JPH10138311A - Injection molding of molded product composed of different kind of material and molding apparatus therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a molded product of high quality composed of a different kind of materials. SOLUTION: For the first time, a first resin material is injected by a first injection unit A by using first injection units (A, B) equipped with at least injection cylinders 7, 7' and the screws 6, 6' rotated and axially driven within the screws 7, 7' and, subsequently, a second resin material is injected by the second injection unit B to obtain a molded product consisting of a different kind of materials. At this time, the injection start period of the second injection unit B is controlled by the position signal of the screw 6 of the first injection unit A.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention uses a first and a second injection unit having at least an injection cylinder and a screw which is driven in the injection cylinder in rotation and axial direction. First, a first resin material is injected into a mold clamped by a first injection unit, and then a second resin material is injected by a second injection unit to obtain a molded article made of a different material. The present invention relates to an injection molding method for a molded article made of a material and a molding apparatus used for performing the method.

[0002]

2. Description of the Related Art In recent years, molded articles using composite materials, for example, molded articles composed of two-color materials, molded articles composed of hard and soft materials, sandwich molded articles, and the like are often seen in order to increase added value. It has become. A method of molding an injection molded product composed of different materials such as a hard material and a soft material has been proposed by the present applicant, for example, in Japanese Patent Application No. Hei 7-264701. According to this method, as shown in FIG. 2, an airbag handle cover of an automobile can be formed from a leg made of, for example, a hard material nylon and a main body made of a soft material elastomer. That is, although not shown in the drawing, the nylon resin and the elastomer are respectively weighed using the first and second injection units as is well known in the art. The mold is clamped as shown in FIG. 2A, and the gates 35, 35 are moved by the first injection unit.
, A primary injection of nylon resin is performed to the extent that the first cavity portions 32 are filled. The primary injected nylon resin is indicated by reference numerals 40,40. Before the nylon resin 40, 40 is solidified, the second injection unit performs the secondary injection of the elastomer through the same gate 35, 35 as the primary injection. The elastomer is filled as shown by reference numerals 45 and 45 in FIG. 2B through the center of the soft nylon resin before solidification. When the injection is continued, the elastomers 45, 45 advance, pierce the melt fronts 41, 41 of the nylon resins 40, 40, reach the second cavity portion 33, and the cavity portion 33 is filled. Secondary injection is performed until the entire cavity 34 is filled at a predetermined pressure. When the movable mold 31 is opened after cooling and solidification, an airbag handle cover made of nylon resin and elastomer is obtained.

[0003] A sandwich molding method for molding a sandwich molded article composed of a surface layer and an inner layer, that is, a skin layer and a core layer, is also known in the art. By injecting the material into the cavity and then injecting the core material from the second injection unit through the same gate, a sandwich molded product composed of the skin layer and the core layer can be obtained.

As described above, in order to mold a molded article made of a different material such as a molded article made of a hard material and a soft material, or a sandwich molded article, the mold is first clamped from the first injection unit. A predetermined amount of the first resin material is injected into the cavity of the mold to fill a predetermined space of the cavity, and then the second resin material is completely discharged from the second injection unit through the same gate. Conventionally, a timer is activated at the same time as the first injection unit starts injection, and when the timer expires to a preset time, a predetermined amount of the first resin is conventionally injected. It is assumed that the material has been filled, and the second injection unit starts injecting the second resin material by the time-up signal.

[0005]

As described above, the conventional injection molding method has no problem since the predetermined amount of the first resin material is filled when the injection speed is constant. However, when the injection speed of the first injection unit changes, there is a disadvantage that the quality of the molded product is reduced. In other words, when the injection speed of the first injection unit changes, the injection start signal of the second injection unit is conventionally set to the time of the first injection unit despite the change of the injection amount even if the injection is performed for the same set time. Due to the up signal, the filling amount of the first resin material changes, and there is a disadvantage that the quality of the molded product is not stable. More specifically, referring to FIG. 2, when the injection speed of the first injection unit is lower than the set speed, the filling amount of the hard nylon resins 40, 40 is small, and the strength of the legs is reduced. On the other hand, if the injection speed is high, the nylon resin 40, 40 fills the space filled with the soft elastomers 45, 45, and an airbag handle cover having a predetermined softness cannot be obtained. As described above, the conventional injection molding method has a drawback that the amount of the first resin material to be initially filled is insufficiently grasped and the quality of the molded product is not constant. Therefore, the present invention can accurately determine the filling amount of the first resin material to be filled first, and can obtain a high-quality molded article of a heterogeneous material. It is an object of the invention to provide an injection molding method and a molding device used for carrying out this method.

[0006]

SUMMARY OF THE INVENTION The above object of the present invention is as follows.
This is achieved by precisely controlling the filling ratio of different materials to be filled in one cavity. That is, the filling amount of the second resin material is naturally determined by the filling amount of the first resin material and the capacity of the cavity.
This is achieved by controlling the filling amount of the resin material.
Thus, in order to achieve the above object, the present invention provides a first and a second injection unit having at least an injection cylinder and a screw adapted to be driven in the injection cylinder in a rotational and axial direction. First, a first resin material is injected into the mold clamped by the first injection unit, and then a second resin material is injected by the second injection unit to be made of a different material. When a molded product is obtained, the filling amount of the first resin material is determined based on the position of the screw of the first injection unit. The invention according to claim 2 uses the first and second injection units each having at least an injection cylinder and a screw that is driven in the injection cylinder in a rotational and axial direction. When injecting the first resin material into the mold clamped by the first injection unit and then injecting the second resin material by the second injection unit to obtain a molded article made of a different material, The injection start of the second injection unit is controlled by a screw position signal of the first injection unit. According to a third aspect of the present invention, there are provided first and second injection units each including at least an injection cylinder, a screw that is driven in the injection cylinder in a rotational and axial direction, and a control device. A molding apparatus for obtaining a molded article made of a heterogeneous material in which the first injection unit first injects the first resin material and then the second injection unit injects the second resin material. Wherein the control device comprises: detecting means for detecting a screw position of the first injection unit; and comparing means for comparing a screw position detected by the detecting means with a set screw position. And the start of injection of the second injection unit is controlled by a comparison signal of the comparison means.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. FIG. 1 is a diagram schematically showing an example in which the present invention is applied to a hydraulic injection molding machine. As shown in FIG. 1, as the injection devices, first and second injection units A and B are used. The first injection unit A measures and injects the first resin material, and the second injection unit B measures and injects the second resin material.
First and second injection units A and B according to the present embodiment
Are substantially the same in structure, the first injection unit A will be described below, and the second injection unit B will be denoted by the same reference numerals with a dash “′” and will not be described repeatedly.

The first injection unit A includes an injection piston / cylinder unit 1 and a plasticizing hydraulic motor 15 as is well known. The injection piston / cylinder unit 1 comprises a cylinder 2 and a piston 3 reciprocally provided in the cylinder 2, and the piston rod 4 is attached to the spline drive shaft 5 and to the tip of the spline drive shaft 5. The screw 6 is fixed. The screw 6 is provided rotatably in the injection cylinder 7 and drivable in the axial direction.

A pressure oil supply pipe 10 is connected to the piston head side of the injection piston / cylinder unit 1. The hydraulic oil supply pipe 10 has an electromagnetic directional switching valve 1.
1 is interposed and connected to the hydraulic pump 12. When the electromagnetic directional control valve 11 is switched to the a position, the pressure oil is supplied to the piston head side and plasticized at the b position. In addition, the piston rod side is connected to the tank by an oil drain pipe 13.

A control device 20 for controlling the electromagnetic directional control valve 11, the hydraulic pump 12, the plasticizing hydraulic motor 15, and the like is provided with setting means for setting the position of the screw 6, that is, the position of the piston 3 of the injection piston / cylinder unit 1. And a comparing means for comparing the position of the screw 6 set by the setting means with the position of the piston 3 measured by the position sensor 21. The position sensor 21 is connected by a signal line 22, and the solenoid of the electromagnetic switching valve 11 is connected by a signal line 23.

The nozzle block to which the first and second injection units A and B are applied is disclosed in Japanese Patent Application No. 7-25572 by the present applicant.
No. 9 can be used, or a conventionally known nozzle block can be used as it is. Therefore, FIG.
Of the injection units A and B of FIG. That is, the first injection hole 52 is formed in the mold 51.
And a second injection hole 53 are provided.
Nos. 2 and 53 are provided with nozzles of the first and second injection units A and B, respectively.

Next, an example of molding a sandwich molded article using the above-described injection molding apparatus will be described. The position of the piston 3 of the first injection unit A is set by the setting means of the control device 20. The setting determines the injection amount of the first resin material. Hereinafter, as is well known in the art, the plasticizing hydraulic motor 15 is activated to measure the skin material by the first injection unit A and the core material by the second injection unit B, respectively.

When the measurement is completed, the electromagnetic directional control valve 11 is switched to the a position by a signal from the control device 20. The pressure oil supplied from the hydraulic pump 12 is supplied from the pressure oil supply pipe 10 to the piston head side of the first injection unit A. The piston 3 is driven in the injection direction, and the skin material is injected from the injection cylinder 7 into the mold cavity via the first injection hole 52. The position of the piston 3 during injection is detected by the position sensor 21 and input to the comparing means of the control device 20. The comparing means compares the detected position with the set position, and when they match, determines that a predetermined amount of the skin material has been filled. The injection is stopped based on this determination. When they match, an injection start signal of the second injection unit B is output,
The electromagnetic direction switching valve 11 'of the second injection unit B switches to the a' position. The pressure oil supplied from the hydraulic pump 12 is supplied from the pressure oil supply pipe 10 'to the piston head side of the second injection unit B. As a result, the core material is similarly discharged from the second injection unit B to the injection cylinder 7 '.
Through the second injection hole 53 into the same cavity. As a result, a sandwich molded product comprising the skin layer and the core layer is obtained as is well known.

As described above, according to the present embodiment, the filling amount of the first resin material is measured by the position of the piston 3 of the first injection unit A, that is, by the position of the screw 6, so that the first Is not affected by the injection speed of the screw 6. Therefore, the amount of the first resin material in the mold cavity is stabilized, and a high-quality molded product can be obtained.

The present invention can be implemented in various forms without being limited to the above embodiment. For example, in the above-described embodiment, the position of the piston 3 of the first injection unit A is detected, but the position of the screw 6 may be directly detected. Also, piston 3
Is in a fixed relationship with the amount of pressure oil supplied to the piston head side of the first injection unit A. Therefore, a flow meter is provided in the pressure oil supply pipe 10, and the flow rate and the flow rate set in the control device 20 are determined. The position of the screw 6 can also be detected by comparing the flow rate measured by the meter. Further, it is apparent that the present invention can be implemented by first and second electric injection units instead of the first and second injection units A and B.

[0016]

As described above, according to the present invention, the first and second injection units each including at least the injection cylinder and the screw which is driven in the injection cylinder in the rotational and axial directions. When a molded article made of a different material is obtained using the method, the filling amount of the first resin material is determined based on the position of the screw of the first injection unit. The judgment is accurate. Therefore, molding control based on this determination is also accurate. According to another aspect of the present invention, first, the first and second injection units each including at least an injection cylinder and a screw that is driven in the injection cylinder in a rotational and axial direction are used. The first resin material is injected into the mold clamped by the first injection unit, and then the second resin material is injected into the second mold.
When the second resin material is injected by the first injection unit to obtain a molded article made of a different material, the start of injection of the second injection unit is controlled by the position signal of the screw of the first injection unit. Therefore, the filling amount of the first resin material is not affected by the injection speed. Therefore, the ratio of the first and second resin materials is stable, and a high-quality molded product can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing a partial cross-section of an embodiment of the present invention.

FIG. 2 is a view showing an example of a molding order of an airbag handle cover made of a different material, in which (a) is a cross-sectional view schematically showing a state after the primary injection, and (b) is a secondary injection. 3 is a cross-sectional view schematically showing the initial stage of FIG. 3, and FIG. 4C is a cross-sectional view schematically showing the state after the secondary injection.

[Explanation of symbols]

Reference Signs List 2 cylinder 3 piston 6 screw 7 injection cylinder 20 control device 21 position sensor (screw position detection means) A first injection unit B second injection unit

Claims (3)

[Claims] At least an injection cylinder (7, 7 ′)
And first and second injection units (A, B) each having a screw (6, 6 ′) adapted to be rotated and axially driven in the injection cylinder. The first resin material is injected into the mold clamped by the first injection unit (A), and then the second resin material is injected by the second injection unit (B) to be made of a different material. When obtaining a molded product, a method of injection molding a molded product made of a different material, wherein a filling amount of the first resin material is determined based on a position of the screw (6) of the first injection unit (A). 2. At least an injection cylinder (7, 7 ′)
And first and second injection units (A, B) each having a screw (6, 6 ′) adapted to be rotated and axially driven in the injection cylinder. The first resin material is injected into the mold clamped by the first injection unit (A), and then the second resin material is injected by the second injection unit (B) to be made of a different material. When a molded product is obtained, the start of injection of the second injection unit (B) is controlled by a position signal of a screw (6) of the first injection unit (A). Injection molding method. 3. At least an injection cylinder (7, 7 ′)
A first and a second injection unit (A, B) including a screw (6, 6 ') adapted to be driven in the injection cylinder in a rotational and axial direction; and a control device (20).
First, the first injection unit (A) is the first injection unit (A).
A molding apparatus for obtaining a molded article made of a different material, wherein the second injection unit (B) injects the second resin material. ) Is detection means (2) for detecting the position of the screw (6) of the first injection unit (A).
1) and comparing means for comparing the position of the screw (6) detected by the detecting means (21) with the set screw position, and the second injection unit (B) starts injection. A molding apparatus for obtaining a molded article made of dissimilar materials, wherein the molding apparatus is controlled by a comparison signal of the comparison means.