RU1811926C - Method of manufacture of elongator mandrels - Google Patents

Abstract

Usage: in the manufacture of pipe rolling tools, in particular mandrels for rolling pipes. The essence of the invention: the preform is molded with a cavity whose dimensions correspond to the final dimensions of the cavity in the working area of the finished mandrel, and in the calibrating and tail zones of the mandrel preform, the diameter of the cavity is cast equal to the maximum inner diameter of the finished mandrel, and the calibrating and tail zones of the mandrel preform are cast with an outer diameter, equal to 1.10-1.50 of the final diameter of the calibrating zone of the mandrel. Then the preform is heated and the technological insert is introduced into the cavity to a depth equal to the length of the calibrating and tail zones and with a diameter equal to the inner diameter of the tail zone of the finished mandrel. After that, the workpiece is deformed in the section of the calibrating and tail zones in the radial direction of deformation of the calibrating and tail zones of the mandrel and the process insert is pulled. 2 ill., 1 tab. Caiish

Description

The invention relates to ferrous metallurgy and can be used in the manufacture of a tube rolling tool, namely mandrels for rolling pipes.

The aim of the invention is to reduce the complexity of manufacturing mandrels with an internal cavity of complex shape and to improve their quality due to the intensive study of the structure of the workpiece.

Fig. 1 shows a water-cooled mandrel that is used for rolling pipes, with finally formed zones — working, calibrating, tail, where Omax is the maximum inner diameter of the finished mandrel; Dx is the inner diameter of the tail zone of the finished mandrel; DK is the outer diameter of the calibrating zone of the mandrel.

Figure 2 shows a cast billet with a technological insert introduced into the cavity, where DH is the outer diameter of the casting equal to (1.10-1.50) DK; C-length of the calibrating zone of the mandrel; LX is the length of the tail zone of the mandrel.

The method is carried out as follows.

The initial billet 1 is cast by casting with the formation of an internal cavity, the dimensions of which correspond to the final dimensions of the mandrel cavity in the working area, and in the calibrating and tail zones of the casting, the cavity diameter is equal to the maximum diameter (Omax) of the finished mandrel. The outer diameter of the gage and tail zones of the workpiece It is cast equal to 1.10-1.50 of the diameter of the gage zone of the mandrel DK.

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The preform thus obtained is heated to the temperature of plastic deformation, the process insert 2 is introduced into the cavity to a depth equal to the length of the gauge and tail zones, with an outer diameter equal to the diameter of the tail zone Dx of the finished mandrel.

Then, the workpiece is deformed in the sections of the gauge and tail zones in the radial direction, forming the final dimensions of the gauge zone (DK) and the tail zone of the mandrel, after which the technological insert is removed from the workpiece by pulling.

The mandrel blank is cast with an outer diameter equal to 1.10-1.50 of the final diameter DK of the mandrel gauge zone. In this interval, during deformation, the required surface quality of the mandrel gauge zone is achieved. If the workpiece is cast with an outer diameter of less than 1.10 of the diameter of the mandrel zone, then the cast structure is poorly worked out during deformation, which leads to a decrease in the quality and durability of the mandrels. In the case of castings with an outer diameter of more than 1.5 the outer diameter of the gauge zone of the mandrel the deformation time increases, the complexity of manufacturing the mandrels increases with a slight improvement in the quality and durability of the mandrels.

Etc. and me r. The mandrel blanks were made of steel 20KHN4FA by electroslag casting in a metal mold. The outer diameter of the casting is 240 mm, the maximum inner diameter is Omax 100 mm, the inner diameter of the tail zone of the mandrel is DX 50 mm.

After removing the billets from the chill molds, they were placed in a chamber heating furnace and heated to a deformation temperature of 1180 ° C. Forging of the castings was also carried out on a hydraulic forging press with a force of 5 MN, equipped with a special four-sided forging device in which the strikers move in the radial direction with respect to mandrel blanks. The process insert is mounted and locked in the clamping head of the manipulator. The mandrel blank heated to the deformation temperature was removed from the furnace, then the technological insert was introduced to a depth equal to the sum of the lengths of the calibrating and tail parts of the blank. Forging was carried out starting from the calibrating zone, forming the outer diameter of the calibrating zone of the mandrel DK equal to 185 mm, while He was 1.30 K. Then the tail zone of the mandrel was forged. In the process of forging calibrating and

tail zones, the inner diameter of the tail zone He is formed, which is equal to the diameter of the technological insert 60 mm. After forging, the mandrels were removed from the obtained preform

technological insert by extrusion.

Similarly, mandrel blanks were formed with boundary and transcendental values of the claimed process parameters (experiments 2-5, see table).

To obtain comparative data

mandrels were made according to the prototype method (experiment 6).

Macro templates and samples for mechanical testing were cut from the prepared blanks. Impact bending of the samples was carried out according to GOST 9454-78. All samples passed the same heat treatment, namely: Tzak. 870 ° С, oil cooling, Т0тп, 400 ° С. The test results are shown in the table.

Analysis of the results of the above tests shows that the complexity of manufacturing elongator mandrels according to the claimed technical solution is 2040% less than the prototype method, and the mandrel resistance is 1.7-1.9 times higher than

the durability of mandrels made by a known method.

Claims (1)

The claims A method of manufacturing elongator mandrels, including casting a hollow billet, its mechanical and heat treatment, characterized in that, in order to reducing the complexity of manufacturing mandrels with an internal cavity of complex shape and improving their quality due to intensive study of the structure, the workpiece is cast with a cavity, the dimensions of which are. the swarm correspond to the final cavity dimensions in the working zone of the finished mandrel, and in the calibrating and tail zones of the workpiece, the diameter of the cavity is cast equal to the maximum inner diameter of the finished mandrel, and the calibrating and tail zone of the mandrel blank is cast with an outer diameter of 1.10-1.50 of the final diameter the calibrating zone of the mandrel, followed by procurement The technological insert is heated, the technological insert is introduced into the cavity to a depth equal to the length of the calibrating and tail zones and with a diameter equal to the inner diameter of the tail zone of the finished mandrel, then the workpiece is deformed in the section of the calibrating and tail zones in the radial direction to form the calibrating and tail zones mandrels, after which the technological insert is removed from the workpiece by pulling.