Preparation method of large-stroke pneumatic rubber diaphragm

Abstract

The invention discloses a preparation method of a large-stroke pneumatic rubber diaphragm, an aramid cord fabric is prepared by adopting a weft knitting method, and the prepared aramid cord fabric is used as a diaphragm to be clamped and attached to the surface or the interior of rubber, and the preparation method comprises the following steps: weaving aramid yarns by adopting a double-sided large-circle knitting machine; the aramid yarn is divided into three strands, and three yarn feeding wheels are combined into one hole to feed the yarn; setting the thread length and adjusting the tension of the cloth rolling frame; uniformly soaking the aramid cord fabric prepared by a weft knitting method in the adhesive cement, and finishing and flattening the aramid cord fabric; performing thin-passing on the rubber in an open rubber mixing mill, and discharging sheets; respectively cutting the aramid cord fabric and the rubber sheet into circular sheets with different diameters according to different specifications; according to different process requirements, the cut sheets are sequentially put into a mold to be subjected to vulcanization forming. The preparation method of the large-stroke pneumatic rubber diaphragm provided by the invention can solve the problem of wrinkles generated when the cord fabric and the rubber of the large-stroke pneumatic rubber diaphragm are compounded, and the large-stroke pneumatic rubber diaphragm can be applied to a severe environment for a long time.

Description

Technical Field

[0001] The invention relates to a method for preparing a rubber diaphragm, in particular to a method for preparing a large-stroke pneumatic rubber diaphragm. Background Art

[0002] The long-stroke pneumatic rubber diaphragm is a rubber product with a cord on the surface or inside. It is used in long-stroke pneumatic control valves and installed in the upper actuator of the pneumatic control valve. Through high-frequency input or release of air pressure, the diaphragm moves back and forth with a large stroke to output mechanical force, which is transmitted to the valve disc through the connected valve stem, thereby opening or closing the valve at a high frequency to achieve the purpose of controlling the flow of pipeline fluid. It is one of the core components of the pneumatic control valve.

[0003] At present, the cord fabrics commonly used in rubber diaphragms are mainly made by shuttle weaving, and the cord fabric fiber materials are mostly nylon fiber and polyester fiber. Shuttle weaving: The yarns are interlaced in the warp and weft directions through a loom in the form of shuttle throwing, and are divided into three categories: plain weave, twill and satin.

[0004] When the long-stroke pneumatic rubber diaphragm is used in the pneumatic valve equipment of the nuclear island and conventional island in the nuclear power field, after the air pressure is continuously input and released to the device, the rubber diaphragm is moved back and forth with high frequency and large stroke, and the connecting rod is driven to move, thereby converting the air pressure into mechanical force, and the mechanical force is transmitted to the guide device to achieve the function of opening and closing the guide device. However, when the curtain made by the shuttle weaving method is used in the molding process of the long-stroke pneumatic rubber diaphragm, due to the lack of elasticity and extensibility, the curtain wrinkles are very likely to occur when compounded with rubber, which seriously shortens the service life of the long-stroke pneumatic rubber diaphragm. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a preparation method of a long-stroke pneumatic rubber diaphragm, which can solve the wrinkle problem generated when the long-stroke pneumatic rubber diaphragm curtain is compounded with rubber and can be used in harsh environments for a long time.

[0006] The technical solution adopted by the present invention to solve the above technical problems is to provide a preparation method of a large-stroke pneumatic rubber diaphragm, wherein an aramid cord fabric is prepared by a weft knitting method, and the prepared aramid cord fabric is clamped on the surface or inside of the rubber as a diaphragm. The specific preparation steps are as follows: S1) loom selection, using a double-sided large-circle knitting machine to weave aramid yarn; S2) yarn feeding, dividing the aramid yarn into three strands, and using three yarn feeding wheels to merge into one hole to feed the yarn; S3) line length setting, adjusting the line length to 46cm / 100 needles; S4) cloth roll rack tension adjustment, adjusting the tightness to A8 gear; S5) post-finishing, adjusting the width of the shaping machine to 195-205cm, and adjusting the shaping drop The machine width is 215-225cm; S6) Aramid cord fabric dipping treatment, the aramid cord fabric made by weft knitting is evenly immersed in the glue, and after being smoothed, it is naturally dried at room temperature for 24h-48h, or dried in a drying oven at 40℃-50℃ for 4h-8h; S7) Rubber film preparation, the rubber is thinned through an open rubber mixer for 5-8 times and then produced into sheets, and the thickness of the film is produced according to the thickness requirements of different processes; S8) Sheet cutting, the aramid cord fabric and the film are cut into circular sheets of different diameters according to different specifications; S9) Sheet molding, according to the needs of different processes, the cut sheets are put into the mold in turn for vulcanization molding.

[0007] In the above-mentioned method for preparing the long-stroke pneumatic rubber diaphragm, the loom is a 12-gauge double-sided large-circle knitting machine.

[0008] In the above-mentioned method for preparing a large-stroke pneumatic rubber diaphragm, the aramid filaments are aramid filaments.

[0009] In the above-mentioned method for preparing a large-stroke pneumatic rubber diaphragm, the aramid yarn has a density of 200D per strand.

[0010] In the above-mentioned method for preparing a large-stroke pneumatic rubber diaphragm, the glue in step S6 is proportioned by mass as follows:

[0011]

[0012] In the above-mentioned method for preparing a large-stroke pneumatic rubber diaphragm, the thickness of the film in step S7 is 1 mm to 4 mm.

[0013] In the above-mentioned method for preparing a large-stroke pneumatic rubber diaphragm, the diameter of the circular sheet in step S8 is 400 mm to 1000 mm.

[0014] The above-mentioned preparation method of the large-stroke pneumatic rubber diaphragm, wherein, in step S9, the rubber film is first placed, and then the aramid curtain is placed; or the aramid curtain is first placed, and then the rubber film is placed; or both are placed at the same time; the temperature range is controlled to be 150°C to 160°C, the time is 60 to 300 minutes, and the pressure is 15 to 20MPa.

[0015] Compared with the prior art, the present invention has the following beneficial effects: the preparation method of the long-stroke pneumatic rubber diaphragm provided by the present invention forms a dedicated line through a specific weft knitting process, so that the woven aramid cord fabric has high strength and firmness, good elasticity and extensibility, no hairiness, horizontal stripes and fancy needles are generated on the cloth surface, the needle breakage rate can be minimized, and the cord fabric production efficiency and yield rate are greatly improved. The aramid cord fabric woven by this process is used in the process of forming the long-stroke pneumatic rubber diaphragm, which can effectively solve the wrinkle problem of the cord fabric and rubber composite. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram of the structure of a large-stroke pneumatic rubber diaphragm of the present invention;

[0017] Figure 2 The figure is a schematic diagram of the preparation process of the large-stroke pneumatic rubber diaphragm of the present invention. DETAILED DESCRIPTION

[0018] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0019] In order to solve the wrinkle problem caused by the compounding of the long-stroke pneumatic rubber diaphragm curtain with rubber, the present invention has found through continuous selection and experimental verification that the curtain made by the knitting method has the effect of improving wrinkles, but not all knitting methods can play an improvement role. The knitting method uses a crochet needle to bend the yarn into a loop and string it together, which is divided into two categories: warp knitting and weft knitting. The curtain made by the knitting method is elastic. The present invention found in the experiment that the curtain made by the warp knitting method is used in the molding of long-stroke pneumatic rubber diaphragms, because of its relatively small elasticity and insufficient extensibility, it cannot solve the wrinkle problem. The curtain made by the weft knitting method has relatively good elasticity and good extensibility, which has a significant effect on improving wrinkles, but its firmness is not as good as the warp knitting method.

[0020] See also Figure 2 The invention provides a method for preparing a large-stroke pneumatic rubber diaphragm, wherein an aramid cord is prepared by a weft knitting method, and the prepared aramid cord is used as a diaphragm and is attached to the surface or inside of the rubber. The specific preparation steps are as follows:

[0021] S1) Loom selection: double-sided large-loop loom is used to weave aramid yarn;

[0022] S2) feeding yarn, dividing the aramid yarn into three strands, and using three yarn feeding wheels to merge into one hole to feed the yarn;

[0023] S3) Thread length setting, adjust to 46cm / 100 stitches;

[0024] S4) Adjust the tension of the cloth roll frame to A8;

[0025] S5) After finishing, adjust the width of the upper machine to 195-205cm, and adjust the width of the lower machine to 215-225cm;

[0026] S6) Aramid cord fabric dipping treatment: the aramid cord fabric obtained by weft knitting is evenly immersed in a special adhesive, and after being smoothed, it is naturally dried at room temperature for 24 hours to 48 hours, or dried in a drying oven at 40°C to 50°C for 4 hours to 8 hours;

[0027] S7) Preparation of rubber sheets: the rubber is thinned through an open rubber mixer for 5 to 8 times before being produced into sheets. The thickness of the sheets is determined by the thickness required by different processes.

[0028] S8) Sheet cutting: cutting the aramid cord fabric and the film into circular sheets of different diameters according to different specifications;

[0029] S9) Sheet forming: according to different process requirements, the cut sheets are placed into the mold in sequence and vulcanized under certain temperature, time and pressure conditions.

[0030] The advantages of this weaving process are: by forming a dedicated line, the woven aramid cord fabric has high strength and firmness, good elasticity and extensibility, no hairiness, horizontal stripes and fancy needles on the fabric surface, the needle breakage rate can be minimized, and the cord fabric production efficiency and yield rate are greatly improved. The aramid cord fabric woven by this process is used in the large-stroke pneumatic rubber diaphragm molding process to effectively solve the wrinkle problem of the cord fabric 1 and rubber 2. Figure 1 shown.

[0031] The preparation method of the long-stroke pneumatic rubber diaphragm provided by the present invention is preferably that the loom is a 12-gauge double-sided large-circle knitting machine; the aramid material is an aramid long-fiber material, and the aramid yarn is 200D per strand.

[0032] As a preference but not limitation, the aramid cord fabric can be woven in a workshop environment with a temperature of 20-30° C. and a relative humidity of 60-75%.

[0033] As a preference but not limitation, the glue in step S6 is formulated in the following proportions by mass:

[0034]

[0035] As a preference but not limitation, the thickness of the film in step S7 is 1 mm to 4 mm.

[0036] As a preference but not limitation, the diameter of the circular sheet in step S8 is 400 mm to 1000 mm.

[0037] As a preference but not limitation, in step S9, the rubber film is first placed, and then the aramid cord fabric is placed; or the aramid cord fabric is first placed, and then the rubber film is placed; or both are placed at the same time; the temperature range is controlled to be 150°C to 160°C according to different specifications, the time is 60 to 300 minutes, and the pressure is 15 to 20 MPa.

[0038] Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art may make some modifications and improvements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be based on the definition of the claims.

Claims

1. A method for preparing a large-stroke pneumatic rubber diaphragm, characterized in that: The aramid cord fabric is prepared by a weft knitting method, and the prepared aramid cord fabric is sandwiched on the surface or inside of the rubber as a diaphragm. The specific preparation steps are as follows: S1) Loom selection: double-sided large-loop loom is used to weave aramid yarn; S2) feeding yarn, dividing the aramid yarn into three strands, and using three yarn feeding wheels to merge into one hole to feed the yarn; S3) Thread length setting, adjust to 46cm / 100 stitches; S4) Adjust the tension of the cloth roll frame to A8; S5) After finishing, adjust the width of the upper machine to 195-205cm, and adjust the width of the lower machine to 215-225cm; S6) aramid cord fabric dipping treatment, the aramid cord fabric obtained by weft knitting is uniformly immersed in the adhesive, and after being arranged and leveled, it is naturally dried at room temperature for 24h to 48h, or dried in a drying oven at 40℃ to 50℃ for 4h to 8h; S7) Preparation of rubber sheets: the rubber is thinned through an open rubber mixer for 5 to 8 times before being produced into sheets. The thickness of the sheets is determined by the thickness required by different processes. S8) Sheet cutting: cutting the aramid cord fabric and the film into circular sheets of different diameters according to different specifications; S9) Sheet forming: according to different process requirements, the cut sheets are placed in the mold in turn for vulcanization forming.

2. The method for preparing a long-stroke pneumatic rubber diaphragm according to claim 1, characterized in that: The loom is a 12-gauge double-sided large-circle knitting machine.

3. The method for preparing a long-stroke pneumatic rubber diaphragm according to claim 1, characterized in that: The aramid yarn is aramid filament.

4. The method for preparing a long-stroke pneumatic rubber diaphragm according to claim 1, characterized in that: The aramid yarn has 200D per strand.

5. The method for preparing a long-stroke pneumatic rubber diaphragm according to claim 1, characterized in that: The glue in step S6 is formulated in the following proportions by mass:

6. The method for preparing a long-stroke pneumatic rubber diaphragm according to claim 1, characterized in that: The thickness of the film in step S7 is 1 mm to 4 mm.

7. The method for preparing a long-stroke pneumatic rubber diaphragm according to claim 1, characterized in that: In step S8, the diameter of the circular sheet is 400 mm to 1000 mm.

8. The method for preparing a long-stroke pneumatic rubber diaphragm according to claim 1, characterized in that: In step S9, the rubber film is first put in, and then the aramid cord fabric; or the aramid cord fabric is first put in, and then the rubber film; or both are put in at the same time; the temperature range is controlled to be 150° C. to 160° C., the time is 60 to 300 minutes, and the pressure is 15 to 20 MPa.

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