CN103418750A - Spherical valve main body casting technology - Google Patents

Abstract

A spherical valve main body casting technology relates to the technical field of casting. The technology combines an outer layer of open risers, an inner layer of blind risers and an external chill chilling technology and effectively eliminates the shrinkage hole and shrinkage porosity in the production process of thin-walled steel castings, that is, the technology forms a set of complete inner quality control system, thereby effectively solving the following difficult problems of a spherical valve main body caused by structure problems: a casting feeding passage is blocked and consideration cannot be given to feeding of castings at both upper and lower flange parts.

Description

A kind of ball valve main valve body casting technique

[technical field]

The present invention relates to casting technology field, especially relate to a kind of casting technique of hydroelectric facility ZG20Mn carbon steel ball valve main valve body.

[background technology]

Known, due in hydroelectric facility for the needs of the key and particularity of ZG20Mn carbon steel ball valve in environment for use of closing key control, requirement to its main valve body inherent quality is also relatively high, yet, be subject to the limitation of existing Casting Technology, at present China is domestic does not also have a set of unified casting technique in casting field, the ball valve main valve body that is current casting that casting technique is produced can't effectively guarantee that its inherent quality can reach reliable and stable requirement, this has brought hidden danger virtually just to the safe and stable operation of the relevant hydroelectric facility of installing and using this ball valve.

[summary of the invention]

In order to overcome the deficiency in background technology, the invention discloses a kind of ball valve main valve body casting technique, described technique has formed the Control of Internal Quality system of a set of complete unified standard, thereby reach according to described technological requirement, effectively controls the reliable and stable purpose of ball valve main valve body inherent quality.

For achieving the above object, the present invention adopts following technical scheme:

A kind of ball valve main valve body casting technique, described technological requirement is as follows:

(1), process design parameter: reduced scale 1.8%; Bag bore dia: ∮ 70; Sprue: ∮ 100; Cross gate ∮ 80; 50 * 4 * 3 layers of ingate ∮; Pouring temperature: 1560-1570 ℃;

(2), wood-mode technology requires: mo(u)ld bottom half melt pit external mold full pattern, inner chamber core core assembly, out-of-plane is scraped with axle thick stick scraper plate in bottom, the mo(u)ld top half cover core;

(3), rising head setting: rising head calculates by rod-like element, be divided into two-layerly up and down, be positioned at 1.3 times, the upper strata open riser modulus heat-obtaining joint in the outside, be positioned at 1.1 times, inboard lower floor's blind riser modulus heat-obtaining joint, wherein, two place's open risers of corresponding axis hole all calculate modulus by thermal center after placing subsidy;

(4), the rising head subsidy arranges: two place's open risers of corresponding axis hole are divided into subsidy, and the thickness of subsidy need meet the molten steel feeding demand of axis hole bottom thermal center;

(5), external chill setting: all place 200mm between every adjacent two blind riser bottom surfaces thick in the sand external chill; It is thick in the sand external chill that axis hole bottom and axis hole bottom thermal center inner face are placed respectively 100mm, and all place 30mm hard chromium iron ore at each bull nose place; Requirement is placed the thick external chill of 60mm at the valve body lateral wall, and will be placed on being spliced to form around the valve body lateral wall structure of a week by seamless every the sand external chill of axis hole bottom; , between two-layer rising head, manufacture for preventing that the feeding a casting end of centre porosity from appearring in foundry goods, requirement can meet and is not less than 40Kgf/cm simultaneously ²The pressure testing requirement;

(6), moulding points for attention: all external chills all must be in place on request; The inner chamber core must meet the deformability requirement; The whose surfaces reality of will pounding, then require in twice rear thorough oven dry of brush zirconium English coating;

(7), sand mold cast: adopt the ladle refining pouring molten steel, on molten steel, slow watering after die joint, put exothermic shield in open riser;

(8), post processing: foundry goods carries out normalizing+tempering heat treatment by standard-required, after the finishing polishing, does whole magnetic powder inspection, does ultrasonic examination and hydraulic pressure leak test after roughing, all meets the requirements and is finished product.

Owing to adopting technical scheme as above, the present invention has following beneficial effect:

Ball valve main valve body casting technique of the present invention adopts inside and outside two-layer bright, blind riser and external chill chilling technology combine, effectively eliminate Thin-Section Steel Castings shrinkage cavity in process of production, the shrinkage porosite problem, be that described technique has formed a set of complete Control of Internal Quality system, thereby it is obstructed because of the feeding a casting passage that structure problem causes to efficiently solve the ball valve main valve body, the difficult problem that upper and lower flange position feeding a casting can not take into account, this has not only ensured the reliable and stable of ball valve main valve body inherent quality, need to repeatedly repair brought cost burden but also significantly reduced when the heat treatment link is reprocessed and cleared up to foundry goods, and then be that the enterprise that applies this technique has brought good economic well-being of workers and staff.

[accompanying drawing explanation]

Fig. 1 is the schematic diagram of sand mold in the present invention;

Fig. 2 is the B-B rotation generalized section of Fig. 1.

In figure: 1, main valve body; 2, open riser; 3, blind riser; 4, axis hole; 5, external chill.

[specific embodiment]

Can explain in more detail the present invention by the following examples, disclose purpose of the present invention and be intended to protect all changes and improvements in the scope of the invention, the present invention is not limited to the following examples:

Described ball valve main valve body casting technique requires as follows:

(1), process design parameter: technique weight: 9000Kg; Molten steel gross weight 16800Kg; Reduced scale 1.8%; Bag bore dia: ∮ 70; Sprue: ∮ 100; Cross gate ∮ 80; 50 * 4 * 3 layers of ingate ∮; Pouring temperature: 1560-1570 ℃;

(2), wood-mode technology requires: mo(u)ld bottom half melt pit external mold full pattern, inner chamber core core assembly, out-of-plane is scraped with axle thick stick scraper plate in bottom, the mo(u)ld top half cover core, and such wooden model structure can effective secure foundry goods all surface all can meet and polishes the requirement of magnetic powder inspection and place easily external chill;

(3), rising head setting: with reference to accompanying drawing 1, require rising head to calculate by rod-like element, be divided into two-layer up and down, be positioned at 1.3 times of upper strata open riser 2 modulus heat-obtainings joints in the outside, be positioned at 1.1 times that inboard lower floor's blind riser 3 modulus heat-obtainings save, wherein, two place's open risers 2 of corresponding axis hole 4 all require to calculate modulus by the thermal center of placing after subsidizing;

(4), the rising head subsidy arranges: two place's open risers 2 of corresponding axis hole 4 are all divided into subsidy, and the thickness of its subsidy must meet the molten steel feeding demand of axis hole 4 bottom thermal centers;

(5), external chill setting: with reference to accompanying drawing 2, all place 200mm between the bottom surface of every adjacent two blind risers 3 thick in sand external chill 5, thereby effectively prevent that the molten steel between blind riser 3 from the series winding phenomenon occurring; For the MOLTEN STEEL FLOW between blocking-up axis hole 4 and blind riser 3, it is thick in sand external chill 5 that requirement is placed respectively 100mm at the thermal center inner face of axis hole 4 bottoms and corresponding axis hole 4 bottoms, simultaneously, for preventing that sintering from appearring in the molding sand that correspondence is positioned at bull nose, require all to place 30mm hard chromium iron ore at each bull nose place; In addition, require to place the thick external chill of 60mm at corresponding valve body lateral wall, and require the external chill of placing and be placed on forming around the valve body lateral wall loop configuration of a week every the sand external chill of axis hole bottom after seamless splicing; For effectively preventing that the centre porosity phenomenon from appearring in foundry goods, require to manufacture the feeding a casting end between two-layer rising head, require it to meet and be not less than 40Kgf/cm ²The pressure testing requirement, thereby to meet the user;

(6), moulding points for attention: all must be in place on request every the sand external chill; The inner chamber core must meet the deformability requirement; Whose surfaces requires by the ramming reality of pounding, then in twice rear thorough oven dry of brush zirconium English coating;

(7), sand mold cast: adopt the ladle refining pouring molten steel, require to underspeed delay to water during die joint on molten steel, and require the placement exothermic shield in open riser;

(8), post processing: foundry goods carries out normalizing+tempering heat treatment by standard-required, after the finishing polishing, does whole magnetic powder inspection, does ultrasonic examination and hydraulic pressure leak test after roughing, all meets the requirements and is finished product.

Part not in the detailed description of the invention is prior art, therefore the present invention is not described in detail.

Claims (1)

1. a ball valve main valve body casting technique, it is characterized in that: described technological requirement is as follows:

(1), process design parameter: reduced scale 1.8%; Bag bore dia: ∮ 70; Sprue: ∮ 100; Cross gate ∮ 80; 50 * 4 * 3 layers of ingate ∮; Pouring temperature: 1560-1570 ℃;

(2), wood-mode technology requires: mo(u)ld bottom half melt pit external mold full pattern, inner chamber core core assembly, out-of-plane is scraped with axle thick stick scraper plate in bottom, the mo(u)ld top half cover core;

(3), rising head setting: rising head calculates by rod-like element, be divided into two-layerly up and down, be positioned at 1.3 times, the upper strata open riser modulus heat-obtaining joint in the outside, be positioned at 1.1 times, inboard lower floor's blind riser modulus heat-obtaining joint, wherein, two place's open risers of corresponding axis hole all calculate modulus by thermal center after placing subsidy;

(4), the rising head subsidy arranges: two place's open risers of corresponding axis hole are divided into subsidy, and the thickness of subsidy need meet the molten steel feeding demand of axis hole bottom thermal center;

(5), external chill setting: all place 200mm between every adjacent two blind riser bottom surfaces thick in the sand external chill; It is thick in the sand external chill that axis hole bottom and axis hole bottom thermal center inner face are placed respectively 100mm, and all place 30mm hard chromium iron ore at each bull nose place; Requirement is placed the thick external chill of 60mm at the valve body lateral wall, and will be placed on being spliced to form around the valve body lateral wall structure of a week by seamless every the sand external chill of axis hole bottom; , between two-layer rising head, manufacture for preventing that the feeding a casting end of centre porosity from appearring in foundry goods, requirement can meet and is not less than 40Kgf/cm simultaneously ²The pressure testing requirement;

(6), moulding points for attention: all external chills all must be in place on request; The inner chamber core must meet the deformability requirement; The whose surfaces reality of will pounding, then require in twice rear thorough oven dry of brush zirconium English coating;

(7), sand mold cast: adopt the ladle refining pouring molten steel, on molten steel, slow watering after die joint, put exothermic shield in open riser;

(8), post processing: foundry goods carries out normalizing+tempering heat treatment by standard-required, after the finishing polishing, does whole magnetic powder inspection, does ultrasonic examination and hydraulic pressure leak test after roughing, all meets the requirements and is finished product.

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