SU1219184A1 - Composite mandrel for pilger rolling of tubes - Google Patents

Description

FIG. one

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The invention relates to rolling production, namely to a pipe tool and can be used for hot rolling of pipes in pilger mills.

The purpose of the invention is to reduce the cost of manufacture and increase service life.

FIG. Figure 1 shows the mandrel, longitudinal section; in fig. 2 - core and bandage to plastic deformation.

A mandrel consists of a core 1 with an annular notch 2 on the front part and a shank with a locking element 3 and a band 4.

Making an annular recess on the core, located at a distance from the front end of 0.01–0.20 from the core length, ensures that the defective end of the sleeve freely converges beyond the core during the plastic deformation (rolling) of the band and its subsequent removal, which ensures tool quality, its service life, and allows to use low-cost ingots with a profitable part and, consequently, reduce the cost of tool making as a blank workpiece used in pipe industry . In addition, with such a construction, it is not necessary to accurately determine the dimensions of the original sleeve for the band.

The implementation of the annular recess at a distance from the front end of less than 0.01 from the core length leads to a decrease in the strength of the core section beyond it, and more than 0.20 to a violation of the process of landing (rolling) the bandage.

The geometrical dimensions of the annular recess are determined from the strength conditions of both the core itself and the locking element, in the form of a part of the band projecting with the inner surface, and also on the condition of its high-quality metal filling when the band is fitted.

When the depth and width of the notch is less than 0.025 and 0.10 of the diameter of the core, the strength of the protruding part of the bandage is necessary for fixing, and the loss of the strength of the core occurs more than 0.75 and 1.25.

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The presence between the front end of the annular recess of the core and the hollow section with a width of 0.0001-0.005 of the length of the bandage that mates with it ensures their independent thermal deformation, which significantly reduces the level of temperature stresses in the bandage. The width of the cavity is determined from the condition of unhindered axial elongation of the bandage by the amount of its thermal deformation: with a cavity width of less than 0.0001 of the length of the bandage, the condition of its free deformation is not ensured, and with its width of more than 0.005, the bandage begins to work for axial tension, resulting in to reduce the diameter of its working surface and the rapid failure of a composite tool.

The proposed composite tool is made as follows.

The pretreated core 1 with the shank and the front plate with capacitive 2 being the locking elements is installed in the feed lock. apparatus and is supplied together with a heated sleeve, obtained, for example, on a piercer, and rolls of a piligrim mill, where the process of hot piligrim rolling is carried out.

In this case, rolling is performed in two passes. During the first pass on the outer surface of the sleeve (fig ,, 2) and its front part, corresponding to the width of the annular recess 2, smaller by an amount of 0, OOOl 0.005 of the length of the bandage form a protrusion. The second pass reduces this thickening into the annular recess of the core. . Thus, a composite mandrel is obtained with the required geometric dimensions after heat treatment and machining for size and removal of the front defective end, it is ready for operation.

The proposed mandrel is operated like a solid-forged one. It is installed in the feeding apparatus and fed together with a sleeve put on it in pilgerstan rolls, where the process of hot pilgrim pipe rolling takes place.

In the rolling cycle, the bandage, perceiving the rolling force, due to the presence of the front ring lock in the composite mandrel, works only on the hedgehog, and with its warming up more than the core, it is able to lengthen freely, thereby reducing the dangers that are dangerous to durability. thermal stresses in bandage

In the cooling cycle of the mandrel, when a negative temperature difference is observed over its cross section (m, e, the bandage temperature is lower than the core) due to the presence of a cavity, the bandage can be freely shortened, which reduces the cooling voltage.

So, the proposed design allows to increase the tool life due to a significant reduction in cyclic temperature stresses in the bandage both at the rolling stage and at the cooling stage due to the presence of an annular recess between the bandage and the core, which allows their free thermal deformation, as well as due to the conclusion outside the core of the defective end of the band and its removal, and reduce the cost of manufacturing tool

for use as a bandage blanks. used in pipe industry for low-cost ingots with a profitable part.

Example. Constructive dimensions of the composite mandrel with a band made of steel 25H2MF, designed for rolling pipes of size 326X7 mm.

The composite mandrel has the following geometrical dimensions: length 5500 mm, working surface diameter 0 312 mm, outer diameter of the core 0 230 mm, depth and width of the annular notch of the core, respectively, are 20 and 100 mm. This annular recess is located 250 mm from the front end of the core. The width of the cavity between the band and the core is 5 mm. The diameter and width of the thickened ban. sales are 0 350 and 95 mm.

Preliminary tests of the proposed mandrel design as compared to solid-forged (base object) showed an increase in the service life of the tool by 1.5-1.7 times and a decrease in the cost of its manufacture by 1.9-2.1 times.

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Compiled by L. Maturina. Editor E. Papp Tehred I. Ver. E. Proofreader V. But ha

Order 1187/13 Circulation 518 Subscription of the State Committee of the USSR

for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab ,, d, 4/5

Branch PPP Patent, T. Uzhgorod, ul., Proektna, 4

F1 / 1g2

Claims (1)

COMPONENT DORN FOR PILGRI.MOVA ROLLING OF PIPES containing a core with a shank and a cylindrical outer surface with an annular recess and a bandage connected to the core by plastic deformation, characterized in that, in order to reduce manufacturing costs and increase the service life, the annular recess is made with depth 0.0250.075 and a width of 0.10-1.25 from the diameter of the core and is located from its front end at a distance of 0.0ΙΟ, 20 of its length, while a protrusion is made on the outer surface of the bandage before plastic deformation, respectively corresponding to the location of the recess on the core, but smaller in width _c by an amount of 0.0001 - & 0.005 band length. ^{3 14} g I ^ ZZfZZZzlzZZZZZZZZZZZZZZZZ ^ 7727 /////// 7 ^ 7/1 //// 7 FIG. 1 SU „1219184 1,121