CN112721238B - Preparation method of variable-thickness composite material workpiece - Google Patents

Abstract

The invention provides a preparation method of a variable-thickness composite material workpiece, which comprises the following steps of 1: coating a mold release agent on a mold consisting of two pressing modules; step 2: preparing a variable-thickness composite material component and a splicing unit; and step 3: and (3) assembling the composite material member, the splicing unit and the die into a molding press, and adjusting parameters of the molding press for molding. Through the high-efficient utilization to original mould, reduced the waste of experimental fund and time. Compared with the original processing process, the design of the assembling and splicing process before the original workpiece is formed is only needed to be added, compared with the method of manufacturing a new die by consuming a large amount of funds and time, the use of the original die and the isolation film is used, so that concave-convex parts are formed on the special surface of the target workpiece and corresponding parts to be mutually occluded, the male and female die assembling hot press forming can still be performed in the original die, and the availability of the die is greatly improved.

Description

Preparation method of variable-thickness composite material workpiece

Technical Field

The invention belongs to the technical field of composite material forming, and particularly relates to a preparation method of a variable-thickness composite material workpiece.

Background

In the process of manufacturing various workpieces made of composite materials, factors such as processing technology, a mould, forming conditions and the like often cause certain difficulty in processing variable-thickness workpieces, the workpieces manufactured by consuming a large amount of manpower, funds and time are difficult to avoid phenomena such as material layering, poor glue, splitting and the like, the strength, rigidity and stability of composite workpieces are reduced in different ranges due to manufacturing defects, and the influence on unidirectional fiber workpieces is particularly serious. For special processing surfaces, the traditional modes include two major types, one is to increase the capital investment and manufacture more complex dies, so that the defects of simple dies on manufacturing composite workpieces are overcome, the processing requirements are met, and the purpose of integral forming is achieved. The second category is to solve the difficult-to-machine parts in a specific molding process by optimizing the design. The traditional solutions are undoubtedly a huge expenditure of money and time for the project.

Disclosure of Invention

In view of the above problems, the present invention provides a method for manufacturing a workpiece made of a variable thickness composite material. The method is based on the existing die, can be used for producing various composite material workpieces with variable thickness surfaces, expands the application range of the die, and is particularly suitable for the conditions of frequent change and tight cycle in the development stage. The specific scheme is as follows: the single fixed die based on compression molding comprises two pressing modules, a pressing space is formed after the pressing modules are assembled and used for placing a workpiece to be pressed, and the workpiece body is matched with the pressing space in the whole shape formed by the splicing units. Comprises the following steps of (a) preparing a solution,

step 1: coating a mold release agent on a mold consisting of two pressing modules;

step 2: preparing a variable-thickness composite material component and a splicing unit;

and step 3: and (3) assembling the composite material member, the splicing unit and the die into a molding press, and adjusting the parameters of the molding press for molding.

Further, uniformly coating a release agent in the mold, uniformly coating, and performing next coating after completely air-drying for 5 times in total.

Further, in the step 2, a thermoplastic composite material sheet is adopted, the sheet is cut into thin strip-shaped raw materials, multilayer layering is carried out, an original workpiece matched with the die space is formed, and the original workpiece is cut into variable-thickness workpiece units (workpieces) and spliced workpiece units.

Further, marking the required cutting positions of different layers by using a marker.

Further, after the contact surface of the variable-thickness workpiece and the splicing unit is paved, an isolation film is paved, and then the variable-thickness workpiece and the splicing unit are placed into a die.

Further, the operation within the molding press includes several stages:

1) Adjusting the target temperature of 108 ℃ in the first stage of the molding press, heating for 40 minutes, starting heating until the temperature rises to 108 ℃, and controlling and stopping the equipment to preserve heat for 20 minutes to ensure that the temperature in the mold is transferred uniformly; after heat preservation, the temperature is quickly adjusted to 140 ℃, the temperature is preserved for 30 minutes, and secondary preheating is carried out to ensure that the material is fully heated, so as to prepare for exhaust work.

2) And (4) exhausting, namely after the heat preservation curve is completely applied, continuously pressing the die at 3MPa according to a die press with preset parameters, and repeating for 4-6 times to remove bubbles existing in the material.

3) Forming, namely continuously heating to 195 ℃ according to a preset third-stage curve after exhausting, preserving heat for 30 minutes, and adjusting the heating process to 1 hour; and pressing with a molding press at 6MPa, maintaining the pressure, cutting off a temperature power supply after the preset three stages are completed, cooling to room temperature, opening the mold, and demolding. And (4) polishing the surface of the workpiece to remove redundant resin and smooth the surface.

Furthermore, a mold surface is coated with a release agent, and an isolation film is arranged between the splicing unit and the workpiece.

Further, the layering mode is

[0/0/90/0/0] _5s 、[0/0/90/0/0] _5s 、[0/0/90/0/0] _5s 、[0/0/90/0/0] _5s 、[0/0/90/0/0] _5s

The method completes the processing of the special surface by assembling and splicing the composite material parts and further integrally forming, solves the problems in the traditional forming process, namely time prolonging and cost sharp increase caused by the fact that the original processing die and processing conditions are changed to complete the processing means of the special surface. The preparation work of the special surface is completed by using materials such as an isolating membrane and the like and pre-installing the concave-convex part raw material, so that the development period is greatly shortened, and the efficiency is greatly improved. In the manufacturing process, waste of test fund and time is reduced by efficiently utilizing the original mold. Compared with the original processing process, the method has the advantages that the original mold is utilized, a large amount of funds and time are consumed to manufacture a new mold, the method of adding the isolation film to the original mold is used, so that the concave-convex parts are formed on the special surface of the target part and the corresponding parts and are mutually occluded, the female and male mold closing hot press forming can still be carried out in the original mold, and the mold availability is greatly improved.

Drawings

FIG. 1 is a schematic view of a female mold structure of one embodiment of the mold of the present invention;

FIG. 2 is a schematic view of a male mold of one embodiment of the mold of the present invention;

FIG. 3 is a schematic view of the position of a workpiece and a splice produced using the mold of the present invention;

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

Referring to fig. 1-3, the invention provides a method for preparing a variable thickness composite material workpiece, which is based on a single fixed die for compression molding, wherein the die comprises a female die and a male die, the two pressing modules form a pressing space for placing the workpiece to be pressed after being assembled, and the overall shape formed by the workpiece body and a plurality of splicing units is matched with the pressing space. Comprises the following steps of (a) carrying out,

step 1: coating a mold release agent on a mold consisting of two pressing modules; and (3) uniformly coating a release agent in the mold, uniformly coating, completely drying in the air, and then coating for the next time, wherein the total time is 5 times.

Step 2: preparing a variable-thickness composite material component and a splicing unit; the method comprises the steps of cutting a sheet material into thin strip-shaped raw materials by adopting a thermoplastic composite material, layering the raw materials at multiple levels to form an original workpiece matched with the space of the die, and cutting the original workpiece into variable-thickness workpiece units and splicing workpiece units. And marking the position of the required truncation of different layers by using a marking pen. And (3) smearing a release agent on the contact surface of the variable-thickness workpiece and the splicing unit, paving an isolating film, and then putting the isolating film into a mold.

And step 3: and (3) assembling the composite material member, the splicing unit and the die into a molding press, and adjusting parameters of the molding press for molding.

The operation in the molding press comprises the following stages:

1) Adjusting the target temperature of 108 ℃ and the heating time of 40 minutes in the first stage of the molding press, starting heating until the temperature rises to 108 ℃, and controlling and stopping the equipment to preserve heat for 20 minutes to ensure that the temperature in the mold is transferred uniformly; after heat preservation, quickly adjusting the temperature to 140 ℃, preserving the heat for 30 minutes, and carrying out secondary preheating to ensure that the material is fully heated to prepare for exhaust work;

2) Exhausting, namely after the heat preservation curves are completely applied, continuously pressing the die at 3MPa according to a die press with preset parameters, and repeatedly exhausting bubbles existing in the material for 4-6 times;

3) Forming, namely heating to 195 ℃ according to a preset third-stage curve after exhausting, preserving heat for 30 minutes, and adjusting the heating process to 1 hour; pressing with a molding press at 6MPa, maintaining the pressure, and cutting off a temperature power supply after the preset three stages are completed; cooling to room temperature, opening the mold, and demolding. And (4) polishing the surface of the workpiece to remove redundant resin and smooth the surface. The surface of the mold is coated with a release agent, and an isolating film is arranged between the splicing unit and the workpiece.

Referring to fig. 1, the variable thickness workpiece used in this embodiment is a plate spring member having stepped surfaces on both sides, and is manufactured by using a conventional manufacturing mold having an arc-shaped upper end surface, and the model structure is as follows, referring to fig. 2:

step 1: coating a mold release agent on a mold consisting of two pressing modules (a female mold 1 and a male mold 2); and (3) polishing the die by using sand paper, uniformly coating a release agent in the die, uniformly coating, and completely drying in the air, and then coating for the next time for 5 times in total.

Step 2: preparing a variable-thickness composite material component and a splicing unit; the method comprises the steps of cutting a thermoplastic composite material sheet into thin strip-shaped raw materials, layering the raw materials in multiple layers to form an original workpiece matched with the space of the die, and cutting the original workpiece into variable-thickness workpiece units and splicing workpiece units, namely a stepped plate spring workpiece 3 and two convex parts 4 which are spliced with the stepped plate spring workpiece and have convex parts. And marking the position of the required truncation of different layers by using a marking pen. Curing and molding the two convex parts, smearing a release agent on the contact surface of the stepped plate spring workpiece and the splicing unit, paving an isolation film, and finally putting the isolation film into a mold; and paving and pasting an isolation film between the splicing unit and the variable-thickness workpiece, and splicing and assembling.

And step 3: and (3) assembling the stepped plate spring workpiece, the two convex parts and the die into a molding press, and adjusting parameters of the molding press for molding.

The operation in the molding press comprises the following stages:

1) Adjusting the target temperature of 108 ℃ and the heating time of 40 minutes in the first stage of the molding press, starting heating until the temperature rises to 108 ℃, and controlling and stopping the equipment to preserve heat for 20 minutes to ensure that the temperature in the mold is transferred uniformly; and after heat preservation, quickly adjusting the temperature to 140 ℃, preserving the heat for 30 minutes, and carrying out secondary preheating to ensure that the material is fully heated to prepare for exhaust work.

2) And (5) exhausting, namely after the heat preservation curves are completely applied, continuously pressing the mold at 3MPa by a mold press according to preset parameters, and repeating for 4-6 times.

3) Forming, namely heating to 195 ℃ according to a preset third-stage curve after exhausting, preserving heat for 30 minutes, and adjusting the heating process to 1 hour; pressing with a molding press under 6MPa, maintaining the pressure, and cutting off the temperature power supply after the preset three stages are completed; cooling to room temperature, opening the mold, and demolding. And (4) polishing the surface of the workpiece to remove redundant resin and smooth the surface. The surface of the mold is coated with a release agent, and an isolating film is arranged between the splicing unit and the workpiece.

The three-stage curve refers to three different heating and pressurizing stages, wherein the first stage, namely a heat preservation preheating stage, is to firstly heat and preserve heat so as to soften the material and reach the corresponding glass transition temperature of about 108 ℃; the second stage, namely the scheduling stage, is to heat the material to 140 ℃ of pressurizing temperature, apply pressure to exhaust the material after fully heating the material, and eliminate the material defects as much as possible; in the third stage, after all temperature pressurization preparations are carried out in the early stage, the whole material is heated to the molding temperature of 195 ℃, and molding pressure is applied until the finished piece is cooled and demoulded for post-treatment.

As an improvement of the scheme, based on the design mode of the mold, the following paving modes are adopted to be more beneficial to cutting the splicing units and the shape stability of the whole workpiece, and the paving modes are as follows:

[0/0/90/0/0] _5s 、[0/0/90/0/0] _5s 、[0/0/90/0/0] _5s 、[0/0/90/0/0] _5s 、[0/0/90/0/0] _5s

the arrangement of the isolation film is that the whole part is designed to be gradually changed in thickness, namely, the layering design is also gradually changed. For example, if the total ply is 36 layers, 18 layers of complete plies should be provided, the other 18 layers should be cut at two ends of the corresponding strip-shaped expected material to meet the design requirements, and the cut and finished material should be alternately laid in the whole mould. And the addition of the thermosensitive material cloth generally takes out 18-36 layers of all layers at the theoretical center of the whole product, namely 18 layers, trisecting the layers according to the actual length, cutting the layers into 1/3 of the front layer, 1/3 of the middle layer and 1/3 of the rear layer, placing the 1/3 of the middle layer into a mold and the 1-18 layers of the original layers, placing the layers by using the center line of the mold, and horizontally placing the center of gravity of the material corresponding to the center of gravity of the mold. And then, sequentially coating 18-36 layers of all the remaining 2/3 materials by using an isolating film respectively, returning the first 1/3 of the coated materials to the left side of the original paving, placing the second 1/3 of the coated materials to the right side of the original paving, filling the original mould, and finishing the mould, wherein the shape of the mould is almost the same as the shape of the original normal gradient plate raw material paving.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.

Claims (5)

1. The utility model provides a preparation method of thickness-variable combined material work piece, based on compression molding's single fixed mould, the mould include two pressing module, pressing module forms a suppression space after the assembly and is used for placing the work piece of waiting to suppress, its characterized in that: the overall shape formed by the workpiece body and the splicing units is matched with the pressing space; comprises the following steps of (a) carrying out,

step 1: coating a mold release agent on a mold consisting of two pressing modules;

and 2, step: preparing a variable-thickness composite material component and a splicing unit; cutting a thermoplastic composite material sheet into thin strip-shaped raw materials, performing multilayer layering to form an original workpiece matched with the die pressing space, and cutting the original workpiece into a variable-thickness workpiece unit and a splicing workpiece unit;

and 3, step 3: assembling the composite material member, the splicing unit and the die into a molding press, and adjusting parameters of the molding press for molding; the in-mold operation includes the following stages:

1) Adjusting the target temperature of 108 ℃ in the first stage of the molding press, heating for 40 minutes, starting heating until the temperature rises to 108 ℃, and keeping the temperature of the equipment for 20 minutes by controlling and stopping to ensure that the temperature in the mold is transferred uniformly; after heat preservation, adjusting the temperature to 140 ℃, preserving the heat for 30 minutes, and carrying out secondary preheating to ensure that the material is fully heated;

2) Exhausting, namely after the heat preservation curves are completely applied, continuously pressing the die at 3MPa by a die press according to preset parameters, and repeatedly removing bubbles existing in the material for 4-6 times;

3) Forming, namely continuously heating to 195 ℃ after exhausting, preserving the heat for 30 minutes, and adjusting the heating process to 1 hour; pressing with a mould press at 6MPa and maintaining the pressure; cutting off the temperature power supply, cooling to room temperature, opening the mold, and demolding.

2. A method of making a varied thickness composite workpiece as defined in claim 1, wherein: and (3) uniformly coating a release agent in the mold, and coating the mold for the next time after air drying, wherein the total time is 5 times.

3. A method of making a variable thickness composite workpiece as defined in claim 1, wherein: and (3) paving an isolating film on the contact surface of the variable-thickness workpiece and the splicing unit, and then putting the isolating film into a mold.

4. A method of making a varied thickness composite workpiece as defined in claim 1, wherein: the surface of the mold is coated with a release agent, and an isolating film is arranged between the splicing unit and the workpiece.

5. A method of making a varied thickness composite workpiece as defined in claim 3, wherein: the layering mode is as follows:

[0/0/90/0/0]5s、[0/0/90/0/0]5s、[0/0/90/0/0]5s、[0/0/90/0/0]5s、[0/0/90/0/0]5s。

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