CN1215763A - Galvanizing method and special equipment for malleable iron pipe fittings - Google Patents

Abstract

The invention discloses a galvanizing method and special equipment for a malleable cast iron pipe fitting, belonging to the technical field of casting. The method mainly comprises the process steps of sand cleaning, hot water washing, acid washing, cold water washing, solvent treatment, drying, dip plating, cooling and the like, wherein in the galvanizing procedure, the workpiece is dipped and plated in the zinc liquid for 30-50 seconds under the condition that the temperature of the zinc liquid of special equipment is 443-470 ℃, and then the galvanizing procedure operation of the cast iron pipe fitting can be completed. The zinc solution is prepared from 50 parts of zinc ingot, 0.1 part of aluminum ingot and 1 part of lead ingot.

Description

Galvanizing method and special equipment for malleable iron pipe fittings

The invention relates to the field of casting technology, in particular to the field of galvanizing of malleable cast iron pipe fittings.

At present, the production process of malleable iron pipe fittings in our country is outdated, especially the galvanizing process of pipe fittings has been produced under the conditions of the old process. Use a large cast iron pot. The zinc liquid in the pot should reach a temperature range of 580-620°C. The lower end of the pot is heated with coal. Under the pressure of the zinc liquid in the pot, not only the service life of the pot body is short, but also the qualified rate of galvanizing pipe fittings has been hovering between 75-80%, which seriously affects the production efficiency. Therefore, the galvanizing process of malleable iron pipe fittings has always been a bottleneck in the malleable iron industry. For the neck process, the temperature of hot-dip galvanizing at around 600 °C has long been considered an unbreakable forbidden zone in the malleable iron and steel industry. As recorded in the book "Hot-dip Galvanizing Technology" edited by Comrade Chen Houzai published by Shanghai Jiaotong University Press in January 1994, from the fifth to last third line on page 355: "C, Si and other contents are higher than those of steel parts, and the microstructure is also different, ..., and when plating malleable cast iron, it must reach about 600 ° C." The book also stated in the 7th to 10th lines on page 357 It is recorded that "malleable iron castings are prone to brittleness after hot-dip galvanizing. This is because heating in the temperature range of 450-600 ° C is just in the range of its brittleness..., so generally adopted to avoid this This is why the galvanizing temperature is usually specified in the range of 610-620°C.”

The purpose of the present invention is to improve the deficiencies in the prior art, and provide a low-temperature galvanizing process and special equipment to improve production efficiency and first pass rate, and reduce labor intensity.

The purpose of the present invention is achieved in this way, a method for galvanizing malleable iron pipe fittings, the method comprises the following steps in turn: sand cleaning, hot water washing, pickling, cold water washing, solvent treatment, drying, dipping, cooling; sand cleaning It is to place the pipe fittings to be galvanized in the polishing machine and use φ1.2-1.8 mm steel sand to remove surface impurities; hot water washing is to immerse the sand-cleaned pipe fittings in hot water at 65-100°C to wash off the iron powder of the workpiece itself and its impurities; pickling is to pickle the pipe fittings after hot water washing in a solution of 0.2-0.5% hexamethylenetetramine in hydrochloric acid with a concentration of 15-25%, and the time is 1-3 minutes ; Cold water washing is to place the pickled castings in a drum, and rinse them continuously in circulating water (natural water temperature) for 2-5 minutes, and dry the water after washing; solvent treatment is the pre-galvanizing treatment of workpieces. It is to immerse the workpiece washed in cold water into a solution of 550-750 grams of zinc chloride and 40-90 grams of ammonium chloride per liter of water, and in the range of solution temperature 50-90 ° C, 1-2 Minutes; drying is to turn the workpiece soaked in solvent up and down on a drying plate at 250-300°C to dry its moisture; dipping is to immerse the dried workpiece in a zinc solution with a temperature of 443-470°C for 30- 50 seconds, the zinc liquid preparation ratio is: 50 parts of zinc ingot, 0.1 part of aluminum ingot, 1 part of lead ingot; cooling is to cool the galvanized pipe fittings with cold water and then dry the water.

In order to achieve the purpose of the present invention, the special equipment for implementing the method is mainly composed of a pot body and a heating body for heating the pot body. Above the insulation layer, the skirt of the pot body is sealed with the insulation layer, and there is a cavity between the outside of the pot body and the inside of the insulation layer, and a protective layer is fastened to the outside of the insulation layer; There is a through hole connected with the cavity, the fuel injection nozzle is fixed in the through hole through the fastener of the protective layer, and the outer end of the fuel injection nozzle is fixedly connected with a valve, a booster pump and an oil storage tank; The insulation layer and protective layer on the same end face of the oil nozzle are provided with grooves and circulation wind tunnels, and a circulation fan is fixed in the grooves; a temperature display mechanism is installed in the cavity,

Compared with the prior art, the present invention has the following positive effects: one is because the present invention adopts the low-temperature galvanizing process, thereby the first pass rate of galvanized workpieces is increased from 75-80% in the prior art to more than 95%, thereby The production efficiency is greatly improved, and the labor intensity of repeated operations of the production workers is reduced; the second is that the special equipment for the low-temperature galvanizing process adopted in the present invention is heated from the side of the pot body, and the circulation fan planed the inner side cavity of the pot body. The heating is uniform, the pot body is heated evenly, the temperature of the zinc liquid is easy to control, and the service life of the pot body is long. The one-time pass rate of zinc workpieces creates conditions.

A galvanizing method and special equipment for malleable iron pipe fittings of the present invention are provided by the following drawings and examples.

Fig. 1 is a structural schematic diagram of special equipment for a method of galvanizing malleable iron pipe fittings according to the present invention.

Fig. 2 is a sectional view along A-A of Fig. 1 .

Example 1

A method for galvanizing malleable cast iron pipe fittings, the method includes the following steps in sequence: sand cleaning, hot water washing, pickling, cold water washing, solvent treatment, drying, dipping, cooling; sand cleaning is to place the pipe fittings to be galvanized in a polished Use φ1.2-1.8mm steel grit to remove surface impurities in the machine; hot water washing is to immerse the sand-cleaned pipe fittings in hot water at 65-100°C to clean off the iron powder and impurities of the workpiece itself; The pipe fittings after hot water washing are pickled in a solution of 15-20% hydrochloric acid and 0.5% hexamethylenetetramine for 2-3 minutes; cold water washing is to put the pickling castings in In the drum, rinse continuously in circulating water (natural water temperature) for 2-5 minutes, and dry the water after rinsing; solvent treatment is the pre-galvanizing treatment of workpieces, which is to immerse workpieces washed in cold water into Add 550 grams of zinc chloride and 40 grams of ammonium chloride solution per liter of water, and the temperature of the solution is within the range of 75-90 ° C, and the time is 1.5-2 minutes; drying is to put the workpiece soaked in solvent at 250 The -300°C drying plate is flipped up and down to dry its moisture; dip-plating is to immerse the dried workpiece into the zinc liquid in the pot under the condition of its special equipment, and in the zinc liquid with a temperature of 443-460°C In 40-50 seconds, the zinc liquid preparation ratio is: 50 parts of zinc ingot, 0.1 part of aluminum ingot, 1 part of lead ingot, and 0.1 part of rare earth aluminum; cooling is to cool the galvanized pipe fittings with cold water and then dry the water.

Example 2

A method for galvanizing malleable cast iron pipe fittings, the method includes the following steps in sequence: sand cleaning, hot water washing, pickling, cold water washing, solvent treatment, drying, dipping, cooling; sand cleaning is to place the pipe fittings to be galvanized in a polished Use φ1.2-1.8mm steel grit to remove surface impurities in the machine; hot water washing is to immerse the sand-cleaned pipe fittings in hot water at 65-100°C to clean off the iron powder and impurities of the workpiece itself; The pipe fittings after hot water washing are pickled in a solution of 20-25% hydrochloric acid and 0.2% hexamethylenetetramine for 1-2 minutes; cold water washing is to put the pickled castings in In the drum, rinse continuously in circulating water (natural water temperature) for 2-5 minutes, and soak in water after rinsing; solvent treatment is the pre-galvanizing treatment of workpieces, which is to immerse workpieces washed in cold water into Add 750 grams of zinc chloride, 90 grams of ammonium chloride, 2.5-7.5 grams of glycerin, 1.25-3.75 grams of OP ₇ per liter of water, and keep the temperature of the solution in the range of 50-75 °C for 1-1.5 minutes ;Drying is to turn the workpiece soaked in solvent up and down on the drying plate at 250-300℃ to dry its water; immersion plating is to immerse the dried workpiece into the zinc in the pot under the condition of its special equipment. Liquid, in the zinc liquid at a temperature of 460-470 ℃ for 30-40 seconds, the preparation ratio of the zinc liquid is: 50 parts of zinc ingots, 0.1 parts of aluminum ingots, 1 part of lead ingots, and 0.05 parts of rare earth aluminum; The pipe fittings are cooled by cold water and dried up.

In order to reach the implementation conditions of the above two embodiments and realize the specific implementation method of the immersion-plating process, special equipment (see accompanying drawing 1) for implementing the immersion-plating method is specially provided, which is mainly composed of a pot body 1 and a pot body for heating the pot body. The heating body 7 and the flue 5 etc. are composed. The pot body 1 of this special equipment is a cuboid formed by welding 50 mm thick 05F steel plate and arc-shaped plate, and the four right angles are arc-shaped, and the bottom end surface 14 is placed on the insulation layer 3, and the insulation layer 3 It is made of silicon-aluminum refractory bricks. The lower edge of the skirt 13 of the pot body is fastened and sealed with the insulation layer 3. There is a cavity 2 between the outer side of the pot body 15 and the inner side of the insulation layer 3. The protective layer 4 of the steel-concrete structure that the layer and the insulation layer are connected into one; there is a through hole 16 communicating with the cavity 2 in the middle of the end face of the pot body 1 long to the outer cavity 2, and the outer protective layer 4 of the through hole 16 is buried. There are bolt fasteners 17, and the fuel injection nozzle 7 is fixedly connected in the through hole 16 through the bolt fastener 17, and the outer end of the fuel injection nozzle 7 is connected with the valve 10, the booster pump 11, and the oil storage tank 12 accordingly. The insulation layer 3 and the protective layer 4 located on the same end face as the fuel injection nozzle 7 are provided with a groove 19 and a circulation wind tunnel 8, and the circulation fan 6 is fixedly installed in the groove 19 through an expansion bolt 18; There is a flue 5, and a thermocouple 9 is fixedly installed in the cavity 2.

When this special equipment is used for galvanizing pipe fittings, after adding galvanized solid materials according to the zinc liquid preparation ratio, open the valve of the oil storage tank 12, raise the pressure pump 11, open the oil delivery valve 10, and ignite the fuel injection Nozzle 7, the temperature will rise soon in the cavity 2; At this time, the circulation fan 6 is turned on again, so that the wind blown by the circulation fan 6 is circulated in the cavity 2 through the circulation wind tunnel 8 along the groove 19, thereby ensuring The heating temperature of the pot body 1 is uniform. When the zinc liquid in the pot body 1 reaches the required temperature, the operation of the galvanizing process can be carried out; The temperature displayed by the pair 9 is properly adjusted to the valve 10 to reduce or increase the oil intake of the injector 7 to meet the production process requirements.

Claims (6)

1. A method for galvanizing malleable iron pipe fittings, the method comprising the following steps in turn: sand cleaning, hot water washing, pickling, cold water washing, solvent treatment, drying, dipping, cooling; sand cleaning is to place the pipe fittings to be galvanized Use steel grit of φ1.2-1.8 mm in the polishing machine to remove surface impurities; hot water washing is to immerse the sand-cleaned pipe fittings in hot water at 65-100°C to clean off the iron powder and impurities of the workpiece itself; pickling is Pickle the pipe fittings after hot water washing in a solution of 15-25% hydrochloric acid and 0.2-0.5% hexamethylenetetramine for 1-3 minutes; cold water washing is to pickle The finished castings are placed in a drum and rinsed continuously in circulating water (natural water temperature) for 2-5 minutes. After rinsing, the water should be dried; The workpiece is immersed in a solution of 550-750 grams of zinc chloride and 40-90 grams of ammonium chloride per liter of water, and the temperature of the solution is within the range of 50-90 ° C for 1-2 minutes; The solvent-treated workpiece is turned up and down on a drying plate at 250-300°C to dry its moisture; dip-plating is to immerse the dried workpiece in a zinc liquid at a temperature of 443-470°C for 30-50 seconds, and the zinc liquid is prepared The ratio is: 50 parts of zinc ingots, 0.1 parts of aluminum ingots, and 1 part of lead ingots; cooling is to cool the galvanized pipe fittings with cold water and then dry them out. 2. The galvanizing method according to claim 1, characterized in that the solution in the solvent treatment also contains 2.5-7.5 grams of glycerin and 1.25-3.75 grams of OP ₇ per liter of water. 3. The galvanizing method according to claim 1 or 2, characterized in that said zinc solution also contains 0.2% rare earth aluminum. 4. A special equipment for implementing the method according to claim 1, which is mainly composed of a pot body and a heating body for heating the pot body. Above the insulation layer, the skirt of the pot body is sealed with the insulation layer, and there is a cavity between the outside of the pot body and the inside of the insulation layer, and a protective layer is fastened to the outside of the insulation layer; There is a through hole connected with the cavity and a fuel injection nozzle, and the outer end of the fuel injection nozzle is fixedly connected with a valve, a pressure pump and an oil storage tank; Groove and circulation wind tunnel, and a circulation fan is fixed in the groove; a temperature display mechanism is installed in the cavity. 5. The special equipment according to claim 4, characterized in that the four corners of the rectangular parallelepiped pot are arc-shaped. 6. The special equipment according to claim 4 or 5, characterized in that the cuboid pot body is welded with 05F steel plate.

Images