A connection structure between a ceramic matrix composite material skin and a workpiece and a connection method thereof

Abstract

The present invention relates to a connection structure between a ceramic-based composite material skin and a workpiece and a connection method thereof, so as to solve the technical problem that the connection method between the skin and the workpiece in the existing ceramic-based composite material skin component cannot effectively apply a pre-tightening force to the edge of the skin, and is prone to opening, warping and deformation under the action of thermal stress. The component includes a workpiece, a skin covering at least part of the surface of the workpiece, and a connecting piece for fastening the skin to the workpiece; the connecting piece includes a countersunk screw and a countersunk nut of a ceramic-based composite material. The connection method includes: 1. The skin covers the surface of the workpiece; 2. The connecting piece connects the skin and the workpiece; 3. CVI deposition is performed.

Description

Technical Field

[0001] The invention relates to a connection structure between a ceramic-based composite material skin and a workpiece, and in particular to a connection structure between a ceramic-based composite material skin and a workpiece and a connection method thereof. Background Art

[0002] Ceramic matrix composites are a new type of thermal structure / functional integrated material that combines the performance advantages of metal materials, ceramic materials and carbon materials. They are resistant to high temperatures, low density, high specific strength, high specific modulus, anti-oxidation, anti-ablation, insensitive to cracks, and do not suffer catastrophic damage. They are widely used in the fields of machinery, aerospace, nuclear, and energy. In the prior art, the ceramic matrix composite skin on the surface of lightweight thermal protection workpieces is connected by composite pins or studs. This connection method cannot effectively apply pre-tightening force to the edge of the skin. If the surface skin of the product is connected by pins or screws, the edge of the skin is prone to opening, warping, deformation, etc. under the action of thermal stress. Summary of the invention

[0003] The purpose of the present invention is to solve the technical problems that the existing connection method between the ceramic-based composite material skin and the workpiece cannot effectively apply pre-tightening force to the skin edge, and is prone to opening, warping and deformation under the action of thermal stress, and proposes a connection structure and a connection method for the ceramic-based composite material skin and the workpiece.

[0004] The technical solution of the present invention is:

[0005] A connection structure of a ceramic matrix composite material skin and a workpiece, the special features of which are:

[0006] It includes a workpiece, a skin covering at least a portion of the surface of the workpiece, and a connecting piece for fastening the skin to the workpiece;

[0007] The connecting piece includes a countersunk screw and a countersunk nut;

[0008] The countersunk screw and the countersunk nut are both made of ceramic-based composite materials;

[0009] The countersunk screw comprises a head and a stem;

[0010] The head is a first cone, the end face of the thick end of the first cone is the first end face, the end face of the thin end of the first cone is integrally connected with the rod, and the diameter of the end face of the thin end is the same as the diameter of the rod;

[0011] The countersunk nut is a second cone having a screw hole matched with the rod, and the rod can pass through the screw hole of the second cone; the thick end face of the second cone and the end face of the rod away from the head constitute the second end face, and the inner side face of the second cone is threadedly connected to the rod.

[0012] Furthermore, the countersunk nut also includes a pressure ring, which is located at the thin end of the second cone and is integrally formed with the second cone. The pressure ring is connected to the thin end of the second cone at one end and has the same diameter as the thin end of the second cone.

[0013] Furthermore, the radial thickness of the pressure ring is 0.5-3 mm, and the axial height of the pressure ring is greater than or equal to 1 mm.

[0014] Further, the workpiece has a first surface and a second surface opposite to each other, and the first surface and the second surface are parallel;

[0015] The skin includes a first skin covering the first surface and a second skin covering the second surface;

[0016] The first end surface is flush with the surface of the first skin, and the first end surface is perpendicular to the length direction of the countersunk screw.

[0017] Further, the workpiece has a first surface and a second surface opposite to each other, and an angle between the first surface and the second surface is α, 0<α≤60°;

[0018] The skin includes a first skin covering the first surface and a second skin covering the second surface;

[0019] The thick end of the first cone is provided with a first extension portion, the first end surface is located at the outer end surface of the first extension portion, and the shape of the first end surface matches the shape of the first surface of the workpiece, and is a slope, a curved surface or a step surface.

[0020] Further, the workpiece has a first surface and a second surface opposite to each other, and the first surface and the second surface are parallel;

[0021] The skin includes a first skin covering the first surface and a second skin covering the second surface;

[0022] The second end surface is flush with the surface of the second skin, and the second end surface is perpendicular to the length direction of the countersunk screw.

[0023] Further, the workpiece has a first surface and a second surface opposite to each other, and the angle between the first surface and the second surface is α, 0<α≤60°;

[0024] The skin includes a first skin covering the first surface and a second skin covering the second surface;

[0025] The thick end of the second cone is provided with a second extension portion, the second end surface is located at the outer end surface of the second extension portion, and the shape of the second end surface matches the shape of the second surface of the workpiece, and is a slope, a curved surface or a step surface.

[0026] Furthermore, the density of the ceramic matrix composite material used in the countersunk screw and countersunk nut is ≥1.85kg / cm 3 .

[0027] At the same time, the present invention provides a method for connecting a ceramic matrix composite material skin and a workpiece, based on the above-mentioned connection structure of the ceramic matrix composite material skin and the workpiece, which is special in that it includes the following steps:

[0028] S1. The skin of the required size is covered on the surface of the workpiece;

[0029] S2. Insert the countersunk screw through the skin and the workpiece, apply a pre-tightening force on the surface of the skin by tightening the countersunk screw, and tighten the countersunk nut to apply a pre-tightening force on the other side of the skin;

[0030] S3. CVI deposition is performed on the workpiece with skin by using CVI process, and the countersunk screws and countersunk nuts are riveted to the skin.

[0031] Further, in step S1, the workpiece has a first surface and a second surface opposite to each other, the angle between the first surface and the second surface is α, 0<α≤60°; the skin includes a first skin covering the first surface and a second skin covering the second surface;

[0032] Before step S3, step S2-3 is also included, in which the first extension portion and the second extension portion are processed so that the first end face formed after the processing of the first extension portion matches the shape of the first surface, and is a slope, a curved surface or a step surface; and the second end face formed after the processing of the second extension portion matches the shape of the second surface, and is a slope, a curved surface or a step surface.

[0033] Beneficial effects of the present invention:

[0034] 1. The connection structure between the ceramic-based composite material skin and the workpiece provided by the present invention applies a pre-tightening force to the surface of the skin covering the surface of the workpiece through countersunk screws and countersunk nuts to prevent the edge of the skin from opening, curling or deformation due to changes in temperature and pressure during use.

[0035] 2. The connector provided by the present invention is not only applicable to workpieces with two parallel opposing surfaces, but also applicable to workpieces with an angle between the opposing surfaces being less than or equal to 60°, and has a wide range of applications.

[0036] 3. The present invention provides a pressure ring on the countersunk nut to prevent the countersunk nut from being crushed when subjected to force, thereby increasing the pressure bearing capacity of the connecting piece and improving the tensile strength of the countersunk nut.

[0037] 4. The connection method of the present invention is simple to operate, has good fastening properties, and has many application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a schematic structural diagram of Embodiment 1 of the connection structure between a ceramic-based composite material skin and a workpiece according to the present invention;

[0039] Figure 2 This is a schematic diagram of the structure of the connecting piece in Example 1 of the connecting structure of the ceramic-based composite material skin and the workpiece of the present invention;

[0040] Figure 3 This is a schematic diagram of the countersunk nut structure in Example 1 of the connection structure between the ceramic-based composite material skin and the workpiece of the present invention;

[0041] Figure 4 This is a schematic structural diagram of Embodiment 2 of the connection structure between a ceramic-based composite material skin and a workpiece according to the present invention;

[0042] Figure 5 This is a schematic diagram of the structure of the connecting piece in Example 2 of the connecting structure of the ceramic-based composite material skin and the workpiece of the present invention;

[0043] Figure 6 This is a schematic diagram of the countersunk nut structure in Example 2 of the connection structure between the ceramic-based composite material skin and the workpiece of the present invention;

[0044] Figure 7 This is a schematic diagram of the connection between the countersunk nut and the countersunk screw in Example 2 of the connection structure between the ceramic-based composite material skin and the workpiece of the present invention.

[0045] The reference numerals are as follows:

[0046] 1-workpiece, 2-skin, 21-first skin, 22-second skin, 3-countersunk screw, 31-head, 32-rod, 4-countersunk nut, 5-pressure ring, 6-first extension part, 7-second extension part. DETAILED DESCRIPTION

[0047] Example 1

[0048] See also Figure 1 and Figure 2 This embodiment provides a connection structure between a ceramic matrix composite material skin and a workpiece, the connection structure comprising a workpiece 1, a skin 2 covering the surface of the workpiece 1, and a connecting piece for fastening the skin 2 to the workpiece 1.

[0049] The connecting piece includes a countersunk screw 3 and a countersunk nut 4; the countersunk screw 3 and the countersunk nut 4 are both made of ceramic-based composite materials. Specifically, the density of the ceramic-based composite materials used in the countersunk screw 3 and the countersunk nut 4 is ≥1.85kg / cm 3 .

[0050] The countersunk screw 3 includes a head 31 and a rod 32; the head 31 is a first cone, the end face of the thick end of the first cone is the first end face, the end face of the thin end of the first cone is integrally connected with the rod 32, and the end face diameter of the thin end is the same as that of the rod 32;

[0051] The countersunk nut 4 is a second cone, which has a screw hole that matches the rod 32, and the rod 32 passes through the screw hole of the second cone; the end face of the thick end of the second cone and the end face of the rod 32 away from the head 31 constitute the second end face, and the inner side face of the thin end of the second cone is threadedly connected to the rod 32.

[0052] Preferably, the countersunk nut 4 also includes a pressure ring 5, which is located at the thin end of the second cone and is integrally formed with the second cone. The pressure ring 5 is connected to the thin end of the second cone at one end, and its diameter is the same as the diameter of the thin end of the second cone. The radial thickness of the pressure ring 5 is 0.5 to 3 mm, and the axial height of the pressure ring 5 is greater than or equal to 1 mm. The thin end edge thickness of the countersunk nut 4 is too small, and it is very easy to collapse under stress. Figure 2 The countersunk nut 4 in the test was tested and the tensile strength was only 35MPa. In order to solve the problem that the thin end surface of the countersunk nut 4 is easily crushed, the countersunk nut 4 was structurally improved by adding an integrally connected pressure ring 5. The improved structure is as follows Figure 3 As shown, after testing, the improved countersunk nut 4 has a tensile strength of about 65 MPa, which is substantially equal to the connection strength of a standard composite material part and can better meet the fastening function of the ceramic matrix composite material skin 2.

[0053] The workpiece 1 has a first surface and a second surface relative to each other, and the first surface and the second surface are parallel; the skin 2 includes a first skin 21 covering the first surface and a second skin 22 covering the second surface; the countersunk screw 3 passes through the first skin 21, the workpiece 1 and the second skin 22, and the head 31 of the countersunk screw 3 presses on the first skin 21 to apply a pre-tightening force thereto; the countersunk nut 4 is threadedly connected to the rod 32 of the countersunk screw 3, and presses on the second skin 22 to apply a pre-tightening force thereto; the first end face is flush with the surface of the first skin 21, and the first end face is perpendicular to the length direction of the countersunk screw 3; the second end face is flush with the surface of the second skin 22, and the second end face is perpendicular to the length direction of the countersunk screw 3.

[0054] The method for connecting the ceramic matrix composite material skin and the workpiece includes:

[0055] S1, a first skin 21 and a second skin 22 of a size required for processing are respectively covered on a first surface and a second surface of a workpiece 1;

[0056] S2, passing the countersunk screw 3 through the first skin 21, the workpiece 1 and the second skin 22, applying a pre-tightening force on the surface of the first skin 21 by tightening the countersunk screw 3, and tightening the countersunk nut 4 to apply a pre-tightening force on the surface of the second skin 22;

[0057] S3, using the CVI process to perform CVI deposition on the workpiece 1 with the skin 2, and riveting the countersunk screw 3 and the countersunk nut 4 to the skin 2.

[0058] Example 2

[0059] See also Figure 4 and Figure 5 This embodiment provides a connection structure between a ceramic matrix composite material skin and a workpiece, including a workpiece 1, a skin 2 covering a portion of the surface of the workpiece 1, and a connecting piece for fastening the skin 2 to the workpiece 1.

[0060] The connecting piece includes a countersunk screw 3 and a countersunk nut 4; the countersunk screw 3 and the countersunk nut 4 are both made of ceramic-based composite materials. Specifically, the density of the ceramic-based composite materials used in the countersunk screw 3 and the countersunk nut 4 is ≥1.85kg / cm 3 .

[0061] The countersunk screw 3 includes a head 31 and a rod 32; the head 31 includes a first cone and a first extension 6 arranged at the thick end of the first cone, the outer end face of the first extension 6 is the first end face, the shape of the first end face matches the shape of the first surface of the workpiece, and is a slope, a curved surface or a step surface; the end face of the thin end of the first cone is integrally connected to the rod 32 and the end face diameter of the thin end is the same as that of the rod 32.

[0062] The countersunk nut 4 includes a second cone and a second extension portion 7 arranged at the thick end of the second cone. The outer end face of the second extension portion 7 is the second end face. The shape of the second end face matches the shape of the second surface of the workpiece, and is a slope, curved surface or step surface. The inner side surface of the thin end of the second cone is threadedly connected to the rod portion 32.

[0063] See also Figure 6 and Figure 7 The countersunk nut 4 also includes a pressure ring 5, which is located at the thin end of the second cone and is integrally formed with the cone. The pressure ring 5 is connected to the thin end of the second cone at one end, and its diameter is the same as the diameter of the thin end of the second cone; the radial thickness of the pressure ring 5 is 0.5 to 3 mm, and the axial height of the pressure ring 5 is greater than or equal to 1 mm.

[0064] The workpiece 1 has a first surface and a second surface relative to each other, the first surface and the second surface are flat surfaces, and the angle between the first surface and the second surface is α, 0<α≤60°; the skin 2 includes a first skin 21 covering the first surface and a second skin 22 covering the second surface; the countersunk screw 3 passes through the first skin 21, the workpiece 1 and the second skin 22, and the head 31 of the countersunk screw 3 presses the first skin 21 to apply a pre-tightening force to it; the countersunk nut 4 is threadedly connected with the rod 32 of the countersunk screw 3, and presses the second skin 22 to apply a pre-tightening force to it; the shape of the first end face matches the shape of the first surface of the workpiece, and is an inclined surface; the shape of the second end face matches the shape of the second surface of the workpiece, and is an inclined surface. It can be understood that the angle between the first surface and the second surface is α, 0<α≤60°, and the first end face can be a plane and the second end face can be an inclined surface, or the first end face can be an inclined surface and the second end face can be a plane.

[0065] The method for connecting the ceramic matrix composite material skin and the workpiece comprises the following steps:

[0066] S1. The first skin 21 and the second skin 22 of the required size for machining are covered on the first surface and the second surface of the workpiece 1.

[0067] S2. Pass the countersunk screw 3 through the first skin 21, the workpiece 1 and the second skin 22, apply a pre-tightening force on the surface of the first skin 21 by tightening the countersunk screw 3, and apply a pre-tightening force on the surface of the second skin 22 by tightening the countersunk nut 4.

[0068] After S3, the countersunk screw 3 and the countersunk nut 4 are installed, the end portions of the first extension portion 6 and the second extension portion 7 are processed so that the first end face formed after the processing of the first extension portion 6 is flush with the surface of the first skin 21 and is an inclined surface; the second end face formed after the processing of the second extension portion 7 is flush with the surface of the second skin 22 and is also an inclined surface; in this embodiment, before processing, the first extension portion 6 and the second extension portion 7 are both cylindrical, which is convenient for the processing and manufacture of the countersunk screw 3 and the countersunk nut 4.

[0069] S4, using the CVI process to deposit the workpiece 1 with the skin 2 after processing in step S3, and riveting the countersunk screw 3 and the countersunk nut 4 to the skin 2.

[0070] The ceramic-based composite skin component provided in the above-mentioned embodiment has been verified through relevant ground experiments, such as static test, thermal test, noise test, vibration test, wind tunnel test, etc. All performance of the product meets the use requirements, and the ceramic-based composite skin component and its connection method are reliable and feasible.

Claims

1. A connection structure between a ceramic matrix composite material skin and a workpiece, characterized in that: It comprises a workpiece (1), a skin (2) covering at least a portion of the surface of the workpiece (1), and a connecting piece for fastening the skin (2) to the workpiece (1); The connecting piece comprises a countersunk screw (3) and a countersunk nut (4); The countersunk screw (3) and the countersunk nut (4) are both made of ceramic-based composite materials; The countersunk screw (3) comprises a head (31) and a stem (32); The head (31) is a first cone, the end surface of the thick end of the first cone is the first end surface, the end surface of the thin end of the first cone is integrally connected to the rod (32), and the diameter of the end surface of the thin end is the same as the diameter of the rod (32); The countersunk nut (4) is a second cone, and the second cone has a screw hole adapted to the rod (32), and the rod (32) can pass through the screw hole of the second cone; the thick end surface of the second cone and the end surface of the rod (32) away from the head (31) form a second end surface, and the inner side surface of the second cone is threadedly connected to the rod (32); The countersunk nut (4) further comprises a pressure ring (5), the pressure ring (5) being located at the thin end of the second cone and being integrally formed with the second cone, the pressure ring (5) being connected to the thin end of the second cone at one end and having the same diameter as the thin end of the second cone; The radial thickness of the pressure ring (5) is 0.5 to 3 mm, and the axial height of the pressure ring (5) is greater than or equal to 1 mm; The workpiece (1) has a first surface and a second surface opposite to each other, the angle between the first surface and the second surface is α, 0<α≤60°; The skin (2) comprises a first skin (21) covering the first surface and a second skin (22) covering the second surface; The thick end of the first cone is provided with a first extension portion (6), the first end surface is located at the outer end surface of the first extension portion (6), and the shape of the first end surface matches the shape of the first surface of the workpiece (1), and is an inclined surface, a curved surface or a stepped surface; The thick end of the second cone is provided with a second extension portion (7), the second end face is located at the outer end face of the second extension portion (7), and the shape of the second end face matches the shape of the second surface of the workpiece (1), and is a slope, a curved surface or a stepped surface.

2. The connection structure of the ceramic matrix composite material skin and the workpiece according to claim 1, characterized in that: The density of the ceramic-based composite material used in the countersunk screw (3) and the countersunk nut (4) is ≥1.85 kg / cm 3 .

3. A method for connecting a ceramic matrix composite material skin to a workpiece, based on the connection structure of the ceramic matrix composite material skin to a workpiece according to claim 1 or 2, characterized in that: The following steps are involved: S1, a skin (2) of a size required for processing is covered on the surface of a workpiece (1); S2, passing the countersunk screw (3) through the skin (2) and the workpiece (1), applying a pre-tightening force on the surface of the skin (2) by tightening the countersunk screw (3), and applying a pre-tightening force on the other side of the skin (2) by tightening the countersunk nut (4); S3. CVI deposition is performed on the workpiece (1) with the skin (2) using a CVI process, and the countersunk screw (3) and the countersunk nut (4) are riveted to the skin (2).

4. The method for connecting a ceramic matrix composite material skin and a workpiece according to claim 3, characterized in that: In step S1, the workpiece (1) has a first surface and a second surface opposite to each other, the angle between the first surface and the second surface is α, 0<α≤60°; the skin (2) includes a first skin (21) covering the first surface and a second skin (22) covering the second surface; Before step S3, step S2-3 is also included, in which the first extension portion (6) and the second extension portion (7) are processed so that the first end face formed after the first extension portion (6) is processed matches the shape of the first surface and is in the form of an inclined surface, a curved surface or a stepped surface; and the second end face formed after the second extension portion (7) is processed matches the shape of the second surface and is in the form of an inclined surface, a curved surface or a stepped surface.

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