RU2308358C1 - Rolled piece breaking method - Google Patents

Abstract

FIELD: machine engineering, namely manufacturing operations for producing piece blanks of rolled material.

SUBSTANCE: method comprises steps of sign-variable bending of end portion of rolled material; performing bending simultaneously in several cross sections in one plane by normalized value in each cross section; changing bending sign in each cross section after axially moving rolled material by one stroke equal to length of divided blank; trimming material fibers during bending process in breaking zone at convex side.

EFFECT: enlarged manufacturing possibilities, improved quality of rolled material breaking.

3 dwg

Description

The invention relates to mechanical engineering, and in particular to technological operations for the production of piece stocks from rolled metal.

A known method of cutting pipe billets from a cylindrical pipe with a cutting tool: a cutter, milling cutter or grinding wheel [1], in which the cylindrical pipe is rotated around its axis, and the tool is moved in the radial direction. The disadvantages of this method are low productivity and high consumption of basic material and tools.

Known methods of breaking the rolled products, in which stress concentrators are preliminarily applied at the fault points, and the fault is carried out by free bending until the workpiece is separated [2, 3, 4, etc.]. The disadvantage of these methods is the low quality of the fault, since with free bending the fault line moves freely between internal defects of the rolled material, as a result of which the fault surface is wavy.

Closest to the technical nature of the claimed invention is a method of breaking the rolling [5] into individual blanks, in which the end section of the rolling is subjected to alternating bending. A rolling section with several stress concentrators deposited on it is placed between two bearing bearings, in the middle between the bearings, the rental section is deformed by a free-rotating roller, and the rolling is allowed to rotate.

The disadvantages of this method are limited technological capabilities, since the method can only be used for the manufacture of round billets, as well as the low quality of breaking, since, firstly, a crack during bending develops freely and passes through the most significant material defects in the bending zone, as a result, the fault surface is wavy, and secondly, under the action of a convex deforming tool in the form of a roller, large contact stresses develop, as a result of which minute contact plastic deformation may occur on the rolling surface.

The objective of the invention is to remedy these disadvantages, namely the expansion of technological capabilities and improving the quality of breaking.

The problem is solved in that in the known method of breaking the rolled into individual billets, in which the end section of the rolling is subjected to alternating bending, the bending of the end section of the rental is carried out simultaneously in several sections in the same plane by a regulated amount in each section, changing the direction of bending in each section is carried out after moving the rolled products in the axial direction by one step equal to the length of the detachable workpiece, and in the process of bending in the fault zone from the convex side, t cropping fiber material.

The main distinguishing features of the invention are the following:

1. The bending of the end section of the car is carried out simultaneously in several sections in the same plane.

2. The value of the bending of rolled products is regulated in each section.

3. The change in the direction of the bend is carried out after each movement of the rolled metal in the axial direction by one step.

4. In the process of bending in the area of stress concentrators from the convex side, the material fibers are trimmed

Since the bending of the end section of the car is carried out simultaneously in one plane, and the change in the direction of the bending is carried out after each movement of the car in the axial direction by one step, breaking is subjected not only to round or pipe rolling, but also to rolling of any other profile, which extends the technological capabilities of the method . In addition, due to this, not a convex but a concave tool is used to deform the rolled products, thereby reducing contact stresses and eliminating the possibility of plastic deformation of the rolled products at the points of contact with the deforming tool. Since bending is each time carried out at a regulated amount, this prevents the possibility of free development of cracks and reduces the waviness of the fracture surface. Since in the process of bending in the plane of the fault on the convex side, the material fibers are trimmed, they thereby direct the fracture into the fracture plane and thereby improve the quality of breaking.

The invention is illustrated by drawings, where figure 1 shows a diagram of the method, figure 2 is a view in cross section in the deformation zone, figure 3 is a view in cross section in the area of cutting fibers of the rolled material.

Rolled 1 in the form of a bar is placed between the upper plate 2 and the lower plate 3 (figure 1 and figure 2). The inner surface of the plates 1 and 2 is made in the form of a semi-cylindrical surface (FIGS. 2 and 3), on the inner surface of the plates a deforming tool is fixed in the form of half rings 4 arranged in increments equal to

Li = 2L,

where L is the required length of the detachable workpiece, and a cutting tool in the form of half rings 5 located between the deformation rings 4 with the same step. The used number of deforming and cutting half rings determines the number of bends of each section of the rolled product at the fault point, and the required number of bends during breaking is determined depending on the required quality of breaking and increases with increasing quality requirements.

The deforming half rings 4 are made with an internal symmetrical conical surface with a cone angle α (Fig. 1), and the cutting half rings 5 have a bulge in the plane of symmetry (Fig. 3), similar in shape to the required shape of the chamfers or roundings of the workpiece, but with a protruding pointed apex. To the convex part of the cutting half-ring uniformly embedded in the surface of the car, it is performed in cross section with a chord length (figure 3) equal to:

and a radius equal to:

where D is the diameter of the rental;

K is the depth of the stress concentrator;

t is the estimated depth of the crack;

h - the depth of introduction of the cutting edge in the material of the material during bending.

The deforming 4 and cutting 5 tools of the upper plate are displaced with respect to the deforming and cutting tools of the lower plate in the axial direction of the rolled products by one step L. The upper plate 2 is oriented relative to the lower plate 3 with two guides 6 (Fig. 2).

Rolled 1 is oriented in the axial direction so that the fault plane coincides with the symmetry planes of the deforming 4 and cutting 5 half rings. A deforming load P is applied to the upper plate 2. Under the action of a deforming load P, the deforming half rings 4 bend the rolling alternately in each fault plane in opposite directions by an angle α, causing the initiation of a fault crack of depth t. In the process of bending rolled products in each plane of the fault from the outside of the bend, the pointed vertices of the convex parts of the cutting half rings 5 to a depth h≤t are introduced, cutting the metal fibers and creating stress concentrators. Thereby, the risk of a significant exit of the fault crack from the fault plane is reduced.

After the deformation, the upper plate 2, together with the deforming 4 and cutting 5 half rings mounted on it, is led upward, the rolled 1 is fed axially one step L. Then, the upper plate 2 is again brought to rolling by the action of the deforming load P 1. The deforming half rings 4 are bent rolled in each plane of the fault alternately in the opposite direction at an angle α, and the pointed tops of the cutting half rings 5 cut the metal fibers at the fault location on the opposite side. The cycle is repeated.

As a result of several bends in opposite directions, cracks in each plane of the fault on both sides propagate deep into the rolled material. To ensure guaranteed separation of the workpiece from the rental, at the end of the upper plate 2, a thrust roller 7 is fixed, which finally separates the workpiece from the rental.

The angle of each next bend of the rolling under the action of deforming half rings 4 should ensure the nucleation and development of a fracture fracture and therefore it is determined by the formula:

where W _i is the axial moment of resistance of the rolled section at the location of the fault relative to the main axis;

J _i is the axial moment of inertia of the cross section of the rolled product at the fault point relative to the main axis;

E is the elastic modulus of the rolled material;

[σ] is the tensile strength of the rolled material.

The values of the values of W _i and J _{i are} determined taking into account the presence of pre-applied stress concentrators at the rental and the presence of fracture cracks that appeared during previous bends. In particular, for round hire

where t _i-1 is the total value of the cracks formed on the previous i-1 bends of the rolling stock in this section (on the first bend t ₁ = 0).

With the next rolling deformation in the same section, but in the opposite direction, for the crack to develop, as follows from the above formula, a large strain value is required, since the initial depth increases by:

So that the crack does not strictly deviate from the plane of the fault, it should be cut by this amount during breaking, but taking into account the permissible roughness of the surface of the fault and the fact that the cutting edge of the cutting half ring 5 bends around the rolled surface (Fig. 3) and directs the propagation of the crack for the most part the circumference in the plane of the fault, the depth of its penetration into the surface of the rolled product makes the size of the crack less.

In order to increase the effectiveness of breaking the rolled products, the bending angle of the rolled products in each section must be gradually increased from the first bend by an angle α to the last by an angle, after which the billet is separated from the rolled products. In addition, it is necessary at each next bend to increase the depth of introduction of the cutting edge of the cutting half ring 5 into the surface of the car by an amount that ensures the required quality of breaking.

A numerical example. Let D = 32 mm, L = 53 mm, E = 21000 kg / mm ² , [σ] = 73 kg / mm ² . The maximum crack depth is taken to be t = 9 mm, and the maximum penetration depth of the cutting edge of the cutting sleeve into the rolled surface is equal to h = 6 mm. Then the angle of the first bend of round steel should be equal to:

which corresponds to 0.4 degrees. We take the angle of the first bend equal to α = 0.5 °. Subsequent bending angles are gradually increased until the crack propagates to a depth of 9 mm. This corresponds to a bend angle of 1.1 degrees. If we want to break the rolling in four bends, then the second bend should be equal to 0.7 degrees, the third - 0.9 degrees, and the fourth - 1.1 degrees.

Based on the maximum crack depth of 9 mm, determine the chord length and the radius of the cutting edge of the cutting sleeve 5 at the last bend:

The depth of introduction of the cutting edge of the cutting half rings is gradually increased: at the first bend it is taken equal to 1.5 mm, at the second bend - 3 mm, at the third bend - 4.5 mm, and at the fourth bend - 6 mm. In order to optimize the breaking process with a large number of bends, the radius R and the length of the working chord b of the cutting edge of the cutting bushings should be determined using the above formulas for each bend. But since in our case the number of bends is small, then for all cutting bushings we accept the same geometric parameters of the cutting edge. Finally, the workpiece is separated from the rental roller 7 (figure 1).

The technical and economic effectiveness of the proposed method of breaking the rolling is as follows:

1. The technological capabilities of the method are expanding, since it becomes possible to break the car with any cross-sectional shape.

2. The quality of breaking increases, since the contact area of the deforming tool with rolled products increases and thereby prevents the possibility of deformation of rolled products in places of contact with the tool.

3. The quality of the fault surface increases, since the crack during the fault is covered and guided by the cutting edge.

4. The breaking performance increases, since each bending of the rolled products in the zone of the stress concentrator is accompanied by the occurrence and development of a fracture crack, while the existing methods use a long multi-cycle loading until a fatigue crack appears.

Information sources

1. Reference technologist-machine builder. In 2 vols. T.2 / Ed. A.G. Kosilova and R.K. Meshcheryakova. - M.: Mechanical Engineering, 1986. S. 64-65 and 292-293.

2 A.S. No. 1180186 of the USSR. MKI B23D 21/00. The way of breaking the car / Timoshchenko V.A. and Kirilovsky V.V. - 4 p. ill.

3. A.S. No. 810402 of the USSR. MKI B23D 31/00. Method for breaking rolled products and device for its implementation / Vysotsky, Cant. - 2 p. ill.

4. A.S. No. 16116006 of the USSR. MKI B23D 31/00. The way of breaking the car / Timoshchenko V.A. - 2 p. ill.

5. A.S. No. 1292946 of the USSR. MKI B23D 31/00. The way of breaking the car / Timoshchenko V.A. and Kirilovsky V.V. - 2 p. ill.

Claims (1)

The method of breaking the rolled products into separate billets, in which the end section of the rental is subjected to alternating bending, characterized in that the bending of the end section of the rental is carried out simultaneously in several sections in one plane by a regulated amount in each section, the change in the direction of the bend in each section is carried out after the rental is moved to axial direction by one step equal to the length of the workpiece to be separated, and in the process of bending in the fault zone from the convex side, the material fibers are trimmed la

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