the molding die (11) for molding the resin pipe (1), from the portion corresponding to one end of the pipe body (2) toward the portion corresponding to the other end of the pipe body (2). The first step of injecting the molten resin and pumping the gas to cause the molten resin to flow toward the portion corresponding to the other end of the pipe body (2) inside the molding die (11).
The molten resin is injected into the molding die (11) for molding the resin pipe (1) from the portion corresponding to the side surface or the base end portion of the branch pipe portion (3), and the molten resin is used in the molding die. (11) is provided with a second step of flowing toward the portion corresponding to the pipe body (2) inside.
The molten resin flowed in the first step and the molten resin flowed in the second step while flowing the gas toward the portion corresponding to the branch pipe portion (3) inside the molding die (11). The molten resin is merged inside the molding die (11) to form a hollow portion of the pipe body (2) and a hollow portion of the branch pipe portion (3) by the pressure of the gas, and the molten resin is formed. Inside the molding die (11), excess molten resin is allowed to flow inside the waste cavity (15a) by flowing it to the waste cavity (15a) communicating with the portion corresponding to the other end of the pipe body (2). A method for manufacturing a resin pipe, which is characterized by being solidified. In the method for manufacturing a resin pipe according to claim 1,
A method for manufacturing a resin pipe, characterized in that injection of the molten resin in the first step is started after a predetermined time has elapsed from the start of injection of the molten resin in the second step. In the method for manufacturing a resin pipe according to claim 1 or 2.
In the second step, a resin pipe is characterized in that a molten resin is injected into a portion corresponding to a rib (4) at a base end portion of the branch pipe portion (3) inside the molding die (11). Manufacturing method. The pipe body (2), the branch pipe portion (3) branching from the longitudinal intermediate portion of the pipe body (2), and the flange portion (5) protruding from the branch pipe portion (3) are integrally molded. In the manufacturing method of the resin pipe (1)
Inside the molding die (11) for molding the resin pipe (1), from the portion corresponding to one end of the pipe body (2) toward the portion corresponding to the other end of the pipe body (2). The first step of injecting the molten resin and pumping the gas to cause the molten resin to flow toward the portion corresponding to the other end of the pipe body (2) inside the molding die (11).
The molten resin is injected into the molding die (11) for molding the resin pipe (1) from the portion corresponding to the flange portion (5), and the molten resin is injected into the molding die (11) inside the molding die (11). It is equipped with a second step of flowing toward the part corresponding to the pipe body (2).
While flowing the gas toward the portion corresponding to the branch pipe portion (3) inside the molding die (11), the molten resin flowed in the first step and the molten resin flowed in the second step. The molten resin is merged inside the molding die (11) to form a hollow portion of the pipe body (2) and a hollow portion of the branch pipe portion (3) by the pressure of the gas, and the molten resin is formed. Inside the molding die (11), excess molten resin is allowed to flow inside the waste cavity (15a) by flowing it to the waste cavity (15a) communicating with the portion corresponding to the other end of the pipe body (2). A method for manufacturing a resin pipe, which is characterized by being solidified. In the method for manufacturing a resin pipe according to claim 4.
A method for manufacturing a resin pipe, characterized in that injection of the molten resin in the first step is started after a predetermined time has elapsed from the start of injection of the molten resin in the second step. In the method for manufacturing a resin pipe according to claim 4 or 5.
The second step is a method for manufacturing a resin pipe, which comprises injecting a molten resin into a portion of the molding die (11) corresponding to the tip of the flange portion (5). In the method for manufacturing a resin pipe (1) in which a pipe body (2) and a branch pipe portion (3) branching from an intermediate portion in the longitudinal direction of the pipe body (2) are integrally molded.
Inside the molding die (11) for molding the resin pipe (1), from the portion corresponding to one end of the pipe body (2) toward the portion corresponding to the other end of the pipe body (2). The first step of injecting the molten resin and pumping the gas to cause the molten resin to flow toward the portion corresponding to the other end of the pipe body (2) inside the molding die (11).
A valve gate (30) is opened from a portion corresponding to the intermediate portion in the longitudinal direction of the branch pipe portion (3) inside the molding die (11) for molding the resin pipe (1), and a predetermined amount of molten resin is injected. After that, the molten resin is allowed to flow toward the portion corresponding to the pipe body (2) inside the molding die (11), and is provided with a second step of closing the valve gate (30).
The molten resin flowed in the first step and the molten resin flowed in the second step while flowing the gas toward the portion corresponding to the branch pipe portion (3) inside the molding die (11). The molten resin is merged inside the molding die (11) to form a hollow portion of the pipe body (2) and a hollow portion of the branch pipe portion (3) by the pressure of the gas, and the molten resin is formed. Inside the molding die (11), excess molten resin is allowed to flow inside the waste cavity (15a) by flowing it to the waste cavity (15a) communicating with the portion corresponding to the other end of the pipe body (2). A method for manufacturing a resin pipe, which is characterized by being solidified. In the method for manufacturing a resin pipe according to claim 7.
A method for manufacturing a resin pipe, characterized in that injection of the molten resin in the first step is started after a predetermined time has elapsed from the start of injection of the molten resin in the second step. In the method for manufacturing a resin pipe according to claim 7 or 8.
In the second step, the valve pin (32) of the valve gate (30) is projected outward by a predetermined amount from the gate port (31a) of the valve gate (30) with the valve gate (30) closed. A method for manufacturing a resin pipe, which is characterized in that it is held in a state of being kept.

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