JPS62220308A - Reactive injection molding method - Google Patents

Abstract

PURPOSE:To enable molding of a beautiful molded article which generates neither a void nor a sink nor unevenness on the outside by enabling press molding by filling a cavity of a mold device with a material integrally, by a method wherein pressurization is applied to a reactive material by lowering a top force stepwise every microscopic quantity in accordance with a shrinkage quantity at the time of cure of the reactive material. CONSTITUTION:A bottom force 10 of a mold device 11 is charged with a predetermined quantity of a one-pack type or two-pack type or three-pack type reactive molding material 12, which is cured by increasing viscosity through reaction when the same is heated, through casting. A mold device 11 so that is formed by fitting the top force 9 in the bottom force 10 in a shear-edge-like state a top force 9 can press the low- viscosity material 12, which has been cast, in an even state without overflowing the mold device 11 by forming the circumference of the same of the top and bottom forces 9, 10. Then as the material 12 is kept shrinking when the same is reacted through heating, a pressurizing cylinder 6 is descended in accordance with a shrinking quantity at the time of cure of the material 12 every fixed hour in accordance with the reaction. Then press control is performed by corresponding to the viscosity of the material 12 by applying a predetermined program to a controller by lowering the top force 9 every microscopic quantity.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a reaction injection molding method, and particularly to a reaction injection molding method in which a molded article is obtained by injecting a low-viscosity liquid reaction molding material into a required cavity of a mold device. Regarding the method.

Conventional technology In recent years, automobile parts, computer parts, home appliance parts, etc. have come to be molded using one-liquid, two-liquid, and three-liquid reaction molding materials, and polyurethane reaction injection molding with added blowing agents is generally used. It is being done. However, with one-component, two-component, and three-component reactive molding materials that do not contain a blowing agent, such as nylon reaction injection molding materials, when heated and reacted, they shrink and create voids inside the product. , the surface was likely to have whiskers and become uneven.

Therefore, it is known that a reaction injection molding apparatus is improved by providing a liquid reservoir in a part of the mold to compensate for the shrinkage of the reaction molding material due to the heating reaction, as disclosed in Japanese Patent Application Laid-Open No. 58-201627. There is.

Problems to be Solved by the Invention However, in the above-mentioned method of compensating for the amount of shrinkage of the reaction molding material, it is very difficult to establish the relationship between the installation positions of the compensation part corresponding to the shapes of various molded products. Does it correspond to hardening? It is not easy to press in the amount of ili Ia, especially? l
! It was difficult to uniformly press-fit the reactive molding material to be filled.

In addition, when performing press molding in the same way as conventional sheet-form molding materials, the reactive molding material is a liquid with very low viscosity, so a punch or upper mold is loaded into the cavity. The reaction molding material overflowed and spilled, and abnormal fluid pressure was generated, which was dangerous.

Means for Solving the Problems The present invention has been made in view of the above-mentioned points, and the mold devices facing each other in the press device are provided so that they can be fitted freely so as to form a required cavity, and the mold devices are A low viscosity liquid reaction molding material, such as one-component, two-component, or three-component, which is molded by reaction, is injected into the cavity to be fitted in a predetermined amount, taking into account the amount of shrinkage, and applied to the reaction molding material. The injected reaction molding material is made to react by heating the mold device to a predetermined temperature, and the slides are sequentially moved in a stepwise manner according to a preset program corresponding to the amount of reaction molding material recovered by the reaction. The pressure of the slide is gradually increased as the viscosity of the reaction molding material increases, and finally the reaction molding material is placed in a predetermined cavity to form the desired shape. Even if the material is press-molded into a shape and press-molded without using conventional reaction injection molding means, it will not overflow from the mold equipment even though the supplied material is a liquid reaction molding material with a very low viscosity. In addition, although the reactive molding material contracts due to thermal reaction, the reactive molding material does not need to be supplied through a material supply device, and can be reacted to the cavity of a predetermined mold device by relatively easy downward control. To provide a reaction injection molding method capable of integrally filling a molding material and press molding, and molding a beautiful molded product without sink marks or irregularities on the void or outer surface.

Example Hereinafter, the present invention will be explained based on examples.

FIGS. 1 and 2 show an embodiment of the present invention. The press device 1 is a hydraulic press with a crown 2 as shown in Fig. 1.
, an upright 3 and a bed 4 surround the slide 5 with the required rigidity. It is slidable toward the bed 4 side at the bottom.

On the lower surface of the slide 5 and the upper surface of the bed 4, an upper mold 9 and a lower mold 10 for press-molding required parts such as automobile parts are disposed facing each other. A predetermined amount of reactive molding material 12, which is a one-component, two-component, three-component, etc., low-viscosity liquid that reacts, increases viscosity, and hardens when heated, is applied to the lower mold lO using a material supply device (not shown). It can be injected and loaded.

The mold device 11 has a peripheral portion formed by fitting an upper mold 9 and a lower mold 10 into a so-called shear edge shape as shown in the figure. The reaction molding material 1 is poured into the upper mold 9 without overflowing.
2 can be pressed evenly. Mold device 11
Although not shown in the figure, the mold device 11 is heated to a required temperature such as 140 to 180° C. by installing a steam or electric heating device to cause a reaction in the injected reactive molding material 12. It turns into a gel and hardens into the desired shape so that it can be molded. Since the reactive molding material I2 gradually shrinks when it undergoes a heating reaction, the pressure cylinder 6 is pressed at predetermined time intervals according to the amount of contraction when the reactive molding material 12 hardens, as shown in FIG. A predetermined program is input into a control device (not shown) to prevent the upper mold 9 from being excessively pressurized. The press is controlled according to the viscosity.

For example, the program setting may be such that the slide 5 is lowered and the upper mold 9 is held at a predetermined height so as to be in contact with the reaction molding material 12 for about several minutes, and the mold apparatus i! 11 to about 140 to 180°C, then lower the slide 5 by 0.1 to 0.31 degrees to lower the upper mold 9, and heat it for about ten seconds or more.
Hold for 1 minute. In this way, the upper mold 9 is sequentially reduced by 0.1 to 0.3 against the reaction shrinkage of the reaction molding material 12.
Pressure is applied as the viscosity of the reaction molding material 12 increases as it descends in increments of about 1 inch, and is press-hardened for a certain period of time in a predetermined cavity 13, thereby press-molding it into a stepped shape. .

For example, when the upper mold 9 molded for automobile parts is fitted into the lower mold 10, a shrinkage amount (for example, 5 to 10%) is estimated in advance from the material supply device into the cavity 13. A predetermined volume of reactive molding material 12 is injected and the mold device 11 is heated. Then, based on the program settings, the slide 5 is lowered to fit the upper mold 9 into the lower mold 10.

At this time, the hydraulic servo pump 8 is controlled according to the program settings as shown in FIG. A reaction occurs and the reaction molding material 12
The collection III! The slide 5 is sequentially lowered by a predetermined amount according to the program of 0.1 to 0.30 as described above according to u, and the upper mold 9 is pressed while responding to the reaction molding material 12 whose viscosity is gradually increasing. The reaction molding material 12 is then pressurized. In this way, the reaction molding material 12 is gradually hardened, and as shown in FIG. ! The descent is controlled in a stepwise manner to reduce lff1, and finally the predetermined cavities 13 are pressurized for a certain period of time to harden the reaction molding material 12 into the desired shape and form the desired molded product. It is press-molded.

In this way, although the low viscosity liquid reaction molding material is supplied to the press equipment and press molding is performed, the mold equipment is used as a sealed space with a shear edge structure, and the upper mold is attached to the low viscosity reaction molding material. Without applying pressure, let the reaction molding material react and increase its viscosity, then lower the slide in a stepwise manner corresponding to the amount of shrinkage of the reaction molding material and react the upper mold. As the molding material shrinks and becomes more viscous, the pressure is applied in response to the viscosity, which prevents the reaction molding material from overflowing from the mold equipment or from being abnormally compressed and ejecting. There is no need for insufficient capacity of the material (it can be reliably filled into the desired cavity and press-molded. Therefore, unlike conventional reaction injection molding, it is necessary to provide a supplementary weir section for the reaction molding material or to use a supplementary device. There is no need for special installation, and it is possible to obtain a good molded product with no voids and no unevenness or sink marks on the outer surface.In particular, in a press machine, the slide is moved every 0.01 to 0.02 m5. It is extremely difficult to control the descent continuously at present, but as mentioned above, it waits for the predetermined amount of shrinkage of the reaction molding material and then descends in steps of 0.1 to 0.31, so it is relatively easy to control. It is extremely practical and can be widely used because the descent control is easy.

Another Embodiment FIG. 3 shows another embodiment of the slide control of the present invention, in which the hydraulic servo pump 8 and pressure control valve 14 are controlled so that no impact is applied to the mold assembly 21i:11 or the reaction molding material. Therefore, the slide 5 can be driven smoothly.

Note that the descending control of the slide 11 can be controlled at an appropriate speed gradient by controlling the hydraulic servo pump 8, etc., and can be set appropriately depending on the reaction speed, curing speed, etc. of the reaction molding material 12. be.

In the above embodiments, automobile parts are used as molded products, but computer parts, home appliances, and other products molded by ordinary reaction injection molding methods can also be press-molded in the same manner. Suitable for large or complicated shapes.

Effects of the Invention As described above, in the present invention, even if a low viscosity liquid reaction molding material is injected into the mold device and press-molded, the low viscosity liquid reaction molding material overflows from the mold device. (Also, despite the reaction molding material shrinking due to reaction, it is possible to fill the specified cavity with relatively easy descending control without installing a supplementary supply device.) It can be filled with a reactive molding material and press-molded integrally, making it possible to mold beautiful molded products with no voids and no whiskers or unevenness on the outer surface.

[Brief explanation of drawings]

FIG. 1 is a partially omitted side sectional view of an apparatus used in an embodiment of the present invention, and FIG. 2 is an explanatory diagram of press adjustment in the above usage example.
FIG. 3 is an explanatory diagram of press adjustment in another usage example same as above. ■... Press device, 5... Slide, 11... Mold device, 12... Reaction molding material, 13... Cavity. Applicant Kawasaki Oil Industries Co., Ltd. Aisin Seiki Co., Ltd. Agent Patent Attorney Kuni Morimoto Figure 1 Figure 2 Time j-

Claims (1)

[Claims] (1) The opposing mold devices of the press device are provided so that they can be fitted freely to form the required cavity, and one-component, two-component, three-component, etc. A predetermined amount of a low-viscosity liquid reaction molding material, which is molded by reaction, was injected in consideration of the amount of shrinkage, and the mold device was heated to a predetermined temperature and the load was applied to the extent that it came into contact with the reaction molding material. The reaction molding material is caused to react, and the slide is lowered step by step in small amounts according to a preset program corresponding to the amount of contraction of the reaction molding material due to the reaction, and the mold device is fitted. A reaction injection molding method characterized by sequentially increasing the pressure of the slide as the viscosity increases, and finally filling a predetermined cavity with the reaction molding material and press-molding it into a desired shape.