CN110815688A - Tube plate processing die and process - Google Patents

Abstract

The invention relates to a tube sheet processing mold and process, comprising a tube sheet blank and a FEP composite layer clamped on both sides of the tube sheet blank, the lower side of the FEP composite layer is provided with a lower mold, and the upper part of the FEP composite layer is There is an upper die on the side, flange holes are evenly distributed on the outer edge of the tube sheet blank, the upper die and the lower die are provided with through holes at the positions corresponding to the flange holes, and the upper die, the lower die and the tube sheet blank pass through the through holes bolts are inserted into the flange holes for fast connection; the middle part of the upper die is provided with a pressing plate. Compared with the prior art, the beneficial effects of the present invention are: 1. The sintering and molding process of the steel-lined FEP composite tube sheet fills the blank of the domestic silicon carbide heat exchanger tube sheet manufacturing technology, and completely solves the problem of creep of the PTFE tube sheet. problems, making the use of silicon carbide heat exchangers more stable and reliable. 2. The sintering and molding process of the steel-lined FEP composite tube sheet combines the fluoroplastic and the carbon steel substrate well, which solves the problem of weak adhesion between the PTFE material and the carbon steel substrate, which is easy to fall off and cause cracks.

Description

Tube sheet processing mold and technology

technical field

The invention relates to the technical field of composite tube sheet processing, in particular to a tube sheet processing mold and process.

Background technique

Silicon carbide has extremely high corrosion resistance, oxidation resistance and erosion resistance, and is resistant to high concentrations of sulfuric acid, nitric acid, phosphoric acid, mixed acid, strong alkali, oxidant, etc. It is the only ceramic material that can resist hydrofluoric acid corrosion. long life.

Silicon carbide heat exchangers as a new type of material used in chemical equipment manufacturing have not been widely promoted, mainly because the manufacturing technology of silicon carbide heat exchangers is not mature enough, especially the sealing between silicon carbide heat exchange tubes and heat exchanger tube sheets There are also defects in the form, which limit the application of silicon carbide heat exchangers under higher temperature and pressure conditions. Although the PTFE tube sheet can resist most acid and alkali corrosion and is a reliable anti-corrosion material, the mechanical strength of PTFE is greatly reduced at high temperature, and the expansion ratio of PTFE is higher than that of metal materials. The creep is much larger, and it is easy to deform at high temperature, resulting in an unsatisfactory sealing effect; at the same time, the silicon carbide heat exchange tube is easily squeezed and fractured during the shrinkage and deformation of the PTFE tube sheet. The equipment damage caused by the deformation of the PTFE tube sheet is an inevitable after-sales problem of the silicon carbide heat exchanger, which greatly increases the manufacturing cost of the silicon carbide heat exchanger and affects the customer's quality and credibility of the silicon carbide heat exchanger.

How to increase the mechanical strength of the PTFE tube sheet and improve the service temperature of the PTFE tube sheet has become a major problem in the manufacture of silicon carbide heat exchangers. FEP is a copolymer of tetrafluoroethylene and hexafluoropropylene. The content of hexafluoropropylene is about 15%. It is a modified material of polytetrafluoroethylene; FEP has similar characteristics to polytetrafluoroethylene and has thermoplastic properties. It has good processing properties, so it makes up for the lack of processing difficulties of PTFE, making it a material to replace PTFE. The steel-lined FEP composite tube sheet can greatly improve the operating pressure and operating temperature of the heat exchanger tube sheet, and better promote the application and promotion of silicon carbide heat exchangers in the chemical industry.

When adding reinforced steel parts to the existing molded PTFE tube sheet, it is necessary to completely pre-embed the reinforced steel parts into the PTFE powder for molding together and then demold and sinter at high temperature; since the reinforced steel parts are completely embedded in PTFE, It is impossible to accurately find the reference level and positioning center of the tube sheet lathe processing, and the drilling of the tube holes during the lathe processing can easily expose the steel base material and cause the tube sheet to be scrapped. After PTFE molding and sintering, the bonding force between PTFE and carbon steel reinforcements is insufficient due to the different warm-up rates, and cracks are easily formed at the junction of PTFE and carbon steel reinforcements.

SUMMARY OF THE INVENTION

In order to solve the above-mentioned problems in the prior art, the present invention provides a tube sheet processing mold and process. By designing a new mold, the flange hole part of the carbon steel base plate in the steel-lined FEP composite tube sheet can be exposed to the FEP composite tube sheet. On the outer side of the layer, CNC machining can be accurately positioned through the flange hole, which solves the problem of precise machining of the composite tube sheet. In addition, different from the cold pressing and hot sintering of mold PTFE, the steel-lined FEP composite tube sheet is produced by hot pressing after hot sintering. Since there is no experience in making steel-lined FEP composite tube sheets in China, a set of sintering molding process for steel-lined FEP composite tube sheets is designed to produce composite tube sheets that meet the sealing requirements of silicon carbide heat exchangers.

The technical scheme adopted by the present invention to solve its technical problems is:

A tube sheet processing mold, comprising a tube sheet blank and a FEP composite layer clamped on both sides of the tube sheet blank, the lower side of the FEP composite layer is provided with a lower mold, and the upper side of the FEP composite layer is provided with an upper mold , flange holes are evenly distributed on the outer edge of the tube sheet blank, the upper die and the lower die are provided with through holes at the positions corresponding to the flange holes, and the upper die, the lower die and the tube sheet blank pass through the through holes and the flange holes. Fastening connection through penetration bolts; the middle part of the upper die is movably connected with a pressing plate for extruding the FEP composite layer and the tube sheet blank to form a steel-lined FEP composite tube sheet, and the pressing plate is extruded by a molding machine, so that the FEP composite layer and The tubesheet stock is fused into a composite tubesheet.

Further, the positions of the upper mold and the lower mold corresponding to the FEP composite layer are provided with grooves, and the depth of the grooves is less than the height of the side steps of the steel-lined FEP composite tube sheet after forming, and the grooves are circular grooves, which are used for the FEP composite layer. The layers and tube sheet blanks are limited and fixed.

Preferably, the tube sheet blank is in the shape of a disc, and is made of carbon steel plate, stainless steel, alloy plate or aluminum plate and other materials.

Preferably, the FEP composite layer of the steel-lined FEP composite tube sheet can also be made of PFA or ETFE composite material.

A construction technique of the above-mentioned tube sheet processing mould, comprising the following construction steps:

a. Laminate the tube sheet blank and the FEP composite layer. The FEP composite layer consists of two layers, and the thickness of the sheet is ≤ 10mm. After processing and forming, the end face of the tube sheet with the sheet and the shell of the heat exchanger are connected correspondingly; the thickness of the thick plate is ≤ 50mm , After processing and forming, the end face of the tube sheet with the thick plate is connected to the head of the heat exchanger, which is mainly used for contacting with corrosive materials and exerting its corrosion resistance;

b. The upper and lower templates are clamped to the tube sheet blank and the FEP composite layer by bolts to form a clamp, and then the clamp is sent to the oven for heating;

b1. The oven is evenly heated to 280°C, and the duration is 3h;

b2. The oven is kept at 280℃ for 3h;

b3. The oven continues to heat up to 330°C evenly, and the duration is 2h;

b4. The oven is kept at 330℃ for N hours;

c. After sintering in the oven, the FEP pellets are in a semi-molten state, and there is no oxidation and blackening phenomenon. At this time, in order to meet the requirements of molding fluidity, transfer the clamping piece to the molding machine and start the molding work;

c1. Control the molding press to connect the stable pressing plate and start the pressing work;

c2. Pressurize evenly to 80barg/c㎡, during which time is 5h;

c3. The molding machine is kept for 5h under the pressure of 80barg/c㎡;

c4. The secondary pressure is up to 120barg/c㎡, and the duration is 5h;

c5. The molding machine is kept for N hours under the pressure of 120barg/c㎡;

d. When the pressure is maintained until the time is required, the mold can be opened by cooling to normal temperature naturally;

e. Finally, it is the steel-lined FEP composite tube sheet required for the installation of the silicon carbide heat exchanger after finishing by the demoulding lathe.

Preferably, the holding time in the step b4 is determined according to different specifications of the molded steel-lined FEP composite tube sheet.

Preferably, the pressure holding time in the step c5 is determined according to different specifications of the molded steel-lined FEP composite tube sheet.

Preferably, after the temperature rises in the pressurizing process of step c, a water mist spraying mold is used to cool the clamping member.

Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention provides a tube sheet processing die and process, which have the following advantages:

1. The sintering and molding process of steel-lined FEP composite tube sheet fills the blank of domestic silicon carbide heat exchanger tube sheet manufacturing technology, completely solves the problem of PTFE tube sheet creep, and makes the use of silicon carbide heat exchangers more stable and reliable.

2. The sintering and molding process of the steel-lined FEP composite tube sheet combines the fluoroplastic and the carbon steel substrate well, which solves the problem of weak adhesion between the PTFE material and the carbon steel substrate, which is easy to fall off and cause cracks.

Description of drawings

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

Fig. 1 is the structural representation of the present invention;

Fig. 2 is the sintering heating curve of the steel-lined FEP composite tube sheet of the present invention;

Fig. 3 is the pressure curve of the molding process of the steel-lined FEP composite tube sheet of the present invention.

In the picture: 1. Lower die, 2. Upper die, 3. Tube sheet blank, 4. FEP composite layer, 5. Press plate, 6. Flange hole, 7. Bolt.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention. Also, unless otherwise defined, technical or scientific terms used herein should have the ordinary meaning as understood by one of ordinary skill in the art to which this invention belongs. The terms "first", "second" and similar terms used in the description of the patent application and the claims of the present invention do not denote any order, quantity or importance, but are only used to distinguish different components. Likewise, words such as "a" or "an" do not necessarily imply a limitation of quantity. "Comprising" or "comprising" and similar words mean that the elements or things appearing before the word encompass the elements or things recited after the word and their equivalents, but do not exclude other elements or things. Words like "connected" or "connected" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "Down", "Left", "Right", etc. are only used to represent the relative positional relationship, and when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

Example 1

As shown in FIG. 1 , the present invention designs a tube sheet processing mold, which includes a tube sheet blank 3 and a FEP composite layer 4 clamped on both sides of the tube sheet blank 3. The lower side of the FEP composite layer 4 is provided with a lower mold 1. An upper die 2 is arranged on the upper side of the FEP composite layer 4, and flange holes 6 are evenly distributed on the outer edge of the tube sheet blank 3. The upper die 2 and the lower die 1 are arranged at the positions corresponding to the flange holes 6. There are through holes, and the upper die 2, the lower die 1 and the tube sheet blank 3 are fastened and connected by bolts 7 through the through holes and the flange holes; From the blank to the pressing plate 5 forming the steel-lined FEP composite tube sheet, the pressing plate 5 is extruded by a molding press, so that the FEP composite layer 4 and the tube sheet blank 3 are fused into a composite tube sheet.

Further, the positions of the upper die 2 and the lower die 1 corresponding to the FEP composite layer 4 are provided with grooves, the depth of the grooves is less than the height of the side steps of the steel-lined FEP composite tube sheet after forming, and the grooves are circular grooves for Limit and fix the FEP composite layer and the tube sheet blank.

Preferably, the tube sheet blank 3 is disc-shaped and is a carbon steel substrate.

Preferably, the FEP composite layer 4 of the steel-lined FEP composite tube sheet is a FEP composite material.

As shown in Figure 2-3, the construction process of a tube sheet processing mold includes the following construction steps:

a. Laminate the tube sheet blank and the FEP composite layer. The FEP composite layer consists of two layers. The thickness of the sheet is 10mm. After processing and forming, the end face of the tube sheet with the sheet and the shell of the heat exchanger are connected correspondingly; the thickness of the thick plate is 50mm. , After processing and forming, the end face of the tube sheet with the thick plate is connected to the head of the heat exchanger, which is mainly used for contacting with corrosive materials and exerting its corrosion resistance;

b. The upper and lower templates are clamped to the tube sheet blank and the FEP composite layer by bolts to form a clamp, and then the clamp is sent to the oven for heating;

b1. The oven is evenly heated to 280°C, and the duration is 3h;

b2. The oven is kept at 280℃ for 3h;

b3. The oven continues to heat up to 330°C evenly, and the duration is 2h;

b4. The oven is kept at 330℃ for 5 hours;

c. After sintering in the oven, the FEP pellets are in a semi-molten state, and there is no oxidation and blackening phenomenon. At this time, in order to meet the requirements of molding fluidity, transfer the clamping piece to the molding machine and start the molding work;

c1. Control the molding press to connect the stable pressing plate and start the pressing work;

c2. Pressurize evenly to 80barg/c㎡, during which time is 5h;

c3. The molding machine is kept for 5h under the pressure of 80barg/c㎡;

c4. The secondary pressure is up to 120barg/c㎡, and the duration is 5h;

c5. The molding machine is kept under the pressure of 120barg/c㎡ for 8 hours;

d. When the pressure is maintained until the time is required, the mold can be opened by cooling to normal temperature naturally;

e. Finally, it is the steel-lined FEP composite tube sheet required for the installation of the silicon carbide heat exchanger after finishing by the demoulding lathe.

Embodiment 2

As shown in Figure 2-3, the construction process of a tube sheet processing mold includes the following construction steps:

a. Laminate the tube sheet blank and the FEP composite layer. The FEP composite layer consists of two layers. The thickness of the sheet is 2mm. After processing and forming, the end face of the tube sheet with the sheet and the shell of the heat exchanger are connected correspondingly; the thickness of the thick plate is 5mm. , After processing and forming, the end face of the tube sheet with the thick plate is connected to the head of the heat exchanger, which is mainly used for contacting with corrosive materials and exerting its corrosion resistance;

b. The upper and lower templates are clamped to the tube sheet blank and the FEP composite layer by bolts to form a clamp, and then the clamp is sent to the oven for heating;

b1. The oven is evenly heated to 280°C, and the duration is 3h;

b2. The oven is kept at 280℃ for 3h;

b3. The oven continues to heat up to 330°C evenly, and the duration is 2h;

b4. The oven is kept at 330℃ for 2 hours;

c. After sintering in the oven, the FEP pellets are in a semi-molten state, and there is no oxidation and blackening phenomenon. At this time, in order to meet the requirements of molding fluidity, transfer the clamping piece to the molding machine and start the molding work;

c1. Control the molding press to connect the stable pressing plate and start the pressing work;

c2. Pressurize evenly to 80barg/c㎡, during which time is 5h;

c3. The molding machine is kept for 5h under the pressure of 80barg/c㎡;

c4. The secondary pressure is up to 120barg/c㎡, and the duration is 5h;

c5. The molding machine is kept under the pressure of 120barg/c㎡ for 3 hours;

d. When the pressure is maintained until the time is required, the mold can be opened by cooling to normal temperature naturally;

e. Finally, it is the steel-lined FEP composite tube sheet required for the installation of the silicon carbide heat exchanger after finishing by the demoulding lathe.

The foregoing has shown and described the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above-mentioned embodiments, and the descriptions in the above-mentioned embodiments and the description are only to illustrate the principle of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have Various changes and modifications fall within the scope of the claimed invention. The claimed scope of the present invention is defined by the appended claims and their equivalents.

Claims (6)

1. The tube plate processing die is characterized by comprising a tube plate blank and FEP composite layers clamped on two sides of the tube plate blank, wherein a lower die is arranged on the lower side of the FEP composite layer, an upper die is arranged on the upper side of the FEP composite layer, flange holes are uniformly distributed in the outer edge of the tube plate blank, through holes are formed in the positions, corresponding to the flange holes, of the upper die and the lower die, and the upper die, the lower die and the tube plate blank are fixedly connected through bolts penetrating through the through holes and the flange holes;

and the middle part of the upper die is movably connected with a pressing plate for extruding the FEP composite layer and the pipe plate blank to form the steel lining FEP composite pipe plate.

2. The tube plate processing die of claim 1, wherein the upper die and the lower die are provided with grooves at positions corresponding to the FEP composite layer, and the depth of the groove is smaller than the height of the step on the side surface of the formed steel lining FEP composite tube plate.

3. The construction process of the tube plate processing die is characterized by comprising the following construction steps:

a. the tube plate blank is attached to an FEP composite layer, the FEP composite layer is formed into two layers, the thickness of the thin plate is less than or equal to 10mm, and the end face of the tube plate which is formed by machining and compounded with the thin plate is correspondingly connected with the shell of the heat exchanger; the thickness of the thick plate is less than or equal to 50mm, the end face of the tube plate compounded with the thick plate after processing and forming is correspondingly connected with the end socket of the heat exchanger, and the tube plate is mainly used for contacting corrosive materials and exerting the corrosion resistance of the tube plate;

b. clamping the tube plate blank and the FEP composite layer by the upper and lower templates through bolts to form a clamping piece, and then feeding the clamping piece into a baking oven for heating;

b1, uniformly heating the furnace to 280 ℃, and consuming for 3 hours in the period;

b2, keeping the temperature of the oven at 280 ℃ for 3 hours;

b3, continuously and uniformly heating the oven to 330 ℃, wherein the time is 2 hours;

b4, preserving the heat of the oven at the temperature of 330 ℃ for N hours;

c. after sintering in a baking furnace, the FEP granules are in a semi-molten state and have no oxidation blackening phenomenon, and at the moment, in order to meet the requirement of mold pressing fluidity, the clamping piece is transferred to a mold press to start mold pressing work;

c1, operating the mould pressing machine to connect the stable pressing plate, and starting pressing work;

c2, uniformly pressurizing to 80barg/c square meter, and using for 5 hours in the period;

c3, keeping the mould press for 5h under the pressure of 80barg/c square meter;

c4, pressurizing for the second time to 120barg/c square meter, and using for 5 hours in the period;

c5, maintaining the mould press for N hours under the pressure of 120barg/c square meter;

d. naturally cooling to normal temperature and opening the die when the pressure is maintained for the required time;

e. and finally, carrying out finish machining by a demolding lathe to obtain the steel lining FEP composite tube plate required by the installation of the silicon carbide heat exchanger.

4. The construction process of a tube plate processing mold according to claim 3, wherein the holding time in the step b4 is determined according to different specifications of the molded steel lining FEP composite tube plate.

5. The process of claim 3, wherein the dwell time in the step c5 is determined according to different specifications of the moulded steel lining FEP composite tube plate.

6. The construction process of the tube plate processing mold according to claim 3, wherein the temperature of the clamping piece is reduced by spraying water mist to the mold after the temperature is increased in the pressurizing process of the step c.

Images