Production method of wear-resistant high-frequency screen

Abstract

The invention relates to a production method of a wear-resistant high-frequency sieve, belongs to the technical field of wear-resistant high-frequency sieves, and discloses the production method of the wear-resistant high-frequency sieve, which comprises the following steps of: cutting, punching, rolling and welding a steel wire into a sieve plate framework; the preparation method comprises the following steps: carrying out chain extension on a prepolymer containing polytetrafluoroethylene micro powder, which is prepared by taking polycaprolactone diol and diphenylmethane diisocyanate as raw materials, through a DMTDA (Dimethylthio-toluenediamine) chain extender, putting the prepolymer into a sieve plate framework in a pouring mold at 115-120 DEG C, and carrying out normal-pressure pouring, curing and post-curing, so as to obtain the polyurethane pouring sieve plate with high abrasive resistance. The high-frequency sieve plate grinding strip has good elasticity and weather resistance and excellent tear resistance and wear resistance, the sieve plate grinding strip of the high-frequency sieve can be replaced every 24-30 months after being manufactured, the service life is longer, and the maintenance cost is lower. By adding the polytetrafluoroethylene micro powder, the high-frequency screen has good wear resistance and certain self-lubricating performance, and the wear resistance of the high-frequency screen is improved.

Description

Technical Field

[0001] The invention relates to the technical field of wear-resistant high-frequency screens, and in particular to a production method of a wear-resistant high-frequency screen. Background Art

[0002] In the past, sedimentation filtration centrifuges had strict requirements on feed concentration. When the concentration was low, the water content of the discharged material was large, causing the moisture content of the screened coal to exceed the standard. When the feed concentration was high, the centrifuge was prone to cutting failure. Because the screen bars are pasted with ceramic sheets, the most feared thing is that there are iron debris such as nuts, bolts, and welding rod heads in the coal slurry water. If iron debris enters the centrifuge, the screen bars will be damaged and the centrifuge will have a "diarrhea phenomenon", that is, the water content of the discharged material is too high. The use of high-frequency screens and coal slurry centrifuges instead of sedimentation filtration centrifuges has large processing capacity for recovering coarse coal slurry, low product moisture, simple process equipment, low operating costs, and simple operation and maintenance. Because the screen basket of the coal slurry centrifuge is made of stainless steel wear-resistant strips and is replaced every 4 to 6 months, the high-frequency screen and coal slurry centrifuge have more advantages in terms of maintenance costs and difficulty. However, the polyurethane screen plate used in the screen plate of the high-frequency screen needs to be replaced every 12 to 18 months, and the wear resistance still needs to be improved. In summary, it is necessary to develop a production method for wear-resistant high-frequency screens. Summary of the invention

[0003] In view of the problems existing in the above-mentioned prior art, the present invention aims to provide a production method of a wear-resistant high-frequency screen.

[0004] A production method of a wear-resistant high-frequency screen comprises the following steps: a first step, cutting, punching, rolling and welding steel wires into a screen plate skeleton; a second step, adding dehydrated polyester polyol into a reaction kettle, adding diphenylmethane diisocyanate under stirring, reacting for 10-30 minutes, then heating to 90-100°C, continuing to react for 2-3 hours, until the -NCO content of the system is 4.6%-5.1%, uniformly dispersing polytetrafluoroethylene powder therein to obtain a polyurethane prepolymer; a third step, uniformly mixing the polyurethane prepolymer with a dimethylthiotoluene diamine chain extender at 80°C, extending the chain at a chain extension coefficient of 0.9-0.95, and obtaining a cast polyurethane elastomer; a fourth step, using the cast polyurethane elastomer for casting molding, placing the screen plate skeleton in a casting mold at 115-120°C, casting at normal pressure, aging, and post-aging, and obtaining a polyurethane cast screen plate with high wear resistance.

[0005] Furthermore, the polyester polyol is a polycaprolactone diol having a number average molecular weight of 1000-3000.

[0006] Furthermore, the mass ratio of the polytetrafluoroethylene powder in the second step to the polyurethane liquid is 0.5% to 0.7%.

[0007] Furthermore, the second step polytetrafluoroethylene powder has an average particle size of 4 μm to 12 μm and a specific surface area of ​​8 m2 / g~12m 2 / g of polytetrafluoroethylene powder.

[0008] Furthermore, the fourth step of aging is performed at a temperature of 110°C to 120°C for a time of 1 hour to 1.5 hours. Furthermore, the fourth step post-aging temperature is 110° C. to 120° C., and the time is 12 h to 18 h.

[0009] Beneficial effects of the present invention: The present invention discloses a production method of a wear-resistant high-frequency screen, which adopts steel wire cutting, punching, wire rolling and welding to form a screen plate skeleton; a prepolymer containing polytetrafluoroethylene powder prepared from polycaprolactone diol and diphenylmethane diisocyanate as raw materials is chain extended by DMTDA dimethylthiotoluenediamine chain extender, and the screen plate skeleton is placed in a casting mold at 115-120°C, and cast, matured and post-matured at normal pressure to obtain a polyurethane casting screen plate with high wear resistance, high tensile strength, flexibility, good elasticity and weather resistance, excellent tear resistance and wear resistance, and the screen plate grinding strip of the high-frequency screen can be extended to 24-30 months after manufacture, with longer service life and lower maintenance costs. The addition of polytetrafluoroethylene powder gives the high-frequency screen good wear resistance, has certain self-lubricating properties, and improves the wear resistance of the high-frequency screen. DETAILED DESCRIPTION

[0010] The present invention is described below with specific examples, but is not intended to be limiting of the present invention. Example 1

[0011] Raw materials: Jiangxi Zhongtong Chemical Industry, average particle size 4μm, specific surface area 8m 2 / g JTW polytetrafluoroethylene powder. Yisheng New Materials polycaprolactone diol PCL210N with a number average molecular weight of 1000. Hai Ruibao DMTDA dimethylthiotoluene diamine; diphenylmethane diisocyanate MDI-100AH.

[0012] A production method of a wear-resistant high-frequency screen comprises the following steps: the first step is to cut, punch, roll and weld steel wires into a screen plate skeleton; the second step is to add dehydrated polyester polyol into a reaction kettle, add diphenylmethane diisocyanate under stirring, react for 10 minutes, then heat to 90°C, continue to react for 2 hours, and when the -NCO content of the system is 4.6%, uniformly disperse polytetrafluoroethylene powder therein to obtain a polyurethane prepolymer, and the mass proportion of polytetrafluoroethylene powder in the polyurethane liquid is 0.5%; Step 3: Mix the polyurethane prepolymer and the 80℃ dimethylthiotoluene diamine chain extender evenly, and extend the chain at a chain extension coefficient of 0.9 to obtain a cast polyurethane elastomer; Step 4: Use the cast polyurethane elastomer for casting, put a 115℃ sieve plate skeleton into the 115℃ casting mold, cast at normal pressure, mature, and post-mature, and obtain a high wear-resistant polyurethane cast sieve plate, the aging temperature is 110℃, the time is 1h, and the post-mature temperature is 110℃, the time is 12h. Steel wire Q235A, its nominal diameter is 12.50mm, the maximum out-of-roundness is 0.08mm, and the tensile strength is 1800MPa. Example 2

[0013] Raw materials: PCL230B polycaprolactone diol with a number average molecular weight of 3000 from Yisheng New Materials. DMTDA (SD-30) from Leling Chuangli; Tianyuxiang Micro Powder Factory with an average particle size of 12μm and a specific surface area of ​​12m 2 / g polytetrafluoroethylene powder; diphenylmethane diisocyanate MDI-1102.

[0014] A production method for a wear-resistant high-frequency screen comprises the following steps: the first step is to cut, punch, roll and weld steel wires into a screen plate skeleton; the second step is to add dehydrated polyester polyol into a reaction kettle, add diphenylmethane diisocyanate under stirring, react for 30 minutes, then heat to 100°C, continue to react for 3 hours, and when the -NCO content of the system is 5.1%, uniformly disperse polytetrafluoroethylene powder therein to obtain a polyurethane prepolymer, and the mass proportion of polytetrafluoroethylene powder in the polyurethane liquid is 0.7%; Step 3: Evenly mix the polyurethane prepolymer with the 80℃ dimethylthiotoluene diamine chain extender, and extend the chain at a chain extension coefficient of 0.95 to obtain a cast polyurethane elastomer; Step 4: Casting the cast polyurethane elastomer, place a 120℃ sieve plate skeleton in a 120℃ casting mold, cast at normal pressure, mature, and post-mature, to obtain a high wear-resistant polyurethane cast sieve plate, the aging temperature is 120℃, the time is 1.5h, the post-mature temperature is 120℃, and the time is 18h. Steel wire Q235A, its nominal diameter is 12.50mm, the maximum out-of-roundness is 0.08mm, and the tensile strength is 1800MPa.

[0015] The wear-resistant high-frequency sieve plates of Examples 1 and 2 were subjected to performance testing. The performance test results are shown in Table 1. Table 1 Wear-resistant high-frequency sieve plate performance test results of Example 1 and Example 2

[0016] Note: Refer to GB / T33091-2016 polyurethane sieve plate.

Claims

1. A method for producing a wear-resistant high-frequency screen, characterized in that: The following steps are involved: The first step is to cut, punch, roll and weld the steel wire into a screen plate skeleton; the second step is to add the dehydrated polyester polyol into the reactor, add diphenylmethane diisocyanate under stirring, react for 10min to 30min, then heat up to 90 to 100°C, continue to react for 2h to 3h, until the -NCO content of the system is 4.6% to 5.1%, uniformly disperse the polytetrafluoroethylene powder therein to obtain a polyurethane prepolymer; the third step is to uniformly mix the polyurethane prepolymer with the 80°C dimethylthiotoluene diamine chain extender, extend the chain at a chain extension coefficient of 0.9 to 0.95, and obtain a cast polyurethane elastomer; the fourth step is to use the cast polyurethane elastomer for casting, place the screen plate skeleton in a casting mold at 115 to 120°C, cast at normal pressure, mature, and post-mature, and obtain a polyurethane cast screen plate with high wear resistance.

2. The method for producing a wear-resistant high-frequency screen according to claim 1, characterized in that: The polyester polyol is a polycaprolactone diol with a number average molecular weight of 1000-3000.

3. The method for producing a wear-resistant high-frequency screen according to claim 1, characterized in that: In the second step, the mass ratio of the polytetrafluoroethylene powder to the polyurethane liquid is 0.5% to 0.7%.

4. The method for producing a wear-resistant high-frequency screen according to claim 1, characterized in that: The second step polytetrafluoroethylene powder has an average particle size of 4 μm to 12 μm and a specific surface area of ​​8 m 2 / g~12m 2 / g of polytetrafluoroethylene powder.

5. The method for producing a wear-resistant high-frequency screen according to claim 1, characterized in that: The fourth step of aging has a temperature of 110° C. to 120° C. and a time of 1 h to 1.5 h.

6. The method for producing a wear-resistant high-frequency screen according to claim 1, characterized in that: The fourth step post-aging temperature is 110° C. to 120° C., and the time is 12 h to 18 h.

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