CN109453908B

CN109453908B - Spiral nozzle manufacturing process

Info

Publication number: CN109453908B
Application number: CN201910018504.9A
Authority: CN
Inventors: 郝鹏
Original assignee: Shandong Zhongpeng Special Ceramics Co ltd
Current assignee: Shandong Zhongpeng Special Ceramics Co ltd
Priority date: 2019-01-09
Filing date: 2019-01-09
Publication date: 2020-09-04
Anticipated expiration: 2039-01-09
Also published as: CN109453908A

Abstract

The invention discloses a spiral nozzle manufacturing process, wherein the spiral nozzle is a silicon carbide spiral nozzle and has the following indexes: the tolerance of the atomization angle is less than 10 degrees; the tolerance of the inner diameter is +/-1 mm; the dimensional tolerance is +/-1 mm; the surface roughness Ra0.2-1.6. The tolerance range of the atomization angle of the silicon carbide spiral nozzle produced by the invention is reduced from 15-20 degrees to within 10 degrees; through programming and accurate machining, the spiral tangent plane of unified standard has been realized, realize that the surface is level and smooth, orderly arris and angle, and the accurate streamlined design of thick liquid from import to export in the cavity makes the drag coefficient fall to minimum, has reached best effect.

Description

Spiral nozzle manufacturing process

Technical Field

The invention relates to a machining and manufacturing process of a spiral nozzle, in particular to a novel manufacturing process of a silicon carbide spiral atomizing nozzle in a wet flue gas desulfurization device, and belongs to the technical field of nozzle manufacturing.

Background

The inside of the spiral nozzle is an unobstructed channel, and liquid (or slurry) with certain pressure and speed is tangent and collided with a continuously reduced spiral layered interface at a certain angle after passing through the channel, so that the slurry is changed into tiny liquid beads, the slurry is sprayed out from the nozzle in a changed direction to form a fog shape, a layered spraying effect is generated, and the included angle (spiral angle) between the streamline of the conical spraying surface of different layers and the center of the nozzle is gradually reduced. The streamlined design from the inlet to the outlet within the nozzle cavity minimizes the drag coefficient, and thus the helical nozzle is suitable for various industrial applications, such as: chemical industry, environmental protection, electric power, textile and other industrial fields. Silicon carbide (SiC) has the characteristics of high strength, high hardness, wear resistance, corrosion resistance, oxidation resistance, thermal shock resistance, high temperature resistance, high thermal conductivity, low thermal expansion coefficient, high temperature creep resistance and the like, so that the silicon carbide spiral nozzle is widely applied to a Wet Flue Gas Desulfurization (WFGD) device worldwide, and in a limestone-gypsum wet flue gas desulfurization process, the spiral nozzle for spraying limestone slurry in the spray absorption tower is an important factor for controlling the operation efficiency and the maintenance cost of a wet flue gas desulfurization system.

In the spray tower, the flue gas can be washed by spray droplets sprayed from different angles by the desulfurization nozzles when flowing outwards, so that the dust removal and desulfurization effects are effectively achieved. The function of the silicon carbide spiral nozzle is to convert a large amount of limestone slurry into atomized small droplets with sufficient contact area to effectively remove sulfur dioxide (SO) from flue gas₂). The silicon carbide spiral nozzle comprises a connecting part and a spiral part, wherein the spiral part comprises 3 layers with different anglesThe spiral body is formed, after high-pressure slurry with relatively small pressure is used for impacting the section of the spiral body, a multi-layer circular spraying fog drop covering surface can be formed, and the atomization effect is very good. The spiral nozzles with different circular coverage surface sizes and spraying angles can be adjusted by controlling the angle and the size of the spiral body in production. The connecting part mainly comprises the following connecting modes: threaded connection, clamp connection, winding connection and flange connection. According to different connection modes, threads, chucks, flange plates, grooves or bulges and the like are arranged on the periphery of the lower end of the spiral cone as required. Different types of connecting portions are processed on the spiral nozzle in a matching mode, so that the spiral nozzle is convenient to install in different use environments and easy to manage. When in maintenance, the spiral nozzle joint part and the spraying pipeline are only required to be separated to be cleaned and replaced.

The selection and design of the silicon carbide spiral nozzle should take into account several factors:

the processing of the internal channel of the spiral nozzle and the section of the spiral part can realize the process of smooth transition, neat edge and reasonable angle. Because the wet desulphurization process mainly adopts limestone slurry as an absorbent, the factors causing nozzle corrosion, particularly chloride and fluoride, in the flue gas have strong abrasion and corrosiveness. The surface of the spiral nozzle and the surface of the spiral part with unsmooth, uneven and rough edges of the structure transition can not reach the atomization desulfurization dust removal effect in design, and the spiral nozzle is easy to corrode, scale and block, so that the service life is greatly reduced.

The spiral nozzle is special in structure, and the overall strength of the nozzle, the sensitivity to blockage and the success of overcoming mechanical damage such as installation operation, maintenance and the like need to be considered. In the wet desulfurization process, the slurry is generally atomized by a pressure atomization method. The high pressure (2-20 Mpa) is obtained by high pressure, and the high pressure slurry enters from the inlet and impacts after passing through the inside of the joint partOn the rotating part tangent plane, the thick liquid obtains certain rotary motion through the inside and the rotating part of conical nozzle to strike the rotatory tangent plane and strike and form the atomizing droplet, different rotatory tangent planes can form the atomizing region of different angles.

Whether the machining size and the process control of the spiral part spiral body (the number of spiral turns can be 2-5 turns) are strict and accurate, the spiral body which is not standard and smooth cannot have a strict and consistent dispersion inclination angle, and after slurry impacts a spiral tangent plane, uniform atomized small liquid drops cannot be formed, so that the atomization dust removal and desulfurization effects are reduced.

The spiral nozzle has high strength and the connection between the spiral part and the combining part is integrated or combined uniformly. Whether spiral portion and joint portion have dark line, whether joint strength is enough, whether machining tolerance controls to minimumly, directly influences nozzle life, is the very crucial technology in the spiral nozzle production. Under the continuous impact of slurry high pressure, if the joint has dark lines or insufficient strength, nozzle cracks are likely to be caused by continuous corrosion and pressure in the installation and use process, and further slurry leaks, scales and even breaks and falls off.

Whether the machining tolerance of the joint is strictly controlled within a specified range. The processing technology of the joint part is not strictly controlled, the joint part can not be strictly jointed with a spraying pipeline, slurry can be leaked and scaled, loosened, blocked, broken and fallen off in the installation, debugging and use processes, the project period is influenced, the poor spraying effect is caused, and even shutdown maintenance or other serious consequences are required.

On the inner die and the outer die for producing the spiral nozzle,the position and the size of the grouting holes are optimized, and the number of the grouting holes is reduced as much as possible, so that excessive intersecting lines and grouting lines are avoided, and the appearance and the use strength of a product are not influenced. Silicon carbide (SiC), as a typical material in inorganic non-metallic materials and industrial ceramics, is an important branch of the spiral nozzle industry. The silicon carbide spiral nozzle not only has excellent corrosion resistance, but also has high temperature resistance, high hardness and wear resistance, and even if the silicon carbide spiral nozzle is subjected to severe corrosion, high temperature and chemical reagents with extremely strong corrosivity, the atomization nozzle made of the silicon carbide spiral nozzle can also keep the advantages. In terms of the service life, the service time of the reaction sintering silicon carbide spiral nozzle can reach more than 10000 hours, the service time of the nitride combined silicon carbide nozzle is 6000-7000 hours, and the service time of the recrystallized silicon carbide is 5000 hours.

The silicon carbide spiral process is introduced into China in the beginning of the 21 st century and through Germany, the localization of the whole process from raw materials to sintering is basically realized in China, the cost advantage of labor force in China is added, the cost of a silicon carbide spiral nozzle produced by enterprises in China is greatly reduced compared with that of similar products in China and abroad, the increasing attention on environmental protection in China and abroad is combined, the demand of a plurality of industrial fields on high-performance silicon carbide nozzles is increased, and corresponding mechanical equipment is continuously optimized, so that the vigorous development of the silicon carbide nozzles in China is promoted, and a new industry in the field of nozzles is formed. And the silicon carbide ceramic not only has corrosion resistance, high-temperature oxidation resistance, high-temperature strength, small creep property, good heat conductivity, light specific gravity and the like, can bear harsh working environment which is difficult to bear by metal materials and organic polymer materials, and not only can be widely applied to the flue gas desulfurization and dust removal industry, but also the silicon carbide nozzle gradually has more demands in a plurality of industrial fields such as chemical industry, environmental protection, electric power, textile and the like.

As the domestic nozzle processing mechanization level is still a certain gap from the international mechanization level of the upper developed countries, and the foreign countries keep the partial processing technology secret. The technology of the domestic silicon carbide nozzle still needs to be independently researched and developed, and is further promoted. Particularly, with the development of the silicon carbide nozzle market, the finishing call of the market for controlling the size of the domestic silicon carbide nozzle is higher and higher. Due to the high hardness of the silicon carbide material, reprocessing after the sintering of the silicon carbide nozzle is completed is difficult to realize, and is not feasible from an economic perspective. Therefore, the silicon carbide spiral nozzle forming technology is one of the most important technologies in the spiral nozzle manufacturing process. The forming processing of the silicon carbide spiral nozzle is directly related to the final technological level and the atomization effect of the spiral nozzle.

At present, a direct grouting forming method is mainly adopted in China, namely slurry is injected into a gypsum model, a blank body in a product shape is directly manufactured by means of water absorption of the gypsum model, and the product blank is directly fired after being manually overhauled. Because the nozzle needs a certain R angle when being demoulded from the plaster mould, the integral tolerance range of the spiral nozzle is large due to integral forming, and the spiral tangent plane and the conical channel with high precision can not be possessed. And the spiral part and the joint part are processed by the traditional process of manual carving and then pasting and assembling, and the method has the defects of low percent of pass, low precision of the spiral part, large angle tolerance, large manual demand, low strength of the joint and uneven spraying effect.

The whole process of manual work is involved in the forming process, so that products in the same batch cannot reach a uniform size standard. The tolerance range of the atomization angle of the spiral nozzle produced by the method is as high as 15-20 degrees, the sprayed conical spraying layering interfaces cannot be layered obviously, the number of the sprayed conical spraying layering interfaces cannot be more than 3 conical spraying surfaces, the qualified rate of the products in the same batch is lower than 50 percent through spray detection, and the spraying effect is poor. The spiral nozzle can not possess the best stress structure of unified standard, and then can influence the flow angle and the speed of thick liquid in the spiral nozzle, influences spiral nozzle's life, can't realize and promote atomizing SOx/NOx control environmental protection effect in wet flue gas desulfurization device.

Disclosure of Invention

The technical problem to be solved by the invention is to overcome the defects in the prior art, and provide a spiral nozzle manufacturing process to solve the technical defects of low manufacturing process level, high manual participation degree, large tolerance of finished products, low strength of product joint parts, low atomization effect, non-uniform product standards in the same batch and the like in the prior art.

In order to solve the problems, the invention adopts the following technical scheme: the spiral nozzle is a silicon carbide spiral nozzle and has the following indexes:

the tolerance of the atomization angle is less than 10 degrees;

the tolerance of the inner diameter is +/-1 mm;

the dimensional tolerance is +/-1 mm;

the surface roughness Ra is 0.2-1.6.

The following is a further optimization of the present invention to the above scheme: the process comprises the steps of early molding and slip casting, middle machining and post-processing, wherein the slurry used in the steps of early molding and slip casting comprises the following components in parts by weight:

75-85 parts of silicon carbide micro powder, 58-62 parts of softened water, 3.6-4.4 parts of carbon black, 2.7-3.3 parts of carbon fiber, 2.7-3.3 parts of silicon nitride micro powder, 2.7-3.3 parts of metal tungsten micro powder, 2.7-3.3 parts of manganese dioxide powder, 2.7-3.3 parts of titanium oxide powder, 3.6-4.4 parts of dispersing agent and 6.5-7.5 parts of binding agent.

Further optimization: the intermediate machining step comprises the following steps: firstly, machining the shapes of an inner hole and a cone by using a machine tool; secondly, machining a spiral part by using a machine tool; and thirdly, machining the connecting part by using a machine tool.

Further optimization: firstly, machining the inner hole and the cone shape of the spiral nozzle to the tolerance range +/-0.7 mm by adopting a machine tool.

Further optimization: the roughness of the inner hole surface of the spiral nozzle processed in the step I is Ra1.6-3.2.

Further optimization: the surface roughness of the spiral part of the spiral nozzle processed in the second step is Ra1.6-3.2.

Further optimization: and step three, machining the connecting part by adopting a machine tool according to the connecting mode and the size requirement of the connecting part.

Further optimization: the post-processing step comprises the steps of: a. drying in a high-temperature drying chamber, and then loading into a furnace for sintering; b. and (5) sand blasting treatment.

Further optimization: in the step a, the temperature in the high-temperature drying chamber is 80-100 ℃, and the drying time is 8-10 hours.

Further optimization: the sand blasting treatment makes the surface roughness of the product Ra0.2-1.6.

The invention achieves the following beneficial effects:

1. the tolerance range of the atomization angle of the silicon carbide spiral nozzle produced by the process is reduced from 15-20 degrees to within 10 degrees;

2. by programming and accurate machining, a uniform and standard spiral section is realized, flat, smooth and tidy edges and angles of the surface are realized, and the resistance coefficient is reduced to the lowest by the accurate streamline design of the slurry from an inlet to an outlet in the cavity, so that the best effect is achieved;

3. multiple layers of different conical spray surfaces can be arranged according to requirements, spiral nozzles above 3 conical spray surfaces can be produced, and the maximum number of the spiral nozzles can reach 6 conical spray surfaces;

4. the gypsum mold is designed precisely and simply, the influence of the gypsum mold on the shape of a product is reduced, and the problems that the edge R angle of the outline dimension of the product is difficult to demould and the precision is greatly reduced are prevented;

5. the spiral section is machined and manufactured, the size standard of the spiral section is unified, and the product percent of pass is improved from 50 percent to more than 98 percent;

6. the joint of the nozzle joint part adopts an autonomous research and development machining process, so that the mechanical integrated machining of threads, chucks, bolt holes and concave-convex winding lines can be realized, the high-precision machining of the threads, external threads, bolt holes, chucks, grooves and bulges can be realized, the uniformity of a product is better, and the machining precision can be controlled to be 0.1-0.5 mm;

7. the spiral nozzle can be processed by a lathe, so that the structure of the nozzle is more reasonable and compact, the design of a smooth and non-blocking straight-through flow passage without an inner core is realized, and the liquid can reach large flow on a pipeline with a given size;

8. the surface roughness of the product can reach Ra0.2-1.6, which is far lower than Ra3.2 of the existing manual manufacturing technology, and the surface of the product is smoother.

9. The customer uses the detection feedback, when the liquid with certain pressure and speed flows through the spiral nozzle produced by the process from top to bottom, the liquid on the outer layer part of the spiral nozzle collides with the spiral surface with a certain angle, so that the spraying direction is changed to leave the nozzle, the included angle (spiral angle) between the streamline of the conical spraying surface on different layers and the center of the nozzle is gradually reduced, the atomization effect is better, and the service life of the spiral nozzle is prolonged by more than 30% compared with that of the original product.

10. The sintered silicon carbide product produced by the processing method has the advantages that the content of silicon carbide (SiC) can reach more than 92%, the porosity of the product is lower than 0.1%, the product shrinkage ratio is small, the product is not prone to cracking, the product with a special shape can be integrally produced, the product compactness is good, the internal structure distribution is uniform, and the sintered product rate is up to more than 95%.

The following is a comparison of the present invention with the prior art:

drawings

FIG. 1 is a schematic diagram of a blank structure of the present invention in an embodiment using a clip connection;

FIG. 2 is a schematic view of a clip connection of the present invention;

FIG. 3 is a schematic diagram of a blank structure of the present invention in an embodiment using a threaded connection;

FIG. 4 is a schematic structural diagram of a finished product adopting a threaded connection mode in an embodiment of the invention;

FIG. 5 is a schematic structural view of a blank in an embodiment of the present invention using a flange connection method;

FIG. 6 is a schematic structural diagram of a finished product in a flange connection manner according to an embodiment of the present invention;

FIG. 7 is a schematic structural diagram of a finished product in a flange connection manner according to an embodiment of the present invention;

FIG. 8 is a schematic diagram of a blank structure using a winding connection method in an embodiment of the present invention;

FIG. 9 is a schematic diagram of a finished structure of the present invention in an exemplary embodiment using a winding connection;

FIG. 10 is a schematic view of a cutter according to an embodiment of the present invention;

FIG. 11 is a schematic view of a cutter according to an embodiment of the present invention;

FIG. 12 is a schematic view of the structure of a cutter in an embodiment of the present invention.

The invention is further illustrated with reference to the following figures and examples.

Detailed Description

Example 1, a spiral nozzle fabrication process, comprising the steps of:

(1) making inner and outer bottom molds

The method is characterized in that the sizes of an inner bottom die and an outer bottom die in the design of an atomizing nozzle (spiral nozzle) mechanism are used as the basis, the integral structures of the inner bottom die and the outer bottom die are simplified, the integral manufacture of conical bodies and connecting parts (combining parts) of the inner bottom die and the outer bottom die after the structures are simplified is completed by adopting a machining and manual process bonding method, the outer bottom die is made of one of aluminum alloy, gypsum and epoxy resin, and the inner bottom die is made of one of aluminum alloy and gypsum.

(2) Production of outer molds by outer sole molding

The production external mold adopts a plaster mold, an outer bottom mold is uniformly wiped with soapy water, the outer bottom mold is placed in the plaster mold external mold and fixed, gypsum slurry is prepared according to the proportion of 3:2 of gypsum powder and water, the gypsum and the water are fully mixed and then stirred for 1-3 minutes in vacuum, impurities are screened out after the stirring is uniform, the gypsum slurry is injected into the mold, slight oscillation is carried out to remove air bubbles, the gypsum slurry flows into each fine corner, the mold cavity is fully injected with the gypsum slurry at one time, after the gypsum slurry is solidified, the outer bottom mold is removed, the production external mold is obtained, the production external mold made of the gypsum is dried for 3-4 days in a drying chamber with the temperature of 40-50 ℃, weighing is carried out by using an electronic scale, when the water content of the mold is measured to be lower than 10 percent, the mold is further taken out by using a measuring tool to measure the size of the mold, and under the condition that the tolerance of the mold is less, the product can be used.

(3) And manufacturing the mold core

Manufacturing a production inner mold by using the inner bottom mold, and manufacturing a mold core by using the production inner mold;

and manufacturing a core matched with the internal flow passage of the spiral nozzle according to the internal structures of the spiral part and the combining part of the spiral nozzle.

(4) Mixing and slip casting

Before starting up, checking whether a clutch, a brake and the like of the mixer for batching are good, cleaning the mixer barrel to a certain extent without foreign matters, and checking that the insulation and grounding of electrical equipment are kept intact;

when the machine is started for use, the stirrer is started to run in a no-load test mode, and after the machine runs normally, raw materials are added to stir to prepare the slurry, wherein the slurry comprises the following components in parts by weight: 60 parts of softened water, 80 parts of silicon carbide micro powder, 4 parts of carbon black, 3 parts of carbon fiber, 3 parts of silicon nitride micro powder, 3 parts of metal tungsten micro powder, 3 parts of manganese dioxide powder, 3 parts of titanium oxide powder, 4 parts of dispersing agent and 7 parts of binder;

wherein: most of the softened water in the raw materials volatilizes when demoulding and drying are carried out, the dispersing agent and the binder volatilize completely when the temperature is about 1000 +/-10 ℃, and the metallic silicon permeates into the blank body in the high-temperature reaction to react and fill all pores.

The raw materials are added into a stirrer and need to be stirred at a high speed under the working condition that the rotating speed is 850-900r/min, the stirring time needs more than 32 hours, all the raw materials are fully mixed to prepare slurry, and after the slurry is prepared, the slurry is taken out and filtered for later use;

placing the dried mould into a grouting area, adopting a solid grouting method to inject filtered slurry into the mould, during grouting operation, determining the position, the number and the size of grouting holes on a production mould according to the specific structure (the structure of a conical part and a joint part) of an atomizing nozzle, then fixing a mould core into a production external mould, keeping the central lines of the mould core and the production external mould coincident, closing the mould for grouting, reasonably controlling the grouting speed in the grouting process, wherein the grouting speed is about 25-40s/L, ensuring that the phenomena of bubbles, splash and the like cannot be generated during slurry injection, and vibrating the production mould when the slurry is not injected so as to ensure that the slurry flows uniformly.

(5) Drying the mixture

Standing the grouted mould for 40-50 hours, opening the mould, taking out the silicon carbide blank, as shown in figures 1, 3, 5 and 8, demoulding to obtain the blank of the spiral nozzle, naturally drying the blank outdoors for 5-8 hours when the outdoor temperature is above 15 ℃ and the air humidity is less than 70% RH, separating the mold core from the blank (blank) after drying, weighing the blank by using an electronic scale to calculate the predicted moisture content, then sending the blank into an electric heating drying chamber for low-temperature drying, setting the temperature of the electric heating drying chamber to be 30-45 ℃, drying for 40-60 hours, weighing the blank by using the electronic scale, calculating the moisture content, and taking out when the moisture content is less than 5%.

(6) Machining and repairing biscuit

The dry blank is processed by a machine tool processing method, the processing mode is more prominent in the aspect of a spiral nozzle and can be mainly divided into 3 steps:

firstly, processing an inner hole (the inner hole is a hole which is arranged on a blank and used for accommodating a mold core) and a cone shape

Setting the lathe tool stroke of a vertical or horizontal machine tool according to the size of an inner hole and the shape of a cone of a spiral nozzle to be processed, clamping the inner hole of a blank on a chuck of the machine tool after drying, correcting the clamped blank, then installing a special lathe tool of a machine (a machine tool or a lathe) on a tool rest and aligning the tool, further correcting the angle between a lathe tool bit and the axis of the spiral nozzle blank by using a caliper and an angle ruler (a measuring tool) according to the size requirement of the shape of the cone of the spiral nozzle, starting the machine tool, processing the shape of the cone of the spiral nozzle by using a lathe tool 3 (shown in figure 11) with a square structure, continuously measuring the shape and the size of a product by using the tool in the processing process, ensuring that the shape tolerance range of the spiral nozzle blank is within +/-0.7 mm, and visually checking that the surface of the blank has no dark;

then clamping the blank on a chuck of a machine tool through the surface of the conical shape of the spiral nozzle, placing a turning tool on the central line of the conical shape of the spiral nozzle (namely, carrying out tool setting again), further correcting the angle between the turning tool and the axis of the spiral nozzle blank according to the size requirement of the inner hole of the spiral nozzle, starting the machine tool, roughly machining the inner hole of the spiral nozzle through the turning tool, continuously measuring the size of the inner hole of a product by using the turning tool in the machining process, finally ensuring the tolerance range of the inner hole of the blank product to be within +/-0.7 mm, and visually checking that the surface of the blank has no dark grains, damage, air holes and the like;

after the inner hole is machined, the machined inner hole is clamped on a chuck on a machine tool, a turning tool 2 (shown in figure 12) with an arc-shaped corner is replaced, the clamped blank is corrected, tool setting is carried out again, the machining angle and the machining stroke of the turning tool 2 are determined according to the requirement of the overall dimension of the spiral nozzle cone, then the machine tool is started, the spiral nozzle cone is finely machined until the surface is smooth, and a surface roughness comparison sample block (sample block for short) is used for comparing the measured surface of the blank according to vision and touch so as to ensure that the surface roughness is between Ra1.6 and 3.2.

② processing spiral part

The spiral portion is the important component link that atomizes the thick liquid, spray the range size on layer according to the spiral nozzle, spray the number of piles and spray injection angle parameter (the spraying angle can be 60 degrees to 170 degrees), confirm the spiral number of turns that the nozzle need be processed, aperture size and grinding angle, then according to the spiral number of turns that the spiral nozzle need be processed, size of aperture and grinding angle isopize parameter, set up the angle and the tool setting of lathe tool 1 (as figure 10) that one end is the triangle-shaped structure, then control the sectional type processing of can updating through lathe (the later stage is CNC controlling means): grinding to finish the first turn of the spiral part, and then finishing other turns of spiral in sequence, wherein the number of turns of the spiral part is at least 2 turns and can reach 5 turns at most until the size and the angle required by the spiral part are processed, such as common 60 degrees, 90 degrees and 120 degrees;

finally, the turning tool 2 is replaced, the angle of the turning tool 2 is set according to the size and the angle of the spiral part, the tool is set, the product is refined, the size of the product is measured by a straight ruler or a measuring tape continuously in the refining process, the product reaches the optimal theoretical value, namely, the surface roughness is ensured to be about Ra1.6-3.2 by comparing a surface roughness comparison sample block (sample block for short) with the measured surface of the blank, and the best atomization treatment effect of the product is realized; finally, visually checking the surface of the product to be free of burrs, air holes and the like;

③ processing connecting parts (joints)

Common connection modes of the spiral nozzle are shown in fig. 2, 4, 6, 7 and 9, namely clamp connection, threaded connection, flange plate connection and winding bonding, and high-standard finish machining is performed in different modes according to different connection modes;

when the thread is connected, a thread machining process is adopted, a matched tool for machining and thread machining is used, the machining of the connecting part of the spiral nozzle is carried out according to parameters such as the size of the thread, the number of threads, the distance of the thread and the like, and the connecting part and the spiral part are integrally machined and formed, so that the connecting part is more compact, firm and durable, and the proper value is exerted in practical application;

when the flange plates are connected, a flange plate machining process is adopted, a machine tool and a matched turning tool are used for machining according to the parameters of the flange plate such as the outer diameter, the hole center distance, the number of holes, the hole diameter, the flange plate thickness and the like, the product can be molded by adopting an integrated machining or split machining and bonding method with the spiral part, the flange tolerance is small, the precision is high, the standard is unified, the connection part has no tolerance or small tolerance, and the product is more tightly and firmly combined and matched for use;

when the clamp is connected, a machining process of a connecting chuck is adopted, a machine tool and a matched turning tool are used for machining according to data such as the size, the position and the shape of the chuck, and therefore the connecting parts are unified in standard, high in size precision, firm and durable;

when winding connection is carried out, a machining process of the connecting part is adopted, a machine tool and a matched turning tool are used, and machining is carried out according to the position, the size and other data of the groove and the protrusion, so that the connecting part is uniform in standard, high in size precision, uniform in stress, firm and durable;

the groove and the protrusion are located at the lower end of the connecting part of the spiral nozzle, and when the spiral nozzle is produced in a blank mode, the thickness of the connecting part of the spiral nozzle in the axial direction is larger than that of the connecting part after forming, so that the groove and the protrusion can be conveniently machined.

The whole blank is machined to form a formed blank, and then the formed dry blank (biscuit) with the defective surface is trimmed, so that the surface of the product has no air holes, dark lines, damage and the like.

(7) And sintering:

and (2) sending the trimmed molded blank into a high-temperature drying chamber, drying for 10-12 hours at 80-100 ℃, measuring the moisture content of the blank to be less than 2% through the weight change of the blank, putting the blank into a vacuum sintering furnace after the moisture content is measured, pouring metal silicon into gaps and the bottom of a product, wherein the weight of the metal silicon (the purity of the metal silicon is more than 99.5%) which is dispersedly placed is about 1 time of that of the blank of the product, and the weight difference is not more than 25% by weight fluctuation.

Before a vacuum sintering furnace is started, cooling water is firstly communicated, the water pressure of the cooling water is kept between 0.1 and 0.2 Mpa, the water outlet temperature is less than or equal to 45 ℃, the flow of each water valve on the vacuum sintering furnace is adjusted to a proper position, then compressed air is filled into the vacuum sintering furnace, the pressure in the vacuum sintering furnace reaches 0.3 to 0.5Mpa, then a heating process curve is set through a temperature controller (FP23) on the vacuum sintering furnace, and then the vacuum is absorbed by the vacuum sintering furnace, so that the vacuum degree in the furnace is reduced to between 10 and 50 Pa.

Then heating, operating an FP23 heating program, flushing industrial nitrogen (with the purity of more than 99.6%) into the vacuum sintering furnace after the heating is started, opening an exhaust fan and a micro-flushing valve on the vacuum sintering furnace when the vacuum sintering furnace is inflated to a set upper limit (1 +/-0.05 Kpa), adjusting the air inflow of a rotor flowmeter on the micro-flushing valve to be 400 +/-5L/h, giving an alarm when the temperature rises to 800 ℃, automatically closing the micro-flushing valve and the exhaust valve, releasing the alarm on an alarm interface, closing the exhaust fan on a monitoring interface, continuously raising the temperature to 1700 +/-5 ℃, vacuumizing to 50-200pa, and observing the temperature change condition displayed by an infrared thermometer in the hot zone at any time through an observation window on the furnace body by an operator;

when the temperature in the vacuum sintering furnace rises to 1410 ℃, the metallic silicon begins to melt, the metallic silicon continues to melt and generate steam along with the continuous rise of the temperature, the steam is adsorbed and permeated into a silicon carbide blank body, carbon in the blank body reacts with the permeated Si to generate beta-SiC, the beta-SiC is combined with alpha-SiC (silicon carbide micro powder), and free Si fills pores to form a high-compactness ceramic material;

when the temperature reaches 1700 +/-5 ℃, the operation of the heating program is finished, the heating system of the vacuum furnace (vacuum sintering furnace) is automatically closed and stopped, after the constant temperature is waited for 0.5-1.5 hours, nitrogen (with the purity of more than 99.6%) is filled to 1 +/-0.05 Kpa and cooled, when the temperature is lower than 600-700 ℃, the air cooling system on the vacuum sintering furnace can be opened to assist cooling, and after the tapping temperature (below about 150 ℃), the air cooling system is closed to prepare for tapping.

(8) Sand blasting treatment

Cooling the sintered product discharged from the furnace to normal temperature (about 10-45 ℃), separating the sintered product from the silica sand, putting the product into a sand blasting machine, blowing the silica sand to move by using gas generated by a hollow press in the sand blasting machine, enabling the silica sand to be in contact friction with the surface of the product, removing the silicon metal adhered to the surface of the product, enabling the surface of the product to be smooth and clean, and comparing the surface roughness comparison sample block (sample block for short) with the measured surface of the product according to vision and touch to ensure that the surface roughness of the product is Ra0.2-1.6; that is, the surface of the product is free from metal silicon and other visible foreign matters, and then the product is taken out and stored, as shown in fig. 2, 4, 6, 7 and 9, and the product is cleaned to obtain a finished product which can be packaged.

The steps (1) to (5) are the steps of early-stage molding and slip casting, the step (6) is the step of middle-stage machining, and the steps (7) and (8) are the steps of post-processing.

Example 2, in the step (4) of example 1, the slurry comprises the following components in parts by weight: 58 parts of softened water, 75 parts of silicon carbide micro powder, 3.6 parts of carbon black, 2.7 parts of carbon fiber, 2.7 parts of silicon nitride micro powder, 2.7 parts of metal tungsten micro powder, 2.7 parts of manganese dioxide powder, 2.7 parts of titanium oxide powder, 3.6 parts of dispersing agent and 6.5 parts of binder; a silicon carbide nozzle was produced by the process described in example 1.

Example 3, in the step (4) of example 1, the slurry comprises the following components in parts by weight: 62 parts of softened water, 85 parts of silicon carbide micro powder, 4.4 parts of carbon black, 3.3 parts of carbon fiber, 3.3 parts of silicon nitride micro powder, 3.3 parts of metal tungsten micro powder, 3.3 parts of manganese dioxide powder, 3.3 parts of titanium oxide powder, 4.4 parts of dispersing agent and 7.5 parts of binder; a silicon carbide nozzle was produced by the process described in example 1.

The invention achieves the following beneficial effects:

6. the connection part of the nozzle adopts an autonomous research and development machining process, so that the mechanical integrated machining of threads, a chuck, bolt holes and concave-convex winding lines can be realized, and the high-precision machining of the threads, external threads, the bolt holes and the chuck can be realized, so that the product uniformity is better, the stress is more balanced, and the machining precision can be reduced to 0.1-0.5 mm;

8. the surface roughness of the product can reach Ra0.2-1.6, which is far lower than Ra3.2 of the existing manual manufacturing technology, and the surface of the product is smoother;

9. when a client uses detection feedback, when liquid with certain pressure and speed flows through the spiral nozzle produced by the method from top to bottom, the liquid on the outer layer part of the spiral nozzle impacts a spiral surface with a certain angle on the nozzle, so that the spraying direction is changed to leave the nozzle, the included angle (spiral angle) between the streamline of the conical spraying surface on different layers and the center of the nozzle is gradually reduced, the atomization effect is better, and the service life is prolonged by more than 30 percent compared with that of the original product;

The following is a comparison of the present invention with the prior art:

Claims

1. the spiral nozzle manufacturing process is characterized in that: the spiral nozzle is a silicon carbide spiral nozzle and has the following indexes:

the tolerance of the atomization angle is less than 10 degrees;

the tolerance of the inner diameter is +/-1 mm;

the dimensional tolerance is +/-1 mm;

surface roughness Ra0.2-1.6;

the process comprises the steps of primary molding and slip casting, middle-stage machining and post-processing, wherein the middle-stage machining comprises the following steps:

firstly, machining the inner hole and the cone shape by a machine tool:

firstly, clamping an inner hole of a blank piece formed by grouting on a machine tool and correcting, and then starting the machine tool to process the cone shape of the spiral nozzle to the tolerance range +/-0.7 mm;

then clamping the conical shape of the spiral nozzle on a machine tool and correcting, then starting the machine tool to process the inner hole of the spiral nozzle to the tolerance range of +/-0.7 mm, wherein the surface roughness of the processed inner hole of the spiral nozzle is Ra1.6-3.2;

secondly, machining a spiral part by using a machine tool;

1) rough machining: the method comprises the following steps of (1) carrying out sectional machining by adopting a lathe, firstly grinding a first turn of spiral of a spiral part, and then sequentially machining the spiral part of a spiral nozzle according to the sequence;

2) fine modification: adopting a lathe to finish the size of the spiral part of the spiral nozzle to meet the requirements of a drawing, wherein the surface roughness of the spiral part of the processed spiral nozzle is Ra1.6-3.2;

processing the connecting part by using a machine tool:

machining the connecting part by adopting a machine tool according to the connecting mode and the size requirement of the connecting part;

the slurry used in the early molding and slip casting steps comprises the following components in parts by weight:

75-85 parts of silicon carbide micro powder, 58-62 parts of softened water, 3.6-4.4 parts of carbon black, 2.7-3.3 parts of carbon fiber, 2.7-3.3 parts of silicon nitride micro powder, 2.7-3.3 parts of metal tungsten micro powder, 2.7-3.3 parts of manganese dioxide powder, 2.7-3.3 parts of titanium oxide powder, 3.6-4.4 parts of dispersing agent and 6.5-7.5 parts of binding agent;

the post-processing step comprises the steps of: a. drying in a high-temperature drying chamber, and then loading into a furnace for sintering; b. sand blasting treatment, wherein the sand blasting treatment ensures that the surface roughness of the product is Ra0.2-1.6.

2. The spiral nozzle manufacturing process of claim 1, wherein: in the step a, the temperature in the high-temperature drying chamber is 80-100 ℃, and the drying time is 8-10 hours.