Connection structure for composite backrest and a method for making the same

This application is the national phase entry of International Application No. PCT/CN2021/071643, filed on Jan. 14, 2021, which is based upon and claims priority to Chinese Patent Application No. 202011376175.4, filed on Nov. 30, 2020, the entire contents of which are incorporated herein by reference.

The present invention relates to a connection structure for a composite backrest and a method for making the same. The connection structure has reliable structural strength and improved performance of force transmission, while providing the strength required under conditions such as high impact and high torsion.

At present, composite materials are widely used in various fields of production and life by virtue of their high strength and rigidity, superior impact resistance and excellent structural designability, as well as the ability to facilitate the shaping of cambered structures. Composite materials not only retain the advantages of all constituent materials, but also exhibit, by means of synergy and correlation among these constituent materials, an improved overall performance that cannot be achieved by a single constituent material. Also, composite materials can be easily formed into various complex shapes. Hence, composite materials are widely used in various fields such as aerospace, medicine, automobiles, textiles, and machinery making. Composite backrests have been gradually introduced in the field of aviation by virtue of their advantages of light weight and high strength. Current composite backrests typically have a structure with a combination of frames and a back plate. The connection between the backrest and a support component is accomplished by connecting pins or shafts into holes at the lower end of the frame. Once the composite backrest is punched, the current connection method has the following shortcomings:

(1) Fibers at the hole positions may fracture, which affects the performance of force transmission.

(2) Stress concentration may arise at the hole positions and consequently causes interfacial damage.

(3) The processing accuracy of the holes cannot achieve the accuracy required by metal processing. In this case, the pins or shafts cannot satisfactorily fit within the holes. As a result, gaps are present between the pins or shafts and the holes, resulting in nonuniform contact surfaces under stress, which easily causes unilateral damage.

In view of the above-mentioned problems, an objective of the present invention is to provide a connection structure for a composite backrest and a method for making the same. The connection structure has reliable structural strength and improved performance of force transmission, while providing the strength required under conditions such as high impact and high torsion.

To solve the above-mentioned technical problems, the present invention adopts the following technical solution. A connection structure for a composite backrest includes two frames, a backrest body, and metal bushings. The metal bushings include a group of left metal bushings and a group of right metal bushings. The two frames are respectively fixed to the left side and the right side of the backrest body by the group of left metal bushings and the group of right metal bushings.

In a specific embodiment, each group of metal bushings include a plurality of groups of connection bushings.

In a specific embodiment, each group of connection bushings include an externally-threaded bushing and an internally-threaded bushing matched with the externally-threaded bushing. A threaded hole is formed in each of the two frames and the backrest body. The externally-threaded bushings and the internally-threaded bushings are engaged to fix the two frames to the backrest body. The externally-threaded bushings and the internally-threaded bushings on the same side of the backrest body are alternately arranged.

In a specific embodiment, the frames are hollow and rectangular.

In a specific embodiment, the lower half of the backrest body is thinner than the upper half of the backrest body, and the lower half is formed as a U-shaped groove.

A method for making a connection structure for a composite backrest includes:

step 1: punching the composite backrest body and the two frames, and placing the two frames into the backrest body;

step 2: processing the metal bushing into an externally-threaded bushing and an internally-threaded bushing matched with the externally-threaded bushing;

step 3: sandblasting or sanding the external surface of the metal bushing processed in step 2;

step 4: coating a configured structural adhesive on the metal bushing with the surface processed in step 3, and oppositely bonding the metal bushing from the two sides of the hole in the frame of the backrest;

step 6: placing the fixed metal bushing, the composite backrest and the two frames into a drying oven for heating, and removing the tool after the structural adhesive is completely cured.

In a specific embodiment, the composite backrest body in step 1 is made from a carbon fiber reinforced polymer, an aramid fiber reinforced polymer, or a glass fiber reinforced polymer.

In a specific embodiment, the metal bushing in step 2 is made from aluminum, steel, or copper.

In a specific embodiment, the step of processing the external surface of the metal bushing in step 3 specifically includes the following steps:

cleaning the external surface of the metal bushing by using a cleaning agent, sandblasting or sanding the surface according to different materials for roughening, cleaning the roughened surface by using the cleaning agent again, and according to different structural adhesives, coating the cleaned surface of the metal bushing with a primer to improve the bonding effect when necessary.

In a specific embodiment, the structural adhesive in step 4 includes an epoxy structural adhesive, a polyurethane structural adhesive, or an acrylic structural adhesive.

In a specific embodiment, the heating process in step 6 is performed at 40° C.-100° C. for 10-240 minutes.

The connection structure for a composite backrest and the method for making the same provided by the present invention has the following advantages. The connection structure provides more reliable structural strength between the composite backrest and a support component thereof, and has improved performance of force transmission, while providing the strength required under conditions such as high impact and high torsion.

FIG. 1 is a schematic diagram of the composite backrest body and the frames after being punched according to the present invention;

FIG. 2 is a structural schematic diagram of metal bushings according to the present invention;

FIG. 3 is a schematic diagram illustrating opposite bonding of the metal bushings according to the present invention; and

FIG. 4 is a schematic diagram of a connection structure for the composite backrest according to the present invention.

In the figures:

1 , frame; 2 , backrest body; 3 , metal bushing; 4 , threaded hole; 301 , externally-threaded bushing; 302 , internally-threaded bushing.

The technical solutions of the present invention are expounded below based on the preferred embodiments described with reference to the drawings.

FIG. 1 is a schematic diagram of the composite backrest body and the frames after being punched according to the present invention. FIG. 2 is a structural schematic diagram of metal bushings according to the present invention. FIG. 3 is a schematic diagram illustrating the opposite bonding of the metal bushings according to the present invention. FIG. 4 is a schematic diagram of a connection structure for the composite backrest according to the present invention. As shown in these figures, the connection structure for a composite backrest includes the two frames 1 , the backrest body 2 , and the metal bushings 3 . The metal bushings 3 include a group of left metal bushings and a group of right metal bushings. The two frames are respectively fixed to the left side and the right side of the backrest body by the group of left metal bushings and the group of right metal bushings. Each group of metal bushings include a plurality of groups of connection bushings.

Referring to FIGS. 3 - 4 , each group of connection bushings include the externally-threaded bushing 301 and the internally-threaded bushing 302 matched with the externally-threaded bushing. The threaded hole 4 is formed in each of the two frames and the backrest body. The externally-threaded bushings and the internally-threaded bushings are engaged to fix the two frames to the backrest body. The externally-threaded bushings and the internally-threaded bushings on the same side of the backrest body are alternately arranged. Particularly, referring to FIG. 3 , the externally-threaded bushings 301 and the internally-threaded bushings 302 in the group of left metal bushings are alternately arranged. In a group of upper connection bushings, the externally-threaded bushing 301 is located on the outer side of the backrest body 2 , while the internally-threaded bushing 302 is located on the inner side of the backrest body 2 . In a group of lower connection bushings, the externally-threaded bushing 301 is located on the inner side of the backrest body 2 , while the internally-threaded bushing 302 is located on the outer side of the backrest body 2 . If multiple groups of connection bushings are arranged, in the next group of connection bushings, the externally-threaded bushing 301 is located on the outer side of the backrest body 2 , while the internally-threaded bushing 302 is located on the inner side of the backrest body 2 . In still the next group of connection bushings, the externally-threaded bushing 301 is located on the inner side of the backrest body 2 , while the internally-threaded bushing 302 is located on the outer side of the backrest body 2 . Similarly, the externally-threaded bushings 301 and the internally-threaded bushings 302 in the group of right metal bushings are arranged in the same way.

In a specific implementation of the present invention, the frames are hollow and rectangular. The lower half of the backrest body is thinner than the upper half of the backrest body, and the lower half may be structurally formed as a U-shaped groove shown in the figure.

According to the present invention, a method for making the connection structure for a composite backrest includes:

Step 1: the composite backrest body and the two frames are punched, and the two frames are placed into the backrest body.

Step 2: the metal bushing is processed into the externally-threaded bushing and the internally-threaded bushing matched with the externally-threaded bushing.

Step 3: the external surface of the metal bushing processed in step 2 is sandblasted or sanded.

Step 4: a configured structural adhesive is coated on the metal bushing with the surface processed in step 3, and the metal bushing is oppositely bonded from the two sides of the hole in the frame of the backrest.

Step 6: the fixed metal bushing, the composite backrest and the two frames are placed into a drying oven for heating, and the tool is removed after the structural adhesive is completely cured.

The composite backrest body in step 1 is made from a carbon fiber reinforced polymer, an aramid fiber reinforced polymer, or a glass fiber reinforced polymer.

The metal bushing in step 2 is made from aluminum, steel, or copper.

The step of processing the external surface of the metal bushing in step 3 includes the following steps:

the external surface of the metal bushing is cleaned by using a cleaning agent, and is then sandblasted or sanded according to different materials for roughening; the roughened surface is cleaned by using the cleaning agent again; and according to different structural adhesives, the cleaned surface of the metal bushing is coated with a primer to improve the bonding effect when necessary.

The structural adhesive in step 4 includes an epoxy structural adhesive, a polyurethane structural adhesive, or an acrylic structural adhesive.

The heating process in step 6 is performed at 40° C.-100° C. for 10-240 minutes.

The connection structure obtained according to the process of the present invention provides the overall strength required under conditions such as high impact and high torsion, has stable performance, and effectively exploits the structural advantages of the composite backrest.

The connection structure for a composite backrest of the present invention is particularly used between the composite backrest and a support component thereof. Such a connection structure provides more reliable structural strength between the composite backrest and the support component thereof, and has improved performance of force transmission while providing the strength required under conditions such as high impact and high torsion. The connection structure obtained by means of the process according to the present invention has stable performance and effectively exploits the structural advantages of the composite backrest, and is thus conducive to be widely popularized and applied on the market.

The above describes the basic principles, main features and advantages of the present invention. Those skilled in the art should know that the present invention is not limited by the above embodiments. The above embodiments and the specification merely describe the principle of the present invention. The present invention further has various changes and improvements without departing from the spirit and principle of the present invention, and these changes and improvements shall fall within the scope of protection of the present invention. The scope of protection of the present invention is limited by the appended claims and their equivalents.