Loading structure of high and low temperature rubber hardness measuring device

Abstract

The invention discloses a loading structure of a high and low temperature rubber hardness measuring device. The loading structure comprises a spring, a fixed limiter, an internal main rod, an external main rod, an outer pipe and an alloy pressure head, the spring is of a double-spring structure of an adjusting spring and a force applying spring, and the force applying spring is connected with the top of the inner main rod and used for applying force to the inner main rod. The adjusting spring is used for compensating linear force; the lower end of the internal main rod is connected with an external main rod which is arranged in the outer pipe, and the lowermost end is connected with an alloy pressure head; the force loaded by the spring to the internal main rod acts on the rubber product to be measured through the alloy pressure head, and the hardness value of the rubber product is calculated by measuring the displacement of the internal main rod; the outer pipe comprises two pipe bodies, the two pipe bodies are vertically connected through threads, the pipe body with the upper end close to the inner main rod is made of non-metal materials, and the pipe body with the lower end close to the alloy pressing head is made of metal materials. The device can meet the requirements of multiple times of loading and isolation of high and low temperatures.

Description

Technical Field

[0001] The invention belongs to the field of hardness measurement, and in particular relates to a loading structure of a high and low temperature rubber hardness measuring device. Background Art

[0002] Different industries have different requirements for the performance of rubber products in high and low temperature environments. In the aerospace field, rubber seals, shock-absorbing components, etc. need to maintain stable performance under extreme high and low temperature conditions. Research on high and low temperature rubber hardness can provide a basis for the design and material selection of these key components, ensuring that aircraft can operate normally in high-altitude, low-temperature environments and in high-temperature parts such as engines. Similarly, in special environments such as polar expeditions and deep-sea exploration, rubber products also need to be able to adapt to high and low temperatures. Through in-depth research, the application areas of rubber products can be expanded to meet the needs of more special environments.

[0003] At present, in China, the hardness testing equipment used by many rubber manufacturers and testing institutions is mainly designed for normal temperature environments. These devices can measure the hardness of rubber more accurately at room temperature, but their performance and accuracy may be greatly affected in high and low temperature environments, and there are many limitations. For example, when the temperature changes, the elastic coefficient of the measuring probe of some traditional hardness testers may change, resulting in inaccurate measurement results; and long-term high and low temperature environments will have a serious impact on the test device. High temperature may cause the device to deform and degrade performance, while low temperature may make the device brittle and damaged. At the same time, when performing multiple loading tests, if the strength of the test rod is insufficient, it will affect the accuracy and reliability of the measurement results. Summary of the invention

[0004] The object of the present invention is to provide a loading structure of a high and low temperature rubber hardness measuring device, which can meet the requirements of multiple loading and isolation of high and low temperatures.

[0005] In order to achieve the above-mentioned object, one aspect of the present invention provides a loading structure of a high and low temperature rubber hardness measuring device, comprising a spring, a fixed stopper, an inner main rod, an outer main rod, an outer tube and an alloy pressure head;

[0006] The spring is a double spring structure of an adjustment spring and a force spring. The force spring is connected to the top of the internal main rod and is used to apply force to the internal main rod. One end of the adjustment spring is connected to the middle of the internal main rod, and the other end is fixed to the upper end of the internal main rod, so as to compensate for the linear force.

[0007] The lower end of the inner main rod is connected to the outer main rod, the outer main rod is arranged in the outer tube, and the lower end is connected to an alloy pressure head, and the fixed limiter is used to fix the movement direction and movement range of the inner main rod;

[0008] The force applied by the spring to the internal main rod acts on the rubber product to be tested through the alloy indenter, and the hardness value of the rubber product can be calculated by measuring the displacement of the internal main rod;

[0009] The outer tube includes two tube bodies, which are connected up and down by threads. The tube body at the upper end close to the internal main rod is made of non-metallic material, and the tube body at the lower end close to the alloy pressure head is made of metal material.

[0010] Preferably, the material of the upper tube body is alumina ceramics, polytetrafluoroethylene or polyetheretherketone, and the material of the lower tube body is stainless steel, titanium alloy or alloy steel.

[0011] Preferably, the material of the upper tube body is alumina ceramics, and the material of the lower tube body is titanium alloy.

[0012] Preferably, the material of the internal main rod is stainless steel, titanium alloy, aluminum alloy, nickel-chromium alloy steel or high-strength low-alloy steel, and the material of the alloy pressure head is stainless steel, alloy steel or high-strength low-alloy steel.

[0013] Preferably, the material of the internal main rod is stainless steel, and the material of the alloy pressure head is alloy steel.

[0014] Preferably, the adjustment spring and the force-adding spring remove stress by means of multi-frequency vibration.

[0015] The loading structure of the high and low temperature rubber hardness measuring device according to the above aspect of the present invention can meet the requirements of multiple loading and isolation of high and low temperatures. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solution of the present invention, the following briefly introduces the drawings used in the description of the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work:

[0017] Figure 1 2 is a schematic structural diagram of a high and low temperature rubber hardness measuring device according to an embodiment of the present invention;

[0018] Figure 2 is a schematic diagram of a measurement structure of an embodiment of the present invention;

[0019] Figure 3 is a schematic diagram of a portion of an outer tube close to a pressure head in an embodiment of the present invention;

[0020] Figure 4 It is a schematic diagram of a portion of an outer tube close to an inner main rod in one embodiment of the present invention;

[0021] Figure 5is a schematic diagram of an alloy indenter according to an embodiment of the present invention;

[0022] Figure 6 is a temperature distribution diagram of the non-metallic part of the outer tube at high temperature in one embodiment of the present invention;

[0023] Figure 7 1 is a temperature distribution diagram of the non-metallic part of the outer tube at low temperature according to an embodiment of the present invention. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] One embodiment of the present invention provides a loading structure of a high and low temperature rubber hardness measuring device. Figure 1-5 As shown, the high and low temperature rubber hardness measuring device is composed of a measuring structure and a loading structure, wherein the loading structure includes a spring 1, a fixed stopper 3, an external main rod 4, an internal main rod 5, an outer tube 6, and an alloy indenter 7. Among them, the external main rod 4, the internal main rod 5, and the outer tube 6 constitute an extension module. The measuring structure includes a grating reading head 2 and a grating ruler, wherein the grating reading head 2 is located below the right side of the spring 1, and the movable internal main rod 5 is located on the left side of the grating reading head 2 and is connected to the spring 1, and a grating ruler is added between the internal main rod 5 and the grating reading head 2. A fixed stopper 3 is connected to the left side of the internal main rod 5, and the lower end of the internal main rod 5 is connected to the external main rod 4, which is wrapped in the outer tube 6, and the lower end is connected to the alloy indenter 7. The force applied by the spring to the internal main rod 5 acts on the rubber product to be tested through the alloy indenter 7, and the hardness value of the rubber product can be calculated by measuring the displacement of the internal main rod 5.

[0026] By adopting the above technical solution, the spring 1 can be used to apply force to the main rod 5, and then the alloy pressure head 7 acts on the rubber hardness block. After a certain period of loading, holding and unloading, the displacement of the main rod 5 is recorded by the grating reading head 2 and the grating ruler, and the hardness value is calculated by the corresponding formula. The fixed limiter 3 on the left side of the internal main rod 5 is mainly used to fix the movement direction and range of the internal main rod 5, and the outer tube 6 mainly plays the role of heat insulation and force transmission.

[0027] The spring 1 is a double spring structure of an adjustment spring 11 and a force spring 12, which solves the problems of internal stress, nonlinearity, and low life of a single spring, and realizes high-precision linear loading that maintains a fixed force. Among them, the adjustment spring 11 is mainly used as a compensation connection for linear force, and the force spring 12 is mainly used as the main test force for loading. The force spring 12 is located at the uppermost end of the loading structure, inserted into the spring seat, and connected to the main rod below; one end of the adjustment spring 11 is connected to the middle of the internal main rod 5, and the other end is fixed to the upper end of the internal main rod 5 with a top screw. When loaded normally, the force spring 12 begins to enter a normal working state, and the adjustment spring 11 only plays an auxiliary limiting role; when the load is released, the adjustment spring 11 plays a major tensile support role, eliminating the internal residual stress generated by the long-term force of the loading spring, so that it always maintains a good state.

[0028] Before use, the spring 11 and the force spring 12 are adjusted to quickly remove the stress of the spring by means of multi-frequency vibration, and stress tempering is performed to stabilize the precision. During stress tempering, the additional alternating stress is superimposed on the residual stress, and the energy is absorbed by the friction inside the material. When a certain threshold of the material is reached or exceeded, the spring undergoes microscopic or macroscopic viscoelastic-plastic mechanical changes, thereby reducing and homogenizing the residual stress inside the spring and stabilizing its dimensional precision.

[0029] The outer tube 6 includes two tube bodies, which are connected by threads. The threaded connection ensures that the two tube bodies can stably withstand axial forces after being connected, and maintain the reliability and stability of the connection under load-bearing conditions, and will not easily loosen or fail due to external forces. Of the two tube bodies, the tube body at the upper end close to the internal main rod 5 is made of non-metallic material and has good thermal insulation performance, and the tube body at the lower end close to the alloy pressure head 7 is made of metal material and can withstand various pressures and loads.

[0030] Compared with the traditional rubber hardness tester, the loading structure of the high and low temperature rubber hardness measuring device of the embodiment of the present invention adds an outer main rod 4 and an outer tube 6 integrated with the inner main rod 5 between the inner main rod 5 and the alloy pressure head 7, thereby forming an extended structure. The total length of the outer tube 6 composed of two connected tube bodies is (300-400) mm. By applying a certain pre-tightening force between the two connected outer tube bodies, the strength and stability of the connection are further improved, making it an effective rigid body.

[0031] After the main rod is lengthened, its strength can remain stable under multiple loading conditions, ensuring that in load-bearing application scenarios, even after multiple external forces, it can still reliably exert its force-adding effect, and will not reduce strength, deform or damage due to repeated loading. And the overall mass remains consistent with the original unlengthened pressure foot, always maintaining 1kg.

[0032] The material used for the inner main rod 5 is one of stainless steel, titanium alloy, aluminum alloy, nickel-chromium alloy steel or high-strength low-alloy steel. The material used for the alloy pressure head 7 is one of stainless steel, alloy steel or high-strength low-alloy steel. The material used for the outer tube 6 is a combination of two materials selected from alumina ceramic, PEEK (polytetrafluoroethylene), PTFE (polyetheretherketone), stainless steel, titanium alloy and alloy steel.

[0033] In one embodiment, the material used for the inner main rod 5 is stainless steel, the material used for the alloy pressure head 7 is alloy steel, and the material used for the outer tube 6 is a combination of alumina ceramic and titanium alloy.

[0034] In order to verify the effect of the loading structure of the high and low temperature rubber hardness measuring device of the embodiment of the present invention, the extended module is placed in an incubator to perform heat analysis during the loading process. The titanium alloy tube body and the alloy pressure head part at the lower end of the outer tube are heated by the convection heat transfer of the hot air flow in the incubator. The heating rate is set to 5.3K / s, and it takes about 51.8 seconds to heat up from room temperature 25°C to 300°C. After 8 hours of high temperature in the incubator, the temperature of the titanium alloy tube body at the lower end reaches 300°C, which is consistent with the temperature of the incubator. There is an obvious temperature gradient distribution between the outer tube and the measuring structure due to the thermal insulation effect of the alumina ceramic at the upper end of the outer tube. The temperature curves of the high temperature end and the low temperature end of the alumina ceramic tube body over time are as shown in the figure. Figure 6 As shown, from top to bottom are the standard heating curve, the high temperature end temperature curve and the low temperature end temperature curve. It can be seen that the temperature change at the high temperature end close to the titanium alloy tube body is basically consistent with the heating curve, and the temperature at the low temperature end is significantly reduced due to the thermal insulation performance of alumina ceramics.

[0035] The cooling rate is set to 4.7K / s, and the other conditions remain unchanged. It takes 21.9s to cool from room temperature 23℃ to -80℃. The temperature curves of the high-temperature end and low-temperature end of the alumina ceramic tube over time are as follows: Figure 7 As shown, from top to bottom are the high temperature end temperature curve, the low temperature end temperature curve and the standard cooling curve. It can be seen that the temperature change at the low temperature end close to the titanium alloy tube body is basically consistent with the cooling curve, and the temperature at the high temperature end is significantly increased due to the thermal insulation performance of alumina ceramics.

[0036] In summary, the loading structure of the high and low temperature rubber hardness measuring device according to the embodiment of the present invention has the following beneficial effects compared with the traditional rubber hardness tester:

[0037] 1. The loading force is compensated by the double springs to achieve high-precision linear loading;

[0038] 2. After the main rod is lengthened, its strength can remain stable under multiple loading conditions, ensuring that in load-bearing application scenarios, even after multiple external forces, it can still reliably play a supporting role and will not experience strength reduction, deformation or damage due to repeated loading;

[0039] 3. It has the function of heat insulation and cold insulation, which can effectively prevent the influence of external high temperature or low temperature environment on the internal structure and performance of the measuring device, ensuring that the hardness value can still be reliably displayed accurately when used under different temperature conditions;

[0040] 4. The extension module can be extended into the temperature chamber to measure the rubber hardness and meet the needs of isolating high and low temperatures.

[0041] The above description is only by way of illustration of certain exemplary embodiments of the present invention. It is undoubted that those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A loading structure of a high and low temperature rubber hardness measuring device, characterized in that: It includes a spring, a fixed stopper, an inner main rod, an outer main rod, an outer tube and an alloy pressure head; The spring is a double spring structure of an adjustment spring and a force spring. The force spring is connected to the top of the internal main rod and is used to apply force to the internal main rod. One end of the adjustment spring is connected to the middle of the internal main rod, and the other end is fixed to the upper end of the internal main rod, so as to compensate for the linear force. The lower end of the inner main rod is connected to the outer main rod, the outer main rod is arranged in the outer tube, and the lower end is connected to an alloy pressure head, and the fixed limiter is used to fix the movement direction and movement range of the inner main rod; The force applied by the spring to the internal main rod acts on the rubber product to be tested through the alloy indenter, and the hardness value of the rubber product can be calculated by measuring the displacement of the internal main rod; The outer tube includes two tube bodies, which are connected up and down by threads. The tube body at the upper end close to the internal main rod is made of non-metallic material, and the tube body at the lower end close to the alloy pressure head is made of metal material.

2. The loading structure according to claim 1, characterized in that: The material of the upper end tube body is alumina ceramics, polytetrafluoroethylene or polyetheretherketone, and the material of the lower end tube body is stainless steel, titanium alloy or alloy steel.

3. The loading structure according to claim 2, characterized in that: The material of the upper tube body is alumina ceramics, and the material of the lower tube body is titanium alloy.

4. The loading structure according to any one of claims 1 to 3, characterized in that: The material of the internal main rod is stainless steel, titanium alloy, aluminum alloy, nickel-chromium alloy steel or high-strength low-alloy steel, and the material of the alloy pressure head is stainless steel, alloy steel or high-strength low-alloy steel.

5. The loading structure according to claim 4, characterized in that: The material of the internal main rod is stainless steel, and the material of the alloy pressure head is alloy steel.

6. The loading structure according to any one of claims 1 to 3, characterized in that: The adjusting spring and the force-adding spring remove stress by means of multi-frequency vibration.

Images