JPH0659672B2 - Multiple injection machine for multi-layer molding - Google Patents

Description

Description: [Industrial field of use] The present invention relates to an injection apparatus used for molding a multi-layer molded article having at least three cross-sectional structures.

[Prior Art] For molding a multi-layer molded product by injection molding, a resin is injected from a plurality of injection devices into a plurality of resin streams by a multiple nozzle having a plurality of concentric nozzle openings, and is injected and filled into a cavity. There is.

Although several methods are adopted for injection filling of a plurality of resins, all of them are performed by individually operating the injection device. Further, the resin amount of the surface layer and the inner layer required for the multi-layer molding is remarkably larger than that of the resin for molding the surface layer, and therefore, two kinds of apparatuses having different injection amounts are used. Molding by operating injection devices of different sizes is not so difficult when the cross-sectional structure of the molded product is a three-layer structure including a surface layer made of the same resin and an inner layer made of another resin. It is very difficult to mold a five-layer molded product made of three kinds of resins by individually operating three injection devices.
The amount produced by molding once is limited to a very small number, resulting in high cost.

Therefore, as a device of this type that can be mass-produced, a device described in JP-A-60-34819 is known.

[Problems to be Solved by the Invention] This known device is combined with a device for generating a material flow for forming each layer of a multilayer molded article, and a nozzle device to separate the material flows from each other so that each nozzle device has a separate material flow. Since it requires a flow channel device for guiding and a device for moving the material flow from each flow channel to the nozzle device, the structure is extremely complicated and costly compared to a normal injection device, and from the injection device to the nozzle device Since each resin has a long flow path, there is a problem that a special technique is required for controlling the flow velocity and pressure of the resin.

The present invention is easier to set conditions than a case where a plurality of injection devices are individually operated to perform multi-layer molding, the structure is simpler than that of the above-mentioned known device, and complicated operations are not required for molding. It is an object of the present invention to provide a multiple injection device for multi-layer molding.

[Means for Solving the Problems] A feature of the present invention according to the above-mentioned object is to provide an injection device for molding a surface layer of a multilayer molded article and one or a plurality of injection devices for molding an inner layer, which are hot with a multilayer nozzle. Plungers protruding from the rear end of each injection cylinder are integrally connected to the runner block, are integrally connected by a movable member, and a piston of an injection cylinder that simultaneously advances the plurality of plungers is connected to the movable member, and A cylinder and a piston for advancing the plunger of the surface layer injection device are provided in the movable member.

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

Further, each injection device is installed in parallel by connecting the injection cylinders to the upper part of the hot runner block having the same number of plasticizers as the injection devices on its back, and each injection cylinder is provided with a passage in the hot runner block. The injection cylinder is connected to each of the plasticizing devices and the multi-layer nozzle, has a means for preventing resin backflow to the plasticizing device side, and the injection cylinder is provided above the holding member that interconnects the injection cylinders. A movable member, which is attached to the support shafts on both sides and is connected to each plunger between the injection cylinder and the holding member, is provided so as to pass through the guide shaft, and the piston of the injection cylinder is attached to the movable member. It is composed of connected parts.

Further, the injection device includes a plunger for molding a surface layer of a multilayer molded product, a common injection cylinder in which one or more plungers for molding an inner layer are individually mounted, and a support shaft on both sides of a holding member integrated with the injection cylinder. An injection cylinder mounted on the injection cylinder, a piston in the injection cylinder connecting the plungers, a cylinder for moving the plunger for surface molding forward and a piston are provided in the piston of the injection cylinder, and the whole cylinder is 1 The injection unit is formed by connecting the injection cylinder to a hot runner block having the same number of plasticizers as the plungers, and the end of the injection cylinder at the tip of each plunger is hot runner. It is individually connected to each plasticizing device and the multi-layer nozzle via the flow path in the block, and has a means for preventing resin backflow to the plasticizing device side. That.

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.

[Operation] In the above configuration, since the plungers of each injection device are connected by the movable member, when the piston moves by driving the injection cylinder, all the plungers move forward simultaneously with the movable member connected to the piston. In operation, multiple types of molten resin are simultaneously injected into the hot runner. The molten resin of each hot runner is injected and filled into the mold cavity from each flow path of the multi-nozzle to form a molded product having a cross-sectional structure of 3 layers or 5 layers.

Also, since the plunger of the surface layer injection device can be independently moved by the cylinder and piston in the movable member, it is possible to precede the inner layer injection device in metering and injection, and if necessary, seal and hold pressure after injection filling. Etc. can be performed by operating the surface layer injection device.

[Embodiment] The embodiment shown in FIGS. 1 to 5 is configured such that three injection devices having screw plungers inside are multi-connected so that a multi-layer molded product of five layers of three types can be injection-molded. In the figure, 1 is an injection device for forming a surface layer located in the center (hereinafter referred to as an injection device for a surface layer), and 2 and 2 are injection devices for forming an inner layer located on both sides (hereinafter referred to as an injection device for an inner layer). Is.

In the embodiment shown in FIG. 1, the injection cylinders 3, 4, 4 of the respective surface layer and inner layer injection devices 1, 2, 2 are integrally connected to each other by a block-shaped holding member 5, and these The tip portion is connected to a hot runner block 7 having a multi-layer nozzle 6, and the injection devices 1, 2, 2 are arranged side by side on the back portion of the hot runner block 7.

In addition, screw plungers 8, 9, 9 are installed in each injection cylinder.
The screw end, which is inserted from the rear part so as to be rotatable and movable back and forth, and which projects from the rear end of the injection cylinder, has a block-shaped movable member 1.
The screw plungers 8, 9 and 9 are integrally connected by means of 0 so that the screw plungers 8, 9 and 9 move forward and backward simultaneously with the movable member 10.

Injection cylinders 11 are attached to both sides of the holding member 5 in parallel with the plungers, and the movable member 10 is connected to a piston 12 projecting to the rear of the injection cylinder 11. Rotating members 13 and 14 are inserted through the portions of the movable member 10 where the plunger ends are located.

The one rotating member 13 is rotatably housed inside a cylindrical piston 16 of a cylinder 15 provided inside a movable member, and the rear end of the screw plunger 8 is connected to the inner end thereof. A drive shaft 19 of a motor 18 at the outer end of the piston provided outside the movable member 10 is connected to the outer end by a guide shaft 17 so as to move together with the piston 16.

Regarding this connection, like the rotary ram type, a piston 16 is movably connected in the axial direction to a drive shaft 19 such as a square shaft, the plunger 8 is connected to the piston 16, and the rotary member 13 is connected. It may be omitted.

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 the motor 20 fixed to the movable member 10 is connected to the outer end.

As shown in FIG. 2, a valve cylinder 22 of the multi-nozzle 6 is provided at the center of the back of the hot runner block 7. As shown in FIG. 3, the bubbling cylinder 22 includes double cylinders 24 and 25 that move a rod-shaped valve 23 located at the center of the multi-nozzle 6 back and forth, and a piston 2.
6 and 27, the annular nozzles of five layers of resin passages 28, 29, 30, 31, 32 in a multi-nozzle formed in a concentric circle are opened and closed, and each is injected through hot runners 33, 34, 35. The injection of the molten resin pumped from the device to each resin path is controlled.

The embodiment shown in FIG. 4 is an example in which the hot runner block 7 attached to the stationary platen 37 of the mold clamping device 36 is provided with the injection devices 1, 2 for the surface layer and the injection devices for the inner layer 2 by nozzle touch. 38 is a mold, 39 is a movable plate, and 40 is
Is a mold clamping ram, and 41 is a tie bar.

As shown in FIG. 5, the multi-nozzle 6 used here has a core 23a in the central portion thereof, and five concentric resin paths 28 to 32 are formed around this core 23a.

Next, the operation of the above embodiment will be described. FIG. 1 shows a state where the measurement of the material is completed. In this state, when pressure oil is supplied to the oil chamber 11a on the right side of the injection cylinder 11 and the piston 12 is moved leftward, The movable member 10 moves to the left, the three screw plungers 8, 9, 9 move forward, and the molten resin measured in front of the screws of the injection cylinders 3, 4, 4 is fed to each of the hot runner blocks 7. Hot runner 3
Inject to 3, 34, 35.

Here, the molten resin of the hot runner 33 is in the resin passages 28 and 32 of the multiple nozzle 6, the molten resin of the hot runner 34 is in the resin passage 30, and the molten resin of the hot runner 35 is 29,
In the case of having the valve rod 23 pumped to each of the three (31
(See the drawing), the valve cylinder 22 is operated to inject and fill the cavity in the mold from the multiple nozzle 6 as a resin flow of five layers.

Further, in the case of the multiple nozzle 6 (see FIG. 5) having the core 23a in the central portion, the laminar flow is directly formed and the cavity is injected and filled.

In the injection molding of a multi-layer molded product, injection of the resin forming the surface layer is preceded, then the resin for the surface layer is injected together with the resin for forming the inner layer, and finally the resin for the surface layer is injected and filled. preferable. This is because the resin for the inner layer is prevented from protruding and the bottom can be molded with only the resin for the surface layer by performing the molding in this manner.

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

When the injection of the surface layer resin is carried out first and the single injection is finally carried out, the material measurement in the surface layer injection device 1 is carried out first. The measurement 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 measurement is performed within the range of the stroke S ₁ of the piston 16 while the back pressure is applied by the cylinder 15.

When the measurement of the predetermined amount of material is completed, the process is shifted to the whole measurement. Upon completion of the injection before the metering piston 12 of the injection cylinder 11 from moving in the oil chamber 11b side of the left side of the cylinder, the stroke S ₂ is the weighing tolerance from that position.

The metering is performed by driving the motors 18, 20, 20 while simultaneously applying a back pressure by the oil pressure in the oil chamber 11a of the injection cylinder 11 to rotate all the screw plungers 8, 9, 9 in unison. Material resin from each injection cylinder 3, 4, 4
Be sent to.

Each material resin is sheared and melted and measured in front of the screw, and the piston 12 moves backward in the stroke S ₂ to complete the measurement. When the weighing is completed, all the motors stop driving,
The process switches to injection filling.

The injection filling is performed by first rotating the rotary member 1 that moves forward together with the piston 16 by the operation of the cylinder 15 of the surface layer injection device 1.
The screw plunger 8 is moved forward via 3 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 and filled into the cavity from both the resin passages 28 and 32 of the multiple nozzle 6.
The injection amount at this time may be small, and therefore the preceding injection is stopped in the middle of the stroke S ₁ .

Subsequent to the preceding injection, the process is switched to the whole injection filling, and the oil pressure is applied to the oil chamber 11a of the injection cylinder 11. As described above, all screw plungers 8, 9, 9
Moves forward to inject the molten resin measured in front of the injection cylinders 3, 4, 4 into the hot runner block 7.

Among the resins to be the inner layer, the molten resin formed in the center as the barrier layer is the hot runner 34 to the multiple nozzle 6
The molten resin that is pressure-fed to the resin path 30 and is formed between the surface layer and the barrier layer as an adhesive layer is pressure-fed to the resin paths 29 and 31, and both of the molten resin to be the surface layers from the resin paths 28 and 32 are concentric. It becomes a laminar flow and is injected and filled into the cavity from the nozzle port.

When the piston 12 moves to the end of the stroke S ₂ , the operation of the injection cylinder 11 is stopped and the process is switched to the forward operation of the cylinder 15. As a result, the piston 16 moves forward in the remaining stroke of the stroke S ₁ , and injection-fills only the surface layer resin. As a result, only the molten resin for molding the surface layer is pushed into the cavity, and the end portions of the resin for molding the inner layer are all sealed inside, so that the resin is 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-preparing method in which a plasticized resin is supplied to an injection device and injection and filling is performed by a plunger is adopted.

In this multi-layer molding multiple injection device, the injection devices 1, 2, 2
It has the same number of plasticizers 50 for three in-line screws. This plasticizing device 50 includes a fixed plate 52 on a machine base 51.
Is horizontally installed on the upper part of the base using a pedestal 53, and its tip end is connected to the upper part of the hot runner block 7 mounted inside the fixed plate 52.

On the upper part of the hot runner block 7, a surface layer injection device 1 having a large-diameter plunger 8 and two inner layer injection devices 2 and 2 having a small-diameter plunger 9 are provided in each injection cylinder 3,
4, 4 are connected in parallel so as to face downward, 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 for preventing the backflow of the molten resin to the plasticizer side is provided at the connecting portion with the flow path 54.

Further, each injection cylinder 3, 4, 4 is connected to another flow path 56 connected to a predetermined flow path of the multi-nozzle 6, and each plunger 8, 9, 9 is connected.
Thus, each molten resin can be pressure-fed to the multiple nozzle 6 having the valve cylinder 22.

The upper portions of the injection cylinders 3, 4, 4 are integrally connected to each other by a plate-shaped holding member 5, and an injection cylinder 11 is attached above the holding member 5 to the upper end portion of a support shaft 57 on both sides of the holding member. A plate-shaped movable member 10 in which the upper ends of the plungers 8, 9, 9 are connected between the injection cylinder 11 and the holding member 5 is inserted into the guide shaft 57 and is vertically movable. It is provided in. Further, a piston 12 of an injection cylinder 11 is connected to the movable member 10, so that the plungers 8, 9, 9 are simultaneously operated for injection.

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, whereby the plunger 8 is
The piston 16 can be independently moved within the stroke S ₁ range.

In such a configuration, the resin for the surface layer and the inner layer is plasticized by each plasticizing device 50, and the molten resin is sent out from the flow path 54 to each of the injection cylinders 3, 4 and 4 and is simultaneously measured.

At this time, in order to precede the injection of the surface layer injection apparatus 1, the cylinder 15 is hydraulically operated to move the plunger 8 together with the piston 16 by the stroke S ₁ and place the plunger 8 upward.
The amount of the surface layer molding resin is more than that of the inner layer molding resin.

As in the case of the above-described embodiment, the injection filling after the measurement is preceded by the injection filling of the surface layer injection apparatus 1, and then the entire injection filling is performed up to the end of the stroke S ₂ , and the stroke S ₁
The process is completed by performing the single injection of the surface layer injection device 1 for the remaining strokes.

The embodiment shown in FIG. 8 is a case where three injection devices are unitized, and a plunger 8 for injecting a resin for surface layer is used.
And two plungers 9, 9 for injecting the resin for the inner layer are housed in a common injection cylinder 58, and the injection cylinders 11 are attached to the support shafts 60 on both sides of a holding member 59 integrated with the injection cylinder 58. The upper end of each of the plungers 8 and 9 is connected to the piston 12 of the injection cylinder 11, and the cylinder 13 and the piston 15 for advancing the plunger 8 for forming the surface layer are provided in the piston to configure the injection unit 61. Become.

Such an injection unit 61 can be provided by connecting the injection cylinder 58 to the hot runner block 7 having the plasticizing device, as in the embodiment shown in FIGS. 6 and 7.

FIG. 9 and FIG. 10 show the injection unit 61 with the hot runner block 7 having two multiple nozzles 6, 6.
2 shows a case where injection cylinders 58 are connected to both sides of the multi-layer molded article so that two multi-layer molded articles can be molded at the same time.

On the upper part of the hot runner block 7, three plasticizing devices 50 are vertically installed in parallel on a pedestal 53 on a fixed platen 52, and both injection units 61, 61 have respective injection cylinder end portions at the plunger tips. Is connected to each plasticizing device 50 individually via the flow passage 54 in the hot runner block shown in FIG. 8, and the plasticizing device is connected to the passage 54. A check valve 55 is provided for preventing backflow of the molten resin to the side.

Further, each injection cylinder end is connected to another flow path 56 connected to a predetermined flow path inside both of the multiple nozzles 6, and each plunger can send each molten resin under pressure to the multiple nozzles 6 and 6. It is like this.

11 and 12 show a case where the injection unit 61, the plasticizing device 50, and the hot runner block 7 can be moved back and forth like a normal injection device. The plasticizing device 50 installed horizontally in parallel at the upper part is fixed to a pedestal 64 that moves by using a support shaft 63 laid horizontally between a fixed plate 52 and a support plate 62 as a guide, and a pedestal support body 65 and a fixed plate 52. A nozzle touch cylinder 66 and a piston 67 are provided over the area, and by this, it is configured to be movable back and forth with respect to the fixed plate 37.

[Effects of the Invention] As described above, the present invention is configured such that a plurality of injection devices used for multi-layer molding are integrally multi-connected, and the resin for molding the surface layer and the inner layer can be simultaneously injected by a common injection cylinder. Therefore, it is easier to set the timing etc. by operating multiple injection devices of different models individually and co-injecting them. Since each layer is always injected in the same ratio, multi-layer molding with good molding conditions You can get the goods.

In addition, even though the injection device is shared, the surface layer injection device can also be separately weighed and individually injected, so that the surface layer resin can be pre-injected and pushed last, thereby completely preventing the inner layer from projecting or exposing. It is possible to surely mold the obtained multi-layer molded product with high molding accuracy.

Furthermore, since there is no need for a device for adjusting each resin pressure or speed between each injection device and multiple nozzles, the structure is not complicated, and the same operation as molding of a single-layer molded product is performed. It has the advantage that multi-layer molding can be carried out underneath.

[Brief description of drawings]

The drawings show an embodiment of the multiple injection apparatus for multi-layer molding according to the present invention. FIG. 1 is a cross-sectional plan view of a main part of the first embodiment, FIG. 2 is a sectional view taken along line II-II, and FIG. FIG. 4 is a cross-sectional plan view of a multi-nozzle, FIG. 4 is a plan view of an embodiment in which the tip of the injection cylinder is of a nozzle touch type, FIG. 5 is a cross-sectional plan view of the multi-nozzle portion of the above-mentioned embodiment, and FIG. A partially longitudinal rear view of the second embodiment, FIG. 7 is a side view thereof, FIG. 8 is a vertical cross-sectional view of an embodiment in which a plurality of injection devices are unitized to form multiple units, and FIG. 9 is a unit of the injection device. Front view of an embodiment employing
FIG. 11 is a side view thereof, FIG. 11 is a side view in which a part of another embodiment is similarly removed, and FIG. 12 is a front view thereof. 1 …… Surface layer injection device 2 …… Inner layer injection device 3,4 …… Injection cylinder 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 of screw plunger (8) 14 …… Rotating member of screw plunger (9) 15 …… Cylinder of screw plunger (8) 16 …… Screw plunger ( 8) Piston 18 ... Motor for surface layer injection device 20 ... Motor for inner layer injection device 50 ... Plasticizer 61 ... Injection unit

Claims (5)

[Claims] 1. An injection device for molding a surface layer of a multilayer molded article,
One or a plurality of injection devices for molding the inner layer are arranged side by side in a hot runner block equipped with a multi-layer nozzle, and plungers protruding from the rear end of each injection cylinder are integrally connected by a movable member, and the movable A multi-layered molding characterized in that a piston of an injection cylinder for simultaneously advancing the plurality of plungers is connected to a member, and a cylinder and a piston for advancing the plunger of the surface layer injection device are provided in the movable member. Multiple injection device. 2. The plunger comprises a screw plunger, and the screw plunger of the injection device for molding the surface layer is
A screw plunger of an injection device, which is connected to a drive shaft of a motor on the movable member side through a piston of a cylinder provided in the movable member or a rotating member penetrating the piston to form an inner layer, is provided in the movable member. The multiple injection device for multilayer molding according to claim 1, wherein the multiple injection device is connected to a drive shaft of a motor on the movable member side through a rotating member. 3. Each injection device is provided on the top of a hot runner block having as many plasticizers as the injection devices on its back,
The injection cylinders are connected and arranged side by side, and each injection cylinder is individually connected to each plasticizing device and the multi-layer nozzle via the flow path in the hot runner block, while preventing resin backflow to the plasticizing device side. An injection cylinder is attached to the support shafts on both sides of the holding member, and the plunger is connected between the injection cylinder and the holding member. 2. The multiple injection apparatus for multilayer molding according to claim 1, wherein the movable member is provided so as to be inserted through the guide shaft, and the piston of the injection cylinder is connected to the movable member. 4. An injection apparatus comprising: a plunger for molding a surface layer of a multilayer molded article; a common injection cylinder in which one or a plurality of plungers for molding an inner layer are individually mounted; and both holding members integrated with the injection cylinder. The injection cylinder mounted on the spindle of the injection cylinder and provided in the injection cylinder, the piston in the injection cylinder in which the plungers are connected, and the cylinder for moving the plunger for surface layer forming forward and the piston are provided in the piston of the injection cylinder. It consists of a unitized whole,
The injection unit is provided by connecting an injection cylinder to a hot runner block having the same number of plasticizers as the above-mentioned plungers, and the end of the injection cylinder at the tip of each plunger passes through a flow path in the hot runner block. 4. The multiple injection apparatus for multi-layer molding according to claim 3, further comprising means for preventing backflow of the resin to the side of the plasticizer, which is individually connected to the plasticizer and the multilayer nozzle. 5. A plunger of an injection device for molding an inner layer comprises:
5. The multiple injection device for multilayer molding according to claim 1, wherein the injection device for molding the surface layer has a diameter smaller than that of the plunger of the injection device.