RU2228811C1 - Roll of tube shaping mill - Google Patents

Abstract

FIELD: plastic metal working, namely manufacture of straight-seam electrically welded tubes. SUBSTANCE: roll of tube shaping mill includes axle supporting stationary mounted members and freely rotating narrow washer of large diameter. Stationary members are mounted on axle by means of pins; they are fixed against horizontal shift by means of flange of axle and lock nut and have cylindrical protrusions engaging one with another and supporting said narrow washer with possibility of rotation at gap between its ends and ends of stationary members consisting 0.05 - 0.10 of thickness of shaped tube. Opening of washer is fit with gap H8/f7; rigidity of working surface of washer exceeds by 10 - 15% rigidity of surface of stationary members. EFFECT: lowered damaging of strip edges and ends of washer at changing width of blank, elimination of beatings, possibility for regrinding roll in assembled state. 1 dwg, 1 ex

Description

The present invention relates to pipe production and can be used in the manufacture of longitudinal welded pipes.

Such pipes are preformed in a multicell mill, similar to roll forming mills, by sequentially bending a strip billet to obtain a closed circular section. The main types of double-roll gauges and rolls for obtaining the above sections are described in sufficient detail, for example, in the book of V.N. Druyana “Production of welded pipes”, “Metallurgy”, 1980. The tube-forming mill necessarily includes a gauge (usually two or three), in which the upper roll contains a middle narrow element (washer), the diameter of which is slightly larger than that of the adjacent ones lateral elements, which does not allow the edges of the flexible section to close, thereby providing the required (to obtain a high-quality seam) gap between these edges. Such a roll is sometimes called a roll with a split washer.

In order to avoid negative phenomena associated with a large difference in speeds between the tool and the workpiece (injury to the surface of the rolls and strip edges), due to a significant difference in current diameters along the height of the caliber, the roll barrels of both tube-forming and roll-forming mills are made of separate elements.

A composite roll of a profile bending mill installed in the line of a pipe welding unit is known, the middle part of the barrel of which is rigidly connected to the axis, and the side flanges rotate freely on rolling bearings, moreover, the flanges are in the form of a truncated cone with a floating support on a needle bearing, and in the bore of the cone with side of its maximum diameter, a 2-row tapered bearing is installed (see US Pat. No. 3757554, class B 21 B 27/08, publ. 11.09.73). A roll forming mill tool is also known, consisting of upper and lower rolls, each of which is made in the form of profile washers and bushings placed on the shaft, moreover, the washers are mounted rigidly on the shaft, and the washers on rolling bearings (see A.S. USSR No. 388811, class B 21 D 5/06, B 21 B 1/08, publ. 14.12.73).

A disadvantage of the known roll designs is the complexity of their design, which increases production costs.

The closest analogue to the claimed object is a roll with a split washer of the pipe forming mill according to US Pat. US No. 3050101, CL 153-54, claimed 03/22/61 and publ. 08.21.62 g.

This roll consists of two halves, between which a distance ring is installed of a slightly smaller outer diameter, on which a narrow (split) washer freely rotates, and the roll halves and the ring are connected on the drive shaft of the cage through bolts.

The disadvantage of this design roll is its relative complexity, as well as insufficient wear resistance, which increases labor costs.

The technical task of the invention is to reduce the cost of the roll, increase its wear resistance and reduce, thereby, the cost of manufacturing electric welded pipes.

To solve this problem, a roll of a pipe-forming mill containing an axis on which fixed elements and a freely rotating narrow washer of a larger diameter are mounted, fixed elements are mounted on an axis on dowels, are fixed from horizontal displacement by an axis flange and a lock nut and are made with cylindrical protrusions in contact with each other, on which a narrow washer is placed with the possibility of rotation with a gap between the ends of it and the stationary elements within 0.05-0.10 of the thickness of the pipe being molded, and this washer hole is made with a fit with a gap of H8 / f7, and the hardness of its working surface is 10-15% more than that of the surface of the stationary elements.

The indicated ratios are obtained as a result of experiments and are empirical.

The essence of the proposed technical solution is to simplify the design of the roll of the pipe forming mill and to optimize some of its parameters, which ensures the fulfillment of the technical task.

Indeed, the known roll contains three elements, bolted together (not counting the axis), and the proposed one - two, fixed by screwing one lock nut. The presence of a horizontal gap between the washer and the stationary elements of the roll allows the first of them to move along the axis by a certain distance, which reduces injury to the edges of the strip and the ends of the washer when changing the width of the workpiece. Empirically found such a ratio of the diameters of the washer hole and the protrusions of the stationary elements, which virtually eliminates its “runout”, making, at the same time, the resistance to rotation of the washer to a minimum, which increases its performance.

In addition, the hardness of the working surface of the washer is made greater than that of the stationary elements, as a result of which its wear (in contact with the edges of the workpiece) becomes comparable to the wear of the stationary elements, which makes it possible to regrow the roll (by wear) in assembled form.

The design of the inventive roll is shown schematically in the drawing.

обеспечивают посадку шайбы с зазором.On the roll axis, fixed elements 3 are installed on the key 2 with a semicircular generatrix of radius R that are in contact with each other along the yy line with cylindrical protrusions 4. From the axial displacement, the elements 3 are fixed by the axis flange 5 and the lock nut 6. The washer 7 freely rotates on the protrusions 4, the outer diameter D is greater than the minimum diameter d of the elements 3 by a predetermined amount. The width “b” of the washer 7 is less than the distance B between the ends of the elements 3 by an amount: B-b = (0.05-0.10) · S, where S is the thickness of the formed pipe. The hardness of the working surface of the washer 7 is 10-15% higher than the hardness of the surfaces of the 8 elements 3. Tolerances on the diameter of the washer hole and the diameters of the protrusions

provide landing of a washer with a gap.

When forming the pipe, the washer 7 controls the gap between the edges of the pipe section, which ensures the proper quality of the weld; while the washer has a peripheral speed equal to the speed of movement of the formed strip.

To disassemble the roll, it is enough to unscrew the nut 6 and remove the elements 3 and the washer 7 from the axis. As shown by experiments (see below), the proposed fastening of the roll elements on its axis is quite reliable at molding speeds of up to 0.8 m / s.

An experimental verification of the proposed roll was carried out on pipe-welding units “20-114”, “10-60”, “40-140” of LLC “Profile-GP” of OJSC “Magnitogorsk Iron and Steel Works”. For this purpose, when forming pipes with an outer diameter of 30-114 mm, the main parameters of the rolls with a split washer were varied, changing the gap for the washer, the type of fit of its hole and the difference in hardness of the washer and the stationary elements. At the same time, the quality of the weld on the pipes, as well as the degree of wear of the working surfaces of the roll, were recorded.

The best results (the maximum duration of the working campaign of the rolls when sorting pipes for low-quality welding is not more than 0.3%) were obtained using rolls of the proposed design.

With a small horizontal gap (<0.05 S), the wear of the washers increased due to a decrease in their peripheral speed relative to the speed of the workpiece, and at B-b> 0.1 S, the quality of the welds deteriorated with a corresponding increase in the sorting of finished pipes.

Reducing the difference in the diameters of the holes of the washers and cylindrical protrusions also led to the braking of the washers with corresponding negative consequences. With an increase in this difference, “breaking” of the washer holes was observed (ie, an increase in their diameters due to beating of the washers in the vertical plane), which reduced the duration of the working campaign of the rolls by 1.2–1.8 times.

With a difference in hardness of washers and fixed elements (material - Art. 9X2MF) less than 10%, wear of washers increased, which led to premature transshipment of the entire caliber; an increase in this difference (in excess of 15%) led to an acceleration of the wear of the surfaces of the cylindrical protrusions of the stationary elements and, as a consequence, to vertical runout of the washers (see above).

A comparative molding of the pipes was also carried out using a roll selected as the closest analogue. The cost of manufacturing such rolls increased by almost 30%, the duration of their working campaign was almost 1.5 times less, and the sorting of poor-quality pipes increased to 0.5%.

Thus, the pilot test confirmed the acceptability of the technical solution found to fulfill the task and its technical and economic advantages over the well-known object (US Pat. No. 3050101).

According to the Central Control Laboratory of OJSC MMK, the use of the inventive roll in the production of straight-seam electric-welded pipes at the plant will reduce the cost of their manufacture by 8-12% with a corresponding increase in profits from their sale.

Concrete example

The pipe forming mill “40-140” contains three stands with split washers with a width of b = 5.30 and 56 mm. Rolls with such washers are made according to the drawing.

The main parameters of the roll:

d _b = 89 mm; the diameters of the roll elements - D = 190 mm;

d = 160 mm; the diameter of the washer hole - d _o = 120 mm;

, что при d_o=120 мм для отверстия означает допуск +0,054 мм, а для вала: -0,036...-0,071 мм (см. стандарт СЭВ 145).its landing on the cylindrical protrusions of the fixed elements - with a gap

that with d _o = 120 mm for a hole means a tolerance of +0.054 mm, and for a shaft: -0.036 ...- 0.071 mm (see CMEA standard 145).

The hardness of these elements is 58 units. HRC; hardness of the working surface of the washers - 1.13x58 = 65.5 units. HRС - (material of elements and washers - Art. 9X2MF).

The diameter (outer) of the pipe being formed is 114 mm, its thickness is 3 mm, i.e. B-b = 0.08 S = 0.08x3 = 0.24 mm.

Forming speed (maximum) - 0.7 m / s.

Claims (1)

A roll of a pipe forming mill containing an axis on which fixed elements are mounted and a freely rotating narrow washer of a larger diameter, characterized in that the stationary elements are mounted on the axis on the dowels, are fixed from horizontal displacement by the axis flange and the lock nut and are made with cylindrical protrusions in contact with each other with a friend, on which a narrow washer is placed with the possibility of rotation with a gap between the ends of it and the stationary elements within 0.05-0.10 of the thickness of the pipe being molded, while TIFA washer configured to fit with a clearance H8 / f7, while its working surface hardness by 10-15% more than the surface of the fixed elements.