JP3041067B2 - Injection mold - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold for injection molding and, more particularly, to a mold having a plurality of resin passages and injecting a plurality of kinds of resins to simultaneously produce a plurality of sets of products having a multilayer structure corresponding thereto. About.

[0002]

2. Description of the Related Art Most of the conventional molds of this type are the same as those of the embodiment of the present invention, and the similar parts will be described with reference to FIGS. I do. This mold is composed of a fixed mold A and a movable mold B, and the fixed mold A has a plurality of first and second multilayer molding portions 1 of the same shape.
2 and the respective multilayer molded portions 1 and 2 have the same shape as described above, so that the first multilayer molded portion 1 is shown in FIGS. The multilayer molded parts 1 and 2 have first and second
First and second central resin passages 5 and 6 having outlets 3 and 4, and at least one (two in this example) first and second peripheral resin passages 7-1 and 2-1; , Peripheral resin passage 7-
The first, second, and third stems 9, 10, 10, and 12 open at different positions in the axial direction of the central resin passages 5 and 6 so as to be movable on the axis thereof in the central resin passages 5 and 6. The rear ends of the stems 9 and 10 are connected to the first hydraulic cylinders 11 and 11, respectively.
17, 16 are connected to the first pistons 13, 14 disposed in the inside 12, and are ventilation holes for supplying fluid to the front and rear surfaces of the first pistons 13, 14. A fluid pressure second cylinder 19, which further forms a stop member behind the first cylinders 11, 12,
The second cylinders 19, 20 have second pistons 21, 22 having a pressure receiving area larger than the first pistons 13, 14 housed in the first cylinders 11, 12 so as to protrude therefrom. Numerals 23 and 24 are ventilation holes for supplying fluid to the rear surfaces of the second pistons 21 and 22. The stems 9 and 10 have a fully closed position (FIG. 2) where fluid is supplied to the vents 16 and 18 to prevent communication between the outlets 3 and 4 and the resin passages 5, 6, 7, and 8; , 17 to move between the outlet 5 and the fully open position (FIG. 3) to allow communication between the resin passages 5, 6, 7, 8 and vent holes 16, 23; By supplying the fluid to the second pistons 21 and 22
It protrudes into the chambers of the cylinders 11, 12 and abuts against the first pistons 13, 14, thereby stopping at an intermediate position between them (FIG. 4). The movable mold B is provided with first and second cavities 25 and 26.

FIG. 7 shows a control circuit for a pressurized fluid in such a mold, and the vent holes 15, 16, 23;
One ends of vent pipes 29, 30, 31; 33, 34, 35 are connected to 8, 24, and the other ends of vent pipes 29, 33; 30, 34; It is connected to pipes 37,38,39. These first, second, and third feed / exhaust pipes 37, 38, and 39 are connected to an air supply source 45 or the atmosphere via switching valves 41, 42, and 43 that are solenoid valves. These switching valves 41, 42, 43 are connected to the injection molding machine 46 via control members 47, 48, 49, and by the operation of these control members 47, 48, 49, the supply and exhaust pipes 37, 38, 39 communicates with the air supply 45 or the atmosphere.

In such a mold, each of the multilayer molded parts 1 and 2
Each of the ventilation holes 15, 17; 16, 18; 23, 24 is a switching valve
Both stems 9 and 10 are connected to 41, 42 and 43.
Outlets 3 and 4 by supplying fluid to vent holes 16 and 18
To the closed position where communication with the resin passages 5, 6, 7, 8 is prevented, and between the outlet 5 and the resin passages 5, 6, 7, 8 by supplying fluid to the ventilation holes 15, 17. The movement to the fully open position allowing the communication, or the stop at the intermediate position by supplying the fluid to the ventilation holes 16, 23; 18, 24, and the like are simultaneously performed. FIG. 7 shows the ventilation holes 15 and 17 for the air supply source 4.
1, the vent holes 15, 17; 16, 18, 23, 24 communicate with the atmosphere, and the stems 9, 10 are in the fully open position.

[0005]

The case of forming a three-layer molded product in such a mold will be described with reference to FIGS. 8 to 11. First, the primary injection for forming the skin resin layer x shown in FIG. And supply the fluid to the vent holes 16, 23; 18, 24 so that the stems 9, 10 are connected to the outlets 3, 4 and the outermost peripheral resin passage 7-.
2,8-2 and other resin passages 5,6,7-1,8
-1 is moved to the position to close, and the resin passages 7-2 and 8-2
The first resin a to be the skin layer x is supplied from both cavities 25 and 26
In this case, the amount of resin injected into the cavities 25 and 26 is not equal due to uneven temperature of the hot runner and unbalance of the flow resistance. Is attached.

Next, a secondary injection for forming the core resin layer y shown in FIG. 9 is performed. In this case, a fluid is supplied to the air holes 15 and 17 and the stems 9 and 9 are supplied.
10 is moved to the fully open position allowing communication between the outlets 3, 4 and all the resin passages 5, 6, 7, 8;
The second and third resins b and c to be the core resin layer y from 7 and 8 are injected into both cavities 25 and 26. By doing so, the distance D3 between the tips of the core resin layer y due to the injected second and third resins b and c is small, but the distance D2 between the tips of the skin resin layer x due to the first resin a is large.

Next, a tertiary injection for forming the cut resin layer z for cutting the core resin layer y shown in FIG. 10 is performed. In this case, the stems 9 and 10 are connected to each other as shown in FIG. At the same position as the time of the next injection, the same first resin a as the skin resin layer x for cutting the core resin layer y is injected into the first cavity 25 and the second cavity 26. Thus, the tip of the core resin layer y made of the injected second and third resins b and c is longer in the second cavity 26 than in the first cavity 25, and the skin resin layer x made of the first resin a is formed. The distance D4 between the tips becomes smaller.

FIG. 11 shows a state in which the resin is completely filled in both cavities 25 and 26 as described above. As can be seen from the figure, the tip of the core resin layer y is positioned closer to the second cavity 26. Is longer by a length D5, and the cut resin layer z is D6
Only shorter.

In the conventional mold as described above, as described above, there is a problem that the distribution of the molded product is different for each layer and it is difficult to make the whole uniform, and as a measure for solving such a problem, The resin in the nozzle portion is heated and adjusted by the nozzle heater 27 to adjust the imbalance of filling between the cavities 25 and 26. Therefore, even if the set temperature of the nozzle portion is changed, the temperature is immediately increased. It is difficult to change the temperature stably, and it is difficult for the second and third resins b and c to be rapidly affected by the temperature change of the mold. Since the result after the adjustment cannot be confirmed unless the minutes have elapsed, there is a problem that it takes a long time to adjust the imbalance of the filling between the cavities 25 and 26.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the conventional mold and to provide an injection mold capable of efficiently forming a plurality of good and uniform multilayer molded products by an easy operation. To offer.

[0011]

According to the present invention, in order to achieve the above-mentioned object, in the above-mentioned conventional injection molding die, a fluid circuit for operating a fluid cylinder is provided for each multilayer molding part. And a control means provided for each of these fluid circuits. Further, the control means has a timer for determining the timing of operating a control valve contributing to supply and discharge of fluid to each fluid circuit, and further comprises a detection means for reading a resin distribution of a product sample, and the control means outputs the output from the detection means. The operation time of the timer is set based on the input signal.

[0012]

In the present invention as described above, the operation of the timer is started by the injection signal of the injection molding machine, and the control output from the control member based on the signal from the first and second detection members obtained from the product sample. Each timer operates for the time determined by the signal, and for example, as for a molded article as shown in FIG. 11, the first stem of the first multilayer molding section 1 has moved to the intermediate position where the first resin is injected. At this time, in the second multilayer molding section 2, the second stem 10 is at the fully closed position, then a primary injection completion signal is output, and the first stem of the first multilayer molding section 1 is at the fully open position, and all the resin is used. The process shifts to the secondary injection, and the second stem is at the intermediate position in the second multilayer molded portion, and the injection and injection of the first resin is continued.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the embodiment of the present invention shown in FIGS.
The same parts as those of the conventional injection molding die will be denoted by the same reference numerals, and the description thereof will be omitted, and different points will be mainly described. The difference lies in the control circuit that operates the first and second stems 9 and 10 of the fixed type A.
6, the vent holes 15, 16, 23; 17, 18,
Vent pipes 29, 30, 31 with one end connected to 24; 33, 34,
The other end of 35 is directly connected to the first, second, third, fourth, fifth and sixth switching valves 51, 5
It communicates with the air supply 45 or the atmosphere via 2, 53, 54, 55, 56. And these switching valves 51, 52, 5
3, 54, 55, and 56 are the first, second, third, fourth, fifth, and sixth timers.
1, 62, 63, 64, and 65, these timers 61, 6
2, 63, 64, 65 are connected to the injection molding machine 46 via a control member 69. After the secondary injection in the first and second multilayer molding parts 1 and 2, there are first and second sensors 71 and 72, which are ultraviolet or infrared sensors for detecting the positions of the front and rear ends of the product sample and the resin distribution. First and second detection members 73 and 74 are provided, and these are connected to the control member 69.

In FIG. 5, when the first stem 9 of the first multilayer molding unit 1 is moved to the intermediate position for injecting the first resin a by the operation of the timers 61 to 63, the timer is set in the second multilayer molding unit 2. The operation of steps 64 to 66 causes the second stem 10 to be in the fully closed position, and FIG.
The first stem 9 of the multilayer molded part 1 is in the fully open position, and has shifted to the secondary injection with all the resins a, b, and c. In the second multilayer molded part 2, the second stem 10 is at the intermediate position. Indicates that the primary injection for injecting the first resin a is continued. In this case, the operation start of the timers 61 to 63; 64 to 66 is carried out by the injection signal of the injection molding machine 46, and the time set there is determined by the signals from the first and second detection members 73 and 74 obtained from the product samples. Is determined by the control signal output from the control member 69 based on the control signal. In this embodiment, the operation of the stems 9 and 10 is performed by an electric solenoid valve. Alternatively, the operation may be performed manually or by mechanical means. However, the number of peripheral resin passages may be one or three or more.

[0015]

The present invention is as described above, and a fluid circuit for operating a fluid cylinder for bringing a stem to a fully closed position, a fully open position, and an intermediate position thereof is provided for each multilayer molded part. A control means is provided for each fluid circuit, the operation of the timer is started by the injection signal of the injection molding machine, and the control signal output from the control member based on the signal from the first and second detection members obtained from the product sample Thus, the time of each timer is determined, so that there is an effect that a plurality of good and uniform multilayer molded products can be efficiently formed by an easy operation.

[Brief description of the drawings]

FIG. 1 is a vertical sectional front view of an embodiment of the present invention.

FIG. 2 is a longitudinal sectional front view showing a state in which a stem of a first multilayer molded part is in a fully closed position.

FIG. 3 is a vertical sectional front view showing a state in which the stem is in a fully open position.

FIG. 4 is a vertical sectional front view showing a state where the stem is in an intermediate position.

FIG. 5 is an explanatory diagram showing one operation state of the control circuit of the above.

FIG. 6 is an explanatory view showing another operation state of the above.

FIG. 7 is an explanatory diagram similar to FIG. 5 of a control circuit of a conventional injection molding apparatus of the same type as the present invention.

FIG. 8 is an explanatory view showing a filling state of a resin in a cavity after a primary injection operation according to the above.

FIG. 9 is an explanatory view showing a filling state of a resin in a cavity after the secondary injection operation.

FIG. 10 is an explanatory view showing a filling state of a resin in a cavity after the third injection operation.

FIG. 11 is an explanatory diagram showing a state of filling the resin in the cavity after the end of the injection work.

[Explanation of symbols]

 A Fixed mold B Movable mold 1 First multilayer molded part 2 Second multilayer molded part 3 First outlet 4 Second outlet 5 First central resin passage 6 Second central resin passage 7 First peripheral resin passage 8 Second peripheral resin passage 9 First stem 10 Second stem 11,12 First cylinder 13,14 First piston 15-18 Vent hole 19,20 Second cylinder 21,22 Second piston 23,24 Vent hole 25 First cavity 26 Second cavity 29-31 Vent pipe 33-35 Vent pipe 45 Air supply source 46 Injection molding machine 51-56 1st-6th switching valve 61-66 1st-6th timer 69 Control member 73 1st detection member 74 2nd detection member

Continuation of the front page (56) References JP-A-2-67117 (JP, A) JP-A-62-268618 (JP, A) JP-A-61-268421 (JP, A) JP-A-61-206612 (JP, A) , A) JP-A-59-67029 (JP, A) JP-A-52-14660 (JP, A) Fully open 1974-73364 (JP, U) Really open 1975-15566 (JP, U) Really open 52-66780 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) B29C 45/00-45/84

Claims (3)

(57) [Claims] A central resin passage having an outlet at a distal end, at least one peripheral resin passage opening into the resin passage,
A stem disposed movably on the axis thereof in the central resin passage, and a fully closed position where the stem is prevented from communicating with all of the central resin passage and the peripheral resin passage and the outlet;
A plurality of multi-layer molded parts having a fluid cylinder that moves between all of the central resin passage and the peripheral resin passage and a fully open position where communication with the outlet is allowed, and stops at an intermediate position therebetween. In the injection molding die, a fluid circuit for operating the fluid cylinder is provided for each multilayer molding part, and a control means is provided for each of the fluid circuits. 2. The injection mold according to claim 1, wherein the control means has a timer for determining a timing for operating a control valve contributing to supply and discharge of the fluid to each fluid circuit. 3. A detection means for reading a resin distribution of a product sample, wherein the control means receives a signal output from the detection means and sets an operation time of a timer based on the signal. Mold for injection molding.