Tapered section mold and pultrusion forming method of tapered section and tapered long rod based on the same

Abstract

The present invention relates to a taper section mold and a pultrusion forming method for a taper section and a taper long rod based on the same. The taper section mold includes two half molds that are buckled together to jointly form a conical cavity, and two limit members that are buckled together to jointly form a central hole and an annular hole surrounding the central hole. The central hole and the annular hole are both facing the large end surface of the conical cavity. Wherein, each half mold is provided with a plurality of yarn passing holes and multiple pairs of fixing holes along the axial direction. Each pair of fixing holes corresponds to one yarn passing hole. The yarn passing holes are located on the far mold closing side of the half mold. The arrangement directions of the two fixing holes in each pair of fixing holes are perpendicular to the axial direction and the mold closing direction of the half mold. Each pair of fixing holes gradually approaches the mold closing side of the half mold from the large end surface to the small end surface of the half mold. The present invention can well form the taper section, solves the problem of integral forming of a carbon fiber reinforced composite taper long rod with taper sections at both ends, and ensures the connection strength through the cooperation of the taper section of the taper long rod and the joint.

Description

Technical Field

[0001] The present invention relates to the field of pultrusion molding of carbon fiber reinforced composite materials, and particularly relates to a taper section mold and a pultrusion molding method of a taper section and a taper long rod based on the same. Background Art

[0002] Carbon fiber reinforced composite long rods are mainly used for the skeleton tension in large aircraft. Such long rods are generally cylindrical with a constant cross-section, and the connection method with the joint is mostly glue connection. The strength of the glue affects the bonding area between the two. To ensure the bonding strength between the two, a large bonding area is required. Such joints are mostly metal joints. The large bonding area greatly increases the weight of the entire structure, and the bonding strength does not increase infinitely with the extension of the bonding length. The strength cannot meet the structural requirements, and the variability of the bonding quality of such structures is relatively large. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to overcome the defects of the prior art and provide a taper section mold, which can well form the taper section, solve the problem of integral molding of a carbon fiber reinforced composite taper long rod with taper sections at both ends, and ensure the connection strength through the cooperation of the taper section of the taper long rod and the joint.

[0004] To solve the above technical problem, the technical solution of the present invention is: a taper section mold, including two half molds that are buckled together to jointly form a conical cavity and two limit members that are buckled together to jointly form a central hole and an annular hole surrounding the central hole, and the central hole and the annular hole are both facing the large end face of the conical cavity; wherein,

[0005] Each half mold is provided with a plurality of yarn passing holes and a plurality of pairs of fixing holes along the axial direction. Each pair of fixing holes corresponds to one yarn passing hole. The yarn passing holes are located on the far mold closing side of the half mold. The arrangement directions of the two fixing holes in each pair of fixing holes are perpendicular to the axial direction and the mold closing direction of the half mold, and each pair of fixing holes gradually approaches the mold closing side of the half mold from the large end face to the small end face of the half mold.

[0006] Further, fixing rods are arranged on both sides of the half mold, and the fixing rods extend along the axial direction of the half mold.

[0007] The present invention also provides a pultrusion molding method of a taper section, which is based on the taper section mold. The method includes:

[0008] S1, passing a carbon fiber prepreg tape 1 through each pair of fixing holes and fixing the carbon fiber prepreg tape 1 outside the half mold;

[0009] S2, passing the carbon fiber prepreg tape 2 into the conical cavity from the yarn passing hole, bypassing the corresponding carbon fiber prepreg tape 1, passing out from the large end face of the conical cavity, and then passing through the central hole;

[0010] Or the second carbon fiber prepreg tape passes through the central hole and enters the conical cavity from the large end surface of the conical cavity, bypasses the corresponding carbon fiber prepreg tape one and passes out from the yarn hole;

[0011] S3, the carbon fiber prepreg tape three penetrates the conical cavity and the annular hole simultaneously along the axial direction.

[0012] Furthermore, the two half molds and the two stoppers are firstly passed through by the carbon fiber prepreg tapes and then buckled; wherein,

[0013] The first carbon fiber prepreg tape, the second carbon fiber prepreg tape and the third carbon fiber prepreg tape are collectively referred to as carbon fiber prepreg tapes.

[0014] The present invention also provides a pultrusion method for a tapered long rod, comprising:

[0015] SA, adopts the pultrusion method of the tapered section to pultrude the front tapered section of the tapered long rod;

[0016] SB, using a pulling device to pull the tapered section mold in step SA and the carbon fiber prepreg tape unwound during the pulling process through a drying tunnel three times, and the carbon fiber prepreg tape unwound during the pulling process is three-pultruded into a middle equal-section section of the tapered long rod;

[0017] SC, the rear tapered section of the tapered long rod is pultruded by the tapered section pultrusion method;

[0018] SD, using a pulling device to pull the tapered section mold in step SC through the drying tunnel.

[0019] After adopting the above technical solution, the present invention has the following beneficial effects:

[0020] 1. The tapered section mold of the present invention can form the tapered section well, so that the tapered long rod of the carbon fiber reinforced composite material with tapered sections at both ends can be formed in one piece;

[0021] 2. The present invention cooperates with the central hole and the annular hole so that the carbon fiber prepreg tape 3 is used as a long yarn and gradually dispersed at the edge of the tapered section, and the carbon fiber prepreg tape 2 is used as a broken yarn and stuck in the middle of the tapered section. The broken yarn is protected inside, and the broken yarn and the long yarn are not only glued but also interlaced and wrapped with each other, which greatly improves the mechanical properties of the tapered section and makes up for the defect that the broken yarn itself does not have the high strength of the continuous long yarn. In the process of pulling, the broken yarn can be effectively prevented from falling off;

[0022] 3. The tapered section of the tapered long rod is used for fixed installation with the joint. It is fixed with the joint through the tapered shape, which greatly reduces the size of the connecting part, thereby reducing the weight of the joint, reducing the weight of the aircraft, ensuring a longer flight time, and providing favorable protection for the flight stability of the aircraft. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Schematic structural diagram of the taper section mold of the present invention;

[0024] Figure 2 Schematic structural diagram of the half mold of the present invention;

[0025] Figure 3 Schematic structural diagram of the two limit members of the present invention;

[0026] Figure 4 Schematic structural diagram of the limit member of the present invention;

[0027] Figure 5 Schematic structural diagram of the carbon fiber prepreg tape passing through the taper section mold of the present invention;

[0028] Figure 6 Equipment diagram applied to the pultrusion forming method of the taper long rod of the present invention;

[0029] Figure 7 Schematic structural diagram of the taper long rod of the present invention;

[0030] Figure 8 Schematic structural diagram after the taper long rod is assembled with the metal joint;

[0031] Figure 9 Schematic structural diagram after the equal cross-section structure φ3 carbon fiber composite rod is assembled with the metal joint;

[0032] Figure 10 Assembly drawing of the φ3 carbon fiber composite rod after the tapered part is adhesively bonded to the outside and the metal joint; Detailed implementation manners

[0033] In order to make the content of the present invention be more clearly understood, the following further describes the present invention in detail according to specific embodiments and in conjunction with the accompanying drawings.

[0034] Embodiment 1

[0035] As Figure 1 , 2 , 3, 4, 5 show, a taper section mold includes two half molds 2 that are buckled with each other and jointly form a tapered cavity 1, and two limit members 5 that are buckled with each other and jointly form a central hole 3 and an annular hole 4 surrounding the outside of the central hole 3, and the central hole 3 and the annular hole 4 are both opposite to the large end face of the tapered cavity 1; wherein,

[0036] Each half mold 2 is axially provided with a plurality of yarn passing holes 6 and a plurality of pairs of fixing holes 7. Each pair of fixing holes 7 corresponds to one yarn passing hole 6. The yarn passing holes 6 are located on the far mold closing side of the half mold 2. The arrangement direction of the two fixing holes 7 in each pair of fixing holes 7 is perpendicular to the axial direction and the mold closing direction of the half mold 2. Each pair of fixing holes 7 gradually approaches the mold closing side of the half mold 2 from the large end face to the small end face of the half mold 2.

[0037] In this embodiment, the diameter of the central hole 3 is greater than or equal to the size of the large end face of the conical cavity 1. The wall thickness of the connecting part between the central hole 3 and the annular hole 4 is 2 - 3 mm, and the difference between the outer diameter and the inner diameter of the annular hole 4 is about 1 mm.

[0038] As Figure 5 shown, in this embodiment, the paired fixing holes 7 are used to pass through the spacer bars. The spacer bars are carbon fiber prepreg tapes 10. The yarn passing holes 6 are used for the carbon fiber prepreg tape 20 to pass through. The carbon fiber prepreg tape 20 passing through the yarn passing holes 6 bypasses the corresponding carbon fiber prepreg tape 10. The carbon fiber prepreg tape 10 plays a role in positioning the carbon fiber prepreg tape 20, so that the carbon fiber prepreg tape 20 is shaped in the central part of the conical section. The conical section has a variable cross-section, and during the forming process, the fibers need to be gradually expanded along the axis. The carbon fiber prepreg tape 20 is used to expand the fibers. Each pair of fixing holes 7 gradually increases in the horizontal direction, ensuring that the carbon fiber prepreg tapes 20 bypassing the carbon fiber prepreg tape 10 are parallelly distributed in the conical cavity 1. The specific distribution is determined according to the size and angle of the tapered section of the tapered long rod. The number and positions of the yarn passing holes 6 and the fixing holes 7 need to be calculated according to the size, angle of the tapered section and the specifications of the carbon fiber prepreg tapes used.

[0039] In this embodiment, the distance between the limiting member 5 and the half mold 2 is about 5 mm. The carbon fiber prepreg tape 20 for expansion passes through the central hole 3, and the carbon fiber prepreg tape 30 for forming the equal cross-section section of the tapered long rod passes through the annular hole 4. With such a setting, the carbon fiber prepreg tape 30 serves as a long yarn and is gradually dispersed at the edge part of the conical section, and the carbon fiber prepreg tape 20 serves as a broken yarn and is stuck in the middle part of the conical section. The broken yarn is protected inside. The broken yarn and the long yarn are not only adhesively bonded, but also intertwined and wrapped with each other, greatly improving the mechanical properties of the conical section and making up for the defect that the broken yarn itself does not have the high strength of continuous long yarn. During the pulling process, the falling off of the broken yarn can be effectively avoided.

[0040] As Figure 1 、 2 shown in FIGS. 5, fixing rods 8 are provided on both sides of the half mold 2. The fixing rods 8 extend along the axial direction of the half mold 2. The fixing rods 8 are used to better and more conveniently fix the two ends of the carbon fiber prepreg tape 10 passing through the paired fixing holes 7, so as to ensure that the carbon fiber prepreg tape 10 is in a taut state when the carbon fiber prepreg tape 20 bypasses it.

[0041] Example 2

[0042] As Figure 5 shown, a pultrusion forming method for a taper section, which is based on the taper section mold described in Example 1, the method includes:

[0043] S1, Pass the first carbon fiber prepreg tape 10 through each pair of fixing holes 7, and fix the first carbon fiber prepreg tape 10 outside the half mold 2;

[0044] S2, The second carbon fiber prepreg tape 20 enters the conical cavity 1 from the yarn passing hole 6, bypasses the corresponding first carbon fiber prepreg tape 10, then passes out from the large end face of the conical cavity 1 and then passes through the central hole 3;

[0045] Or the second carbon fiber prepreg tape 20 passes through the central hole 3 and then enters the conical cavity 1 from the large end face of the conical cavity 1, bypasses the corresponding first carbon fiber prepreg tape 10 and then passes out from the yarn passing hole 6;

[0046] S3, The third carbon fiber prepreg tape 30 axially penetrates through the conical cavity 1 and the annular hole 4 simultaneously.

[0047] In this embodiment, both two half molds 2 and two limit members 5 are first passed through by the carbon fiber prepreg tape and then buckled; among them,

[0048] The first carbon fiber prepreg tape 10, the second carbon fiber prepreg tape 20 and the third carbon fiber prepreg tape 30 are collectively referred to as carbon fiber prepreg tape. Such a setting facilitates the process of the carbon fiber prepreg tape passing through the taper section mold.

[0049] Example 3

[0050] As Figure 6 shown, a pultrusion forming method for a taper long rod, includes:

[0051] SA, Use the pultrusion forming method for the taper section described in Example 2 to pultrude the front taper section of the taper long rod;

[0052] SB, Use the traction device to traction the taper section mold in step SA and the third carbon fiber prepreg tape 30 unrolled during the traction process through the baking oven. The third carbon fiber prepreg tape 30 unrolled during the traction process is pultruded into the middle equal cross-section section of the taper long rod; after the middle equal cross-section section is pultruded to the preset length, pause the traction device;

[0053] SC, Use the pultrusion forming method for the taper section described in Example 2 to pultrude the rear taper section of the taper long rod;

[0054] SD, Use the traction device to traction the taper section mold in step SC through the baking oven.

[0055] Figure 7The figure is a schematic structural view of a tapered long rod formed by pultrusion in this embodiment. The diameter D1 of the middle equal cross-section section of the tapered long rod is 3 - 10 mm. The taper of the tapered sections at both ends of the tapered long rod is greater than 0° and less than 90°. The overall length L of the tapered long rod is more than 20 meters.

[0056] Figure 6 The figure is a device diagram applied to the pultrusion method of the tapered long rod in this embodiment. As Figure 6 shown, the tapered section die at the left end is the front die 100, which is used to form the front tapered section. The tapered section die at the right end is the rear die 200, which is used to form the rear tapered section. The yarn unwinding rack 300 is used to unwind the carbon fiber prepreg tape three 30 in the whole process of this embodiment and the carbon fiber prepreg tape two 20 in step SC. The yarn unwinding rack 400 is used to unwind the carbon fiber prepreg tape two 20 in step SA. The traction device 500 is used to traction the front die 100, the carbon fiber prepreg tape in the front die 100 and the carbon fiber prepreg tape two 20 unwound during the traction process through the baking oven. The traction device 600 is used to traction the rear die 200 and the carbon fiber prepreg tape in the rear die 200 through the baking oven.

[0057] In this embodiment, in step SA, the carbon fiber prepreg tape two 20 enters the tapered cavity 1 from the yarn passing hole 6, bypasses the corresponding carbon fiber prepreg tape one 10, and then passes through the large end face of the tapered cavity 1 and then through the central hole 3. In step SC, the carbon fiber prepreg tape two 20 passes through the central hole 3, enters the tapered cavity 1 from the large end face of the tapered cavity 1, bypasses the corresponding carbon fiber prepreg tape one 10, and then exits from the yarn passing hole 6.

[0058] As Figure 5 shown, the carbon fiber prepreg tape three 30 is used as the main body carbon fiber to form the outer edge part of the tapered section of the tapered long rod and the main body part of the tapered long rod, that is, the equal cross-section section. The carbon fiber prepreg tape two 20 is used as the external carbon fiber to form the inside of the tapered section of the tapered long rod. Such a structure can ensure the integrity of the outer edge carbon fiber and the main body carbon fiber part, thereby ensuring better strength of the tapered long rod.

[0059] Figure 8 The figure shows the form after the tapered long rod and the metal joint 700 are assembled in this embodiment; Figure 9As shown in the figure, it is the form after the assembly of the φ3 carbon fiber composite rod with an equal cross-section structure and the metal joint 700. Through comparative tests, this structure is bonded to the metal joint 700 with structural adhesive. As the bonding length increases, the bonding area increases, and thus the bonding strength increases. However, when the bonding length exceeds 300 mm, the trend of the bonding strength increasing with the increase of the bonding area is no longer obvious. When the bonding length is 300 mm, the adhesive layer fails under a tensile force of 3 KN, resulting in the disconnection between the carbon fiber composite rod and the metal joint 700. But if the tapered long rod with tapered sections at both ends in this embodiment is used, when the length of the tapered section is 20 mm, that is, the length of the metal joint 700 is 20 mm, the tapered long rod fails when the tensile force reaches 10 KN. Therefore, the tapered long rod in this embodiment fully utilizes the high-strength advantage of the carbon fiber rod. At the same time, since the length of the metal joint 700 is reduced to 1 / 15, the size of the metal joint of the overall structure is greatly reduced, thereby reducing the weight of the entire structure, increasing the endurance time of the aircraft, and also giving full play to the maximum strength of the carbon fiber composite rod.

[0060] As Figure 10 shown in the figure, a φ3 carbon fiber composite rod with an equal cross-section structure and a tapered part 800 made of carbon fiber prepreg of the same raw material are taken, and then the tapered part 800 is bonded to the φ3 carbon fiber composite rod with structural adhesive, and then assembled into the metal joint 700. Through tensile tests, it is found that the φ3 carbon fiber composite rod and the tapered part 800 are debonded and damaged only when the tensile force is 0.8 KN. This is because this connection form is still a bonding method, and the tensile shear strength of the structural adhesive is about 20 MPa, which is much smaller than the tensile strength of carbon fiber, and tensile failure is likely to occur.

[0061] In summary, the carbon fibers in the tapered section and the equal cross-section section of the carbon fiber reinforced composite tapered long rod made by the method in this embodiment are integrated, and a larger tensile strength can be obtained with a smaller assembly size when cooperating and assembling with the metal joint 700.

[0062] Inspired by the above ideal embodiment based on the present invention, through the above description, relevant staff can completely make various changes and modifications without departing from the technical idea of this invention. The technical scope of this invention is not limited to the content in the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A taper section mold, characterized in that it includes two half molds (2) that are buckled with each other and jointly form a conical cavity (1), and two limit members (5) that are buckled with each other and jointly form a central hole (3) and an annular hole (4) surrounding the outside of the central hole (3). The central hole (3) and the annular hole (4) are both opposite to the large end face of the conical cavity (1); wherein, each half mold (2) is provided with a plurality of yarn passing holes (6) and a plurality of pairs of fixing holes (7) along the axial direction. Each pair of fixing holes (7) corresponds to one yarn passing hole (6). The yarn passing holes (6) are located on the far mold-closing side of the half mold (2). The two fixing holes (7) in each pair of fixing holes (7) are arranged perpendicular to the axial direction and the mold-closing direction of the half mold (2). Each pair of fixing holes (7) gradually approaches the mold-closing side of the half mold (2) from the large end face to the small end face of the half mold (2); the paired fixing holes (7) are used to pass through the carbon fiber prepreg tape one (10), and the yarn passing holes (6) are used for the carbon fiber prepreg tape two (20) to pass through. The carbon fiber prepreg tape two (20) passing through the yarn passing holes (6) bypasses the corresponding carbon fiber prepreg tape one (10). The carbon fiber prepreg tape one (10) plays a role in positioning the carbon fiber prepreg tape two (20), so that the carbon fiber prepreg tape two (20) is shaped in the central part of the taper section.

2. The taper section mold according to claim 1, characterized in that fixing rods (8) are arranged on both sides of the half mold (2), and the fixing rods (8) extend along the axial direction of the half mold (2).

3. A pultrusion forming method for a taper section, characterized in that based on the taper section mold according to claim 1 or 2, the method includes: S1, passing the carbon fiber prepreg tape one (10) through each pair of fixing holes (7) and fixing the carbon fiber prepreg tape one (10) outside the half mold (2); S2, the carbon fiber prepreg tape two (20) enters the conical cavity (1) from the yarn passing holes (6), bypasses the corresponding carbon fiber prepreg tape one (10), and then passes out of the large end face of the conical cavity (1) and then passes through the central hole (3); or the carbon fiber prepreg tape two (20) passes through the central hole (3) and then enters the conical cavity (1) from the large end face of the conical cavity (1), bypasses the corresponding carbon fiber prepreg tape one (10), and then passes out of the yarn passing holes (6); S3, the carbon fiber prepreg tape three (30) axially passes through the conical cavity (1) and the annular hole (4) at the same time.

4. The pultrusion forming method for a taper section according to claim 3, characterized in that both the two half molds (2) and the two limit members (5) are first passed through by the carbon fiber prepreg tape and then buckled.

5. A pultrusion forming method for a taper long rod, characterized in that it includes: SA, using the pultrusion forming method for a taper section according to claim 3 or 4 to pultrude and form the front taper section of the taper long rod; SB, using a traction device to traction the taper section mold in step SA and the carbon fiber prepreg tape three (30) unrolled during the traction process through a baking channel. The carbon fiber prepreg tape three (30) unrolled during the traction process is pultruded into the middle equal cross-section section of the taper long rod; SC, pultrude the rear taper section of the tapered long rod by using the pultrusion method of the taper section described in claim 3 or 4; SD, use a traction device to pull the taper section die in step SC through the drying oven.

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