CN104001844A - Forging process for adopting centrifugal casting hollow ingots to produce ring-shaped parts and cylindrical parts - Google Patents

Abstract

The invention relates to a process for producing ring parts and cylindrical parts by adopting centrifugal casting hollow ingots, which belongs to the technical field of forging. Casting hollow ingot after peeling and flaw detection on the inner and outer surfaces→heating→upsetting the hollow body on a specially designed anvil→heating→elongating the mandrel→heating→upsetting the hollow body on a specially designed anvil→heating→ The mandrel is pulled up to the required size or reamed to the required size. The advantage is that, compared with the widely used forging forming process of solid ingots, this forging forming process has the relative advantages of obviously improving material yield, saving energy and reducing consumption.

Description

Forging Process for the Production of Rings and Cylinders Using Centrifugal Casting Hollow Ingots

technical field

The invention belongs to the technical field of forging, and in particular relates to a forging process for producing ring parts and cylindrical parts by adopting centrifugal casting hollow ingots.

Background technique

Large rings and cylinders are mainly used in important fields such as electric power, construction machinery, and military industry, because the conditions of use are usually relatively harsh, and the performance requirements of the products are extremely high. Typically, large rings and barrels are forged and then machined to form the final product. At present, the method of forging large-scale ring tube parts at home and abroad is mainly to use a solid billet, form a hollow billet after heating, upsetting, and punching, and then elongate or expand the hole to the corresponding size. The disadvantages of this forging method are: (1) more blanks are required, the process flow is lengthy, too many fires, and more energy consumption; (2) the center material of the solid blank is treated as waste in the punching process, and the material yield is low.

Contents of the invention

The object of the present invention is to provide a forging process for producing ring and cylindrical parts by adopting centrifugal casting hollow ingot, which can effectively improve material yield and reduce energy consumption compared with the existing technology.

The present invention is realized in the following way: the casting hollow ingot after skinning and flaw detection on the inner and outer surfaces → heating → upsetting of the hollow body on a specially designed anvil → heating → mandrel extension → heating → on a specially designed anvil Upsetting the hollow body → heating → drawing the mandrel to the required size (or reaming to the required size). The specific process steps are as follows:

(1) Control and analyze the composition of the low-diameter-to-wall ratio centrifugally cast hollow ingot cast by refining molten steel outside the furnace, and perform turning peeling and flaw detection on the inner and outer surfaces. The thickness of the inner surface is 8-10mm, and the outer The surface is skinned 5~10mm, and the two ends of the hollow ingot are machined to form a chamfer of 80°~85°;

(2) After removing the residual oxides in the furnace, place the steel ingot in a weak oxidizing atmosphere that maintains positive pressure in the furnace (the composition of the weak oxidizing atmosphere is: CO ₂ =3-5%, CO=20-40%, H ₂ =28-35%, CH ₄ =1-3%, H ₂ O=10-20%, N ₂ =15-30%) for heating;

(3) Carrying out the heated centrifugal casting hollow ingot on an anvil with a certain taper (cone top angle 160 ° ~ 170 °) can prevent serious instability (such as the diameter of the upsetting drum exceeds 2 times the original diameter) times, or the billet is distorted during the upsetting process), the hollow ingot is upset and formed;

(4) Returning the billet formed by upsetting the hollow ingot described in (3) to the furnace for heating and heat preservation, the heating temperature is 900-1250°C, and the heat preservation time is 0.5-2h;

(5) The billet is out of the furnace, and the mandrel is drawn out. The upper and lower anvils in the drawn out are all V-shaped anvils, which can effectively prevent the generation and expansion of end cracks;

(6) Return the drawn billet of (5) to the furnace for heating and heat preservation, the heating temperature is 900～1250°C, and the heat preservation time is 0.5～2h;

(7) the elongated billet of (6) is released from the furnace, and the anvil is upset for the second time;

(8) Return the upsetting blank of (7) to the furnace for heating and heat preservation, the heating temperature is 900-1250°C, and the heat preservation time is 0.5-2h (;

(9) Take the upsetting blank of (8) out of the furnace, and pull out the mandrel (the upper and lower anvils are selected as V-shaped anvils during the elongation, which can effectively prevent the cracks at the end from expanding) to the required size (or expand the hole to the required size. size).

(10) The forging is air-cooled to room temperature for machining.

The centrifugal casting hollow ingot is a hollow billet with a low diameter-to-wall ratio (outer diameter/wall thickness=2.5-5) and the inner and outer surfaces have been machined and inspected.

Compared with the usual method of forging solid parts and the method of forging hollow bodies using solid ingots, the use of centrifugal casting hollow billets to forge rings and cylindrical parts has the following advantages:

1. Avoid or reduce the problems related to forging large rings and cylindrical parts (such as punching, punching, and folding) through punching and reaming of solid ingots, and can better ensure the quality of finished products;

2. The yield rate of materials is significantly improved, saving a lot of materials;

3. Reduce energy consumption: Since fewer materials are required, energy consumption in smelting, casting, and heating before forging is reduced;

4. Due to the reduction in the weight of the billet, the capacity requirement of the forging press is lower than that of a solid billet.

Description of drawings

Fig. 1 is a process block diagram of the present invention.

Fig. 2 is a schematic diagram of the upsetting of the medium-sized anvil of the present invention. Wherein, upsetting lower anvil 1, centrifugal casting hollow ingot 2, upsetting upper anvil 3.

Detailed ways

Embodiment 1: The present invention will be further described by taking the forging test of a 316LN stainless steel cylinder used in a certain nuclear power plant as an example.

As shown in Figure 1, be the technical process block diagram of the present invention and its implementation example, specifically comprise following process steps:

In the first step, after the chemical composition analysis, peeling of the inner and outer surfaces of the pipe as required, processing of pipe end taper and flaw detection, the centrifugally cast hollow ingot with a weight of about 1045kg and a size of Φ480×115×1000mm is sent into the After removing the residual oxides, the furnace is heated according to the six-stage heating curve (the holding time of each stage decreases and the heating speed increases). The furnace entry temperature is 700°C, and the maximum heating temperature is 1180°C.

The six-stage heating curve refers to: the temperature rise of the cold ingot below 700°C is regarded as the first stage, the heat preservation at 850°C is regarded as the second stage, and the heating from 850°C to 950°C is regarded as the third stage , 950°C heat preservation is regarded as the fourth stage, 950°C to 1180°C heating is regarded as the fifth stage, and 1180°C heat preservation is regarded as the sixth stage. And strictly distinguish the heating specification of the cold ingot and the heating specification of the reheating of the intermediate forging. The maximum heating temperature of the former is 1180 ° C, while the latter is 1160 ° C respectively; the final forging temperature of each fire is 920 ~ 950 ° C.

In the second step, the heated hollow blank with a size of Φ480×115×1000mm (calculated according to the cold state size) is upset on a specially designed anvil with an upsetting ratio of 2.3. The average increase in the inner diameter of the forging after upsetting is 35%, and the size after forging is Φ690×182×435mm.

In the third step, return to the furnace and quickly heat to 1160°C and hold for 0.5 hours; after being released from the furnace, select a mandrel with a nominal diameter of 240mm and draw it to an outer diameter of 538mm. V-shaped anvils are used for the upper and lower anvils in the elongation, which can effectively prevent the generation and expansion of end cracks.

In the fourth step, after reheating out of the furnace, place the hollow part on the specially designed anvil for upsetting with an upsetting ratio of 1.6 to obtain a forging with a size of Φ668×190×435 mm.

The fifth step is to return to the furnace and quickly heat to 1160°C, and keep it warm for 0.5 hours; after being out of the furnace, the elongation coefficient of 1.5 is used to elongate the above-mentioned upsetting piece on a long mandrel with a nominal diameter of 240mm, and the forging size after elongation is Φ546× 153×650mm.

In the sixth step, the forging is air-cooled to room temperature.

The seventh step is to machine the above-mentioned forgings to Φ516×118×550mm.

Embodiment 2: The present invention will be further described by taking the forging test of a 316LN stainless steel cylinder used in a certain nuclear power plant as an example.

In the first step, after the chemical composition analysis, peeling of the inner and outer surfaces of the pipe as required, processing of pipe end taper and flaw detection, the centrifugally cast hollow ingot with a weight of about 1045kg and a size of Φ480×115×1000mm is sent into the After removing the residual oxides, the furnace is heated according to the six-stage heating curve (the holding time of each stage decreases and the heating speed increases). The furnace entry temperature is 700°C, and the maximum heating temperature is 1180°C.

The six-stage heating curve refers to: the temperature rise of the cold ingot below 700°C is regarded as the first stage, the heat preservation at 850°C is regarded as the second stage, and the heating from 850°C to 950°C is regarded as the third stage , 950°C heat preservation is regarded as the fourth stage, 950°C to 1180°C heating is regarded as the fifth stage, and 1180°C heat preservation is regarded as the sixth stage. And strictly distinguish the heating specification of the cold ingot and the heating specification of the reheating of the intermediate forging. The maximum heating temperature of the former is 1180 ° C, while the latter is 1160 ° C respectively; the final forging temperature of each fire is 920 ~ 950 ° C.

In the second step, the heated hollow blank with a size of Φ480×115×1000mm (calculated according to the cold state size) is upset on a specially designed anvil with an upsetting ratio of 2.3. The average increase in the inner diameter of the forging after upsetting is 35%, and the size after forging is Φ690×182×435mm.

In the third step, return to the furnace and quickly heat to 1160°C and hold for 0.5 hours; after being released from the furnace, select a mandrel with a nominal diameter of 240mm and draw it to an outer diameter of 538mm. V-shaped anvils are used for the upper and lower anvils in the elongation, which can effectively prevent the generation and expansion of end cracks.

In the fourth step, after reheating out of the furnace, place the hollow part on the specially designed anvil for upsetting with an upsetting ratio of 1.6 to obtain a forging with a size of Φ668×190×435 mm.

The fifth step is to return to the furnace and quickly heat to 1160°C, and keep it warm for 0.5 hours; after the furnace is released, the punch hole is expanded. Using a punch with a nominal diameter of 318mm, the size of the forging after reaming is: Φ689×185×414mm.

The sixth step is to return to the furnace and quickly heat it to 1160 ° C, and keep it warm for 0.5 hours; after it comes out of the furnace, punch the hole. Using a punch with a nominal diameter of 348mm, the size of the forging after reaming is: Φ716×182×395mm.

In the seventh step, the forging is air-cooled to room temperature.

The eighth step is to machine the above-mentioned forgings to Φ686×147×345mm.

The detailed description and drawings of the above-mentioned embodiments of the present invention are intended to be explained by words and diagrams, rather than to limit the scope of protection of the claims. Various changes in the specific implementation methods described in the description of this application are obvious to those skilled in the art, and are within the protection scope of the claims and their equivalent technologies. Any changes and modifications that do not depart from the claims of the present invention All belong to the protection content of the present invention.

Claims (4)

1. adopt centrifugal casting hollow ingot to produce a Forging Technology for annular element and cylindrical member, it is characterized in that, comprise the following steps:

(1) the low diameter-wall-rate centrifugal casting hollow ingot forming through the casting of external refining molten steel is carried out to constituent analysis, and its surfaces externally and internally is carried out to turning strip off the skin and detect a flaw, the inner surface thickness 8～10mm that strips off the skin wherein, outer surface 5～the 10mm that strips off the skin, the both ends of the surface of hollow ingot are carried out to machined, form the chamfering of 80 °～85 °;

(2) in removing stove, after residual oxide, above-mentioned centrifugal casting hollow ingot is being maintained in the weak oxide atmosphere of malleation in stove and heating;

(3) the centrifugal casting hollow ingot after heating is carried out stopping on the swage block with certain taper the hollow body upsetting formation of serious unstability;

(4) blank of (3) hollow body upsetting formation is melted down to heating and insulation, 900～1250 ℃ of heating-up temperatures, temperature retention time 0.5～2h;

(5) blank is come out of the stove, and carries out core bar drawing, and in pulling, upper and lower anvil is all selected V-type anvil, effectively prevents the expansion that results from of crack on end side;

(6) the pulling blank of (5) is melted down to heating and insulation, 900～1250 ℃ of heating-up temperatures, temperature retention time 0.5～2h;

(7) the pulling blank of (6) is come out of the stove, carry out hollow body upsetting formation for the second time;

(8) blank after (7) jumping-up is melted down to heating and insulation, 900～1250 ℃ of heating-up temperatures, temperature retention time 0.5～2h;

(9) blank after (8) jumping-up is come out of the stove, carry out core bar drawing to requiring size or reaming to requiring size;

(10) forging air cooling to room temperature is carried out machined.

2. technique according to claim 1, is characterized in that: described centrifugal casting hollow ingot is the hollow ingot with low diameter-wall-rate 2.5～5 and surfaces externally and internally process and machined and flaw detection.

3. technique according to claim 1, is characterized in that: the swage block with certain taper described in step (3) is 160 °～170 ° of vertex of a cone angles.

4. technique according to claim 1, is characterized in that: the weak oxide atmosphere described in step (2) consists of: CO ₂=3～5%, CO=20～40%, H ₂=28～35%, CH ₄=1～3%, H ₂o=10～20%, N ₂=15～30%.