RU2516139C2 - Method of ring blanks production by bending of steel pipes - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to machine building and can be used for fabrication of steel closed circular chamber filled with carbon dioxide under high pressure and made of steel pipes made from alloyed steels. Pipe is annealed with one end tightly plugged. Pipe is filled with aqueous solution of dichromate with concentration of 3-5 g/l as filler. Pipe with said solution is located in refrigerator chamber to bring said solution in pipes to crystallisation and held said pipes at a temperature for at least one hour. Now, pipe is bent.

EFFECT: higher rotundity in ring blank OD, better operating properties of the assembly and article.

1 ex

Description

The invention relates to mechanical engineering and can be used to make a steel closed annular chamber filled with carbon dioxide under high pressure, which serves to displace powder gases from the channel of the barrel of a tank gun after firing ATGM.

A known method of producing annular blanks of parts of flexible pipes in the cold state using filler on special machines (see "Directory of a young locksmith", E.I. Krupitsky, publishing house "Higher School", Moscow, 1966, p.207-209) . The essence of the method is as follows: they plug the annealed pipe with a stopper, pour fine sand into it, then plug the other end of the pipe and bend it in a cold state using special devices or pipe bending machines.

The disadvantages of the method are as follows:

- the use of sand as a filler for bending alloy steel pipes leads to the formation of corrugations and an unacceptable deviation of the ring blanks of parts from roundness.

A known method of producing annular blanks of parts of flexible steel pipes, which consists in annealing the pipes, closing one end with a hermetic stopper, filling the pipes with filler, followed by flexible. Nitrate melt is used as a filler in pipe bending. Then the pipe is cooled in air. After hardening, nitrate is bent (see “Mednitsky-tin works”, Zavgorodnev PI, Bolotnikov BM Textbook for secondary vocational schools, Moscow, Higher School, 1978, chapter 12, §4 "Filling pipes for bending. Fillers for bending pipes: liquid, free-flowing fusible"). The method adopted for the prototype.

The disadvantages of the prototype is the following: the use of nitrate as a filler gives good results in the geometric dimensions of the ring blanks of parts, however, nitrate:

- toxic, if there is moisture in the pipes, it may be released at the time of filling;

- has a high cost and significant consumption when used as a filler;

- leads to a partial rejection of the ring blanks of parts - “crushing” due to the formation of voids in the pipes when they are filled;

- may adversely affect the reliability of the assembly and the product as a whole with incomplete removal of nitrate from the annular workpiece of the part.

The proposed invention solves the problem of reducing material, labor and energy costs in the production of ring blanks of parts and improving working conditions.

The technical result obtained by carrying out the invention is to strictly comply with the technical requirements for roundness and outer diameter of the ring blanks of parts with a simultaneous increase in the operational qualities of the assembly and the product as a whole.

The specified technical result is achieved in that in the method of producing ring blanks of parts of flexible steel pipes, which consists in annealing the pipes, closing one end of the pipes with a tight stopper, filling the pipes with filler, followed by flexible, it is new that the pipes are filled with an aqueous solution of chromic peak with a concentration of 3-5 g / l, pipes with an aqueous solution of chrompeak are placed in a refrigerator with a temperature of -30 ± 5 ° C, the aqueous solution of chrompeak in the pipes is brought to crystallization and the pipes with filler are held at -30 ± 5 ° C at least one hour.

Technical solutions with features distinguishing the claimed solution from the prototype are unknown and do not follow explicitly from the prior art. This suggests that the claimed solution is new and has an inventive step.

The proposed method for producing ring blanks of parts of flexible steel pipes is implemented as follows.

Alloy steel pipes, for example, 30KhGSA, are annealed to increase ductility. Choke one end sealed with a rubber stopper, the tube is filled with an aqueous solution of potassium bichromate (K ₂ Cr ₂ O _7), a concentration of 3-5 g / l, a pipe with an aqueous solution of potassium bichromate in the refrigerating chamber temperature -30 ± 5 ° C, the aqueous solution was adjusted chrompeak in the pipes before crystallization and withstand pipes with a filler at a temperature of -30 ± 5 ° C for at least one hour. Then produce bending of pipes with a filler on a lathe using a mandrel.

The use of ice as a filler obtained by crystallization of an aqueous solution of chrompick in pipes at a temperature of -30 ± 5 ° C and holding for at least one hour ensures that, when bending, the required dimensions of the ring blanks of parts are obtained in diameter and deviation from roundness. In this case, the particles of dissolved chrompeak act as crystallization centers and provide the formation of the required ice structure. In addition, an aqueous solution of chrompick with a concentration of 3-5 g / l is a temporary protective environment against corrosion.

An increase in the temperature of ice above the established one results in an ellipse that is unacceptable by technical conditions, and a decrease in temperature above the established one can affect the ductility of steel, which will increase the likelihood of cracking during bending of pipes. An hour-long exposure of pipes after ice crystallization at a temperature of -30 ± 5 ° C ensures the stability of the process.

An example of the implementation of the method of producing ring blanks of parts such as a chamber of a flexible steel pipe

Pipes made of steel 30KhGSA, with a diameter of ⌀25 mm and a wall thickness of 2.5 mm are cut into dimensional blanks with a length of 1310 mm. Annealed billets to increase ductility at a temperature of 680-700 ° C for 2 hours. Muffle one end of the measured billet with a hermetically rubber stopper, fill the measured billet with an aqueous solution of chrompeak at a concentration of 3-5 g / l, place pipes with an aqueous solution of chrompeak in a refrigerator with a temperature of -30 ± 5 ° C, bring the aqueous solution of chrompeak in the pipes to crystallization and maintain pipes with filler at a temperature of -30 ± 5 ° C for at least one hour. Then the pipes with filler are bent on a lathe, for which: they fix the mandrel with a stream in the form of a spiral of three turns in a three-jaw chuck, place the workpiece with filler under two rollers located one after another, fixed in the support and having the ability to move in the direction along the mandrel. The end of the measured workpiece is fixed by means of a hook rigidly connected to the mandrel and located above the first coil of the spiral. Turn on the mandrel rotation and produce pipe bending. Upon completion of bending, the free end of the measured workpiece comes out from under the rollers. The obtained flexible spiral from a measured billet consisting of three turns is removed by rotation from the mandrel. Cut the spiral on a milling machine into three turns and get three ring blanks of parts with divorced ends. After the ice melts naturally in air, by turning the ring blanks of the parts, water is drained from their cavity. Then, the obtained ring blanks are heated and hot straightening is carried out in a stamp with a stream having a diametric size equal to the outer diameter of the ring blank of parts 137-138 mm.

Withstand the annular workpiece in the stamp and fix the closure of its ends.

Thus, the proposed method for producing ring blanks of parts of flexible steel pipes ensures their geometric dimensions according to technical conditions, is simple to implement, economical, and has no negative factors affecting the reliability of the assembly and the product as a whole.

Claims (1)

A method of producing annular blanks of parts of flexible steel pipes, including annealing the pipes, closing one end of the pipes with a sealed stopper, filling the pipes with filler and then bending, characterized in that 30KhGSA alloy steel pipes with a wall thickness of 2.5 mm are used, water is used as the filler a solution of chrompeak with a concentration of 3-5 g / l, pipes with an aqueous solution of chrompeak are placed in a refrigerator with a temperature of -30 ± 5 ° C, the aqueous solution of chrompeak in the pipes is brought to crystallization and the pipes are maintained with filler at a temperature of -30 ± 5 ° C for at least one hour.