阅读说明：本技术 一种模压栅板制造工艺 (Die pressing grid plate manufacturing process ) 是由 王旭卫 于 2019-11-28 设计创作，主要内容包括：本发明公开了一种模压栅板制造工艺,包括步骤一：在钢制模具上铺设PTFE粉末,在PTFE粉末上嵌入钢骨架；步骤二：在PTFE粉末和钢骨架上再铺设一层PTFE粉末；步骤三：在钢制模具中间套入皮囊模型,在皮囊模型内接入28-60Mpa的水压,对PTFE粉末打压成型；步骤四：去除格栅位置中的PTFE粉末；步骤五：在栅格位置中放入填充物；步骤六：将钢制模具放在炉中烧结成型。通过上述工艺,在烧结前,先用皮囊模型进行水压压缩,使PTFE的粉末更加致密,减小粉末间的间隙,减小烧结时粉末的收缩变形,从而使栅板在成型后力学性能更好,抗形变和承重能力更强；且在收缩变形缩小后,栅板的表面更加光洁,能承受介质冲刷的时间更长,提高栅板的使用寿命。(The invention discloses a die pressing grid plate manufacturing process, which comprises the following steps: laying PTFE powder on a steel mould, and embedding a steel skeleton on the PTFE powder; step two: a layer of PTFE powder is paved on the PTFE powder and the steel skeleton; step three: sleeving a leather bag model in the middle of a steel mould, and connecting 28-60Mpa of water pressure in the leather bag model to press and form PTFE powder; step four: removing the PTFE powder in the grid locations; step five: placing a filler in the grid location; step six: and (4) placing the steel mould in a furnace for sintering and forming. Through the process, before sintering, the leather bag model is used for hydraulic compression, so that PTFE powder is more compact, gaps among the powder are reduced, and shrinkage deformation of the powder during sintering is reduced, so that the grid plate is better in mechanical property after molding, and higher in deformation resistance and bearing capacity; and after the shrinkage deformation is reduced, the surface of the grid plate is smoother, the time for bearing the medium scouring is longer, and the service life of the grid plate is prolonged.)

1. A manufacturing process of a die-pressed grid plate is characterized by comprising the following steps: comprises that

The method comprises the following steps: laying PTFE powder on a steel mould, and embedding a steel skeleton on the PTFE powder;

step two: a layer of PTFE powder is paved on the PTFE powder and the steel skeleton;

step three: sleeving a leather bag model in the middle of a steel mould, and connecting 28-60Mpa of water pressure in the leather bag model to press and form PTFE powder;

step four: removing the PTFE powder in the grid locations;

step five: placing a filler in the grid location;

step six: and (4) placing the steel mould in a furnace for sintering and forming.

2. The process of making a stamped grid as claimed in claim 1, wherein: the sintering temperature in the sixth step is 360-380 ℃, the sintering pressure is 10-25Mpa, and the heat preservation time is 9-12 hours.

3. The process of making a stamped grid as claimed in claim 2, wherein: and sixthly, the sintering temperature is linear temperature, the temperature rising speed is 30-40 ℃/h, the temperature is reduced after the temperature reaches the upper limit, the temperature reduction speed is 15-24 ℃/h, the temperature is kept for 9-12 h when the temperature is reduced to 315 ℃, and the temperature is cooled at room temperature after the temperature is kept.

4. The process of making a stamped grid as claimed in claim 1, wherein: the water pressure in the third step is 29-35Mpa, and the pressure maintaining time is 0.25-1 h.

5. The process of making a stamped grid as claimed in claim 1, wherein: the filler is industrial salt.

Technical Field

The invention relates to a steel-embedded die pressing process, in particular to a die pressing grid plate manufacturing process.

Background

Compression molding (also called compression molding or compression molding) is an operation of putting powdery, granular or fibrous plastic into a mold cavity at a molding temperature, and then closing the mold and pressurizing to mold and solidify the plastic.

The PTFE embedded steel die grid plate is a large-area grid plate and is commonly used on pipelines and pressure containers under various working conditions. The volume of the die pressing grid plate manufactured by the common die pressing process is reduced more in the sintering process, and the deformation resistance and the bearing capacity of the die pressing grid plate are greatly influenced.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide a die pressing grid plate manufacturing process which can reduce the shrinkage rate of the grid plate after sintering and forming.

In order to achieve the purpose, the invention provides the following technical scheme: a manufacturing process of a die-pressed grid plate is characterized by comprising the following steps: comprises that

The method comprises the following steps: laying PTFE powder on a steel mould, and embedding a steel skeleton on the PTFE powder;

step two: a layer of PTFE powder is paved on the PTFE powder and the steel skeleton;

step three: sleeving a leather bag model in the middle of a steel mould, and connecting 28-60Mpa of water pressure in the leather bag model to press and form PTFE powder;

step four: removing the PTFE powder in the grid locations;

step five: placing a filler in the grid location;

step six: and (4) placing the steel mould in a furnace for sintering and forming.

As a further improvement of the invention, the sintering temperature in the sixth step is 360-380 ℃, the sintering pressure is 10-25Mpa, and the heat preservation time is 9-12 hours.

As a further improvement of the invention, the sintering temperature in the sixth step is linear temperature, the temperature rising speed is 30-40 ℃/h, the temperature is reduced after the temperature reaches the upper limit, the temperature reduction speed is 15-24 ℃/h, the temperature is kept for 9-12 h when the temperature is reduced to 315 ℃, and the temperature is cooled at room temperature after the temperature is kept.

As a further improvement of the invention, the water pressure in the third step is 29-35Mpa, and the pressure maintaining time is 0.25-1 hour.

As a further improvement of the invention, the filler is industrial salt.

The process has the beneficial effects that through the process, before sintering, the leather bag model is firstly used for hydraulic compression, so that PTFE powder is more compact, gaps among the powder are reduced, and shrinkage deformation of the powder during sintering is reduced, so that the grid plate is better in mechanical property after molding, and stronger in deformation resistance and bearing capacity; and after the shrinkage deformation is reduced, the surface of the grid plate is smoother, the time for bearing the medium scouring is longer, and the service life of the grid plate is prolonged.

Drawings

FIG. 1 is a schematic structural view of a molded grid.

Detailed Description

The invention will be described in further detail below with reference to the model shown in fig. 1.

The manufacturing process of the die pressing grid plate is characterized in that: comprises that

The method comprises the following steps: laying a layer of flat-plate-shaped PTFE powder on a steel mould, and embedding a steel skeleton on the PTFE powder;

step two: laying a layer of PTFE powder on the PTFE powder and the steel skeleton to form a flat plate blank;

step three: sleeving a leather bag model in the middle of the steel mould, and connecting 25-60Mpa of water pressure in the leather bag model to press and form the PTFE powder blank plate;

step four: removing the PTFE powder in the grid locations;

step five: putting industrial salt as a filler in the position of the grating;

step six: and (4) placing the steel mould in a furnace for sintering and forming.

In the sixth step, the sintering temperature is 330-380 ℃, the sintering pressure is 25-30Mpa, and the heat preservation time is 2-5 hours.

The pressure maintaining time of the water pressure in the third step is 0.25-1 hour.

Through the process, before sintering, the leather bag model is used for hydraulic compression, so that PTFE powder is more compact, gaps among the powder are reduced, and shrinkage deformation of the powder during sintering is reduced, so that the grid plate is better in mechanical property after molding, and higher in deformation resistance and bearing capacity; and after the shrinkage deformation is reduced, the surface of the grid plate is smoother, the time for bearing the medium scouring is longer, and the service life of the grid plate is prolonged. The shrinkage rate of PTFE is 3.1% -5% in general, and the shrinkage rate can be reduced to 2.1% -2.5% by the process of first pressure molding and then pressure sintering. In the grid plate manufacturing process, water is added for molding, so that the shrinkage rate of PTFE after sintering can be effectively reduced, wherein the shrinkage rate refers to the change of the volume of a finished product after sintering. When the pressure reaches 25MPa during hydraulic molding, a better molding effect can be achieved within a shorter time, and when the pressure is greater than 35MPa, local structural damage is easy to occur, so that the better molding effect cannot be achieved, the structural damage is different according to materials, and copper powder or other substances are doped into PTFE, so that the parameter can reach 50-60 MPa. The pressure maintaining time of the hydraulic molding is also the key of the molding, and a more compact surface structure can be obtained by maintaining pressure for more than 15 minutes. The filler is placed in the grid position to prevent inward shrinkage of the grids during sintering, thereby reducing inward shrinkage of the grids. The filler is selected to be industrial salt, the grid can be filled with the industrial salt, gaps are avoided during filling, and the situation that the surface quality is low after molding is avoided. And the temperature rise is slower during sintering of the industrial salt, similar to PTFE, local high temperature cannot be generated in the PTFE, and the stable operation of the sintering process is ensured. The maximum sintering temperature is not more than 380 ℃, and is preferably 360-380 ℃, the sintering process is a linear temperature control process, and different sintering processes are adopted according to the doped substances, the sizes of finished products and the particle sizes of raw materials. In the invention, the temperature rising speed of sintering is preferably 30-40 ℃/h, the temperature begins to be reduced after the temperature is reduced to 380 ℃, the temperature reduction speed is preferably 15-24 ℃/h, and when the temperature is reduced to about 315 ℃, the temperature is kept for more than 9 hours, so that the materials in the die are fully melted and mixed. And after the heat preservation is finished, slowly cooling to the room temperature to finish the sintering of the product.

The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above-mentioned embodiments, and all technical solutions belonging to the idea of the present invention belong to the protection scope of the present invention. It should be noted that modifications and embellishments within the scope of the invention may occur to those skilled in the art without departing from the principle of the invention, and are considered to be within the scope of the invention.