Disclosure of Invention
In order to solve the technical problem that the cooperative pressurization of each step is difficult to ensure in the hard die forming composite material multi-step platform in the prior art, the invention provides a forming die for composite material multi-step platform forming and a manufacturing method thereof, and a composite material multi-step platform and a high-quality forming method thereof.
In order to achieve the above object, the present invention provides in a first aspect a method of manufacturing a molding die for multi-step terrace molding of composite materials, the method comprising the steps of:
(1) providing a multi-step rigid mold made of a high modulus material;
(2) determining the theoretical thickness of each step included in the composite material multi-step platform to be molded, and determining the compression amount of each step according to the theoretical thickness and the actual thickness of each step;
(3) selecting a low-modulus material matched with the compression amount of each step as a replacement material of the high-modulus material on one side of the multi-step hard die, which is attached with the composite material, and determining the thickness of the low-modulus material according to the matching relation between the thickness of the low-modulus material and the modulus of the low-modulus material;
(4) according to the equal thickness replacement principle, determining the replaced thickness of the high modulus material on the side, attached with the composite material, of the multi-step hard mold, and then performing machining on the multi-step hard mold to remove the redundant thickness of the high modulus material on the side, attached with the composite material, of the multi-step hard mold;
(5) the low-modulus material with the corresponding thickness is bonded on the multi-step hard die with the redundant thickness removed through the structural adhesive, so that the high-modulus material is replaced by the low-modulus material on one side, which is attached to the composite material, of the multi-step hard die, and the forming die for forming the composite material multi-step platform is manufactured.
Preferably, the actual thickness of each step is 110% of the theoretical thickness of each step.
Preferably, the matching relationship between the thickness of the low modulus material and the modulus of the low modulus material is as follows:
wherein D is the thickness of the low modulus material, E is the modulus of the low modulus material, σ is the pressure required for curing the composite material, and Δ is the amount of compression on the step of the composite material.
Preferably, the thickness of the structural adhesive is not more than 0.2 mm.
Preferably, the method further comprises smoothing the surface of the low-modulus mold material attached to the composite material, which is included in the molding mold prepared in the step (5).
Preferably, when the forming die is used for forming a composite material multi-step platform with complex working conditions, the thickness of the low-modulus material is increased to one third of the thickness of the forming die.
The present invention provides, in a second aspect, a molding die for multi-step terrace molding of composite materials, which is obtained by the manufacturing method of the invention described in the first aspect.
The invention provides a high-quality forming method of a composite multi-step platform in a third aspect, which comprises the following steps: after the composite material is laid on the forming die for forming the composite material multi-step platform manufactured by the manufacturing method of the first aspect of the invention, the die is closed, and then the composite material multi-step platform is obtained after curing and demoulding.
Preferably, during the closing process of the forming mold, the upper mold and the lower mold of the forming mold are closed tightly, and when the size of a closing seam between the upper mold and the lower mold of the forming mold is close to 0, the compression amount of the low-modulus material included in the forming mold is observed by a feeler gauge to ensure that the low-modulus materials on different steps have approximately equal compression amounts.
In a fourth aspect, the present invention provides a composite multi-step platform formed by the high quality forming method of the third aspect of the present invention.
Compared with the prior art, the invention at least has the following beneficial effects:
(1) the invention provides a novel forming die for forming a composite material multi-step platform and a manufacturing method thereof, the forming die manufactured by the method of the invention is used for forming the composite material multi-step platform, the technical problem that the conventional hard die forming composite material multi-step platform is difficult to ensure the cooperative pressurization of steps can be solved, and the problem of uneven pressurization of composite material workpieces under different height step working conditions can be relieved by the pressure reaction of a gradient modulus material; compared with the traditional method of carrying out hard forming on the composite multi-step platform by adopting a hard die, the method has the outstanding advantages of low cost, high forming quality and the like.
(2) The forming die and the high-quality forming method can improve the qualification rate and the forming quality of the composite material multi-step platform product, and the key technology is as follows: the invention utilizes the design idea of equal thickness and introduces the design of modulus gradient mold, thereby ensuring the uniformity of pressurization of different steps and realizing high-quality reliable molding of a multi-step platform structure.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.
The present invention provides in a first aspect a method of manufacturing a forming die for multi-step platform forming of composite material, the method comprising the steps of:
(1) providing a multi-step hard mold (hard mold) made of a high modulus material (e.g., a hard metal material); in the present invention, as the hard metal material, for example, P20 die steel (hard die steel);
(2) determining the theoretical thickness of each step (each step) included in the composite material multi-step platform to be molded, and determining the compression amount of each step according to the theoretical thickness and the actual thickness of each step; in the present invention, the composite multi-step platform is also denoted as a composite step;
(3) selecting a low-modulus material matched with the compression amount of each step as a replacement material of the high-modulus material on one side of the multi-step hard die, which is attached with the composite material, and determining the thickness of the low-modulus material according to the matching relation between the thickness of the low-modulus material and the modulus of the low-modulus material; in the present invention, the low modulus material may be selected from a non-metal material such as rubber or a soft metal material such as aluminum;
(4) according to the equal thickness replacement principle, determining the replaced thickness of the high modulus material on the side, attached with the composite material, of the multi-step hard mold, and then performing machining on the multi-step hard mold to remove the redundant thickness of the high modulus material on the side, attached with the composite material, of the multi-step hard mold; according to the equal thickness replacement principle, namely the replaced thickness of the high-modulus material at the side, attached with the composite material, of the multi-step hard mold, the redundant thickness of the high-modulus material at the side, attached with the composite material, of the multi-step hard mold needing machining removal and the thickness of the low-modulus material are in equal relation;
(5) bonding a low-modulus material with corresponding thickness on the multi-step hard die with the excessive thickness removed through structural adhesive, so that the high-modulus material is replaced by the low-modulus material on one side, which is close to the composite material, of the multi-step hard die, and thus a forming die (gradient modulus structure forming die) for forming the composite material multi-step platform is prepared; in the invention, the low-modulus material and the high-modulus material of the forming die are reliably connected through structural adhesive (such as J-168 structural adhesive), and finally the forming tool (forming die) with gradient modulus is integrally formed; in the present invention, a high modulus material is also referred to as a high modulus mold material and a low modulus material is also referred to as a low modulus mold material.
The invention provides a manufacturing method of a forming die for forming a composite multi-step platform, which specifically comprises the steps of pressure feedback type low-modulus material selection, equal-thickness design, gradient modulus structure forming die design and manufacturing and the like so as to meet the requirement of high-quality forming of the composite multi-step platform. The forming die manufactured by the method can solve the technical problem that the conventional hard die forming composite material multi-step platform is difficult to ensure the cooperative pressurization of the steps, and can relieve the uneven pressurization problem of the composite material workpiece under the working condition of the steps with different heights by the pressure reaction of the gradient modulus material; compared with the traditional method of carrying out hard forming on the composite multi-step platform by adopting a hard die, the method has the outstanding advantages of low cost, high forming quality and the like. The forming die manufactured by introducing the modulus gradient die design by utilizing the equal thickness design idea can improve the product percent of pass and the forming quality of the composite multi-step platform, ensure the uniformity of pressurization of different steps and realize high-quality reliable forming of a multi-step platform structure.
According to some preferred embodiments, the actual thickness of each step is 110% of the theoretical thickness of each step. In the present invention, the actual thickness of each step varies depending on the amount of prepreg contained in the composite material, and is usually calculated as 110% of the theoretical thickness of each step.
According to some preferred embodiments, the matching relationship between the thickness of the low modulus material and the modulus of the low modulus material is:
where D is the thickness of the low modulus material, E is the modulus of the low modulus material, σ is the pressure required to cure the composite material, and Δ is the compression on the step of the composite material (composite lay-up compression).
According to some preferred embodiments, the thickness of the structural adhesive does not exceed 0.2mm, so that the thickness of the structural adhesive does not influence the thickness of the whole forming die, and the structural adhesive does not influence the stability of the low-modulus die material during curing.
According to some preferred embodiments, the method further comprises smoothing the surface of the low-modulus mold material included in the molding mold prepared in the step (5) and attached to the composite material to ensure the quality of the molding surface of the composite material with the multi-step platform; in the present invention, the smoothing process is performed, for example, by a process such as finish polishing when necessary.
According to some preferred embodiments, when the forming die is used for forming a composite material multi-step platform with complex working conditions, the thickness of the low-modulus material is increased to be one third of the thickness of the forming die so as to eliminate the non-uniformity of the pressure. In the present invention, when the molding die is used to mold a composite material multi-step platform under a complex condition (for example, the composite material multi-step platform appears in a non-main pressure direction) which is unpredictable in size and direction of the clamping pressure, the thickness of the low-modulus die material (for example, 1/3 which is increased to the thickness of the whole die) should be increased as much as possible to eliminate the pressure nonuniformity.
The invention provides, in a second aspect, a forming die for multi-step platform forming of composite materials, which is manufactured by the manufacturing method of the first aspect.
The invention provides a high-quality forming method of a composite multi-step platform in a third aspect, which comprises the following steps:
after the composite material is laid on the forming die for forming the composite material multi-step platform manufactured by the manufacturing method of the first aspect of the invention, the die is closed, and then the composite material multi-step platform is obtained after curing and demoulding. In the invention, the composite material can be the composite material used for forming the multi-step platform.
The invention provides a high-quality forming method of a composite multi-step platform, which solves the high-quality problem of a multi-step platform structure, and is designed and manufactured by a design idea of gradient modulus and equal thickness to obtain a high-quality multi-step platform structure product, and the method specifically comprises pressure feedback type low-modulus material selection, equal thickness design, design and manufacture of a gradient modulus structure forming die and the like. The problem of uneven pressurization of the composite material workpiece under different height step working conditions is relieved by the pressure reaction of the gradient modulus material; compared with the traditional composite material multi-step platform hard forming, the method has the outstanding advantages of low cost, high forming quality and the like. The high-quality forming method provided by the invention utilizes the design idea of equal thickness and introduces the design of a modulus gradient mold, so that the uniformity of different step pressurizing is ensured, the high-quality reliable forming of a multi-step platform structure is realized, and the qualification rate and the forming quality of products can be improved.
According to some preferred embodiments, during the clamping of the forming mold, the compression amount of the low-modulus material included in the forming mold is observed with a feeler gauge to ensure that the low-modulus material on different steps has approximately equal compression amounts.
According to some preferred embodiments, during the clamping process of the forming mold, the upper mold and the lower mold of the forming mold are tightly closed, and when the size of a clamping seam between the upper mold and the lower mold of the forming mold is close to 0, the compression amount of the low-modulus material included in the forming mold is observed by a feeler gauge to ensure that the low-modulus materials on different steps have approximately equal compression amounts. In the invention, when the integral die-closing seam of the forming die is close to 0, the compression amount of the low-modulus material contained in the forming die is observed through the feeler gauge, and according to the matching relation between the composite material layering compression amount (composite material layering compression amount) and the low-modulus material of the forming die, the low-modulus die materials on different steps have approximately equal compression amounts so as to ensure that the pressure on each step is uniform.
According to some specific embodiments, the method for high-quality forming of the composite multi-step platform comprises the following steps:
s1, firstly, the theoretical thickness (theoretical thickness) of each step of the multi-step platform of the composite material is confirmed, the actual thickness is different according to the different amounts of prepreg rubber according to the theoretical thickness and the actual thickness of each step, and a low-modulus mould material matched with the compression amount of the composite material laying is selected according to 110% of the theoretical thickness.
S2, after determining the low-modulus mold material, replacing one side, attached to the composite material, of the multi-step hard mold with the low-modulus mold material (the modulus of the material is lower than that of the high-modulus mold material adopted by the multi-step hard mold) according to the equal thickness; before replacing the high-modulus mold material on the composite material pasting side of the multi-step hard mold with the low-modulus mold material, the thickness of the low-modulus mold material needs to be determined according to the matching relation between the thickness of the low-modulus material and the modulus of the low-modulus material, and the extra thickness of the high-modulus mold material on the composite material pasting side of the multi-step hard mold is removed through machining of the multi-step hard mold.
S3, reliably connecting the low-modulus material with the high-modulus material on the side, attached with the composite material, of the machined multi-step hard mold through structural adhesive to finally integrally form the molding mold with the modulus gradient, wherein the selected structural adhesive is thin (the adhesive thickness is usually not more than 0.2), does not influence the overall thickness, and does not influence the stability of the low-modulus mold material during curing; when the integral die is designed and processed, the surface of the low-modulus die material adhered with the composite material is subjected to smoothing treatment so as to ensure the quality of the molding surface.
S4, performing a normal layering process on the forming die formed in the step S3, wherein the die closing process is to be noticed that the die closing seam of the upper die and the lower die is uniformly reduced until the upper die and the lower die are tightly closed, and then curing and demolding are performed to obtain the composite material multi-step platform; in the actual operation process, when the integral die-closing gap of the die is close to 0, the compression amount of the low-modulus material of the die is observed by a feeler gauge; according to the matching relationship between the composite material layering compression amount and the mold low-modulus material, the low-modulus mold material on different steps is ensured to have approximately equal compression amount so as to meet the requirement of pressure uniformity on each step; for complex conditions with unpredictable mold clamping pressure directions and sizes, the thickness of the low-modulus mold material determined in step S2 should be increased as much as possible (for example, to 1/3 of the total mold thickness) to eliminate pressure non-uniformity.
In a fourth aspect, the present invention provides a composite multi-step platform formed by the high quality forming method of the third aspect of the present invention.
The present invention will be further described with reference to the following examples. These examples are merely illustrative of preferred embodiments of the present invention and the scope of the present invention should not be construed as being limited to these examples.
Example 1
For a composite material step with 2mm height and 4mm high step and 2mm low step, the high-quality forming method comprises the following steps:
firstly, a P20 die steel (hard die steel) machine is adopted to add a hard die.
Determining the compression amount of the composite material step (composite material step): the high step is 4 × 0.1 ═ 0.4, the low step is 2 × 0.1 ═ 0.2, and a high quality molding pressure (curing pressure) of 1MPa is required.
Determining that the replacement material is rubber (low-modulus material), the compression modulus of the replacement material is 7.8MPa, and the matching relation between the thickness of the low-modulus material and the modulus of the low-modulus material is as follows:
determining the thickness of the replacement rubber: the high step is determined to be 3.12mm and the low step is 1.56 mm.
And fourthly, according to the equal thickness replacement principle, determining the replaced thickness of the high-modulus material on the side, attached with the composite material, of the hard mold, performing machining on the hard mold, and removing the redundant thickness of the high-modulus material on the side, attached with the composite material, of the multi-step hard mold, so that the replaced thickness of the high-modulus material on the side, attached with the composite material, of the hard mold is equal to the thickness of the rubber low-modulus material determined in the third step.
Fifthly, firmly bonding rubber with corresponding thickness through J-168 structural adhesive on the side, which is adhered with the composite material, of the hard mold obtained in the step IV and machined, so as to form a complete forming mold.
Sixthly, carrying out a normal composite material layering process on the formed forming die, wherein the die closing process is to pay attention to the fact that a die closing seam of the upper die and the lower die is uniformly reduced until the upper die and the lower die are tightly closed, and then carrying out curing and demolding to obtain the composite material step.
The composite material stepped structure obtained by the embodiment has a smooth surface, does not have surface defects such as rich resin, poor glue and the like, and has good lossless quality, and the step thickness is controlled within +/-0.1.
Finally, the description is as follows: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the embodiments can still be modified, or some technical features can be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the present invention in its spirit and scope.