CN108407328B

CN108407328B - Hot press molding method of composite material product

Info

Publication number: CN108407328B
Application number: CN201810140803.5A
Authority: CN
Inventors: 张小明
Original assignee: Foshan Shunde Maijin Machinery Manufacturing Co ltd
Current assignee: Zhang Xiaoming
Priority date: 2018-02-11
Filing date: 2018-02-11
Publication date: 2020-04-17
Anticipated expiration: 2038-02-11
Also published as: CN108407328A

Abstract

The invention discloses a hot press molding method of a composite material product, which comprises the following steps: A. when the mold reaches the set temperature, the cloth sticking capsule is placed into the mold set in the mold opening state; B. pre-closing the mold, and enabling the two half molds to be close to each other and enabling the two half molds to have a certain gap; C. b, closing the gap in the step B, and reserving a plurality of air extraction openings; D. vacuumizing, namely pumping air in the mould set and the patch capsule away from the air pumping hole by using a vacuum device; E. closing the mold, and completely closing the two half molds after vacuumizing; F. press molding and curing the product. According to the invention, a pre-mold closing step is added in the hot-press molding process, so that a certain gap is reserved in the mold, then the gap is locally closed, and finally the mold is vacuumized, so that the air in the mold cavity is pumped out, the defects of bubbles or pinholes, glue deficiency and the like generated in the product are effectively avoided, and the effect of stable and reliable product quality is ensured.

Description

Hot press molding method of composite material product

Technical Field

The invention relates to the technical field of hot press molding, in particular to a hot press molding method of a composite material.

Background

The hot press molding of composite material products of glass fiber, carbon fiber and the like mainly refers to the process of hot press molding of composite materials through special dies, tools and machines, such as helmets, sport protectors, traveling cases, automobile parts, spacecraft parts, mobile phone back shells and the like. The hot press forming process mainly comprises the steps of applying a certain pressure (the pressure can be a certain value, and can also give a plurality of fixed values at different times or stages according to process requirements), a certain temperature (the temperature can be a certain value, and can also give different fixed values at different times or stages according to process requirements), and keeping for a certain time to obtain a desired product. Because the cavity of the mold is often sealed in the hot-press molding process, air in the mold or materials is not easy to exhaust, so that the product has defects, and therefore, the extraction of the air in the mold cavity is the key of the hot-press molding process of the composite materials such as glass fiber, carbon fiber and the like.

The method of the existing composite material products (such as helmet shells) of glass fiber, carbon fiber and the like in the hot press molding process is as follows: sticking the prepreg on a cloth sticking capsule (the outer side of the capsule), placing the cloth sticking capsule into a die cavity, closing the die (the molding surfaces of the die components are overlapped), pressing the capsule (in a contraction state at the moment) to descend into the cloth sticking capsule, sealing the upper plane of the die, injecting pressure air into the pressing capsule to perform hot press molding and shaping on a product, and simultaneously exhausting the air in the die cavity; because the parting surfaces of the molds are overlapped, the air groove for exhausting air is positioned on the upper plane of the mold (the position of the waste edge of the neck of the helmet shell), the gaps between the cloth-attached capsule and the pre-impregnated cloth and the inner wall of the mold cavity are small, the air exhausting of the upper part is relatively easy, the middle and lower parts are difficult to exhaust, the upper part of the mold is the helmet neck (the waste edge of the helmet product is removed finally), and the part which is easy to store air is positioned on the middle and lower parts of the mold (the top and the ear part of the. Therefore, the existing air pumping method has poor effect, so that the product is easy to generate air bubbles or pinholes, rubber shortage and other defects, and the product quality is influenced.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: the hot forming method overcomes the defects of the prior art, can comprehensively pump out air in a die cavity in the hot press forming process, effectively avoids the defects of bubbles, pinholes, glue deficiency and the like generated by composite material products, and ensures stable and reliable product quality.

The solution of the invention for solving the technical problem is as follows: a hot press molding method of a composite material product comprises the following steps: A. when the mold reaches the set temperature, the cloth sticking capsule is placed into the mold set in the mold opening state; B. pre-closing the dies, namely, enabling the two half dies to be close to each other and enabling a certain gap to be reserved between parting surfaces of the two half dies; C. b, closing the gap in the step B, and reserving a plurality of air extraction openings; D. vacuumizing, namely pumping air between the inner cavity of the mould set and the patch capsule from the air pumping hole by using a vacuum device; E. closing the mold, and completely closing the two half molds (the parting surfaces are overlapped) after vacuumizing; F. and (4) removing the pressurizing capsule, and directly pressurizing the inside of the cloth sticking capsule to form and solidify the product.

As a further improvement of the above technical solution, in the step a, the patch capsule and the mold are connected by a positioning pin and a positioning pin hole.

As a further improvement of the above technical solution, in the step a, the patch capsule has a flat sealing edge platform.

As a further improvement of the above technical solution, in the step C, gaps in the front, rear and lower directions between the parting surfaces of the two halves of the mold are blocked by using a channel-shaped block, then the upper gap is blocked by pressing the pressing plate on the plane sealing edge of the patch capsule, and a pressurizing and exhausting port is provided in the pressing plate, an air channel is provided on the parting surface of the mold, and the air channel is communicated with the exhausting port.

As a further improvement of the above technical solution, in step D, before the vacuum-pumping, the pressing plate is required to press the planar seal of the patch capsule tightly along the table, so as to keep the gap between the inner cavity of the mold set and the patch capsule completely isolated from the outside, and after the vacuum-pumping is completed, the pressing plate is kept in contact with the sealing rubber pad to be in a sealing state.

As a further improvement of the above technical solution, in the step E, after the mold assembly, the pressing plate presses the planar seal edge of the patch capsule again, so that the mold assembly can be kept completely isolated from the outside in the subsequent work.

As a further improvement of the above technical solution, in the step F, the capsule is not pressurized, and the inside of the patch capsule is directly pressurized, so that the product is molded and cured at a certain temperature and pressure.

The invention has the beneficial effects that: according to the invention, a certain gap is reserved in the die by adding the step of pre-closing the die during the hot-press forming process, then the gap is locally closed, finally the gap between the inner cavity of the die set and the patch capsule is vacuumized, and because the gap is reserved between the die parting surfaces of the die and the air grooves are arranged on the parting surfaces and communicated with the air suction holes, the air between the inner cavity of the die set and the patch capsule (particularly the middle and lower parts of the die cavity, namely the top and the ear parts of the helmet shell) is easily sucked out, and the composite material automatically clings to the surface of the die cavity of the die under the atmospheric pressure due to the vacuum formed between the inner cavity of the die set and the patch capsule, so that the defects of bubbles or pinholes, glue shortage and the like of composite material products are effectively avoided, and the stable and reliable product quality. And compared with the traditional method, the pressure loss is reduced because a pressurizing capsule is eliminated, and the inner cavity of the die set is in a vacuum state, so that the pressure of the product in the inner cavity of the die set is higher than that of the traditional method under the same pressure.

Detailed Description

The conception, the specific structure, and the technical effects produced by the present invention will be clearly and completely described in conjunction with the embodiments below, so that the objects, the features, and the effects of the present invention can be fully understood. It is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments, and those skilled in the art can obtain other embodiments without inventive effort based on the embodiments of the present invention, and all embodiments are within the protection scope of the present invention. In addition, all the coupling/connection relationships mentioned herein do not mean that the components are directly connected, but mean that a better coupling structure can be formed by adding or reducing coupling accessories according to specific implementation conditions. All technical characteristics in the invention can be interactively combined on the premise of not conflicting with each other.

Example 1: a hot press molding method of a composite material product comprises the following steps: A. when the mold reaches the set temperature, the cloth sticking capsule is placed into the mold set in the mold opening state; B. pre-closing the dies, namely, enabling the two half dies to be close to each other and enabling a certain gap to be reserved between parting surfaces of the two half dies; C. b, closing the gap in the step B, and reserving a plurality of air extraction openings; D. vacuumizing, namely pumping air between the mould set and the patch capsule from an air pumping hole by using a vacuum device; E. closing the mold, and completely closing the two half molds (the parting surfaces are overlapped) after vacuumizing; F. and (4) removing the pressurized capsule, directly pressurizing and molding the inside of the cloth sticking capsule, and curing the product.

In the traditional steps, because the vacuumizing is performed after the mould is completely closed, and the air suction opening is arranged at the upper end (the waste edge of the neck) of the mould, because the inner cavity of the mould is a curved surface and the gap between the inner cavity of the mould and the patch capsule is very small after the mould is completely closed, the air in the mould is difficult to be completely sucked away, and particularly, the air is easier to accumulate at the middle lower part (the ear part and the top part of the helmet shell) of the inner cavity of the mould; the invention innovatively moves the vacuumizing step forward, and vacuumizes the mould by utilizing the gap between the air groove on the parting surface and the parting surface under the condition that the parting surface of the mould is not completely closed, so that the air between the inner cavity of the mould set and the patch capsule is easier to be pumped out compared with the traditional method. Under the action of atmospheric pressure, the composite material can be automatically attached to the surface of the mold cavity; and finally, the traditional capsule pressurization is cancelled, and the patch capsule is directly pressurized to form the product. Because a pressurizing capsule is cancelled, the pressure loss is reduced, and the inner cavity of the die set is in a vacuum state, the pressure applied to the product forming process is higher than that applied to the traditional method under the same pressure. Of course, the conventional pressurized capsule structure can be retained, so that the structure of the patch capsule is not improved.

Further preferably, in step a, the patch capsule is connected to the mold through a positioning pin and a positioning pin hole, and the patch capsule has a flat sealing edge platform. Because the cloth pasting capsule can have a certain clearance with the mould after being placed into the mould, the reliable fixation of the cloth pasting capsule needs to be ensured in the later stage when the mould is closed. The patch capsule of the method includes a planar sealing edge for subsequent sealing and for the elimination of pressurized capsules.

When a cloth pasting capsule which is required by cloth pasting is put in, the positioning pin is inserted into the positioning pin hole of the die, and if the left die is fixed, the plane seal of the cloth pasting capsule is positioned on the upper surface of the left die along the table; otherwise, if the right die is fixed, the plane seal of the cloth sticking capsule is positioned on the upper surface of the right die along the table; if the left die and the right die are provided with the moving mechanisms, the positioning pins of the cloth pasting capsule are ensured to be inserted into the positioning pin holes of the dies by hands in the pre-closing process. Note that: before the positioning pin at the other side of the cloth sticking capsule or the positioning pins at the two sides are not inserted into the positioning pin holes of the mold at the other end or the mold at the two ends, the cloth sticking capsule needs to be held by hands from the inner cavity of the cloth sticking capsule, so that the cloth sticking capsule cannot fall off from the mold set or generate obvious deviation due to dead weight.

Further preferably, in the step C, gaps in the front, rear and lower directions of the two half molds are sealed by using a groove-shaped block, then a pressure plate is pressed on a plane sealing edge of the patch capsule to seal the gap above the space between the inner cavity of the mold set and the patch capsule, a pressurizing and exhausting port is arranged in the pressure plate, an air groove is arranged on the parting surface of the mold, and the air groove is communicated with the exhausting port.

When a composite material product such as glass fiber, carbon fiber and the like is subjected to hot press molding (such as a helmet shell hot press molding machine), when the left die is fixed, the right heating assembly drives the right die to move towards the left die along the guide rod to perform die closing movement; on the contrary, when the right die is fixed, the left heating component drives the left die to move towards the right die along the guide rod for die closing; or when the left mold and the right mold can move, the left heating assembly drives the left mold and the right heating assembly drives the right mold to simultaneously move in opposite directions along the guide rod, the left mold and the right mold are both stopped at a position with a distance of 10-20mm between the parting surface of the left mold and the parting surface of the right mold (namely, a gap in the step B is reserved), the positioning pins at the other side (or two sides) of the patch capsule enter the positioning pin holes of the moving mold, and the groove block is utilized to press the outer sealing rubber strip on the moving mold into the groove block, so that the front, the back and the lower part of the mold are in a sealing state; the pressing plate presses the flat surface of the patch capsule on the upper surface of the die set along the table, and the pressurizing and exhausting port is positioned on the upper surface of the pressing plate. When the vacuum pumping is carried out, the air between the inner cavity of the mould group and the patch capsule is pumped away through the air pumping hole, the air groove and the gap between the parting surfaces of the mould group, so that the vacuum is formed in the mould cavity, and the composite material is automatically adhered to the surface of the mould cavity under the action of the atmospheric pressure. And during hot pressing, high-pressure gas is filled into the opening of the cloth sticking capsule, so that the cloth sticking capsule extrudes the composite material to the inner cavity wall of the die set from inside to outside, and the composite material is hot-pressed and molded.

Further as a preferred embodiment, in the step D, before the vacuum-pumping, the pressing plate is required to press the plane sealing edge of the patch capsule, so as to keep the space between the mold set and the patch capsule completely isolated from the outside, and after the vacuum-pumping is completed, the pressing plate is kept in contact with the plane sealing edge of the patch capsule, but is not pressed to facilitate the mold-closing. A pressing plate in a hot-pressing forming machine is used for descending to a plane sealing edge platform of the cloth pasting capsule and pressing the flat sealing edge platform tightly, so that the flat sealing edge platform is in a sealing state, and at the moment, a gap between a cavity of the die set and the cloth pasting capsule is isolated from the atmosphere; after isolation, a vacuum system in the hot-pressing forming machine exhausts air in the left die cavity and the right die cavity to achieve an approximate vacuum state through a vacuum pipeline, a left air exhaust hole of the left die, a left air groove, a right air exhaust hole of the right die, a right air groove, and a gap (10-20mm) between the left die parting surface and the right die parting surface.

In a further preferred embodiment, in the step E, after the mold is closed, the pressure plate presses the sealing rubber gasket again, so that the mold set can be kept completely isolated from the outside in the subsequent work. In a hot-pressing forming machine, a movable die performs die assembly movement towards a fixed die or performs die assembly movement towards a left die and a right die, a parting surface on the left die is superposed with a parting surface on the right die, and a die cavity is closely attached to a parting surface of the left die through a right inner sealing rubber strip to isolate a left air groove and a right air groove. Because the positioning pin matched with the cloth sticking capsule and the die is designed, the cloth sticking capsule is ensured to be matched with the die cavity in the die closing process and cannot deviate.

Further as a preferred embodiment, in the step F, the traditional pressing capsule is eliminated, and the pressing is directly applied to the patch capsule, so that the pressing loss is reduced, and the product is cured and molded at a certain temperature and pressure. The hot-press forming machine pressurizes the inner cavity of the cloth-sticking capsule and the subsequent technological process, so that the composite material such as glass fiber, carbon fiber material and the like stuck on the cloth-sticking capsule is completely stuck and formed with the die cavity and solidified under the condition similar to vacuum.

It is worth noting that: the novel process technology for hot-press molding of the glass fiber and carbon fiber prepreg has requirements on the sticking cloth, when the prepreg is stuck, the sticking cloth process inevitably generates bubble bulges because the plane is converted into a spherical surface, and at the moment, sharp tools (such as scissors and the like) are applied to cut the bulge parts of the prepreg and compact the prepreg to eliminate the air in the bubble bulges.

While the preferred embodiments of the present invention have been illustrated and described, it will be understood by those skilled in the art that the present invention is not limited to the details of the embodiments shown and described, but is capable of numerous equivalents and substitutions without departing from the spirit of the invention as set forth in the claims appended hereto.

Claims

1. A hot press molding method of a composite material product is characterized in that: the method comprises the following steps:

A. when the mold reaches the set temperature, the cloth sticking capsule is placed into the mold set in the mold opening state;

B. pre-closing the mold, namely, enabling the two half molds to approach each other and enabling a certain gap to be reserved between parting surfaces of the two half molds;

C. b, closing the gap in the step B, and reserving a plurality of air extraction openings; an air groove is formed in the parting surface of the mold and communicated with the air suction port;

D. vacuumizing, namely pumping air between the inner cavity of the mould set and the patch capsule from the air pumping hole by using a vacuum device;

E. closing the mold, completely closing the two half molds after vacuumizing, and overlapping parting surfaces;

F. and pressurizing the inside of the cloth sticking capsule to form the product and curing the product.

2. The method of hot press forming a composite article according to claim 1, wherein: in the step A, the cloth pasting capsule is connected with the die through the positioning pin and the positioning pin hole, and the cloth pasting capsule is provided with a plane sealing edge platform.

3. The method of hot press forming a composite article according to claim 2, wherein: in the step C, gaps in the front direction, the rear direction and the lower direction between the parting surfaces of the two half dies are sealed by utilizing the groove-shaped block, then the plane sealing edge table of the cloth sticking capsule is pressed by a pressing plate, the gap above the pressing plate is sealed, and meanwhile, a pressurizing and air exhaust port is arranged in the pressing plate.

4. A method of thermoforming a composite article as claimed in claim 3, characterised in that: in the step D, before vacuumizing, the pressing plate is required to be used for pressing the plane sealing edge platform of the cloth pasting capsule, the space between the inner cavity of the die set and the cloth pasting capsule is kept completely isolated from the outside, and after vacuumizing is completed, the pressing plate is kept in contact with the plane sealing edge platform of the cloth pasting capsule, and the sealing state is kept.

5. The method of hot press forming a composite article according to claim 4, wherein: in the step E, after the die assembly is carried out, the pressing plate presses the plane sealing edge platform of the cloth pasting capsule again, so that the die set can be kept completely isolated from the outside in the subsequent work.

6. The method of hot press forming a composite article according to claim 5, wherein: and step F, pressurizing the inner cavity of the cloth pasting capsule, so that the product is cured and molded at a certain temperature and pressure.