JP2858180B2 - Multi-layer molding resin injection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel resin injection apparatus for producing very precise skin-core type molded articles or marble-shaped molded articles which alternately or simultaneously inject two kinds of resin materials. About.

[0002]

2. Description of the Related Art As shown in FIGS. 5 to 7, a conventional resin injection device (X) is provided with a nozzle head (42) for pressing and separating from a sprue bush (41) provided on a mold (40). A nozzle inner hole (44) communicating with the nozzle hole (43) of the nozzle head (42) is provided, and a plunger (46) having a plunger resin passage (45) is inserted into the nozzle inner hole (44). The rear end of the plunger (46) is fixed to the piston (48) of the plunger operating hydraulic cylinder (47) fixed to the nozzle head (42), and the positioning hydraulic cylinder (4
9), the tip of the piston rod (50) of the positioning hydraulic cylinder (49) is projected into the plunger operating hydraulic cylinder (47), and the operation of the positioning hydraulic cylinder (49) causes the plunger (46) to move. When the plunger (46) reaches the forward limit, the second resin passage (51) provided in the nozzle head (42) and the nozzle hole (43) can be prevented.
And the first resin passage (52) provided in the nozzle head (42) at the same time by closing the tip taper of the plunger (46) closely to the tip taper of the nozzle head inner hole (44).
And the resin passage (45) in the plunger of the plunger (46) so that the first resin can be injected.
When injecting the second resin (see FIG. 6) (see FIG. 6), the plunger (46) is retracted to the retreat limit, so that the second resin passage (51) and the nozzle hole (43) are connected. Are communicated, and on the other hand, the first resin passage (52) and the resin passage (45) in the plunger are shut off.

When the first and second resins are simultaneously injected (see FIG. 7), the plunger (46) is prevented from retreating by the operation of the positioning hydraulic cylinder (49), and the first resin passage (52). A space is formed in the outer periphery of the plunger (46) for communicating the resin passage (45) in the plunger with the first resin passage (52) and the second resin passage (51) in the nozzle hole (43). It communicates at the same time.

In this case, as shown in FIG. 5, when the first resin is to be injected, the plunger (46) is advanced and the first resin passage (52) is inserted into the nozzle bore (44) of the nozzle head (42). ) And connect the tip of the plunger (46) with the nozzle head.
The first resin is injected by contacting the inner periphery of the tip of (42) to block the second resin passage (51).

Conversely, when trying to inject the second resin,
As shown in FIG. 6, the plunger (46) is retracted to block the first resin passage (52) of the nozzle head (42) and the resin passage (45) in the plunger of the plunger (46), and the nozzle head
The second resin passage (51) of (42) communicates with the nozzle hole (43). As a result, the second resin is injected and filled into the mold (40). At this time, the ball (5) at the front end of the plunger (46) is
4) is pressed by the first resin to close the tip of the plunger (46) so that the second resin does not leak from the plunger (46).

FIG. 7 shows a case in which two resins are simultaneously injected. In this case, the positioning hydraulic cylinder (49) is operated to advance the cylinder rod (50), and the rear end of the plunger (46) is moved to the cylinder rod (50). To stop at the intermediate position, to communicate the second resin passageway (51) of the nozzle head (42) with the resin passageway (45) in the plunger of the plunger (46), and the first of the nozzle head (42). The resin passage (52) communicates with the nozzle inner hole (44). As a result, the first resin extruded from the first heating cylinder (Z) becomes a skin, and the second resin extruded from the second heating cylinder (Y) becomes a core and is simultaneously filled in the mold (40).

The problem in this case is that the plunger (4
6) simply acts as a valve to switch the filling resin depending on its position, so after filling, the plunger (46) cannot be moved, and the pressure after injection is maintained by the mold (40 ), Which is very far from the first and second heating cylinders (X) and (Y), the holding pressure effect tends to be insufficient, and as a result, "shrinkage" occurs on the surface of the molded product. However, there is a drawback that the precision of a molded product cannot be improved even if the mold precision is improved.

Further, as described above, the switching of the resin is performed by using a mold.
When the first resin (J1) and the second resin (J2) are separately injected, the first resin (J1) and the second resin (J2) are used in the first and second resin passages (51) and (52) far from the (40). There is a problem that the second resin (J2) is mixed with the resin (J1).

[0009]

The first problem to be solved by the present invention is the case where the first resin and the second resin are injected in the order of injection and the case where the first and second resins are simultaneously injected. In addition, by applying a holding pressure directly to the resin injected into the mold very close to the mold, it cools while giving sufficient pressure to the molded product, there is no occurrence of `` shrinkage '' on the surface, The second is to make it possible to inject a molded product with extremely good transferability to the mold shape, and secondly to make the resin switching performance excellent by switching the resin very close to the mold. It is.

[0010]

SUMMARY OF THE INVENTION A resin injection device for a multilayer molded article according to the present invention has been made in view of the problems of the above-mentioned prior art. In the example in which the second resin seal portion (13) is provided at the tip of the inner cylinder (2), an outer cylinder nozzle hole (5) connected to the mold (4) is formed at the tip. An outer cylinder body (1) and an inner cylinder nozzle hole (9) are drilled at the tip corresponding to the outer cylinder nozzle hole (5), and are slidable in the axial direction of the outer cylinder body (1). An inner cylinder body housed in the outer cylinder body (1) so as to form a first resin passageway (6) with its outer periphery and the inner periphery of the outer cylinder body (1)
(2) and the inner cylinder (2) so as to be slidable in the axial direction of the inner cylinder (2).
And a needle (3) that forms a second resin passageway (12) with its outer periphery and the inner periphery of the inner cylindrical body (2). In (B), when the inner cylinder (2) moves forward, the outer periphery (2a) of the front end of the inner cylinder (2)
The first resin passageway (6) which is in contact with and communicates with the outer cylinder nozzle hole (5)
When the inner cylinder (2) retreats, the outer periphery of the front end of the inner cylinder (2) is separated, and the first resin that communicates the first resin passageway (6) to the outer cylinder nozzle hole (5). The seal part (7) is the inner peripheral front end of the outer cylinder (1).
(1a), is formed in a straight shape near the inner cylinder nozzle hole (9) of the inner cylinder (2), and when the needle (3) advances, the needle is formed.
After the front end (30) of (3) is inserted to close the second resin passageway (12), it is further inserted to serve as a pressure-holding allowance, and the needle (3)
Is retracted, the second resin seal portion (13) that escapes from the straight portion and opens the second resin passageway (12) has an inner cylindrical body.
It is characterized in that it is formed on the inner periphery of the front end of (2). As a result, the resin injected into the mold (4) very close to the mold
(J1) (J2) can be directly applied with holding pressure, it can be cooled while giving sufficient pressure to the molded product, and there is no "shrinkage" on the surface, and it is transferred to the mold shape It is now possible to inject molded products with extremely good properties. In addition, since the resin is switched very close to the mold, the resin switching performance is excellent.

A resin injection device for a multilayer molded article according to a second aspect of the present invention provides a resin injection device for a multi-layer molded article, in which the outer cylinder body is provided with a pressure-holding function. An outer cylinder body (1) having a hole (5) formed at the tip thereof, and an inner cylinder nozzle hole (9) formed at the tip corresponding to the outer cylinder nozzle hole (5). It is housed in the outer cylinder (1) so as to be slidable in the axial direction of the cylinder (1), and a first resin passage (6) is formed by the outer periphery and the inner periphery of the outer cylinder (1). Inner cylinder
(2) and the inner cylinder (2) so as to be slidable in the axial direction of the inner cylinder (2).
And a needle (3) that forms a second resin passageway (12) with its outer periphery and the inner periphery of the inner cylindrical body (2). B), it is formed in a straight shape close to the outer cylinder nozzle hole (5) of the outer cylinder (1), and when the inner cylinder (2) advances, the front end (2a ) Is inserted to close the first resin passage (6),
After injecting the second resin (J2) into the mold (4) by the needle (3), the tip of the inner cylindrical body (2) is further inserted into the straight portion to serve as a pressure-holding allowance for the mold filling resin. When the inner cylinder body (2) retreats, it comes out of the straight portion and passes through the first resin passage.
A first resin seal (7) for opening (6) is formed on the inner circumference (1a) of the front end of the outer cylinder (1), and when the needle (3) advances, the front end (30) of the needle (3) is When the outer periphery contacts and closes the second resin passageway (12) communicating with the inner cylinder nozzle hole (9), and the needle (3) retreats, the needle (3)
A second resin seal portion (13) communicating the second resin passageway (12) to the inner cylinder nozzle hole (9) with the outer periphery of the front end portion of the
It is characterized in that it is formed at the inner peripheral front end of (2). Thereby, the same effect as the first aspect can be obtained.

A third aspect of the present invention relates to a drive mechanism of a resin injection device for a multilayer molded article, and in the resin injection apparatus (B) for a multilayer molded article having a triple structure according to the first or second aspect, the inner cylinder body ( (2) Drive cylinder for inner cylinder (B
1) and a needle drive cylinder (B2) that moves together with the inner cylinder (2) and moves the needle (3) forward and backward.

According to a fourth aspect of the present invention, a drive mechanism is incorporated in the resin injection device.
An inner cylinder drive cylinder (B1) is provided with an outer cylinder body (8) formed on the rear inner circumference of the outer cylinder (1) and an inner cylinder piston formed on the rear outer circumference of the inner cylinder (2). (10), the needle driving cylinder (B2) is formed on the inner circumference of the inner cylinder rear part of the inner cylinder body (2) and the needle (3) formed on the outer circumference of the rear part of the needle (3). It is characterized by comprising the piston part (14). As a result, the resin injection device (B) can be made compact.

[0014]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 1 is a plan view of a multilayer resin injection molding machine (A) according to the present invention, in which a resin injection device (B) is installed at the center,
A first heating cylinder (C) and a second heating cylinder (D) are installed in parallel on both sides thereof, and a first and a second connection provided at the tip of the first and second heating cylinders (C) and (D). The tubes (28) and (29) are connected to the resin injection device (B). The structure of the first and second heating cylinders (C) and (D) is a known structure, and the resin pellets supplied from the first and second hoppers (15) and (16) are rotated by internal rotating screws (17) and (18). It is heated and kneaded and gradually extruded forward.

FIG. 2 is a front view of a multilayer resin injection molding machine (A) according to the present invention. The resin injection device (B) is fixed on a support (19), and the support (19) is a guide. It is slidably supported by the rail (20). The support base (19) is connected to the main drive cylinder (22) via the center shaft (21), and the main drive cylinder (22) controls the entire resin injection device (B) and both heating cylinders (C) and (D). Moves back and forth, and the tip of the outer cylinder (1) of the resin injection device (B) comes into contact with and separates from the sprue bush (23) of the mold (4). (24) is a fixed fulcrum for fixing the rear part of the main drive cylinder.

The first and second heating cylinders (C) and (D) slide together with the resin injection device (B) along side shafts (25) arranged in parallel on both sides of the center shaft (21). It has become. (2
6) The first and second heating cylinders (C) connected to the first and second heating cylinders (C) and (D)
(D) is a slider provided in the body part (C1) (D1),
(27) is a support side stand that supports the side shaft (25).
(15) and (16) are hoppers for supplying raw material pellets,
It is provided in the main body part (C1) (D1) connected to the first and second heating cylinders (C) and (D), respectively. (C2) (D2) is a screw for kneading (17)
This is a motor for rotating (18).

FIG. 3 shows a resin injection device with a built-in cylinder unit.
It is a schematic sectional drawing of (B). Main structure is outer cylinder (1), inner cylinder
(2) and the needle (3), the drive cylinder (B1) for the inner cylinder for moving the inner cylinder (2) forward and backward, and the needle for moving the needle (3) forward and backward with the inner cylinder (2) Drive cylinder
(B2), a position detection device (40a) for detecting the position of the needle (3), a position detection device (40b) for detecting the position of the inner cylinder (2), a CPU (41), for the inner cylinder It is composed of an inner cylinder proportional valve (42) for controlling the drive cylinder (B1), and a needle proportional valve (43) for controlling the needle drive cylinder (B2). It goes without saying that the proportional valves (42) and (43) may be servo valves.

The first half of the outer cylinder (1) is a kneaded first resin (J).
This is a first resin filling injection section for filling 1), and the latter half is an operating section, which is an outer cylinder section (8).
The first resin passageway (6), which is the first resin-filled injection section, includes an inner periphery of the outer cylinder (1) and an outer periphery of the inner cylinder (2).
Further, an outer cylinder nozzle hole (5) connected to the mold (4) is formed at the tip of the outer cylinder (1), and the inner cylinder ( 2) The front end outer peripheral surface is in contact with the first
A first resin seal portion (7) for closing the resin passage (6) is formed. The first connection cylinder (28) connected to the outer cylinder (1)
The distal end portion of the first heating cylinder (C) is connected so as to communicate with the first resin passage (6).

The first half of the inner cylinder (2) is made of a kneaded second resin.
(J2) is a second resin filling injection unit for filling, the latter half is an operating part, the inner periphery of which is an inner cylinder part (11)
The outer circumference is an outer cylinder piston section (10), which is slidably disposed in the outer cylinder section (11). The second resin passage, which is the second resin-filled injection section
(12) is composed of the inner circumference of the inner cylinder (2) and the outer circumference of the needle (3). Furthermore, an outer cylinder nozzle hole is provided at the tip of the inner cylinder (2).
An inner cylinder nozzle hole (9) is formed in correspondence with (5), and the front end outer peripheral surface of the advanced needle (3) is in contact with the inner peripheral surface of the distal end portion, and the second resin passage (12) ) Is formed with a second resin seal portion (13). The second connection cylinder (29) connected to the outer cylinder (1) is connected so that the distal end of the second heating cylinder (D) communicates with the second resin passage (12).

The first half of the needle (3) is a small-diameter resin-filled injection section, the second half is an operating section, and serves as an inner cylinder piston section (14). Tube cylinder (1
It is slidably housed in 1). The tip of the first half of the needle (3) is
The mold is inserted into a second resin seal portion (13) formed on the inner periphery of the tip of (2) to close the second resin passage (12), and
(4) It is possible to apply pressure to the resin inside. That is, as shown in FIG. 4, the entrance portion of the second resin seal portion (13) and the tip insertion portion (30) of the needle (3) are advanced from the state where they are opened by the interval (a), and they match. At the point, the second resin seal portion (13) is closed, and further advanced by (b), it is possible to apply strong pressure at a position close to the resin in the mold (4) only by the insertion margin (b) It is.

The position detecting device (40a) is mounted on the rear end exposed portion of the needle (3) and moves with the needle (3), and is used for detecting the position of the needle (3). , A potentiometer or an encoder is used. Similarly, the position detecting device (40b) is attached to the rear end exposed portion of the inner cylinder (2), moves together with the inner cylinder (2), and is used for detecting the position of the inner cylinder (2).

The CPU (41) receives a signal from the position detecting devices (40a) (40b) and controls the proportional valve (42) for controlling the inner cylinder cylinder (B1) and the needle cylinder (B2). (43) or feedback control of the servo valve

Thus, the resin pellets of the first and second resins (J1) and (J2) are put into the first and second hoppers (15) and (16), and the motor (C2)
(D2) is operated to rotate the kneading screws (17) and (18), and the resin pellets are heated by the heaters (H1) and (H2) wound around the outer circumference of the first and second heating cylinders (C) and (D). (J1) and (J2) are kneaded while being heated and melted, and are sequentially sent forward.

The first and second resins (J1) and (J2) sufficiently kneaded in the first and second heating cylinders (C) and (D) pass through the first and second connection cylinders (28) and (29), respectively. The first and second resin passages (6) and (12) of the injection device (B) are fed respectively.

Here, the first resin (J1), followed by the second resin
The case where the first resin (J1) is used as a skin layer and the second resin (J2) is used as an inner main body layer by injection in the order of (J2) will be described. First,
When the first resin (J1) is to be injected, the inner cylinder piston (14) is operated to advance the needle (3), and the second resin seal ( 13) is closed by the tip of the needle (3) so that the second resin (J2) does not leak from the inner cylinder nozzle hole (9) at the tip of the inner cylinder (2). On the other hand, the inner cylindrical body (2) is retracted, and the first resin seal portion (7) is open. When the screw (17) of the first heating cylinder (C) is operated in this state, the first resin (J1) gradually kneaded accumulates at the tip portion, and the screw (17) retreats accordingly. . When a predetermined amount of the first resin (J1) accumulates, the screw (17) moves forward and pushes out the kneaded first resin (J1) stored at the tip. The extruded kneaded first resin (J1) passes through the first connecting cylinder (28) and is
The resin enters the resin passageway (6), passes through the opened first resin seal portion (7), and is injected into the mold (4) from the outer cylinder nozzle hole (5) at the tip of the outer cylinder (1). You.

Subsequently, the second resin (J2) is injected into the mold (4). After the injection of the first resin (J1), the inner cylinder (2) is advanced and the outer cylinder (1) is moved. The first resin passage (6) is closed by contacting the first resin seal portion (7) of the first resin passage (6) so that the first resin (J1) does not leak from the first resin passage (6). needle
Move (3) to the rear and insert the tip (30) of the needle (3).
A gap (a) is provided between and the second resin seal portion (13). When the screw (18) of the second heating cylinder (D) is operated in this state, the kneaded second resin (J2) gradually accumulates at the tip portion, and the screw (18) retreats accordingly. . When a predetermined amount of the second resin (J2) accumulates, the screw (18) moves forward and pushes out the kneaded second resin (J2) stored at the tip. The extruded kneaded second resin (J2) enters the second resin passageway (12) through the second connecting cylinder (29), and the second resin (J2) is opened.
Inner cylinder nozzle hole of inner cylinder (2) through resin seal (13)
(9), mold (4) through the outer cylinder nozzle hole (5) at the tip of the outer cylinder (1)
It is injected inside.

As described above, when the first and second resins (J1) and (J2) are injected into the mold (4), the process shifts to the pressure-holding step. And apply pressure to the resin in the mold (4). As a result, a molded article having a shape extremely faithful to the cavity shape of the mold (4) is obtained. When the pressure-holding step is completed and the product in the mold (4) solidifies, the mold is opened to take out the product from the mold (4) and prepare for the next injection work. As a result, a skin-core molded product having the second resin (J2) in the center portion and the outer periphery of the second resin (J1) surrounded by the resin is completed, but sufficient holding pressure is applied near the mold (4). As a result, the density of the molded article becomes sufficiently high, and the molded article hardly shrinks during cooling and does not substantially shrink after being taken out, so that a molded article that is extremely faithful to the cavity shape can be obtained.

Alternatively, the inner cylinder driving cylinder (B1) and the needle driving cylinder (B2) are simultaneously operated to activate the inner cylinder body.
(2) and the needle (3) are advanced to close the first and second resin seal portions (7) and (13), and in this state, the first and second heating cylinders (C) are closed.
By operating the screw (17) of (D), the first and second resins (J1) and (J2) are pushed into the first and second resin passages (6) and (12) to apply pressure. Subsequently, the inner cylinder body (2) is retracted by operating the inner cylinder drive cylinder (B1), the first resin seal portion (7) is opened, and the first resin (J1) is rapidly moved to the mold (4). Inject with. The injection amount is feedback-controlled by the CPU (41) while detecting the position of the inner cylinder (2) by the position detection device (40b). At the same time when the injection of the first resin (J1) is completed, the first resin seal portion
(7) is closed, high-speed injection of the second resin (J2) is performed by the same operation, and while detecting the position of the tip (30) of the needle (3) by the position detection device (40a), the CPU ( It is also possible to take the method of performing feedback control according to 41).

When simultaneously injecting the first and second resins (J1) and (J2), the first and second heating cylinders (C) and (D) are operated to operate the first and second resin passages (6) and (12). ) Are supplied with the first and second resins (J1) and (J2), respectively. In this case, the inner cylinder body (2) and the needle (3) are both retracted, the first and second resin seal portions (7) and (13) are open, and the first and second heating cylinders (C ) (D) operates simultaneously and the first and second resin
The procedure is the same as above except that (J1) and (J2) are simultaneously injected. (Of course, high-speed injection by feedback control can be performed as described above.)

In this way, the first and second resins (J1) and (J2) are simultaneously injected into the mold (4).
The resin seal portions (7) and (13) are closed, and the process proceeds to the pressure-holding step as described above. When the process shifts to the pressure holding process, the needle
(3) further advances by (b) to apply a strong pressure to the mold filling resin to hold the pressure, thereby forming a molded product that is extremely faithful to the cavity shape of the mold (4). When the pressure-holding step is completed and the product in the mold (4) solidifies, the mold is opened to take out the product from the mold (4) and prepare for the next injection work. The pattern of the product formed in this manner has a marble tone in which the first and second resins (J1) and (J2) are mixed together. Also in this case, since the sufficient holding pressure is applied near the mold (4), the molded product hardly shrinks due to cooling, and the molded product after being taken out has a shape that is extremely faithful to the cavity shape.

[0031]

[Effect] The present invention has the above-described structure, and therefore, when the first resin and the second resin are sequentially injected and when the first and second resins are simultaneously filled, the resin is placed in the immediate vicinity of the mold. Pressure can be applied to the mold, so it is possible to obtain an excellent pressure-holding effect that has never been seen before, and to obtain a molded product that is extremely faithful to the mold cavity shape. Since the resin passage can be cut off at the tip of the device, the resin can be switched easily and accurately.

Further, by incorporating a drive cylinder, the resin injection device can be formed as a composite.

[Brief description of the drawings]

FIG. 1 is a plan view of a multilayer resin injection molding machine according to the present invention.

FIG. 2 is a front view of the multilayer resin injection molding machine according to the present invention.

FIG. 3 is a schematic sectional view of the resin injection device of the present invention.

FIG. 4 is a cross-sectional view showing an operation state of a tip portion of the resin injection device of the present invention.

FIG. 5 is a cross-sectional view showing an operation state when a first resin is injected in a conventional example.

FIG. 6 is a cross-sectional view showing an operation state when a second resin is injected in a conventional example.

FIG. 7 is a cross-sectional view showing an operation state at the time of simultaneous injection of first and second resins in a conventional example.

[Explanation of symbols]

 (1) ... outer cylinder (2) ... inner cylinder (3) ... needle (4) ... mold (5) ... outer cylinder nozzle hole (6) ... first resin passage (7) ... first resin seal Part (8) ... outer cylinder cylinder part (9) ... inner cylinder nozzle hole (10) ... piston part for outer cylinder (11) ... inner cylinder cylinder part (12) ... second resin passage (13) ... second resin Seal part (14)… Piston part for inner cylinder (30)… Tip insertion part

Continuation of the front page (56) References JP-A-4-84654 (JP, A) JP-A-61-268421 (JP, A) JP-A-59-201834 (JP, A) JP-A-4-294114 (JP, A) JP-A-2-169219 (JP, A) JP-A-4-169215 (JP, A) JP-A-58-179632 (JP, A) JP-A-3-272821 (JP, A) JP-A-5-104578 (JP, A) JP-A-4-113918 (JP, U) JP-A-2-10916 (JP, U) JP-A-2-58920 (JP, A) U) (58) Field surveyed (Int. Cl. ⁶ , DB name) B29C 45/00-45/24 B29C 45/46-45/88

Claims (4)

(57) [Claims] 1. An outer cylinder body having an outer cylinder nozzle hole drilled at a tip end connected to a mold, and an inner cylinder nozzle hole drilled at the tip corresponding to the outer cylinder nozzle hole. Is housed in the outer cylinder so as to be slidable in the axial direction of the outer cylinder,
An inner cylinder that forms a first resin passageway between the outer circumference and the inner circumference of the outer cylinder; and an inner cylinder that is housed in the inner cylinder so as to be slidable in the axial direction of the inner cylinder. In a resin injection device of a multilayer structure having a triple structure constituted by a needle forming a second resin passage with the inner circumference of the body, when the inner cylinder advances, the outer circumference of the front end portion of the inner cylinder comes into contact with the inner cylinder. When the first resin passage that communicates with the outer cylinder nozzle hole is closed, and when the inner cylinder retreats, the outer periphery of the front end of the inner cylinder is separated and the first resin that communicates the first resin passage with the outer cylinder nozzle hole. A seal portion is formed at an inner peripheral front end of the outer cylinder, and is formed in a straight shape close to the inner cylinder nozzle hole of the inner cylinder. When the needle advances, the front end of the needle is inserted and (2) After the resin passage is closed, it is further inserted to serve as a pressure-holding margin. Et exit and resin injection apparatus of the multilayer molded article second resin seal portion to open the second resin passage is characterized in that formed at the front end inner periphery of the inner cylinder. 2. An outer cylinder body having an outer cylinder nozzle hole formed at a tip end thereof connected to a mold, and an inner cylinder nozzle hole formed at a tip end corresponding to the outer cylinder nozzle hole. Is housed in the outer cylinder so as to be slidable in the axial direction of the outer cylinder,
An inner cylinder that forms a first resin passageway between the outer circumference and the inner circumference of the outer cylinder; and an inner cylinder that is housed in the inner cylinder so as to be slidable in the axial direction of the inner cylinder. In a resin injection device of a multilayer structure having a triple structure constituted by a needle forming a second resin passage with the inner periphery of the body, the resin injection device is formed in a straight shape close to the outer cylinder nozzle hole of the outer cylinder. When the inner cylinder advances, the front end of the inner cylinder is inserted to close the first resin passage, and after the second resin is injected into the mold by the needle, the tip of the inner cylinder further moves. When inserted into the straight portion, it becomes a pressure-holding allowance for the mold filling resin.
A first resin seal portion for opening the resin passage is formed on the inner periphery of the front end of the outer cylinder, and when the needle advances, the outer periphery of the front end of the needle contacts and closes the second resin passage communicating with the inner cylinder nozzle hole. Then, when the needle is retracted, the outer periphery of the front end of the needle is separated and a second resin seal portion communicating the second resin passage to the inner cylinder nozzle hole is formed at the inner peripheral front end of the inner cylinder. Characteristic resin injection equipment for multilayer molded products. 3. A resin injection device for a multilayer molded article having a triple structure according to claim 1 or 2, further comprising: an inner cylinder drive cylinder for moving the inner cylinder forward and backward; A resin injection device for a multilayer molded body, comprising a needle drive cylinder for moving forward and backward. 4. The resin injection device for a multilayer molded article having a triple structure according to claim 3, wherein the drive cylinder for the inner cylinder is formed on the inner periphery of the rear part of the outer cylinder and the outer periphery of the rear part of the inner cylinder. The drive cylinder for the needle is composed of an inner cylinder portion formed on the inner periphery of the rear portion of the inner cylinder and a piston portion for the needle formed on the outer periphery of the rear portion of the needle. A resin injection device for a multilayer molded article, characterized in that: