Vacuum-pumping injection molding method for rubber elastic bearing of helicopter rotor

Abstract

The invention discloses a helicopter rotor rubber elastic bearing vacuumizing injection molding method which comprises the following steps: S1, taking a plurality of small joints, large joints and metal spacers required for processing an elastic bearing body, carrying out sand blasting pretreatment on the small joints and the large joints, and carrying out uniform punching pretreatment on the metal spacers; according to the invention, the elastic bearing is subjected to injection molding in a vacuum environment, so that the porosity in the elastic bearing is reduced, and the tensile strength and the fatigue resistance of the elastic bearing laminated body can be remarkably improved by combining the rubber material with fibers for injection molding and the perforated metal spacer; the elastic bearing of the helicopter can better adapt to high-frequency vibration and extreme temperature change scenes, and the service life of the elastic bearing is prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of elastic bearings, and particularly relates to a method for vacuum injection molding of a helicopter rotor rubber elastic bearing. Background Art

[0002] The helicopter rotor rubber elastic bearing is a core component of the rotor system, which needs to bear alternating torsional loads, radial loads and vibration shocks, and has extremely high requirements for the bonding strength between rubber and metal, internal compactness and dimensional accuracy.

[0003] Chinese Patent Application No. CN202111354469.1 discloses a vulcanization molding method based on a rubber-metal spherical elastic bearing. The vulcanization molding process of the spherical elastic bearing is divided into two parts: a preforming process in section I and a hot vulcanization molding process in section II.

[0004] In the traditional injection molding process, air bubbles are easily entrapped in the rubber melt during the mold filling process, resulting in pore defects inside the product; and the laminated body of the elastic bearing has weak tensile strength and fatigue resistance, resulting in a low service life of the elastic bearing. Therefore, it is urgent to design a method for vacuum injection molding of a helicopter rotor rubber elastic bearing to solve the above problems. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for vacuum injection molding of a helicopter rotor rubber elastic bearing to solve the above deficiencies in the prior art.

[0006] To achieve the above purpose, the present invention provides the following technical solutions:

[0007] A method for vacuum injection molding of a helicopter rotor rubber elastic bearing, comprising the following steps:

[0008] S1: Take a number of small joints, large joints and metal spacers required for processing the elastic bearing body, perform sandblasting pretreatment on the small joints and large joints, and perform uniform hole punching pretreatment on the metal spacers;

[0009] S2: Use a jig to fix the metal spacers in a laminated form, and fix the small joints and large joints on the jig according to the design dimensions of the elastic bearing to form a skeleton of the elastic bearing body. Then, place the skeleton of the elastic bearing body together with the jig into a mold with a vacuum channel and close the mold;

[0010] S3: First, evacuate the inside of the mold, and then inject the rubber compound with fibers into the inside of the mold for blank molding;

[0011] S4: Cut off the excess rubber outside the blank, and then vulcanize it to obtain the elastic bearing body.

[0012] Further, in the step S1, when performing sandblasting pretreatment, alumina sand with a mesh size of 120 - 150 is used, the sandblasting pressure is 0.3 - 0.5 MPa. After sandblasting, ultrasonic cleaning is carried out with acetone for 10 min, and then alkaline solution immersion treatment is carried out for 30 min.

[0013] Further, the pH value of the alkaline solution is 10 - 12, and the surface roughness of the small joint and the large joint is Ra = 3.2 - 6.3 μm.

[0014] Further, in the step S1, the diameter of the holes punched on the metal spacer is 3 - 6 mm, and the number of holes punched on each metal spacer is 4 - 10.

[0015] Further, in the step S2, a gap of 1 - 5 mm is left between several stacked metal spacers.

[0016] Further, in the step S3, the vacuum degree inside the mold is controlled at - 0.08 to - 0.095 MPa.

[0017] Further, in the step S3, the process of injecting the rubber compound is carried out in two stages:

[0018] In the first stage, 60% of the rubber compound is injected at a low speed of 15 - 25 cm 3 / s, and the injection pressure is 50 - 70 MPa;

[0019] In the second stage, it is switched to a high speed of 40 - 60 cm 3 / s to complete the injection of the remaining rubber compound, and the pressure is increased to 80 - 100 MPa. After the injection is completed, the vacuum degree is maintained for 30 - 60 min.

[0020] Further, in the step S4, gradient vulcanization

[0021] Adopts three - stage temperature control:

[0022] In the first stage: the vulcanization temperature is 110℃ - 120℃, and the vulcanization time is 20 min to promote the full flow of the rubber compound;

[0023] In the second stage: the vulcanization temperature is 150℃ - 160℃, and the vulcanization time is 30 min to complete the main cross - linking reaction;

[0024] In the third stage: the vulcanization temperature is 170℃ - 180℃, and the vulcanization time is 10 min to increase the cross - linking density.

[0025] Further, in the step S3, the fiber in the rubber compound is one or a combination of two of aramid fiber and nylon fiber.

[0026] In the above technical solution, a method for vacuum injection molding of a helicopter rotor rubber elastic bearing provided by the present invention has the following beneficial effects: The present invention injects the elastic bearing in a vacuum environment, reducing the porosity in the elastic bearing. By combining the injection molding with a rubber compound having fibers and a perforated metal spacer, the tensile strength and fatigue resistance of the elastic bearing laminate can be significantly improved, enabling the elastic bearing of the helicopter to better adapt to high-frequency vibration and extreme temperature change scenarios and extending the service life of the elastic bearing. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required in the embodiments. Obviously, the drawings described below are only some embodiments recorded in the present invention, and those of ordinary skill in the art can also obtain other drawings based on these drawings.

[0028] Figure 1 It is the overall flowchart provided by an embodiment of the method for vacuum injection molding of a helicopter rotor rubber elastic bearing of the present invention.

[0029] Figure 2 It is the vulcanization flowchart provided by an embodiment of the method for vacuum injection molding of a helicopter rotor rubber elastic bearing of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0030] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the following will further introduce the present invention in detail Figure 1-2 with reference to the attached drawings.

[0031] Embodiment 1

[0032] A method for vacuum injection molding of a helicopter rotor rubber elastic bearing includes the following steps:

[0033] S1: Take several small joints, large joints, and metal spacers required for processing the elastic bearing body. Perform sandblasting pretreatment on the small joints and large joints. When performing sandblasting pretreatment, use alumina sand with a mesh size of 120 - 150, a sandblasting pressure of 0.3 - 0.5 MPa. After sandblasting, perform ultrasonic cleaning with acetone for 10 minutes, and then soak in an alkali solution for 30 minutes. The pH value of the alkali solution is 10 - 12. The purpose of cleaning is to remove oxides and stains on the metal surface. The surface roughness of the small joints and large joints is Ra = 3.2 - 6.3 μm. The purpose of sandblasting is to increase the surface roughness of the metal parts, so that the contact area between the rubber and the metal increases. Perform uniform punching pretreatment on the metal spacers. In the prior art, each rubber layer is independent, resulting in a small bonding force between the rubber layer and the metal spacer. After long-term use, the rubber layer and the metal spacer are prone to separation. After punching the metal spacer, it can form a connection between each rubber layer after injection molding, thereby improving the bonding force between the rubber layer and the metal spacer, making it difficult for the rubber layer and the metal spacer to separate. The diameter of the holes punched on the metal spacer is 3 - 6 mm, and the number of holes punched on each metal spacer is 4 - 10;

[0034] S2: Use a jig to fix the metal spacers in a stacked form, leaving a gap of 1 - 5 mm between the stacked metal spacers, so that rubber can enter between adjacent two metal spacers to form a rubber layer. Fix the small joint and the large joint on the jig according to the design dimensions of the elastic bearing, and also maintain a gap of 1 - 5 mm between the small joint and the large joint and the metal spacer to form the elastic bearing body skeleton. Then, put the elastic bearing body skeleton together with the jig into a mold with a vacuum channel and close the mold;

[0035] S3: First, evacuate the inside of the mold, and then inject the rubber compound with fibers into the inside of the mold for blank molding. The vacuum degree inside the mold is controlled between -0.08 and -0.095 MPa;

[0036] S4: Cut off the excess rubber outside the blank, and then vulcanize it to obtain the elastic bearing body.

[0037] Further, in S3, the process of injecting the rubber compound is carried out in two stages:

[0038] In the first stage, inject 60% of the rubber compound at a low speed of 15 cm 3 / s, and the injection pressure is 60 MPa;

[0039] In the second stage, switch to a high speed of 40 cm 3 / s to complete the injection of the remaining rubber compound, and the pressure is increased to 100 MPa. After the injection is completed, maintain the vacuum degree for 30 minutes.

[0040] Further, in S4, gradient vulcanization

[0041] Three-stage temperature control is adopted:

[0042] The first stage: The vulcanization temperature is 110°C - 120°C, and the vulcanization time is 20 min to promote the full flow of the rubber compound.

[0043] The second stage: The vulcanization temperature is 150°C - 160°C, and the vulcanization time is 30 min to complete the main cross-linking reaction.

[0044] The third stage: The vulcanization temperature is 170°C - 180°C, and the vulcanization time is 10 min to increase the cross-linking density.

[0045] Furthermore, in S3, the fiber in the rubber compound is aramid fiber.

[0046] Example 2

[0047] A method for vacuum injection molding of a rubber elastic bearing for a helicopter rotor, comprising the following steps:

[0048] S1: Take several small joints, large joints and metal spacers required for processing the elastic bearing body, and perform sandblasting pretreatment on the small joints and large joints. When performing sandblasting pretreatment, 120 - 150 mesh alumina sand is used, the sandblasting pressure is 0.3 - 0.5 MPa. After sandblasting, ultrasonic cleaning is carried out with acetone for 10 min, and then alkali liquor soaking treatment is carried out for 30 min. The pH value of the alkali liquor is 10 - 12. The purpose of cleaning is to remove oxides and stains on the metal surface. The surface roughness of the small joints and large joints is Ra = 3.2 - 6.3 μm. The purpose of sandblasting is to increase the surface roughness of the metal parts, so that the contact area between the rubber and the metal increases. Uniform punching pretreatment is carried out on the metal spacers. In the prior art, each rubber layer is independent, so that the bonding force between the rubber layer and the metal spacer is small, and the rubber layer and the metal spacer are prone to separation after long-term use. After the metal spacer is punched, it can form a connection between the rubber layers after injection molding, and then can improve the bonding force between the rubber layer and the metal spacer, so that the rubber layer and the metal spacer are not easy to separate. The diameter of the holes punched on the metal spacer is 3 - 6 mm, and the number of holes punched on each metal spacer is 4 - 10.

[0049] S2: Use a jig to fix the metal spacers in a stacked form, leaving a gap of 1 - 5 mm between the stacked metal spacers, so that rubber can enter between adjacent two metal spacers to form a rubber layer. Fix the small joints and large joints on the jig according to the design dimensions of the elastic bearing, and also maintain a gap of 1 - 5 mm between the small joints and large joints and the metal spacers to form a skeleton of the elastic bearing body. Then, put the skeleton of the elastic bearing body together with the jig into a mold with a vacuum channel and close the mold.

[0050] S3: First, evacuate the inside of the mold, and then inject the rubber compound with fibers into the inside of the mold to form a blank. The vacuum degree inside the mold is controlled between -0.08 and -0.095 MPa. The injection of the rubber compound is carried out in two stages. The fibers in the rubber compound are nylon fibers:

[0051] In the first stage, inject 60% of the rubber compound at a low speed of 15 cm 3 / s, and the injection pressure is 60 MPa;

[0052] In the second stage, switch to a high speed of 40 cm 3 / s to complete the injection of the remaining rubber compound, and the pressure is increased to 100 MPa. After the injection is completed, maintain the vacuum degree for 30 min;

[0053] S4: Cut off the excess rubber outside the blank, and then vulcanize it to obtain an elastic bearing body.

[0054] Gradient vulcanization adopts three-stage temperature control:

[0055] The first stage: The vulcanization temperature is 110°C - 120°C, and the vulcanization time is 20 min to promote the full flow of the rubber compound;

[0056] The second stage: The vulcanization temperature is 150°C - 160°C, and the vulcanization time is 30 min to complete the main cross-linking reaction;

[0057] The third stage: The vulcanization temperature is 170°C - 180°C, and the vulcanization time is 10 min to increase the cross-linking density.

[0058] Only some exemplary embodiments of the present invention are described above by way of illustration. Undoubtedly, for those of ordinary skill in the art, without departing from the spirit and scope of the present invention, the described embodiments can be modified in various different ways. 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 method for vacuum injection molding of a helicopter rotor rubber elastic bearing, characterized in that: The following steps are involved: S1: Take a number of small joints, large joints and metal spacers required for processing the elastic bearing body, perform sandblasting pretreatment on the small joints and large joints, and perform uniform punching pretreatment on the metal spacers; S2: Fix the metal spacers in a stacked form using a jig, and fix the small joints and the large joints on the jig according to the design size of the elastic bearing to form an elastic bearing body skeleton. The elastic bearing body skeleton and the jig are loaded into a mold with a vacuum channel and then molded; S3: First, the inside of the mold is vacuumed, and then the rubber material with fibers is injected into the mold to form the blank; S4: The excess rubber on the outside of the blank is cut off and then vulcanized to obtain an elastic bearing body.

2. A method for vacuum injection molding of a helicopter rotor rubber elastic bearing according to claim 1, characterized in that: In S1, 120-150 mesh alumina sand is used for sandblasting pretreatment, and the sandblasting pressure is 0.3-0.5 MPa. After sandblasting, acetone ultrasonic cleaning is performed for 10 minutes, and then alkali solution immersion treatment is performed for 30 minutes.

3. A method for vacuum injection molding of a helicopter rotor rubber elastic bearing according to claim 2, characterized in that: The pH of the alkali solution is 10-12, and the surface roughness of the small joint and the large joint is Ra=3.2-6.3μm.

4. A method for vacuum injection molding of a helicopter rotor rubber elastic bearing according to claim 3, characterized in that: In S1, the diameter of the holes punched on the metal separator is 3-6 mm, and the number of holes punched on each metal separator is 4-10.

5. The method for vacuum injection molding of a helicopter rotor rubber elastic bearing according to claim 1, characterized in that: In the above S2, a gap of 1-5 mm is left between the stacked metal spacers.

6. The method for vacuum injection molding of a helicopter rotor rubber elastic bearing according to claim 1, characterized in that: In S3, the vacuum degree inside the mold is controlled to be -0.08 to -0.095 MPa.

7. The method for vacuum injection molding of a helicopter rotor rubber elastic bearing according to claim 1, characterized in that: In S3, the process of injecting the rubber material is divided into two stages: The first stage is to slow down 15-25cm 3 / s inject 60% rubber, injection pressure 50-70MPa; The second stage switches to high speed 40-60cm 3 / s to complete the injection of the remaining rubber material, the pressure is increased to 80-100MPa, and the vacuum is maintained for 30-60min after the injection is completed.

8. The method for vacuum injection molding of a helicopter rotor rubber elastic bearing according to claim 1, characterized in that: In the S4, gradient vulcanization Three-stage temperature control: The first stage: the vulcanization temperature is 110℃-120℃, and the vulcanization time is 20min; The second stage: the vulcanization temperature is 150℃-160℃, and the vulcanization time is 30min; The third stage: the vulcanization temperature is 170℃-180℃, and the vulcanization time is 10min.

9. The method for vacuum injection molding of a helicopter rotor rubber elastic bearing according to claim 1, characterized in that: In S3, the fiber in the rubber material is one or a combination of aramid fiber and nylon fiber.

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