JPS62220307A - Press molding method for low-viscosity reactive molding material - Google Patents

Abstract

PURPOSE:To enable molding of a beautiful molded article by enabling performance of press molding unitarily by filling out a reactive molding material smooth and reliably, by a method wherein a mold device is made into an enclosed space of shear edge structure, the reactive molding material is gelatinized by acting upon the same and a slide is lowered and pressed in order through a balance supporting device by corresponding to a shrinking quantity of the molding material. CONSTITUTION:A cavity 10 to be formed by a mold device 9 is charged with a predetermined quantity of a one-pack type or two-pack type or three-pack type reactive molding material 11, which is cured by increasing viscosity through reaction when the same is heated, through casting. Then a balance supporting devices 12 like a hydraulic servocylinder are provided in a suspending state on four corners of a head 4 and the descent of a side end part of a slide 5 is controlled by supporting a side end part of a slide 5 in a balanced state. A necessary pressure detecting device 13 is connected with the supporting device 12 and pressure change to be loaded through shrinkage of the material 11 is detected. The material 11 is pressed in order by corresponding to viscosity of the material 11 without pressurizing the mold device 9 excessively by corresponding to a shrinkage quantity based on reaction of the material 11 by lowering the slide 5 in order. The material 11 is press-molded into a desired form by filling the predetermined cavity 10 in proper quantities.

Description

[Detailed Description of the Invention] Prior Art In recent years, automobile parts, computer parts, home appliance parts, etc. have come to be molded using malleable, two-component, three-component reactive molding materials that react when heated. Generally, reaction injection molding of polyurethane with added blowing agents is carried out. but,
One-component, two-component, and three-component reaction molding materials that do not contain a blowing agent, such as nylon reaction injection molding materials, may shrink when heated and react, creating voids inside the product. The surface was prone to sink marks and became uneven.

Therefore, it is known that a liquid reservoir is provided in a part of the mold of a reaction injection molding apparatus to supplement and improve the yield of reaction molding material due to heating reaction, as disclosed in Japanese Patent Application Laid-Open No. 58-20.1627. It is being

Problems to be Solved by the Invention However, with the above-mentioned method of limiting the amount of shrinkage of the reaction molding material, it is very difficult to establish the relationship between the installation positions of the supplementary parts corresponding to the shapes of various molded products, and It is not easy to press in supplementary at to cope with curing, and it is particularly difficult to press in evenly the reactive molding material to be supplemented.

In addition, when press molding is performed in the same way as conventional sheet-form molding materials, the reaction molding material becomes a very low viscosity liquid or a low viscosity liquid, so it is difficult to punch or press into the mold. When the mold was loaded, 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 problems, and includes providing a balance support device such as a hydraulic servo cylinder for balanced support of the slide on the bed of a press machine, and a mold device. Low viscosity reaction molding, in which one-component, two-component, three-component, etc., are reacted and molded into the cavity formed by fitting the mold device so that the required cavity can be formed. Load the material at a predetermined amount, taking into account the amount of shrinkage caused by the reaction.
The slide is balancedly supported by a balance support device at a position where the upper mold of the mold device contacts the reaction molding material and a predetermined pressure is generated, and the mold device is brought to a predetermined temperature to cause the charged reaction molding material to react. The pressure force of the slide is sequentially applied to the equilibrium support device in accordance with the amount of contraction of the reaction molding material due to the reaction, and the equilibrium support device is sequentially lowered according to the amount of contraction of the reaction molding material, thereby reducing the reaction of the reaction molding material. As the viscosity increases, the pressure of the slide is gradually increased, and the reaction molding material is filled into a predetermined cavity and pressed into the desired shape, resulting in press molding without using conventional reaction injection molding methods. Even when the material being supplied is a very low viscosity liquid reaction molding material or a low viscosity liquid reaction molding material, it does not overflow from the mold equipment, and the reaction molding material does not overflow due to thermal reaction. Despite the shrinkage, the reactive molding material can be smoothly and smoothly delivered to the cavity of a given mold device through a balance support device that supports the slide in a balanced manner, especially without replenishing the supply of reactive molding material through a material supply device. To provide a press-molding method for a low-viscosity reactive molding material that can be reliably filled and integrally press-molded, and can be molded into a beautiful molded product without sink marks or unevenness 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.
A slide 5 of the required rigidity is provided in the center surrounded by the upright 3 and the bed 4, and a pressure cylinder 6 fixed to the crown 2 is freely driven by a hydraulic servo pump (not shown) as a hydraulic source. The slide 5 is freely slidable toward the lower bed 4 side. An upper mold 7 and a lower mold 8 are disposed facing each other on the lower surface of the slide 5 and the upper surface of the bed 4, respectively, for press-molding required parts such as automobile parts. Cavity 10 formed by
One-component, two-component, or three-component reactive molding material 1, which is a low-viscosity liquid that reacts, increases viscosity, and hardens when heated.
1 can be injected and loaded into a predetermined port using a material supply device (not shown). The mold device 9 has a peripheral portion formed by fitting an upper mold 7 and a lower mold 8 into a so-called shear edge shape as shown in the figure, and a low viscosity reaction molding material 11 to be loaded into the mold device 9. The reaction molding material 11 can be pressed uniformly with the upper mold 7 without overflowing. Mold assembly′
Although not shown in the drawings, the FL9 is equipped with a steam or electric heating device to heat and control the mold device 9 to a required temperature of 140 to 180° C. to cause a reaction in the reactive molding material 11 to be charged. It turns into a gel and hardens into the desired shape, allowing it to be molded.

In addition, as shown in the figure, a balance support device 12 such as a hydraulic servo cylinder is installed vertically at the four corners of the bed 4 to support the side ends of the slide 5 in a balanced manner so that the slide 5 can be controlled to descend in synchronization. . A required pressure detector I3 is connected to this equilibrium support device 12 to detect the pressure change applied to the equilibrium support device 12 due to contraction of the reaction molding material 11, and the slide 5 is sequentially moved as shown in FIG. The reaction molding material 11 is lowered.
The reaction molding material 11 is molded into a predetermined cavity 10 by successively pressing the mold device 9 corresponding to the viscosity of the reaction molding material 11 without excessively pressurizing the mold device 9 according to the amount of shrinkage caused by the reaction.
This allows press molding into the desired shape with just the right amount of advance notice. For example, if the slide 5 is set to have a constant pressing force, the reaction molding material 1
1 causes a reaction and contracts, a portion of the pressing force of the slide 5 applied to the reaction molding material 11 will be applied to the balance support device 12, and for example, the support of the balance support device 12 will be reduced by several percent. Each time the pressure increases, the balance support device 12
If you control the drop by 0.01 to 0.05 m, it will automatically work even if the conditions such as the type of reaction molding material 11, heating temperature, reaction rate, etc. are different and it is difficult to set the program!
It can be press-formed in accordance with fk. 14 is a position detector such as a linear scale of the balance support device 12.

For example, when the upper mold 7 molded for automobile parts is fitted with the lower mold 8, the amount of shrinkage (for example, 5 to 10%) is estimated in advance from the material supply device into the cavity 10. A predetermined volume of reactive molding material 11 is injected and the mold device 9 is heated. Initially, the upper mold 7 is filled with the reaction molding material 11.
Balance support device 1 is placed at a position where it comes into contact with and generates a predetermined pressure.
2, the slide 5 with a constant predetermined pressure applied thereto is supported for a certain period of time as shown in FIG. 2 to wait for the reaction of the reactive molding material 11.
When the reactive molding material 11 undergoes a reaction and contracts, a portion of the pressing force of the slide 5, which is pressurized at a constant pressure, is applied to the balance support device 12. Each time the support pressure increases, the balance support device is controlled to descend by 0.01 to 0.05 mm. Since the reactive molding material 11 gradually hardens, the pressing force of the slide 5 is increased by program settings, etc., and the reaction molding material 11 is gradually hardened via the balance support device 12 while corresponding to the amount of hardening and shrinkage of the reactive molding material 11. Then, the slide 5 is controlled to descend, and finally, pressure is applied for a certain period of time in a predetermined cavity 10 to press-form the molded product into a desired shape.

In this way, although the low-viscosity liquid reaction molding material is supplied to the press equipment and press-molded, the mold equipment is a sealed space with a shear edge structure, and the reaction molding material is caused to react and gel. In addition, the slide is sequentially lowered via the balance support device in accordance with the amount of shrinkage of the molding material to press the upper mold without applying excessive pressure, so that the reactive molding material overflows from the mold device and spills. It also prevents the reaction molding material from being compressed abnormally and ejecting, and it can reliably fill the desired cavity and press-form it as one piece without causing insufficient capacity of the reaction molding material, producing molded products with a good appearance. It's something you get.

In addition, since the equilibrium support device can detect and respond to changes in support pressure in response to shrinkage of the reactive molding material, it is possible to
Even if program setting is difficult, press molding can be performed automatically, which is preferable.

In addition, as for the method of lowering the slide, since the balance support device can have a small stroke and a small capacity relative to the pressurizing cylinder, it can be lowered even by 0.011 units as described above, and it can be lowered smoothly as shown in Figure 3. The descending speed of the slide can be controlled almost continuously in a curved manner, and the descending speed of the slide can also be set to an appropriate speed gradient depending on the reaction speed, curing speed, etc. of the reaction molding material. Note that press molding can also be performed as a program setting in which the pressing force of the slide is appropriately increased or decreased in accordance with the reaction molding material independently of the speed of equilibrium support.

In the above examples, the reaction molding material was explained as a liquid material itself, but even if the material itself is powder or flake, it becomes a low viscosity liquid in the early stage of the reaction. The same applies to the following.

Furthermore, in the above embodiments, automobile parts were used as molded products, but computer parts, household 11M products, and other products molded by ordinary reaction injection molding methods can also be press-molded in the same manner. It is particularly suitable for large-sized or complicated-shaped objects.

Effects of the Invention As described above, in the present invention, even if a low-viscosity liquid reaction molding material or a reaction molding material that becomes a low-viscosity liquid is supplied to the mold device and press-molded, a low-viscosity liquid reaction molding material is not produced. The slide can be reliably supported in equilibrium by the balance support device without the liquid reaction molding material overflowing from the mold device or ejecting due to abnormal pressure, and even though the reaction molding material shrinks due to reaction. In particular, it is possible to smoothly apply the reaction molding material to a predetermined cavity without installing a supply device for captives, and it can be integrally press-molded, and it is possible to mold a beautiful molded product without voids and without whiskers or unevenness on the outer surface. It is.

[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, 4...Bed, 5...Slide, 9...Mold device, 10...Cavity, 11...
...Reactive molding material, 12...Equilibrium support device. Applicant Kawasaki Oil Industries Co., Ltd. Agent Patent Attorney Kuni Morimoto Figure 1 Figure 2 UL1

Claims (1)

[Claims] (1) A balance support device such as a hydraulic servo cylinder for supporting the slide in a balanced manner is installed on the bed of the press device, and a mold device is installed so that it can be fitted freely to form the required cavity. A low viscosity reaction molding material, such as one-component, two-component, or three-component, which is molded by reaction, is charged into the cavity formed by fitting, and a predetermined amount is charged in consideration of the amount of shrinkage caused by the reaction. The slide is balancedly supported by a balance support device at a position where the upper mold of the mold device contacts the reaction molding material and a predetermined pressure is generated, and the mold device is brought to a predetermined temperature to cause the loaded reaction molding material to react. The pressure of the slide is sequentially applied to the balance support device in accordance with the amount of contraction of the reaction molding material, and the balance support device is sequentially lowered according to the amount of contraction of the reaction molding material. A press-molding method for a low-viscosity reactive molding material, which is characterized by filling a predetermined cavity with the reactive molding material and pressing it into a desired shape by increasing the pressing force of a slide sequentially as the viscosity increases. .