阅读说明：本技术 一种高温超低膨胀的制动软管及其制备方法 (High-temperature ultralow-expansion brake hose and preparation method thereof ) 是由 康鑫 王亮燕 陶平 任建民 符寿康 卢丽婷 于 2019-10-17 设计创作，主要内容包括：本发明公开了一种高温超低膨胀的制动软管,该制动软管包括橡胶层和编织层,所述编织层位于两层橡胶层之间,并且编织层采用的增强材料为聚酰亚胺纤维,同时采用2股24锭的编织结构；其中,所述制动软管采用三层橡胶层、两层编织层的复合结构,并且从内到外依次为内层橡胶、第一编织层、中层橡胶、第二编织层和外层橡胶。本发明相比于现有软管,具有胶管爆破强度高,常温及高温体积膨胀值小等有益效果,达到了降低制动软管膨胀量及高温下保持制动软管超低膨胀性即在20MPa压力下的膨胀值低于0.60ml/m的目的。(The invention discloses a high-temperature ultralow-expansion brake hose which comprises rubber layers and a woven layer, wherein the woven layer is positioned between the two rubber layers, the reinforced material adopted by the woven layer is polyimide fiber, and meanwhile, a 2-strand 24-spindle woven structure is adopted; the brake hose is of a composite structure of three rubber layers and two woven layers, and is composed of inner rubber, a first woven layer, middle rubber, a second woven layer and outer rubber from inside to outside in sequence. Compared with the existing hose, the hose has the advantages of high hose bursting strength, small normal-temperature and high-temperature volume expansion values and the like, and achieves the purposes of reducing the expansion amount of the brake hose and keeping the ultralow expansibility of the brake hose at high temperature, namely the expansion value of the brake hose under the pressure of 20MPa is lower than 0.60 ml/m.)

1. The brake hose with the high temperature and the ultralow expansion is characterized in that the brake hose is of a composite structure consisting of a rubber layer and a woven layer, the woven layer is located between the two rubber layers, and the woven layer is made of polyimide fibers as a reinforcing material.

2. A high temperature ultra low expansion brake hose according to claim 1, wherein said brake hose is a composite structure of three rubber layers and two braided layers.

3. A high temperature ultra-low expansion brake hose according to claim 1 or 2, wherein the composite structure of the brake hose is composed of an inner rubber layer, a first braided layer, a middle rubber layer, a second braided layer and an outer rubber layer in sequence from inside to outside.

4. A high temperature ultra low expansion brake hose according to claim 1 or 2, wherein said braided layer is of 2 strands of 24 gauge braid structure

5. The preparation method of the high-temperature ultralow-expansion brake hose is characterized in that the brake hose is of a composite structure consisting of a rubber layer and a woven layer, and the preparation steps of the brake hose of the composite structure are as follows:

extruding inner rubber layer into pipe blank with extruder, and penetrating steel core rod with soaked isolating layer into the pipe blank;

step two, placing the pipe blank with the steel core rod in a braiding machine for braiding, sequentially braiding a first braided layer, coating intermediate rubber on the first braided layer, and then braiding a second braided layer;

thirdly, passing the braided tube through an extruder, and coating the braided tube with outer rubber to produce a rubber hose;

putting the rubber hose into a steam vulcanization cylinder for vulcanization and shaping;

and step five, after vulcanization, cutting the end part, and pulling out the steel core to obtain the brake hose.

6. The method for preparing a high-temperature ultra-low expansion brake hose according to claim 5, wherein in the first step, the inner layer rubber is extruded into a 4.0-5.0 mm tube blank by an extruder, and the inner diameter of the steel core rod penetrating into the tube blank is 3.2-3.4 mm.

7. The method for preparing a high-temperature ultralow-expansion brake hose according to claim 5, wherein in the second step, the first braided layer is braided into 24-spindle 2-strand braid structure with a lead of 12-14 mm and an outer diameter of 6.0-7.0 mm.

8. The method for preparing a high-temperature ultralow-expansion brake hose according to claim 5, wherein in the second step, the second braided layer is braided into 24-spindle 2-strand structure with a lead of 15-17 mm and an outer diameter of 7.5-8.5 mm.

9. The method for preparing a high-temperature ultralow-expansion brake hose according to claim 5, wherein the thickness of the intermediate rubber is 0.2-0.4 mm, and the outer diameter of the rubber hose is 9.5-10.5 mm.

10. The method for preparing a high-temperature ultralow-expansion brake hose according to claim 5, wherein in the fourth step, the rubber hose is vulcanized and shaped under the conditions of 0.5-0.7 MPa and 30-60 min.

Technical Field

The invention relates to a high-temperature ultralow-expansion brake hose and a preparation method thereof, belonging to the field of brake hoses.

Background

With the improvement of living standard of people, the consumption of automobiles is gradually changed from demand consumption to enjoyment consumption, which means that the requirements of people on automobiles are increasingly strict, especially the attention on safety. For a vehicle, the most direct safety is whether a brake can brake the vehicle in an emergency, and one of the important factors for determining whether the brake can brake the vehicle is whether the brake hose transmits the brake pressure sufficiently, so that it is expected that the expansion of the brake hose is low, the brake pressure can be transmitted sufficiently, the braking distance is shortened, and the driving safety is improved.

At present, the brake hose on the market mostly adopts a structure of compounding multiple layers of rubber and reinforced materials, wherein the characteristics of the reinforced materials are main factors influencing the expansion performance of the hose. The reinforcing materials commonly used for producing the automobile brake hose comprise rayon, polyester fibers, vinylon fibers and the like, wherein the vinylon fibers have high modulus and small elongation under constant stress, and are the main selection of the low-expansion brake hose at present. However, even in a brake hose using vinylon fibers as a reinforcing material, the hose still has an expansion value higher than 0.60ml/m under a pressure of 20MPa, and vinylon fibers have a large mechanical loss at high temperature, which causes a further increase in the expansion value of the hose.

In summary, the main disadvantages of the currently available brake hoses are: 1. the expansion value of the low-expansion brake hose on the market is high, and the expansion value under the pressure of 20MPa is still higher than 0.60 ml/m; 2. since vinylon fibers are easy to form hydrogen bonds among molecules, the initial modulus of the vinylon fibers is higher than that of polyester fibers with only van der waals force among molecules, and the high initial modulus of the vinylon fibers means that the deformation of the fibers is small when a load of the same magnitude is applied, the vinylon fibers are the main choice for the low-expansion brake hose, but the vinylon fibers have the characteristics of high water absorption rate and large loss of mechanical properties at high temperature, and cause the loss of the expansion performance of the brake hose at high temperature.

Therefore, in order to further reduce the expansion value of the hose at normal and high temperatures of 20MPa, shorten the braking distance, and improve the safety of the vehicle, it is necessary to optimize the structure of the hose and optimize the reinforcing material of the hose.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provide the high-temperature ultralow-expansion brake hose which is reasonable in structural design and matched with reasonable reinforcing materials; the hose can keep the ultralow expansibility of the brake hose at normal temperature or high temperature, namely the expansion value under the pressure of 20MPa is lower than 0.60 ml/m.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

the brake hose is a composite structure consisting of a rubber layer and a woven layer, wherein the woven layer is positioned between the two rubber layers, and the reinforced material adopted by the woven layer is polyimide fiber.

Furthermore, the brake hose adopts a composite structure of three rubber layers and two woven layers; preferably, the rubber layer comprises an inner rubber layer, a first woven layer, a middle rubber layer, a second woven layer and an outer rubber layer from inside to outside.

Further, the braided layer adopts a 2-strand 24-spindle braided structure

A preparation method of a high-temperature ultralow-expansion brake hose comprises the following preparation steps:

extruding inner rubber layer into pipe blank with extruder, and penetrating steel core rod with soaked isolating layer into the pipe blank;

step two, placing the pipe blank with the steel core rod in a braiding machine for braiding, sequentially braiding a first braided layer, then coating intermediate rubber (the intermediate rubber is a pre-made rubber sheet and directly coats the first braided layer) on the first braided layer, and then braiding a second braided layer;

thirdly, passing the braided tube through an extruder, and coating the braided tube with outer rubber to produce a rubber hose;

putting the rubber hose into a steam vulcanization cylinder for vulcanization and shaping;

and step five, after vulcanization, cutting the end part, and pulling out the steel core to obtain the brake hose.

Further, in the first step, the inner layer rubber is extruded into a pipe blank with the diameter of 4.0-5.0 mm through an extruder, and the inner diameter of the steel core rod penetrating into the pipe blank is 3.2-3.4 mm.

Further, in the second step, the weaving structure of the first weaving layer is 24 spindles and 2 strands, the lead is 12-14 mm, and the outer diameter is 6.0-7.0 mm; the second weaving layer weave the structure for 24 spindle 2 strands, the helical pitch is 15 ~ 17mm, and the external diameter is 7.5 ~ 8.5 mm.

Further, the thickness of the middle rubber is 0.2-0.4 mm, and the outer diameter of the rubber hose is 9.5-10.5 mm.

Further, in the fourth step, the rubber hose is vulcanized and shaped under the conditions of 0.5-0.7 MPa and 30-60 min.

In summary, in the design of the reinforced material, the reinforced material is selected from polyimide fibers, which have the characteristics of high modulus, low elongation and high temperature resistance, and the design of the reinforced material can achieve the purpose of the invention for two reasons, one is that the fibers have excellent mechanical properties, for example, the polyimide fibers have breaking strength of 17cN/dtex, which is much greater than 6cN/dtex of vinylon fibers, and have breaking elongation of 2.5%, which is less than 7% of vinylon fibers, and the elongation at 27N is much less than that of vinylon fibers, and the polyimide fibers are selected as the reinforced material of the brake hose, so that the deformation of the reinforced material is smaller under the same pressure, that is, the expansion of the hose is smaller, and the purpose of reducing the expansion of the brake hose can be achieved through the characteristic of the polyimide fibers; and secondly, the polyimide fiber has excellent heat resistance and ultralow water absorption, the mechanical property of the polyimide fiber at 170 ℃ is consistent with that of the normal temperature, the polyimide fiber has no strong loss and is far superior to the high-temperature mechanical retentivity of the vinylon fiber, and the aim of keeping the ultralow expansibility of the brake hose under the conditions of normal temperature and high temperature is fulfilled by virtue of the characteristic.

The invention has the beneficial effects that: the expansion value of the brake hose under the pressure of 20MPa is lower than 0.60ml/m, and the expansion value under the pressure of 20MPa can be always kept to be lower than 0.60ml/m under the temperature of 170 ℃.

Drawings

Fig. 1 is a schematic view of the construction of a brake hose.

Labeled as: 1-outer rubber, 2-second braided layer, 3-middle rubber, 4-first braided layer and 5-inner rubber.

Detailed Description

The invention is described in detail below with reference to the figures and specific embodiments.

The high-temperature ultralow-expansion brake hose is composed of a composite structure of rubber-reinforced material-rubber, wherein the reinforced material is polyimide fiber, and the reinforced material layers are all in a 2-strand 24-spindle braided structure.

The production process of the brake hose comprises the following steps:

1. extruding the inner layer rubber into a pipe blank with the diameter of 4.0-5.0 mm by an extruder, and then penetrating a steel core rod with the inner diameter of 3.2-3.4 mm and immersed with an isolation layer into the pipe blank;

2. placing the tube blank with the mandrel in a braiding machine for braiding, sequentially braiding a first braiding layer, wherein a braiding structure comprises 24 spindles and 2 strands, the lead is 12-14 mm, the outer diameter is 6.0-7.0 mm, the thickness of the middle rubber is 0.2-0.4 mm, a second braiding layer is braided, the braiding structure comprises 24 spindles and 2 strands, the lead is 15-17 mm, and the outer diameter is 7.5-8.5 mm;

3. enabling the braided tube to pass through an extruder, and coating the outer rubber layer on the braided tube to produce a rubber hose with the outer diameter of 9.5-10.5 mm;

4. putting the rubber hose into a steam vulcanization cylinder, and carrying out vulcanization molding under the conditions of 0.5-0.7 MPa and 30-60 min;

5. and after vulcanization, cutting the end part, and pulling out the steel core to obtain the brake hose.

The pair of the brake hose of the present embodiment and the existing brake hose is as follows 1:

TABLE 1 structures and Properties of examples and comparative examples

As can be seen from Table 1, compared with the comparative example, the example has the advantages of high hose bursting strength, small volume expansion values at normal temperature and high temperature and the like, and achieves the purposes of reducing the expansion amount of the brake hose and keeping the ultralow expansion property of the brake hose at high temperature, namely the expansion value of the brake hose under the pressure of 20MPa is lower than 0.60 ml/m.

The foregoing illustrates and describes the principles, general features, and advantages of the present invention. It should be understood by those skilled in the art that the above embodiments do not limit the scope of the present invention in any way, and all technical solutions obtained by using equivalent substitution methods fall within the scope of the present invention.

The parts not involved in the present invention are the same as or can be implemented using the prior art.