Composite material connecting piece structure, preparation method thereof, test tool and test method

Abstract

The invention relates to a connecting piece structure, in particular to a composite material connecting piece structure, a preparation method thereof, a test tool and a test method. The problems that an existing composite material product is uneven in density distribution and unstable in mechanical property, the use requirement under the high-temperature and high-load working condition is difficult to meet, and application of a ceramic-based composite material in the field of large-scale equipment connection is limited are mainly solved. The composite connecting piece structure comprises a bolt and a tightening nut, the bolt comprises a bolt head nut and a screw rod; the bolt head nut is in threaded connection with one end of the screw rod and is riveted with the screw rod through a plurality of first pins; the tightening nut comprises a plurality of nut sheets; the plurality of nut sheets are sequentially stacked and are riveted into a whole through the plurality of second pins; the tightening nut is in threaded connection with the other end of the screw rod; the bolt head nut, the screw, the nut piece, the first pin and the second pin are all made of ceramic matrix composites. The composite material connecting piece structure is uniform in density, good in performance and capable of meeting the use requirements under the high-temperature and high-load strength.

Description

Technical Field

[0001] This invention relates to a connector structure, specifically to a composite connector structure and its preparation method, testing fixture, and testing method. Background Technology

[0002] Ceramic matrix composites are a new type of thermally structural / functional integrated material that combines the advantages of metallic, ceramic, and carbon materials. They are characterized by high temperature resistance, low density, high specific strength, high specific modulus, oxidation resistance, ablation resistance, insensitivity to cracks, and non-catastrophic damage. They have wide applications in fields such as machinery, aerospace, nuclear, and energy.

[0003] In the existing technology, the preparation of large-size ceramic matrix composite bolts and nuts has always been a bottleneck. Traditional processes result in uneven product density distribution and unstable mechanical properties, making it difficult to meet the requirements of use under high temperature and high load conditions, thus limiting the application of ceramic matrix composites in the field of large equipment connection.

[0004] Meanwhile, for torque and load testing of bolted connections, existing testing methods either rely on complex and costly specialized testing equipment, or cannot achieve synchronous and accurate measurement of torque and load. The testing process is cumbersome and the data reference value is limited, making it difficult to effectively evaluate and optimize product performance, and also unable to provide reliable data support for the design improvement of composite material connectors. Summary of the Invention

[0005] The purpose of this invention is to solve the problems of uneven product density distribution and unstable mechanical properties of existing ceramic matrix composite bolts and nuts, which make it difficult to meet the requirements of high temperature and high load conditions and limit the application of ceramic matrix composites in the field of large equipment connection; as well as the technical problems that existing testing methods cannot achieve synchronous and accurate measurement of torque and load. The invention provides a composite connector structure and its preparation method, testing tooling and testing method.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A composite connector structure, characterized by: Includes bolts and tightening nuts; The bolt includes a bolt head nut and a threaded rod; the bolt head nut is threaded to one end of the threaded rod and riveted to the threaded rod by a plurality of first pins. The tightening nut includes multiple nut pieces; the multiple nut pieces are stacked coaxially in sequence and riveted together by multiple second pins; the tightening nut is threadedly connected to the other end of the screw rod. The bolt head nut, bolt, nut plate, first pin and second pin are all made of ceramic matrix composite material.

[0007] Furthermore, the bolt head nut is riveted to the screw rod by three first pins, the axial direction of the three first pins is perpendicular to the axial direction of the screw rod, and the riveting positions of the three first pins are evenly distributed along the axial direction of the screw rod. The nut pieces are three in number; the three nut pieces are riveted together by six second pins; the axial direction of the six second pins is parallel to the axial direction of the screw, and the riveting positions of the six second pins are evenly distributed along the circumference.

[0008] Furthermore, the screw is a hollow structure, with both its inner and outer walls being stepped structures, and the large ends of the inner and outer walls are arranged in the same direction; The bolt head nut is connected to the large end of the outer wall of the screw rod, and the tightening nut is connected to the small end of the outer wall of the screw rod; A gap is provided axially between the stepped surfaces of the inner and outer walls of the screw, and the length of the gap is 1 / 3 to 1 / 2 of the length of the large end of the outer wall; The thickness between the large end of the inner wall and the large end of the outer wall of the screw is 8mm~10mm, and the thickness between the small end of the inner wall and the small end of the outer wall is 16mm~20mm.

[0009] Furthermore, the bolt head nut has an external hexagonal and internal thread structure, and the straight-line distance from the hexagonal plane to the internal thread is 8mm~10mm.

[0010] Meanwhile, the present invention also provides a method for preparing the aforementioned composite connector structure, which is characterized by including the following steps: Step 1: Deposit bolt head nuts, bolts, nut plates, first pins and second pins with the required material density using chemical vapor deposition. Step 2: Connect the deposited bolt head and nut to the screw rod through threads, and rivet the bolt head and nut to one end of the screw rod through the first pin. After riveting, perform riveting welding treatment by chemical vapor deposition to connect them into a whole bolt. Step 3: Rivet multiple nut pieces together using the second pin, and then machine the internal threads of the nut by chemical vapor deposition. After machining, further strengthen the threads by chemical vapor deposition to connect them into a single tightening nut, thus completing the preparation.

[0011] The present invention also provides a test fixture for the aforementioned composite connector structure, which is characterized in that: Includes upper chuck, lower chuck, and digital torque wrench; The upper chuck is positioned above the lower chuck, and there is a gap between the two. The upper clamp and the lower clamp are respectively fixed at opposite ends to the two output ends of the tensile strength tester, and are used to perform tensile tests on the composite connector structure by means of the tensile strength tester. The upper clamp has a first placement groove on one side, and the lower clamp has a second placement groove on one side that is compatible with the bolt head and nut. The upper clamp and the lower clamp are respectively provided with a third placement groove on one side of their close proximity, which is adapted to the screw in the structure of the composite connector to be tested; the opening directions of the first placement groove, the second placement groove and the third placement groove are arranged in the same direction; The bolt head and nut in the composite connector structure to be tested are placed in the second placement groove, the tightened nut is placed in the first placement groove, and the screw is placed in the third placement groove of the upper and lower chucks; The working end of the digital torque wrench extends into the first placement groove and is installed on the tightening nut for applying torque to the tightening nut.

[0012] Furthermore, the ends of the upper and lower clamps that are furthest from each other are fixed to the two output ends of the tensile strength tester via connecting columns.

[0013] Furthermore, the third placement groove is a U-shaped groove, the width of which is 1-2 mm greater than the diameter of the screw; the center of the inner semi-circle of the U-shaped groove is on the same straight line as the center of the upper and lower chucks.

[0014] This invention also provides a testing method for composite connector structures, based on the aforementioned testing fixture for composite connector structures, characterized by the following steps: Step 1: Place the bolt head and nut in the second placement slot, and tighten the nut and place it in the first placement slot; Step 2: The upper and lower clamps are pulled and moved away from each other by a tensile strength testing machine to preload the composite connector structure. Step 3: After the tensile strength tester displays the preloaded load, install the working end of the digital torque wrench on the tightening nut and apply torque through the digital torque wrench. While applying torque, the tensile strength tester continues to apply load until the set test target is achieved, and the test is completed.

[0015] The beneficial effects of this invention are: 1. This invention designs a structural design for large-size composite material connectors, which solves the problem of preparing large-size ceramic matrix composite bolts and nuts. The products have uniform density and good performance after preparation, and can meet the requirements for use under high temperature and high load strength.

[0016] 2. The present invention also designs a fixture for synchronous testing of torque and load of bolted connections. The fixture has a simple structure, requires no special equipment, and can be tested with the help of a common tensile testing machine.

[0017] 3. This invention also designs a method for synchronously testing the torque and load of bolted connections. The testing process is convenient and quick, and can synchronously record the load value borne by the bolt under a specific torque, providing reliable data support for product performance analysis and structural optimization.

[0018] 4. This invention effectively overcomes the limitations of existing technologies in the preparation and testing of composite material connectors, and improves the application adaptability and performance evaluation efficiency of ceramic matrix composite material connectors. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of a composite connector structure according to an embodiment of the present invention; Figure 2 This is a schematic diagram showing the arrangement of the first and second pins in an embodiment of a composite connector according to the present invention; Figure 3 This is a schematic diagram of the screw structure in an embodiment of a composite connector of the present invention; Figure 4 This is a schematic diagram of a test fixture embodiment of a composite connector structure according to the present invention; Figure 5 This is a schematic diagram of the upper clamp structure in a test fixture embodiment of a composite connector structure of the present invention, where a is a bottom view and b is a front view; Figure 6 This is a schematic diagram of the lower clamp structure in a test fixture embodiment of a composite connector structure according to the present invention. a is the front view and b is the top view.

[0020] The attached figures are labeled as follows: 1- Bolt, 11- Bolt head and nut, 12- Screw, 13- First pin; 2- Tighten the nut, 21- Nut plate, 22- Second pin; 3-Upper chuck, 4-Lower chuck, 5-Digital torque wrench, 6-First placement slot, 7-Second placement slot, 8-Third placement slot, 9-Connecting post. Detailed Implementation

[0021] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] See Figure 1 and Figure 2This embodiment describes a composite connector structure, which mainly includes a bolt head nut 11, a screw 12, a nut plate 21, a first pin 13, and a second pin 22 made of ceramic matrix composite material.

[0023] Bolt 1 is composed of bolt head nut 11, screw 12 and first pin 13.

[0024] See Figure 3 Specifically, the screw 12 is a hollow structure with stepped inner and outer walls, and the larger ends of the inner and outer walls are oriented in the same direction. An axial gap is provided between the stepped surfaces of the inner and outer walls of the screw 12, the length of which is 1 / 3 to 1 / 2 of the length of the larger end of the outer wall; in this embodiment, 1 / 3 is preferred, to enhance the strength of the root of the hollow bolt 1. The thickness between the larger end of the inner wall and the larger end of the outer wall of the screw 12 is 8mm to 10mm, and the thickness between the smaller end of the inner wall and the smaller end of the outer wall is 16mm to 20mm.

[0025] The bolt head nut 11 has an external hexagonal and internal thread structure. The straight-line distance from the hexagonal plane to the internal thread is 8mm~10mm to ensure good material deposition quality.

[0026] The bolt head nut 11 is connected to the large end of the outer wall of the screw 12 and is riveted to the screw 12 by three first pins 13. The axial direction of the three first pins 13 is perpendicular to the axial direction of the screw 12, and the riveting positions of the three first pins 13 are evenly distributed along the axial direction of the screw 12. The connection is made by a three-layer through riveting method to improve the strength and reliability of the connection.

[0027] The nut piece 21 and the second pin 22 together form the tightening nut 2, which is connected to the small end of the outer wall of the screw 12.

[0028] Specifically, there are three nut pieces 21, which are stacked coaxially in sequence. There are six second pins 22, and the three nut pieces 21 are riveted together by the six second pins 22; the axial direction of the six second pins 22 is parallel to the axial direction of the screw 12, and the riveting positions of the six second pins 22 are evenly distributed along the circumferential direction.

[0029] The following steps are specifically adopted when preparing the above-mentioned composite connector structure: Step 1: Deposit the bolt head nut 11, bolt 12, nut plate 21, first pin 13 and second pin 22 with the required material density using chemical vapor deposition.

[0030] Step 2: Connect the deposited bolt head nut 11 to the screw 12 by thread. Rivet the bolt head nut 11 to one end of the screw 12 through three first pins 13. After riveting, perform riveting welding by chemical vapor deposition to connect them into a whole bolt 1.

[0031] Step 3: Instead of preparing internal threads inside the three nut pieces 21, the three nut pieces 21 are first riveted together by the second pin 22, and then the internal threads of the nut are machined by chemical vapor deposition. After machining, the threads are strengthened by chemical vapor deposition to connect them into a whole tightening nut 2, thus completing the preparation.

[0032] When testing the aforementioned composite connector structure, the following testing fixtures are required; see [link to fixture description]. Figure 4 The testing fixture includes an upper chuck 3, a lower chuck 4, and a digital torque wrench 5.

[0033] The upper clamp 3 is positioned above the lower clamp 4, with a gap between them; the opposite ends of the upper clamp 3 and the lower clamp 4 are respectively fixed to the two output ends of the tensile strength tester via connecting posts 9, and the tensile strength tester is used to perform tensile tests on the composite connector structure.

[0034] See Figure 4 and Figure 5 The upper chuck 3 has a first placement groove 6 on one side, see [reference]. Figure 4 and Figure 6 The lower chuck 4 has a second placement groove 7 on one side that is adapted to the bolt head nut 11.

[0035] See Figure 4 , Figure 5 and Figure 6 The upper chuck 3 and the lower chuck 4 are respectively provided with a third placement groove 8 on their respective sides that are close to each other, which is adapted to the screw 12 in the composite connector structure to be tested; the opening directions of the first placement groove 6, the second placement groove 7 and the third placement groove 8 are located on the same side of the upper chuck 3 and the lower chuck 4, and the third placement groove 8 is a U-shaped groove with a width greater than the diameter of the screw 12 by 1~2mm; the center of the inner semi-circle of the U-shaped groove is on the same straight line as the center of the clamping head (upper chuck 3 and lower chuck 4); the screw 12 in the composite connector structure to be tested is placed in the third placement groove 8 of the upper chuck 3 and the lower chuck 4, the bolt head nut 11 is placed in the second placement groove 7, and the tightening nut 2 is placed in the first placement groove 6; the working end of the digital torque wrench 5 extends into the first placement groove 6 and is installed on the tightening nut 2 for applying torque to the tightening nut 2.

[0036] When testing the composite connector structure using the above-mentioned testing fixtures, the following steps are specifically adopted: Step 1: Place the bolt head nut 11 in the second placement groove 7, and tighten the nut 2 in the first placement groove 6.

[0037] Step 2: The upper clamp 3 and the lower clamp 4 are pulled by a tensile strength testing machine to move in a direction away from each other, thereby preloading the load on the composite connector structure.

[0038] Step 3: After the tensile strength tester displays the preloaded load, install the working end of the digital torque wrench 5 on the tightening nut 2, and apply torque through the digital torque wrench 5. While applying torque, the tensile strength tester continues to apply load until the set test target is achieved, and the test is completed.

[0039] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions within the technical scope disclosed in the present invention should be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A composite connector structure, characterized in that: Includes bolts (1) and tightening nuts (2); The bolt (1) includes a bolt head nut (11) and a screw (12); the bolt head nut (11) is threaded to one end of the screw (12) and is riveted to the screw (12) by a plurality of first pins (13); The tightening nut (2) includes multiple nut pieces (21); the multiple nut pieces (21) are stacked coaxially in sequence and riveted together by multiple second pins (22); the tightening nut (2) is threaded to the other end of the screw (12); The bolt head nut (11), bolt (12), nut plate (21), first pin (13) and second pin (22) are all made of ceramic matrix composite material.

2. The composite connector structure according to claim 1, characterized in that: The bolt head nut (11) is radially riveted to the screw (12) by three first pins (13). The axial direction of the three first pins (13) is perpendicular to the axial direction of the screw (12), and the riveting positions of the three first pins (13) are evenly distributed along the axial direction of the screw (12). There are three nut pieces (21); the three nut pieces (21) are riveted together by six second pins (22); the axial direction of the six second pins (22) is parallel to the axial direction of the screw (12), and the riveting positions of the six second pins (22) are evenly distributed along the circumferential direction.

3. A composite connector structure according to claim 1 or 2, characterized in that: The screw (12) is a hollow structure, with both its inner and outer walls being stepped structures, and the large ends of the inner and outer walls are arranged in the same direction; The bolt head nut (11) is connected to the large end of the outer wall of the screw (12), and the tightening nut (2) is connected to the small end of the outer wall of the screw (12); A gap is provided axially between the stepped surfaces of the inner and outer walls of the screw (12), and the length of the gap is 1 / 3 to 1 / 2 of the length of the large end of the outer wall; The thickness between the large end of the inner wall and the large end of the outer wall of the screw (12) is 8mm~10mm, and the thickness between the small end of the inner wall and the small end of the outer wall is 16mm~20mm.

4. The composite connector structure according to claim 3, characterized in that: The bolt head nut (11) has an external hexagonal and internal thread structure, and the straight-line distance from the hexagonal plane to the internal thread is 8mm~10mm.

5. A method for preparing a composite connector structure according to any one of claims 1-4, characterized in that, Includes the following steps: Step 1: Deposit the bolt head nut (11), bolt (12), nut plate (21), first pin (13) and second pin (22) with the required material density using chemical vapor deposition. Step 2: Connect the deposited bolt head nut (11) and screw (12) with threads, and rivet one end of the bolt head nut (11) and screw (12) through the first pin (13). After riveting, perform riveting welding treatment on it by chemical vapor deposition so that it is connected into a whole bolt (1). Step 3: Rivet multiple nut pieces (21) together with the second pin (22), and process the internal thread of the nut by chemical vapor deposition. After processing, further strengthen the thread by chemical vapor deposition to connect them into a whole tightening nut (2) to complete the preparation.

6. A test fixture for the composite connector structure according to any one of claims 1-4, characterized in that: Includes an upper chuck (3), a lower chuck (4), and a digital torque wrench (5); The upper chuck (3) is positioned above the lower chuck (4), and there is a gap between them; The upper clamp (3) and the lower clamp (4) are respectively fixed at opposite ends to the two output ends of the tensile strength tester, and are used to perform tensile tests on the composite connector structure by means of the tensile strength tester. The upper clamp (3) has a first placement groove (6) on one side, and the lower clamp (4) has a second placement groove (7) that is compatible with the bolt head nut (11) on one side. The upper clamp (3) and the lower clamp (4) are respectively provided with a third placement groove (8) that is adapted to the screw (12) in the structure of the composite connector to be tested on one side of the upper clamp (3) and the lower clamp (4); the opening directions of the first placement groove (6), the second placement groove (7) and the third placement groove (8) are arranged in the same direction; The bolt head nut (11) in the composite connector structure to be tested is placed in the second placement groove (7), the tightening nut (2) is placed in the first placement groove (6), and the screw (12) is placed in the third placement groove (8) between the bolt head nut (11) and the tightening nut (2). The working end of the digital torque wrench (5) extends into the first placement groove (6) and is installed on the tightening nut (2) for applying torque to the tightening nut (2).

7. The test fixture for a composite connector structure according to claim 6, characterized in that: The upper clamp (3) and the lower clamp (4) are respectively fixed to the two output ends of the tensile strength tester by connecting columns (9) at their opposite ends.

8. The test fixture for a composite connector structure according to claim 6 or 7, characterized in that: The third placement groove (8) is a U-shaped groove, the width of which is 1-2 mm greater than the diameter of the screw (12); the center of the inner semi-circle of the U-shaped groove is on the same straight line as the center of the upper chuck (3) and the lower chuck (4).

9. A testing method for a composite connector structure, based on the testing fixture for the composite connector structure according to any one of claims 6-8, characterized in that, Includes the following steps: Step 1: Place the bolt head nut (11) in the second placement groove (7) and tighten the nut (2) in the first placement groove (6); Step 2: The upper clamp (3) and lower clamp (4) are pulled by a tensile strength testing machine to move away from each other, thereby preloading the load on the composite connector structure; Step 3: After the preload is displayed on the tensile strength tester, install the working end of the digital torque wrench (5) on the tightening nut (2) and apply torque through the digital torque wrench (5). While applying torque, the tensile strength tester continues to apply load until the set test target is achieved and the test is completed.

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