Method of producing sheet reinforced antifriction fluoroplastic billets

FIELD: process engineering.

SUBSTANCE: invention may be used for production of long sheet reinforced fluoroplastic billets for friction assembly operated without lubrication. Polydisposed polymer film is produced from fluoroplastic-4 or from compositions based thereon. Strip mesh power are filled by said film by rolling said film on both sides. Produced sheets are wound on rolls to be fitted in limiting mandrels with no clearance. Billets are sintered at 643-653 K and pressure developed by expansion of fluoroplastic-4 and cooled down thereafter. Billets are withdrawn from mandrels and passed through rolls.

EFFECT: simplified procedure, expanded range of products.

2 ex

 

The invention relates to the field of anti-friction, self-lubricating materials and can be used in machine building, food processing, aviation, instrument, chemical and other fields of technology for friction without lubrication.

A method of obtaining metallobiomolecules material [SU A, C08F 29/16, 12.09.1972 /2/], which allows to create a composite cast-in-wire spatial grid of fine metals of lead or tin or their alloys and Nickel particles. This method improves the conductivity of the fluoropolymer composition, but does not increase operational characteristics of filled PTFE materials.

The closest analogue is the way to obtain sheet reinforced PTFE antifriction material, including the production of non-oriented polymer film fluoroplast-4 or of compositions based on it, filling in the specified film then grid in the form of a strip through a roll of film on rolls with both sides receiving sheet blanks, the Assembly sheet blanks in the package, fixed in the frame, sintering the sheet blanks in the batch at a temperature 643-653 To the pressure created by the expansion of fluoroplast-4, and disassembly of the package [U.S. Pat. No. 2384412 RF, MKI 7 WW 5/02, VS 44/00].

The disadvantage of this method is the I, that the method used does not allow to get sheet products of large dimensions, as increasing amounts of detail requires special large equipment during sintering and snap (bounding plane-parallel plate at a temperature subjected to warping, lifts and other), and the process is time-consuming.

The technical result of the invention is obtaining a long sheet of reinforced PTFE anti-friction billet-bands that can significantly increase the productivity of the process up to automate and expand the product range.

The technical result is achieved by the fact that the proposed method of producing reinforced sheet PTFE anti-friction billet includes the production of non-oriented polymer film fluoroplast-4 or of compositions based on it, filling in the specified film then grid in the form of a strip through a roll of film on a roll mill with two sides, sintering the obtained sheet blanks at a temperature 643-653 To the pressure created by the expansion of fluoroplast-4 and cooling, according to the invention before sintering sheet is wound on a reel and placed within the bounding frame without a gap, and after cooling, removed from the mandrel and feed them through rollers.

the manual receiving sheet reinforced PTFE anti-friction billet can be implemented as follows. Pressing blanks of the required size fluoroplast-4 or its compositions is carried out at a pressure of 25-50 MPa for the pure polymer and 35-100 MPa for songs. Sintering is carried out at a temperature 643-653 in air atmosphere. Unoriented polymer film get on lathes using standard technology. The thickness of the cut film may be different and is chosen empirically so as to ensure complete filling of the pores of the mesh.

As a reinforcing element can be used bronze, brass and bronzestone grid different numbers and types of tissue.

Filling the pores of the mesh unoriented polymer film is performed on rollers from two sides at once.

When rolling the unoriented fluoropolymer film to the grid violated its continuity, which is restored at the expense of diffusion processes occurring at the temperature of heat treatment, but inside the porous metal layer. This restoration of the continuity of the film is possible only if the convergence of the particles due to the pressure created by the expansion of fluoroplast-4 at sintering temperature in a confined space.

Cooked long sheet reinforced strip is wound on a cylindrical bobbin with strips of aluminum foil and set in limiting the edits without a clearance. Limited thus reinforced sheet strips are placed in an oven for sintering the PTFE is heated with a speed of 100-120 degrees per hour to a temperature of 643-653 To and kept at this temperature for 3.5-4 h in air atmosphere for every 100 mm of thickness.

When the heat of the molten polymer particles further penetrate the pores, converging and are sintered with each other to form a monolithic PTFE layer.

The cooling sheet of reinforced strips are in limiting the mandrel together with the microwave, and then disconnect the cable and remove the strip and passed through the rollers. Upon cooling, the fluoropolymer matrix is sealed and secured in the cells, macromolecules are oriented, which provides a high physico-mechanical and tribological properties of the material.

Below are examples of the implementation of the proposed method.

Example 1. As a reinforcing element used Braselton grid N 16 (the number of wires in a duck 1 cm - 16, diameter 0.25 mm, the number of wires on the basis of 1 cm - 12, the diameter of 0.27 mm) (GOST 3583-73). Mesh cut strips along the entire length of the roll. Filling unoriented polymer film fluoroplast-4 in the grid was carried out on rollers from two sides simultaneously. The thickness Vityaev unoriented film on one side was equal to 0.3 mm, on the other 0.2 mm (pdbi the Ali empirically), which ensures complete filling of the pores of the mesh polymer. Cooked long reinforced PTFE strip grid was wound on a cylindrical bobbin with an intermediate layer of aluminum foil, then set in the bounding frame without a clearance. The size of the frame depends on the length of the wound strip and is determined empirically.

Limited thus reinforced sheet strips were placed in a furnace for sintering of PTFE, was heated with a speed of 100-120 degrees per hour to a temperature of 643-653 To and kept at this temperature for 3.5-4 h in air atmosphere for every 100 mm of thickness.

The cooling sheet of reinforced strips were in limiting the mandrel together with the microwave, then cut off the mandrel and removed the strip and passed through the rollers.

Example 2. As a reinforcing element used Braselton grid N 16. Mesh cut strips along the entire length of the roll.

Filling unoriented polymer film of the fluoropolymer composition (60 wt.% PTFE+40 wt.% Pb) in the grid was carried out on rollers from two sides simultaneously. The thickness Vityaev unoriented film on one side was equal to 0.3 mm, with the other of 0.2 mm. Cooked long reinforced PTFE strip grid was wound on a cylindrical bobbin with an intermediate layer of aluminum is Olga, then set in the bounding frame without a clearance. Limited thus reinforced sheet strips were placed in a furnace for sintering of PTFE, was heated with a speed of 100-120 degrees per hour to a temperature of 643-653 To and kept at this temperature for 3.5-4 h in air atmosphere for every 100 mm of thickness.

The cooling sheet of reinforced strips were in limiting the mandrel together with the microwave, then cut off the mandrel and removed the strip and passed through the rollers.

Sheet reinforced PTFE anti-friction billet obtained by the proposed method can be used as long guides in various waterworks, support washers, bearings, bearings, ball joints and provide long-term performance of friction without lubricant in air and in various fluids which do not have lubricating properties.

A method of obtaining a sheet of reinforced PTFE antifriction blanks, including the production of non-oriented polymer film fluoroplast-4 or of compositions based on it, filling in the specified film then grid in the form of a strip through a roll of film on a roll mill with two sides, sintering the obtained sheet blanks at a temperature 643-653 To the pressure created by the expansion of fluoroplast-4,and cooling, characterized in that prior to sintering the sheet is wound on a reel and placed within the bounding frame without a gap, and after cooling, removed from the mandrel and feed them through rollers.



 

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