JPH06102335B2 - Method for heating fiber-reinforced composite material preform - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating method for a lump preform in a fiber reinforced composite material, and more particularly to a heating method capable of uniformly and quickly heating the fiber reinforced composite material throughout. is there.

[0002]

2. Description of the Related Art Composite materials in which reinforcing fibers are uniformly dispersed in a thermosetting or thermoplastic synthetic resin have excellent physical properties (especially tensile strength and impact resistance), It is widely used for various panel materials, outer panel materials, body materials, container materials, etc. according to the thermal characteristics of the. These are handled in the form of a sheet or a block (including a block and a bulk) as a preform before being molded into a final product shape. In the process of obtaining the final product shape from the preform, some heating is performed depending on the type of synthetic resin and the shape of the preform.

By the way, conventionally, a sheet-shaped preform has been widely used because it can be uniformly heated easily and has excellent secondary workability when it is pressed into a product shape. The preform has the following drawbacks. (1) Since the synthetic resin material must be once melted and then extruded onto a glass fiber mat, etc., the manufacturing cost is high. (2) The synthetic resin material is melted into chopped strands, etc. It is possible to extrude into a sheet after kneading,
In this method, the reinforcing fibers are often broken in the kneading step, and the reinforcing effect is reduced. (3) When forming a preform into a product shape (hereinafter sometimes referred to as secondary molding), Since it is necessary to cut the sheet-shaped preform according to the target shape and stack it on the mold according to the target thickness and press-mold it, the molding cost is also high. The demand for what we do is increasing.

[0004]

However, in the case of a preform formed into a block (hereinafter, sometimes referred to as a block material),
It is difficult to heat the preform uniformly to the inside. That is, as a heating method of the preformed body, heating by an infrared heater or an electric heater, hot air, or the like is adopted, but in any case, since it is a method of heating from the outside, the inside of the preformed body is from the outer surface side to the central portion. There is a temperature gradient toward the outside, and the outer peripheral side becomes overheated when the center reaches a predetermined processing temperature. Therefore, for example, in the case of a block material using a thermoplastic resin, the outer peripheral side is excessively softened and fluidized, and in the case of a block material using a thermosetting resin, secondary curing on the outer peripheral side proceeds, and in both cases, secondary workability Is significantly harmed.

Therefore, in order to avoid such a problem,
The rate of temperature rise due to heating must be slowed down as much as possible to minimize the difference in temperature gradient described above, and it takes a long time to raise the temperature to the secondary processing temperature. As a result, not only the productivity of the secondary processed product is significantly lowered, but also the bulk material using the thermosetting resin undergoes secondary curing during this long time and the workability is deteriorated.

The present invention has been made in view of these problems, and the purpose thereof is to uniformly and quickly raise the temperature of the composite material preform in the heating step performed prior to the secondary forming. It is intended to provide a heating method that can be performed.

[0007]

The structure of the heating method according to the present invention, which was able to solve the above-mentioned problems, is such that a non-through hole is formed in a preform, and a heating gas is blown into the non-through hole to carry out the heating. The gist is that the gas is diffused and heated in the preformed body.

[0008]

FUNCTION AND EXAMPLE FIG. 1 is a sectional view showing an example of a heating apparatus used in the present invention. This heating device
It is composed of a tubular casing 1, a gas recovery lid 2 that can move forward and backward in the arrow direction with respect to one opening of the casing 1, and a gas supply lid 3 that can move forward and backward with respect to the other opening. It The gas supply lid 3 has a heating gas supply pipe 3
1 is connected and the supply gas chamber 3A is formed. A gas recovery pipe 23 is connected to the gas recovery lid 2 and a recovery gas chamber 2A is formed. The recovery gas chamber 2A has a perforated plate 22
It is preferable to fractionate into ₁ and 2A ₂ , so that the gas pressure in the recovery gas chamber 2A ₁ can be increased and at the same time the end edge of the gas recovery lid 2 holds down a part of the end face of the preform B. Recommended to keep.

The preform B to be heated by the above heating device is preliminarily formed with a non-through hole B ₁ by using a punching device described later. That is, the non-through hole B ₁ is housed in the casing 1 so that the opening of the non-through hole B ₁ corresponds to the side of the gas supply lid 3, and then the gas supply lid 3 and the gas recovery lid 2 are fitted into both openings of the casing 1 to heat the gas. Gas supply pipe 3
1 through each non-through hole B from the supply gas chamber 3A.
_Install within ₁ . Then, the heating gas introduced into the non-through hole B ₁ is diffused into the preform B, and the gas that has heated the preform B as a whole is collected in the collection gas chambers 2A ₁ and 2A ₂ to collect the gas. It is led to 23. An inert gas such as N ₂ gas or air (when the resin material does not undergo oxidative deterioration) is used as the heating gas.

Since the preform is heated by the heating gas through the non-through hole B ₁ , it can be rapidly heated to the inside and can reach a predetermined temperature in a short time. Since it will be diffused and heated from the inside, the difference in temperature gradient of the preform itself will be small,
It enables uniform heating.

After the heating is completed, the gas supply lid 3 and the gas recovery lid 2 are withdrawn from the casing 1, and the heated preform B is fed to a pressure molding machine or the like in the subsequent step.

(Experimental Example) A lump preform of glass fiber reinforced plastic (diameter 180 mm x length 120 mm) in which polypropylene and chopped glass fiber are mixed is used as 220
The variation in time and temperature required to heat to ℃ was investigated. In the embodiment of the present invention, a non-through hole (diameter 16 mm
X length 110 mm) was used, the comparative example used was one without holes, and the heating device was as shown in FIG.
No. ₂ was used together and N ₂ gas at 230 ° C. was used as a heating gas.

[0013]

[Table 1] As is apparent from Table 1, it was found that the examples of the present invention having the non-through holes can be heated in about half the time compared with the comparative examples, and the variation in temperature can be dramatically improved.

FIG. 3 is a cross-sectional explanatory view showing a punching device for the preform B, in which a pressing lid 15 which can move back and forth is arranged in one opening of the casing 11, and a moving back and forth in the other opening. A free inner lid 12 and a perforating member 13 are provided. The rod-shaped heaters 14, 14, ... Are provided on the preformed body B side of the punching member 13, and the rod-shaped heaters 14, 14 ,.
The preformed body B sandwiched between the pressing lid 15 and the inner lid 12.
The non-through hole is formed by inserting into

The heating temperature of the rod-shaped heater 14 may be set to a temperature not higher than the temperature at which the synthetic resin of the preform B does not melt or soften and adhere, and the rod-shaped heater 14 may preheat the preform B.

After forming the non-through hole B ₁ , the hole forming member 13 is first withdrawn. That is, the heaters 14, 14, ... Are withdrawn while the preform B is supported by the inner lid 12, either the inner lid 12 or the holding lid 15 is retracted, and the preform B is pushed out of the casing 1 by the remaining lid.
By this operation, as shown in FIG. 4, a preform B having a plurality of non-through holes B ₁ and B ₁ can be produced.

FIG. 2 is a cross-sectional explanatory view showing another heating apparatus used in the present invention, in which the gas supply lid 3 is replaced by an inner lid 4 which can be moved forward and backward and a heating nozzle device 5 which can be moved forward and backward. That is, a main body 50 in which a gas chamber 5A is formed is arranged in the inner lid 4 so as to be movable back and forth, a gas supply pipe 53 is connected to the main body 50, and the preformed body is provided on the preformed body side of the main body 50. The nozzle 51 inserted into B is provided in a protruding manner. The nozzle 51 is formed by a hollow pipe, and a large number of nozzle holes 52 are formed in the peripheral wall surface of the nozzle 51. The heating gas supplied from the gas supply pipe 53 is supplied to the gas chamber 5A and the nozzle 5.
It is blown into the preform B through the nozzle hole 52 through the nozzle 1.

The temperature of the heating gas is set to a temperature at which the synthetic resin of the preform is not melted or softened and does not adhere to the nozzle 51, and the nozzle 51 can be extracted from the heated preform without any trouble. When using this heating device, the preform B is stored in the casing in a lump form,
When the hole forming process is performed by the nozzle 51, it is possible to efficiently perform the hole forming process for the preform and then the heating using the same apparatus.

There is no limitation on the kind of synthetic resin material or reinforcing fiber as a material of the composite material to which the present invention is applied, and as the synthetic resin material, a thermosetting resin or a thermoplastic resin may be used depending on the application and required characteristics. It is possible to appropriately select and use from among the above, and as the type of reinforcing fiber, various metal fibers, various whiskers, and the like can be used in addition to the most common glass fiber and carbon fiber. Further, a composite material containing these synthetic resin materials and reinforcing fibers, if necessary, a filler, an antioxidant,
Stabilizers, colorants, plasticizers, antistatic agents, flame retardants and the like may be added.

There is no limitation on the preforming method when preforming and using the composite material as described above, and a conventionally known molding method may be applied as it is or modified appropriately. The following method is illustrated as a typical method. (1) A method in which a synthetic resin powder and short fiber-shaped reinforcing fibers are uniformly mixed in a vapor phase (dry mixing) together with other additives to be blended, if necessary, and filled in a molding die to be compacted. In this case, it is of course effective to use an appropriate binder in order to enhance the moldability and shape retention. It is also possible to improve the shape retention by heating the synthetic resin powder partially in the powder compacting step to partially melt the synthetic resin powder and mutually fuse them. (2) A method in which a synthetic resin powder and short fiber reinforcing fibers are wet mixed with other additives to be mixed as necessary with water as a mixing medium, and the mixture is molded into an arbitrary shape and dried, or a plunger. A method of extrusion-molding into a rod shape using a type extrusion molding device or the like, cutting to an appropriate length, and then drying. Also in this case, if necessary, an appropriate binder may be added to improve moldability and shape retention. (3) A method in which the dry mixture as shown in (1) above is charged into a plunger type extrusion molding device or the like, and the synthetic resin powder is extruded in a partially molten state by heating appropriately in a discharge die part or the like.

There is no limitation on the shape of the preforming, and it may have any shape such as a rectangular shape, a polygonal pillar shape, an elliptic pillar shape, etc. in addition to the short cylinder shape as shown in the drawing. It may be determined according to the shape of the heating device used in the invention.

[0022]

The present invention is constructed as described above, and the whole composite material can be quickly and efficiently heated, and the subsequent secondary molding can be efficiently and smoothly performed. Moreover, since there is no remarkable temperature gradient in the preformed body in this heating step, there is no fear that the preformed body is locally overheated, and due to the partial melting that is often observed when the thermoplastic resin is used. There is no problem such as deterioration of shape retention or progress of partial secondary curing reaction that is often seen when using thermosetting resin, and secondary molded products of uniform and stable quality are produced with good productivity. It can be manufactured.

[Brief description of drawings]

FIG. 1 is a cross-sectional side view showing an example of a heating device used in the present invention.

FIG. 2 is a cross-sectional side view showing another example of the heating device used in the present invention.

FIG. 3 is a cross-sectional side view showing an example of a punching device used in the present invention.

FIG. 4 is a partially cutaway explanatory view of a preform having a non-through hole formed therein.

[Explanation of symbols]

1 Casing 2 Gas recovery lid 3 Gas supply lid B Preform B ₁ Non-through hole

Claims (1)

[Claims] 1. A method for heating a composite material preform in which reinforcing fibers are dispersed in a synthetic resin, wherein a non-through hole is formed in the preform, and a heating gas is blown into the non-through hole to form a non-through hole. A method for heating a fiber-reinforced composite material preform, comprising heating a heating gas by diffusing heated gas into the preform.