JPH03182318A - Multiple injection device for multilayer molding - Google Patents

Abstract

PURPOSE:To facilitate the setting of timing and the like and obtain a multilayer molded form having excellent molding conditions of respective layers by a method wherein a plurality of injection devices, which are employed for multilayer molding, are integrated to multiply them and resin molding a surface layer and an inner layer is injected simultaneously by a common injection cylinder. CONSTITUTION:When pressure oil is supplied to an oil chamber 11a at the right side of an injection cylinder 11 to move a piston 12 leftward, a movable member 10 is moved leftward together with the piston 12 to move three sets of screw plungers 8, 9, 9 forward whereby the resin of molten condition, which is metered before the screws of respective injection cylinders 3, 4, 4 is injected into respective hot runners 33, 34, 35 of a hot runner block 7. In this case, the molten resin of the hot runner 33 is set into the resin passages 28, 32 of a multiple nozzle 6, the molten resin of the hot runner 34 is sent into the resin passage 30 while the molten resin of the hot runner 35 is sent to resin passages 29, 31 respectively by pressure. When a valve rod 23 is provided, the resin is injected and filled from the multiple nozzle 6 into the cavity in the mold as the resin flow of five layers by the operation of a valve cylinder 22.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application 1] The present invention relates to an injection device used for molding a multilayer molded product having at least three layers in cross section.

[Prior art 1] In the molding of multilayer molded products by injection molding, resin from multiple injection devices is arranged into multiple resin flows using multiple nozzles with multiple nozzle openings formed in concentric circles, and then injected into a cavity. There is.

In addition, several methods have been adopted for injection filling of a plurality of resins, but all of them are performed by operating an injection device all at once. In addition, the amount of resin required for multilayer molding for the surface layer and the inner layer is significantly larger for the resin used to mold the surface layer, and therefore two types of equipment, large and small, with different injection amounts are used. Molding using injection devices of different sizes is not so difficult if the cross-sectional structure of the molded product is three layers consisting of a surface layer made of the same resin and an inner layer made of another resin. It is extremely difficult to mold a 5-layer structure molded product made of 3 types of resin by individually operating 3 injection devices, and 1.
The amount produced by multiple moldings is also limited to a very small number, resulting in high costs.

Therefore, as a device of this type that can be mass-produced, the one described in Japanese Patent Application No. 60-34819 is known.

[Problems to be Solved by the Invention] This known device is combined with a device that generates a material flow for forming each layer of a multilayer molded product and a nozzle device to separate the material flows from each other and send them to the respective nozzle devices. Because it requires a channel device to guide the material flow and a device to move the material flow from each channel to the nozzle device, the structure is extremely complex and expensive compared to a normal injection device, and the process from the injection device to the nozzle device is extremely complicated. Since the flow paths of each resin are long, there are problems such as requiring special technology to control the flow rate and pressure of the resin.

This invention is a new method that allows for easier setting of conditions than when performing multilayer molding by individually operating a plurality of injection devices, has a simpler structure than the above-mentioned known devices, and does not require complicated operations for molding. The object of the present invention is to provide a multiple injection device for multilayer molding.

[Means for Solving Problem 11] The feature of the present invention according to the above object is that an injection device for molding the surface layer of a multilayer molded product and one or more injection devices for molding the inner layer are equipped with a multilayer nozzle. Plungers that are arranged in parallel to the hot runner block and protrude from the rear end of each injection cylinder are integrally connected by a movable member, and a piston of an injection cylinder that moves the plurality of plungers simultaneously forward is connected to the movable member. , and a cylinder and a piston for moving the plunger of the surface layer injection device forward are provided in the movable member.

The plunger is a screw plunger, and the screw plunger of the injection device for molding the surface layer connects to the drive shaft of the motor on the movable member side via a piston of a cylinder provided in the movable member or a rotating member penetrating the piston. A screw plunger of an injection device that connects and molds the inner layer is connected to a motor on the movable member side via a rotating member provided within the movable member.

In addition, each injection device is arranged in parallel with an injection cylinder connected to the upper part of a hot runner block which has the same number of plasticizing devices as the injection device on its back, and each injection cylinder connects a flow path in the hot runner block. An injection cylinder is connected to each plasticizing device and the multilayer nozzle through the plasticizing device, and has means for preventing backflow of resin to the plasticizing device side, and above a holding member that interconnects the injection cylinders. A movable member, which is attached to the support shafts on both sides of the holding member and has each plunger connected between the injection cylinder and the holding member, is inserted through the guide shaft. It consists of connected pistons.

In addition, the injection device includes a common injection tube in which a plunger for molding the surface layer of a multilayer molded product and one or more plungers for molding the inner layer are individually housed, and a support shaft on both sides of a holding member integrated with the injection tube. An injection cylinder installed and provided in the injection tube, a piston in the injection cylinder to which each plunger is connected, and a cylinder and piston for moving the plunger for surface molding forward are provided in the piston of the injection cylinder, and the whole is assembled into one. The injection unit is provided by connecting an injection cylinder to a hot runner block having the same number of plasticizing devices as the plungers, and the end of the injection cylinder at the front of each plunger is heated. It is individually connected to each plasticizing device and the multilayer nozzle via a flow path in the runner block, and has means for preventing backflow of resin toward the plasticizing device.

The plunger of the injection device that molds the inner layer of the molded product has a smaller diameter than the plunger of the injection device that molds the surface layer.

[Function] In the above configuration, since the plungers of each injection device are connected by the retractable member, when the piston moves due to the drive of the injection cylinder, all the plungers simultaneously move together with the movable member connected to the pinoton. By moving forward, a plurality of types of molten resin are simultaneously injected into the hot runner.

The molten resin from each hot runner is injected and filled into the mold cavity through the channels of multiple nozzles to form a molded product with a 3-layer or 5-layer cross-sectional structure.

In addition, since the plunger of the surface layer injection device can be moved independently by the cylinder and piston in the movable member, it is possible to carry out metering and injection earlier than the inner layer injection device, and if necessary, perform sealing and pressure holding after injection and filling. etc., can be performed by operating a surface layer injection device.

[Embodiment] The embodiment shown in FIGS. 1 to 5 is configured to multiplex three injection iA positions inside the screw plunger so that a multilayer molded product of three types and five layers can be injection molded. 1 is an injection device for molding the surface layer located in the center (hereinafter referred to as the injection device for surface layer), and 2.2 is an injection device f for molding the inner layer located on both sides (hereinafter referred to as the injection device for inner layer). (say).

In the embodiment shown in FIG. 1, each injection device 1 for the surface layer and for the inner layer
, 2.2 are integrally connected to each other by a block-shaped holding member 5, and their tips are connected to a hot runner block 7 having a multilayer nozzle 6, At the back of the hot runner block 7, injection bags ff1.2°2 are arranged in parallel.

Further, screw plungers 8 and 9 are inserted into each injection cylinder from the rear so as to be rotatable and movable back and forth, and the screw ends protruding from the rear end of the injection cylinder are integrally connected by a block-shaped movable member 10. Each screw plunger 8.9
．． 9 is designed to move forward and backward at the same time as the movable member 10.

Injection cylinders 11 are mounted on both sides of the holding member 5 in parallel with the plunger, and the movable member 10 is connected to a piston 12 that projects from the rear of the injection cylinder 11. Further, rotating members 13 and 14 are inserted through the portions of the movable member 10 where each plunger end is located.

This one rotating member 13 is rotatably housed inside a cylindrical piston 16 of a cylinder 15 provided within the movable member, and the rear end portion of the screw plunger 8 is connected to the inner end thereof. In addition, a drive shaft 19 of a motor 18 at the outer end of the piston, which is provided on the outside of the movable member 10 with a guide shaft 17, is connected to the outer end so as to move together with the piston 16. Like the ram type, a piston 16 is connected to a drive shaft 19 such as a square shaft so as to be movable in the axial direction, and a plunger 8 is connected to the piston 16.
You may connect them and omit the rotating member 13.

The rear end of the screw plunger 9 is connected to the inner end of the other rotating member 14, and the drive shaft 21 of a motor 20 fixed to the movable member 10 is connected to the outer end.

At the center of the back of the hot runner block 7, as shown in FIG. 2, a valve cylinder 22 for the multiple nozzles 6 is provided. As shown in FIG. 3, this valve cylinder 22 consists of a double cylinder 24, 25 and a piston 26 that move forward and backward a rod-shaped valve 23 located at the center of the multiple nozzle 6.
．． 27, and 5 in the multiple nozzles formed in concentric circles.
The annular nozzles of N resin paths 28, 29, 30, 31, and 32 are opened and closed to control the injection of molten resin that is pumped from each injection device to each resin path via hot runners 33, 34, and 35. .

In the embodiment shown in FIG. 4, a hot runner block 7 attached to a fixed platen 37 of a mold clamping device 36 has injection devices for the surface layer and the inner layer. 1.2.2 are arranged side by side by touching the nozzles, 38 is a mold, 39 is a movable platen, 40
indicates a mold clamping ram, and 41 indicates a tie bar.

The multiple nozzle 6 used here has a core 23a in the center, as shown in FIG. 5, and concentric 5N resin paths 28 to 32 are formed around the core 23a.

Next, the operation in the above embodiment will be explained.

FIG. 1 shows the state where the measurement of the material has been completed, so in this state, the oil chamber 11 on the right side of the injection cylinder 11
When pressure oil is supplied to a and the piston 12 is moved to the left,
Together with the piston 12, the movable member 10 moves to the left, and the three screw plungers 8, 9.9 move forward, discharging the molten resin measured in front of the screw of each injection cylinder 3° 4.4. The hot runners 33, 34, and 35 of the runner block 7 are injected.

Here, the molten resin from the hot runner 33 goes into the resin path 28.32 of the multiple nozzle 6, the molten resin from the hot runner 34 goes into the resin path 30, and the molten resin from the hot runner 35 goes into the resin path 29.
31 and has a valve stem 23 (the third
(see figure), by operating the valve cylinder 22, the resin is injected and filled into the cavity in the mold from the multiple nozzles 6 as a five-layer resin flow.

In the case of a multiple nozzle 6 (see FIG. 5) having a core 23a in the center, the injected material is injected and filled into the cavity as it is in a laminar flow.

When injection molding multilayer molded products, the resin that forms the surface layer is injected first, then the resin for the surface layer is injected together with the resin that will mold the inner layer, and finally the resin for the surface layer is injected and filled. preferable. This is because when molding is performed in this manner, protrusion of the resin for the inner layer is prevented, and the bottom portion can be molded only with the resin for the surface layer.

Further, the filling amount of each resin forming the multilayer molded product is different between the surface layer and each inner layer, and the ratio of the measured materials is determined mechanically by the screw diameter.

When the surface layer resin is first injected and the individual injection is performed last, the material is first measured in the surface layer injection device 1. The metering is performed by rotating the screw plunger 8 by the motor 18 via the rotating member 13 and feeding the material resin into the injection cylinder 3 from the supply port 5a of the holding member 5. This metering is performed within the stroke S1 of the piston 16 while back pressure is applied by the cylinder 15.

Once the predetermined amount of material has been measured, the next step is to measure the entire material. When the injection is completed before metering, the piston 12 of the injection cylinder 11 has moved to the oil chamber 1ib on the left side of the cylinder, so the stroke S2 from that position falls within the metering allowable range.

Metering is carried out by driving the motor 18.20°20 while applying back pressure by the hydraulic pressure of the oil chamber 11a of the injection cylinder 11, rotating all the screw plungers 8 and 9°9 at the same time, and opening each supply port 5a. This is done by feeding the resin material into each injection cylinder 3, 4.4.

Each material resin is shear-melted and metered in front of the screw, and the piston 12 moves backward through stroke S2 to complete metering. At the same time as measurement is completed, all motors stop driving.
The process switches to injection filling.

Injection filling is performed by first operating the cylinder 15 of the surface layer injection device 1, and the rotating member 1 moves forward together with the piston 16.
3, the screw plunger 8 is moved forward to inject a predetermined amount of the surface layer resin into the hot runner 33 of the hot runner block 7. This resin is injected into the cavity from both resin passages 28, 32 of the multiple nozzle 6.

The amount of injection at this time may be small, so the advance injection is stopped in the middle of the stroke S1.

Following this preliminary injection, the process is switched to full injection filling, and hydraulic pressure is applied to the oil chamber 11a of the injection cylinder 11. All screw plungers 8,9.9 as mentioned above
moves forward and injects the molten resin measured into the front part of the injection cylinder 3°4.4 into the hot runner block 7.

Among the resins forming the inner layer, the molten resin formed in the center as a barrier layer is passed from the hot runner 34 to the multiple nozzle 6.
The molten resin to be formed between the surface layer and the barrier layer as an adhesive layer is pumped to the resin path 29.31, and the molten resin forming the surface layer from the resin path 28.32 forms a concentric circle. It becomes a laminar flow and is injected and filled into the cavity from the nozzle opening.

When the piston 12 has moved to the end of stroke $2, the operation of the injection cylinder 11 is stopped and the process is switched to forward operation of the cylinder 15. As a result, the piston 16 moves forward through the remaining stroke of the stroke S1 to inject and fill only the surface layer resin. As a result, only the molten resin for molding the surface layer is forced into the cavity, and the ends of the resin for molding the inner layer are all sealed and are not exposed to the outside. The process then switches to holding pressure.

The embodiment shown in FIG. 6 and FIG. 7 shows a case where a so-called screw-brib system is adopted in which plasticized resin is supplied to an injection device and injection and filling is performed using a plunger.

This many li! In the multiple injection device for molding, the injection device 1゜2
．． 2 and the same number of 3 in-line screw plasticizing devices 5
has 0. This plasticizing device 50 is installed horizontally using a pedestal 53 above a fixed platen 52 on a machine stand 51, and its tip is connected to the upper part of a hot runner block 7 attached inside the fixed platen 52. There is.

In the upper part of the hot runner block 7, there are two injection devices 2°2 for the surface layer, a surface layer injection device W1 having a large diameter plunger 8, and an inner layer injection device 2°2 having a small diameter plunger 9, each injection cylinder 3.4.
．． 4 are connected downwardly and provided in parallel, and each injection cylinder 3.4.4 is individually connected to each plasticizing device 50 via a flow path 54 in the hot runner block. A check valve 55 is provided at the connection portion with the flow path 54 to prevent the molten resin from flowing back toward the plasticizing device.

Further, each injection cylinder 3, 4.4 is connected to another flow path 56 connected to a predetermined flow path of the multiple nozzle 6, and each plunger 8.9.9
This makes it possible to force-feed each molten resin to the multiple nozzle 6 equipped with the valve cylinder 22.

The upper parts of each injection cylinder 3, 4.4 are integrally connected to each other by a plate-shaped holding member 5, and above the holding member 5, an injection cylinder 11 is attached to the upper end of a support shaft 57 on both sides of the holding member. Between the injection cylinder 11 and the holding member 5, a plate-shaped movable member 10, which connects the upper end of each plunger 8, 9, 9, is inserted into the guide shaft 57 and is movable up and down. It is set in. Further, a piston 12 of an injection cylinder 11 is connected to the movable member 10, so that each plunger 8, 9, 9 can perform an injection operation at the same time.

Furthermore, the portion of the movable member 10 where the plunger 8 is located is a cylinder 15 of a piston 16 connected to the upper end of the plunger 8.
In such a configuration in which the piston 16 can move independently within the range of the stroke S1, the resin for the surface layer and the inner layer is plasticized by each plasticizing device 50, and the molten resin is injected from the flow path 54! ! 3.4.4, and weighing is performed at the same time.

At this time, in order to precede the injection of the surface layer injection bag @1, the cylinder 15 is hydraulically operated to move the plunger 8 and the piston 16 upward by a stroke S1.
Make sure that the amount of surface layer molding resin is larger than that of the inner layer molding resin.

In the injection filling after measurement, as in the case of the previous embodiment, injection filling of the injection bag N1 for the surface layer is performed first, and then the entire injection filling is carried out to the end of the stroke S2, and the injection filling for the surface layer is performed only for the remaining stroke of the stroke S1. A single injection of the device 1 is performed to complete the process.

The embodiment shown in FIG. 8 is a case where three injection devices are integrated into a unit, and the plunger 8 injects the resin for the surface layer.
Two plungers 9.9 for injecting the resin for the inner layer are installed in a common injection cylinder 58, and the injection cylinders 11 are attached to the support shafts 60 on both sides of the holding member 59 that is integrated with the injection cylinder 1158. The upper end of each plunger 8.9 is connected to a piston 12 of a cylinder 11, and a cylinder 13 and a piston 15 for moving the plunger 8 for surface molding forward are provided in the piston, and an injection unit 61 is constructed. Become.

Such an injection unit 61 is a hot runner having a plasticizing device, similar to the embodiment shown in FIGS. 6 and 7.
An injection cylinder 58 can be connected and provided to the block 7.

9 and 10 show the injection unit 61 in a hot runner block 7 with two multiple nozzles 6.6.
This figure shows a case in which injection tubes 58 are connected and provided on both sides of the molding machine, so that two multilayer molded products can be molded at the same time.

At the top of the hot runner block 7, three plasticizing devices 50 are installed vertically on a pedestal 53 on a fixed platen 52 and installed in parallel, and each injection cylinder end in front of the plunger of both injection units 61 and 61 is installed in parallel. As in the above embodiment, the parts are individually connected to each plasticizing device 50 via a flow path 54 in the hot runner block shown in FIG. A check valve 55 is provided to prevent backflow of molten resin to the oxidizer side.

Further, each injection cylinder end is connected to another flow path 56 connected to a predetermined flow path inside both multiple nozzles 6, and each plunger can force-feed each molten resin to the multiple nozzle 6.6. It looks like this.

11 and 12 show a case in which the injection unit 61, the plasticizing device f50, and the hot runner block 7 can be moved forward and backward in the same way as a normal injection device, and the hot runner block The plasticizing devices 50 arranged horizontally on the upper part of the 7 are fixed to a pedestal 64 that moves as a guide with a support shaft 63 horizontally suspended between a fixed plate 52 and a support plate 62, and fixed to a pedestal support 65. A nozzle touch cylinder 66 and a piston 67 are provided over the panel 52, so that the nozzle touch cylinder 66 and the piston 67 can be freely moved forward and backward relative to the fixed part 1137.

[Effects of the Invention] As described above, the present invention is configured such that a plurality of injection devices used for multilayer molding are integrally connected and resins for molding the surface layer and the inner layer can be simultaneously injected using a common injection cylinder. Therefore, it is easier to set the timing, etc. than when co-injecting is performed by individually operating a plurality of injection devices of different models, and a multilayer molded product with good molding conditions of each layer can be obtained.

In addition, although the injection device is shared, the injection device for the surface layer can be used for independent metering and injection, so the surface layer resin can be injected in advance and pushed in at the end, thereby completely preventing protrusion or exposure of the inner layer. High precision molding machine
Shaped products can be molded reliably.

Furthermore, since there is no need for a device to adjust each resin pressure, speed, etc. between each injection device and multiple nozzles, the structure does not become complicated, and the operation is similar to that of molding a single-layer molded product. It has the advantage of being able to carry out multilayer molding under the

[Brief explanation of drawings]

The drawings show an embodiment of the multiple injection device for multilayer molding according to the present invention, and FIG. 1 is a cross-sectional plan view of the main part of the first embodiment, FIG. The figure is a cross-sectional plan view of the multiple nozzle, FIG. 4 is a plan view of an embodiment in which the tip of the injection tube is a nozzle touch type, FIG. 5 is a cross-sectional plan view of the multiple nozzle portion of the above embodiment, and FIG. 7 is a side view of the second embodiment, FIG. 8 is a sectional view of an embodiment in which a plurality of injection devices are unitized and connected in multiple units, and FIG. 9 is a unit of the injection device. FIG. 10 is a side view of the embodiment, FIG. 11 is a partially cutaway side view of another embodiment, and FIG. 12 is a front view thereof. 1... Injection device for surface layer 2... Injection device for inner layer 3.4... Injection tube 5... Holding member 6.・・・・・・・・・Multilayer nozzle 7・・・・・・Hot runner block 8.9・
...Screw plunger (plunger) 10...
......Movable member 11...Injection cylinder 12...Piston, 13...Rotating member 14 of screw plunger (8)・・・・・・・・・Screw plunger (
Rotating member 15 of 9)...Cylinder 16 of screw plunger (8)...Piston 18 of screw plunger (8)...Surface layer Motor 20 of the injection device for inner layer...Motor 50 of the injection device for inner layer...Plasticizing device 61...Injection unit Fig. 2 1 Figure 3 Figure 5 Figure 7 Figure 1 Figure 11 Figure 12

Claims (5)

[Claims] (1) An injection device for molding the surface layer of a multilayer molded product and one or more injection devices for molding the inner layer are installed side by side in a hot runner block equipped with a multilayer nozzle, and from the rear end of each injection cylinder. A cylinder in which the protruding plungers are integrally connected by a movable member, the piston of an injection cylinder that simultaneously moves the plurality of plungers forward is connected to the movable member, and the plunger of the surface layer injection device is moved forward within the movable member. A multiple injection device for multi-layer molding, characterized by comprising: and a piston. (2) The plunger is a screw plunger, and the screw plunger of the injection device for molding the surface layer drives the motor on the movable member side via the piston of a cylinder provided in the movable member or the rotating member penetrating the piston. 2. The screw plunger of the injection device connected to the shaft and molding the inner layer is connected to the drive shaft of the motor on the movable member side via a rotating member provided within the movable member. Multiple injection device for multilayer molding. (3) Each injection device is arranged in parallel with an injection cylinder connected to the upper part of a hot runner block which has the same number of plasticizing devices as the injection device on its back, and each injection cylinder connects a flow path in the hot runner block. An injection cylinder is connected to each plasticizing device and the multilayer nozzle through the plasticizing device, and has means for preventing backflow of resin to the plasticizing device side, and above a holding member that interconnects the injection cylinders. A movable member, which is attached to the support shafts on both sides of the holding member and has each plunger connected between the injection cylinder and the holding member, is inserted through the guide shaft. 2. The multiple injection device for multilayer molding according to claim 1, characterized in that it has a structure in which pistons are connected. (4) The injection device consists of a common injection tube that individually houses a plunger for molding the surface layer of a multilayer molded product and one or more plungers for molding the inner layer, and supports on both sides of a holding member integrated with the injection tube. An injection cylinder attached to the shaft and provided in the injection cylinder, a piston in the injection cylinder in which each plunger is connected, and a cylinder and piston for moving the plunger for surface molding forward are provided in the piston of the injection cylinder as a whole. The injection unit is provided by connecting an injection cylinder to a hot runner block having the same number of plasticizing devices as the plungers, and the end of the injection cylinder at the front of each plunger is 4. The multilayer according to claim 3, wherein the multilayer is individually connected to each plasticizing device and the multilayer nozzle via a flow path in the hot runner block, and further includes means for preventing backflow of resin toward the plasticizing device. Multiple injection device for molding. (5) The multiple injection device for multilayer molding according to any one of claims 1, 2, 3, and 4, wherein the plunger of the injection device that molds the inner layer has a smaller diameter than the plunger of the injection device that molds the surface layer.