CN116576179A - Open self-plugging rivet based on negative poisson ratio and manufacturing method thereof - Google Patents

Abstract

The invention provides an open self-plugging rivet based on negative poisson ratio and a manufacturing method thereof, belonging to the technical field of fasteners; the open self-plugging rivet comprises a rivet rod and a rivet cap, wherein the rivet cap is sleeved with the outer wall of a part of a rod body of the rivet rod, and the part of the rivet rod left in the rivet cap after the loose core of the rivet rod is broken and the rivet cap are both made of materials with negative poisson ratio; calculating the length of a part left in the nail cap after the core pulling of the nail rod is broken according to the size and shape parameters of the open blind rivet, processing and manufacturing the part left in the nail cap after the core pulling of the nail rod is broken and the part of the corresponding nail cap by adopting a material with negative poisson ratio, wherein the rest part is a positive poisson ratio material; the invention solves the problem that the gap is generated between the nail rod and the nail cap rod, and then the gap is generated between the nail rod and the installation hole, so that the loosening is generated, and the service life of the rivet is effectively prolonged.

Description

A kind of open blind rivet based on negative Poisson's ratio and its manufacturing method

technical field

The invention belongs to the technical field of fasteners, in particular to an open blind rivet based on a negative Poisson's ratio and a manufacturing method thereof.

Background technique

The open blind rivet is a type of rivet for single-sided riveting, but it must be riveted with a special tool-a riveting gun (manual, electric, pneumatic). When riveting, the rivet mandrel is pulled by a special riveting gun to expand the riveting body and play the role of riveting. This type of rivet is especially suitable for riveting occasions where it is inconvenient to use ordinary rivets (riveting must be done from both sides). Therefore, it is widely used in construction, automobiles, ships, aircrafts, machines, electrical appliances, furniture and other products. Among them, the open type oblate head blind rivets are the most widely used, the countersunk head blind rivets are suitable for riveting occasions where the surface needs to be smooth, and the closed blind rivets are suitable for riveting occasions requiring higher load and certain sealing performance.

Negative Poisson's ratio materials are currently popular materials, because they are different from traditional materials in terms of mechanical properties of expansion and contraction after being subjected to axial force; this type of material will produce auxetic effect when subjected to axial tension, A compression effect occurs when compressed. This property makes negative Poisson's ratio materials have good shear resistance, impact resistance, fracture resistance and energy dissipation and shock absorption performance. Due to its excellent mechanical properties, this material is widely used in aerospace, industrial engineering, medical equipment and other fields.

In the prior art, conventional blind rivets are constructed of positive Poisson's ratio materials. The connection is achieved by pulling the nail rod to make it tightly connected with the nail cap. However, when the traditional blind rivet is pulled, the nail rod will shrink, so that there will be a certain gap between the nail rod and the nail cap rod, and the device will be stretched when it is subjected to external vibrations in actual engineering, so that the nail cap rod will be stretched. There is a gap between the shrinkage phenomenon and the installation hole and loosening occurs.

Contents of the invention

The invention overcomes the deficiencies of the prior art, and proposes an open blind rivet based on a negative Poisson's ratio and a manufacturing method thereof.

In order to achieve the above object, the present invention is achieved through the following technical solutions.

An open blind rivet based on negative Poisson's ratio, comprising a nail shank and a nail cap, the nail cap is sleeved with part of the outer wall of the shank of the nail shank, the part of the nail shank left in the nail cap after the core is pulled and broken, and the nail cap Both are materials with negative Poisson's ratio properties.

Preferably, the head of the nail rod is provided with a nail rod head, and the nail cap includes a nail cap rod with a nut head at one end; the nail cap rod is adjacent to the nail rod head; the nail cap rod is Materials with a negative Poisson's ratio.

More preferably, the nail shank head, the nail nut head and the nail shank are made of positive Poisson's ratio material except for the part left inside the nail nut after the core is broken.

Preferably, the material with positive Poisson's ratio characteristics is stainless steel, with elastic modulus E=190GPa, Poisson's ratio v=0.305, and density ρ=7.85g/cm ³ .

A method for manufacturing an open blind rivet based on negative Poisson's ratio, comprising the following steps:

Step 1: According to the required construction conditions, determine the size and shape of each part of the blind rivet, including the total length and diameter of the nail shank and the nail cap, and the shape and size of the head of the nail shank and the nail cap;

Step 2: Calculate the length of the part left in the nail cap after the core of the nail rod is broken according to the force during installation and use;

Step 3: The part of the nail shank left in the nail cap after core pulling and fracture, and the corresponding part of the nail cap are made of materials with negative Poisson's ratio properties, and the rest are made of positive Poisson's ratio materials.

Preferably, after determining the size and shape of each part of the blind rivet, establish a finite element model; divide the model grid; set the model loading and boundary conditions according to the force situation during installation and use; then analyze and calculate the core pulling of the nail rod The part that remains inside the nut after breaking.

The beneficial effect that the present invention produces relative to prior art is:

In the present invention, part of the nail shaft and the nail cap are set as negative Poisson's ratio materials. The negative Poisson's ratio material is introduced into the blind rivet, which has auxetic and compressive properties. When the core-pulling rivet is pulling the core, the nail rod is subjected to axial tension to produce an auxetic effect, which makes it more closely connected with the nut rod; at the same time, the nut rod is subjected to axial compression to produce a compression effect, so that the nut rod and the nail rod head The contact is more fit; after the installation is completed, the device is stretched by the external load, and the nail cap rod undergoes auxetic deformation to dissipate energy and absorb shock, and it is more tightly connected to the installation hole after being stretched. The open blind rivet of the present invention can be widely used in daily life and related projects, greatly improving the service life of the rivet. The invention solves the problem of the gap between the nail rod and the nail cap rod, and further the gap between the nail rod and the installation hole to cause loosening.

Description of drawings

Fig. 1 is the structural representation of the split blind rivet utilizing the energy dissipation and shock absorbing type of negative Poisson's ratio in the present invention;

Fig. 2 is a cross-sectional view of Fig. 1;

Fig. 3 is a schematic diagram of the structure of the rivet in Fig. 1 after the core is pulled out, and the contact part between the cap rod and the head of the rivet is "compressed" and deformed;

Fig. 4 is a cross-sectional view of Fig. 3, the nail shank undergoes "auxetic deformation" when the core is pulled under tension, wherein _L4 is the length of the nail shank left in the nail cap rod after the core is pulled;

Fig. 5 is a schematic diagram of the deformation of the open blind rivet according to the present invention after receiving an external impact load during actual engineering operation, and the part of the cap rod that is not in contact with the head of the nail rod undergoes "auxetic deformation" by the external load;

Figure 6 is a schematic diagram of the microporous structure of a material with negative Poisson's ratio properties and its deformation diagram after tension and compression;

In the figure: 1 is the nail rod; 2 is the nail cap rod; 3 is the nail rod head; 4 is the nail cap head; 5 is the material with negative Poisson's ratio;

L1 is the length of the shank; L2 is the length of the head of the shank; L3 is the length of the shank of the shank; L4 is the length of the part of the shank with negative Poisson's ratio; d1 is the radius of the shank; d2 is the radius of the head of the nail; Rod head radius; d4 is the inner diameter of the nut rod.

Detailed ways

In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention clearer, the present invention will be further described in detail in combination with the embodiments and accompanying drawings. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention. The technical solution of the present invention will be described in detail below in conjunction with the embodiments and accompanying drawings, but the scope of protection is not limited thereto.

As shown in Figures 1 to 5, this embodiment provides an energy-dissipating and shock-absorbing open blind rivet utilizing a negative Poisson's ratio, including a nail shank 1 and a nail cap; the head of the nail shank 1 has a shank head 3. The nail cap is composed of the nail cap rod 2 and the nail cap head 4 arranged on the head of the nail cap rod 2; where L ₁ is the total length of the nail rod 1, L ₂ is the length of the nail cap head 4, and L ₃ is the nail cap The length of the rod 2, L ₄ is the calculated length of the nail rod 1 fractured in the nut rod 2.

d ₁ is the radius of the nail shank 1, d ₂ is the radius of the nail shank head 4, d ₃ is the radius of the nail shank head 3, d ₄ is the inner diameter of the nail shank 2, and F1 is the force applied to the nail shank 1 during core pulling. Tensile force, F2 is the pressure of the nail rod head 3 on the nail cap rod 2 when the nail rod core is pulled.

The nail cap rod 2 and the part of the nail rod 1 with a length of _L4 broken in the nail cap rod 2 are materials 5 with negative Poisson's ratio properties. And the nail shank head 3, the nail cap head 4 and the other parts of the nail shank which remain in the nail cap after core pulling and fracture are positive Poisson's ratio characteristic materials. In this embodiment, the positive Poisson's ratio characteristic material is stainless steel, with elastic modulus E=190GPa, Poisson's ratio v=0.305, and density ρ=7.85g/cm ³ . The negative Poisson's ratio material is 3D printed or processed in a factory to manufacture a positive Poisson's ratio material into a microporous structure with a negative Poisson's ratio property as shown in Figure 6 .

Example 2

A method for manufacturing an energy-dissipating and shock-absorbing open blind rivet utilizing a negative Poisson's ratio, comprising the following steps:

Step 1: According to the required construction conditions, determine the size and shape of each part of the blind rivet, including the total length and diameter of the nail shank and the nail cap, the shape and size of the nail shank and the head of the nail cap, the angle of the tail of the nail body and A finite element model is established; in this embodiment, the calculation is performed according to the processing parameters of the split blind rivet described in Embodiment 1.

Step 2: Divide the model grid;

Step 3: Set model loading and boundary conditions according to the force conditions during installation and use;

Step 4: Calculate and calculate the length of the part left in the nail cap after the core-pulling fracture of the nail rod according to the stress situation;

Step 5: Set the part of the nail shank left behind after the core-pulling fracture as a material with a negative Poisson's ratio, and the nail shank is also set as a material with a negative Poisson's ratio, and the rest is a material with a positive Poisson's ratio.

Among them, the steps of establishing a finite element model, dividing the model grid, setting the model loading and boundary conditions, and calculating the length of the part of the nail rod left in the nail cap after the core-pulling fracture according to the force analysis are existing technologies. This implementation In the example, Abaqus commercial finite element software is used for analysis and calculation.

Example 3

The construction method of the open blind rivet described in embodiment 1 specifically comprises the following steps:

Step 1: Customize the structural length of the auxetic region with negative Poisson's ratio properties of the nail rod and the nail cap rod according to the required engineering needs;

Step 2: Insert the device into the part to be connected and prepare for core pulling;

Step 3: Use a rivet gun to pull the nail rod. The auxetic area of the nail rod with negative Poisson’s ratio property will be stretched and expanded more closely with the nail cap rod; the nail rod head will squeeze the nail cap with negative Poisson’s ratio property. Rod, the nail cap rod shrinks and connects more closely with the nail rod head; after the connection is stabilized, the nail rod breaks, leaving only a part of the rod in the auxetic area with negative Poisson's ratio properties;

Step 4: When the connecting part is misaligned by the external load, the nail rod and the nail cap are stretched and expanded while deforming and absorbing energy, which plays the role of energy dissipation and shock absorption.

The working principle provided by the present invention:

As shown in Figure 6, the microporous structure of the negative Poisson’s ratio material, the structure expands to produce auxetic effect when it is stretched, and the structure shrinks to produce a compression effect when it is compressed.

When the nail rod is stretched by the external axial tension during the core-pulling installation process, the nail rod has a microporous material area with a negative Poisson’s ratio performance of the auxetic effect, which causes the auxetic effect to expand and deform under the tensile force . The rod end of the nut that is in direct contact with the head of the screw rod and is subjected to axial pressure from it during installation, under the pressure, due to the negative Poisson's ratio, compression deformation occurs, and the contact with the head of the screw rod is more closely . After the connecting device is installed, in the actual engineering operation, the nail cap rod part of the connecting device is subjected to external force, and auxetic phenomenon will occur when stretching and deformation occur. In the hole, the gap between this area and the hole is reduced, making the connection It is more compact, and the structure deforms to absorb external energy to achieve the effect of energy dissipation and shock absorption.

To sum up, the present invention can well solve the problems related to safety and economy in the existing solutions. This solution has low cost and high degree of automation, thereby improving the construction efficiency, and is more convenient to operate than the existing solutions.

The above content is a further detailed description of the present invention in conjunction with specific preferred embodiments. It cannot be determined that the specific embodiments of the present invention are limited thereto. Under the circumstances, some simple deduction or replacement can also be made, all of which should be regarded as belonging to the scope of patent protection determined by the submitted claims of the present invention.

Claims (6)

1. An open blind rivet based on negative Poisson's ratio, comprising a nail shank and a nail cap, and the part of the nail cap and the nail shank is socketed on the outer wall of the shaft, and it is characterized in that the nail shank stays in the nail cap after the core-pulling fracture The inner part and the nail cap are all materials with negative Poisson's ratio properties. 2. a kind of open blind rivet based on negative Poisson's ratio according to claim 1, is characterized in that, the head of described nail shank is provided with nail shank head, and described nail cap comprises that one end is provided with nail cap head The nut rod; the nut rod is adjacent to the head of the nail rod; the nut rod is a material with a negative Poisson's ratio. 3. a kind of open blind rivet based on negative Poisson's ratio according to claim 2, is characterized in that, described shank head, nut head and nail shank are left in the inner part of nail cap except core-pulling fracture The other parts are positive Poisson's ratio materials. 4. a kind of open blind rivet based on negative Poisson's ratio according to claim 3, is characterized in that, described positive Poisson's ratio characteristic material is stainless steel, modulus of elasticity E=190GPa, Poisson's ratio v= 0.305, density ρ=7.85g/cm ³ . 5. A kind of manufacturing method based on the open blind rivet of negative Poisson's ratio as described in any one of claim 1-4, it is characterized in that, comprises the following steps: Step 1: According to the required construction conditions, determine the size and shape of each part of the open blind rivet, including the total length and diameter of the nail shank and the nail cap, and the shape and size of the head of the nail shank and the nail cap; Step 2: Calculate the length of the part left in the nail cap after the core of the nail rod is broken according to the force during installation and use; Step 3: The part of the nail shank left in the nail cap after core pulling and fracture, and the corresponding part of the nail cap are made of materials with negative Poisson's ratio properties, and the rest are made of positive Poisson's ratio materials. 6. the manufacturing method of a kind of open blind rivet based on negative Poisson's ratio according to claim 5, is characterized in that, after determining the size and the shape of each part of forming blind rivet, set up finite element model; Divide model network According to the force conditions during installation and use, set the model loading and boundary conditions; then analyze and calculate the part left in the nail cap after the core-pulling fracture of the nail shank.