JP2808247B2 - Simultaneous injection molding method and molding machine for multiple molded products with different molding conditions - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method in which a plurality of molds having different molding conditions and a plurality of injection devices are provided in a single mold clamping device, and a plurality of molded articles are shared by using the mold clamping device. And a molding machine at the same time.

[0002]

2. Description of the Related Art As an injection molding method and a molding machine of this kind, a molding method and a molding machine generally called two-color molding are known, and a plurality of parts having different shapes such as a combination toy are formed. It is also applied to simultaneous molding.

An ordinary two-color molding machine has a plurality of metal molds having cavities of different shapes but having a structure related to each other on both sides of a mold clamping center of a rotating plate provided on a fixed plate and a movable plate of a mold clamping device. A plurality of injection devices for injecting material resin for each mold are provided on the machine base, each of the molds being separately mounted. Both of the split molds mounted on the rotary disc are core molds having the same shape, and can be shared by both cavity molds formed by the split mold mounted on the fixed disc.

[0004] The cavity mold is divided into a primary side and a secondary side, and the cavities provided in each are different in shape, depth projection area and the like. Next, the cavity of the molded article is formed. A series of processes such as mold clamping, injection of material resin, and mold opening are both performed at the same time, and after releasing the finished product formed by the secondary mold, the rotary core is rotated to turn the primary core mold into the primary mold. Move to the cavity mold on the secondary side together with the molded product, perform mold clamping again and perform injection molding of the new primary molded product and the finished product by compounding the secondary injection molded product. It is a mechanism to do it.

In the simultaneous molding of a plurality of parts having different shapes,
The core mold and cavity mold of each mold have their own shapes, and a series of processes such as mold clamping, injection of material resin, and mold opening are both performed at the same time. The molded product is released from the mold and is moving to the next molding.

[0006]

In a normal mold clamping device in which the center of the back of the movable plate is pressed by the ram to clamp the mold, the mold clamping force concentrates on the center of the movable plate directly pressed by the ram.
The mold clamping plate receives an injection filling pressure for each mold with the mold clamping center as a fulcrum.

When a plurality of molded products are simultaneously injection-molded by such a mold clamping device, the mold clamping force is set to a pressure which can sufficiently oppose the injection filling pressure for both molds. Is performed under the condition that the injection filling pressures acting on symmetrical positions on both sides of the mold clamping center are the same, and that the movable plate receives the pressure uniformly.

However, the injection filling pressure varies depending on the molding conditions, and the molding conditions vary depending on the projected area of the molded product, the cavity shape, the material resin, and the like. Except for the case of simultaneous molding, it is extremely rare that the molding conditions are the same.In the simultaneous injection molding of molded products with different molding conditions, although the pressure difference is large or small, most of the injections are performed in an imbalanced state. The movable platen is receiving filling pressure.

For this reason, if the difference is large, a remarkable difference also occurs in the moments acting on both sides of the mold clamping plate with the mold clamping center as a fulcrum, and the movable plate is inclined, resulting in a parting of the mold having the larger moment. Although the surface is slightly open, burrs may occur. Such a phenomenon can be avoided by setting the mold clamping force to a large value or, conversely, setting the injection filling pressure to a low value.However, the setting of the mold clamping force is limited by the size of the machine. If is set low,
Since the quality of the molded product is deteriorated, it is difficult to adopt any of them, and when the generation of burrs cannot be prevented, a molding machine having a mold clamping output one class higher will be used.

The present invention has been conceived in order to solve the above-mentioned conventional problems, and an object of the present invention is to change a distance between a mold clamping center and a mold to form a plurality of molds. It is an object of the present invention to provide a new molding method and a new molding machine capable of performing simultaneous injection molding without generating burrs even if there is a difference in injection filling pressure due to a difference in molding conditions of a product.

[0011]

According to the injection molding method of the present invention for the above object, a plurality of molds having different molding conditions depending on a projected area, a cavity shape, a material resin, and the like can be molded by a mold clamping apparatus. In order to simultaneously mold multiple molded products by injecting material resin from multiple injection devices that are individually attached to both sides of the clamping center and arranged for each mold, the above multiple dies are used as a fixed plate of the mold clamping device. It is provided on both movable boards so that the distance between each mold and the mold clamping center can be changed, and each injection device is installed on the machine base so that it can move in the same direction as the mold. The distance between the two dies and the mold clamping center is set relatively for each product, and the mold clamping force is made to correspond to the different injection filling pressure for each mold, thereby ensuring the mold clamping.

In the molding machine of the present invention, dies for a plurality of molded products having different molding conditions depending on the projected area, cavity shape, material resin, etc. are individually mounted on both sides of a mold clamping center of a mold clamping device. In a molding machine that arranges an injection device for each mold and simultaneously injection-molds a plurality of molded products, the plurality of dies can be moved by guide members on both sides of the fixed center of the mold clamping device and the clamping center of the movable plate. And a moving device operated by a motor for each mold is mounted on the fixed platen side or the movable platen side, and the distance between each mold and the mold clamping center can be relatively changed by the moving device. The clamping force is made to correspond to the different injection filling pressure for each mold, and the injection device is mounted on a machine base so as to be movable in the same direction as the mold.

[0013]

[Operation] In the above method, the distance of each mold from the mold clamping center changes by changing the relative positions of the plurality of molds having significantly different injection filling pressures with respect to the mold clamping center. As a fulcrum, the moment acting on the movable platen is balanced, and as long as the material resin is injected and filled into both molds at the changed position at the same time, the imbalance of the moment due to the difference of the injection filling pressure is resolved, and the mold parting The occurrence of burrs due to the opening of the surface is prevented.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS This embodiment shows a case of a rotary molding machine. In the figure, reference numeral 1 denotes a fixed plate installed on a machine base 2; It is provided to move forward and backward. A rotary plate 5 is provided inside the movable plate 3 opposite to the fixed plate 1, and a mold clamping ram 6 is connected to the center of the back of the movable plate 3. An actuator 7 for rotating the turntable 5 by 180 ° is provided in the tip of the mold clamping ram 6.
However, the rotating shaft 8 is connected to the center of the rotating disk 5 and provided.
Although not shown in the figure, the rear part of the mold clamping ram 6 is inserted together with a piston into a mold clamping cylinder fixed to the other stationary platen on the machine base opposed to the stationary platen 1. It has a normal structure in which the movable platen 3 is pressed toward the fixed platen by the applied hydraulic pressure to perform mold clamping.

Reference numerals 9 and 10 denote two sets of dies, which are attached to both sides of the fixed platen 1 and the movable platen 3 of the rotary platen 5 on both sides of the mold clamping center.
The dies 9 and 10 are divided molds in which the core dies 9a and 10a are movable plates and the cavity dies 9b and 10b are fixed plates. These divided dies are provided on the inner surface of the fixed plate 1 and the inner surface of the rotary plate 5. It is movably fitted and held by guide members 11a and 11b which are vertically arranged side by side, and is installed at symmetrical positions on both sides of the mold clamping center.

The core molds 9a and 10a have cores of the same shape and can be shared by both the cavity molds 9b and 10b. The cavities 9b and 10b are divided into a primary side and a secondary side, and the cavities provided therein have different shapes and depth projection areas, but the secondary side alternates with the core molds 9a and 10a together with the primary molded product. To form a cavity for the secondary molded product.

Reference numeral 12 denotes a motor of the moving device for the dies 9, 10, which is installed on both sides of the inner surface of the fixed platen 1. A ball screw shaft 13 is connected to a drive shaft of each motor 12. The ball screw shaft 13 is screwed into a nut member 14 fixed to the outer surface of the cavity molds 9b, 10b and inserted into the mold, and is rotated by the motor 12 so that the molds 9, 10 are closed. Move individually and change the mold distance to the mold clamping center.

Reference numerals 15 and 16 denote machine bases 2 toward the fixed platen 1.
The two injection devices are arranged side by side, and they are a pair of front and rear guide rails 1 laid on the machine in parallel with the fixed platen 1.
A support block 19 on the lower side of the injection cylinder is fitted in a guide groove so as to be movable back and forth on a base block 18 provided with a bottom portion fitted to the base 7 so as to be movable in the lateral direction. The inside of the support block 19 is formed in a cylinder 20 for nozzle touch, into which a piston rod 21 having a rear end fixed and a piston 22 at the end are inserted.

Reference numeral 23 denotes motors for the moving devices of the injection devices 15 and 16, which are installed on both sides of the machine base 2. A ball screw shaft 24 is connected to a drive shaft of each motor 23. The ball screw shaft 24 is screwed to a nut member 25 fixed to the outer surface of each base block 18 and penetrates the base block 18. It moves in the same direction as the dies 9 and 10, and enables nozzle touch at the time of injection molding.

When a plurality of products having different molding conditions are simultaneously molded by the molding machine, the difference between the injection filling pressures in the two sets of dies 9 and 10 used therein is not so large. Even if there is a certain difference between the moments acting on both sides of the mold clamping center of the board 5, if the difference is within an allowable range in which there is no possibility of opening the parting surface of the mold, the two metal members are not changed as before. Simultaneous injection molding is performed with the mold fixed in a symmetrical position, but if the difference is significant,
In order that the moment acting on the movable platen side with the mold clamping center as a fulcrum falls within an allowable range, the position of one mold or both molds 9 and 10 is shifted relative to the mold clamping center so as to be balanced. . This modification may operate one or both of the motors 12 simultaneously or individually, and provide the ball screw shaft 1
3 can be easily performed by driving the rotation.

In the rotary molding machine, if the positions of the two dies 9 and 10 are not symmetrical, the core dies 9a and 10a can be alternately moved by the rotary disk 5 to close the cavities 9b and 10b. Therefore, the positions of the dies 9 and 10 can be changed only at the time of injection molding, and operations such as opening and closing the mold and projecting are performed with the symmetric position as a fixed position. However, in an ordinary molding machine that does not require mold replacement, all steps can be performed with the changed position as a fixed position.

FIG. 3 assumes that two sets of dies 9 and 10 having significantly different injection and filling pressures due to the difference in molding conditions require the primary side die 9 having the smaller injection and filling pressure from the mold clamping center O. while separated by a distance S _1, it illustrates a case where the close as required distance S ₂ in clamping the center O of the die 10 larger. Due to this movement, the distance between the fixed positions A, A of the molds 9, 10 and the mold clamping center O is different as L + S ₁ on the mold 9 side and L−S ₂ on the mold 10 side, and the mold clamping center O is different. As a fulcrum, the moment acting on the movable platen 3 is balanced by the distance difference, and as long as the material resin is injected and filled into the two dies at the changed positions B, B, the imbalance of the moment due to the injection filling pressure difference is This eliminates the occurrence of burrs due to the opening of the parting surface of the mold.

For example, when the injection filling pressure in the primary mold 9 is 2500 kg, the mold 10 side is 6000 kg, and the distance (L) from the mold clamping center O is 40 cm, the difference between the two is 1: 2.4. If the distance of the primary side mold 9 is multiplied by 2.4, the moment is balanced. So the secondary mold 1
The distance (S ₂ ) of 0 may be reduced to 、, and the primary mold 10 may be moved to a distance (S ₁ ) that is 2.4 times the distance. Specifically, the distance L + S ₁ is 48 cm, and L−S
₂ is 20 cm. Of course, it is needless to say that the mold needs to be moved only on one side.

FIG. 4 shows a molding process in the rotary molding machine in order. FIG. 4A shows a state in which the molds 9 and 10 are clamped at a fixed position A to complete the mold closing. Thereafter, the clamps of the dies 9 and 10 are released for injection molding,
By the operation of the motor 12, the molds 9, 1 with respect to the mold clamping center O
Zero relative movement is performed.

When the dies 9 and 10 have been moved to the previously calculated change position B, the dies 9 and 10 are stopped at the positions and fixed by clamps. After the mold is clamped, the injection devices 15 and 16 which have been moved to the change position B in advance and the nozzles are touched for each of the molds, and the material is injected and filled at the same time.
As a result, a primary molded product and a finished product are simultaneously molded as shown in FIG.

After the molding is completed, the clamp is released by removing the mold clamping force, and then the dies 9, 10 are returned to their original fixed positions A by the operation of the motor 12, as shown in FIG. Lock again. Thereafter, as shown in FIG. 5D, the mold is opened, the finished product on the secondary side is protruded and released, and the primary molded product is kept attached to the core mold 9a. After the molded product is projected, the rotary disk 5 is rotated by 180 ° while being clamped at that position, and the core die 9a is moved to the position of the cavity die 10a of the die 10, and the core die 10a Is moved onto the cavity mold 9b of the mold 9. Then, the mold is closed again at that position, and the mold is closed to obtain the state shown in FIG.

[0027]

As described above, according to the present invention, a plurality of molds having different molding conditions are individually mounted on both sides of a mold clamping center of a mold clamping device, and a plurality of molds are provided for each mold. When simultaneously molding a plurality of molded products by injecting material resin from the injection device, the distance between each mold and the mold clamping center can be changed, and the distance between both molds and the mold clamping center , The moment acting on the movable platen is balanced with the mold clamping center as a fulcrum, and the mold clamping force is adjusted to the injection filling pressure that differs for each mold to prevent the occurrence of burrs due to the opening of the parting surface. Accordingly, the molding conditions can be made wider than before, and simultaneous molding of a plurality of molded articles, which has been difficult due to differences in molding conditions, can be performed without lowering the molding quality.

Further, as a molding machine, a plurality of dies are movably held by guide members on both sides of a fixed plate of a conventional mold clamping device and a clamping center of a movable plate, and a mold moving device is fixed to the fixed plate. It is only necessary to install the injection device on the machine base so that it can be moved in the same direction as the mold, so that it does not become particularly complicated, and injection filling of material resin into each mold Also has features such as no need for advanced molding technology.

[Brief description of the drawings]

FIG. 1 is a partially cutaway top view of a molding machine capable of performing a method of simultaneous injection molding of a plurality of molded articles having different molding conditions according to the present invention.

FIG. 2 is a side view of the above injection device.

FIG. 3 is an explanatory diagram showing a comparison between a fixed position and a moving position of a plurality of dies.

FIG. 4 is an explanatory view of a process performed by a rotary molding machine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fixed board 2 Machine stand 3 Movable board 4 Rotating board 6 Ram 9 Primary side mold 10 Secondary side mold 11a Guide member 11b Guide member 12 Motor of moving device 13 Ball screw shaft 14 Nut member 15 Primary side injection Apparatus 16 Secondary side injection device 23 Motor for moving device 30 Primary molded product 31 Finished product

Continuation of front page (56) References JP-A-3-7315 (JP, A) JP-A-2-143820 (JP, A) JP-A-7-156199 (JP, A) JP-A-1-110918 (JP) JP-A-51-76353 (JP, A) JP-A-6-218763 (JP, A) JP-A-6-63989 (JP, A) JP-A-63-100211 (JP, U) (58) Field surveyed (Int. Cl. ⁶ , DB name) B29C 45/00-45/84

Claims (2)

(57) [Claims] 1. A plurality of molds having different molding conditions according to a projection area, a cavity shape, a material resin, etc., are individually mounted on both sides of a mold clamping center of a mold clamping device, and are arranged for each mold. When simultaneously molding a plurality of molded products by injecting material resin from a plurality of injection devices, the plurality of dies are provided movably on both a fixed platen and a movable platen of a mold clamping device, and each mold is The distance between the mold clamping center and the mold clamping center can be changed, and each injection device is installed on the machine base so that it can be moved in the same direction as the mold. A simultaneous injection molding method for a plurality of molded articles having different molding conditions, wherein the mold clamping force is set corresponding to different injection filling pressures for each mold by setting the mold clamping force. 2. A plurality of molds having different molding conditions depending on a projection area, a cavity shape, a material resin, etc., are individually mounted on both sides of a mold clamping center of a mold clamping device, and an injection device is provided for each mold. A molding machine for arranging and molding a plurality of molded articles at the same time, wherein the plurality of dies are movably held by guide members on both sides of a mold clamping center of a fixed plate and a movable plate of a mold clamping device; A moving device operated by a motor for each mold is mounted on the fixed platen side or the movable platen side, and the distance between each mold and the mold clamping center can be relatively changed by the moving device, so that the mold clamping force is changed for each mold. Wherein the injection device is mounted on a machine base such that the injection device can be moved in the same direction as the mold.